The History of Neuroscience in Autobiography

VOLUME 10

The History of Neuroscience in Autobiography

VOLUME 10

Edited by Thomas D. Albright
and Larry R. Squire

Society for Neuroscience

Society for Neuroscience

The Society for Neuroscience publishes works that advance
the understanding of the brain and nervous system.

Copyright © 2018 by the Society for Neuroscience

Published by the Society for Neuroscience
1121 14th Street, NW
Washington, DC 20005
www.sfn.org

All rights reserved. No part of this publication may be reproduced,
stored in a retrieval system, or transmitted, in any form or by any means,
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without the prior permission of the Society for Neuroscience.

Library of Congress Control Number: 96070950

978-0-916110-10-9

Printed in the United States of America

Contents

Previous Contributors

Preface to Volume 1

Preface to Volume 10

Ben A. Barres

Anders Björklund

Thomas J. Carew

Dennis W. Choi

Joseph T. Coyle

Kjell Fuxe

Michael E. Goldberg

Mary Elizabeth Hatten

Steven E. Hyman

Eve Marder

Roger A. Nicoll

S. Murray Sherman

Douglas G. Stuart

Index of Names

Previous Contributors

Volume 1

Denise Albe-Fessard

Julius Axelrod

Peter O. Bishop

Theodore H. Bullock

Irving T. Diamond

Robert Galambos

Viktor Hamburger

Sir Alan L. Hodgkin

David H. Hubel

Herbert H. Jasper

Sir Bernard Katz

Seymour S. Kety

Benjamin Libet

Louis Sokoloff

James M. Sprague

Curt von Euler

John Z. Young

Volume 2

Lloyd Beidler

Arvid Carlsson

Donald Griffin

Roger Guillemin

Ray W. Guillery

Masao Ito

Martin Larrabee

Jerry Lettvin

Paul MacLean

Brenda Milner

Karl Pribram

Eugene Roberts

Gunther Stent

Volume 3

Morris H. Aprison

Brian B. Boycott

Vernon B. Brooks

Pierre Buser

Hsiang-Tung Chang

Claudio A. Cuello

Robert W. Doty

Bernice Grafstein

Ainsley Iggo

Jennifer Lund

Edith and Patrick McGeer

Edward R. Perl

Donald B. Tower

Patrick D. Wall

Wally Welker

Volume 4

Per Andersen

Mary Bartlett Bunge

Jan Bures

Jean Pierre G. Changeux

William Maxwell (Max) Cowan

John E. Dowling

Oleh Hornykiewicz

Andrew F. Huxley

JacSue Kehoe

Edward A. Kravitz

James L. McGaugh

Randolf Menzel

Mircea Steriade

Richard F. Thompson

Volume 5

Samuel H. Barondes

Joseph E. Bogen

Alan Cowey

David R. Curtis

Ennio De Renzi

John S. Edwards

Mitchell Glickstein

Carlton C. Hunt

Lynn T. Landmesser

Rodolfo R. Llinás

Alan Peters

Martin Raff

Wilfrid Rall

Mark R. Rosenzweig

Arnold Bernard Scheibel

Gerald Westheimer

Volume 6

Bernard W. Agranoff

Emilio Bizzi

Marian Cleeves Diamond

Charles G. Gross

Richard Held

Leslie L. Iversen

Masakazu Konishi

Lawrence Kruger

Susan E. Leeman

Vernon B. Mountcastle

Shigetada Nakanishi

Solomon H. Snyder

Nobuo Suga

Hans Thoenen

Volume 7

Floyd E. Bloom

Joaquín Fuster

Michael S. Gazzaniga

Bertil Hille

Ivan Izquierdo

Edward Jones

Krešimir Krnjević

Nicole M. Le Douarin

Terje Lømo

Michael M. Merzenich

John Wilson Moore

Robert Y. Moore

Michael I. Posner

Peter H. Schiller

Gordon M. Shepherd

Robert H. Wurtz

Volume 8

Huda Akil

Philippe Ascher

Giovanni Berlucchi

Lily Jan

Yuh-Nung Jan

Bruce Sherman McEwen

Frederick A. Miles

Peter M. Milner

Fernando Nottebohm

Tomaso A. Poggio

Marcus E. Raichle, Sr.

Pablo Rudomin

Anne Treisman

Stanley J. Watson, Jr.

Anne Buckingham Young

Volume 9

David H. Cohen

Yadin Dudai

Gerald D. Fischbach

Sten Grillner

Jon Howard Kaas

Eric Kandel

Nancy Kopell

Margaret Stratford Livingstone

Giacomo Rizzolatti

Trevor W. Robbins

Wolf Singer

David C. Van Essen

Preface to Volume 1

Before the Alfred P. Sloan Foundation series of books began to appear in 1979, the scientific autobiography was a largely unfamiliar genre. One recalls Cajal’s extraordinary Recollections of My Life, translated in English in 1937 and the little gem of autobiography written by Charles Darwin for his grandchildren in 1876. One supposes that this form of scientific writing is scarce because busy scientists would rather continue to work on scientific problems than to indulge in a retrospective exercise using a writing style that is usually outside their scope of experience. Yet, regard-less of the nature of one’s own investigative works, the scientific enterprise describes a community of activity and thought in which all scientists share. Indeed, an understanding of the scientific enterprise should in the end be accessible to anyone because it is essentially a human endeavor, full of intensity, purpose, and drama that are universal to human experience.

While writing a full autobiographical text is a formidable undertaking, preparing an autobiographical chapter, which could appear with others in a volume, is perhaps less daunting work and is a project that senior scientists might even find tempting. Indeed, a venture of this kind within the discipline of psychology began in 1930 and is now in eight volumes (A History of Psychology in Autobiography). So it was that during my term as president of the Society for Neuroscience in 1993 to 1994, I developed the idea of collecting autobiographies from senior neuroscientists, who at this period in the history of our discipline are in fact pioneers of neuroscience. Neuroscience is quintessentially interdisciplinary, and careers in neuroscience come from several different cultures, including biology, psychology, and medicine. Accounts of scientific lives in neuroscience hold the promise of being informative and interesting, and they could be a source of inspiration to students. Moreover, personal narratives provide for scientists and nonscientists alike an insight into the nature of scientific work that is simply not available in ordinary scientific writing.

This volume does have a forerunner in neuroscience. In 1975, MIT Press published The Neurosciences: Paths of Discovery, a collection of 30 chapters in commemoration of F. O. Schmitt’s 70th birthday, edited by F. Worden, J. Swazey, and G. Adelman. The contributing neuroscientists, all leaders of their discipline, described the paths of discovery that they had followed in carrying on their work. While writing in the style of the conventional review article, some authors did include a good amount of anecdote, opinion, and personal reflection. A second, similar volume, The Neurosciences: Paths of Discovery II, edited by F. Samson and G. Adelman, appeared in 1992.

In any case, neuroscience writing that is deliberately and primarily autobiographical has not been collected before. This project, The History of Neuroscience in Autobiography, is the first major publishing venture by the Society for Neuroscience after The Journal of Neuroscience. The book project was prepared with the active cooperation of the Committee on the History of Neuroscience, which serves as an editorial board for the project. The first chairperson of the committee was Edward (Ted) Jones; its members were Albert Aguayo, Ted Melnechuk, Gordon Shepherd, and Ken Tyler. This group compiled the names and carried out the deliberations that led to the first round of invitations. In 1995 Larry Swanson succeeded Ted Jones as chair of the committee, and as we go to press with volume 1 the committee members are Albert Aguayo, Bernice Grafstein, Ted Melnechuk, Dale Purves, and Gordon Shepherd.

In the inaugural volume of the series, we are delighted to be able to present together 17 personal narratives by some of the true pioneers of modern neuroscience. The group includes four Nobel Laureates and 11 members or foreign associates of the National Academy of Sciences, USA. The contributors did their scientific work in the United States, Canada, England, Australia, France, and Sweden. It is difficult to imagine a finer group of scientists with which to inaugurate our autobiographical series. The autobiographical chapters that appear here are printed essentially as submitted by the authors, with only light technical editing. Accordingly, the chapters are the personal perspectives and viewpoints of the authors and do not reflect material or opinion from the Society for Neuroscience.

Preparation of this volume depended critically on the staff of the book’s publisher, the Society for Neuroscience. The correspondence, technical editing, cover design, printing, and marketing have all been coordinated by the Society’s central office, under the superb direction of Diane M. Sullenberger. I thank her and her assistants Stacie M. Lemick (publishing manager) and Danielle L. Culp (desktop publisher) for their dedicated and skillful work on this project, which was carried out in the midst of demands brought by the first in-house years of the Society’s Journal of Neuroscience. I also thank my dear friend Nancy Beang (executive director of the Society for Neuroscience) who from the beginning gave her full enthusiasm to this project.

Larry R. Squire
Del Mar, California
September 1996

Preface to Volume 10

In this tenth volume of The History of Neuroscience in Autobiography we are pleased to present 13 personal narratives by leaders in our field of science. This stellar group includes six members or foreign associates of the National Academy of Sciences, six members of the National Academy of Medicine, and six past presidents of the Society for Neuroscience. We are particularly fortunate to include a contribution from the late Ben Barres (1954–2017), who pioneered much new territory in his short life.

Collectively, these chapters document the steep rise of a bold venture in biomedical research, as it played out in the late 20th century. Individually, they are treasures, for they are cast in the irresistible and uniquely human form of expression: the story. As such, they connect the dots along paths of scientific discovery, but they also convey the human elements behind those connections, the rich drama and comedy of interpersonal relationships, the sudden flashes of insight, the folly of hubris and the pain of missed opportunities, the beauty of new ideas and the raw excitement of discovery. These are stories populated by imposing and quirky characters, magnified by the lenses of memory and attention. There are tales of brilliance, fantasy, risk, sacrifice, triumph, and camaraderie, but the theme that binds every one of the chapters in this volume is success. Thus, these chapters not only entertain in the way that only good stories can, but they also offer appealing models and nuanced lessons for success in the human side of science for the next generation of vanguards in our field.

It was through Larry Squire’s initiative that this autobiographical series was founded nearly 25 years ago. Beginning with publication of the first volume in 1996, Larry’s interest in history and his devotion to neuroscience have yielded an expanding library of autobiographical chapters. Tom Albright joined Larry as coeditor beginning in volume 9. With the publication of volume 10, the library of chapters now numbers 143. There are many more great stories in the making, of course, as the field of neuroscience bounds ahead, and we look forward to curating them in these pages.

Beginning with volume 8 in this series, the Society for Neuroscience assumed full responsibility for the project. Volume 10 was prepared with the advice of the Society’s Publications Committee, which serves as editorial board for the project. With input from the committee, from the Council of the Society for Neuroscience, and many others, names were compiled for inclusion in this volume. Production was overseen by Suzanne Rosenzweig (director of scientific publications), with project management handled by Jackie Perry (senior publications manager). The contents of the volume will be posted on the Society’s Web site, under the “About SfN” menu tab (https://www.sfn.org/about/history-of-neuroscience), where one can also find the 130 autobiographical chapters that appeared in the first nine volumes. Copies of volume 10 will also be available for purchase. We hope readers will find volume 10 as interesting and useful as the earlier volumes.

Thomas D. Albright and Larry R. Squire
Del Mar, California
February 2018

Ben A. Barres

BORN:

Newark, New Jersey

September 13, 1954

EDUCATION:

Massachusetts Institute of Technology, SB (1976)

Dartmouth Medical School, MD (1979)

Harvard Medical School, PhD (1990)

APPOINTMENTS:

Internship in Internal Medicine, Cornell Cooperating Hospitals (1979–1980)

Residency in Neurology, Cornell Cooperating Hospitals (1980–1983)

Postdoctoral Fellow in Neurobiology, University College London (1990–1993)

Assistant Professor of Neurobiology, Stanford University (1993–1997)

Assoc. Professor of Neurobiology, Stanford University (1997–2001)

Professor of Neurobiology, Stanford University (2001–present)

Vice-Chair, Department of Neurobiology, Stanford University (1998–2007)

Chair, Department of Neurobiology, Stanford University (2008–2016)

Director, Masters of Medicine Program for PhD students, Stanford University (2005–present)

Annexon Biosciences, Inc., Co-Founder and Chairman of Scientific Advisory Board (2011–present)

HONORS AND AWARDS (SELECTED)

Bell Labs Engineering Scholar (1976)

Diplomate, National Board of Medical Examiners (1980)

Diplomate, American Board of Psychiatry and Neurology (1984)

Mika Salpeter Lifetime Achievement Award, Society for Neuroscience (2008)

Alcon Research Institute Award (2010)

American Association for Advancement of Science (2011)

American Academy of Arts and Sciences (2012)

National Academy of Sciences (2013)

National Academy of Medicine (2014)

Gill Distinguished Scientist Award, University of Indiana (2016)

Ralph Gerard Prize, Society for Neuroscience (2016)

Grundke-Iqbal Award, Alzheimer’s Association (2017)

Stanford University President’s Award for Excellence through Diversity (2017)

Helis Award for Parkinson’s Disease and Neurodegenerative Research (2017)

The work of Ben Barres has enriched our understanding of the active roles of central nervous system glial cells in health and disease.

Ben A. Barres

I have not yet retired but was diagnosed about two years ago, at the age of 61, with advanced pancreatic cancer. Although this is generally considered one of the most aggressive and least treatable of cancers, thanks to recent medical advances, I am fortunate to still be working every day. Surprisingly cancer has had an upside. It allowed me to shed many time-consuming activities such as being department chair, being on endless committees and editorial boards, grant writing, teaching, and traveling to meetings. It suddenly became easy to say no to all these things without guilt so that I could focus on the things I really wanted to accomplish before my time runs out. What was left was all the very best parts of being a scientist, running a lab, and mentoring young scientists. I am grateful for this opportunity to write about my life. I would like to tell you what a privilege it has been to be a scientist and to mentor young scientists. I also would like to tell you about my experiences as a female scientist, then as a transgender scientist, and how my differences may have contributed beneficially to my path in science. Finally, I would like to tell you about glial cells, what we know as well as what we don’t know, and the great adventure it has been to explore their roles in healthy and diseased brains.

Growing Up

I was raised in West Orange, New Jersey. My family was not financially well off. There were four of us kids, so my mom spent her time raising us, while my dad worked as a salesman, first of baby furniture and later of liquor. My mother came from a Lithuanian Jewish family and my dad came from an Italian Roman Catholic family. Neither of my parents attended college. But my mom was highly intelligent, and she expected that her kids would do well in school and attend college. As a woman, she had been forced in high school to take the “secretarial” track. But when all of her kids had grown up, she enrolled at a local college, Rutgers, and started working toward a mathematics degree. Sadly in only her mid-forties she passed away from breast cancer, a familial curse caused by a BRCA2 mutation, which I also inherited. She never lived to see how her kids did as adults, but she would have been proud. My fraternal twin sister Jeanne became a pediatrics nurse practitioner, my brother started a successful insurance company, I (Barbara) became a scientist, and my younger sister became a legal secretary. All of my siblings married and had children; I was the outlier in that regard, as I will come to.

My mom was not particularly compatible with my father, but they stuck it out for the good of us kids. Although there were many times when my parents struggled financially to make ends meet, we never lacked for basic necessities. Looking back on it, my mom never seemed very happy and she was often irritable. I suspect this was due to both undiagnosed severe obstructive sleep apnea—another familial curse—as well as the constant absence of my father. When he was not working, which was most of the time, he was either with his “second wife” (who we only learned about after my mom died) or was out with his friends gambling, playing cards, or betting on ponies. From my mother, I inherited intelligence, the BRCA2 mutation, and sleep apnea, and from my father an addictive tendency, not for gambling but for doing research.

My parents apparently agreed when they married that their kids would be raised in the Roman Catholic religion, and we learned only after my mom died that she had been Jewish. I do not know why she did not tell us this, but undoubtedly she wished to shield her kids from anti-Semitism. So in grade school, every Monday after school we would be bussed to a local church for religious indoctrination and forced to attend mass at church every Sunday. Even in grade school, I recognized that what I was being taught about God was not supported by evidence, was internally inconsistent, and made no sense. But I dared not upset my mom who insisted that knowledge of right and wrong could come only from religion, an idea that deeply offended me then and now. When I was about 14 years old, I finally got up the courage to refuse to go to church anymore and informed my parents that I was an atheist. In response, my mother ordered my dad to beat me, which he did (this was the only time that he did this), and I ran away from home for a brief period to escape the beating. When I returned home, my mom informed me that until I started going to church, I must stay in my bedroom all day every Sunday without food. Needless to say, every Saturday I would stock up my room with things to do and with food. Fortunately, after a few months, my mom relented and life resumed as normal.

I agree with those who have argued that it is a great crime to indoctrinate children with religious beliefs. It is always surprising to me that childhood religious indoctrination seems to stick lifelong for most people. For many kids, this indoctrination must exert a powerful influence on the developing brain. Children not only quickly absorb knowledge but somehow must learn to neglect or not see the internal inconsistencies between actual facts and the fictions they are being taught. I wonder if such childhood indoctrination, by irreversibly affecting brain development, might have permanent effects on cognitive development, perhaps even impairing scientific thinking ability in later life.

One of the great pleasures of growing up was having endless time to read. My mom would take us to the West Orange Public Library once a week, and we were allowed to take out two books, a limit that constantly annoyed me. Science was an early interest. At the age of four or five years old, my twin sister decided she wanted to be a nurse and I decided I wanted to be a scientist, and that is what we did. I do not know why I was interested in science at such a young age, as I did not know any scientists and hardly had any concept of what science was. But somehow I had the idea that science was something fun. Perhaps it was because I liked to watch the show “Superman” on television that had a mad scientist who was always making fascinating concoctions and inventions. Perhaps that is why I thought I might someday be a chemist. My favorite childhood toys were chemistry sets and microscopes.

Unfortunately from grade school onward it always seemed to me that public school moved at a very slow pace. Fortunately, I had a marvelous science teacher in eighth grade, Jeffrey Davis. One of the best teachers I had in public school, he was full of passion for teaching. He made science discovery seem like incredible fun, and I wanted to be in on it. I recall that we read the Voyage of the Beagle by Charles Darwin and also the Double Helix by James Watson, a book I have since read every 10 years throughout my life. No book better captures the excitement of scientific discovery—and the realities that talented women face in science.

Fortunately, starting in junior high school, I found an endless stream of local science programs at nearby universities to supplement my public school education. I was one of the best science and math students in my junior and high school classes and was captain of the math team. I attended mathematical astronomy courses at Rutgers University on weekends and during summers in junior high school. I was fortunate to attend the Phillips Andover Academy summer session when I was about 14 years old. They provided me with a full scholarship as otherwise I would not have been able to attend; in recent years, I have funded full scholarships for several Andover summer students with financial need. At Andover, I studied chemistry and calculus as well as computer programming. We, the six kids in math class, covered the entire calculus textbook in the six-week summer program, even though the class was only one hour per day.

Andover was the first time that I was able to take science and math courses that progressed at a more stimulating and challenging rate. When I returned home after the summer session was over, I keenly felt the loss as I faced returning to my local public school. Fortunately I learned of a National Science Foundation program at Columbia University called the Science Honors Program where Columbia faculty volunteered their time to teach high school kids science and math courses on Saturday mornings. Luckily I tested in and there was no charge to attend it. For all of high school, every Saturday morning I would bus in to New York City to attend these courses. I am pleased that 40 years later this wonderful program still exists. In these courses, I found that many of my classmates came from the outstanding public high schools in New York City that specialized in science education such as Stuyvesant High School and the Bronx High School of Science. I sure was jealous of these classmates who were able to attend such outstanding public schools full time.

Attending the Science Honors Program at Columbia allowed me to more fully develop my interest in computer programming from Andover. I spent much of the rest of high school learning computer languages (such as Basic, Fortran, assembly language, and C) and coding, which greatly helped lessen the boredom of high school. Laptop computers did not exist yet, so I had to find local universities that would allow me access to their computers, such as Columbia, Brooklyn Polytech, and Stevens Institute of Technology. This was great fun and prepared me for a wonderful opportunity at Bell Laboratories nearby in Murray Hill, New Jersey. I was looking for a summer job in high school. Their computer systems division had an opening for a summer student. At my interview, I was asked to spontaneously write short computer programs to do various tasks on the blackboard, which was a snap given all my computer experience, and luckily I won the job. My high school let me graduate a month early. So I was able to work the entire summer after high school as well as every summer during college. The salary they paid me greatly helped me afford to go to college, and they even provided me with a desperately needed full scholarship that financed my senior year in college.

Working at Bell Laboratories at that time was an incredible experience, as they had not yet divested from the phone company and so the environment was still highly research intensive. I got to interact with a terrific group of engineers and computer scientists. Unix and C were just being invented in the department where I worked (my first summer I was coding in a language called “B“!). The computer skills I learned were to come in very handy when I attended college at Massachusetts Institute of Technology (MIT) and later as a graduate student.

Bell Labs was the first time that I got to work in a research environment. From the start, I found that once I was working on a project I was totally hooked. I would race to work in the morning, stay late into the evening, and work Saturdays and Sundays as well. I would even debug computer programs while I was sleeping. This kind of self-motivated internal intensity has also characterized the research that I was to do as a PhD student, as a postdoc, and then in my own lab at Stanford. In thinking about my success as a scientist, I do not attribute it to any especially great intelligence. I have met many people far more intelligent than I am who have been much less successful. I believe that two specific attributes have made me successful. First is the intense and uncontrollable passion that I have for doing research. I do not know where this passion comes from, but it has always been there. The second attribute is what in recent years has been called “grit” and refers to attributes of perseverance and resilience. I believe that I have grit in spades. I strongly suspect that this grit likely comes from my “difference,” which I have omitted discussing up to now.

Gender Confusion While Growing Up

I must admit that despite boredom in public school, I had a fun time growing up. But there was a problem that I first became aware of at about the age of three or four years old. Although I was a girl, internally I felt strongly that I was a boy. This was evident in everything about my behavior. Because I had a fraternal twin sister, these differences were all the more apparent. Starting in grade school, my sister had many girl friends and liked to play with traditional toys associated with girls, whereas I strongly preferred to play with boys and toys that were more traditionally masculine. At Christmas, I was disappointed with gifts of jewelry or dresses and was always jealous of the toys that my brother, who was two years younger, would get. I desperately wanted to be in Cub Scouts and Boy Scouts, like my brother, but got stuck in Brownies and Girl Scouts. Every Halloween, I would dress as an army man or a football player. Unfortunately as I got older, these differences were less and less acceptable. When I was about eight years old, I recall going over to my friend Tommy’s house to play with his train set. But one day when I knocked on his door, his mother appeared and disapprovingly told me that I couldn’t play with Tommy anymore because I should be playing with girls. From that time on, I had few friends and learned to keep occupied by myself with reading and various hobbies.

In junior high school, there were some new frustrations. I wanted to take wood shop, machine shop, and auto mechanics, but only the boys were allowed to take these courses, while the girls took courses in sewing and cooking. Every year I asked permission to take the boys’ courses and every year I was told no. But one year, one of the boys asked if he could take cooking because he wanted to learn how to make cookies. He was told yes! In high school, my difficulties began to magnify. As I went through puberty, I felt uncomfortable with developing breasts, which I did not think I should have. And as my twin sister started to shave her legs and wear jewelry and makeup, I found all of this to be very uncomfortable. Instead, I dressed and acted as a tomboy. Whereas my sister had an active social life and many dates, I never dated in high school. Not that this bothered me, as I found that I had very little if any attraction to men (or to women). It was only much later as an adult that I finally realized that I lack the ability to experience sexual attraction (I also have severe face blindness and wonder if the two difficulties are connected somehow).

Because of my gender differences, I was often made fun of and bullied in high school. Another confusing thing was that, unlike my sisters, I never menstruated. Unfortunately I was seen by a doctor when I was about 15 who failed to examine me and injected me with high dose estrogen monthly for over a year. It made me very ill but did not help, and when it came time to go to college, I refused to take it anymore. I finally learned in college that, except for ovaries, I was born without inner reproductive organs, a condition known as Mullerian Agenesis. This was another strong blow to my self-esteem, although lack of reproductive ability bothered me surprisingly little as I have never had maternal instincts or envisioned raising children.

From junior high school on, I had increasingly strong feelings of gender dysphoria, difference, and confusion. I felt very embarrassed and ashamed about my gender incongruity but was totally unable to express what I was feeling to anyone. A male high school teacher once pulled me aside to lecture me about my tomboyish dress. I just listened politely, but was embarrassed and unable to respond in any way. I never uttered a word about my gender confusion to my mother or to my siblings or to anyone else. Surely my mother must have noticed my unusual behavior in grade school, junior high school, and high school, but she never said a word about it. Perhaps she thought I would grow out of it or that I might be gay. If the latter, she never asked me about it (she would not have approved and surely would have seen homosexuality as immoral).

Although I did not yet understand the nature of my differences, I saw two movies during high school that had enormous emotional impact on me because of these differences. One of these was the 1958 science fiction movie The Fly. In a failed scientific experiment the protagonist becomes half man, half fly, ultimately committing suicide in a hydraulic press. Somehow I sensed that I shared an identity with this scientist and his ultimate fate. The other movie that powerfully emotionally affected me in high school was the 1932 horror movie Freaks. Again I identified with the deformed circus performers. With the exception of Harry Potter (considered a freak by muggles), I have never identified with any other movie characters except for the fly and the freaks in these films. But it was many more years before I understood that the real monsters in the movie Freaks were not the physically deformed circus performers, but the “normal” members of the circus who humiliated and degraded those circus performers.

It is difficult to express the degree of continued emotional pain, low self-esteem, and ultimately strong suicidal ideation that my gender discordance caused me while growing up and as a young adult. It was only at the age of 40, as I will come to later in this chapter, that I finally understood that I was transgender and was able to deal effectively with the problem. But growing up I was too confused to talk with anyone about it or to have any idea what to say. It just made no sense that I was a girl feeling like a boy. How could I ever utter something like that to anybody?

The cause of transsexuality is not known. Recent identical twin studies show a concordance rate of about 30 percent so part of it may be genetic. Female animals and humans exposed to male hormones during fetal development exhibit masculinized behaviors. My mom was treated with a testosterone-like drug during the first trimester of her pregnancy, when she was carrying my twin sister and me in 1954. Back then synthetic steroid drugs had only been recently invented and doctors were experimenting with them to see if they could prevent miscarriage in certain high-risk pregnancies (my mother had had some slight vaginal bleeding early in her pregnancy which was thought back then, wrongly as it turns out, to put her at high risk of miscarriage). Many women were treated with diethylstilbestrol but my mother was instead given a testosterone-like drug. I suspect that this drug may have masculinized my brain (for most transgender people there is no history of abnormal fetal hormone exposure). If so, it did not affect my twin sister. Fetal iatrogen exposure, however, almost always affects one twin but not the other

Unfortunately, I never developed particularly close feelings of affection for anyone in my family. Partly this is because I moved away from home at a young age. But I suspect it may also be because I was unable to bring myself to share the constant emotional pain I suffered from childhood years onwards. I blame myself entirely for this. I sorely wish that I had been able to open up to my mother about it. In recent years, it has been realized that as many as 1 percent of people may be transgender and there has been so much public education that parents are often able to open the discussion with their transgender children as early as grade school. Whenever I see videos of parents talking openly and supportively with their (pretransition) transgender children, I weep. Much progress is left to be made, but I marvel at how far the world has come in recent years.

MIT

I decided when I was 13 years old that I wanted to go to MIT. My eighth-grade science teacher had mentioned some research done there. I looked up MIT in the encyclopedia, and it said that it was one of the best science universities in the world. No one in my family had ever gone to college, my parents had never heard of MIT, and my parents could not afford to pay anything toward my college tuition or expenses. But I was sure I was going to go there. When it came time to apply to college my senior year (1971), I talked with my guidance councilor and told him of my plan to apply to MIT. Although I was the strongest science and math student in my class and had nearly perfect SAT scores, he assured me that I would not get in there and strongly encouraged me to apply to some local, less competitive schools. I later found out that the same guidance councilor had encouraged several of the boys in my class to apply to MIT even though I ranked higher academically than they did. This was long before my sensitivities about gender-based discrimination had been raised. In any case, I ignored his advice and I applied only to MIT early decision.

By early December in my senior year, I learned that MIT had accepted me and that, thanks to their scholarship and loan programs, I would be able to attend despite my family’s low-income status. I sure was happy! In retrospect, major American universities were only just starting to admit women in any appreciable number in the late ’60s and early ’70s. So even though I was a more than qualified applicant, the barriers that talented women faced when applying to top colleges were lessening substantially around the time of my application in 1971. Although MIT admitted women from their start, their numbers were very low, perhaps a few per year, until the 1970s. When I arrived in the fall of 1972, I found that only about 5 percent of students at MIT were women. As I felt that I was a boy, however, I did not particularly notice this and it did not concern me.

I loved MIT. I found immediately that despite my differences, unlike in high school, I fit in. I was a science nerd just like everyone else. The quality of the courses that I took and the faculty that taught them were all beyond superb. MIT has long prided itself on having their best faculty teach the undergrad courses and, boy, did I have stellar professors there. In my freshman year, like all the students, I took physics, calculus, and chemistry. Although I worked hard, I did not find that I needed to pull all-nighters and I enjoyed everything that I was learning. Though I got A’s in most of my classes, I was no longer close to the best student in every science class anymore. But this did not matter to me at all. I was just finally being academically challenged, able to take whatever course I was interested in, and I totally loved it. Despite my relative lack of sexual attraction, in college I had my first and only boyfriend, whom I lived with for several years. We were not a good match and eventually split; I preferred a single existence from that point on.

Because of my financial difficulties, sometimes I would run out of money and need to scrape by until the next monthly scholarship check arrived. Though I am sure others in my class faced worse financial difficulties, these experiences made me realize the challenges that many students from low-income families face in college. I was not surprised to see that even though Stanford and some other universities now pay full tuition and provide a stipend for low-income kids whose families make less than $60,000 per year, few of these kids are accepted into Stanford each year. Those who do get in still face enormous financial challenges as they have many expenses beyond tuition, room, and board to somehow pay for—and many of these kids must send funds home to help support their families. We need to do much more to help these kids!

MIT’s course requirements for any given major were not very extensive then, which made it possible to try new areas of interest. I entered as a double major in chemistry and computer science, and came very close to fulfilling the major degree requirements in both of these areas. Although I did very well in these courses, my professors failed to notice my ability and failed to encourage my interest (I will say more about this later). In my sophomore year, intrigued by artificial intelligence and the excitement in this research area at MIT, I took a course on the subject. The professor lectured about ongoing efforts in the field to make intelligent computer programs, for instance to decode visual scenes or understand language. This got me curious to know more about how the brain actually worked, so I signed up for a popular course called introduction to psychology and brain science (the term neurobiology had not yet been coined).

The professor who taught this course, Hans-Lukas Teuber, was a gifted teacher. His course changed my life. Like many of MIT’s professors, during Teuber’s lectures, he talked as much about what was yet unknown as about what was already known, weaving the very latest research into every lecture. He had spent much of his own career studying how brain injuries in different brain regions affected the functioning of the brain. From his lectures, I understood that studying patients could be a powerful approach to understanding the brain. By the end of the course, I had decided to become both a neurologist and a neuroscientist. I don’t think I quite understood yet how many more years of study and hard work would be needed to accomplish these goals. I changed my major to neurobiology (I had to create that major, which did not yet exist—an option MIT provided) but soon decided to switch my major to life sciences when I realized how many pre-med courses I still needed to take. These courses included biology, biochemistry, genetics, and cell biology, and again all were outstanding. I vividly recollect, for instance, the wonderful lectures of Salvadore Luria, who taught my biology course at MIT. Again, he skillfully interleaved basic knowledge with the very latest research advances. Both Teuber and Luria wrote strong letters of recommendation for me that helped me to win a desperately needed full scholarship from Bell Labs that financed my last year of college.

Going to MIT was an incredible privilege. It changed my life and opened many doors for me. But it was not a perfect experience by any means. Although MIT was finally admitting more women, women were not in some important respects receiving the same education as the men. In 1972–1976, the years I attended MIT, there were almost no women on the faculty. So women students did not see many role models. The course lecturers were almost all men, and the research that was being presented was virtually all done by men. Sometimes there were overtly sexist remarks made by famous male faculty during their lectures. The Nobel laureate who taught my first physics course made overtly sexist remarks in lectures and showed nude pinups, causing me to transfer to another physics course. Also, although I was an outstanding chemistry and computer science student and did extremely well in many advanced courses on these topics, the faculty did not notice me or offer me research opportunities in their labs as frequently happened to the male students. Both chemistry and computer science have long been highly male-dominated fields, and historically, women have not been particularly welcome. Even in 2017, few women are on Stanford’s chemistry and computer science faculties.

In the artificial intelligence computer science course I took at MIT, I was the only student to solve a very difficult question on the take-home final exam whose solution involved constructing a LISP program with nested subroutines that recursively called on each other. The professor announced in class that because no one had solved it, he was not counting it toward our grades. After class, I went up to the professor to show him that I had solved the question. To my dismay, he sneered at me and said that my boyfriend must have solved it for me. I was offended because he was unfairly and wrongly accusing me of cheating. It was many years before I realized that his meaning was deeply sexist—he just couldn’t believe a woman had solved the problem when so many men had been unable to. I imagine if I had been a male student that my name might have been mentioned in class and or that the professor might have encouraged my career in computer science; perhaps he might have offered me an opportunity in his or a colleague’s lab. This is why I get deeply angry when famous men (like Larry Summers, who I will come to later) espouse the idea that women as a group are innately less good at science than men but say that, of course, they do not discriminate against individual talented women. They fail to miss the basic point that in the face of pervasive negative stereotyping talented women will not be recognized. Such negative stereotyping is not supported by any data and is deeply harmful to all women.

Indeed, when it came time for me to find a lab to do undergraduate research, although I was an outstanding student, I struggled to find any MIT lab that would accept me. Equivalent male students did not have much difficulty finding outstanding labs in which to train. I finally found a young female professor who was willing to supervise me. Although I worked long hours in her lab for several years, I received little mentoring, and it was a less than ideal experience. It is not surprising to me that with this kind of gender-based discrimination so many women in my generation (and still) were dissuaded from careers in science. I suspect that these discouraging experiences overall had much less effect on me than most women because, as I have mentioned, I did not see myself as a woman. In any case, I entered MIT full of passion for science, and I left the same way. In the end, that’s all that really matters.

Medical Training

I attended Dartmouth Medical School from 1976 to 1979. Medical school generally takes four years to complete, but Dartmouth managed to shrink it down to three years. As I wanted to do research training after medical training, the shorter time to complete the doctor of medicine (MD) degree was appealing to me. Also living in beautiful rural New Hampshire seemed like a dream to me. I enjoyed living there more than any other place that I have been. All of the medical school classes were on the honors, pass, or fail grading system, and we got two afternoons a week off. Dartmouth was known for its strong basic science training, and I found that all of the courses were superb. While in medical school, I took full advantage of the beautiful New Hampshire environment. In fall and spring, I frequently went hiking or biking, and during the long cold winter, I was generally outside cross-country skiing on the many beautiful local ski trails. Once I entered my clinical rotations, time for these activities largely diminished, but I am very glad that I took some time during my first year and a half at Dartmouth to enjoy these things as I look back on that time very fondly.

Unfortunately, during medical training, I found that the barriers for women started to become even more glaring than they were at MIT. Dartmouth was one of the last colleges to go co-ed. Many colleges began admitting more women in the late 1960s, but Dartmouth started to do this only in 1972. So although my class was only 20 percent women, these women included some of the very first women to graduate from Dartmouth College. I would often go to Dartmouth home ice hockey games and hear old alums on the benches behind me loudly complaining about how the school had gone to pot since they started to admit women. Perhaps not surprisingly I once again found that there were still barriers for women in medical education. In my first-year anatomy class, the male professor liked to show slides with pictures of nude females. I was grateful when one of the male students went up to the professor after class to protest this. Disconcertingly, when women students asked a question after lecture, male professors often responded to a nearby male student. I was interested in doing research in a neuropathology lab. I found a professor who was willing to admit me to his lab. Unfortunately, I soon found that the reason that this professor had agreed to take me into his lab was so that I would talk with his wife. He was not willing to actually teach me anything or involve me in his research. Similarly, when I got to the clinics, I found that women students were largely ignored by many of the clinical faculty. I quickly realized that if I wanted to learn anything, I had to be fairly assertive. It was hard to get past the feeling that women were largely not wanted or respected. Fortunately, although neurology was largely a male profession back then, I do not recall anything but a supportive neurology environment at Dartmouth.

One day during an endocrinology lecture, the professor taught us about a rare condition called testicular feminization, now called complete androgen insensitivity syndrome, in which XY individuals are born phenotypically female because they have a mutation in androgen receptors and thus are insensitive to testosterone. These patients lack internal reproductive organs. The professor said that these “women” were often not told of their diagnosis and XY karyotype. I was kind of in shock after the lecture as I thought that maybe I had this condition but was never told. It was many months before I was able to read my medical records to find out for sure that this was not the case and that my karyotype was XX. As I became more knowledgeable about reproductive disorders, I also spent time in medical school trying to research more about what was known about gender identity and whether there was any relationship between my gender identity confusion and my reproductive organ anomaly. There was no evidence that fetal steroid hormone exposure ever caused Mullerian agenesis; moreover, most patients with Mullerian agenesis had normal female gender identity. Only recently had the term gender identity even been coined by Hopkins psychologist John Money. His view was that gender identity was completely socially constructed. To prove this, he was studying a patient who had lost his penis from a circumcision accident when he was an infant, and he had convinced the boy’s parents to raise him as a girl. Money wrote many papers asserting that the boy was developing with a normal female gender identity (as it later turned out, none of this was true, and the theories of Money were later completely discredited). So my confusion remained because if Money was correct, there was no reason why my gender identity should not be female despite my reproductive anomaly. In recent years, genetic mutations have been linked to Mullerian agenesis, so I suspect that such a genetic defect led to my abnormal fetal development, which led to my mom’s first trimester vaginal spotting, which in turn led to her doctor giving her the testosterone-like drug, which in turn affected my gender identity.

At the end of medical school, I continued to be interested in both neuroscience and neurology. I next had to decide whether to do research training or to proceed with a neurology residency. I asked quite a few different professors. This was not very helpful as by the end of this inquiry, I realized that each of them had advised me to do exactly what they had done. I was not in a rush to complete my training, and I was still strongly considering being both a practicing neurologist and a neuroscientist. I decided to proceed with a medical internship (one more year) and neurology residency (three more years). Because my mother had been diagnosed with metastatic breast cancer, I wanted to do an internship near to where she lived in West Orange, New Jersey. I selected as my first choice a Cornell-based program at North Shore University Hospital (NSUH) in Manhasset, New York, where interns and residents spent half of each year at NSUH and the other half at Memorial Sloan Kettering Cancer Center (MSKCC) and New York Hospital (NYH). Both the medical and neurology training in this program were superb, and it was only about a 45-minute drive to West Orange. Fortunately, they selected me, so I began my internship in July 1979.

In those days, there was not yet any limit on the number of hours that house officers could work. As an intern, I worked about 110 hours per week, sometimes more, and was on call every third night. On the call night, there was no sleep or, if I were lucky, at most, one hour. Interns always used to debate whether it was best to sleep for that hour or not (I took any sleep I could get!). On the other two nights, interns typically worked until midnight (and the days often began at 6 a.m.). Some interns were unable to handle the stress and soon left the program. As I had gone to a three-year MD program in a rural location, I found that I was not nearly as well prepared as my fellow interns who had trained in city-based programs. But I quickly caught up. It was the most intense year of my life. It is good that there are now strict restrictions on how many hours a house officer can work per week, limiting the time to 80 hours per week. After all, 80 hours is still barbaric!

After internship, I began neurology residency. Call was still every third night, but with every progressive year, there was more sleep to be had as the most junior residents shouldered much of the night workload. Alas, during the second year of my residency, my mother’s cancer was rapidly progressing. I transferred her to MSKCC where I could keep an eye on her and her care, but she soon passed away. She was only in her mid-forties. She was a really great mother who raised four successful kids under extremely difficult personal and financial conditions. It is sad that she did not live to see us kids do well and get to know all her grandchildren.

Neurological disorders can of course be devastating to the patients they affect, but I loved every moment of my neurology training. My fellow residents were terrific as were most of my attendings at NSUH, MSKCC, and NYH. With only one exception, nearly all of the neurology attendings were men. One of the chief neurologists was very hostile and disrespectful in public to the few women residents and I certainly both experienced this and watched his treatment of others. My fellow (male) residents would often tell me of overtly sexist things he would say to them behind closed doors. But all of my fellow residents and nearly all the other attendings treated me with respect so, as always, I just sucked it up, and did the best that I could do in my job. I was lucky to have Jerome Posner as an attending physician while at MSKCC. He was as gifted a neurologist as I have ever known, a brilliant teacher, and a very kind man. I served as chief resident of neurology in my final year of training. Overall, the training was superb. I did well and passed my neurology boards with ease. But as I completed my residency, I increasingly reflected that even as a fully trained neurologist, I could offer my patients few treatments to help them with their neurological injuries and diseases. This strongly drove my desire to move on to neuroscience research training.

Doctoral Training

As I had completed seven years of medical training, many people encouraged me to skip graduate school and go straight to a postdoctoral fellowship. This idea did not appeal to me, as I had not yet done any neuroscience research. Moreover, during the seven years of my medical training, the field of neuroscience was exploding. I was not ready to select a specific research topic to focus on and wanted to have a bigger picture of neuroscience first. I therefore applied to PhD programs in neuroscience. I applied to many graduate programs, as I wasn’t sure anyone would be interested in accepting a neurologist with no neuroscience research experience. To my surprise, nearly all of the programs that I applied to accepted me. I decided to go to the relatively new neuroscience PhD program at Harvard Medical School (HMS) as it allowed its students to rotate in labs not only at the HMS quad (main campus) but also in the nearby Harvard-affiliated hospitals, which tended to be more disease oriented. I turned down a lucrative offer to join a neurology practice on the North Shore of Long Island. I had spent six months in my neurology training in an electrodiagnostics lab and was highly skilled at doing electromyography and nerve conduction testing, a lucrative skill back in those days. But the lure of a high salary held little attraction to me. This particularly puzzled my dad who I recall saying, “Let me see if I understand this correctly: You are going to turn down a $200,000 per year salary after seven years of expensive medical training to earn $6,000 per year as a graduate student and start all over again?” I gave him an enthusiastic, “yes!”

I began my graduate training in 1983. Unfortunately, the day that I began my graduate training was also the day that my college and medical school loans all came due. So for the first two years of graduate school, I was also moonlighting as a neurologist at New England Baptist Hospital every Friday night to Monday morning where I rounded on all the neurology patients, performed electromyography and nerve conduction tests, performed neurology consults and the many needed procedures somehow not done during the week, and covered any neurological emergencies. It was exhausting. I found that I was not performing as well in my graduate lab rotations and courses because I was not getting enough sleep and never had enough time. My first two lab rotations did not go well. The summer of my first year quickly arrived, and it was time to select a third rotation. The patch clamp technique had recently been invented, and I was interested in learning it. One possibility was David Corey, a new faculty member who would be arriving in the fall. But his lab was not set up yet, so I was considering another lab instead. I called David up (he was still at Yale) to discuss the possibilities with him. I told him about the other “patch clamp” lab I was thinking about. He knew it to be a very weak choice, something I was unable to yet judge for myself. Rather than telling me not to go to that lab, he suggested that because I could work with him in the fall, I should select another lab in the meantime where I could learn other skills that might come in handy when I was learning to patch clamp, such as tissue culture. He suggested Linda Chun’s lab because she was next door to where his new lab would be at Massachusetts General Hospital (MGH). His advice helped me to avoid a poor mentorship choice that would have greatly limited my career. This example illustrates the enormous role that luck plays in scientific training. Despite the importance of selecting good mentors, first-year graduate students are rarely ready to make this choice wisely.

Fortunately, Linda Chun agreed to let me do my third rotation with her. She was also a very young faculty member who had only recently established her own lab. So she had lots of time every day to personally talk with me and guide me. I started to really love being in the lab. I had selected her lab not only because of David’s recommendation but because I was very curious about glial cells from my neurology training. Glial cells were still very mysterious back in the early 1980s, but it was clear from histology and pathology studies that they were the majority of cells in the human brain and that they changed their properties radically in most or all neurological injuries and diseases. Although it was known that oligodendrocytes (OLs) were the myelinating cells, the roles of astrocytes were particularly mysterious. It was not clear what the astrocytes normally did in healthy brains—they were assumed to be largely passive and to be support cells for the neurons—or what they did in diseased brains, where they changed their properties and became “reactive.” But whether reactive astrocytes were helpful or harmful was not known. In Linda’s lab, I learned how to dissociate brains into cell suspensions and then how to culture those cells, including the glial cells.

Linda had done beautiful work as a graduate student with Paul Patterson culturing and studying sympathetic neurons and their responses to nerve growth factor (NGF), and as a postdoc she had studied immunology. Now she was interested in studying whether and how glial cells interacted with immune cells. Methods to purify and culture central nervous system (CNS) cell types were still in their infancy in 1984 so I spent a lot of time during my rotation playing around with different ways of isolating and culturing neurons and glia. Linda was a wonderful mentor. She was full of passion for science, and she asked big, important questions. She used new methods as soon as they were available and was undaunted by high-risk work. I learned a great deal from working with her. I also enjoyed being at MGH because some of the most legendary neurologists to ever live were still in active practice there, including Ray Adams and C. Miller Fisher. I had read many of their papers in my neurology training and it was thrilling to hear their eloquent discussion of patients at case presentations.

In the fall of 1984, at the start of my second PhD year, I began my fourth rotation in David Corey’s lab. As yet, no one else was in his lab so, and to my very good fortune, he had much time to talk with me and teach me many things. I was really quite immature yet as a scientist, and all those years of medical training had not helped my research abilities. So I really needed some serious mentoring. David turned out to be a phenomenally good and caring mentor. He was not only an incredibly talented and rigorous scientist, but quality mentorship was something he cared about very deeply. I have tried to emulate this in my own lab, but I always feel that I fall far short of the standard he set. Some of the things that he did were to go to neurobiology lectures with me and insist that I ask a question after the talk, and when I generated interesting data, he would often tell me to go make an appointment with a particular professor he thought might be interested in it. He would always allow me to join him when he met with visiting scientists. Although I was initially very shy to do all these things, my shyness quickly diminished as I realized that all these professors were always kind and enthusiastic to discuss interesting new findings, and I always benefited enormously. His focus was always on mentorship and expanding me as a scientist, and he encouraged me to take Cold Spring Harbor laboratory courses and to go to many meetings. It also helped that he was a Howard Hughes Medical Institute (HHMI) investigator, as his lab was always well funded and I was able to try new techniques and whatever crazy ideas for experiments came to mind.

When it came time to teach me how to patch clamp, David was still setting up his lab and the bullfrogs, whose ears he studied to understand mechanical transduction of inner hair cells, had not yet arrived. He said let’s practice on glial cells, which I had learned how to culture in Linda Chun’s lab. This promised to be deadly boring, as back then, it was neurons that were thought to express all the interesting voltage-dependent ion channels and neurotransmitter receptors, whereas glial cells did not fire action potentials and thus were thought not to express ion channels or neurotransmitter receptors. I quickly learned how to patch clamp, and to my surprise, I soon found that, although they were not electrically excitable, both astrocytes and OLs expressed a broad array of different ion channel types and even neurotransmitter receptors. I decided to join David’s lab (Linda remained a wonderful coadvisor) and spent the next six years cataloging and describing the various types of ion channels in glial cells in vitro and after acute isolation as well as how their properties compared with their neuronal counterparts. It was technically challenging work, as patch clamping was still quite new. It took much effort to figure out how to patch on to these cells to achieve gigaohm, tight electrical seals. In addition, the computer programs necessary to acquire and analyze patch data did not yet exist, so I was (most enjoyably) able to use my computer programming skills to write many of these programs.

Upon joining the Corey lab early in my second year of graduate school, there were still obstacles to getting much research done. I was still taking required graduate courses and still moonlighting so that I could pay off my loans. I was often sleep deprived and frequently was caught falling asleep during course lectures. One Monday morning after a particularly grueling weekend of moonlighting and little sleep, I dragged myself into work. David looked at me and realized I was exhausted and asked me why I was doing this to myself. I explained to him that I needed the money, and he exclaimed, “Is that all?” He proposed that I quit my moonlighting and instead be paid by him at a postdoctoral level since I already had an MD, and he had many HHMI postdoctoral slots as yet unfilled. This would immediately raise my salary from $6,000 per year to $17,000, which was sufficient for me to make ends meet. I quickly accepted his kind offer, which also enabled me to move from the HMS quad dormitory to a small, and alas cockroach infested, apartment in Beacon Hill only a block away from David’s lab. This change immediately resulted in more sleep, and less stress, and I suddenly started to do much better in my courses and in lab. Although some physician-scientists are able to combine clinical and research careers, I realized that I was not a good multitasker and, although I missed practicing neurology, I never again tried to combine clinical practice with research.

Besides, I was enjoying the research too much. As happened to me at Bell Labs, I found that I did not want to ever leave the lab. I could be found there nights, weekends, and holidays. I slept as little as possible (my clinical training had taught me I could survive without much sleep) and never took vacation. Once though, I was feeling particularly tired and decided to go to Miami Beach for a week holiday. I arrived in Miami around 4 p.m., fell into bed, and slept until the next morning. I then went to the beach for about 15 minutes, but then decided I would rather be in the lab, and flew straight back to the lab!

As I tried to formulate my thesis proposal, I turned to the superb HMS library to learn what was known about glial cells and what methods were available to study them. I read the work of the early neurohistologists and found that Cajal had wondered about glial cells and what they might do. He had concluded that until better techniques were available to study them, their roles would be a mystery. As I read the more recent work and realized how few techniques had materialized, I despaired as the available papers did not seem coherent, and I wondered how I could make much progress. But one day I stumbled across the recent work of Dr. Martin Raff, a professor at University College London who had also trained as a neurologist and then had done brilliant work as an immunologist. He had recently turned to using his immunology skills to start to dissect the types of CNS glial cells; his first papers about glia were only just being published in the early 1980s.

These papers were exceptionally elegant and beautifully written. He took advantage of the optic nerve as a simple part of the CNS and showed that optic nerve cultures contained not only oligodendrocytes (OLs) and two different types of astrocytes that he called type 1 astrocytes (1As) and type 2 astrocytes (2As), but also a new type of glial progenitor that he dubbed O2As for OL-type 2 astrocyte progenitor cells (the O2As were later renamed OPCs for OL precursor cells (OPCs) when it became clear that there were few 2As in vivo, although they are generated robustly under certain in vitro conditions). Most excitingly, he identified and generated a variety of antibodies that could be used to specifically identify each of these cell types: Both 1As and 2As expressed the glial fibrillary acidic protein (GFAP) antigen, 1As expressed the Ran2 antigen, 2As expressed the A2B5 antigen as did O2As, and OLs expressed galactocerebroside. The culture conditions that his lab developed not only allowed for the study of all of these cell types but also enabled their development and maturation to be studied. Moreover all of the axons in the optic nerve came from retinal ganglion cells (RGCs), and as these axons could all be severed by a simple surgical procedure, this was also a powerful system to investigate the nature of neuron–glial interactions. I immediately realized that the optic nerve system would be the perfect system to investigate the nature of ion channel and neurotransmitter receptor expression by different types of glial cells as well as the nature of neuronal influence on glial electrophysiological properties.

By coincidence, at the same time that I was excitedly telling David about these papers, David happened to notice that Martin Raff was coming to MIT to give a lecture. When the time came for the lecture, David insisted on joining me, which surprised me because David’s research focus was on hair cells. He insisted that we go to the lecture early. When Martin Raff entered the MIT auditorium to set up his slides, we were so early that we were the only other people present. David told me to go up to him and introduce myself and ask him a question. I was still terribly shy as I was only at the start of my second graduate year. I said no, but David insisted, and as he was sitting there watching me, I had no choice. I shyly approached Martin, and he was very kind and answered my question. After Martin’s most elegant lecture, David insisted that I go ask him another question! I had lots of questions, so I am glad that David was there to make sure that I asked them. Soon after, David suggested that I write to Martin to ask him to be on my thesis committee. I could not imagine that Martin would agree to this, but to my surprise he kindly agreed.

When the time came for my qualifying exam, Martin was there and made many helpful suggestions. This began an active correspondence (via air mail from Boston to England as the Internet had not yet been invented) in which I would write to Martin with questions or with my latest data, and he would in turn answer my questions or tell me about recent advances in his lab. He was full of passion for science, and by early in my graduate career, I was already thinking that it would be wonderful to do a postdoctoral fellowship in his lab. But I doubted very much that he would ever accept me, as whenever I would go up to ask him a question after a lecture, I would always hear him telling others that he did not have room for them to do a fellowship in his lab. In the meantime, he was like a third graduate advisor, in addition to David and Linda, as he generously provided me with so many helpful thoughts and suggestions for my research.

I will not detail all of my research findings as a graduate student, but some of the interesting findings that I made were that 1As, 2As, OPCs, and OLs all expressed different complements of ion channel types, in vitro and in vivo (as judged by examination immediately after acute isolation), and that OPCs expressed functional α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors (Barres et al. 1988a, 1990a, 1990b). I found that the presence of serum, and even different lots of serum, had profound effects on which types of channels were expressed by glia in culture, which taught me to avoid the use of serum in cultures for the rest of my life (Barres et al. 1989b). I found that even voltage-dependent sodium channels were present in astrocytes, although these cells were not excitable, and by single channel analysis that the glial sodium channels had different properties compared with their neuronal counterparts, with different kinetics and voltage sensitivity (Barres et al. 1989a). In collaboration with Linda Chun, I also developed a simple method to very highly purify RGCs by immunopanning, although the purified cells quickly died in culture (Barres et al. 1989b). I was not able, however, to figure out how to keep them alive to study their interactions with glial cells until many years later, as I shall come to. I also showed that the primary ion channel type in OLs was an inwardly rectifying potassium channel and that, over development, these channels rapidly localized to the ends of their processes (Barres et al. 1990a). These channels were also highly expressed by the 1As, although they were not present immediately after their generation but rather developed by about a week later unless the RGC axons were severed, in which case they never appeared, suggesting that neurons were inducing their expression (Barres et al. 1990b). Because I found that astrocytes and OLs expressed high levels of an occult voltage-dependent chloride channel, which became activated in excised patches (Barres et al. 1988a), I proposed that astrocytes accumulate potassium during neuronal activity not by spatial buffering but by accumulation of potassium (K⁺), chlorine (Cl⁻), and water, as do muscle cells but with the caveat that there must be a missing signal, probably neuronal, that activates these chloride channels and, in turn, the accumulation of K⁺ for later return to the glia after activity was over. Alas, this possibility remains uninvestigated, but I still think it is an intriguing possibility. The injured brain swells rapidly after injury and release of such a neuronal signal might lead to new insight about why this swelling occurs and how to better treat it.

Because I liked doing experiments I was accumulating many papers’ worth of data but was stalling on writing it up. I had never written a paper before and, besides, that seemed boring compared with generating the data. David grew increasingly frustrated. It didn’t help that I tended to mess around with other experiments that had nothing to do with my thesis. One night in my third year I used a dounce homogenizer to isolate some nuclei that I labeled with a fluorescent nuclear dye so that I could visualize them and try to patch onto them to see whether their were any ion channels in the nuclear membrane. I did the experiment late at night so David would not catch me, but around 10 p.m. he suddenly appeared! He asked me what I was doing. I said nothing, just the same old thing. He said, “Let me see,” and he sat down at the microscope and looked through the eyepieces and … I was busted! He was silent for a minute. I could see he was not happy. He looked at me and said, “You know someday, if you ever learn how to focus, you are going to be a great scientist.” That was David, even in criticism he was supportive and kind.

Eventually, by my fourth year when no papers had yet appeared, David banned me from the lab. He sent me home with a computer and told me not to come back to lab until I had written at least one paper. Not being allowed to be in the lab was a terrible agony, so I wrote that paper in record speed! By the time I graduated, I had written six primary research papers (five of which were published by Neuron and the first of which was the inaugural article in the first issue of Glia), a long Annual Review of Neuroscience article on ion channels in glia (Barres et al. 1990c), as well as a few other reviews and commentaries. That seemed like a lot, but the patch clamp technique was new and there were a lot of low-hanging fruit. I learned a tremendous amount about ion channel biophysics, but all of these papers shared the flaw that they were largely descriptive and did not really provide any really new insight into what the glial cells actually were doing in the brain. I always tell students that one good paper is more than plenty for a PhD or postdoc. Just ask an important question, and take it one step forward. That was hard to do back in the 1980s but with the tremendous advances in methodology, it is now something within reach of every trainee and is what makes running a lab now so much fun.

There were many difficulties in graduate school. There were many technical stumbling blocks, which I eventually solved, in figuring out how to isolate glial cells viably, how to stably patch records from them, and so forth, which I will not belabor. At one point, in my third year, there was an HHMI site visit during which some super-famous scientists were rolled out to hear about what research was going on in David’s lab. David presented to them both the hair cell stuff, which they rated very highly, and the glia stuff, which they were not so impressed by, to put it mildly. I decided perhaps I should work on hair cells after all. The lab was quite small, and it was really amazing that David was even allowing me to work on glial cells rather than hair cells. So I decided to work on hair cells for a while, and even got my name on the author line of one hair cell paper. I actually did not do any of the experiments in the paper but had suggested a simple way of isolating hair cell stereocilia for biochemical analysis that David dubbed “the bundle blot,” which turned out to work rather well. But after a few months, I found myself thinking again about glial cells. There were so many things I wanted to understand about their roles both normally and in disease. I decided that I would keep working on them anyway despite the negative HHMI review. Although I didn’t realize it back then, the HHMI folks were quite correct that the work was largely descriptive; nonetheless, I was developing methods and laying the groundwork that would allow me in the future to finally be able to answer questions about glial cells. As always, David was highly supportive and encouraged my return to the glial work. Although I did not do much work on hair cells, it was an incredible privilege to be in the lab to watch David and his trainees elucidate so many of the fundamental mechanisms of hair cell transduction in technically versatile and brilliant experiments.

During graduate school, my gender confusion was increasingly bothersome. I had still not been able to talk to anyone about it and was increasingly feeling suicidal. I was beginning to contemplate specific ways that I might kill myself. This got sufficiently scary that I decided to go talk with a psychiatrist for the first time in my life. I had one appointment with a Harvard psychiatrist that lasted about 10 minutes. I told him that I was feeling increasingly suicidal, but was too ashamed to admit the gender confusion to him, which he did not ask me about. All I recall him asking me was whether I was close to anyone (friends, siblings, parents, etc.) to which I replied no. At the end of our brief chat he pronounced that I “was unable to love.” I doubted this was the case, although now I am not so sure. In any case, my desire to see him again or any other psychiatrist waned, but my suicidal ideation persisted. Eventually, I got up the courage to mention my suicidal thoughts to David. I do not think he believed me because I did not appear depressed (and I do not think I was depressed, nor have I ever experienced a clinical depression), but he did make an appointment for me to talk with a social worker he knew. I talked to her regularly for several months. Again, I could not bring myself to talk about my gender confusion, but we did talk a lot about low self-esteem. Eventually, I felt a bit better, and I returned to dealing with my problems, as always, by burying myself in my work.

Fortunately, in graduate school, it seemed that gender-based discrimination was much less a concern that it had been during my medical training. Most of the professors were men, but there were some terrific women on the faculty. Back then many male professors had affairs with their graduate students and postdocs with impunity despite the harm to the trainees that often resulted; I was uncomfortably aware of many such relationships. It has been a great advance in recent years that most top universities, in the United States anyway, now have explicit policies that govern such relationships. There was only one episode that I feel was likely gender-based discrimination that directly affected me. In my last year of graduate school, I applied for an elite career-transition award that would have funded my postdoctoral fellowship as well as provided funding for my own lab someday. Harvard was allowed to submit two candidates into the national competition, and I earned one of those two spots! When I met the senior Harvard dean to discuss the competition, he said to me “I shouldn’t tell you this, but you are one of our two candidates. The other one (who was a man) has a far weaker application. You have six papers in top journals and he only has one, and your letters of recommendation are also much stronger. You are definitely going to win this award.” But the other guy won. No doubt he was also very talented, but within a year or two, he dropped out of academia to start a biotech company so he must have quickly given up the award. But, other than the question of fairness, it really did not matter to me, as I found other sources of funding for my postdoctoral fellowship.

I feel fortunate that I was able to do my doctoral work in the neuroscience program at HMS. It was a superb program in every way. Eventually, by the end of my seventh year, my advisor David decided that it was time for me to graduate. I had successfully defended my thesis (I still recall his concluding line of his introduction, which makes me smile, he mentioned all my papers and then said, “This would be enough work to get Barbara tenure at most universities; let’s see if it’s enough to get her a PhD at Harvard!”). But I still had many experiments I wanted to do, so I was not in any rush to leave. David said to me one day that on such and such a day, I would no longer be paid. I took the hint and moved on to my postdoctoral work, but it was very painful to leave his lab. In many ways, I saw David as a father figure. I admired him deeply as a scientist, mentor, and friend. He was very kind to me and taught me so much, spending endless hours rehearsing talks with me, editing my papers, and so on. I know that the unusually high-quality mentorship that I received in his lab was the key to my success in science; he went on to train many other highly successful scientists (10 of them have Harvard faculty positions; 11 if you count a Harvard offer I was once made but turned down). When it was time for me to leave his lab, it ripped my heart out. On my last day, I sat in the MGH courtyard and cried at having to leave. And at the goodbye party, for the first of two times in my life, I got drunk. I returned to my Beacon Hill apartment for one final night with the cockroaches and departed for London the next day.

Postdoctoral Years

I did my postdoctoral work in Martin Raff’s lab between the years of 1990 and 1993. One day during my fifth year of graduate school, he was visiting me at MGH, and I worked up the nerve to finally ask him if I could work in his lab. As I feared, he immediately said no, he didn’t think that was a good idea. I was crushed! Eventually, he said that if I really wanted to do that, I could visit his lab at University College London. He had a very tiny lab in a very old building with only a few postdocs and no graduate students. I couldn’t believe that such a small lab had been the home to so many important research contributions in cell biology, immunology, and neuroscience! He finally agreed that I could have a postdoc position with him. I guess I failed to tell him that I needed a couple of more years to finish my PhD (in England, they are typically only three or four years) so I felt very guilty (and still do) when I realized after finally arriving that he had held a bench for me in his tiny lab for a couple of years, but he never said a word to me about this.

I was concerned about how I was going to finance my postdoc, as I still had educational loans to pay off and few fellowships financed training abroad. Fortunately, I was awarded fellowships by both the National Multiple Sclerosis Society (NMSS) and the Life Sciences Research Foundation (LSRF). Each of these fellowships offered an annual salary of $18,500 and allowed foreign training. When I looked up the National Institutes of Health (NIH) recommended salary scale based on years of training, it recommended a salary of $37,000. So I asked NMSS and LSRF if I might simultaneously accept both of their fellowships and to my great surprise they both readily agreed. This was a huge relief. The LSRF funding also provided a generous annual $15,000 amount to help finance the cost of experiments, which was also extremely helpful. The great generosity of these two organizations made my postdoctoral training possible.

During my first year in Martin’s lab, I did not listen much to his advice. I worked hard and long hours on at least six different projects. One by one, each of these projects failed. When the sixth project failed at the end of my first year, I remember walking home that night to my nearby apartment in King’s Cross (it was in the middle of a “red light” zone, which I had not realized when I rented it, so I was often propositioned for sex when I walked home after work at 3 or 4 a.m.). As I walked home that night, the soul-crushing thought occurred to me for the first time in my life that perhaps I was not cut out to be a scientist; perhaps, I was not good enough. This was without doubt the low point of my career. I didn’t yet realize that I had actually learned a lot from all those experiments that didn’t work. I started to listen more to Martin’s advice.

Martin was just starting to become interested in why cells die. Up to that time, it was thought that only certain types of specialized immune cells and neurons die, but Martin was starting to realize that this might be a much more universal property of cells, including glial cells. He proposed a heretical idea: Maybe apoptosis is a universal property of all cell types and that to avoid apoptosis, they needed to be constantly signaled by neighboring cell types not to commit suicide. I thought this was a brilliant idea. I realized that I might be able to adapt the immunopanning method to purify RGCs that I had developed with Linda Chun to purify specific types of glial cells. This would allow me to test their vulnerability to apoptosis as well as to investigate the nature of the cell types and signaling molecules that inhibited this death. A prior postdoc in his lab, Ian Hart, had noticed that OPCs and OLs often underwent apoptosis in culture and another of his postdocs, Sam David, had noticed that OLs underwent apoptosis after a proximal optic nerve crush (when they were deprived of signals from RGC axons).

Given that Martin had already identified and generated antibodies that specifically recognized each of the optic nerve glial cell types, it was straightforward to develop an immunopanning method to generate pure OPCs, pure OLs, or pure astrocytes from the optic nerve (Barres et al. 1992). Consistent with Martin’s hypothesis, I found that each of these cell types, just like the purified RGCs, when placed into serum-free culture, quickly underwent apoptosis. But this apoptosis could be avoided if the purified cells were cocultured with other cell types or specific peptide trophic factors released by these other cell types (Barres et al. 1992, 1993a, 1994a, 1996). For instance, astrocytes strongly promoted the survival (and proliferation) of OPCs and the survival of newly formed OLs, as did platelet-derived growth factor AA (PDGF-AA), ciliary neurotophic factor (CNTF), LIF, insulin-like growth factor 1 (IGF1), or forskolin (which increased their cAMP levels). Moreover, when I looked at a normal developing optic nerve, I found that some newly formed OLs were normally undergoing apoptosis (and then within an hour, their corpses were being phagocytosed by microglia). Our experiments indicated that at least half of the newly generated OLs were undergoing apoptosis during normal development (Barres et al. 1992). When I cut the optic nerve, the mass death of OL lineage cells ensued, but I could prevent much of this death by addition of exogenous peptide trophic factors, such as PDGF and CNTF (Barres et al. 1993b). Altogether these experiments provided strong support for Martin’s ideas and also suggested the model that newly formed OLs competed for limited amounts of trophic factors from axons and that if they did not find an axon to myelinate within several days after generation, as might happen in already fully myelinated territories, they would die (Barres and Raff 1994). We still don’t know what the relevant axonal signals are, but a postdoctoral fellow in my lab, Lu Sun, has recently stumbled on a signaling pathway in developing OLs that very strongly controls their survival and has the potential to lead to these axonal signals (in preparation).

I also found to my surprise that the rate of oligodendrocyte precursor cell (OPC) proliferation in the developing optic nerve was strongly stimulated by the electrical activity of RGCs (Barres and Raff 1992). In playing around with the components of serum-free medium historically used to culture OL lineage cells, I stumbled upon the fact that, in the presence of PDGF to drive OPC proliferation, OLs failed to be generated when a thyroid hormone was left out of the medium (Barres et al. 1994b). It had been known that a thyroid hormone strongly stimulates CNS myelination and that hypothyroid children are hypomyelinated, but the mechanisms responsible had been mysterious. Our findings provided one mechanism by which thyroid hormone could stimulate myelination, and later postdocs in Martin’s lab beautifully extended this work to show that it was highly physiologically relevant.

Altogether, the work I did in Martin’s lab led to seven first author research papers in Cell, Nature, and several other journals, as well as a number of review articles (today a paper in one of these journals usually contains about seven times more data than 30 years ago!). It was a fun time as the methods we developed allowed us to ask some fundamental questions about glial development. Martin and his lab had laid a powerful background that I was able to help build upon. It helped that the field was just beginning to uncover the fundamental peptide trophic factors involved, and many of these were available to us in purified or recombinant form for our experiments. Every night when I went home, typically around 3 a.m. (although on Sunday nights, I usually went home early so I could watch “Dr. Who” at 11 p.m.), I would leave data from my latest experiments on Martin’s desk. When he was in town, the next morning before I got started doing experiments, I would drop by Martin’s office to discuss the latest data. I learned a great deal during these discussions about how to think about questions, results, experimental design, and so on. Like David, Martin was a model of rigor and integrity, and he always had a focus on the important unsolved questions, as well as creative and hypothesis-driven science, and he believed that killing off the hypothesis was always the best way forward. At Harvard, there was often a tendency to ask critical questions at seminars that verged on the destructive, but I learned from Martin that a much better way was to ask constructive questions in the form of suggestions, such as what would happen if you did a particular experiment.

It was amazing that in addition to Martin’s day job, he also had another job that was to serve as a primary coauthor on the book Molecular Biology of the Cell. He was often away at meetings, and whenever he would return from one, he almost always did what he called a “report back.” The night before these reports, he would review the detailed notes he made from every talk and synthesize these notes. In his report back, for each talk, he would tell us (his postdocs) what important question it addressed, what had been known, and then what the new step forward was. These report backs often would last for several hours, but attending one of them was far more educational than actually attending the meeting. Of course, the report backs were as much for Martin as for us, as they enabled him to retain and synthesize new knowledge that ultimately would end up in the next edition of his book. Whenever I came back from the annual Society for Neuroscience meeting in the United States, Martin would always immediately ask me to tell him what the most important thing I learned was. This kept me focused on big picture, question-oriented research.

Once again, I was fortunate to have found such a highly generous and exceptional mentor. In David’s lab, the training I received from Martin has been pivotal to my successful career in science. It is a trend these days to suggest to graduate students that they accelerate their training by skipping their postdocs. I cannot help but feel that those who do this usually are making a big mistake—why be in such a rush that you lose out on the chance to expand your horizons as a scientist? An important thing about postdoc training is that it teaches you that you can start on a new problem and rapidly begin conducting useful experiments. In my experience, those who skip postdocs are generally more risk averse and, decades later, are often still working on almost the same question as they focused on in their graduate work.

Martin and I did have one running argument for the three years that I was in his lab. I claimed that he was away at meetings three out of every four days, whereas he claimed that he was only away one out of four days. We used the same data set—his desktop calendar—to arrive at our conclusions! In my last week in his lab, before he went home one night, I gave him one of my final papers for him to edit. Deep in the methods section, I had buried in the middle of a sentence the following words: “Dear Raff, it has been really wonderful being in your lab even if you have been away three out of every four days.” The next morning, as always, I found the fully edited manuscript awaiting me on my desk. I immediately opened it to that page and found that he had crossed out the three and replaced it with a one. On my last day in London, Martin held a goodbye dinner and, for the second and final time in my life, I got drunk. I had such a wonderful time being in his lab: As with David, I thought of Martin almost as a father, and it was heart-wrenching to leave. But I wasn’t really leaving, as both David and Martin have remained good friends and advisors throughout my career.

Starting Out at Stanford

When it came time to look at jobs—I was now 38 years old—I received wonderful offers from Duke, University of Washington–Seattle, University of California at San Francisco (UCSF), and Stanford. I agonized over which I would accept, making three visits to each school. Having been raised and schooled on the East Coast, I liked the idea of living on the West Coast for a while, and I narrowed down the possibilities to UCSF and Stanford. Each had wonderful faculty, students, and facilities. But there was something about the neurobiology department at Stanford that appealed to me. It was a small faculty that felt almost like a small family, and they placed a high value on quality teaching and mentoring. Clearly this department was a place where research was thriving. Each of the faculty members had identified an important question and had successfully advanced their work with depth. This appealed to me because I knew that understanding the roles of glia would be challenging and that I would need supportive colleagues.

I chose Stanford. I would be the only woman in the department when I started, as Carla Shatz had just moved her lab to University of California at Berkeley, but this did not concern me. After I arrived, I soon learned to my surprise that one of the reasons that I was given the job was because the dean had decided that it was time to better diversify the faculty. Because of a financial downturn, he had closed off all searches unless qualified women candidates were found. The way I learned this was that my chair at the time was telling male applicants that they need not apply unless they had an orchiectomy (i.e., got castrated)! This chair was a little eccentric, so I did not hold that against the department—when I went to say hi to him on my first day at Stanford, he looked at me, scowled, and said only “the clock is ticking” (he was referring to the tenure clock, of course). That was my welcome to Stanford! In his own curmudgeonly way, I think he meant well and, although I was initially quite offended to learn that I had been hired in part because I was a woman, in retrospect I think that this dean did exactly the right thing. In those days, the medical school faculty was nearly entirely male, and they were rarely inclined to hire women without incentive. Twenty-five years later, our medical school faculty has better diversified, but we still have a long way to go.

As I had hoped, the neurobiology department turned out to be a wonderful place to start a lab. My colleagues were all terrific, they provided a generous startup package, and it was easy to obtain great graduate students and postdocs. Within a couple of years of starting my assistant professorship, however, I realized that although I had sufficient lab space to do electrophysiological studies and tissue culture, I needed more bench space to do molecular and biochemical studies. I did not have any benches at all! There were many unused lab rooms on our floor at the time, so I did not think this would be a serious problem. I asked my chair if I could have a bench or two. To my surprise, he said no and that was the end of the conversation. As a talented young woman scientist, I was not infrequently getting inquiries from other universities about whether I might like to move. I always said no, but given the serious space problem, when the next inquiry came along from the neurobiology department at HMS, I decided to take a serious look.

The offer came through in my fourth year as an assistant professor. I was being offered a tenured associate professor position at Harvard, with an endowed chair, a lab three times bigger than my current lab, and a much higher salary. I don’t think that my department ever seriously considered that an offer with tenure would come through because, at the time, Harvard had not tenured anyone in a great many years, and there were only a few tenured women professors in the entire medical school. I suspected, of course, that one of the reasons that Harvard was offering me this position was as an attempt to better diversify their faculty. But I just wanted to do whatever I could to advance my lab’s research program. I left a copy of the offer on my chair’s desk and told him not to bother matching the offer because I had decided to leave (I admit that, by this point, I was quite angry at my department’s failure to give me the couple of benches I had asked for as it was seriously harming my lab’s research). To my great surprise, colleagues in many departments as well as my own learned of the situation and came together quickly to help. Stanford quickly matched Harvard’s offer, and I decided to stay at Stanford. I had given my word to Harvard that I would move if offered the job, but I had not realized it would take two years for a firm offer to materialize, and by that time, an unexpected and serious health issue had emerged.

After being at Stanford for only two or three years, at the age of 40, I had developed breast cancer. I foolishly never did breast self-exams and just happened to feel the hard painless mass in my right breast one day when my hand brushed against it. Before I had the mastectomy, I asked my surgeon if he also would remove my left breast. I told him that I suspected familial breast cancer susceptibility because my mom also had been diagnosed with breast cancer at a similarly young age (this was a few years before the BRCA1/2 gene testing was available). I also told him that I did not feel I should have breasts, mentioning this to someone for the first time in my life. He initially was horrified at the idea of removing healthy tissue, but my oncologist agreed that I might be at genetic risk, and so my surgeon soon agreed. A few years later, testing showed that I indeed had a BRCA2 mutation. By extraordinary luck, however, I had had that mass for several years before the surgery, and none of my lymph nodes or other tissues revealed any sign of metastatic spread. Later studies showed that prophylactic mastectomy greatly decreases the chance of new breast cancers in genetically susceptible patients. I was greatly relieved to be no longer burdened with having breasts. Doctors, nurses, and friends all encouraged me to have breast reconstruction surgery, but there was no way I was going to let anyone put breasts back on me. I did not yet understand that I was transgender, but I felt enormous relief at having a body that more closely resembled my internal male identity.

I faced one other unexpected obstacle as an assistant professor. I could not win an NIH R01 grant no matter how hard I tried, although I won many junior investigator awards. Back in the mid-1990s, NIH R01 grant applications were 25 pages single spaced (not counting all the administrative parts) and very time-consuming to prepare. It seemed there were several issues as to why I could not win a grant. The first was that there were rules to proper construction of such a grant, but I had no idea what they were, and it did not occur to me to ask anyone. The second problem was that I was starting completely new projects in my own lab. I wanted to move from glial electrophysiology and glial development to investigate actual glial function. But I had no idea what these functions were yet, and I had insufficient preliminary data to support my proposals. I eventually was able to overcome these two problems as I got advice from colleagues and as my lab generated more and more preliminary data. But I was to learn that there was yet another problem that was much harder to surmount. My reviewers simply did not believe that glial cells served any roles in the brain beyond their traditional support roles. Even when my lab had published two papers in Science demonstrating profound effects of glia in inducing both synapse formation and function, my grant reviewers still insisted there was no way that this could be true. Grant application after grant application continued to be rejected. And they were not just rejected, but they were spit on and stomped upon. In the early 1990s, NIH agencies, including NINDS, the National Institute of Neurological Diseases and Disorders, was funding only proposals that scored in the top 7 percent or so. But my scores were usually higher than 50 percent (i.e., they were usually triaged and not even discussed), although after about seven attempts I had gotten up only to 43 percent.

Things started to get a bit stressful. My lab was running out of funding from junior investigator awards and setup funds. My “clock is ticking” colleague told me that my failure to get a grant was highly embarrassing and that I should not tell anyone about the low scores I was getting. I worried that perhaps my colleagues were thinking they had made a mistake after all in hiring a woman. I started to seriously consider dropping out of academia. With my clinical training, I could easily go back to neurology practice or do research in a biotech startup or pharmaceutical company. Indeed, companies were not infrequently approaching me about the possibility. But I really wanted to understand glia, so I held on. Soon, to my great relief, two unexpected miracles happened that solved the problem for me and put the fun back into doing science.

The first was that one day I got an unexpected phone call from a young program officer at NIDA (the National Institute for Drug Addiction) named Jonathan Pollock. Jonathan and NIDA were trying to understand the neurological mechanisms that lead to long-lasting craving for addictive drugs, even when drug use had been stopped. He happened to come across the Science paper mentioned earlier in which we had shown that neurons had little ability to form synapses unless astrocytes were present. This suggested the possibility to Jonathan that addictive drugs might act on astrocytes, rather than neurons, to enhance their synapse-inducing ability. This might create extra synapses in a circuit that might leave a long-lasting effect on circuit function. He told me that he noticed in the acknowledgment section of the paper that I had not mentioned NIH funding. Was it possible that I did not have NIH funding for this “beautiful” work? I started to explain to him about my difficulty with grant funding, and he quickly pulled up from his computer database that I had recently obtained a score of 43 percent on a grant submitted to NINDS. NIDA Council was about to meet in a week, he told me, and he could not promise anything, but if I would write him a paragraph about the relevance of our work to addiction that he would see what he could do. One week later, he called me to tell me that he had transferred the grant to NIDA and that it was fully funded.

That was 20 years ago, and ever since, he has looked after not only my lab but also those of my trainees who have continued this work in their own labs. It is fair to say that understanding the active roles of glia at synapses has advanced in large part because of his support. Another program officer at NEI (the National Eye Institute), Michael Oberdorfer, similarly provided advice and help in obtaining funding for my lab’s work on RGC axon regeneration. Without Jonathan and Michael’s incredible support, I certainly would have dropped out of academic research as an assistant professor. Once my lab was established and we had generated much more preliminary data, it became easier to obtain NIH support. But those first five years were tough. I am glad that NIH recently started new mechanisms to specifically help support research of new and early investigators. Without these mechanisms, in these competitive days, I fear that we could lose many talented young scientists. The NIH is a great institution. It may not be perfect, but the difficulty of the Institute’s job is hard to overstate. There is never sufficient funding for all the deserving proposals, so somehow their officials must navigate a difficult path to ensure that it is fairly and appropriately distributed. They do a magnificent job.

In those first few years of my lab when I was having so many grant rejections, I took it personally. But now after a long career, I can look back on it with more detachment and see that this may be the way it always is when young scientists start with new ideas, often seeing the same old things in different ways. It is not personal but just the usual resistance that new ideas are met with, particularly when the investigator is young and not yet independently established. Young investigators need to hang in there and realize that things will eventually get better!

One more unexpected miracle greatly helped my lab. After I had had a lab for only about five years, I received a phone call from Vincent Coates. Vincent was a highly successful engineer who had made many brilliant inventions in nanotechnology. He founded and ran a successful Silicon Valley company called Nanometrics, based on his invention of the first scanning electron microscope that allowed silicon chip quality to be assessed. He and his wife Stella wished to philanthropically support neuroscience research relevant to neurodegenerative disease. He had read about some of my lab’s work, and he wanted to find out more. Vince visited my lab, and I told him about the work we were doing on glial cells and how I thought it might be relevant to neurological disease. He and his wife made a generous gift to my lab and have continued to support our work ever since. Alas, Vince passed away a few years ago from Alzheimer’s disease, and I am sad that he did not live to see the way that the work he supported in my lab has indeed led to new drug targets for treating neurodegenerative disease.

In addition to the Coates’s support, over the past 25 years my lab has been the lucky and very grateful recipient of funding from several other philanthropic foundations, including the Fidelity Foundation, the Sheldon and Miriam Adelson Medical Research Foundation, the JPB Foundation, the Christopher and Dana Reeve Foundation, the Cure Alzheimer’s Disease Foundation, and several others. Without their generous support, much of my lab’s work, particularly the most high-risk work we have done, would not have been possible. It has been a great privilege to know these donors and observe their generosity firsthand. Their generosity not only has helped fund my lab’s research and many others, but also has made possible the training of the next generation of young scientists who will continue this research. These wonderfully generous folks have greatly stimulated my own philanthropic interests. I have bequeathed my entire estate to my department at Stanford. I hope very much that it will help our faculty sustain their cutting-edge research.

Transitioning from Barbara to Ben

After about four years at Stanford, I was promoted to associate professor with tenure. One morning, I was reading a local newspaper, the San Francisco Chronicle, and came across a four-page article about Jamison Green, a female to male transgender person and transgender rights activist. He was one of few openly transgender people at the time. I read this article with astonishment. In it, Green described in detail his personal experiences with gender identity and to my surprise they mirrored my own very closely. This was the first time that I understood that other people had the same gender identity discordance that I had. It was also the first time that I had heard the word transgender. The article mentioned the clinic of Don Laub, a Stanford plastic surgeon who was a Bay Area pioneer in helping transgender people. I started to read more about other transgender people and realized that I was likely transgender. I made an appointment at his clinic to be evaluated. It was the first time I was able to discuss my gender confusion with anyone. I met with Dr. Laub, as well as with an experienced psychologist who had worked with him for many years. The clinic concluded that I was transgender and offered to help me to transition from female to male.

At this time transsexuality was still listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM), a classification of mental disorders published by the American Psychiatric Association, as a mental illness. Proponents of this view argued that it was wrong and harmful to help people change their sex. Did I have a mental illness? I did not think so. Moreover, reflecting on my experiences during psychiatry rotations during my neurology training days, my impression was that the incidence of serious mental illness was likely far higher in psychiatrists than in transgender people. So, I did not see why they should get to categorize me as mentally ill! Moreover I had been exposed to a testosterone-like drug during fetal development, and my masculinization was consistent with relevant animal and human data.

I felt an irresistible desire to transition from female to male from the moment I was offered that possibility. But I thought about it for several weeks because I was worried about the repercussions for my career. Even though I was already tenured and so did not have to worry about being fired—a frequent outcome for transgender people in other professions at the time (in many states, transgender people are still not legally protected from being fired)—there was much to consider. Not only did I not know of any successful transgender scientists but also I worried if I transitioned, would I be able to get grants anymore (it was already nearly impossible!)? Would new students or postdocs wish to join my lab? Would my colleagues reject me? Would I be invited to meetings and so forth? Reading about the experiences of other folks in other professions who had transitioned, I strongly feared that a transition would very likely end my career. For about a week, I was almost unable to sleep from the stress as I pondered whether I should transition or commit suicide. I finally decided to open up to three friends whose opinion I valued very much: David Corey, Martin Raff, and Louis Reichardt. For the first time, I opened up to them about my gender confusion and told them that I was considering changing sex. Did they think that the repercussions would be so bad that it would harm my career? To my great relief, all three were immediately and strongly supportive. On the basis of their support, I decided to transition. I sent out the following letter to my colleagues, family, and friends late in December of 1997 to let them know of my gender dysphoria and my decision to transition. My letter follows:

Dear friends,

I am writing to disclose a personal problem that I’ve been struggling with for some time. It is important for me to talk about it now in order that I can finally move forward.

Ever since I was a few years old, I have had profound feelings that I was born the wrong sex. As a child I played with boys’ toys and boys nearly exclusively. As a teenager, I could not wear dresses, shave, wear jewelry, makeup, or anything remotely feminine without extreme discomfort; I watched amazed as all of these things came easily to my sisters. Instead I wanted to wear male clothing, be in the boy scouts, do shop, play sports with the guys, do auto mechanics, and so forth. Since childhood, I have been ridiculed and shunned by women and by men. At the age of 17, I learned that I had been born without a uterus or vagina (Mullerian agenesis), and that I had been exposed prenatally to masculinizing hormones. Despite plastic surgical correction of my birth defect, throughout my life I have continued to have intensely strong feelings of non-identity with women. Perhaps most disturbingly I feel that I have the wrong genitals and have had violent thoughts about them. My lack of female identity was brought home vividly to me recently after having bilateral mastectomies for breast cancer. This surgery, rather than being an assault on my female identity as it was for my mother, felt corrective as my breasts never seemed like they should be there anyway; the thought of reconstructive surgery has been repellant to me. Since the surgery, people who do not know me often call me sir, but that doesn’t bother me either. It is not that I wish I were male; rather, I feel that I already am.

It would be difficult to describe the mental anguish that this gender confusion has caused me. Although I have never been clinically depressed, it has been the source of strong feelings of worthlessness, intense isolation, hopelessness, and self-destructive feelings. I have never been able to talk to anyone about it because I felt so ashamed and embarrassed by it. It seemed that it must be my fault, that somehow I should be able to make myself be a woman. This is how things stood until two months ago, when I read in the newspaper about the existence of a gender clinic at Stanford. They found that I have a condition known as gender dysphoria. To my amazement, I learned that I am not alone and that my story is stereotypical of all of those who have this condition.

So what is gender dysphoria (also known as being transgendered or as gender identity disorder)? Those who have it feel from childhood a strong mismatch between their anatomical sex and their brain sex (gender identity). The cause is unknown but is thought to be biological, as some cases are clearly associated with a history of hormone exposure during development. Although it is not treatable by psychotherapy, the dysphoria is substantially lessened by a change in gender role. Treatment with testosterone induces normal male secondary sexual characteristics within 6 to 12 months. Most patients also opt for mastectomies, which I have already had, and hysterectomy, which nature has already done for me. In my case, testosterone treatment would have the added benefits of substantially lowering my chance of new or recurrent breast cancer, because it lowers estrogen levels, and would block the osteoporosis and menopausal symptoms that will otherwise follow when I have my ovaries removed because of my cancer susceptibility mutation.

After much reflection, I have made the decision to take testosterone. I will thus become a female to male transsexual. This has been a difficult decision because I risk losing everything of importance to me: my reputation, my career, my friends, and even my family. Testosterone is a far from perfect solution; I’m still not going to be “normal” and social isolation will undoubtedly continue. But testosterone treatment offers the possibility that for the first time in my life I might feel comfortable with myself and not have to fake who I am anymore. I know that I am making the right decision because whenever I think about changing my gender role, I am flooded with feelings of relief. I will begin taking testosterone in February. A change in my appearance will not be visible for several months. By summer, I will begin to dress in men’s clothes and will change my name to Ben. Throughout this process, I will continue to work normally and to conduct myself in all ways as usual (except that I will only use single-occupancy bathrooms). Although the idea of my changing sex will take some time for you to get used to, the reality is that I’m not going to change all that much. I’m still going to wear jeans and tee shirts and pretty much be the same person I always have been—it’s just that I am going to be a lot happier.

Many transsexuals change jobs after their “sex change” in order to retain anonymity, but anonymity is obviously not an option for me—nor is it one I desire. I am tired of hiding who I am. More importantly I owe it to others who unknowingly endure this condition, as I did, to be visible. Despite my 7 years of medical training, which I undertook to understand what was wrong with me, until 2 months ago I had never heard of gender dysphoria (oddly I somehow picked the right organ to study!). Had it not been for the transsexual who allowed himself to be the subject of the news piece I read, I would still not know about it. Sure I knew that sometimes there were male to female transsexuals but I had thought that these people were perverts. I am not a pervert; I don’t seek pleasure, only relief from pain. Most transsexuals hide because of shame and fear, perpetuating ignorance and oppression about their condition. Their suicide rate is so high that some experts have called gender dysphoria a lethal disease. This is why I cannot hide.

In my heart I feel that I am a good scientist and teacher. I hope that despite my transsexuality you will allow me to continue with the work that, as you all know, I love. I am happy to answer any questions.

Sincerely,

Barbara A. Barres

Despite David, Martin, and Louis’s support, sending out this letter was still very scary. But I found that my family was immediately supportive and so were all of my colleagues. I heard back from many of them very quickly. Here is the very first response that I received (from Chuck Stevens at Salk, a colleague I had long admired for his science and his wonderfully generous mentorship of so many young scientists):

Dear Barbara,

Thanks for the letter and the personal info. I have always been fond of the person in there and the gender makes zero difference to me—I expect you will find the same with all of your friends. Let me know when to change to “Ben.”

Best regards,

Chuck

All of the other responses I received were similarly supportive. And there it was: This shameful secret I had held inside of me for 40 years was out, and within a few months, I had transitioned to Ben simply by taking testosterone (mastectomies had already been done, but I did have my ovaries removed soon thereafter as they were a cancer risk because of my BRCA2 mutation; the testosterone prevented menopausal symptoms). My career went on as before without a hitch. I am not aware of a single adverse thing that has happened to me in the past 20 years as a result of my being transgender. But there was immediate relief of all emotional pain as a result of my transition. Never did I think of suicide again, and I felt much happier being myself (Ben), no longer having to pretend to be a woman. It is hard to explain how much relief I felt and how much happier I became. It was as if a huge weight had suddenly been lifted from my shoulders.

I should also say that Stanford as a whole was very supportive, including the provost, dean, and all my faculty colleagues. To be honest, I feared that some of the faculty in my department might be very embarrassed by my transition. Back then the Internet had only recently come into existence and there was still much ignorance about transsexuality. But if they had any qualms, they did not mention them and they were all completely supportive (even the curmudgeonly “clock is ticking” guy!). I would like to think that I eventually accomplished enough to fit in. I was elected to the National Academy of Sciences (NAS) in 2013. I was proud to be the first transgender scientist to be elected to NAS and upset when the Academy president refused to mention this in the NAS press release on the grounds that the Academy “had to deal with religious people.” I was deeply disturbed by this as it denies lesbian, gay, bisexual, and transgender (LGBT) people proper attribution for their accomplishments, particularly given the great need of LGBT students to be aware of successful role models. Fortunately, other news writers soon mentioned it in pieces about me.

How did taking testosterone affect me? It is powerful stuff! There were some of the expected side effects, such as increased sex drive for a while (almost like going through a second puberty), and the development of a male hair pattern. I was delighted to be able to grow a mustache and beard, but less thrilled with the rapid onset hair loss that began almost immediately upon start of testosterone (my photograph on page 1 shows the extent of these effects). All cellulite quickly disappeared. Fat distribution changed from hips and buttocks to abdomen (but a lot stayed everywhere else, too). I became much stronger even without doing any exercise. I had never been able to do a single pushup as Barbara, but after about six months of taking testosterone, I noticed that my triceps were beefing up. To my surprise, I was able to do 10 pushups (and soon 30 pushups, although I never really worked at it). I did not particularly notice any change in mathematical, spatial, or verbal abilities. I did notice on a test that was given to me before and after testosterone that my verbal abilities seemed a little worse, and my spatial abilities seemed a bit improved, but I still get lost every time I get in a car. Perhaps the most surprising and unexpected effect though was that I largely lost the ability to cry. Before testosterone, I cried easily, and often cried myself to sleep because of the gender anguish. But after testosterone, I found that I was almost entirely unable to cry any more. In response to some very strongly sad stimulus, perhaps I would shed a tear, but the feeling would almost instantly pass. Many other transgender men have told me this has happened to them as well, whereas transgender women gain the ability to cry much more easily.

In 1997, when I transitioned, it was thought that only 1 in about 20,000 people were transgender, but in 2017, it is now thought that at least 1 in 200 people are transgender. LGBT people are often high achievers. Many LGBT people in my generation share in common growing up with a shameful secret and consequent low self-esteem. Perhaps this may drive us to work hard to succeed to prove our self worth. Things are changing fast for transgender people. The Internet has enabled relevant information to be easily researched and accessed, and the public is now being rapidly educated. Television shows often feature transgender characters, and they can now serve openly in the military. There are still some battles being fought, such as protections to prevent being fired for being transgender and bathroom protections, but the public is mostly sympathetic to and supportive of LGBT people, so I believe these battles will soon be won. Most important, clinics are popping up to help trans children. As a result of public education, trans kids often self-identify, or are identified by their parents, even at grade school age. As they approach puberty, if their transgender identity persists, these kids can be treated with puberty blockers so they do not undergo permanent bodily changes inconsistent with their gender identity. Then when they are of age (at about 16 years old) they can make the decision about whether they wish to transition. Up until now at least 40 percent of transgender people attempt suicide. But I hope that these kids who are able to transition early will be spared the anguish of growing up in the wrong gender with the wrong body, will be able to have more normal social and romantic interactions, and will not have to keep shameful secrets from their families. How I envy them!

I am happy to be an openly transgender scientist and to serve as a role model for young LGBT scientists. I hope that I have helped ease their way a little bit. LGBT students and postdocs at Stanford and other institutions frequently contact me to discuss whether or not to be open in their applications to various training programs. I always counsel them to be open about who they are, as it seems to me that presently the advantages far outweigh the risk. The vast majority of academics are highly supportive. It is difficult to live life in a closet. It does not make sense to do this because of an occasional bigot. I have yet to have anyone tell me they regretted their decision to be open.

Development of Methods to Purify and Culture CNS Neurons

In thinking about what projects to work on as I got my new lab started at Stanford, I felt that figuring out how to keep CNS (central nervous system) neurons alive in culture was of high priority. If successful, this would provide an important tool for investigating neuron-glial interactions to better understand the functions of glial cells. (RGCs made the most sense to start out with as I had already developed a method to highly purify them to greater than 99.5 percent purity by immunopanning from cell suspensions prepared from postnatal rat retinas. But oddly, unlike peripheral nervous system (PNS) neurons whose survival could easily be promoted in culture by specific peptide trophic factors (NGF for sympathetic neurons, BDNF for nodose ganglion neurons, CNTF for ciliary neurons, etc.), a wide variety of peptide trophic factors alone or combined was frustratingly unable to promote RGC survival.

Anke Meyer-Franke joined the lab as one of my first postdoctoral fellows and decided to tackle this problem. Neurotrophic factors were just being identified and becoming available in recombinant or purified form. She tried testing a large variety of these peptide trophic factors individually and in combination on purified rat RGCs in serum-free culture, but always the purified RGCs quickly died of apoptosis over a one-day period. It had been reported that the survival of some types of PNS neurons could be promoted by intracellular cAMP elevation or by K⁺-induced depolarization. Anke tried these also but once again found that they did not promote RGC survival. However, when she combined several peptide trophic factors together—BDNF, CNTF (or LIF), and IGF1 (or high concentrations of insulin, which activates IGF1 receptors)—together with either cAMP elevation (using forskolin or chlorphenylthio-cAMP) or K⁺-induced depolarization, she found that about 65 percent of the RGCs survived for weeks or longer, extending beautiful dendrites and axons (Meyer-Franke et al. 1995). Anke found that this survival effect was mimicked exactly by culture of the RGCs on an astrocyte-feeding layer or just in astrocyte-conditioned serum-free medium. OL-conditioned medium did not promote survival of the RGCs on its own, but Anke found when she combined it with her BDNF/CNTF/IGF1/forskolin cocktail, that RGC survival approached 80 percent. We still do not know the identity of the trophic signal from OLs, but we know that it is likely relevant in vivo because we observed that in mutant mice that lack OLs, apoptotic RGCs are observed in the adult retina long after their period of normal cell death in the first week postnatal.

Anke wondered why the RGCs did not directly respond to BDNF when in side-by-side experiments in which she purified nodose ganglion neurons (a type of BDNF-responsive PNS neuron), BDNF was fully sufficient by itself to promote their survival. We worked with Louis Reichardt’s lab at UCSF to investigate where the BDNF receptor, TrkB, was localized. Anke found that although RGCs made TrkB mRNA and protein, it was not present on the RGC surface but rather in an intracellular store. When she cultured the RGCs in the presence of the cAMP elevator forskolin or K⁺ elevation (which she showed worked by elevating intracellular cAMP within the RGCs), she was able to use surface biotinylation experiments to show that TrkB was present on the RGC surface, inducing BDNF responsiveness (Meyer-Franke et al. 1998). Subsequently many other types of CNS neurons have been shown to respond similarly (Goldberg and Barres 2000). This was a remarkable and interesting discovery as it reveals a fundamental difference between PNS and CNS neuronal responsiveness to peptide trophic factors, with PNS neurons intrinsically programmed to be responsive, but CNS neurons requiring extracellular signaling to be responsive. This may well be important in understanding the plasticity of neurons in the CNS. In fact Jeff Goldberg in my lab, while studying the mechanisms that control RGC axon regeneration, made the remarkable observation that the rate of axon growth in response to BDNF was profoundly enhanced by almost tenfold when the RGCs were stimulated at physiological rates of electrical activity by growing them on silicon chips (Goldberg, Espinosa et al. 2002). He later showed in his own lab that this effect was mediated by elevation of intracellular cAMP levels, and he is currently investigating the relevant mechanisms. Andy Huberman recently beautifully extended the significance of this work in his own lab by showing that RGCs regenerate their axons in vivo far more robustly and, for a long distance, all the way to their targets when they are electrically simulated either by visual stimulation or chemogenetic manipulation (Lim et al. 2016). We still do not know, however, what the physiologically relevant signals are that promote RGC (or other types of CNS neurons) survival in vivo. RGC number is not appreciably affected in mutant mice that lack BDNF, CNTF or LIF, or IGF1. Next we will come to the more likely trophic signal.

When Martin Gartz Hanson was in the lab as a “post bac” for a couple of years, he wanted to highly purify and culture rat embryonic spinal motor neurons, another type of CNS neuron. He adapted a previous method of Chris Henderson’s and found that while many different peptide trophic factors would individually promote partial survival, when he cultured them in cAMP elevators, such as CPT-CAMP alone, he could promote the long-term survival of the majority of these spinal motor neurons (Hanson et al. 1998) just as had been shown for purified PNS neurons by Gene Johnson and others many years before. Brad Zuchero in my lab later modified our immunopanning protocols to very highly purify DRG neurons for studies of myelination. All of our lab’s methods to purify and culture neural cell types have been collected into a Cold Spring Harbor Laboratory manual (Barres and Stevens 2014) with step-by-step protocols.

I think that many neuroscientists think that the survival signaling mechanisms that promote CNS neuronal survival is a question that largely has been solved since the pioneering work of Rita Levi-Montalcini and so many others, who showed that single peptide trophic factors are necessary and sufficient to promote PNS neuronal survival. We found that brain vascular cells secrete trophic activity that powerfully induces growth of CNS neuronal axons (Dugas et al. 2008), although it was not sufficient to promote their survival. Gary Banker’s group made an important observation more than 40 years ago when they discovered that astrocytes secrete signals that powerfully promote the survival and growth of hippocampal neurons, and others have gone on to show that many types of CNS neurons also can be supported by astrocyte secretions. And the ability of astrocytes to promote neuronal survival is likely critical in vivo and not just in vivo: In mutant mice in which neurons are generated but then astrocytes fail to be generated, CNS neurons quickly die. Identifying the astrocyte-secreted trophic factors for neurons is a crucial and unsolved question in neurobiology. Though we have been able to take advantage of RGCs, which we can culture apart from glia in serum-free culture, and therefore study their interactions with glia (many of which I will come to shortly), it has long been frustrating that we cannot do similar experiments with hippocampal neurons or other types of CNS neurons.

Therefore, we decided to biochemically tackle the problem of the molecular identity of the neuron survival signals secreted by astrocytes. As they were soluble, we thought this should be straightforward. Madolyn Rogers began this work in my lab when she was a graduate student. It turned out to be very tough work, and soon Madolyn realized the reason why: At least two different activities were required to be present together for the hippocampal neurons to survive. One of these activities was a large molecule, more than 100 kD, whereas the other molecule was much smaller, perhaps only about 500 kD. When Madolyn finished in the lab, Jennifer Zamanian continued this project. To our surprise, Jennifer’s experiments have revealed that the trophic activity that astrocytes secrete is entirely made of sugar chains, either chondroitin sulfate or heparin sulfate glycosaminoglycan chains (Zamanian et al. 2017). These chains are bound to a large variety of proteoglycans that are made and secreted by astrocytes. Unfortunately, the addition of CS or HS to hippocampal neuron culture medium is not sufficient by itself to keep these neurons alive; they must be combined with the small molecule that we have not yet biochemically identified. As soon as we identify that, it should finally be possible to have a completely defined serum-free medium with which most types of CNS neurons can be cultured. This will enable many interesting studies, including a much better understanding of the nature of neuron-glial signaling mechanisms and their functional significance. It is remarkable that glycosaminoglycans, and not peptides or protein, are able to so powerfully promote CNS neuronal survival. This raises the question of the relevant chondroitin sulfate proteoglycan/heparin sulfate proteoglycan (CSPG/HSPG) receptor, which will be another important question for future studies.

When Ye Zhang was in my lab, she took advantage of the methods that we have developed to culture highly pure neurons, astrocytes, and OLs in a serum-free medium to ask the question of what small (not protein) molecules they are secreting using a metabolomics approach. These were pilot experiments, but it was enough to show that each of these cell types are secreting a large variety of molecules, some very highly, and most not yet identified or characterized functionally. It is very likely that many interesting and important neuron-glial signaling processes are happening that we as yet have no clue of or their functional significance in health and disease.

Why Do CNS Neurons Fail to Regenerate Their Axons after Injury?

The methods that we developed to purify and culture RGCs and optic nerve astrocytes and OLs enabled us to branch out into some new questions. One fascinating question is why axotomized PNS neurons can survive and regenerate their axons, where axotomized CNS neurons die and fail to regenerate their axons. One claim at the time I started my lab back in 1993 was that RGCs were being killed by glutamate excitotoxicity. Several other labs had found that when they injected glutamate or various glutamate receptor agonists into the retina that RGCs would quickly die. But we had found in our culture experiments that glutamate helped to depolarize RGCs and actually promoted their survival; we could never kill RGCs by dumping glutamate or glutamate agonists on them in culture. Erik Ullian in my lab investigated what happened when he injected glutamate agonists into the retina. He found that the RGCs were completely invulnerable in contrast to many previous reports. In fact many cells in the RGC layer were rapidly killed, but Erik showed that these were entirely displaced amacrine cells (Ullian, Barkis et al. 2004). Remarkably, he found that amacrine cells and RGCs had the same amplitude glutamate currents, yet one cell type was clearly more vulnerable to excitotoxicity. This remains an important unanswered question as to what mechanisms make some neuron types more vulnerable to excitotoxicity than others.

Another idea for why RGCs might die after axotomy, in analogy with what was known about PNS neuronal survival, was that the axotomy might block retrograde trophic signaling from target-derived trophic factors. Shiliang Shen, a research associate in my lab, decided to investigate this possibility. Other labs had found that simply injecting trophic peptides such as BDNF or CNTF was not sufficient to promote the survival of most axotomized RGCs. However, Shiliang reasoned that, as in culture, single peptide trophic factors might not be sufficient. Rather, several trophic factors such as BDNF, CNTF, and IGF1 might need to be combined with a drug that would make RGCs traffic their trophic receptors to their cell surface, just as we needed to do in culture to keep RGCs alive. In fact, Shiliang showed axotomized RGCs quickly lost their trophic responsiveness but that when BDNF and CNTF were injected into the retina together with CPT-cAMP, a cell-permeable cAMP analogue that is not digested by phosphodiesterases, the survival of axotomized RGCs was powerfully promoted (Shen et al. 1999).

As noted, however, it is far from clear that target-derived signaling is normally important for the survival of RGCs in vivo. In fact RGCs are surrounded by astrocytes and astrocyte-like Muller glial cells, which likely make the critical trophic signals that keep the RGCs alive. Axotomy should not interrupt that flow of trophic signals within the retina. It is possible that RGCs die because after axotomy, they become electrically silent (either because channels and receptors are down-regulated or because their intraretinal synaptic contacts are stripped off or degenerate) and their intracellular cAMP levels fall, and they lose responsiveness to the astrocyte-secreted factors. As we shall come to later, the death of RGCs after axotomy turns out not to be caused by trophic deprivation-induced apoptosis but rather because the RGCs are murdered by nearby reactive astrocytes.

Nonetheless, having found ways of keeping RGCs alive after axotomy, either by expressing genes that block apoptosis such as bcl2 or by using the trophic approach reported by Shen et al. (1999) or simply by studying their axon regeneration in adult rodents where it takes several weeks for all the RGCs to die, it is possible to next explore the mechanisms preventing successful axon regeneration. Many previous studies have called attention to the role that inhibitory signals from reactive astrocytes and degenerating myelin play, which cause axonal growth cones to collapse and stop growing. Certain forms of CSPGs on astrocytes and Nogo in degenerating myelin are some of the inhibitory molecules that have been identified. Jeff Goldberg in my lab also identified semaphorin-5A as an oligodendrocyte inhibitor of axon regeneration (Goldberg et al. 2004) and stunningly Alissa Winzeler and Wim Mandemakers in my lab identified the major myelin lipid sulfatide as the first lipid myelin-associated inhibitor of axon outgrowth (Winzeler et al. 2011). They found that axotomized RGCs regenerate significantly better in mice whose OLs lack this lipid. The relevant axonal receptor has not yet been identified and is an important question for future studies.

One of the reasons that PNS axons are better at regenerating is that degenerating myelin is rapidly cleared after axotomy, whereas that does not happen in the CNS, where degenerating myelin along with its inhibitory cues may persist for a decade or more after injury. Several young scientists in my lab have investigated the mechanisms of PNS myelin clearance with the hopes that this might lead to new insight into why myelin debris clearance occurs so slowly if at all in the injured CNS. Mauricio Vargas wondered whether antibodies might play a role in clearing degenerating PNS myelin because the brain–blood barrier (BBB) might be prevented from helping clear CNS myelin. In a series of clever experiments, he took advantage of the JHD strain of mice that lack B cells so are unable to make any antibodies at all (Vargas et al. 2010). He found that these mice display a significant delay in macrophage influx, myelin clearance, and axon regeneration. He could restore rapid clearance of myelin debris by passive transfer of antibodies from naïve WT mice or by an anti-PNS myelin antibody. His findings showed that degenerating PNS myelin is targeted by preexisting endogenous antibodies and demonstrate a role for immunoglobulin (Ig) in clearing damaged myelin during healing. This finding also suggests that the immune-privileged status of the CNS may contribute to failure of CNS myelin clearance and axon regeneration after injury. As we shall see, other CNS myelin clearance mechanisms also fail after CNS injury. I think that Mauricio’s observations suggest a reason why Nogo antibodies delivered into the injured CNS by Martin Schwab’s lab have consistently been found to promote axon regeneration better than occurs in mutant mice lacking Nogo. The Nogo antibodies may well be helping to promote myelin debris clearance by microglia or macrophages. It may be that any antibody that opsonizes degenerating myelin as Nogo does would be similarly able to help promote myelin debris clearance. To my knowledge this possibility has not been investigated yet.

Mauricio’s experiments provided insight into how peripheral macrophages help to clear degenerating PNS myelin but, as his and other experiments had shown, the Schwann cells also phagocytose degenerating myelin, but the mechanisms were not known. To better understand how Schwann cells clear myelin debris, Amanda Brosius-Lutz in my lab investigated this question. She developed methods to highly purify Schwann cells both before and after nerve crush, and then performed RNAseq experiments to identify candidate phagocytic pathways. She found that the major pathways that Schwann cells use to clear myelin debris are the Mertk and Axl pathways (Brosius-Lutz et al. 2017). Purified Schwann cells in culture robustly engulf myelin debris, but Schwann cells that lacked both of these phagocytic receptors were unable to clear myelin debris at all. In vivo, the rate of myelin clearance was delayed when Schwann cells lacked these pathways, although ultimately myelin was cleared, presumably by macrophages and other immune system cells that serve a redundant role. Amanda also showed that astrocytes in vitro robustly engulf myelin debris using these same phagocytic pathways, raising the question of why they fail to do so in the CNS in vivo after axotomy. As we will see, it turns out that reactive astrocytes induced by this type of injury lose their ability to phagocytose. As microglia have minimal ability to phagocytose myelin debris, and macrophages cannot enter distal to a nerve crush (they enter only at sites of BBB breakdown), and as reactive astrocytes lose the ability to phagocytose myelin debris, it is now clear why the CNS fails to clear myelin debris. But these findings also suggest that if drugs could be developed that restored phagocytic ability to these reactive astrocytes, perhaps by reverting them back to normal astrocytes, that myelin debris clearance might well be induced after CNS injury.

As discussed, much attention has been paid to the extrinsic mechanisms that inhibit axon regeneration, but when Jeff Goldberg was in my lab he wondered whether intrinsic mechanisms might come into play as well. Specifically, he wondered whether CNS neurons might lose the intrinsic capacity to regenerate as they aged, after development was over. Other investigators had shown that embryonic neurons transplanted into adult brain had substantial capacity to regenerate a long distance even through myelin pathways. So Jeff purified RGCs from different aged rats from embryonic day 17 (E17) all the way to adult (P60) rats and measured the rate of their axon growth in response to BDNF signaling in serum-free medium. He found that embryonic RGCs rapidly extended their axons until postnatal age 0, around the time when they normally reach their targets. But remarkably, when he cultured E17 RGCs in serum-free culture, they continued to rapidly extend axons for weeks, long past the time when they would have slowed down in vivo. When he cultured P0 or older RGCs for prolonged periods, however, they never regained the ability to grow rapidly again. He reasoned that some cell–cell interaction around P0 must trigger the RGCs to irreversibly lose their growth ability. Surprisingly, it was not target innervation that did this, but rather he found that amacrine cells signal neonatal RGCs to undergo a profound and apparently irreversible loss of intrinsic axon growth ability. Concurrently, he found that retinal maturation triggers RGCs to greatly increase their dendritic growth ability (Goldberg, Daneman et al. 2002). His findings provide strong evidence that adult CNS neurons fail to regenerate not only because of CNS glial inhibition but also because of a loss of intrinsic axon growth ability. By performing gene profiling on RGCs of different embryonic and postnatal ages (Wang et al. 2007), he identified some interesting gene candidates and is presently investigating these in his own lab. It is likely that epigenetic changes underlie this irreversible switch.

Of course, the critical question is even if adult RGCs can be induced to regenerate their axons, will they be able to find their appropriate target regions and form functional synapses to restore visual function? When Andy Huberman was in my lab, he took a variety of clever approaches to identify transgenic mouse lines, many made by the Gensat Project of Nat Heintz at Rockefeller University, which expressed green fluorescent protein (GFP) just in subsets of RGCs. There are at least 20 different subtypes of RGCs and Andy was able to identify mouse lines in which about 5 of these types were specifically labeled. These mice provided a powerful tool to investigate the specific target regions of each RGC subtype, to study how each of these subtypes developed their connections, and the molecular mechanisms responsible (Huberman et al. 2008, 2009; Cheng et al. 2010; Osterhout et al. 2011). Having identified the normal target regions of each of these RGC subtypes, in his own lab (and in other labs as well), he has taken wonderful advantage of these lines to demonstrate that they can indeed regenerate back to their appropriate target regions, make functional connections, and restore visual function. For all these reasons, the possibility that CNS function may be repaired after injury is increasingly plausible, causing Jeff Goldberg, Andy Huberman, and others to propose to cure blindness by eyeball transplantation. Much work is left to be done to make this a reality.

Understanding OL Development, Node of Ranvier Formation, and Myelination

Having figured out how to purify and culture RGCs, we next wondered whether we could get them to myelinate with OLs. Studies of CNS myelination have long been hampered by the lack of a rapid and robust myelinating culture system. We found that when we added OLs to the RGC cultures, although we did not get any myelination (more about that later), to our surprise, beautiful regularly spaced clusters of sodium channels appeared along their axons, even when there was no contact between the RGCs and the oligodendrocytes, because we used conditioned medium. This was a surprise because in the PNS, it had been shown that direct Schwann cell contact was needed to induce nodal clustering of sodium channels, and at the time, it was thought that similar astrocyte contact of nodes was needed in the CNS to induce sodium channel clustering. But there were no astrocytes present in our RGC-OL cultures. We found that OLs were secreting a protein that induced this clustering, but we have not yet identified this protein. OLs were required in vivo for the formation of sodium channel clustering along axons because mutant rats that lacked OLs developed almost no sodium channel clusters (Kaplan et al. 1997; Kaplan et al. 2001). The requirement of OLs to induce sodium channel clustering revealed an unexpected new function for OLs.

We also investigated the mechanisms by which (OPCs differentiate into myelinating OLs. It is known that the timing of oligodendrocyte differentiation from OPCs in different pathways is precisely controlled, occurring generally right after a given axonal pathway has innervated its target area. Songli Wang in my lab found that OPCs highly expressed Notch1 receptors and that activating these receptors in culture strongly inhibited their differentiation (Wang et al. 1998). Moreover, he found in vivo that RGCs expressed Jagged1, a Notch ligand, and targeted jagged1 protein to their axons, but he also found that this Jagged1 protein was down-regulated from axons right around the time of optic nerve myelination. This suggested the hypothesis that target innervation induced RGCs to down-regulate jagged1 mRNA or protein delivery to the axon. This possibility has not yet been tested, but other labs showed soon after that premature and ectopic myelination in fact occurs in the CNS in the absence of Notch1. What so precisely controls the timing of CNS myelination, and why it occurs only after target innervation, is a fascinating and very important unsolved question. The lack of target-derived signals may well explain why robust CNS myelinating culture systems have yet to be developed.

To better understand how OLs differentiate from OPCs to newly formed OLs to mature myelinating OLs, Jason Dugas took advantage of gene profiling methods and examined mRNA isolated from pure cultures of OPCs at various time points along their differentiation over a one-week time period. He found that they fully matured into OLs normally despite the absence of neurons and other cell types in several sequential stages, each characterized by the appearance of distinct transcription factors (Dugas et al. 2006). These gene profiles led to the identification of Id2, p57Kip2, Dicer1, mir-219, and KLF9 as powerful controllers of OL differentiation (Wang and Barres 2001; Dugas and Barres 2007; Dugas et al. 2010; Dugas et al. 2012).

Ben Emery, working together with John Cahoy, did additional transcriptomic work to zoom in on transcription factors that might control the ability of OLs to myelinate. His studies lead him to identify a new gene (at the time called gene mode 98) now named Myrf for myelin regulatory factor as a transcriptional regulator required for CNS myelination (Emery et al. 2009). In the CNS, he found that Myrf is specifically expressed by post-mitotic OLs and encodes a nuclear protein containing an evolutionarily conserved DNA-binding domain homologous to a yeast transcription factor. In mice lacking MRF within the OL lineage, premyelinating OLs are generated but they are unable to express myelin genes and fail to myelinate. These mice display severe neurological abnormalities and die because of seizures during the third postnatal week. Thus, Myrf is a critical transcriptional regulator essential for OL maturation and CNS myelination. A fascinating aspect that Ben has discovered in his own lab is that Myrf is a membrane-associated transcription factor that autoproteolytically cleaves to directly activate myelin genes (Bujalka et al. 2013). Perhaps this may imply as yet undiscovered mechanisms for regulating myelination.

To better understand the molecular basis of myelination by OLs, we have tried to develop more robust and rapid in vitro myelinating cultures. Along the way, we have found that astrocytes release signals, as yet unidentified, which enhance ensheathment of axons by oligodendrocytes (Meyer-Franke and Barres 1999; Watkins et al. 2008). But genuine myelin wrapping did not occur in these cultures until Trent Watkins was in the lab and found that inhibitors of gamma secretase triggered rapid myelin wrapping as demonstrated by electron microscopy (Watkins et al. 2008). He tried gamma secretase inhibition as he thought this might inhibit Notch signaling, which might be inhibiting the wrapping, but his studies instead showed that it was not Notch but inhibition of some other gamma secretase substrate in OLs that is not yet identified. By time-lapse microscopy, he was able to directly observe the process of myelination in this culture system. To our surprise, he observed that when an OL decided to myelinate, it myelinated all of the axons it was going to myelinate within several days in a critical window of time early after the OL differentiated, and then it never myelinated other axons again. The same observation was made shortly thereafter by David Lyons by imaging OLs myelinating in zebrafish in vivo. This suggests that an intrinsic genetic program is operating that drives OL lineage cells through their successive phases of maturation and that, once an OL has myelinated, it may never be able to myelinate again, which has important implications for understanding the failure of remyelination in the disease multiple sclerosis. Very likely generation of new OLs from OPCs will be critical for successful remyelination.

But what is the molecular basis of CNS myelination? It has long been known that myelin basic protein (MBP) is essential for myelin wrapping as shiverer mutant mice that lack MBP generate OLs that cannot myelinate. When Brad Zuchero joined the lab, he carefully examined the gene profiles of differentiating OLs and noticed changes in actin control genes. He showed that the initial stage of process extension and axon ensheathment by OLs requires dynamic actin filament assembly by the Arp2/3 complex. Surprisingly, he found that subsequent myelin wrapping coincides with the up-regulation of actin disassembly proteins and that rapid disassembly of the OL actin cytoskeleton does not require Arp2/3. When he induced loss of actin filaments, this drove OL membrane spreading and myelin wrapping in vivo, and he showed that the actin disassembly factor gelsolin is required for normal wrapping. Remarkably, he discovered that MBP is required for actin disassembly and that its loss phenocopies loss of actin disassembly proteins (Zuchero et al. 2015). His findings provided new insight into the molecular mechanism of myelin wrapping and identified it as an actin-independent form of mammalian cell motility. Brad has his own lab now and is doing some exciting work aimed at understanding how MBP induces actin disassembly and myelination.

Development of Methods to Purify and Culture Astrocytes and Elucidation of the Astrocyte Transcriptome

When I started at Stanford, I had developed methods to purify astrocytes from the developing optic nerve, but these did not work to purify astrocytes from the rodent brain. At the time, the way astrocytes were cultured from the brain was to make cell suspensions from neonatal brain and culture them in fetal calf serum containing medium for a week or so, then to shake off the top layer of microglia and OL lineage cells (and perhaps some neurons), and then to culture the remaining cells in a mitotic inhibitor to stop growth of contaminating cells. This method developed by McCarthy and DeVellis (in my lab, we call these astrocytes MD astrocytes) took several weeks, was not prospective, and worked only with newborn brains. It was not clear whether the resulting cells were astrocytes or some sort of glial progenitor cell. Clearly, many neural stem cells were present as new neurons were generated in these cultures over time. These cultures were also highly contaminated by residual microglia. Moreover, the use of serum greatly altered the properties of the purified cells, making them reactive. We desperately wanted to develop a prospective isolation method that would allow us to isolate astrocytes from more mature rodent brain tissue.

We worked on this for many years without success. We just could not identify antibodies useful for immunopanning that specifically bound to the surface of astrocytes and not other cells. When John Cahoy joined the lab he decided to tackle this problem. He screened various lines of mice that expressed GFP off of an S100b promoter. He found one reported in the literature that looked pretty good. His immunostaining experiments showed that it only expressed GFP in astrocytes and in OPCs. That was great because he then was able to develop a simple prospective purification method in which he first immunopanned with antibodies to remove OPCs and OLs and then used fluorescence-activated sorting (FACs) to purify the remaining GFP cells, which he showed were highly pure astrocytes. As a side product, he also got highly purified populations of OPCs, newly formed OLs, and more mature OLs. After the sort, the remaining cells were highly enriched neurons. The new generation of Affymetrix gene chips was now available, and John, working together with Ben Emery, was able to generate spectacularly beautiful data sets. Their paper, “A Transcriptome Database for Astrocytes, Neurons, and Oligodendrocytes: A New Resource for Understanding Brain Development and Function” (Cahoy et al. 2008) is the most highly cited paper my lab has published. It is hard to understate what a useful road map this turned out to be not only for my lab but also for many others. It provided a gold mine of information that has helped us to better understand glial function and neuron-glial interactions by allowing us to formulate new and testable hypothesis.

Immediately, these data sets let us bootstrap to finally being able to develop an immunopanning method to isolate rodent astrocytes from the brain. Being able to prospectively purify and culture astrocytes in serum-free medium was a vital tool needed for us to better understand their functions and interactions with other brain cell types. Lynette Foo tackled this project. She was able to analyze the data sets to identify highly expressed astrocyte genes that encoded for plasma membrane proteins that were not expressed by other brain cell types. With much hard work and ingenuity, she figured out a simple way to immunopan and purify brain astrocytes. But this was only halfway there because, as expected, the purified astrocytes rapidly underwent apoptosis in culture. She found that vascular cells strongly promoted astrocyte survival in serum-free culture and that they did this in part by secreting heparin-binding EGF-like growth factor (HBEGF), which was an interesting candidate as it is an epidermal growth factor receptor ligand, a receptor that astrocytes highly express. By adding HBEGF to the serum-free culture medium, Lynette was able to keep the astrocytes alive. She also found that some developing astrocytes normally undergo apoptosis in vivo and that the vast majority of astrocytes contact blood vessels, suggesting the hypothesis that astrocytes are matched to blood vessels by competing for vascular-derived trophic factors such as HBEGF. Finally, she showed that compared with the traditional MD astrocyte cultures, the gene profiles of her cultured immunopanned postnatal astrocytes (we call them IP astrocytes) much more closely resembled those of in vivo astrocytes (Foo et al. 2011). The simple purification and culture method that Lynette developed has been an invaluable tool for much of the astrocyte work our lab has subsequently done. Using this method, when Ye Zhang and Steven Sloan joined the lab, they were able to take advantage of RNA-sequencing technology to construct even better transcriptomes and a splicing database of glial cell types, neurons, and vascular cells in the cerebral cortex (Zhang et al. 2014).

Elucidation of Active Roles of Astrocytes in Synapse Formation and Function

Having developed methods to purify and culture both RGCs and astrocytes, we were finally in a great position to ask the question, what do neurons do by themselves and what do they need astrocytes to do? When Frank Pfrieger joined the lab, he asked whether astrocytes might play any role in controlling synapse function. In vivo, the majority of synapses are ensheathed by astrocytes. The astrocytes have largely been thought to have relatively passive roles, isolating synapses from one another, helping control ion concentrations, and rapidly clearing released neurotransmitters. But might astrocytes also have more active roles at synapses? To find out, Frank cultured RGCs in the absence and presence of astrocytes. In the absence of astrocytes, in serum-free medium with trophic factors for the RGCs, the RGCs looked beautiful, extended dendrites, made axons, and were electrically excitable if injected with depolarizing current. To our surprise, however, they displayed little spontaneous synaptic activity and had high failure rates in evoked synaptic transmission. But when co-cultured with astrocytes, either in direct contact or just in conditioned medium, Frank found that the frequency and amplitude of spontaneous postsynaptic currents were potentiated by seventyfold and fivefold, respectively, and fewer transmission failures occurred. Astrocytes increased the action potential-independent quantal release by twelvefold. Thus, RGCs in culture inefficient synapses that require astrocyte signals to become fully functional (Pfrieger and Barres 1997). This was quite a surprise to us because, at the time, it was thought that neurons autonomously expressed all the molecular machinery needed to form functional synapses.

What could account for this lack of synaptic activity in the absence of astrocytes? Were the RGCs failing to form synapses, or were they forming synapses that were not functional? Erik Ullian took up this question next. By performing a variety of experiments, including quantal analyses, FM1-43 imaging, immunostaining, and electron microscopy, he found that few RGC synapses form in the absence of astrocytes and that the few synapses that did form were functionally immature. But astrocytes increased the number of mature, functional synapses on the neurons by sevenfold and also were required for synaptic maintenance in vitro. In addition, he found that in developing rodents in vivo most synapses are generated concurrently with the development of astrocytes. Thus, Erik’s findings demonstrated that astrocytes are actively involved in inducing and stabilizing CNS synapses (Ullian et al. 2001). Similarly Erik found, together with Brent Harris, that Schwann cells strongly promote synapse formation between purified spinal motor neurons in culture (Ullian, Harris et al. 2004).

These findings, altogether, strongly supported active roles for astrocytes in inducing synapse formation and strengthening synapse function. But to find out whether they were functioning similarly in vivo, we next needed to identify the astrocyte-secreted molecules that were promoting synapse formation and function. Karen Christopherson took a biochemical approach to identify thrombospondins (TSPs)-1 and -2, which were expressed and secreted by developing but not mature astrocytes, as promoters of CNS synaptogenesis in vitro and in vivo. She found that TSPs induce ultrastructurally normal synapses that are presynaptically active but postsynaptically silent and work in concert with other, as yet unidentified, astrocyte-derived signals to produce functional synapses (Christopherson et al. 2005). Cagla Eroglu took up the question of the identity of the neuronal TSP receptor. She identified it as alpha2delta-1, a voltage-dependent calcium channel subunit of unknown function with a large extracellular domain, which was also the known receptor for the anti-epileptic and analgesic drug gabapentin. She showed that the VWF-A domain of alpha2delta-1 interacts with the EGF-like repeats common to all TSPs, that alpha2delta-1 overexpression increases synaptogenesis in vitro and in vivo, and that it is required postsynaptically for TSP- and astrocyte-induced synapse formation in vitro. She also discovered that gabapentin antagonizes TSP binding to alpha2delta-1, powerfully inhibiting excitatory synapse formation in vitro and in vivo (Eroglu et al. 2009). Together these experiments not only demonstrated that astrocytes promote synapse formation in the developing CNS, but also were an important step forward in understanding the therapeutic mode of action of gabapentin. Cagla also identified another highly expressed astrocyte-secreted protein called Sparcl1 (hevin) as a strong promoter of excitatory synapse formation in vitro and in vivo (Kucukdereli et al. 2011) and found that Sparcl1 induces glutamatergic synapses by bridging neurexin-1alpha and neuroligin-1B.

Astrocyte-secreted TSPs and SparcL1 both induce the formation of structural synapses, but these synapses are postsynaptically silent. So how do astrocytes promote synapse function? Frank Pfrieger had shown in his own lab that astrocyte-secreted cholesterol powerfully enhanced presynaptic efficacy. When Nicky Allen joined the lab, she found that astrocytes also profoundly promoted postsynaptic function. Remarkably she discovered that in pure cultures lacking astrocytes, RGCs express all of the AMPA receptor mRNAs (GluR1, 2, 3, and 4) and translate them all into protein, but this protein remains inside the RGCs and fails to get to the synaptic surface. Astrocytes secreted signals that rapidly induced all four AMPA glutamate receptors to get to the synaptic surface. She used biochemical fractionation of astrocyte-conditioned medium to identify glypican-4 (Gpc4) and glypican-6 (Gpc6) as astrocyte-secreted signals sufficient to induce functional synapses between purified RGCs. Application of Gpc4 to purified neurons increased the frequency and amplitude of glutamatergic synaptic events and Gpc4-deficient mice have defective synapse formation, with decreased amplitude of excitatory synaptic currents in the developing hippocampus and reduced recruitment of AMPARs to synapses. Her data identified glypicans as a family of novel astrocyte-derived molecules that are necessary and sufficient to promote glutamate receptor clustering and receptivity and to induce the formation of postsynaptically functioning CNS synapses (Allen et al. 2012). Remarkably, although astrocytes recruit all four AMPA receptors to the synaptic surface, GPC4 was able to recruit only GluR1, indicating that other astrocyte signals not yet identified recruit the other GluRs. Indeed, in her own lab, Nicky has already identified the astrocyte-secreted molecule that recruits GluR2. Together these findings reveal a remarkable complexity of astrocyte-neuron interactions that control synapse formation and function. Many astrocyte-secreted molecules control synapses awaiting discovery. Indeed, while we have focused so far on excitatory synapses, another lab has shown that astrocytes also strongly promote the formation and function of inhibitory synapses.

Elucidation of Active Roles of Astrocytes and Microglia in Synapse Pruning

The developing brain initially makes excess synapses and an activity-dependent process eliminates the weaker un-needed or inappropriate synapses. The mechanisms that eliminate synapses have until recently been largely mysterious. This was not a problem that my lab was initially working on but our lab’s first gene chip experiment led us to think about it. At the time, we were trying to understand how astrocytes so strongly stimulated synapse formation. We wondered whether maybe astrocytes simply induced expression of synaptic genes in RGCs. We tested this in a gene chip experiment by comparing mRNA levels in RGCs that had and had not been exposed to astrocyte-conditioned medium. To our surprise, few genes significantly changed in levels, but all three mRNAs encoding the three subunits of the complement component C1q (i.e., the initiating component of the classical complement cascade) were highly up-regulated. This was a surprise as C1q and other complement components were not thought to be expressed by healthy brain tissue. Developing brain tissue, however, had not been examined before. By immunostaining, we found that C1q immunoreactivity was strongly localized to developing synapses throughout the CNS in the first week postnatal. As this is a time period when extensive synapse elimination is occurring and the known role of the classical complement cascade is to help mediate elimination of bacteria, apoptotic cells, and debris, we immediately hypothesized that the classical complement cascade was helping to tag unwanted synapses for uptake and elimination by microglial cells, which express high levels of phagocytic complement receptors. Beth Stevens had just joined the lab and did some beautiful experiments assessing the role of this pathway in retinogeniculate synapse refinement. Indeed, she found that part of this refinement was impaired in C1q and C3 deficient mice, strongly implicating the classical complement cascade (Stevens et al. 2007). Moreover, when she imaged microglia during early postnatal development, she observed synaptic remnants, but these were greatly decreased in mice that lacked C3 or the microglial complement receptor (Schafer et al. 2012). Pruning of complement-coated synapses did not continue into adulthood.

In addition, in the lab, Won-Suk Chung found that astrocytes also helped to mediate part of retinogeniculate synapse refinement by mediating synapse elimination (Chung et al. 2013). This hypothesis initially also had been suggested by our transcriptome data sets, which showed to our great surprise that astrocytes were highly enriched in multiple phagocytic pathways, including the MEGF10 and MERTK pathways. Up to that point, microglia had been thought to be the main phagocytic cells present in the brain. But Won-Suk found that astrocytes in the developing brain contained synaptic remnants of both excitatory and inhibitory synapses, but these were absent in mutant mice that lacked MEGF10 and MERTK (engulfment of synapses by astrocytes was independent of C1q). Phagocytosis of synapses by astrocytes continued into adulthood although at a slower rate than postnatally. Remarkably Won-Suk found that electrical activity strongly controlled the phagocytosis of synapses by astrocytes. When he silenced electrical activity of RGCs in both eyes, little phagocytosis in the lateral geniculate occurred, but when only one eye was silenced, the silenced synapses were preferentially phagocytosed.

These findings raise many questions. Why are some synapses engulfed and not others? And why are some engulfed by microglia and others by astrocytes? Are there other mechanisms of synapse elimination that do not depend on glia? How does activity control phagocytosis? Perhaps one of the most interesting questions is what is the role of the continued activity-dependent engulfment of synapses in the adult hippocampus and CNS in general? Is it possible that this engulfment is critical for the structural remodeling of synapses involved in learning and memory? Laura Clarke in the lab is investigating this question now. Given the abilities of astrocytes to control synapse formation, function, and elimination, it is clear that these cells are not passive support cells after all, but they are critical components in the functioning and plasticity of neural circuits.

Understanding Human Astrocytes: Is There an Astrocytic Basis to Humanity?

As we found that rodent astrocytes were so strongly controlling synapse development and functioning, we increasingly wondered whether these properties would be shared by human astrocytes. The enhanced cognitive abilities of the human brain compared with other animals are generally attributed to evolution of neural circuits, but might the synaptic abilities of astrocytes also have evolved in beneficial ways that could enhance cognition? Ye Zhang and Steve Sloan in the lab developed an immunopanning method to acutely purify astrocytes from fetal, juvenile, and adult human brains that was able to maintain these cells in serum-free cultures (Zhang et al. 2016). They found that human astrocytes have abilities similar to those of murine astrocytes in promoting neuronal survival, inducing functional synapse formation, and engulfing synaptosomes. In contrast to mouse astrocytes, however, they found that intracellular calcium in mature human astrocytes responds robustly to glutamate. They performed RNA sequencing to compare gene expression with rodent astrocytes and identified many highly expressed human-specific astrocyte genes whose functions remain unknown. They also found that, comparing human astrocytes to mouse astrocytes, more changes in gene expression occur in astrocytes than the neurons. Importantly, their work identified two specific stages of astrocyte differentiation: Fetal brains contained only astrocyte precursor cells (APCs), which were highly proliferative cells that expressed only immature astrocytic properties; however, between 6 and 12 months after birth, they found that the APCs differentiated into postmitotic astrocytes with their fully mature pattern of gene expression. The timing of this astrocyte maturation overlaps exactly the time window when synapse density in the developing human brain greatly increases.

Because human astrocytes share the abilities of rodent astrocytes to control synapse development and function, it is possible that some developmental disorders and diseases might be caused by defects in these astrocyte abilities. Therefore, Steve Sloan in my lab collaborated with Sergiu Pasca’s group to investigate whether human astrocytes were generated in the induced pluripotent stem cell–derived three-dimensional (3D) human cortical spheroid (hCS) culture system that Pasca had invented (Pasca et al. 2015; Sloan et al. 2017). He acutely purified astrocyte-lineage cells from hCSs at varying stages up to 20 months in vitro and performed RNA sequencing to directly compare them to purified primary human brain cells. He found that hCS-derived glia closely resemble primary human fetal astrocytes and that, over time in vitro, they transition from a predominantly fetal to an increasingly mature astrocyte state. The hCS-derived astrocytes closely resemble primary human astrocytes and will be highly useful for future studies of development and disease. By comparing the properties of the APCs and mature astrocytes, Steve found that both astrocyte stages have the equivalent ability to induce synapse formation, but that the APCs engulfed synapses at a vastly higher rate. This suggests that the emergence of a high density of synapses in the human cerebral cortex between 6 and 12 months of postnatal age may not be the result of synapse formation induced by mature astrocytes but rather the result of a greatly decreased rate of synapse pruning. What controls the timing of astrocyte maturation is an important unsolved question. If this maturation timing becomes abnormal, occurring either too early or too late, it might have irreversible consequences on the formation of neural circuitry.

Development of New Tools to Study Microglia

Dysfunctioning microglial cells are increasingly implicated in many neurological diseases, but little is yet known of their normal functions. A stumbling block has been the lack of tools to identify, purify, and genetically manipulate them apart from closely related macrophages. Mariko Howe Bennett in my lab identified transmembrane protein 119 (Tmem119), a cell-surface protein of unknown function, as a highly expressed microglia-specific marker in both mice and humans (Bennett et al. 2016). She developed monoclonal antibodies to its intracellular and extracellular domains that enabled the specific immunostaining of microglia (and not macrophages) in histological sections in healthy and diseased brains, as well as isolation of pure nonactivated microglia by FACS. This enabled her to construct RNAseq profiles of gene expression by highly pure mouse microglia during development and in adulthood as well as after an immune challenge. These profiles demonstrated that mouse microglia mature by the second postnatal week and suggested novel microglial functions for future investigation. Mariko is currently constructing an inducible TMEM119-Cre mouse line that, if successful, will provide an invaluable tool for manipulating microglia and studying their in vivo functioning in health and disease models.

Another great limitation in studies of microglia has been the lack of a serum-free culture system. Most studies of microglia have required the use of a serum-containing medium to avoid microglial death, but the serum induces activation and alteration of the microglia properties. To better study microglia and the properties that distinguish them from other tissue macrophage populations, Chris Bohlen in my lab developed defined serum-free culture conditions to permit robust survival of highly ramified adult microglia. He found that astrocytes secreted CSF-1, TGF-β2, and cholesterol and that together these three molecules strongly promoted microglial survival in serum-free culture (Bohlen et al. 2017). With Chris Bennett in my lab, however, he found that mature microglia rapidly lose their signature gene expression after isolation in culture but that this loss can be reversed by engrafting the cells back into an intact CNS environment. Their data thus indicate that the specialized gene expression profile of mature microglia requires continuous instructive signaling from the intact CNS. Identification of this microglia maturation inducing CNS signal is now an important goal.

Currently, in the lab, Chris Bennett has generated antibodies to human TMEM119 for isolation of human microglia so that their properties can be directly compared to mouse microglia. He also is generating a novel humanized mouse that will enable engrafting and study of human microglia so that their functions in disease can be better investigated.

Studies of BBB Formation

When Rich Daneman joined my lab, he decided to investigate the molecular mechanisms that regulate CNS angiogenesis and (BBB formation, which were largely unknown at the time. He developed methods to highly purify and gene profile endothelial cells from different tissues, and by comparing the transcriptional profile of brain endothelial cells with those purified from the liver and lung, he generated a comprehensive resource of transcripts that are enriched in the BBB, forming endothelial cells of the brain (Daneman et al. 2010a). Through this comparison, he identified novel tight junction proteins, transporters, metabolic enzymes, signaling components, and unknown transcripts whose expression is enriched in CNS endothelial cells and provided a valuable resource for further studies of the BBB. His experiments revealed an essential role for Wnt/beta-catenin signaling in driving CNS-specific angiogenesis and provided molecular evidence that angiogenesis and BBB formation are in part linked (Daneman et al. 2009). He found that the BBB is formed during embryogenesis as endothelial cells invade the CNS and pericytes are recruited to the nascent vessels over a week before astrocyte generation, and that pericytes are necessary for BBB formation (Daneman et al. 2010b). He found that the pericytes induced the formation of tight junctions and vesicle trafficking in CNS endothelial cells, and also inhibited the expression of molecules that increase vascular permeability and CNS immune cell infiltration. Thus, pericyte-endothelial cell interactions are critical to regulate the BBB during development, and disruption of these interactions may lead to BBB dysfunction and neuroinflammation during CNS injury and disease. Overall, his studies illustrated how each component of the BBB (tight junctions, vesicular transport, and transporters) is under separate control by different cell–cell interactions and molecular signaling pathways. By imaging the BBB, Dritan Agalliu found that these barriers were differentially affected during stroke, with stepwise impairment of transcellular barrier followed by paracellular barrier breakdown (Knowland et al. 2014).

Understanding Reactive Astrocytes and Their Roles in Neurodegenerative Diseases

Reactive astrogliosis is characterized by a profound change in astrocyte phenotype in response to all CNS injuries and diseases. But it has been unclear whether reactive astrocytes are helpful or harmful. To better understand the reactive astrocyte state, Jennifer Zamanian in my lab decided to purify and gene profile reactive astrocytes from two different mouse injury models: Ischemic stroke induced by middle cerebral artery occlusion and neuroinflammation induced by systemic injection of the immunostimulant lipopolysaccharide (LPS). To our surprise, reactive astrocyte phenotype strongly depended on the type of inducing injury (Zamanian et al. 2012). Reactive astrocytes in ischemia up-regulated many neurotrophic factors and TSPs, suggesting they might be helpful by promoting survival and repair, whereas reactive astrocytes induced by LPS up-regulated many classical complement cascade components, suggesting they might be harmful by driving synapse loss. We named these two types of reactive astrocytes A1 and A2 for their hypothesized “bad” and “good” functions after the M1/M2 macrophage nomenclature.

Work from Michael Sofroniew’s lab had already strongly supported a repair-promoting function for A2 reactive astrocytes induced by ischemia, so Shane Liddelow in my lab decided to investigate the role of the LPS-induced A1 neuroinflammatory reactive astrocytes (Liddelow et al. 2017). He found that microglia that were activated either by LPS exposure or by CNS injury induce A1 astrocytes by secreting Il-1α, tumor necrosis factor (TNF), and C1q, and that these cytokines together are necessary and sufficient to induce A1 astrocytes. He was able to create cultures of pure A1 reactive astrocytes by simply adding these three cytokines to their serum-free medium, which allowed him to directly compare the function of normal astrocytes with A1 reactive astrocytes in vitro. He found that A1 astrocytes lost most of the normal astrocyte functions, losing the ability to promote neuronal survival, outgrowth, synaptogenesis, and phagocytosis. He also found that A1 reactive astrocytes gained a new function: They secreted a neurotoxin that rapidly induced the death of neurons (as well as axons and synapses) and OLs.

Because A1s are rapidly induced in the CNS after acute injury, these findings suggested the possibility that axotomized CNS neurons die after axotomy not because they are deprived of retrograde neurotrophic signals but because they are murdered by A1s. Shane tested this by investigating whether death of axotomized RGCs could be stopped by preventing the formation of A1 astrocytes after injury by inhibitory antibodies to Il-1α, TNF, and C1q or in mutant mice deficient for all three cytokines. Remarkably, he found that RGC death was entirely prevented when A1 formation was blocked. These experiments provided strong evidence that A1 reactive astrocytes are responsible for the death of axotomized RGCs. As Shane found that A1 astrocytes are abundant in degenerating regions of most major human neurodegenerative diseases, including Alzheimer’s, Huntington’s, and Parkinson’s disease; amyotrophic lateral sclerosis; and multiple sclerosis, his findings suggest that A1 astrocytes may actively drive neurodegeneration in these disorders. By developing drugs that prevent A1 formation, that revert A1s back to normal resting astrocytes, that convert A1 into A2 reactive astrocytes, or that block the A1 neurotoxin, in the future it may be possible to block or greatly decrease neurodegeneration. At present, Kevin Guttenplan in the lab, working with Shane, has used biochemistry to highly purify and identify a candidate neurotoxin.

A working model consistent with these observations is that neuronal dysfunction or injury leads to the release of a signal that activates microglia, which in turn induces formation of A1 reactive astrocytes, which in turn secrete a toxin that kills specifically only the injured neurons (or OLs). Our findings indicate that the A1 neurotoxin does not kill healthy neurons. By only killing injured neurons, this mechanism avoids innocent bystander killing of unharmed neurons. By removing only injured neurons, their synaptic inputs would be freed up to wire onto other nearby neurons, which might help to preserve circuit function. It is unclear why a mechanism would have evolved to kill neurons and OLs, but analysis of the gene profiles of A1s indicates that they are activating strong antiviral and antibacterial defense programs. Thus, A1s may have initially evolved to fight infection but in the aging brain, or after brain injury, induction of A1s may be harmful.

Why is the aging brain so vulnerable to neurodegenerative disease? Alexander (Ali) Stephan, when he was in my lab, stumbled upon what may be an important clue. We had found that the classical complement cascade was targeting developing synapses, but specific antibodies to C1q for immunostaining and for biochemical purposes were not available. So Ali made a monoclonal antibody to mouse C1q. He found that it worked well for immunostaining (and unlike other available antibodies did not stain C1q-deficient mouse brain). To our surprise, he discovered that as the mouse brain aged, their synapses became highly immunoreactive to C1q, first beginning in the hippocampus at only a few months of age and then gradually this synaptic staining spread throughout the CNS (Stephan et al. 2013). But unlike what occurred at developing CNS synapses during the first postnatal week, he found that the classical complement cascade did not become activated in the normal aging brain and there was no evidence that synapse loss was occurring. Although C1q-coated aging synapses are not engulfed by microglia, Ali found that they were functionally impaired. The extent of this synaptic C1q accumulation with normal mouse and human brain aging was remarkable as Western blots indicated that C1q protein was increasing with aging a hundredfold.

Ali’s findings raise the question of why synaptic C1q increases with aging. As C1q is a lectin-like protein that generally binds to debris, dying cells, and foreign substances, an interesting hypothesis is that C1q is binding to “senescent” synapses that are exponentially building up during normal brain aging. Synapses might become senescent because they are turning over less rapidly, and indeed, we found that the rate of engulfment of synapses by astrocytes decreases with brain aging (Chung et al. 2013). Moreover, Won-Suk Chung found that the rate of synaptic phagocytosis by astrocytes was fivefold slower in vitro and in vivo in a human ApoE4 background compared with ApoE2 (ApoE3 was in between; Chung et al. 2016). Moreover, he found that transgenic mice expressing human ApoE4 accumulated C1q more quickly than did ApoE2 mice. His work lends support to the idea the buildup of synaptic C1q with age may indeed be the result of slower synapse turnover by astrocytes and more rapid accumulation of senescent synapses. Perhaps development of drugs that stimulate the ability of aging astrocytes to healthily turn over synapses might someday ward off the normal cognitive decline of aging.

Together these findings raise the possibility that the vulnerability of the aging brain to Alzheimer’s disease and other neurodegenerative disorders might be in part because of the exponential rise in synaptic C1q levels, which places them at great risk for any “second hit” that might activate the classical complement cascade and lead to unwanted synapse loss. That is, could a normal developmental mechanism of synapse elimination become aberrantly activated in the adult brain triggering progressive synaptic neurodegeneration? This idea seemed likely as soon we had discovered that the classical cascade was targeting developing synapses. Many studies had documented strong complement activation in a large variety of human neurodegenerative diseases, including Alzheimer’s disease, in which synapse degeneration is a prominent feature. Moreover, our RNAseq studies showed that neurons lacked the high levels of multiple complement inhibitor proteins that most other cells in the body express. We began by investigating the DBA2J mouse model of glaucoma in collaboration with Simon Johns’ lab (Stevens et al. 2007). Although RGCs do not die in this model until almost a year of age, we were startled to find that C1q was highly up-regulated and localized to RGC synapses in the inner plexiform layer of the retina by two to three months of age, accompanied by marked synaptic neurodegeneration by four months of age, long preceding RGC death. Mutant mice that lacked C1q were very strongly protected from RGC death and optic nerve degeneration (Howell et al. 2011). Similarly, in collaboration with several other labs, we found early complement-mediated degeneration of synapses as a very early sign of pathology in many other mouse models of neurodegenerative disease, including Alzheimer’s disease (Hong et al. 2016), frontotemporal dementia (Lui et al. 2016), and spinal muscular atrophy (Vukojicic et al. 2017). As with glaucoma, in all of these models, C1q inhibition or deficiency was strongly neuroprotective.

What second hit might activate the classical complement cascade and trigger synaptic neurodegeneration? The most likely possibilities are triggers of A1 reactive astrocytes because our RNAseq studies demonstrate that genes encoding classical complement cascade proteins, including C1r, C1s, C4, C2, and C3, are among the most highly up-reguated A1 genes and would fuel the classical complement cascade (C1q mRNA and protein are highly present in microglial cells even in normal brain tissue). In addition, oligomeric beta amyloid is a strong activator of the classical cascade. Triggers of A1 formation include acute and chronic neural injuries as well as immunostimulants, such as lipopolysaccharide, that normally may be produced by acute and chronic bacterial infections. A low level of A1 reactive astrocyte formation even happens with normal brain aging (Clarke et al. 2017). As we found that A1s were the predominant type of reactive astrocytes in most or all major neurodegenerative diseases, including Alzheimer’s disease, there is likely ample complement present to drive the classical complement cascade and thus microglia-mediated synapse loss in these diseases. The neurotoxin released by A1s, which is not itself a complement component, likely additionally helps to drive neurodegeneration. Thus, the classical complement cascade and A1 reactive astrocytes (and their toxin) are important new therapeutic targets that should be tested for efficacy in neurodegenerative disorders. Although septic encephalopathy and hepatic encephalopathy do not involve neurodegeneration, the possibility that A1s contribute to the encephalopathy is an important consideration for future investigations.

Founding a Biotech Company: Annexon Biosciences

Having realized that the classical complement cascade was an exciting new therapeutic target for treatment of Alzheimer’s and other neurological diseases, starting around 2006, I began to talk with major pharmaceutical companies about the idea of making a drug to inhibit the cascade. Over a several year period, I met with a wall of resistance. Some people thought it would be too hard to make this drug; others thought it might have side effects. It was true that some C1q-deficient mice and humans had lupus, but in most cases this was mild, and in any case there was (and is) no evidence that acute C1q deficiency in adults would cause lupus. In any case, lupus is a very common drug side effect that is well managed by a drug holiday, when needed. C1q and C1s seemed to me the best targets for inhibition, as only the classical arm of the cascade would be blocked, leaving the other two arms and their immune functions intact.

After a few years, I realized that if a drug were going to be made, I would have to become more actively involved. I started talking to my friend Arnon Rosenthal about starting a new biotech company to make complement inhibitors. Arnon, long a highly successful neuroscientist at Genentech and then the successful founder and chief scientific officer (CSO) of Rinat Neuroscience Corporation, had just sold Rinat to Pfizer. I had gotten to know Arnon while serving on the Scientific Advisory Board of Rinat and was impressed by what he had accomplished. In only five years, while leading Rinat, he had generated monoclonal antibody therapeutics that inhibited nerve growth factor for treatment of neuropathic pain, beta amyloid for treatment of Alzheimer’s disease, calcitonin gene-related peptide for treatment of migraine, and PCSK9 to reduce low-density lipoprotein cholesterol. We decided to cofound Annexon Biosciences in 2011. We obtained $500,000 in seed funding from Fidelity Bioventures. Arnon again led these efforts and was successful in making a monoclonal antibody that strongly inhibited both mouse and human C1q and thus was highly useful for efficacy studies in mouse models of disease. Later, we were fortunate to work with Ted Yednock as Annexon’s CSO. Ted, previously CSO of Elan Pharma and inventor of the blockbuster drug Tysabri for multiple sclerosis, had great expertise in both neuroscience and immunology. Under his leadership, and that of Doug Love, CEO, we were successful in obtaining larger series A and B venture capital investments of $34 million and $44 million. Doing this amount of fundraising took a substantial amount of my time for several years, but it is very nice to see the effort finally moving forward smoothly. Our C1q antibody has so far shown impressive efficacy in multiple mouse models of neurological disease, including neuromyelitis optica, Guillain-Barre syndrome, spinal muscular atrophy, and Alzheimer’s disease (Phuan et al. 2013; McGonigal et al. 2016; Hong et al. 2016; Vukojicic et al. 2017). As of now, having so far tested our antibody safely in mice and primates, we are currently testing its safety in human volunteers and hope to start our first clinical trial this year. We will start by testing its efficacy in Guillain-Barre syndrome and glaucoma, but our ultimate goal is to be able to test its efficacy in major neurodegenerative diseases, including Alzheimer’s disease, frontotemporal dementia, and Huntington’s disease.

Mentoring Young Scientists

It has been a very great privilege to mentor young scientists (Table 1). I did not realize when I started my own lab at Stanford that this was going to be, by far, the most rewarding part of the job. This is not to say that the process of scientific discovery has not been continuously thrilling, because it has been. But it is even more exhilarating to watch young people develop into independent scientists and to play some role in guiding that process. Indeed, the process of scientific discovery and mentoring young scientists is completely interwoven. In an academic lab at a top university like Stanford, the principal investigator is not the one doing the experiments and not even the one having most of the ideas (if I am lucky I get to make an occasional suggestion that is not instantly thrown under the bus). I can honestly say that the vast majority of my graduate students and postdoctoral fellows have been far more talented than I ever was. I have written before about my approach to mentoring (Barres 2013, 2017) so will not repeat those thoughts here. I have always felt that I was incredibly fortunate in my training to have had such exemplary mentors for my PhD and postdoctoral work. I have tried to emulate their practices when it comes to mentoring, but often feel that I am not coming close. I find, like my mentors, that my natural tendency is to be as hands off as I possibly can and to allow my trainees to be as independent as possible. I tend to make suggestions for possible starting points when new trainees join the lab. Sometimes my suggestions are taken, sometimes not. In any case, these starting points soon evolve into something different and very often the trainee thinks of something better. As long as they work in the area of neuron-glial interactions, it fits well into the general lab environment. I did have one postdoc, Andrew Huberman, who never worked on glial cells at all and was completely independent from his start in my lab. I consider Andy my “paying it forward” to help relieve my continued guilt at not having worked on hair cells as a graduate student. It is very nice that he is now an associate professor in the lab next door to mine!

Table 1 Past and Current Trainees in the Barres Lab

Overall, as I have previously written about, I feel that mentoring young scientists is something that involves great generosity (Barres 2013, 2017). It is a great challenge to stay at the leading edge of science and maintain grant funding. But to do this and still be highly generous to your trainees is even more challenging. That’s why those scientists who manage to both be great scientists and great mentors are real heroes to me. Some wonderful examples include my own mentors, David Corey and Martin Raff, as well as Steven Kuffler, Seymour Benzer, Corey Goodman, Lily and Yuh Nung Jan, Marc Tessier-Lavigne, Bob Horvitz, David Baltimore, Louis Reichardt, Sol Snyder, Mike Greenberg, Bill Newsome, Richard Axel, Cori Bargmann, and Chuck Stevens (and of course many more).

Training Young Scientists about Human Biology and Disease

Being interested in disease, I had an unusually prolonged training period before starting my own lab. After college, I did three years of medical school (usually it’s four years, but Dartmouth once featured a three-year program), four years of internship and neurology residency, seven years of graduate school, and three years of postdoctoral training. That’s 17 years of very low pay and long hours of hard work! I would do it all again because I loved every moment of it. My training about neurological disease drove much of my life’s research on glial cells and their roles in disease. But 17 years of training is far too much to ask of young scientists who want to study disease. But what is a better way? I think as a community we need to put more thought into this. MSTP (MD-PhD) training, paid for by the NIH, has long been the main way that physician-scientists are generated. I enjoy having MSTP students do their graduate work in my lab because I find that I can engage with them in meaningful disease-oriented research in a way that typical neuroscience PhD students generally cannot. But MD-PhD training suffers from a serious flaw. Most of these trainees, by the time they finish their MD-PhD training and their residencies (and clinical fellowships) find, as I did, that it is too difficult to be simultaneously a successful physician and a scientist. To be sure, some manage to do it, but most do not. Nationally only about 30 percent of MD-PhDs continue to do research. Moreover, those who do continue to do research have often done an accelerated PhD training period and generally skipped postdoctoral training (or at most done a short research fellowship). It is very difficult therefore for them to compete for NIH funding and to do research at the highest level.

As a result, just as was true 20–30 years ago, we are applying the results of basic science discovery far too slowly to developing new treatments for disease. Many diseases have never been worked on by outstanding scientists. I like to use hepatic encephalopathy as an example. When the liver fails, the brain fails. Why? No one really knows and only a few, frankly not so good, labs have ever worked on the problem. There are countless other examples. When I began my lab at Stanford 25 years ago, working on disease was seen as a second-class activity. This is no longer the case. At least half of all graduate students express strong interest in studying disease and, given recent scientific technological advancements, it is now possible to do first-class research on human biology and disease. Unfortunately we are not teaching most graduate students about human disease, or at best only superficially in a course or two.

As an attempt to begin to rectify this problem, 13 years ago, I began a Master’s of Science in Medicine (MOM) program at Stanford University to teach entering PhD students intensively about human biology and disease. What I did essentially was to recreate the Markey Foundation program that had run at HMS for PhD students for about six years during the 1980s back when I was a graduate student there. As with the Markey program, PhD students who take the MOM program essentially take the first 1.5 years of basic biomedical science courses with the MD students, while delaying most of their PhD coursework for one year. These courses include anatomy, histology, physiology, pathology, and so forth. In short, the MOM students add on what amounts to about a year of extra training time in return for an intensive knowledge of human biology and disease. We have taken about five MOM students per year (determined by funds availability; several times more graduate students apply into MOM each year). I have watched MOM training transform the education of every PhD student who has taken it. It has not only intensified their interest in disease but also enabled them to seriously study disease. In nearly every case, it has altered their choice of PhD thesis lab.

But this is not enough. We are not reaching enough students and most schools do not have a MOM program. Furthermore, the MOM courses are not designed for PhD students. We need to do this. I would like to see a Khan academy–like series of high-quality MOM courses, designed for young scientists, freely available to all who wish to learn about human biology and disease. Moreover such a website might contain an area where physicians can tell young scientists what the most important unanswered questions and medical needs are from their point of view. Discussions could be posted about these problems and needs that might stimulate new research and advances. Perhaps a medical foundation like the HHMI or the Chan Zuckerberg Initiative will step up and help.

I finished my training in neurology almost 35 years ago. Since then, there are still no substantially new treatments for stroke (other than clot busters), neurodegenerative diseases, and glioblastoma. For multiple sclerosis, there are some new immunosuppressive drugs that are highly risky and there is still a need for drugs that promote remyelination. Progress is glacial. When one looks at efforts that have gone into treating some common neurological diseases, such as stroke and Alzheimer’s disease, things are surprisingly disheartening. There have been more than 1,000 failed clinical trials to treat stroke, mostly all versions of saving the neuron from excitotoxic death. Similarly, there has been one leading hypothesis for Alzheimer’s disease treatment—lowering beta amyloid—and many largely failed trials have focused on that. Something is broken. Normally in science when one disproves a hypothesis, one moves on to another hypothesis. Why is this not happening in our understanding and treatment of neurological diseases? There is a desperate need for new (and better) scientists to engage in these problems.

Helping Women in Science

When I was young, I did not believe that any barriers would hinder my career as a woman in science. The story told at MIT and elsewhere was that academia was a meritocracy. It never occurred to me to doubt this. MIT even had a bulletin board where they talked about how they admitted women from their very start. What it didn’t mention is that it accepted only an occasional few until the 1970s. Even when I was accused of cheating on that computer science exam because “my boyfriend must have solved it for me,” it was many years before it even occurred to me that this was sexism. I see this same belief in meritocracy in young women today; the idea that their womanhood confers barriers generally occurs only as they reach mid-career and see less competent men being promoted or given leadership positions while they are passed over. When I look at mid-level and senior women at Stanford, I do not think that most are thriving the same way that their male counterparts are. They are all too aware of the barriers, and they are resentful (sadly, one woman put it this way in a Stanford survey: “I feel like if I failed to stop showing up for work, no one would notice”). The few exceptions tend to be super highly successful women who also, with few exceptions, tend to deny the existence of barriers for women. Many young women would like to believe that these battles are over and successfully fought. But much evidence says this is not so. For instance, recently, a news article has reported that three of four senior women scientists at Salk Institute were suing because they feel they have been systematically denied the same space and financial resources that their male colleagues have enjoyed, reminiscent of the same battle that Nancy Hopkins waged at MIT almost 20 years ago.

In general, my perception is that most of my male academic colleagues are highly well meaning and strongly believe that it is truly a meritocratic system for both men and for women. They are unaware from their own experience of the many barriers that women continuously face. The best explanation I have found for why it is so hard for men to understand that gender-based barriers truly exist comes from Shankar Vedantam’s book The Hidden Brain (2009). Vedantam talks about an experience he had swimming in the ocean, not realizing that the tide was with him. As he swam, he felt stronger and more confident. But when he tried to swim back to shore, he found that the tide was against him, his confidence left him, and it was very difficult to return. It was only changing sex at the age of 40 and experiencing life from the vantage of a man that I finally came to be fully aware of these barriers. I have written about these experiences in my essay called “Does Gender Matter?” (Barres 2006). But as my transgender colleague Joan Roughgarden so wisely summarized: “Until proven otherwise, women are presumed to be incompetent whereas men are presumed to be competent.” All transgender people, whether male or female, share a common anger at the very different way that society treats people simply based on their gender. A counselor who works with people who have recently transitioned once told me that her most difficult challenge is helping male to female transsexuals understand that their suddenly vastly lowered social status is not because they are now transgender but because they are now women.

My experience being differently treated as a woman and then a man, even though I was the same person, is the reason why I was deeply angry when Larry Summers, when president of Harvard, proclaimed that one of the reasons that few women were getting tenure in science and engineering at Harvard under his leadership was that women were innately less able than men. My essay “Does Gender Matter?” a detailed response as to why I disagree—and more important all the scientific evidence that compellingly speaks against his view—was published by Nature in 2006. I made the following points in it: There is no compelling evidence for relevant innate gender differences in cognition. There is overwhelming evidence for severe gender prejudice. Both men and women often deny gender-based bias; we all have a strong desire to believe that the world is fair. When faculty tell their students that they are innately inferior based on race or gender, they are crossing a line that should not be crossed—the line that divides responsible free speech from verbal violence. In a culture in which women’s abilities are not respected, women cannot effectively learn, advance, lead, or participate in society in a fulfilling way.

I was stunned by the response to my commentary. In the aftermath, it was covered by most major newspapers around the world, hundreds of television shows and radio stations asked to interview me, I received eight book offers, and I received hundreds of invitation to speak on this subject (and continue to receive them). I gave only one talk on this subject titled “Reflections on the Dearth of Women in Science,” at Harvard University, on the condition that it be posted online for anyone to watch (the video can be found on YouTube and the PowerPoint slides, and notes with references under each slide, can be found at http://www.memdir.org/video/ben-barres-dearth-of-women-in-science.html). Please watch this talk or read through the slides.

In response to my Nature (Barres 2006) commentary, I received more than 3,000 emails, the majority from women telling me of terrible experiences of gender-based discrimination (and in some cases serious sexual harassment by their male professors) that had hindered their careers. I provide here two of these messages that particularly strongly struck me. The first strikingly illustrates the relative neglect that women experience throughout their lives, a neglect that not only women may not realize they experience but that most men also may not realize women typically experience:

Dear Ben,

Just wanted to say thanks so much for coming forward with your experiences … I was a Harvard student. I remember strongly a meeting I had with the poet Adrienne Rich. I came away from the meeting feeling shocked—I realized it was the first time I’d felt truly taken seriously as a person.

Julie

Another of these messages was from Dr. Nalini Ambady who alas passed away in 2013 from leukemia. I do not think she would mind my sharing her message here:

Dear Dr. Barres,

I very much enjoyed reading your thoughtful article in Nature and have attached a couple of papers from my lab that indicate quite clearly that sociocultural stereotypes affect the performance of both adults and children (as young as 5 years of age!). Interestingly, mine was one of the first tenure cases that came before Summers at Harvard in 2002. He ruled against the Psychology department’s positive recommendation. This was, of course, well before he made his infamous remarks and before it was revealed that he had disproportionately ruled against women in tenure decisions in his first years in office.

I do hope that you’re only getting positive feedback … And that your comments are taken seriously. As seriously as they deserve to be.

Best,

Nalini Ambady, PhD

Professor, Neubauer Faculty Fellow

Psychology; Tufts University

Dr. Ambady was a social psychologist who did highly influential work on nonverbal behavior and social influences at Harvard, Tufts, and then finally Stanford prior to her death, winning many prizes and honors for her discoveries (https://en.wikipedia.org/wiki/Nalini_Ambady), but apparently Larry Summers was unable to appreciate their significance.

It is remarkable to me that 10 years later, we are repeating a similar chapter in history after Google engineer James Damore wrote a company memo detailing why he thought innate differences between men and women explained why there are so few women engineers at Google. His claims again rested heavily on very dubious arguments from evolutionary psychology, just as had Larry Summers’s comments, which were in turn largely based on his conversations with Harvard Professor Steven Pinker. What all of these folks—Larry Summers, Steven Pinker, and James Damore, as well as many of the other highly successful white men who have made the same arguments throughout history—strongly believe is that, although more men may be innately better suited for science and engineering than women, there of course should be an individual meritocracy for those women who are as good or better than men. But what they also entirely fail to see is that individual merit cannot and will not be recognized in the face of pervasive negative stereotyping.

This conclusion is strongly supported by the many studies that show that men are hired over women with equivalent curriculum vitae. Moreover, as I reviewed in my essays (Barres 2006, 2010), negative stereotyping itself is deeply harmful to the ambitions and achievement of women. As Nancy Hopkins ultimately concluded, even when women scientists are highly successful, the research accomplishments of women are perceived as lesser than identical work done by a man (see Humphries 2017). Everyone should read the final chapter in Malcolm Gladwell’s book Blink (2005), which describes what happened when major symphony orchestras finally switched to gender blind auditions. Even then, male conductors often persisted in their beliefs that the women winners were not deserving, and, perhaps most sadly of all, when women won many positions in these orchestras, men no longer saw being a member of these orchestras as prestigious and salaries dropped.

At present, the evidence that gender-based stereotyping is holding back women’s careers is overwhelming, so I am quite tired of hearing unscientifically supported claims from successful white men (unaware of their benefits from their privileged status that continuously fuels their success) that women are innately less able. Given this pervasive negative stereotyping, all of us (male and female) need to be constantly working hard to make the environment more diverse and supportive. I have focused here on women, but many other groups also face substantial bias and barriers, including Latinos and African Americans. Despite all good intentions, I am constantly also disturbed by how few Asians I see in leadership positions at Stanford and elsewhere. It is very clear looking at the rosters of the National Academy of Sciences that Asians are only rarely elected no matter how deserving. We all need to do much better!

I am constantly surprised given the existence of tenure, that more faculty members don’t speak up and demand more progress. We need many more Nancy Hopkins’s in this world. Her courageous and long battle to help women at MIT and elsewhere has been a model. There has been a great personal cost to her, I am certain. As has been said, leadership is about going out of your comfort zone to help others. No one fits this definition better than Nancy. I think the reason that many women who reach leadership positions often neglect to use their power to help women is that they may feel that such acts would undermine their leadership authority in the eyes of men. That’s why women in leadership positions who do not behave this way are real heroes to me—Jackie Speier (U.S. Congress), Sheryl Sandberg (COO of Facebook), and Drew Faust (president of Harvard University who eliminated the longstanding and highly sexist Finals Clubs system at Harvard) come to mind.

To paraphrase Martin Luther King, a first-class scientific enterprise cannot be built on a foundation of second-class citizens. Change is hard, but we all need to do our part to work toward a better world for all. The welfare of science depends on it as many studies have shown that diverse perspectives drive innovation. Diverse young scientists frequently are successful because they enter a field and see the same old data in completely new ways. But it is hard enough to advance the frontiers of science without having to simultaneously confront a mountain of prejudice. Every one of us has the responsibility to work to recognize and lessen these barriers lest the passion for science that drives many of our best and brightest diverse young scientists is extinguished, leading them to “choose” other careers. This tragedy still happens routinely today to women, to LGBT people, to Latinos, to African Americans, and to other talented people who are different in some way.

When it comes to prejudice and discrimination, we are all “the monsters.” I don’t know what it will take to make academia truly welcome diverse people, but I do know that, despite all good intentions and efforts, this work is still only just beginning. Despite good intentions, the continued barriers that diverse talented people continue to experience in academia every day are astonishing. Overall I am happy to say that although many battles are left to be fought, undeniable progress is being made. It was thrilling to visit MIT a few months ago and see that 40 years after I had graduated, the faculty finally had a large number of incredibly talented women.

Summing Up

As I have described, I believe that my different experiences in life as an LGBT person helped to provide me with diverse perspectives and with the fortitude that I needed to persevere in a competitive world. Growing up transgender in a time of universal ignorance and hate has been difficult and emotionally painful. I believe that most or all of this pain is preventable in a future world in which people are less ignorant, more supportive, and more understanding. I have tried my best to help others by being open about my transgender identity and by being as good a scientist, mentor, and human being as I have been able to be. It has been a great privilege to have had such an enjoyable academic career.

Selected Bibliography

Allen NJ, Bennett ML, Foo LC, Wang GX, Chakraborty C, Smith SJ, Barres BA (2012) Astrocyte-derived glypicans 4 and 6 promote the formation of excitatory synapses containing GluA1 AMPA glutamate receptors. Nature 486, 410–14.

Barker A, Koch S, Reed J, Barres B, Ullian E (2008) Developmental control of synaptic receptivity. J. Neurosci 28, 8150–60.

Barres BA (2006) Does gender matter? Nature 442, 133–36.

Barres BA (2010) Neuro nonsense. Book review of Delusions of Gender by Cordelia Fine. PLOS Biol. 8, e1001005.

Barres BA (2013) How to pick a graduate advisor. Neuron 80, 275–9.

Barres BA (2017) Stop blocking the postdoc’s path to success. Nature, in press.

Barres, BA, Chun LLY, Corey DP (1988a) Ion channel phenotype of white matter glia: I. Type 2 astrocytes and oligodendrocytes. Glia 1, 10–30.

Barres, BA, Silverstein BE, Corey DP, Chun LLY (1988b) Morphological, immunological and electrophysiological characterization of rat retinal ganglion cells purified by panning. Neuron 1, 791–803.

Barres, BA, Chun LLY, Corey DP (1989a) Glial and neuronal forms of the voltage-dependent sodium channel: characteristics and cell-type distribution. Neuron 2, 1375–88.

Barres, BA, Chun LLY, Corey DP (1989b) Induction of a calcium current in cortical astrocytes by cAMP and neurotransmitters. J. Neurosci. 9, 3169–75.

Barres, BA, Koroshetz WJ, Swartz KJ, Chun LLY, Corey DP (1990a) Ion channel expression by white matter glia: II. The O2A glial progenitor cell. Neuron 4, 507–24.

Barres, BA, Koroshetz WJ, Chun LLY, Corey DP (1990b) Ion channel expression by white matter glia: III. Type 1 astrocytes. Neuron 5, 527–44.

Barres, BA, Chun LLY, Corey DP (1990c) Ion channels in vertebrate glia. Annu Rev Neurosci. 13, 441–74.

Barres, BA, Hart IK, Coles HSR, Burne JF, Voyvodic JT, Richardson WD, Raff MC (1992) Cell death and control of cell survival in the oligodendrocyte lineage. Cell 70, 31–46.

Barres BA and Raff MC (1992) Proliferation of oligodendrocyte precursors depends on electrical activity in axons. Nature 361, 258–60.

Barres, BA, Schmid R, Sendtner M, Raff MC (1993a) Multiple extracellular signals are required to for long-term oligodendrocyte survival. Development 118, 283–95.

Barres BA, Jacobson MD, Schmid R, Sendtner M, Raff MC (1993b) Does oligodendrocyte survival depend on axons. Curr. Biol. 3, 489–97.

Barres, BA, Raff MC, Gaese F, Bartke I, Dechant G, Barde YA (1994a) A crucial role for neurotrophin-3 in oligodendrocyte development. Nature 367, 371–75.

Barres, BA, Lazar M, Raff MC (1994b) A novel role for thyroid hormone, glucocorticoids, and retinoic acid in timing oligodendrocyte differentiation. Development 120, 1097–108.

Barres, BA and Raff MC (1994) Control of oligodendrocyte number in the developing rat optic nerve. Neuron 12, 935–42.

Barres BA, Burne J, Sendtner M, Thoenen H, Raff M (1996) CNTF controls the rate of oligodendrocyte generation. Mol. Cell. Neurosci. 8, 146–56.

Barres BA, Freeman MR, Stevens B (2015) Glia (CSH Monograph Series). Cold Spring Harbor Press, New York.

Barres BA, Stevens B (2014) Purifying and Culturing Neural Cells: A Laboratory Manual. Cold Spring Harbor Press, New York.

Bennet ML, Bennett FC, Liddelow SA, Ajami B, Zamanian JL, Fernhoff NB, Mulinyawe SB, Bohlen CJ, Aykezar A, Tucker A, Weissman I, Chang E, Li G, Grant GA, Hayden-Gephart M, Barres BA (2016) New tools for studying microglia in the mouse and human CNS. Proc. Natl. Acad. Sci. USA, 113, E1738–46.

Berg A, Zelano J, Stephan A, Thams S, Barres BA, Pekny M, Pekna M, Cullheim S (2012) Reduced removal of synaptic terminals from axotomized spinal motoneurons in the absence of complement C3. Exp. Neurol. 237, 8–17.

Bjartmar L, Huberman A, Ulliam EM, Chapman B, Barres BA, Perin M (2006) Neuronal pentraxins mediate process refinement in the retinogeniculate system. J. Neurosci. 22, 6269–81.

Bohlen CJ, Bennett FC, Tucker AF, Collins HY, Mulinyawe SB, Barres BA (2017) Diverse requirements for microglial survival, specification, and function revealed by defined-medium cultures. Neuron 94, 759–73.

Brosius Lutz A, Chung WS, Sloan SA, Carson GA, Lovelett E, Posadac S, Zhou L, Zuchero JB, Barres BA (2017) Schwann cells use TAM receptor-mediated phagocytosis in addition to autophagy to clear myelin in a mouse model of nerve injury. Proc. Natl. Acad. Sci. USA, in press.

Bujalka H, Koenning M, Jackson S, Perreau VM, Pope B, Hay CM, Mitew S, Hill AF, Lu QR, Wegner M, Srinivasan R, Svaren J, Willingham M, Barres BA, Emery B (2013) MYRF is a membrane associated transcription factor that autoproteolytically cleaves to directly activate myelin genes. PLOS Biol. 11(8), e1001625.

Cagla E, Susman M, Allen NJ, Huberman A, … Luo ZD, Mosher D, Barres BA (2009) Identification of the neuronal thrombospondin receptor that induces CNS synapse formation as the gabapentin receptor cacna2d1. Cell 139, 380–92.

Cahoy JD, Emery B, Kaushal A, Foo LC, Zamanian JL, Christopherson KS, Xing Y, Lubischer JL, Krieg PA, Krupenko SA, Thompson WJ, Barres BA (2008) A transcriptome database for astrocytes, neurons, and oligodendrocytes: a new resource for understanding brain development and function. J. Neurosci. 28, 264–78.

Chan JR, Watkins T, Cosgaya J, Zhang C, Chen L, Reichardt L, Shooter E, Barres B (2004) NGF controls axonal receptivity to myelination by Schwann cells and oligodendrocytes. Neuron 43, 183–91.

Cheng TW, Liu XB, Faulkner RL, Stephan AH, Barres BA, Huberman AD, Cheng HJ. (2010) Emergence of lamina-specific retinal ganglion cell connectivity by axon arbor retraction and synapse elimination. J. Neurosci. 30, 16376–82.

Christopherson K, Ullian EM, Stokes C, Mullowny C, Hell JW, Agah A, Lawler J, Mosher D, Bornstein P, Barres BA (2005) Thrombospondins are astrocyte-secreted proteins that promote CNS synaptogenesis. Cell 120, 421–33

Chung WS, Verghese PB, Chakraborty C, Joung J, Hyman BT, Ulrich JD, Holtzman DM, Barres BA (2016) Novel allele-dependent role for APOE in controlling the rate of synapse pruning by astrocytes. Proc. Natl. Acad. Sci. USA 113, 10186–91.

Chung WS, Wang G, Stafford B, Sher A, Chakraborty C, Joung J, Foo L, Smith SJ, Barres BA (2013) Astrocytes mediate synapse elimination and neural circuit refinement through the MEGF10 and MERTK phagocytic pathways. Nature 504, 394–400.

Clarke L, Heiman M, Chakraborty C, Barres BA (2017) Characterization of the aging mouse astrocyte transcriptome. Neuron, submitted.

Daneman R, Agalliu D, Zhou L, Kuhnert F, Kuo CJ, Barres BA (2009) Wnt signaling is necessary for CNS, but not non-CNS, angiogenesis. Proc. Natl. Acad. Sci. USA 106, 641–7.

Daneman R, Zhou L, Kebede AA, Barres BA (2010a) Pericytes are required for blood-brain barrier integrity during embryogenesis. Nature 468, 562–6.

Daneman R, Zhou L, Agalliu D, Cahoy JD, Kaushal A, Barres BA (2010b) The mouse blood-brain barrier transcriptome: a new resource for understanding the development and function of brain endothelial cells. PLOS One 5(10), e13741.

Darmanis S, Sloan SA, Zhang Y, Enge M, Caneda C, Shuer LM, Hayden Gephart MG, Barres BA, Quake SR (2015) A survey of human brain transcriptome diversity at the single cell level. Proc. Natl. Acad. Sci. USA 112, 7285–90.

Dugas J, Ngai J, Barres B (2006) Functional genomic analysis revels that terminal oligodendrocyte differentiation proceeds in distinct temporal stages. J. Neurosci. 26 (43), 10967–83.

Dugas J, Barres B (2007) A crucial role for p57Kip2 in the intracellular timer that controls oligodendrocyte differentiation. J. Neurosci. 27, 6185–96.

Dugas J, Mandemakers W, Rogers M, Ibrahim A, Daneman R, Barres B (2008) A new purification method for CNS projection neurons leads to the identification of brain vascular cells as a source of trophic support for corticospinal motor neurons. J. Neurosci. 28, 8294–305.

Dugas J, Cuellar T, … McManus M, Barres B (2010) Dicer1 and miR-219 are required for normal oligodendrocyte differentiation and myelination. Neuron 65, 597–611.

Dugas JC, Ibrahim A, Barres BA (2012) The T3-induced gene KLF9 regulates oligodendrocyte differentiation and myelin regeneration. Mol. Cell. Neurosci. 50, 45–57.

Emery B, Agalliu D, Rowitch D, Barres B (2009) Identification of myelin-gene regulatory factor as a critical transcriptional regulator required for CNS myelin gene expression and myelination. Cell 138, 172–85.

Foo L, Allen NJ, Bushong EA, Ventura PB, Chung WS, Zhou L, Cahoy JD, Daneman R, Zong H, Ellisman MH, Barres B (2011) A new method to purify and culture rodent astrocytes. Neuron 71, 799–811.

Goldberg JL, Barres BA (2000) The relationship between neuronal survival and regeneration. Annu. Rev. Neurosci. 23, 579–612.

Goldberg J, Espinosa K, Xu Y, Davidson N, Kovacs G, Barres BA (2002) CNS axon extension does not occur by default but is stimulated by electrical activity together with neurotrophic factors. Neuron 33, 689–702.

Goldberg J, Daneman R, Hua Y, Barres BA (2002) An irreversible, neonatal switch from axonal to dendritic growth in the developing CNS. Science 296, 1860–4.

Goldberg J, Vargas M, Mandemakers W, Barres BA (2004) Inhibition of retinal ganglion cell regeneration by oligodendrocyte derived semaphorin 5A. J. Neurosci. 24, 4989–99.

Hanson, G, Shen S, Wiemelt A, McMorris FA, Barres BA (1998) cAMP elevation is sufficient to promote the survival of spinal motor neurons. J. Neurosci. 18, 7361–71.

Hong S, Beja-Glasser VF, Nfonoyim BM, Frouin A, Li S, Ramakrishnan S, Merry KM, Shi Q, Rosenthal A, Barres BA, Lemere CA, Selkoe DJ, Stevens B (2016) Complement and microglia mediate early synapse loss in Alzheimer mouse models. Science 352, 712–6.

Howell GR, … , Barres BA, Libby RT, John S (2011) Complement cascade and endothelin receptor blockade powerfully lessen neurodegeneration in a mouse model of glaucoma. J. Clin. Invest. 121, 1429–44.

Huberman A, Manu A, … , Ullian E, Baccus S, Barres B (2008) Architecture and activity-mediated refinement of axonal projections from a mosaic of genetically identified retinal ganglion cells. Neuron 59, 425–438.

Huberman A, Wei W, Elstrott J, Stafford B, Feller M, Barres B (2009) Genetic identification of an on-off direction-selective retinal ganglion cell subtype reveals a layer-specific subcortical map of posterior motion. Neuron 62, 327–34.

Humphries, C (2017) Measuring up. MIT Technol. Rev. 120 (August 16).

Kaplan, M, Meyer-Franke A, Lambert S, Bennett V, Duncan ID, Levinson SR, Barres BA (1997) Soluble oligodendrocyte-derived signals induce regularly-spaced sodium channel clusters along CNS axons. Nature 386, 724–28.

Kaplan M, Cho M, Isom L, Levinson R, Barres B (2001) Differential control of clustering of the sodium channels Nav1.2 and Nav1.6 at developing CNS nodes of Ranvier. Neuron 30, 105–19.

Knowland D, Arac A, Sekiguchi KJ, Hsu M, Lutz SE, Perrino J, Steinberg GK, Barres BA, Nimmerjahn A, Agalliu D (2014) Stepwise recruitment of transcellular and paracellular pathways underlies blood brain barrier breakdown in stroke. Neuron 82, 603–17.

Kucukdereli H, Allen NJ, Lee AT, Feng A, Ozlu MI, Conatser LM, Chakraborty C, Workman G, Weaver M, Sage EH, Barres BA, Eroglu C. (2011) Control of excitatory CNS synaptogenesis by astrocyte-secreted proteins hevin and SPARC. Proc. Natl. Acad. Sci. USA 108, E440–9.

Liddelow S, Guttenplan K, Clarke L, Bennett F, Bohlen C, Schirmer L, Bennett M, Munch A, Chung W, Peterson T, Wilton D, Frouin A, Napier B, Panicker N, Kumar M, Buckwalter M, Rowitch D, Dawson V, Dawson T, Stevens B, Barres B (2017) Neurotoxic reactive astrocytes are induced by activated microglia. Nature 541, 481–87

Liddelow S, Barres BA (2017) Reactive astrocytes: production, function and therapeutic potential. Immunity 46, 957–67.

Lim JH, Stafford BK, Nguyen PL, Lien BV, Wang C, Zukor K, He Z, Huberman AD (2016) Neural activity promotes long-distance, target specific regeneration of adult retinal axon. Nat. Neurosci. 19, 1073–84.

Lui H, Zhang J, Makinson, Barres BA, Huang EJ (2016) Progranulin deficiency promotes circuit specific synaptic pruning by microglia via complement activation. Cell 165, 921–35.

McGonigal R, Cunningham ME, Yao D, Barrie JA, Sankaranarayanan S, Fewou SN, Furukawa K, Yednock TA, Willison HJ (2016) C1q-targeted inhibition of the classical complement pathway prevent injury in a novel mouse model of acute motor axonal neuropathy. Acta Neuropathol. Commun. 4, 23.

Meyer-Franke A, Kaplan M, Pfrieger F, Barres BA (1995) Characterization of the signaling interactions that promote the survival and growth of developing retinal ganglion cells in culture. Neuron 15, 805–19.

Meyer-Franke A, Wilkinson G, Kruttgen A, Hu M, Munro E, Hanson M, Reichardt L, and Barres BA (1998) Depolarization and cAMP recruit TrkB to the plasma membrane of CNS neurons. Neuron 21, 681–93.

Meyer-Franke A, Barres BA (1999) Astrocyte-induced adhesion of axons and oligodendrocytes. Mol. Cell Neurosci. 14, 385–97.

Mi H, Barres BA (1998) Purification and characterization of astrocyte precursor cells in the developing rat optic nerve. J. Neurosci. 19, 1049–1061.

Mi H, Haeberle H, Barres BA (2001) Endothelial cells induce astrocyte differentiation. J. Neurosci. 2, 1538–47.

Osterhout JA, Josten N, Yamada J, Pan F, Wu SW, Nguyen PL, Panagiotakos G, Inoue YU, Egusa SF, Volgyi B, Inoue T, Bloomfield SA, Barres BA, Berson DM, Feldheim DA, Huberman AD (2011) Cadherin-6 mediates axon-target matching in a non image forming visual circuit. Neuron 71, 632–9.

Pasca A, Sloan S, Clarke L, Tian Y, Makinson C, Huber N, … Barres BA, Pasca S (2015) Generation of functional cortical neurons and astrocytes from human pluripotent stem cells in 3D cultures. Nature Methods 12, 671–8.

Pfrieger F, Barres BA (1997) Glial cells regulate synaptic efficacy. Science 277, 1684–87.

Phuan PW, Zhang H, Asavapanumas N, Leviten M, Rosenthal A, Tradtrantip L, Verkman AS (2013) C1q-targeted monoclonal antibody prevents complement-dependent cytotoxicity and neuropathology in in vitro and mouse models of neuromyelitis optica. Acta Neuropathol. 125, 829–40.

Schafer DP, Lehrman EK, Kautzman AG, Koyama R, Mardinly AR, Yamasaki R, Ransohoff RM, Greenberg ME, Barres BA, Stevens B (2012) Microglia sculpt postnatal neural circuits in an activity and complement-dependent manner. Neuron 74, 691–705.

Scholze AR, Foo LC, Mulinyawe S, Barres BA (2014) BMP signaling in astrocytes downregulates EGFR to modulate survival and maturation. PLOS One 9(10), e110668.

Shen S, Wiemelt AP, McMorris FA, Barres BA (1999) Retinal ganglion cells lose trophic responsiveness after axotomy. Neuron 23, 285–95.

Shi, JY, Marinovich A, Barres BA (1998) Purification and characterization of adult oligodendrocyte precursor cells, J. Neurosci. 18, 4627–4636

Shimomura Y, Agalliu D, … Barres B, Christiano A (2010) Mutations in the novel Wnt inhibitor Apcdd1 underlie hereditary hypotrichosis simplex. Nature 464, 1043–7.

Sloan SA, Darmanis S, Huber N, Khan T, Birey F, Caneda C, Reimer R, Quake SR, Barres B, Pasca S (2017) Human astrocyte maturation captured in 3d cerebral cortical spheroids derived from pluripotent stem cells. Neuron, in press.

Stephan AH, Madison DV, Mateos JM, Fraser DA, Lovelett EA, Coutellier L, Kim L, Tsai HH, Huang EJ, Rowitch DH, Berns DS, Tenner AJ, Shamloo M, Barres BA (2013) A dramatic increase in C1q protein in the CNS during normal brain aging. J. Neurosci. 33, 13460–74.

Stevens B, Allen N, Huberman H, … , Lambris J, John S, Barres B (2007) The classical complement cascade mediates developmental CNS synapse elimination. Cell 131, 1164–68.

Ullian E, Sapperstein S, Christopherson K, Barres BA (2001) Control of synapse number by glia. Science 291, 657–61.

Ullian EM, Harris BT, Wu A, Barres BA (2004) Schwann cells strongly promote synapse formation by spinal motor neurons in culture. Mol. Cell Neurosci. 25, 241–51.

Ullian EM, Barkis W, Chen S, Diamond J, Barres BA (2004) Invulnerability of retinal ganglion cells to glutamate excitotoxicity. Mol. Cell Neurosci. 26, 544–57.

Vargas ME, Watanabe J, Singh SJ, Robinson WH, Barres BA (2010) Endogenous antibodies promote rapid myelin clearance and effective axon regeneration after nerve injury. Proc. Natl. Acad. Sci. USA 107, 11993–8.

Vukojicic A, Delestree N, Fletcher E, Sankaranarayanan S, Yednock T, Barres B, Mentis G (2017) Complement and microglia mediated sensory-motor synaptic loss in spinal muscular atrophy. Soc. Neurosci. abstract.

Wang JT, Kunzevitzky NJ, Dugas JC, Cameron M, Barres BA, Goldberg JL (2007) Disease gene candidates revealed by expression profiling of retinal ganglion cell development. J. Neurosci. 27, 8593–603.

Wang S, Sdrulla A, diSibio G, Bush G, Nofziger D, Hicks C, Weinmaster G, Barres BA (1998) Notch receptor activation inhibits oligodendrocyte differentiation. Neuron 21, 63–75.

Wang S, Barres BA (2001) Control of oligodendrocyte differentiation by Id2. Neuron 29, 603–14.

Wang JT, Medress ZA, Vargas ME, Barres BA (2015) Local axonal protection by Wlds as revealed by conditional regulation of protein stability. Proc. Natl. Acad. Sci. USA 112, 10093–100.

Watkins TA, Emery B, Mulinyawe S, Barres BA (2008) Distinct stages of myelination regulated by gamma secretase and astrocytes in a rapidly myelinating CNS co-culture system. Neuron 60, 555–69.

Winzeler A, Mandemakers W, Sun M, Stafford M, Phillips C, Barres B (2011) The lipid sulfatide is a novel myelin-associated inhibitor of CNS axon outgrowth. J. Neurosci. 31, 6481–92.

Zamanian JL, Xu L, Foo LC, Nouri N, Zhou L, Giffard RG, Barres BA (2012) Genomic analysis of reactive astrogliosis. J. Neurosci. 32, 6391–410.

Zamanian, JL, Zhou, L, Barres, BA (2017) Astrocytes promote CNS neuronal survival by secretion of sulfated glycosaminoglycans. Proc. Natl. Acad. Sci. USA, in preparation.

Zhang Y, Chen K, Sloan S, Barres BA, Wu JQ (2014) An RNA-sequencing transcriptome and splicing database of glia, neurons, and vascular cells of the cerebral cortex. J. Neurosci. 34, 11929–47.

Zhang Y, Sloan S, Calrke L, Caneda C, Plaza C, Blumenthal P, Vogel H, Steinberg GK, Edwards MS, Li G, Dunctan JA, Cheshier S, Shuer L, Chang E, Grant G, Hayden-Gephart MG, Barres BA (2016) Purification and characterization of progenitor and mature human astrocytes reveals transcriptional and functional differences with mouse. Neuron 89, 37–53.

Zuchero JB, Fu MM, Sloan SA, Ibrahim A, Olson A, Zaremba A, Dugas JC, Wienbar S, Caprariello AV, Kantor C, Leonoudakus D, Lariosa-Willingham K, Kronenberg G, Gertz K, Soderling SH, Miller RH, Barres BA (2015) CNS myelin wrapping is driven by actin disassembly. Dev. Cell 34, 152–67.

Anders Björklund

BORN:

Söderhamn, Sweden

July 11, 1945

EDUCATION:

Lund University, Sweden, Med. Candidate (1966)

Lund University, Sweden, MD, PhD (1969)

University of Oxford, UK, MS (1989)

APPOINTMENTS:

Docent of Histology, Lund University, Sweden (1970)

Associate Professor of Histology (Lektor), Lund University, Sweden (1973)

Professor of Histology, Lund University, Sweden (1983)

Visiting Professor at the College de France, Paris (April 1985)

Newton-Abraham Visiting Professor, University of Oxford, United Kingdom (1989–1990)

Senior Professor, Lund University, Sweden (2012)

HONORS AND AWARDS (SELECTED)

Doctor Honoris Causa, University of Turin, Italy (1987)

Doctor Honoris Causa, University of Copenhagen, Denmark (1989)

Member of the Royal Swedish Academy of Sciences (1989–present)

The Zulch Prize from the Max-Planck Society, Germany (1990)

The IPSEN Prize in Neuronal Plasticity, Paris (1990)

The Charles A. Dana Award from the Dana Foundation, New York (1993)

The Anders Jahre Prize for Medical Research, Oslo, Norway (1995)

The Söderberg Prize for Medical Research from Swedish Society for Medicine (2000)

The Wendell Krieg Lifetime Achievement Award from the Cajal Club (2006)

The Robert A Pritzker Prize from the Michael J Fox Foundation (2011–present)

The Eric K Fernström Nordic Prize (2011)

Foreign Associate of the National Academy of Sciences, USA (2011–present)

Anders Björklund received his MD and PhD at Lund University in Sweden in 1969 and has spent his entire academic career at this institution. He was appointed professor of histology in 1983, and since 2012, is senior professor at the Wallenberg Neuroscience Center in Lund. He was president of the European Neuroscience Association 1996–1998 and served as chairman of the Neuroscience Panel at the European Research Council in Brussels in 2007–2010. He was elected member of the Royal Swedish Academy of Sciences in 1989, and foreign member of the National Academy of Sciences, USA, in 2011. His main research interests are in studies of brain regeneration and repair, with a focus on cell replacement and gene therapy in neurodegenerative diseases. In the 1970s, his team pioneered the development of methods for cell transplantation to the brain, and over the following decades, Björklund’s team at Lund University has pioneered the use of cell transplantation in Parkinson’s disease and has played an active role in the exploration of stem cells as a source of cells to be used for this purpose.

Anders Björklund

As a scientist I have been passionately curiosity driven, always looking forward to the next experiment and exploring new ideas. This has made me, I believe, more interested in what is ahead of me rather than recording the events as they happen. I have been poor at taking notes of events and I have kept no diary, so when I now endeavor to recall how my research has evolved over the years, I have had to resort to my notoriously imprecise memory and the support I have found in my correspondence, which, before the Internet era, I had collected in 60 thick files.

Looking back, I realize that this lack of detailed written records has helped me to retain the positive memories and the fascination and excitement embedded in the pursuit of new ideas and the exploration of the unknown. And my luck was that I entered brain research at the time, in the late 1960s, when modern neuroscience was born, and in the laboratory where a new groundbreaking microscopic technique, the Falck-Hillarp monoamine histofluorescence method, had just been developed. It was like walking into an open landscape: Everything was new, and everything was possible. Memories of failed experiments, rejected papers, and frustrating struggles for grant money all seem to kindly fade away with time. And wisely were not kept on record.

My research career has been unadventurous in the sense that I have remained at the same institution, Lund University in Sweden, where I started my medical studies in 1964. I was drawn into research already during my second year in medical school, and full of enthusiasm I finished my hybrid MD/PhD thesis in two and a half years. I was then 24 years old and had to decide whether I wanted to complete my medical training or stay in research. For a few years, I entertained the possibility to go abroad on a postdoc, but the support and the laboratory resources provided by my mentor Bengt Falck made it less attractive to leave Lund, particularly since Bengt generously gave me the freedom to develop my own ideas and pursue my own research. It was unlikely that I could find similar opportunities elsewhere. And over time, I have become very fond of Lund—a small, practical, and very friendly town that combines the very old with the very new, dominated by the university and its lively student activities. A good place for a compulsive thinker like me! Instead of moving elsewhere I have been fortunate to spend three stimulating sabbaticals abroad, with my family. Twice with Susan Iversen and Steve Dunnett in Cambridge, United Kingdom, and once with Paul Bolam and Peter Somogyi in Oxford. In retrospect, it is clear that these visits were important and given me opportunities not only to “recharge my batteries” but also to reflect and find new directions for my research.

Early Days

I think it was inevitable that I should end up as an academic. My parents were both university educated, at Uppsala University, and it was there they met and formed a family. My father studied to become a clergyman, but he soon realized that a job in the Swedish state church was not for him. So after just a couple of years as a clergy, he decided to return to Uppsala to complete his licentiate degree and become a high school teacher in philosophy and religion. My mother also studied to become a teacher, in English and Swedish literature, and their first jobs were in a small town north of Uppsala, Söderhamn, where I was born, three years after my older brother. A year later, we moved further north to Boden, a town close to the pole circle where a new gymnasium (high school) had just opened, offering them both good teaching jobs. Boden was at the time known for housing four military regiments (all gone now), and thus was full of young men completing their (compulsory) military service. When I turned eight, my parents had had enough of the cold and dark winters up north and moved to Växjö, a bigger town centrally located in southern Sweden, known for its cathedral and as a bishop’s site, and with an old cathedral school where the famous botanist Carl Linnaeus had spent his formative years.

It was here, in Växjö, that I went to school and finished my studentexamen (high school exam). Like my older brother, I was an exemplary student. My favorite subjects were physics and math. I had superb and engaged teachers and was initially convinced that I wanted to study these subjects also at the university. However, the fact that several of my classmates planned to apply to medical school made me rethink my plan. So to keep this option open, I had to add biology as my extra subject in my last year, a necessary complement if I wanted to go to medical school. The cathedral school in Växjö was full of highly qualified teachers with the ability to stimulate and engage the students, and my biology teacher was one of them. I realized that studies of living matter were very special and, at this time, a decade after the discovery of the double helix, it became clear to me that biology had become an exciting subject.

How It Started

I began my medical studies in Lund in 1964. Lodging in the student dormitories was difficult to find for the newcomers, so for the first two years, I rented a room from a lovely octogenarian widow who treated me with tea and sandwiches on a tray in my room on Sunday mornings. There I stayed until I found my own small apartment, with bathroom and a tiny kitchenette, conveniently located above a fine gourmet shop on one of the main shopping streets, just a 10 minute walk from the Histology Department where I now was employed as part-time teaching assistant, amanuens as it was called. There were three of us, and our job was to be present during the microscopy lectures, run the microscopy projector, and assist the students at the microscope and in the lab practicals. Rather boring but the salary, though small (250 SEK, around US$20, per month at that time) was a good addition to the state-guaranteed student loan that had just been introduced.

The reason I ended up in histology was twofold: I enjoyed doing microscopy and found that I was quite good at it. And in the histology course, the associate professor Bengt Falck had given a lecture on a topic that had intrigued me: a new microscopic method that allowed visualization of neurotransmitters in microscope sections. At the end of the lecture, Bengt said that he would welcome any interested student to visit his lab. In the following break, I persuaded one of my fellow students, another Anders, to give it a try. We were the only two in the class to turn up, and Bengt told us that we were welcome to follow the work in the lab and try our hands on the new method in our spare time. Spare time was no problem for me, but for the other Anders “spare time” soon disappeared when he became the father of twins.

The new method, now named the Falck-Hillarp histofluorescence method, had been developed a few years earlier by Bengt and his mentor and senior colleague Nils-Åke Hillarp. Bengt and Nils-Åke had been exploring various ideas on how to visualize noradrenaline in the microscope and the one that finally worked was based on the use of hot gaseous formaldehyde to convert the nonfluorescent catecholamines to fluorescent tetrahydro-isoquinolines that could be detected under blue-violet light in a fluorescence microscope, shining with a yellow-green color. The method was published in 1962 and at the time when I walked into Bengt’s lab, in 1965, it was clear that it had opened tremendous opportunities, not only for Bengt and his collaborators, but also for the lab at the Karolinska Institute in Stockholm that Hillarp had started when he moved there as professor in 1962. I learned that Hillarp had sadly died from a malignant melanoma, but in the short time he was active in Stockholm, he had assembled a tremendous team of young students and collaborators, including Kjell Fuxe, Annica Dahlström, Gösta Jonsson, Urban Ungerstedt, and Lars Olson, who all went on to make important contributions to the budding field of monoamine research.

Looking back, it is clear that the F-H method came to play a very important role in the study of monoamine neurotransmitters, dopamine, noradrenaline and serotonin. It made possible, for the first time, the anatomical mapping of the monoamine systems in the nervous system, not only in mammals but across species, and it opened entirely new opportunities for pharmacological and functional studies of dopaminergic, noradrenergic, and serotonergic neurotransmission in both the central nervous system (CNS) and PNS. It dominated the field for about two decades, until the mid-1980s, when immunohistochemistry took the lead. During that time the Swedish labs in Lund, Stockholm, and Göteborg remained at the forefront, driving the technical development and setting the standards for how it should be applied. The fact that it was technically tricky worked against it being more widely spread. The method used a freeze-drying procedure to remove water from the tissue blocks. This step was capricious and could easily go wrong, and it seemed that it did not work well in warm and more humid climates, such as—we were told—in Floyd Bloom’s lab in Washington. Our cold climate apparently played to our advantage in this case.

I was lucky to join Bengt’s lab at the time when the method was in full swing and the opportunities were endless. The lab was housed in a modest dwelling, a wooden annex to the main department and because of its color popularly known as “the pink barrack.” Bengt’s main interest at this time was in endocrinology and reproduction, and he had a close collaboration with a clever zoologist, Anders Enemar, who was engaged in a project to describe the development of the catecholamine system in the hypothalamo-pituitary system in the mouse. I rapidly got on friendly terms with him, and he invited me to join as a collaborator in this project. At the same time Bengt suggested that I should take on a project that involved measurements of dopamine and noradrenaline levels in the different subportions of the pituitary (the anterior, posterior, and intermediate lobes) and the hypothalamic median eminence. This could not be easily done in rats and mice, but he had good contacts with the local slaughterhouse where they regularly extracted pituitaries from pigs (delivered to a local pharmaceutical company for extraction of human pituitary hormones). Bengt arranged for me to go there early in the morning, before my lectures started, to collect the tissues. His lab had an old mini-truck that I could use to get there. So once a week, I went up early in the morning, drove the 15 km to Kävlinge, collected the dissected tissue in tubes frozen in dry ice, delivered them to the Evald Rosengren’s biochemistry lab in pharmacology, and then off to the start of the first lecture of the day. I mostly made it, as I recall!

Years earlier Evald, then a doctoral student in Arvid Carlsson’s department, had published the first description of the regional distribution of dopamine in the brain. This study had been published together with his fellow MD student Åke Bertler in the Swiss journal Experientia in 1959, less than a year after Carlsson’s seminal Science paper on the presence of dopamine in the brain. They found that dopamine was highly concentrated in the striatum, which led them to conclude that

the results favour the assumption that dopamine is concerned with the function of the corpus striatum and thus with the control of motor function. This view is supported by the fact that drugs which influence the dopamine content of the striatum also produce disturbances of motor activity… . Excess of dopamine in the brain produced by administration of DOPA is accompanied by motor hyperactivity. (Bertler and Rosengren 1959)

As described in his autobiographical chapter in volume 4 of this series (Hornykiewicz 2004), it was this paper that triggered Oleh Hornykiewicz, a young pharmacologist in Vienna, to initiate his classic postmortem studies of dopamine in brains of patients with Parkinson’s disease (PD). After his dissertation in 1960 Evald moved with Arvid Carlsson to Göteborg and returned a few years later to a professorship in Lund where he initiated a fruitful collaboration with Bengt and his team that lasted until his retirement.

This pig study led to my first scientific paper, which was submitted to Life Sciences in July 1967 with me as first author (Bjorklund et al. 1967; the convention at the Swedish universities at the time was to list authors in alphabetical order and the leading Scadinavian journal, Acta Physiologica Scadinavica, for example, had adopted this principle as a rule). Although limited in content, this eight-page article made me proud. I had been allowed to write the first draft myself, and this was my Opus 1! Emboldened, and much encouraged by Bengt, I decided to take a break in my medical studies and start as a full-time doctoral student in Bengt’s lab. The biochemical data in the Life Sciences paper strongly suggested the presence of a dopaminergic innervation of both the posterior and intermediate lobes of the pituitary. I went on to investigate that in further detail using the F-H method, and in two follow-up papers, published in Zeitshrift für Zellforschung in 1968 (Bjorklund et al. 1968), and in Brain Research in 1970 (Bjorklund et al. 1970), I could show the presence of a dense dopamine fiber network in these parts of the pituitary, in mouse, rats, cats, and pigs, originating in the hypothalamic A12 cell group previously described by Annica Dahlstöm and Kjell Fuxe in Stockholm. Tiny in size, of course, but I had discovered a previously unrecognized dopamine projection system. Not so bad, I thought!

The Glyoxylic Acid Method and My Neuroanatomical Work

When I defended my thesis in October 1969, it was clear that, rather than going back to my medical studies, I wanted to continue in the lab. At that time, I had been appointed to an assistant teacher job, and in 1970, I had acquired my docentship, which made it possible for me to act as supervisor of new doctoral students coming to the lab. It was a fantastic time. Bengt’s lab was like a hotbed, boiling with activity. It was also very well funded and offered unlimited possibilities for a young enthusiast like me. This was the place to be, I felt. Of the many young medical students and doctors working in Bengt’s lab at the time, six went on to develop highly successful independent research careers, eventually ending up as professors in the faculty: Christer Owman in histology, Berndt Ehinger in ophthalmology, Nils-Otto Sjöberg in obstetrics and gynecology, Frank Sundler in histology, Olle Lindvall in neurology, and myself in histology. Thus, the creative research environment in the pink barrack fostered a whole new generation of researchers with a major and lasting impact on the development of modern neuroscience in Lund.

During my thesis work, I had become involved in the efforts to optimize and improve the F-H method. The method was quite capricious: If the freeze-dried tissue was too dry, the formaldehyde reaction would not run, and if the tissue was too wet, the catecholamines would diffuse away from their storage sites. The Karolinska group had come up with a reasonably good way to standardize the reaction, that is, to add a defined amount of water to the paraformaldehyde powder by storing it at a predetermined humidity in a sealed container. Nevertheless, it was clear that the sensitivity was not optimal: It usually allowed good detection of cell bodies and the varicose beads of axon terminals, but not of preterminal axons and dendritic processes where the levels of catecholamines and serotonin are lower. There was clearly room for improvement.

At this time Olle Lindvall, a medical student two years younger than me, had joined the lab and Bengt suggested that he join me in this work. We decided to look for an alternative and more efficient reagent and set off to perform a screen of a broad range of so-called carbonyl compounds that could be expected to react with the monoamines in a similar way as formaldehyde. In this screen, which was performed on amines enclosed in dried albumin droplets, we zoomed in on one that seemed most promising: glyoxylic acid (GA). Formaldehyde has the chemical formula H-CHO. In GA, HOOC-CHO, the hydrogen is replaced by carboxylic acid. GA reacted with catecholamines and serotonin in a similar way as formaldehyde, but the yield and brightness of the fluorophores were considerably higher, resulting in a five- to eightfold increase in sensitivity compared with the standard F-H reaction. In our first attempts we exposed tissue sections to hot GA vapor, as used in the F-H method, but the best results were obtained with tissue that had been perfused with an ice-cold 2 percent GA solution (later with 0.5 percent formaldehyde added to obtain better fixation) followed by sectioning on a Vibratome, three- to five-minute immersion of the sections in GA, and heating at 100°C for 6 minutes. This allowed microscopy of the sections within half-an-hour after perfusion. Vibratome sectioning had just been introduced by Tomas Hökfelt at Karolinska, and our first application of the GA method to Vibratome sections was thus carried out during a short visit to Tomas’ lab in Stockholm, resulting in a short joint paper in Histochemie in 1973 (Lindvall et al. 1973).

The results obtained with the GA-Vibratome method were absolutely stunning: The fluorescence was bright and sharp against an essentially black background, axons and dendrites were visualized in their entirety, and even the tiniest of axonal braches and terminals were nicely detectable. Olle and I returned home full of excitement. We ordered first one, and soon after, two more Vibratomes and got started. It soon became clear to us that the new GA method allowed us to map the catecholamine systems in the brain with a sensitivity and precision that went far beyond what had been possible with the classic F-H method and, more important, we could detect previously unobserved axonal pathways and projections, such as the first demonstration of the midbrain dopamine projection to neocortex, the previously unknown projection of the A13 cell group in the zona incerta, and the storage of dopamine in the dendrites of the nigral dopamine neurons, suggesting a role of dopamine in dendritic terminals. Olle and I had a great time at the microscope and enjoyed the challenge of getting all the new findings published as quickly as possible. Over a little more than a year, we reported the new findings in five papers, published in rapid succession, including a detailed description of the organization of the ascending catecholamine projection systems in the rat brain that was published as a supplement to Acta Physiologica Scandinavica in 1974 (Lindvall and Bjorklund 1974). This paper has had major impact in the field and, over the years, has been cited (according to Google Scholar) more than 1,300 times. It also formed the core of Olle’s doctoral thesis, which he defended in May 1974.

Although very sensitive, the GA-Vibratome method was not well suited for processing of larger numbers of brains, such as in experimental studies in which the effects of interventions are compared between groups of animals. Vibratome sectioning was slow and had to be done more or less online and was less suitable for serial sectioning of larger specimens. For such studies, the F-H method was more attractive. Paraffin-embedded blocks of tissue, as used in this method, allowed bulk processing of a large number of specimens with a consistent fluorescence yield in samples processed together and facilitated storage, sectioning, and handling of the specimens. Thus, we continued our efforts to increase the sensitivity of the freeze-drying method. We focused on the fact that the formation of fluorophores in the F-H reaction is efficiently catalyzed by acids. In model experiments, we found that metal ions, like magnesium and aluminum, in particular, are efficient fluorescence-promoting agents in the formaldehyde reaction and that this effect can be explained by the fact that these metal ions are acids according to the so-called Lewis acid–base definition. In subsequent in vivo experiments, we could show that addition of aluminum sulfate to the formaldehyde perfusion solution markedly increased the sensitivity of the method for the detection of catecholamines by about fivefold.

The sensitivity of this improved method for the visualization of catecholamines, coined the ALFA (aluminum-formaldehyde) method, closely matched that obtained with the GA-Vibratome method. It was published in 1980 (Loren et al. 1980) and became the standard method in all our subsequent work. Using this versatile method, Olle and I, together with a talented PhD student, Gunnar Skagerberg, went on to explore and map several previously unrecognized dopamine projection systems, such as the dopaminergic projections from the diencephalic A11 cell group to the spinal cord (Skagerberg et al. 1982), the meso-habenular dopamine pathway (Skagerberg et al. 1984), and the dopaminergic innervation of the neuro-secretory paraventricular and supraoptic nuclei (Lindvall et al. 1984).

The grand finale of our neuroanatomical studies, spanning over more than a decade, was the publication of two major reviews, in Volume 2 of the Handbook of Chemical Neuroanatomy, in 1983, and in Volume 4 of the Handbook of Physiology, in 1986. When I look at them now, I am very pleased: Two decades after the pioneering work of Fuxe and Dahlström, Olle and I had provided the first fully comprehensive account of the anatomy of the dopamine and noradrenaline systems that remains on the whole accurate and still valid today. And the first of the two, in particular, has been very well cited over the years.

During the 1980s, it became gradually clear to us that the immunohistochemical (IHC) techniques were going to take over. Thanks to the increasing commercial availability of antibodies suitable for use on tissue sections, the IHC method had became highly versatile and also readily available for the wider research community. For visualization of catecholamine systems, the access to excellent tyrosine hydroxylase (TH) antibodies was the turning point, and at the end, we in Lund were also converted to TH immunostaining on cryostat or freeze-microtome sections. The very last studies in which the aluminium-formaldehyde (ALFA) method was used in Lund were published in 1988 and soon thereafter the imposing freeze-dryers that had been built in Lund were dismantled after more than 25 years of continuous use! As is often the case with technologies that are superseded by new technology, the F-H method, despite its historical impact and its dominance in the field over a quarter of a century, is virtually unknown to neuroscientists active today.

Serotonin Neurotoxins

In 1967, Hans Thoenen and Jean-Pierre Tranzer, working at the Hoffman-LaRoche company in Basel, discovered the ability of the noradrenaline analogue 6-hydroxydopamine (6-OHDA) to induce an acute and selective degeneration of sympathetic noradrenergic nerve terminals. This remarkable observation was rapidly picked up by a young graduate student in Stockholm, Urban Ungerstedt, who showed that this compound could be used for selective lesioning of dopamine and noradrenaline neurons also in the brain. Two years later, in 1970, Ungerstedt and Gordon Arbuthnott in a now-classic paper introduced the unilateral 6-OHDA lesion model, combined with the amphetamine-induced rotation test, which has become a standard tool in dopamine research and is still widely used today.

It was known that 6-OHDA acted as a “false transmitter” in catecholamine neurons, meaning that it was taken up and stored by the same transport systems as dopamine and noradrenaline. Because of its oxidative properties, however, 6-OHDA is easily auto-oxidized, leading to the formation of toxic reactive oxygen species within the target cell, leading to mitochondrial damage. The selectivity of 6-OHDA for catecholamine neurons is due to the fact that it is effectively taken up by the membrane transporter, leading to an accumulation of the drug selectively within dopamine and noradrenaline neurons. This mechanism suggested that similar neurotoxins could be developed for lesioning of the serotonin neurons in the brain.

This idea was picked up be a young anatomist in Hamburg, Hans-Georg Baumgarten. He had an ongoing collaboration with Bengt Falck using the F-H method to map the distribution of catecholamines in frogs, lizards, and lampreys, as well as in various human tissues, and I came to know him during his frequent visits to Lund. Inspired by the neurotoxic properties of 6-OHDA, and with the help of a clever chemist in Munich, H. G. Schlossberger, he arranged for the synthesis of hydroxylated derivatives of serotonin (5-hydroxy-tryptamine), and one day in 1970, he came to Lund with a sample of freshly synthesized 5-6-dihydroxy-tryptamine (5,6-DHT) and asked me if I wanted to join in the in vivo testing of this compound (Baumgarten et al. 1971). This was the start of a very productive collaboration that spanned almost a decade. With Schlossberger’s help, and through other sources, Baumgarten managed in the end to get access to more than 20 5-HT analogs that we tested both in vitro and in vivo. The most promising results were obtained with 5,6-DHT and 5,7-DHT, but both had their disadvantages: 5,6-DHT induced nonspecific tissue damage at higher doses, and 5,7-DHT had a significant toxic effect on noradrenergic neurons as well. We zoomed in on 5,7-DHT as the most effective and selective compound, and we found that the noncoselective damage to noradrenaline neurons could be effectively counteracted by coadministration with a catecholamine uptake blocker, DMI. 5,7-DHT, administered either intraventricularly or directly into the brain parenchyma, has remained a standard experimental tool for selective damage of serotonin neurons (Baumgarten et al. 1973; Bjorklund et al. 1975a).

In our studies of the effects induced by the intraventricular serotonin neurotoxin lesions, we made an intriguing observation: The damage induced by these neurotoxins was primarily hitting the axons and leaving the cell bodies intact. This was particularly striking in the descending serotonin projection from the brain stem to the spinal cord, the so-called bulbo-spinal serotonin system (Bjorklund et al. 1973). In the treated animals, axonal damage appeared within the first four days after injection. These swollen and distorted axonal profiles were mostly confined to the caudal medulla oblongata and at the junction to the spinal cord and was accompanied by a nearly complete loss of serotonin terminals at all levels of the cord after two to three weeks. This was followed by a remarkably efficient regenerative response, starting about one week after injection and progressing over the subsequent weeks and months. A near-normal innervation was restored in nuclei of the lower brain stem (inferior olive and facial nucleus) within a month, and in the rostral segments of the cervical spinal cord after about three months. At longer survival times, 7–12 months postinjection, regenerated axons and terminals also were observed further caudally, in the previously denervated thoracic segments, several centimeters below the initial axotomy (Bjorklund and Wiklund 1980; Wiklund and Bjorklund 1980).

The neurotoxin lesion apparently provided favorable conditions for efficient long-distance axon growth along the spinal cord. Compared with standard mechanical or electrolytic lesions, the regeneration of new axons in the toxin-treated rats takes place in brain tissue that is morphologically intact and in the absence of impeding necrotic tissue and scars. Strikingly, the regenerating axons were seen to re-innervate the correct terminal areas with a high degree of specificity, suggesting that the regrowth of the serotoninergic axons was controlled by precise mechanisms of guidance and recognition, a phenomenon that we were to explore in much greater detail in our cell transplantation studies.

How I Got Interested in CNS Regeneration

The studies of neurotoxin lesions were among the very first to demonstrate the ability of CNS neurons to regenerate efficiently, and over larger distances, after axotomy. My interest in central nervous system (CNS) regeneration, however, was triggered several years earlier thanks to an American neurologist, Bob Katzman, who spent a six-month sabbatical in Bengt Falck’s lab in 1969. I had just finished my PhD thesis and decided to stay on in Bengt’s lab and was put to work helping Bob in his experiments.

Bob wanted to find out where the therapeutically active dopamine is formed from L-DOPA when the intrinsic nigro-striatal dopamine system is removed. A young neurosurgeon, Kurt West, made electrolytic lesions unilaterally in the substantia nigra in rats, and the brains were processed for F-H fluorescence microscopy at varying time points. The localization of L-DOPA-derived dopamine turned out to be difficult to spot in the striatum. When looking at the sections through the nigra itself, we not only saw the damage caused by the lesion, and the associated loss of dopamine neurons, but also and most conspicuously a pattern of fine-caliber fluorescent fibers that was not there at short time points. They emerged over time, during the second and third week, most prominently along the border of the lesion and the electrode tracks and invading the walls of adjacent blood vessels and had all the features of regrowing noradrenaline containing axonal sprouts. This raised the possibility that they were derived from the sympathetic innervation of the meningeal vessels. They remained after sympathectomy, however, so we concluded that they must be of central origin, most probably derived from the noradrenergic axon bundle that passed through the lesioned area. This axon bundle, which originated in the locus coeruleus, was transected by the electrolytic lesion, and a closer inspection in the microscope suggested that the newly appearing delicate fibers were sprouts that had grown out from the severed axon stumps. This was one of these unexpected, serendipitous findings that easily could have gone unnoticed, but Bob convinced me that it was really important: Regeneration was not supposed to happen in the brain!

We published this study in Brain Research in 1971 (Katzman et al. 1971). These findings were indeed intriguing but how could we prove that these growing axons indeed were regenerating? Here, Ulf Stenevi comes on the stage. Ulf was a friend and classmate in medical school. For some reason, he decided to take a break from his medical studies and started a PhD project in Bengt’s lab. Perhaps he felt he needed to do something else for a while, or perhaps I had convinced him that lab work was fun and exciting. Anyway, when Ulf started in the lab in 1970, it was the beginning of a fantastically enjoyable and stimulating collaboration that lasted more than 15 years and resulted in nearly 90 joint publications, some of which I regard as my very best. It was a great partnership, and when I look back, I am amazed—on average, one publication every second month, including the years when Ulf qualified as a specialist in ophthalmology and entered a highly successful career in the clinic. We had complementary skills and worked very well together. Ulf was the imaginative experimentalist with a remarkable skill for advanced surgery in the rat brain, and I was the compulsive and driven thinker and the one organizing and leading the lab. An excellent combination, as it turned out!

In our discussions, Ulf came up with a somewhat odd but very clever idea: Why not challenge these axons with a noninnervated target and see whether these transected axons could regenerate a new noradrenergic innervation there? Ulf suggested that we use transplants of irises, placed so that they were in direct contact with the cut axons. Iris tissue was a classic experimental tool in Bengt’s lab. This tissue has a rich adrenergic innervation, and it was in the trials using whole-mounts of irises that Bengt and Nils-Åke Hillarp obtained their first successful images of noradrenaline fluorescence in sympathetic nerves in 1961. Ulf reasoned that these thin tissue sheets—mostly composed of smooth muscle and nerves—would stand a good chance to receive sufficient nourishment through diffusion from the extracellular fluid to survive in the brain parenchyma. This proved to be right.

Ulf devised a technique using a thin, flat glass rod to introduce the iris through a hole in the skull, passing ventrally through the brain parenchyma and crossing the bundle carrying the axons from the locus coeruleus, the so-called dorsal noradrenergic bundle, as well as the dopamine and serotonin axons running within the medial forebrain bundle (MFB). When the rod was gently removed, the iris was left in place in direct contact with the cut stumps of these two fiber tracts. The results were striking: The regrowing catecholamine axons invaded the entire iris tissue within three to four weeks and remained densely innervated by six months after the surgery (Bjorklund and Stenevi 1971). We soon found out that the transplanted irises could be removed from the brain and unfolded so that it could be spread out as a whole-mount on the microscope slide. Using this approach, we could study the dynamics and growth patterns of the regenerating noradrenaline axons in greater detail, all done in sympathectomised rats to exclude any involvement of sympathetic axons. In these whole-mounts, we could see that the regenerating noradrenergic axons growing from the transected dorsal bundle formed a well-developed terminal network. This network covered the entire iris within a month and mimicked very closely that of the normal sympathetic nerve supply, suggesting that the axons seek out and ramify along the denervated Schwann cell sheaths that form the so-called autonomic ground plexus within the smooth muscle of the iris (Svendgaard et al. 1975b). We went on to show that there was an extensive ingrowth of cholinergic axons as well, derived from the cholinergic axons running in the cingulum bundle and entering the transplants at their dorsal end. In double-stained whole-mounts, we could see that the noradrenergic and cholinergic innervations matched each other, suggesting that they ran together within the same neural sheets, as is the case in the intact iris (Svendgaard et al. 1976).

To us these findings provided compelling evidence that the same factors that promote and guide regeneration of peripheral sympathetic and parasympathetic axons can operate also on lesioned noradrenergic and cholinergic neurons in the brain and that this effect also was retained in iris transplants that were chronically denervated by at least a month before transplantation. The role of Schwann cells in axonal regeneration has been extensively studies over the years, and we know fairly well today that their role in promotion and guidance of regeneration peripheral axons is mediated by a mixture of growth factors, growth factor receptors, and cell-specific guidance molecules, some of which also are likely to operate in the CNS.

We published this extensive work in four papers in 1975–1976, one of them as a monograph in the Springer series called Advances in Anatomy Embryology and Cell Biology in 1975 (Svendgaard et al. 1975b). This turned out to be an unfortunate choice. According to Google Scholar this 76-page long paper has received zero citations over the ensuing years. What I am most proud of in this study are the illustrations. To be able to illustrate the complete outgrowth picture in the iris whole mounts, we used a combination of photomontages (composed of a grid of more than 50 individual pictures captured at 10 × magnification in the fluorescence microscope) and camera lucida-type ink drawings that I did in a large format. They look really nice and I still have one of these on the wall in my study.

Two other papers, published in Nature (Bjorklund et al. 1975b; Svendgaard et al. 1975a), received more attention (my first Nature papers!). In the first of these, we reported electrophysiological evidence of functional noradrenergic and cholinergic neurotransmission in the reinnervated transplants and concluded that

an important implication of the current studies on the reinnervation of peripheral transplants in the CNS would be that—when given the same growth conditions as in the peripheral nervous system—at least some neurone systems in the mammalian CNS will show an entirely adequate regenerative capacity resulting in restitution of normal neurotransmission in the denervated tissue.

A few years later, this lead was picked up by Albert Aguayo in Montreal who went on to publish a series of seminal studies using grafts of peripheral nerves as conduits for regenerating axons in the spinal cord and the retino-tectal system. One day in December 1979, he came on a visit to Lund to talk about his recent work on the regeneration of CNS neurons into nerve grafts, which was then in press in Nature. This was the beginning of a lifelong friendship that has involved not only stimulating scientific interactions and joint publications but also enjoyable contacts between our families.

Cell Transplantation: How It Started

In the neuroscience community, I am best known as one of the pioneers in the development of cell transplantation in the CNS. When I go back to the protocols in my picture archive, I see that Ulf and I made some early pilot experiments already in 1971 using neonatal sympathetic ganglia implanted directly into the brain parenchyma, but it was in the summer and autumn of 1973 that we took it up in a more serious way.

We were inspired not only by the intriguing results we had obtained in the experiments using transplants of iris and other peripheral tissues, but importantly also by Lars Olson’s work at the Karolinska Institute in Stockholm. He had, as part of his PhD thesis, published a study on sympathetic ganglia transplanted to the anterior eye chamber in 1970, and in December 1972, Lars and his then-PhD student Åke Seiger published a paper in Zeitschrift für Zellforschung in which they reported observations from experiments using transplants of pieces of fetal and neonatal CNS tissue implanted into the anterior eye chamber. This paper caught my attention: Immature dopamine, noradrenaline, or serotonin neurons contained in small pieces of brain stem tissue, 1–3 mm³, were shown to survive and grow after transplantation provided that they were taken from fetal donors. If they survive in the eye, it should be possible to make them survive also in the brain, I thought.

In the first series of experiments, we dissected pieces from the ventral midbrain (VM) and dorsal pons of late-stage fetal rat fetuses, similar in age to the ones used in the Olson and Seiger paper, and we deposited them into the VM of adult rats with the help of a metal cannula fitted with a plunger to extrude the tissue. Most of these transplants did not make it, but in some interesting cases, the dopamine and noradrenaline neurons, visualized with the F-H method, were seen to survive. After a while, we realized that these transplants were mostly located in direct contact with the underlying pia, suggesting that this richly vascularized membrane could provide an important vascular support for the grafted tissue. This triggered Ulf to test an alternative approach, that is, to place the graft pieces directly onto the pia on the caudal surface of the midbrain. The approach he adopted was to suck away a piece of cortex, including a piece of the hippocampus, to expose the pia overlying the midbrain tectum. After all the bleeding was stopped (which could take some time), he placed the dissected piece on the pia and in direct contact with the cut surface of the hippocampus, and then filled the cavity with gelfoam. After some trial and error (apparent in the microscopy pictures I have saved in my photo archive), these efforts started to pay off. It was in the spring and summer of 1974 that we obtained the first results that convinced us that this was going to work. Although the outcome was still variable, the most successful specimens showed excellent survival of all three fetal neuron types, and also of pieces of superior cervical ganglia. The most striking finding, and the finding that made us really excited, was the extent of axonal outgrowth into the host hippocampus.

Over the next year, we worked to optimize and standardize the results. This concerned both the fetal donor age, the landmarks for dissection of the fetal tissue and refinement of the surgical procedure. We started to use rats treated with 6-OHDA or 5,7-DHT (to remove the noradrenergic and serotonergic innervation of the hippocampal formation), and Ulf introduced a second graft site: on the pia overlying the rostral thalamus, exposed through a suction lesion made to include the fimbria-fornix bundle. This lesion, which severed the connections between septum and the hippocampal formation, was effective in removing the cholinergic innervation of the entire hippocampal formation, save for its most ventral tip.

In the autumn of 1975, we were ready to publish the first two papers (Bjorklund et al. 1976; Stenevi et al. 1976). One contained a detailed account of the results with a focus on the rate of survival of fetal grafts placed in various locations, which we submitted to Brain Research, our household journal at the time. In the second paper, which we got published in Nature, we reported on the remarkable ability of grafted noradrenergic, dopaminergic, and serotonergic neurons to reinnervate the previously denervated hippocampus. A year later we followed this up with a study on the capacity of fetal septal cholinergic neurons to reinnervate the hippocampus in rats with lesions of the intrinsic septo-hippocampal pathway (Bjorklund and Stenevi 1977). The most intriguing finding in these studies was that different types of neurons, although growing along the same route, formed distinctly different and highly consistent terminal innervation patterns in the hippocampus. Thus, the innervation pattern generated by the grafted noradrenergic or cholinergic neurons appeared closely similar to that of the normal innervation patterns, while the terminal distribution of the dopaminergic and serotonergic innervations were entirely different. Moreover, the extent and patterning of the ingrowing axons were entirely dependent on the presence or absence of the intrinsic afferent innervation of the same type.

Writing these papers gave me an opportunity to explore the earlier literature for previous attempts on neural transplantation in the mammalian brain. Neural tissue transplantation was of course a classic approach in cold-blooded vertebrates, but the attempts to explore this technique in mammals were more scattered and far between. I found that single reports, such as by Elisabeth Dunn (in 1917), Wilfried LeGros Clark (in 1940), and Gopal Das and Joe Altman (in 1971), showed that brain tissue from fetal or neonatal donors could survive, at least partly, in the brains of neonatal recipients. But our studies were apparently the first to achieve significant survival and growth of fetal CNS tissue in the brains of adult mammals. And we had a significant advantage over all previous studies: We had access to a microscopic technique, the F-H histofluorescence method, that allowed for visualization of specific subsets of neurons in their entirety. This made it possible for us to trace the outgrowing axons and map their terminal innervation fields in the host brain in a way that had not been possible before.

At the time, the prevailing view of neuronal regeneration was that it occurred in some cold-blooded vertebrates, but that in mammals, efficient regeneration was confined to the peripheral nervous system. In studies going back to the classic experiments of Santiago Ramon y Cajal, regrowth of axons after damage in the adult mammalian brain or spinal cord was seen as abortive, at best. The regrowth of axons over long distances, as we could report in our studies of regenerating monoaminergic neurons in the adult rat CNS, was thus highly unexpected. Equally unexpected was the remarkable growth of transplanted fetal noradrenergic, dopaminergic, serotonergic, and cholinergic neurons. Their capacity to provide new, functional innervations of previously denervated regions in the adult CNS, such as hippocampus, striatum, and spinal cord, is a striking demonstration of the ability of the damaged brain to integrate new cellular elements into functional circuitry. The innervation patterns of the intrinsic noradrenergic and cholinergic innervations (removed by lesions before transplantation) were accurately reproduced by the reinnervating axons derived from the grafted locus coeruleus and septal neurons, respectively. These exciting findings, which we published in 1976–1979, opened up a fascinating field of study on the functionality of the newly formed graft-host connections and their impact of hippocampus-related behaviors, and gave us new ideas of how cellular implants may be used to help the brain to repair itself.

Family

My marriage in 1976 had not been very long in the planning. I was known to work all the time, and one of my PhD students once asked me if I ever did anything else. My answer, as I recall it, was that I didn’t need to do anything else. Research was so fun, much like a dear hobby. I really enjoyed research, both the lab work and, in particular, the reading and writing that goes along with it, like a journey in a fascinating mental landscape, the world of the brain. I met Eva on New Year’s Eve in 1974, in my hometown Växjö. This was at a party in the home of her aunt who at the same time was a close friend of my parents. She was, as I understood much later, just right for me, and I fell immediately in love.

Luckily, Eva lived also in Lund, and the next time we met was at the opera in Malmö where we saw a performance of the Strauss opera Der Rosenkavalier. It was a marvelous performance, as we both remember, one of many that would follow. This was like a seal, and since then, we have been together all the time. In May, we made a trip together to visit my brother’s family in Stockholm, and on the travel back to Lund, I asked her if she wanted to join me on a trip to Canada, the United States, and Mexico in the autumn (the reason being that I had an invitation to give a talk at a meeting in Toronto, I must admit). Eva, as I found out later, does not like flying, so the thought of this trip terrified her. But luckily she said yes, and in October, we left on a two-week tour that took us first to Toronto, where I gave my talk and where we arranged to get engaged. Then off to San Diego (where I also gave a talk), and further on to Mexico City to see the pyramids and visit the remains of the Aztec culture (including a bout of Montezuma’s revenge). When we were back in Lund, all went very fast. We found a house in the center of Lund that we could move into in February 1976, and in April, we got married in Eva’s hometown with all our relatives present. Looking back, I realize that meeting Eva was the luckiest moment of my life. She has with a gentle hand steered my life and given me the balance between work and family that has made me prosper. Indeed, the decade after our two boys were born (in 1977 and 1979) was also the most creative and rewarding time in my research.

My Golden Decade

The long decade, from the publication of our first study of dopamine neuron transplants in the rat PD model in 1979 to the first report of dopamine neuron transplantation in PD patients, published in 1990 in Science, stands out as the most creative, dynamic, and enjoyable period in my scientific life. It included the beginning of lifelong friendships with two of my most stimulating collaborators and partners in science, Steve Dunnett and Rusty Gage, and the recruitment of some of my very best PhD students who have gone on to build highly successful careers on their own. And it was amazingly productive. Over this 12-year period, we published more than 100 original reports on studies using fetal cell transplantation in a broad range of experimental models, and we had 12 papers published in Nature or Science. On average one each year!

Of course, in those days, it was easier to get published in these journals—they were, like now, focused on novelty, but Nature and Science papers at the time typically reported observations from a single set of experiments, and they were often preliminary in nature meant to be followed by more substantial studies published in specialty journals. This was also the case for several of our Nature and Science papers. Our report of the mechanism of graft-induced functional recovery in the rat PD model, for example, published in Nature in 1981 (Bjorklund et al. 1981), was accompanied by more extensive and detailed studies in Brain Research published the same year (Dunnett et al. 1981a, 1981b). Similarly, our first study of the graft-induced recovery of maze learning in rats with lesions of the septo-hippocampal pathway published in Nature in 1982 (Low et al. 1982) was followed by several more extensive studies published in Brain Research in 1982 (Dunnett et al. 1982) and Acta Physiologica Scandinavica in 1983 (Bjorklund et al. 1983a, 1983b), and our first paper of neural grafting in the rat Huntington model, published in Nature in 1984 (Isacson et al. 1984) was followed by more extensive papers in Neuroscience and PNAS in 1985 and 1986 (Isacson et al. 1985, 1986).

Until 1979, I had run two very active research programs in parallel, one related to the anatomy of the catecholamine systems in the CNS, and one pursuing my interest in neuronal regeneration and intracerebral transplantation. Our pioneering cell transplantation studies, published in 1976–1979, had opened an entirely new field of investigation with unlimited possibilities. That really fascinated me. After 1979, most of our efforts were focused on the development of the cell transplantation approach.

I was lucky to have Steve and Rusty join me in this endeavor. Steve was a newly recruited doctoral student in Susan Iversen’s lab in Cambridge, United Kingdom. I had met Sue at a meeting held at the Ciba Foundation (later Novartis Foundation) in London. She was one of the leading researchers in the study of the function of dopamine neurons in the brain, and in a break at the meeting, I asked her whether she would be interested in a collaboration to explore the functionality of intracerebral transplants. She was immediately positive and engaged Steve in this work. He came on several month-long visits to Lund, and once he had passed his PhD in 1980, he spent a year as a postdoc in my lab, studying not only the impact of nigral transplants in the rat PD model, but also the functional effects of septal cholinergic neuron transplants in models of hippocampus-related memory and learning impairments.

In 1981, our work got a further boost when Rusty joined the lab. I met Rusty at the European Neuroscience meeting in Brighton in September 1980. We had a set of posters on our ongoing cell transplantation work. Rusty came to have a look, and we got engaged in interesting discussions. He had an interesting background in studies of hippocampus-related behavior and was looking for a place to spend a sabbatical from his current job as assistant professor at Fort Worth in Texas. Initially, his plan was to stay for one year, but when that time was up, he decided to stay on for another three years in the lab. This was a fabulously stimulating and exciting time, simmering with new ideas! Rusty and Mary Lynn became dear friends, and when their daughters were born in Lund, it was as if we were all becoming a big extended family. In 1985, Rusty was recruited (by Bob Katzman!) to a faculty position at the University of California–San Diego (UCSD), and they moved back to the states. Luckily, we have managed to remain in close contact over the years.

In 1979, with Steve on board, we started to introduce new tools to monitor behavioral changes in rats with nigrostriatal or hippocampal lesions. Up until then, our work had been performed using microscopy techniques and biochemistry. Now when we had become seriously interested in studying recovery of function in our transplanted animals, we needed to be able to monitor behavioral changes in our lesioned rats. Urban Ungerstedt in Stockholm had recently introduced the rotation test to quantify loss of dopamine neurons in animals with unilateral 6-OHDA lesions of the nigrostriatal pathway, and he recently had constructed an automated “rotometer” for this purpose. Urban was kind to offer us to copy his equipment, and together with our engineer, Nils Lynhagen, I went to visit Urban’s lab to see how that could be done. Following Urban’s clever design, Nils prepared a bank of six rotometer bowls, and also automated open-field activity boxes that came to be extensively used in our lab over the following two decades. We bought our first desktop computers, two Swedish made ABC80 computers, running on BASIC and with floppy discs.

For our studies of the functional impact of grafted septal cholinergic neurons in rats with fimbria-fornix lesions, Steve had devised an elevated T-maze that we had built in our workshop. And a year later, in 1981, we were one of the first labs to adopt the Morris Watermaze test that had just been published. I had heard about it at the Society for Neuroscience meeting that was held in Los Angeles that year and thought that it would be a great tool for our studies of hippocampus-related behavior. We found a factory outside Lund that manufactured large plastic sewage tubes. Their largest diameter was 1.2 meters. I asked if they could sell us an 80-centimeter piece and attach it to a flat bottom. They were of course used to selling much longer ones—80 meter would have been more their style. But they kindly made it for us, and our caretaker brought it home tied to the roof of our department car. We found space for it in a temporary hut (“the blue barrack,” bought from a local building company) that Bengt had put up next to our pink barrack. There we could establish our new behavior test lab and attach a sign on the door saying “World Brain Transplant Center.”

With these new tools in hand, we could launch our studies on dopamine neuron transplants in the rat PD model (which I will deal with in more detail later) and studies on graft-induced recovery of maze learning in rats with lesions of the septo-hippocampal pathway, as well as in aged rats, which we pursued in parallel. Until then, Ulf and I had performed much of the experimental work ourselves, with the help of three highly skilled and experienced technicians, Gertrude Stridsberg, Birgit Haraldsson, and Ulla Jarl. Now as our transplantation work was getting up in speed, we started to look around for talented PhD students. In the autumn of 1980, we organized an evening “research-contact” course for interested medical students. Among the participants were two first-year students, Ole Isacson and Patrik Brundin. After the course, they contacted me to ask if they could follow the research in my lab. Yes, they were welcome to spend time in the lab, in parallel with their medical studies, and in the two following summers, they got going on experiments involving lesion and transplantation surgery in combination with behavioral tests.

In 1983, Ole and Patrik decided to take a break from their medical training and became enrolled as PhD students. In the beginning, they had worked together, which made it easier to mix the work with the scheduled activities in the medical classes, but now we had to define separate thesis projects. That was not easy, both of them were keen to work on the Parkinson project. There might be an opening, however: We had at that time switched from the solid-transplant/cavity method to transplantation using dissociated cell suspensions, and in a first round of experiments, we had tried this approach in rats with excitotoxin lesions of the striatum. This lesion had been introduced by Joe Coyle and Robert Schwarcz as a model of the striatal pathology seen in Huntington’s disease, and our initial experiments, which were published in Brian Research in 1981 (Schmidt et al. 1981) had shown that the fetal striatal primordium, transplanted as a cell suspension, survived well in the excititoxically lesioned striatum and appeared to mature into a striatum-like structure. Thus, grafting in this alternative disease model could be an interesting topic! We agreed that these two projects were both interesting, and to solve who should do what, we drew lots: Patrik got the Parkinson project and Ole the Huntington one. A happy solution, and I think it worked out very well. Ole got his first Nature paper already in 1984, a follow-up PNAS paper in 1986, and defended his PhD thesis in 1987. Truly groundbreaking work that catapulted Ole to a highly successful career at Harvard in Boston. Patrik came to play a central role in the development of dopamine cell transplantation in patients with PD, as I will tell more about later. At the time when he defended his thesis, Towards a Transplantation Therapy for Parkinson’s Disease, in May 1988, the first two patients had already been operated. The thesis defense was a memorable event. David Marsden, the leading movement disorders authority at the time, had been appointed as the faculty opponent. Patrik was off to a good start!

Cell Therapy for PD: How It Happened

Our first attempts to transplant fetal VM dopamine neurons to the striatum were performed in 1975. The approach we used was to prepare a suction cavity in the parietal cortex, through the corpus callosum, to expose the dorsal surface of the caudate-putamen. In this location, the cavity is lacking the vascular surface present on the surface of the tectum present at the bottom of the retro-splenial cavity, thus failing to provide the necessary vascular support. We reported these observations in our 1976 Brain Research paper and then left it aside in favor of the studies on transplants innervating the hippocampus that worked so well. Three year later, we took it up again. After some further experimentation, we found that we could make the fetal VM grafts survive by performing the surgery in two steps: In a first step, the cavity was prepared, filled with gel-foam, and closed. Three to four weeks later, the cavity was re-exposed and the fetal VM piece was placed over the vascular bed that had developed in response to the lesion. Now the grafts survived well and grew in size, and we saw that the dopamine neurons were capable of providing the underlying striatum with a new dense innervation that covered most of the dorsal caudate-putamen in the host.

We published these initial findings in 1979 (Bjorklund and Stenevi 1979). We submitted this paper first to Science, but while it was under review, a similar study, to our surprise, appeared in Science. As a result, being too similar, the editors kindly declined our paper, and we rushed to have it published in Brain Research instead. This competing study was based on the same idea, but their approach was different. In the Science paper, fetal VM tissue was implanted into the lateral ventricle, in contact with the surface of the denervated caudate-putamen. These transplants were quite small, and in contrast to the effective reinnervation seen in our transplanted animals, the growth of axons from the intraventricular transplants into the striatum was quite limited. We found that the functional impact of our intracavity grafts, monitored by tests of amphetamine-induced turning, was directly correlated to the extent of striatal reinnervation, and in the most successful cases, the motor asymmetry seen in the unilaterally lesioned rats was completely reversed. This led us to propose that the grafts of fetal dopamine neurons could be used to establish a new functional “nigro-striatal” connection able to compensate for the loss of dopamine innervation in the toxin-lesioned animals. The functional response induced by the intraventricular transplants, lacking the critical fiber outgrowth, was most probably due to dopamine diffusing from the grafted cells into the adjacent denervated striatum.

As a follow-up to the 1979 paper, and with Steve Dunnett on board, we sped up and published over the next two years six papers in rapid succession. Collectively, these studies provided an extended analysis of the survival, growth, and effects of fetal nigral transplants on both drug-induced and spontaneous motor behaviors, as seen in rats with either unilateral or bilateral 6-OHDA lesions of the nigro-striatal dopamine pathway. In our 1981 paper in Nature (Bjorklund et al. 1981), we proposed a model of dopamine graft function based on the idea that dopamine acts as a tonic regulatory system that sets the threshold for activation of the movement-initiating cortico-striato-thalamic circuitry. This suggested that the reinstatement of dopaminergic neurotransmission obtained by dopamine neuron transplants is able to reduce the threshold for the initiation of movements in response to movement-activating sensory stimuli. According to this model, tonic release of the transmitter at the reinnervated synaptic sites would be sufficient to induce recovery of sensori-motor behavior. In our subsequent studies of graft-induced dopamine release, which we studied using amperometry and intracerebral microdialysis, we could add further support for this idea. This mode of action helped to explain why dopamine neuron transplants placed in an ectopic location (i.e., in the striatum rather than in their normal location in the VM) are capable of restoring at least some aspects of normal dopamine-dependent behaviors. I believe it is still valid.

The cavity surgery used in these studies had an obvious weakness in that it involved major damage to the overlying cortex. And there was another snag: The functional effect seen in these animals was limited to recovery in motor asymmetry, and the severe and characteristic impairment in spontaneous sensori-motor behavior induced by the 6-OHDA lesion was not affected. Steve suggested that this shortcoming could be due to the fact that the new innervation extending from the intracortical grafts was limited to the dorsal part of the head of the caudate-putamen. In his ongoing thesis work, Steve had shown that the striatum is functionally heterogeneous and that it is the ventral-lateral sector, that is, the part corresponding to the putamen in humans, that is specifically involved in the regulation of sensori-motor behavior. Thus, more complete functional recovery may require more widespread reinnervation of the striatal complex.

We had already started to work on a different transplantation technique based on the injection of dissociated cell suspensions, which would allow grafting to deep brain sites, as well as multiple graft placements, and thus offer the possibility of obtaining more widespread and complete dopamine reinnervation of the striatum. Thus, in 1981, we abandoned the cavity approach in favor of a less invasive technique based on stereotaxic injections of dissociated cell suspensions directly into the brain parenchyma. The initial results we obtained with this approach were very promising, and in collaboration with Steve and Rusty, we set out to further optimize this technique and evaluate its potential, resulting in a series of experiments that was published (in six parts) as a supplement to Acta Physiologica Scandinavica in 1983 (Bjorklund et al. 1983c). The results showed that the cell suspension approach made it possible to distribute the graft tissue over multiple sites (up to five in these experiments) and achieve more extensive reinnervation of the striatum, combined with near-complete recovery of both drug-induced and spontaneous sensori-motor behavior, as seen in rats with either unilateral or bilateral 6-OHDA lesions.

It was around this time that Olle and I initiated a process that would give us permission to use VM tissue from aborted human fetuses for transplantation. This allowed us to perform the necessary preclinical studies with human fetal tissue in our animal model, and it was Patrik who took this on. This preclinical work was summarized in three papers, published in 1986–1988, showing that human fetal VM tissue from seven- to nine-week-old fetuses could survive well after transplantation to the striatum (provided that the animals were immunosuppressed by daily injections of cyclosporine), reinnervate the previously denervated striatum, reverse amphetamine-induced rotation, restore dopamine release, and form normal synaptic contacts with the host striatal projection neurons. In these experiments, Patrik was also able to identify the appropriate landmarks to be used for dissection of the dopamine-rich VM tissue pieces and define the optimal range of donor ages to be used in a future clinical protocol.

It was in 1985 that we started to discuss in earnest the possibility of initiating a clinical trial using VM tissue from aborted fetuses. But would it be possible to get the permission to use fetal tissue for this purpose? Even in Sweden with its liberal abortion law, this was a difficult and contentious issue. Professor David Ingvar, the head of clinical neurophysiology at our university, was at the time chairman of the Swedish Society of Medicine, and he advised us to engage the Society in a discussion of this issue. He put us in contact with the chairperson of its Ethics Delegation, and she agreed to take it on. After a series of hearings and discussions at the Society in Stockholm, guidelines for the use of human fetal tissue for transplantation purposes were adopted by the Society in March 1986 (later incorporated by the parliament into Swedish law). This was a critical step that made it possible for us to seek approval from our local ethical committees. But was the time ripe?

In April that year, Olle and I attended a meeting in New York, organized by the New York Academy of Sciences (NYAS). Olle reported on the results obtained in two patients who had received transplants of adrenal medullary tissue in the putamen (performed in 1985 in collaboration with the Karolinska team), and Patrik discussed the first results we had obtained with transplants of human fetal VM tissue in immunosuppressed rats. The discussions following these presentations were lively and raised a number of important issues. The ethical question, of course, was raised in the discussion after Patrik’s talk, and he responded cautiously calling for public discussions on the use of human fetal tissue for transplantation to the brain. And then there was the question of the body of preclinical data needed to justify going into the clinic, and the push for studies in monkeys in particular. The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) primate model had recently been introduced, and at the NYAS meeting, two teams, led by Roy Bakay and Eugene Redmond, had reported promising preliminary data in MPTP-treated monkeys that had received transplants of fetal VM tissue into the caudate nucleus. Clearly, this model could offer an opportunity to validate the fetal grafting approach in a primate model. Nevertheless, Olle and I realized that it would take years to generate any really informative primate data, and we felt that in the end they would not tell us more than what we could learn from the rodent experiments. So when we returned home, we had decided to go ahead, in spite of the resistance from the scientific and clinical community.

Two months later, in June 1986, we were on our way to London to meet with David Marsden and Richard Frackowiak. Frackowiak’s Medical Research Council (MRC) Cyclotron Unit at the Hammersmith Hospital has just adopted ¹⁸F-DOPA as a tracer to monitor changes in dopamine metabolism using positron emission tomography (PET). This technique had been introduced a couple of years earlier by E. S. Garnett and collaborators, working at McMaster University in Canada, and the Hammersmith group had just published their first ¹⁸F-DOPA study, not in PD, but in a patient with Huntington’s disease. Garnett et al., in their 1984 paper, had shown that the accumulation of ¹⁸F-DOPA was reduced in the striatum, and in the putamen in particular, in PD patients, and we realized that this technique could provide a tool to monitor survival of the transplanted dopamine neurons. But would this technique have sufficient resolution and sensitivity to detect a surviving graft? David and Richard were positive to give it a try, and after an intense year of preparations, including a series of “dry-run” rehearsals that we carried out in the summer and autumn of 1987, all was in place: the ethical permits, the well-rehearsed fetal dissection and handling procedure, the surgical approach, the assessment protocol, and the PET scanning protocol.

In September 1987, Olle traveled with the first two patients to Hammersmith for their preoperative ¹⁸F-DOPA scans. This was the start of a long-lasting and very fruitful collaboration, initially driven by David, Richard, and Klaus Leenders, and later taken over by their successors Niall Quinn, David Brooks, and Paola Piccini. ¹⁸F-DOPA PET became a central and important element of our program. This technique gave us the possibility to follow the development and survival of the grafted dopamine neurons over time, and with the increasing resolution of subsequent generations of PET scanners, it also allowed us to assess the extent of reinnervation provided by the grafts in individual patients. Later on, the Raclopride displacement method made it possible for us, for the first time, to monitor dopamine release from the grafted neurons. We often met the sour argument that it was the patient we should cure, not the PET scan. But these critics of course missed the point: Unless we could develop a procedure that allowed the grafted dopamine neurons to survive long term and restore dopamine neurotransmission back to normal, it would not be ready for more serious clinical testing. And there was also the issue of immune reactions and graft rejection. We knew from the animal experiments that allogeneic transplants (i.e., transplants between unrelated individuals) survive well in the brain provided that the recipient is immunosuppressed. But we did not know what kind of immunosuppressive treatment would be necessary in the PD patients or how long it had to be maintained. The transplantation experts at the hospital advised us to use the same triple combination, cyclosporine, azathioprine, and prednisolone, they used for kidney transplants at the time. The access to ¹⁸F-DOPA PET gave us the ideal tool to pick up signs of graft rejection, and with time, the PET scans have told us that temporary immunosuppression is sufficient to provide long-term graft survival over more than two decades.

The two first patients, operated in November and December 1987, were a disappointment. Both the clinical assessments and the ¹⁸F-DOPA PET scans showed minimal improvement and no signs of graft survival. Olle presented the negative data at the International Parkinson Symposium in Jerusalem in 1988. We were disappointed, of course, but the reactions at the meeting were surprisingly positive and supportive. Olle was complimented for how carefully the study had been performed, and the amount of preclinical work that had gone into the design of the study was appreciated by many of our colleagues. So we returned home encouraged to proceed. First, however, we needed to make improvements in the transplantation procedure. We suspected that the transplantation instrument was too thick, with an outer diameter of 2.5 mm compared with the 0.45 mm thick syringe needle that we had used in the animal experiments. Together, with our neurosurgeon Stig Rehncrona, Patrik made a series of tests and showed that the excess damage and bleeding caused by the thicker cannula seriously compromised the survival of the cells. Indeed, when this first patient died in 2009, the autopsy confirmed that the graft had survived poorly (Kurowska et al. 2011). Clearly, we needed to use a thinner implantation device. Stig had one made by the hospital workshop, cleverly designed with an outer 1.0 mm cannula and an inner plunger that could be used both to load the tissue and to extrude it in defined steps.

With this new instrument in hand the two next patients, called Patient 3 and 4, were operated on in April and May 1989. They were transplanted unilaterally, on the side opposite to the most affected limbs, using VM tissue from four fetal donors. This time the number of implantation sites was increased from two to three to reach a larger volume of the putamen. Over the subsequent months, Olle had the patients come regularly for neurological assessment. In Patient 3, it was clear that something started to happen around three months: The speed of movements was increased, the rigidity in the limbs was gradually reduced, and the effect of his L-DOPA dose lasted longer. At five months, we decided that it was time for an ¹⁸F-DOPA scan to check whether the improvement could be correlated with signs of a surviving graft. This was really exciting, and this time, I decided to join Olle in London to be there when it happened. Indeed, the scans showed a clear increase in ¹⁸F-DOPA uptake in the grafted putamen but not on the contralateral side. Subsequent scans, performed in both Patient 3 and 4, would show that the uptake in the grafted putamen continued to increase and reach normal levels after two or three years, in contrast to the uptake on the nongrafted side, which would continue to decrease over time.

To both Olle and me, this was one of the most exciting moments in our scientific careers. We rushed to publish, and when our paper appeared in Science in February 1990 (Lindvall et al. 1990), it caused an international media interest that none of us had anticipated. There were reports on our study, not only in Swedish media but also on CNN and BBC, and there were articles in the New York Times and Washington Post, and an editorial in The Lancet with the headline “A Brain Transplant That Works.” We had reached an important milestone in our program.

Patient 4

Over the following decade, a total of 18 PD patients were transplanted in the Lund program. Olle has estimated that about one-third of them showed significant long-lasting and clinically meaningful improvements, accompanied by recovery of ¹⁸F-DOPA uptake in the grafted putamen, and in some of the patients, the improvement was remarkable. One of them, Patient 4, stands out as quite special. He was transplanted one month after Patient 3 and remained with transplant on only one side. All other patients with unilateral transplants went on to receive a second transplant on the other side. This made him particularly interesting, since his nongrafted side could serve as an “internal control.” He did very well after surgery and was able to withdraw his L-DOPA treatment completely after three years, and still at 10 years after transplantation, he had only mild Parkinsonian symptoms. At six years, Olle reintroduced a low dose of L-DOPA (one-third of the preoperative dose) owing to progression of symptoms on the side ipsilateral to the graft.

In 1998, the Hammersmith team published an interesting article in Nature in which they had introduced a new method to measure striatal dopamine release by PET. Paola Piccini suggested to Olle that this technique could be tried on the transplanted patients. Patient 4 was particularly interesting, because the measurements on the grafted side could be directly compared with those on the denervated, nongrafted side. The technique worked beautifully: The graft had indeed restored both spontaneous and drug-induced dopamine release (induced by a low dose of amphetamine) to normal levels in the grafted putamen. The release on the nonoperated side, by contrast, was reduced to only 10 percent of normal. The article reporting these findings, published in Nature Neuroscience in 1999 (Piccini et al. 1999), is undoubtedly one of the landmark papers in this field.

Patient 4 died in 2013, 24 years after transplantation. At that point, he had deteriorated and developed severe dementia. His brain was severely atrophied, with enlarged ventricles, shrunken cortex, and Lewy body pathology distributed over all forebrain regions. Nevertheless, his transplant looked really great. In line with his 10-year PET scan, we found a dense, near-normal dopamine innervation in the grafted putamen, whereas the nongrafted putamen was completely devoid of dopamine fibers. To us, this was compelling proof that a rich functional dopamine innervation, which had developed over the first three years after transplantation and induced major and sustained symptomatic improvement, could be maintained for a quarter of a century in the PD brain. At the same time, the history of Patient 4 told us that the benefits of a viable transplant may be lost if widespread synucleinopathy and degenerative changes develop in the host brain. In the paper we published on these findings in PNAS (Li et al. 2016), I am particularly proud of the documentation of the microscopic material that Bengt Mattsson and I prepared from the TH-stained autopsy sections. Really beautiful, I think!

The Frozen Addicts

The discovery of MPTP is one of the most remarkable stories in the history of Parkinson’s research. How this unraveled is like a detective story and has been very well told in the book The Case of the Frozen Addicts published in 1995 by Bill Langston and John Palfreman (new edition released in 2014). As told in this book, I first met Bill at a meeting in Belgium in October 1986, and under very memorable circumstances. We were on a bus taking us to a state dinner at Princess Liliane’s Summer Palace outside Brussels. The rain was pouring down and, after some aimless driving in the misty darkness, it became clear to us that the driver had gotten lost. We had ended up in a narrow road that seemed to lead to nowhere, and when he tried to turn the bus around, it reversed into a field and got stuck in the mud. After some desperate attempts to get the bus loose, the driver decided to seek help. He locked the bus and walked away, and there we were, 18 scientists, all dressed up in tuxedos, left in the dark and listening to the rain pounding on the roof. I moved up to the front where there was some light and sat down beside Bill and we started to talk. I knew of course about Bill’s famous MPTP patients, but this was the first time Bill heard about our cell transplantation program and our plans to try this in PD patients. He was intrigued and (as told in the book) found our plans fascinating. Indeed, it became immediately clear to us that the MPTP patients would be ideal candidates for this surgery: Their damage was likely to be confined to the dopamine system, their impairments were profound, but—unlike the human disease—stable and nonprogressive with little fluctuations, and the causative agent was no longer present. A very interesting idea!

So what happened to us in the bus? After about 40 minutes, a caravan of four private cars, with the desperate cook in the lead, came to pick us up. We arrived an hour and a half late to a crowd of hungry people that had been kept going on sparkling wine.

Back in Lund, Olle liked the idea and agreed that the MPTP patients offered a very interesting opportunity. But it would require quite a bit of preparation to get everything in place. To work out the plans Olle and I went to visit Bill in California in July 1987. Bill took us on a tour of the sites where the MPTP drama had taken place, and he also arranged for us to meet his most severely affected patient, Connie Sainz, who was one of the candidates to be included. With Bill as a captivating guide, it became a highly memorable and absolutely fascinating experience. Then, in the beginning of December, Bill came to Lund to settle the plans: Håkan Widner, the younger of the two neurologists in the Lund team, would take the lead in this project, perform the presurgical assessments, select the two most suitable candidates to be included, and travel with the them to Lund for surgery.

Over the following year and a half, Håkan traveled frequently to Sunnyvale and also to Wisconsin, where one of the patients lived, to see the patients and perform the preclinical testing of those two, George and Juanita, who eventually were selected to take part in the trial. To cover the costs of Håkan’s travels and hotel expenses, I had managed to get a donation from a small local family foundation run by the parents of a classmate of one of my children; they were surprised and perplexed when I contacted them, but I guess too embarrassed to say no! And Bill took an inventive step to cover the costs for the patients’ travels to Sweden: The television program Nova wanted to make a follow-up of their previous documentary on the Frozen Addicts and John Palfreman had persuaded them to pay these costs provided that they were allowed to accompany the patients on their journey.

George was transplanted in August–September and Juanita in November 1989. They received transplants of VM tissue from four fetal donors, implanted on both sides with a two-week delay. The timing was good. We had just submitted our paper on Patient 3 to Science, giving us some confidence that we now had a grafting procedure that allowed the transplanted dopamine neurons to survive and function. The trial in the two MPTP patients, if positive, could provide further proof-of-principle for the technique we had developed.

The outcome was reassuring, but we had to wait for the positive results. During the first few months, very little happened. The first signs of improvement were observed at five to six months, and during the next two years, both of them showed a progressive improvement in motor function, accompanied by a marked increase in striatal ¹⁸F-DOPA uptake that closely paralleled the clinical improvement in both patients. They could reduce their daily L-DOPA intake by 70 percent and the troublesome dyskinesias they had experienced before surgery were much reduced. They became much more independent, and the filmed sequences that appeared later in the Nova program were striking. No question that the grafts had had a major impact on their Parkinsonian symptoms.

We published the results in November 1992 in New England Journal of Medicine (Widner et al. 1992). To our surprise, we found our paper back-to-back with two papers from two U.S. teams, reporting promising results obtained in idiopathic PD patients. Together these three studies caused a real upstir. In the United States, the use of tissue from aborted human fetuses was highly controversial and a ban on federal funding for fetal tissue research had been introduced by the Reagan administration already in 1988. The overall promising results reported in the three NEJM papers generated considerable interest and debate, and the resulting media attention may have played a role in the decision of the new president, Bill Clinton, to lift this ban in January 1993 (indeed, the first made in his presidency). This opened the way for the National Institutes of Health (NIH) to fund two sham surgery-controlled studies, the Colorado/Columbia trial and the Tampa/Mount Sinai/Rush trial, that were initiated in mid 1990s and reported in 2001 and 2003, respectively.

The negative outcome of these two trials was a major setback for the whole field and convinced many of our colleagues, particularly in the United States, that the cell transplantation approach had reached a dead-end. The wide media attention and the fact that these placebo-controlled trials were initiated and sponsored by the NIH helped to convey the impression that the outcome provided an authoritative and definitive answer: Cell transplantation in PD does not work. In retrospect, however, it is clear that these trials were performed prematurely. Cell transplantation was at the time in a very early stage of development and many technical issues and problems, such as cell preparation, handling and storage, method and site(s) of implantation, patient selection, and type and extent of immunosuppressive treatment, had not been studied properly and certainly not properly sorted out. Thus, the protocols used in the two trials were based on limited or insufficient experience from preclinical studies. Notably, these trials used limited immunosuppressive treatment (none in the Colorado/Columbia study) and the postoperative observation period was quite short, limited to one or two years. We learned later on that the clinical benefits induced by the transplants develop slowly over time, reaching full impact only after three to five years and that efficient immunosuppression is needed to obtain optimal graft survival. Clinical trials compromising on immunosuppressive treatment and using short end-points will thus run the risk of missing the full impact of the transplanted cells. Despite these shortcomings, the negative message spread by the NIH trials brought the whole field to a standstill. No further transplantations were made in Lund until last year when the European Union–sponsored TransEuro program was launched. The outcome of these new efforts will be known only in a few years’ time.

Pathology Spread

In the early days, we were frequently asked whether the grafted neurons could be affected or damaged by the ongoing disease process. Little was known at that time about the pathophysiology of PD, so our response was, yes, this is definitely a possibility, but we do not know if this can happen. PD was known to be a progressive disease, but the mechanism underlying disease progression was not known. The impact of disease progression could go two ways: It might mask the effect of the graft, or it might attack the graft itself. Much later we would learn that both can occur, but that it takes a very long time.

The critical observation was made in 2007 when the brains from two of our transplanted patients had come to autopsy, 11 and 16 years after transplantation (Li et al. 2008). In these two brains Patrik and his senior collaborator Jia-yi Li observed that a small fraction of the TH-positive neurons in the grafts contained α-synuclein-positive aggregates, and some of them with the characteristic appearance of Lewy bodies, the pathological hallmark of PD. Similar changes were reported by Jeff Kordower in brains from the Tampa/Mount Sinai/Rush trial, and they seemed to be a consistent finding in all grafts that had survived longer than 10 years. The α-synuclein aggregates developed very slowly: About 2 percent of the TH neurons were affected at 11 years, 5 percent at 16 years and 11–12 percent at 24 years, suggesting that an additional 1 percent of the grafted neurons were recruited each year.

These findings generated enormous interest and opened up a completely new research field on the pathogenesis of PD. Our findings were viewed as the first compelling evidence for a prion-like mechanism underlying the spread of α-synuclein pathology that could explain its progression from the periphery to the brain and within the brain itself. This obviously represented a threat to the long-term viability of the graft, but it happened very slowly and involved only a small fraction of the cells. We knew that the fetal VM grafts could provide long-lasting and sustained benefit to the grafted patients and that the vast majority of the grafted dopamine neurons remained healthy and functional over more than a decade. To us, dopamine cell transplantation remained a viable therapeutic option.

Neurotrophic Factors: Nerve Growth Factor and Glial Cell Line-Derived Neurotrophic Factor

My collaboration with Rusty Gage also continued after his move to San Diego in 1985, but it was now focused on exploring the neuroprotective effects of nerve growth factor (NGF) in the septo-hippocampal system. In parallel with our studies on cholinergic neuron transplants in rats with lesions of the septo-hippocampal pathway, and in cognitively impaired aged rats, Rusty and I had developed an interest in the basal forebrain cholinergic system, its reactions to injury, and its changes during aging. Work from Martin Schwab, Hans Thoenen, and Franz Hefti had provided interesting data showing that NGF was produced in the hippocampus and transported retrogradely in the septal cholinergic neurons and that exogenous NGF had a stimulation effect on ChAT activity in these neurons. This suggested that NGF may act as a neurotrophic factor, not only in the peripheral nervous system but also in the brain. Stimulated by these findings, we initiated a collaboration with Rusty’s new colleague in San Diego, Silvio Varon, and his student Larry Williams, who had devised a method for continuous intraventricular infusion of NGF using osmotic minipumps. We applied this infusion technique in rats with unilateral lesions of the fimbria-fornix pathway, and the results were striking. The resulting paper, which we published in PNAS in 1986 (Williams et al. 1986), has become one of my most quoted publications. We went on to show that NGF-infused intraventricularly over four weeks could partially reverse the cholinergic neuron atrophy and improve retention of spatial memory seen in behaviorally impaired aged (two-year-old) rats (Fischer et al. 1987) and that similar infusions induced cholinergic neuron hypertrophy in rats before the onset of neuronal atrophy (Fischer et al. 1991).

Rusty went on to develop this approach further, and together with his colleagues at UCSD, Leon Thal and Mark Tuszynski, he confirmed this neuroprotective effect on lesioned septal cholinergic neurons in nonhuman primates and developed an entirely new approach to NGF delivery using transplants of fibroblasts engineered to secrete NGF. I was intrigued by this idea to combine cell transplantation and ex vivo gene transfer, and when Alberto Martinez-Serrano came to work as a postdoc in my lab, we decided to apply this technique to a conditionally immortalized neural progenitor cell line, HiB5, which we had obtained from Ron McKay in Boston. Alberto succeeded in generating a NGF-secreting HiB5 cell line that produced the factor at functionally active levels after transplantation to the brain, sufficient to afford complete rescue of axotomized cholinergic neurons after transplantation to the septum (Martinez-Serrano et al. 1995b) and equally effective at reversing age-dependent cognitive impairments and neuronal atrophy after transplantation to the basal forebrain in aged rats (Martinez-Serrano et al. 1995a).

It was at this time that Lin et al. reported the isolation and cloning of glial cell line-derived neurotrophic factor (GDNF). GDNF had been isolated as a potent neurotrophic factor for cultured dopamine neurons, and as soon as the paper was published in Science in May 1993, I started to explore the possibility of obtaining a sample to test in our new, progressive intrastriatal 6-OHDA lesion model. After several futile attempts, it was clear that Synergen (i.e., the company holding the ownership of GDNF) did not want to share the factor with us. So, instead, I turned to Arnon Rosenthal at Genentech who was positive about helping us. In the meantime, the Synergen and Genentec teams had published two back-to-back papers in Nature providing evidence for a potent neurotrophic effect on lesioned dopamine neurons in mice and rats. In our study, which we published in PNAS in September 1995 (Sauer et al. 1995), we could show that injection of GDNF over the substantia nigra could provide complete dopaminergic (DA) neuron protection in the intrastriatal 6-OHDA model. The results were intriguing: GDNF was the first neuroprotective factor able to provide complete protection against neurotoxic damage in rodents as well as primates. We went on to characterize this effect in detail in rats, first using injections of recombinant protein over the nigra or into the striatum, and later using Lenti and adeno-associated virus (AAV) vectors to provide a source for constant delivery of GDNF. Over the following decade we published more than 20 papers (and material for four PhD theses) and established ourselves as one of the leading labs in the GDNF field.

It was this work that caught the attention of Teit Johansen, then working at the NeuroSearch company in Copenhagen. At a meeting in Copenhagen, where I had given a talk on our neurotrophic factor work, he contacted me and asked whether I would be interested in taking part in an initiative to establish a new gene therapy company devoted to the development of novel neuroprotective therapies. I agreed. This new company, NsGene, was launched in December 1999. This was the beginning of an enjoyable, and also quite exciting, endeavor that continued for more than a decade. We were lucky to have Lars Wahlberg join us as the third founding member. He was at the time working as research director of the CytoTherapeutics (CTI) company in Rhode Island, and when CTI closed down, Lars suggested that we should acquire the cell encapsulation technique from them. Over the next several years NsGene developed GDNF- and NGF-secreting cell lines to be used for encapsulation. These capsule devices were validated in both rats and minipigs, and manufactured to GMP standards. Because the company, despite serious efforts, failed to get a license for the use of GDNF, it was decided to develop the NGF-secreting capsules for a clinical trial in patients with Alzheimer’s disease to be conducted in Stockholm (published in Eriksdotter-Jonhagen et al. 2012). Unfortunately, and despite the encouraging results obtained in this trial, the company failed to generate the financial support needed to continue these trials. But the company survived and under Lars’ leadership, NsGene Inc. has now entered an agreement with Takeda to develop the encapsulation technology for PD.

The neurotrophic factor field has experienced its ups and downs, not unlike cell transplantation, and the efforts to use these factors clinically in patients with PD and Alzheimer’s disease have encountered numerous setbacks. But we have not yet seen the end of this endeavor: GDNF in particular is endowed with such intriguing properties, not only because of its role as a survival factor but also because of its ability to promote neuronal regeneration and boost function in lesion DA neurons. More recently, my research in this field has been focused on the interaction between Nurr1 and GDNF in the regulation of GDNF signaling, pointing to an interesting cellular machinery that appears to be dysregulated in nigral DA neurons affected by synuclein toxicity (Decressac et al. 2012).

The Wallenberg Center

In 1989–1990, I spent a 10-month sabbatical in Oxford. At that time, I felt it was time to take a break. I had had 20 years of intense research in Lund and felt that I needed to get away and contemplate on how to steer my research in the future. My two boys were now at the age, 10 and 12, when we thought they would benefit from the experience of living in another country and also training their English. I had an invitation from David Smith, the chairman of Pharmacology, to spend time in his MRC unit, and he offered to arrange a visiting professorship for me. This professorship was linked to Lincoln College and included housing in a superbly located villa next to the university park. A very nice offer and, luckily, Eva agreed to take leave of absence from her work at the museum in Malmö. It was a great experience for us all, and a very refreshing break for me. I had stimulating collaborations with Paul Bolam and Debbie Clarke that took some of my time, and my doctoral students came on visits for data analysis and writing of papers. Anyway, I had much time for reading and thinking, and all kinds of activities with my family.

Time was running fast, but all did not develop as I had expected. Soon after I had arrived, I was contacted by my close friends in Cambridge, asking if I was willing to join in a new initiative aimed to establish, and build, a new center for brain repair in Cambridge. They were in the process of submitting an application to the MRC and wanted to list me as the prospective director of this new center. It looked like a great plan and I agreed. Over the next few months, I drove to Cambridge for planning meetings, and I was summoned for a discussion with the MRC director, Dai Rees, about the realism of the plans. After several revisions, it was finally approved, but the awarded sum was only half of what had been requested, and most of it would be needed to cover the cost for the building. It became clear to me that the running costs would have to be generated from other sources. These prospects dampened my enthusiasm. In the meantime, however, I had become fond of the idea behind the project, a translational center on brain damage and repair spanning from molecules to man.

When I returned home to Lund by the end of May 1990 I contacted Per Belfrage, who at the time was vice-dean of the faculty (later dean) and asked whether there would be any possibility of establishing anything similar in Lund. The timing was good. Per had just started to dream up plans for a new research building—later to be named the Biomedical Center, or BMC—that would be a joint initiative between the university and the hospital and that would allow the different departments of the medical faculty to be housed together. He convinced me that my idea could be realized as part of this plan, but if it was going to fly, it had to be a combined basic science–clinical initiative with a disease focus. I discussed this with Olle, and we agreed that it would be great to plan this as a joint venture. Per was very keen to get it off the ground. If we could secure financing of the Neuroscience Center, this could serve as a trigger for his greater BMC plan. The way to get it started was to attract a major donation from the Wallenberg Foundation, the largest research-funding agency in Sweden. But there was a snag: An application of this kind had to be submitted by the university, not by any constellation of scientists. Luckily, the vice-chancellor, Håkan Westling, was a close ally of Per and willing to help. Following informal contacts with the foundation, we were encouraged to prepare a proposal that could be incorporated into the formal application submitted by the vice-chancellor. We were lucky that the foundation awarded us a grant that would be sufficient to cover the cost for two floors in the new building, sufficient to house Olle’s and my labs, with the rest to be covered by the university and the hospital. In the meantime, Per had secured support for the greater BMC plan from both the university and the hospital, and with the Wallenberg donation in hand, he could now take the next step, to initiate an architect competition. In the beginning of 1993, the plan was approved and the architects were chosen. Over the next year, we could work closely with Akademiska Hus and the architects in the detailed design of the labs in the Neuroscience Center. Once it got started, it all went very fast, and we could finally move into the new building in May 1996.

Entering a New Phase

The move to the new center was a major event, and an important milestone in my research. In the old histology building, we were cramped for space and the possibilities of modernizing and expanding the labs were limited. The new top-class facilities and the increased lab space in the center allowed me to expand my team and venture into new lines of research. As a result, my research became more diversified with several research programs developing in parallel and relying more on my senior postdocs, experienced technicians, and young colleagues in the day-to-day management of the work.

I also started to take my role as mentor more seriously. In the steadily increasing competition for positions and resources in academia, it has become increasingly difficult for young talented researchers to develop successful independent research careers. Here, senior established scientists with secure faculty positions can play an important role, not only as mentors but also in providing a genuinely supportive and well-equipped research environment that can help our best young investigators get started and establish independent research programs, and to be able to compete successfully for major grants and well-financed group leader positions. It has been one of the most rewarding experiences in my research life to see many of my best PhD students and postdocs go on to develop highly successful research careers, both in Lund and in other universities around the world. As a scientist, I am blessed with a large “extended family.”

The 1990s was a very busy time for me in many other ways. I had been elected to the Swedish Academy of Sciences in 1989 and came to serve as the chairman for the medical section for five years, 1995–2000. I had also become very much involved with the European Neuroscience Association (ENA), first as a council member and later as president. I was elected to the ENA Council in 1985, and over the subsequent 11 years, I took part in two major initiatives, the launch of the European Journal of Neuroscience and the creation of the Federation of European Neuroscience Societies (FENS). Inspired by the example of SfN’s Journal of Neuroscience, ENA decided in the late 1980s to start its own journal to generate income for the association. They appointed four of us, Per Andersen, Michel Cuenod, Wolf Singer, and myself (“the gang of four”) to get it done. We managed to find a publisher (Oxford University Press) and were very lucky to persuade Ray Guillery to take on the job as the journal’s first chief editor. It became a success. The revenues were relatively modest during the first few years, but with time, it has become economically profitable and has given the society a solid economic basis to grow and become the leading force in European neuroscience.

It was during my time as president elect and president, 1994–1998, that ENA was transformed into the Federation of European Neuroscience Societies. In the beginning of the 1990s, the attendance of the annual ENA meetings had declined, to less than 2,000, an order of magnitude below the American SfN meetings, and there was a worry that more and more of the European scientists had chosen to go to the ever-growing SfN meetings instead. The problems facing the ENA meetings were distinctly European: the competition from large national neuroscience meetings held during the same years, and the presence of around 20 specialized European associations attracting participants from a range of subdiciplines. It was decided to replace ENA with a federation of national societies that would hold a joint European meeting every two years, linked to a deal with the national societies promising to hold their meetings in the intervening years. At first, there was resistance from the well-established national societies, and there was in several cases a reluctance to change to a bi-annual meeting schedule. But in the end, we managed to get all major societies on board and the first Federation meeting, called Forum of European Neuroscience, was held in Berlin in 1998. The organization of the Berlin meeting, which was in the hands of Helmut Kettenmann and his team, was a financial gamble: Despite a highly cost-effective organization, the meeting had to have more than 3,000 paying registrants to break even, twice as many as the previous ENA meetings. In the end, there were more than 4,000 registrants, and to house the increased numbers of posters, we managed to get Nature Neuroscience, which had just launched their first issues, to sponsor a large tent that was erected outside the meeting room. Since then, the FENS Forum meetings have continued to grow to become a truly international meeting, attended by more than 6,000 delegates from around the world.

Gene Therapy and Viral Vectors

After his move to San Diego, Rusty teamed up with one of the pioneers in the gene therapy field, Ted Friedman, and initiated a new line of research based on the transplantation of cells engineered to secrete therapeutic factors. They developed NGF-secreting fibroblasts and transplanted them to rats with fimbria-fornix lesions, (i.e., the same model we had used in our NGF infusions experiments). In a paper published in Science in December 1988, they could show similar protective and growth-stimulating effects on the axotomized cholinergic neurons as we had obtained with protein infusions. Soon thereafter, in September 1989, Jacques Mallet in Paris published a paper in PNAS showing that cells could be engineered to stably produce L-DOPA and dopamine by the use of retroviral gene transfer.

This approach intrigued me. Here was a new possibility for cell-based dopamine replacement, and I was keen to explore this idea further. I met Jacques at a meeting in Paris in October and suggested that we should collaborate. I checked with Patrik, and he was positive to join as well. We moved quickly, and with Patrik’s help, we transplanted two different cell lines, one secreting only DOPA and one secreting mainly dopamine. Both cell types survived implantation into the dopamine-depleted striatum and expressed TH immunoreactivity. Using the microdialysis technique, we could show that the DOPA-producing cells secreted large amounts of DOPA that was efficiently decarboxylated to dopamine by the host striatal tissue. They produced four to five times higher extracellular dopamine levels than the dopamine-secreting cells, and they were also functionally more efficient. We submitted the paper to Neuron in May and it was out in print in October (Horellou et al. 1990). Not bad—from idea to a high-impact publication in just over a year!

The European Science Foundation had just launched a new program for funding transnational projects in neuroscience. Together with Jacques and his team, we submitted a joint proposal and got funded. This grant made it possible for us to develop this new gene therapy approach, and it provided the money to recruit a new PhD student to this project, Cilla Lundberg. She became the driving force in these projects, and after her thesis defense in 1996, she was the one who led the transition from engineered cells to the use of viral vectors, a technology that has been central to the work in our center ever since.

The viral vector technology led to the development of two major research programs. The first program involved the use of AAV vectors expressing TH and GCH1 for local delivery of L-DOPA. This new line of work started when Ron Mandel spent his second postdoc period in my lab in 1999. He was between jobs, moving from his previous job at the Somatix company to his new job in Gainesville, Florida, and had been allowed by Somatix to use his TH- and GCH1-expressing vectors for experiments here in Lund. This study, which was published in PNAS in 2002 (Kirik et al. 2002a), was the beginning of a program that eventually led us to start our company, Genepod Therapeutics, with the goal to bring this gene therapy approach to the clinic. The second program investigated the use of AAV vectors to overexpress α-synuclein in nigral dopamine neurons as a way to reproduce the synuclein toxicity seen in patients with PD. The role of α-synuclein in PD had been discovered a few years earlier, and the generation of rodent models of what was coined “synucleiopathy” was a hot topic. We were among the first to develop viral vector models of PD that reproduced several of the cardinal features of the human disease. Our first two papers, published in 2002 (in rats; Kirik et al. 2002b) and 2003 (in monkeys; Kirik et al. 2003), have become standard references in this field. Work based on this model, used as a tool to study the pathogenesis of PD and as an experimental model for neuroprotective and disease-modifying treatments, has been central to the work in my lab up to the present day.

Stem Cells: My Road to the Future

My interest in expandable neural progenitors goes back to the early 1990s when techniques for expansion of neural progenitors in the presence of growth factors were developed by Brent Reynolds and Sam Weiss, who developed the neurosphere culture system, and by Rusty and his collaborators, who worked with adherent monolayer cultures. I was intrigued by these new techniques. The use of multipotent progenitors that could be expanded to large numbers in culture suggested a possibility of bypassing the use of fetal cells for grafting. We adopted the neurosphere technique in my lab, and through a collaboration with Melissa Carpenter and Lars Wahlberg at the CytoTherapeutics company, we got access to a stable human neurosphere cell line that we could explore in our transplantation models. We transplanted these cells into the neurogenic regions in the adult rat brain—the subventricular zone, and the dentate gyrus—and showed for the first time that these in vitro propagated human progenitors could respond to in vivo guidance cues, allowing them to migrate specifically along the routes normally taken by the endogenous neuronal precursors: along the rostral migratory stream to the olfactory bulb and within the subgranular zone in the dentate gyrus, with site-specific neuronal differentiation in the granular and periglomerular layers of the bulb and in the dentate granular cell layer (Fricker et al. 1999).

During this time, we worked hard to generate dopamine neurons from neurosphere progenitors, but eventually we gave up: the neurospheres were too heterogeneous in composition, and in our hands, they were largely biased to develop into glial phenotypes in the brain. The important breakthrough in this research had to wait until my former student and postdoc, Malin Parmar, started to work with human embryonic stem cells. After her PhD in 2003, she went to work on embryonic stem cells with Meng Li in Edinburgh, and brought this knowledge back with her to Lund. Eventually, and in close collaboration with a new recruit, Agnete Kirkeby, she managed to devise a protocol for efficient conversion of human embryonic stem cells to dopamine neurons that possess the properties of authentic midbrain dopamine neurons. The paper reporting the performance of these cells in vivo, after transplantation to the striatum and substantia nigra in the 6-OHDA lesion model, published in Cell Stem Cell in 2014 (Grealish et al. 2014) is an important landmark in our efforts to generate transplantable dopamine neurons from stem cells, and a critical step toward their clinical use in PD patients.

Epilogue

Our field has in the past two decades seen two major breakthroughs: the discovery of human embryonic stem cells by Jamie Thompson and collaborators in 1998, and the introduction of cellular reprogramming by Shinya Yamanaka in 2006. These technical innovations have opened up entirely new possibilities and generated important new tools for cell- and gene-based brain repair. The introduction of these new techniques has been truly transformative and has given new momentum to our field. As a result, the research closest to my heart—the development of cell-replacement for brain repair—has over the past decade entered a new exciting phase and made it possible for our lab at the Wallenberg Center, now led by Malin Parmar and her team, to join the frontline in the development of a stem cell–based therapy for PD. Together with our partners in the international consortium, called G-Force-PD, which was established four years ago, we are now part of a coordinated international effort to bring this technology to be tested in the clinic. As I write this, in September 2017, it is 40 years since Ulf and I made our first exploits in cell transplantation and almost exactly 30 years since we operated on our first PD patient. Looking back, I feel both lucky and proud to be part of this exciting new endeavor that builds on the program we started and developed here in Lund. In many ways, it is a continuation of what Olle and I dreamed up 30 years ago.

References

Baumgarten HG, Bjorklund A, Lachenmayer L, Nobin A. 1973. Evaluation of the effects of 5,7-dihydroxytryptamine on serotonin and catecholamine neurons in the rat CNS. Acta Physiol Scand Suppl 391: 1–19.

Baumgarten HG, Bjorklund A, Lachenmayer L, Nobin A, Stenevi U. 1971. Long-lasting selective depletion of brain serotonin by 5,6-dihydroxytryptamine. Acta Physiol Scand Suppl 373: 1–15.

Bjorklund A, Baumgarten HG, Rensch A. 1975a. 5,7-Dihydroxytryptamine: improvement of its selectivity for serotonin neurons in the CNS by pretreatment with desipramine. J Neurochem 24: 833–5.

Bjorklund A, Enemar A, Falck B. 1968. Monoamines in the hypothalamo-hypophyseal system of the mouse with special reference to the ontogenetic aspects. Z Zellforsch Mikrosk Anat 89: 590–607.

Bjorklund A, Falck B, Hromek F, Owman C, West KA. 1970. Identification and terminal distribution of the tubero-hypophyseal monoamine fibre systems in the rat by means of stereotaxic and microspectrofluorimetric techniques. Brain Res 17: 1–23.

Bjorklund A, Falck B, Rosengren E. 1967. Monoamines in the pituitary gland of the pig. Life Sci 6: 2103–10.

Bjorklund A, Gage FH, Schmidt RH, Stenevi U, Dunnett SB. 1983a. Intracerebral grafting of neuronal cell suspensions. VII. Recovery of choline acetyltransferase activity and acetylcholine synthesis in the denervated hippocampus reinnervated by septal suspension implants. Acta Physiol Scand Suppl 522: 59–66.

Bjorklund A, Gage FH, Schmidt RH, Stenevi U, Dunnett SB. 1983b. Intracerebral grafting of neuronal cell suspensions. VII. Recovery of choline acetyltransferase activity and acetylcholine synthesis in the denervated hippocampus reinnervated by septal suspension implants. Acta Physiol Scand Suppl 522: 59–66.

Bjorklund A, Johansson B, Stenevi U, Svendgaard NA. 1975b. Re-establishment of functional connections by regenerating central adrenergic and cholinergic axons. Nature 253: 446–8.

Bjorklund A, Nobin A, Stenevi U. 1973. Regeneration of central serotonin neurons after axonal degeneration induced by 5,6-dihydroxytryptamine. Brain Res 50: 214–20.

Bjorklund A, Stenevi U. 1971. Growth of central catecholamine neurones into smooth muscle grafts in the rat mesencephalon. Brain Res 31: 1–20.

Bjorklund A, Stenevi U. 1977. Reformation of the severed septohippocampal cholinergic pathway in the adult rat by transplanted septal neurons. Cell Tissue Res 185: 289–302.

Bjorklund A, Stenevi U. 1979. Reconstruction of the nigrostriatal dopamine pathway by intracerebral nigral transplants. Brain Res 177: 555–60.

Bjorklund A, Stenevi U, Dunnett SB, Iversen SD. 1981. Functional reactivation of the deafferented neostriatum by nigral transplants. Nature 289: 497–9.

Bjorklund A, Stenevi U, Schmidt RH, Dunnett SB, Gage FH. 1983c. Intracerebral grafting of neuronal cell suspensions. I. Introduction and general methods of preparation. Acta Physiol Scand Suppl 522: 1–7.

Bjorklund A, Stenevi U, Svendgaard N. 1976. Growth of transplanted monoaminergic neurones into the adult hippocampus along the perforant path. Nature 262: 787–90.

Bjorklund A, Wiklund L. 1980. Mechanisms of regrowth of the bulbospinal serotonin system following 5,6-dihydroxytryptamine induced axotomy. I. Biochemical correlates. Brain Res 191: 109–27.

Decressac M, Kadkhodaei B, Mattsson B, Laguna A, Perlmann T, Bjorklund A. 2012. alpha-Synuclein-induced down-regulation of Nurr1 disrupts GDNF signaling in nigral dopamine neurons. Sci Transl Med 4: 163ra56.

Dunnett SB, Bjorklund A, Stenevi U, Iversen SD. 1981a. Behavioural recovery following transplantation of substantia nigra in rats subjected to 6-OHDA lesions of the nigrostriatal pathway. I. Unilateral lesions. Brain Res 215: 147–61.

Dunnett SB, Bjorklund A, Stenevi U, Iversen SD. 1981b. Behavioural recovery following transplantation of substantia nigra in rats subjected to 6-OHDA lesions of the nigrostriatal pathway. II. Bilateral lesions. Brain Res 229: 457–70.

Dunnett SB, Low WC, Iversen SD, Stenevi U, Bjorklund A. 1982. Septal transplants restore maze learning in rats with fornix-fimbria lesions. Brain Res 251: 335–48.

Eriksdotter-Jonhagen M, Linderoth B, Lind G, Aladellie L, Almkvist O, et al. 2012. Encapsulated cell biodelivery of nerve growth factor to the Basal forebrain in patients with Alzheimer’s disease. Dement Geriatr Cogn Disord 33: 18–28.

Fischer W, Bjorklund A, Chen K, Gage FH. 1991. NGF improves spatial memory in aged rodents as a function of age. J Neurosci 11: 1889–906.

Fischer W, Wictorin K, Bjorklund A, Williams LR, Varon S, Gage FH. 1987. Amelioration of cholinergic neuron atrophy and spatial memory impairment in aged rats by nerve growth factor. Nature 329: 65–8.

Fricker RA, Carpenter MK, Winkler C, Greco C, Gates MA, Bjorklund A. 1999. Site-specific migration and neuronal differentiation of human neural progenitor cells after transplantation in the adult rat brain. J Neurosci 19: 5990–6005.

Grealish S, Diguet E, Kirkeby A, Mattsson B, Heuer A, et al. 2014. Human ESC-derived dopamine neurons show similar preclinical efficacy and potency to fetal neurons when grafted in a rat model of Parkinson’s disease. Cell Stem Cell 15: 653–65.

Horellou P, Brundin P, Kalen P, Mallet J, Bjorklund A. 1990. In vivo release of dopa and dopamine from genetically engineered cells grafted to the denervated rat striatum. Neuron 5: 393–402.

Hornykiewicz, O. The History of Neuroscience in Autobiography, Vol. 4, 2004, pp 242–281.

Isacson O, Brundin P, Gage FH, Bjorklund A. 1985. Neural grafting in a rat model of Huntington’s disease: progressive neurochemical changes after neostriatal ibotenate lesions and striatal tissue grafting. Neuroscience 16: 799–817.

Isacson O, Brundin P, Kelly PA, Gage FH, Bjorklund A. 1984. Functional neuronal replacement by grafted striatal neurones in the ibotenic acid-lesioned rat striatum. Nature 311: 458–60.

Isacson O, Dunnett SB, Bjorklund A. 1986. Graft-induced behavioral recovery in an animal model of Huntington disease. Proc Natl Acad Sci USA 83: 2728–32.

Katzman R, Bjorklund A, Owman C, Stenevi U, West KA. 1971. Evidence for regenerative axon sprouting of central catecholamine neurons in the rat mesencephalon following electrolytic lesions. Brain Res 25: 579–96.

Kirik D, Annett LE, Burger C, Muzyczka N, Mandel RJ, Bjorklund A. 2003. Nigrostriatal alpha-synucleinopathy induced by viral vector-mediated overexpression of human alpha-synuclein: a new primate model of Parkinson’s disease. Proc Natl Acad Sci USA 100: 2884–9.

Kirik D, Georgievska B, Burger C, Winkler C, Muzyczka N, et al. 2002a. Reversal of motor impairments in parkinsonian rats by continuous intrastriatal delivery of L-dopa using rAAV-mediated gene transfer. Proc Natl Acad Sci USA 99: 4708–13.

Kirik D, Rosenblad C, Burger C, Lundberg C, Johansen TE, et al. 2002b. Parkinson-like neurodegeneration induced by targeted overexpression of alpha-synuclein in the nigrostriatal system. J Neurosci 22: 2780–91.

Kurowska Z, Englund E, Widner H, Lindvall O, Li JY, Brundin P. 2011. Signs of degeneration in 12-22-year old grafts of mesencephalic dopamine neurons in patients with Parkinson’s disease. J Parkinsons Dis 1: 83–92.

Li JY, Englund E, Holton JL, Soulet D, Hagell P, et al. 2008. Lewy bodies in grafted neurons in subjects with Parkinson’s disease suggest host-to-graft disease propagation. Nat Med 14: 501–3.

Li W, Englund E, Widner H, Mattsson B, van Westen D, et al. 2016. Extensive graft-derived dopaminergic innervation is maintained 24 years after transplantation in the degenerating parkinsonian brain. Proc Natl Acad Sci USA 113: 6544–9.

Lindvall O, Bjorklund A. 1974. The organization of the ascending catecholamine neuron systems in the rat brain as revealed by the glyoxylic acid fluorescence method. Acta Physiol Scand Suppl 412: 1–48.

Lindvall O, Bjorklund A, Hokfelt T, Ljungdahl A. 1973. Application of the glyoxylic acid method to vibratome sections for the improved visualization of central catecholamine neurons. Histochemie 35: 31–8.

Lindvall O, Bjorklund A, Skagerberg G. 1984. Selective histochemical demonstration of dopamine terminal systems in rat di- and telencephalon: new evidence for dopaminergic innervation of hypothalamic neurosecretory nuclei. Brain Res 306: 19–30.

Lindvall O, Brundin P, Widner H, Rehncrona S, Gustavii B, et al. 1990. Grafts of fetal dopamine neurons survive and improve motor function in Parkinson’s disease. Science 247: 574–7.

Loren I, Bjorklund A, Falck B, Lindvall O. 1980. The aluminum-formaldehyde (ALFA) histofluorescence method for improved visualization of catecholamines and indoleamines. I. A detailed account of the methodology for central nervous tissue using paraffin, cryostat or Vibratome sections. J Neurosci Methods 2: 277–300.

Low WC, Lewis PR, Bunch ST, Dunnett SB, Thomas SR, et al. 1982. Function recovery following neural transplantation of embryonic septal nuclei in adult rats with septohippocampal lesions. Nature 300: 260–2.

Martinez-Serrano A, Fischer W, Bjorklund A. 1995a. Reversal of age-dependent cognitive impairments and cholinergic neuron atrophy by NGF-secreting neural progenitors grafted to the basal forebrain. Neuron 15: 473–84.

Martinez-Serrano A, Lundberg C, Horellou P, Fischer W, Bentlage C, et al. 1995b. CNS-derived neural progenitor cells for gene transfer of nerve growth factor to the adult rat brain: complete rescue of axotomized cholinergic neurons after transplantation into the septum. J Neurosci 15: 5668–80.

Piccini P, Brooks DJ, Bjorklund A, Gunn RN, Grasby PM, et al. 1999. Dopamine release from nigral transplants visualized in vivo in a Parkinson’s patient. Nat Neurosci 2: 1137–40.

Sauer H, Rosenblad C, Bjorklund A. 1995. Glial cell line-derived neurotrophic factor but not transforming growth factor beta 3 prevents delayed degeneration of nigral dopaminergic neurons following striatal 6-hydroxydopamine lesion. Proc Natl Acad Sci USA 92: 8935–9.

Schmidt RH, Bjorklund A, Stenevi U. 1981. Intracerebral grafting of dissociated CNS tissue suspensions: a new approach for neuronal transplantation to deep brain sites. Brain Res 218: 347–56.

Skagerberg G, Bjorklund A, Lindvall O, Schmidt RH. 1982. Origin and termination of the diencephalo-spinal dopamine system in the rat. Brain Res Bull 9: 237–44.

Skagerberg G, Lindvall O, Bjorklund A. 1984. Origin, course and termination of the mesohabenular dopamine pathway in the rat. Brain Res 307: 99–108.

Stenevi U, Bjorklund A, Svendgaard NA. 1976. Transplantation of central and peripheral monoamine neurons to the adult rat brain: techniques and conditions for survival. Brain Res 114: 1–20.

Svendgaard NA, Bjorklund A, Hardebo JE, Stenevi U. 1975a. Axonal degeneration associated with a defective blood-brain barrier in cerebral implants. Nature 255: 334–6.

Svendgaard NA, Bjorklund A, Stenevi U. 1975b. Regenerative properties of central monoamine neurons: studies in the adult rat using cerebral iris implants as targets. Adv Anat Embryol Cell Biol 51: 3–77.

Svendgaard NA, Bjorklund A, Stenevi U. 1976. Regeneration of central cholinergic neurones in the adult rat brain. Brain Res 102: 1–22.

Widner H, Tetrud J, Rehncrona S, Snow B, Brundin P, et al. 1992. Bilateral fetal mesencephalic grafting in two patients with parkinsonism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). N Engl J Med 327: 1556–63.

Wiklund L, Bjorklund A. 1980. Mechanisms of regrowth in the bulbospinal serotonin system following 5,6-dihydroxytryptamine induced axotomy. II. Fluorescence histochemical observations. Brain Res 191: 109–27.

Williams LR, Varon S, Peterson GM, Wictorin K, Fischer W, et al. 1986. Continuous infusion of nerve growth factor prevents basal forebrain neuronal death after fimbria fornix transection. Proc Natl Acad Sci USA 83: 9231–5.

Thomas J. Carew

BORN:

Los Angeles, California

July 25, 1944

EDUCATION:

Loyola University, Los Angeles, CA, Psychology BS (1966)

University of California at Riverside, Riverside, CA, PhD (1970)

APPOINTMENTS:

Postdoctoral Fellow, Department of Psychiatry, NYU School of Medicine (1970–1972)

Instructor, Department of Psychiatry, NYU School of Medicine (1972–1974)

Assistant Professor, College of Physicians and Surgeons, Columbia University (1974–1981)

Associate Professor, College of Physicians and Surgeons, Columbia University (1981–1983)

Professor of Psychology and Biology, Yale University (1983–1999)

Professor, Neurobiology and Behavior, University of California, Irvine (2000–2011)

Professor, Center for Neural Science, New York University (2011–present)

Dean, Faculty of Arts and Science, New York University (2011–present)

HONORS AND AWARDS (SELECTED)

National Institute of Mental Health, Career Development Award (1975–1987)

National Institute of Mental Health, MERIT Award (1990)

Yale College Dylan Hixon Prize for Excellence in Teaching in the Natural Sciences (1991)

Endowed Chair, Yale University: John M. Musser Professor of Psychology (1991)

Guest Professor, Free University, Berlin, Germany (1993–1998)

Elected Fellow, American Psychological Association (1991)

Endowed Chair, University of California, Irvine: Donald Bren Professor (2000)

Elected Fellow, American Academy of Arts and Sciences (2004)

Endowed Chair, New York University: Anne and Joel Ehrenkranz Dean of the Faculty of Arts and Science (2011)

Thomas Carew has explored the cellular and molecular mechanisms of memory in the model system Aplysia californica. Early in his career, he was a member of the team in Eric Kandel’s laboratory that provided the first evidence for both long-term memory and associative learning in Aplysia. These discoveries gave rise to independent behavioral, synaptic, and molecular studies in the Carew laboratory first at Yale, then at the University of California–Irvine, and finally at New York University. In this work, he developed several lines of research that provide mechanistic insights into learning and memory. For example, with his research team, he was able to dissociate several different types of memory on both behavioral and synaptic levels, showing, for example, in contrast to a prevailing theoretical view, that it is possible to induce both intermediate-term and long-term synaptic changes underlying memory in the absence of any short-term changes. He also identified three mechanistically distinct phases of synaptic facilitation in the central nervous system, each of which predicted the existence and molecular features of distinct temporal phases of behavioral memory. The predominant focus of his work for the last several years has centered on two basic themes: first, the critical importance of pattern and timing in memory formation; and, second, the essential roles that growth factors play in the induction of long-term memories. In exploring both of these themes, he has been able to identify the contribution of a number of specific molecular cascades, as well as their interactions, in the induction and consolidation of different forms of memory. The overarching goal of his research has been the forging of direct connections between specific synaptic and molecular events to bona fide instances of memory expressed behaviorally.

Thomas J. Carew

Prologue

The singular event that most affected my life was a radiator boiling over; specifically, the radiator of my 1954 Ford station wagon. This stately vehicle had no backseat to make room for my surfboard. It also had no muffler, which had two consequences: first, it made the car sound like a beast, and, second, it caused the floorboard in the back to get really hot, prompting the occasional hitchhiker to ask to get out before his intended destination. I will return to the radiator in a bit.

The Early Years

I was born in Los Angeles in 1944. I grew up in a lower middle-class neighborhood called La Puente and had a rather unremarkable youth. My brother and I went to Catholic elementary school where our classmates were predominantly of Mexican American heritage. I still have fond memories of negotiating lunch deals on the playground where I would trade my typical lunch of tuna fish sandwiches for my classmates’ lunch, usually cold refried beans wrapped in flour tortillas: gourmet meals all around.

High school consisted of a Catholic boarding school in the San Fernando Valley. At the time, I felt that being in boarding school was a little like being in jail, but when I look back, the education I received was certainly of high quality. Following high school, I attended Loyola University in Los Angeles. I was a first-generation kid. My dad was a salesman and my mother was the secretary at a local Catholic school. So, for my parents, my going to college was very important, because it offered me a chance to have a shot at a better life than they had.

Loyola University was a terrific experience for me. Being trained by the Jesuits was extremely important for my early intellectual development. The key elements of this training were an emphasis on logical thinking, on rigorous argument, and on intellectual discipline. It was at Loyola where I first fell in love with learning in general, and with science in particular.

Now back to the radiator. Loyola at that time comprised all male students. The companion university up the road a bit, Mount St. Mary’s, consisted of all women. Occasionally on a Friday night, there would be a dance, called “a mixer,” in which the Loyola men and the Mount St. Mary’s women would get together. In my sophomore year at such a mixer, I met a girl whose name was Mary Jo Sick (that’s right, Sick). I also met another girl that evening: her name was Julie and she was Mary Jo’s best friend from high school. On a Saturday morning a week or two later, I thought it a good idea to drive up the road and drop in to say hi to Julie (unannounced of course; I was not a terribly sophisticated fellow). An important element of the story is that Mount St. Mary’s is on a steep hill. On the way up that hill to visit Julie, my trusty station wagon overheated and the radiator boiled over. So I turned around and coasted down the hill, wondering who else I might know that would want an unannounced visitor? Oh yeah, that interesting gal named Mary Jo. Importantly, she lived at the bottom of the hill, in a fancy neighborhood where she worked as an au pair, taking care of the children of a wealthy family.

So, I dropped by to say hi to Mary Jo. She took my unannounced arrival in stride. We sat out on the front lawn of the wealthy folk’s home and chatted … for a long time. That was in October 1963. We were married the next August (yes, I’m leaving out the part where virtually everyone thought that we were crazy to be married as juniors in college). That was 53 years ago. It’s gotten better every day.

The Formative Years

Two critical events happened while I attended Loyola. First, as I mentioned, I fell in love with science. I always have truly enjoyed mystery stories (I do to this day. Truth be told, I have a serious addiction to Irish crime fiction), and doing science was like being engaged in a real-world mystery story. At Loyola, I was a psychology major and became extremely interested in a field that was then called “physiological psychology” (one of the forerunners of modern neuroscience). I was especially interested in the broad field of learning and memory. Little did I know at the time that this deep interest would profoundly shape my career for the rest of my professional life.

The second critical event that happened at Loyola was the birth of our first daughter, Maura Beth. I have to admit that, on graduation day, carrying Maura on my hip when I went up to get my diploma was quite special.

Immediately after graduating from Loyola, I enrolled in a master’s program in Physiological Psychology at California State College at Los Angeles, hoping to strengthen my chances of attending graduate school for my PhD. I earned my master’s degree in 10 months and, in the following year, enrolled in the graduate program in the Psychology Department at the State University of New York at Stony Brook, where several faculty were interested in studying learning and memory.

While at Stony Brook our second daughter, Amy, was born. So now our family was complete. Soon thereafter, my PhD advisor (Lewis Petrinovich) was recruited to become chair of psychology at the University of California, Riverside (UCR). So with kids in tow, we packed up everything and headed back west.

As a graduate student at UCR, I had little to no mentoring or guidance in the laboratory. I worked pretty much on my own. But that was just fine; the upside was that I could study virtually anything I wanted. I just had to figure out how to do it, from designing the experiments, to building the equipment, to analyzing the data. I have no doubt that problems that took me a week to solve would’ve taken a well-mentored student an hour or two. But the trade-off was well worth it, as I learned a critical life skill: not to be afraid of trying something … anything. The worst that could happen is that it wouldn’t work. And when it did (occasionally) work, wow, what a feeling.

For my thesis project, I studied retrograde amnesia in rats. I recorded from cortex (extracellularly) in freely moving animals, and identified some interesting correlates of memory impairment (Carew 1970). In addition, working with a fellow graduate student and great friend, Terry Crow, we also found some interesting (and surprising) dissociations between cortical and behavioral reflections of a phenomenon called “cortical spreading depression.” That study gave rise to my first paper in Science (Carew et al. 1970).

Are You Finished Yet?

A brief aside is warranted here. Recall that my mom didn’t go to college and had little to no idea of what a “scientist” did. Throughout my graduate years, she would repeatedly ask me a single question: “Have you finished your experiment yet?” This was not an innocent question; it was a less-than-subtle Irish-Catholic guilt trip. And whenever I answered “No, mom, not yet,” there was a moment of silence before she went on to ask about the grandkids.

The New York University Years

I completed my studies for a PhD in 1970. Reflecting on those graduate years, I am quite proud of what I accomplished. I learned not to be afraid to try anything on my own. I also learned that any decent scientific experiment will take at least five times longer to complete than anticipated. But most important, I came to love the feeling of being on the hunt intellectually for important clues as to how the brain accomplishes this trick called “memory,” the effortless and yet magical feat of acquiring information about the world, somehow storing it, and then later retrieving it.

But as much as I loved the big questions that I had studied surrounding the broad area of learning and memory in the brain, I realized that I had, in fact, gained little insight into the actual mechanisms utilized by the brain to achieve this feat. Said another way, I came to appreciate that, although I had acquired a rich vocabulary with which to describe the processes of learning and memory in the brain, I had achieved no true mechanistic insights into how those processes were actually implemented. It was this insight that prompted me to search for a simple model system in which it might be possible to achieve such a mechanistic understanding. Enter Aplysia!

I had read extensively about different invertebrate model systems, and came to appreciate that a premier system was provided by a simple marine mollusk, Aplysia californica. And when I read these papers, far and away the most exciting work was being done by an investigator named Eric Kandel at New York University (NYU). So I wrote to Eric asking him whether it might be possible to join his laboratory as a postdoctoral fellow and, to my delight, he said yes.

On my flight from California to New York City to visit Eric for the first time, I read three extraordinarily exciting new papers from his lab that had just appeared in Science. The coauthors of these papers were Harry Pinsker, Irving Kupfermann, and Vincent Castellucci (Pinsker et al. 1970; Kupfermann et al. 1970; Castellucci et al. 1970). Little did I know at the time, that these three members of the Kandel group would become lifelong friends. These back-to-back Science papers described the analysis of a simple form of learning, habituation. What was incredibly exciting to me was the fact that this elementary form of learning could be simultaneously studied at three levels of analysis: a behavioral level, a circuit level, and a synaptic level. I couldn’t wait to get to NYU!

Joining Eric’s laboratory was a truly transformative experience, for several reasons. First, I was exposed to incredibly smart, energetic, and highly motivated colleagues. These included the primary members of Eric’s lab: as I mentioned above, Vincent Castellucci and Harry Pinsker, as well as Earl Mayeri. Another extremely talented graduate student in the lab, Jack Byrne, had a strong background in engineering. Jack became, and to this day remains, my closest friend.

In addition to Eric’s lab, there were three other laboratories in the overall group. One belonged to a terrific colleague and friend, Irving Kupfermann, who had just formed his own independent group studying the feeding system in Aplysia. There were also two other primary laboratories: one studying sensory processing in the mammalian cortex, led by Alden Spencer, and the other studying fundamental principles of neurochemistry, led by Jimmy Schwartz. Collectively, this consortium of laboratories was highly collegial and extremely interactive.

A truly positive aspect of joining the Kandel lab was the feeling that I had arrived in the major leagues. I felt that the scientific questions about learning and memory that we were trying to solve were fundamentally important, and the analytic techniques with which we attacked these questions were state of the art. Finally, and perhaps most important, was the fact that it was just plain fun to work with these colleagues, each and every day.

Lunchtime Was a Classroom

Another key feature of life in the Kandel lab was lunchtime. In his college years at Harvard, Eric was a student of history. And that background deeply informed every conversation we had at lunchtime. It was routine for Eric to tell us stories about the first person to discover a particular scientific phenomenon, the system and methods that were used, and why the particular finding was important in the field of neuroscience. I cannot overstate the importance of these lunchtime conversations. As a complete tyro in this exciting new field of neuroscience, I had a daily tutorial that made a deep and lasting impact.

Long-term habituation: One of the first major projects that I worked on in the Kandel lab was with my colleague Harry Pinsker. Harry and I were continuing the analysis of habituation that he and other members of the group had carried out the previous year. We developed a method for studying habituation of a simple reflex response (the gill and siphon withdrawal reflex) in freely moving animals. One day Harry and I were examining the magnitude of response (in the siphon-withdrawal reflex) of an animal that we had trained the previous day. To our surprise, the animal still showed evidence of habituation training 24 hours after its original learning experience. This immediately suggested to us that Aplysia might be capable of remembering the habituation training for several days. We set out to examine this phenomenon in detail and found that, when animals received behavioral training for four consecutive days (with only 10 trials per day), they showed significant retention of the memory for habituation for far longer than 24 hours later, even as long as three weeks later (Carew et al. 1972). This was the first demonstration of long-term memory in Aplysia, and opened the door to a wide range of future studies. Next, Harry, Eric, and I carried out a series of studies examining the acquisition and retention of long-term habituation, not only at the behavior level but also at the cellular level. We found that we could identify specific synaptic signatures of long-term memory for up to three weeks after initial training (Carew and Kandel 1973). This was an exciting time for us, as it was the first instance of long-term memory that could be studied in detailed synaptic and mechanistic terms.

Long-term sensitization: Soon after our analysis of long-term habituation, Harry, Eric, and I turned our attention to another form of nonassociative learning called sensitization, an increase in behavioral responsiveness following the presentation of a strong stimulus. We were joined in this study by a graduate student, Wayne Hening. In parallel to the long-term habituation studies that we had carried out the year before, we found that Aplysia also could exhibit long-term sensitization of its withdrawal reflexes. Specifically, when we delivered a noxious stimulus to the tail of the animal repeatedly over a few days, the animal would show memory for sensitization that lasted for several weeks (Pinsker et al. 1973).

Thus, in a period of only a couple of years in the Kandel lab, my colleagues and I discovered that Aplysia was fully capable of at least two forms of long-term memory, for habituation and for sensitization, opening the door to the possibility of detailed mechanistic studies in the coming years. But first, a change of address!

The Columbia Medical School Years

In 1974, our entire scientific group, composed of the Kandel, Kupfermann, Spencer, and Schwartz labs, was recruited to the Columbia College of Physicians and Surgeons located a few miles uptown in New York City. This was a major move that took some serious coordination. But move we did. And by the end of the year, we were all back in business in a wonderful new space up at Columbia Medical School.

Synaptic Studies of Long-Term Memory

Soon after our move to Columbia, Vince, Eric, and I began a series of studies examining long-term habituation and sensitization at a mechanistic level. Informed by synaptic studies that we had carried out previously (Carew and Kandel 1973), Vince and I examined the synaptic connections between identified sensory neurons and motor neurons making up an elementary component of the reflex circuit for the withdrawal reflex that we studied. We discovered that we could in fact identify clear changes at the synapses of intact animals that had received the behavioral training. Specifically, in one set of studies, we found that, in animals that had received long-term habituation training, the synapses were significantly depressed for more than a week (Castellucci et al. 1978). In striking contrast, in a separate set of studies we found that, in animals that had received long-term sensitization training, the same synapses were enhanced, also for more than a week (Carew et al. 1979).

The Quest for Associative Learning

A major feature of learning and memory in higher animals (including humans) is the ability to associate stimuli with either a positive or negative consequence. In our laboratory, we were extremely interested in examining whether Aplysia could exhibit this type of associative learning.

Our first step in this direction was carried out with a talented new graduate student named Terry Walters. Terry, Eric, and I examined a form of associative learning in Aplysia that commonly was known as “fear conditioning.” We found that Aplysia could learn to associate the taste and smell of a chemical in seawater with a negative consequence, such as tail shock. Specifically, after pairing the chemical stimuli with tail shock, subsequent delivery of this chemical stimulus alone would enhance the reflex responsiveness in the animal. We went on to study this interesting form of associative learning at both a behavioral level and at the level of neural correlates of the learning (Walters et al. 1979, 1981; Carew et al. 1981). This was the first evidence of associative learning that we identified in Aplysia.

Differential Classical Conditioning

Perhaps the most familiar form of associative learning is called “classical” or “Pavlovian” conditioning. A major goal of the lab for many years was to examine whether Aplysia were indeed capable of classical conditioning. A wonderful new postdoctoral colleague, Bob Hawkins, recently had joined the laboratory, as had a very bright young behavioral technician, Emily Marcus, who had just graduated from college. So the team was ready to go. We set out to examine the question of whether Aplysia were capable of exhibiting bona fide classical conditioning. We struggled with this problem for months and finally, after several frustrating attempts, we were successful. Specifically, we discovered that Aplysia were fully capable of a rather sophisticated form of associative learning called “differential classical conditioning” (Carew et al. 1983). We went on to study this phenomenon in behavioral detail, and subsequently Bob, Eric, and I, together with a new postdoctoral colleague, Tom Abrams, were able to identify a powerful candidate synaptic mechanism for classical conditioning called “activity-dependent facilitation” (Hawkins et al. 1983; see also Walters and Byrne 1983). These were indeed exciting times in the Kandel laboratory.

My First Grant Award!

During these years in Eric’s lab I was privileged to be free from the stress of having to get independent grant funding. That said, it was truly important for me to jump into this arena and learn the ropes of National Institute of Health (NIH) applications. My first serious foray into the grant world was my submission for a Career Development Award from the National Institute of Mental Health (NIMH). And what do you know, I got the award the first time out. Moreover, I was truly fortunate to renew that award twice more. Thus, I had continuous funding by the Career Development Award from 1975 to 1987. I remain deeply appreciative of this early support of my work by the NIMH. I have been privileged to enjoy continuous funding from NIMH throughout my entire career (to the present day, more than 42 years).

Moving On

In the fall of 1982, Eric and I were both invited to speak at a conference on learning and memory held at Princeton University. At that conference, I was approached by a senior member of the Psychology Department at Yale, Allan Wagner, a renowned learning theorist whose work I deeply respected and admired. After a brief introductory chat, he asked me a straightforward question: Would I ever consider joining the Psychology Department at Yale? I was both truly surprised and deeply honored by the question. The answer was simple: of course, I would.

Soon thereafter, I visited Yale and gave a talk to the students and faculty of the Psychology Department, as well as to the broader neuroscience community. They were an intellectually stimulating group of people who were great fun to meet and get to know. Following this visit, I was fortunate enough to receive an offer from Yale. After a few weeks of discussions with Yale (and a good bottle of wine with Mary Jo to consider what this opportunity would mean for the family), we were on our way to New Haven.

The Yale Years

As soon as I arrived at Yale, it was very important to me to set up an active, independent laboratory. I was extremely fortunate to have an early key partner in this endeavor, as Emily Marcus, that very talented behavioral technician who had joined the Kandel lab at Columbia a few years earlier, agreed to come with me to Yale to help establish the new laboratory.

Setting Up the Lab

Emily and I worked tirelessly for months setting up the lab. One notable memory deserves mention. In the lab we had several large (400 gallon) seawater tanks in which to study the behavior of Aplysia. To keep each animal separately housed, we developed a system of individual “cages” that were actually plastic colanders, individually fitted with small Styrofoam cubes to keep them afloat in the tank. To set up this behavioral system, one day Emily and I set out to a local large grocery store to buy the colanders. We found about three dozen of them on the shelf and put each and every one of them in our shopping cart. When we went to the checkout stand, the cashier looked at us strangely and remarked: “Man, you folks must really like spaghetti!” Now I had two choices: One was to tell her exactly what we were going to do; namely, individually house marine mollusks in a very large aquarium to study their learning and memory. The other option was to simply say, “Yeah, we really can’t get enough of the stuff.” Prudence was the better part of valor: I opted for the latter explanation, leaving the cashier with a good story to tell her coworkers later that day.

Now What Do I Do?

In setting up my lab at Yale, a major goal was to chart out new experimental territory to establish my scientific independence. I knew that I wanted to continue to examine learning and memory at multiple levels of analysis, and that meant continuing to use the powerful system of Aplysia that I was so fortunate to learn in the Kandel lab. There were two novel areas that I wished to establish right away, both using Aplysia. One program focused on the development of learning and memory, and the other on neural mechanisms underlying operant conditioning. In both of these endeavors, I was extremely fortunate to be joined by very talented colleagues.

Development of Learning and Memory in Aplysia

The overall rationale for the developmental program in the lab was this: Development can serve as a powerful dissection tool with which to examine the relationship between different forms of learning. Here is a simple example. Two forms of nonassociative learning that were commonly studied at behavioral and cellular levels in Aplysia were sensitization (the facilitation of a nondepressed reflex response) and dishabituation (the facilitation of a previously habituated response). Both can be induced by exactly the same stimulus (e.g., a mild shock to the tail), and phenotypically they look identical. But are they? One way to answer this question is to examine when these forms of learning emerge developmentally. It turns out they have very different developmental timetables (see below), showing that they are indeed, at least in part, different processes. The ability to launch this major research program at Yale was founded on previous groundbreaking work of Arnold Kreigstein, Steven Rayport, and colleagues in the Kandel lab who were responsible for several technical and conceptual breakthroughs in the analysis of the development of Aplysia from their early larval stages all the way into adulthood (Kriegstein et al. 1974; Kandel et al. 1980; Rayport and Kandel 1986).

The development of habituation and sensitization: In the examination of the development of learning and memory, I hit pay dirt right away, as two gifted postdoctoral fellows, Cathy Rankin and Tom Nolen, joined the lab. Cathy assumed primary responsibility for the behavioral analysis in the project, while Tom took on the cellular component. Also at this time, the lab began to grow further. A talented young undergraduate at Yale, Mark Stopfer, joined the group as a graduate student, and to my delight, Emily Marcus decided to apply to the Department of Biology at Yale and begin her graduate career in our lab. Thus, the lab began to gel into a small but well-organized community.

As we began our behavioral studies, I clearly remember chatting with Cathy about her project. Using a high-powered inverted microscope, she was going to study the development of habituation of the siphon withdrawal reflex in individual larval animals, each of which looked just like a speck of dust in a test tube of seawater. Cathy held up the tube and asked me straight away: “Can we really do this??” And with great confidence I answered, “Absolutely!” And then (as Cathy learned later), I went across the hall, closed my office door, and asked myself the question: “Can we do this?” Luckily, the “we” was Cathy, who had magic hands and plenty of resolve.

So Cathy and Tom, together with Emily and Mark, tackled the developmental project with equal amounts of creativity and high energy (with a healthy dose of skepticism thrown in, appropriately so, given the extremely challenging technical nature of the experiments on both behavioral and cellular levels). But thanks to their hard work and perseverance, the overall project proved quite successful and offered novel insights into the relationship among three important forms of nonassociative learning: habituation, dishabituation, and sensitization, each of which we found to emerge behaviorally according to different developmental timetables (Carew 1989).

In the ensuing years, I was extremely fortunate to have a number of extraordinary colleagues join the lab both as graduate students and as postdoctoral fellows. Among the postdocs were Tom Fischer, Nigel Emptage, Carolyn Sherff, Bill Wright, Diana Blazis, Julianne Mauelshagen, Sharen McKay, and Lore Gruenbaum. These young scientists were highly motivated and soon identified projects that would allow them to pursue their interests in the laboratory. I’ll expand on this theme shortly.

At different times, we also were joined by three extraordinary senior scientists: Alison Mercer from Otago University in New Zealand, Uli Mueller from the Free University in Berlin, and Yadin Dudai from the Weissman Institute in Israel.

In addition to these postdoctoral fellows and senior scientists, several graduate students came on board. These bright young folks included David Cook, Fred Kinsey, Kent Fitzgerald, Laura Stark, René Marois, Teresa Nick, Stephen Fisher, Adam Bristol, Angela Purcell, and Michael Sutton.

So those were the Yale teammates who collectively, over a span of 15 years, made this phase of my career a true joy, both scientifically and personally. Let me now give you a sense of some of their accomplishments.

Developmental timetables for behavioral plasticity: The deep theme of the developmental project informed many of our studies in those years. Kathy, Tom, Mark Stopfer, Emily Marcus, and I published several papers examining different forms of learning in terms of their developmental timetables and underlying mechanisms (Rankin et al. 1987; Rankin and Carew 1987, 1988, 1989; Nolen et al. 1987; Nolen and Carew 1988; Stopfer and Carew 1988; Marcus and Carew 1998; Stark and Carew 1999). This team was also able to differentiate and analyze a wide range of behavioral plasticity in the adult animal. For example Emily, Tom, Kathy, and I found that, just like in the developing animals, we could behaviorally dissociate habituation, dishabituation, and inhibition in adult animals (Marcus et al. 1988a). This finding paved the way for important future mechanistic studies.

Structural development of a modulatory serotonergic circuit: Another extremely talented graduate student in the laboratory, René Marois, tackled a very difficult problem. René wished to study the development of the modulatory circuit in Aplysia at the ultrastructural level. René was fearless in his project. Because none of us in the laboratory had ever done electron microscopy before, René got the training he needed from another extremely helpful colleague at Yale, Susan Hockfield (who, a few years later, went on to be the president of MIT). Thanks in large measure to Susan’s critical guidance, René produced a seminal series of papers describing in detail the ultrastructural development of serotonergic modulation in the larval stages of Aplysia (Marois and Carew 1997a, 1997b, 1997c).

Operant Conditioning in Aplysia

The second novel project that we tackled was the examination of a form of associative learning called operant (or instrumental) conditioning. The rationale for this project was this: Because Aplysia had proven to be such a powerful system for studying diverse forms of nonassociative learning (habituation, dishabituation, and sensitization), and a major form of associative learning (classical conditioning) at a mechanistic level, it might also prove to be a good system for studying another major form of associative learning, operant conditioning.

At about this time, David Cook asked to join my laboratory as a graduate student. David arrived with lots of ideas and full of energy. He approached this difficult problem with great creativity and came up with a way to establish that Aplysia could indeed exhibit operant conditioning. And he did so in a novel way: David took advantage of a natural occurring behavior of Aplysia called head-waving. When the animal is suspended above a substrate underwater, it naturally waves its head back-and-forth searching for food or for a place to gain a foothold. David found that Aplysia do not like bright light. So he combined these two facts and asked whether he could operantly condition Aplysia to change their head-waving response in response to the presentation of bright lights (this would be called negative reinforcement in the learning trade). David found that he could indeed teach Aplysia in this fashion. Animals readily learned to change their head-waving response to avert the bright lights (Cook and Carew 1986). This constituted a basic but effective form of operant conditioning in this simple model system. For his thesis, David went on to examine operant conditioning at three levels: (a) at a behavioral level, (b) at the level of identified electrical activity in the muscles that produced the operant response (head waving), and (c) at the cellular level of identifying possible reinforcement pathways in the central nervous system that mediated this form of learning (Cook and Carew 1989a, 1989b, 1989c; Cook et al. 1991).

Temporal Domains of Memory

Another theme that emerged during the Yale years was the examination of the mechanistic differences between various temporal phases of memory. We examined three phases in depth over the ensuing years (and we continue to do so to this day in my current lab at NYU): short-term memory (lasting minutes), intermediate-term memory (lasting hours), and long-term memory (lasting days to weeks, and even longer). As I will illustrate with several examples, we found that the best way to differentiate these three temporal domains was not on the basis of time, but rather on the basis of what we call their “molecular signatures.” This overall thread of research that began at Yale has remained an active focus of our research efforts for more than 20 years.

Long term in the absence of short term: Allison Mercer, Nigel Emptage, and I combined pharmacological and synaptic physiological approaches to examine different forms of synaptic plasticity at the sensory neuron to motor synapse in the reflex circuit. In one of our studies, Allison made use of a specific pharmacological blocker that differentiates different kinds of serotonergic receptors and, with Nigel, found that we could completely block short-term synaptic plasticity, while leaving long-term plasticity completely intact (Mercer et al. 1991). In another study, Nigel and I went on to conclusively show that long-term synaptic facilitation could be observed in the complete absence of short-term facilitation (Emptage and Carew 1993). These studies were a major breakthrough for us, because they addressed a fundamental question in the neurobiology of learning: Is short-term memory required for long-term memory? Allison and Nigel’s data showed quite clearly that it was possible to generate clear long-term synaptic facilitation (the cellular correlate of long-term memory in Aplysia) in the complete absence of short-term facilitation.

Synaptic analyses of dynamic gain control in a well-defined neural circuit: I first met my postdoctoral fellow Tom Fischer when he was a student at the Neural Systems and Behavior course at the Marine Biological Laboratory in Woods Hole, MA, in which I participated for several years (more about this later). Tom was a gifted synaptic physiologist. He became very interested in an inhibitory circuit for the withdrawal reflex in Aplysia and carried out several seminal studies in this well-defined circuit. With several colleagues, including Diana Blasis, a new postdoctoral fellow, Tom showed that this inhibitory synapse could provide a form of “dynamic gain control” in the reflex circuit (Fischer et al. 1997). In a particularly interesting study, Tom further expanded our horizons by elucidating a phenomenon called “meta-plasticity,” which essentially means that the plasticity exhibited in this dynamic gain control process could itself be shaped by experience. This exemplified the power of combining synaptic physiology with a conceptual analysis of neural processing in this simple reflex circuit (Fischer and Carew 1995a, 1995b; Fischer et al. 1997; Fischer et al. 2000).

A final word about Tom is relevant: In addition to being a terrific scientist and a die-hard hockey player (who often came back from a “lunch break” at the Yale hockey rink with a few bruises to his credit), he was also a deep thinker. For example, in a lab meeting one day, he posed the question: “24 hours in a day; 24 beers in a case; coincidence?” As I said, Tom was a truly thoughtful colleague.

Synapses and cell bodies learn to get along: Another creative postdoctoral colleague, Carolyn Sherff, significantly advanced our understanding of the induction of long-term synaptic facilitation. In a series of clever experiments, Carolyn developed a chamber in which the cell bodies of the sensory neurons could be functionally separated from their synapses onto motor neurons by means of a watertight barrier. This allowed Carolyn to independently manipulate the molecular environment of the synapses, or the cell bodies. In one experiment, Carolyn asked whether local application of the neuromodulator serotonin at the sensory neuron synapse could contribute to the induction of long-term synaptic facilitation produced by serotonin applied at a later time to the cell body. And, indeed, she proved that was the case. She found that long-term synaptic facilitation could be induced, with a striking form of “cooperativity” between the cell bodies of the sensory neurons and their remote synapses (Sherff and Carew 1999).

The Molecular Architecture of Learning and Memory

A deep theme of our work for many years (and to the present day) has been the examination of the molecular mechanisms that underlie the diverse forms of learning exhibited by Aplysia. This research program really flourished at University of California Irvine (UCI, as I will describe). But without doubt, it had its inception at Yale, with the help of two friends and colleagues, Uli Mueller and Yadin Dudai.

Protein kinase A: I mentioned before that Uli Mueller, old friend and colleague from Berlin, spent a year in my laboratory at Yale. Uli had a deep understanding of second messenger signaling in neurons. His scientific work was primarily in honeybees, so he was no stranger to invertebrate neurobiology. When he came to the lab at Yale, we decided to examine different phases of activation of a key second messenger in neurons, the cyclic AMP-dependent protein kinase, or protein kinase A (PKA). PKA already has been well established as an important second messenger system in Aplysia through the groundbreaking work done by Jimmy Schwartz and his colleagues back in the NYU days. What Uli brought to our laboratory was a novel technique that would allow us to examine in great detail the temporal choreography of different phases of PKA activation in the sensory neurons. In one series of experiments, Uli and I found that serotonin produces temporally and mechanistically distinct phases of persistent activation of PKA in the sensory neurons (Mueller and Carew 1998). This finding significantly enhanced our understanding of the role of this critical second messenger system in the production of long-term memory in Aplysia.

Another important step in our molecular studies was provided by Yadin Dudai, who spent several months in the lab at Yale and introduced us to additional molecular techniques for studying cAMP in Aplysia. This greatly aided our work at the time and would prove to be especially valuable for our later work. He was also a real mensch.

Molecular pathways and memory formation: An additional series of experiments began with the arrival of a new graduate student, Michael Sutton. In his first series of studies, Mike examined two distinct forms of synaptic facilitation at the sensory-motor synapse. Complementing the findings that Uli provided a year earlier, Mike found that parallel molecular pathways mediate the expression of two distinct forms of intermediate-term facilitation at the sensory-motor synapses (Sutton and Carew 2000). Through these experiments, Mike opened up an entirely new direction of experimental inquiry in the laboratory, one that greatly advanced our collective understanding of the temporal domains of memory formation.

Early Studies of Growth Factors in Aplysia: Foreshadowing the Future

Soon after a talented developmental biologist, Sharon McKay, joined the lab as a postdoctoral fellow, we began to examine the role of specific molecules, “growth factors,” that are critical in wiring up the brains of developing animals. Growth factors were first identified by Rita Levi-Montalcini and Stanley Cohen, who showed that these molecules are critically important during the development of the nervous system. For this groundbreaking work, Levi-Montalcini and Cohen received the Nobel Prize in 1986.

Sharon and I were interested in the question of whether growth factors might also have significant effects in adult animals, specifically in the induction of synaptic and behavioral plasticity (McKay et al. 1999). About that time another postdoctoral fellow, Laurie Gruenbaum, also joined our group. I was extremely fortunate to have Laurie come to the shop because she had been a graduate student with Uli Mueller back in Berlin, and thus was truly well trained. A final critical player in this new growth factor team was Angela Purcell, a new graduate student in the lab. Angela was highly motivated and tenacious in her experimental pursuits. This small team of colleagues in the lab was very energetic and productive. The collective insights provided by the team’s work showed that growth factors in Aplysia could significantly influence the following: (a) the pattern of growth of identified neurons, (b) the specific kind of facilitation that is induced at the synapse, and (c) specific molecular cascades during long-term synaptic facilitation (Gruenbaum and Carew 1999; McKay et al. 1999), These early findings helped to launch an experimental program that, to this day, remains a central focus of my laboratory.

A tragic postscript: One of the most gifted and committed young scientists I have ever met was a young postdoctoral fellow in my lab, Julianne Mauleshagen. Julianne had been a graduate student with Randolf Menzel in Berlin. She came to my laboratory to study synaptic mechanisms of learning and memory (Mauleshagen et al. 1996, 1998; Bunge et al. 1997). Julianne had two great passions: science, and mountain climbing. When she wasn’t in the laboratory, she was scaling a mountain somewhere around Connecticut. One evening when I was at Cold Spring Harbor for a scientific conference, I got a phone call that I will never forget. Julianne had tragically fallen from mountaintop in upstate New York and was killed. The lab was in shock, for we all loved Julianne and truly admired her for her extraordinary dedication to her work. A few weeks later, two communities gathered together in a meadow near Yale to share our memories of Julianne: the scientific community from my laboratory and the climbing community from the local region. I can still see that meadow.

The Berlin connection: The fact that several of the colleagues who joined me at Yale were from Berlin, and specifically, the Free University of Berlin, was no coincidence. This relationship with colleagues in Berlin arose from a long-standing friendship with Randolf Menzel, a colleague, at the Free University. Randolph, a neuroethologist, was one of the leading experts in the world in honeybee behavior. In Berlin, Randolf had assembled a phenomenal group of scientists to study the learning ability of this fascinating animal. Randolph and I met at a conference in Europe some years earlier and had become close friends. Over a period of five years, for a month or so each year, I was delighted to be a guest professor in Randolph’s laboratory at the Free University. I will never forget those years in Berlin, as they introduced me to a new culture; a new way to examine and think about behavior; and, most important, to a wonderful new set of friends and colleagues.

Teaching at Yale

One of the reasons that I was highly motivated to join the Yale faculty in 1983 was that it would allow me to reconnect to something I truly valued: the opportunity to teach undergraduates. After I first arrived, I taught several types of courses and came to realize that an important dimension of a complete academic experience was missing for our students. Specifically, there was no introduction or exposure to the analysis of brain mechanisms of naturally occurring behavior. Broadly speaking, this discipline is called “neuroethology.” I was fascinated by this discipline and began reading avidly to develop a comprehensive course in this area.

Writing a textbook … no problem! After teaching this course for several years at Yale, it occurred to me that it might be worthwhile to write a textbook describing some of the extraordinary studies that had been carried out by leaders in this field, such as Karl Von Frisch, Nikolaas Tinbergen, and Konrad Lorenz, who collectively won the Nobel Prize in physiology or medicine in 1973. Little did I know what I had in store for me. By this time in my scientific career, I had written literally dozens of original scientific papers as well as several scholarly reviews. So I thought that I was well prepared for the task of writing a textbook. How hard could it be? I will never forget one summer in Maine. We had a summer home on a lake where I spent the entire summer writing the first chapter of the book, which focused on echolocation in bats. I read avidly, collected every scholarly paper I could find, and set out to tell the story. I wrote every day and, at the end of two long, arduous months, I looked at what I had written and realized it was terrible. Perhaps the most challenging but important decision I ever made in my career as a teacher was to tear up the entire manuscript and start from scratch. So what was wrong with my work, telling the story of echolocation? The problem was simple: It was extremely scholarly, it was a very comprehensive review of the literature, and it was unbelievably boring. I did not tell a story, nor did I allow the reader to engage in both understanding and appreciating the amazing abilities of these animals. It was simply a dry, scholarly work best suited in the hands of a curious professional in the field, not a student’s hands.

So I started over and asked myself: “How in fact do I teach this material when I lecture in front of students in a classroom?” I don’t try to simply provide them with a scholarly perspective (although this is certainly part of the goal), but rather, I also try to engage students and allow them to come along for the ride as they learn about the phenomenal ability of bats to navigate their world with ultrasound and echolocation, using highly specialized brain mechanisms such as a neural Doppler-shift analysis to distinguish, while on the wing, between a flying moth and a falling leaf.

Once I got back on track with this kind of mind-set for the book, I worked steadily for two years, learning about a wide range of animals in their natural environment, and how the brains of these animals provided them with elegant mechanisms for successful adaptation in their world. And during this time, I was extremely fortunate to have many ethological colleagues around the world who were experts in these specialized areas, and who were willing to read my chapters and work critically with me, to keep me on track in a scholarly domain. The book finally saw the light of day in 2000 (Carew 2000).

1990 Was a Good Year

A teaching prize: Over the years, my course, called “The Cellular Basis of Behavior” (or CBOB, as the students affectionately called it) grew substantially, often enrolling several hundred students. Teaching this course was one of the high points of my career at Yale. And I was truly honored in 1990 to be voted by the undergraduates to receive the Yale College Dylan Hixson prize for excellence in teaching in the natural sciences. This was a real honor that I genuinely appreciate to this day.

Paying the bills: When I arrived at Yale in 1983, I was extremely fortunate to already have extramural funding. As I mentioned previously, while at Columbia I received a Career Development Award, which I took with me to Yale. It lasted until 1987 and was extremely important in the early years. After that, I was fortunate to maintain continuous funding through several other grants, mainly from NIMH, and also crucially, for many years from the National Science Foundation. But in 1990, I received a surprise: a letter from NIMH that I opened late one night in the lab. It looked to be pretty routine; so I just scanned it. Then I looked again. I remember walking down the hall to my postdoc Bill Wright’s office and saying, “Would you read this … does it say what I think it does?” In Bill’s inimitable way he said, “Yep.” The letter said that I had been awarded a MERIT Award from NIMH that provided 10 years of uninterrupted funding. It was a good night.

An endowed chair: To cap off 1990, at the end of that year, I was awarded an endowed chair, being named the John M. Musser Professor of Psychology. Being recognized at Yale in this fashion was quite special.

A Visit from Jim McGaugh

It was common at Yale, as at most major research universities, to have famous scientists come to give one or more talks about their work. Thus, it was no surprise that a leading figure in behavioral neurobiology, James McGaugh, came to give a talk. Jim was not just a pioneer in developing this field at UCI, but also one of the founding fathers of the university itself. He also happened to be an old friend from my graduate school days at UCR. So, when he visited Yale, Mary Jo and I invited him to stay at our home rather than stay in a hotel (not an unusual occurrence in our family). After his talk and the usual dinner with other faculty, we came home and sat around the fireplace chatting. Jim had a funny grin on his face and said, “You know I feel a little awkward being a guest of Yale and asking you this question.” That said, pressing on, he asked whether I would be interested in the possibility of coming to UCI to be the chair of the Department of Neurobiology and Behavior. Having held this department in very high regard for many years, I found this a seriously intriguing possibility. To make a long story short, I made a couple of very productive visits to UCI and truly enjoyed meeting the faculty and students. After a third visit, when Mary Jo and I returned from Irvine to New Haven, we broke out a bottle of wine to think it over, and we decided to take on this new adventure. So we packed our bags and headed back west.

The University of California Irvine Years

I was extremely fortunate to have several of my Yale colleagues join me in my move to UCI. These included my long-term colleague Carolyn Sherff, and a new postdoctoral fellow, Stephane Marinesco. In addition, four graduate students, Mike Sutton, Angela Purcell, Adam Bristol, and Joanna Schaffhausen also elected to come along, and a very talented undergraduate at Yale, Martha Bagnall, who had worked in our laboratory in New Haven, also opted to move with us. Finally, a critical member of our Yale group, our lab manager Paul Hofstadter, also elected to join us, rounding out our UCI research team.

In large part thanks to all of these colleagues, the move to UCI was extremely easy and efficient. The moving van arrived on a Monday, and by Friday the lab was, for the most part, up and running. We had only one rule: Everyone had to replicate the last experiment they did in New Haven to make sure that they still worked on the West Coast.

In addition to the colleagues who moved with me from Yale, I was joined at UCI by a new, highly talented postdoctoral colleague, Shiv Sharma, and a few years later, by a second postdoctoral fellow, Lu Pu. Finally, I was extremely fortunate to have several very bright graduate students join the lab during the UCI years. They included Kathryn (Kate) Reissner, Justin Shobe, Gary Phillips, Shara Stough, Xiaojing Ye, Soren Fischbach, and Ashley Kopec.

Chairmanship of Neurobiology and Behavior

Before I discuss the scientific programs in our laboratory at UCI, I want to spend a moment discussing a new role for me in my career: being the chair of a major neuroscience department. I had indeed been chair of the Department of Psychology at Yale for six years. I thoroughly enjoyed that experience and learned a great deal from it. But Yale had a tradition going back more than 350 years, whereas UCI was only 35 years old when I joined it. Thus, I had the opportunity at UCI to deeply engage in the continued development of an exciting, young department, the Department of Neurobiology and Behavior (NB&B). Moreover, I was privileged to receive an endowed chair at UCI, being named a Donald Bren Professor of the University. There were only two other Bren Professors at the time: F. Sherwood (Sherry) Rowland (who won the Nobel Prize in Chemistry in 1995), and Franciso Ayala, a world-famous evolutionary biologist and philosopher … heady company, indeed.

The faculty colleagues who I was privileged to work with in NB&B were a highly collegial group and were deeply committed, not only to their own work, but also to the continued growth and excellence of the department. I was also delighted to become a member of the Center for the Neurobiology of Learning and Memory (CNLM) that was established by the University of California Regents in 1983, with Jim McGaugh as its founding director. The CNLM was a lively and exciting group of UCI faculty and students who all shared a deep interest in learning and memory.

In my position as chair of NB&B, I learned a great deal, not only about different areas of neuroscience that were represented in our department, but also about the importance of consultation, transparency, and collaboration in guiding the department. I also learned a lot about myself. For example, I learned that I thoroughly enjoyed the process of recruiting highly talented new young faculty to the department, providing them with as many resources as we could muster to ensure their success, and then getting out of their way and watching them flourish. This was one of the most rewarding aspects of my 11 years as chair at UCI.

I also enjoyed having the opportunity to learn how a major research university actually works, at the level of higher administration. During my time at UCI, I was extremely fortunate to have a wonderful chancellor, Ralph Cicerone; a highly engaged and talented provost, Mike Gottfredson; and a very collegial dean, Susan Bryant, to help me learn the ropes as I developed as chair of NB&B over the following decade or so.

Now back to science. During our 11 years at UCI, my colleagues and I continued some of the principal work that we had begun at Yale and also set out on some new scientific paths to explore.

Temporal Domains of Memory

One of the major themes that we had established at Yale, and we continued to pursue at UCI, was an exploration of the mechanisms underlying different temporal domains of memory. An important collaborator in this enterprise was my graduate student Mike Sutton. Together with Martha Bagnall and others members of the lab, Mike carried out a number of seminal studies examining different phases of memory in Aplysia. One key finding in these studies was that different forms of memory in exactly the same temporal domain could be clearly distinguished by their underlying molecular mechanisms. We were especially interested in a temporal domain called “intermediate-term memory.” We found that there were actually different forms of intermediate-term memory for sensitization that were mediated by different molecular mechanisms. For example, one form that is induced by repeated trials (either tail shock in the intact animal, or serotonin in cellular experiments) required both the second messenger PKA and protein synthesis, whereas another form, produced in an activity-dependent fashion, required a different second messenger system, PKC, and did not require protein synthesis (Sutton et al. 2001, 2004). Further understanding of the temporal domains of memory was provided by Justin Shobe together with other colleagues in the laboratory. Building on the work of Shiv Sharma in the lab, Justin found that the temporal phases of activity-dependent plasticity and memory in Aplysia are mediated by a form of compartmentalized “routing” of the critically important second messenger, mitogen-activated protein kinase (MAPK), in the sensory neurons (Shobe et al. 2009).

It’s all in the timing: Another theme that we began to explore at Yale, but took up in earnest when we moved to UCI, was the importance of the patterning of training trials in producing long-term memory for sensitization.

A key finding produced by Mike Sutton and other colleagues in the lab was that long-term sensitization in Aplysia behaved just like virtually every other form of long-term memory in the animal kingdom; it is extremely sensitive to the temporal pattern of training trials (Mauelshagen et al. 1998; Sutton et al. 2002). Thus, trials spaced out in time are typically far superior in producing long-term memory than the same number of trials presented in rapid succession. This is called the “massed-spaced effect,” which was first described more than a century ago by the renowned learning psychologist Herman Ebbinghaus (1885).

Another seminal finding in the examination of patterning in memory formation was made by Gary Phillips and others in the lab. Specifically, Gary found that long-term memory in Aplysia could be induced by only two sensitization training trials (tail shocks), if those trials were spaced by a critical temporal interval, 45 minutes. Surprisingly, the same two trials spaced either by 15 or 60 minutes, were ineffective in producing long-term memory. Only the 45-minute interval provided a “permissive window” for the induction of long-term memory. Gary went on to show that the transient activation of MAPK also was confined to a narrow temporal window that exactly aligned with the behavioral observations: MAPK was significantly activated only in the 45-minute window (Philips et al. 2007; Philips and Carew 2013). This not only provided important insights into the importance of trial pattern in memory formation but also paved the way for critical future experiments examining the role of growth factors in long-term memory.

G-proteins: A final critical observation that gave us further insights into the importance of patterning in memory formation came from the work of a gifted graduate student, Xiaojing Ye. Along with other members of the lab, Xiaojing showed that critical small molecules, “G proteins,” exhibited clear pattern sensitivity during MAP activation, both in the induction of long-term synaptic facilitation and long-term memory (Ye et al. 2008). These results critically informed our understanding of the way the nervous system uses its molecular tool kit to induce long-term memory in a pattern-sensitive fashion.

Behavioral, Synaptic, and Molecular Analysis of Long-Term Memory

Mitogen-activating protein kinase: A recurrent theme in some of the studies that I have described emphasized the crucial role of a fundamentally important second messenger MAPK in memory formation in Aplysia. MAPK is also known to be critically important in memory formation in a wide range of other species, from invertebrates to mammals. Our understanding of MAPK was significantly advanced by the studies conducted by Shiv Sharma in the lab. Shiv, together with Carolyn Sherff, Martha Bagnall, and Mike Sutton, discovered a differential role for MAPK in three distinct phases of memory for sensitization (Sharma et al. 2003a; Sharma and Carew 2004). Shiv also showed that MAPK was responsible for removing a critical molecular brake (the phosphatase calcineurin) in the induction of both intermediate-term and long-term memory for sensitization (Sharma et al. 2003b).

The neuromodulator serotonin: Earlier work in the Kandel lab had uncovered the critical role that the neuromodulator serotonin plays in the induction of long-term synaptic plasticity in Aplysia. A new postdoctoral fellow, Stephane Marinesco, joined my lab to further explore the role of serotonin in memory formation. Stephane developed an electro-chemical detection system using carbon fiber electrodes to directly measure the release of serotonin, in real time, in the central nervous system of Aplysia (Marinesco and Carew 2002a). Using this approach, Stephane identified a “distributed serotonergic network” that was activated by the sensitizing stimuli that produce long-term memory. He went on to show that the regulation of behavioral and synaptic plasticity by serotonin was accomplished through its release within local “modulatory fields” in the nervous system of Aplysia (Marinesco and Carew 2002b). These studies significantly advanced our understanding of the ways in which the neuromodulator serotonin exerts its diverse effects in the induction of both synaptic plasticity and memory.

Synaptic plasticity underlying long-term memory: In parallel to the behavioral and molecular studies described earlier, another focus of the lab was the study of synaptic plasticity during memory formation. One key study was carried out by Carolyn Sherff, in which she examined the coincident induction of long-term facilitation at the sensory-motor synapses of Aplysia. She was able to identify critical factors both on the presynaptic and the postsynaptic sides of the synapse (Sherff and Carew 2002, 2004). In parallel, another important study was carried out by Kate Reisner, a new graduate student who moved to my group from a purely molecular lab at UCI to dive into neuroscience, and by Joanna Schaffhausen, who came with me from Yale. Kate and Joanna discovered a novel postsynaptic mechanism for the sharing of the critical cation calcium in the induction of short-term plasticity at the synapse (Schaffhausen et al. 2001; Reissner et al. 2010).

Collectively these and other synaptic studies rounded out the three principal levels of analysis (behavioral, synaptic, and molecular) that we routinely used to study learning and memory. Combined, these three levels allowed us to establish a better understanding of the diverse mechanisms used by the nervous system to produce long-term memory.

Growth Factors

A final research program we began at UCI deserves mention. These studies were focused on growth factors, a topic I introduced in discussing our research at Yale. Continuing the rationale that motivated our Yale studies, we became very interested in the possibility that growth factors, in addition to being important during development, might be retained throughout the life of an animal and used (if you will, recycled) in the service of establishing long-term memory. This idea was certainly not novel. For example, the basic notion was suggested in another form by the pioneering Spanish neuroanatomist Santiago Ramón y Cajal, who won the Nobel Prize in 1906.

Tyrosine kinase: A key observation that contributed to this research program was made by Angela Purcell, along with Shiv Sharma, Martha Bagnall, and Mike Sutton. Angela found that an important signaling molecule, tyrosine kinase, along with MAPK, is critically involved in the induction of long-term facilitation in long-term memory (Purcell and Carew 2001; Purcell et al. 2003). It had been well established in other systems before Angela’s work that tyrosine kinases are critical molecular brokers of the actions of growth factors in the nervous system. So Angela and her colleagues opened the door for us to begin to study the actions of growth factors at a molecular level in Aplysia.

Cystine-rich neurotrophic factor: Another critical step in our understanding of growth factors was taken by Lu Pu, a postdoctoral colleague in the lab. Lu cloned and studied a growth factor in Aplysia called cysteine-rich neurotrophic factor (ApCNRF). She found that this growth factor both facilitated the growth of neurons in Aplysia and also activated MAPK during the induction of long-term synaptic facilitation (Pu et al. 2014).

Growth factors in time and space: A final research program focused on the interaction of different growth factors in memory formation in Aplysia was initiated by a graduate student, Ashley Kopec. I will discuss these findings a bit later.

In summary, the analysis of the role of growth factors in memory formation was a central focus in our research program at UCI. The basic idea underlying these studies is that nature never throws anything away. Thus, growth factors, which are critical for building brains in developing animals, appear to be “recycled” or “repurposed” in adult animals in the service of memory formation.

Unexpected Honors along the Way

While at UCI I had three lovely surprises. First, soon after arriving, in 2001 I was delighted to learn that I had been elected as a fellow of the American Association for the Advancement of Science. A few years later, in 2005, I was elected chair of the Neuroscience Section of the AAAS.

Second, I had a real treat in 2004 when I received a phone call one afternoon telling me that I had just been elected to the American Academy of Arts and Sciences. This was both completely unexpected and a genuine honor.

Third, in 2007, I was elected to serve as president of the Society for Neuroscience (SfN). Over the years, I had served on numerous committees and as an elected councilor in the SfN, but being elected as its president was truly an honor. Now it would be disingenuous to say that this truly falls under the heading “unexpected honors,” as I did, indeed, agree to run for the office. Where the “unexpected” part comes in is that I certainly did not expect to win. That said, it sure was fun to receive the phone call from the then-president and my old friend David VanEssen, telling me of the results. My three years in the leadership of the SfN (as incoming president, president, and past president) was a wonderful experience, one that I will always deeply appreciate.

A Call from Tony Movshon

One day in the early spring of 2011, I received a phone call from an old friend, Tony Movshon. Tony is a distinguished faculty member at NYU, where he is a university professor and a Silver Professor, and at the time, was also the director of the University’s Center for Neural Science, which he founded in 1987. He told me that he was on the search committee seeking to fill the position of dean for the Faculty of Arts and Science (FAS) at NYU, and he asked whether I might be interested in applying for the position. The notion of possibly joining NYU in this position was at the same time daunting and exhilarating. So I said that I would be happy to chat with folks at NYU to explore this possibility, at least informally. After a visit or two, and a long and engaging interview with the search committee (consisting of distinguished faculty, university leaders, students, and administrators), I was hooked: This could be a terrific job. And I was fortunate enough to be offered the position. But should I take it?

A little help from my friends: One of the huge attractions of NYU was its central location in the city of New York, which boasts one of the strongest neuroscience communities in the world. In addition, as luck would have it, an old friend from my Yale days, Richard (Dick) Tsien, had very recently joined NYU as the director of the NYU Neuroscience Institute at the NYU Medical Center. I remember calling Dick one snowy evening from Cleveland, Ohio, where I was on a scientific team reviewing the Neuroscience Program at Case Western Reserve. Dick and I chatted for more than an hour. I appreciated his telling me that he was very happy in his new position, and he encouraged me to take the job. The next afternoon, Susan Amara, another old friend from my Yale days (who was on the same review team) and I got snowed in at the Cleveland Airport. Over a beer, Susan strongly encouraged me to take the position, essentially saying, “Take the chance and go for it!” Susan took her own good advice: A couple of years later, she left a leadership position at the University of Pittsburgh to become the Scientific Director of NIMH. Another friend who helped a great deal was Cristina Alberini. Cristina also had been a postdoctoral fellow of Eric Kandel many years earlier, and although we didn’t overlap in Eric’s lab, we had become close friends. Cristina was a professor of neuroscience at Mt. Sinai Medical School, so she was already in New York City—a real plus. She also strongly encouraged me to take the position. Finally, I checked in with my former mentor and friend, Eric Kandel, and he too thought it was a terrific opportunity and encouraged me to accept the job.

So once again, back in California, Mary Jo and I pulled out a good bottle of wine and thought it over. We decided that, indeed, we were we both up for a new adventure. So we packed our bags and headed back east. By now, it must seem that, geographically at least, my career looks a bit like a bicoastal tennis match, with the net somewhere in Kansas.

NYU Redux

One of the important conditions of my move back to NYU as dean was the clear agreement that I would be able to maintain my scientific program. This was in no way a problem, as the NYU leadership at the time, President John Sexton and Provost David McLaughlin, were both very supportive of my keeping an active laboratory. To be sure, I downsized considerably. But I was indeed most fortunate that Ashley Kopec, my graduate student from UCI, decided to come with me in the move to NYU. She was amazing in her energy and high standards: The lab was up and running in no time. In addition, soon thereafter, Gary Philips, my former graduate student from UCI, who had just completed a postdoctoral fellowship, returned to the NYU lab to finish up a long-standing project that was central to our work. Some new colleagues joined us as well. They included another graduate student, Anamaria (Ana) Alexandrescu, and a postdoctoral fellow, Nikolay Kukushkin, who came to us from Harvard. Finally, we were joined by Anastasios (Taso) Mirisis, who initially assumed the role of our lab manager, but now is a full-fledged member of our research team with his own independent project.

In our research program at NYU, we continued two of the major themes that had been the focus of our work for years: One was timing and pattern in the induction of long-term memory, and the other was the role of growth factors in memory formation.

Timing and Pattern in Long-Term Memory

A molecular context: Recall that in his earlier work in the lab at UCI, Gary, along with other colleagues, discovered the importance of a narrow temporal window (45 minutes) that was permissive for producing two-trial long-term memory for sensitization (Philips et al. 2007). Why did the second trial have to arrive exactly in that 45-minute window? In his work begun at UCI and completed at NYU, together with Xiaojing and Ashley, Gary found that the first trial set in motion a chain of events that established a “molecular context” for the second trial to “inherit” at 45 minutes (Philips and Carew 2013). Specifically, the first trial caused (a) the protein synthesis-dependent translocation of activated MAPK into the nucleus of the sensory neurons; (b) the activation of a transcription factor, CREB, that is well known to be critical for long-term memory formation in Aplysia and many other species; and (c) the induction of an immediate early gene in Aplysia, CCAAT/enhancer-binding protein (c/ebp), which is synthesized in response to CREB activation and plays a critical role in long-term facilitation and memory in Aplysia (Philips et al. 2013). These were seminal observations, as they illustrated the complex molecular choreography engaged by different patterns of training trials that ultimately support memory formation.

Growth Factors

Time and space: In discussing our work at UCI, I briefly mentioned the work of a highly creative graduate student, Ashley Kopec, who began her project there and continued it at NYU. Ashley was interested in the general question: Might different growth factors play different roles in the induction of long-term memory? The foundation of this question was as follows. Several growth factors have been implicated in long-term memory, but no single factor can support all of the plastic changes that occur during memory formation. Because growth factors engage highly convergent signaling cascades that often mediate similar functional outcomes, the relative contribution of any particular one to long-term memory is difficult to ascertain. To explore this question, Ashley determined the unique contribution to memory formation of two distinct growth factor families: one signaling via tropomyosin receptor kinase B (TrkB) and the other via transforming growth factor beta (TGF-beta).

Ashley found that TrkB and TGF-beta signaling are differentially recruited during two-trial training in both time (by trial 1 or 2, respectively) and space (in distinct subcellular compartments). These growth factors independently regulate MAPK activation and synergistically regulate gene expression. She also showed that both trial 1 TrkB and trial 2 TGF-beta signaling are required behaviorally for memory formation (Kopec et al. 2015). Specifically, Ashley found that the immediate early gene c/ebp is upregulated in sensory neurons in a TrkB signaling-dependent manner by the first trial, and these nascent transcripts are subsequently stabilized by a TGF-beta signaling-dependent mechanism following the second trial. These data are highly instructive, as they support the view that growth factors engaged in memory formation are interactive components of a complex molecular network (Kopec and Carew 2013).

ELAV: In light of the findings just described, that distinct growth factor families are recruited in unique spatial and temporal domains during the induction of long-term memory, we next explored the critical mechanisms and cellular processes that are dependent on this coordinated signaling system. Taso Mirisis, an important member of the lab, together with Ashley, has taken on this task. As mentioned earlier, the immediate early gene c/ebp is upregulated by a single training trial, and these new mRNA transcripts then are stabilized by a TGF-beta signaling-dependent mechanism following the second trial (Kopec et al. 2015). A bit of background: a specific region of the mRNA for c/ebp contains AU-rich elements (AREs), which function as binding sites for RNA-binding proteins, which modulate the stability of their target transcripts. A well-described member of a family of such binding proteins (ELAV), binds to ARE-containing transcripts and increases their longevity by (a) hindering the ability of destabilizing proteins to bind to the AREs, and (b) shielding the mRNA from degradation. Taso’s preliminary studies have implicated the coordinated binding of an Aplysia ELAV-like protein to c/ebp transcript as a prerequisite of long-term memory formation. Why is this important? The novel possibility that growth factor–mediated regulation of mRNA transcripts can be critical for the induction of long-term memory significantly broadens the horizon of possible molecular mechanisms that are deployed in neurons to form lasting memories.

Cystine-rich neurotrophic factor (ApCNRF): Another avenue of investigation of growth factors in the lab is being carried out by a thoughtful and dedicated graduate student, Ana Alexandrescu, whose work is building on our earlier findings that ApCNRF both facilitated the growth of neurons, and activated MAPK, during the induction of long-term synaptic facilitation (Pu et al. 2014). In extending this work at NYU, Ana is exploring mechanistically the spatial contribution of ApCNRF signaling at the sensory-motor synapse during the induction of long-term synaptic facilitation. Ana has already shown that ApCRNF is expressed in both the sensory and motor neurons. She is now exploring its mechanisms of action in both these pre- and postsynaptic compartments by taking advantage of the high spatial resolution of the sensory-motor neuron coculture system that was first developed in the Kandel lab many years ago and is widely used in the Aplysia community. Considerable evidence indicates that synaptic activity regulates the synthesis, secretion, and signaling of growth factors, which in turn can induce changes in synaptic efficacy and morphology to support long-term memory formation. Ana’s experiments are examining the cellular sites of ApCNRF synthesis, release, and actions during the induction of synaptic plasticity, using the monosynaptic “microcircuit” of sensory neurons connected to motor neurons in culture. Why is this important? This detailed analysis of a well-identified microcircuit, of known behavioral relevance, can significantly contribute to our understanding of how secreted molecules like growth factors are tightly regulated specifically and locally in the synaptic compartment during the induction of a long-term memory.

Insulin signaling: A final component of the growth factor research program in our laboratory is the province of a postdoctoral colleague, Nikolay (Niko) Kukushkin. Niko initiated a research program exploring the growth factor insulin, and his results are already highly informative. Specifically, Niko was interested in the fact that insulin-like signaling is ubiquitous in virtually all animals, but its role in the nervous system is largely unexplored. A critical exception is the recent work of my friend and colleague Cristina Alberini, who by the way, we were fortunate enough to recruit to NYU soon after I arrived. With her colleagues, Cristina identified an insulin-like growth factor (IGF2) that serves a critical role in memory consolidation and, in addition, is a molecule that can act as a potent memory enhancer (Chen et al. 2011).

Niko’s work has two focal points. The first is the insulin system itself. He shows conclusively that Aplysia not only possesses insulin-like receptors and ligands related to their mammalian counterparts but also exerts effects reminiscent of a “hybrid” insulin/insulin-like growth factor functionality: on the one hand, control of metabolism; on other hand, stimulation of growth. The second focal point Niko’s work examines is the neuromodulatory effects of insulin-like signaling. As a model system, Aplysia is most useful for studying neural phenomena at multiple levels of analysis, from molecular to behavioral. In his work, Niko has obtained evidence that implicate the Aplysia insulin-like system in a variety of effects that reveal a common theme across these levels: decreased activity and excitability in response to nutrition. Because these effects range from tyrosine dephosphorylation and reduced neuronal excitability to reduced locomotor activity of the fed animals, they paint a clear picture of a systemic, coordinated “rest-and-digest” response directly controlled by insulin-like peptides.

Ending on a theoretical note: “Memory takes time.” A final recent theoretical piece from the lab deserves brief mention. Niko and I had great fun recently writing a theoretical review (Kukushkin and Carew 2017), in which we consider the temporal structure of memory. We suggest that memory is an adaptation to particular temporal properties of a past event. In neurons, this adaptation can be understood in terms of a hierarchical system of molecular and cellular time windows, which collectively retain information from the past. We propose that this system makes various timescales of past experience simultaneously available for future adjustment of behavior.

The basic theoretical notion we advance is this: Memory is represented in the brain much like a “Fourier transform of experience.” Just as sound is broken down by the auditory system into many discrete bins of frequencies that are perceived simultaneously, Niko and I suggest that an experience as a whole is parsed by the brain into many “time windows” that collectively represent the past. Most memories last seconds before they are forgotten, but some last a lifetime, and yet at each given moment both kinds of memory coexist with ongoing experiences on the same terms. For example, a familiar musical piece is experienced simultaneously through the short-term memory of the few notes just heard and the long-term memory of listening to the piece in the past. Both retain information about the past and both shape perception in the present.

Being a Dean

Soon after I took the job as dean of FAS at NYU, many of my science colleagues would ask me: “What’s it like being a dean?” The question was always quite polite, but often was asked as if I had just moved to another solar system, and they wondered what the weather was like there.

It’s a big job: Now, indeed, being dean of the largest School at NYU, the FAS, is no small undertaking. There are about 1,000 faculty, 13,000 students, and in excess of 400 staff in the School. Moreover, the FAS spans a broad range of disciplines, which include the humanities, the social sciences, and the sciences. In addition, there are numerous institutes, centers, and programs with extremely diverse interests and goals. So it’s a complex academic landscape, indeed.

It’s a fun job: There are three things that I especially enjoy about being a dean of such a large and complex enterprise. First, I am extremely fortunate to have an amazing staff. These colleagues have, as their daily jobs, the management of matters ranging from budgets, to faculty hiring, to human resources, to overseeing physical facilities, to making sure that the dean’s office is an efficient and collegial operation. Another group of colleagues within the FAS who also make a huge difference are the three divisional deans (who attend to the humanities, social sciences, and sciences, respectively), the dean of the college, and the dean of the graduate school. All six of us work together as a coordinated team to ensure that the School stays on course.

The second source of great satisfaction is the extraordinary intellectual reach of the job. In a single day in my office, I will be visited by a poet, then a physicist, and then an historian. Typically, these colleagues want to discuss a proposal they have in mind or perhaps a new hire for their department. But I have (a bit playfully) put in place a modest “intellectual tax” for any visit. Before the colleague discusses the actual purpose of his or her visit, I ask that they spend 5–10 minutes telling me about their own scholarly work. Thus, I am privileged to have the opportunity, on a daily basis, for an ongoing tutorial across an amazing intellectual landscape.

The third extremely rewarding aspect of the position is the ability to actually contribute to making a difference in higher education, through the lens of NYU. There are enormous challenges to be sure. Let me highlight just two. First is the critical importance of increasing diversity, inclusion, and equity across all levels of the university, from faculty and students to administrators and staff. A second pressing concern is affordability. There are simply way too many extremely qualified students across the nation and around the globe who cannot afford to go to college. Both of these are of the highest priority in the FAS at NYU. And although there are absolutely no simple quick-fix answers to these complex and critical issues, having the chance to work with faculty, students, and administrators in addressing them is, in and of itself, extremely rewarding.

A few trade-offs: There are, indeed, trade-offs in being a dean. I cannot spend nearly enough time in my laboratory to give my research team the attention they fully deserve. Another trade-off is that being a dean limits the extent of my contact with undergraduates. I still teach an advanced undergraduate course in molecular mechanisms of memory each year, but this brings me into contact with only a modest cohort of students. Nonetheless, while the number of students I teach is certainly reduced at NYU, their curiosity and boundless energy remains a great source of satisfaction.

Coming full circle: So, here I am, having come full circle professionally from NYU, to Columbia Medical School, to Yale, to UCI, and back to NYU. Each of these institutions has afforded me the opportunity for exceptional professional and personal growth. And over these years, the very best part are the amazing friends and colleagues who have come my way. They make it all worthwhile.

Epilogue

No mom, I haven’t finished my experiment yet.

References

Bunge, S.A., Mauelshagen, J., and Carew, T.J., (1997) Reversal of relative thresholds for synaptic facilitation and increased excitability induced by serotonin and tail nerve stimulation in Aplysia sensory neurons. Neurobiol. Learning and Memory 67, 259–263.

Carew, T.J. (1970) Do passive avoidance tasks permit assessment of retrograde amnesia in the rat? J. Comparative and Physiological Psychology 72, 267–271.

Carew, T.J. (1989) Developmental assembly of learning in Aplysia. Trends in Neuroscience 12, 389–394.

Carew, T.J. (2000) Behavioral Neurobiology: The Cellular Organization of Natural Behavior. Sunderland, MA: Sinauer Associates Inc.

Carew, T.J., Castellucci, V., and Kandel, E.R. (1979) Sensitization in Aplysia: Rapid restoration of transmission in synapses inactivated by long-term habituation. Science 205, 417–419.

Carew, T.J., Crow, T., and Petrinovich, L. (1970) Lack of coincidence between neural and behavioral manifestations of cortical spreading depression (CSD). Science 169, 1339–1342.

Carew, T.J., Hawkins, R.D., and Kandel, E.R. (1983) Differential classical conditioning of a defensive withdrawal reflex in Aplysia. Science 219, 397–400.

Carew, T.J. and Kandel, E.R. (1973) Acquisition and retention of long-term habituation: Correlation of behavioral and cellular processes. Science 182, 1158–1160.

Carew, T.J., Pinsker, H., and Kandel, E.R. (1972) Long-term habituation of a defensive withdrawal reflex in Aplysia. Science 175, 451–454.

Carew, T.J., Walters, E.T., and Kandel, E.R. (1981) Associative learning in Aplysia: Cellular correlates supporting a conditioned fear hypothesis. Science 211, 501–504.

Castellucci, V., Carew, T.J., and Kandel, E.R. (1978) Cellular analysis of long-term habituation in the gill-withdrawal reflex of Aplysia californica. Science 202, 1306–1308.

Castellucci, V., Pinsker, H. Kupfermann, I., and Kandel, E.R. (1970) Neuronal mechanisms of habituation and dishabituation of the gill-withdrawal reflex in Aplysia. Science 167, 1743–1745.

Chen, D.Y., Stern, S.A., Garcia-Osta, A., Saunier-Rebori, B., Pollonini, G., Bambah-Mukku, D., Blitzer, R.D., and Alberini, C.M. (2011) A critical role for IFG-II in memory consolidation and enhancement. Nature 469, 491–497.

Cook, D.G. and Carew, T.J. (1986) Operant conditioning of head-waving in Aplysia. Proc. Natl. Acad. Sci. 83, 1120–1124.

Cook, D.G. and Carew, T.J. (1989a) Operant conditioning of head-waving in Aplysia I: Identified muscles involved in the operant response. J. Neurosci. 9, 3097–3106.

Cook, D.G. and Carew, T.J. (1989b) Operant conditioning of head-waving in Aplysia II: contingent modification of electromyographic activity in identified muscles. J. Neurosci. 9, 3107–3114.

Cook, D.G. and Carew, T.J. (1989) Operant conditioning of head-waving in Aplysia III: Cellular analysis of possible reinforcement pathways in Aplysia. J. Neurosci. 9, 3115–3122.

Cook, D.G., Stopfer, M., and Carew, T.J. (1991) Identification of the neural pathway mediation reinforcement in operant conditioning of head-waving in Aplysia. Behav. Neural. Biology 55, 313–337.

Ebbinghaus, H. (1885) Memory: A Contribution to Experimental Psychology. New York: Dover.

Emptage, N.J. and Carew, T.J. (1993) Long-term synaptic facilitation in the absence of short-term facilitation in Aplysia sensory neurons. Science 262, 253–256.

Fischer, T.M., Blazis, D.E., Priver, N.A., and Carew, T.J. (1997) Metaplasticity at identified synapses in Aplysia. Nature 389, 860–865.

Fischer, T. and Carew, T.J. (1995a) Cutaneous activation of inhibitory L30 interneuron provides a mechanism for regulating adaptive gain control in the siphon withdrawal reflex of Aplysia. J. Neurosci. 15, 762–773.

Fischer, T. and Carew, T.J. (1995b) Cutaneous activation of inhibitory L30 interneuron provides a mechanism for regulating adaptive gain control in the siphon withdrawal reflex of Aplysia. J. Neurosci. 15, 762–773.

Fischer, T.M., Yuan, J.W., and Carew, T.J. (2000) Dynamic regulation of the siphon withdrawal reflex of Aplysia in response to changes in the ambient tactile environment. Behav. Neurosci. 114, 1209–1222.

Fischer, T.M., Zucker, R.S., and Carew, T.J. (1997) Activity-dependent potentiation of synaptic transmission from L30 inhibitory interneurons of Aplysia depends upon residual presynaptic calcium but not on post synaptic calcium, J. Neurophysiol. 78, 2061–2071.

Gruenbaum, L. and Carew, T.J. (1999) Growth factor modulation of substrate-specific morphological patterns in Aplysia bag cell neurons. Learning and Memory 6, 292–306.

Hawkins, R.D., Abrams, T.W., Carew, T.J., and Kandel, E.R. (1983) A cellular mechanism of classical conditioning in Aplysia: Activity-dependent amplification of presynaptic facilitation. Science 219, 400–405.

Kandel, E.R., Kriegstein, A., and Schacher, S. (1980) Development of the central nervous system of Aplysia in terms of the differentiation of its specific identifiable cells. Neuroscience 5, 2033–2063.

Kopec, A.M., and Carew, T.J. (2013) Growth factor signaling and memory formation: temporal and spatial integration of a molecular network. Learning and Memory 10, 531–539.

Kopec, A.M., Philips, G.T., and Carew, T.J. (2015) Distinct growth factor families are recruited in unique spatiotemporal domains during long-term memory formation in Aplysia californica. Neuron 86, 1228–1239.

Kriegstein, A.R., Castellucci, V., and Kandel, E.R. (1974) Metamorphosis of Aplysia californica in laboratory culture. Proc. Natl. Acad. Sci. 71, 3654–3658.

Kukushkin, N.V. and Carew, T.J. (2017) Memory takes time. Neuron 95, 259–279.

Kupfermann, I., Castellucci, V., Pinsker, H., Kandel, E. (1970) Neuronal correlates of habituation and dishabituation of the gill-withdrawal reflex in Aplysia. Science 167, 1743–1745.

Marcus, E.A. and Carew, T.J. (1998) Developmental emergence of different forms of neuromodulation in Aplysia sensory neurons. Proc. Nat. Acad. Sci. 95, 4726–4731.

Marcus, E.A., Nolen, T.G., Rankin, C.H., and Carew, T.J. (1988a) Behavioral dissociation of dishabituation, sensitization, and inhibition in Aplysia. Science 241, 210–213.

Marcus, E.A., Nolen, T.G., Rankin, C.H., Stopfer, M., and Carew, T.J. (1988b) Development of behavior and learning in Aplysia. Experientia 44, 415–423.

Marinesco, S., and Carew T.J. (2002a) Improved electrochemical detection of biogenic amines in Aplysia using base-hydrolyzed cellulose-coated carbon fiber microelectrodes. J. Neurosci. Meth. 117, 87–97.

Marinesco, S. and Carew, T.J. (2002b) Serotonin release evoked by tail-nerve stimulation in the central nervous system of Aplysia: Characterization and relationship to heterosynaptic plasticity. J. Neurosci. 22, 2299–2312.

Marois, R. and Carew, T.J. (1997a) Ontogeny of serotonergic neurons in Aplysia californica. J. Comp. Neurol. 386, 477–490.

Marois, R. and Carew, T.J. (1997b) Projection patterns and developmental functions of serotonergic cells in larval Aplysia californica. J. Comp. Neurol. 386, 491–506.

Marois, R. and Carew, T.J. (1997c) Fine structure of the apical ganglion and its serotonergic cells in the larva of Aplysia californica. Biol. Bull. 192, 388–398.

Mauleshagen, J., Parker, G., and Carew, T.J. (1996) Dynamics of induction and expression of long term synaptic facilitation in Aplysia. J. Neurosci. 16, 7099–7108.

Mauelshagen, J., Sherff, C. M., and Carew, T.J. (1998) Differential induction of long-term synaptic facilitation by massed and spaced application of serotonin in Aplysia sensory neurons. Learning and Memory 5, 246–256.

McKay, S.E, Purcell, A. L., and Carew, T.J. (1999) The regulation of synaptic function by neurotrophic factors in vertebrates and invertebrates: Implications for development and learning. Learning and Memory 6, 193–215.

Mercer, A.R., Emptage, N.E., and Carew, T.J. (1991) Pharmacological dissociation of modulatory effects of serotonin in Aplysia sensory neurons. Science 254, 1811–1813.

Mueller, U. and Carew, T.J. (1998) Serotonin induces temporally and mechanistically distinct phases of persistent PKA activity in Aplysia sensory neurons. Neuron 21, 1423–1434.

Nolen, T.G., Marcus, E., and Carew, T.J (1987) Development of learning and memory in Aplysia: III. Central neuronal correlates. J. Neurosci. 7, 144–153.

Nolen, T.G. and Carew, T.J. (1988) A cellular analog of sensitization emerges at the same time in development as behavioral sensitization in Aplysia. J. Neurosci. 8, 212–222.

Philips, G.T. and Carew, T.J. (2013) Pattern and predictability in memory formation: From molecular mechanisms to clinical relevance. Neurobiol. Learning and Memory 105, 117–124.

Philips, G.T., Tzvetkova, E.I., and Carew, T.J. (2007) Transient mitogen-activated protein kinase activation is confined to a narrow temporal window required for the induction of two-trial long-term memory in Aplysia. J Neurosci. 50, 13701–13705.

Philips, G.T., Ye, X, Kopec, A., and Carew, T.J. (2013) MAPK establishes a molecular context that defines effective training patterns for long-term memory formation. J. Neurosci. 33, 7565–7573.

Pinsker, H., Carew, T.J., Hening, W., and Kandel, E.R. (1973) Long-term sensitization of a defensive withdrawal reflex in Aplysia californica. Science 182, 1039–1042.

Pinsker, H., Kupfermann, I., Castellucci, V., and Kandel, E.R. (1970) Habituation and dishabituation of the gill-withdrawal reflex in Aplysia. Science 167, 1740–1742.

Pu, l., Kopec, A.M., Boyle, H.D., and Carew, T.J. (2014) A novel cysteine-rich neurotrophic factor in Aplysia facilitates growth, MAPK activation, and long-term synaptic facilitation. Learning and Memory 4, 215–222.

Purcell, A.L. and Carew, T.J. (2001) Tyrosine kinases modulate serotonin-induced excitability Aplysia sensory neurons. J. Neurophysiol. 85, 2398–2411.

Purcell, A.L., Sharma, S.K., Bagnall, M.W., Sutton, M.A., and Carew, T.J. (2003) Activation of a tyrosine kinase-MAP kinase cascade facilitates the induction of long-term synaptic facilitation and long-term memory in Aplysia. Neuron 37, 473–484.

Rankin, C.H. and Carew, T.J. (1987) Development of learning and memory in Aplysia: II. Habituation and Dishabituation. J. Neurosci. 7, 133–143.

Rankin, C.H. and Carew, T.J. (1988) Dishabituation and sensitization emerge as separate processes during development in Aplysia. J. Neurosci. 8, 197–211.

Rankin, C.H. and Carew, T.J. (1989) Developmental analysis in Aplysia reveals inhibitory as well as facilitatory effects of tail shock. Behav. Neurosci. 103, 334–344.

Rankin, C.H., Stopfer, M., Marcus, E.A., and Carew, T.J. (1987) Development of learning and memory in Aplysia: I. Functional assembly of the gill and siphon withdrawal reflex. J. Neurosci. 7, 120–132.

Rayport, S.G. and Kandel, E.R. (1986) Development of plastic mechanisms related to learning at identified chemical synaptic connections in Aplysia. Neuroscience 17, 283–294.

Reissner, K.J., Pu, L., Schaffhausen, J.H., Boyle, H.D., Smith, I.F., Parker, I., and Carew, T.J. (2010) A novel postsynaptic mechanism for heterosynaptic sharing of short-term plasticity. J. Neurosci. 30, 8797–8806.

Schaffhausen, J.H., Fischer, T.M., and Carew, T.J (2001) Contribution of postsynaptic Ca2+ to circuit for siphon withdrawal in Aplysia. J. Neurosci. 21, 1739–1749.

Sharma, S.K. and Carew, T.J. (2004) The roles of MAPK cascades in synaptic plasticity and memory in Aplysia: facilitatory effects and inhibitory constraints. Learning and Memory 11, 373–378.

Sharma, S.K., Sherff, C.M., Bagnall, M.W., Sutton, M.A., and Carew, T.J. (2003a) Differential role of mitogen-activated protein kinase in three distinct phases of memory for sensitization in Aplysia. J. Neurosci. 23, 3899–3907.

Sharma, S.K., Bagnall, M.W., and Carew, T.J. (2003b) Inhibition of calcineurin facilitates the induction of intermediate-term and long-term memory for sensitization in Aplysia: requirement of mitogen activated protein kinase. Proc. Natl. Acad. Sci. 100, 4861–4866.

Sherff, C.M. and Carew, T. J. (1999) Coincident induction of long-term facilitation in Aplysia: Cooperativity between cell bodies and remote synapses. Science 285, 1911–1914.

Sherff, C.M. and Carew, T.J. (2004) Parallel somatic and synaptic processing in the induction of intermediate-term and long-term synaptic facilitation in Aplysia. Proc. Natl. Acad. Sci. 101, 7463–7468.

Sherff, C.M. and Carew, T.J. (2002) Coincident induction of long-term facilitation at sensory-motor synapses in Aplysia: Presynaptic and postsynaptic factors. Neurobiol. Learning and Memory 78, 498–507.

Shobe, J., Zhao, Y., Ye, X., Stough,, S., Martin, K., and Carew, T.J. (2009) Temporal phases of activity-dependent plasticity and memory are mediated by compartmentalized routing of MAPK signaling in Aplysia sensory neurons. Neuron 61, 113–125.

Stark, L.L. and Carew, T.J. (1999) Developmental dissociation of serotonin-induced spike broadening and synaptic facilitation in Aplysia sensory neurons. J. Neurosci. 19, 334–346.

Stopfer, M. and Carew, T.J. (1988) Development of sensitization of escape locomotion in Aplysia. J. Neurosci. 8, 223–230.

Sutton, M.A. and Carew, T.J. (2000) Parallel molecular pathways mediate the expression of distinct forms of intermediate-term facilitation at tail sensory-motor synapses in Aplysia. Neuron 26, 219–232.

Sutton, M.A., Bagnall, MW, Sharma, SK, Shobe, J., and Carew, T.J. (2004) Intermediate-term memory for site-specific sensitization in Aplysia is maintained by persistent activation of protein kinase C. J. Neurosci. 24, 3600–3609.

Sutton, M.A., Ide, J., Masters, S.E., and Carew, T.J., (2002) Interaction between amount and pattern of training in the induction of intermediate- and long-term memory for sensitization in Aplysia. Learning and Memory 9, 29–40.

Sutton, M.A., Masters, S.E., Bagnall, M.W., and Carew, T.J. (2001) Molecular mechanisms underlying a unique intermediate phase of memory in Aplysia. Neuron 31, 143–154.

Walters, E.T. and Byrne, J.H. (1983) Associative conditioning of single sensory neurons suggests a cellular mechanism for learning. Science 219, 405–408.

Walters, E.T., Carew, T.J., and Kandel, E.R. (1979) Associative learning in Aplysia californica. Proc. Natl. Acad. Sci. 76, 6675–6679.

Walters, E.T., Carew, T.J., and Kandel, E.R. (1981) Associative learning in Aplysia: Evidence for conditioned fear in an invertebrate. Science 211, 504–506.

Ye, X., Shobe, J.L., Sharma, S.K., Marina, A., and Carew, T.J. (2008) Small G proteins exhibit pattern sensitivity in MAPK activation during the induction memory and synaptic facilitation in Aplysia. Proc. Natl. Acad. Sci. 51, 2051–2056.

Dennis W. Choi

BORN:

Michigan, 1953

EDUCATION:

Harvard College, Cambridge, MA, AB (1974)

Harvard Medical School (Harvard-MIT Health Sciences and Technology Program), MD (1978)

Harvard University, PhD (1978)

APPOINTMENTS:

Assistant-Associate Professor of Neurology, Stanford University School of Medicine (1983–1991)

Andrew B. and Gretchen P. Jones Professor and Head of Neurology, Washington University Medical School (1991–2001)

Executive Vice President, Neuroscience, Merck Research Labs (2001–2006)

Professor of Pharmacology & Experimental Therapeutics, Boston University (2006–2007)

Professor of Neurology, Pharmacology, and Pediatrics, Emory University (2007–2012)

Director, Brain Science Institute, Korea Institute of Science and Technology (2013–2016)

Professor and Chair of Neurology, SUNY Stony Brook (2012–present)

HONORS AND AWARDS (SELECTED)

Wakeman Award for Neuroscience Research (1992)

Silvio O. Conte Decade of the Brain Award, National Foundation for Brain Research (1994)

Vice-President, American Neurological Association (1996–1997)

Ho-Am Prize in Medical Science, Samsung Foundation (1997)

Christopher Reeve Research Medal (1998)

President, Society for Neuroscience (1999–2000)

Santiago Grisolia Prize (2000)

Member, National Academy of Medicine (2000)

Fellow, American Association for the Advancement of Science (2005)

As a graduate student, Choi discovered the mechanism of action of benzodiazepine drugs, demonstrating potentiation of gamma-aminobutyric acid responses, a key early example of a modulatory rather than agonist or antagonist action at a neurotransmitter receptor. Later as a faculty member at Stanford and Washington University, he initiated systematic studies of insult-induced neuronal death, establishing the utility of primary neuronal cell cultures in identifying underlying mechanisms and contributing to the emergence of therapeutic neuroprotection as a field. Much of his early work focused on excitotoxicity and calcium overload; later his laboratory added study of inappropriate apoptosis and disturbances in the homeostasis of other ions, including zinc and potassium.

Dennis W. Choi

Early Life (1950s–1970s)

I had a happy, albeit in retrospect, odd childhood, notable for a disconnect between expectation and privilege, and entirely too little adult supervision. My parents were immigrants from Korea and China, fortunate in being able to come to America with a small stake that allowed my father to attend a U.S. college. They met while working for U.S. intelligence in postwar Japan as translators, a service that facilitated their immigration.

They both came from highly political families. My paternal grandfather was a young founder of the current Republic of Korea, a member of the Provisional Government in exile that formed in 1919 in Shanghai to resist Japanese colonial rule of Korea. Unfortunately, he was captured and his health broken in a Japanese prison, but he did meet my grandmother (“Florence”) in Shanghai. Florence was a fiercely independent woman who learned of the existence of this organization while in high school, and later traveled alone over land to join up—dressing as a man for the hazardous journey and couriering smuggled documents for the resistance. In a formal photograph that I have of Ahn Changho and other Provisional Government officials, including my grandfather, she is one of only two women and she is seated in the front row. My maternal grandfather was a classically educated scholar who served as chief secretary in the Republic of China government under Chiang Kai-shek, prior to Mao Tse-Tung’s Communist revolution. Before that, he was a provincial governor (Kweichow), a banker, and a publisher who led the Ta Kung Pao newspaper in Tientsin to prominence (it is the oldest active Chinese language newspaper in China today).

I was born in Michigan, and unfortunately for me, my parents made a strategic decision to speak only English at home, rendering me embarrassingly monolingual. My father, fluent in five languages, moved us to a working-class neighborhood in the Boston area while he earned a PhD in mechanical engineering at MIT and joined the faculty at Tufts University. I have early memories of being fascinated by the heavy equipment in his heat transfer laboratory and admiring the precision of his thinking. He also gave me chemistry sets as birthday presents beginning when I was in first grade, launching the Chemistry Phase of my young scientific career.

Initially my experiments consisted of mixing supplied chemicals together in various combinations to see whether anything interesting would happen (of course it never did), but a few years later, I read about the composition of explosives and acquired a mail-order catalog from a professional chemistry supply house. I first ordered a few beakers, and then, in that more innocent time, had no difficulty ordering kilogram quantities of explosive ingredients, including finely powdered metals. By then my father had departed my life to pursue a career in global industrial consulting, and my mother ignored whatever I was doing up in my bedroom “laboratory.” My best friend Dougie, from down the street, however, was thoroughly impressed, and we made an ever-larger series of aluminum foil-wrapped flares which we gleefully set off in backyards and driveways, at one point melting a good-size hole in the asphalt. We had just enough sense to not pack our explosives, so we retained fingers and internal organs for later use. The pinnacle of my Chemistry Phase came in sixth grade, when I saw an ad in the back of my favorite magazine (Popular Mechanics) that offered to sell instructions for making a “powerful contact explosive from household supplies” for $2 in cash. Who could resist? The resultant explosive worked but barely crackled. Reasoning that ingredient purity needed to be upgraded, I visited a local compounding pharmacy and negotiated for a bottle of crystals (handed across the counter with a raised eyebrow) in exchange for delivering some packages on my bicycle. The next batches were epic. But our unwise decision to booby-trap a light switch in Dougie’s house (in his kid sister’s bedroom, just a trace/crackle) sent her into tears and led to us being told by his parents that our chemistry careers were now over.

I was ready to move on anyway, having been given a last science kit from my father that focused on electric circuits. I read up on electronics, and set up a shop in my basement, stocked with parts salvaged from discarded television sets and some amazing military equipment obtained at a local junkyard at scrap metal prices. The Electricity Phase of my career coincided with a major upgrade in my schooling, courtesy of grandmother Florence. While my parents always assumed implicitly that I would become an educated man, being raised by a single mother on an office clerk’s salary left the actual path forward to higher education unclear. The span of my world then was limited to the travel radius of my bicycle, and other boys in the neighborhood were aspiring to become auto mechanics, which seemed to me a pretty good line of work. Grandmother Florence had come to live with us, however, bonding with my mother. She was ever doing things: networking with the Boston Korean community, volunteering with the Red Cross, figuring out America. She would tell stories from her large past life, and assure me that I could do anything if I worked at it. When she learned somehow that a private school in Cambridge was looking to diversify its student body, she hopped a bus down and pitched my case. Next thing I knew, I was riding the same bus daily to seventh grade to the Browne & Nichols (B&N) School on a full scholarship.

B&N was good to me, exposing me to a previously unsuspected palette of ideas, horizons, and topics, including Latin and Moby Dick. Their charismatic head science teacher, “Doc” Walters, encouraged me with wry humor and a special science prize when I graduated. I developed plans to study electrical engineering, applying to MIT and two other engineering schools; but I also enjoyed the humanities and had advanced placement in English, so I decided to apply additionally to Harvard and Brown. To my delight, I was accepted by both Ivies. I entered Harvard College before I turned 17, supported by enough scholarship and loans to leave the neighborhood and live in a dorm.

I started on an engineering track, taking math and physics courses and landing my first paid electrical jobs: during the school year, soldering circuit boards for a kind psychology professor, Marshall Haith; and summers, working as a studio technician at the Boston NBC affiliate, WBZ-TV. The latter unusual opportunity came my way again through the mysterious networking of grandmother Florence. I was useful to WBZ because I had obtained a federal first-class commercial radio license through self-study (only passing a written examination was required), and thus, I could be designated the official television transmitter operator when needed. The work was great fun, although I still recall vividly an error I made in the air-switcher room, rewinding an active tape and causing Rex Trailer, a children’s show cowboy, to ride his horse fast backward one Saturday morning. Meanwhile, on the side, I satisfied my latent auto mechanic, buying and repairing a series of cheap cars and motorcycles for practical transportation. A hometown buddy, Chet, gifted me with a Yamaha two-cycle motorcycle whose transmission he had blown. I found only one gear unusable, and purchased a replacement from a salvage shop for $10. After patching the gear-case, the Yamaha was my noisy but dependable ride for several years.

I began to have second thoughts about majoring in electrical engineering during my college sophomore year, wondering whether I might rather study something with less definition and more conceptual breadth. A memorable course on Greek drama built around sonorous readings by “the Professor” William Alfred had me thinking sophomore thoughts about the human spirit and mind. Also, my roommate, Dan Weitekamp, had declared a biochemistry major and seemed to have interesting assignments. So I also declared a biochemistry major, choosing it over biology because the former, smaller department offered individual attention to its undergraduates, assigning to each a “tutor” charged with overseeing progress. I figured that having some extra help available might help me catch up.

This was an inspired decision. I lucked out in being assigned Barbara Talamo as my tutor, who was then a postdoc at the medical school, and would go on to found and chair the Neuroscience Department at Tufts School of Medicine. With skill and patience, she led me through some remedial readings in a biology textbook, and then had me read, chapter-by-chapter, the book Nerve, Muscle, and Synapse by Bernard Katz. That book, illuminated by Barbara’s sharp insights, brought it together for me, tying electric circuit behavior to nervous system signal processing. I then successfully sought permission to take two graduate-level seminar courses in neuroscience at the medical school, one on synaptic physiology, taught by Jack McMahan and Rami Rahamimoff; the other on the visual system, taught by David Hubel and Torsten Wiesel. These were the best courses I have ever taken, and I recall being awed by the faculty and trainees in the Neurobiology Department, the latter including Carla Shatz, David Van Essen, Jim Hudspeth, and Josh Sanes.

I began to plan to attend graduate school in neuroscience. However, I had not gotten far when a singular opportunity came my way. Harvard and MIT, often rivals on opposite sides of Cambridge, Massachusetts, had decided to collaborate on the launch of a medical training program, the Harvard-MIT Program in Health Sciences and Technology (HST). The program combined medical training at Harvard with an expanded exploration of related engineering topics at MIT. Since the program, with 25 MD training slots per year, was just getting going and did not yet have full national visibility, the HST director, Irving London, decided to reach out proactively to selected MIT and Harvard undergraduates to offer them positions. My engineering to biology path, likely coupled with my missionary enthusiasm for neuroscience, brought me to his attention, and I was offered a position contingent on entering directly after my college junior year and completing college concurrently the following year.

I had not seriously considered medicine as a career at that point. There were few Asian students or faculty in U.S. medical schools in those days, and my mother opined that Asian physicians would not be accepted by sizeable segments of the American public. Hopefully, her viewpoint will seem parochial to most today, but America has come a long way to overcome old biases (and still has a way to go). When my parents bought their small Boston-area house, their future neighbors held a meeting to decide whether they could accept the situation. Fortunately, the decision was yes.

Anyway, medicine felt just right to me. I saw it as the engineering side of biology, and admired its humanism. And Dr. London’s offer would save me time and expense, allowing me to live as an undergraduate in a college dorm and even take a literature course during my first HST year. So, deal.

Training (1970s–1980s)

HST was grueling, with an unfashionably large number of lecture hours, yet rewarding, with unexpected insights served up regularly by a talented faculty. I recall modeling the human body as an inverse pendulum (very unstable without continuous neuromuscular adjustments) and Farish Jenkins climbing on a table to demonstrate how the arthropod gait differed from the primate gait. Walle Nauta, a founding member of the Society for Neuroscience (SfN), taught us neuroanatomy, regaling us one day about the time he saved a soldier’s life in World War II by drilling a hole in the man’s skull on a kitchen table and relieving an expanding hematoma.

As the first two years of medical school progressed, I wondered whether I could still gain neuroscientific training. Barbara Talamo encouraged me, and tried to get me a summer position with Steve Kuffler, the head of Harvard’s Neurobiology Department, but his lab was not accepting students. She then successfully recommended me to Gerry Fischbach, who had recently come from the National Institutes of Health (NIH) to join the Pharmacology Department. I found Gerry’s ideas and approaches inspiring, and decided to interrupt my medical training to study for a PhD with him. Back then, the MD-PhD program was a background administrative entity. One simply finished when one met each degree’s separate requirements, often after seven or eight years of study.

My first project leveraged the chick neuronal cell culture system that Gerry and others had pioneered at NIH. I was assigned to study the chemosensitivity of dorsal root ganglion (DRG) cells to gamma-aminobutyric acid (GABA), which by the early 1970s had become recognized as a major vertebrate inhibitory neurotransmitter, specifically implicated in inhibiting sensory afferents into the spinal cord. I would record from DRG neurons with a sharp intracellular pipette, while iontophoresing GABA from a nearby extracellular pipette. The iontophoretic pipette contained 1M GABA, buffered to pH 4, so it would be charged and ejected by positive current pulses. I quickly obtained strong membrane responses and embarked on characterizing these. After several months’ work and beginning to plan my thesis, I thought I should do a control experiment, iontophoresing from a pipette filled with 1M buffer at pH 4—but I got the same responses. Big lesson for me: Do control experiments early! This “acid response,” seemed curious, but the possibility that local pH transients might play a central nervous system (CNS) signaling function was not yet on radar screens, and I considered it a dead end. (Retrospective lesson: Pay close attention to unexpected lab results.)

I decided to study GABA chemosensitivity instead on cultured spinal cord neurons, a richer system containing excitatory and inhibitory synapses—and no acid responses. Like most electrophysiologists, I loved listening to my preparations, especially late at night when the lab was quiet: the popping and crackling of spontaneous postsynaptic and action potentials as rendered by an audio amplifier. Private conversations among neurons in mysterious code, scaling somehow to form perceptions and thoughts. I would take reams of oscilloscope pictures using a Grass camera with its massive 35 mm film magazine, a photomachine gun.

Progress was initially slow. I found GABA iontophoresis variable, making it difficult to establish reliable baselines that I could challenge with manipulations, and access to equipment was sometimes limiting. I decided therefore to take a break from the lab and work on clinical rotations. I found that I also enjoyed seeing patients and trying to figure out their problems. Meanwhile, perhaps aided by this mental refresh, I came to a couple of research solutions. First, I found a way to accelerate the lab’s planned construction of a third electrophysiology rig, placing a Steelcase office desk on scooter inner tubes for use as an air table, and making a chart recorder out of an ancient electroencephalography (EEG) machine that I found in the department’s basement equipment archives. Although this makeshift chart recorder tended to spray ink when excited, it was accurate enough, and I could use it 24/7 because no one else wanted anything to do with it. With ink, EEG paper, and a lot of Kimwipes nearby, it provided an efficient way to track slow voltage responses. No need to spend hours in the darkroom developing film. And, more important, I devised a reliable method for delivering solutions of choice to cultured neurons.

Occasionally, an iontophoretic pipette would plug up and fail to deliver drug. Gerry taught to diagnose this by breaking off the electrode tip so that its contents would leak out. I wondered whether a similar approach could be made to work in a more controlled fashion with a smaller tip, around 3 microns. Nothing came out spontaneously from such a pipette, but it looked like a squirt gun nozzle under the microscope—maybe some air pressure would help? Eric Frank was a postdoc in the lab and a generous scientific mentor to me from day one. When I discussed the situation with him, he went across the quad to the Neurobiology Department and obtained a compressed gas source complete with a mechanical switch. The results were beyond expectation—the “puffer” pipette (Gerry’s term) rapidly delivered undiluted pipette contents to a recorded neuron, and then it backfilled slightly when the pressure pulse was terminated, preventing content leakage. It effectively constituted a microperfusion approach, giving Nernst equation fidelity when high potassium buffers were ejected. (Unfortunately, I did not appreciate the commercial potential of the device, or the later emergent Picospritzer apparatus—presumably the result of a parallel thought process and still on the market today—might have had some competition.)

My fellow pharmacology graduate students, including Terry Gibbs, Steve Schuetze, and Chauncey Bowers were bemused by this puffer system (Terry commented that it positioned me to spend my days cheerfully “squirting *** on cells”). One afternoon, Chauncey came by with a vial of chlordiazepoxide and suggested that I squirt it. A bit of reading informed me that this benzodiazepine, the clinically momentous invention of the Hoffman-La Roche medicinal chemist Leo Sternbach, had become the second best-selling drug in the United States (as Librium, surpassed only by its fast-follow cousin, Valium) based on useful anxiolytic actions, but its mechanism of action was still unknown. The lead theory at the time, based on the receptor binding studies of Anne Young and Sol Snyder, was that these drugs were glycine agonists. A few experiments with my puffer system was all that was needed to reveal that chlordiazepoxide did not have a direct effect on membrane voltage or conductance, but when switching back and forth to compare with GABA, I saw that the response to submaximal GABA (but not glycine) was potentiated right after a chlordiazepoxide pulse.

Another postdoc in the lab, David Farb, joined the project to exclude an inhibitory effect on GABA uptake. Although neuropharmacological drugs at the time were classified as agonists or antagonists, we felt that this potentiation likely reflected action at a modulatory site on or near the GABA receptor and that it might be a more general precedent for drug action. David became another valued lab mentor to me, sharing his expertise in enzyme biochemistry as well as his infectious enthusiasm for life and science. We had an uphill challenge to convince Gerry to let us write up a short report, as he strongly preferred full-length papers, but we eventually convinced him that the finding would not keep and published it in Nature in 1977, EEG machine recordings and all. The discovery of the CNS benzodiazepine-binding site was reported in the same year by Squires and Braestrup, as well as by Mohler and Okada. I recall afterward having energetic discussions with David about how much fun it would be to discover a clinically useful drug, overlooking the evident fact that our study had nothing to do with the discovery and development of benzodiazepine drugs.

Anyway, soon after, I was delighted to learn that Gerry and the Pharmacology Department thought my lab work met PhD requirements and that Harvard Medical School likewise considered my completed clinical clerkships sufficient for graduation. The prospect of finishing well ahead of schedule was irresistible. A wiser man would have delayed at least another year, to flesh out the benzodiazepine discovery, establish a presence in the field, and then come back up to speed in clinical skills before internship. But I was in a hurry: I had gotten engaged to my college girlfriend, Yvette Sheline, and could not see how I could marry on my graduate student stipend of $325 a month.

I plunged directly from a thesis defense into marriage and a medical internship at Harvard’s Peter Bent Brigham Hospital. (Lesson: not an ideal sequence.) I tried to compensate for my clinical shortcomings by working hard. It was five months before I even looked for the on-call room to catch brief naps during my every third night on call. But eventually the intense training brought me up to speed, and I entered a neurology residency at Harvard’s Longwood area hospitals feeling like a doctor. Neurology had become the obvious choice of medical specialty for me. I had ruled out neuropathology (wanted to see patients) and neurosurgery (didn’t think I could maintain operative skill while doing research). Psychiatry at the time seemed insufficiently connected with neuroanatomy and neurobiology, but this has changed and I would certainly consider a career in psychiatry today.

My clinical role model was H. Richard Tyler, the chief of neurology at the Brigham, an exceptional neurologist whose physique and analytic style reminded me of Doyle’s Sherlock Holmes. I also had an opportunity to learn from other renowned senior clinicians, including Norman Geschwind, Marcel Mesulam, and Simeon Locke at the Beth Israel Hospital, and an excellent cohort of more junior attending physicians, including Marty Samuels, Mark Hallett, Dennis Selkoe, Mike Moscowitz, Mike Ronthal, and Marc Dichter. Marc was a role model for me—he saw patients, recorded from cultured neurons, and loved his life.

My neurology residency was less demanding than the internship, but I still had more duty hours than would be permitted under current residency training rules, in part because of illness in the resident group. I would sometimes cover neurology for two hospitals simultaneously, running across Longwood Avenue in the middle of the night. I remember a fellow resident taking hospital call while acutely ill, an IV plugged into his arm, rather than impact his colleagues with additional absence. Arnold Kriegstein and Stuart Lipton were neurology residents in the same program, one year ahead, and Paul Rosenberg was a coresident with me. Although all three would go on to have distinguished careers in academic neurology and laboratory neuroscience, the service intensity of the residency program had us preoccupied with clinical issues. I have had great scientific discussions with each, but only later.

Mark Hallett kindly agreed to teach me electromyography during residency; afterward, I completed a fellowship at the Massachusetts General Hospital in EEG and evoked potentials with Keith Chiappa. Subspecializing in the electrical arts of neurology seemed logical, and I also needed to delay job-hunting while Yvette finished her residency in psychiatry at the Beth Israel. During my fellowship, I took stock of my skills and applied for faculty jobs in academic neurology departments. I wanted a clinician-scientist position, but by then, it had been five years since I had done an experiment and I was not the strongest candidate. The alternatives were to take a straight clinical job or to train further in research. The former option was briefly tempting, but I knew I would miss research. Variations on the latter option were moving up when an offer came from Stanford that I thought might work.

Stanford (1983–1991)

The driver for the Stanford offer was my subspecialty training in clinical neurophysiology, as the neurology department needed someone to back up existing EEG and EMG faculty. It was a tenure track job, but only because Stanford had no other track in place at that time in clinical departments. Today, a similar job at Stanford or elsewhere would likely be on a clinician track, and someone taking such a position would have little chance of reestablishing a bench research career.

The department was small, with a modest clinical service and a deep commitment to laboratory research. The chair was David Prince, an eminent neuroscientist who studied epilepsy mechanisms in slice preparations. The neurology faculty at that time included Steve Waxman, Bruce Ransom, Arnold Kriegstein, Barry Connors, Mike Weinrich, and Steve Peroutka, and the Prince lab attracted outstanding trainees, such as David McCormick, Istvan Mody, John Huguenard, and Scott Thompson. I carried an extra clinical service load compared with other junior faculty, performing the EEG and electromyography (EMG) studies I was hired to do, and serving at one point as acting head of the EEG laboratory. However, David set a fair limit on my clinical responsibilities and encouraged me to attend also to the research that I would need to do to gain tenure. There were only two problems: not enough space, and what to work on.

The department had a single hallway in the basement of Stanford Medical School to support its research, so the only lab space David could assign to me was a small electrophysiology rig room—the proverbial windowless room with a sink. Worse, though, was the problem of my own making, an absence of research momentum after five exclusively clinical years. I thought about returning to studying benzodiazepines, but I had not established a presence in the field and would have to retool. I had bookmarked multiple topics worthy of investigation during residency, but the practicality of starting a laboratory within my limitations had me leaving my intellectual pride at the door and thinking more like the guy with a hammer, looking for nails.

Let’s see, neuronal cell cultures (Bruce Ransom had kindly agreed to let me use his culture equipment): electrophysiology. I decided to return to studying the action of central amino acid transmitters, switching to the excitatory side, glutamate, and to a mammalian system, Marc Dichter’s murine cortical cell cultures (upon his good advice, given translational goals). The glutamate field was then rapidly expanding, following breakthroughs in receptor pharmacology led by Watkins, Curtis, McLennan, and others, and recognition of its CNS neurotransmitter role. One puzzle caught my eye: the basis for the unusual “negative slope” seen in the current-voltage relationship of the newly delineated N-methyl-D-aspartate (NMDA)-type glutamate receptor. At certain membrane potentials, depolarization paradoxically increased, rather than decreased, cation entry through the NMDA receptor-gated membrane channel, a characteristic that positioned the NMDA receptor to participate in key circuit behaviors. I wrote an R01 grant application to NIH outlining how I would investigate the basis of this phenomenon. The NIH study section was concerned about my hiatus from research, but recommended that I be given a chance: an R01 grant with a two-year duration. Before I could start study, however, the phenomenon was thoroughly explained in beautiful papers published by Nowak and Asher, and Mayer and Westbrook: the voltage-dependent block of the NMDA receptor channel by magnesium ions.

Abruptly project-free yet funded, I began to search for a related new direction that my NIH program officer would find acceptable. Reading further in the glutamate field, I came across John Olney’s work describing glutamate’s neurotoxic potential, which he called “excitotoxicity.” Although it was clear that glutamate and related analogues could kill neurons, how this occurred was undefined and seemed like a good topic for me. It was possibly relevant to disease, and I thought it was likely related to membrane events and ionic movements. The case for studying excitotoxicity was iced for me when I read a fantastic paper published by Steve Rothman in the Journal of Neuroscience in 1984, demonstrating in hippocampal neuronal cell cultures that an early glutamate antagonist, D-glutamylglycine, could block glutamate-induced depolarization, glutamate-induced death, and anoxic neuronal injury.

I set out with my technician to examine the dependence of glutamate toxicity on extracellular ions. Although Steve had added glutamate to the culture medium to achieve long exposure, I worried that such exposure might overemphasize the acute cellular swelling induced by glutamate in an open culture system: neurons exposed to glutamate blew up like balloons and rapidly disintegrated, whereas cell volume expansion in the intact brain was limited by the skull. Going instead with limited, five-minute exposures, I saw that the immediate swelling induced by glutamate could be reversible; potentially more important was a later degeneration occurring hours later. Acute swelling, like glutamate excitation, was dependent on extracellular sodium; the later degeneration, which was rate limiting for neuronal survival after brief glutamate exposure, was dependent on extracellular calcium. The idea that calcium overload might contribute to pathological neuronal cell death fit nicely with observations implicating calcium overload in other forms of toxic cell death involving hepatocytes or skeletal muscle cells.

I submitted my first glutamate paper at the end of 1984 to Neuroscience Letters. Around then, my lab space problem vanished. Chronic departmental space requests finally resulted in the school giving the department a block of additional research space; not in the packed medical center itself, but leased in a nearby office building on Welch Road, near the Stanford Shopping Center and adjacent to dentists and real estate companies. The eminent pharmacologist, Avram Goldstein, discoverer of dynorphin, had established a lab there, and was winding down. David Prince assembled the neurology faculty and asked for volunteers to relocate. None of the senior faculty wanted to go, seeing it as a form of exile, so Steve Peroutka and I, the most junior faculty, were ordered to go.

Welch Road was perfect for me, and the presence of a Häagen-Dazs® across the street an additional plus. With ample space and an interesting project, I could tap into the rich flow of talented trainees drawn to Stanford and the beauty of northern California. Mark Goldberg, Evelyn Tecoma, and John Weiss joined my lab during their neurology residency, John eventually enrolling for a PhD and Mark staying on as a full-time fellow afterward. I put a request in with the Stanford neuroscience PhD training program for students, and matched with Dean Hartley and Jae Young Koh. Bringing Jae to Stanford took extra doing, as he was then in Seoul. The admissions committee was impressed with his perfect test scores and academic record, including a medical degree from Seoul National University, but arranging an interview was problematic. I offered to absorb risks and guarantee him a place in my group, and I met him for the first time in the San Francisco Airport. He looked like a bodybuilder and didn’t talk much, but he would bring deep thoughtfulness and creativity to everything he did.

Another early addition to my lab was Hannah Monyer, a Romanian-German physician who had come to Stanford to study EEG. One morning while we were plowing through a stack of EEGs, she asked what I did in the afternoons, and I told her about excitotoxicity. She asked to come by and observe. I recall that others in the group did not think she would be with us very long. She was gifted, multilingual, and worldly, with deep interests in music and literature, but needed instruction on how to use a lab balance. However, she dove into a project to see whether glucose deprivation would trigger excitotoxic neuronal death (it did). By then we had taken a page from the clinical medicine playbook and were assessing late neuronal death by measuring lactate dehydrogenase release from lysed cells, as cardiologists do when assessing heart attacks. Jae showed that this simple approach was nicely linear. However, we were equipment limited and had to measure enzyme activity with a single tube spectrophotometer assay. I came in one morning and saw Hannah sitting on bench stool next to a large pile of tubes, looking a little cross. “In early,” I noted. “What do you mean, early,” she replied, “I wanted to see some results and I haven’t gone home yet.” I suspected then that she would make a major mark in research.

Other key members of the Stanford lab later included Laura Dugan, a geriatrician with expertise in free radical biology; Rona Gifford, a Stanford faculty anesthesiologist on research sabbatical; Valeria Bruno, a postdoc from Fernando Nicoletti’s lab in Catania, Italy; Ray Swanson, an assistant professor of neurology at the University of California, San Francisco (UCSF), interested in glia; Ray Regan, an emergency medicine physician; and Steve Peters, a postdoc trained in intracellular recording. Money was very short to start. In a silly effort at economy, I hired a Stanford engineering undergraduate, Paul Duffy, to build a commercially available electrophysiology amplifier from scratch, which he did with good cheer. It worked, but was predictably noisier than the commercial device. A $10,000 grant from the Hereditary Disease Foundation, intrigued by suggestions that excitotoxicity might contribute to neuronal loss in Huntington’s disease, came just in time. More important in the longer run, the funding was accompanied by an invitation from Allan Tobin to join the foundation’s scientific advisory board, giving me a chance to meet and learn from the outstanding scientists associated with the organization, including Robert Horvitz, Ron McKay, John Mazziotta, and Anne Young.

Having implicated calcium in triggering excitotoxic neuronal death, our attention focused on NMDA-type glutamate receptors, which had been shown by then to gate calcium-permeable channels, unlike the monovalent cation channels typically gated by non-NMDA glutamate receptors. As this calcium permeability would predict, NMDA receptors dominated glutamate-induced death, even, as Dean Hartley showed, after termination of glutamate exposure, demonstrating a feed-forward property of excitotoxicity. Non-NMDA, or alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors, could also trigger excitotoxic death, but typically required more prolonged receptor activation. Mark Goldberg set up a combined oxygen-glucose deprivation (OGD) protocol that triggered cultured neuronal death also prominently mediated by NMDA receptors; this model became widely adopted by the brain ischemia field. Our work fit nicely with key in vivo studies, beginning with the work of Nils Diemer and colleagues showing that extracellular glutamate rapidly accumulated in ischemic brains, and the work of Brian Meldrum and colleagues showing that an NMDA antagonist could reduce brain damage in rats subjected to transient global ischemia.

Evelyn Tecoma and Mark Goldberg also showed that NMDA receptors contributed to the propagation of neuronal death on the edges of a physical scratch in the cultured neuronal cell layer, modeling a traumatic brain insult. We found that both brief intense exposure to glutamate and OGD were pharmacologically well-behaved assays: neuroprotective drugs demonstrated IC₅₀’s and classic competitive or noncompetitive dose-response curves appropriate to their mechanisms of action. Looking downstream, Hannah discovered that free radicals were important mediators of excitotoxic death. We imagined that loss of calcium homeostasis would lead to myriad derangements all sharing responsibility for free radical generation, but there we were wrong; Sol Snyder’s lab fingered calcium-activated neuronal nitric oxide synthase as a critical source of excitotoxic free radicals. Later, Laura Dugan developed some spectacular novel antioxidants, based on buckminsterfullerenes, that were neuroprotective in vitro and in vivo.

We had the bandwidth to explore some interesting side topics as well. Jae Koh asked whether vulnerability to excitotoxicity was uniform across the different types of neurons present in cortical cultures, and found a population of cells resistant to NMDA receptor-mediated toxicity, but highly vulnerable to non-NMDA receptor-mediated toxicity. We thought that differential vulnerability to excitotoxicity might help explain the various patterns of selective neuronal death observed in certain neurodegenerative conditions. John Weiss would later pursue the hypothesis that AMPA receptor-mediated excitotoxicity might specifically contribute to selective motor neuron loss in amyotrophic lateral sclerosis. In a search for clinically relevant environmental excitotoxins, John studied the cycad plant amino acid, β-N-methylaminoalanine, which was suspected of triggering an ALS (amyotrophic lateral sclerosis)–like neurodegenerative disease in Guam, and found that it combined with bicarbonate to form an effective glutamate agonist and excitotoxin.

Another fruitful side project examined the effect of lowered pH on cortical cell death after OGD, as tissue lactic acidosis accompanied brain ischemia in vivo. Consistent with the discovery of Morad and colleagues that pathophysiologically relevant levels of acidity reduced NMDA receptor-mediated currents, Rona Gifford found that such acidity reduced OGD-induced calcium influx and neuronal death. Later we found it could also injure glial cells and potentiate the contribution of AMPA receptors to neuronal death, the latter likely by delaying normalization of intracellular free calcium levels. These experiments highlighted for us both the potential utility of reductionist approaches for dissecting the factors contributing to the pathogenesis of ischemic brain injury, and also their limitations. In vivo, and ultimately, human experiments would be needed to define the weighting of different factors.

Our largest side project, which steadily grew over time, was the study of zinc as a modifier of glutamate action and excitotoxicity, as well as another neurotransmitter toxin in its own right. Noting that zinc was known to be coreleased along with glutamate from many central excitatory synaptic terminals, we thought it had to do something interesting to glutamatergic transmission and found that it could regulate NMDA receptor activation, inhibiting channel opening and blocking channel current. Steve Peters started the project using intracellular recording electrodes, and Chad Christine, a medical student, then extended it to the channel level. We also found that zinc exposure could itself be neurotoxic, a finding that Jae Koh would later pursue at Washington University.

Searching for a suitable practical neuroprotective antagonist for NMDA receptors, we came across a 1985 paper by Church and colleagues reporting that dextrorphan reduced the excitatory effects of N-methyl-aspartate on rat spinal neurons. Given prior safe use of the related morphinan, dextromethorphan, as an over-the-counter cough medicine, we tested both against neuronal death induced by glutamate or OGD, and we found both to be neuroprotective. This finding interested the original inventor of these compounds, Hoffman-La Roche. Roche hired me as a consultant to advise them on entering the field of neuroprotection and began to explore development of dextrorphan as a treatment for stroke. The lead pharmaceutical company in the area at the time was Merck, which had invented the extremely potent NMDA antagonist, MK-801.

This was an exciting time for my lab. We felt that we were doing important work and contributing to ending a then-pervasive nihilism regarding treatments for neurodegenerative diseases, such as stroke or Alzheimer’s disease. A growing number of university labs and companies were joining the neuroprotection fight. Appreciation was growing that pathological cell death was not necessarily an inevitable consequence of insults, such as ischemia, but rather the result of specific molecular cascades potentially subject to therapeutic interdiction. I fantasized that standard neuropharmacology textbooks would someday have a chapter on neuroprotective agents, right up there with chapters on anesthetics or antidepressants.

By 1987, I had run four years off my seven-year Stanford tenure clock, obligating David Prince to sit down with me and notify me that I was not on a trajectory likely to earn tenure. I had only two more years of employment to go, and then a terminal year. He did this kindly and made good suggestions for how I might try to increase my research productivity. The meeting was not as devastating as it might have been, since by then I had some good studies and manuscripts in progress, but it was certainly uncomfortable and humbling. Down the line, I think the experience helped me become a more empathetic faculty mentor in the two academic neurology departments that I would later chair.

In the months after this official academic warning, my lab’s work became more visible and I received invitations to participate in a growing number of scientific symposia. I remember one meeting particularly well—an international meeting dedicated to the neurobiology of CNS excitatory amino acids, held in Manaus, Brazil, in 1988, just before the first glutamate receptor was cloned. The organizers chose Manaus simply because it seemed to be an interesting place that few scientists had previously visited. Travel there was challenging, but the field’s momentum ensured strong attendance. I was with a group of American scientists who missed the evening connecting flight out of Rio and had to spend the night slumped in plastic chairs at an open-air bar on the airport tarmac, too much beer mixing with jet fumes and fragments of sleep. We caught a flight the next morning, with me running back to retrieve Mark Bear, still fast asleep in his jet bar chair.

Manaus itself was otherworldly, a place where native Brazilians transitioned from jungle villages into city life, living first in rough, colorful shacks positioned around the city’s perimeter, beautiful from a distance but sad up close. Our hotel was old-European elegant, with oddly heavy rugs slightly redolent of humidity and mold. Power was irregular, but the science was exhilarating. Appropriately, Jeffrey Watkins gave the keynote lecture. It was the first opportunity for me to meet some of the field’s pioneering senior scientists, whose work I had studied and admired, including Philippe Ascher, Erminio Costa, Carl Cotman, John Davies, Sten Grillner, Uwe Heinemann, David Lodge, Brian Meldrum, and John Olney. Other key scientists present included Graham Collingridge, Michel Cuenod, Gary Lynch, Richard Miller, Michael Rogawski, Robert Schwarcz, Roger Simon, Vivian Teichberg, Tadeusz Wieloch, Anne Young, and Suzanne Zukin. Pharmaceutical company laboratories were represented in force, including by Les Iverson, who was leading the Terlings Park discovery research site for Merck where MK-801 had been invented.

Receptor subtype-selective agonists and antagonists in hand, and molecular cloning of receptors just around the corner, the field had by then moved about a decade past “the dark ages” when a specific transmitter function for glutamate was widely considered unlikely (Watkins and Jane 2006). Yes, glutamate was a cell metabolite, but it also mediated neural signaling and synaptic plasticity throughout the mammalian CNS. The ubiquity and transmitter function of glutamate made its toxicity all the more remarkable. How could evolution permit the development of such a dangerous system, capable of triggering neuronal death in minutes following loss of blood flow, or structural damage? Perhaps a glutamate gun to the head was a small price to pay for a fast and plastic nervous system.

Around the same time, Erminio Costa invited me to join the inaugural faculty of a new international school of neuroscience sponsored by the Fidia Research Foundation and based in Padua, Italy. This appointment was largely honorific, although it began with the privilege of teaching in a week-long seminar course convened in a beautiful and historic monastery in Abano Terme. Lecturing about brain science, and watching monks perform sunlit chores outside while the monastery bells pealed, I felt connected to timeless human endeavors: the tending of bees, the quest for knowledge.

Meanwhile at Stanford, I had maintained steady clinical engagement. I enjoyed teaching and was assigned responsibility for the neurology residency-training program. By the end of 1989, I was granted tenure and promoted to associate professor—and then shortly thereafter, rather abruptly and to my surprise, considered nationally as a candidate to lead neurology departments. I was invited to interview for the neurology chair at Harvard and Beth Israel Hospital where I had trained, vacated by the sudden and sad death of Norman Geschwind. The idea of returning to Boston was appealing, and I was warmly hosted during my interviews by David Potter, who put me up in his Cambridge home in place of the usual hotel. But then another option appeared, after members of a search committee from Washington University visited my laboratory.

The Washington University Neurology Department was large and nationally prominent, drawing patients in from a multistate region and running clinical service volumes that were a multiple of corresponding Stanford department numbers. The dean of the medical school, Bill Peck, was seeking to boost the department’s research efforts and was prepared to make a substantial block of laboratory space available to a new neurology chair. I worried about my ability to take on the associated management responsibility, but the opportunity to expand pursuit of neurodegenerative mechanisms both in the laboratory and in clinical trials was for me irresistible. And although some Stanford colleagues opined that they could not imagine trading the Bay Area for the Midwest, I saw adventure there. Beer, bombers, baseball; Gateway to the West, Mark Twain, the Show-Me state; and with both John Olney and Steve Rothman there, the birthplace of excitotoxicity research. Yvette, who struggled daily for resources as a psychiatrist in the Santa Clara County mental health system, was also offered a full-time academic position at Washington University. We agreed to go, despite a strong counteroffer from Dean David Korn Stanford.

I delayed my departure from Stanford for a year and a half to allow me to complete some ongoing projects. I was also predictably drawn into affairs in St. Louis and ended up with a job and a half to do for quite some time. Lesson: Transition gracefully, but expeditiously.

On the other hand, the extra time working with my Stanford lab was valuable. I attended a superb week-long workshop on the topic of neurodegeneration, a Dahlem Konferenzen sponsored by the German Science Foundation, which was held in Berlin and chaired by Don Price, Hans Thoenen, and Albert Aguayo. The workshop took place during historic change in Berlin, as the Wall had come down only a few months before, and the streets of West Berlin were filled with window-shopping groups of East Berliners, readily recognizable in their faded denim clothes. I found the Gedachtniskirche, the Kaiser Wilhelm Memorial Church, especially moving: its blackened, ruined tower a stern reminder of the devastation of war. At the workshop, I benefited from discussions with investigators at the forefront of the development, Alzheimer’s disease, neurodegeneration, and growth factor fields. I left with an enhanced appreciation for the importance of programmed cell death in sculpting the nervous system during development, and intrigued by the potential ability of inappropriately triggered apoptosis to contribute to pathological neurodegeneration.

The extended transition period also allowed me to help a neurology resident, Greg Albers, launch his career as a clinical stroke specialist. At the time, given a paucity of proven interventions, vascular neurology was not a recognized subspecialty, and stroke patients were typically managed on general neurology or medicine floors. No special effort was made to get these patients to the hospital quickly, in contrast to patients with heart attacks who were always a top priority for emergency medical service transport. Greg had joined me in some early discussions with Hoffman-La Roche regarding the possibility of developing dextrorphan as a neuroprotective agent for stroke or cardiac arrest. In the process, he became convinced that dedicated stroke centers would soon emerge broadly in U.S. medical centers and be responsible for testing new acute therapies. Following residency, Greg signed on as a clinical fellow with me, in actuality training himself as he explored the frontiers of optimizing stroke care. He went on to join the faculty and cofound the Stanford Stroke Center, the first stroke center in the United States to gain Joint Commission certification as a Comprehensive Stroke Center.

Washington University (1991–2001)

At Washington University, I started faculty recruitment with two Stanford colleagues, Mark Goldberg and Laura Dugan. Later, having completed a medical internship in California, Jae Koh joined the department as a resident trainee. As a framework for expanding departmental research, I designated the department’s new laboratory floor the core of a new Center for the Study of Nervous System Injury (CSNSI), dedicated to identifying mechanisms underlying neurodegeneration in acute and chronic disease states, with emphases on convergent pathways and therapeutic countermeasures. This theme was attractively inclusive of a range of faculty research programs, including longitudinal clinical studies led by Leonard Berg and John Morris in the Alzheimer’s Disease Research Center, and neuroimmunology studies led by Anne Cross and Michael Racke. Pediatric neurology was historically a division of pediatrics, but I convinced that chair, Harvey Colton, that research synergies would be enhanced by moving the division to neurology. The move had the great consequence of bringing Steve Rothman’s and Kel Yamada’s laboratories into the CSNSI core. Other faculty recruited early on to join Washington University and the CSNSI were Chung Hsu, an experienced stroke biologist and clinician; David Gutmann, a pioneer in elucidating the molecular pathogenesis of neurofibromatosis; and David Holtzman, a rising star in the Alzheimer’s disease field.

Getting my own laboratory restarted took longer than I would have liked, but I had the fortune to recruit a series of outstanding fellows and students, and things gradually picked up. A big boost came when Hoffman-La Roche, increasingly interested in neuroprotection, offered us a major research collaboration. Roche provided unrestricted research support to CSNSI investigators, ultimately about $11 million over 8 years, in exchange for frequent scientific discussions and a right of first refusal for any commercial products stemming from work they supported. I believe we provided Roche with useful guidance, and certainly their support was helpful in advancing our research programs. In a world apart from Stanford equipment-building days, we could afford to buy top-line equipment and all the supplies we needed. Regrettably, such industry seed investments in academic collaborations have become rare in modern times, typically replaced by focused research contracts.

Merck, Roche, and most other large pharma companies advanced NMDA antagonist drugs for acute stroke neuroprotection, while medical centers and emergency medical services across the country geared up for rapid stroke treatment, minimizing “door-to-needle” delay. This accelerated when the thrombolytic agent, tissue plasminogen activator, was approved by the U.S. Food and Drug Administration for stroke treatment. However, one after another NMDA antagonist program failed. Some failures, as with Roche’s dextrorphan program, were due to side effects, but others, as with the Ciba-Geigy drug CGS19755, appeared to be due to a straight up lack of efficacy.

What went wrong? How could drugs so effective in reducing ischemic infarction in rodent models of stroke fail to show benefit in human stroke? Drawing on perspectives gelled by the Dahlem workshop in Berlin, my lab pursued the hypothesis that ischemic apoptosis was to blame. Intense activation of NMDA receptors triggered a fulminant neuronal death distinct from programmed cell death, and it seemed plausible that such “excitotoxic necrosis” might be exaggerated in experimental rodent models: sharp onset of complete ischemia, lissencephalic brains, and simple vascular territories. In contrast, human stroke is often characterized by a progressive onset, and the gyrencephalic human brain has complex vascular territories and large watershed zones. Threshold insults seemed more likely to allow cells to execute orderly programmed death mechanisms, beyond the reach of NMDA antagonist drugs.

We developed three lines of evidence to support this idea, which remains an unproven but viable hypothesis today. First, Byoung Joo Gwag set up a cell culture model of ischemic apoptosis by blocking excitotoxicity with NMDA plus AMPA antagonists, and then extending the period of oxygen-glucose deprivation until cortical neurons died. This death was apoptotic, associated with cell shrinkage and requiring caspase activity. Lorella Canzoniero and Stefano Sensi showed that the intracellular free calcium levels in these dying cells were lower than normal. Bringing calcium back to normal with a calcium ionophore—or even a glutamate agonist—attenuated neuronal apoptosis; lowering calcium alone could induce apoptosis. We envisioned that the high-level NMDA receptor blockade targeted by industry stroke programs might have beneficially reduced excitotoxic necrosis but swamped this benefit by enhancing ischemic apoptosis.

Second, Cheng Du looked for evidence of ischemic apoptosis in rodent stroke models. At the time, intense ischemic insults were in widespread use; necrosis evolved quickly over hours and final infarction could be accurately assessed the next day. We tried grading the insult down, using shorter periods of transient ischemia, until we found a threshold insult producing little or no infarction one day later. But if we followed instead of sacrificing, we found that infarction gradually progressed over the next days. This “very delayed infarction,” a counterpart to the delayed neuronal death known to occur after transient global ischemia, was associated with considerable neuronal apoptosis at the borders of the maturing infarction.

And last, Jae Koh and Sangwon Suh discovered that loss of zinc homeostasis contributed to selective ischemic neuronal apoptosis after transient global ischemia. JinMoo Lee and Greg Zipfel followed that work by identifying a zinc-mediated component in the neuronal apoptosis associated with very delayed infarction after mild transient ischemia. We initially focused on the trans-synaptic movement of presynaptic terminal zinc as the source of postsynaptic zinc overload, but later elegant work by Elias Aizenmann and colleagues implicated free radical-triggered release of intracellular bound zinc as a more important source.

Our pursuit of ischemic brain injury mechanisms to consideration of apoptosis and zinc overload led us to consider excitotoxic ionic derangements more broadly. Although we had previously focused on calcium and sodium entry through glutamate receptor-gated channels (the latter further enhancing calcium entry), these channels were also highly permeable to potassium: Could potassium efflux from depolarized cells contribute to injury? Shan Ping Yu, a patch clamper recruited from Stony Brook, found that the activation of delayed rectifier-mediated potassium efflux contributed to several forms of neuronal cell apoptosis, and that glutamate receptor-mediated potassium efflux could also play a role. These studies fit with work by Cidlowski and colleagues in monocytes, suggesting that potassium efflux and resultant lowering of intracellular potassium concentrations were key steps enabling programmed cell death pathways, including the activation of caspases.

Other studies in the lab led by Marga Behrens, Uta Strasser, Valerie Heidinger, and Alain Buisson explored the modulatory effects of the metabotropic glutamate receptor system on glutamate receptor function and excitotoxicity. Injury pathways downstream of glutamate receptor or zinc were further delineated by Joy Snider, Christian Sheline, Pat Manzerra, and Shadi Fahrangrazi. Sandy Hewett linked in reactive astrocytes when she found that cytokine-stimulated astrocytes generated nitric oxide that potentiated NMDA receptor-mediated neuronal death. Besides additional work on OGD-induced neuronal death or stroke carried out by Margaret Grabb, Doug Lobner, Deb Babcock, and Arshad Majid, we also were able to extend investigations into spinal cord injury, funded by the National Institute of Neurological Disorders and Stroke (NINDS) and the Christopher Reeve Foundation. I had the privilege of joining an international research consortium organized and supported by the Reeve Foundation: Reggie Edgerton, Rusty Gage, Louis Parada, and Martin Schwab were other members. A Washington University neurology resident and postdoc, John McDonald, represented my lab in this working group, and established a local collaboration with David Gottlieb in neurobiology and Ling Wei in cell biology (Shan Ping Yu’s wife) to see whether the transplantation of neutrally differentiated stem cells could improve recovery in vivo after brain or spinal cord injury (it could). John additionally widened the traditional concept of excitotoxicity when in collaboration with Mark Goldberg he demonstrated that oligodendrocytes were highly vulnerable to AMPA toxicity.

When not doing research, I attended to managing neurology department operations. When I assumed responsibility, the department lost a little money each year, despite the benefits of the last vestiges of straight fee-for-service reimbursement—outside of charity work, the department collected much of what it billed. During my decade tenure as department head, our net collection rate would drop by more than a third; without changes, we would have lost millions of dollars per year on clinical operations. But we expanded services and increased efficiencies, recruiting faculty, opening new subspecialty services and more than quadrupling clinical volume and external research support. By 2001, the department had saved up a sizable endowment and was ranked first in the country in NIH research support (really second, since Harvard’s multiple departments were considered separately). This could not have happened without the efforts of a skilled senior administrator, Bob Schaefer, and staff: Laura Waugh, Linda Montague, Micky Wilderspin, Patti Nacci, and Paul Demediuk. Patti’s position was new and impactful: helping young faculty write research grant applications. Paul likewise had a new role: A biologist turned information technologist, he set up the departmental computer network well ahead of institutional initiatives, stringing cable himself between rooms. I recall cheering when the department’s first IBM Pentium desktop computer (“Rothman’s Big Bad Pentium”) appeared on the network. Paul’s efforts allowed the department to gain a strong internet presence in the early days of the web, with Alan Pestronk’s section becoming known in neurology circles as a go-to place for up-to-date information about neuromuscular diseases.

Paul’s advanced skills also saved me from an editorial nightmare. Jacques Mallet and I had been approached by Blackwell Scientific to establish a new research journal focusing on the biology of brain diseases. We thought this timely, as papers in this area could sometimes fall between the scope of the clinical and basic neuroscience journals of the time. We launched the Neurobiology of Disease in 1994, begging colleagues to send us papers. We got great submissions, but after only a few issues, Blackwell abruptly informed us that they were abandoning the journal, effective immediately. The prospect of letting down the friends who had trusted us to publish their work was unbearable. Fortunately, Paul came up with a creative temporary solution. He scanned the papers and posted them electronically on a dedicated server he set up in the department. Jacques and I assured authors that we would continue to make the papers available on the web indefinitely, if needed. A permanent solution surfaced a few months later, when Graham Lees at Academic Press enthusiastically offered to take on the journal, and arranged for the journal to be indexed in MEDLINE retroactive to the first issue. Today, the journal is absorbed under the Elsevier roof and thriving under new editorship.

Between research, managing the department, and a busy travel schedule, I decided that I could not have my own outpatient practice, but I continued to see inpatients as an attending on the busy main Barnes-Jewish Hospital service each July, welcoming the new residents. I also held regular chief-of-service rounds. This I felt was a true perk of the job—an opportunity to see some of the most interesting or challenging patients of the week. I also continued to teach when possible. The highlight of my teaching career was an opportunity to direct the Neurobiology of Human Disease course at Cold Spring Harbor, which I did for several years together with Bill Mobley from UCSF. A roomful of energetic, incisive students from diverse backgrounds and multiple countries, long summer days to bounce ideas around with a spectacular series of visiting faculty, the idyllic Banbury Conference Center on Long Island’s north shore. What could be better? I still have the t-shirts.

Administration: SfN, Industry, and Academia

I loved my work as a researcher-clinician-teacher, but as department-building and recruitment leveled off, I began to think about taking on another professional adventure. I recalled that when I started, I had asked Dean Peck how long he thought a clinical department head should serve. He had answered without hesitation: 10 years. Long enough to see things through, but not to stagnate.

A major administrative challenge had already come my way, unexpectedly, from SfN. I had been active in the Society, chairing the Program Committee and serving as a councilor. In 1998, I began concurrent service as treasurer and president-elect, joining an Executive Committee with President Ted Jones and Past-President Lorne Mendell. In this unusual dual role, I could see that the Society had some key organizational weaknesses. It was dependent on a successful annual meeting to cover each year’s expenses and hence vulnerable if circumstances (e.g., weather) impaired a single meeting’s attendance. Under Ted’s steadfast leadership, the Executive Committee took a deep breath and began the difficult and initially controversial process of revamping Society processes and administration. During my year as president, an ad hoc advisory committee, consisting of Ray Dingledine, Gerry Fischbach, and Bernice Grafstein, provided additional counsel, and the next two Society presidents, Don Price and Rusty Gage, did the heavy lifting to put new processes in place. Rusty ultimately led the recruitment of Marty Saggese as executive director. I consider the present SfN to be an exemplar of a modern academic society, extensively and effectively engaged in support of neuroscience and landlord of its own headquarters building in Washington, DC.

In formulating academic initiatives for the SfN, I drew upon perspectives gained during service as chair of the U.S. National Committee to the International Brain Research Organization and worked to enhance partnerships with neuroscience societies outside North America, as well as with the Dana Alliance for Brain Research. As one of a small number of clinicians to serve as SfN president, I actively supported the SfN’s growing interest in disease biology and societal impact. I used the traditional privilege of organizing a Presidential Symposium for the purpose, unusual at the time, of bringing in a lay speaker who I thought had something important to say to neuroscientists. Christopher Reeve described his experiences with spinal cord injury and public advocacy in an evening lecture, riveting a packed lecture hall with articulate whispers, punctuated by respirator breaths. Later, he toured a poster session and seemed heartened and impressed. I also convinced Merck to provide no-strings support for the Presidential Symposium for a decade, setting a precedent for the more vigorous external fundraising that continues today. More longitudinally, I have been pleased to have served for many years on the committee for the SfN’s Neurobiology of Disease Workshop, part of the annual meeting—a wonderful tradition founded by the distinguished invertebrate neurobiologist, Ed Kravitz.

Two extraordinary job offers came in at about the same time in 2001. First, after a national search, NIH Director Ruth Kirstein offered me the directorship of NINDS. I was honored and tempted—to this day, it remains for me the “road not taken” that I still reflect upon. I had gotten to know NINDS well, having served on Study Section and Council, as well as an ad hoc advisor to two NINDS directors. But then another offer took shape: a chance to lead neuroscience drug discovery and clinical development at Merck Research Laboratories.

Merck had a reputation for being a science-driven company that discovered its own drugs. Furthermore, it had plans to expand an already large commitment to neuroscience drug development, building a new discovery site in Boston. I worried about leaving academia and knew that I would miss having my own lab, as well as clinical neurology and teaching. I had recently gained competitive renewal of my two NIH program project grants and R01, funding CSNSI research teams studying mechanisms of stroke and spinal cord injury. But I thought that the Merck position represented a rare opportunity to contribute directly to the development of needed drugs, going beyond what I was then doing as an academic collaborator or advisor to several companies. Also, on a personal and sad note, my marriage to Yvette had become strained. Divorce is not a good reason to change jobs and move, but it would be inaccurate to say that it did not factor in. After debating only briefly, I took the plunge, moving from St. Louis to outside Philadelphia where the company’s research and development (R&D) was headquartered.

Working for Merck was quite a change from academia. I enjoyed the multidisciplinary team environment, as well as learning industry methods for discovering and developing new drugs. But I also experienced what a lengthy and challenging process this could be. The only neuroscience drug to make it out the door during my five-year employment was Emend, a small molecule neurokinin receptor antagonist for the treatment of chemotherapy-induced nausea and vomiting. A first-in-class drug candidate, it had been created under Les Iversen’s leadership at Terlings Park, and hopes were high that it would open a new dimension in treatments for depression. Unfortunately, the molecule did not show efficacy in large Phase III depression trials. The project team managed to pivot admirably and salvage the program, leveraging dosage information gleaned from human brain PET receptor occupancy studies and observations of anti-emetic effects in ferrets. Emesis clinical trials were quickly successful. Although Emend’s market size was modest by pharma standards, it represented a useful addition to available therapies, and the company received warm letters from grateful cancer patients.

I looked forward to seeing other interesting pipeline drugs also advance. However, one day in late 2004 as I was convening an external expert workshop on Alzheimer’s disease targets, the company’s wires lit up with news that cardiovascular risks of its blockbuster drug, Vioxx, had been confirmed in a major study. Over the next days, Merck pulled Vioxx from the market; as Merck’s stock price tumbled, it embarked on budget reduction, including a sharp downsizing of neuroscience research. I argued that the cost savings of this downsizing were too little to justify its negative impact on future pipelines, but the prevailing view was that neuroscience drug R&D produced a lower return on investment than R&D in some other areas, because of lower success probabilities and longer development times. Research sites in San Diego and Terlings Park were shuttered and not much later I was personally downsized. It meant a lot to me that remaining neuroscience leadership arranged an unofficial dinner to see me off.

During my post-Merck job search, I held a research professorship in the Department of Pharmacology at Boston University, thanks to David Farb, my friend from benzodiazepine days and the department’s chair; as well as a visiting professorship at Oxford, thanks to the medical school dean, Alastair Buchan. I did seriously consider another industry position. After being approached by a search firm, I interviewed for a job as head of R&D for a large biotechnology company. I had completed a required, day-long executive psychological profiling (finding: mostly not crazy) and was negotiating compensation and a relocation package when I read the news that the company had just been acquired by a larger company. I never heard another word about the job (other than a single “hang on” that morning from the search firm) and realized that the recruitment process was no more than cover for the ongoing acquisition.

I subsequently focused my attention on academic jobs, declining an offer to lead neuroscience drug discovery from another pharma, and was delighted when Mike Johns, the head of health sciences at Emory University, suggested that I come there to direct a newly established university-wide neurosciences initiative/institute. Emory had gained a windfall when it licensed the faculty-invented antiretroviral drug, Emtriva, to Gilead for a cash payment of $525 million, enabling it to launch several exciting new initiatives, including in neurosciences. Getting the initiative going was enormous fun, made easy by Emory’s collaborative culture and accomplished faculty. I reported to Mike (and later his successor, Fred Sanfilippo) as well as the provost, Earl Lewis, and had the pleasure of working with many members of the neuroscience community there, including Allan Levey, Ray Dingledine, Charlie Nemeroff, Mahlon DeLong, Helen Mayberg, Tim Olsen, Carolyn Meltzer, Stuart Zola, Greg Berns, Elaine Walker, Don Stein, Paul Wolpe, and Paul Lennard. The initiative emphasized interdisciplinary explorations, including at the emerging interfaces between neuroscience and the humanities or social sciences. Given my medically oriented background, these explorations were particularly fascinating to me. I served as a facilitator at large, with funds to support pilot studies and aid recruitments. To push my own academic comfort zone, I elected to teach a seminar course on artificial intelligence to undergraduates.

However, as the initiative coordinating committee was laying the groundwork for expanding research space and fundraising, the Great Recession of 2007 hit. Emory, well endowed and dependent on endowment income for operating expenses, was highly affected and had to put luxury initiatives, such as the neurosciences initiative, on slow track. To utilize my freed-up effort, Fred Sanfilippo appointed me Vice President for Academic Health Affairs at the health sciences center, responsible for overseeing the academic elements of inter-school centers, such as the Cancer Center, or a contemplated new Vascular Disease Center. This was an excellent job in academic administration, but too removed from neuroscience to be completely fulfilling for me.

I decided then to take an academic leave of absence for two years, generously permitted by Emory, to work for the Simons Foundation in New York City, focusing on their Autism Research Initiative (SFARI). This gave me an opportunity to work on the pleasant, supply-side of the grant business, working with excellent scientific colleagues to identify and support the best studies. I developed admiration for Jim and Marilyn Simons and an appreciation for the major and unique contributions their foundation is making to society in mathematics and biology. Contrary to expectation, speaking as a former Boston-area townie constitutively suspicious of New York City, I ended up liking the city a lot. More important, I met Melanie, an obligate area resident and knew quickly that I had to remain in New York.

Back to Basics: Stony Brook Neurology and Korea Institute of Science and Technology

During my search for a New York position, the new medical school dean at SUNY Stony Brook, Ken Kaushansky, asked Bud Rowland, the former chair of neurology at Columbia University, and me to come in as consultants to evaluate the neurology department at Stony Brook. The previous chair of that department, James Davis, had been tragically killed in a private plane crash, and the department had been under acting leadership for years. Bud and I made the easy recommendation that the institution invest in recruiting a chair and rebuilding the department. Ken offered me the position, and I gladly accepted.

Since joining Stony Brook in 2012, I have worked on expanding both the faculty and the residency. Stony Brook operates the only academic medical center on the eastern two-thirds of Long Island, so the department’s priority is working with network partners to provide appropriate clinical services to the 1.5 million people resident there. To support the department’s predominantly clinical research programs, I have initiated several pilot therapeutic clinical trials in the areas of stroke and autism, using repurposed drugs already approved for use in humans. I continue to serve as a scientific advisor to several companies and will start work again shortly with the Christopher & Dana Reeve Foundation as an advisor.

Besides working at Stony Brook, I recently completed a term as Director of an overseas neuroscience research institute, the Brain Science Institute (BSI) in Seoul, which accordingly supported part of my Stony Brook salary. The BSI is part of the Korea Institute of Science and Technology (KIST), a government-supported research organization predominantly working in engineering and computer sciences. Appointed by KIST President Kil-Choo Moon, I found working at KIST both scientifically and personally meaningful. I especially enjoyed overseeing projects combining biology and engineering, such as one led by Tae Song Kim, YoungSoo Kim, and Kyo Seon Hwang that combined drug administration with a novel microelectromechanical sensor to detect beta amyloid species at femtomolar concentrations. The BSI licensed this technology out to a biotechnology company seeking to develop a blood diagnostic test for Alzheimer’s disease. Being a largely remote director was possible because I had an on-site partner, Dong Jin Kim, an accomplished medicinal chemist and capable leader who concurrently served as Acting Director. At the end of 2016, Dong Jin and I turned leadership responsibilities over to a new BSI Director, Uhtaek Oh. I have agreed to continue working with the KIST BSI and Uhtaek as chair of their external scientific advisory board.

A personal highlight of my time as BSI director occurred in 2016, when KIST celebrated its fiftieth anniversary. KIST was established with resources—even basic building materials were needed—gifted by U.S. President Lyndon B. Johnson, in gratitude for South Korea’s wartime aid in Vietnam. Its subsequent value to the country’s extraordinary industrial and economic growth reflects well on the wisdom of Korean President Park Chung Hee’s original, and apparently unexpected, ask. As part of its commitment, the United States sent over an advisory team contracted from Battelle Memorial Institute, and it turned out that my father Harry was the Battelle engineer selected to lead the U.S. team and help develop initial strategic plans. Harry joined me at KIST for the fiftieth anniversary celebration, and KIST President Byung Gwon Lee presented him with a special award on stage. I had not spent much time since childhood with my father, so this event provided us with a rare opportunity for reflection, bringing us closer.

When in Korea, I also advised a Suwon-based biotechnology company founded by my former postdoc, Byoung Joo Gwag. This company, GNT Pharma, is bringing a version 2.0 NMDA antagonist drug, Neu2000, forward for acute stroke neuroprotection, and has begun initial multicenter efficacy trials in Korea and China. Their candidate drug differs from first-generation candidates in being a weak, fast antagonist with selectivity for the N-methyl-D-aspartate receptor subtype 2B (NR2B), hopefully able to blunt acute excitotoxicity without going too far and facilitating calcium starvation and apoptosis. Their drug additionally incorporates a second mechanism, free radical scavenging, aimed at ameliorating downstream injury pathways and reperfusion injury.

Another promising next-generation NMDA antagonist drug candidate in current development is NA-1, invented by Michael Tymianski at the University of Toronto. NA-1 acts to decouple NMDA receptor activation from free radical generation by inhibiting interactions with postsynaptic density protein 95. It reduced strokes in patients undergoing endovascular repair of cerebral aneurysms and is being tested in a large multicenter stroke trial in Canada.

Closing Thoughts on the Neuroscience Phase of My Life

Although teaching has not been the primary focus of my career, it has been steadily important to me for personal fulfillment and contribution. I am proud of the 50-plus PhD students and postdoctoral fellows that I trained in my lab (the net teaching vector being admittedly reversed in some cases). About half hold senior faculty positions at various universities around the world, many as department heads, division chiefs, or center directors. Other former fellows work as scientists or program officers in industry, research institutes, or foundations. I am also proud of my three grown sons, and perhaps especially so of my oldest son Eric. Since right after his freshman year in college, Eric has struggled with severe bipolar disease and has been hospitalized numerous times for psychotic breaks. Yet, he has managed between hospitalizations to complete college and gain a master’s degree in social work, setting a goal of helping individuals with mental health disorders like himself. My middle son, Alex, is in neurology residency and I hope the Neuroscience Phase of his life turns out to be as good as mine has been. He is off to a strong start and has a brilliant baby daughter. When my youngest son, Jason, was a child, he told me that he thought I worked too hard and would do something completely different, which he has. After enlisting in the U.S. Army and serving as a lieutenant in Iraq, he now works in the financial sector.

I would dearly like to see stronger translation of neuroscience to ameliorate disease impact. I am concerned that the assessment of neuroscience R&D as financially uncompetitive has become a broad pharma trend, as multiple companies have reduced or exited neuroscience over the past several years. These reductions affect the entirety of the neuroscience research ecosystem, including small companies and academia, and lower the probability of needed new drugs emerging sooner rather than later. Ultimately, advances in understanding disease and better drug development processes will prevail, but there are many calls on available budgets and lives are at stake now.

One practical, relatively budget-neutral remedial step that could be taken now is to modify market protection for new drugs. Current U.S. policy, based on patent law, accords the same market protection to a “me-too” drug adding little to current therapies, as it would to a breakthrough drug capable of stopping or reversing Alzheimer’s disease, or limiting stroke damage. In fact, the former would likely have longer market protection, as its clinical testing would likely be faster and burn less time on its chemical entity patent clock. Assigning additional market protection to selected therapies needed by society, but not favored by an industry risk or reward calculus, would encourage private investment in developing these drugs.

Another policy change that might encourage industry to reinvest in neuroscience R&D would be the creation of additional flexibility in regulatory approval mechanisms. The safety, efficacy, and medical impact profile of each therapy is graded and different, yet our current regulatory system offers essentially only a single, all-or-none approval threshold. An “adaptive approval” mechanism (Eichler et al 2012), providing intermediate levels of approval and marketing rights for safe, breakthrough drugs showing promise in late development would allow industry sponsors to gain some limited early income to help defray the costs of final large trials, thereby reducing risk.

Recently, the American Brain Coalition (ABC) has launched a task force to explore these issues and find ways to increase private investment in neuroscience R&D. The ABC is a nonprofit public advocacy organization, with academic society, disease foundation, and industry members, that seeks to understand brain functions and reduce the burden of brain diseases. I have joined this task force, and hope that it can help bring about changes to serve society’s interests.

On a scientific note, I think that the translation of neuroscience discoveries to therapeutics could be enhanced by a couple of paradigm shifts, and I hope to model these in a small way in my own clinical research at Stony Brook. First, more screening of candidate approaches in pilot clinical trials is needed. A plethora of possible therapeutic approaches have been identified by now in myriad laboratories around the world, but animal disease models, which are great tools to dissect disease mechanisms, have recurrently disappointed as predictors of clinical efficacy. Even if industry neuroscience R&D had not been reduced, the conventional pharma approach of exquisitely selecting a few candidate therapies for thorough sequential clinical testing could not do justice to the large pool of ideas now accumulating in the neuroscience community. Utilizing the bandwidth of academic medical centers, disease foundations, and biotechnology companies to conduct an expanded number of pilot trials would increase society’s ability to sift through this stack and identify the most promising approaches for further testing in full-scale trials.

Second, more approaches concurrently targeting multiple disease mechanisms, either with agents designed for this purpose or with drug combinations, are essential. Efforts to treat nervous system diseases to date have overwhelmingly targeted single mechanisms, and as selectively as possible. Although this approach is intellectually satisfying and easier to advance in drug development than combination treatments, the recognition of a growing number of parallel pathogenic mechanisms in the brain injury field is also occurring in other areas. This is not surprising. Many effective therapies for infectious diseases or cancer would fail in monotherapy trials.

Looking back, the Neuroscience Phase of my life has been terrific. It has allowed me to ponder, to contribute, to teach, to meet extraordinary people, and to learn continuously: the proverbial firehose. I have changed duties and venues more than some, but I would not trade the attendant adventures and learnings for a monotonic career. When I consider my first branch point, and the possibility that my career expertise at this moment might have been restricted to effecting quick spark plug changes, I feel deeply grateful for the opportunities that have come my way and to the people who have generously supported me, beginning with grandmother Florence and my parents. Blind good luck also obviously helped me out a lot.

I do not envision ever completely leaving neuroscience, but I am now looking forward to opening a new phase.

References

Benveniste H, Drejer J, Schousboe A, Diemer, NH. Elevation of the extracellular concentrations of glutamate and aspartate in rat hippocampus during transient cerebral ischemia monitored by intracerebral microdialysis. J Neurochem 1984;43:1369–1374.

Bortner CD, Hughes FM, Cidlowski JA. A primary role for K⁺ and Na⁺ efflux in the activation of apoptosis. J Biol Chem 1997;272:32436–32442.

Choi DW. Glutamate neurotoxicity in cortical cell culture is calcium dependent. Neurosci Lett 1985;58:293–297.

Choi DW. Glutamate neurotoxicity and diseases of the nervous system. Neuron 1988;1:623–634.

Choi DW. Calcium-mediated neurotoxicity: relationship to specific channel types and role in ischemic damage. Trends Neurosci 1988;11:465–469.

Choi DW. Calcium: Still center-stage in hypoxic-ischemic neuronal death. Trends Neurosci 1995;18:58–60.

Choi DW. Exploratory clinical testing of neuroscience drugs. Nat Neurosci 2002;5:1023–1025.

Choi DW, Farb DH, Fischbach GD. Chlordiazepoxide selectively augments GABA action in spinal cord cell cultures. Nature 1977;269:342–344.

Choi DW, Koh JY. Zinc and brain injury. Ann Rev Neurosci 1998;21:347–375.

Choi DW, Armitage R, Brady LS, Coetzee T, Fisher W, Hyman S, Pande A, Paul S, Potter W, Roin B, Sherer T. Medicines for the mind: Policy-based “pull” incentives for creating breakthrough CNS drugs. Neuron 2014;84:554–563.

Christine C, Choi DW. Effect of zinc on NMDA receptor-mediated channel currents in cortical neurons J Neurosci 1990;10:108–116.

Church J, Lodge D, Berry SC. Differential effects of dextrorphan and levorphanol on the excitation of rat spinal neurons by amino acids. Europ J Pharm 1985;111:185–190.

Dawson VL, Dawson TM, London ED, Bredt DS, Snyder SH. Nitric oxide mediates glutamate neurotoxicity in primary cortical cultures. Proc Natl Acad Sci 1991;88:6368–6371.

Du C, Hu R, Csernansky C, Hsu CY, Choi DW. Very delayed infarction after mild focal cerebral ischemia: A role for apoptosis? J Cereb Blood Flow Metab 1996;16:195–201.

Eichler HG et al. Adaptive licensing: taking the next step in the evolution of drug approval. Clin Pharm Ther 2012;91:426–437.

Frederickson CJ. Neurobiology of zinc and zinc-containing neurons. Int Rev Neurosci 1989;31:145–238.

Goldberg MP, Weiss JH, Pham PC, Choi DW. N-methyl-D-aspartate receptors mediate hypoxic neuronal injury in cortical culture. J Pharm Exp Ther 1987;243:784–791.

Hill MD et al. for the ENACT trial investigators. Safety and efficacy of NA-1 in patients with iatrogenic stroke after endovascular aneurysm repair (ENACT): A phase 2, randomised, double-blind, placebo-controlled trial. Lancet Neurol 2012;11:942–950.

Koh JY, Suh SW, Gwag BJ, He YY, Hsu CY, Choi DW. The role of zinc in selective neuronal death after transient global cerebral ischemia. Science 1996;272:1013–1016.

Lee JM, Zipfel GJ, Choi DW. The changing landscape of ischaemic brain injury mechanisms. Nature 1999;399:A7–A14.

McCord MC, Aizenman, E. Convergent Ca²⁺ and Zn²⁺ signaling regulates apoptotic Kv2.1 K⁺ currents. Proc Nat Acad Sci 2013;110:13988–13993.

McDonald JW, Bhattacharyya T, Sensi SL, Lobner D, Ying HS, Canzoniero LM, Choi DW. Extracellular acidity potentiates AMPA receptor-mediated cortical neuronal death. J Neurosci 1998;18:6290–6299.

Mcdonald JW, Althomsons SP, Hyrc KL, Choi DW, Goldberg MP. Oligodendrocytes from forebrain are highly vulnerable to AMPA/kainate receptor-mediated excitotoxicity. Nature Med 1998;4:291–297.

Monyer H, Hartley DM, Choi DW. 21-Aminosteroids attenuate excitotoxic neuronal injury in cortical cell cultures. Neuron 1990;5:121–126.

Olney JW. Brain lesions, obesity, and other disturbances in mice treated with monosodium glutamate. Science 1969;164:719–721.

Rothman S. Synaptic release of excitatory amino acid neurotransmitter mediates anoxic neuronal death. J Neurosci 1984;4:1884–1891.

Simon RP, Swan JH, Griffiths T, Meldrum BS. Blockade of N-methyl-D-aspartate receptors may protect against ischemic damage in the brain. Science 1984;226:850–852.

Tang CM, Dichter M, Morad M. Modulation of the N-methyl-D-aspartate channel by extracellular H⁺. Proc Natl Acad Sci 1990;87:6445–6449.

Watkins JC, Jane DE. The glutamate story. Brit J Pharmac 2006;147:S100–S108.

Yu SP, Canzoniero LM, Choi DW. Ion homeostasis and apoptosis. Curr Opin Cell Biol 2001;13:405–411.

Yu SP, Yeh CH, Sensi SL, Gwag BJ, Canzoniero LMT, Farhangrazi ZS, Ying HS, Tian M, Dugan L, Choi DW. Mediation of neuronal apoptosis by enhancement of outward potassium current. Science 1997;278:114–117.

Joseph T. Coyle

BORN:

Chicago, Illinois

October 9, 1943

EDUCATION:

College of the Holy Cross, Worcester, MA, BA (1965)

Johns Hopkins School of Medicine, Baltimore, MD, MD (1969)

Intern in Pediatrics, Johns Hopkins Hospital (1970)

Postdoctoral Fellowship, National Institute of Mental Health (1973)

Residency in Psychiatry, Phipps Clinic, Johns Hopkins Hospital (1976)

APPOINTMENTS:

Assistant Professor of Pharmacology, Johns Hopkins University (1974–1978)

Assistant Professor of Psychiatry, Johns Hopkins University (1976–1978)

Associate Professor of Pharmacology and Psychiatry (1978–1980)

Professor of Neuroscience, Psychiatry and Pharmacology, Johns Hopkins University (1980–1991)

Director of the Division of Child Psychiatry, The Johns Hopkins Hospital (1982–1991)

Distinguished Service Professor of Child Psychiatry, Johns Hopkins University (1985–1991)

Chairman of the Consolidated Department of Psychiatry, Harvard Medical School (1991–2001)

Eben S. Draper Professor of Psychiatry and Neuroscience, Harvard University (1991–present)

HONORS AND AWARDS (SELECTED)

A.E. Bennett Award in Basic Science, Society for Biologic Psychiatry (1978)

John Jacob Abel Award, American Society for Pharmacology and Experimental Therapy (1979)

Foundation’s Fund Prize for Research, American Psychiatric Association (1985)

Elected to the Institute of Medicine (National Academy of Medicine) (1990)

President, Society for Neuroscience (1991)

William McAlpin Award Research Achievement Award, National Mental Health Association (1992)

Elected Fellow, American Academy of Arts and Sciences (1994)

Elected Fellow, American Association for the Advancement of Science (2005)

Axelrod Prize, Society for Neuroscience (2013)

The Rhoda and Bernard Sarnat International Prize in Mental Health, National Academy of Medicine (2017)

Joseph Coyle began his career in research as a medical student in the laboratory of Solomon Snyder, MD, at Johns Hopkins School of Medicine in 1968. His early research with Snyder and as a postdoctoral fellow with Julius Axelrod at the National Institute of Mental Health focused on the synthesis and inactivation of catecholamines and the development of neurotransmitter systems in the rat brain. While completing his residency in psychiatry at Hopkins, he established his laboratory and began studies on excitotoxic lesions, developing animal models of Huntington’s disease and Alzheimer’s disease. He identified the degeneration of the basal forebrain cholinergic neurons as an early lesion in Alzheimer’s disease and a contributor to the memory deficits in the disorder. For nearly a decade, he served as the director of the Division of Child Psychiatry at Hopkins. In 1991, he moved to Harvard Medical School where he served as the chairman of the Consolidated Department of Psychiatry for a decade. His most recent research has focused on the role of glutamatergic N-methyl-D-aspartate receptors in the pathophysiology of schizophrenia and related severe mental disorders.

Joseph T. Coyle

Introduction

I want to thank Larry Squire and Tom Albright for inviting me to contribute to this volume of The History of Neuroscience in Autobiography. It is a great honor to be included in this series of autobiographies by esteemed neuroscientists. Also, the invitation is particularly timely as it was precisely 50 years ago when as a third-year medical student at Johns Hopkins I began an elective research quarter in the psychopharmacologic laboratory of Solomon H. Snyder. The intervening years seem to have gone by too quickly. But, the opportunity to write these reflections made clear to me that my life in neuroscience research and psychiatry can be best summarized by chance events of unappreciated significance at the time, the generosity of mentors and colleagues, excellent trainees who taught me so much, and a wonderful family that kept me grounded.

The Early Years

I came from a family of physicians. My mother’s father was a small-town doctor in Iowa, who attended Rush Medical School in Chicago after emigrating from Luxembourg. My father, the son of a train conductor, worked his way through college and medical school at the threshold of the Great Depression and became an orthopedic surgeon (Coyle 1951; Voris and Coyle 1952¹). Two uncles and two cousins also became physicians. So, I was probably destined to go into medicine. But, I never gave it much thought as I was growing up on the south side of Chicago.

In retrospect, I was probably a bit odd as a child. I was not particularly interested in playing sports in spite of the fact that during my adolescence my father was the team physician for the Chicago White Sox, a major league baseball team. I was more interested in how things worked: taking a clock apart at age six, playing with my Gilbert Chemistry set at 10, raising a Polyphemous moth from a caterpillar at 12, and struggling with my assignments for the J. W. Ellwood’s School of Taxidermy’s correspondence course at 14. Adolescence found me in a Jesuit high school hewing to their centuries-honed approach to education—ratio studiorum—that extended over the next eight years through college at Holy Cross in Worcester, Massachusetts. This curriculum entailed five years of classical Greek, six years of Latin, and eight years of French. In addition, my college years were laden with philosophy and theology courses, so that technically I was a French and philosophy major. The science courses required for medical school were painfully dull, mainly concerned with the memorization of mind-numbing facts or conducting canned experiments. The transformative college experience for me was the year that I spent as a student at the Sorbonne, going from a very parochial life at Holy Cross to a very cosmopolitan one in Paris. The return for my last year of college in Worcester was quite painful.

At my interview with the admissions committee at Johns Hopkins Medical School, I was asked whether I had any experience with research. To some puzzled looks, I confidently responded in the affirmative: I did my senior thesis on Samuel Beckett, the Irish playwright, who wrote exclusively in French (later a Nobel Laureate in Literature). Stepping back now, in spite of this naivety about what they really meant by “research,” I am convinced that this eight-year immersion in literature, languages, and philosophy was extraordinarily helpful in developing the ability to think critically and to communicate effectively during my scientific career. Of course, the experience also greatly transformed my view of the world and solidified my interests in art, music, and literature.

During the summer between college and medical school, I took a position as a psychiatric orderly at the local community hospital because I was vaguely interested in psychiatry as a result of my readings of Freud, Lacan, and Sartre. After a few weeks, the older brother of my closest childhood friend was admitted to the ward with his first episode of schizophrenic psychosis. Soon, I became enmeshed in his paranoid delusions. I then saw psychosis as the ultimate epistemological conundrum: “what one knows and how does one know it.” His thinking had been hijacked by solipsistic (mis)perceptions: paranoid delusions and auditory hallucinations. This experience cemented my decision to focus on psychiatry in medical school as it seemed to blend epistemology, humanism, and medicine.

Medical School

Having only a rudimentary background in science in college, I struggled during the first two years of medical school, barely managing a C+ grade point. Nevertheless, the introductory course to psychiatry in the first year was an extraordinary experience, in spite of the fact that it took place on Saturday mornings. Lecturers included Leon Eisenberg (the founder of social medicine), Jerome Frank (a pioneer in subjecting psychotherapy to objective research), Robert Cooke (the chairman of pediatrics, who had two children with cri du chat syndrome), Horsley Gantt (one of the last students of Pavlov), Seymour Kety (who applied rigorous genetic analysis to schizophrenia), and Curt Richter (the discoverer of circadian rhythms). Contrary to my expectation, the course spent little time on psychoanalytic theory, portraying it as one psychological intervention among many, but rather emphasized scientific and evidence-based approaches to psychiatry.

The second year opened with the pharmacology course. Several lectures were allocated to a new faculty member, Solomon Snyder, who was also a resident in psychiatry, to cover the nascent subspecialty of psychopharmacology. The topics included stimulants, antidepressants, antipsychotics, and hallucinogens. He reviewed the research on how these drugs exert their effects by altering chemical neurotransmission in the brain. The obvious implication of this research was that the etiology of serious mental disorders did not derive from psychological disturbances but rather from biochemical abnormalities. So, I chose to write my pharmacology term paper on the etiology of schizophrenia covering the twin studies showing high heritability to the more ephemeral findings, such as the purple spot in urine and taraxein. The epigram that I chose to set the tone for the paper was from Bob Dylan’s album, Highway 61 Revisited: “you know something is happening here but you don’t know what it is, do you, Mr. Jones.” Fortunately, we have made some progress over the past 50 years.

I sought out Dr. Snyder to ask whether I could spend the elective quarter in my third year in his laboratory (my second year elective quarter and summer were already committed to a 20-week externship in pathology). He was pleased to have me, not the least because the extra hands would be quite helpful since he was preoccupied with his psychiatric residency training. The focus of research in the laboratory was characterizing the pharmacology of neurotransmitter transporters in the brain. Julius Axelrod, with whom Snyder had just completed a postdoctoral fellowship at the National Institute of Mental Health (NIMH), had recently demonstrated that antidepressant drugs act by inhibiting the neuronal reuptake of norepinephrine, thereby potentiating its action at the synapse, a finding that resulted in the Nobel Prize in 1970 (Axelrod 1971). The primary assay for neurotransmitter uptake used finely chopped rat brain tissue suspended in buffer, which would then be allocated to small beakers containing the radioactive neurotransmitter and drugs dissolved in artificial cerebrospinal fluid (Snyder et al. 1968).

My initial task in the lab was to screen psychotropic medications for their ability to inhibit the uptake of [³H]norepinephrine. I soon realized that substantial variability was introduced in the assay by the fact that the chopped tissue tended to settle in the pipette, resulting in the early beakers getting more tissue than the later beakers. In a biochemistry laboratory assignment in my first year to study metabolism in dissociated fat cells, I stumbled on some articles discussing how brain tissue could be homogenized in sucrose; and with differential centrifugation, metabolically active “pinched-off nerve endings” or synaptosomes could be isolated (Gray and Whittaker 1962; de Robertis et al. 1962). I asked Sol if I could try this synaptosome preparation for the transport studies. The preparation had a uniform “milky” appearance, and intra-assay variability declined dramatically, leading to my first peer-reviewed publication (Snyder and Coyle 1969). That this seemingly minor technical advance came from my insight was quite gratifying. Science was no longer boring; it was fun and exciting. Thus, this 10-week experience in Sol’s laboratory dramatically altered the trajectory of my life because he allowed me the freedom to experience the joy of discovery.

Over the last two years of medical school, I spent 12 months in Sol’s laboratory, part of which was funded by the Denison Research Scholarship, a real boon as my father had recently passed away. The scholarship covered half my tuition. I successfully petitioned the dean to allow me to continue in the laboratory for another quarter instead of taking a second surgical rotation in the fourth year. Sol was on “sabbatical” in the Maudsley laboratory of Professor Henry McIlwain, the inventor of the eponymous tissue chopper that was replaced in the Snyder lab with synaptosomes. So, my supervision was conducted by mail and phone calls in this pre-e-mail era. In studying the characteristics of catecholamine transport in synaptosomes in various brain regions, I noticed some anomalies between the striatum, the brain region that receives a very dense dopaminergic innervation, and the rest of the brain, which receives noradrenergic innervation (Coyle and Snyder 1969). Dopamine transport did not exhibit stereoselectivity in striatal synaptosomes in contrast to [³H]norepinephrine uptake in the cortex. At Sol’s urging, I screened a large number of drugs that were used to treat Parkinson’s disease, many of which were muscarinic acetylcholine receptor antagonists. Benztropine among others clearly differentiated [³H]dopamine transport by striatal synaptosomes from transport for [³H]norepinephrine in other brain regions receiving noradrenergic but not dopaminergic innervation. Published in Science, this was the first description of the dopamine transporter, DAT (Coyle and Snyder 1969).

In the second year of medical school, a fellow student from my Paris days, who lived in Washington, DC, invited me to a party at her house. Attending the party was this beautiful, smart, and poised woman, Genevieve Sansoucy, who was working on a master’s degree in clinical social work at Catholic University. I could not forget her. Several months later, my friend invited me to her own wedding; and, thankfully, Genevieve Sansoucy was in attendance. I took her to Baltimore for Chesapeake Bay hard-shell crabs for our first date. We were married in the summer of 1968 and took up residence in a fifth-floor apartment on Mount Vernon Place in Baltimore. Within eight years, we went from a couple to a family with three fine sons: Peter, Andrew, and David.

Having enjoyed my rotation in pediatrics but also discouraged by my experience with internal medicine rotations, which were dominated by patients suffering primarily from the consequences of poor life choices (drugs, alcohol, tobacco), I decided to pursue postgraduate training in pediatrics before doing a residency in psychiatry. I also applied for a postdoctoral position in the Public Health Service at the National Institutes of Health (NIH). This position would satisfy my military service requirements, and thus I could avoid being drafted into the armed services at the height of the Vietnam War, which I strongly opposed. At NIH, I was invited to interview with Julius Axelrod, Floyd Bloom, Erminio Costa, and the Nobel Prize Laureate Marshal Nirenberg. I accepted Julius Axelrod’s offer for a position in his laboratory, to begin after my pediatric internship at Johns Hopkins Hospital.

Postdoctoral Training

Starting in Julie’s laboratory after my internship was a challenging experience because he took his vacation during July. This meant that the new postdoctoral fellows had to tag along with established fellows to learn what they were doing and thus get a real sense of the methods and projects of the laboratory. I helped Perry Molinoff (currently professor of pharmacology at the University of Pennsylvania) in his project to purify dopamine-β-hydroxylase (DBH), the final enzyme in the synthesis pathway for norepinephrine, to homogeneity from beef adrenals. This was my introduction to protein purification and characterization, which was a strength of the Axelrod laboratory. While this project ultimately failed after Perry’s departure, I successfully revisited it when I started my own laboratory at Hopkins, purifying rat adrenal DBH to homogeneity and raising an incredibly avid and specific antisera (Grzanna and Coyle 1976; Grzanna et al. 1978).

Because of my interest in development, I decided with Julie’s approval to study the development of the catecholaminergic systems in the rat brain as there was virtually no published information on the maturation of transmitter-specific neuronal systems in the brain, especially antenatally. The project was consistent with the catecholaminergic orientation of the laboratory and took advantage of Julie’s skills in enzymology but brought a new developmental perspective to the laboratory. A major challenge was to increase the sensitivity of existing assays by ten- to a hundredfold to reliably measure noradrenergic markers as early as 14 days gestation in the rat brain. We were able to show that the synaptosomal uptake of [³H]norepinephrine, the activity of tyrosine hydroxylase, the rate-limiting step in the synthesis of norepinephrine, and the activity of DBH all appeared at 15 days gestation, a particularly primitive stage of brain development in the rat when the cerebral cortex is in the earliest stages of formation (Coyle and Axelrod 1971, 1972a, 1972b).

Collaborating with David Henry, a fellow in the late Irwin Kopin’s Laboratory, we established the most sensitive assay at the time for measuring norepinephrine by exploiting catechol-O-methyl transferase, an enzyme discovered by Julie, to transfer a [³H]methyl moiety from S-adenosyl methionine ([³H]SAM) to norepinephrine; the product was separated from the [³H]SAM by differential extraction with organic solvents, another of Julie’s strategies (Coyle and Henry 1973). As with the other presynaptic markers, norepinephrine appeared in the rat brain at 15 days gestation, suggesting that it might play a role in modulating forebrain development (Coyle 1977). Based on the simultaneous appearance of all four presynaptic markers, we predicted that the locus coeruleus, the primary noradrenergic nucleus in the brain, was formed by 15 days gestation. This proposal was subsequently validated by [³H]thymidine autoradiography (Lauder and Bloom 1974).

Julie was an extraordinary mentor (Coyle 2005). Julie’s government-issued steel desk was strategically placed in the laboratory where it was 4 feet from the reagent scale and 10 feet from the scintillation radioactivity counter so that every fellow would have to chat with him when either starting or finishing an experiment. Julie made sure his fellows were visible in the field. Every fellow presented a slide talk at the annual meeting of the American Society for Pharmacology and Experimental Therapeutics, which was the scientific meeting of the year. Julie would turn down seminar invitations and recommend a fellow to speak in his stead. Julie would give fellows journal articles to review. After he felt confident in the quality of these reviews, he would let the fellow sign the review so that soon the journal was soliciting reviews directly from the fellow. Once, I wrote a sarcastic review of what was a weak scientific manuscript. Julie caught me at the reagent scale and said, “Joe, a scientific article is like the scientist’s child. You shouldn’t attack it. Be constructive with your criticism.” I learned humility from a Nobel Prize winner.

Julie taught us that the best science is not simply confirming your hypotheses but watching out for the anomalous results that may point to novel insights and new, productive avenues of inquiry. He suggested that the way to succeed in a research career was to identify an important problem on which few were working. “Life is too short to study uninteresting problems.” He encouraged us to be aggressive in our research: “Be the firstest with the mostest.” He bridled a bit at the introduction of statistics into data analysis, commenting: “If you have to do a t-test to prove something is different, it probably isn’t important.” This skepticism about statistics resulted from his uncanny ability to pose experimental questions with such clarity that the results were unequivocal. But, he always repeated the experiment to confirm the reliability of the finding.

Getting Started at Hopkins

During the last year at NIMH, I needed to find a residency in psychiatry. Although several residency programs expressed interest, Johns Hopkins offered the best opportunity for jump-starting a research laboratory. Paul Talalay, the chairman of pharmacology, working with Joel Elkes, the chairman of psychiatry (clearly facilitated by Sol Snyder) offered to appoint me as an assistant professor of pharmacology when I started the second year of psychiatric residency and to provide start-up funds and laboratory space. The first person that I hired for the laboratory in 1975 was Rob Zaczek as a technician. A graduate of Towson State University, he was working in the steel mills in East Baltimore. Rob turned out to be brilliant in the laboratory and got it functioning while I was distracted with my psychiatric residency. After serving several years as the senior technician in my laboratory, he completed a PhD in pharmacology with me (Zaczek et al. 1987b) and went on to become the head of neuroscience discovery at Bristol-Meyer Squibb.

Sol kindly referred to me an Austrian postdoctoral applicant to his laboratory, Robert Schwarcz, PhD. Robbie did not have fellowship support and sold his father’s stamp collection to cover his salary initially. I later learned that both of his parents were Holocaust survivors in Austria, who had lost several family members in the concentration camps. My first RO1 ($26,000 direct costs) was funded after a Floyd Bloom site visit to ensure that my laboratory was adequately equipped to carry out the proposed studies. The gist of my grant was to use cultured chick retina to characterize dopaminergic neuronal differentiation as a model for schizophrenia. While in the >Axelrod laboratory, I published the first description of culturing dopaminergic neurons (Coyle et al. 1973). Robbie took on this project and demonstrated the presence of a dopamine-sensitive adenylyl cyclase along with dopamine and tyrosine hydroxylase but not dopamine-beta-hydroxylase in the retina, confirming the presence of retinal dopaminergic neurons (Schwarcz and Coyle 1976).

The retinal project was soon eclipsed by the discovery of in situ excitotoxicity, which arose out of the confluence of two events. While I was in Julie’s laboratory, one of his former postdoctoral fellows, Les Iversen, visited from Cambridge and gave a seminar on his postmortem neurochemical study of Huntington’s disease (HD). He found a selective degeneration of striatal intrinsic GABAergic neurons with sparing of the dopaminergic afferents and axons passing through the striatum (Bird and Iversen 1974). In early 1976, Frode Fonnum gave a seminar to the Hopkins Pharmacology Department on the neurotoxic effects to the neonatal rat retina of systemic treatment with glutamate (Karlsen and Fonnum 1976), presumably mediated by the excitatory effects of the glutamate that accumulated in the eye (Olney et al. 1969). The two seminars prompted an epiphany for me: Could direct injection of a potent glutamate receptor agonist into the rat striatum replicate the pathology of HD?

Mike Kuhar, PhD (currently the Candler Professor of Neuropharmacology at Emory University School of Medicine), another one of the Sol-trained junior faculty members in the department, was developing a ligand binding assay for excitatory glutamate receptors using the very potent agonist, [³H]kainic acid, as the ligand. Mike was able to provide us with kainic acid for our studies. Two μg of kainic acid injected into the striatum caused the rat to rotate away from the side of the injection for 24 hours. Measurement of presynaptic markers for the striatal GABAergic neurons, glutamic acid decarboxylase (GAD), and for cholinergic neurons, choline acetyl transferase (ChaT), revealed marked reductions at 48 hours after injection, whereas the marker for the dopaminergic terminals, tyrosine hydroxylase, was actually increased by 100 percent. These preliminary findings supported our hypothesis of neuronal cell body selective and axon sparing effects of in situ injection of a potent glutamate receptor agonist. In short order, Robbie and I published a detailed letter in Nature describing the dose response, time course, cellular specificity, and histolopathology of the striatal kainite lesion (Coyle and Schwarcz 1976). We proposed that dysfunction of glutamatergic neurotransmission might account for the neurodegeneration in HD and related neurodegenerative disorders.

Development of Neurotransmitter Systems

Because little was known about the development of specific neurotransmitter systems in the brain, I continued to pursue this line of investigation in my laboratory at Hopkins. With Sam Enna, a senior postdoc in Sol’s laboratory with expertise in GABAergic neurochemistry, we characterized the developmental expression of γ-aminobutyric acid (GABA), its synthetic enzyme GAD, the GABA-A receptor and [3H]GABA transport. Similar to the noradrenergic system, GAD, GABA, and the GABA-A receptor were detectable in the last third of gestation in the rat brain but showed major increases in close synchrony after birth, plateauing at four weeks postpartum. Collaborating with Hank Yamamura in Sol’s laboratory, we found that accrual of presynaptic markers for cholinergic neurons and their postsynaptic muscarinic receptors exhibited the most delayed pattern of development.

Although histofluorescent microscopy suggested low innervation of the rat neonatal cortex by aminergic neurons, this seemed inconsistent with my findings of the very early formation of the aminergic nuclei and the presence of presynaptic markers in the fetal neonatal cortex. To address this question, I established a collaboration with the late Mark Molliver, MD, a faculty member in the Department of Anatomy. Mark was clinically trained in neurology and was a superb classical neuroanatomist. We hypothesized that this discrepancy was due to the fact that aminergic terminals were deficient in neurotransmitter. To reveal their presence, we treated neonatal rats with 5-hydroxydopamine (5HODA), which is selectively taken up by and concentrated in the vesicles of aminergic terminals and converted to an electron dense precipitate with fixation for electron microscopy (Coyle and Molliver 1977). Although in the early postnatal period the total density of synapses was quite low, a striking 30 percent exhibited aminergic characteristics after treatment with 5HODA. This synthesis-storage capacity was confirmed by treatment with L-3,4-dihydroxyphenylalanine, which produced a twentyfold increase in cortical catecholamines in a reserpine-sensitive compartment (reserpine blocks vesicular storage of amines).

With the incredibly avid and specific antiserum against homogeneously purified DBH developed by Reinhard Grzanna in my laboratory, Mark, Reinhard, and I embarked on another very productive collaboration around characterizing the anatomy of the noradrenergic innervation of the cortex. By using the peroxidase-anti-peroxidase (PAP) immunocytochemical method, the noradrenergic neurons were revealed in their Golgi-like entirety so that cell bodies, dendrites, and axons could be traced in thick sections (Grzanna et al. 1978). John Morrison with his blond Afro was conducting his thesis research in Mark’s laboratory, which focused on the intracortical trajectory and organization of the noradrenergic projections. He showed that the dorsolateral cortex is innervated by fibers in the medial forebrain bundle that wrap around the frontal pole, running occipitally in the deep layers. This pattern indicates that noradrenergic fibers have the capacity to modulate a vast expanse of cortex in a tangential manner (Morrison et al. 1978, 1979, 1981). John went on to become the dean for research at Mount Sinai School of Medicine. The PAP technique was extended to electron microscopy and revealed that, contrary to expectations, nearly 60 percent of the noradrenergic axonal varicosities formed axodendritic synapses with specialized appositions, indicating restricted synaptic contacts (Olschowka et al. 1981).

Mike Johnston joined the laboratory after completing his military service and his residency in pediatrics and pediatric neurology, an unusually late start for a research career for someone who ultimately became an outstanding translational neuroscientist on developmental disabilities, a professor of neurology at Hopkins, and the chief medical officer at the Kennedy Krieger Institute. The difference in the times of neurogenesis for different populates of neurons suggested a novel way to selectively lesion neuronal populations based on the time of neurogenesis. Methylazoxy methanol (MAM) is a sort-lived DNA alkylating agent that kills mitotic cells. We timed treatment with MAM to late in gestation when brainstem and pyramidal neurons had already completed mitosis, whereas the GABAergic neurons in the ventricular germinal zone were actively dividing.

Treatment of pregnant rats at 15 days gestation with a single dose of MAM results in severe cortical hypoplasia in the offspring. The cortical volume is reduced by nearly 70 percent, primarily because of the loss of cortical GABAergic neurons as evidenced by the reduction in total GAD activity and GABA levels (Johnston et al. 1979a). We were surprised to find that the total innervation of the cortex by noradrenergic terminals was virtually unchanged. DBH immunocytochemistry revealed that the noradrenergic axons were “compressed” to a much greater density within the atrophic cortex and their pattern of innervation was disrupted. More extensive studies suggested that the cholinergic innervation of the cortex was also of extrinsic origin, as the concentrations of presynaptic markers were increased in the hypoplastic cortex (Johnston and Coyle 1979). We found that the severity of the lesion and the site of GABAergic deficits could be determined by the date of administration of MAM. Notably, with fetal administration, the cerebellum appeared to develop normally, whereas treatment postnatally with MAM when granule cells were in mitoses produced severe hypoplasia of the cerebellum resulting from loss of granule cells (Slevin et al. 1982).

The parallels between the fetal MAM lesion in the rat and schizophrenia did not go unnoticed by me (Coyle and Johnston 1980). Early imaging studies were revealing ventricular enlargement and cortical atrophy in schizophrenia (Johnstone et al. 1976) similar to what is seen in the MAM lesion. Also, early postmortem studies revealed significant reductions in cortical GABAergic markers (Spokes, 1979) similar to the MAM lesion. Furthermore, the striatum was also reduced in volume, thereby increasing the density of dopaminergic terminals, consistent with the hypothesized hyperfunction of forebrain dopamine in causing psychosis in schizophrenia (Beaulieu and Coyle 1981). However, I could not get much traction with this model of schizophrenia with NIMH review committees as schizophrenia was considered a “functional” disease. As a consequence, I discontinued the project after nearly 20 publications. Forty years later, the MAM lesion is considered to be one of the more robust models of schizophrenia pathology (Grace 2016).

Excitotoxicity

After Robbie and I discovered the selective neurotoxic effect of in situ injection of kainic acid, I knew that we needed to move rapidly to characterize its mechanism of action, limitations, and possibly better agonists. Following Julie’s dictum (“be the firstest with the mostest”), I wrote up the project as an RO1 using the prior research on the catecholaminergic neurotoxin, 6-hydroxydopamine, as a template. This was one of the best grant applications that I have written, and it was funded on the first round by the National Institute of Neurological Disorders and Stroke with a very high priority score.

We obtained some structural modifications of kainic acid and showed that there was a close correspondence between reported excitatory potency of the analogues and excitotoxicity with striatal injection. (Schwarcz et al. 1978). Strikingly, reduction of the side chain resulted in complete loss of activity, whereas extension of the side chain as in domoic acid, a deadly toxin released from algae, increased toxicity by threefold (Schwarcz et al. 1978). One of the effects of intracranial injection of kainic acid was that the rats developed limbic seizures with forepaw stereotypies and retropulsion. Rob Zaczek developed a method for quantifying seizures (Zaczek et al. 1986). Using the electroencephalography, he showed that the subtle head shakes and streotypies exhibited by the rats after kainite injection masked severe limbic seizures, which were associated with widespread neuronal death in the hippocampus and pyriform cortex. Although the convulsant effects of kainite analogues correlated with neurodegeneration in the limbic system, such proconvulsant effects were not observed with quisquate, N-methyl-D-aspartate (NMDA), and ibotenate, which produced small uniform lesions. These disparities were consistent with the emerging evidence of three families of glutamate-gated cation channels: NMDA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and kainite receptors (Zaczek and Coyle 1982).

We were able to obtain [3H]kainic acid of high specific radioactivity to carry out ligand binding. Edye London, PhD, on whose PhD thesis committee at the University of Maryland I had sat, joined my laboratory as a postdoctoral fellow and accepted this project. She demonstrated that [3H]kainic acid bound to a high- and a low-affinity site. In retrospect, the structure-activity relationships of the former are consistent with the kainite receptor, whereas the latter was likely the glutamate transporter, GLT1. The highest concentration of the high-affinity sites was in the striatum and the lowest concentration was in the medulla and cerebellum. After a striatal kainite lesion, receptor binding was virtually unaffected a week postlesion when intrinsic neurons were cleared; but by four weeks, the high-affinity site was reduced by 64 percent. This delayed clearance probably reflects the predominant presynaptic localization of the kainite receptor in the striatum and delayed retraction of afferents (Jin and Smith 2011).

Because kainite is secreted as a toxin from the seaweed digenea simplex and is ascaricidal, Edye examined the phylogenetic distribution of the kainite receptor. High-affinity [3H]kainite binding sites had a broad phylogenetic distribution in the nervous system, including in planaria, earthworm, dogfish, chicken, and human but were undetectable in hydra (London et al. 1980). Edye went on become an accomplished human brain imager and an expert in the neurobiology of substance abuse. She currently is the Thomas and Katherine Pike Professor of Addiction Studies in the Department of Pharmacology at the University of California, Los Angeles.

A French neurologist from Tours, France, Kathleen Biziere, MD, joined my laboratory and continued the elucidation of the mechanism of kainite toxicity. She found that removing the cortex overlying the striatum protected against kainite toxicity within hours of the lesion. The cortical lesion caused a substantial reduction in glutamate in the synaptosomal fraction as well as in [3H]-glutamate uptake in the striatum, consistent with a massive loss of a glutamatergic projection to the striatum. In support of this hypothesis, injection of 1 µmole glutamate with 9 nmole of kainite into the decorticate striatum restored the toxicity of kainite (Biziere and Coyle 1979). These finding were consistent with the presynaptic localization of kainite receptors, which caused endogenous glutamate release.

The interaction between kainite and glutamate in neurotoxicity was supported in acute striatal slices incubated in vitro. Adenosine triphosphate (ATP) levels were used as an index of neurotoxicity. Although 10 mM glutamic acid modestly depressed ATP levels in the striatal slices, the addition of low concentrations of kainite, which itself does not reduce ATP, markedly potentiates the effect of glutamate (Biziere and Coyle 1978). We directly addressed the presynaptic effects of kainate in stimulating endogenous glutamate and aspartate release in perfused slices of cerebellum, striatum, and hippocampus (Ferkany et al. 1982). Kainate (0.5 mM) was as effective as 40 mM K+ in releasing endogenous glutamate and aspartate. Notably, glutamate release was unaffected by tetrodotoxin, unlike 40 mM K+, but was Ca++ dependent, pointing to a presynaptic site of action of kainate, as action potentials were not involved.

Peter Campochiaro was a Hopkins medical student, who took a research rotation in my laboratory. He undertook a project to characterize the development of striatal neuronal vulnerability to kainate. The seven-day-old rat showed minimal vulnerability, whereas three-week-old rats exhibited near adult vulnerability. Striatal vulnerability paralleled the postnatal increase in [3H]kainate high-affinity binding, synaptosomal uptake of [3H] glutamate, and endogenous glutamate levels (Campochiarro and Coyle 1978). Peter took a residency in ophthalmology and a neuroopthalmology fellowship, returning to my laboratory for his research requirement, characterizing neurotransmitter disposition in the retina. He is currently the Eccles Professor of Ophthalmology and Neuroscience at Hopkins and a world-recognized expert on macular degeneration (Campochiaro 2015).

The term “excitotoxin” posits that kainite and related ionotropic glutamate receptor agonists kill neurons by overwhelming depolarization, thereby depleting their energy supplies through persistent activation of Na+ K+ ATPase. To test this hypothesis, we had to establish a full battery of microassays for high-energy phosphates and adapted a microwave oven so that the microwaves were focused on the rat brain so that it reached more than 100°C in less than a second to instantaneously stop metabolism (Retz and Coyle 1982). Thirty minutes after the striatal injection of kainite, there were significant reductions in phosphocreatine, ATP, and glucose and elevations in adenosine diphosphate (ADP) and adenosine monophosphate (AMP). By 2 hours, ATP had fallen by 32 percent, adenosine phosphates by 20 percent, and glucose by 56 percent, whereas AMP increased by 60 percent and lactate by 44 percent. These results were consistent with the hypothesis that excitotoxins killed neurons by profound energy depletion.

By the early 1980s, the “generic” glutamate receptor had been pharmacologically dissected into three distinct subtypes: kainite, AMPA, and NMDA receptors. The proconvulsant effects accounted for the very uneven neuropathology of kainic acid. Robbie Schwarcz pioneered the use of NMDA receptor agonists for making more uniform lesions. He showed the striking differences between the effects of kainic acid and ibotenic acid injected into the rat hippocampus in cases in which kainate exhibited a very uneven vulnerability of neurons in contrast to the uniform lesion caused by ibotenate (Kohler et al. 1979). Ibotenate did not cause seizures and other morbidity associated with kainate, perhaps because of its metabolism to the GABA-A receptor agonist, muscimol, thereby limiting excitatory diffusion (Curtis et al. 1979). In situ injection of an excitotoxin, increasingly ibotenic acid, has replaced electrolytic lesions to identify the role of specific nuclei, because of the axon-sparing effect of the excitotoxin lesion, thereby eliminating the confound of damage to axons of passage or termination (Coyle 1985). After thirty years, the excitotoxin method for selective pathway lesioning is now used without citation to its origins.

Alzheimer’s Disease

In the 1970s, evidence was accumulating that senility, long accepted as a normal consequence of aging, in fact, was a disease (Roth 1980). The brains of the elderly with senility exhibited the same neuritic plaque and neurofibrillary tangle pathology as presenile dementia or Alzheimer’s disease (AD). The notion of selective neuronal vulnerability in neurodegenerative disorders was solidified with postmortem neurochemical studies on Parkinson’s disease and HD (Bird and Iversen 1974). In 1977, a few brief reports appeared describing selective reduction in the presynaptic marker for cholinergic neurons, ChAT, in the cerebral cortex but no change in the GABAergic presynaptic marker GAD in AD (Davies and Maloney 1976; Perry et al. 1977). The inference of cholinergic involvement in AD was supported by the finding that the muscarinic acetylcholine receptor antagonist, scopolamine, replicated the memory deficits of AD in healthy volunteers (Drachman and Leavitt 1974). Given that AD was considered to be a prototypic cortical dementia, it was unclear whether these cholinergic deficits reflected cholinergic neuronal death in the cortex or elsewhere.

The basal forebrain nucleus stains intensely for acetyl cholinesterase (AChEs) and sends fibers to the cortex, prompting Lewis and Shute (1967) to propose it as the major source of cholinergic innervation. However, many noncholinergic neurons stain intensely for AChEs, and McGeer et al. (1974), using antiserum purported to be selective for ChAT, reported that ChAT was confined to cortical neurons, supporting the notion that the cortex was the primary site of pathology in AD. Given our interest in neurodegenerative disorders, we felt that the excitotoxin lesion method could resolve these uncertainties (Johnston et al. 1979b). We first made exploratory electrolytic lesions in various potential sources of cholinergic innervation of the cortex, including the thalamus, and found that only the lesion in ventral pallidum of the rat cause a 45 percent reduction of ChAT activity in the ipsilateral cortex. We then made a kainite lesion in the basal forebrain in the ventral pallidum that caused a striking loss of the AChEs-stained neurons in the basal forebrain and selective 50 percent loss of ChAT activity, acetylcholine, and [3H]-choline uptake and loss of AChEs staining in the ipsilateral cortex. We concluded: “studies directed at understanding the pathogenesis of (AD) … might profitably be directed towards the cholinergic neurons in the basal forebrain.” (Johnston et al., 1979, p. 5396).

Don Price, MD, the head of neuropathology, was just across the street. With Peter Whitehouse, a young neurologist, we decided to look at the nucleus basalis of Meynert in a subject who died with a clinical diagnosis of AD. We found a profound loss of the large multipolar neurons with the remaining ones laden with neurofibrillary tangles (Whitehouse et al. 1981). We published in Science a follow-up postmortem study involving five controls and five subjects with a clinical diagnosis of AD. Consistent with the preliminary report, we reported an 80 percent loss of the large neurons in the nucleus basalis. This was “the first example of loss of a transmitter-specific cell population in a major disorder of higher cortical function” (Whitehouse et al. 1982). The findings were quite surprising because AD was the prototypical “cortical dementia“; yet, the results indicated that a critical lesion was located in the midbrain. We found that loss of the nucleus basalis cholinergic neurons also occurred in dementia pugilistica, which is now known as chronic traumatic encephalopathy or CTE (Uhl et al. 1982). With Don Price, MD, and Mahlon DeLong, MD (who later won the Lasker Award for electrophysiologically characterizing the circuitry exploited for deep brain stimulation in Parkinson’s disease), we then published a highly cited review (more than 2,000 citations) on AD as a disorder of cortical cholinergic innervation, linking together the cortical pathology with senile plaques, the selective loss of cortical cholinergic markers, degeneration of cholinergic nucleus basalis, and the memory-disrupting effects of cholinergic antagonists (Coyle et al. 1983).

Collaborating with David Olton, PhD, who unfortunately died young of pancreatic cancer at the age of 51, we characterized the memory impairments resulting from ibotenate lesions in the nucleus basalis magnocellularis (NBM) and the medial septal area (MSA) in the rat (Hepler et al. 1985). The NBM lesion caused a selective reduction in ChAT in the frontal cortex, whereas the MSA lesion caused a selective reduction of ChAT in the hippocampus. The four tasks—T-maze, radial arm maze, active avoidance, and passive avoidance—differed in response-reinforcement contingencies. Nevertheless, regardless of the lesion site, the performance of the lesioned rats was significantly impaired for all four of the memory tasks, indicating the important role of these midbrain cortical cholinergic projections for memory. The impact of the cholinergic denervation of cortex with an NBM ibotenate lesion was confirmed by the 30 percent reduction in glucose consumption (London et al. 1984), similar to what had recently been described in subjects with AD (Friedland et al. 1983).

To better understand the molecular determinants of the risk for AD, I collaborated with John Gearhart, PhD, and Mary Lou Oster-Granite, PhD, in the Department of Physiology, who were studying a mouse model of Down syndrome (DS). DS, which results from trisomy of chromosome 21, is associated with cognitive limitations, but of particular relevance is the fact that all DS individuals exhibit the neuropathology of AD, including the cortical cholinergic deficits by the age of 40 (Yates et al. 1980; Price et al. 1982). The gene encoding the precursor protein for amyloid A-beta, APP, is located on human chromosome (HSA) 21 in the so-called Down’s region; it maps to mouse chromosome 16 in a region that has synteny with the human DS region on HSA 21 (Reeves et al. 1987). As the TS16 mice die by birth, we focused on prenatal development of the NBM and found that neurogenesis for the TS16 fetal NBM AChEs-positive neurons peaked two days earlier than in littermate wild-type (WT) mice. Furthermore, at the end of neurogenesis of the NBM, the TS16 mice had many fewer AChEs-positive cells than did littermate controls (Sweeney et al. 1989a).

We also used tissue culture to study postnatal maturation of the NBM in TS16 mice (Corsi and Coyle 1991). We dissociated the NBM of TS16 and WT fetuses at 15 days gestation and grew the cells in completely defined medium. In the TS16 NBM cultures, there were fewer ChAT-positive neurons, and these neurons were smaller, and emitted fewer processes, which were simpler and smoother. The addition of nerve growth factor to the cultures resulted in more and bigger ChAT-positive TS16 neurons with processes that formed varicosities. These results were replicated in the DN mouse, which has a much more restricted triplication of the DN region of HSA 21 (Kleschevnikov et al. 2012). These studies on the TS16 mouse were my first foray into genetic approaches to neuroscience and opened my eyes to new, more powerful methods for understanding brain disorders (Bendotti et al. 1988).

Forty years ago, I met Ken Davis, MD, who is now the president of Mount Sinai Health System in New York City, when he was an assistant professor of psychiatry at Stanford. At the time, he was doing pioneering studies on the cognitive enhancing effects of the AChEs inhibitor, physostigmine, in normal adults and in AD patients (Davis and Mohs, 1982; Davis et al. 1983). His wife, Bonnie, an endocrinologist, scoured the scientific literature to find the best AChEs inhibitor for treating AD while she stayed at home raising their two children. She identified galantamine, a natural product isolated from snowdrop bulbs, which was used in various “tonics” in Eastern European medicine. Bonnie asked whether I could determine its ability to reverse the cognitive deficits in the NBM lesion model of AD.

I had a smart, enthusiastic student, who was going to do her PhD thesis in my laboratory and had already worked on the NBM during an elective rotation. Joanne Sweeney, who is now the president of Trinity College in Hartford, showed that galantamine treatment reversed the memory deficits in the Morris water maze caused by a prior ibotenate lesion of the NBM (Sweeney et al. 1988). She found that galantamine had a relatively long effect on memory in the NBM-lesioned mice of more than six hours after a single dose, whereas it showed a mirror effect on control mice, inhibiting their performance (Sweeney et al. 1989b). The results of these animal studies served as the basis for carrying out successful clinical trials by Janssen that resulted in galantamine (Reminyl) being approved as a treatment for AD. However, galantamine differs from other U.S. Food and Drug Administration–approved AChEs inhibitors because it also acts as a positive allosteric modulator of α-7 nicotinic acetylcholine receptors, which may contribute to its efficacy (Coyle et al. 2007).

Oxidative Stress

A popular assay for a glutamate receptor was the quisqualate-sensitive, chloride-dependent “binding” of [3H]glutamate to brain homogenates at 37°C (Foster and Fagg 1984). We and other laboratories used this “quisqualate receptor” assay in many published studies without question. However, Rob Zaczek was troubled by the peculiar features of this purported receptor-binding assay and took on the task of deconstructing the “receptor” as his thesis project. He showed that it was in fact a Cl⁻ dependent antiporter, exchanging glutamate for cysteine and a primary mechanism for the synthesis of the antioxidant, glutathione (Zaczek et al. 1987a, 1987b). Tim Murphy, a graduate of St Mary’s College and world-class wind-surfer, pursued this issue further as his thesis project. He showed that blocking the antiporter caused oxidative stress that could be mitigated by treatment with antioxidants or by drugs that induce antioxidant defenses. Immature neurons were particularly vulnerable (Murphy et al. 1989, 1991). Tim subsequently became professor of psychiatry at the University of British Columbia.

With Nancy Simonian, MD, a postdoctoral fellow and clinically trained neurologist, we explored whether oxidative mechanisms might also explain excitotoxicity. We had hints of this as Masa Miyamoto, PhD, a visiting scientist in my laboratory from Takeda Pharmaceuticals, found that idebenone, a potent centrally active antioxidant, protected against kainite toxicity in the striatum (Miyamoto and Coyle 1990). Nancy, who later became the chief scientific officer at Millennium Pharmaceuticals, showed that kainite caused neuronal apoptosis secondary to oxidative stress (Simonian et al. 1996). In 1991, after I was elected president of the Society for Neuroscience (after serving as program chair, treasurer, and councilor), I was invited by Science to write a review article on a topic of my interest. Given our findings and those of others, I chose to review oxidative stress in neurodegenerative disorders, emphasizing the role of glutamate (Coyle and Puttfarcken 1993). This article proved to be the most highly cited (more than 2,900 times) in my career because it is still relevant after more than 25 years.

NMDA Receptor Modulation

Although understanding the pathophysiology of schizophrenia seemed to me to be the “great white whale” of psychiatric research, it took some fortuitous events to draw me into this focus during the latter third of my research career. Because the structural determinants of kainite receptor binding involved an unsaturated side chain extending beyond the primary glutamate structure (London and Coyle 1979), we hypothesized that the endogenous ligand might be a polypeptide containing glutamate. Rob Zaczek proceeded to purify acidic peptides from rat brain by ion exchange and high-performance liquid chromatography using the Tris-HCL buffer [3H]-glutamate binding assay (“quisqualate receptor”). He isolated N-acetyl-aspartyl-glutamate (NAAG), a peptide previously described by Italian neurochemists in horse brain (Zaczek et al. 1983). Randy Blakely, the first PhD candidate in the nascent neuroscience doctoral program at Hopkins, was carrying out his thesis research in my laboratory. While N-acetylaspartyl-[3H]glutamate appeared to bind to the quisqualate receptor, Randy showed that in fact the [3H]NAAG was cleaved by a quisquale-sensitive peptidase to [3H]glutamate, which was then efficiently concentrated into glutamatergic synaptosomes (Blakely et al. 1988a, 1988b). Randy developed highly specific antiserum to NAAG linked to bovine serum albumin by carbodiimide and showed that NAAG was concentrated in forebrain glutamatergic neurons (Blakely et al. 1987; Ory-Lavollée et al. 1987). Subsequent studies revealed high concentrations of NAAG in the locus coeruleus, NBM, compacta dopaminergic neurons, and motor neurons (Tsai et al. 1993). Randy is now head of the Florida Atlantic University Brain Institute.

Mike Robinson, PhD, a postdoctoral fellow, who later became a professor of pediatrics at University of Pennsylvania, working with a doctoral student, Barbara Stauch (Slusher), purified the peptidase to homogeneity from rat brain (Robinson et al. 1987). We then raised an antiserum for immunocytochemistry and were surprised to find that it was expressed on the surface of astrocytes (Slusher et al. 1992; Berger et al. 1999). Ruth Carter (Luhti), who grew up in Kansas and is now a professor of neuroscience at Leicester University in England, moved to Harvard with me in 1991 to carry out her thesis research on the cloning and molecular characterization of rat N-acetyl-L-aspartyl-L-glutamate peptidase (NAALADase). This was new territory for the laboratory, but she succeeded with our rat antibody to identify a clone. Sequencing revealed that the human homologue to human prostate-specific membrane antigen (PMSA), a protein highly expressed on the surface of metastatic prostate cancer cells, was the same as NAALADase (Carter et al. 1996). Then, Chuck Halstead at the University of California, San Francisco, contacted us because the amino acid sequence of our protein matched the sequence of a protein fragment of folate hydrolase 1, a gut enzyme that cleaves off the polyglutamate tail from dietary folate for absorption (Halstead et al. 1998). The gene is now known as FOLH1.

Emil Tsai, MD, a Taiwanese psychiatrist, was pursuing his Hopkins PhD thesis in neuroscience in my laboratory. He had been working on the NAAG project and decided to carry out a postmortem study on NAAG, glutamate, and NAALADase in the brains of subjects who died with schizophrenia and matched controls because clinical pharmacologic studies suggested that NMDAR antagonists produce a syndrome resembling schizophrenia, including the cognitive and negative symptoms not seen in stimulant-induced psychosis (Krystal et al. 1994). He found reduced NAALAdase activity in the cortex and hippocampus, reduced glutamate levels, and elevated NAAG in the hippocampus (Tsai et al. 1995). Indirect evidence suggested that NAAG was an NMDAR antagonist, a proposal that was supported by elegant electrophysiologic studies performed by my former postdoctoral fellow, Richard Bergeron, MD, PhD, and currently professor of psychiatry at the University of Ottawa (Khacho et al. 2015).

My Clinical Life

Isolating my clinical experiences from my research career is artificial but may be less confusing to the reader. For, at my core, it is difficult to separate my interest in how the brain works (albeit focusing primarily on one corner: glutamaterigc mechanisms) and how it doesn’t work in neuropsychiatric disorders. Both roles stimulated research questions that, not surprisingly, overlapped.

The 1969–1970 pediatric internship at Hopkins went by in a blur with the brutal three-day rotation: 24 hours on, next day on until the care of your assigned patients is complete (typically around 8:00 P.M.) and then off at 5:00 P.M. on the third day. Every other weekend, we were on duty. Exhaustion was a constant, so that I would fall asleep whenever I sat down (once in the bathtub). There was no phlebotomy team then. The intern would arrive before rounds to draw bloods for the necessary tests. The residents one to two years removed in experience supervised an intern, who was clinically quite naïf. The motto was “watch one, do one, teach one.” Nevertheless, with the layers of oversight from intern, to assistant resident, to chief resident, and finally to attending faculty, I think that the care was excellent.

Certain clinical experiences stick with me. On the neonatal intensive care unit (ICU), we were treating a 1,000 gm premature infant born to a 14-year-old girl. Although he had been in the ICU for weeks, no family member had visited. The infant had been successfully resuscitated from several cardiac arrests but clearly sustained major brain damage. Given the circumstances of likely lifelong disability and no family support, the attending recommended a “Do not resuscitate” order and a “DNR” sign on the incubator. Several days later, the chairman of pediatrics, Robert Cooke, MD, made rounds on the floor, saw the DNR sign, and became quite angry, saying, “Take down that sign. At Hopkins we treat children, we don’t kill them.”

At the time, the treatment of childhood cancers was quite primitive. Children three to six years old would be admitted with leukemia, looking normal, and then would die from an overwhelming infection weeks later. One of my patients was a 10-year-old boy, who had no recorded visitors since his admission but was dying of end-stage lymphoma. I sat with him as he expired so he wouldn’t be alone. Another young girl presented in the emergency room with a painful leg mass and a note from her local physician (“I can do nothing”). She soon died of metastatic osteosarcoma. All of these conditions are now curable. These deaths of children were a reality hard to accept but an impetus for some of my fellow interns to take a deep dive into cancer research. After internship, to keep up my clinical skills and to obtain the patient contact that I enjoyed, I volunteered at an outpatient clinic in Anacostia, a poor African American community in southeast Washington, DC, while I was a postdoctoral fellow in the Axelrod laboratory at NIH.

My three-year residency in psychiatry at Hopkins presented some challenges because I also joined the faculty as an assistant professor of pharmacology in the second year. While I was at NIH, the American Board of Psychiatry and Neurology changed the requirements for psychiatry, ruling that an internship was no longer needed because “psychiatry was so far removed from medicine.” To me, this was the nadir for American psychiatry as it became “brainless” in the words of Leon Eisenberg (1986). Being four years older and much more clinically experienced than my fellow first-year residents, I found that I could accomplish my clinical responsibilities more efficiently so that I was able to free up time to set up my laboratory.

I did not shirk my clinical training. One of the highlights for me that stood me in good stead throughout my career was the T-group run by Kenneth Artis, MD, who supervised therapeutic groups for the clinical staff at the National Cancer Institute (thereby reducing burnout and suicide). The seminar was built around reading theoretical articles on group dynamics; and our resident discussion group served as an incubator where the group dynamics played out in real life. Another memorable experience was my long-term, insight-oriented psychotherapy patient for which I received intense supervision from a psychoanalyst. She was a single mother, who was employed as a court reporter, a position that paid well. In my first year of residency, she started weekly hour-long psychotherapy sessions with me for panic attacks. Her attacks increased progressively in intensity and frequency. She developed agoraphobia, causing missed work and leading to her termination. As a consequence of her unemployment, she had to apply for welfare to support herself and her daughter. In spite of her worsening condition, she was committed to the psychotherapy, and she and my supervisor felt that she was making progress with insights into the causes of her anxiety. Then, I discovered a recently published paper demonstrating the efficiency of imipramine for treating panic attacks and agoraphobia (Zitrin et al., 1978). My supervisor opposed treatment with imipramine as he believed that it would disrupt the therapeutic alliance. My patient however, agreed to try the drug, and within a few weeks her symptoms began to melt away.

As I was completing my residency, I was involved in the initial evaluation and treatment of a young woman experiencing her first psychotic episode of schizophrenia. A bright, athletic, and a quite attractive adolescent, she was a senior in a private high school. But, her thinking was very disturbed, and she was experiencing auditory hallucinations. I treated her as an outpatient, except for an occasional crisis requiring hospitalization, for the next 15 years. She responded reasonably well to antipsychotic drugs, but her hallucinations did not disappear. She simply ignored them when doing well. It was distressing to observe the gradual coarsening of her appearance and the erosion of her social skills as negative and cognitive symptoms emerged over time, components of schizophrenia unresponsive to neuroleptics and little noted at the time. Long-term treatment relationships reveal the true course of disease, not cross-sectional “snap-shots.”

After completing residency in 1976, I became an assistant professor of psychiatry in addition to my pharmacology appointment. My laboratory was up and running with two postdoctoral fellows, a technician, an R01, and a Career Development Award. Paul McHugh, the chairman of psychiatry, required all psychiatry faculty to take on a clinical responsibility. I chose to run the Chronic Treatment Clinic (CTC), in which residents provide outpatient treatment for schizophrenic patients. This resident-run clinic had no faculty oversight because these patients were not viewed as very intellectually challenging. To me, they were the essence of psychiatry: individuals struggling with symptoms that disrupted their emotions, cognition, and relationships with others, who needed the best treatment that we could provide.

With the recent formulation of the dopamine hypothesis for schizophrenia (Snyder 1976), I felt that by using neuroscientific methods we could optimize antipsychotic treatment. We exploited the ability of drugs in serum to compete with and inhibit [3H]-ligand binding to a receptor, based on the affinity of the drug for the receptor of therapeutic interest, regardless of structure, to measure serum drug levels. Serum antipsychotic levels were measured using [3H]spiroperdol as the ligand for the D₂ dopamine receptor (Tune et al. 1980a). Anticholinergic drug levels were measured by their displacement of [3H]quincyclindyl benzoate from muscarinic acetylcholine receptors (Tune and Coyle 1980). Although we were able to optimize neuroleptic doses, with some caveats (Tune et al. 1980b), and minimize cognitive impairments, most patients remained severely impaired, estranged from their families and unemployed.

In 1981, Paul McHugh, the chairman of psychiatry, asked me to become the director of the Division of Child Psychiatry, which had languished since its last director, Leon Eisenberg moved to Harvard several years before. Because virtually all child psychiatry programs in the country were dominated by psychoanalytic theory, I thought that by building a program based on developmental neurobiology with a focus on serious mental disorders in children, we could transform the field. Richard Ross, MD, the dean at the time, raised substantial funds in support of my vision. Over the next several years, we created two inpatient units for severely ill children and adolescents (13 beds each) designed with the assistance of James Harris, MD, to provide the optimal therapeutic environment. Our residency expanded from a couple of foreign medical graduates per year to attracting top American medical school graduates, many of whom went on to academic careers, such as Joseph Piven, MD, who is now the Thomas E. Castelloe Distinguished Professor of Psychiatry, Pediatrics, and Psychology, and Director of the Carolina Institute for Developmental Disabilities at the University of North Carolina; and Maryland Pao, MD, the deputy director of the NIMH Intramural Research Program.

By the end of the 1980s, my career seemed to be going quite well. I was elected president of SfN (effective 1991), elected to the Institute of Medicine of the National Academy of Sciences, and was named nationally as “Top Doc” in both child psychiatry and geriatric psychiatry. The laboratory was well funded with productive projects on the neurobiology of AD, Down syndrome, and excitotoxicty. However, clouds were gathering on the horizon. Managed care, which ravaged psychiatry from the late 1980s through the late 1990s, severely cut income for clinical services. This income underwrote the academic mission of the division. Maryland Medicaid drastically reduced reimbursement to $15.00 per day per patient for clinical care on our inpatient units in spite of reimbursing the hospital for its entire “expenses” (about $1,000/day). So, in spite of our nationally recognized success in developing a scientifically grounded program in child psychiatry and a growing NIH grant portfolio, the hospital refused to offer assistance, unlike most academic hospitals that reimbursed psychiatry departments for managing inpatient units because they were quite profitable to the hospital. After I left, the hospital agreed to subsidize the salaries of the psychiatrists on the inpatient services for the next director.

Dan Tosteson, MD, the dean at Harvard Medical School, had approached me on a couple of occasions to head a subdepartment of psychiatry at Harvard Medical School (historically, clinical departments were managed by their affiliated hospitals at Harvard). I demurred because of the almost comical rivalry among the subdepartments evident during residency recruitment, which undermined the credibility of their programs in the eyes of Hopkins applicants. In 1991, he enticed me to serve as the chairman of the Consolidated Department of Psychiatry, bringing together the academic programs in the nine clinical departments of psychiatry affiliated with Harvard Medical School. This was underwritten with a $20 million commitment over a decade by the participating hospitals to support the academic mission.

With this commitment, we reorganized the residency training, condensing six competing adult residency-training programs into three thematically differentiated programs with a single application form. The six child psychiatry residencies were merged into three with a single core curriculum. The medical student curriculum, historically dependent on the idiosyncrasies of the nine hospital departments, was reorganized with clear objectives and evidence-based teaching so that all students could be subjected to the same test of their knowledge. Over the decade, external research funding to psychiatry grew nearly fourfold to more than $65 million per year with faculty members affiliated with different hospitals collaborating for the first time. These educational and research initiatives are still in place to this day.

I managed to maintain my laboratory, which continued to compete successfully for NIH grants, but I knew that after 10 years of major administrative responsibilities I had lost a few steps: I was the master of 20th-century neuroscience, but we were now in the 21st century where molecular approaches reigned supreme. I signed up for the Woods Hole Neurobiology Course, a nine-week course divided into three-week trimesters focused on molecular biology, electrophysiology, and imaging. The course leaders were incredulous (acceptance by postdoctoral fellows was highly competitive), because they assumed that I just wanted to kick back and enjoy the Cape. I swore that I would be a “full” student and would not miss any classes; and they accepted me. It was a very intense experience, starting with three hours of seminars in the morning followed by labs that extended to 10:00 P.M. or later; and it was a bit humbling living in a dormitory room (but I snuck my wife in on weekends). The 11 other students were extremely talented and diverse. We still stay in contact. And the faculty was unbelievable in their generosity; tops in their fields but spending hours providing hands-on supervision to this small group of students. This experience gave me the energy, experience, and confidence to move to the next stage of my scientific career that took a much more molecular approach.

With the freedom to pursue research on a full-time basis after finishing my administrative responsibilities for an academic department containing more than 1,600 members, I did want to maintain a clinical “presence.” Cathy DeAngelis, a long-time friend from my Hopkins days, was the editor of JAMA and was also responsible for the Archives family of journals. She called me in some panic in October 2001, because the current editor of the Archives of General Psychiatry (AGP) had tendered his resignation, and she needed a replacement as soon as possible. AGP had been the “journal of record” in psychiatry for decades, maintaining the highest five-year citation impact in the field because it published substantive articles “with legs” as they were cited long after the two-year window of the Institute for Scientific Information’s rankings. I joined the editorial board in the 1980s when Danny Freedman, MD, was the editor. I saw this as another opportunity in which the neuroscience perspective could be brought to bear on this important journal, although I was scientifically omnivorous about psychiatry, recognizing the importance of epidemiology, health services research, and medical anthropology. I accepted Cathy’s offer and started January 1, 2002.

The journal was still being run entirely with paper. So, in late December, we received about 25 cartons of old manuscripts under review, unprocessed recent submissions, and correspondence. My editorial assistant, Fran MacNeil, worked tirelessly to organize the materials so we could proceed. I decided that until I fully grasped the process, I would assign all reviewers (e-mailing invitations to about six possible reviewers and going with the first four) and evaluate all reviews for the editorial decision. AGP could publish only about 140 manuscripts a year because of the fixed number of pages, meaning that our acceptance rate was less than 15 percent of submissions. As time went on, I tried to identify important trends. I think that we were ahead of the curve on the reassessment of the prevalence of autism and its genetic and environmental determinants, inflammation and psychiatric illness, and late-life depression as a risk factor for dementia and biomarkers for AD.

JAMA had a long tradition of having art on its cover whereas AGP had the table of contents for the issue, which was informative but not visually attractive. I enlisted my long-time friend and child psychiatrist from Hopkins, James Harris, MD, to do the covers. He created Art and Images in Psychiatry; the cover of each issue had a reproduction of a painting and an essay linking the art to issues relevant to psychiatry. For the associate editor, I selected Stephan Heckers, MD, whom I had recruited into our psychiatric residency while he was doing a postdoctoral fellowship with neuroanatomist Marcel Mesulam, MD, PhD. Stephan applied his neuroanatomic expertise to brain imaging and had made some significant discoveries. We were complementary. Using Isaiah Berlin’s metaphor, Stephan was the hedgehog digging down to get the facts right, and I was the fox looking over the landscape for something new and transformative. The partnership worked very well, and he ultimately replaced me as editor.

Closing in on Schizophrenia

Given our findings of an elevated endogenous NMDAR antagonist, NAAG, in postmortem schizophrenic brains (Tsai et al. 1995), findings of elevated kynurenic acid levels in their brains (Schwarcz et al. 2001), and the clinical observations that dissociative anesthetics like ketamine reproduced the full spectrum of symptoms of schizophrenia (Krystal et al. 1994), I finally felt like I had a “hook” on the fundamental pathophysiology of the disorder. Free of administrative responsibilities, I decided that the most effective way to proceed was to organize a group of basic and clinical investigators with shared interests in the “NMDA receptor hypothesis of schizophrenia” to apply for a NIMH Conte Center, a new grant mechanism that fostered translational and interdisciplinary research. We focused on the NMDA receptor and the hippocampus. The first attempt did not receive a fundable priority score because it was “too diffuse” and “lacked sufficient expertise in hippocampal physiology.” Our resubmission included Stephan Heckers, MD, for hippocampal imaging; Robbie Greene, MD, PhD, for hippocampal NMDA receptors; Don Goff, MD, for NMDA receptor clinical trials; Howard Eichenbaum, PhD, for hippocampal memory; Mike Hasselmo, PhD, to head a computational core; John Lisman, PhD, for hippocampal physiology; and myself. NMDA receptor modulation was successful, and the Conte Center was ultimately funded at $20 million for 10 years.

Instead of the typical scientific advisory board, I requested that we use the funds for an annual retreat at which we would focus on a particular aspect of the hypothesis and bring in outside experts to present and to participate in discussions. John Lisman hosted these retreats at Brandeis and, on occasion, had the dinners at his lovely condo overlooking the Charles River. With his infectious curiosity and gregarious personality, John evolved into the “soul” of the Conte Center and worked to bring together the disparate findings into a consistent model. This led to his leading a consensus article on a circuit-based approach for understanding neurotransmitter and risk gene interactions in schizophrenia that was published in Trends in Neuroscience and has been cited more than 500 times (Lisman et al. 2008).

I had reservations about pharmacologic models of schizophrenia, such as chronic ketamine treatment (the brain adapts), MAM lesion (GABAergic neurons are down-regulated and not lost), or postnatal stress (a nonspecific risk factor for depression, anxiety disorders, and schizophrenia). Therefore, I decided to use a molecular approach by genetically silencing serine racemase (SR), the enzyme that synthesizes D-serine (Basu et al. 2009). Previous studies indicated that D-serine was a coagonist at forebrain NMDARs and was synthesized in astrocytes, being the prototypic “gliotransmitter” (Schell et al. 1995). Thus, genetically silencing SR should result in forebrain NMDA receptor hypofunction.

The meandering path on which this research took us reaffirmed the power of Julie’s admonition: “follow the results.” Using commercially available antibodies against SR, we confirmed its forebrain localization and the loss of SR immunoreactivity in SR-/-mice (Basu et al. 2009). I assigned my new postdoctoral fellow, Mike Benneyworth, PhD, to use a conditional knockout strategy to ascertain the relative contribution of neurons and glia to the expression of SR. Given the abundant literature on the glial localization of SR, we chose the inducible glial knockout strategy first. Over several months, in spite of increasing doses of tamoxifen and varied durations of treatment, the inducible knockout of SR in astrocytes produced simply small to negligible effects on SR levels. Reluctantly, we turned to the CamK-promoter-driven Cre recombinase, which was neuron selective. We found a 65 percent reduction in SR (Benneyworth et al. 2012), indicating that SR was expressed primarily in neurons.

We found an overlooked article from Mori’s laboratory that used SR knockout mice to control for immune specificity and demonstrated that SR was expressed in forebrain glutamatergic and GABAergic neurons but not in astrocytes (Miya et al. 2008). We replicated their findings on SR expression with our SR-/-controls and found that astrocytic “D-serine immunoreactivity” was intense in the SR-/- mice under published conditions for blocking L-serine cross-reactivity when the levels of D-serine were less than 10 percent of WT. Increasing the concentrations of blocking L-serine hundredfold revealed D-serine staining only in neurons as it vanished from astrocytes (Balu et al. 2014).

In a very productive collaboration with Dan Liebl, PhD, we were able to show that SR was indeed expressed in astrocytes but in A1 reactive or toxic astrocytes (Liddelow et al. 2017) that appear after traumatic brain injury (TBI). TBI results in cognitive impairment by seven days after the insult when the SR-expressing astrocytes are prominent in the hippocampus (Perez et al. 2017). Using our inducible astrocyte selective knockout, we showed that the cognitive impairment resulted from D-serine release from the A1 astrocyte, because silencing SR expression only in astrocytes prevented the cognitive impairment. Thus, SR was indeed expressed in astrocytes, but not in resting astrocytes in the normal brain.

Articles continued to appear in high-impact journals concluding that astrocytes were the primary source of D-serine. Together with Herman Wolosker, a visiting scientist from Technion Institute, who originally cloned SR (Wolosker et al. 1999), and Darrick Balu, we published a perspective in Trends in Neuroscience that described the many artifacts that led scientists to the misperception that D-serine is a gliotransmitter (Wolosker et al. 2016, 2017).

Postmortem studies in schizophrenia have revealed consistent brain pathology, including atrophy of cortical pyramidal neurons, down-regulation of the parvalbumin-positive (PV+) GABAergic neurons, oxidative stress, and reduction in neurotrophic pathways (Steullet et al. 2017). Darrick led a series of studies to characterize the phenotype of the SR-/- mouse, focusing on the males, which were more severely affected, consistent with the lower severity and later onset of schizophrenia in females. These studies showed a reduction in dendritic complexity, total dendritic length, and spine density of pyramidal neurons in the frontal cortex, primary sensory cortex, and hippocampus that would result in a reduction of approximately 30 percent of cortical glutamatergic synapses (Balu et al. 2012, 2013). The actual degree of cortical and hippocampal volume loss was significant but small (about 4 percent), comparable to what is observed in schizophrenia. It is surprising how this subtle volume loss masks the serious degree of disconnection first predicted by Seymour Kety (Coyle et al. 2016). The SR-/- mice also showed the stigmata of oxidative stress and the down-regulation of the cortical PV+GABAergic neurons similar to schizophrenia (Steullet et al. 2017). The SR-/- mice exhibited memory deficits in several domains. Intracranial self-stimulation studies indicated a profound reduction in hedonic state. In vivo dialysis showed a significantly elevated basal release of dopamine in the ventral striatum, consistent with the hyperdopaminergic state associated with psychosis. Thus, the parallels in the phenotype of the SR-/- mouse and pathology of schizophrenia were striking.

After much of this research had been completed, the results of the largest genome-wide association study (GWAS) in schizophrenia comprising 110,000 controls and nearly 40,000 subjects with schizophrenia were published (Schizophrenia Working Group of the Psychiatric Genomics Consortium 2014). The results supported the hypothesis that schizophrenia was a disorder of complex genetics with multiple risk alleles of modest effect interacting with the environment, thereby causing the disorder (in terms of individualized medicine, schizophrenia consists of multiple gene-based disorders with overlapping phenotypes).

I was not surprised that only a few of the “usual subjects,” candidate genes for the dopamine hypothesis, showed up in the GWAS. This failure of the candidate gene approach, popular in the first decade of the 21st century, resulted from underpowered studies, yielding misleading results (Johnson et al. 2017). However, as was pointed out in the analysis of genes localized to highly penetrant copy number variants (Kirov et al. 2012), genes encoding proteins associated with the glutamatergic synapse were quite well represented in the GWAS. We showed that eight genes encoding proteins like SR either modulated NMDA receptor function or mediated down-stream consequences of NMDA receptor activation (Balu and Coyle 2015). The impact of epistatic interactions of gene products adversely affecting glutamatergic neurotransmission is not difficult to envision, resulting in the schizophrenic phenotype.

Comment

The convergence of neuroscientifically generated hypotheses based on clinical and postmortem findings and the GWAS results sparks new confidence that the field is on the right track for deciphering the many etiologies of this disorder that we call schizophrenia and related serious mental disorders. However, I have been disabused of the belief that answers will emerge quickly. My early involvement in HD and AD research filled me with optimism that once we found the risk genes, effective treatments would rapidly emerge. Contrary to this assumption, 25 years after identifying risk genes for HD, AD, and amyotrophic lateral sclerosis (from which my editorial assistant, Fran, died), we still have no treatments. If the “low-hanging fruit” of autosomal dominant mutations are not amenable to rapid solutions, the common psychiatric disorders with their complex genetics face log-unit more challenges. Perhaps, as in oncological research, a “tipping point” in understanding will be reached that results in a burst of therapeutic advances.

At the close of my career, I should hazard some insights to guide the next generation if they happen upon this autobiography. After nearly 50 years, I still find Julie Axelrod’s insights particularly helpful. I believe that his admonition to pay particular attention to the finding that is inconsistent with your hypothesis to be particularly valuable, and one that I have emphasized to my trainees. Rob Zaczek’s deconstructing the “quisqualate receptor,” which undermined the conclusions of many of ours and others’ publications, led us to the discovery of FOLH1. More important, Rob did not feel constrained by a “must be right theme” that dominates many laboratories. Julie’s admonition comports nicely with the fundamental argument of Karl Popper in The Logic of Scientific Discovery that the function of research is to disprove hypotheses and thus get closer to an approximation of reality.

When I started on my career in research, I assumed that science was transparent and self-correcting. I have learned that there is, in fact, a complex social culture of science that determines to a great extent what appears to be important and correct at the time (see Thomas Kuhn, The Structure of a Scientific Revolution). My most recent experience with this phenomenon is the controversy over the localization of serine racemase and its product, D-serine. Several years after we have demonstrated both to be localized to neurons using rigorous immunocytochemical (Balu et al. 2014) and molecular techniques (Benneyworth et al. 2012), high-impact journals continue to publish studies claiming to demonstrate a purported glial localization based on flawed methods (for review, Wolosker et al. 2016).

I feel extraordinarily blessed that society has granted me the resources to pursue a career in scientific research and to gratify my need to explore the unknown. I believe that I have created useful knowledge that will ultimately lead to improved treatments of brain disorders. But, as I grow older, I have come to appreciate the complexity of these conditions and fear that meaningful help is still years to come. I know that my thirst for new knowledge, and new insights into how the brain works, will not be dimmed for a while, but I will miss having the tools and the resources to directly participate in the process of discovery, the wonderful “ah-ha” experience that I first felt 50 years ago.

Finally, the really important issues: Genevieve and I are celebrating the 50th anniversary of our marriage. She retired after a nearly 40-year career as a psychotherapist. She has now become a skilled sculler, an accomplished potter, and a political advocate. We continue to be surprised by each other. Our sons are married and are pursuing satisfying careers of their own. And, we have two beautiful grandchildren.

References

Axelrod J. Noradrenaline: fate and control of its biosynthesis. Science. 1971 Aug 13;173(3997):598–606.

Balu DT, Basu AC, Corradi JP, Cacace AM, Coyle JT. The NMDA receptor co-agonists, D-serine and glycine, regulate neuronal dendritic architecture in the somatosensory cortex. Neurobiol Dis. 2012 Feb;45(2):671–82.

Balu DT, Coyle JT. The NMDA receptor “glycine modulatory site” in schizophrenia: D-serine, glycine, and beyond. Curr Opin Pharmacol. 2015 Feb;20:109–15.

Balu DT, Li Y, Puhl MD, Benneyworth MA, Basu AC, Takagi S, Bolshakov VY, Coyle JT. Multiple risk pathways for schizophrenia converge in serine racemase knockout mice, a mouse model of NMDA receptor hypofunction. Proc Natl Acad Sci USA. 2013 Jun 25;110(26):E2400–9.

Balu DT, Takagi S, Puhl MD, Benneyworth MA, Coyle JT. 11. D-serine and serine racemase are localized to neurons in the adult mouse and human forebrain. Cell Mol Neurobiol. 2014 Apr;34(3):419–35.

Basu AC, Tsai GE, Ma CL, Ehmsen JT, Mustafa AK, Han L, Jiang ZI, Benneyworth MA, Froimowitz MP, Lange N, Snyder SH, Bergeron R, Coyle JT. Targeted disruption of serine racemase affects glutamatergic neurotransmission and behavior. Mol Psychiatry. 2009 Jul;14(7):719–27.

Beaulieu M, Coyle JT. Effects of fetal methylazoxymethanol acetate lesion on the synaptic neurochemistry of the adult rat striatum. J Neurochem. 1981 Oct;37(4):878–87.

Bendotti C, Forloni GL, Morgan RA, O’Hara BF, Oster-Granite ML, Reeves RH, Gearhart JD, Coyle JT. Neuroanatomical localization and quantification of amyloid precursor protein mRNA by in situ hybridization in the brains of normal, aneuploid, and lesioned mice. Proc Natl Acad Sci USA. 1988 May;85(10):3628–32.

Benneyworth MA, Li Y, Basu AC, Bolshakov VY, Coyle JT. Cell selective conditional null mutations of serine racemase demonstrate a predominate localization in cortical glutamatergic neurons. Cell Mol Neurobiol. 2012 May;32(4):613–24.

Berger UV, Luthi-Carter R, Passani LA, Elkabes S, Black I, Konradi C, Coyle JT. Glutamate carboxypeptidase II is expressed by astrocytes in the adult rat nervous system. J Comp Neurol. 1999 Dec 6;415(1):52–64.

Bird ED, Iversen LL. Huntington’s chorea. Post-mortem measurement of glutamic acid decarboxylase, choline acetyltransferase and dopamine in basal ganglia. Brain. 1974 Sep;97(3):457–72.

Biziere K, Coyle JT. Effects of cortical ablation on the neurotoxicity and receptor binding of kainic acid in striatum. J Neurosci Res. 1979;4(5-6):383–98.

Biziere K, Coyle JT. Effects of kainic acid on ion distribution and ATP levels of striatal slices incubated in vitro. J Neurochem. 1978 Aug;31(2):513–20.

Blakely RD, Ory-Lavollée L, Grzanna R, Koller KJ, Coyle JT. Selective immunocytochemical staining of mitral cells in rat olfactory bulb with affinity purified antibodies against N-acetyl-aspartyl-glutamate. Brain Res. 1987 Feb 3;402(2):373–8.

Blakely RD, Robinson MB, Guarda AS, Coyle JT. A re-examination of the interaction of N-acetyl-L-aspartyl-L-glutamate with a subpopulation of rat brain membrane L-[3H]glutamate binding sites. Eur J Pharmacol. 1988a Jul 14;151(3):419–26.

Blakely RD, Robinson MB, Thompson RC, Coyle JT. Hydrolysis of the brain dipeptide N-acetyl-L-aspartyl-L-glutamate: subcellular and regional distribution, ontogeny, and the effect of lesions on N-acetylated-alpha-linked acidic dipeptidase activity. J Neurochem. 1988b Apr;50(4):1200–9.

Campochiaro P. Molecular pathogenesis of retinal and choroidal vascular diseases. Prog Retin Eye Res. 2015 Nov;49:67–81.

Campochiaro P, Coyle JT. Ontogenetic development of kainate neurotoxicity: correlates with glutamatergic innervation. Proc Natl Acad Sci USA. 1978 Apr;75(4):2025–9.

Carter RE, Feldman AR, Coyle JT. Prostate-specific membrane antigen is a hydrolase with substrate and pharmacologic characteristics of a neuropeptidase. Proc Natl Acad Sci USA. 1996 Jan 23;93(2):749–53.

Corsi P, Coyle JT. Nerve growth factor corrects developmental impairments of basal forebrain cholinergic neurons in the trisomy 16 mouse. Proc Natl Acad Sci USA. 1991 Mar 1;88(5):1793–7.

Coyle JT. Errors in the treatment of common fractures. Ill Med J. 1951 Jul;100(1):10–11.

Coyle JT. Biochemical aspects of neurotransmission in the developing brain. Int Rev Neurobiol. 1977: 20:65–103.

Coyle JT. Excitatory amino acid neurotoxins. In: IBRO Handbook Series: Methods in Neurosciences (G. Jaim-Etcheverry, ed.) pp. 123–41. Wiley, 1985.

Coyle JT. Julius Axelrod (1912–2004). Mol Psychiatry. 2005 Mar;10(3):225–6.

Coyle JT, Axelrod J. Development of the uptake and storage of L-(3 H)norepinephrine in the rat brain. J Neurochem. 1971 Nov;18(11):2061–75.

Coyle JT, Axelrod J. Dopamine-?-hydroxylase in the rat brain: developmental characteristics. J Neurochem. 1972a Feb;19(2):449–59.

Coyle JT, Axelrod J. Tyrosine hydroxylase in rat brain: developmental characteristics. J Neurochem. 1972b Apr;19(4):1117–23.

Coyle JT, Balu DT, Puhl MD, Konopaske GT. History of the Concept of Disconnectivity in Schizophrenia. Harv Rev Psychiatry. 2016 Mar-Apr;24(2):80–6.

Coyle JT, Enna SJ. Neurochemical aspects of the ontogenesis of GABAnergic neurons in the rat brain. Brain Res. 1976 Jul 23;111(1):119–33.

Coyle JT, Geerts H, Sorra K, Amatniek J. Beyond in vitro data: a review of in vivo evidence regarding the allosteric potentiating effect of galantamine on nicotinic acetylcholine receptors in Alzheimer’s neuropathology. J Alzheimers Dis. 2007 Jul;11(4):491–507.

Coyle JT, Henry D. Catecholamines in fetal and newborn rat brain. J Neurochem. 1973 Jul;21(1):61–7.

Coyle JT, Jacobowitz D, Klein D, Axelrod J. Dopaminergic neurons in explants of substantia nigra in culture. J Neurobiol. 1973;4(5):461–70.

Coyle JT, Johnston MV. Functional hyperinnervation of cerebral cortex by noradrenergic neurons results from fetal lesions: parallels with schizophrenia. Psychopharmacol Bull. 1980 Jan;16(1):27–9.

Coyle JT, Molliver ME. Major innervation of newborn rat cortex by monoaminergic neurons. Science. 1977 Apr 22;196(4288):444–7.

Coyle JT, Price DL, DeLong MR. Alzheimer’s disease: a disorder of cortical cholinergic innervation. Science. 1983 Mar 11;219(4589):1184–90.

Coyle JT, Puttfarcken P. Oxidative stress, glutamate, and neurodegenerative disorders. Science. 1993 Oct 29;262(5134):689–95.

Coyle JT, Schwarcz R. Lesion of striatal neurones with kainic acid provides a model for Huntington’s chorea. Neurochemical aspects of the ontogenesis of GABAnergic neurons in the rat brain. Brain Res. 1976 Jul 23;111(1):119–33.

Coyle JT, Snyder SH. Antiparkinsonian drugs: inhibition of dopamine uptake in the corpus striatum as a possible mechanism of action. Science. 1969 Nov 14;166(3907):899–901.

Coyle JT, Snyder SH. Catecholamine uptake by synaptosomes in homogenates of rat brain: stereospecificity in different areas. J Pharmacol Exp Ther. 1969 Dec;170(2):221–31.

Coyle JT, Yamamura HI. Neurochemical aspects of the ontogenesis of cholinergic neurons in the rat brain. Brain Res. 1976 Dec 24;118(3):429–40.

Curtis DR, Lodge D, McLennan H. The excitation and depression of spinal neurones by ibotenic acid. J Physiol. 1979 Jun;291:19–28.

Davies P, Maloney AJ. Selective loss of central cholinergic neurons in Alzheimer’s disease. Lancet. 1976 Dec 25;2(8000):1403.

Davis KL, Mohs RC. Enhancement of memory processes in Alzheimer’s disease with multiple-dose intravenous physostigmine. Am J Psychiatry. 1982 Nov;139(11):1421–4.

Davis KL, Mohs RC, Davis BM, Horvath TB, Greenwald BS, Rosen WG, Levy MI, Johns CA. Oral physostigmine in Alzheimer’s disease. Psychopharmacol Bull. 1983;19(3):451–3.

de Robertis E, Rorequez De Lores Arnaiz G, Pelligrino De Iraldi A. Isolation of synaptic vesicles from nerve endings of the rat brain. Nature. 1962 May 26;194:794–5.

Drachman DA, Leavitt J. Human memory and the cholinergic system. A relationship to aging? Arch Neurol. 1974 Feb;30(2):113–21.

Eisenberg L. Mindlessness and brainlessness in psychiatry. Br J Psychiatry. 1986 May;148:497–508.

Ferkany JW, Zaczek R, Coyle JT. Kainic acid stimulates excitatory amino acid neurotransmitter release at presynaptic receptors. Nature. 1982 Aug 19;298(5876):757–9.

Foster AC, Fagg GE. Acidic amino acid binding sites in mammalian neuronal membranes: their characteristics and relationship to synaptic receptors. Brain Res. 1984 May;319(2):103–64.

Friedland RP, Budinger TF, Ganz E, Yano Y, Mathis CA, Koss B, Ober BA, Huesman RH, Derenzo SE. Regional cerebral metabolic alterations in dementia of the Alzheimer type: positron emission tomography with [18F]fluorodeoxyglucose. J Comput Assist Tomogr. 1983 Aug;7(4):590–8.

Grace AA. Dysregulation of the dopamine system in the pathophysiology of schizophrenia and depression. Nat Rev Neurosci. 2016 Aug;17(8):524–32.

Gray EG, Whittaker VP. The isolation of nerve endings from brain: an electron-microscopic study of cell fragments derived by homogenization and centrifugation. J Anat. 1962 Jan;96:79–88.

Grzanna R, Coyle JT. Rat adrenal dopamine-beta-hydroxylase: purification and immunologic characteristics. J Neurochem. 1976 Nov;27(5):1091–6.

Grzanna R, Molliver ME, Coyle JT. Visualization of central noradrenergic neurons in thick sections by the unlabeled antibody method: a transmitter-specific Golgi image. Proc Natl Acad Sci USA. 1978 May;75(5):2502–6.

Halsted CH, Ling EH, Luthi-Carter R, Villanueva JA, Gardner JM, Coyle JT. Folylpoly-gamma-glutamate carboxypeptidase from pig jejunum. Molecular characterization and relation to glutamate carboxypeptidase II. J Biol Chem. 1998 Aug 7;273(32):20417–24.

Hepler DJ, Olton DS, Wenk GL, Coyle JT. Lesions in nucleus basalis magnocellularis and medial septal area of rats produce qualitatively similar memory impairments. J Neurosci. 1985 Apr;5(4):866–73.

Jin XT, Smith Y. Localization and functions of kainate receptors in the basal ganglia. Adv Exp Med Biol. 2011;717:27–37.

Johnson EC, Border R, Melroy-Greif WE, de Leeuw CA, Ehringer MA, Keller MC. no evidence that schizophrenia candidate genes are more associated with schizophrenia than noncandidate genes. Biol Psychiatry. 2017 Jul 13. pii: S0006-3223(17)31772–9. doi: 10.1016/j.biopsych.2017.06.033. [Epub ahead of print]

Johnston MV, Coyle JT. Histological and neurochemical effects of fetal treatment with methylazoxymethanol on rat neocortex in adulthood. Brain Res. 1979 Jul 6;170(1):135–55.

Johnston MV, Grzanna R, Coyle JT. Methylazoxymethanol treatment of fetal rats results in abnormally dense noradrenergic innervation of neocortex. Science. 1979a Jan 26;203(4378):369–71.

Johnston MV, McKinney M, Coyle JT. Evidence for a cholinergic projection to neocortex from neurons in basal forebrain. Proc Natl Acad Sci USA. 1979b Oct;76(10):5392–6.

Johnstone EC, Crow TJ, Frith CD, Husband J, Kreel L. Cerebral ventricular size and cognitive impairment in chronic schizophrenia. Lancet. 1976 Oct 30;2(7992):924–6.

Karlsen RL, Fonnum F. The toxic effect of sodium glutamate on rat retina: changes in putative transmitters and their corresponding enzymes. J Neurochem. 1976 Dec;27(6):1437–41.

Khacho P, Wang B, Ahlskog N, Hristova E, Bergeron R. Differential effects of N-acetyl-aspartyl-glutamate on synaptic and extrasynaptic NMDA receptors are subunit- and pH-dependent in the CA1 region of the mouse hippocampus. Neurobiol Dis. 2015 Oct;82:580–92.

Kirov G, Pocklington AJ, Holmans P, Ivanov D, Ikeda M, Ruderfer D, Moran J, Chambert K, Toncheva D, Georgieva L, Grozeva D, Fjodorova M, Wollerton R, Rees E, Nikolov I, van de Lagemaat LN, Bayés A, Fernandez E, Olason PI, Böttcher Y, Komiyama NH, Collins MO, Choudhary J, Stefansson K, Stefansson H, Grant SG, Purcell S, Sklar P, O’Donovan MC, Owen MJ. De novo CNV analysis implicates specific abnormalities of postsynaptic signalling complexes in the pathogenesis of schizophrenia. Mol Psychiatry. 2012 Feb;17(2):142–53.

Kleschevnikov AM, Belichenko PV, Faizi M, Jacobs LF, Htun K, Shamloo M, Mobley WC. Deficits in cognition and synaptic plasticity in a mouse model of Down syndrome ameliorated by GABAB receptor antagonists. J Neurosci. 2012 Jul 4;32(27):9217–27.

Köhler C, Schwarcz R, Fuxe K. Hippocampal lesions indicate differences between the excitotoxic properties of acidic amono acids. Brain Res. 1979 Oct 19;175(2):366–71.

Krystal JH, Karper LP, Seibyl JP, Freeman GK, Delaney R, Bremner JD, Heninger GR, Bowers MB Jr, Charney DS. Subanesthetic effects of the noncompetitive NMDA antagonist, ketamine, in humans. Psychotomimetic, perceptual, cognitive, and neuroendocrine responses. Arch Gen Psychiatry. 1994 Mar;51(3):199–214.

Kuhn T. The Structure of a Scientific Revolution. University of Chicago Press, 1962.

Lauder JM, Bloom FE. Ontogeny of monoamine neurons in the locus coeruleus, Raphe nuclei and substantia nigra of the rat. I. Cell differentiation. J Comp Neurol. 1974 Jun 15;155(4):469–81.

Lewis PR, Shute CC. The cholinergic limbic system: projections to hippocampal formation, medial cortex, nuclei of the ascending cholinergic reticular system, and the subfornical organ and supra-optic crest. Brain. 1967 Sep;90(3):521–40.

Liddelow SA, Guttenplan KA, Clarke LE, Bennett FC, Bohlen CJ, Schirmer L, Bennett ML, Münch AE, Chung WS, Peterson TC, Wilton DK, Frouin A, Napier BA, Panicker N, Kumar M, Buckwalter MS, Rowitch DH, Dawson VL, Dawson TM, Stevens B, Barres BA. Neurotoxic reactive astrocytes are induced by activated microglia. Nature. 2017 Jan 26;541(7638):481–87.

Lisman JE, Coyle JT, Green RW, Javitt DC, Benes FM, Heckers S, Grace AA. Circuit-based framework for understanding neurotransmitter and risk gene interactions in schizophrenia. Trends Neurosci. 2008 May;31(5):234–42.

London ED, Coyle JT. Specific binding of [3H]kainic acid to receptor sites in rat brain. Mol Pharmacol. 1979 May;15(3):492–505.

London ED, Klemm N, Coyle JT. Phylogenetic distribution of [3H]kainic acid receptor binding sites in neuronal tissue. Brain Res. 1980 Jun 23;192(2):463–76.

London ED, McKinney M, Dam M, Ellis A, Coyle JT. Decreased cortical glucose utilization after ibotenate lesion of the rat ventromedial globus pallidus. J Cereb Blood Flow Metab. 1984 Sep;4(3):381–90.

McGeer PL, McGeer EG, Singh VK, Chase WH. Choline acetyltransferase localization in the central nervous system by immunohistochemistry. Brain Res. 1974 Dec 6;81(2):373–9.

Miya K, Inoue R, Takata Y, Abe M, Natsume R, Sakimura K, Hongou K, Miyawaki T, Mori H. Serine racemase is predominantly localized in neurons in mouse brain. J Comp Neurol. 2008 Oct 20;510(6):641–54.

Miyamoto M, Coyle JT. Idebenone attenuates neuronal degeneration induced by intrastriatal injection of excitotoxins. Exp Neurol. 1990 Apr;108(1):38–45.

Morrison JH, Grzanna R, Molliver ME, Coyle JT. The distribution and orientation of noradrenergic fibers in neocortex of the rat: an immunofluorescence study. J Comp Neurol. 1978 Sep 1;181(1):17–39.

Morrison JH, Molliver ME, Grzanna R, Coyle JT. The intra-cortical trajectory of the coeruleo-cortical projection in the rat: a tangentially organized cortical afferent. Neuroscience. 1981;6(2):139–58.

Morrison JH, Molliver ME, Grzanna R, Coyle JT. Noradrenergic innervation patterns in three regions of medial cortex: an immunofluorescence characterization. Brain Res Bull. 1979 Nov-Dec;4(6):849–57.

Murphy TH, De Long MJ, Coyle JT. Enhanced NAD(P)H:quinone reductase activity prevents glutamate toxicity produced by oxidative stress. J Neurochem. 1991 Mar;56(3):990–5.

Murphy TH, Miyamoto M, Sastre A, Schnaar RL, Coyle JT. Glutamate toxicity in a neuronal cell line involves inhibition of cystine transport leading to oxidative stress. Neuron. 1989 Jun;2(6):1547–58.

Olney JW. Brain lesions, obesity, and other disturbances in mice treated with monosodium glutamate. Science. 1969 May 9;164(3880):719–21.

Olschowka JA, Molliver ME, Grzanna R, Rice FL, Coyle JT. Ultrastructural demonstration of noradrenergic synapses in the rat central nervous system by dopamine-beta-hydroxylase immunocytochemistry. J Histochem Cytochem. 1981 Feb;29(2):271–80.

Ory-Lavollée L, Blakely RD, Coyle JT. Neurochemical and immunocytochemical studies on the distribution of N-acetyl-aspartylglutamate and N-acetyl-aspartate in rat spinal cord and some peripheral nervous tissues. J Neurochem. 1987 Mar;48(3):895–9.

Perez EJ, Tapanes SA, Loris ZB, Balu DT, Sick TJ, Coyle JT, Liebl DJ. Enhanced astrocytic d-serine underlies synaptic damage after traumatic brain injury. J Clin Invest. 2017 Aug 1;127(8):3114–25.

Perry EK, Gibson PH, Blessed G, Perry RH, Tomlinson BE. Neurotransmitter enzyme abnormalities in senile dementia. Choline acetyltransferase and glutamic acid decarboxylase activities in necropsy brain tissue. J Neurol Sci. 1977 Nov;34(2):247–65.

Price DL, Whitehouse PJ, Struble RG, Coyle JT, Clark AW, Delong MR, Cork LC, Hedreen JC. Alzheimer’s disease and Down’s syndrome. Ann NY Acad Sci. 1982;396:145–64.

Reeves RH, Robakis NK, Oster-Granite ML, Wisniewski HM, Coyle JT, Gearhart JD. Genetic linkage in the mouse of genes involved in Down syndrome and Alzheimer’s disease in man. Brain Res. 1987 Sep;388(3):215–21.

Retz KC, Coyle JT. Effects of kainic acid on high-energy metabolites in the mouse striatum. J Neurochem. 1982 Jan;38(1):196–203.

Robinson MB, Blakely RD, Couto R, Coyle JT. Hydrolysis of the brain dipeptide N-acetyl-L-aspartyl-L-glutamate. Identification and characterization of a novel N-acetylated alpha-linked acidic dipeptidase activity from rat brain. J Biol Chem. 1987 Oct 25;262(30):14498–506.

Roth M. Senile dementia and its borderlands. Proc Annu Meet Am Psychopathol Assoc. 1980;69:205–32.

Schizophrenia Working Group of the Psychiatric Genomics Consortium. Biological insights from 108 schizophrenia-associated genetic loci. Nature. 2014 Jul 24;511(7510):421–7.

Schell MJ, Molliver ME, Snyder SH. D-serine, an endogenous synaptic modulator: localization to astrocytes and glutamate-stimulated release. Proc Natl Acad Sci USA. 1995 Apr 25;92(9):3948–52.

Schwarcz R, Coyle JT. Adenylate cyclase activity in chick retina. Gen Pharmacol. 1976 Oct;7(5):349–54.

Schwarcz R, Scholz D, Coyle JT. Structure-activity relations for the neurotoxicity of kainic acid derivatives and glutamate analogues. Neuropharmacology. 1978 Feb;17(2):145–51.

Schwarcz R, Rassoulpour A, Wu HQ, Medoff D, Tamminga CA, Roberts RC. Increased cortical kynurenate content in schizophrenia. Biol Psychiatry. 2001 Oct 1;50(7):521–30.

Schwarcz R, Whetsell WO Jr, Mangano RM. Quinolinic acid: an endogenous metabolite that produces axon-sparing lesions in rat brain. Science. 1983 Jan 21;219(4582):316–8.

Simonian NA, Getz RL, Leveque JC, Konradi C, Coyle JT. Kainate induces apoptosis in neurons. Neuroscience. 1996 Oct;74(3):675–83.

Slevin JT, Johnston MV, Biziere K, Coyle JT. Methylazoxymethanol acetate ablation of mouse cerebellar granule cells: effects on synaptic neurochemistry. Dev Neurosci. 1982;5(1):3–12.

Slusher BS, Robinson MB, Tsai G, Simmons ML, Richards SS, Coyle JT. Rat brain N-acetylated alpha-linked acidic dipeptidase activity. Purification and immunologic characterization. J Biol Chem. 1990 Dec 5;265(34):21297–301.

Slusher BS, Tsai G, Yoo G, Coyle JT. Immunocytochemical localization of the N-acetyl-aspartyl-glutamate (NAAG) hydrolyzing enzyme N-acetylated alpha-linked acidic dipeptidase (NAALADase). J Comp Neurol. 1992 Jan 8;315(2):217–29.

Snyder SH. The dopamine hypothesis of schizophrenia: focus on the dopamine receptor. Am J Psychiatry. 1976 Feb;133(2):197–202.

Snyder SH, Coyle JT. Regional differences in H3-norepinephrine and H3-dopamine uptake into rat brain homogenates. J Pharmacol Exp Ther. 1969 Jan;165(1):78–86.

Spokes EG. GABA in Huntington’s chorea, Parkinsonism and schizophrenia. Adv Exp Med Biol. 1979;123:461–73.

Snyder SH, Green AI, Hendley ED. Kinetics of H3-norepinephrine accumulation into slices from different regions of the rat brain. J Pharmacol Exp Ther. 1968 Nov;164(1):90–102.

Steullet P, Cabungcal JH, Coyle J, Didriksen M, Gill K, Grace AA, Hensch TK, LaMantia AS, Lindemann L, Maynard TM, Meyer U, Morishita H, O’Donnell P, Puhl M, Cuenod M, Do KQ. Oxidative stress-driven parvalbumin interneuron impairment as a common mechanism in models of schizophrenia. Mol Psychiatry. 2017 Jul;22(7):936–943.

Sweeney JE, Höhmann CF, Moran TH, Coyle JT. A long-acting cholinesterase inhibitor reverses spatial memory deficits in mice. Pharmacol Biochem Behav. 1988 Sep;31(1):141–7.

Sweeney JE, Höhmann CF, Oster-Granite ML, Coyle JT. Neurogenesis of the basal forebrain in euploid and trisomy 16 mice: an animal model for developmental disorders in Down syndrome. Neuroscience. 1989a;31(2):413–25.

Sweeney JE, Puttfarcken PS, Coyle JT. Galanthamine, an acetylcholinesterase inhibitor: a time course of the effects on performance and neurochemical parameters in mice. Pharmacol Biochem Behav. 1989b Sep;34(1):129–37.

Tsai G, Passani LA, Slusher BS, Carter R, Baer L, Kleinman JE, Coyle JT. Abnormal excitatory neurotransmitter metabolism in schizophrenic brains. Arch Gen Psychiatry. 1995 Oct;52(10):829–36.

Tsai G, Slusher BS, Sim L, Coyle JT. Immunocytochemical distribution of N-acetylaspartylglutamate in the rat forebrain and glutamatergic pathways. J Chem Neuroanat. 1993 Sep-Oct;6(5):277–92.

Tune L, Coyle JT. Serum levels of anticholinergic drugs in treatment of acute extrapyramidal side effects. Arch Gen Psychiatry. 1980 Mar;37(3):293–7.

Tune LE, Creese I, Coyle JT, Pearlson G, Snyder SH. Low neuroleptic serum levels in patients receiving fluphenazine decanoate. Am J Psychiatry. 1980a Jan;137(1):80–2.

Tune LE, Creese I, Depaulo JR, Slavney PR, Coyle JT, Snyder SH. Clinical state and serum neuroleptic levels measured by radioreceptor assay in schizophrenia. Am J Psychiatry. 1980b Feb;137(2):187–90.

Tune LE, Strauss ME, Lew MF, Breitlinger E, Coyle JT. Serum levels of anticholinergic drugs and impaired recent memory in chronic schizophrenic patients. Am J Psychiatry. 1982 Nov;139(11):1460–2.

Voris HC, Coyle JT. Fusion versus nonfusion in operative treatment of protrusion of an intervertebral disk. AMA Arch Neurol Psychiatry. 1952 Sep;68(3):398–9.

Whitehouse PJ, Price DL, Clark AW, Coyle JT, DeLong MR. Alzheimer disease: evidence for selective loss of cholinergic neurons in the nucleus basalis. Ann Neurol. 1981 Aug;10(2):122–6.

Whitehouse PJ, Price DL, Struble RG, Clark AW, Coyle JT, Delon MR. Alzheimer’s disease and senile dementia: loss of neurons in the basal forebrain. Science. 1982 Mar 5;215(4537):1237–9.

Wolosker H, Balu DT, Coyle JT. The rise and fall of the D-serine-mediated gliotransmission hypothesis. Trends Neurosci. 2016 Nov;39(11):712–21.

Wolosker H, Balu DT, Coyle JT. Astroglial versus neuronal D-serine: check your controls! Trends Neurosci. 2017 Sep;40(9):520–2.

Wolosker H, Sheth KN, Takahashi M, Mothet JP, Brady RO Jr, Ferris CD, Snyder SH. Purification of serine racemase: biosynthesis of the neuromodulator D-serine. Proc Natl Acad Sci USA. 1999 Jan 19;96(2):721–5.

Yates CM, Simpson J, Maloney AF, Gordon A, Reid AH. Alzheimer-like cholinergic deficiency in Down syndrome. Lancet. 1980 Nov 1;2(8201):979.

Zaczek R, Coyle JT. Excitatory amino acid analogues: neurotoxicity and seizures. Neuropharmacology. 1982 Jan;21(1):15–26.

Zaczek R, Arlis S, Markl A, Murphy T, Drucker H, Coyle JT. Characteristics of chloride-dependent incorporation of glutamate into brain membranes argue against a receptor binding site. Neuropharmacology. 1987a Apr;26(4):281–7.

Zaczek R, Balm M, Arlis S, Drucker H, Coyle JT. Quisqualate-sensitive, chloride-dependent transport of glutamate into rat brain synaptosomes. J Neurosci Res. 1987b;18(3):425–31.

Zaczek R, Koller K, Cotter R, Heller D, Coyle JT. N-acetylaspartylglutamate: an endogenous peptide with high affinity for a brain “glutamate” receptor. Proc Natl Acad Sci USA. 1983 Feb;80(4):1116–9.

Zaczek R, Markl A, Balm M, Coyle JT. A simple method for quantitative electroencephalographic assessment of drugs with convulsant and anticonvulsant properties. J Neurosci Methods. 1986 Dec;18(4):351–60.

Zitrin CM, Klein DF, Woerner MG. Behavior therapy, supportive psychotherapy, imipramine, and phobias. Arch Gen Psychiatry. 1978 Mar;35(3):307–16.

¹This article appeared in the journal of which I was appointed editor-in-chief 60 years later.

Kjell Fuxe

BORN:

Stockholm, Sweden

April 25, 1938

EDUCATION:

Karolinska Institutet, Stockholm, BMedSci (1959)

Karolinska Institutet, Stockholm, PhD (1965)

Karolinska Institutet, Stockholm, MD (1971)

APPOINTMENTS:

Assistant Professor of Histology, Karolinska Institutet (1966–1968)

Associate Professor of Histology, Karolinska Institutet (1968–1979)

Professor of Histology, Karolinska Institutet, (1979–2005)

Professor Emeritus, Karolinska Institutet (2005–present)

HONORS AND AWARDS (SELECTED)

Member of the Nobel Assembly 1986, of Royal Swedish Academy of Sciences (1980)

Honorary Doctorates, Lyon (1992), Barcelona (1998), Ferrara (2002), Malaga (2007)

Kaiser Award, Medical Faculty, University of Honolulu, Hawaii, (1975)

Gold Medal, Research on Prolactin, First International Prolactin Symposium (1977)

Erik H. Fernströms Reward at Karolinska Institutet (1979)

Hilda and Alfred Erikssons Prize, Swedish Royal Academy (1979)

International Madonina Prize of the Biological Sciences, Milan, Italy (1980)

New York Academy of Sciences Award, Biological and Medical Sciences (1985)

IPSEN Prize, Paris, France (1992)

Albert Einstein International Academy Foundation, Cross of Merit (1993)

Humboldt Prize Award, Germany (1998)

ECNP Neuropsychopharmacology Award, Prague (2003)

The Palay Award in Structural Neuroscience, Cajal Club (2006)

Camillo Golgi Medal Award, Brescia (2012)

Sigillo d’Ateneo, University of Urbino (2012)

Kjell Fuxe has been a pioneer in brain and neuroendocrine communication and integration. He provided evidence for the existence of central monoamine neurons, volume transmission and its different forms, and receptor-receptor interactions in heteroreceptor complexes in the central nervous system. He applied this knowledge to develop novel strategies for treatment of schizophrenia, depression, Parkinson’s disease, and cocaine addiction. He introduced, for example, several DA receptor agonists for treatment of Parkinson’s disease and became a pioneer also in molecular neuropychopharmacology. Integration of synaptic and volume transmission signals can take place in synaptic and extrasynaptic heteroreceptor complexes, becoming a new major mechanism for neuromodulation of synapses. The reorganization of the homo- and heteroreceptor complexes in the postsynaptic membrane with novel adapter proteins may form the molecular basis of learning and memory.

Kjell Fuxe

Stockholm in the Early Years

Sweden is my country, and I was born in its capitol in 1938 just before the beginning of World War II. My father and mother came from the farming country of Västergötland at the heart of Sweden. They both grew up in the same village, which had the name Kållands-Mellby, located outside a small town named Lidköping. I do not remember having met any of my grandfathers and grandmothers on my mother’s or father’s side. My parents had to leave and start a new life because the oldest brother inherited the small farm. I still dream of the waving golden cornfields in the sun and the green meadows that I never saw.

My father, Nils Johansson, worked hard as a firewood dealer to take care of our family in Norrmalm in the city of Stockholm, but I never got to know him. My mother, Linnea, called Nea, was a housewife, but she wished she had become a nurse. She gave me the love I badly needed and I grew up as a happy boy. My mother was at the basis of my existence, although I did not understand it at the time. She remained close to my heart all my life. My older brother was kind, but he was six years older and we did not interact much.

I did not realize how lucky I was to live in Sweden, a neutral country during World War II. The rest of Europe suffered in its fight against Nazi Germany, while I was playing on the safe and quiet streets of Norrmalm in the city of Stockholm and in its parks. I had no idea what war meant but remember the strong voice of Winston Churchill on the radio and how happy everyone was the day the war was over. The Americans became my heroes, especially after seeing all the Hollywood war movies.

Entering a New World: Norra Latin

I began school at seven years of age and enjoyed to study and learn already from the beginning. The teachers were kind and the discipline was fair.

After passing four years in elementary school of Adolf Fredrik in Norrmalm, my marks allowed me to enter in Norra Latin, one of the best schools in Stockholm and also located in Norrmalm. There I started in a secondary school for four years. With good marks, you could pass into its high school for another four years and receive a high school diploma.

This eight-year period was full of hard work and was fundamental for my life because I learned foreign languages and began to understand biology, chemistry, physics, and mathematics. I remember that almost every morning I had to run over the alleys of the cemetery of Adolf Fredriks church, where Prime Minister Olof Palme now is buried, because the gates of the school closed at 8 a.m.; being late had consequences. The teachers did a good job, and it did not matter that my parents were poor and lacked academic background. The only drawback was that it was a school only for boys. It made it difficult for me to understand girls. I finished my last year at the top of my class, got a stipend for this achievement, and could enter any university education of my choice. I chose medical studies because it seemed to be the beginning of something important, namely, understanding life.

Karolinska Institutet, Medical Studies

In the autumn of 1957, my studies began at the Karolinska Institutet. The first year was devoted to anatomy and histology, the second year to chemistry and physiology. I became a bachelor of medical science in 1959 and a teaching assistant at the department of histology. I loved to study the beauty of stained cells in the light microscope. In 1960, while learning pharmacology and microbiology, I managed to set up a histochemical method for demonstration of cholinesterases at the histology department. It became my first paper and I enjoyed my collaboration with histologist Bengt Fredricsson and pharmacologists Bo Holmstedt and Folke Sjöqvist at the Karolinska Institutet. The latter two became famous in pharmacology and clinical pharmacology, respectively. My next teacher was Dr. Ove Nilsson at the histology department with whom I published a number of papers in 1962 on the histochemistry of the uterine epithelium in different hormonal states.

In 1962, the important event was that Professor Nils-Åke Hillarp became the new chairman at our department of histology. He was brilliant and full of enthusiasm and energy. He wanted me to set up the histochemical fluorescence method for the cellular localization of monoamines, which he and Bengt Falck had just introduced the same year. With this method the catecholamines (CA) and 5-hydroxytryptamine (5-HT) were transformed into fluorescent compounds by means of a condensation with formaldehyde followed by a secondary dehydrogenation yielding a green and yellow fluorescence, respectively. I was more than happy to accept and chose the subject for my thesis to be focused on the possible existence of monamine neurons in the central nervous system (CNS). Professor Hillarp also collaborated with Professor Arvid Carlsson at the Department of Pharmacology, University of Göteborg, and in 1962, they published a fine article on the existence of a high density of noradrenaline (NA) nerve terminals in the hypothalamus.

Karolinska Institutet, Thesis Period, 1962–1965: Evidence for the Existence of Monoamine Neurons in the CNS

During this period, I stopped my medical education to complete my thesis. A two-years younger medical student, Annica Dahlström, helped me when she was not occupied by her medical studies. My first publication on the brain was based on the indications of the existence of tubero-infundibular dopamine (DA) neurons, which may have a significant role in neuroendocrine regulation. The work on my thesis turned out to be a tremendous struggle because it was impossible to standardize the Falck-Hillarp method, at least with regard to the analysis of the CNS. Working day and night, never giving up, I could obtain a sufficient number of excellent sections from many rats, which made it possible for me to obtain evidence for the existence of DA, NA, and 5-HT cell bodies and nerve terminals and their architecture (Dahlstrom and Fuxe 1964; Fuxe 1965a, 1965b). The axon bundles could be visualized by means of monoamine oxidase inhibitors increasing the monoamine levels and ablations and lesions, which led to the high accumulation of monoamines in axons, especially on the cell-body side of the injury.

This work led to the discovery of the nigro-striatal DA pathway (Anden et al. 1964), degenerated in Parkinson’s disease (PD), and to the mesolimbic DA pathway innervating mainly the nucleus accumbens and the olfactory tubercle (Fuxe 1965a, 1965b). The papers with Dr. Anden were not part of my thesis but rather were published in parallel with the thesis work. They represented the results of a fine collaboration with Professor Arvid Carlsson’s team, where Dr. Nils-Erik Anden gave us the biochemical correlates to the results with the Falck-Hillarp histofluorescence method. Also in parallel, we found the impressive NA and 5-HT nerve terminal networks in the ventral, lateral, and dorsal horns of the entire spinal cord from the rostral to the caudal levels after a number of failures.

What stands out in my memories of the thesis work is the magnificent DA nerve cell groups of the ventral tegmental area, the unique beauty of the NA cell groups of the locus coeruleus (LC), and the subcoeruleus and the 5-HT nerve cell groups of the dorsal and median raphe. I remember these moments when the images created by the green CA fluorescence or the yellow 5-HT fluorescence reached my eyes in the darkness of the microscopy room and changed my life. Happiness came around and said hello.

The opponent (external examiner) at my thesis on April 25, 1965, was Professor Theodore Blackstad from the University of Oslo. He was an outstanding neuroanatomist. Much to my relief he liked my thesis. We had a nice discussion and became friends.

It seemed to me that the identification of the central DA, NA, and 5-HT brainstem neurons in my thesis (1965), innervating more or less globally the brain and the spinal cord, represented the beginning of chemical neuroanatomy. It was made possible through the visualization of these neurotransmitters at the cellular level with the Falck-Hillarp histofluorescence method. The innervation of the brain and spinal cord from the brainstem NA and 5-HT neurons appeared to take place through extensive collateralization of their ascending (Fuxe 1965a, 1965b) and descending pathways. The nigro-striatal and mesolimbic DA neurons were more restricted in their collateralization and mainly involved an innervation of the dorsal and ventral striatum, respectively. Later on in 1973, however, the Glowinsky group discovered the cortical projections of the mesolimbic DA neurons that had a major impact in the DA field, which we rapidly validated.

There were shadows over my thesis celebration because my mentor and supervisor Professor Nils-Åke Hillarp died from a malignant melanoma just one month before my thesis defense. I had a close relationship with him, as I was his first graduate student at the Karolinska Institutet. I respected and admired him very much, and he became my friend. In spite of increasing bad health, he gave me invaluable support and help. His enthusiasm and encouragement made the tough work possible. After having been fortunate to meet, get to know, and work together with this great scientist, it was bitter, sad, and depressing to face the fact that he was gone and no longer with us.

Karolinska Institutet after My Thesis, 1965: Reorganization and Meetings in Stockholm, Milan, and New York

It was far from clear how the Hillarp students would survive at the histology department after the death of Hillarp. However, the prosektor (associate professor) Lars Gyllensten helped us a lot. He became a good friend.

Gyllensten was also a brilliant author and wrote several outstanding novels. He was invited to join the Swedish Academy, which gives out the Nobel Prize in literature, and soon led the Academy, being selected to become its secretary.

Two other Hillarp students defended their thesis after me in the spring of 1965: Torbörn Malmfors and Karl-Axel Norberg. It was decided that the Hillarp students should form an Amine Group at the department built up of three subgroups, each led by one of the three that had obtained their doctor degree in the spring. Medical student Annica Dahlström decided to leave and have her thesis made at the department of pharmacology at the University of Göteborg where Professor Arvid Carlsson was the chair. Instead, medical student Urban Ungerstedt decided to join me. He was a young man with many unique talents. We became good friends, and he made an excellent thesis on the central CA neurons, which he defended in 1971. He became professor of neuropsychopharmacology at the Karolinska Institutet because of his outstanding scientific contributions. At the end of 1965, the Swedish Research Council gave equal support to all the three subgroups, and the Amine Group was able to survive for at least a three-year period.

As a result of my thesis work, I was invited to speak on the topic of central monoamine neurons at several conferences in 1965. One was organized on mechanisms of release of biogenic amines at the Wenner-Gren foundation by U. S. von Euler, S. Rosell, and Börje Uvnäs, professors at the Karolinska Institutet. Another one was the second international CA symposium in Milan in July, where I for the first time presented our illustrations of the central DA, NA, and 5-HT neurons and their pathways. It was an exciting meeting, and I got to know great young scientists in the CA field like Floyd Bloom and Jacques Glowinsky. After the meeting, I went to Venice for a day or two to enjoy the Mediterranean Sea together with Nils-Erik Anden, Arvid Carlsson, and Annica Dahlström. On the way back, I had a nice lunch with the outstanding chemist Hans Corrodi and his family on the green hills of Zurich. I still remember the scent of cut grass and the spectacular view, which made me think of Earth as being close to paradise.

The most exciting meeting for me was held on November 29, 1965, in New York. It dealt with the biochemistry and pharmacology of the basal ganglia. It was organized by Drs. Costa, Cote, and Yahr at Columbia University. I spoke on the nigro-striatal DA neurons and how its degeneration can cause the motor symptoms of PD and can explain the disappearance of DA levels as found by Hornykiewicz. The audience was excited, but one classical neuroanatomist claimed that the ascending DA pathways did not exist. I explained to him that transmitter histochemistry can discover pathways not previously detected by classical neuroanatomy. Arvid Carlsson and Nils-Erik Anden were also there, and we had a good time in Manhattan together, especially at Gallagher’s steak house on the west side, close to Times Square. We felt that our work was becoming recognized in the neurology field.

Even so, there were groups, especially from Chicago, that still claimed that the monosynaptic NA and 5-HT pathways from the lower brain stem to the cerebral cortex did not exist. It took more than 10 years and lots of work before our long ascending and descending monoamine pathways to the cerebral cortex and the spinal cord were accepted in the entire neuroanatomy field.

After New York, I traveled to Los Angeles. I had been invited by Dr. Arnold Scheibel at UCLA, School of Medicine to give a lecture on the central monoamine neurons. Arnold Scheibel is known from his work on the architecture of the brain and spinal cord using inter alia Golgi techniques. He was kind to me and genuinely interested in our work. He appeared to believe in our evidence that the NA and 5-HT brainstem neurons from the reticular formation, including the raphe regions, could directly innervate the cerebral cortex. It was the first time such neuron systems were shown to directly reach and form vast networks of varicose terminals in the limbic and neocortex.

I also met Professor Horace Magoun at UCLA. I was honored to meet him because he was already famous from his work together with Dr. Giuseppe Moruzzi on the ability of electrical stimulation of the brainstem reticular formation to produce arousal and awakening in animal experiments. He was the director of the Brain Research Institute on the campus, and I remember him as full of life and devoted to his institute. He was a charming host at the lunch in Bel Air Country Club on the hills facing the university buildings in the sun. He indicated that perhaps our ascending monoamine neurons may be involved in the arousal mechanism they had discovered. I was happy to enjoy the world of California and its science and felt its attraction. I realized, however, that it would be difficult to work effectively in such a lovely climate. It was sad saying goodbye to California.

Karolinska Institutet, 1966–1968: Application for a Prosektor (Associate Professor) Position at the Department of Histology

This was another important period filled with hard and exciting work. It became clear that to stay on at the Karolinska Institutet it was crucial to obtain a permanent position. It was also necessary for the survival of the Amine Group. I was lucky that such a position became free at the department in this period. To increase my chances, I felt it was important to study also the function and pharmacology of the central monoamine neurons. This became possible through the development of methods to study changes in monoamine turnover through inhibition of tyrosine hydroxylase (TH) and trytophane hydroxylase and measuring the disappearance rate of DA, NA, and 5-HT neuronal levels with biochemistry and histochemistry (the Falck-Hillarp technique). I was happy to collaborate in this project especially with the biochemist Hans Corrodi and the pharmacologist Nils-Erik Anden at Arvid Carlsson’s department in Göteborg. The work was initiated by Hans Corrodi, and I was already friends with both of them. I am sorry to say that they are no longer with us.

We showed that the disappearance of the monoamines after synthesis inhibition was dependent on impulse flow. Anden, Corrodi, and I wrote a summary of this work in the proceedings of a meeting of the British and Scandinavian Societies in Edinburgh in July 1968. I still remember the excellent lecture of Professor John Vane, which was performed in great style.

The degree of disappearance of monoamines was highly correlated with the activity of the discrete neuron systems analyzed, and we frequently used this method to characterize the dynamic changes in discrete DA, NA, and 5-HT neurons in various physiological and pathological states and after treatment with neuropsychopharmacological compounds like the hallucinogen lysergic acid diethylamide (LSD). The reductions of striatal DA turnover we observed in 1967 with apomorphine also strongly indicated that apomorphine possessed DA agonist properties, as previously proposed by A. M. Ernst the same year based on behavioral work.

Later on in 1969–1970, Dr. Gordon Arbuthknott was a guest scientist at the department working, especially, with Urban Ungerstedt in my group and also Lars Olson in another group. They were three friendly, young, and fine scientists. Together, we obtained indications that the mesolimbic DA neurons represented a reward pathway. Thus, electrical stimulation of the ventral tegmental area DA cells, using the same protocol as for electrical self-stimulation, appeared to enhance the neuronal activity of the mesolimbic DA neurons. This was indicated from the enhanced disappearance of the accumbens DA fluorescence after TH inhibition giving evidence for an increase of DA turnover in the mesolimbic DA neurons. Dr. T. J. Crow working with us, now a psychiatrist and researcher at University of Oxford, also played a significant role in this work.

In a series of papers, we also studied DA turnover changes in the median eminence terminals of the tubero-infundbular DA neurons in different hormonal states. This work made it possible to propose that they participated in the inhibitory regulation of gonadotrophin and prolactin secretion at the median eminence and anterior pituitary level.

The most interesting finding in this period was the demonstration in 1967 that after intraventricular injections of 5-HT, Ungerstedt and I, using the Falck-Hillarp technique, observed an accumulation of 5-HT in the central 5-HT neurons. The overall analysis indicated the existence of an uptake-concentration mechanism in the 5-HT neurons (Fuxe and Ungerstedt 1967). It also indicated the possibility that not only the NA uptake-concentration mechanism discovered by Nobel Laureate Julius Axelrod but also a 5-HT uptake-concentration mechanism could be a target for antidepressant drugs. I approached Arvid Carlsson for a collaboration on the effects of antidepressant drugs on this 5-HT uptake mechanism. He agreed to be part of the project. In 1968, we could in fact show that imipramine blocked the 5-HT uptake mechanism (Carlsson et al. 1968). This was further documented the same year by our group, and imipramine was also found to reduce 5-HT turnover in the brain as part of a negative feedback mechanism. The same was true also for other classical antidepressants. This was the beginning of the development of new antidepressant drugs based on their selective ability to block the 5-HT uptake mechanism. It led to a new era in antidepressant therapy with the introduction of serotonin selective reuptake inhibitors (SSRI), the first being fluoxetine.

I was also happy to collaborate in this period with Dr. Donald Reis who later became famous in the cardiovascular field. We found under his leadership that sham rage following brainstem transection was linked to NA release. We became friends, and he always remembered his time in Sweden with joy.

Happy Ending in 1968

I could add manuscripts from the work in this period to the application for the prosektor position and believe it helped me in the competition with the other applicants. Two of the three reviewers voted for me, but there were complaints from another applicant and many in the medical faculty turned against me, especially those from the physiology department. At the end, I was finally approved by the faculty at the Karolinska Institutet. I was lucky.

The year 1968 turned out to be my best year ever, and not only because I got my permanent position. I fell in love with a beautiful girl working as first lab assistant at one of the departments at Karolinska Institutet. We married in April 1968, and I got one son for free from her previous marriage, Jonas, who now is associate professor at Karolinska Institutet. My other son Jörgen arrived in August 1968 and looks a little bit like me. My daughter entered the world in June 1971. Our children were all healthy and wonderful. I am a proud father and have a great wife. I believe it is rare to be so lucky, especially in the world of science, who is a demanding lady.

Meetings in 1968–1969 in Edinburgh, Mexico City, Puerto Rico, and Milan

I gave a lecture at the Third Symposium on PD in Edinburg in 1968 on the nigro-striatal DA neurons. I had the pleasure to meet Professor George Cotzias, a tall and friendly scientist with a strong voice, who was the first to provide the evidence that levodopa in fact possessed anti-Parkinson actions.

The same year I was invited to the Third International Symposium on Endocrinology in Mexico City. I introduced our concept that the tubero-infundibular DA neurons played an inhibitory role in the regulation of luteinizing hormone-releasing hormone (LHRH) release from the external layer of the median eminence based on our results on DA turnover changes in the external layer of the median eminence in various endocrine states. There was no agreement on the neuroendocrine role of the tubero-infundibular DA neurons because inter alia microinjections of CA into the third ventricle gave opposing results, namely, an enhancement of LH secretion. This controversy stayed around for a long time.

In 1969, a meeting was held in Puerto Rico on contemporary research methods in neuroanatomy. I was invited to speak on fluorescence microscopy in neuroanatomy with a focus on the Falck-Hillarp technique for the cellular demonstration of DA, NA, and 5-HT in the CNS. I met the organizers Professor Walle Nauta and Professor Sven Ebbesson and liked both of them. I was proud to meet and play golf with Walle Nauta, who was one of the world leaders in neuroanatomy.

The most important meeting for me was the Second International Meeting of the International Society for Neurochemistry in Milan in the summer of 1969. I was part of a symposium on “Neurochemical Aspects of Hypothalamic Function” organized by Professors L. Martini and J. Meites. I gave a presentation on central monoaminergic neurons and their participation in the regulation of anterior pituitary function. It was a friendly meeting with fine discussions, and I met Professor Menek Goldstein working at the New York University Center. He was one of the world leaders on the neurochemistry of CAs. We immediately liked each other, and Menek was interested in understanding central CA pathways. We decided to take a train ride to the famous lake country of Northern Italy. As we watched the beautiful countryside with the green hills of Italy passing by, we decided to start a collaboration and map out the central CA pathways with immunohistochemistry based on the use of his antibodies against TH, dopa decarboxylase, and DA-beta-hydroxylase. We became truly happy because we had great expectations, and this led to a great collaboration and a large number of papers that further established the architecture of the central monoamine neurons. A warm friendship developed from the very beginning. I still remember the joy I felt at seeing the DA-beta-hydroxylase immunoreactivity (IR) in the LC for the first time. At the end of 1969, I invited Dr. Hökfelt to join my collaboration with Menek Goldstein.

1970s Quantitation of 5-HT and CA Fluorescence

It was important to move away from subjective evaluations to quantitative measurements of monoamine fluorescence. Microfluorimetric measurements were introduced to quantitate the monoamine fluorescence in cell bodies and nerve terminals in combination with a microspectrofluorimetric analysis. In 1974 quantitative comparisons were made on amine fluorescence in NA terminals based on counts in photographs using different transmittance gratings. In this way, quantitative comparisons could be made not only on fluorescence intensity but also on the number of NA varicosities. Luigi Agnati was an Italian postdoc in my laboratory who became a professor of physiology of the Department of Physiology at the University of Modena. We became great friends, and we have worked together in a large number of projects for more than 40 years together with our groups in a splendid way.

Together with Kurt Andersson, an excellent doctoral student; Dr. F. Wiesel, an outstanding neurochemist and psychiatrist; and Professor Luigi Agnati, we also developed a method in 1979 to determine the DA levels and turnover rate in DA terminal networks of the brain by quantitative use of the DA fluorescence derived from the Falck-Hillarp formaldehyde histofluorescence technique.

1970s Novel Developments in the Histochemical Analysis of the Central Monoamine Neurons

6-Hydroxytryptamine became a new tool in monoamine fluorescence histochemistry, because it gave a high fluorescence yield with the Falck-Hillarp technique. It could be taken up into both CA and 5-HT terminal networks, and by use of selective 5-HT reuptake inhibitors, it was possible to have an improved visualization of the brain 5-HT nerve terminal networks. The high success of immunohistochemistry with excellent morphology through formalin fixation was also clear to us. This was based on our own work on the localization of CA synthesizing enzymes in the 1970s. We reported our findings at a meeting organized by Professor O. Eränkö in Helsinki in 1971 and published in Progress in Brain Research the same year. Therefore, 5-HT immunohistochemistry appeared to be the best approach. In 1981, the brain 5-HT nerve terminal networks were mapped out in all their details in an excellent way by Dr. Harry Steinbusch. We published a paper in 1974 on the theory, practice, and application of the Falck-Hillarp technique in the Journal of Histochemistry and Cytochemistry. The immunohistochemistry was taking over, however, especially in view of the varying quality of the results obtained with the Falck-Hillarp technique, which could not be well controlled.

1970s Novel Observations on the Striatal DA Terminal Networks: Striatal Islands of DA Nerve Terminals

In 1970, I was invited to a symposium by Professor de Ajuriaguerra and Professor Gauthier on the “The Central Grey Nuclei of the Monoamines and the Parkinson Syndrome” held in Bel Air, Geneva. I hoped to find novel types of striatal DA nerve terminal networks in the rat by also analyzing the striatum in postnatal development. The reward came quickly with the discovery of highly fluorescent striatal DA islands with densely packed DA nerve terminals against a dark background, because DA terminals in the surrounding striatal tissue had not yet been developed or lacked DA storage. These primary observations were published in a symposium book by Georg and Cie (Ajuriaguerra and Gauthier 1970). This work was done in collaboration with Drs. Lars Olson and Åke Seiger. Both became professors at the Karolinska Institutet. Professor Lars Olson played a significant role in the Nobel assembly and became an international leader of high recognition in neuroscience thanks to his outstanding work.

These observations gave the first indications that the striatum may be organized as islands and as a matrix to integrate information from, for example, glutamate terminals from the cortex cerebri and dopamine terminals from the substantia nigra of the midbrain. In 1972, we published the original article, including evidence that these DA islands exist also in the adult rat (Olson et al. 1972). In parallel and independently, the striatal DA islands also were demonstrated in the rabbit by the Tennyson group at Columbia University.

It is of substantial interest that a new type of ergolene derivative was indicated to be a preferential agonist at ventral striatal DA receptors and at DA receptors belonging to the DA islands but not to the diffuse matrix DA terminal system of the dorsal striatum. This observation led to a selective reduction of DA turnover in the ventral striatum and in the dorsal striatal islands as determined by the TH inhibition method. Using this ergolene derivative in combination with the TH inhibition, the islandic DA system could be excellently demonstrated in the adult rat as well, because of the higher rate of disappearance of DA in the diffuse matrix system as a result of its higher DA turnover.

Professor Ann Graybiel, at McGovern Institute for Brain Research at the Massachusetts Institute of Technology, called the striatal islands striosomes and made pioneering work on their connections and function over many years. The gamma-aminobutyric acid (GABA) output from the striosomes were found inter alia to participate in the integrative afferent compartments of nigral DA dendrites. It has been a great pleasure to meet and discuss this finding with Ann Graybiel at several meetings over the years. She is one of the world leaders in the basal ganglia field.

1970s Novel Observations on the Locus Coeruleus NA Projections

The Histology Department made major contributions to the LC field in the 1970s. The results gave evidence that the NA LC nerve cells formed the entire NA nerve terminal networks in the ventral and dorsal horn through descending projections, the global cerebellar terminal networks, and the global terminal networks of the neocortex and limbic cortex. The hypothesis was advanced that many LC nerve cells may each produce both ascending and descending NA projections as well as cerebellar projections from which massive NA collaterals can arise. This view is now being challenged by a few groups. Nevertheless, I believe our concept is correct, but it is possible that certain NA LC cells may preferentially produce ascending projections targeting, for example, limbic or neocortex. Others may preferentially produce descending projections targeting the ventral or dorsal horn.

To me, early on, it was highly attractive to look upon a single NA LC neuron as a reticular formation brainstem neuron modulating globally the entire CNS from the spinal cord to the cerebellar cortex and the cerebral cortex with collaterals innervating the reticular formation and the thalamus.

We had similar ideas on the subcoeruleus NA system, which like the other remaining NA cell groups, mainly send projections to the autonomic and neuroendocrine regions of the CNS. We proposed that the subcoeruleus NA neurons may have ascending axons to the hypothalamus and preoptic regions and descending axons to the nucleus tractus solitarius (NTS) and the sympathetic lateral column of the spinal cord. Their nerve terminal varicosities were larger with a more intense NA fluorescence and a higher density of these NA terminals was formed compared with the LC NA terminal networks. These features of the autonomic NA nerve terminal plexus may be related to the need for a safe and tonic activation of multiple adrenergic receptor types at different micrometer (μm) distances from these NA varicosities dependent on NA diffusion.

1970s Understanding Communication in the Central Monoamine Neurons

From the beginning of this work, in my thesis it was unclear whether the CA terminal networks in the brain only operated via synaptic transmission (Fuxe 1965a, 1965b). The hypothalamic NA nerve terminal plexa looked the same as the NA nerve terminal plexa in the autonomic nervous system with large varicosities and an intense NA fluorescence as shown by Torbjörn Malmfors, another student in the Hillarp lab. These varicosities did not belong to synapses. We proposed that the varicosities represent parts of the central monoamine terminals specialized for synthesis, storage, and release of CAs and 5-HT (Fuxe 1965a, 1965b). Synaptic transmission was the dogma for communication in the CNS. It seemed possible, however, that diffusion of monoamines could take place from the varicosities into the extracellular space.

It was therefore of high interest that amphetamine, a DA-releasing drug, produced an extraneuronal DA fluorescence around the DA cell bodies of the zona compacta and the ventral tegmental area in the presence of monoamine oxidase inhibition. Urban Ungerstedt and I presented these findings at a meeting on Amphetamines and Related Compounds in Milan in 1969, organized by E. Costa and S. Garattini. The book chapter was published in 1970 (Fuxe and Ungerstedt 1970). Dr. Costa was always a dominant force, but no one seemed to be interested in our results. He was a first-class pharmacologist but is unfortunately no longer with us.

At the 1969 meeting in Puerto Rico on Contemporary Research Methods in Neuroanatomy, I also showed that after a 5-HT uptake blockade with chlorimipramine, an extraneuronal 5-HT fluorescence was demonstrated outside the 5-HT cell bodies of the dorsal raphe in the presence of monoamine oxidase inhibition. These two findings gave me the first indications that monoamines may be able to reach the extracellular space after release from cell bodies and dendrites and, through diffusion in the um range, may reach and activate extrasynaptic monoamine receptors.

In support of this view that monoamines also can communicate via the extracellular fluid, we found that application of DA crystals into the neostriatum led to the appearance of a DA diffusion gradient (Ungerstedt et al. 1969). It was the beginning of the discovery of a novel mode of brain communication that we, along with Luigi Agnati, called volume transmission (VT).

1970s 5,6-Dihydroxytryptamine and 5,7-Dihydroxytryptamine as New Tools in the Mapping of Central 5-HT Neurons and in Producing Their Selective Degeneration

This work was possible through a close collaboration with the outstanding biochemist John Daly at the National Institutes of Health (NIH) who synthesized the compounds and played a great role in our discussions. Dr. Gösta Jonsson, also in our department, played an important role. It was always great to meet John, a complete person both in science and life who traveled in the jungle to find biological material from which new compounds could be obtained. He always faced the risk of getting a tropical disease. I miss him deeply and feel truly sad that he is no longer with us.

5,7-Dihydroxytryptamine turned out be the most selective in lesioning the ascending 5-HT neurons. Together with especially Drs. B. Everitt, K. Hole, and K. Kiianmaa, we published a number of papers on the impact of their degeneration on sexual and aggressive behaviors and on the sleep-wakefulness cycle.

In the work on the sleep-wakefulness cycle, we followed in the footsteps of Professor Michel Jouvet and his group in Lyon who pioneered this field. We could validate his discovery that the ascending 5-HT neurons are required for the maintenance of SWS2. Peter Lidbrink, my graduate student, also was able to validate Jouvet’s work showing that the cortical NA terminals have a role in maintaining cortical arousal. I remember the genuine appreciation Jouvet showed us in response to our neurohistochemical findings on the existence of the ascending NA and 5-HT neuron systems with monosynaptic projections to the entire cerebral cortex. He was a great scientist full of charms and French culture at its best.

A summary of this work was presented at a meeting on serotonin neurotoxins organized by the New York Academy of Sciences. The neurotoxic effects on the 5-HT axons made possible an outstanding demonstration of the ascending 5-HT axons through the accumulation of the yellow 5-HT fluorescence in the axons on the cell body side of the lesions because of the axoplasma flow of the 5-HT storage vesicles from the 5-HT nerve cell bodies of the midbrain 5-HT cell groups.

We wrote many papers with Dr. Barry Everitt in this period on the role of DA and 5-HT in sexual behavior using mainly a behavioral pharmacology approach. I remember our fine interactions. Barry Everitt is currently one of the leaders in the world on drug addiction and works as a professor at the University of Cambridge.

1970s Development of DA Receptor Agonists as a Novel Treatment of PD

We had been interested in developing DA receptor agonists for the treatment of PD since our discovery of the nigro-striatal DA pathways. The idea was that in contrast to levodopa, DA receptor agonists could directly activate the DA receptors and were not dependent on the presence of DA nerve terminals in which DOPA decarboxylase converted levodopa to DA for subsequent release. We assumed that with progressive degeneration of the striatal DA terminals in PD, levodopa treatment could still exert its anti-Parkinson actions through diffusion of DA in the extracellular fluid from remaining DA terminals into regions with DA receptors lacking DA terminals. Thus, in line with our early work (see previous section), we assumed the existence of a DA transmission operating via extracellular fluid diffusion in the extracellular space enhanced by the relative absence of DA terminals with DA uptake mechanisms.

This novel DA transmission was also enhanced by the development of DA receptor supersensitivity in the striatal regions with few or no DA nerve terminals. This was first demonstrated by Urban Ungerstedt in 1971 in his hemi-Parkinson rat model produced through 6-hydroxydopamine neurotoxin (6-OHDA) microinjections into the rostromedial substantia nigra. We were aware in 1970 through collaboration with Drs. Butcher and Engel in Arvid Carlsson’s lab that levodopa could be taken up and decarboxylated in the central 5-HT neurons. Therefore, after levodopa treatment, DA also can be formed in striatal 5-HT terminals and can be released as a false transmitter from these terminals and diffuse via extracellular fluid transmission to activate supersensitive DA receptors in PD.

We therefore proposed that DA receptor agonists should be an interesting therapeutic strategy for the treatment of PD. Apomorphine (see the previous section) was potent but short lasting. We found an interesting compound called ET495 (a piperonyl-piperazine derivative) that produced hypotension, as also found after levodopa treatment, likely because of activation of peripheral dopaminergic receptor systems. In behavioral studies, it showed anti-Parkinson-like actions in hemi-Parkinson rat, as found after levodopa and apomorphine, and reduced striatal DA turnover (Fuxe 1979). In view of my collaboration with Menek Goldstein, I contacted him about also testing ET495 in a monkey model of PD. I was happy to visit his laboratory at the New York University Medical Center and met his colleagues, Dr. Battista, a neurosurgeon, and Drs. Ohmoto and Anagnoste, who were working in the laboratory. It was of high interest for me to watch the antitremor actions of ET495 and the involuntary movements induced. In 1973, a report was published in Science in which the effects of levodopa and the DA receptor agonist ET495 were compared with regard to effects on tremor and involuntary movements. We demonstrated that DA receptors mediated the antitremor actions and the induction of involuntary movements (Goldstein et al. 1973). It was tested in clinical trials for anti-Parkinson effects under the generic name of Piribedil and was shown to have therapeutic actions by Chase and colleagues at NIH in 1974. We were happy that this translational research had been successful. ET495 was later characterized as a D2/D3 agonist.

The work on Piribedil took me to Tunisia in 1975 for the first time. Here I had the pleasure of meeting another outstanding neurologist, Professor Charles Marsden who at the age of 34 already had been appointed to first chair of Neurology at King’s College in London. He turned out to be a great person, brilliant and highly critical in a friendly and humorous way. We were of the same age and in love with neuroscience. In the 1990s, Charles Masden died. He is missed by all of us.

Our intense research on the tubero-infundibular DA neurons indicated that these neurons were involved in the inhibitory regulation of prolactin and LH secretion, later on it was demonstrated that DA receptors existed not only in the brain but also on the prolactin-producing cells of the anterior pituitary. There were indications that 2-br-ergokryptine-methanesulfonate (CB154) could inhibit prolactin and LH-dependent functions, such as ovulation. Therefore, I became interested in testing this compound on the amine turnover in the tubero-infundibular DA neurons. The tubero-infundibular DA neurons, however, did not change their DA turnover in the median eminence in response to CB154. Instead, I found that the striatal DA turnover was reduced by CB154, which indicated a DA agonist action.

The reduction of striatal DA turnover was validated biochemically by Dr. Hans Corrodi in Arvid Carlsson’s laboratory. Then, the DA agonist action of CB 154 was demonstrated in the hemi-Parkinson rat model by Ungerstedt, as shown by contralateral turning behavior of long duration (Corrodi et al. 1973). Menek Goldstein and his group became interested in CB154 and demonstrated its long lasting antitremor activity in their monkey model of PD.

We then started clinical trials with CB154 under the leadership of Dr. A. Lieberman under its generic name bromocriptine, and its long-lasting anti-Parkinson efficacy was demonstrated. These results validated the positive results published by Dr. Donald Calne on bromocriptine in PD in 1974.

It was a true pleasure to meet and get to know Drs. Lieberman and Calne, two outstanding neurologists. They contributed in a significant way to the clinical development of bromocriptine as an anti-Parkinson drug. For many years, bromocriptine became a highly used drug for treatment of PD, second only to levodopa. In 1978, I organized with Dr. Calne an international Wenner-Gren Center symposium on “Dopaminergic Ergot Derivatives and Motor Function” in Stockholm to understand their future potential in the treatment of motor disorders in view of their potent anti-Parkinson actions.

Our research and others indicated that the DA receptors activated by bromocriptine were not linked to activation of adenylate cyclase (AC) but involved a DA receptor now known as D2 receptors with an inhibitory coupling to AC mediated via Gi/o activation. Thus, multiple DA receptors appeared to exist. These results indicated that activation of D2 receptors played a significant role as a target for treatment of PD. Many ergot drugs appear to act as partial DA agonists with the ratio of DA agonist–DA antagonist activity varying from one DA receptor subtype to another one. We realized that ergot drugs in general appear to target multiple DA, NA, and 5-HT receptor subtypes, each of them having their own profile with regard to potency (Fuxe et al. 1978).

The most potent ergot DA agonists in our hands were agroclavine and elymoclavine, but there was no support to go ahead with these interesting ergots of the clavine type. I believed that an in-depth analysis of these ergot compounds would be rewarding in spite of side effects reported on many ergot drugs leading to their withdrawal from clinical use.

Our work on DA receptor agonists as tools in neuroscience and as anti-Parkinson drugs was summarized in a Trends in Neuroscience article in 1979 (Fuxe 1979).

1970s On the Mechanism of Action of d-LSD and the Hallucinogenic Indolamines

On the basis of findings in 1968 that the hallucinogen d-LSD could potently reduce brain 5-HT turnover and activate postjunctional 5-HT receptors, we made the suggestion that d-LSD can produce hallucinations via activation of postjunctional 5-HT receptors in the brain. In 1970–1974 the hallucinogenic indolamines, psilocybine, dimetyltryptamine, and 5-methoxy-N,N-dimetyltryptamine were shown to produce similar actions, which was true also for the hallucinogenic phenylethylamines. These results strengthened our hypothesis.

In parallel, George Aghananian, a pioneer in neuropsychopharmacology and working at Yale School of Medicine, had found d-LSD and hallucinogenic indolamines to have their highest potency at presynaptic 5-HT receptors, leading to reductions in the firing of the dorsal raphe cells. Aghajanian and his group therefore proposed that the hallucinations produced by these compounds were caused by their highly potent actions at presynaptic 5-HT receptors. However, they obtained similar results also with antidepressant drugs, and therefore, this hypothesis appeared to be less likely to them also. I have had a good relationship with George over the years, and we always said a friendly hello to each other at the meetings we attended.

In 1977, we found that the antidepressant drugs amitriptyline and nortrypyline had affinity for some of the d-LSD binding sites in the cerebral cortex, but they had no or very weak affinity for the high-affinity 5-HT binding sites. Both these drugs blocked d-LSD-induced head twitches. We therefore believed that these results indicated the existence of two types of 5-HT receptors, but we were not allowed by the reviewers to put this suggestion into the text. The evidence came a couple of years later in the pioneering papers from Professor Solomon Snyder and his group at Johns Hopkins School of Medicine.

In view of these results, we were of the opinion that the hallucinogens reported earlier targeted a distinct type of 5-HT receptor at which a special type of signaling could be induced by the hallucinogens versus 5-HT, the natural transmitter.

At a meeting on neuroleptics in Belgium in 1970 organized by Janssen and Bobon, I underlined the possible impact of dysfunctional mesolimbic DA neurons on schizophrenia development. It seemed reasonable that there should be a link between the mesolimbic DA neurons and the 5-HT receptor subtype targeted by the previously noted hallucinogens.

In 1975, I was invited to give a lecture at a conference in Capri on “Schizophrenia Today” organized by Kemali, Bartholini, and Richter. This was a golden opportunity to give a summary of our work on the biochemistry and pharmacology of hallucinogens. We received no negative or positive response to the lecture, but it felt good to bring it all together, including the use of 5-HT receptor antagonists. Above all, I loved the island of Capri. The view over the mountains and the Mediterranean Sea was spectacular. At the terrace, there was a delightful lemon tree close by and an icy cold limoncello within reach at sunset. The feeling of being in an Italian heaven entered my mind.

1970s GABA-DA Interactions

With the arrival of the biochemist Dr. Miguel Perez de la Mora in the laboratory from the National Autonomic University of Mexico in Mexico City with high expertise in the GABA field, it became possible to study GABA-DA interactions in detail. We found in 1975 that the DA receptor agonist apomorphine can increase GABA turnover in the ventral tegmental area and the substantia nigra rich in DA nerve cells. The results suggested that activation of DA receptors can induce a GABAergic feedback control of the ascending DA neurons. We also found an inhibitory GABAergic control via GABA-B receptors of the amine turnover in the mesolimbic DA neurons. This finding opened up the possibility of improving treatment of schizophrenia through a combined treatment with GABA-B drugs and DA receptor antagonists. We were invited in 1976 to present our results at a meeting on “Psychopathology and Brain Dysfunction” organized by Shagass, Gershon, and Friedhoff. We also were invited to a meeting on GABA-neurotransmitters in Copenhagen in 1978 organized by Krogsgaard-Larsen, Scheel-Kruger, and Kofod.

This pharmacological approach involving GABA-B receptors made sense to me because we had postulated that the mesolimbic DA neurons may be overactive in schizophrenia. Arvid Carlsson in 1962 had found indications that antipsychotic drugs block DA receptors. Our treatment strategy, however, still remains unexploited.

In this period, we also obtained results indicating the involvement of GABA mechanisms in the actions of benzodiazepines on central CA neurons. These results were reported at a meeting on “Mechanism of Action of Benzodiazepines” organized by Costa and Greengard in 1974. Treatment with chlordiazepoxide and diazepam, drugs with preferential actions in the limbic regions in low doses, reduced DA turnover in the dorsal striatum and especially in the nucleus accumbens and olfactory tubercle. These effects of the benzodiazepines were similar to the effects of the GABAergic drugs. Diazepam also reduced GABA turnover, which we explained on the basis that the drug elicited an increased GABA receptor signaling, leading to an inhibitory feedback on GABA neuronal activity. These actions of benzodiazepines may contribute to their antianxiety effects because, inter alia, the ascending DA neurons also innervate the amygdala. A reduced DA drive to the D1R-enriched intercalated cell masses of the amygdala may bring down the exaggerated fear output from the medial subnucleus of the central amygdala.

Our chapter was published in a book edited by Costa and Greengard for Raven Press in 1975 (Fuxe et al. 1975). It was one of the first reports on the involvement of GABA mechanisms in the actions of benzodiazepines.

This work on GABA in the 1970s with Dr. Miguel Perez de la Mora was the fine beginning of a long-term collaboration, and we became great friends. Miguel for many years now has been a professor at his university in Mexico City. Our work together over many years made it possible for me to become a foreign member of the Mexican Academy of Sciences.

1970s Indications of Adenosine-DA Interactions Using Caffeine and Theophyllamine

In 1972, we observed evidence that caffeine can produce a reduction of 5-HT turnover and especially of DA turnover in the brain but an increase of NA turnover. We therefore tested whether caffeine and theophyllamine could modulate the actions of levodopa and DA receptor agonists in the hemi-Parkinson model. We obtained a marked enhancement of the actions of levodopa and the DA receptor agonists by pretreatment with caffeine and theophyllamine (Fuxe and Ungerstedt 1974) as seen from the marked enhancement of contralateral turning behavior.

In a subsequent paper with Bertil Fredholm, we obtained indications that phosphodiesterase inhibition was not involved in the actions caffeine and theophyllamine but rather adenosine receptor mechanisms. This was the beginning of the work on adenosine-dopamine interactions and opened up a novel field in integrative neuroscience. Bertil Fredholm became a professor of pharmacology at the Karolinska Institutet, a leading member of the Nobel assembly, and an international leader in the adenosine field second to no one through his outstanding research.

1970s Continuation of the Work on the Neuroendocrine Role of the Tubero-Infundibular DA Neurons and the Hypothalamic-Preoptic NA Terminal Networks

We published in this period a large number of papers in the neuroendocrinological field and were invited to give lectures at various neuroendocrine congresses on topics like neuroendocrine regulation of fertility, aspects of neuroendocrinology, neurochemical aspects of hypothalamic function, hormones and brain function, endocrinology, basic applications and clinical uses of hypothalamic hormones, clinical reproductive neuroendocrinology, progress in prolactin physiology and pathology, or brain-endocrine interactions.

We obtained further support for the view that the tubero-infundibular DA neurons were involved in the inhibitory regulation of the LHRH release from the lateral palisade zone (LPZ) of the external layer of the median eminence, including the inhibitory feedback actions of 17-beta-estradiolbenzoate on LH secretion. Furthermore, TH and LHRH IR nerve terminals codistributed in the LPZ but not in the medial palisade zone (MPZ), which received very few LHRH IR terminals.

In the rat MPZ, DA appeared instead to be released as a prolactin inhibitory factor into the hypophyseal portal vessels (Andersson et al. 1981) to reach the DA receptors on the prolactin secretory cells of the anterior pituitary to inhibit its secretion into the circulation. Thus, DA could operate as a prolactin inhibitory factor through release into the capillaries of the median eminence connected to the portal vessels.

Anders Löfström, an excellent graduate student, did his thesis on this topic in the 1970s. Through microfluorimetric quantitation of CA fluorescence in the rat median eminence, he obtained evidence for the distribution of DA and NA nerve terminal networks in the median eminence. He found DA and NA turnover changes in the median eminence in several hormonal states and could validate our previous work in an excellent way. Of special value was his work on the dopamine and NA turnover changes in the critical period for ovulation and his pharmacological analysis of pregnant mare serum induced ovulation in the immature rat. His thesis gave further strong indications for an inhibitory role of the tubero-infundibular DA neurons in LHRH release by targeting the LPZ.

In line with the original findings of Professor Tom Sawyer at UCLA, evidence was obtained for the existence of a stimulatory influence of the hypothalamic NA networks on LHRH release into the portal vessels. I had the pleasure and honor to meet Tom Sawyer, a pioneer in neuroendocrinology, several times, and once I gave a lecture in his laboratory. He was a man I looked up to and respected and remember his gentle and kind way that made me feel at ease.

We found that gut hormones also influenced the hypothalamus and the median eminence. Glucagon, for example, reduced dopamine turnover in the external layer of the median eminence. Instead secretin increased dopamine turnover in the external layer and vasoactive intestinal polypeptide (VIP) produced no action. NA turnover in these regions also was differentially affected by the gut hormones. Dysfunction of the gastrointestinal tract in terms of hormonal release therefore may lead to disturbances in neuroendocrine function and in food intake.

1970s Moving into Nicotine Effects on the Tubero-Infundibular DA Neurons to Understand the Mechanism for Its Neuroendocrine Actions

We started in this decade a highly fruitful collaboration with Dr. Peter Eneroth, an excellent biochemist with a focus on determining hormone levels in blood. He was based at the Karolinska Hospital. I liked him, and we became friends. Together, we felt it was time to evaluate whether certain neuroendocrine actions of nicotine in man could be related to targeting the tubero-infundibular DA neurons.

In three papers from 1977, we demonstrated that acute intermittent treatment with nicotine produced an inhibition of serum prolactin, LH, and FSH levels, mainly seen in the castrated female rat, and associated with an increase of the DA turnover in the external layer of the median eminence. We proposed that nicotinic cholinergic receptors may be located on the tubero-infundibular DA neurons or on other neurons connected to the tubero-infundibular DA neurons. This opened up the possibility that these neurons were targeted by nicotine also in man. Thus, at least part of the nicotine-induced changes in the neuroendocrine panorama, like effects on prolactin and LH secretion may be mediated over the tubero-infundibular DA neurons.

1970s Setting Up a Small Cardiovascular Laboratory

We were interested in understanding whether the NA nerve terminal networks in the brain stem, especially in the NTS, were involved in cardiovascular regulation. They were formed from the non-LC cells in the medulla oblongata and pons (Fuxe 1965a, 1965b). We had certain indications in 1970 that central NA receptors may participate in mediating the hypotensive actions of clonidine.

Per Bolme and I had been medical students together, and he had made his thesis on cardiovascular mechanisms related to cholinergic transmission at the department of pharmacology. We discussed a possible collaboration, and he agreed to be the leader of this project in my laboratory and teach one of my laboratory assistants, Beth Hagman, to measure blood pressure and heart rate as well as respiration rate and depth in rats. Beth was outstanding in performing animal experiments.

We were able to validate the hypotensive effects of clonidine and the involvement of alpha-adrenergic receptors in this action. In addition, we found that clonidine also reduced respiration rate and increased respiration depth. This was the first indication that alpha-adrenergic receptors participated in modulating respiratory centers in the brain stem.

With the findings also of phenylethanolamine N-methyltransferase (PNMT) positive nerve cells and nerve terminals in the brain stem, including cardiovascular areas, we started experiments to see whether adrenaline also was involved besides NA in activating the alpha-adrenergic receptors in the brain stem. We could not obtain a clear-cut answer, especially in view of the low amounts of adrenaline versus the high amounts of NA found in the cardiovascular regions, including the nuc tractus solitarius. It seemed to us that both NA and adrenaline could reach and act as a transmitter at the alpha-adrenergic receptors. In regions of overlap of NA and PNMT-positive nerve terminals, it appeared likely that NA dominated in view of its higher concentrations. The possible role of adrenaline in the brain still remains to be determined. I give Per Bolme my sincere thanks for his contribution in the 1970s after which he devoted his life in medicine to pediatrics.

End of 1970s Moving into Ibotenic Acid with Robert Schwarcz as a Leader

Robert Schwarcz arrived in the laboratory with new ideas. I liked him right away. He had published a great paper with Joe Coyle at Harvard Medical School in Boston on lesions of striatal nerve cells with kainic acid (KA), a conformationally restricted analogue of glutamic acid. It had given a model for Huntington’s disease. He soon found among my chemical compounds ibotenic acid, an isoxazole isolated from the mushroom Amanita muscaria, which also was a conformationally restricted analogue of glutamic acid. I received ibotenic acid from a Swiss biochemist, Dr. C. H. Eugster. I am truly grateful to him for this great gift.

Like KA, ibotenic acid induced neuronal degeneration after microinjection into brain regions like striatum and substantia nigra without affecting axons of passage and nerve terminals of extrinsic origin. It, however, was less toxic and produced more discrete lesions. This made it an improved tool versus KA for the analysis of the architecture of distinct brain regions. Ibo in contrast to KA does not depend on the integrity of a glutamatergic innervation. Unlike KA, it also had a low affinity for ³H-KA binding sites.

We observed compensatory bilateral changes in dopamine turnover after a striatal kainate lesion on one side of the brain with a reduction of striatal DA turnover on the contralateral side to the lesion. Such mechanisms may remove striatal network asymmetry and help maintain symmetrical motor behavior in animals with unilateral lesions.

We wrote 14 papers together in this period from 1978 to 1980. I was happy and honored to be invited to his wedding with Damian in Stockholm. Afterward, we had a wonderful time at the best café in Stockholm. Since then, I have had great interactions with them over three decades. We also organized an international symposium held in Stockholm at the Wenner-Gren Center in 1982 on excitotoxins together with Peter Roberts.

This was the year the secretary of the Wenner-Gren Foundation died. His name was Yngve Zotterman, and he was an outstanding sensory physiologist in love with neuroscience. He was also a great person. I organized my first international Wenner-Gren Center symposium with him in 1973 together with Lars Olson on the dynamics of degeneration and growth in neurons. I respected him and felt close to him, although he was several decades older.

Robert Schwarcz is now a professor of psychiatry, pharmacology, and pediatrics at the University of Maryland School of Medicine, and deputy director of the Maryland Neuroscience Research Center, Baltimore. He pioneered the field of kynurenines in the mammalian brain and is an outstanding neuroscientist.

1980s Introduction of the Concept of Receptor-Receptor Interactions in the Plasma Membrane

At the end of the 1970s, we were convinced that the plasma membrane had been neglected as a place for integration of signals. The integration process was believed to mainly take place in the intracellular pathways toward the nucleus and in the promoter regions of genes regulating gene expression. We therefore tested in membrane preparations to see whether activation of one G protein-coupled receptor (GPCR) could modulate the affinity and density of another GPCR, assumed to be colocated in the CNS, as studied in biochemical binding experiments. We started out by testing whether substance P and CCK8 could modulate the binding characteristics of ³H-5-HT binding sites and dopamine D2R antagonist binding sites using ³H-spiroperidol. Significant changes in the binding characteristics were observed both in the 5-HT and D2 receptors (Fuxe et al. 1981; Fuxe et al. 1983). In the 1981 paper, we were not allowed to use receptor-receptor interactions in the text, but in the 1983 paper, we could even use it in the title. We also found indications of significant neurotensin receptor-D2R, neuropeptide Y receptor–alpha2 receptor interactions, and glutamate receptor-D2R interactions in 1983 and 1984, again using biochemical binding techniques.

We wrote the first review on intramembrane receptor-receptor interactions in 1985 where we also correlated the biochemical findings to results in functional models (Fuxe et al. 1983). We published the first results in journals like Acta Physiologica Scandinavica, Journal of Neural Transmission, Neuroscience letters, European Journal of Pharmacology, and Medical Biology. We were invited to present our work on CCK peptides and the CCKR-D2R interactions at a meeting on neuronal cholecystokinin in Brussels in 1984 organized by Professor Jean-Jacques Vanderhaeghen and Dr. J. N. Crawley. It was a great meeting, and I got to know the Brussels aperitifs.

Jean-Jacques and I were good friends after skiing together at the alpine neuroscience meetings organized by the French neuroscientists at various ski resorts. I especially remember our time together in Megeve not far from Geneva. We had great discussions and a lot of fun and the magnificent Mont Blanc was not far away. I was happy to be invited to his 80th birthday celebration in the house of his son Pierre in Brussels, also a famous neuroscientist like his father. Jean-Jacques and I planned for future meetings but sudden death intervened one year later. Sadness is there, but I know he had a fine life and was proud of his son.

To us, the intramembrane receptor-receptor interactions represented a novel integrative mechanism for biological signals, a mechanism that could be of fundamental importance. It gave a new understanding to the existence of isoreceptors (Agnati et al. 1980; Fuxe et al. 1981; Fuxe et al. 1983), because each one of them could have a differential capability to interact with other types of receptors. It opened up a dramatic increase in molecular integration in the plasma membrane and thus in information handling in the synaptic and extrasynaptic membranes because of the receptor diversity obtained. They should have a major place in learning and memory as we proposed in a meeting on neural transmission, learning and memory in Argentina in 1982 organized by Professors Caputto and Marsan. The meeting book was published in 1983.

This molecular integrative mechanism also offered a novel therapeutic approach. Thus, instead of targeting the orthosteric receptor binding sites directly with agonist–antagonist drugs, its receptor partner could be targeted, upon which agonist activation could modulate its recognition and signaling process through receptor-receptor interactions. In fact, at a meeting in 1983 in Corfu on frontiers in neuropsychiatric research organized by Goldstein, Friedhoff, and Georgotas, we discussed receptor-receptor interactions as a new mechanism for antidepressant drugs.

Later on in 1988, we found an antagonistic galanin receptor-5-HT1A receptor-receptor interaction in the limbic cortex of likely relevance for depression. We presented these findings at a meeting organized by Professor Pauletti in Florence in 1989 on “Serotonin from Cell Biology to Pharmacology and Therapeutics.” In view of the therapeutic potential of 5-HT1A agonists in depression, galanin receptor antagonists seemed to be one possible new strategy for development of novel antidepressant drugs.

We gave a comprehensive report on the relevance of intramembrane receptor-receptor interactions for drug development in the CNS in 1988 in Washington, D.C., at a meeting on “Neurochemical Pharmacology: A Tribute to B. B. Brodie” organized by Erminio Costa. It was an honor and pleasure to meet Brodie and give him my genuine congratulations for his lifetime achievements in pharmacology.

Agnati and I organized our own international symposium on “Receptor-Receptor Interactions: A New Intramembrane Integrative Mechanism” at the Wenner-Gren Center in Stockholm in 1986. However, clear-cut evidence for our concept was missing and most of the participants did not believe in our story to put the plasma membrane in the center for integration of biological signals. Only Dr. W. Rostène from Paris was positive. We were disappointed and a little depressed. Already as a medical student, I had believed that the plasma membrane should be an important center for integration of biological signals. The receptors, ion channels, and G proteins were there in the synaptic and extrasynaptic membranes and could be reached by protein kinases and phosphatases. For information handling to work, their signaling and recognition should become integrated already in the plasma membrane followed by molecular integration in the cytoplasmatic pathways and at the transcription level in the nucleus.

Gabriel von Euler arrived in my laboratory as a graduate student in the second half of the 1980s. Together, we agreed that he should focus his thesis on the antagonistic neurotensin receptor (NTSR)-D2R interactions we had previously found. In his thesis, he obtained evidence that made the relevance of these receptor-receptor interactions more convincing. The NTSR interacted with D2Rs and was biochemically characterized. The interaction was G-protein independent and could be demonstrated also after intraventricular NT injections and was not related to the coexistence of DA and NT in nerve terminals. NT also reduced the affinity of the D2R in human caudate-putamen.

Of great interest was that my postdoc Sergio Tanganelli demonstrated that NT in the striatum counteracted apomorphine-induced inhibition of dopamine release, which could be elegantly explained by the antagonistic NTSR-D2R interaction in the DA nerve terminals (Tanganelli et al. 2012). We regarded this receptor-receptor interaction as a major mechanism for the neuroleptic-like action of neurotensin and its antipsychotic potential. These results taken together strengthened the functional relevance of the antagonistic intramembrane NTSR-D2R interactions.

1980s Central CA-Neuropeptide Y Interactions in Cardiovascular Centers. Focus on the Neuropeptide Y Receptor (NPYR)–Alpha2 AdrenergicR Interactions

Dr. Anders Härfstrand entered my laboratory after completing his medical study in the beginning of the 1980s. He was a highly competent graduate student. He brought new life into our lab, and we agreed his thesis should be on brain NPY mechanisms and involve cardiovascular and neurochemical studies, including interactions with the alpha2-adrenergic receptors in the NTS. The NPY-positive neurons recently had been demonstrated in the brain.

Harfstrand demonstrated that intraventricular injections of NPY produced hypotension, bradycardia, and bradypnoea in the awake unrestrained rat, which is similar to the actions of clonidine. The target region was probably the NTS where the baroreceptor afferents terminate. It is rich in both NPYR and alpha2-adrenergic receptors. It was highly interesting that simultaneous central administration of adrenaline and NPY led to antagonistic interactions in vasodepressor responses in awake male rats (Harfstrand and Fuxe 1987). We then had the idea based on our concept of receptor-receptor interactions that NPYR and alpha2-adrenergic receptors formed a complex in which antagonistic reciprocal receptor-receptor interactions developed, reducing the affinity and signaling of each other. Evidence for this view was obtained by Harfstrand and colleagues in 1989 (Harfstrand et al. 1989). In vitro incubation and central administration to NPY or clonidine reduced the binding of an alpha2 adrenergic receptor agonist and of an NPY radioligand, respectively.

Taken together, the results indicated that antagonistic receptor-receptor interactions can play a major role in cardiovascular homeostasis. I am proud of Anders Harfstrand for his great thesis that was defended in 1987 (Harfstrand 1987). He played a leading role also in other projects in the laboratory. Härfstrand was the first to obtain evidence for a cardiovascular role of central galanin neurons, published in 1987. He was, for example, the first author of a paper on glucocorticoid receptor (GR) IR in monoaminergic neurons, which had a major impact on understanding the glucocorticoid regulation of the central monoamine neurons, especially in relation to stress. It was part of a collaboration with Professor Jan-Åke Gustafsson at the Karolinska Institutet, whose GR antibody made this paper possible. He is one of the world leaders on steroid receptors.

I remember giving a lecture on steroid hormone regulation of brain function in Paris in 1984 at a conference on steroids and the brain. I was a coorganizer together with Bruce McEwen and Etienne-Emile Baulieu, pioneers in the field, at this Table Ronde Roussel Uclaf meeting. I knew Bruce already from the beginning of my time at the Karolinska Institutet. We always had a good time together, and sometimes with our families.

Harfstrand also played a leading role together with Dr. M. Kalia at Thomas Jefferson University in Philadelphia in the discovery that somatostatin produces apnea, which through our work together indicated a possible role in apneic syndromes. We became good friends, and I remember we had a great dinner together in Texas in relation to a meeting on CNS mechanisms in hypertension organized by Drs. Buckley and Ferrario in 1981.

Harfstrand made an outstanding career as a leader for drug development in several of the leading drug companies in the world and presently is a consultant to Karolinska Institutet Innovations AB.

1980s Research on the Role of CA Mechanisms in Neuroendocrine Regulation (continued)

Dr. Kurt Andersson came to my laboratory at the end of the 1970s. He was interested in neuroendocrinology and became the scientist in our group who would do his thesis on the role of DA and NA nerve terminal networks in regulating the endocrine function of the anterior pituitary. Dr. Andersson became an outstanding expert in quantitative microfluorimetry. Together with his fine knowledge of brain microanatomy, his experiments were highly successful. Our expert in animal experiments, Beth Hagman, was also available to help him with the animal experiments in a fine way. Dr. Andersson was the leading author on the method paper on determinations of CA half-lives and turnover rates in discrete CA nerve terminal systems of the hypothalamus, the preoptic region, and the forebrain by quantitative histofluorimetry. Dr. Kurt Andersson is now chief physician in medicine and diabetes at the Karolinska Hospital in Huddinge.

In this period with Andersson as the leading author, we mainly focused our studies on the effects of rapid feedback by pituitary hormones prolactin and growth hormone on the DA and NA terminal networks of the median eminence and the hypothalamus-preoptic area. We also studied the effects of ultrashort feedback via the hypothalamic hormones like LHRH and corticotropin-releasing factor (CRF) on the terminal networks. These experiments were performed with Dr. Eneroth, and in the case of rapid feedback also with Drs. Nyberg and Roos. As an example, I will mention that rat prolactin given intravenously produced a rapid and highly significant enhancement of dopamine turnover exclusively in the MPZ of the median eminence of the hypophysectomized rat. These results strongly indicated that DA as a prolactin inhibitory factor was released from the MPZ in the rat, rapidly responding to increases in prolactin levels in the blood. Thus, DA can operate via long-distance signaling in the portal blood vessels to the anterior pituitary gland. NA turnover was also increased in discrete regions of the hypothalamus, indicating that rat prolactin modulated other functions of the hypothalamus.

The next example I will highlight is the selective LHRH-induced activation of DA turnover in the LPZ of the median eminence using quantitative microfluorimetry, where the DA and LHRH nerve terminals codistribute in high densities (Andersson et al. 1984). Thus, the ultrashort feedback action by LHRH may involve release of LHRH from the nerve terminals in the LPZ, which may enhance DA release from adjacent DA terminals via their postulated LHRH receptors or via adjacent LHRH-induced tanycyte signaling, with the tanycytes possessing postulated LHRH receptors. LHRH was given intravenously. It was of high interest that LHRH in the same experiment selectively reduced NA turnover in the medial preoptic nucleus where many of the LHRH immunoreactive nerve cell bodies are found. Such events should lead to a reduced activity in the LHRH neurons, in view of the excitatory influence of noradrenergic neurons on their activity. The mechanism may involve diffusion and flow of intravenously injected LHRH from the median eminence within paraaxonal channels along the LHRH axons. In this way, LHRH can reach the LHRH nerve cell bodies and dendrites in the preoptic region and can modulate NA release through the activation of postulated LHRH receptors located on the local NA nerve terminals or the local astroglia. The change in local astroglia signaling may then modulate the local NA release. These results again indicated the existence of a major transmission in the extracellular fluid.

Through the excellent work of Dr. Andersson and Professor Eneroth, we determined in a large series of papers that many of neuroendocrine actions of nicotine and exposure to cigarette smoke (e.g., inhibition of prolactin, LH, and thyroid-stimulating hormone secretion) were linked to changes in the tubero-infundibular DA neurons and to changes in NA turnover in the NA terminal networks in discrete parts of the hypothalamus. Nicotinic cholinergic receptor activation was the receptor targeted by nicotine and cigarette smoke and induced the changes observed. One review of this work was presented at a Ciba Foundation Symposium in 1989 on “The Biology of Nicotine Dependence.” Here we also reported on our findings from 1981 that nicotine induced increases of dopamine turnover in the mesostriatal and mesolimbic dopamine neurons. We proposed that the nicotine-induced increase in DA turnover in nucleus accumbens was involved in mediating the rewarding actions of nicotine. In a 1989 review in Psychoneuroendocrinology, we discussed the medical implications of the neuroendocrine actions of nicotine.

In 1988, we were the first group to show the neuroprotective effects of nicotine treatment on lesioned nigrostriatal dopamine neurons in the rat. This was part of Ann-Marie Janson’s thesis in my group. She is now one of the experts at the Swedish Medical Products Agency in Uppsala because of her excellent analytical capability.

Together with Drs. Belluardo, Mudo, and Blum we found in 1998 that acute intermittent nicotine treatment produced regional increases of basic fibroblast growth factor (bFGF) messenger RNA and protein in the tel- and diencephalon of the rat. Such effects may be involved in the mechanism for the neuroprotective actions found with nicotine treatment. We have a highly rewarding long-term collaboration on nicotinic receptor agonists as neuroprotective and neurotrophic drugs with the Belluardo-Mudo team at the Department of Physiology, University of Palermo, Italy. Together, we wrote one review on central nicotinic receptors, neurotrophic factors, and neuroprotection that appeared in Behavioral Brain Research in 2000 and another one on neurotrophic effects of central nicotinic receptor activation published in the Journal of Neural Transmission the same year.

Note that in the early 1990s, an excellent postdoc Gershon Chadi from Sao Paulo, Brazil, came to our laboratory. He demonstrated the neuroprotective effects of bFGF upon lesion of nigro-striatal DA neurons with MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and studied the astroglia bFGF dynamics after lesions. He performed great work in his studies on trophic response in the lesioned brain.

1980s Toluene Vapor Exposure Alters CA Turnover and the Binding Properties of CA Receptor Subtypes in the Brain: Possible Mechanism

These experiments were a joint effort by our team, especially Dr. Andersson, the Toftgård toxicology group, Dr. Celani of the Agnati group, Dr. Martire, and Dr. Eneroth. It was of high interest that decreases in DA turnover in the anterior dorsal striatum were induced by toluene at concentrations lower than the current Occupational Safety and Health Administration threshold limit value (100 ppm). It was published in Toxicology Letters in 1982. Such changes may lead to disturbances in motor functions and may involve changes in membrane fluidity altering the properties of pre- and postjunctional DA receptors. At high concentrations of toluene, DA turnover in the subcortical limbic regions, including the nucleus accumbens, was instead increased.

This last reported result is of high interest because these regions are innervated by the mesolimbic DA reward neurons. We therefore proposed that these actions may represent the neurochemical basis for its abuse in humans. It was therefore interesting that subacute treatment with toluene produced a dose-related decrease of affinity in the [3H]-spiperone binding sites labeling striatal D2Rs. It was also published in Toxicology Letters. The D2Rs are in part located as autoreceptors on the striatal DA terminals. If a decreased affinity of the D2 autoreceptors also takes place in the mesolimbic DA neurons, the increased DA turnover in these neurons found with toluene may be the result of a reduced affinity of the D2 autoreceptors. Such effects on receptor binding characteristics may be related to the physico-chemical properties of toluene, which can produce alterations in membrane fluidity. As a consequence, the receptor structures may be modulated as well as their receptor-receptor interactions.

Notably, subacute treatment with toluene in a dose-dependent way increased the density and reduced the affinity of beta-adrenergic receptors in the cerebral cortex without affecting the binding characteristics of alpha1-adrenergic and alpha2-adrenergic binding sites in this region. These findings were published in Acta Physiologica Scandinavica in 1987 and indicated that certain receptors may be more sensitive to changes in membrane fluidity than others.

1980s Studies on the Neuroprotective and Trophic Actions of the GM1 Ganglioside

Professor Luigi Agnati wrote a number of papers on the impact of the GM1 ganglioside on neuronal repair and survival of neurons, including studies on the nigro-striatal DA neurons. I was happy to help him in this endeavor, and we were able to observe neuroprotective actions. In this project, Agnati used computer-assisted morphometry and microdensitometry to study the effects of the GM1 ganglioside on the degenerative and regenerative features of the nigro-striatal DA neurons.

1980s Quantitative Neuroanatomy in Transmitter Research

Thanks to Luigi Agnati’s excellence in developing new methods in neuroanatomy, we were able to introduce the principles for the morphological characterization of transmitter-identified cell groups in 1982. This work was followed by the development of a method for rostrocaudal integration of morphometric information in 1984. This year we also organized an international Wenner-Gren Center symposium in Stockholm on “Quantitative Neuroanatomy in Transmitter Research,” with Professor Agnati having a leading role. The book I coedited with Agnati was published in 1985 (Agnati and Fuxe 1985). I remember that quantitative autoradiography was excellently discussed at the meeting by Dr. Fabio Benfenati in Agnati’s group.

1980s Effects of Treatment with the Antidepressant Drug Imipramine on 5-HT IR in Nerve Cells of Four Different 5-HT Cell Groups

The psychiatrist Dr. Isao Kitayama came to my laboratory from Japan in the second half of the 1980s. He was an excellent scientist and performed the morphometric and microdensitometric analysis of, for example, 5-HT IR in a fine way together with members of my group. We appreciated each other, and our families have met in Stockholm and Japan, sometimes with Dr. Yuji Odagaki and his wife in recent years. This has been a fruitful collaboration. Today, Dr. Kitayama has also become a known artist, and he presents his work at international exhibitions, for example, in Paris.

We were both interested in depression and in understanding the actions of antidepressant drugs. We decided to study the effects of acute and chronic treatment with imipramine in normal rats on 5-HT nerve cell groups, namely, raphe pallidus, raphe obscurus, and the raphe magnus nuclei with the ventral part of the reticular gigantocellular nucleus and the large dorsal raphe nucleus.

Only acute imipramine treatment significantly enlarged the field area of 5-HT IR in the nerve cells in the dorsal raphe. The mechanism was unknown. In view of recent work by Dr. Borroto-Escuela and colleagues in our group it seems possible that 5-HT reuptake blockade can contribute by activation of 5-HT1A autoreceptors through increased extracellular 5-HT levels. The 5-HT1A autoreceptors may activate FGFR1 signaling via a receptor-receptor interaction. The FGFR1 signaling may then increase 5-HT synthesis in the dorsal raphe nucleus, projecting into the tel- and diencephalon.

Instead, however, only chronic imipramine treatment selectively enhanced 5-HT IR in the nerve cells of the ventral part of the reticular gigantocellular nucleus, which is continuous with the raphe magnus nucleus, evaluated from the median grey values. Thus, the antidepressant drug imipramine can differentially affect the 5-HT cell groups, which is quite interesting. The mechanism for these differential effects is unknown, but it may be that the FGFR1-5-HT1A autoreceptor complexes are different between 5-HT cell groups, leading to different dynamics in response to imipramine treatment. In addition, the degree of NA innervation also can differ and can play a role because imipramine also inhibits the NA transporter.

It is of substantial interest that Kitayama and colleagues also found that chronic imipramine treatment altered GR IR in distinct regions of the lower brain stem. We found a selective increase of nuclear GR IR in the 5-HT nerve cell group from the ventral part of the reticular gigantocellular nucleus of the rostral ventromedial medulla in continuity with raphe magnus nucleus. These results were obtained with microdensitometrical analysis. In the morphometric analysis, there were instead changes in the mean profile area of the nuclear GR IR, secondary to the significant increase in GR IR in the raphe magnus nucleus. Serum levels of corticosterone and aldosterone turned out to be unaffected.

The increased GR IR may be the result of an altered number of GR in these two 5-HT cell groups or an altered translocation of GR to their nuclei. With current knowledge, we proposed a modulation induced by imipramine, through inhibitory effects on the 5-HT transporter, on the organization of the 5-HT1A autoreceptor containing heterocomplexes of which the 5-HT transporter may be part. The resulting alterations in the signaling from these heteroreceptor complexes can alter the gene expression of GR or the recruitment of the GR to the nucleus. The selectivity observed among the 5-HT cell groups may be that each 5-HT cell group has its own panorama of 5-HT1A heteroreceptor complexes that determine the sensitivity to imipramine treatment. The 5-HT1A-FGFR1 heteroreceptor complex may play a role also in this case.

The most impressive change with chronic imipramine treatment was the increase of GR IR in the NA nerve cells of the LC. In this case, the NA reuptake inhibition may play the major role. The NA transporter may be part of a complex with alpha2-adrenergic autoreceptor and the increase in extracellular NA levels leading to activation of the alpha2 autoreceptor. This receptor can have other functions than being an autoreceptor by being part of heteroreceptor complex containing, for example, FGFR1.

The net outcome with increases in GR IR after chronic imipramine treatment in distinct monoamine cell groups seems to be of value for its therapeutic actions, because responsivity to glucocorticoids remains or is increased in at least one relevant system. The locus coruleus NA system and antistress actions therefore may develop.

Effects of a 14-day immobilization stress on 5-HT and GR IR in 5-HT nerve cell groups was evaluated on day 7 after the end of the immobilization to understand the relationship between behavioral recovery and changes in GR and 5-HT IR in raphe pallidus, raphe obscurus, and the raphe magnus nuclei with the ventral part of the reticular gigantocellular nucleus and the large dorsal raphe nucleus. The first three raphe nuclei send descending 5-HT pathways to the spinal cord, and the last one gives rise to ascending 5-HT pathways to the tel- and diencephalon. At day 7 after the 14-day stress, food intake and locomotion were fully recovered. Nevertheless the 5-HT IR in the 5-HT cell groups studied was substantially and significantly reduced. This was observed in the dorsal raphe, in spite of an increase in nuclear GR IR in this 5-HT cell group known to play a relevant role in mood regulation. Thus, in this case, the increase in GR IR cannot produce a recovery of 5-HT IR, which probably indicates a lack of recovery of 5-HT synthesis. The explanation may be that GRs, even if increased, cannot function properly and therefore fail to increase 5-HT synthesis. A brake may have been developed in the promotor regions where GRs may act to increase 5-HT synthesis. Future experiments are needed to test this proposal.

1980s Introduction of the Concept of Two Main Types of Communication in the CNS: Volume Transmission and Wiring Transmission

The major result of this study was the finding of a lack of an overall correlation of the regional distribution of central enkephalin and B-endorphin immunoreactive terminals and of mu and delta opioid receptors in adult rat brain (Agnati et al. 1986). These results indicated that the opioid peptides needed to diffuse in the extracellular fluid before reaching their receptors to induce opioid transmission. Thus, a transmitter-receptor mismatch existed. These findings together with our work in 1969–1970 indicating that monoamines can diffuse in the brain, as well as the overall architecture of the central monoamine neurons, led us to introduce the concept of VT in this paper. It was described as a widespread mode of intercellular communication that occurs in the extracellular fluid and in the cerebrospinal fluid (CSF) of the brain. VT signals move from source to target cells via concentration, temperature, and pressure gradients leading to diffusion and flow (convection) in the extracellular space. Thus, there are in VT no private channels as in wiring transmission (WT), the prototype being synaptic transmission. The latter operates via axons, terminals, and synapses. In 1988, at a meeting on the regulatory role of opioid peptides organized by Illes and Farsang, we reported that the opioid peptide systems operated via VT to produce their actions in the brain. This represented a new major transmission in the CNS that ranged from very short (um range) to long distances (mm range) with global effects introduced via CSF.

1990s to Present: Evidence for VT and Further Development of the Concept

Dr. Börje Bjelke came to the laboratory around 1987, and he was interested in having his thesis on VT and did a great job. He started out in an excellent way with a Neuroscience Letter paper in 1988 on the survival of adenohypophyseal homologous transplants in the rat striatum associated with diffusion of prolactin-like IR into the surrounding neuropil of the striatum. In 1989, he found an increased diffusion of prolactin-like material into the brain neuropil from homologous adenohypophyseal transplants in the rat neostriatum after a 6-OH-dopamine-induced degeneration of the nigrostriatal dopamine neurons. Thus, the D2 receptors on the prolactin cells inhibiting prolactin release were inhibited by DA originating from striatal DA nerve terminal networks communicating via VT.

We organized an international Wenner-Gren Center Congress in 1990 on “Volume Transmission in the Brain. Novel Mechanisms for Neural Transmission” and the book, Advances in Neuroscience, Volume 1, which I edited with Agnati, was published in 1991 by Raven Press (>Fuxe and Agnati 1991). There was a mixed response to the meeting. We provided further evidence for VT based on findings of transmitter-receptor mismatches in the NPY neuronal systems and of biological effects of NPY fragments. Miles Herkenham instead interpreted receptor-transmitter mismatches as implying endocrine functions in brain.

Bunnemann in my group, in collaboration with Professor Detlev Ganten, reported on a major role of VT in communication within the brain renin-Angiotensin system (RAS) and the angiotensin AT1 receptors. Bunnemann presented his thesis on RAS and VT in 1992. The angiotensinogene mRNA expression was restricted to the astroglia.

The most important support for VT in the brain was obtained from Professor Laurent Descarries in Canada. In his outstanding presentation, he demonstrated nonjunctional relationships of monoamine axon terminals in the cerebral cortex. In many cortical monoamine varicosities, there was a lack of synaptic junctions, which supported a role for VT. I am sad that Laurent is no longer with us, and I am happy that I could meet him at a neuroscience meeting a couple of years ago at Christmas time in Uppsala. We had a nice discussion on brain communication, especially VT. I did not know that he was ill.

In 1991, Professor Paul Trouillas and I organized a meeting at the Claude Bernard University in Lyon on “Serotonin, the Cerebellum and Ataxia.” The proceedings were published by Raven Press in 1993. Here we presented indications that the 5-HT, DA, and NA nerve terminal networks in the cerebellum can modulate synaptic transmission in the cerebellar cortex via VT. The Purkinje neurons were hypothesized to be major integrators of synaptic and VT.

We were also happy for the great work of Charles Nicholson along with Margaret Rice and of Eva Sykova on diffusion of ions and transmitters in the brain cell microenvironment presented at the meeting in 1990. This represented fundamental work. Börje Bjelke presented his experimental evidence on VT (see the previous section) along with a three-dimensional reconstruction of the prolactin-positive extracellular pathways. Our meeting on VT ended with the outstanding concluding remarks of Professor Jean-Perre Changeux.

In his 1994 thesis work, Börje Bjelke presented indications for VT in the dopamine terminal denervated striatum in the hemi-Parkinson model after amphetamine treatment. Dopamine transmission may be partly restored via systemic amphetamine treatment through the release of dopamine. The origin is unknown, but it may involve the release of DA from remaining DA nerve terminals on the lesioned side as well as from DA terminals on the unlesioned side. The results obtained were mainly from eletrophysiological (Dr. Strömberg) and microdialysis (Dr. O’Connor) studies. This paper illustrated the impact of having a team of experts to get the work done.

In 1995, Börje Bjelke, as the first author, obtained evidence for long-distance pathways of diffusion for dextran along myelinated fiber bundles in brain as well as along perivascular pathways. It indicated the existence as well of long-distance pathways for VT and was performed in collaboration with Dr. Englund and the groups of Professor Agnati and Professor Nicholson (Bjelke et al. 1995). In 1996, he produced another great paper on evidence for VT in dopaminergic communication in the rat retina, along with other experts like Drs. Goldstein, Tengroth, Seesack, Steinbusch, and Watson. He defended his great thesis on VT in an excellent way.

Dr. Anders Jansson started his thesis with me on VT in 1998. The title of his thesis was “Experimental Studies on the Sources, Pathways, and Targets for Volume Transmission in the Rat Brain.” He was a rock in the lab, and we established a great relationship. His first paper on VT was on the relationship of 5-HT neurons to 5-HT 2A receptor-immunoreactive neuronal processes in the brain stem of rats. The results indicated the existence of extrasynaptic VT (in the micrometer range) in 5-HT2A mediated 5-HT transmission in certain brain stem nuclei.

In 2000–2001, Jansson and colleagues including Barbro Tinner, a great laboratory assistant, and Steinbusch again explored the relationships of 5-HT immunoreactive terminal-like varicosities to 5-HT2A receptor-immunoreactive neuronal processes, this time in the forebrain (Jansson et al. 2001). The observations again suggested that 5-HT2A receptor-mediated 5-HT transmission in the forebrain mainly involves a VT process mediated through extrasynaptic diffusion in the um range in the extracellular fluid, which seems to be true for all monoamine transmitters (see the review by Fuxe et al. 2012).

Jansson and colleagues, including Barbro Tinner, also focused on the distribution patterns of D1 and D2 receptors in relation to TH and dopamine transporter immunoreactivities in the ventral striatum. The most important finding was the existence of nerve cell patches of strong D1 receptor IR associated with low D2 receptor, dopamine transporter, and TH immunoreactivities (Jansson et al. 1999). They may represent a compartment in which dopamine VT mainly acts on D1 receptors via a short diffusion distance in the range of 30–50 um, producing a delay in their activation by DA. This may represent part of a temporal-difference learning based on VT. Taken together, the findings give a new understanding of the chemical microarchitecture of the nucleus accumbens. These patches formed a continuous rostro-caudal tubular nerve cell system in the shell part of the nucleus accumbens.

That same year Jansson and colleagues, which included the Sykova group, studied the effects of nitric oxide inhibition on the spread of biotinylated dextran and on extracellular space parameters in the neostriatum. The observed changes after nonspecific nitric oxide synthase inhibition appeared to affect the extracellular space concentration of neurotransmitters. The actions on VT pathways were mainly linked to increased capillary and cellular clearance, although changes in extracellular space diffusion were lacking.

In 2000, Jansson and colleagues discussed clearance mechanisms for long-distance VT signals in the brain. This involved clearance over the brain-blood barrier and over the leaky brain-CSF interface. It can also occur through receptor-mediated uptake into other discrete nerve cell systems through internalization.

We were happy that Professor Laurent Descarries agreed to be the opponent of the Anders Jansson thesis on VT. I remember the fine interactions between them and the ambiance we shared at the celebration in a castle after the approval of his thesis, which was enhanced by excellent food and wine. It was a great day.

In 2002, we published a review together in the book Brain Homeostasis in Health and Disease, edited by Dr. Walz (Jansson et al. 2002). It dealt with transmitter-receptor mismatches in central DA, 5-HT, and neuropeptide systems. It gave further evidence for VT. Dr. Anders Jansson was the first author.

The next graduate student interested in doing a thesis on VT was Malin Höistad. She was highly motivated, showed excellence in the performance of the experiments, and came to my laboratory around 2000. Her coadvisor was Dr. Jan Kehr, an excellent biochemist and pharmacologist.

Her first paper dealt with dual-probe microdialysis to study long-distance diffusion. It involved intracerebral infusion of ³H-dopamine and the extracellular marker ³H-mannitol in the striatum. Unmetabolized ³H-dopamine could not be detected at the 1 mm distance. It was concluded that the spread of transmitters and compounds in the brain was highly dependent on the nature of the molecules infused. Classical transmitters like monoamines appear to be used for VT mainly at an extrasynaptic range of um as observed in the majority of our studies on the relationships of monoamine terminals and monoamine receptors. Finally, there were indications that in the DA nerve terminal denervated rat striatum versus striatum of controls, ³H-DA may cause an immediate increase of local CBF and capillary permeability. This enhanced the clearance processes of extracellular ³H-DA and its metabolites, which was demonstrated by a decline in their extracellular levels.

In the coming year, we continued our collaboration with Dr. Charles Nicholson and his team (Dr. Chen) in New York. This made it possible for Höistad to evaluate [³H]mannitol diffusion in agar and rat striatum involving the use of quantitative dual-probe microdialysis. This approach will be valuable in determining interstitial diffusion and the clearance processes supporting the dynamics of brain VT. A mathematical model and analysis was also introduced.

The last paper of the Höistad thesis (Hoistad et al. 2005) involved the detection of intact beta-endorphin in the CSF after intrastriatal microinjection of beta-endorphin. We needed experts from the Karolinska Institutet (Jenny Samskog, Ernst Brodin, Annica Olsson) and the University of Göteborg (Hans-Arne Hanson) to get the manuscript into a final state. Höistad found a significant intracerebral spread of the injected beta-endorphin, for example, into the globus pallidus via diffusion in the extracellular space. It was of high interest that beta-endorphin-IR became colocalized with the mu-opioid receptor-IR at the cell surface of the globus pallidus cell bodies. It was of high relevance to have indications that beta-endorphin may operate via long-distance VT to reach mu-opioid receptors and also via CSF VT globally activate the mu and delta opioid receptors in the CNS.

We have been interested in understanding the role of thermal microgradients for VT besides thermal macrogradients between active and inactive brain regions. The uncoupling proteins (UCPs) may help in the generation of thermal microgradients. They are found in the inner mitochondrial membrane in which they in part uncouple oxidative phosphorylation from ATP synthesis by decreasing the proton gradient over the membrane. This leads to the generation of heat and to a reduction of oxygen production. Therefore, UCPs can cause local temperature gradients and can increase the flow of neurotransmitters in the extracellular fluid. It was of special interest to study the presence of UCPs in transmitter-receptor mismatch areas. UCP2 like IR was found to be increased in the DA terminal rich regions in the nucleus accumbens shell surrounding the D1 receptor rich mismatch area. UCP2 like IR therefore may increase the diffusion or flow of DA into the mismatch regions by producing local temperature gradients, which will increase DA VT mediated by D1 receptors.

These results indicated the dynamics of VT and suggested a relevant role of UCP2 in VT. In this work, Dr. Alicia Rivera at the University of Malaga and Dr. Tamas Horvath at the Yale School of Medicine played an especially important role. Malin Hoistad was also a coauthor. Rivera established and gave evidence that UCP-like IR surrounded the transmitter-receptor mismatch region. She also observed UCP2-like IR in discrete dopamine terminal networks in the nucleus accumbens and in the cerebral cortex, whereas the IR was found in scattered noradrenergic terminals in the caudate putamen and Islands of Calleja Magna. I am especially fond of this paper.

We were happy that the expert Dr. Margaret Rice from the New York University School of Medicine accepted to be the opponent of Malin Hoistad’s thesis. Already at this time, Rice was one of the international leaders in the field of brain communication. I enjoyed the friendly battle between them on the day of the thesis defense. Both of them did an excellent job.

Malin Hoistad was my last graduate student, and I retired from my professor position in 2005. However, I was able to continue my research because I could keep my grant at the Swedish Research Council. I dramatically reduced my laboratory and office space to bring down the high costs of renting space at the neuroscience department.

In this period, I also had an excellent postdoc Alberto del Arco in my laboratory. He came from the Department of Physiology at the University of Complutense in Madrid. I also got to know his professor. His name was Francisco Mora. We were all interested in VT, so we wrote a review together in 2003. We introduced the concept that changes in dialysate levels of GABA and glutamate can be regarded as a result of GABA and glutamate VT in the CNS targeting receptors on neuron-astroglia networks. Professor Mora kindly invited Luigi Agnati and me to be coorganizers of an international conference in Madrid hosted by the Ramon Areces Foundation in 2008. It dealt with “Brain Plasticity, Aging and Neuropsychiatric Disorders.” At the lunch, I discovered Pacharan, a very old drink from the Middle Ages. It was originally made from sloe berries in the Navarra country and had a reddish color and a novel attractive taste, unknown to me. The president of the foundation was a kind man who spoke of science with high respect. I gave him my genuine thanks for accepting our conference. I was happy to help Professor Mora with a few additional conferences. We had great interactions and became friends.

In the coming years, we wrote several reviews on our concepts on VT together with Luigi Agnati and many other coauthors with titles like “From the Golgi-Cajal Mapping to the Transmitter-Based Characterization of the Neuronal Networks Leading to Two Modes of Brain Communication: Wiring and Volume Transmission” and “The Discovery of Central Monoamine Neurons Gave Volume Transmission to the Wired Brain” (Fuxe et al. 2007; Fuxe et al. 2010). Along with Luigi Agnati and Dasiel Borroto-Escuela, we also included the extracellular vesicles into VT and compared the role of transmitter diffusion and flow versus the role of extracellular vesicles in VT to understand their differential role (Borroto-Escuela et al. 2015). We also discussed the same year VT in central dopamine and NA neurons as they target the astroglia. It seems to me that today most neuroscientists accept the existence of VT in the CNS as a major mode of communication inter alia mediating glial transmission and modulating synaptic transmission.

VT also has a special value in neuropsychopharmacology because the VT concept is relevant for pharmacokinetics and thus for the actions of neuropsychoative drugs. Drugs may be considered as exogenous VT signals because they flow or diffuse in the extracellular space (volume). Their migration is limited by the same factors that limit the endogenous VT signals like transmitters, modulators, and ions. Neuropsychoactive drugs may interact more effectively with VT, which is less constrained than synaptic transmission.

There is also an impact of VT on Chinese medicine. Together with Professor Zhang at China Academy of Chinese Medical Sciences, Beijing, we had previously proposed that VT pathways of diffusion and flow in the interstitial fluid can underlie the acupuncture actions and the meridian phenomena. I had given lectures on VT at his department earlier, and we were in full agreement on this concept. To obtain indications whether or not this was true, alcian blue was microinjected under anesthesia into the fish Gephyrocharax melanocheir. It had the advantage for us of having a translucent body.

We discovered that the alcian blue could migrate and be recorded with a digital camera. Eight longitudinal threadlike blue tracks were found with positions similar to the meridians found on the body of humans (Zhang et al. 2017). The migration tracks were located in intermuscular septa and in different layers of loose connective tissue. Sometimes the blue tracks had an association with lymphatic vessels. These extracellular pathways may operate via VT through diffusion and flow of biological signals, which need to be identified. They give a new understanding of the acupuncture meridians and why they play a major role in Chinese medicine.

In my mind, based on the work with Professor Weibo Zhang, who is an excellent scientist and fully understands Chinese medicine, I believe that Eastern and Western medicine must be integrated. In doing so, we will begin to understand the biological mechanisms involved in Eastern medicine as exemplified in our work on VT. Improved treatment of human disease will then develop.

1990s Central GR Immunoreactive Neurons as Targets for Glucocorticoid Action

Graduate student Antonio Cintra came to my laboratory in the mid-1980s. He was a fine and quiet scientist of Brazilian origin. Antonio performed his experiments in an excellent way and gave support to our group under stressful conditions. I had great trust in him and I liked him. Dr. Antonio Cintra is now a medical doctor working in the field of gerontology in Sweden.

As part of his thesis, Cintra found GR IR in different classes of peptidergic neurons. Enkephalin nerve cells, especially in the basal ganglia, and all arcuate beta-endorphin nerve cells were GR positive. Conversely, the majority of the dynorphin nerve cells lacked GR IR. For most peptide systems, there were substantial differences among regions of the brain. In cerebral cortex, including hippocampus, the majority of the various peptide nerve cells did not show GR IR. Instead, the same types of peptide nerve cells in the arcuate and paraventricular nucleus like neuropeptide Y, somatostatin, and the cholecystokinin nerve cells exhibited intense GR IR. It seems likely that such differences depend on their participation in stress circuits. The paraventricular nerve cells show GR IR in their corticotropin-releasing factor, growth hormone-releasing factor, thyrotropin-releasing hormone, and somatostatin IR neurons, which indicates a neuroendocrine regulation by glucocorticoids.

Cintra also found prenatal development of GR gene expression and IR in the rat brain and pituitary gland. Thus, it seems possible that neurochemical and behavioral impairments can be caused by prenatal stress.

Cintra’s major papers describe the mapping of the GR IR neuronal and glial cell populations in the rat CNS. This also involved computer-assisted morphometric and microdensitometric evaluations. Nuclear GR IR profiles of neuronal and glial cells were found all over the CNS but in a heterogeneous way. Thus, glucocorticoids can modulate a large number of nerve and glial cells by changing their gene expression. The GR IR neurons, however, seem to be major target for glucocorticoids. The results emphasize the actions of glucocorticoids both in regions known to be involved in stress responses and in regions not linked to such responses, indicating that glucocorticoids have more widespread effects in their modulation of brain function. Our interpretation is that glucocorticoids can modulate the neural-glial networks of many brain regions to produce an optimal integration of these networks to assist in the survival of the individual under stress conditions. Taken together, the Cintra papers indicate that GR is a modulator of neuronal and glial plasticity throughout life from the beginning in the fetal and postnatal period until the adult and aging period, when the intensity of GR IR in the neuronal cells becomes reduced.

1990s Functional Interactions between Different Types of Receptors and G-Proteins in Native Brain Membranes: Activation of High-Affinity GTPase Activity by Receptor Agonists in Hippocampal and Striatal Membranes

Dr. Yuji Odagaki came to my laboratory in the mid-1990s on a fellowship from Japan. He was interested in developing a technique to determine agonist-induced high-affinity GTPase activity, which I thought was a fine idea. He established the method in a perfect way, and we got beautiful results. Our families met, and we had good interactions with Yuji and his wife Tomoko. We have had great discussions in Kyoto, Seoul, Berlin, and Copenhagen in relation to ECNP and CINP congresses and congresses in biological psychiatry.

The method was established by determining DA-stimulated high-affinity GTPase activity in striatal membranes. D2 receptors mediated the actions via activation of Gi proteins. High-affinity GTPase activity was also stimulated by carbachol and acetylcholine and was mediated by pirenzepine-insensitive muscarinic receptors. Both receptors were coupled to Gi proteins, which inhibited AC activity. A detailed method paper was published in 1997 focused on “Agonist-Induced High-Affinity GTP Hydrolysis as an Index of Receptor-Mediated G Protein Activation in Mammalian Brain Membranes.” GTP hydrolyzing activity was determined from the amount of 32P released from [gamma-32P] GTP in the membranes.

Dr. Odagaki and I were both interested in depression and the role of 5-HT receptor subtypes in this disease. We found that 5-HT-stimulated high-affinity GTPase activity of the G protein involved the 5-HT1A receptor in the hippocampal membranes and its coupling to Gi. A pharmacological analysis of high-affinity GTP hydrolyzing activity was also performed involving the use of 5-HT receptor agonists and antagonists. The functional interaction between the 5-HT1A receptors and G proteins, in particular the Gi subfamily, can be studied using this method.

The method could be modified to determine high-affinity GTPase activity mediated via adenosine receptors in hippocampal membranes. It was possible to determine via a pharmacological analysis that the adenosine A1R mediated this interaction, producing Gi/o activation and inhibition of AC. It is of substantial interest that additivity between high-affinity GTPase activities mediated via A1Rs and 5-HTlA receptors was observed. These results suggest that A1R and 5-HT1A receptors are linked independently to distinct pools of Gi/o-proteins. How these events at two pools of Gi/o proteins become integrated at the level of, for example, AC, mitogen-activated protein kinases (MAPK), and G protein-gated inwardly rectifying potassium (GIRK) channels is unknown.

1990s to Present: Evidence for the Existence of Allosteric Receptor-Receptor Interactions in Homo- And Heteroreceptor Complexes in the CNS, a Major Molecular Integrative Mechanism

In 1993, we introduced along with the Agnati group the concept that the intramembrane receptor-receptor interactions took place in receptor heterodimers, which could be formed from the corresponding homodimers or monomers (Zoli et al. 1993). The heterodimer formed the molecular basis for the receptor-receptor interaction. We underlined that the receptor heterodimer represented a novel integrative mechanism in the plasma membrane.

The A2A-D2 Receptor Heteromer and Its Function

In 1974, we had found that the methylxanthines could enhance the levodopa and DA receptor agonist–induced contralateral turning behavior in the hemi-Parkinson rat model (Fuxe and Ungerstedt 1974), which was indicated to be related to an adenosine receptor action. Based on this paper and on the ability of methylxanthines to enhance DA receptor action, we decided to mainly focus our work on the possible existence of adenosine receptor-dopamine receptor interactions. In my group, mainly Dr. Ferre and graduate student Maria Torvinen were involved. In a collaboration with Professor Fredholm, we were able to demonstrate antagonistic A2A-D2 receptor-receptor interactions, leading to a reduction of D2R affinity in the high-affinity state (Ferre et al. 1991). These results obtained in the striatal membranes supported our 1974 findings that adenosine receptor antagonists enhanced DA receptor actions.

On the basis of this paper, we proposed the use A2A receptor antagonists in the treatment of PD. Thanks to Dr. Dasgupta in our lab, in 1996, we were able to validate the striatal results in A2A-D2 stably cotransfected fibroblast cells with the additional help of Dr. Björn Kull and Dr. Ernest Arenas.

In 1995, we had observed in studies on intracellular calcium levels a reduction of dopamine D2 receptor transduction by activation of adenosine A2a receptors in stably A2a/D2 (long-form) receptor cotransfected mouse fibroblast cell lines. We were happy for a collaboration with Professors Lledo and Vincent and their team, especially Dr. Salim at Institute Alfred Fessard at Gif-sur-Yvette. Through this fine collaboration, it was possible to study A2A-D2 receptor-receptor interactions in D2R stably transfected human neuroblastoma cells constitutively expressing A2AR. They found that the A2 receptor agonist CGS-21680 acutely counteracted the D2 receptor-induced [Ca2+] responses. We appreciated very much the important results from these outstanding neuroscientists who provided evidence that A2A receptors can reduce D2R signaling. They showed warm hospitality at our visit to the Albert Fessard Institute, and I regarded them as my friends.

Note that in 1991 Ferre found that stimulation of A2A receptors produced catalepsy, and in 1997, Roberto Rimondini and colleagues in our laboratory established the atypical antipsychotic features of A2A receptor agonists, which included help from Dr. Sven-Ove Ögren at the department. He completed his thesis with me in 1999 with the title “Behavioral and Biochemical Pharmacology of Adenosine-Dopamine Receptor-Receptor Interactions.” He did an excellent job and is now back at the University of Bologna, Italy. Together with Professor Urban Ungerstedt and Dr. O’Connor working in his group, in 1993, we demonstrated with microdialysis that the main locus for A2A-D2 receptor-receptor was in the striato-pallidal GABA neurons.

An important step in demonstrating the relevance of A2A receptor antagonists for the treatment of PD came in the beautiful work led by Dr. Ingrid Strömberg at our department in 2000. She demonstrated in the hemi-Parkinson model that subthreshold doses of the A2A receptor antagonist MSX-3 substantially increased the action of the D2R agonist quinpirole on striatal firing rate; instead, the A2A receptor agonist produced the opposite actions.

Through a collaboration with Dr. Yasmin Hurd and Professor Vanderhaegen in Brussels, my outstanding postdoc Zaida Diaz-Cabiale was able to demonstrate that adenosine A2A agonist CGS 21680 decreased the affinity of dopamine D2 receptors for dopamine in human striatum. Thus, the A2A-D2 heteroreceptor complexes also may exist in the human brain.

Around 2000, we started our collaboration with Professor Rafael Franco and his group at the University of Barcelona. The Fuxe and Franco teams, which also included the Agnati team, made a major effort to obtain indications for the existence of A2A-D2 heteromers, which we believed to exist based on our concept from 1993. The first paper came out in 2002, and Joel Hillion in my group was the leading author.

A2AR-D2R heteroreceptor complexes were found in coimmunoprecipitation experiments in membrane preparations from cell models expressing A2A and D2 receptors. Combined treatment with A2AR and D2R agonists produced coggregation, cointernalization, and codesensitization of the A2A and D2 receptors. In 2003, came further evidence for the existence of A2AR-D2R heteromerization using fluorescence resonance energy transfer (FRET) and bioluminescence resonance energy transfer (BRET) performed in the Franco laboratory in collaboration with the expert Professor M. Bouvier. The A2A homodimerization was found the following year by the same techniques in the Franco laboratory.

In 2001, there were indications from the work of Dr. Patrizia Popoli together with our group that an mGlu5R agonist could reduce the D2R agonist-induced contralateral turning behavior in the hemi-Parkinson model and also could reduce the affinity of the D2R agonist binding sites in line with our early work in the 1970s on the glutamate modulation of D2 agonist binding sites. Synergistic interactions between mGluR5 and A2A receptors were indicated. In a follow-up paper in 2002, Ferre and colleagues found the existence of A2A-mGluR5 complexes based on immunoprecipitates from inter alia striatal membrane preparations, which may be the basis for synergistic A2AR-mGluR5 interactions. In 2009, the Francisco Ciruela group at the University of Barcelona found evidence that mGluR5, dopamine D2, and adenosine A2a receptors form higher-order oligomers in living cells.

In 2004, Dr. Amina Woods pioneered the understanding of the A2A-D2 receptor interface. She demonstrated direct epitope-epitope electrostatic interactions between adenosine A2A and dopamine D2 receptors involving cytoplasmic intracellular loop3 of the D2R and the C-terminal of the A2AR. Mass spectrometry was used, and Dr. Ciruela validated her results with pull-down techniques. It is a beautiful paper. In 2008, I was happy to be part of another paper by Woods and colleagues. Calmodulin was indicated to disrupt the electrostatic interactions between the D2 receptor epitope and the more distal A2A receptor epitope.

In 2005, we wrote a review on the A2A-D2 heteroreceptor complexes and their function in a special issue of the Journal of Molecular Neuroscience (Fuxe et al. 2005). Writing this review, I realized how little you can do on your own with the limited budget you have. You need national and international teams to work together to determine whether or not novel concepts on molecular mechanisms are correct. Out of this effort also novel or revised hypotheses may develop.

This special issue contained the proceedings of a Wenner-Gren Foundation symposium we organized in Stockholm in 2004 on receptor-receptor interactions among GPCRs, “From Structure to Function.” I enjoyed my discussions with Fiona Marshall who gave a fine lecture on the GABAB heterodimer. I was happy and honored that Nobel Laureate Robert Lefkowitz gave the concluding remarks of the meeting. They made clear his outstanding leadership in the GPCR field. I had great interactions with Robert.

A2A-D2 Heteroreceptor Complex Studies after the Arrival of Postdoc Dasiel Borroto-Escuela in the Laboratory in 2009

Dr. Dasiel Borroto-Escuela was an outstanding biochemist from the University of Havana and a PhD from the Universitat Politècnica de Catalunya, of Cuban origin. He mastered molecular biology and markedly increased the strength of our laboratory by setting up BRET and FRET as well as luciferase reporter gene assays and proximity ligation assays. Through his great contribution, we could together obtain evidence for the existence of a large number of receptor-receptor interactions in heteroreceptor complexes and their function. This work is still ongoing and intense and involves crucial collaboration with outstanding teams in Europe.

With regard to A2A-D2 receptor heteromers, we found that a point mutation of serine 374 to alanine reduced the A2A-D2 receptor heteromerization. This point mutation also abolished the A2A receptor agonist–induced reduction of the high-affinity D2 receptor agonist binding and signaling (Borroto-Escuela et al. 2010b). In a subsequent paper, we found that mutations of two negatively charged aspartates in the C-terminal tail (D401A/D402A) of the A2A receptor together with the S374A mutation markedly diminished the heteromerization with the loss of the antagonistic allosteric A2A-D2 receptor-receptor interaction. These results gave further evidence for an important role of the electrostatic receptor-receptor interactions in the receptor interface of the A2A-D2 receptor heteromer. Incubation with peptides corresponding to the transmembrane (TM) domains IV and V significantly reduced the A2A and D2 receptor heteromerization. Thus, these TM domains of the D2 receptor play a major role in the A2A-D2 receptor interface. It presented a novel development.

In this paper, postdoc Wilber Romero-Fernandez also participated. He had just arrived from the same University in Barcelona as Dasiel and became part of our team on receptor-receptor interactions in heteroreceptor complexes. Mutation of the arginine residues (217-222 and 267-269) on the intracellular loop 3 of the D2 receptor performed by the Ciruela group finally established a major role of these positively charged residues in producing the allosteric A2A-D2 receptor-receptor interaction.

In 2010–2011, we pointed out the importance of adenosine-dopamine interactions in A2A-D2 heteroreceptor complexes in the pathophysiology and treatment of CNS disorders also involving a regulation of glutamate transmission, especially mGluR5 signaling.

Of substantial interest were the findings of Borroto-Escuela and colleagues (Borroto-Escuela et al. 2011) that the antagonistic A2A-D2 receptor-receptor interactions enhanced beta-arrestin2 recruitment to the D2 receptor protomer leading to subsequent cointernalization and an earlier time onset of Akt phosphorylation, rapidly followed by a dephosphorylation. The results opened up the existence of a possible A2A-D2-beta-arrestin2 complex.

Jeffrey, in 1999, introduced the term “moonlighting protein” for a multifunctional protein in which different functions are found in single strands of amino acids not linked to splicing. GPCR protomers can moonlight through the allosteric receptor-receptor interactions. As an example, the third intracellular loop of D2 can moonlight through the allosteric mechanism by switching between interactions with different types of G proteins, between G proteins and beta-arrestin2, or between G proteins and calmodulin.

A2A-D2 Receptor Heteromers and Drug Addiction, Especially Cocaine Addiction

This work became possible through a highly rewarding collaboration with Professor Malgorzata Filip and her group, notably with Malgorzata Frankowska and Karolina Wydra at the Laboratory of Drug Addiction Pharmacology, Institute of Pharmacology, Polish Academy of Sciences in Krakow. Our collaboration started around 2005 and is still intensely ongoing, in which Dr. Borroto-Escuela has a crucial role. The first paper was published in 2006 and suggested an antagonistic modulation of D2 receptor-induced actions by cocaine involving A2A/D2 heteroreceptor complexes. Through a collaboration with Professor Luca Ferraro and Professor Sergio Tanganelli and their groups, we were able to obtain indications that a novel mechanism independent of DA transporter blockade was involved in the cocaine actions. That same year Filip and her group wrote a review, which I was happy to be part of. The review proposed that A2A-D2 receptor-receptor interactions may play an overall important role in drug addiction in view of the fundamental role of the midbrain mesolimbic DA neurons in reward. It was interesting to observe that in the ventral and dorsal striatum differential changes were observed in the A2A and D2 receptors during cocaine self-administration maintenance and its extinction.

Another finding of interest was that changes in DA and GABA extracellular levels in nucleus accumbens using microdialysis during cocaine self-administration maintenance appeared to follow the motivational aspects of cocaine intake as demonstrated especially by Drs. Wydra and Krystyna Golembiowska. Both pharmacological and transgenic approaches were employed in findings that A2A receptor signaling counteracts locomotor sensitization known to be linked to nicotine reward-learning.

Of high interest was the finding published in Psychopharmacology that an antagonistic A2AR-D2R interaction can help mediate the inhibitory actions of an A2AR agonist, injected into the nucleus accumbens shell, on cocaine seeking and cocaine reward using cocaine self-administration. The A2AR-D2R interaction led to an increase in GABA release in the nucleus accumbens, likely reflecting an increased activity in the ventral striato-pallidal GABA anti-reward pathway (Fuxe et al. 2008). In a subsequent psychopharmacology paper, it was shown that A2AR agonists counteracted cocaine seeking as well as its reinstatement by cues. Instead, A2AR antagonists could reinstate cocaine seeking, blocked by D2 receptor antagonists. Food seeking was modulated in a similar way. Brain-penetrant heterobivalent drugs with, for example, A2AR agonist and D2R antagonist pharmacophors, may be one novel strategy to treat cocaine abuse. They should preferentially target the A2AR-D2R heteromer to increase activity in the GABA antireward neurons.

In 2016, we studied the allosteric A2AR-D2R interactions after cocaine self-administration versus yoked saline controls. A significant reduction in the affinity of the D2R high-affinity state was found after A2AR activation following cocaine self-administration in the ventral striatum but not in the dorsal striatum versus respective control groups. We proposed that differential recruitment of sigma 1 receptor to the ventral striatum can help understand the mechanism involved. In this way, the A2A-D2-Sigma1 receptor may be formed only in the ventral striatum after maintenance of cocaine self-administration. This event can lead to the observed increase in the antagonistic A2A-D2 receptor-receptor interactions. The target for the anticocaine actions of A2A receptor agonists therefore may be the A2A-D2 heteroreceptor complexes in the ventral striatum.

The details of our hypothesis focused on A2A-D2 heteroreceptor complexes, as a target for cocaine actions was found in the Journal of Neural Plasticity in 2016. In 2017, using the proximity ligation assay, we followed up the Pintsuk paper (Pintsuk et al. 2016) with findings that cocaine self-administration can reorganize the panorama of A2A and D2 homoreceptor complexes and receptors monomers into an increased formation of A2A-D2 and D2R-sigma1R heteroreceptor complexes in the nucleus accumbens shell (Borroto-Escuela et al. 2017). Such a reorganization can reflect the development of an increased density of A2AR-D2R-sigma1R heterocomplexes with improved antagonistic allosteric A2A-D2 receptor-receptor interactions as indicated by Pintsuk and colleagues. This is the first evidence that A2A-D2 heteroreceptor complexes can be a novel target for the treatment of cocaine abuse and cocaine addiction.

The A1-D1 Receptor Heteromer

We provided biochemical and behavioral results indicating the existence of antagonistic A1R-D1R interactions in collaboration with Dr. Popoli in Rome and Dr. Lydia Gimenez-Llort at our department at Karolinska Institutet. In 1998, we validated the antagonistic adenosine A1 receptor-mediated modulation of dopamine D1 receptors in stably cotransfected fibroblast cells. Graduate student Torvinen played an important role with help from Ferre, Arenas, Civelli, and the Fredholm team. The antagonism exerted by A1 receptors led to a reduction in both D1 receptor recognition and signaling. In 2000, Torvinen was a coauthor in our papers with Professor Franco, demonstrating by means of coimmunoprecipitation the existence of agonist regulated A1R-D1R heteroreceptor complexes in fibroblast cells cotransfected with A1R and D1R receptors (Franco et al. 2000). The article by Franco and colleagues was published in a special issue based on presentations at a special symposium on receptor heteromerzation being linked to the Society of Neuroscience meeting in 1999. We appreciated the good work performed by Dr. Gines on the Franco team.

In 2002, Torvinen as first author published the last paper of her thesis. It dealt with interactions among adenosine deaminase, adenosine A1 receptors, and dopamine D1 receptors in stably cotransfected fibroblast cells and neurons. It was part of a collaboration mainly with the Franco group. She demonstrated the importance of having adenosine deaminase bound to the A1 receptor for the development of the antagonistic A1-D1 receptor-receptor interaction. I was proud of her thesis and liked her fine spirits. She did a great job, and in 2005, she was the first author of a paper demonstrating the existence of A2A-D3 heteroreceptor complexes with FRET in cell lines with antagonistic A2A-D3 receptor-receptor interactions. Antagonistic interactions were demonstrated leading to reduced affinity and signaling of the D3 receptor. The results opened up a new target for treatment of schizophrenia, should the A2A-D3 complex exist in the brain. This was the result of a fine collaboration with the Franco team.

In the brain, we found in 1996 the antagonistic A1R-D1R receptor-receptor interactions to be located in the strio-entopenduncular/nigral GABA pathway, known as the direct pathway. The paper involved the participation of the Fuxe, Fredholm, and Ungerstedt teams and Dr. Strömberg at the Karolinska Institutet. The role of the A1R-D1R heteroreceptor complexes in the reward neurons of the nucleus accumbens remain to be studied. Rafael Franco and I wrote reviews on this work in 2007.

The Neurotensin R(NTSR)-D2 Receptor Heteromer and Its Function

In 1992, together with the Ungerstedt and Tanganelli groups using microdialysis, evidence was obtained that antagonistic NTSR-D2R interactions at the pre- and postsynaptic level resulted in a DA transmission dominated by D1Rs. Thus, the heteroreceptor complexes could alter the plasticity of striatal DA transmission. In a lecture in New York, we also proposed that intramembrane interactions between neurotensin receptors and D2 receptors represented a major mechanism for the neuroleptic-like action of neurotensin.

In 1992, graduate student XM Li arrived in the laboratory. He did a great job and found in 1993 that the NT peptide neuromedin N (NN) also was a potent modulator of striatal D2 receptor agonist binding sites in dorsal striatum by reducing their affinity. That same year he also found that the C-terminal neurotensin fragment (8-13) could reduce the affinity of the neostriatal D2 receptors and with higher potency and efficacy than NT.

In 1994, Li made the important observation that NT/NN peptides demonstrate a stronger reduction in the affinity of the striatal D2R agonist binding sites in brain sections compared with membrane preparations. This indicated the participation of cytoplasmatic factors like enzymes, such as protein kinases, to optimize the receptor-receptor interactions in the plasma membrane, and a likely demand for a relatively intact plasma membrane structure. In two lectures in New York in this period, we pointed out that the mechanisms for the high modulatory potency of neuropeptides can involve their ability to act as VT signals and also often via active fragments to modulate WT through receptor-receptor interactions at nanomolar concentrations. This also gave diversity to the receptor protomers involved.

Tanganelli and colleagues in 1994 through microdialysis work made the discovery that NT in nucleus accumbens, in contrast to dorsal striatum, reduced DA release. This involved increased GABA release induced by NT through the antagonistic NTSR–D2R interaction on the ventral striato-pallidal GABA pathway or their glutamate afferents (Tanganelli et al. 2012). The findings indicated that through GABA VT mediated via GABAA receptors on the DA terminals, DA release was reduced. The NT receptors were not present on the accumbens DA terminals. These results offered one mechanism for the proposed antipsychotic role of NT in schizophrenia proposed by Nemeroff. I met Nemeroff a couple of times, but he did not seem to like our NTSR-D2R story very much.

Through a combined D2R binding and microdialysis study in 1995 performed by Drs. XM Li, Dr. Ferraro, and Professor Tanganelli, further evidence was obtained that NT peptides via NTSR-D2R interactions antagonistically regulated postsynaptic D2Rs in the nucleus accumbens. This evidence strengthened our hypothesis that the antagonistic NTSR-D2R receptor-receptor interactions in the nucleus accumbens was part of the mechanism for the atypical antipsychotic profile of NT peptides.

Dr. Luca Ferraro was an outstanding associate professor of pharmacology in the University of Ferrara and Sergio Tanganelli and Luca Ferraro formed a great team. They found in 1997 that the NT fragment 8-13 lacked effects on the striatal DA release in contrast to NT itself. This finding opens up the possibility that the NTSR-D2R autoreceptor complex is different from the corresponding postsynaptic complex, leading to a differential change in the NTR recognition through altered allosteric receptor-receptor interactions.

In 2002, through a collaboration with Dr. Diaz Cabiale at the University of Malaga, we could block the NTSR-D2R receptor-receptor interactions with an NTSR1-like receptor antagonist. Ferraro and colleagues published a review in Brain Research Reviews in 2007 on mesolimbic DA neurons and cortico-accumbens glutamate afferents as major targets for the regulation of the ventral striato-pallidal GABA pathways by neurotensin peptides.

In 1995, the Ferraro-Tanganelli team found that NT can release endogenous glutamate in the dorsal striatum in the awake rat. In 2002, Dr. Tiziana Antonelli at the University of Ferrara found that NT enhances glutamate excitotoxicity in midbrain neurons in collaboration with Ferraro and Tanganelli. Antonelli also found that NT receptors can be involved in N-methyl-D-aspartate (NMDA)-induced excitotoxicity in primary cultures of cortical neurons and published a review on these significant results in Progress in Neurobiology in 2007, including their relevance for neurodegenerative diseases and their treatment. Of high interest was the review in Mini-Reviews in Medicinal Chemistry by Ferraro, Antonelli, and colleagues in 2009 on “Emerging Evidence for NT Receptor 1 Antagonists as Novel Pharmaceutics in Neurodegenerative Disorders.” Also, the idea of NMDA-NTSR1 receptor-receptor interactions was introduced in addition to the NTSR1-D2R receptor-receptor interactions (Ferraro et al. 2012; Tanganelli et al. 2012). It was proposed that NTSR1 antagonists represent a novel strategy for treatment of PD.

The paper in 2013 by Borroto-Escuela and colleagues was of high importance. For the first time evidence could be given for the existence of D2LR-NTS1R and D2SR-NTS1R heteromers in cell models using the BRET² technique. The cAMP responsive element binding (CREB) reporter gene assay demonstrated that NTSR1 activation inhibited the CREB signaling. Instead, using the NTSR1 agonist, there was an enhanced activation of the MAPK intracellular pathway, which likely was mediated by enhanced activation of PKC in the MAPK cascade. Instead, the antagonistic allosteric receptor-receptor interactions in the plasma membrane was responsible for the reduction of the D2R mediated inhibition of the Gi/o-AC-protein kinase A (PKA)-CREB pathway by agonist activation of NTSR1. The Borroto-Escuela paper in 2013 gave evidence that the antagonistic NTSR1-D2R interaction (Borroto-Escuela et al. 2013), first observed in 1983 by Agnati and colleagues, likely took place in an NTSR1-D2R heteromer as observed 20 years later.

Putative CholecystokininR-D2R Heteromers and Their Receptor-Receptor Interactions

In 1990, Tanganelli and colleagues followed up our early work from the 1980s (Fuxe et al. 1983) by giving a functional correlate to the CCK-8 induced reduction of D2 receptor affinity. He found that CCK-8 in low concentrations could enhance striatal DA extracellular levels likely through an antagonistic CCKR-D2R autoreceptor interaction on the striatal DA nerve terminals. In 1993, Tanganelli also found that nanomolar concentrations of NT and CCK-8 synergistically counteracted the apmorphine-induced inhibition of DA release in the dorsal striatum. Li, in the same paper, found that these effects were associated with a synergistic reduction of D2R affinity in biochemical binding experiments. The mechanism involved may be linked to the observations that CCK-8 reduced the association rate constant of the D2Rs, while NT increased their dissociation rate constant.

The CCK-8 Induced Reduction of the Affinity of D2R Agonist Binding Sites Was Blocked by a CCKB Receptor Antagonist

It was unexpected that a nanomolar concentration of CCK-8 instead increased the affinity of the D2R agonist binding sites in DA competition experiments for D2R antagonist binding sites performed in dorsal striatal membranes. This action was blocked not only by CCKB but also by CCKA receptor antagonists. The fact that the D1R antagonist also blocked the CCK-8-induced increase in D2R affinity helped us understand the mechanism of action. We proposed that DA, through its activation of D1Rs, can recruit D1Rs to D2R-CCKB heteroreceptor complexes. The formation of putative D1R-D2R-CCKB heteroreceptor complexes with the possible presence of CCKA receptors will then alter the D2R-CCKB allosteric receptor-receptor interaction and an increase in the D2R protomer affinity develops. Susan George has demonstrated that D1R-D2R heteromers do exist. Jonathan Javitch, however, has pointed out that these heteromers exist only in a low percentage of the neurons. In our minds, we should consider the possibility that agonist activation of the D1Rs in neurons that express both D1 and D2R may increase the formation of D1R-D2R heteroreceptor complexes, which can help explain our findings. We plan to start by testing this hypothesis in cellular models.

In 1995, XM Li and colleagues made one highly interesting observation, namely, that CCK-8 can much more strongly modulate the D2R affinity in the dorsal striatum and in the nucleus accumbens when using receptor autoradiography, which involves sections compared with biochemical binding experiments using membrane preparations. As discussed previously, this may be related to the need for a more intact membrane structure and participation of intracellular mechanisms like protein phosphorylation and dephosphorylation to optimally perform the receptor-receptor interactions in the plasma membrane, at least for certain types of receptor complexes in the plasma membrane. Another interesting finding was that strong modulation was also found ex vivo after intraventricular injection of CCK-8.

In 1996, Dasgupta and colleagues found that the reduction of D2R affinity by CCK8 also was found in cells cotransfected with CCKB and D2L receptor cDNAs. Notably, the enhancement by CCK-8 of GABA and dopamine release in the accumbens likely reflects an inhibitory effect CCK-8 on both pre- and postsynaptic D2Rs through CCKB receptors. Instead CCKA receptors inhibit GABA release via cholinergic mechanisms.

In brief, the findings indicate the existence of antagonistic CCKB-D2 receptor-receptor interactions on the ventral striato-pallidal GABA antireward neurons, which can reduce the D2R brake on GABA transmission in this system. CCK-B agonists therefore may have antipsychotic actions, which can enhance the therapeutic effects of D2R antagonists, representing known antischizophrenic drugs. Likewise CCKB agonists should synergize with NTSR1 agonists to increase the brake on the D2Rs of these antireward neurons, which should enhance their activity and produce antipsychotic actions. There is also a need to increase the activity of these antireward neurons in drug use disorders. Therefore, in this case, CCKB-D2R heteroreceptor complexes also should be a new target for treatment of drug abuse. This story on the putative CCKB-D2R heteroreceptor complexes is far from complete and demands the demonstration that these receptor complexes in fact exist in the brain.

Neuropeptide Y (NPY) Y1-Alpha2 Adrenoceptor, NPYY2-Alpha2 Adrenoceptor, and Angiotensin AT1-Alpha2 Adrenoceptor Receptor-Receptor Interactions in Central Cardiovascular Regulation: Focus on the NTS

In the early 1990s, we had an excellent graduate student Shao-Nian Yang from China interested in central cardiovascular regulation. We were lucky to have Professor Jose Narvaez from University of Malaga and his postdoc Jose Aguirre in the laboratory who were experts in cardiovascular regulation. Jose Narvaez is now rector of the University of Malaga. Dr. Debora R. Fior from San Paulo, Brazil, also were with us and had interest in cardiovascular transmitters and modulators. In addition, we had also a long-standing collaboration with Professor Detlev Ganten in Germany on the brain renin-angiotensin system, which operated via VT. One of his students Bernd Bunnemann had become a graduate student with me in this period. The stage was set for understanding how the NPY receptors and angiotensin II receptors modulated the alpha2 adrenoceptors as well as their reciprocal interactions in the NTS. They formed a great group.

In 1993, we found that microinjections of the NPYY2 agonist NPY (13-36) into the NTS counteracted the vasodepressor actions of NPY (1-36) and of a NPYY1 receptor agonist. Thus, the NPY fragment may exert an inhibitory feedback on the NPYY1 receptor through a possible direct feedback via antagonistic NPYY2-NPYY1 receptor-receptor interactions. We demonstrated that the NPYY1 receptor IR was located on CA nerve cells in the medulla oblongata, including the NA cell bodies of the NTS, known to have alpha2 adrenoceptors. Yang and colleagues in 1995 could validate the findings of Harfstrand (Harfstrand and Fuxe 1987) by demonstrating that coinjections of NPY (1-36) or a NPYY1 agonist with adrenaline could block the vasodepressor responses to adrenaline. These findings taken together opened up the possibility that at least part of the action may take place at NPYY2-NPYY1-alpha2 adreno-heteroreceptor complexes located on the NTS NA neurons at the presynaptic or postsynaptic levels.

It is of substantial interest that upon alpha2-adrenoceptor activation in the NTS, there is the appearance of an antagonistic alpha2-adrenoceptor-NPYY2 interaction associated with an enhanced signaling over the NPYY1 receptor, as demonstrated by Yang and colleagues in 1994. This may be related to the removal of the inhibitory NPYY2-NPYY1 receptor-receptor interaction.

In the spontaneously hypertensive rat, the potency of NPY to antagonize the alpha2-adrenoceptor signaling was enhanced relative to the normotensive strain, which may contribute to the hypertension development. Errors in receptor-receptor interactions thus may contribute to disease processes.

An antagonistic angiotensin IIR-alpha2-adrenoceptor interaction was also demonstrated in the NTS, which was disturbed in spontaneously hypertensive rats. In 1995, Fior and I also found a bradykinin receptor modulation of the alpha2 adrenoceptors in NTS upon its activation by bradykinin.

The possible existence of NPYR-AT1R-alpha2-adrenoceptor heterocomplexes with multiple receptor-receptor interactions is still unknown. However, NPY-angiotensin II interactions were found in central cardiovascular regulation by Aguirre and colleagues in 1991 and published in Brain Research (Aguirre et al. 1991).

GalaninR-5-HT1A, 5-HT1A-5-HT2A, and GalR1-GalR2 Receptor-Receptor Interactions

Around 1990, Peter Hedlund came to our laboratory as a graduate student. His thesis project was to develop the concept on the existence of the galaninR-5-HT1A receptor-receptor interactions. He started by studying the reciprocal interaction and found that 5-HT1A activation increased the affinity of the high-affinity galanin receptors in the tel- and diencephalon using receptor autoradiography. We also found along with Jose Aguirre and Jose Narvaez in 1991 that galanin and a 5-HT1A agonist synergize to produce vasodepressor responses.

In view of the failure to observe high-affinity galanin receptor binding sites in the dorsal hippocampus, the neocortex, and the dorsal striatum, we started to also use [¹²⁵I]galanin-(1-15) as a radioligand. We discovered [¹²⁵I]galanin-(1-15) fragment binding sites in the previously noted areas of high specificity. The results suggested that a special type of galanin receptor may exist in brain with a high and selective affinity for N-terminal galanin fragment binding sites. In line with these results, we found that galanin (1-15) but not galanin (1-29) reduced the affinity of the 5-HT1A agonist binding sites in membrane preparations of the dorsal hippocampus.

In support of these results, José A. Narvaez and his collaborator Zaida Diaz-Cabiale found that galanin-(1-15) has a different role than galanin-(1-29) in central cardiovascular regulation. The action of the fragment was blocked by a galanin receptor antagonist. Diaz-Cabiale demonstrated in 1996 that galanin-(1-15) but not Gal-(1-29) decreased the baroreceptor reflex.

We wrote three reviews on this work for the Annals of the New York Academy of Sciences. One was prepared in 1996 by Hedlund and I on galanin receptor-5-HT1A receptor-receptor interactions as an integrative mechanism in 5-HT neurotransmission. I prepared the second review with colleagues in 1998 on how galanin and galanin fragments modulates 5-HT receptors and their function. The third review was prepared by Diaz-Cabiale and colleagues in 1998 on the role of galanin and N-terminal galanin fragments in central cardiovascular regulation.

GalR-5-HT1A autoreceptor interactions also exist in the 5-HT cell bodies and dendrites of the dorsal raphe shown by Haleh Razani and colleagues in 2000 as part of her thesis.

Dr. Inmaculada Bellido and colleagues in our group found in 2002 a significant increase of galanin receptors in dorsal raphe in a genetic rat model of depression, which correlated with an increase in immobility in the forced swim test. Thus, Gi/o-coupled galanin receptors in the dorsal raphe may contribute to depression.

In an exciting paper from 2010, evidence for the existence GalR1-5-HT1A receptor heteromers was finally obtained in cellular models by Borroto-Escuela and Manuel Narváez using FRET (Borroto-Escuela et al. 2010c). Through CRE-luciferase and SRE-luciferase reporter assays, the signaling over MAPK or AC pathways in this heteromer was demonstrated. Results revealed an allosteric cross-inhibition between both signaling pathways, which avoids excessive inhibition of the AC pathway or an increase in the MAPK pathway.

We hypothesized in 2008 and 2012 that the Gal fragment-preferring sites developed through the existence of a GalR1/GalR2 heteroreceptor complex (Fuxe et al. 2008). The evidence was obtained in a great paper from 2014 by Borroto-Escuela and colleagues using BRET² assays in cellular models. Through proximity ligation assays, evidence was obtained that GalR1-GalR2 heteroreceptor complexes were also present in the raphe-hippocampal system. We found a preferential activation by Gal (1-15) of the GalR1 protomer versus galanin (1-29). In contrast, galanin (1-29) preferentially activated GalR2 with increased Gq/11-mediated signaling determined in NFAT reporter gene assays. This may be the mechanism for the ability of GalR1 agonists to produce depressive actions.

In parallel, the Diaz-Cabiale group in Malaga, using an in vivo model of siRNA GalR2 knockdown or siRNA GalR1 knockdown rats, provided evidence that Gal (1-15) produced depression and anxiety-like behaviors by targeting GalR1-GalR2 heteroreceptor complexes in brain.

On the basis of these results, it seems likely that GalR1–GalR2–5-HT1A heterotrimeric complexes also may exist. Zaida Diaz-Cabiale and colleagues in 2000 also observed that Gal-(1-15) exerted a stronger decrease of 5-HT1A receptor recognition in the ventral limbic cortex than gal-(1-29).

It is of high interest that Millon and colleagues found in 2016 that Galanin (1-15) enhanced the antidepressant effects of a 5-HT1A receptor agonist. The results suggested that upon activation of all receptor protomers of putative GalR1-GalR2-5-HT1A heteroreceptor complexes linked to the raphe-hippocampal 5-HT neurons, antagonistic allosteric GalR1-5-HT1A receptor-receptor interactions no longer dominate but instead are replaced by an enhancing GalR2-5-HT1A interaction. This indicates the possible impact of agonist regulation on the dynamics of the receptor-receptor interactions in this putative heteroreceptor complex. This possibility seems to open up new strategies for the treatment of depression. In the Diaz-Cabiale group, Flores-Burgess and colleagues also demonstrated an enhancement of the antidepressant-like actions of fluoxetine by Gal-(1-15), which leads to a novel strategy for treatment of depression. The mechanisms involved can be an increase in the facilitatory GalR2-5-HT1A receptor-receptor interaction caused by the increased 5-HT1A protomer activation in the putative GalR1-GalR2-5-HT1A complex through increased extracellular levels of 5-HT. An increased expression of 5-HT1A receptors also can be involved.

It is of substantial interest that we, under the leadership of Professor Garriga in Barcelona, could find that the zinc binding receptor GPR39 interacts with 5-HT1A and GalR1 to form dynamic heteroreceptor complexes with signaling diversity. In view of the antidepressant effects of zinc, it is of interest that the GalR1-5-HT1A complex with inhibitory receptor-receptor interactions on 5-HTA signaling is the dominant complex at low zinc concentrations.

Galanin receptor-NPY receptor interactions were found in the brain by Diaz-Cabiale and Jose Narvaez and their colleagues. In a fine paper from 2016, Manuel Narvaez, Borroto-Escuela, and colleagues observed GalR2-NPYY1 receptor-receptor interactions in the dentate gyrus that are associated with antidepressant actions. These receptor-receptor interactions in the amygdala led to increased anxiolytic actions, as also found by Manuel Narvaez and colleagues. These are important findings because they suggest a new basis for integration of Galanin and NPY peptides at the molecular level in the brain.

In October 2017, our paper on 5-HT1A-5-HT2A isoreceptor complexes was published with Dr. Dasiel Borroto-Escuela as first author and corresponding author. Thus, two subtypes of 5-HT receptors from two major families of 5-HT receptors can form a heteroreceptor complex and produce integration and diversity of 5-HT receptor signaling, which likely is relevant for depression. These experiments were done thanks to the financial support of the Hjärnfonden, a neuroscience-focused foundation from Sweden.

FGFR1-5-HT1A Heteroreceptor Complexes and Their Receptor-Receptor Interactions: Relevance for Depression

Postdoc Dasiel Borroto-Escuela was leading this project and did so in an outstanding way. Postdoc Wilber Romero-Escuela in our laboratory also made fine contributions as did colleagues from other research teams abroad, especially the Belluardo-Mudo group at the University of Palermo, Italy. The project involved a large number of techniques, including, for example, BRET, co-immunoprecipitation, in situ proximity ligation assay, interface interacting peptides, and biochemical binding assay.

A hippocampal FGFR1-5-HT1A receptor complex was demonstrated (Borroto-Escuela et al. 2012), in which the 5-HT1A protomer enhanced the FGFR1 signaling. Upon combined activation of the two receptor protomers, synergistic increases in neuroplasticity were observed in primary hippocampal cultures. Upon acute and repeated intraventricular treatment with FGF2 and a 5-HT1A agonist, substantial antidepressant effects were observed (Borroto-Escuela et al. 2012). We believe this is a great paper. We had postulated the existence of these effects in 2007 (Fuxe et al. 2007). These results opened up novel strategies for the treatment of depression through the use of brain penetrant heterobivalent drugs built up of FGFR1 agonist and 5-HT1A agonist pharmacophors. The treatment has the potential to reverse the atrophy of the hippocampus found in depression.

In 2015, we were able to present evidence for the existence of FGFR1-5-HT1A heteroreceptor complexes in the midbrain raphe 5-HT system. The fact that 5-HT1A autoreceptors also can be part of heteroreceptor complexes with FGFR1 was of high significance. Thus, in this way, the 5-HT1A autoreceptor may become uncoupled from the GIRK channel and may no longer silence the dorsal raphe and medianus raphe neurons. Instead of reducing the firing of the ascending 5-HT neurons and contributing to depression, the 5-HT1AR in the raphe cell bodies and dendrites may enhance trophic actions of FGFR1 and increase plasticity and reduce the downstate of the ascending 5-HT neurons with a return of their mood-elevating functions. An enhancement of the FGFR1 protomer signaling of this heteroreceptor complex in the midbrain 5-HT nerve cells was in fact demonstrated after cotreatment with 5-HT1A agonist and FGF2.

Through these exciting findings, it became possible to write a research opinion article in Trends in Neuroscience on the integration of 5-HT and neurotrophic factor hypotheses of major depression (Borroto-Escuela et al. 2016). This was based on the demonstrated molecular integration in FGFR1-5-HT1A heteroreceptor complexes through allosteric receptor-receptor interactions.

In 2017, Dasiel and I were happy to be part of a paper by the Mudo-Belluardo group indicating the existence of mAChR-FGFR heterocomplexes enhancing neural plasticity in the hippocampus. Also, activation of such complexes can contribute to counteracting depression-induced atrophy of the hippocampus.

OxytocinR-Alpha2-Adrenoceptor Interactions

In 2000, Dr. Zaida Diaz-Cabiale worked with me as postdoc as part of a collaboration with Professor Jose Narvaez. We started a collaboration with Dr. Kerstin Uvnäs-Moberg and her group at the Karolinska Institutet. Uvnäs-Moberg was interested in understanding the actions of oxytocin on the brain, and so were we. We published a series of papers from 2000 to 2005 in Neuroendocrinology, Journal of Neuroendocrinology, and Brain Research. We found an antagonistic oxytocinR-alpha2-adrenoceptor interaction in the hypothalamus and amygdala involving a reduction in the affinity of the alpha2-adrenoceptor agonist binding sites using receptor autoradiography, which may be of relevance for the ability of oxytocin to acutely reduce the increase in food intake produced by the alpha2-adrenergic agonist clonidine. We also observed antagonistic oxytocin/alpha2-adrenoceptor interactions in the NTS, which is of possible relevance for acute effects on cardiovascular control in the NTS.

The most interesting finding was that subchronic oxytocin treatment could increase the density of the alpha2-adrenergic agonist binding sited in the hypothalamus and the amygdala. We proposed that this increase reflected an increase in alpha2-adrenergic signaling, which could contribute to the antistress actions of oxytocin, including modulation of neuroendocrine and cardiovascular functions. Similar results were observed in the ovarieectomized rat with demonstration also of increases in the alpha2-adrenergic agonist binding sites in the NTS. The mechanism for this increase is still unknown but could involve an increase in the expression of alpha2 adrenoceptors or an increase in the proportion of alpha2-adrenergic agonist binding sites in the high-affinity state because of an allosteric oxytocinR-alpha2-adrenergic receptor interaction in a heteroreceptor complex.

D2R-Oxytocin Receptor Heterocomplexes and Their Receptor-Receptor Interactions

Professor Insel and his group, through pioneering work, demonstrated the key role of oxytocin and its receptor in social and emotional behaviors. They also found that simultaneous activation of oxytocin receptor and D2Rs in the nucleus accumbens is crucial for pair bond formation. We therefore tested whether integration of oxytocin and DA signals took place in an oxytocinR-D2R heterorocomplex with facilitatory receptor-receptor interactions. Dr. Wilber Romero-Fernandez had a leading role in this project. The oxytocinR-D2R heterocomplexes were demonstrated in cell models with BRET² and in nucleus accumbens and dorsal striatum with proximity ligation assay (Romero-Fernandez et al. 2013). Using biochemical-binding techniques, oxytocin in nanomolar concentrations was found to produce an increased D2R recognition involving increased D2R density and an increase in the affinity of the high-affinity D2R agonist binding site. As a result, an increase in dopamine-induced Gi/o protein stimulation was observed. All effects of oxytocin were blocked by an oxytocin receptor antagonist (Romero-Fernandez et al. 2013).

Our hypothesis was that facilitatory allosteric D2-likeR-oxytocinR interactions in heteroreceptor complexes in nucleus accumbens may have a role in social and emotional behaviors in rodents and also in humans, including bonding and trust through regulation of the limbic circuits, especially to the prefrontal cortex. This complex may enhance social salience through its presence in a special component of the ventral striato-pallidal GABA pathway.

It is known that oxytocin may exert antipsychotic effects and be a natural antipsychotic. Dysfunction or disruption of the D2-likeR-oxytocinR heteroreceptor complexes may be involved in the social and emotional disturbances found in schizophrenia. By blocking the D2R protomers of these receptor heteromers, antipsychotics may fail to reduce the negative symptoms of schizophrenia, such as social withdrawal and emotionless behavior, by reducing the signaling of the D2R-oxytocinR heterocomplex.

We then established the enhancing effects of the receptor-receptor interactions on the CREB, MAPK, and phospholipase C (PLC) signaling pathways of the D2R-oxytocin receptor heterocomplexes, with Dr. Borroto-Escuela in charge. Oxytocin enhanced the inhibitory D2R signaling in the AC-PKA-pCREB pathway and D2R activation of the MAPK-pELK pathway. D2R enhanced oxytocinR signaling in the PLC-IP3-Calcineurin pathway. In the same paper, their relevance for the anxiolytic effects of dopamine and oxytocin interactions in the central amygdala was found with Professor Miguel Perez de la Mora in charge (de la Mora et al. 2016). D3R-oxytocin receptor heterocomplexes also may exist.

Professor Malinka recently wrote a beautiful article on ecstasy as a probe and drug for treatment of social behaviors. We propose that the D2R-OTXR heteroreceptor complexes can be an indirect or direct target for ecstasy, which can mediate its actions on social behavior. This will be exciting future work.

D2R-5-HT2AR Heteroreceptor Complexes as Targets for 5-HT2A Hallucinogens: Relevance for Schizophrenia

In 2010, we demonstrated the existence of D2R-5-HT2A heteroreceptor complexes BRET and proximity ligation assays in cellular models and in ventral and dorsal striatum (Borroto-Escuela et al. 2010a). Borroto-Escuela also found that reciprocal receptor-receptor interactions and standard 5-HT2A agonists reduced Gi/o-mediated D2R signaling. In view of the key role of D2Rs in schizophrenia, we proposed it could be a new target for antipsychotic drugs. It was therefore of high interest when we found that the hallucinogenic 5-HT2A agonists LSD and DOI were able to instead enhance D2R signaling and recognition. We proposed that this action could contribute to their hallucinogenic actions. Thus, the hallucinogenic 5-HT2A agonists had the ability to interact with the 5-HT2A binding pocket in a unique way, leading to a conformational change introducing an altered allosteric receptor-receptor interaction, enhancing D2R function.

It seems possible that in schizophrenia, the disease itself could alter the composition and stoichiometry of these heteromers and therefore the allosteric receptor-receptor interactions. Because of such changes, we now believe that the transmitter 5-HT can instead enhance the D2R protomer signaling as found after LSD, which can contribute to the schizophrenic symptoms. The prolonged and enhanced DA release from overactivity in the mesolimbic DA neurons in schizophrenia may contribute to a reorganization of the D2R heteroreceptor complexes or to altered receptor-receptor interactions, as found after amphetamine challenge.

These results are of high relevance for schizophrenia because the 5-HT2A antagonist–inverse agonist Pimavanserin recently was marketed under the trade name Nuplazid as a nondopaminergic atypical antipsychotic for the treatment of PD psychosis and schizophrenia. Professor Meltzer in Chicago made important contributions to its development.

D2R-D4R Isoreceptor Complexes and D4R-MOR Heteroreceptor Complexes

Borroto-Escuela and colleagues in 2011 found the D2R-D4R heteroreceptor complexes in cellular models using coimmunoprecipitation, proximity ligation assay, and BRET. D4.2R and D4.4 R were most effective in forming heteromers with the D2R. Facilitatory allosteric receptor-receptor interactions were found using assays for MAPK. It was the first demonstration that D4 receptors also can form heteroreceptor complexes.

Rivera and colleagues in 2016 obtained indications for D4R-MOR receptor-receptor interactions in the striosomes and in the zona reticulata of the substantia nigra. These functional D4R-MOR interactions appeared to prevent the MOR-induced activation of the nigrostriatal DA system and take place in D4R-MOR heteroreceptor complexes, as recently demonstrated using in situ proximity ligation assay (PLA) by Borroto-Escuela and Kirill Shumilov in my laboratory. D4R activation also prevented the rewarding effects of morphine but not the analgesic effects. The study suggests a novel strategy to avoid the addictive properties of morphine without interfering with the pain-reducing actions. The paper indicates the high impact of receptor-receptor interactions on modulation of the pathways of the brain.

1990s to Present: Understanding Communication and Integration in the Amygdala, Especially the Role of DA and Other Transmitters in Anxiety and Fear

This work represented a continuation of the work with Professor Miguel Perez de la Mora on the amygdala. He was leading the work. We were interested in understanding the neuromodulation of the intercalated paracapsular GABA islands and the main intercalated GABA islands, known to regulate the input and output regions of the amygdala, the basolateral amygdaloid (BLA) nucleus and the central amygdaloid nucleus (CeA), respectively. We found an overall intense D1R immunofluorescence in all of the nerve cells of the intercalated GABA islands (Fuxe et al. 2003). The density of their DA nerve terminal innervation differed from being high in the rostrolateral paracapsular islands and low to very low in the medio-caudal component of these D1R islands. Likewise, in the rostro-medial component of the main intercalated island, there was a high DA innervation, whereas in the caudal part, DA innervation was very low or absent.

Thus, DA communication was in these islands dominated from extrasynaptic (less than 10 um) and short-distance VT. D1R activation leads to anxiety and D1R blockade to anxiolytic actions as described by Perez de la Mora and colleagues in 2010 and 2012. The mechanism appears to be that D1R activation leads to a hyperpolarization of the GABA neurons through the opening of GIRK channels. This results in a reduction of the activity of the intercalated GABA neurons followed by disinhibition of the BLA and CeA glutamate neurons and production of fear and anxiety as demonstrated by Anne Marowsky in 2005.

Instead, dopamine D2Rs had their highest density within the latero-capsular division of CeA. Microinjections into the CeA of raclopride produced anxiogenic-like effects in the Shock-Probe Burying test. This part of CeA is innervated by DA terminals (Fuxe 1965a, 1965b). Activated D2Rs may inhibit, via a local interneuronal network, the anxiogenic outflow from the medial division. Thus, the DA projection pathways from the ventral tegmental area and the medial substantia nigra operate in the GABA intercalated cell masses mainly via D1R-mediated VT at various distances to enhance anxiety and fear. Instead, in the CeA they operate mainly via D2R-mediated extrasynaptic VT to produce anxiolytic effects. The balance between these two D1R- and D2R-modulated pathways may have a major role in the regulation of anxiety and fear.

We have studied the distribution of dopamine D1R and mu-opioid receptor immunoreactivities in the amygdala and the interstitial nucleus of the posterior limb of the anterior commissure. Again, there was no correlation between the distributions of D1R and MOR receptor systems with the TH and opioid peptide systems, respectively, indicating that VT was the major mode of communication. It was of substantial interest that strong dopamine and cyclic AMP-regulated phosphoprotein, 32 kDa (DARPP-32) immunofluorescence was observed in TH-D1R match regions but not in TH-D1R mismatch regions. Thus, the D1R signaling becomes altered in D1R-positive mismatch nerve cells, which are reached by lower concentrations of DA. It may mean that these D1R mismatch cells are forced to switch toward other signaling systems and may operate without inhibition of protein phosphatase-1 being part of D1R signaling.

In view of the partial codistribution of D1R and MOR receptor systems in the intercalated cell masses, the existence of receptor-receptor interactions in D1R-MOR heterocomplexes should be considered to exist in the intercalated islands and should be recognized as targets for VT.

In one of the papers in 2010 with Miguel Perez de la Mora dealing with GABAA rho receptor in the amygdala, Professor Ricardo Miledi was a coauthor. Miledi is known for his outstanding work on the key role of calcium ions in regulating neurotransmitter release. It was a pleasure to meet him in Mexico in this period, and he was happy to learn that GABAA rho receptors may have a place in the mechanisms modulating anxiety and fear.

I also had the pleasure to meet Professor Jorge Larriva-Sahd at a Cajal Club meeting in Queretaro, north of Mexico City. Larriva-Sahd is an outstanding neuroanatomist that mastered the rapid Golgi technique. I enjoyed discussing this with him, and our families had a good time together in Queretaro and its surroundings. We got to know this part of Mexico in a splendid way. I appreciated very much their hospitality and believed that Jorge liked my lectures on VT and receptor-receptor interactions at the Neurobiology Center in Queretaro.

We started to collaborate and studied the anterior and rostral paracapsular intercalated islands in horizontal sections along with Miguel Perez de la Mora using rapid Golgi. Our findings indicated that the intercalated islands may gate the information flow of neurons from the contralateral amygdala and other contralateral parts of the basal forebrain using the anterior commissure for their axons. In this way, the anxiogenic outputs of both amygdalae could be synchronized. In particular, the anterior intercalated islands seemed to participate in decoding neuronal activity produced in the ipsi- and contra-lateral amygdala to achieve a balanced and appropriate output from the two amygdala in the various functional states of the brain. The paper was published in Neuroscience in 2012.

In 2014, we published together another fine paper, this time on the tubero-infundibular DA neurons and their relationship to D1R and D2R receptors using not only immunohistochemistry but also Golgi techniques. With the Golgi technique, Larriva-Sahd obtained further evidence that the arcuate nerve cells projected into the median eminence. Their axons formed horizontal axons in the internal layer producing a number of collaterals forming single or multiple strands reaching the external layer. The immunohistochemistry gave evidence for the first time that D1R receptors or D2R receptors exist in the LPZ of the median eminence and may mediate, through dopamine VT in the um range, inter alia inhibition of LHRH release from LHRH-immunoreactive nerve terminals in this region. Our concept on the existence of important integrative mechanisms in the external layer of the median eminence was finally receiving support decades after its introduction. The concept assumed the existence of VT in the um range because no synapses exist in the external layer.

A large number of TH immunoreactive nerve cell bodies in the dorsomedial region of the arcuate region, known to form DA, showed punctate dopamine D1R IR. Thus, dopamine D1Rs may directly modulate the activity or dopamine synthesis in many tubero-infundibular dopamine neurons at the soma-dendrite level. D2R IR was found only in a number of TH-positive neurons in the ventral periventricular cell group of the tubero-infundibular DA neurons. This demonstrated an unknown heterogeneity of this DA neuronal system.

2010 to Present: The Triplet Puzzle Theory: Homologies of Amino Acid Protriplets in the Interface of Receptor Heteromers

I was happy to begin a collaboration with Dr. Alexander Tarakanov, of the Russian Academy of Sciences, St. Petersburg Institute for Informatics and Automation, Saint Petersburg. We both believed that homologies were involved in forming heterodimers and Dr. Tarakanov was leading the work, being an expert in mathematics and bioinformatics. Through a mathematical approach, it was deduced, based on 48 pairs of receptors that form or do not form heteromers, that sets of triplet amino acid homologies may participate in the guiding process or in the receptor interface. This was called the triplet puzzle theory. They formed a kind of code that made different receptors come together and form heterodimers (Tarakanov and Fuxe 2010). We proposed a “guide-and clasp” manner for receptor–receptor interactions in which triplet homologies represented potential “adhesive guides.”

Dr. Tarakanov found the same year sets of protriplet amino acid homologies in the D2R-D4R, GalR1-5-HT1A, and D2R-5-HT2AR heterodimers, which Borroto-Escuela and colleagues recently identified as well in the A2AR-D2R heterodimer. In 2011, the triplet puzzle of homologies also was found in other types of protein-protein interactions.

In 2012, Tarakanov and colleagues obtained indications that the origin of the triplet amino acid homologies found in receptor heterodimers may be from immunoglobulin triplets and Toll-like receptor triplets. It is also of substantial interest that integrin triplets of marine sponges are used in the interface of MHC class I (MHCI) and CD8αβ, representing two immune molecules, and in the interface of neural receptor heteromers. Thus, some triplet amino acid homologies may originate from cell adhesion molecules of the oldest multicellular animals, where they may be used for recognition.

In 2015, we found that the opioid and chemokine receptor subtypes have several sets of amino acid homologies in common, which can be the mechanism for the massive formation of heteromers between chemokine and opioid receptors. This integrative mechanism should make possible a major modulation of pain and neuroinflammation. Thus far, the existence of triplet amino acid homologies in positions relevant to the interface in a receptor pair have turned out to always reflect a heteromer.

The interactions with Dr. Tarakanov had a significant impact on our understanding of how receptor heteromers are formed. To demonstrate the impact of the triplet puzzle theory, I will show its role in understanding the mild neuroinflammation hypothesis of schizophrenia developed by Karl Bechter: We indicated that putative NMDAR-C-C chemokine receptor type 2 (CCR2), NMDAR-C-X-C chemokine receptor type 4 (CXCR4), and NMDAR-interleukin 1 receptor type II (IL1R2) heteromers may develop in the neuronal-glial networks with mild neuroinflammation, in view of the Tarakanov demonstration of triplet Gly-Leu-Leu (GLL), Val-Ser-Thr (VST), and Ser-Val-Ser (SVS) amino acid homologies between these receptor protomers. Tarakanov also found indications for the presence of putative D2R-CCR2, D2R-CXCR4, and D2R-IL1R2 heteromers in mild neuroinflammation because these heteromers also exhibited sets of Leu-Tyr-Ser (LYS), Leu-Pro-Phe (LPF), and Ser-Leu-Ala (SLA) triplet homologies.

In view of the major role of the NMDA and D2 receptors in schizophrenia, these NMDAR and D2R heteroreceptor complexes may cause schizophrenia symptoms in mild neuroinflammation through a putative reduction of NMDA receptor protomer function and an increase in D2R protomer function.

We propose that CCR2, CXCR4, and IL1R2, as well as their ligands, may reach the neuronal cells by being present in exosomes released from astroglia and microglia as part of the inflammatory process and then internalized into neuronal cells. From recycling endosomes, they may enter the plasma membrane and interact with NMDA or D2 receptors and alter their function. This may lead to symptoms of schizophrenia because of the disturbances developed in the neuronal network.

2007 to Present: Using an Electrophysiological Approach on Xenopus Oocytes to Understand Voltage Sensitivity and Pharmacology of GPCRs and the Actions of Typical and Atypical Antipsychotics

This work became possible through a collaboration with a neurophysiological group at our department led by Professor Peter Århem and Dr. Johanna Nilsson who were in charge of the project. Kristoffer Sahlholm, an excellent graduate student, played an important part in the work. It has been a rewarding collaboration.

The first two papers in 2007–2008 dealt with how H3 receptors couple to GIRK channels and on H4 pharmacology using GIRK coupling in Xenopus oocytes. Then we moved into voltage sensitivity of human D2S receptors. We found this to be agonist-specific. Upon depolarization, the potency of DA was reduced. Instead, the potencies of trace amines beta-phenethylamine and p- and m-tyramine receptors were not influenced by depolarization of the plasma membrane. The differential sensitivity to changes in voltage appeared to depend on properties of the receptor-agonist interactions, and were not linked to changes in the G protein or the GIRK channel. Such a difference in voltage sensitivity among agonists to the same receptor has not previously been observed.

In a subsequent paper in Synapse, we presented evidence that the human D2R itself is voltage sensitive using the D2R agonists DA and quinpirole using the same techniques. Such a property of the D2R may play a role in its modulation of synaptic potency and strength and of synaptic plasticity. It is of interest that concentration-response relationships at −80 mV and at 0 mV demonstrated significant rightward shifts for the human D4R but not for the human D3R upon depolarization. Thus, differences exist for closely related receptors.

In 2011, it became possible to demonstrate that the reduced potency of dopamine found at D2S receptors to open the GIRK channels upon depolarization correlated with a reduced binding of the dopamine radioligand. It was also found that the voltage sensitivity was interfered with by a mutation of conserved serines in TM-V, especially S193, or the conserved aspartate residue in TM III (D114). The hydroxyl groups and the amine moiety of dopamine are contacted by these serine and aspartate residues, respectively. Differences were observed in DA receptor agonists used in the treatment of PD. This work on voltage sensitivity of GPCRs is of high relevance for our hypothesis on the molecular basis of learning and memory (see the next section). Thus, changes in the voltage sensitivity and associated changes in resistance can alter receptor protomer recognition and signaling, and thus can alter the allosteric receptor-receptor interactions in the heteroreceptor complexes building up the presynaptic and postsynaptic membranes. In the postsynaptic membrane, such changes therefore can contribute to learning and memories formed upon consolidation of the altered molecular circuit made up of different types of heteroreceptor complexes in the postsynaptic membrane (Fuxe et al. 2014; Borroto-Escuela et al. 2015).

In 2012, we found that the hH3 (445) receptor isoform had the highest sensitivity to voltage versus the hH3(365) isoform. There was also a difference in response deactivation kinetics between the two hH3 isoforms with the hH3 (365) isoform being slower than the hH3 (445) receptor. Thus, it can be speculated that higher sensitivity to voltage may be associated with more rapid deactivation kinetics.

We were aware that extrapyramidal side effects (EPS) were highly frequent with typical antipsychotic drugs, like chlorpromazine and haloperidol. Instead, they were less frequent with atypical antipsychotic drugs like clozapine. Nevertheless, both typical and atypical antipschotic drugs were mainly blocking D2R to produce their antipsychotic actions. Therefore, the fast-off hypothesis was introduced, which proposed that atypical but not typical antipsychotics rapidly dissociate from the D2Rs. Through this mechanism, an improved dynamics of D2R signaling was believed to be maintained. The reversibility of D2R blockade was not sufficiently examined in functional assays, however. We therefore tested a large number of typical and atypical D2R antagonists on D2R agonist-induced activation of GIRK currents in Xenopus oocytes, which have a high temporal resolution.

The major result of these tests was the demonstration of only small differences between the typical antipsychotic drug chlorpromazine and the atypical antipsychotic drugs amisulpride, clozapine, and quetiapine. Thus, the rate of reversibility of D2R blockade is not the key difference between atypical and typical antipsychotic drugs. Other explanations should be considered, such as the blockade of a distinct population of D2Rs as indicated in the case with remoxipride, which could represent a certain type of heteroreceptor complex with a distinct pharmacology.

In a subsequent paper, Sahlholm and colleagues analyzed in 2016 the maintained D2R antagonism produced by certain lipophilic compounds, such as the typical antipsychotic drug haloperidol. A rather rapid recovery of D2R responsivity from blockade by the antipsychotic drug haloperidol was found. The difference compared with previous work using radioligands may involve increased lipophilic sequestration and rebinding to the D2R. In our study, we used competition with DA and continuity of flow.

Thus, rapid rates of response recovery observed with both haloperidol and chlorpromazine indicate that these drugs remain in the brain tissue for other reasons than slow dissociation rates from the D2R. It may to a large extent be determined by their lipophilic properties.

Instead of the fast-off hypothesis, we should consider that many atypical antipsychotic drugs can target the 5-HT2A receptors with high affinity based on Meltzer’s work. We propose that D2R-5-HT2A heteroreceptor complexes can be a novel important target for atypical antipsychotic drugs blocking both D2 and 5-HT2A receptor protomers, leading to synergistic therapeutic effects and allowing low doses to be used. Other D2R heteroreceptor complexes can be relevant targets for atypical antipsychotics. They represent a promised land for drug development in schizophrenia.

2004 to Present: Understanding the Architecture of Central Monoamine Neurons in Wild Rodent Species in South Africa, the Nile Crocodile, the Giraffe, the African Elephant, and the Bottlenose Dolphin

I always wanted to know the structural features of the central monoamine neurons in other species than the laboratory rat. This became possible by having a nice and fruitful collaboration with Professor Paul Manger and his group at the University of the Witwatersrand, Johannesburg, South Africa. Dr. Manger was the leader of the project, and I was happy to come down to his laboratory for a short period now and then. I analyzed the sections with excitement. They were stained using immunohistochemistry.

In the bottlenose dolphin, there was an expansion of the nigral medial and VTA lateral subdivisions forming a large DA cell group visualized with TH immunohistochemistry in the posterior part of the midbrain. Few DA nerve cells were found in the other parts of the substantia nigra. This made the parcellation of the DA cell groups in this area quite different from the rodent species. The coming together of the nigral-VTA DA cell groups may result in rather intense interaction between the nigral DA system involved with motor functions and the mesolimbic DA neurons representing a reward system. It may be speculated that the activity of the DA motor neurons can directly enhance the activity of the mesolimbic DA neurons in the ventral midbrain leading to the “happy” trunk movements of the dolphin.

In the African elephant, the nigral DA neurons instead appeared to form DA cell-rich islands, which are separated from one another by fiber bundles. It is an architecture found only in the elephant. Each DA cell island can form topologically arranged projections to the striatum, where the mosaic of dopamine nerve terminals innervating the striatum can make various trunk movements possible. There is also a medial division of the LC, built up of NA nerve cells, which previously was not observed in other species. It may be related to the demand for wakefulness to maintain a high food intake.

In the sub-adult male giraffe, the most interesting findings were an enlarged ventral component of the nigral DA cell group and an expansion of the NA cell group in the subcoeruleus and its diffuse component in the reticular formation of the rostral pons and caudal midbrain. The overall organization of the monoamine cell groups, however, was similar to that found in other Artiodactyls in spite of changes in phenotype, brain size, and so on, which is in line with the review of Paul Manger published in 2005.

We also studied the nuclear organization and morphology of serotonergic neurons in the brain of the Nile crocodile. It was exciting to see the marked changes found versus mammals, especially in the 5-HT cell groups in the rostral brainstem. Here I saw the medial and lateral parts of the 5-HT immunoreactive superior raphe nucleus and a widely dispersed group of 5-HT immunoreactive neurons in the reticular tegmentum, known as the superior reticular nucleus.

The parcellation of all the DA, NA, and 5-HT cell groups in various wild-type species of rodents had a similar architecture to the central monoamine neurons of the domestic male rats I had found and characterized in my thesis in 1965. These findings were important because they showed that the fundamental architecture remained the same in the rodent order in terms of parcellation of the monoamine cell groups. Major species differences may instead exist in the monoamine nerve terminal networks and their receptor systems.

Paul and I became friends, and he showed me fine hospitality. Paul took me inter alia to the Pilanesberg National Park around 200 km away from Johannesburg. Paul drove through it in his jeep with me at his side. We found abundant wildlife in this nature reserve giving spectacular views of the South African landscape. Among the Big Five, we spotted the buffalos, elephants, and rhinos. We failed to see the lions, to our great disappointment. I am fond of their golden eyes, beautiful and full of power as they inspect their territory. Paul Manger and I are still interacting, and I hope this adventure will continue.

1990s to Present: The Concept of Allosteric Receptor-Receptor Interactions in Homo- and Heteroreceptor Complexes Give a New Dimension to Molecular Neuroscience and Understanding of the Molecular Basis of Learning and Memory and Brain Disease

The concept of allosteric receptor-receptor interactions in GPCR homo- and heteroreceptor complexes of the CNS gave a new biological principle to understanding brain integration and neuropsychopharmacology. Allosteric receptor-receptor interactions made possible through receptor oligomerization lead to novel receptor dynamics during which the receptor protomers change their recognition, pharmacology, signaling, and trafficking, and novel allosteric binding sites can develop. GPCR heteroreceptor complexes can also involve ion channel receptors, receptor tyrosine kinases (RTKs), sets of G protein-interacting proteins, ion channels, and transmitter transporters.

There is a need to improve our understanding of the molecular organization of the receptor oligomers, their allosteric communication, and the features of the receptor interface. It appears clear that synaptic transmission and VT (extracellular fluid and CSF) in the brain can become integrated in heteroreceptor complexes in the synaptic and perisynaptic membranes built up of ion channel receptors, GPCRs, and RTKs (Fuxe et al. 2008; Borroto-Escuela et al. 2012; Fuxe et al. 2014; Borroto-Escuela et al. 2016). This enables modulation of synaptic strength and synaptic plasticity in a dynamic way, and receptor plasticity is accomplished. Integration of the molecular receptor circuits in the postsynaptic and perisynaptic membranes, respectively, can take place through integration of their intracellular molecular signaling pathways in the dendritic spines.

It is now clear from the demonstration of the GPCR heterodimer network (GPCR-HetNet) that the allosteric receptor-receptor interactions dramatically increase GPCR protomer diversity and biased recognition and signaling, leading to enhanced specificity in signaling (Borroto-Escuela et al. 2014).

On the basis of this concept, we proposed that the molecular basis of learning and memory was based on the reorganization of the homo- and heteroreceptor complexes in the postsynaptic membrane of synapses, and also was associated with changes in the presynaptic receptor complexes, to facilitate the pattern of multiple transmitter release to be learned (Fuxe et al. 2014; Borroto-Escuela et al. 2015). As discussed earlier, changes in the voltage sensitivity of the receptors and associated changes in electrical resistance also can contribute to the learning process through modulation of the allosteric receptor-receptor interactions. In addition, VT signals like transmitters and growth factors can diffuse into the synapse from surrounding terminals and dendrites and glial cells and target, for example, GPCRs and RTKs of multiple heteroreceptor complexes in the postsynaptic membrane. In this way, the new molecular circuit formed also contains information about the context in which the patterns of synaptic transmitter release was learned.

Long-term memory may be created by the transformation of parts of the heteroreceptor complexes into unique transcription factors, which can lead to the formation of specific adapter proteins that can consolidate the homo- and heteroreceptor complexes into long-lived complexes with conserved allosteric receptor-receptor interactions. Thus, the homo-heteroreceptor complexes are regarded as highly dynamic assemblies formed or disrupted by integrated synaptic and VT signals. These events are regarded as necessary for learning, and they can become transformed into a consolidated rigid state with conserved allosteric communication representing molecular engrams and resulting in a major long-term modulation of the neuronal networks. This molecular plasticity change, whether transient or long term, can then alter the patterns of outflow in the brain circuits and induce transient and long-term changes in behaviors and cognitive functions (Fuxe et al. 2014; Borroto-Escuela et al. 2015). This appears to be a key molecular mechanism for the modulation of the neuronal networks.

We have a concept for how lifelong memories can be formed. The impact of VT signals, including monoamines from terminals of emotional circuits, may make it possible. They are postulated to act especially on distinct postsynaptic receptor protomers, which otherwise do not become activated. Extracellular-mediated VT also may take place. This can involve internalization of extracellular vesicles containing, as cargo, receptors and transcription factors with a significant ability to contribute to transcriptional activation through, for example, homeoproteins. This can cause, via epigenetic mechanisms, production of adapter–scaffolding proteins with a unique efficacy to consolidate the panorama of various types of heteroreceptor complexes that form the molecular engram in the postsynaptic membrane (Borroto-Escuela et al. 2015).

Dysfunction or disruption of the heteroreceptor complexes can lead to brain disease. Understanding the D2R heteroreceptor complexes and their dysfunction in schizophrenia can lead to new strategies for its treatment and for avoiding side-effects of antipsychotics known to mainly act as D2R antagonists. This includes a way to optimize combined treatment or the single use of heterobivalent drugs targeting distinct D2R heteroreceptor complexes in schizophrenia. This is inspired by current findings on the existence of various types of D2R heteroreceptor complexes in nucleus accumbens core and shell.

It was proposed that novel anti-Parkinson drugs for the future may be heterobivalent drugs, such as a build up of an A2AR antagonist pharmacophor linked to a D2R agonist pharmacophor specifically targeting the A2AR-D2R heterodimer. Other exciting novel targets for anti-Parkinson drugs are A2AR-D2R-mGluR5 heteroreceptor complexes, where A2AR and mGluR5 synergize to put a brake on D2R Gi/o-mediated signaling. Emerging new concepts in PD are that dysfunction of the allosteric receptor-receptor interactions and disbalance of multiple heteroreceptor complexes play a major role. They can be codistributed in the same neuron and synapses of the direct and indirect pathways of the basal ganglia and can contribute to disease progression and levodopa-induced dyskinesias.

Furthermore, the D1R and D2R heteroreceptor complexes in the reward and antireward GABA pathways from the nuc accumbens have become exciting new targets for the treatment of substance use disorder. The changes found in these receptor complexes in cocaine self-administration open up a new understanding of what goes wrong in cocaine use versus cocaine addiction.

Looking into the Past

It all started with our observations of the existence of central DA, NA, and 5-HT brainstem neurons. Their architecture, which often involves formation of global varicose nerve terminal networks in the brain and the spinal cord, made us believe that mainly an extrasynaptic monoamine communication was involved in modulating the panorama of glutamate and GABA neurons building up the CNS. This finding led to the introduction of the concept of the existence of a major mode of communication in the extracellular fluid and in the CSF. We called this VT, which operates through diffusion and flow of biological signals reaching high-affinity receptors located on nerve and glial cells.

Understanding the function of the central monoamine neurons led us into neuroendocrinology, cardiovascular research, neurology, psychiatry, and neuropsychopharmacology.

Sitting at the fluorescence microscope at a young age, I often wondered how the monoamine neurons and their varicosities releasing DA, NA, or 5-HT could become integrated with the classical neurons and their synapses releasing glutamate or GABA. It seemed to me that the plasma membrane had been neglected as a site of integration of signaling. The dogma was that the synapse was fully isolated from the extracellular fluid and other synapses, with integration of transmitter signals taking place only in the cytoplasmatic signaling pathways. This did not make any sense. Why should integration of transmitter signals exclusively take place in the cytoplasmatic pathways? One way to find out would be to study the possible existence of receptor-receptor interactions in the plasma membrane, which we demonstrated at the recognition level.

We then introduced the concept that the receptor-receptor interactions took place in receptor heteromers. As a follow-up, we proposed that the postsynaptic membrane was built up of multiple homo- and heteroreceptor complexes that represented the molecular basis for learning and memory. Upon consolidation by unique adapter proteins formed in the memory process, molecular engrams were formed from the molecular circuit of homo- and heteroreceptor complexes in the postsynaptic membranes, giving a specific barcode to that synapse. In this integrative process leading to learning and memory, the VT and synaptic signals become integrated in synaptic and perisynaptic heteroreceptor complexes.

This work was accomplished by my own group and through national and international collaborations with outstanding scientists and their groups. Each of them gave their own unique contribution. It is no fun to do research without sharing it with other devoted scientists. The discussions are important to lead the way for new experiments and to be happy together for good results and to be depressed together when experiments go wrong. In the past 10 years, my senior postdoc and scientific laboratory manager Dasiel Borroto-Escuela has made outstanding contributions to the work, and I believe he has a great future in neuroscience.

Looking into the Future

An important area will be to build models of GPCR heterodimers of high relevance like the A2AR-D2R heterodimer. GPCRs can crystallize as homodimers and have a large buried surface area. We have started a collaboration with Dr. Jens Carlsson at the University of Uppsala on the A2AR-D2R heterodimer. He will have a leading role in developing this model together with us. The dimer model will be generated by protein-protein docking together with competition experiments with transmembrane peptides using BRET to determine the transmembrane domains involved in the dimer interface. Mutations will be performed at the residues believed to be critical based on the docking analysis. A representative molecular dynamic simulation snapshot of the mutated residues will be performed. This work will be critical to reach into the atomic level and establish the dimer interface of the heterodimers we regard as critical targets for the treatment of PD, schizophrenia, depression, and drug addiction. We hope that by mutating critical residues we can identify, for example, the places of transfer for the inhibitory allosteric waves from the A2AR to the D2R binding pocket, reducing the affinity of the high-affinity D2R state.

It will be of highest importance to integrate the new data from the heterodimer model with the results coming out from the triplet puzzle theory introduced by Tarakanov and Fuxe in 2010. It will be exciting to see how mutations of the protriplets will alter the heterodimer model as studied with BRET and protein-protein docking.

By knowing in greater detail the receptor interface from models of receptor heterodimers, we will be able to develop new specific receptor interface interacting peptides targeting and disrupting specific heteroreceptor complexes. We have already started this work with regard to the A2AR-D2R heteroreceptor complex through a collaboration with Professor Malgorzata Filip and her group at the Polish Academy of Sciences in Krakow. We hope to establish the specific role of the A2AR-D2R heteroreceptor complexes in key areas for cocaine addiction by microinjections of A2AR-D2R interface interacting peptides in cocaine self-administration and in cocaine seeking. This principal approach will be used for other heterodimers of relevance for cocaine addiction, after a model of these receptor heterodimers have been developed. Models of PD, schizophrenia, and depression will be employed using this approach. It will be exciting to see how different types of interface interacting peptides targeting distinct heteroreceptor complexes can modulate the learning process and the long-term memories formed in different brain regions.

We also have a plan to develop specific brain penetrant A2AR-D2R heterobivalent compounds that specifically target the A2AR-D2R heteroreceptor complexes. These will be built up of A2AR agonist and D2R antagonist pharmacophors. This work is just starting in collaboration with Professor Katarzyna Kieć-Kononowicz and Professor Malgorzata Filip in Krakow. It will be of high interest to see whether novel treatment strategies for cocaine abuse and addiction can be developed based on our work.

There is a need to improve our understanding of extracellular vesicle-mediated VT in the brain. The exosomes (40–100 nm) are of special interest because they contain proteins, including receptors and homeoproteins, lipids, mRNA, miRNA, and mtDNA, originating from endosomes based on the fundamental work of Simons and Raposo (2009).

Exosomes are postulated to diffuse and flow in the extracellular space of the brain followed by internalization (Borroto-Escuela et al. 2015).

In light of our recent paper focused on putative IL1R2, CCR2, and CXCR4 heteroreceptor complexes with NMDAR and D2R based on the triplet puzzle theory (Tarakanov and Fuxe 2010), it will be important to determine whether exosomes, containing receptors or transcription factors, in fact exist, for example, in the hippocampus operating via VT in models of neuroinflammation. Are the exosomes internalized into neuronal cells after their release from glial cells? Can IL1R2, CCR2, and CXCR4 form heteroreceptor complexes with NMDA receptors as postulated based on the triplet puzzle theory?

The future looks highly interesting moving further into molecular integration and communication in health and disease and understanding the molecular basis of learning and memory. It will be exciting to see how our concepts will survive and be modified by new experimental evidence. The mystery of how the brain works remains for future generations to solve, but at least we are less ignorant than we used to be.

References

Agnati LF, Fuxe K (1985) Quantitative neuroanatomy in transmitter research. Stockholm: Palgrave Macmillan.

Agnati LF, Fuxe K, Zini I, Lenzi P, Hokfelt T (1980) Aspects on receptor regulation and isoreceptor identification. Med Biol 58:182–187.

Agnati LF, Fuxe K, Zoli M, Ozini I, Toffano G, Ferraguti F (1986) A correlation analysis of the regional distribution of central enkephalin and beta-endorphin immunoreactive terminals and of opiate receptors in adult and old male rats. Evidence for the existence of two main types of communication in the central nervous system: the volume transmission and the wiring transmission. Acta Physiol Scand 128:201–207.

Aguirre JA, Fuxe K, Hedlund P, Narvaez JA, Cintra A, Rosen L, Agnati LF (1991) Neuropeptide-Y angiotensin-ii interactions in central cardiovascular regulation of the rat. Brain Res 566:61–69.

Ajuriaguerra J, Gauthier G (1970) Monoamines noyaux gris centraux et syndromes de parkinson. Geneva: Georg et Cie.

Anden NE, Carlsson A, Dahlstroem A, Fuxe K, Hillarp NA, Larsson K (1964) Demonstration and mapping out of nigro-neostriatal dopamine neurons. Life Sci 3:523–530.

Andersson K, Fuxe K, Eneroth P, Nyberg F, Roos P (1981) Rat prolactin and hypothalamic catecholamine nerve-terminal systems: evidence for rapid and discrete increases in dopamine and noradrenaline turnover in the hypophysectomized male-rat. Eur J Pharmacol 76:261–265.

Andersson K, Fuxe K, Agnati LF, Eneroth P, Camurri M (1984) Luteinizing hormone-releasing hormone increases dopamine turnover in the lateral palisade zone of the median eminence and reduces noradrenaline turnover in the nuc. preopticus medialis of the hypophysectomized male rat. Neurosci Lett 45:253–258.

Bjelke B, Englund R, Nicholson C, Rice ME, Lindberg J, Zoli M, Agnati LF, Fuxe K (1995) Long distance pathways of diffusion for dextran along fibre bundles in brain. Relevance for volume transmission. Neuroreport 6:1005–1009.

Borroto-Escuela DO, Tarakanov AO, Fuxe K (2016) FGFR1-5-HT1A heteroreceptor complexes: Implications for understanding and treating major depression. Trends Neurosci 39:5–15.

Borroto-Escuela DO, Romero-Fernandez W, Tarakanov AO, Ciruela F, Agnati LF, Fuxe K (2011) On the existence of a possible A2A-D2-beta-Arrestin2 complex: A2A agonist modulation of D2 agonist-induced beta-arrestin2 recruitment. J Mol Biol 406:687–699.

Borroto-Escuela DO, Agnati LF, Bechter K, Jansson A, Tarakanov AO, Fuxe K (2015) The role of transmitter diffusion and flow versus extracellular vesicles in volume transmission in the brain neural-glial networks. Philos T R Soc B 370: 20140183.

Borroto-Escuela DO, Romero-Fernandez W, Tarakanov AO, Marcellino D, Ciruela F, Agnati LF, Fuxe K (2010a) Dopamine D2 and 5-hydroxytryptamine 5-HT((2)A) receptors assemble into functionally interacting heteromers. Biochem Bioph Res Comm 401:605–610.

Borroto-Escuela DO, Marcellino D, Narvaez M, Flajolet M, Heintz N, Agnati L, Ciruela F, Fuxe K (2010b) A serine point mutation in the adenosine A(2A)R C-terminal tail reduces receptor heteromerization and allosteric modulation of the dopamine D2R. Biochem Bioph Res Comm 394:222–227.

Borroto-Escuela DO, Narvaez M, Marcellino D, Parrado C, Narvaez JA, Tarakanov AO, Agnati LF, Diaz-Cabiale Z, Fuxe K (2010c) Galanin receptor-1 modulates 5-hydroxtryptamine-1A signaling via heterodimerization. Biochem Bioph Res Comm 393:767–772.

Borroto-Escuela DO, Narvaez M, Wydra K, Pintsuk J, Pinton L, Jimenez-Beristain A, Di Palma M, Jastrzebska J, Filip M, Fuxe K (2017) Cocaine self-administration specifically increases A2AR-D2R and D2R-sigma1R heteroreceptor complexes in the rat nucleus accumbens shell. Relevance for cocaine use disorder. Pharmacol Biochem Behavior 155:24–31.

Borroto-Escuela DO, Romero-Fernandez W, Mudo G, Perez-Alea M, Ciruela F, Tarakanov AO, Narvaez M, Di Liberto V, Agnati LF, Belluardo N, Fuxe K (2012) Fibroblast growth factor receptor 1-5-hydroxytryptamine 1A heteroreceptor complexes and their enhancement of hippocampal plasticity. Biol Psychiatry 71:84–91.

Borroto-Escuela DO, Ravani A, Tarakanov AO, Brito I, Narvaez M, Romero-Fernandez W, Corrales F, Agnati LF, Tanganelli S, Ferraro L, Fuxe K (2013) Dopamine D2 receptor signaling dynamics of dopamine D2-neurotensin 1 receptor heteromers. Biochem Bioph Res Comm 435:140–146.

Borroto-Escuela DO, Brito I, Romero-Fernandez W, Di Palma M, Oflijan J, Skieterska K, Duchou J, Van Craenenbroeck K, Suarez-Boomgaard D, Rivera A, Guidolin D, Agnati LF, Fuxe K (2014) The G protein-coupled receptor heterodimer network (GPCR-HetNet) and its hub components. Intl J Mol Sci 15:8570–8590.

Carlsson A, Fuxe K, Ungerstedt U (1968) The effect of imipramine on central 5-hydroxytryptamine neurons. J Pharm Pharmacol 20:150–151.

Corrodi H, Fuxe K, Hokfelt T, Lidbrink P, Ungerstedt U (1973) Effect of ergot drugs on central catecholamine neurons: Evidence for a stimulation of central dopamine neurons. J Pharm Pharmacol 25:409–412.

Dahlstrom A, Fuxe K (1964) Evidence for existence of monoamine-containing neurons in central nervous system, I. Demonstration of monoamines in cell bodies of brain stem neurons. Acta Physiol Scand 62:1–55.

de la Mora MP, Perez-Carrera D, Crespo-Ramirez M, Tarakanov A, Fuxe K, Borroto-Escuela DO (2016) Signaling in dopamine D2 receptor: Oxytocin receptor heterocomplexes and its relevance for the anxiolytic effects of dopamine and oxytocin interactions in the amygdala of the rat. Biochimica et biophysica acta.

Ferraro L, O’Connor WT, Beggiato S, Tomasini MC, Fuxe K, Tanganelli S, Antonelli T (2012) Striatal NTS1, dopamine D2 and NMDA receptor regulation of pallidal GABA and glutamate release--A dual-probe microdialysis study in the intranigral 6-hydroxydopamine unilaterally lesioned rat. Eur J Neurosci 35:207–220.

Ferre S, von Euler G, Johansson B, Fredholm BB, Fuxe K (1991) Stimulation of high-affinity adenosine A2 receptors decreases the affinity of dopamine D2 receptors in rat striatal membranes. Proc Nat Acad Sci USA 88:7238–7241.

Franco R, Ferre S, Agnati L, Torvinen M, Gines S, Hillion J, Casado V, Lledo P, Zoli M, Lluis C, Fuxe K (2000) Evidence for adenosine/dopamine receptor interactions: Indications for heteromerization. Neuropsychopharmacology 23:S50–59.

Fuxe K (1965a) Evidence for the existence of monoamine neurons in the central nervous system. 3. The monoamine nerve terminal. Zeitschrift fur Zellforschung und mikroskopische Anatomie 65:573–596.

Fuxe K (1965b) Evidence for the existence of monoamine neurons in the central nervous system, IV. Distribution of monoamine nerve terminals in the central nervous system. Acta Physiol Scand Suppl 247:237.

Fuxe K (1979) Dopamine receptor agonists in brain research and as therapeutic agents. Trends Neurosci 2:1–4.

Fuxe K, Agnati LF (1991) Volume transmission in the brain: Novel mechanisms for neural transmission. New York: Raven Press.

Fuxe K, Agnati LF, Benfenati F, Celani M, Zini I, Zoli M, Mutt V (1983) Evidence for the existence of receptor: Receptor interactions in the central nervous system. Studies on the regulation of monoamine receptors by neuropeptides. Journal of neural transmission Supplementum 18:165–179.

Fuxe K, Agnati LF, Benfenati F, Cimmino M, Algeri S, Hokfelt T, Mutt V (1981) Modulation by cholecystokinins of 3H-spiroperidol binding in rat striatum: evidence for increased affinity and reduction in the number of binding sites. Acta Physiol Scand 113:567–569.

Fuxe K, Agnati LF, Bolme P, Hokfelt T, Lidbrink P, Ljungdahl A, Perez de la Mora M, Ogren S (1975) The possible involvement of GABA mechanisms in the action of benzodiazepines on central catecholamine neurons. Adv Biochem Psychopharmacol 14:45–61.

Fuxe K, Borroto-Escuela DO, Ciruela F, Guidolin D, Agnati L (2014) Receptor–receptor interactions in heteroreceptor complexes: A new principle in biology. Focus on their role in learning and memory. Neurosci Discovery 2.

Fuxe K, Borroto-Escuela DO, Romero-Fernandez W, Diaz-Cabiale Z, Rivera A, Ferraro L, Tanganelli S, Tarakanov AO, Garriga P, Narvaez JA, Ciruela F, Guescini M, Agnati LF (2012) Extrasynaptic neurotransmission in the modulation of brain function. Focus on the striatal neuronal-glial networks. Front Physiol 3:136.

Fuxe K, Borroto-Escuela DO, Romero-Fernandez W, Palkovits M, Tarakanov AO, Ciruela F, Agnati LF (2014) Moonlighting proteins and protein-protein interactions as neurotherapeutic targets in the G protein-coupled receptor field. Neuropsychopharmacology 39:131–155.

Fuxe K, Dahlstrom A, Hoistad M, Marcellino D, Jansson A, Rivera A, Diaz-Cabiale Z, Jacobsen K, Tinner-Staines B, Hagman B, Leo G, Staines W, Guidolin D, Kehr J, Genedani S, Belluardo N, Agnati LF (2007) From the Golgi-Cajal mapping to the transmitter-based characterization of the neuronal networks leading to two modes of brain communication: wiring and volume transmission. Brain Res Rev 55:17–54.

Fuxe K, Dahlstrom AB, Jonsson G, Marcellino D, Guescini M, Dam M, Manger P, Agnati L (2010) The discovery of central monoamine neurons gave volume transmission to the wired brain. Prog Nuerobiol 90:82–100.

Fuxe K, Ferre S, Canals M, Torvinen M, Terasmaa A, Marcellino D, Goldberg SR, Staines W, Jacobsen KX, Lluis C, Woods AS, Agnati LF, Franco R (2005) Adenosine A2A and dopamine D2 heteromeric receptor complexes and their function. J Mol Neurosci 26:209–220.

Fuxe K, Fredholm BB, Ogren SO, Agnati LF, Hokfelt T, Gustafsson JA (1978) Ergot drugs and central monoaminergic mechanisms: a histochemical, biochemical and behavioral analysis. Federation Proc 37:2181–2191.

Fuxe K, Jacobsen KX, Hoistad M, Tinner B, Jansson A, Staines WA, Agnati LF (2003) The dopamine D1 receptor-rich main and paracapsular intercalated nerve cell groups of the rat amygdala: relationship to the dopamine innervation. Neuroscience 119:733–746.

Fuxe K, Marcellino D, Rivera A, Diaz-Cabiale Z, Filip M, Gago B, Roberts DC, Langel U, Genedani S, Ferraro L, de la Calle A, Narvaez J, Tanganelli S, Woods A, Agnati LF (2008) Receptor-receptor interactions within receptor mosaics. Impact on neuropsychopharmacology. Brain Res Rev 58:415–452.

Fuxe K, Ungerstedt U (1967) Localization of 5-hydroxytryptamine uptake in rat brain after intraventricular injection. J Pharm Pharmacol 19:335–337.

Fuxe K, Ungerstedt U (1970) Histochemical, biochemical and functional studies on central monoamine neurons after acute and chronic amphetamine administration. In: Amphetamines and related compounds (Costa E, Garattini S, eds), pp 257–288. New York: Raven Press.

Fuxe K, Ungerstedt U (1974) Action of caffeine and theophyllamine on supersensitive dopamine receptors: Considerable enhancement of receptor response to treatment with dopa and dopamine receptor agonists. Med Biol 52:48–54.

Goldstein M, Battista AF, Ohmoto T, Anagnoste B, Fuxe K (1973) Tremor and involuntary movements in monkey: Effect of l-dopa and of a dopamine receptor stimulating agent. Science 179:816–817.

Harfstrand A (1987) Brain neuropeptide Y mechanisms. Basic aspects and involvement in cardiovascular and neuroendocrine regulation. Acta Physiol Scand Suppl 565:1–83.

Harfstrand A, Fuxe K (1987) Simultaneous central administration of adrenaline and neuropeptide Y leads to antagonistic interactions in vasodepressor responses in awake male rats. Acta Physiol Scand 130:529–531.

Harfstrand A, Fuxe K, Agnati L, Fredholm B (1989) Reciprocal interactions between alpha 2-adrenoceptor agonist and neuropeptide Y binding sites in the nucleus tractus solitarius of the rat. A biochemic and autoradiographic analysis. J Neural Transm 75:83–99.

Hoistad M, Samskog J, Jacobsen KX, Olsson A, Hansson HA, Brodin E, Fuxe K (2005) Detection of beta-endorphin in the cerebrospinal fluid after intrastriatal microinjection into the rat brain. Brain Res 1041:167–180.

Jansson A, Descarries L, Cornes-Hebert V, Riad M, Verge D, Bancila M, Agnati LF, Fuxe K (2002) Transmitter-receptor mismatches in central dopamine, serotonin and neuropetide systems. In: The neuronal environment: Brain homeostasis in health and diseases (Walz W, ed), pp 83–107. New Jersey: Humana Press.

Jansson A, Goldstein M, Tinner B, Zoli M, Meador-Woodruff JH, Lew JY, Levey AI, Watson S, Agnati LF, Fuxe K (1999) On the distribution patterns of D1, D2, tyrosine hydroxylase and dopamine transporter immunoreactivities in the ventral striatum of the rat. Neuroscience 89:473–489.

Jansson A, Tinner B, Bancila M, Verge D, Steinbusch HW, Agnati LF, Fuxe K (2001) Relationships of 5-hydroxytryptamine immunoreactive terminal-like varicosities to 5-hydroxytryptamine-2A receptor-immunoreactive neuronal processes in the rat forebrain. J Chem Neuroanat 22:185–203.

Olson L, Seiger A, Fuxe K (1972) Heterogeneity of striatal and limbic dopamine innervation: highly fluorescent islands in developing and adult rats. Brain Res 44:283–288.

Pintsuk J, Borroto-Escuela DO, Pomierny B, Wydra K, Zaniewska M, Filip M, Fuxe K (2016) Cocaine self-administration differentially affects allosteric A2A-D2 receptor-receptor interactions in the striatum. Relevance for cocaine use disorder. Pharmacol Biochem Behav 144:85–91.

Romero-Fernandez W, Borroto-Escuela DO, Agnati LF, Fuxe K (2013) Evidence for the existence of dopamine D2-oxytocin receptor heteromers in the ventral and dorsal striatum with facilitatory receptor-receptor interactions. Mol Psychiatry 18:849–850.

Simons M, Raposo G (2009) Exosomes − vesicular carriers for intercellular communication. Curr Opin Cell Biol 21:575–581.

Tanganelli S, Antonelli T, Tomasini MC, Beggiato S, Fuxe K, Ferraro L (2012) Relevance of dopamine D(2)/neurotensin NTS1 and NMDA/neurotensin NTS1 receptor interaction in psychiatric and neurodegenerative disorders. Curr Med Chem 19:304–316.

Tarakanov AO, Fuxe KG (2010) Triplet puzzle: homologies of receptor heteromers. J Mol Neurosci 41:294–303.

Ungerstedt U, Butcher LL, Butcher SG, Anden NE, Fuxe K (1969) Direct chemical stimulation of dopaminergic mechanisms in the neostriatum of the rat. Brain Res 14:461–471.

Zhang W, Wang Z, Jia S, Tian Y, Wang G, Li H, Fuxe K (2017) Is there volume transmission along extracellular fluid pathways corresponding to the acupuncture meridians? J Acupunct Meridan Stud 10:5–19.

Zoli M, Agnati LF, Hedlund PB, Li XM, Ferre S, Fuxe K (1993) Receptor-receptor interactions as an integrative mechanism in nerve cells. Mol Neurobiol 7:293–334.

Michael E. Goldberg

BORN:

New York, New York

August 10, 1941

EDUCATION:

Harvard College, A.B. magna cum laude in Biochemical Sciences (1959–1963)

Graduate Fellow, Rockefeller Institute for Medical Research (1963–1964)

Harvard Medical School, MD cum laude (1964–1968)

Medical House Office, Peter Bent Brigham Hospital (1968–1969)

Staff Associate, under Robert H. Wurtz, Laboratory of Neurobiology, National Institute of Mental Health (1969–1972)

APPOINTMENTS:

Research Neurologist Armed Forces Radiobiology Research Institute, Bethesda, Maryland (1975–1978)

Investigator, Laboratory of Sensorimotor Research, National Eye Institute, Bethesda, Maryland (1978–2001)

Assistant to Professor of Neurology at the NIH, Georgetown University School of Medicine, Washington, DC (1978–2001)

David Mahoney Professor of Brain and Behavior in the Departments of Neuroscience, Neurology, Psychiatry, and Ophthalmology; and Director of the Mahoney Center for Mind and Brain, Columbia University College of Physicians and Surgeon, New York, New York (2001–present)

Research Scientist VIII and Chief, Neurobiology and Behavior Division, New York State Psychiatric Institute, New York, New York (2001–present)

Senior Attending Neurologist, New York Presbyterian Hospital, Columbia University Medical Center (2001–present)

HONORS AND AWARDS (SELECTED)

Phi Beta Kappa (1963), Alpha Omega Alpha (1968)

S. Weir Mitchell Award, Best Research Essay by a junior member of the American Academy of Neurology (1972)

Trustee, Neural Control of Movement Society (1996–1998)

Wundt Lecture, Max Planck Institute for Cognitive Neuroscience, Leipzig, Germany (1999)

Sprague Lecture, Mahoney Neuroscience Institute, University of Pennsylvania (2000)

Special Lecture, Society for Neuroscience Annual Meeting (2001)

Heller Lecture in Computational Neuroscience, Hebrew University and Hadassah Medical School, Jerusalem, Israel (2002)

Society for Neuroscience, Treasurer (2006) and President (2010)

Louis P. Rowland Teaching Award, Columbia University Department of Neurology (2006)

Fellow of the American Academy of Arts and Sciences (2006)

Fellow of the American Association for the Advancement of Science (2008)

David Robinson Lecturer, Department of Biomedical Engineering, Johns Hopkins (2010)

Swammerdam Lecturer, Netherlands Neuroscience Institute, Amsterdam (2010)

Elected to the National Academy of Sciences (2011)

Patricia Goldman-Rakic Award for Cognitive Neuroscience, Brain and Behavior Research Foundation (2011)

Michael E. (Mickey) Goldberg is a pioneer in the study of the visual and oculomotor systems in the awake, behaving monkey. As a postdoctoral fellow with Bob Wurtz, he discovered attentional enhancement of visual neurons and presaccadic neurons in the monkey superior colliculus. He went on in his own lab to make salient contributions to our understanding of the visual and oculomotor system, attention, and spatial perception He is currently studying how oculomotor proprioception is necessary for spatial memory, the role of the cholinergic system in facilitating activity in the parietal cortex, and the role of the cerebellum in visuomotor learning.

Michael E. Goldberg

Early Days

I was born in a dark time. My parents were the children of immigrants who came to America to escape the perils of Eastern Europe for Jews. My mother’s father was an assimilated Rumanian Jew, trained as an architect. The family legend is that he designed a church in Bucharest. When people discovered that the church had been designed by a Jew, they burned it down and threatened his life. He, his wife, and their three children left Bucharest in the middle of night and escaped to New York. He never practiced architecture again but got work as a draughtsman. My mother was his youngest child, born in New York.

My father’s parents were religious Jews, living in small shtetls in the Russian Pale of Settlement for Jews, now mostly in the Ukraine. My grandmother’s brother had emigrated to America, and when he could afford it, he sent for his sister. At the age of 13, she traveled to London by herself, spent some months with the family of friends who had left the shtetl earlier, and went to New York. She was my only grandparent whom I ever met. I asked her what she remembered about her life in Russia—she said that she remembered the mud, the frequent religious processions of her Polish neighbors, and the worries that the procession might turn into a pogrom. She met my grandfather in New York. My grandfather was a peddler. My father fondly remembered his horse.

My grandfather died early. Somehow my grandmother was able to open a small delicatessen in a Polish neighborhood in the Bronx, and the family survived. My father and his twin brother were excellent students and were admitted to Stuyvesant (then as now one of the best and most selective high schools in New York). From the age of 13 onward, he worked evenings selling souvenirs and trinkets outside Broadway theaters. Simultaneously, he finished high school and then went to the City College of New York (CCNY), where he studied chemistry. CCNY then had no tuition payments. After graduating from college, he earned a master’s degree from Columbia in chemistry. His Columbia diploma, signed by Nicholas Murray Butler, is the only diploma on my office wall. He was advised that academic chemistry was not a good place for Jews, so he applied to medical and dental schools and was accepted at New York University (NYU) dental school. By this time, he was working inside the theaters, ultimately becoming head of concessions for the Schubert theaters. One night a producer asked him if he would rather go on the road to be the stage manager of a production of Oh, Kaye! (a Gershwin musical). He thought long and hard about it, but he was already halfway through dental school and had met my mother. He often wondered what his life would have been like had he entered show business rather than tooth business. After he graduated from dental school, he worked for another dentist for a year or so and then started his own practice in Inwood, the neighborhood at the top of Manhattan. Now a Dominican neighborhood, then it was an Irish-Jewish neighborhood, with a Kosher butcher and deli, Irish bars, and two Yiddish newspapers in the candy store. The dental office was a large apartment at the corner of Vermilyea Avenue and 207th Street, near the top of the A train. His waiting room and office were the livingroom and dining room of the apartment, and the family lived in the back five rooms. His lab was the walk-in pantry in the kitchen. My parents asked my grandmother to close her deli and invited her and my father’s twin sisters to move in with us. My father often said that the proudest day in his life was when he realized he could support my grandmother, and she no longer had to work in her deli.

I was born in August 1941. Germany had swept through Western Europe, threatening to overwhelm Britain. After Pearl Harbor, my father volunteered to join the army as a dentist. He was commissioned a second lieutenant and spent the war in various places in the south, practicing dentistry on American GIs and German prisoners of war. He later told me that he felt, as a Jew, that he had no choice other than volunteering. My earliest memory was taking the train to South Carolina to visit my father. My next earliest memory was his marching in the memorial parade for President Roosevelt.

I enrolled in kindergarten in PS 98, on 211th Street. I thought I was going to learn to read. Instead, they gave me crayons and told me to draw. I moped. The kindergarten teacher thought I was a bit dull. Kindergarten was voluntary in those days, so after a few months my mother took me out of the class. First grade was much better—I learned to read. In 1947, my parents moved to Eastchester, in Westchester County, a bit north of the Bronx. My mother took me to Waverley School, the local elementary school, to enroll me. We met Mr. Merchant, the principal. I moped. Mr. Merchant said that they had an accelerated first grade, but he would put me into a regular first grade for the few weeks remaining. Two weeks later, he asked my parents if they would allow him to skip me to the third grade for the next year. She thought it would be a bad idea, given that I was the smallest kid in the class and socially quiet. I think she made a brilliant decision. She also turned down a subsequent offer for me to skip the third grade.

From the time that I knew what science was, I wanted to become a physician and a scientist. My father encouraged me to learn about chemistry. I remember a Child’s Book of Atoms and Molecules as an early gift from him. In those days, you could get a kid’s chemistry set that had some oomph, and I loved to play with it with my father. I was entranced by the wonders of phenolphthalein changing color and amused that the chemical was also the active ingredient in Ex-Lax (no longer, because of its mild carcinogenicity). We made borax beads with an alcohol lamp. I loved looking at and naming stars and planets, learning trees and birds. Science wasn’t everything. My parents introduced me to classical music, history, novels, poetry, and the theater. My Aunt May took me to the Metropolitan Opera. I took piano lessons.

I was a star in high school—best student, editor of the newspaper, president of the dramatic club, all-county chorus in the glee club. I finished first in the state on the New York State Regents scholarship exam. I was an enthusiastic Boy Scout: hiking and camping (foreign to my family), winning the county Scout nature contest, and tying the bowline on our prize-winning knot-tying relay team. I accumulated enough merit badges to become an Eagle Scout. In that scoundrel time, darkened by the shadow of Joseph McCarthy, every potential Eagle Scout had to appear before a special board of review. They asked me if I were drafted into the army could there be any order I would not obey. I said, of course, that was what the Nuremberg trials were about. I reserved the right to evaluate the morality of my orders. The board of review decided to make a home visit rather than passing me at once. I suspect they were looking for pictures of Lenin and Karl Marx, and copies of Das Kapital. My father calmed them down, as did the picture on the wall of Captain Goldberg in his army uniform. I can still tie knots and identify birds.

I got a summer job at the local drug company, Burroughs-Wellcome. Sir Henry Wellcome divorced his wife who was 27 years younger than he was because of her affair with the novelist W. Somerset Maugham. Wellcome’s daughter Syrie was probably Maugham’s child, and he disinherited her. He left his fortune to the Wellcome Trust and specified that the profits from his company be used exclusively for the research in the company and at other institutions. I was assigned to a lab that was working on purine and pyrimidine antimetabolites. The head of the lab, Dr. George Hitchings, was a remote, rather austere man who had gotten the idea that compounds that interfered with DNA synthesis and function might slow the growth of cancers. The person who organized the day-to-day work in the lab was Gertrude Elion. She didn’t have a PhD. After she graduated from Hunter College (the free woman’s college in New York City), she couldn’t afford to go to graduate school and worked at various chemical and nonchemical jobs. She started working as a technician for Dr. Hitchings and ultimately became his scientific partner. Trudy was one of the warmest, most welcoming people I ever met as well as a great scientist and an especially talented synthetic chemist. They first developed 6-mercaptopurine and thioguanine, which worked against certain forms of leukemia. Those were also the early years of allogeneic kidney transplants, and they realized that their antileukemia drugs might work as immunosuppressors. Their drug azathioprine, a conjugated form of thioguanine, was the first successful nonsteroid immunosuppressive for kidney transplants. It is still used today as an immunosuppressive for various autoimmune diseases. AZT, a drug that had not worked as an antitumor drug or an immunosuppressive was the first successful drug for AIDS. Pyrimethamine, an antifolate drug, is used to treat toxoplasmosis. Trimethoprim is an antibacterial drug. Allopurinol slows the degradation of purines to uric acid and prevents gouty attacks. Trudy and Dr. Hitchings shared the Nobel Prize in 1988.

My job was to work on the tumor screen. On Monday, we would implant chunks of a mouse sarcoma into the peritoneum of C57 black mice. For the next four days, we would inject a particular drug intraperitoneally into each mouse. On Friday, we would kill the mice, take out the tumor, weigh it, and compare it to growth in mice treated with 6-mercaptopurine, and others treated with normal saline. The work was boring, but the ideas floating around the lab were exciting. The lab played bridge at lunch. One of my jobs was to substitute for people on vacation. Trudy was a great bridge player. She also loved opera and had front row center seats in the balcony tier at the Met. We talked as much opera as science.

College and Molecular Biology

When I arrived at Harvard College, I discovered that everyone had been a star in high school, and I was way behind. There were two other Goldbergs in my class—Fred (recently elected to the National Academy of Sciences for discovering proteosomes) and George. I started by taking math and science. I took the calculus class for math majors and realized that I was never going to be a mathematician. My ineptitude in quantitative analysis made me think twice about doing science for real, so I decided after my first year to continue premed but concentrate in English. Like most premeds, I took organic chemistry as a sophomore. There was a Cliffie (a student at Radcliffe, the women’s college of Harvard University) in my organic chemistry lab section whistling the Franck D Major symphony. Her name was Debbie Baron. We said hello frequently but never dated.

I wrote a tutorial paper on The Miller’s Tale from Chaucer’s Canterbury Tales, which my tutor loved and that I thought was trivial. I realized that English scholars comment on what other people had created, but scientists create. I switched my concentration to biochemical sciences to try again. This was the beginning of the great era of molecular biology. Watson and Crick had deciphered the structure of DNA, and Jacob and Monod were unraveling the mechanisms that controlled protein synthesis. I learned about messenger RNA, transfer RNA, ribosomes, and Nirenberg’s breaking the genetic code. The most exciting course I took was William Sistrom’s course on growth and biosynthesis in microorganisms. I took quantum mechanics, statistical mechanics, Shakespeare, metaphysical poetry, and Middle English poetry. Harvard College had no neuroscience of which I was aware. Psychology was B. F. Skinner’s behavior, with the brain as a black box. I spent some time working in my tutor William S. Beck’s lab, but I didn’t accomplish much. I didn’t write a thesis. I did a lot of theater tech, mostly lighting design, and a lot of music. I still remember the thrill of singing the Verdi Te Deum with the Harvard Glee Club and the Boston Symphony under Carlo Maria Giulini.

I applied to medical school and graduate school. Dr. Perry Culver, dean of admissions at Harvard Medical School said that I wouldn’t know for the first two years whether medical school were the right choice, but I would know much sooner in graduate school. He told me to defer medical school and go to graduate school. I took his advice and went to the new graduate program at the Rockefeller Institute for Medical Research, now Rockefeller University, where I wanted to work on mammalian molecular biology. I thought it had to be as exciting as E. coli, but no one had found that excitement.

At the Rockefeller Institute, on the Upper East Side on Manhattan, I worked in the Allfrey-Mirsky lab on calf liver nucleus histones. I made two important discoveries: I pipetted with a Poisson distribution (my mean was equal to my variance), and I could kill cell cultures from an adjacent room. Perry Culver was right. I decided to go to medical school because doctors make critical decisions on inadequate data and that seemed like fun. I would never go near a lab again. I reapplied and was accepted again to Harvard Medical School. That year, I spent a lot of time standing at the Metropolitan Opera and practicing the piano. I could actually play Beethoven’s Opus 78. I read all of Strangers and Brothers, C. P. Snow’s multivolume series of novels about British society and British science in the 1930s and 1940s.

Medical School and Neuroscience

I arrived at Harvard Medical School along with the other two Goldbergs, and Debbie (and 9 other women in a class of 100). With the exception of gross anatomy, which I actually enjoyed, most of the first year at medical school was a rerun of college, until the last six weeks, which was all neuroscience, all the time. Steven Kuffler had created the world’s first neuroscience department, and he and its young members—Torsten Wiesel, Dave Hubel, Dave Potter, Ed Furshpan, and Ed Kravitz—dedicated their time during those six weeks to teaching. It was a revelation, an awakening like the great chorus Et Expecto Resurrectionem from Bach’s B minor Mass, with the wonderful stretto fugue of ascending fourths.¹ I asked Dave Hubel to teach me more neuroscience, and he organized a tutorial during the next year at which we read a bunch of papers about systems neuroscience, not only by Hubel and Wiesel but also by Evarts, Mountcastle, Amassian, Kuffler, and Barlow.

The second year of medical school was dreary, with a few exceptions. I had moved off campus, sharing an apartment in Cambridge’s Central Square with two economists and another medical student. One day, I asked Debbie to come over to my apartment for brunch. A few weeks later, we had a date (the Cornell game and dinner), and some time that day, having known each other for five years, we fell in love. It was as if we had we swallowed Brangaene’s love potion from Tristan und Isolde. She moved in the next week, we got married that summer, and 52 years later, we are still living happily ever after. Another exception was the traditional, raunchy Harvard Medical School Second-Year Show. I organized the tech and lighting and wrote the lyrics (“Nothing remains but the tomb. No ray of hope can come through to us. We cannot return to the womb. Now that we know it is the uterus”). The only courses I liked were neuropathology and physical diagnosis, in which we actually got to examine real patients for the first time. I felt the thrill of clinical medicine.

Entranced by the tutorial in systems neuroscience (columns, hypercomplex cells, and the dream that neurophysiology might render perception understandable), and despite my better judgment, I asked Dave Hubel if I could work in his and Torsten’s lab the following summer. He asked me what I wanted to do. I said that there was all this feature specificity in the visual cortex, but no one had reported anything similar in the somatosensory cortex. He told me to look for it. Mark Hallett, another medical student (ultimately to head the clinical neurology branch at the National Institute of Neurological Disorders and Stroke in Bethesda) and I built an electrode advancer, hooked up an amplifier and an oscilloscope, and learned to drill away the skull and peel away the layers of dura until there was only a transparent membrane left. We found lots of touch-sensitive neurons and ultimately found one directionally selective motion sensitive neuron. I was hooked.

In 1967, there was a war in Vietnam, and every physician with a Y chromosome owed the government two years, unless you were 6’6” or taller. There was no exception for those of us on the other side of the Gaussian distribution, but a lucky few could join the Public Health Service and work at the National Institutes of Health (NIH) or the U.S. Food and Drug Administration instead of going to Vietnam. I asked Dave to write Ed Evarts at the NIH to see whether he had space in his lab for still another Harvard Medical student (Tom Thach, Mahlon Delong, and Harris Funkenstein were already there). Ed didn’t have space, but passed the letter on to Bob Wurtz, who had just joined the Laboratory of Neurobiology at the National Institute of Mental Health (NIMH) and was looking for his first postdoc. Bob interviewed me and told me about his still unpublished work on visual cortex in the awake monkey. He had trained monkeys to fixate, so the position of a stimulus on the screen corresponded to its retinal position. He could then work out the receptive field properties of neurons in awake monkeys, which for these evanescent few seconds were like anesthetized monkeys. He also was able to study the effects of eye movements on cortical neurons. I was entranced.

I spent the next year as a medical intern in the old Peter Bent Brigham Hospital in Boston. A few weeks into my internship, the NIH offered me a position as a staff associate with Bob, starting July 1969. A few days after that, I got an invitation from the Army to go to Fort Sam Houston in Texas, and thence to Vietnam, which I delightedly declined. Those were the days of the iron men (and a few iron women). We were on every other night for almost the entire year. Monday, Wednesday, the weekend, Tuesday, Thursday, and Friday. I loved my internship, the clinical challenges, and the human interactions, but it was exhausting—Debbie took care of a choreographer at the Cambridge Hospital who gave us tickets for a Friday night performance of his show. Every other Friday, was the only day that we went to work in the morning and came home the same day, like ordinary humans. We slept through the intermission. July 1, 1969, Debbie and I moved to Washington, DC: I to work at the NIH, and Debbie to do a medical residency at Georgetown.

NIH and the Superior Colliculus

When I arrived at the NIH, I didn’t know much. I had never even heard the word “saccade,” the rapid eye movement that drives the center of gaze from point to point in the visual world. Bob had done his PhD in psychology at Michigan, studying self-stimulation under James Olds. When he offered me the job, I don’t think he realized my level of ignorance. He introduced me to concepts that I had never heard of, like visual attention, saccadic suppression, corollary discharge, and operant conditioning. I read Teuber on corollary discharge (Teuber 1960) and William James on attention, as well as a lot of neurophysiology. Bob taught me the mysteries of awake monkey neurophysiology.

This was the Paleolithic era of neurophysiology. Ed Evarts had developed the equipment for recording the activity of single neurons in awake, behaviorally trained monkeys. We controlled the monkey’s behavior by hooking together individual logic modules (or-gates, and-gates, one-shots, flip-flops, digital inputs, and output relays) that would sense the monkey’s pressing a bar, open a shutter to present a visual stimulus or turn on an LED fixation point, and reward the monkey with a drop of water. The logic modules, DigiBits, were mounted in rows on a rack and connected in the back by a welter of wires. The tool that connected and disconnected the wires was the digi-bitter, and we referred to the frequent times of trouble as Bitter Digi. We measured eye movements by using electroencephalography electrodes pasted to the monkey’s skin to give us a rather noisy direct current (DC) electrooculogram (EOG). We used glass-coated platinum iridium electrodes made by our technician Mary Fran Roark to pierce the dura and then study one cell at a time. We had a wonderful Rube Goldberg (no relation) device to build data analysis raster plots online. We used a Tektronix storage oscilloscope, which didn’t erase the screen until you told it to. The electrode signal was hooked up to a voltage-crossing detector, which emitted a pulse when the signal went above a threshold. Jim Bryan, the head of the NIMH technical development section, had built a digital delay line for Bob. Pulses from the voltage-crossing detector went into the delay line and emerged 300 ms later. We used a raster circuit to feed a DC level into the y input of the oscilloscope, set the timebase for two seconds, and triggered the x sweep of the oscilloscope on an event, like the pulse that opened the shutter. The pulses from the delay line went into the z input, which intensified the beam, so there would be a dot on the screen when a pulse occurred, with the screen otherwise dark. The delay line allowed us to record activity 300 ms before the triggering event, because the pulses that the oscilloscope saw at time τ had actually occurred at time τ −300. After the trial, the raster circuit would step the DC level down to the next line. When the screen was filled up, we would take a Polaroid picture of the screen, and paste it into the notebook, and then erase the screen. If we could hold the cell long enough, we could pass the EOG trace through a voltage-crossing detector and see the relationship of the activity to the eye movement. We couldn’t perform both analyses at once, so Bob convinced the NIH to buy him an 11-track FM Hewlett-Packard tape recorder to record the experiments, and then we could play the tape again, and reanalyze the data on the missing trigger.

It was also a time when one could hope to keep up with all of neuroscience. We had a journal club that included Bob and me, Mahlon Delong and Noriichi Mano from Ed Evarts’s lab, Mark Hallett who was working on squid axons with Ichiji Tasaki, and David Carpenter (now professor of environmental health sciences at SUNY Albany) who was working on aplysia. We read Kandel, Mountcastle, and Grillner. I miss the broad extent of that journal club in our much more focused world.

This was a time in which you could close your eyes, throw an electrode into the brain of an awake, behaving monkey, and discover something. Bob suggested that we work on the superior colliculus. The superior colliculus is a multilayered structure, with the superficial layers receiving a strong visual input from the retina and V1. We began by studying the visual properties of neurons in the two superficial layers. Peter Sterling and Barbara Wickelgren (now Gordon-Lickey; Sterling and Wickelgren 1969) had recorded from the superior colliculus in the anesthetized cat. They found that almost all of the cells were motion sensitive and selective for the direction of movement. Very few cells in the superficial layers of the awake monkey were motion selective. I named these cells “pandirectional,” to emphasize that they were not motion sensitive or selective, clumsily combining a Greek (pan) and a Latin (directional) word. They should have been called “omnidirectional.” Receptive field size increased as the electrode got deeper into the colliculus, but their centers remained in register (Goldberg and Wurtz 1972). One day, we drove the electrode too deep and heard neural hash going “whoosh whoosh” even when the monkey was in total darkness and making spontaneous eye movements. We realized that these whooshes preceded saccadic eye movements (Wurtz and Goldberg 1971; Wurtz and Goldberg 1972). We mapped out the area of the retina to which, when the monkey made a saccade, the cell would fire, and we called that area the movement field of the cell. Movement fields in the intermediate layers were in register with the visual receptive fields in the superficial layers above. Some intermediate-layer cells had both visual and presaccadic activity. Others had only presaccadic activity. We put an electromyography electrode on the lateral rectus muscle to ensure that the superior colliculus signal preceded the muscle activation as well as the actual eye movement. The movement fields were very large.

We then wondered whether we had missed saccadic activity in the superficial layers. At that time, the only saccade task we used was a simple reflexive visually guided saccade. The fixation point went out, the saccade target appeared, and the monkey made a saccade. Because the reaction time of the saccade varied from trial to trial, the activity of visual cells was better synchronized to the target appearance than to the movement. The activity of movement cells in the intermediate layers was poorly synchronized to the target appearance but well synchronized to the beginning of the saccade. The cells in the superficial layers were all synchronized to the appearance of the target. Half of the neurons, however, gave an enhanced response when the monkey was going to make a saccade to the stimulus in its receptive field, as compared with its responses in the fixation task. There was no enhanced response to a stimulus in the receptive field if the monkey made a saccade to a target outside the receptive field. We thought that the enhanced response was a physiological correlate of attention (Goldberg and Wurtz 1972). We then made electrolytic lesions in the colliculus to see whether there was a behavioral correlate of the neuronal activity that we had discovered. After the lesion, the monkeys made contralateral visually guided saccades, but with very long reaction times. Over a couple of months, the reaction times shortened, until they were only about 25 ms longer than ipsilaterally directed saccades. We concluded that this was an attentional deficit and that because the movement fields of the colliculus were so large, it was unlikely that the colliculus was driving saccades. We argued that the role of the colliculus was to effect a shift of spatial attention and not to drive saccades (Wurtz and Goldberg 1972). Sometimes you write something that you wish you hadn’t. It became more and more obvious that the colliculus was driving saccades. David A. Robinson (1972) had shown that you could evoke saccades by stimulating the superior colliculus, and the map of evoked saccades resembled the visual map. Peter Schiller and Mike Stryker (1972) had shown that electrical stimulation of the colliculus evoked saccades to the center of the cells’ movement fields, and they concluded that the colliculus was driving saccades, not shifting attention. Years later, at a symposium to celebrate the 25th anniversary of the Laboratory of Sensorimotor Research (LSR) of the National Eye Institute (NEI), Mike Stryker told how Peter said, “Those guys not only missed the boat, they missed the ocean.” Luckily, Rich Krauzlis showed, many years later, that inactivation of the colliculus did cause an attentional deficit (Krauzlis et al. 2013). Often the answer to a heated scientific argument is “both.”

Doing the superior colliculus experiments taught us that our methods were so cumbersome that more progress was going to be quite difficult. Behavioral programming was awkward. Data analysis was primitive. Bob had a worked a bit with a Laboratory Instrument Computer (LINC) and had some experience programming. He said it was time to buy a computer. Buying a computer at the NIH was rather bureaucratic. The Digital Equipment Company, DEC, had just marketed a laboratory computer, the PDP12, which fit our needs. It had analog-to-digital inputs through which we could record eye movements; digital inputs with which we could measure unit pulses; and digital outputs that could open and close shutters and the water solenoid, or turn on, dim, and turn off the fixation point. It had a 5-inch CRT that we could program, pixel by pixel. It had a clock speed of 100 kHz, 12 K 12 bit words of core memory. It was actually two computers sharing a box, the LINC and DEC’s workhorse PDP 8 joined together. A software settable mode switch would determine which computer it was. Data storage was on two rewritable three-quarter-inch mini tape drives. It did not have a hard disk. I had to convince the NIH that this was the best computer for us—a “sole source” justification that included a market survey documenting why GE, Data General, Varian, and other minicomputers were not as good for our purposes. It cost $35,000 1970 dollars and occupied two full relay racks. It changed our lives.

I had no computer experience at all. On nights when Debbie was on call at the hospital, we would have dinner (I usually brought her dinner that I had cooked, hot food kept warm during the two-block walk from our house to Georgetown University Hospital) and then drove back to Bethesda to learn to program. The LINC had a language called FOCAL that could do math, but it was far too slow to be usable in real time. I had to learn LINC assembler. I wrote the behavioral control and data analysis sections. Bob wrote the eye movement recognition section. DEC had inserted a new feature into the computer, vectored interrupts, which had not been on either the PDP8 or the LINC. Instead of polling input devices, when an event (like a clock tick) occurred, it would interrupt the current program. In our case, the program running the display and the computer would switch to the interrupt service routine, and when it was done, it would restore the background program. It didn’t work. The program would run for a while and then blow up. I called DEC, and it turned out that we were the first customers to use vectored interrupts. An engineer from DEC came down, sat in the lab, and after a week or so discovered that there was an occasional glitch in the postinterrupt restoring hardware, so it would restore the program counter to the wrong memory block.

The fixed computer worked. It controlled the behavior, sampled eye movements and unit pulses, and calculated rasters. It displayed a running line of the experiment—behavior, units, eye movements, or a data raster for which we could specify triggers and time bases. We hooked up a Grass oscilloscope camera to a slave oscilloscope. When we hit a hardware switch, the camera would take pictures of the rasters synchronized on the beginning of the saccade, the end of the saccade, the appearance of the stimulus or saccade target, and example eye movements. We used the Grass camera negatives to make figures.

The first experiment using the new computer system was a study of the monkey frontal eye field (FEF). Emilio Bizzi (1968), using an awake but untrained monkey, had recorded FEF neurons while monkeys made saccades in total darkness. He was unable to find neurons that responded before these saccades, but he did find neurons that fired during and after eye movements. He suggested that this was a corollary discharge signal, telling the rest of the brain that an eye movement had taken place. Bob, I, and then Chuck Mohler, who replaced me as Bob’s staff associate after I had left the NIH, found that neurons in the monkey FEF had visual receptive fields, which were a plausible contribution to saccade generation. At the 1973 Society for Neuroscience (SfN) meeting in San Diego, Luke Teuber, chair of psychology at the Massachusetts Institute of Technology (MIT), gave a summary of what he thought were the most interesting 10-minute talks at the meeting. It is hard to imagine anyone doing that today. Luke mentioned our description of visual receptive fields in the FEFs. He said that he wished they had been discovered in another place—and that he was not referring to another place in the brain.

Debbie got pregnant in 1969. She was the first woman resident in medicine in 10 years at Georgetown and was determined not to let her pregnancy get in the way of her performance as a resident. One day late in her pregnancy, she noticed a rapid pulse. She took a quick EKG on herself. It was a supraventricular tachycardia. She asked the resident about it—he looked at it and said, “I don’t know, admit it.” She never said that it was her EKG. The tachycardia went away by itself. She was on call every third night until two days before our son Josh was born. She organized her vacation period and elective rotations to start with her delivery, and never missed a day of serious call. We lived two blocks from Georgetown University Hospital. When Josh was hungry our full-time live-in childcare person would beep Debbie and take him to the Georgetown emergency room, where Debbie would breastfeed him. We had some day-care problems, solved by Debbie’s Aunt Esther, who had just retired and offered to help us. She lived with us for more than 20 years.

That was the era of the great anti–Vietnam War marches on Washington. We signed on as physicians to serve as a medical presence. I remember a man with Huntington’s chorea in a wheelchair, who came by the medical unit to rest, but said he would not have missed the march for anything. After the first march, the Yippies charged the justice department building. Our medical van followed them. They fought with the police who fought back with tear gas. Josh was gassed in utero and born on the day Nixon began bombing Cambodia, April 30, 1970. Jon, our second son, was born while Debbie was chief resident in medicine on the Georgetown Service at DC General Hospital. Debbie made rounds four days after Jon was born, carrying him to the hospital in a baby attaché case so she could breastfeed him.

Boston and Neurology

I was committed to being a neuroscientist, but I also wanted to be a neurologist, so I entered the Harvard Longwood Program in 1972, after three years in Bob’s lab. The program included the Peter Bent Brigham Hospital, Boston Children’s Hospital, and the Beth Israel Hospital (B.I.). The chief was Dr. Charles Barlow, a great clinical neurologist. He was famous for aphorisms: “In neurology you are lucky if you know it is above or below the foramen magnum,” but “you are in trouble if you don’t have an idea of what it is by the time you cross the room to the bedside.” He had incredibly accurate intuition, which complemented his traditional neurological compulsiveness.

Debbie took a job practicing internal medicine in a B.I.-related practice in Chelsea, Massachusetts, with Alan Kaitz, an older internist who needed an associate. They took care of most of their patients in the little Chelsea Memorial Hospital, but shipped their sickest patients to the B.I. where they were called “Chelsea Specials.” I was the only resident in the hospital whose wife was an attending.

During the second year of my residency, Nixon impounded the funds that paid for neurology residents, and the program found itself strapped for money. Charlie Barlow offered me a position in the Harvard Neurology Department, but with inadequate startup funds. In the meantime, David Carpenter had been given the opportunity to build a neuroscience department at the Armed Forces Radiobiology Research Institute (AFRRI) on the grounds of the Bethesda Naval Hospital. He made me a fabulous offer, with money for a technician and postdocs; computer facilities, including our own lab computer; faculty-equivalent staff positions for me and for David Lee Robinson, who was doing a postdoc with Bob; and access to a fully staffed primate vivarium. I asked Charlie Barlow what to do—he said that the AFRRI offer was much better, but he could give me a lot of prestige. I went to AFRRI. Charlie asked me if I would not mind saving money for the program by going to Bethesda nine months before my actual three years of residency ended. He said I could do a research rotation with myself, and he would certify me for three years of residency so I could pass neurology boards. In my last rotation in neurology I was chief resident at the B.I. My neurology team was Marc Dichter and Barry Richmond, both of whom have gone on to illustrious careers in neuroscience. My intern was Steve Bergman, a rather hostile, depressed kid who was the poster child for the Vietnam Era counterculture. We worked hard on teaching Steve some neurology and on calming him down. Steve went on to write The House of God, under the alias Samuel Shem. It is a scathing, funny indictment of academic medicine, still read today by almost every medical student and resident. He never mentioned the neurology department in the book. We took good care of our patients and our intern.

Washington and AFRRI

Nine months before the official the end of my residency we moved to Washington, DC. We bought a large house for two kids, Esther, Debbie, and me, in Spring Valley, a suburban area of the District, which originally had a restrictive covenant. The house could not be sold without the express permission of the W. C. and A. N. Miller Company and all of the neighbors on the block—effectively no Jews, African Americans, or Catholics. It was around the block from Lyndon Johnson’s mansion The Elms. It had been originally owned by a conservative Republican senator, Peter Dominick, and then by a liberal Dutch economist from the World Bank. One next-door neighbor, Hillie Paige, was a pioneer in rocket engineering, a member of the National Academy of Engineering, a former president of General Dynamics, and at that time a broker of nuclear reactors. He was a friend of the Shah of Iran. Our other neighbor, John Peabody, was a diplomat, a foreign service officer working in the Agency for International Development, specializing in spreading the good news of contraception. His program’s particular champion in Congress was a Texas congressman named George H. W. Bush. Allegedly Bush was so supportive of the program that his congressional colleagues called him “Rubbers.” Debbie got a job with Group Health and ultimately went into private practice, founding the first all-woman internal medicine practice in Montgomery County, Maryland. We commuted antidromically, in the opposite direction of the usual traffic flow, I to AFRRI and she to Silver Spring. I also arranged to do a bit of neurology at Georgetown—first in the clinic, and then when I passed my boards, as an attending on the ward and consult services.

David Lee Robinson joined me from the NIH, and we started to build our lab. We planned to look for attention-related activity in the pulvinar. We had a PDP11-10 computer, and I set about to recreate Monkrule, the program Bob Wurtz and I had written for the PDP12, for the PDP11. I called the new program Monk11. The PDP11 also had vectored interrupts—it treated hardware devices as actual memory locations. I still think it was humankind’s best computer design. It had a 2.2-megabyte hard disk drive with 18-inch white plastic disk cartridges, which looked like the Millennium Falcon, Han Solo’s ship from Star Wars. We had to make sure that we had multiple copies of our programs stored on different disks—despite our attempts to keep them clean, the disks got dirty and the heads crashed and destroyed the data not infrequently. The computer could only be booted by a paper-tape routine, not from a disk. AFRRI was right across Rockville Pike from the NIH, and we maintained a close relation with Bob. His people made our electrodes. He switched to the PDP11 and used our software.

A funny thing happened on the way to the pulvinar. Vernon Mountcastle had published two papers claiming that the posterior parietal cortex had command neurons that drove arm and eye movements that were not sensitive to light (Mountcastle et al. 1975; Lynch et al. 1977). Dave and I thought that unlikely, and that the command neurons that Mountcastle had described were actually visual neurons with enhanced responses. We decided to record from the posterior parietal cortex. We found lots of neurons that discharged before arm and hand movements, but they all had enhanced visual responses. Greg Stanton, an anatomist at Howard University Medical School, helped us with the histology (Robinson et al. 1978). We described command activity as “epiphenomenal visual responses,” something else I wish I had never written.

Bill Keys (now a practicing neurologist) from the University of Connecticut, and Cathie Bushnell (a star in the pain world, and now director of the Intramural Program of the National Institute for Alternative Medicine) from American University joined us as our first postdocs. Dave and Bill Keys went on to study the pulvinar. Cathie (then, Catherine now) and I decided to study Area 7 and the FEF Area 8 in parallel experiments, using two tasks, a saccade task and a peripheral attention task. In that task, first used by Bob in study of the superior colliculus and V1 (Mohler and Wurtz 1977), the monkey had to make a hand movement, releasing a bar, when a peripheral stimulus dimmed. Neurons in the colliculus only gave enhanced responses in the saccade task. In our experiments, neurons in the FEF also only gave enhanced responses in the saccade task, but neurons in the parietal cortex gave enhanced responses to both the saccade task and the peripheral attention task. This was further evidence that the parietal cortex had more of an attentional role than an oculomotor role. It is now clear that the FEF also has an attentional role (Kodaka et al. 1997; Thompson et al. 2005; Zhou and Thompson 2009), and I often wonder why we failed to see it. I think that it is because Catherine and I did our experiments in blocks—a peripheral attention block, and then a saccade block, or vice versa, and the more recent experiments used randomly interleaved trials. I suspect that comparing randomly interleaved trials to blocks in the FEF is something on my bucket list that I will never get around to.

I wondered why the AFRRI wanted two guys studying cognitive physiology in the monkey cortex, or for that matter a behavioral science division at all. Unhappily, I found out. This was the height of the cold war, and one of the problems faced by the Department of Defense (DOD) was that there were five times as many tanks on the east side of the West German border than there were on the west side of the East German border. It is the job of a defense department to assume that one day, after a sunbath or a dance (as Vladimir Nabokov wrote in Ada, before a catastrophic event) those tanks would cross that border. An ordinary toxic dose of radiation will not stop a tank––the driver will die in Paris, not in Fulda. The solution was the neutron bomb, which had more radioactive effect than blast effect. A much higher dose of neutron radiation will dump the histamine from all of the mast cells in the body, render the driver unconscious, and stop the tank at once. The question was how high? The DOD set up a committee to work on this problem, with representatives from both sides of the military-industrial complex, and me. The first meeting was in Fort Knox, the epicenter of the American tank corps. I got to drive an American tank, just like Michael Dukakis. It was fun. The second meeting was at Edgewood Arsenal. The Syrians had given the Israelis a number of Russian tanks during the Yom Kippur war, and the Israelis gave the Americans a few, in gratitude for their help. Because it is important that a tank have as small a profile as possible, the Russians designed their tanks for short people. I was the only member of the committee who could fit inside a Russian tank. I decided it was time to leave the DOD.

I went out on the job market, applying to a number of neurology departments. I also wrote a grant, using our first paper as preliminary results, and proposing to do the dual frontal-parietal attention experiments. I submitted the grant to the NIH and the National Science Foundation (NSF), delivering 1.5 cubic feet of grant applications to each place. The grant received a fundable score from the NSF, but it went to a behavioral sciences study section rather than to VisB at the NIH. The study section accused me of lèse majesté for arguing against the command neuron hypothesis, and disapproved the grant. That was the 1970s version of triage—if the NIH had all the money in the world, it would be better to drop it into the Potomac than fund Goldberg. Dr. Carl Kupfer was the first director of the NEI. He invited Bob Wurtz to become the chief of a new laboratory, the Laboratory of Sensorimotor Research. One of Bob’s first acts was to offer positions to Dave and me. I turned down very nice offers from the University of California, Irvine and the University of Michigan to join the LSR. Two pieces of paper crossed Carl’s desk the same day—one was a request from Bob to hire Goldberg. The other was a notice from a study section to disapprove Goldberg’s grant. Carl said he couldn’t hire me. Bob said that the grant went to the wrong study section and that Carl should send the grant to a few members of VisB—he sent it to Gerald Westheimer and Torsten Wiesel, both of whom loved the grant. Carl relented. I called the NSF and said that I was not going to use my grant. You don’t often hear real joy over the telephone. We rented space at AFRRI for a few years, but at least our SfN nametags said “LSR-NEI-NIH” and not “AFRRI.”

The LSR

Bob recruited Fred Miles from Ed Evarts’s lab, and Fred Miles’s postdoc Lance Optican as the next members of the LSR. Fred was recording from the cerebellum at that time and discovered that the Purkinje cell signal was unlikely to be permanently responsible for the gain changes of adaptation of the vestibuloocular reflex (VOR). His battle with Masao Ito rivaled mine with Vernon Mountcastle. Lance was an engineer who had gotten his PhD with David A. Robinson at Hopkins. Lance brought a quantitative and modeling sophistication to the LSR and true computer expertise. We hired Al Ziminsky as our first electronics technician, Art Hays as our computer engineer, George Creswell as our histologist, Chuck Crist as our machinist (later to found the Crist Instrument Company, purveyor of equipment for awake monkey neurophysiology to the world), and Nita Hite as our administrator. We were going into new space the NIH was creating in Building 10, the Clinical Center. The new wing was called the Ambulatory Care Research Facility, and the LSR was adjacent to the eye clinic. Someone in the NIH bureaucracy got worried about the proximity of monkeys and patients, and I had to create a list of hospitals that had monkey facilities in them, to assuage their fears. The great thing about the LSR was the community on the floor. We would brutally criticize each other’s manuscripts and ideas and stay friends. A few years later we moved again, into Building 49, the Silvio O. Conte building, dedicated specifically to neuroscience, with a large part dedicated to research on nonhuman primates.

The Frontal Eye Field

Charlie Bruce was my first postdoc at the LSR. He was unhappy that we had never found a saccade-related neuron in the FEF that didn’t have a visual response, so we developed the learned-saccade task. The monkey first did a number of trials in which the fixation point disappeared and a visual stimulus appeared at the same location. The monkey had to make a saccade to the stimulus. Then the fixation point went out and no visual stimulus appeared. The monkey had to make the same saccade, relying on its memory either of the stimulus location or of the prior movement, in total darkness. We found three different classes of neurons in the FEF—visual neurons, which had no presaccadic response; visuomovement cells, which responded to the visual stimulus in the fixation task and also had a presaccadic response; and movement cells, which had no response to the stimulus in the fixation task, but responded before the saccade in the learned-saccade task. The movement neurons did not discharge when the monkeys made spontaneous, non-task-related saccades of the same amplitude in total darkness. We also found cells that fired before learned saccades in one direction, usually contralateral, and after all saccades in the opposite direction (Bruce and Goldberg 1985). Finally, throughout the FEF, we found cells that discharged during fixation, but only after the monkey had acquired the target. We also found a few cells selective for smooth pursuit, a few cells that responded to auditory signals, and many postsaccadic cells that confirmed Emilio’s discovery. We also found evidence for a corollary discharge effect. A subclass of cells gave tonic responses to briefly flashed visual stimuli. The disappearance of the visual stimulus did not change the response of the cell. If the monkey made a saccade that brought the spatial location of the vanished stimulus out of the receptive field, the cells would stop firing. Most cells were tuned for direction, with a Gaussian tuning, but for distance with a log Gaussian.

David A. Robinson and Al Fuchs (1969) had discovered that electrical stimulation of the FEFs evoked saccades. Because we had discovered a number of different types of cells, we wanted to see whether the nature of the cells at the tip of the stimulating electrode affected the results of electrical stimulation. We discovered that we could evoke saccades at a threshold lower than 50 μA, even while the monkey fixated, for the most part only if the cells at the stimulating electrode were movement cells. When the cells at the recording electrode were visual or postsaccadic cells, the threshold for evoking saccades by electrical stimulation was much higher. The saccades evoked by electrical stimulation had the same direction and amplitude as the peak of the directional tuning curve of the neurons. Electrical stimulation at the site of pre-post cells evoked saccades in the presaccadic direction. There was an unusual map of saccades in the FEF. Saccade direction went from small saccades in the most posterolateral part of the medial bank of the arcuate sulcus, to large saccades in the most anteromedial parts. The direction of the first evoked saccade in a penetration at any given point was never predictable. The second electrically evoked saccade in a penetration rotated away from the first saccade in either an upward or downward direction. As the penetration grew deeper, the direction of the evoked saccades continued to rotate until they came close to the vertical meridian, at which point the rotation changed direction. We often found a cycle and a half of rotation. This point-to-line representation had previously been described in the cat suprasylvian cortex by Larry Palmer, Alan Rosenquist, and Ron Tusa (1978). The low-threshold area, which we always considered to be the real FEF, lay in the anterior bank of the arcuate sulcus. Pure movement cells were found only in this region, and the layer V pyramidal cells were particularly large here (Stanton et al. 1989). Now that we had a good idea of the location of the FEFs we were in a position to study their anatomical projections. Charlie Bruce and I made a number of anterograde tracer injections, and Greg Stanton worked out the cortical and subcortical projections of the FEF (Stanton et al. 1988a, 1988b; Stanton et al. 1989, 1993, 1995). The FEF projected to the superior colliculus, and to LIP, but not to the paramedian pontine and mesencephalic reticular formations that drive saccades.

Camp Goldberg

Debbie and I made an significant social discovery. Dave and I couldn’t pay Bill Keys’s salary for a while, and Debbie and I invited him to live in a spare bedroom. It turned out that we enjoyed having young people unrelated to us by blood living with us. We called them “house kids.” Over the years, we probably had more than a dozen house kids who lived with us for more than a year, most of whom are still important people in our lives. The house kids found us in various ways. One day one of our son Josh’s ex-girlfriends called to ask me if her friends, who were coming to DC, could stay with us while they found a place to stay. I said, “Sure.” She said that there was a problem, that they had a baby. I said that it was not a problem (Debbie was dubious). Holly and Michael arrived, red-headed 8-month-old baby in tow. They couldn’t find an inexpensive place to stay, but Debbie and I had fallen in love with the baby, named Canaan because her parents wanted a gender-nonspecific name. We asked them if they wanted to stay with us. They said there was a problem, that they had a very large dog. We had a pretty large dog ourselves, so it wasn’t a problem. They lived with us for two years. The baby, now 26, is like a daughter to us. I had a Howard Hughes Cloister Fellow, Alan Wu (now an associate professor of neurology at University of California, Los Angeles [UCLA]), working in my lab. Alan’s girlfriend Joyce was a medical student at NYU who had a friend who was coming to DC for a weekend. Alan asked us if he could stay with us for the weekend. Alan said that if Joyce’s friend stayed with us he would cook us a great Chinese meal. He did cook us a great Chinese meal. Three weeks later he wrote me, asking if he could come to DC and live with us. He wanted to learn how to live with his emotions on the surface. What he really wanted was an emotionally supportive place where he could come out of the closet. He lived for us for more than two years and became comfortable with his homosexuality. Having house kids was ultimately useful because my mother, who couldn’t live by herself, was moving in with us. We built an extra floor to the house. We had a shift of day care to take care of the two elderly women, whose ages by now were greater than their IQs, and having young people in the house to help us was good.

Camp Goldberg was a great party house. We had a swimming pool and hot tub, a great kitchen with a professional stove. We had all of the LSR parties, including the triennial party for friends who came from all over the world to the DC meeting of the SfN. There was a fishmonger who came to the NIH with great fish, and we would have an informal Friday night fish dinner almost every Friday. Years later we realized this was a Jewish Shabbat, and we still do it. We had a monster New Year’s Eve party every year, frequently with a pianist playing some classical music before midnight.

Spatial Accuracy

One of the great problems in psychology is to understand how the brain can generate a spatially accurate, stable representation of the visual world for action and perception, despite the fact that visual information only enters the world via the retina, and the retina is moving all the time. Herman von Helmholtz, inventor of the direct ophthalmoscope and Helmholtz Free Energy saw a patient who awoke with a paralysis of his lateral rectus muscle. He also had a macular hemorrhage in the other eye, so he relied on the now-paralyzed eye for vision. Every time he tried to move his eye laterally, he perceived the world to jump in the opposite direction, and slowly drift back. Helmholtz postulated that the brain achieved spatial stability by feeding back the plan of an intended movement to the visual system, to compensate for the shift of the visual world on the retina. Sir Charles Sherrington, having discovered the importance of muscle spindles in proprioception, suggested that the way the brain solved the problem of spatial accuracy was to measure where the eyes were in the orbit, and where the head was on the body, and to use those data to calculate where an object was in space.

The early models of the saccadic system used the position of the saccade target on the retina to calculate the saccade necessary to acquire the target (Young 1963). In a brilliant experiment, Hallett and Lightstone (1976) showed that the retinal location was inadequate for driving saccades. They found that human subjects made accurate saccades to targets that appeared and disappeared before an intervening saccade. This was a double-step task: If the subjects made the second saccade to the retinal location of the target, the saccade would be wrong, but they made their saccades to the spatial location of the vanished target. Hallett and Lightstone concluded, “This paper presents more evidence that saccades are towards the physical positions of targets—which is only possible if retinal image position and eye position information are correlated.” Larry Mays and Dave Sparks (1980) showed that if they asked a monkey to plan a saccade to a flashed target and then deranged the eye position by stimulating the superior colliculus, the saccade was accurate despite the dissonance between the retinal location of the target and the vector of the saccade need to acquire it. They, too, concluded that the brain constructed a model of target position in space. Finally, they showed that tonic visuomovement neurons in the colliculus, with sluggish visual and movement responses, discharged when the monkey made a saccade to a target that never appeared in the movement field or visual receptive field of the neuron (Mays and Sparks 1980). They called these neurons “quasi visual.” The target position in space seemed pretty clearly established as the targeting information for saccades. There was a plausible mechanism for establishing a representation of the target position in space. Richard Andersen and Vernon Mountcastle (1983) had demonstrated that the position of the eye in the orbit modulated the intensity of retinotopic visual responses in Area 7, the “gain fields,” and it was easy to calculate target position in head-centered coordinates from gain fields—using a three-layer neural net, in which a back-propagating network developed gain fields in its hidden layer (Zipser and Andersen 1988), or using the gain fields as basis functions (Pouget and Sejnowski 1997).

Charlie Bruce and I wondered how purely visual cells in the FEF would discharge in the double-step task. We found a type of cell that had absolutely no activity in the learned saccade task but that would discharge in the double-step task before the beginning of the first saccade, which was going to bring the spatial location of the vanished stimulus into the neuron’s receptive field. We realized that this was an example of Helmholtz’s theory—the motor system fed back a copy of the motor command to adjust the visual response, subtracting the vector of the first saccade from every point in the visual map and creating a coordinate transformation from a map centered on the original fovea to one whose origin was the first saccade target. This mechanism did not require an explicit computation of target position in space. The brain did not need to know where something was in absolute coordinates, it only had to know how to get there. We sent the paper off to the Journal of Neurophysiology: “Primate Frontal Eye Fields. III. Maintenance of a Spatially Accurate Saccade Signal by the Coordinate Transformation of the Visual Map” (1985). I have never had a more hostile review. One of the comments was “Target position in space is absolutely necessary!” (exclamation point the reviewer’s). The paper, submitted in 1985, was ultimately published in 1990 (Goldberg and Bruce 1990). The reviewers made us take the phrase “by the coordinate transformation of the visual map” out of the title. We at least were allowed to use the phrase in the discussion.

In 1986, Michelle Brouchon invited me to be a visiting professor in Marseille, at the Ecole des Hautes Etudes en Sciences Sociales, for six weeks. We were going to do some experiments on a patient of hers who was able to reach for objects close, but couldn’t throw a ball at an object far away. I was working with a superb graduate student, Jean-René Duhamel (now director of the Institute for Cognitive Neuroscience in Bron, France). I asked him if he wanted to do a postdoc in my lab. He was worried that he didn’t know any physiology. I reassured him that physiology is easy; creativity is hard. Carol Colby (now professor of neuroscience at the University of Pittsburgh and the Center for the Neural Basis of Behavior) arrived in the lab at around the same time from Charlie Gross’s lab at Princeton.

Carol had done a very nice anatomical study with Riccardo Gattass and Carl Olson, showing that a number of areas in the intraparietal sulcus project to area PO in the occipital-parietal sulcus (Colby et al. 1988). She was interested in exploring differences among the different areas in the lateral intraparietal sulcus. She and Jean-René showed that there a number of representations of the visual field in the intraparietal sulcus, each describing a different motor workspace, with its attending specific somatosensory input—the medial intraparietal area (MIP) described reaching space, the space explored with the arm. The lateral intraperietal (LIP) area described far space, the space explored with the eye (Colby et al. 1996). The ventral intraparietal (VIP) area at first didn’t make sense. The neurons in VIP were all motion selective—very much like middle temporal (MT) neurons (Colby et al. 1993). Then Jean-René and Carol discovered that many of the neurons in the VIP also had receptive fields on the face and were topographically mapped to the face, if you consider the mouth to be the fovea of the face (Duhamel 1998). Many VIP neurons were selective for objects near the monkey. These “nearness” neurons did not depend on retinal disparity for their estimation of nearness—they were near-selective even when one eye was occluded. Many would also respond to stimuli coming toward their tactile receptive fields on the face. We decided that VIP described the motor workspace of the mouth.

We then went back to the problem of spatial accuracy in LIP. Visual neurons in LIP gave the same sort of remapping responses in the double-step task as the ones in the FEF (Goldberg et al. 1990). The remapping seen in the double-step task might be a feature only of that task, however, a laboratory curiosity. We asked what happened when a monkey made a saccade that brought a visual stimulus outside the spatial location of its receptive field (the current receptive field) into its receptive field, without the monkey’s ever having to make a second saccade to the stimulus. Delightfully, about a third of the neurons responded to the stimulus in the spatial location that would enter the cell’s receptive field by virtue of the saccade (the future receptive field) before the saccade began. Remapping was a general feature of parietal function (Duhamel et al. 1992). The response required that the saccade bring the remapped target into the receptive field. If the monkey made the saccade without the target being present, or if we flashed the target when the monkey was fixating and not planning a saccade, the cell did not fire. We then asked whether visual memory remapped as well as constant visual stimulation. We flashed a target briefly outside the neuron’s receptive field and asked the monkey to make a saccade that brought the spatial location of the vanished stimulus into the receptive field. Neurons that did not show presaccadic remapping often fired after the saccade, showing that a memory trace of the spatial location persisted. Makoto Kusunoki (now a research scientist at the Medical Research Council Cognition and Brain Sciences Unit at the University of Cambridge), came from Hideo Sakata’s lab in Nihon University in Tokyo. He discovered that neurons became less responsive to stimuli in the current receptive field as they became responsive to stimuli in the future receptive field (Kusunoki and Goldberg 2003).

Jean-René and Ed Fitzgibbon (now chief of the Acuity Section at the LSR), a fully trained retinologist who had joined my lab after his ophthalmology residency and fellowship at the Cleveland Clinic, found a patient with a right frontoparietal lesion who was willing to participate in eye movement studies using the limbic ring eye coil. In this technique, invented by David A. Robinson (1963), the subject wears a contact device that fits on the sclera outside the cornea, with an embedded eye coil whose wire connects to an outside plug. The subject sits inside a device with two high-frequency orthogonal magnetic fields oscillating at different phases. An electric signal is evoked in the eye coil, from which the position of the eye in the space between the fields can be decoded. We now use the same system to record eye position in monkeys, implanting the coil subconjunctivally. I wore a limbic ring eye coil once or twice, and after a few minutes, I was willing to confess to heresy to get the thing removed, but our brave patient persisted. She had a field cut in the left visual field periphery, but her central vision was preserved. She had a bit of neglect for double simultaneous stimulus presentation. Her leftward saccades were a bit less accurate and had a 100 ms or so longer latency than her rightward saccades. This was true for 5° saccades across a 40° range of orbital positions, regardless of the spatial position of the target. We then asked her to do the double-step task, flashing two targets, one in the normal field and one in the affected field before the reaction time of the first saccade. When the target flashed in the right (normal) field and then in the left (affected) field, her first saccades were perfectly accurate, and her second saccades, into the left (affected) field were reasonably accurate, but not as good as single visually guided saccades into the affected field. When the target appeared first in the affected field, the patient made the usual slightly inaccurate, longer latency saccades, but then she was devastated. She could not make saccades to a target that appeared in the good field, in the direction of her normal saccades. She knew where the target was—about 30 percent of the time, she made saccades directly to the second target in the good field because of her neglect. We postulated that the deficit was a deficit of corollary discharge—she was unable to remap the location of the stimulus to the new fixation point. We published a single case report (Duhamel et al. 1992). I always thought that the single case report was the last refuge of the scoundrel, but Wolfgang Heide, in Lübeck, Germany, found the same deficit in a large number of parietal patients (Heide et al. 1995).

Mark Walker, a Howard Hughes Cloister Fellow in my lab (now associate professor of neurology at Case Western Reserve) and Ed Fitzgibbon showed that neurons in the intermediate layers, but not superficial layers, of the superior colliculus remapped, with both predictive remapping and memory-trace remapping (Walker et al. 1995). Marc Umeno (now the project manager for the VMware Cloud on Amazon Web Services) was a graduate student in experimental physics at American University. He convinced the Department of Physics that we did quantitative neurobiology, which could be considered biophysics. I suggested that he see whether the FEF had remapping as well. I showed him how to do the control experiments first (no response when the remapped target flashes while the monkey fixates; no response when the monkey makes the saccade without the remapping target being present) and then to look for remapping. The FEF exhibited remapping like LIP and the superior colliculus (Umeno and Goldberg 1997). Marc was extremely efficient, and unlike most of the other people at the LSR, he had a life. He was a nationally ranked bridge player and a member of the best ultimate Frisbee team in DC. He decided that doing the control experiments first was a waste of monkey time and water, so he ran the remapping experiments first and then did the controls only when he had found a cell that remapped. The saccade control stopped working. After a stimulus had appeared at a specific spatial location for a number of trials designed to demonstrate remapping, neurons that had not responded when the monkey made the remapping saccade without the target now responded, as if the brain had established a memory that lasted across trials. This intertrial memory was different from remapping. Some cells with intertrial memory didn’t remap. Some cells with remapping didn’t exhibit intertrial memory (Umeno and Goldberg 2001).

The strange thing about remapping was that it seemed to require that a remapping neuron have access to every part of the retina and that the corollary discharge from every possible saccade. Lance Optican, Christian Quaia, and I developed a model that explained how that could happen, with a lot of developmental pruning and Hebbian synapse strengthening. I was always unhappy about that model (Quaia et al. 1998).

Years later, I would return to modeling remapping. After I moved to Columbia, Mingsha Zhang (now professor of neuroscience at Beijing Normal University in China) came to the lab. He (and his wife Xiaolan Wang) were Chinese physicians who earned their PhDs at the Weizmann Institute of Science in Israel with Shabtai Barash. Xaiolan then went to work with Patricia Goldman-Rakic and Charlie Bruce at Yale, and Mingsha spent a few months with David Sparks in Houston, where he ran up against terrible bureaucratic problems and wasn’t allowed to touch a monkey. He asked to join my lab. He wondered whether during the remapping process, the receptive field expanded or merely went down at the current receptive field and up at the future receptive field, as Bob and Marc Sommer had shown for a few neurons in the FEF (Sommer and Wurtz 2006). He discovered that the receptive field expanded to encompass the entire part of the retina through which the saccade sweeps the receptive field, but not elsewhere. A student of his lab in Beijing, Shaobo Guan, tried to model this receptive field expansion and, again, I didn’t like the model. Mingsha, I, and his colleague at Beijing Normal University, Si Wu, struggled with this model in Beijing and New York. We finally came up with a model that evoked a cortical wave traveling from the cell whose receptive field included the future receptive field to the cell with the current receptive field. The model required the retinal signal only to drive the future receptive field cell and required the corollary discharge signal only to enable lateral connections among cortical neurons to create the cortical wave. We took advantage of the moving wave in the colliculus to provide the corollary discharge (Munoz et al. 1991). We wrote a paper that included the data and a model that included a one-dimensional retina, and one direction of saccade, and sent it off to Neuron. Reviewer 2 said that the model suggested that the latency of the intermediate location should be shorter, and the response intensity greater, than those of the ultimate remapping response. We analyzed the data and both of these suggestions turned out to be true. He also said that a one-dimensional, one-directional model was worthless. We needed a two-dimensional model that worked for all directions of saccades. Si, Mingsha, and I struggled with the two-dimensional, multisaccade-directional model, and we finally figured it out (Wang et al. 2016). This was the best review I had ever had in my life and should be the model for all reviews, constructive rather than destructive. A few years later, Roozbeh Kiani, assistant professor of neuroscience at NYU, told me that he was Reviewer 2. He should have been an author on the paper.

John Leigh and Ari Zivotofsky at Case Western (1996) had discovered a significant exception to the idea that corollary discharge and eye position are sufficient to determine target position in space. When you look at the moon on a cloudy night, and clouds pass over the moon, you think that the moon is moving in the opposite direction as the clouds. This is called the Duncker illusion. When human subjects pursue a single dot moving at right angles to a moving background, they think that the dot is moving diagonally away from the direction of the background motion and that their eyes move along the same trajectory as the dot.²

In fact, their eyes follow the actual trajectory of the dot. If they try to make a memory-guided saccade to a target that flashes early during the pursuit, the saccade is inaccurate, as if the subjects adjusted their eye position for the pursuit trajectory that they thought they followed, rather than the one they actually followed. They would make this mistake even though they presumably had an accurate corollary discharge of the pursuit movement, and an accurate eye position signal. Ari came to the LSR to work with Fred Miles and asked to join my group to solve the puzzle of how the Duncker illusion fools the brain. Ari and Keith Powell (now working for Teva Pharmaceuticals), from Barry Peterson’s lab at Northwestern, showed that monkeys report the Duncker illusion (Zivotofsky et al. 2005). Years later, Naoko Inaba (now an assistant professor at Sapporo University) came to my lab from Kenji Kawano’s lab in Kyoto to study the cortical responses during Duncker pursuit. She showed that pursuit neurons in the middle superior temporal (MST-l) area but not the MT area are tuned for perceived rather than actual pursuit. We presented this at the SfN and are writing it up.

Music and Theater

We did a lot of music. I was still playing the piano, and Debbie the flute. We mangled sonatas by Bach and Poulenc, and our kids grew up listening to classical music. Jon, age five, with a 60 db flat hearing loss said he wanted to play the violin. We got him an eighth-sized violin, and it soon became apparent that he was very good at it. I installed a smoke detector and tested it. Josh asked “What’s that?” Jon said, “a G.” We ran down to the piano, and he was right. One night a friend came over and we hacked our way through a Beethoven cello sonata. Jon sat at the foot of the cellist, entranced. He asked if we had the records and the book. I said that we did. For the next three weeks Jon listened to the Beethoven cello sonatas full time and kept asking us where it was in the score. Soon he stopped asking. He had decoded bass, tenor, and treble clefs. He then went on to the Beethoven violin sonatas and never asked where he was. I loved going to concerts with him. He always brought the scores. Public television did a broadcast of Don Giovanni. He was outraged that Joan Sutherland sang “Or sai chi l’onore” transposed down a full tone. We bought a fairly new Steinway L because we couldn’t tune our old piano adequately. We played a lot of Baroque trios with Jon. Josh, not a musician himself, had an acute ear for music, and dragged me into 1970s minimalism. I learned not to be bored by Phillip Glass, Steve Reich, and Terry Riley. Jon stopped playing the violin in college, but was a rock dj at WHRB, the Harvard radio station. After college, he did odd computer jobs and ultimately became an Orthodox Jew. After a few years in Israel, he decided to go to law school at Penn, where he made the Law Review, and clerked for a federal district court judge. He was, however, not cut out for the corporate law life.

Josh inherited the theater gene. He was the star of his high school plays, and we had Josh’s high school cast parties in our house. He put on a production of David Mamet’s Sexual Perversity in Chicago in our livingroom. At Hampshire College, he studied directing and lighting design. After a time in New York doing off-off Broadway lighting and directing plays on the Fringe, he became disillusioned with the political world of New York theater. He got a master’s degree at the NYU’s School of Interactive Telecommunications and became a computer-based light artist, specializing in motion-driven environmental lighting and museum displays. He does lights and video for an occasional off-off Broadway play and is a video jockey at an occasional club gig.

Visual Attention

All of our experiments had been done looking at the effect of flashed or moving stimuli on neurons in various parts of the brain. It struck me that in the real world most objects are stable, and they enter the receptive fields of neurons because of eye movements. The assumption had been that flashing a target in the receptive field was not terribly different from the target’s entering the receptive field by way of a saccade. Jackie Gottlieb (now a professor of neuroscience at Columbia) joined the lab. She had worked on the FEF’s role in smooth pursuit as a graduate student at Yale with Charlie Bruce. She joined Makoto, who had to return soon to Japan, to work on the project. We designed the stable target task to test the assumption.

In this task, an array of circular objects stayed on the screen all the time. When the monkey was fixating the center of the array, one of the objects would be in the cell’s receptive field. The monkey made saccades that brought that stable object into and out of a neuron’s receptive field. If the monkey made a saccade that brought a behaviorally irrelevant, stable stimulus into the receptive field of a neuron, its response was very weak. We then took advantage of the fact that the abrupt onset of a visual stimulus grabs attention (Yantis and Jonides 1990). The weak response of the neuron could have been because stable, task-irrelevant objects do not evoke much of a response, or it could have been that making a saccade to bring a stimulus into the receptive field damps down the response. To distinguish between these two possibilities, we made a hole in the array at the spatial location that would be brought into the receptive field of the saccade. We flashed the stimulus in the hole and asked the monkey to make the saccade that would bring the recently flashed stimulus into the receptive field. The neuron fired as if the stimulus had just flashed in its receptive field. The low response evoked by stable targets was due to their intrinsic lack of interest to the monkey, not to the saccade. We also could make the neurons respond intensely to one of the stable objects by cuing the monkey to make a subsequent saccade to the object. In this case, the response became enhanced as soon as the monkey made the first saccade that brought the cued target into the neuron’s receptive field, but not when the monkey had been cued to make a saccade to another target (Gottlieb et al. 1998). These experiments showed that most of the visual world is barely represented in LIP. LIP represents only objects that are behaviorally important, by virtue of top-down priority or bottom-up salience.

James Bisley (now associate professor of neuroscience at UCLA), who had gotten his PhD in Melbourne under Tony Goodwin, was working in Tanya Pasternak’s lab on memory for motion in monkeys. His fiancée Andrea had gotten a postdoc in Baltimore, so he decided to move to Maryland and joined my lab. The debate about whether LIP was primarily involved in attention or saccade planning was still raging, and James and I decided to return to the fray. I had spent a lot of time studying attention, but I used a rather weak, ad hoc definition of attention: If the monkey responded to a stimulus, then it had, at some time, paid attention to that stimulus. Williams James had pointed out that attention increased perceptual efficiency and shortened reaction time. We knew that the abrupt onset of a task-irrelevant visual stimulus lowered humans’ perceptual threshold at the spatial location of the stimulus (Yantis and Jonides 1990). Heiner Deubel (1996) and Eileen Kowler (1995) used perceptual threshold to show that planning a saccade focused attention at the goal of the saccade.

We used perceptual threshold to understand the determinants of a monkey’s attention in a very complicated task. Monkeys first had to plan a memory-guided saccade to a point in space. On any given day, the saccade target could appear at one of four places: one in each quadrant of the visual field, symmetrical across the horizontal, or the vertical meridians. On each trial, a go–no go probe would appear for one video frame during the delay period (800, 1,300, or 1,800 ms) after the saccade target had appeared, while the monkey was planning the saccade. The go–no go probe consisted of three circles and a capital C. Each object appeared at one of the four potential saccade target locations. The monkey had to discriminate the orientation of the C to determine whether actually to make the saccade or to hold fixation after the fixation point disappeared. We varied the contrast of the probe to determine the monkeys’ perceptual threshold and found that planning a saccade to a location lowered the contrast threshold for detecting the orientation at that location. This enabled us to assume that the monkey was attending to the spatial location with the selectively lowered perceptual threshold. On half of the trials, we also flashed a distractor, identical to the saccade target, 500 ms after the saccade target appeared. We found that 200 ms after the distractor appeared, the locus of attention left the saccade and moved to the distractor location. By 700 ms after the distractor appeared, the locus of attention returned to the saccade goal. We then recorded the activity of LIP neurons in this task and placed either the distractor or the saccade goal in the neurons’ receptive field. The response to the saccade target had a large transient, and then a sustained, lower but significant level of activity during the delay period. The response to the distractor had the same large transient, but it rapidly fell beneath the level of the delay period activity evoked by the saccade plan. For about 90 ms, the “window of neuronal ambiguity,” there was no significant difference between the activity evoked by the saccade plan and that evoked by the distractor.

We then studied the monkeys’ perception when the go–no go probe appeared at the center of the neuronal window of ambiguity. We had expected both sites to be somewhat attentionally advantaged, but instead, the monkeys had no attentional advantage at either site. This was a paradoxical result. It is generally assumed that attention is divisible and graded. Our result showed that attention as measured by perceptual threshold is binary and indivisible. We wondered whether attention were quantized, with a shuttle that moves the quanta so rapidly that only very short stimulus presentations can unmask it. Different monkeys had different neuronal windows of ambiguity. Each monkey had no attentional advantage during his own window of neuronal ambiguity, but had an attentional advantage during the other monkey’s window of neuronal ambiguity (Bisley and Goldberg 2003). The activity of neurons in LIP tracked the monkey’s locus of attention, regardless of what evoked that attention.

We then looked at the response of LIP to the probe stimulus. There was no difference between the response to the circle distractor in the receptive field and the response to the go probe. The no-go probe evoked a greater response than either. These results had some interesting implications. The first was that activity during the delayed saccade task can determine the monkey’s locus of attention as well as its saccade plan. The second was that we could not determine the monkey’s locus of attention by looking at the activity at one locus on the visual map in LIP. Attention is determined by the emergence of a statistical peak on the map—activity that can sustain attention during the delayed saccade task can no longer do it when the response to a task-irrelevant distractor becomes the peak. The third is that when a probe appears for a single video frame, attention is not determined by the response to the probe but by whether the peak of the map is at the probe location when the probe appears. The fourth is that because LIP responds more intensely to a probe that cancels a saccade plan than to a probe that sustains it, it is unlikely that LIP by itself is driving saccades. We concluded that LIP integrates top-down signals like a saccade plan and bottom-up signals like the transient visual response to an abruptly appearing, task-irrelevant stimulus, to create a priority map of the visual field. The visual system pins attention to the peak of the priority map. The oculomotor system drives saccades to the peak of the priority map when saccades are appropriate.

Although James and I did the recording and psychophysics in the LSR, we wrote the paper at Columbia. The center of the window of neuronal ambiguity for a given neuron was the time at which the decay of the visual transient crossed the delay period level evoked by the saccade plan. For the majority of the neurons, this crossing point occurred within a 40 ms interval. We wanted to know whether this were a membrane phenomenon or a network phenomenon. We took our data to Ken Miller, in the new Columbia Neurotheory Center, and posed the question to him. He and his postdoc Suriya Ganguli came up with a delightful solution: a network model in which generically high-dimensional firing-rate vectors rapidly decay to a single mode. The model predicted that slowly varying activity patterns, like the delay period activity, are proportional to spontaneous activity, which turned out to be true (Ganguli et al. 2008).

Prefrontal Cortex

Rolf Boch came to my lab from Burkhardt Fischer’s lab in Freiburg. He and Burkhardt had discovered express saccades (Fischer and Boch 1983). They also studied prestriate area V4 (they called it the “prelunate gyrus”) in an overlap task, where the monkey fixates, a saccade target appears; a second or so later, when the fixation point goes out, the monkey makes the saccade. Neurons in V4 show an enhanced response to the saccade target (relative to the response to the same stimulus in a fixation task) and also a presaccadic reactivation (Fischer and Boch 1980). Rolf wanted to know whether we would see the same thing in the prefrontal cortex. We did—some cells showed enhancement of the visual transient, others showed presaccadic reactivation, and some showed both (Boch and Goldberg 1989). I didn’t know what this meant. Rolf was a wonderful artist, and when he returned to Germany, he decided to support himself and his family by teaching physics in a technical school and doing art.

I left the prefrontal cortex alone until Ryohei Hasegawa (now group leader of the Neurotechnology Group at the Tsukuba Electrotechnical Institute in Tsukuba, Japan) came to my lab from Aki Mikami’s lab in the Primate Research Institute of Kyoto University, in the little town of Inuyama. Michael Petrides and Brenda Milner had developed the self-ordered task as a way to study nonspatial memory (Petrides and Milner 1982), and Michael had shown that monkeys with lesions in middorsolateral prefrontal cortex were impaired on the task (Petrides 1995). Ryo; Ari Blitz, a Howard Hughes Cloister Fellow (now assistant professor of neuroradiology at Johns Hopkins); and I trained monkeys to do a saccadic self-ordered task. In this task, the monkey fixated a central fixation point, and then three of six possible objects appeared equidistant from the fovea and spaced 120° apart. The monkey made a saccade to one, his choice, and got a small reward. The objects reappeared, at shuffled spatial locations, and the monkey had to make a saccade to either of the two objects to which he had not previously made a saccade, for which he got a larger reward. The objects reappeared a third time, again shuffled spatially, and the monkey had to make a saccade to the remaining object to which he previously had not made a saccade, for which he got an even larger reward. We had hoped that we would find neurons that were selective for remembering a specific target. We didn’t. Instead the neurons increased their activity from the first to the second to the third saccade. The activity was not an increasing reward signal. If we merely increased the reward in the context of a simple saccade task, we didn’t see the responses increase. Most of the monkeys’ errors were on the third trial. There was no increase in activity between the second and third trials on third-trial errors (Hasegawa et al. 2004). We also noticed that the baseline activity of the neurons, during the fixation period of the first trial, predicted how the monkey was going to do on the third trial several sets in the future, or how it had done on the third trial several sets in the past—but rarely if ever what was going to happen on the current set of trials (Hasegawa et al. 2000).

Barry Peterson, professor of physiology at Northwestern, came to the lab for a sabbatical. One of the hallmarks of patients with frontal cortex lesions is the inability to suppress stimulus-bound behaviors. They have difficulty performing Dan Guitton’s antisaccade task, in which they have to look away from a visual stimulus (Guitton et al. 1985). Barry and Ryo decided to see whether the FEF and its adjacent prefrontal cortex had neurons that responded selectively to targets to which the monkey was not allowed to respond. They designed a spatial nonmatch to a sample task, in which a stimulus flashed and disappeared, and then after a delay, the original stimulus and another stimulus appeared. Depending on the color of the fixation point, the monkey had to make a saccade either to the original stimulus or to the new stimulus. Visually responsive neurons in the FEF and the prefrontal eye field were often selective to the stimulus to which the monkey did not make the saccade (Hasegawa, Peterson et al. 2004). This experiment shows that the frontal cortex has a direct role in suppressing unwanted stimulus-bound behaviors, rather than only an indirect role through the basal ganglia.

Saccadic Adaptation

S. C. McLaughlin (McLaughlin 1967) invented saccadic adaptation as a tool to look at plasticity. Subjects make a saccade to a visual target, and during the saccade, the stimulus consistently moves to a new location toward or away from the target. Gradually, humans and monkeys change the amplitude of their saccade, so the eye moves to where the target ends up, not to where it begins. Separating the amplitude of the saccade from the location of the stimulus enabled us to see whether a neuronal signal described the stimulus or the movement. Mark Segraves (now professor of neuroscience at Northwestern) came to the lab from Alan Rosenquist’s lab at Penn, and after graduation, did a year with Giorgio Innocenti in Lausanne. He and Ed FitzGibbon decided to train monkeys on the task and record from the colliculus. We discovered that visual and movement neurons in the colliculus signaled the target location and not the actual movement (FitzGibbon et al. 1986). We assumed that some downstream center, probably the cerebellum, adjusted the saccadic amplitude to compensate for the adaptive process. However, electrical stimulation of the colliculus failed to produce the adapted saccade, which should have happened if the adaptation occurred downstream. Jay Edelman (now professor of biology at the CCNY–CUNY) came to my lab from Ed Keller’s lab to study saccadic adaptation. He showed that electrical stimulation at high currents did indeed produce the unadapted saccade, but stimulation at lower currents produced the adapted saccade (Edelman and Goldberg 2002), confirming that the change in the saccadic amplitude occurred after the colliculus.

After I arrived at Columbia, Matt Phillips (now staff research engineer at Kitware, a computer consulting company) who had been a postdoc with Jay Edelman at CCNY, and Sara Steenrod (now a science editor at Washington University of St. Louis), a graduate student who had spent time as a technician in Barry Richmond’s lab at the NIH, studied saccadic adaptation in LIP, using a memory-guided delayed saccade task. They showed that visual transient signals, delay period activity, and the presaccadic burst all described the location of the saccade target, and not the amplitude of the actual saccade (Steenrod et al. 2013).

Columbia

I loved the LSR. I had great colleagues and wonderful support. I didn’t have to write grants except occasionally to support a postdoctoral fellow. We had Jim Raber, probably the world’s best primate veterinarian, and Nick Nichols and Tom Ruffner, spectacularly good machinists. John McClurkin and Art Hayes were great computer guys. I had wonderful colleagues not only in the LSR but also in the Laboratory of Neuropsychology of the NIMH, a flight down from the LSR in Building 49: Mort Mishkin, Leslie Ungerleider, Bob Desimone, Barry Richmond, and Betsy Murray. Bob Wurtz, although no longer lab chief, still shielded us from the NIH bureaucracy. There were some downsides. The NIH had little teaching, no formal way to have graduate students. I didn’t have a real role in the Neurology Department at Georgetown and making rounds required a lot of commuting time. I missed New York. The Metropolitan Opera is much better than the Washington National Opera.

Eric Kandel had convinced David and Hillie Mahoney to donate enough money to build the Mahoney Center for Brain and Behavior Research. Columbia and the New York State Psychiatric Institute (NYSPI) were going to renovate the whole fifth floor of the NYSPI for a center dedicated to systems neuroscience, concentrating on neural recording in awake monkeys. Eric had just recruited Jackie Gottlieb as a tenure-track assistant professor. Vince Ferrera and Ning Qian were already there. Eric realized that he needed a senior scientist to head the center. He asked me to come up and look at the position. I gave a seminar for the Center of Neurobiology Behavior on the parietal cortex and ran a session of the neurology department’s morning report. The residents always present the case as a mystery for the professor to solve. Luckily, it was a case of methotrexate-induced white matter disease, a syndrome I had recently seen and could discuss. Eric offered me the job, and Tim Pedley, then chair of the Neurology Department, asked me to join the Neurology Department as well and attend in the clinic. The NEI asked me what would induce me to stay. I said new young colleagues. We hired Bruce Cumming from Oxford (now the lab chief of the LSR) and Kirk Thompson from Vanderbilt. I dithered for a long time and Columbia improved the offer—I would be the David Mahoney Professor of Brain and Behavior Research, and also have a state salary at the NYSPI, an apartment with rent at half the market rate, and even a parking space. Finally, Debbie announced that we were going to New York. After I had agreed to go to Columbia, but while I was still working at the LSR, I recruited Daniel Salzman from Bill Newsome’s lab and Aniruddha Das from Charles Gilbert’s lab to the Mahoney Center. Columbia found Debbie a job in the Department of Medicine.

We sold Camp Goldberg in DC on my 60th birthday, and because our apartment in New York was not going to be available for a month, we were actually homeless. Josh asked us if we would like to go to Burning Man, a somewhat-notorious alternative libertarian arts festival in the Nevada desert. It is an honor to play with your children, so we decided to do it. Because there are no spectators at Burning Man, only participants, we signed on as medical volunteers, doing first aid. One of my first patients asked me whether she could take ecstasy even though she was on Coumadin, an anticoagulant, because she had Leiden factor V, a cause of pulmonary emboli in young people. I said that I didn’t know; therefore, no. Debbie said someone should do a study. We saw a lot of dehydration in the desert, and caffeine-withdrawal migraine headaches. We got hooked on Burning Man and went back another nine times. We became the unofficial den mother and father for chunks of the New York Burning Man community.

Life in New York

Debbie and I finally arrived in New York at 12:15 A.M. on September 11, 2001. The next morning, we were running north in Riverside Park, and a friend called us and told us to turn around. We could see the smoke of the buildings, which had not yet collapsed. We went over to the nearby Red Cross and asked if we could do anything. They decided that we could be a mental health unit and sent us down in a Red Cross van to the foot of the Manhattan Bridge to help people who might be upset. The subway had shut down, and thousands of people dressed in air-conditioning business clothes were walking from Manhattan to Brooklyn across the bridge. It was a hot, sunny day, and we realized that although some few people might need someone to talk to, our Burning Man desert experience told us that everyone needed water. Luckily, the Red Cross van had a large number of paper cups and water dispensers, and the Popeye’s across the street from the bridge had water. We hydrated thousands of people. Around six o’clock the foot traffic had ended, and the cops asked us if we wanted to go to St. Vincent’s hospital to see whether we could help. There was nothing to help—people were either in good shape or dead. We walked up Broadway from 14th Street to 73rd Street, where we were staying with friends, because Columbia had not yet finished our apartment. The only cars in Times Square were police cars and press cars. We were the only pedestrians.

In November, we finally moved into our Columbia apartment, in the Columbia professorial ghetto, across the street from Barnard. The apartment is immense, with a large formal space of dining room, livingroom, and library in the front and a warren of small bedrooms in the back, separated by a very large (for New York) kitchen that we had the Columbia Real Estate people make out of two small rooms. Living in an apartment with a great staff made me realize how stressful maintaining a large house is. I will never make another midnight trip to Home Depot. Because most of the people on the street are faculty members, we know more of our neighbors than we did in DC. Seventeen years later, New York is still breathtaking. Josh and his family live two miles away. Tuesday is grandparent night. Debbie works as an internal medicine hospitalist in a rehab facility owned by Mount Sinai. She walks to work.

New York is heaven for classical music and theater. We see half of the productions at the Metropolitan Opera, lots of off-off Broadway theater, and lots of other music. The building has two apartments per floor, and for a year, we shared the landing with Menachem Zur, an Israeli composer. His son Yonah was a freelance musician in New York. Yonah’s quartet had a grant to study the Brahms clarinet quintet with the Emerson quartet, and they practiced it in our livingroom. They did a house concert for us and we invited friends. More and more, professional freelance musicians would rehearse in our livingroom. They would give house concerts if they wanted to try out a concert in front of a live audience—to get the adrenaline running for a real concert they would be giving in the following week at a real concert venue. We now have about 20 house concerts a year. A piano concert tried out in our livingroom was listed by the music critic of the New York Times among the 10 best concerts of 2014 when the pianist, Benji Hochman, performed it for real a week later. Many of the musicians have become personal friends, coming to dinner on Friday nights, meeting Burners, neurologists, neuroscientists, and old college friends. I grew old and arthritic, and I rarely play the piano myself any more. We maintain the Steinway for our friends.

Visual Search

When we moved to New York, the Mahoney Center labs were not yet finished. I kept my lab at the NIH and commuted to DC for a few days every week. When the labs were finished, I decided to make the atmosphere of the Mahoney Center like the LSR. Every door on the floor has the same key. We shared a single administrator, Latoya Palmer (now very high up in the administration of Cornell Medical School), and a computer hardware and software technician, Lloyd Kim. Columbia had a machine shop, but it took a long time to get anything done. I wrote an R24 grant to provide us with our own machinist, now replaced by an NEI core grant. We destroy each other’s manuscripts at pizza and potshots sessions.

When the labs were finished, James Bisley and Anna Ipata came to Columbia with me. Anna had done pediatric neurology in Pisa, and then got a PhD with Leo Chelazzi and Giovanni Berlucchi in Verona. She was an American citizen because she was born while her father, a biochemist, was doing a postdoc at the NIH. Angela Gee, who had been an undergraduate working with Gerald Westheimer at University of California, Berkley joined the lab at her mentor’s suggestion. Angela had the makings of a great scientist, but she decided instead to spend her life teaching neuroscience to underprivileged students. She is now a professor at Los Angeles Trade and Technical College, where she gets ecstatic student ratings.

We realized that the great bulk of my experiments had been done in paradigms in which the monkey made eye movements to earn a reward. In the real world, however, eye movements are made to facilitate visual perception, and there is no such thing as a wrong eye movement. With Jackie Gottlieb, we designed a visual search task in which the monkey had to search for a capital T among an array of lower case t’s and then tell us, with a hand movement, whether the capital T was upright or inverted. The monkey was free to move its eyes. On most of the trials, the target and distractor were all black, but on some trials, either a distractor or the target was bright green. The monkeys in the Goldberg lab behaved like the humans in the Treisman lab. There was a clear effect of the number of objects in the array on reaction time when there was no popout, but there was no effect when the target popped out. A single popout distractor lengthened the monkey’s reaction time. We recorded from LIP in the search task. We realized that we wanted to study what happened when the monkey made saccades away from the target, so having established the effect of a popout target on reaction time, we never had the target pop out during recording. We found that the monkey was able to make fewer saccades to the popout distractor than to the black distractors and that activity evoked by a popout distractor was less than that evoked by a nonpopout distractor (Ipata et al. 2006).

I had spent a lot of time and energy on showing that parietal activity could be dissociated from saccade planning. In our visual search task, the monkey adopted the strategy of making many rapid saccades, some of which could be to distractors, rather than making sure it was going to make a saccade to the target. These short reaction times were opposed to those in tasks in which the monkey did not get a reward if it made the wrong saccade, like Jeff Schall’s popout search task (Schall and Hanes 1993). We found that activity in LIP correlated with the monkey’s saccadic reaction time. LIP was not entirely dissociated from saccade planning (Ipata et al. 2006). Luckily, LIP gave an enhanced response to the target as compared to the distractor even when the monkey made a saccade to the visual hemifield opposite the target. We showed that in visual search LIP had three different signals: an undifferentiated (“dumb”) visual response to the abrupt appearance of the search array; a presaccadic signal; and a cognitive, feature attention signal. The cognitive signal was present even when the monkey made a saccade to the target.

We used linear summation to model the waveform evoked when the monkey made a saccade to the target using the waveforms evoked when the monkey made saccade to a distractor or a target in the receptive field and when the monkey made a saccade away from a distractor in the receptive field (Ipata et al. 2009). Although spikes might be generated from motor or sensory inputs, they lose their input identity. Recipient areas do not know the source of the spikes. The visual system will pin attention to the peak of the LIP priority map whether that peak arises from delay-period activity during a memory-guided delayed saccade task or from the response to the abrupt onset of a visual target. The oculomotor system will drive saccades to the peak of the map, when appropriate, even when the input to the map was entirely visual. We wrote a review called “On the Agnosticism of Spikes” (Gee et al. 2007).

The question then arose whether LIP demonstrated the nonsaccadic signals when the monkey did a visual search task without moving its eyes. Mingsha trained two monkeys on the task. LIP did demonstrate the dumb visual, presaccadic, and cognitive signals. The fascinating result was in the baseline. The task began with the monkey fixating for 500 ms, after which the search array appeared. If the fixation point went out, the monkey was free to move its eyes and make saccades until it found the target. If the fixation point stayed on, the monkey had to solve the search task without moving its eyes. The fixation task was harder—the monkey got the correct answer around 70 percent of the time, as opposed to nearly 100 percent when it could make a saccade to the target. The baseline activity, while the monkey was fixating, predicted the monkey’s likelihood of success on the fixation task as well as the intensity of the visual transient response to the appearance of the array. The baseline, and the monkey’s likelihood of success, correlated inversely with a recency-weighted measure of the monkey’s past performance.

The problem with the original experiment was that we did not know where the monkey was attending during the fixation period. We added a 50 percent valid cue during the fixation period. The monkeys pinned their attention to the cue location, as measured by manual or saccadic reaction times, but the baseline predicted success even when neither the cue nor the target was in the neuron’s receptive field. This was an arousal effect, not an attentional effect (Zhang et al. 2014). A key feature of attention is its spatial or feature selectivity—the baseline effect was not at all spatially selective. We postulated that the baseline effect was due to some ascending modulatory pathway that affected LIP neurons outside the traditional sensorimotor pathways.

Having discovered that the baseline activity in LIP predicted the probability of the monkey’s success on a difficult task, as well as its memory of prior reward, we postulated that this nontuned signal resulted from an ascending modulatory system. Our first candidate was the cholinergic system. We decided to see whether iontophoresis of acetylcholine affects the neuronal responses and behavior. Mingsha and Xiaolan got iontophoresis working. To do so, Xiaolan puts a tungsten electrode down the center of a seven-barrel micropipette and fills the surrounding barrels with various chemicals. She has learned not to let me within six feet of a filled pipette. I feel uncomfortable having something done in my lab that I can’t do. We are finding that acetylcholine increases the baseline and visual transient responses. Mecamylamine, a nicotinic antagonist, and scopolamine, a muscarinic antagonist, decrease both signals. Iontophoresing acetylcholine actually increases the monkey’s performance on the difficult task, but mecamylamine and scopolamine do not (yet).

Oculomotor Proprioception

Although the visual responsiveness of neurons in LIP and many other parts of the brain is modulated by the position of the eye in the orbit, no one had demonstrated the source of that modulation. Andersen and Mountcastle had postulated that it came from a corollary discharge (Andersen and Mountcastle 1983), but no one had demonstrated a cortical eye position signal that preceded the fixation regardless of the saccade made to the location. I wondered whether the signal came from oculomotor proprioception. For years, I suggested to a number of now-successful postdoc candidates that maybe they would like to work on oculomotor proprioception in somatosensory cortex, and they all took postdocs elsewhere. Finally, Xiaolan Wang agreed to look for it. She was working in Charlie Bruce’s lab at Yale, but Charlie lost his funding, and she had to go elsewhere. Her husband was working in my lab, and the mere fact that the proposed project was insane was not a barrier. Xiaolan found the oculomotor proprioceptive area, deep in the central sulcus, in Brodman’s Area 3a, where the projection from skeletal muscle spindles lies. The cells had monotonically increasing responses with eccentric eye position starting around the center of gaze. The cells had a phasic and then a tonic response after a saccade. Cells in a given hemisphere were tuned for all directions in the orbit, not merely the contralateral direction. Activity came from the contralateral orbit: If we did a retrobulbar block, the activity disappeared, and it came back when the monkey recovered from the block. Because the other eye continued to move, we assumed that all of the corollary discharges were intact, and therefore this was a proprioceptive signal (Wang et al. 2007).

Yixing Xu (now assistant professor of ophthalmology at the University of Southern California) joined the lab as an MD-PhD student. He had bachelor’s degree and a master of science in biomedical engineering from Yale. Yixing was a wonderful violinist. He could have been a world-class concert violinist but decided to go into academic medicine instead. While he was in my lab, he was also the concertmaster of the Camerata Orchestra, a semipro orchestra in New York. After years of frustration, he decided that Yixing was too difficult a name for Anglophones to pronounce, and so he added the first name “Benjamin.” Ben, Xiaolan, and Chris Peck, a graduate student rotator, found that the proprioceptive signal lagged the eye by an average of 60 ms during both smooth pursuit and the VOR. Activity in pursuit and the VOR correlated perfectly, showing that there was no visual input to the signal: The retinal image was stable in the VOR, even though the eyes moved in the head but changed with the pursuit movement (Xu et al. 2011). Carine Karachi, a fully trained neurosurgeon from the Salpetrière in Paris, joined Ben.

The eye position signal was slow to develop, but was it too slow to provide a spatially accurate signal in the double-step task? To answer this question, Ben and Carine asked what happened to eye position modulation after the monkey made a saccade. They trained monkeys to make memory-guided delayed saccades and double-step saccades soon after the monkeys made a first saccade, which we called the conditioning saccade. For 50 ms and 150 ms after the conditioning saccade, two thirds of the neurons gave visual responses modulated by the position of the starting point of the conditioning saccade, and the other third gave visual responses unpredictable from the steady-state eye-position modulation of the neurons. At 250 ms after the conditioning saccade, the eye-position modulation became accurate. If the monkey solved the double-step saccade using gain fields, a double-step saccade performed 50 ms after a conditioning saccade should result in the second saccade being made to the spatial location of the receptive field before the monkey made the conditioning saccade (which is what the gain fields would calculate), rather than to the spatial location of the receptive field after the conditioning saccade (Xu et al. 2012). At 50 ms after a conditioning saccade, the monkeys made accurate double-step saccades even though the gain fields were wrong. The brain uses corollary discharge, and not gain fields, to solve the short-latency double-step task.

Linus Sun is a Columbia-trained neurologist who earned a PhD at MIT with Matt Wilson before he went to medical school. Linus came to my lab under a resident research R25 grant. He then won a K08 mentored award to work on gain fields. Steve Lomber came down from Canada to put a cooling probe in the oculomotor proprioceptive part of Area 3a. Linus found that cooling the proprioceptive region of Area 3a reduces or eliminates the gain fields. With luck, that story will be published before this memoir. Mary Hayhoe had discovered incontrovertible evidence for the presence of a craniotopic representation: If a human makes a number of saccades and then makes a memory-guided saccade, the error of the memory-guided saccade does not increase as much with the number of saccades as one would expect from multiple remappings. Martina Poletti (Poletti et al. 2013) showed that spatially accurate memory can be modeled as a remapping process dominating early but as a craniotopic process dominating after a number of saccades. We hypothesized that the latter craniotopic process requires gain fields to establish the longer-term memory. Linus and my technician, Zikang Zhang (Mingsha’s and Xiaolan’s son) trained a monkey to make a memory-guided saccade after a number of intervening visually guided saccades. The monkey had no trouble making the memory-guided saccade after the first few saccades, but failed after five or nine saccades when the target was in the contralateral but not the ipsilateral field. Zikang presented a poster on this at the recent Gordon Conference on Eye Movements. The idea that long-term visuospatial memory is dependent on oculomotor proprioception makes people giggle when I tell them about it.

Further evidence for craniotopic processing in the parietal cortex comes from studying environmental memory in LIP. Mulugeta Semework Abebe came to my lab after a PhD in brain-machine interface studies at SUNY Downstate. He came to America from Ethiopia and studied in Israel and Georgia. Before she left the lab, Sarah Steenrod had discovered intertrial memory in LIP, and in one monkey, she showed that she could evoke that memory by stimulating a spatial location without ever stimulating the cell’s receptive field. This suggested that LIP has access to a craniotopic memory, although we could not find an explicit representation of it. Mulugeta finished the study on second monkey, and we have submitted the manuscript. The question then arose what was the source of this craniotopic memory? We postulated that it might come from the medial temporal lobe. The parahippocampal gyrus projects to LIP. Mulugeta is now exploring the medial temporal lobe. He has found cells exhibiting spatial memory, and an interesting class of cells responding to visual stimuli all over both hemifields except for a small ring around the fovea.

Sharpening the Priority Map

Suresh Krishna (now at the Cognitive Neuroscience Laboratory at the German Primate Center in Goettingen, Germany) came to my lab from Mal Semple’s lab at NYU, and Annegret Falkner (now assistant professor of neuroscience at Princeton), a graduate student who had been an undergraduate at Oberlin, decided to work on surround effects in LIP. They first discovered that planning a saccade to the surround of an LIP neuron decreases the response of that neuron to a task-irrelevant object in the center of its receptive field (Falkner 2010). They then showed that planning a saccade to the surround decreases the variability of the response to a task-irrelevant stimulus in the center, in a manner independent from the response-lowering effect (Falkner et al. 2013). Both surround suppression and decreasing variability sharpen the priority map. Annegret then trained monkeys on a Sugrue-Newsome foraging task (Sugrue et al. 2004). She recorded simultaneously from neurons that did not share excitatory centers. She placed a saccade target in the center of each receptive field. In this task, the monkeys choose their saccade goals at rates that match the probability of reward. She found that during the fixation period, the activity in the two neurons was highly correlated. After the targets appeared and the monkey was deciding which saccade target to choose, the correlation fell precipitously and even became negative, which is what should happen if surround suppression were important in shaping the priority map. The correlation during the fixation period was sensitive to the monkey’s recent history of reward. This provided further evidence for an untuned, reward-sensitive neural signal that resembled the baseline signal that Mingsha had found. Annegret still owes me a manuscript.

Cognitive Processing in the Cerebellum

Anna was working on a project to understand the relationship between LIP and V4 in visual search. Unbeknownst to her, she made an electrode hemorrhage in V4 and kept driving the electrode until she found cells. The cells responded with hand movement. She was intrigued. We figured out, after an MRI, that the electrode was probably in Crus II of the cerebellar hemisphere. She wanted to study it, but I was dubious: We had no way of measuring hand movements or separating simple from complex spikes. I did not know much about the cerebellum. There is a large literature on the possibility that the cerebellum might be involved in cognitive, as opposed to motor processes, but no monkey physiology. We devised a simple, cognitive task. The monkey was already trained on the search task, in which it had to make a right- or left-hand movement depending on the shape of a symbol. We decided to see whether the monkey could learn to assign the right hand to one new symbol and the left hand to another while we were holding a cell. We found that the monkey could learn the new association within 80 trials. The exciting thing was that the simple spikes of the cerebellar Purkinje cells tracked the learning.

Naveen Sendhilnathan, a student of Adi Murthy’s in Bangalore, joined the lab as an observer and turned to be a superb data analyst and physiologist. He asked to work a year on the cerebellum project as a technician, and then he applied and was accepted to Columbia (and Harvard) as a graduate student. He has officially joined my lab. Some cells gave a greater response when the prior trial was correct; others gave a greater response when the prior trial was wrong. Most cells did so only during a small epoch of the trial. The epochs in which there was a difference in the response after prior reward or failure, however, differed from cell to cell, so the population tiled the entire trial from fixation to after the movement. There was no difference in the kinematics of the movements when the task changed from overlearned to new symbols, although the cerebellar activity changed. There was no change in the activity when the movements changed but the symbol assignment did not. We presented this story at meetings of the SfN and the Neural Control of Movement Society—I hope this too is published before this memoir appears. Anna decided to leave the lab because of family issues, but Naveen is continuing the project.

Columbia Neurology

I hadn’t dreamed what pleasure Columbia Neurology would provide. The department is one of the best neurology departments in the country, and it attracts spectacular residents. I started working in the Thursday outpatient resident clinic. I had not done outpatient neurology since my residency and was a bit insecure. Kirk Roberts, a great clinician, shared the Thursday clinic with me. Kirk taught me as much outpatient neurology as he taught the residents, and he tolerated my occasional bouncing around the world. After a few years, I started attending on the neurology ward and consult services in the Columbia campus of the New York Presbyterian Hospital. It is immense fun. The neurology is fascinating, much more so than in the outpatient clinic, and I love the residents. They have both a thirst for learning and an esprit de corps that makes this incredibly arduous residency worthwhile. The department doesn’t have a real neuroophthalmologist, so I teach them a lot about eye movements and vision. In 2006, the residents voted to give me the Lewis P. Rowland Award for outstanding teaching. They still like to round with me.

The Society for Neuroscience

In 1971, Peter Strick came from Ed Evarts’s lab with membership forms and asked Bob and me to join the new SfN. I am member number 1,768. All three of the people who made me a neuroscientist, Bob, Torsten Wiesel, and David Hubel, were active in the Society and ultimately were elected president. They taught me to do service to the community by example. My first foray into working for the Society was purely out of self-interest. Physicians need a certain amount of certified continuing medical education (CME) credits to maintain their licenses and hospital appointments, and I found it difficult to accumulate the hours. I asked Torsten if the Society would be interested in offering CME to its members at the Annual Meeting. He suggested that I organize it. The first year, we did this as subcontractors to Georgetown University, and then I decided that the SfN could be a primary CME provider. I filled out the Accreditation Council for CME forms and completed the interview, and SfN became a CME provider. I became a member of the Education Committee. I still get my CME from the SfN.

At that time, abstracts were submitted on paper and had to be perfect and camera-ready. The society staff would then Xerox the abstracts for the program committee and ship them out via overnight delivery. When I was a member of the Program Committee, I sorted my 500 abstracts into poster and platform sessions by making 50 piles on the livingroom floor. Harvey Karten and I brought up the idea of having electronic submission of abstracts and making a CD. The SfN Council thought it would be a good idea and appointed me chair of the Ad-hoc Committee on Electronic Initiatives. We asked several companies to submit bids to provide an electronic interface for the Society that would include abstract submission, abstract sorting, a CD that included all of the abstracts, and an itinerary planner that would help you chart your way through the maze of posters and minimize conflicts with platform sessions. The first year, 1999, electronic submission was voluntary. About half of the members submitted abstracts on paper. I was worried that everyone would submit their abstracts electronically in the last half-hour, and I was right. The computer system crashed. The next year, more people submitted electronically, and ultimately electronic submission and the abstract volume became the norm. I was elected treasurer of the Society in 2004, and president-elect in 2008.

Advocacy is a major activity for the Society. After the crash of 2008, there was outpouring of letters, e-mails, and phone calls from members of Society and other scientific organizations in support of the Spector amendment to increase the NIH budget by $10 billion as a part of Obama’s stimulus package. The amendment passed. I testified in front of the House of Representative Committee that oversaw the NIH, emphasizing that not only will funding for science result in our understanding how the brain works and curing brain disease, but also that NIH funds return twice their amount to the economy. I described myself as the steward of a small business dependent on the government, supporting many people who weren’t themselves scientists. “John the Machinist” became a watchword on Capitol Hill. I then realized that the many members of the SfN who lived and worked in other countries were supporting our advocacy. Working with Sten Grillner and Helmut Kettenmann, the presidents of the Federation of European Neuroscientists, we spread the idea of advocacy abroad and provided the funds to support it.

My other major issue was animal research. In 1977, Alex Pacheco, the founder of People for the Ethical Treatment of Animals, volunteered to work in Ed Taub’s lab. While Ed was on vacation, Pacheco took pictures of the lab in disarray that he had created and of monkeys seemingly in pain, although in fact they had been sensorially denervated and couldn’t feel pain. The story hit the front page of the Washington Post, created a huge fuss, and Ed lost his grants without due process. It was apparent that animal research was vulnerable. The SfN at that time provided no support for beleaguered scientists, and usually their institutions did not help at all. Animal researchers and their families were physically threatened. We worked to make institutions more supportive and to provide statements on the importance of animal research that the universities could use immediately to support their attacked scientists without waiting for extensive exonerating investigations. The SfN website has instructions about what to do if you are the subject of animal activist harassments. We are not all the way there, but universities have become more supportive and prepared. I became chair of the Committee on Animal Research after my term as president. There will always be antivivisectionists, and the scientific community must be ever vigilant in the struggle against them. Our job is to convince the great mass of undecided people that not only is animal research likely to provide the answers that will treat diseases like schizophrenia and Alzheimer’s disease, but also that basic research seemingly unrelated to clinical problems ultimately will be related to solving those problems.

Coda

Neuroscience has given me a wonderful life. Many of my medical school classmates are retired—I am having so much fun that I still write grants and work in the lab. The stuff in the lab is currently as exciting as it has ever been. There is nothing like the thrill of discovery, understanding something that no one else has ever understood, or proving a hypothesis or stumbling upon something that you never dreamed of. It is worth the trench warfare of writing grants and struggling with journal reviewers. In my own small way, I have felt what Archimedes must have felt when he realized the implication of the wet floor. But modern science is not one man in a bathtub. I have been lucky to have had a great mentor and a fabulous bunch of collaborators, students, and postdocs who made my life better. They have been my second family. Fred Plum, the great neurologist, once said in a talk, “When I say ‘I,’ I mean ‘we.’ When I say, ‘we,’ I mean ‘they.’” That is certainly true for me. I am intensely grateful.

References

Andersen, R. A. and V. B. Mountcastle (1983). “The influence of the angle of gaze upon the excitability of the light-sensitive neurons of the posterior parietal cortex.” J. Neurosci.3: 532–548.

Bisley, J. W. and M. E. Goldberg (2003). “Neuronal activity in the lateral intraparietal area and spatial attention.” Science 299(5603): 81–86.

Bizzi, E. (1968). “Discharge of frontal eye field neurons during saccadic and following eye movements in unanesthetized monkeys.” Exp. Brain Res.6: 69–80.

Boch, R. A. and M. E. Goldberg (1989). “Participation of prefrontal neurons in the preparation of visually guided eye movements in the rhesus monkey.” J. Neurophysiol. 61: 1064–1084.

Bruce, C. J. and M. E. Goldberg (1985). “Primate frontal eye fields: I. Single neurons discharging before saccades.” J. Neurophysiol. 53: 603–635.

Colby, C. L., J.-R. Duhamel and M. E. Goldberg (1993). “Ventral intraparietal area of the macaque: Anatomic location and visual response properties.” J. Neurophysiol. 69: 902–914.

Colby, C. L., J.-R. Duhamel and M. E. Goldberg (1996). “Visual, presaccadic and cognitive activation of single neurons in monkey lateral intraparietal area.” J. Neurophysiol. 76: 2841–2852.

Colby, C. L., R. Gattass, C. R. Olson and C. G. Gross (1988). “Topographical organization of cortical afferents to extrastriate visual area PO in the macaque: a dual tracer study.” J. Compar. Neurol. 269(3): 392–413.

Deubel, H. and W. X. Schneider (1996). “Saccade target selection and object recognition: evidence for a common attentional mechanism.” Vision Res. 36(12): 1827–1837.

Duhamel, J.-R., C. L. Colby and M. E. Goldberg (1992). “The updating of the representation of visual space in parietal cortex by intended eye movements.” Science 255: 90–92.

Duhamel, J.-R., C. L. Colby and M. E. Goldberg (1998). “Ventral intraparietal area of the macaque: congruent visual and somatic response properties.” J. Neurophysiol. 79: 126–136.

Duhamel, J. R., M. E. Goldberg, E. J. Fitzgibbon, A. Sirigu and J. Grafman (1992). “Saccadic dysmetria in a patient with a right frontoparietal lesion. The importance of corollary discharge for accurate spatial behaviour.” Brain 115(Pt 5): 1387–1402.

Edelman, J. A. and M. E. Goldberg (2002). “Effect of short-term saccadic adaptation on saccades evoked by electrical stimulation in the primate superior colliculus.” J. Neurophysiol. 87: 1915–1923.

Falkner, A. L., M. E. Goldberg and B. S. Krishna (2013). “Spatial representation and cognitive modulation of response variability in the lateral intraparietal area priority map.” J. Neurosci. 33(41): 16117–16130.

Falkner, A. L., B. S. Krishna and M. E. Goldberg (2010). “Surround suppression sharpens the priority map in LIP.” J. Neurosci. 30(30): 12787–12797.

Fischer, B. and R. Boch (1980). “Enhanced visual activity of prelunate neurons before eye movement of trained rhesus monkeys.” Exp. Brain Res. 41: A 34.

Fischer, B. and R. Boch (1983). “Saccadic eye movements after extremely short reaction times in the monkey.” Brain Res. 260: 21–26.

FitzGibbon, E. J., M. E. Goldberg and M. A. Segraves (1986). Short term saccadic adaptation in the monkey. Adaptive Processes in the Visual and Oculomotor Systems. E. Keller and D. S. Zee. Oxford, Pergamon Press, 329–333.

Ganguli, S., J. W. Bisley, J. D. Roitman, M. N. Shadlen, M. E. Goldberg and K. D. Miller (2008). “One-dimensional dynamics of attention and decision making in LIP.” Neuron 58(1): 15–25.

Gee, A. L., A. E. Ipata, J. W. Bisley, J. Gottlieb and M. E. Goldberg (2007). On the agnosticism of spikes: salience, saccades, and attention in the lateral intraparietal area of the monkey. Attention and Performance. P. Haggard, Y. Rosetti and M. Kawato. Oxford, UK, Oxford University Press, XXII: 1–26.

Goldberg, M. E. and C. J. Bruce (1990). “Primate frontal eye fields. III. Maintenance of a spatially accurate saccade signal.” J. Neurophysiol. 64: 489–508.

Goldberg, M. E., C. L. Colby and J.-R. Duhamel (1990). “Representation of visuomotor space in the parietal lobe of the monkey.” Cold Spring Harbor Symp. Quant. Biol. 55: 729–739.

Goldberg, M. E. and R. H. Wurtz (1972). “Activity of superior colliculus in behaving monkey: I. Visual receptive fields of single neurons.” J. Neurophysiol. 35: 542–559.

Goldberg, M. E. and R. H. Wurtz (1972). “Activity of superior colliculus in behaving monkeys. II. Effect of attention on neuronal responses.” J. Neurophysiol. 35: 560–574.

Gottlieb, J., M. Kusunoki and M. E. Goldberg (1998). “The representation of visual salience in monkey parietal cortex.” Nature 391: 481–484.

Guitton, D., H. Buchtel and R. Douglas (1985). “Frontal lobe lesions in man cause difficulties in suppressing reflexive glances and in generating goal-directed saccades.” Exp. Brain Res. Experimentelle Hirnforschung. Expérimentation cérébrale 58(3): 455–472.

Hallett, P. E. and A. D. Lightstone (1976). “Saccadic eye movements to flashed targets.” Vision Res. 16: 107–114.

Hasegawa, R. P., A. M. Blitz, N. L. Geller and M. E. Goldberg (2000). “Neurons in monkey prefrontal cortex that track past or predict future performance.” Science 290(5497): 1786–1789.

Hasegawa, R. P., A. M. Blitz and M. E. Goldberg (2004). “Neurons in monkey prefrontal cortex whose activity tracks the progress of a three-step self-ordered task.” J. Neurophysiol. 92(3): 1524–1535.

Hasegawa, R. P., B. W. Peterson and M. E. Goldberg (2004). “Prefrontal neurons coding suppression of specific saccades.” Neuron 43(3): 415–425.

Heide, W., M. Blankenburg, E. Zimmermann and D. Kompf (1995). “Cortical control of double-step saccades: implications for spatial orientation.” Ann. Neurol. 38(5): 739–748.

Ipata, A. E., A. L. Gee, J. W. Bisley and M. E. Goldberg (2009). “Neurons in the lateral intraparietal area create a priority map by the combination of disparate signals.” Exp. Brain Res. 192(3): 479–488.

Ipata, A. E., A. L. Gee, M. E. Goldberg and J. W. Bisley (2006). “Activity in the lateral intraparietal area predicts the goal and latency of saccades in a free-viewing visual search task.” J. Neurosci. 26(14): 3656–3661.

Ipata, A. E., A. L. Gee, J. Gottlieb, J. W. Bisley and M. E. Goldberg (2006). “LIP responses to a popout stimulus are reduced if it is overtly ignored.” Nat. Neurosci. 9(8): 1071–1076.

Kodaka, Y., A. Mikami and K. Kubota (1997). “Neuronal activity in the frontal eye field of the monkey is modulated while attention is focused on to a stimulus in the peripheral visual field, irrespective of eye movement.” Neurosci. Res. 28(4): 291–298.

Kowler, E., E. Anderson, B. Dosher and E. Blaser (1995). “The role of attention in the programming of saccades.” Vision Res. 35(13): 1897–1916.

Krauzlis, R. J., L. P. Lovejoy and A. Zenon (2013). “Superior colliculus and visual spatial attention.” Ann. Rev. Neurosci. 36: 165–182.

Kusunoki, M. and M. E. Goldberg (2003). “The time course of perisaccadic receptive field shifts in the lateral intraparietal area of the monkey.” J. Neurophysiol. 89(3): 1519–1527.

Lynch, J. C., V. B. Mountcastle, W. H. Talbot and T. C. T. Yin (1977). “Parietal lobe mechanisms for directed visual attention.” J. Neurophysiol. 40: 362–389.

Mays, L. E. and D. L. Sparks (1980). “Dissociation of visual and saccade-related responses in superior colliculus neurons.” J. Neurophysiol. 43: 207–232.

Mays, L. E. and D. L. Sparks (1980). “Saccades are spatially, not retinocentrically, coded.” Science 208: 1163–1165.

McLaughlin, S. C. (1967). “Parametric adjustment in saccadic eye movements.” Percept. Psychophys. 2: 359–362.

Mohler, C. W., M. E. Goldberg and R. H. Wurtz (1973). “Visual receptive fields of frontal eye field neurons.” Brain Res. 61: 385–389.

Mohler, C. W. and R. H. Wurtz (1977). “Role of striate cortex and superior colliculus in visual guidance of saccadic eye movements in monkeys.” J. Neurophysiol. 40: 74–94.

Mountcastle, V. B., J. C. Lynch, A. Georgopoulos, H. Sakata and C. Acuña (1975). “Posterior parietal association cortex of the monkey: command functions for operations within extrapersonal space.” J. Neurophysiol. 38: 871–908.

Munoz, D. P., D. Pélisson and D. Guitton (1991). “Movement of neural activity on the superior colliculus motor map during gaze shifts.” Science 251: 1358–1360.

Palmer, L. A., A. C. Rosenquist and R. J. Tusa (1978). “The retinotopic organization of lateral suprasylvian visual areas in the cat.” J. Comp. Neurol. 177: 237–236.

Petrides, M. (1995). “Impairments on nonspatial self-ordered and externally ordered working memory tasks after lesions of the mid-dorsal part of the lateral frontal cortex in the monkey.” J. Neurosci. 15(1 Pt 1): 359–375.

Petrides, M. and B. Milner (1982). “Deficits on subject-ordered tasks after frontal- and temporal-lobe lesions in man.” Neuropsychologia 20(3): 249–262.

Poletti, M., D. C. Burr and M. Rucci (2013). “Optimal multimodal integration in spatial localization.” J. Neurosci. 33(35): 14259–14268.

Pouget, A. and T. J. Sejnowski (1997). “Spatial transformations in the parietal cortex using basis functions.” J. Cogn. Neurosci. 9(2): 222–237.

Quaia, C., L. M. Optican and M. E. Goldberg (1998). “The maintenance of spatial accuracy by the perisaccadic remapping of visual receptive fields.” Neural Networks 11: 1229–1240.

Robinson, D. A. (1963). “A method of measuring eye movement using a scleral search coil in a magnetic field.” IEEE Trans. Biomed. Engin. BME-10: 137–145.

Robinson, D. A. (1972). “Eye movements evoked by collicular stimulation in the alert monkey.” Vision Res. 12(11): 1795–1808.

Robinson, D. A. and A. F. Fuchs (1969). “Eye movements evoked by stimulation of frontal eye fields.” J. Neurophysiol. 32(5): 637–648.

Robinson, D. L., M. E. Goldberg and G. B. Stanton (1978). “Parietal association cortex in the primate: Sensory mechanisms and behavioral modulations.” J. Neurophysiol. 41: 910–932.

Schall, J. D. and D. P. Hanes (1993). “Neural basis of saccade target selection in frontal eye field during visual search.” Nature 366(6454): 467–469.

Schiller, P. H. and M. Stryker (1972). “Single-unit recording and stimulation in superior colliculus of the alert rhesus monkey.” J. Neurophysiol. 35: 915–924.

Sommer, M. A. and R. H. Wurtz (2006). “Influence of the thalamus on spatial visual processing in frontal cortex.” Nature 444(7117): 374–377.

Stanton, G. B., C. J. Bruce and M. E. Goldberg (1988). “Frontal eye field efferents in the macaque monkey. I. Subcortical pathways and topography of striatal and thalamic terminal fields.” J. Comp. Neurol. 271: 473–492.

Stanton, G. B., C. J. Bruce and M. E. Goldberg (1988). “Frontal eye field efferents in the macaque monkey. II. Topography of terminal fields in midbrain and pons.” J. Comp. Neurol. 271: 493–506.

Stanton, G. B., C. J. Bruce and M. E. Goldberg (1993). “Topography of projections to the frontal lobe from the macaque frontal eye fields.” J. Comp. Neurol. 330: 286–301.

Stanton, G. B., C. J. Bruce and M. E. Goldberg (1995). “Topography of projections to posterior cortical areas from the macaque frontal eye fields.” J. Comp. Neurol. 353: 291–305.

Stanton, G. B., S.-Y. Deng, M. E. Goldberg and N. T. McMullen (1989). “Cytoarchitectural characteristic of the frontal eye fields in macaque monkeys.” J. Comp. Neurol. 282: 415–427.

Steenrod, S., M. H. Phillips and M. E. Goldberg (2013). “The lateral intraparietal area (LIP) codes the location of saccade targets and not the dimension of the saccades that will be made to acquire them.” J. Neurophysiol. 109(10): 2596–2605.

Sterling, P. and B. Wickelgren (1969). “Visual receptive fields in the superior colliculus of the cat.” J. Neurophysiol. 32: 1–15.

Sugrue, L. P., G. S. Corrado and W. T. Newsome (2004). “Matching behavior and the representation of value in the parietal cortex.” Science 304(5678): 1782–1787.

Teuber, H. L. (1960). Perception. Handbook of Physiology, Section I: Neurophysiology. H. W. Magoun. Washington, DC, American Physiological Society. III: 1595–1669.

Thompson, K. G., K. L. Biscoe and T. R. Sato (2005). “Neuronal basis of covert spatial attention in the frontal eye field.” J. Neurosci. 25(41): 9479–9487.

Umeno, M. M. and M. E. Goldberg (1997). “Spatial processing in the monkey frontal eye field. I. Predictive visual responses.” J. Neurophysiol. 78: 1373–1383.

Umeno, M. M. and M. E. Goldberg (2001). “Spatial processing in the monkey frontal eye field. II. Memory responses.” J. Neurophysiol. 86: 2344–2352.

Walker, M. F., E. J. Fitzgibbon and M. E. Goldberg (1995). “Neurons in the monkey superior colliculus predict the visual result of impending saccadic eye movements.” J. Neurophysiol. 73(5): 1988–2003.

Wang, X., C. C. Fung, S. Guan, S. Wu, M. E. Goldberg and M. Zhang (2016). “Perisaccadic Receptive Field Expansion in the Lateral Intraparietal Area.” Neuron 90(2): 400–409.

Wang, X., M. Zhang, I. S. Cohen and M. E. Goldberg (2007). “The proprioceptive representation of eye position in monkey primary somatosensory cortex.” Nat. Neurosci. 10(5): 640–646.

Wurtz, R. H. and M. E. Goldberg (1971). “Superior colliculus cell responses related to eye movements in awake monkeys.” Science 171(966): 82–84.

Wurtz, R. H. and M. E. Goldberg (1972). “Activity of superior colliculus in behaving monkey: III. Cells discharging before eye movements.” J. Neurophysiol. 35(4): 575–586.

Wurtz, R. H. and M. E. Goldberg (1972). “Activity of superior colliculus in behaving monkey. IV. Effects of lesions on eye movements.” J. Neurophysiol. 35(4): 587–596.

Xu, B., C. Karachi and M. Goldberg (2012). “The postsaccadic unreliability of gain fields renders it unlikely that the motor system can use them to calculate target position in space.” Neuron 76(6): 1201–1209.

Xu, Y., X. Wang, C. Peck and M. E. Goldberg (2011). “The time course of the tonic oculomotor proprioceptive signal in area 3a of somatosensory cortex.” J. Neurophysiol. 106(1): 71–77.

Yantis, S. and J. Jonides (1990). “Abrupt visual onsets and selective attention: voluntary versus automatic allocation.” J. Exp. Psychol. Hum. Percept. Perform. 16(1): 121–134.

Young, L. R. (1963). “Measuring eye movements.” Am. J. Med. Electr. 2: 300–307.

Zhang, M., X. Wang and M. E. Goldberg (2014). “A spatially nonselective baseline signal in parietal cortex reflects the probability of a monkey’s success on the current trial.” Proc. Natl. Acad. Sci. USA 111(24): 8967–8972.

Zhou, H. H. and K. G. Thompson (2009). “Cognitively directed spatial selection in the frontal eye field in anticipation of visual stimuli to be discriminated.” Vision Res. 49(10): 1205–1215.

Zipser, D. and R. A. Andersen (1988). “A back-propagation programmed network that simulates response properties of a subset of posterior parietal neurons.” Nature 331: 679–684.

Zivotofsky, A. Z., M. E. Goldberg and K. D. Powell (2005). “Rhesus monkeys behave as if they perceive the Duncker Illusion.” Journal of cognitive neuroscience 17(7): 1011–1017.

Zivotofsky, A. Z., K. G. Rottach, L. Averbuch-Heller, A. A. Kori, C. W. Thomas, L. F. Dell’Osso and R. J. Leigh (1996). “Saccades to remembered targets: the effects of smooth pursuit and illusory stimulus motion.” J. Neurophysiol. 76(6): 3617–3632.

¹See https://www.youtube.com/watch?v=cU2i3gx8880, starting around 22 seconds from the beginning.

²Dunker Motion Illusion, YouTube, October 29, 2014, https://www.youtube.com/watch?v=QUbJKakfmZw.

Mary Elizabeth (“Mary Beth”) Hatten

BORN:

Richmond, Virginia

February 1, 1950

EDUCATION:

Hollins College, Roanoke, VA, AB (1971)

Princeton University, Princeton, NJ, PhD (1975)

Harvard Medical School, Boston, MA, Postdoctoral (1978)

APPOINTMENTS:

Assistant Professor of Pharmacology, New York University School of Medicine (1978–1982)

Associate Professor of Pharmacology (with tenure), New York University School of Medicine (1982–1986)

Associate Professor of Pathology in the Center for Neurobiology and Behavior College of Physicians and Surgeons of Columbia University (1986–1988)

Professor of Pathology in the Center for Neurobiology and Behavior College of Physicians and Surgeons of Columbia University (1988–1992)

Professor and Head of the Laboratory of Developmental Neurobiology, The Rockefeller University (1992–2000)

Frederick P. Rose Professor and Head of the Laboratory of Developmental Neurobiology, The Rockefeller University (2000–present)

HONORS AND AWARDS (SELECTED)

Westinghouse National Science Talent Search Award Finalist (1967)

Research Fellow of the Alfred P. Sloan Foundation (1983–1985)

Pew Neuroscience Award (1988–1992)

McKnight Neuroscience Development Award (1991–1993)

Javits Neuroscience Investigator Award (1991–1998)

National Science Foundation Faculty Award for Women Scientists and Engineers (1991–1996)

Weill Award, American Association of Neuropathology (1996)

Ph.D., Hollins College, honoris causa (1998)

Fellow, American Association for the Advancement of Science (2002)

Distinguished Alumna Award, Hollins University (2011)

Cowan-Cajal Award for Developmental Neuroscience (2015)

Elected to National Academy of Sciences, USA (2017)

Ralph J. Gerard Prize in Neuroscience, Society for Neuroscience (2017)

Mary E. Hatten has used the mouse cerebellar cortex as a model to study molecular mechanisms of central nervous system (CNS) cortical neurogenesis and migration. She pioneered live imaging methods that proved that CNS neurons migrate on glial fibers and revealed a specific, conserved mode of CNS neuronal migration along glial fibers in different cortical regions. Subsequently, she used bioassays to identify key molecular regulators of neuronal migration, including the neuron-glial adhesion ligand Astn1 and the polarity complex mPar6, which coordinates cytoskeletal dynamics during cerebellar granule neuron migration. Using mouse genetics and in vitro chimeras, she discovered that the cerebellar territory arises from rhombomere 1 and that the weaver (Girk2) gene acts nonautonomously in granule cells. Her lab generated the first cDNA libraries from an identified CNS neuron, the cerebellar granule neuron, which she used to identify more than 80 genes that function in cerebellar development. Her research has broad significance for human genetic studies on developmental brain disorders, such as autism, attention deficit disorder, and childhood epilepsy.

Mary Elizabeth (“Mary Beth”) Hatten

The Early Years

I was born the middle child, between two brothers, Bobby and Jay, into a large, extended family, with deep Virginia roots and a distinguished record of community service. Although my father and grandfather, Drs. John Hatten and Waverly Payne, were prominent physicians, medicine held little attraction for me. Instead I used the laboratory of the local hospital in Newport News, Virginia, as a springboard for school science projects. Fortunately for me, that same small Virginia city was the home of NASA’s Langley Research Center, the site of biological research for the early manned space flights, where I worked during the summers in college. As a child, I was lucky to have teachers who encouraged me to do science projects as early as age 10, when Mrs. Little, one of my favorite teachers, said of course, it would be interesting to put the skeleton of the chicken we had eaten for dinner back together again! Later, wonderful teachers, who taught Advanced Placement courses in biology and chemistry in high school, would be influential, but it was my mother, Mary Lou Hatten, who inspired me to follow my interests wherever they might lead. Although my mother was a community leader, not a scientist, who helped spearhead the development of community projects like the Nature Museum and a Live Theatre for elementary school children, she had limitless enthusiasm for helping me do science projects. Thanks to her, I had incubators and microscopes to do Drosophila genetics in my room, and rabbits in the garden shed to generate cell surface antibodies for a project on how gravity affected the growth patterns and colony-forming characteristics of bacteria. My mother often told a story about the reaction of the local newspaper writer who, when spotting a bulletin board covered in photos of the Beatles and Rolling Stones across my room from the science experiments, said, “Thank God!” It was not unlike the reaction I got from Pamela Harriman many years later at a Rockefeller dinner, after I had come there as the first female professor. “You look so normal” she said. Being a southern girl interested in science was not the usual path.

High School Years: The Space Experiments

I went to Homer L. Ferguson High School, a large public high school in the neighborhood where we lived. Although it was not the happiest period of my life, I was busy with sports, clubs, and activities. Two biology teachers, Henry Drudge and Bernie Freeman, encouraged me to do an independent project for the annual science fair, which led me, with my father’s assistance (Dr. John Hatten), to the local hospital laboratory. Among other things, the 1960s were the age of questions about space exploration. Space captured my imagination because Hampton, the adjacent city was the home of NASA’s Mercury Program. Just after his magnificent voyage, I had been able to meet John Glenn at Langley Field, a thrilling experience made all the more so as Glenn, himself a redhead, tussled my hair when I met him and asked “How are you doing, Red?”

My high school science project concerned a general question that would stay with me: how cell-cell interactions influence development. In the 1960s, it was unclear how gravity would influence the growth of bacteria, especially pathogenic bacteria, and whether uncontrolled growth would threaten the lives of the astronauts. I became interested in the proliferation of bacteria and their formation of colonies with different shapes in semisolid growth media. For my project, I grew the bacteria under two conditions—normal gravity or higher gravity generated by centrifugation. To measure differences in surface proteins of the bacteria subjected to higher gravity, I raised antibodies against the bacteria. I was remarkably fortunate that the head of the hospital laboratory, Jerry Hagelberger, seemed thrilled to have a young person interested in science in his otherwise-clinical lab. He taught me all about bacteria and provided all of the equipment I needed. I went to the hospital lab every afternoon for two years working on my project. One piece of equipment, a centrifuge, would gain fame in the article written by the local newspaper journalist mentioned previously. I told him about spinning the bacteria in the centrifuge to collect them for the immunizations and he wrote that I was spinning rabbits in a machine the “size of a washing machine!” That gave me a healthy suspicion of the scientific press. But the project went well, well enough to win a number of local science fairs (which my mother took me to without complaint), and well enough to become a finalist in the Westinghouse Science Talent Search.

My project “Study of the Antigenicity of a Mutant Strain of Aerobacter Aerogenes Produced by the Application of Centrifugal Force” also did well at the NASA Youth Science Congress in 1966, where I met Dr. Judd R. Wilkins, who ran the microbiology lab at NASA’s Langley Research Center. That was especially fortunate, because he gave me a summer job in their labs for the next four years. I really loved working at NASA during the summers and was proud that my project on gravity and bacterial growth eventually flew on an Apollo mission to the moon. Watching the film Hidden Figures about the remarkable work of Catherine Johnson in 2016 reminded me that there were virtually no women scientists at NASA in those days (1967–1971). Just as in the movie, all of the men had white socks, pocket pen protectors, and slide rules. Fortunately, I was so excited about the science that I didn’t notice their attitudes about women, and luckily Dr. Wilkins was a supportive mentor.

Hollins College

It’s hard to believe now, but in 1967, when I applied to college, almost none of the colleges and universities in the East were coeducational. I ended up choosing Hollins College, not just because my mother went there, but also because the most interesting women I knew growing up were her Hollins friends. I loved Hollins for many reasons. I discovered writing and philosophy there and would later realize that it was at Hollins where I first recognized a “woman’s voice,” the voice missing at NASA and in the culture at large in the 1960s. I would appreciate what that meant years later at Columbia when I attended a meeting of the tenured women faculty. I was so thrilled to be meeting those amazing women, who included the great anthropologist Ruth Benedict; the historian Marjorie Nicholson; the scientists Ruth Sager, Salome Gluecksohn-Waelsch, and Sarah Ratner; the novelists Elizabeth Hardwick (Sleepless Nights) and Mary Gordon (Temporary Shelter); and the theologian Elaine Pagels (The Gnostic Gospels). At the meeting, 60 women were trying to fit their chairs into a circle, a stunning sight! Women’s voices filled the room—a different culture, a different way of interacting with one another. The “woman’s voice” that I first heard at Hollins, and recognized later at Columbia, would thankfully stay with me as I went through a career, often being the only woman or one of but a few women in the room.

My years at Hollins were deeply happy years, as I loved the academic work—biochemistry with Sandy Boatman, physical chemistry with Ralph Steinhardt, American literature with Richard Dillard, and philosophy with Larry Becker as well as the January short term when I could do research. I especially enjoyed being able to delve into the arts and humanities. I also enjoyed being involved in student governance, as we gained student representation to faculty meetings and initiated a student-run exam system while I was chair of the Student Government’s Academic Legislation Committee. The times were remarkable between 1967 and 1971, because of the intensity of social change, the politics of the Vietnam War, and, of course, the incredible music! As much as anything, I enjoyed my friends at Hollins. Our long discussions across disciplines enriched how I approached my work in the lab. These conversations continue today, most frequently with my roommate Kathy Hudson, now a well-known garden writer; Jigga Gaynor Dunn, a producer of books on tape; and Nathalie Gilfoyle, general counsel for the American Psychological Association and expert on the intersection between law and psychology.

Graduate School at Princeton and in Basel: Plant Lectins and Membrane Dynamics

I arrived at Princeton in 1971 as a graduate student in biochemical sciences, one of the first years that Princeton admitted women undergraduates. This year was also among the early years that women were admitted to the graduate program in biochemical sciences. Coming from a southern women’s college, I have to say that I found Princeton to be far more conservative politically and socially than Hollins had been. That was surprising, to say the least. I enjoyed my first two years at Princeton, especially knowing Rudi Jaenish and Art Levinson during a stint in Arnie Levine’s lab, and Marc Kirshner who moved into my mentor Max Burger’s old lab as a new faculty member after Max left for Basel. In Max’s lab, I again worked on cell surface proteins, this time using the new reagents that Max had discovered, plant lectins, to study changes in surface properties associated with cancer. After only two years at Princeton, I followed Max to the Biocenter in Basel, Switzerland, to finish my thesis research.

The Biocenter was an especially exciting place, as Werner Arber was purifying restriction enzymes across the hall and Walter Gehring was doing exciting Drosophila genetics downstairs. Indeed, two of Gehring’s postdocs at the time, Janni Nusslein Volhard and Eric Wieschaus, went on to win the Nobel Prize for their discovery of genes that control the early development of Drosophila. The Burger lab was an exciting place as well, given the buzz at the time about plant lectins revealing key differences between normal and transformed cancer cells. I was remarkably fortunate to work with two talented postdocs in the lab, Rick Horwitz and Carl Scandella. With Rick, I worked out methods to remove the lipids from serum, a step that allowed us to manipulate the lipid composition of normal and transformed cell membranes. We used that approach to show that the receptors for different lectins were in different lipid domains of the membrane, a discovery that was later credited as a prelude to the concept of membrane lipid rafts. Rick, who trained with Britton Chance, was a spectacular mentor, who taught me what a good experiment was, and who pushed me to think critically, especially about my own work! After Rick went back to the United States to become an assistant professor at the University of Pennsylvania, I worked with Carl Scandella, a biochemist and biophysicist who trained with Harden McConnell and Arthur Kornberg at Stanford. With Carl, who was one of the most rigorous scientists I ever knew, I incorporated fatty acid spin labels into the cells, a method that allowed us to show that the lipids in the vicinity of the receptors for different lectins had different lipid phase properties. We also used TEMPO labeling to measure how much of the membrane was fluid in normal versus transformed cells. I really enjoyed being able to make precise biophysical measurements of the lipids around lectin receptors. Of course, at that time, we didn’t realize that lectins bound to a large number of receptors. Rick and Carl were wonderful colleagues and, together with Max, they provided me with training in membrane biochemistry as well as in cancer biology.

I also enjoyed working in Europe during those years. It was exciting to be in a different culture, to be able to drive to the ski slopes in the Alps in two hours, or to take a train to Paris or a quick flight to London, where my close Hollins friend, Jigga Dunn, was living. Through Max, I met Nicole LeDouarin, a professor at the College de France in Paris, who would introduce me to cell migrations in the developing nervous system. Indeed, it was Nicole who inspired me to work on nervous system development. Her beautiful work used genetics and developmental biology, a combination I would use in studies on the developing mouse brain.

Harvard Medical School: Cerebellar Development and Genetics

One of the reasons I studied the membrane properties of cancer cells was to understand the molecular basis of metastasis. As nearly all studies on cancer cells were carried out on transformed cell lines in culture at that time, I thought it would be important to learn about mechanisms of normal cell migrations. That took me to the nervous system, where exciting new work concerned the large-scale migrations during brain development, migrations that take young neurons from proliferative zones out to form the layers of cortical regions. To learn about CNS migration, I went to Harvard Medical School to work with Richard Sidman who, together with Pasko Rakic, was carrying out cutting-edge work on central nervous system (CNS) migrations. The lab studied the cerebellum, a region of the brain that controls motor coordination, and also used mouse genetics to analyze the development of the cerebellum of mice with spontaneous neurological mutations that Dick had identified at the Jackson Laboratories (with Hope Sweet). The mouse mutants had names like weaver, reeler, stumbler, and leaner and were the first genetic models for mammalian brain development. They were used by our lab and others to dissect the molecular mechanisms of cerebellar development.

Before joining Sidman’s lab, I spent a summer at Woods Hole taking the Neurobiology Course. That was fortuitous for many reasons, including the quality of the course and the fact that it was taught by the Harvard Neurobiology Department. One of the highlights of the course was Gerry Fishbach’s new method for culturing nerve and muscle cells, which provided a model system to study neuromuscular junctions. It was a great summer and provided a running start for my postdoctoral work. I also met Torsten Wiesel that summer. Torsten would be one of the most important mentors in my career, especially after I moved to Rockefeller many years later.

Learning about cerebellar development from Richard Sidman was especially exciting. Dick had assembled the first interdisciplinary neuroscience department, with neuroanatomists (Pasko Rakic), geneticists (Dick Mullen), biochemists (Mike Shelanski, Susanne Roffler-Tarlov), immunologists (Melitta Schachner), and neurologists (Verne Caviness, Dennis Selkoe). Every Tuesday, I spent the morning doing dissections of the embryonic mouse cerebellum with Dick, an invaluable series of lessons from the master of cerebellar development. The postdocs in the department—Carla Shatz with Pasko Rakic and Jeff Noebels with Dick Sidman among others—would remain among my closest friends and colleagues. Then, too, as I had taken the Woods Hole Neurobiology Course with the Neurobiology Department faculty (a separate department at the Medical School), I often attended their seminars and came to know the neurobiology postdocs as well. They included Charles Gilbert, Josh Sanes, Tom Jessell, Jane Dodd, Story Landis, and Bill Harris, who have also been lifelong colleagues and friends. It was the golden age of Harvard neuroscience, and I was privileged to have been a part of it.

Soon after I arrived in Boston in 1975, Dick Sidman encouraged me to attend the Society for Neuroscience (SfN) meeting for the first time. The meeting was in New York and the entire event took place in the New York Hilton Hotel. There were only about 3,000 people at the SfN meeting that year!

Back at the Children’s Neuroscience Department, I focused on trying to culture embryonic cerebellar neurons and test their surface properties, using lectins as probes, and on what would be the beginnings of methods to do live imaging of glial-guided migration. It was especially beneficial to work with Pasko Rakic, who was doing masterful anatomy on glial-guided migration, and to learn mouse genetics in the Sidman lab. The genetics experiments with mouse chimeras that were ongoing in the lab showed, for the first time, which genes acted autonomously and which acted nonautonomously during cerebellar development. That work changed the view that mammalian brain development involved little plasticity. Now, we know that there is extensive plasticity and that cell interactions are a major force in mammalian CNS development.

New York University and Columbia: Mechanisms of Glial-Guided Migration

Although I would have gladly stayed at Harvard for many more years, I abruptly moved to New York in 1978, because my then-husband lost his job in the Harvard History Department and moved to Wall Street. Luckily for me, Mike Shelanski, who had just become chair of the Pharmacology Department at the New York University (NYU) School of Medicine, recruited me, along with Ron Liem and Lloyd Greene, from Harvard to join the department. Mike was such a supportive chairman. Recruiting Ron turned out to be fortuitous, as it was Ron who asked me to try out his new antibody against glial fibrillary acidic protein (GFAP) in my cerebellar cultures, which was the experiment that revealed that glia provide a template for the positioning of neurons in the cultures. The ability to visualize the neurons and the glia in the cultures, and measure their interactions, led me to go back to my original goal, to study neuronal migration. At about the same time, Mike hired Carol Mason, a wonderful neuroanatomist who had trained with Ray Guillery at Chicago, and Fred Maxfield, a biophysicist who had done important imaging work with Watt Webb at Cornell. Carol taught me neuroanatomy, and Fred opened my eyes to the power of live imaging. Indeed, Fred and I discovered optical memory disk recorder (OMDR) digital recording decks at a trade show for advertisers in New York, but I am getting ahead of myself.

Carol and I soon started a tradition of going to the SfN meeting together every year. The meetings were smaller in those years, which gave me a chance to reconnect with people I knew at Harvard, now scattered around the country, and to get to know new people, mostly through Carol. Carol’s work in the visual system, along with that of Carla Shatz, took me to the talks on the visual system, where I soon met Sue McConnell, Martha Constantine Paton, and others. It was especially rewarding to connect with young women scientists.

Over the years at NYU, I focused more and more on cerebellar granule cells (GCs). Being influenced by Corey Goodman’s experiments on identified neurons in the grasshopper, I developed a rapid method to purify granule neurons to image the migration of an identified CNS neuron in vitro. That was an important step that would open the door to molecular experiments on the mechanisms of migration and of cerebellar development. At a glance, GCs shared a lot of features with B cells of the immune system. Both were incredibly small and both had disproportionately large nuclei, a fact that made B cells “heavy” and easy to purify in Ficoll density gradients. I therefore tested Ficoll and the newer Percoll density gradients to try to purify cerebellar GCs. Fortunately, it worked as I had hoped, and we were able to purify millions of GCs based on their sedimentation rates in a step gradient. By default, we obtained a fraction of large cells that contained the glial cells (and the Purkinje cells). That enabled us to make pure cultures of GCs. Carol Mason was instrumental in our efforts to prove that we indeed had purified GCs, because of her expertise in electron microscopy (EM) and in all things anatomical. Carol was a very important influence, not the least because of her knowledge of neuroanatomy, but also because of her remarkable expertise in microscopy.

About that time, Jim Edmondson came to my lab as my first graduate student. Jim was incredibly meticulous, a skill that enabled him to make precise cultures and later to carry out detailed video recordings. I had begun to do video recordings of migrating GCs about the time Jim arrived, having done my first successful movie the night before my son John was born! Carol and I would share another treasure during those years, our toddler sons John and Daniel. We spent many happy afternoons on the beach in Rye or Rowayton playing with the boys and talking about science.

Jim Edmondson’s work would span the time at NYU and at Columbia, as Mike had decided to move our neuro group (Carol, Ron, Fred, Lloyd, Mike, and I) from NYU Pharmacology to the Columbia College of Physicians and Surgeons. At Columbia, Eric Kandel was organizing a new neuroscience program in neurobiology and behavior with faculty across multiple departments. Eric’s program was a masterstroke as it included scientists across different areas of neuroscience: Richard Axel, who was already at Columbia, in molecular neuroscience; Eric’s own lab (Jimmy Schwartz, Steve Siegelbaum and others) in physiology and behavior; our group in development, neuroanatomy, and biochemistry; and young scientists he recruited from Harvard, most important for me, Tom Jessell and Jane Dodd in developmental neuroscience. Columbia became an especially vibrant and exciting environment for neurobiology.

Although we had used the best tape recording decks available to follow neuronal migration in vitro, the ones used by network news, the transit time to move the tape forward created an artifact in the videos. Fortunately, Fred Maxfield, as mentioned, and I discovered that OMDR digital recording machines would eliminate that problem and provide what were rather stunning images of GC migration. Those experiments were also facilitated by the new Nomarksi optics and video-enhanced contrast differential interference contrast microscopy, with which we provided the first real-time, high-resolution digital images of CNS migration. Fred was instrumental in helping us set all of that up in the lab, but it was Jim Edmondson who made the system work for imaging migration. His work involved finding culture dishes that were flat enough to fit on the stage under the condenser and using Mary Bunge’s scheme to make drop well culture dishes with a number 1 glass coverslip affixed as a false bottom. The glass coverslip enabled the use of high-magnification and low–numerical aperture (NA) objectives (Zeiss 1.5 NA 63×) to acquire high-resolution images. The optics and culture setup were absolutely necessary given the small size of the GC (4–6 microns) and the narrow diameter of the glial fiber (1 micron). The videos that Jim took in 1985–1986 were thrilling, because they proved that neurons migrate on glial fibers, a fact we showed by scribing the area we had filmed, immunostaining with antibodies against glial cellular antigen markers, and identifying the fibers that supported migration as glial fibrillary acidic protein (GFAP) GFAP+ glial fibers. Carol Mason, Jim, and Carol’s postdoc Bill Gregory then teamed up to do the tour de force experiment—to scribe a migrating neuron and serially section that cell for EM. The correlated EM images showed that all of the morphological features that Pasko Rakic had assigned to migrating GCs in vivo were evident in cells migrating on glial fibers in our in vitro system. These features included the formation of a puncta adherens migration junction with the glial fiber just underneath the neuronal cell soma, the positioning of the nucleus in the posterior aspect of the cell, a notch in the nucleus in the direction of migration and a basal body (centrosome) just forward of the nucleus in the direction of migration. I took the images to Yale to show Pasko as soon as I could. He was as thrilled as we were to be able to see migration in real time for the first time and thereby prove that his theory of glial-guided neuronal migration was correct.

As we were doing imaging experiments on migration, one of our main goals was to identify the receptors that guided the movement of the neurons along the glial fiber. To identify the receptor, James Edmonson had raised antibodies against GC membranes (while we were still at NYU). Trevor Stitt then used biochemisty to identify which band among the proteins recognized by the antibody was the active receptor, a protein we named Astrotactin, because it mediated neuronal touching of astroglia. Trevor showed that antibodies purified from that band in the Western blot would block the binding of radiolabeled GC membranes to astroglial cells. This demonstrated that Astrotactin was a neuron-glial adhesion protein.

Soon after we moved to Columbia, I had become a single parent. I was concerned about giving my young son John time out of New York in nature, so we started going to Woods Hole in the summer. At first, I went as an instructor in the neurobiology course, then, when that was incompatible with being a single parent, we started going to Martha’s Vineyard for the month of July. That got John out of the city and helped me get out on the roads to bike or on the beaches to swim in the afternoons. Later, in the 1990s, after Gord Fishell had gotten me into sea kayaking, I also spent time out on the beautiful waters around the Vineyard and Woods Hole. Many colleagues and friends would stop to see us at the Vineyard after teaching at Woods Hole in those days. I especially enjoyed having Scott and Marianne Fraser and their children, as well as Josh Sanes and Susan Corcoran and their kids, come to visit. Chilmark had the perfect setup with an outstanding childcare program, where the cost was the same whether you had one or many children and activities ranged from tennis to arts and crafts to swimming lessons. I could work in the mornings while John was at camp. Then in the afternoons, we would go to the beach where he would play with his friends from the morning camp. We went to Martha’s Vineyard for more than a decade and had wonderful times there. Although many have asked me how I managed to be a single parent and do science, I think it was a major benefit. Going home at an early hour during the school year meant I took time to “play,” which I thought was great for my work, and taking so much time in the summers, before the years of 24/7 Internet access, gave me time with my son, as well as time to think about what we were doing in the lab and refuel.

At Columbia, I recruited a number of postdocs, who made critical contributions to our work on migration—Wei-Qing Gao from Moo Ming Poo’s lab at Columbia, Gord Fishell from Derek van der Kooy’s lab in Toronto, Renata Fishman from the Breedlove lab at Berkeley, and Urs Gasser from Switzerland. Wei-Qiang Gao and I began to work on GC proliferation, a project that we did in collaboration with Nat Heintz, a molecular biologist at Rockefeller, whom I met through Jeff Noebels at a meeting on cerebellar genetics at the Jackson Lab. Wei-Qiang Gao would also carry out the first in vitro chimera “mix and match” experiments that proved that the weaver gene acted autonomously in the GC to cause deficits in migration along glial fibers. Rodolfo Rivas joined the lab about that time and developed methods to implant fluorescently labeled (PKH26) purified GCs into developing cerebellar cortex to be able to see them migrate in situ. (This work preceded genetically encoded fluorescent tags for marking cells.) When I showed Rodolfo’s work at the Columbia Neurobiology retreat at Woods Hole, Eric said, “You made that up, Mary Beth!” It was a stunning achievement for that time. With Rodolfo’s labeling methodology, Wei-Qing implanted labeled GCs purified from either wild-type or weaver cerebellum into the cerebellum of the other genotype to show that the gene acted autonomously in vivo as well. Those experiments settled a long-standing argument about whether the weaver defect, which was a major genetic model for CNS migration, resulted from defects in the neuron or the glial cell. Our finding that the CNS migration deficit was in the neuron, not the glial cell, provided the first indication that the navigational instructions for migration were in the neuron. This conclusion was later strengthened by Renata Fishman’s beautiful experiments purifying glial membranes and coupling them to glass fibers the same diameter as the glia and showing that neurons could migrate perfectly well on “dead” glial membranes.

Gord Fishell took the molecular experiments on migration a giant step forward when he used a Berg chamber to perfuse antigen binding (FAB) FAB fragments of anti-ASTN1 antibodies onto actively migrating GCs. That work showed that antibodies against ASTN, but not integrins, which were everyone’s favorite adhesion protein at the time, blocked glial-guided migration. It would become clear later that although integrins are the key adhesion proteins for nearly all fibroblast and epithelial cell migrations, and even growth cone motility, they do not function in glial-guided migration. Thus, ASTN1 appeared to be a substitute for integrins as the key adhesion receptor. Gord went on to use EM, in collaboration with Carol Mason, to show that the ASTN protein localized to the migration junction with the glial fiber in actively migrating GCs. Subsequently, Renata showed that glass fibers coated with fibronectin, another popular substrate for nonneuronal cell migration, could also support GC migration. Because fibronectin is not expressed on glial cells that support migration, we reasoned that it did not function in glial-guided migration during brain development.

The development of a culture system for purified cerebellar GCs and astroglia provided a powerful approach for studying glial-guided migration in other cortical regions. It also provided an assay system for candidate proteins that function in glial-guided migration. From Jim’s early video recordings, we learned the mode of movement of CNS migration and from Carol’s EM we identified the ultrastructure of migrating neurons and their junction with the glial fiber. The mode of movement was saltatory, with the neuron cycling between adhering to the glial guide and letting go to step forward every three minutes. As the cell moved forward, the nucleus remained in the rear of the cell, and the cell body alternated between an elongated lemon-like form when the neuron stretched out along the glial fiber to a rounded form as the neuron detached and glided forward. The rhythmic movement of the neuron along the glial guide roughly resembled that of an inchworm moving along a slender tree branch. Importantly, the mode of migration that we observed in our in vitro model approximated what Pasko had seen in static images of cells in fixed tissue. This finding would enable us down the road to carry out a long series of experiments to test the function of specific receptors and signaling pathways in migration.

Before moving on to examine the molecular mechanisms of migration, we carried out further experiments on whether the navigational instructions for migration were in the neuron, this time studying migration in the hippocampus and cortex. For this work, Urs Gasser purified neurons and glia from cerebellum, hippocampus and cortex, cultured them with glia from their homotypic brain region, imaged their migrations in vitro and then mixed and matched neurons and glial from different brain regions. Because glial-guided migrations produced very different patterns of neuronal layers in the three brain regions, it was possible that the glial fibers encoded the navigational instructions that gave rise to structural differences among cortical regions. Urs’s experiments showed a remarkable result. All of the neurons in all of the brain regions, whether on homotypic or heterotypic glia had exactly the same mode of movement, cadence, and detailed features we had shown for cerebellar neurons. We therefore called migration “riding the glial monorail,” where the diameter of the fiber and receptor systems on the fiber were critical for movement, not for guidance to a certain spot. Renata Fishman’s experiments confirmed this “Bauhaus” model when she showed that neurons could migrate with the same features on 1 mm glass fibers coated with glial membranes.

Neuroscience at Columbia was especially exciting in that period, with postdocs like Marc Tessier-Lavigne, Mary Hynes, Marysia Placzek, and Andy Furley in the Dodd-Jessell labs; Seth Grant in the Kandel lab; and Linda Buck in the Axel lab. At that time, the Columbia neuroscience community was small enough that we all fit into a moderate-size conference room for Friday morning progress meetings, among the Axel, Kandel, Jessell, Dodd, Mason, and other labs. I had wonderful colleagues, indeed. Beyond that, I had a number of women as close colleagues, especially Carol Mason and Jane Dodd.

As I mentioned earlier, it was a meeting of the tenured women faculty at Columbia, at which 60 women were trying to arrange their chairs into a circle, that reminded me of the women’s college I had attended and of what a woman’s voice in science might be. Sociological studies at the time were suggesting that little boys liked building towers and hierarchies, whereas little girls preferred circles. For me, Deborah Tannen’s sociological studies on gender differences between boys and girls was summed up in an anecdote about what a young boy versus a young girl would do when stressed. She wrote that when a young boy would become frustrated, he would say, “If you don’t stop, I am going to tell Billy, and he is going to beat you up.” The girl, however, would say, “If you don’t stop, I am gong to tell Katie, and she is going to tell all of our friends!” She termed it circles and towers. The story reminded me of the tenured women at Columbia putting the chairs into a circle. I mused about whether these gender differences also reflected different ways of thinking about science, about whether my interest in cell-cell communication and Tom Jessell’s interest in hierarchical models of development were, in part, gender-based.

Although Columbia was an invigorating place with great colleagues, I soon began to realize that not knowing molecular biology was a major handicap. As mentioned, I had begun to collaborate with Nat Heintz at Rockefeller earlier during Wei-Qiang Gao’s experiments on GC proliferation. Nat was a molecular biologist interested in how transcriptional regulation generated so many different cell types in the CNS. As we had developed methods to purify large numbers of GCs, it was a perfect system to generate a CNS cell-type-specific cDNA library, one that likely would be a richer library than single-cell libraries. So, Nat and I joined forces to make the GC cDNA libraries. Soon, Torsten Wiesel recruited me to Rockefeller, and I eagerly moved because of the chance to equip my lab for molecular studies and to learn molecular biology from Nat and his colleagues.

Rockefeller University: Molecular Mechanisms

When I moved to Rockefeller in 1992, I was the first female head of laboratory. Given Rockefeller’s reputation as a male bastion, I might not have moved there except for the work I was doing with Nat and for Torsten, whom I had known well at Harvard. Although the science at Rockefeller was stunning, it was a bit of a shock leaving my female colleagues at Columbia and going it alone at Rockefeller. Indeed, soon after I arrived, one of the senior professors invited me to lunch to clue me in that driving a Jeep Cherokee with a sea kayak on top was not appropriate for the first female Rockefeller professor. It would be a long road to bring great women to Rockefeller, one aided by the absence of departmental structure, and in the end, by the quality of science. Today, although we would like to have more women, we have a number of world-renowned female professors, including Cori Bargmann, Titia De Lange, Elaine Fuchs, Mary Jean Kreek, Jue Chen, and Leslie Voshall, as well as a number of remarkable junior female faculty members, including Vanessa Ruta, Agata Smogorzewska, Li Zhao, and Priya Rajasethupathy.

Soon after I moved to Rockefeller, I was asked to make a scientific presentation to the board of trustees. Naturally, I focused most of the talk on our new work on neuronal migration. David Rockefeller, who was the chair of the board, listened carefully and then asked, “But why would the young neuron want to leave the place where it was born?” Although I thought to myself that the young cell might not have left had it been born at the Rockefeller family estate in Pocantico Hills, that question still endures as one of the central mysteries of brain development.

GC cDNA Libraries: Discovery of GC Developmental Genes

My move to Rockefeller did indeed lead us into molecular experiments, starting with the generation of GC cDNA libraries with Nat that would result in the cloning of some 80 genes that functioned in cerebellar development. The first of these was Astrotactin (Astn), which Chen Zheng, my first Rockefeller graduate student, cloned. The characterization of Astn RNA, by zoo blots, which no one does anymore, showed the interesting fact that Astn is expressed in vertebrates down to frogs, but not in invertebrates. That was gratifying as neuronal migration along glial fibers occurs only in vertebrates. Kathy Zimmerman also joined the lab soon after my arrival, having finished a postdoc with David Anderson at Cal Tech. Kathy made critically important contributions to my understanding of molecular biology and especially of transcription factors in neural specification. Although Kathy came to work on molecular projects in my lab, it soon became evident that she should run her own lab, so she set up a small group working on transcription factors in early frog neural development. Kathy would be a critical collaborator and wonderful colleague for many years to come, until her move to Lehigh University 15 years later.

We also continued to focus on imaging CNS migrations, as Gord moved with me to Rockefeller, where he and Rodolfo Rivas finished experiments on ASTN1 in migration and on characterizing the cytoskeleton of migrating neurons. Gord also did some nice experiments on progenitor cell movements in the ventricular zone (VZ) of the cortex, a topic that was hotly debated in response to Pasko’s protomap hypothesis. Gord’s live imaging of young neurons in the cortical VZ showed that progenitor cells underwent extensive lateral cell movements prior to leaving the zone via glial-guided migrations. This demonstrated that the neuroepithelial cells in the VZ were not hardwired into a given location, but, like cells in other epithelia, could freely move in the lateral plane.

Dorsal Patterning of the Cerebellum: Genetic Studies on Weaver and Dreher

Although we did a number of other migration experiments, now using gene knockout methods instead of naturally occurring neuronal mutations, Phyllis Faust’s analysis of mice lacking Pex5 among them, we turned our attention to the early development of the cerebellar anlagen. This was due in large part to the arrival of Janet Alder, who had worked with Moo Ming Poo at Columbia. Janet and I became interested in the early steps in GC specification and whether dorso-ventral patterning mechanisms, which Janni Nusslein Volhard and Eric Wieschaus pioneered in flies and zebrafish and Tom Jessell mapped in the mouse spinal cord, might be acting in cerebellar development. After all, the puckering of the rhombic lip above the fourth ventricle, where the cerebellum emerged, displaced the anlagen from a dorso-ventral orientation to a medio-lateral orientation.

To examine whether GCs were specified by dorsal signals, Janet collaborated with Kevin Lee from the Jessell lab to probe the role of bone morphogenetic proteins (BMPs) in cerebellar development. We were interested in BMPs because Kevin and Tom had shown that roof-plate-derived BMPs induced the specification of Math1-positive dorsal spinal cord interneurons. As GCs expressed Math1, and as Huda Zoghbi showed that Math1 was critical for GC specification and development, we reasoned that GCs were also “dorsally” specified neurons. Janet and Kevin showed that BMPs localize to the choroid plexus adjacent to the rhombic lip and to the lip itself, the site of origin of GCs. They went on to show that treatment of ventral cerebellar cells with BMPs induced a GC specification pathway. Thus, segregation of GC progenitors (GCPs) into the rhombic lip, where they would be exposed to BMPs, provided a mechanism for the specification of a GC identity. Janet went on to show that rhombic lip cells, but not VZ cells, purified from the embryonic anlagen and implanted into the postnatal cerebellar cortex, gave rise exclusively to GCs, thus showing that GCs were specified very early in development, even though clones of GCPs continued to expand to generate the phenomenal numbers of GCs seen in the adult cerebellum.

To further address dorso-ventral patterning of the cerebellum, Kathy Millen, who had trained with Alex Joyner in Toronto, and Jim Millonig, who had arrived from Shirley Tilghman’s lab at Princeton, studied the spontaneously generated Dreher mouse mutant, a mouse genetic model in which populations of dorsal interneurons did not develop. Kathy and Jim used positional cloning to map the area around the dr/dr locus and to identify the dr gene as Lmx1a. They went on to show in a beautiful Nature paper that mice lacking dr/dr lack a roof plate all along the neural axis, which led to the absence of dorsal interneurons in the spinal cord and a reduction in the population of GCPs in the rhombic lip of the cerebellar system. This work extended the model of dorsal signaling in neuronal specification to rostral areas of the CNS, including the cerebellum.

Jim and Kathy then used positional cloning to identify the weaver gene (wv/wv), carrying out the laborious crosses required for cloning at that time. As the original weaver mutant mouse had been lost, they scraped tissue off of slides from Sidman’s department to harvest DNA. Interestingly, several candidate genes in the area mapped around the wv/wv locus—Big Brain and the GIRK2 channel. Being a developmental neuroscience lab, we focused on Big Brain. Lily Jan’s lab, which was also working to clone weaver, guessed that it was the GIRK2 channel, and they turned out to have made the lucky guess. We then joined forces with Henry Lester at Caltech to study the physiology of wv/wv GCs in culture and were able to show that blocking the leakage through the GIRK2 channel rescued the death of the GCs, thus proving that the Jan lab’s identification of Girk2 as weaver was correct.

During the same time frame, I was fortunate to have Richard Wingate join the lab from Andrew Lumsden’s lab at King’s College in London. Richard was an expert on chick quail chimeras, pioneered by Nicole Le Douarin years earlier. Richard carried out chick quail chimera experiments to map the origin of the cerebellar cortex, using the recently discovered marker for rhombomere 1, Hoxa2. His fate-mapping experiments showed that the cerebellum arises entirely from rhombomere 1, not partially from the presumptive midbrain territory as had been thought earlier. Richard also showed that a population of cells in the rostral rhombic lip that had been thought to only generate the GCPs, generate precursors that migrated to the basilar pons. It was great fun to have chick quail experiments in my lab.

In that same period, Daniver Morales, a postdoc from Chile, mapped transcription factor expression in the early cerebellar anlagen of the chick and the mouse. Dani discovered markers for immature neurons of the cerebellar nuclei, for Purkinje cells and for GCPs as they migrate out of the rhombic lip. That work also showed the remarkable migration patterns of the cell that give rise to the cerebellar nuclei, which first migrate onto the surface of the anlagen and then migrate off of the surface into the deeper zone in concert with the migration of GCPs from the rhombic lip across the surface. Dani also showed that some of the Math1+ cells from the rhombic lip migrate into the cerebellar nuclei, a result that Huda Zoghbi also demonstrated in beautiful fate mapping experiments. Dani’s work went on to provide the first direct evidence that immature Purkinje cells migrate along brain lipid-binding protein positive radial glial fibers from the VZ into the upper aspects of the thickening anlagen.

During the 1990s, I became involved in SfN, first as the founding chair of a committee to promote women in neuroscience, then as a member of the SfN Council, and finally as treasurer. Although I am no financial expert, as treasurer, I realized that we urgently needed a long-term financial plan that included a reserve fund to cover the possibility that a natural disaster, like a hurricane, could cancel the annual meeting, the main source of revenue. Torsten Wiesel, who was president of Rockefeller then, was a huge help in that effort as he had the investment officer at Rockefeller help me make contacts in the New York investment world and get the program going. I am proud to say that the fund is now worth many millions of dollars and serves as a critical financial support for the SfN.

In addition to studying migration in the lab at that time, we continued my long-standing interest in neuronal regulation of glial differentiation. Kim Hunter, who joined the lab from King’s College and St. George’s in London, did interesting work showing that radial glial transformation is bidirectional, as factors purified from embryonic brain could transform mature astrocytes back into radial glial cells. We spent considerable effort trying to isolate the protein from the culture medium of embryonic neurons, but we were never able to get enough material to identify the protein. This project should be revisited, given the advances in mass spectroscopy. Kim’s work followed my earlier work showing that the ratio of neurons to glia dramatically changed glial morphology, with higher ratios inducing the glia to form highly elongated fibers that support neuronal migration. Over the years, we have consistently observed interdependence between neuronal and glial differentiation. Studies on a number of mouse mutants with defects in neuronal migration or differentiation also revealed indirect, nonautonomous effects on radial glial differentiation.

Functional Studies of Genes in GC Development

During the mid to late 1990s, we used two approaches to discover new genes involved in GC development. The first was screening for evolutionarily conserved genes that function in axon outgrowth and migration and the second was to use GC gene expression data to identify important genes. Toshi Tomoda, a postdoc from Tokyo, was the first person in the lab to examine evolutionarily conserved genes from C. elegans in GC development. Toshi studied the Unc51 gene, Unc51.1, in the mouse, which he showed functions in parallel fiber outgrowth. Toshi also established powerful new general methodologies for examining gene function in GC differentiation, including transducing GCPs with retroviral constructs to express genes in vitro. He further discovered that he could simply incubate neonatal cerebellar slices with retrovirus to selectively express genes in proliferating GCPs ex vivo. The use of retroviruses to express genes of interest in GCPs has been a powerful methodology for a wide variety of studies.

Toshi also worked with Rupal Bhatt, a wonderful MD-PhD student in my lab, on his Unc51.1 project and on her thesis project to explore whether receptor tyrosine kinases (RTKs) were important for GCP differentiation. Rupal discovered an especially interesting RTK that she cloned from GCPs: discoidin domain receptor 1 (DDR1). DDR1 is an orphan receptor that contains an RTK domain and an extracellular discoidin (lectin) domain. Rupal and Toshi, working together, overexpressed a dominant negative form of DDR1 in proliferating GCPs and found that this blocked axon outgrowth in vitro. Rupal went on to show that DDR1 functions after GCs begin to extend axons, suggesting it is involved in the maintenance, not initiation, of axon outgrowth. Thus, Ddr1 came on slightly later than Unc51.1, after GCPs committed to cell-cycle exit and functioned in the maintenance of parallel fiber extension rather than initiation of axon outgrowth. Rupal also showed that DDR1 binds to collagen in the pia, suggesting the importance of the three-dimensional (3D) geometry of the cerebellum to patterning differentiation signals.

One of the nicest aspects of Rupal’s DDR1 paper was her beautiful imaging of granule neurons in ex vivo slices, images that showed both the extending parallel fiber axon and the descending migration process. We processed those images in 3D with a Silicon Graphics Program Voxel View, which Nick Didkovsky, a brilliant computer specialist, set up for us in the lab. Nick would go on to make seminal contributions to our videos and later to designing the GENSAT (Gene Expression Atlas) website.

Toshi teamed up with Jee Hae Kim, a postdoc who had trained with Rick Huganir at Johns Hopkins, to demonstrate that Unc51.1 binds to SynGAP, a Ras regulator, and also to a PDZ containing scaffolding protein, Syntenin, which binds a Ras regulator Rab5 GTPase. This was the first indication that GCP process outgrowth involved Ras-like GTPase activity as well as endocytic pathways. The latter fit well with our studies on ASTN2, described later, that showed a key role for receptor trafficking in neuronal locomotion along glial fibers. Receptor trafficking was an early step in axon extension. Toshi also initiated a collaboration with Akira Sawa at Johns Hopkins to use our methodologies to study the role of the schizophrenia-associated gene DISC1 in brain development. Those experiments were the first in my lab that related directly to neurodevelopmental disorders.

Along the way, we continued our efforts to define the molecular mechanisms of GCP migration, especially the role of ASTN in migration, with a graduate student Gunnar Dietz generating the first knockout mouse lacking Astn1. Niels Adams, a wonderful neuroanatomist, who had trained with Ray Guillery at Oxford, analyzed GC migration in mice lacking Astn1. As we had anticipated, those experiments showed a severe deficit in GC migration along glial cells, a deficit that indirectly affected Purkinje cell development, as the Purkinje cells tilted out of the sagittal plane when GCs migrated slowly.

The GENSAT Project

About that time, Nat’s lab came up with bacterial artificial chromosome (BAC) methodology, which enabled us to generate enhanced green fluorescent protein (EGFP)–labeled genes by homologous recombination. Nat had the idea to do a very large contract, which NIH called GENSAT, to map cell-type-specific gene expression for hundreds of CNS genes. My role as a co–principal investigator of GENSAT was to develop the anatomy methods to carry out large-scale brain sectioning of hundreds of lines of mice and also to image the EGFP in the CNS of the mice at cellular resolution. Assembling the large team to do this work and setting up the imaging and designing the website with Nick was a huge project. Although Nat and I spent almost all of our time on the project, we gave the mice away and published only two core papers, a Nature paper describing the project and a later paper describing the use of BAC methodology to make CRE lines for specific genes. We, and many other labs, would use those lines to generate cell-type-specific conditional knockout mutations. The GENSAT project was one of many projects that I enjoyed doing with Nat, a wonderful friend and colleague. His interest in molecular mechanisms and mine in understanding gene function have dovetailed in many joint projects.

The GENSAT project revealed a large number of developmental pathways that had not been recognized previously, both in the spinal cord and in the developing brain. Hillary Osheroff, a graduate student, used two lines of GENSAT mice, Tg(Pde1C-EGFP) mouse embryos, in which the EGFP transgene labeled all preplate neurons, and Tg(Girk4-EGFP) mouse embryos, where EGFP expression was restricted to Cajal–Retzius neurons. This allowed us to examine gene expression during preplate patterning, an important transient step during early stages of cortical development. Her studies showed more than 200 genes enriched in preplate neurons, including genes involved in transcription, cortical development, cell and axon motility, protein trafficking and steroid hormone signaling. Additionally, Hillary identified 10 genes in preplate neurons that were related to degenerative diseases of the cerebral and cerebellar cortex.

Through the years, I greatly enjoyed working with wonderful postdocs in my lab and serving on the boards and review committees of three major neuroscience scholar awards for young faculty: the John Merck Scholars Board and the review committees for the McKnight Neuroscience Program and the Pew Scholars Award. Few meetings were as exciting as those meetings, hearing young scientists talk about their innovative work and, over a period of years, watching their research programs develop.

The Cerebellum and Cancer

The arrival of David Solecki, who had trained with Eckhard Wimmer at Stony Brook in the early 2000s, led to work on GCP proliferation and the role of GCPs in medulloblastomas. David and Toshi followed up on an observation by a graduate student, Xiao Lin Liu, that Notch 2 was highly represented in the GC cDNA library. Their work showed that NOTCH2 activation maintained GCP proliferation through the JAG2 ligand. Although David’s finding on NOTCH2 was overshadowed by the discovery and subsequent publication that SHH promoted GCP proliferation, recent studies show a link between NOTCH2 activation and medulloblastomas.

We then went on to study other regulators of proliferation, including cell cycle regulators, comparing normal GCPs and medulloblastoma. In GCPs, Ink4c is expressed in normal cells, a fact that led Martine Roussel and colleagues to analyze whether a loss of Ink4c would lead to medulloblastoma. This led to a wonderful collaboration with Martine’s lab, showing that purifying the GCPs revealed a much larger change in proliferation than was evident in neuroanatomical studies alone. Sandrine Anne and Jee Hae Kim, postdocs in my lab, would go on to show that Wnt 3 is a negative regulator of GCP proliferation, and Martine would show that it also represses medulloblastoma formation. The work with Martine was gratifying because it brought me back to working on cancer again, completing the circle with my graduate school research on tumor cell regulation.

At about the same time, Enrique Salero, who came to the lab from Mexico City, began to use the developmental signals we and others had identified as functioning in GC development to develop a protocol to differentiate mouse embryonic stem cells into GCs. Recapitulating developmental signals worked very well for generating mouse GCs from embryonic stem (ES) cells, which was gratifying. Enrique went on to show that he could implant EGFP-labeled ES-derived GCs back into mouse cerebellar cortex and show that the labeled cells would migrate into place and incorporate into the cortical architecture. We are now using this approach to test whether human embryonic stem (hES) cells differentiated to a cerebellar neuron fate will integrate into mouse cerebellum. That is a large effort directed toward treatment of human neurodegenerative diseases like Ataxia-telangiectasia.

By the early 2000s, although Mary Jean Kreeke and Titia De Lange had been promoted to professor, and Elaine Fuchs (whom I had known at Princeton) had been recruited to Rockefeller from the University of Chicago, the number of female professors remained very small. Things began to change when we were fortunate enough to recruit Cori Bargmann to Rockefeller. Cori helped bring a number of young women to Rockefeller through the open search process started by Paul Nurse, and she helped promote the careers of our young female faculty, including Leslie Vosshall (Leslie is a wonderful scientist, who has been critical to the effort to bring more young women neuroscientists to Rockefeller), Vanessa Ruta, and Priya Rajasethupathy.

Cori has also been an especially insightful colleague for my work. About the time she arrived, I became interested in examining whether genes that had been identified as migration genes in C. elegans might also function in vertebrate CNS migrations. Early on, I had used spontaneous mouse mutations and biochemistry to discover genes and pathways involved in migration. As we did not do human genetics, it seemed that studying migration genes identified in C. elegans might be a way to discover novel genetic pathways in vertebrate migration. Stephanie Schneider, a postdoc from Cologne, wanted to study mig-13, a gene that Cynthia Kenyon had discovered in C. elegans. Using EGFP-tagged mice that we generated in GENSAT, Stephanie found that Lrp12/Mig13, a mammalian gene related to mig-13, was expressed in a subpopulation of preplate neurons that migrate tangentially in the preplate layer, a transient layer that forms early in cortical development, as well as in some axon pathways. She went on to show that Lrp12/Mig13-positive cells revealed changes in cell polarity as preplate neurons align into a pseudocolumnar pattern before descending into the newly forming subplate layer. She also showed that these changes in cell polarity do not occur in reeler mice, another spontaneous mouse mutant that has been used extensively to study neuronal migration. Yung Lie, who came to the lab from Cynthia’s lab, carried out some interesting experiments in C. elegans in my lab, with Cori’s help, which was fun.

mPar6 Signaling in Glial-Guided Migration

David’s gene expression profiling of GCPs mentioned earlier ushered in another wave of work on the mechanisms of neuronal migration. In the GC data sets, he noticed that the expression of a recently discovered conserved polarity gene, mPar6, increased as GCs left the cell cycle. Using immunocytochemistry, David showed that mPar6 localized to the centrosome of migrating neurons. To study this in more detail, he labeled mPar6 with Venus, a new tag that Roger Tsien had developed that was twentyfold brighter than GFP. This was important because it allowed us to express lower amounts of tagged protein than GFP, which turned out to be a critical factor. With Venus-tagged mPar6 and spinning disc confocal imaging, David was able to prove that the signaling complex localized to the centrosome and that mPar6 activity controlled the speed of neuronal migration along the glial fiber. This also demonstrated that the machinery for migration was perinuclear and not at the tip of the leading process.

David next looked more closely at the cytoskeletal mechanisms underlying GC migration and revealed a previously unappreciated role for actin dynamics in this process. In a wonderful set of experiments, he showed that myosin II motors and F-actin dynamics drive the coordinated movement of the centrosome and soma during GCP glial-guided neuronal migration. Those experiments used real-time imaging combined with specific activators and inhibitors of myosin II assembly to show that activation of myosin motors accelerated the speed of migration, while inhibition slowed migration. David also carried out four-dimensional volumetric mapping of F-actin in the migrating GC and showed dynamic rearrangements in the actin cytoskeleton in the proximal aspect of the leading process, near the centrosome. At the time that David was doing these experiments, Eve Govek joined the lab, after training with Linda Van Aelst at Cold Spring Harbor, and collaborated with David on studies on Par6 regulation of the cytoskeletal dynamics during GC migration. David and Eve demonstrated that mPar6 regulates myosin activity by regulating myosin light chain phosphorylation. Thus, acto-myosin contractility in the proximal leading process appeared to pull the migrating neuron forward along the glial guide. These experiments were the clearest indication to date of the specific role of cytoskeletal dynamics and their control by the mPar6 signaling complex in neuronal migration.

While we were studying mPar6 signaling in migration, Perrin Wilson, a graduate student, and Bob Fryer, a child neurologist, together with Toshi, cloned a second member of the Astn gene family, Astn2. Although the peptide sequences of ASTN1 and ASTN2 are very similar, their expression patterns differ, with ASTN1 being expressed only during early phases of development when migration is ongoing and ASTN2 expression continuing into adulthood. Our expectation that the two proteins would be redundant turned out not to be the case. First, far less ASTN2 is expressed on the neuronal cell surface. Second, in functional experiments, ASTN2 did not appear to function as an adhesion protein. Indeed, our imaging experiments showed that ASTN2 regulates the trafficking of ASTN1 during migration rather than as a redundant adhesion receptor. These experiments were the first to suggest that endocytosis is an important regulator of migration, by removing the adhesion receptor ASTN1 as the neuron takes a step along the glial fiber. Hourinaz Behesti, who came from Jane Sowden’s lab at University College London, is now actively studying the role of ASTN2 in synaptic function in the cerebellum. The finding that human CNVs in Astn2 are associated with autism, intellectual disability, and language disability has spurred this work. It is especially interesting to understand how a gene that is predominantly expressed in the cerebellar cortex might function in higher cognitive functions.

About that time, we also started a project with Nagi Ayad at the University of Miami, to study the role of the APC/C complex in GCP cell cycle exit. Yin Fang, my wonderful lab manager, and Eve collaborated with Clara Penas in Nagi’s lab to show that Casein kinase 1 (CK1d) functions in GCP proliferation and that the ubiquitin ligase APC/C targets CK1d for degradation by the proteasome. With Martine Roussel, Nagi and I also showed that CK1d is important for medulloblastoma formation. That was our last foray into the area of the cerebellum and cancer biology until a newly established collaboration with Agata Smogorzewska, a wonderful cancer biologist here at Rockefeller. A joint graduate student, Danielle Keahi, and Samer Shalaby, a postdoc in Agata’s lab, are currently studying DNA damage pathways during GCP proliferation and in medulloblastomas, a surprisingly understudied area.

Changes in Chromatin Gene Expression during Cerebellar Circuit Formation

As part of our emerging interests in stem cell biology, and continuing work on gene expression during development, we decided to use Nat’s BAC TRAP methodology to carry out a large-scale examination of GC gene expression over development. One major goal in that work was to obtain a genomic fingerprint of GCs to use not just for understanding development but also for analyzing whether stem cells differentiated to a cerebellar neuron fate were very close to native cells at the level of the full transcriptome, rather than a handful of cellular markers. Keisha John, who came from Linda Van Aelst’s lab at Cold Spring Harbor, started those experiments, joined by Xiaodong Zhu, a postdoc from China, and Eve. To carry out the bioinformatics, we collaborated at the Broad with Jill Mesirov and Pablo Tamayo, who used metagene analysis, a method to use matrix factorization to cluster genes into a half dozen or so metagenes. To our surprise, those experiments revealed pivotal changes in virtually all chromatin remodeling genes during the time frame when the cerebellar circuitry forms. Among those genes, we showed that the Tet genes, which generate 5hmC marks, are crucial as increased 5hmC correlated with increased gene expression. Interestingly the main genes that 5hmC activated were axon guidance genes and ion channel genes, both of which function in forming the circuitry. Knockdown of the Tet genes impaired the transition from migrating GCPs to GCs with dendrites, suggesting a key role in forming connections with ingrowing mossy fibers. We are following up on those experiments in Purkinje cells and are testing whether knockout of specific chromatin remodeling genes impairs either synapse formation or other aspects of circuit formation.

Current Work

Currently, we still focus on mechanisms of neuronal migration as well as on the role of ASTN2 in neurodevelopmental disorders and on efforts to generate human cerebellar neurons from hES cells. Eve is using genetic approaches to study the Rho GTPase Cdc42 in GCP migration. That work, which has been submitted for publication, shows that Cdc42 regulates neuronal polarity during GCP axon formation and glial-guided migration. Remarkably, a conditional loss of Cdc42 in GCs results in abnormalities in the foliation of the cerebellum, revealed by the new iDISCO clearing method and light sheet microscopy, which we did in collaboration with Marc Tessier-Lavigne, and a loss of a pseudocolumnar organization of GCPs in the external granular layer. In migrating GCPs, cells lacking Cdc42 fail to form the migration junction with the glial fiber, which slows migration dramatically. By phosphoproteomics, a loss of Cdc42 results in lower phosphorylation of targets that include the polarity protein and actin regulatory proteins PAK1/4. In a second migration project, Zachi Horn (who trained at the Karolinska in Stockholm) is using biochemical and genetic studies to identify the long-sought ligand for ASTN1, which Zachi has identified as CDH2. He is currently carrying out biophysical measurements of the binding of ASTN1 and CDH2 in collaboration with Rob Gilbert’s group at Oxford. Micha Hanzel, who recently arrived from Richard Wingate’s lab in London, is characterizing an Astn2 loss of function mutant that Zachi generated with Shiaoching Gong from Nat’s lab.

As mentioned, Hourinaz Behesti’s experiments show that ASTN2 modulates synaptic strength at later stages of development, by controlling the trafficking and degradation of surface proteins, including synaptic proteins. Her work includes studies of patients that have ASTN2 CNVs as well as detailed studies of the function of ASTN2. The latter shows that ASTN2 localizes to vesicles, binds to synaptic proteins, and regulates receptor trafficking and protein degradation. These functional insights are provocative, because they offer clues on molecular pathways involved in ASTN2-related neurodevelopmental disorders, such as intellectual disability and autism.

To generate human cerebellar neurons, Dave Buchholz, who worked with David Clegg and Pete Coffey at the University of California, Santa Barbara on retinal stem cells, is developing methods to differentiate hES cells into human Purkinje cells. That has been far more difficult than I anticipated as it turns out that human cells are quite different from mouse cells. Dave will use the TRAP methodology to examine gene expression patterns of the hES-derived Purkinje cells and to compare gene expression patterns of mouse and human Purkinje cells. He is also using the implantation methods that we developed for mES-derived GCPs to test whether human Purkinje cells will integrate into the mouse cerebellar cortex.

In addition to these main lines of work on cerebellum, Sasa Jareb a graduate student in Bob Darnell’s lab, is working on cell-type-specific 3’UTR isoform expression; Arif Kocabas, a postdoc from Mary Hynes’s lab, is using CRISPR methods to knock out chromatin remodeling genes; and Isaac Marin-Valencia, who recently arrived from Joe Gleeson’s lab, is working on metabolic pathways and cerebellar development. Thus, we still have plenty of exciting projects in the lab.

I also still have an active collaboration with Nat Heintz, who has been my main colleague here at Rockefeller for so many years. I am also enjoying collaborating with Court Hull, an assistant professor at Duke, who is carrying out electrophysiological studies on Astn2 mutant mice, as well as with Mustafa Sahin at Harvard, with whom we are studying mTor in autism pathways associated with cerebellar Purkinje cells.

I am so lucky to have so many wonderful colleagues at Rockefeller, including Torsten Wiesel, Nat Heintz, Cori Bargmann, Charles Gilbert, Mike Young, Rod MacKinnon, Jeff Friedman, Vanessa Ruta, Gaby Maimon, Winrich Freiwald, Bob Darnell, Bruce McEwen, and Agata Smogorzewska, who have contributed so much to my work.

Looking Back: Reflections

Reflecting on my life in science, three themes have endured: cell migration (imaging and molecular mechanisms), cerebellar development (genetics and cell biology), and cerebellar neurogenesis (including forays into cancer). In this age of translational neuroscience, a new area is emerging—understanding how cerebellar development relates to neurodevelopmental disorders, such as autism and intellectual disability. Although neurodevelopment is not as popular as it once was, I believe there are still many major problems to solve, and cerebellar development remains my core interest. Harvard, Columbia, and Rockefeller made important contributions to my career, through the stimulating and enduring collaborations and wonderful friendships, most of which have persisted for many years. I am grateful to Dick Sidman for teaching me about cerebellar development, to Pasko Rakic for introducing me to GC migration, to Torsten Wiesel for his unwavering support since my Harvard days, to Carol Mason for our exciting work together to image CNS glial-guided migration, to Carla Shatz for so many years of shared interests in development, and of course, to Nat Heintz, who brought so many innovative molecular approaches to my work on cerebellar development and with whom I have done so many critical experiments. Moving to Rockefeller was certainly a boon to my work for all these many years, thanks in no small part to presidents like Torsten Wiesel, Marc Tessier-Lavigne, and now Rick Lifton.

References

Zhu X, Girardo D, Govek EE, John K, Mellen M, Tamayo P, Mesirov J, Hatten ME. 2016. Role of Tet1/3 Genes and Chromatin Remodeling Genes in Cerebellar Circuit Formation. Neuron 89:100–112.

Penas C, Govek EE, Daniel M, Fang Y, Wang W, Rahaim RJ, Bibian M, Kawauchi D, Finkelstein D, Han J-H, Li B, Robbins DJ, Malumbres M, Roussel MF, William R, Roush WR, Hatten ME, Ayad NG. 2015. Casein Kinase 1d Is an APC/CCdh1 Substrate That Regulates Cerebellar Granule Cell Neurogenesis. Cell Reports 11:1–12.

Anne SA, Govek EE, Ayrault O, Kim J-H, Zhu X, Murphy D, Van Aelst L, Roussel MF, Hatten ME. 2013. Wnt3 Inhibits Cerebellar Granule Neuron Progenitor Proliferation and Medulloblastoma Formation via MAPK Activation. PLoS One Nov 26;8(11):e81769.

Govek E, Hatten ME, VanAelst L. 2011. The Role of Rho GTPase Proteins in CNS Neuronal Migration. Dev Neurobiol 71:528–553.

Roussel MF, Hatten ME. 2011. Cerebellum Development and Medulloblastoma. Curr Top Dev Biol 94:235–282.

Schneider S, Gulacsi A, Hatten ME. 2011. Lrp12/Mig13a Reveals Changing Patterns of Preplate Neuronal Polarity during Corticogenesis That Are Absent in Reeler Mutant Mice. Cereb Cortex 21:134–144.

Wilson P, Fryer RH, Hatten ME. 2010. Astn2, a Novel Member of the Astrotactin Gene Family, Regulates the Trafficking of ASTN1 during Glial-Guided Neuronal Migration. J Neurosci 30:8529–8540.

Solecki DJ, Trivedi N, Govek EE, Kerekes RA, Gleason SS, Hatten ME. 2009. Myosin II Motors and F-Actin Dynamics Drive the Coordinated Movement of the Centrosome and Soma during CNS Glial-Guided Neuronal Migration. Neuron 63:63–80.

Osheroff H, Hatten ME. 2009. Gene Expression Profiling of Preplate Neurons Destined for the Subplate: Genes Involved in Transcription, Axon Extension, Neurotransmitter Regulation, Steroid Hormone Signaling, and Neuronal Survival. Cereb Cortex 19 Suppl 1:126–134.

Salero E, Hatten ME. 2007. Differentiation of ES cells into Cerebellar Neurons. Proc Natl Acad Sci USA 104:2997–3002.

Morales D, Hatten ME. 2006. Molecular Markers of Neuronal Progenitors in the Embryonic Cerebellar Anlage. J Neurosci 26:12226–12236.

Kamiya A, Kubo K, Tomoda T, Takaki M, Youn R, Ozeki Y, Sawamura N, Park U, Kudo C, Okawa M, Ross CA, Hatten ME, Nakajima K, Sawa A. 2005. A Schizophrenia-Associated Mutation of DISC1 Perturbs Cerebral Cortex Development. Nat Cell Biol 7:1067–1078.

Uziel T, Zindy F, Xie S, Lee Y, Forget A, Magdaleno S, Rehg JE, Calabrese C, Solecki D, Eberhart CG, Sherr SE, Plimmer S, Clifford SC, Hatten ME, McKinnon PJ, Gilbertson RJ, Curran T, Sherr CJ, Roussel MF. 2005. The Tumor Suppressors Ink4c and P53 Collaborate Independently with Patched to Suppress Medulloblastoma Formation. Genes Dev 19:2656–2567.

Hatten ME, Heintz N 2005. Large-Scale Genomic Approaches To Brain Development and Circuitry. Annu Rev Neurosci 28:89–108.

Solecki DJ, Model L, Gaetz J, Kapoor TM, Hatten ME. 2004. Par6a Signaling Controls Glial-Guided Neuronal Migration. Nat Neurosci 7:1195–1203.

Millen KJ, Millonig JH, Hatten ME. 2004. Roof Plate and Dorsal Spinal Cord Dl1 Interneuron Development in the Dreher Mutant Mouse. Dev Biol 270:382–392.

Tomoda T, Kim JH, Zhan C, Hatten ME. 2004. Role of Unc51.1 and Its Binding Partners in CNS Axon Outgrowth. Genes Dev 18:541–558.

Gong S, Zheng C, Doughty ML, Losos K, Didkovsky N, Shambra U, Nowack N, Joyner A, Lablanc G, Hatten ME, Heintz N. 2003. A Gene Expression Atlas of the Central Nervous System Based on Bacterial Artificial Chromosomes. Nature 425:917–925.

Ozeki Y, Tomoda T, Kleiderlein J, Kamiya A, Bord L, Fujii K, Okawa M, Yamada N, Hatten ME, Synder SH, Ross CA, Sawa A, et al. 2003. Disrupted-in-Schizophrenia-1 (DISC-1): Mutant Truncation Prevents Binding to Nude-Like (NUDEL) and Inhibits Neurite Outgrowth. Proc Natl Acad Sci USA 100:289–294.

Adams NC, Tomoda T, Cooper M, Dietz G, Hatten ME. 2002. Mice That Lack Astrotactin Have Slowed Neuronal Migration. Development 129:965–972.

Solecki DJ, Liu XL, Tomoda T, Fang Y, Hatten ME. 2001. Activated Notch2 Signaling Inhibits Differentiation of Cerebellar Granule Neuron Precursors By Maintaining Proliferation. Neuron 31:557–568.

Bhatt RS, Tomoda T, Fang Y, Hatten ME. 2000. Discoidin Domain Receptor 1 Functions in Axon Extension of Cerebellar Granule Neurons. Genes Dev 14:2216–2228.

Millonig JH, Millen KJ, Hatten ME. 2000. The mouse Dreher Gene Lmx1a Controls Formation of the Roof Plate in the Vertebrate CNS. Nature 403:764–769.

Tomoda T, Bhatt RS, Kuroyanagi H, Shirasawa T, Hatten ME. 1999. A Mouse Serine/Threonine Kinase Homologous To C. Elegans UNC51 Functions in Parallel Fiber Formation of Cerebellar Granule Neurons. Neuron 24:833–846.

Wingate RJ, Hatten ME. 1999. The Role of the Rhombic Lip in Avian Cerebellum Development. Development 126:4395–4404.

Alder J, Lee KJ, Jessell TM, Hatten ME. 1999. Generation of cerebellar granule neurons in vivo by transplantation of BMP-treated neural progenitor cells. Nat Neurosci 2:535–540.

Faust PL, Hatten ME. 1997. Targeted Deletion of the PEX2 Peroxisome Assembly Gene in Mice Provides a Model for Zellweger Syndrome, a Human Neuronal Migration Disorder. J Cell Biol 139:1293–1305.

Millonig JH, Millen KJ, Hatten ME. 1996. A High-Density Molecular Genetic Map around the Weaver Locus. Mamm Genome 7:616–618.

Alder J, Cho NK, Hatten ME. 1996. Embryonic Precursor Cells From The Rhombic Lip Are Specified to a Cerebellar Granule Neuron Identity. Neuron 17:389–399.

Kofuji P, Hofer M, Millen KJ, Millonig JH, Davidson N, et al. 1996. Functional Analysis of the Weaver Mutant GIRK2 K+ Channel and Rescue of Weaver Granule Cells. Neuron 16:941–952.

Zheng C, Heintz N, Hatten ME. 1996. CNS Gene Encoding Astrotactin, Which Supports Neuronal Migration along Glial Fibers. Science 272:417–419.

Hunter KE, Hatten ME. 1995. Radial Glial Cell Transformation to Astrocytes Is Bidirectional: Regulation by a Diffusible Factor in Embryonic Forebrain. Proc Natl Acad Sci USA 92:2061–2065.

Rivas RJ, Hatten ME. 1995. Motility and Cytoskeletal Organization of Migrating Cerebellar Granule Neurons. J Neurosci 15:981–989.

Gao WQ, Hatten ME. 1994. Immortalizing Oncogenes Subvert the Establishment of Granule Cell Identity in Developing Cerebellum. Development 120:1059–1070.

Feng L, Hatten ME, Heintz N. 1994. Brain Lipid-Binding Protein (BLBP): A Novel Signaling System in the Developing Mammalian CNS. Neuron 12:895–908.

Baptista CA, Hatten ME, Blazeski R, Mason CA. 1994. Cell-Cell Interactions Influence Survival and Differentiation of Purified Purkinje Cells In Vitro. Neuron 12:243–260.

Fishman RB, Hatten ME. 1993. Multiple Receptor Systems Promote CNS Neural Migration. J Neurosci 13:3485–3495.

Gao WQ, Hatten ME. 1993. Neuronal Differentiation Rescued By Implantation of Weaver Granule Cell Precursors into Wild-Type Cerebellar Cortex. Science 260:367–369.

Fishell G, Mason CA, Hatten ME. 1993. Dispersion of Neural Progenitors within the Germinal Zones of the Forebrain. Nature 362:636–638.

Kuhar SG, Feng L, Vidan S, Ross ME, Hatten ME, Heintz N. 1993. Changing Patterns of Gene Expression Define Four Stages of Cerebellar Granule Neuron Differentiation. Development 117:97–104.

Gao WQ, Liu XL, Hatten ME. 1992. The Weaver Gene Encodes a Non-Autonomous Signal for CNS Neuronal Differentiation. Cell 68:841–854.

Fishell G, Hatten ME. 1991. Astrotactin Provides a Receptor System for CNS Neuronal Migration. Development 113:755–765.

Gao WO, Heintz N, Hatten ME. 1991. Cerebellar Granule Cell Neurogenesis Is Regulated by Cell-Cell Interactions In Vitro. Neuron 6:705–715.

Stitt TN, Hatten ME. 1990. Antibodies That Recognize Astrotactin Block Granule Neuron Binding to Astroglia. Neuron 5:639–649.

Gasser UE, Hatten ME. 1990. Central Nervous System Neurons Migrate on Astroglial Fibers from Heterotypic Brain Regions In Vitro. Proc Natl Acad Sci USA 87:4543–4547.

Hatten ME. 1990. Riding the Glial Monorail: A Common Mechanism for Glial-Guided Neuronal Migration in Different Regions of the Developing Mammalian Brain. Trends Neurosci 13:179–184.

Gasser UE, Hatten ME. 1990. Neuron-Glia Interactions of Rat Hippocampal Cells In Vitro: Glial-Guided Neuronal Migration and Neuronal Regulation of Glial Differentiation. J Neurosci 10:1276–1285.

Gregory WA, Edmondson JC, Hatten ME, Mason CA. 1988. Cytology and Neuron-Glial Apposition of Migrating Cerebellar Granule Cells In Vitro. J Neurosci 8:1728–1738.

Edmondson JC, Liem RK, Kuster JE, Hatten ME. 1988 Astrotactin: A Novel Neuronal Cell Surface Antigen That Mediates Neuron-Astroglial Interactions in Cerebellar Microcultures. J Cell Biol 106:505–517.

Edmondson JC, Hatten ME. 1987. Glial-Guided Granule Neuron Migration In Vitro: A High-Resolution Time-Lapse Video Microscopic Study. J Neurosci 7:1928–1934.

Hatten ME. 1985. Neuronal Regulation of Astroglial Morphology and Proliferation In Vitro. J Cell Biol 100:384–396.

Hatten ME, Liem RK, Mason CA. 1986. Weaver Mouse Cerebellar Granule Neurons Fail to Migrate on Wild-Type Astroglial Processes In Vitro. J Neurosci 6:2676–2683.

Hatten ME, Mason CA, Liem RK, Edmondson JC, Bovolenta P, Shelanski ML. 1984d. Neuron-Astroglial Interactions In Vitro and Their Implications for Repair of CNS Injury. Cent Nerv Syst Trauma 1:15–27.

Hatten ME, Rifkin DB, Furie MB, Mason CA, Liem RK. 1982. Biochemistry of Granule Cell Migration in Developing Mouse Cerebellum. Prog Clin Biol Res 85 Pt B:509–519.

Hatten ME, Liem RK. 1981. Astroglial Cells Provide A Template for the Positioning of Developing Cerebellar Neurons In Vitro. J Cell Biol 90:622–630.

Hatten ME, Sidman RL. 1978. Cell Reassociation Behavior and Lectin-Induced Agglutination of Embryonic Mouse Cells from Different Brain Regions. Exp Cell Res 113:111–125.

Hatten ME, Scandella CJ, Horwitz AF, Burger MM. 1978. Similarities in the Membrane Fluidity of 3T3 and SV101-3T3 Cells and Its Relation to Concanavalin A- and Wheat Germ Agglutinin-Induced Agglutination. J Biol Chem 253:1972–1977.

Hatten ME, Horwitz AF, Burger MM. 1977. The Influence of Membrane Lipids on the Proliferation of Transformed and Untransformed Cell Lines. Exp Cell Res 107:31–34.

Horwitz AF, Hatten ME, Burger MM. 1974. Membrane Fatty Acid Replacements and Their Effect On Growth and Lectin-Induced Agglutinability. Proc Natl Acad Sci USA 71:3115–119.

Wilkins JR, Hatten ME, Salmirs S. 1969. Effect of Gravity on the Colonial Morphology of Staphylococci in Soft Agar. Appl Microbiol 18:680–681.

Steven E. Hyman

BORN:

New York, New York

July 25, 1952

EDUCATION:

Yale University, BA, Summa Cum Laude (1974)

University of Cambridge, MA (1976)

Harvard Medical School, MD, Cum Laude (1980)

APPOINTMENTS:

Intern in Medicine, Massachusetts General Hospital (1980–1981)

Resident in Psychiatry, McLean Hospital, Belmont, MA (1981–1984); Chief Resident (1982–1983)

Clinical and Research Fellow in Neurology, Mass General Hospital (1983–1984)

Postdoctoral Fellow (Lab of Howard Goodman, PhD), Mass General Hospital (1984–1989)

Assistant Professor to Professor of Psychiatry, Harvard Medical School (1989–1998)

Director, Harvard University Interfaculty Initiative on Mind/Brain/Behavior (1994–1996)

Director, National Institute of Mental Health, National Institutes of Health (1996–2001)

Provost, Harvard University and Professor of Neurobiology, Harvard Medical School (2001–2011)

Editor, Annual Review of Neuroscience (2002–2016)

Harvard University Distinguished Service Professor (2011–present)

Core Member, Broad Institute of MIT and Harvard; Director, Stanley Center for Psychiatric Research (2012–present)

HONORS AND AWARDS (SELECTED)

Mellon Fellowship to the University of Cambridge (1974–1976)

Mathilde Solowey Lecture in Neurosciences, National Institutes of Health (1996)

Hughlings Jackson Lectureship, Montreal Neurological Institute (2000)

Presidential Meritorious Executive Rank Award, U.S. Government, service to NIH (2000)

Member National Academy of Medicine, formerly Institute of Medicine (2000)

Fellow, American Academy of Arts and Sciences (2003)

Founding President, International Neuroethics Society (2008–2013)

Wellcome Trust Lecture in Neuroethics, University of Oxford (2010)

Fellow, American Association for the Advancement of Science (2011)

President, Society for Neuroscience (2014–2015)

Loebel Lectures, University of Oxford 2015

Rhoda and Bernard Sarnat Prize in Mental Health, National Academy of Medicine (2016)

President, American College of Neuropsychopharmacology (2017–2018)

Presidential Special Lecture, Society for Neuroscience (2017)

Steven E. Hyman has engaged in basic laboratory investigation in molecular neurobiology; has taught neurobiology to undergraduates, graduate students, and medical students at Harvard; and has served in academic and government leadership roles at Harvard, the National Institutes of Health, and the Broad Institute. Throughout his career, he has maintained a focus on basic neurobiology that has contributed to understanding the mechanisms underlying neuropsychiatric disorders—such as schizophrenia, mood disorders, and addiction—and thus to their treatment.

Steven E. Hyman

Prologue

As I embarked upon my career as an independent scientist in 1989 and set up my lab at Massachusetts General Hospital (MGH), I was anxious but also felt very lucky. I was one of three new investigators working together to start a molecular neurobiology unit at the MGH Neuroscience Center. We had nicely renovated space and startup funds from our department chair and mentor Joseph Martin, and I had obtained two National Institutes of Health (NIH) grants: one to cover my salary and the other to support my first project. The project grant supported analysis of molecular mechanisms—enhancer elements and activity-regulated transcription factors—that controlled expression of genes encoding endogenous opioid peptides. I had clinical duties, which I found highly rewarding, but I also had managed to keep tightly circumscribed. I spent one morning each week making rounds with the psychiatry residents in the MGH emergency room. The patients we saw together often suffered from serious problems, such as drug overdoses, suicide attempts, and acute psychotic episodes. However, I did not have long-term clinical responsibilities for any patients so that I could focus on the lab.

In 1990, Gerald Fischbach returned to Harvard from Washington University to chair the Medical School Department of Neurobiology and direct the MGH Neuroscience Center. Gerry, who was never short of ideas, decided it was time to reimagine the graduate program in neuroscience. I had taken a graduate neuropharmacology course from Gerry in 1979 during his previous time at Harvard, and he had become a mentor and friend. Gerry invited Richard Masland, David Corey, and me to work with him to rethink the required initial neurobiology course for the first-year graduate students that also would be taken by the joint Harvard–MIT (Health Sciences and Technology) students. Developing this new course (Neuro 200/HST 130) was hard work, but it was also stimulating and, importantly, once we began teaching it, brought me into early contact with the Harvard graduate students. Within a few years, I had four very bright doctoral students in my lab along with several postdoctoral fellows, three of whom had MDs and PhDs and had completed neurology residencies. (I had no such luck recruiting young psychiatrists.) Overall, despite intense early career anxieties as occurred when awaiting news of grant reviews and submitted papers, I felt fortunate to be on the path that I had dreamt of and had reached by a long and indirect route. This path, involving research, teaching, and a modicum of clinical engagement was one that I planned to follow for the duration of my career. Clearly, I did not understand myself well.

In fact, by 1996, my path had deviated profoundly from this initial, idyllic vision. My career has been extremely interesting and, in many ways, privileged, but it also has been characterized by many unexpected twists and turns. These included sojourns in government as director of the National Institute of Mental Health (NIMH) and in academic leadership as provost of Harvard University. These opportunities came unbidden, but they proved to be irresistible. I had remarkable experiences, extraordinary opportunities to learn, and interactions with what were to me exotic fauna, such as senators, cabinet secretaries, and the U.S. president and vice president. Most important, I had the opportunity to shoulder significant responsibilities at institutions that mattered to science and more broadly to academia and to exert influence on matters that I cared about deeply.

I was keenly aware that I lacked the usual administrative experience for the directorship of NIMH and later the position of university provost. Thus, I had to navigate in highly visible roles while learning on the job. I was 43 and had not even been a department chair when I found myself in 1996 at the helm of a federal research agency with a budget of approximately $600 million (and by the time I left, $1.3 billion) and more than 1,000 intramural scientific personnel and extramural program officers and administrators. My intense commitment to the success of these institutions, my desire to advance a vision, and my capacity to lose myself in the work all helped me to manage my anxiety and propel me forward. Given my temperament, I was attracted to these leadership positions because they conjured in me a sense of mission. They also permitted me to make significant contributions to science, academia, and ultimately to society that outweighed the losses I would inevitably incur in terms of my own scientific efforts, privacy, and time with my young family. The move to Bethesda came at a time that was incredibly disruptive to my family; without my wife Barbara’s resilience and understanding, my tenure at NIMH might have been six months instead of nearly six years. Becoming director of NIMH also meant that I had to make my own lab smaller and that I would not have enough time to spend with my students and postdoctoral fellows. After I moved back to Harvard from NIH, the intensity of my duties as university provost and the beginning of turbulent times at the university led me, with regret but of necessity, to close my lab, which I had been maintaining at NIH with a view toward moving it to Boston. Nonetheless, despite my duties as provost, I remained connected to neuroscience by teaching it to undergraduates, writing review articles and opinion pieces, and serving as editor of the Annual Review of Neuroscience. My conscious commitment to stay engaged in neuroscience ultimately made it possible for me to return full time. After a sabbatical in 2011, I was able to take on the directorship of the Stanley Center for Psychiatric Research at the Broad Institute of MIT and Harvard, which now gives me a significant opportunity to influence investigation of genetics, disease mechanisms, and potential therapeutics for mental illness (Hyman 2018).

Notwithstanding my changing job descriptions and titles, my broad scientific goals have remained constant from the beginning of my career. Whether in my lab, in my role as NIMH director, and now at the Stanley Center, I have worked to understand the neurobiological mechanisms that underlie psychiatric disorders with my greatest focus on addiction and schizophrenia and with the ultimate goal of advancing therapeutics. It is frustrating that neurobiological insights into mental illnesses remain modest and that treatment options remain limited for many who are distressed and suffering from significant impairments. The present time offers great promise, however, not because we have become smarter, but as is often the case in science, because of the development of new tools and technologies (Galison 2003). Thus, new tools for genomics, computation, stem cell biology, genome engineering, analyses of single-cell transcriptomes and epigenomes, and system-level neurobiology have made possible real traction on psychiatric disease mechanisms and the hope of achieving meaningful, cumulative progress. I have experienced false dawns before, such as when the genetics of bipolar disorder fleetingly seemed tractable in the late 1980s (Egeland et al. 1987). Thus, my enthusiasm for emerging results (Schizophrenia Working Group 2014) is tempered by the intense skepticism that is a defining aspect of my character.

Education

I was born at St. Albans Naval Hospital in Queens, New York, about a year after my father, a physician trained in hematology, returned from the Korean War. I spent my first four years on the Upper West Side of Manhattan, near my father’s extended family and not far from my wonderful maternal grandparents, who lived in the Bronx, both immigrants from Russia. My maternal grandmother, who lived with us after my grandfather died—I was four at the time—had survived the Triangle fire, an important event in American labor history. She had testified at the trial of the sweatshop’s owners and subsequently was arrested several times for involvement in labor disturbances and for marching for women’s suffrage. She instilled in me an indelible commitment to social justice. Both of my parents had attended New York City Public Schools and were great believers in public education. Like many of their contemporaries, they came to the view that suburban public schools would provide a better and safer education than the schools that they had attended in the city, and so we joined the great migration of the 1950s to the suburbs. In our case, that meant moving a few miles across the Hudson River to Teaneck, New Jersey, where I would remain until I graduated high school and left for Yale in 1970.

I imagine that my elementary and junior high schools offered a perfectly reasonable education, but I could not testify to that because I spent much of my time daydreaming and in the earlier grades, drawing labyrinths (with Minotaur) on my desks with number 2 pencils. Inward pulls generally overpowered any offerings from the external world, especially when the world outside my head meant the classroom. The few experiences that reliably drew me out of myself were those involving nature. My mother had started a graduate degree in biology before her financial needs pushed her into dull office work. She happily took me with my sister and later, my brother (both younger) to such places as the American Museum of Natural History, which was very close to the apartment of a favorite aunt in New York City. We visited the Central Park Zoo often and the far larger Bronx Zoo on occasion. Once or twice a summer, we drove to various quarries in New Jersey or upstate New York to search for interesting rocks and fossils. I still have large chunks of fluorescent franklinite and willemite that I brought home from a closed zinc mine in Franklin, New Jersey. We also took frequent walks along the nearby Hackensack River and the associated (very stinky) wetlands. I remember ponds and creeks that seemed to be teeming with pollution-tolerant killifish and perch that we could catch in nets or with drop lines, and the thrill of spotting and catching frogs and the occasional newt or their terrestrial juvenile forms, red efts. To this day, I experience something strangely akin to Marcel Proust’s description of how the smell and taste of madeleines and tea triggered an involuntary flood of childhood memories—except for me the stimulus is the acrid, eye-watering air that I had encountered on those wetland walks. Because I still have family members to visit in Northern New Jersey, and despite beneficial reductions in pollution over the years, I can still on certain lucky days, enjoy my crypto-Proustian experiences at certain felicitous spots along the New Jersey Turnpike.

A bathtub on the top floor of our house was occupied for a time by a large, admittedly misshapen-looking fish that my brother had netted on one of our walks—we generally brought with us a few nets and the pail that otherwise held our mop. That fish somehow survived several months of bathtub captivity, during which time our Airedale terrier spent periods standing on her hind legs, with her front paws resting on the edge of the tub, watching Alonso (that was the fish’s name) swimming endlessly back and forth. Over the years, many wild animals shared our suburban house with us, but the more significant risk to the human inhabitants was my chemistry set. In our intensely lawyered present, children likely suffer fewer burns on their arms and hands than I did, but they miss out on such glorious experiences as dropping small chunks of metallic sodium into toilets—resulting in minor explosions—of tossing copper, cobalt, or iron-containing salts into the fireplace to produce colors (and an early appreciation of spectroscopy), and of burning magnesium ribbon on the driveway. In Teaneck in the mid-1960s, a teen could even purchase a tiny amount of red phosphorus at a shop called Davis Toys on our main street—such chemicals were kept behind the counter, presumably to keep them out of the hands of even younger children. My “experiments” were limited only by my allowance. My mother not only tolerated these experiments, but also even bought me a periodic table printed on cardboard to hang in my room. I loved that table and loved reading about the different elements listed on it almost as much as I loved the explosions when the metallic sodium hit the toilet.

After puberty had its way with me, the rocks and fossils on my shelves lost some of their salience, and my relentless curiosity turned, inter alia, to what made people tick. I began to read avidly on the topic, but it being the 1960s, I could not find much about the brain that was intelligible to me. The psychology of the time, or at least what I found of it, was Freudian or else behaviorist. I discovered some popular paperbacks by or about the pioneering ethologists, Niko Tinbergen and Konrad Lorenz, but found them disconcertingly dry. I read with no real guidance or even conversation partners—my discussions with high school friends largely focused on football, poker, intoxicants, and similar subjects. In my solitary meanderings at the town library and the occasional well-stocked book store, such as the Strand, when I could get to New York City, I eventually found my way to philosophy, which, seemed to me the discipline that most directly (if not always understandably) addressed my questions about human minds, human identity, the status of scientific knowledge, and the basis of ethics for the skeptical materialist that I had become.

I matriculated at Yale in 1970, just as protests over the Vietnam War reached their apogee. During the spring before my arrival, the Yale president, Kingman Brewster, reflecting on the Black Panthers who were jailed in New Haven awaiting trial for murder, publically expressed doubt as to whether these black revolutionaries could get a fair trial. In response, U.S. Vice President Spiro Agnew (who later was forced to resign over petty bribes he had received) called for Brewster to be fired. Very likely Mr. Agnew spared Yale the violence and disruption that occurred at other colleges by causing the students to rally around Brewster. Against this complex, anxiogenic backdrop, I began my college education.

I had received advanced placement credit in several subjects, including biology and chemistry. I was thus in a position to talk my way out of introductory survey courses and into interesting upper-level science courses. The physical chemistry course with which I started was quite challenging—it was a bracing reminder that I was no longer in Teaneck High School. The biology courses I took in later semesters were enjoyable and not so taxing; a favorite of mine was a well-taught developmental biology course. The odd and opportunistic smattering of science courses that I took would later prove critical in convincing medical schools that I might succeed if admitted.

Against the advice of my parents, I decided to major in philosophy. I was so thirsty for knowledge, however, contrasting the limited intellectual horizons of my high school with the opportunities at Yale that I took a second major as well. This second major, called History, the Arts, and Letters (HAL), was an interdisciplinary program in the humanities, with a competitive application process, that enrolled a cohort of approximately a dozen students. We were taught in seminar format by stellar faculty members on subjects that included world literature; history; history of ideas; and history of art, architecture, and music. The curriculum, spread over three years, was organized chronologically, so that diverse topics were studied in conjunction with each other, demanding interdisciplinary thinking that was well ahead of its time. Although my philosophy major and my science courses emphasized critical thinking, HAL also put enormous demands on integrative thinking and cognitive flexibility, capacities that later proved extremely useful to me.

From Philosophy to Psychiatry and Neuroscience

I loved my undergraduate education. It introduced me to fascinating worlds that I had not known existed, and it increased rather than slaked my curiosity about anything I could learn. I had the sense that a university would be a good place for me to spend my career, but I never had the discipline to narrow my focus or settle on a sensible plan. Thus, as graduation approached, it became obvious that my only option was to temporize. I applied for fellowships to study in England before selecting a goal for graduate school. Having no realistic alternative plan, I was anxious and then incredibly lucky to receive a two-year Mellon Fellowship to the University of Cambridge. The Mellon fellows became members of Clare College, which is particularly beautiful even among Cambridge colleges, and proved to be both welcoming and supportive of my academic goals. With a view toward exploring areas that I might subsequently pursue for a PhD, I decided on history and philosophy of science, which brought together subjects that I found compelling and that had a strong faculty at Cambridge. Although I was broadly interested in both the history and philosophy components, across diverse areas or science, I developed a special focus on issues related to psychology, neuroscience, and their implications for understanding thought, emotion, human identity, and agency—much in keeping with my longstanding interests.

Although, I did not ultimately pursue a PhD in philosophy, I did become deeply engaged in several questions, some of which continue to excite me to this day. One of these, which might have become the topic of my thesis had I stayed in philosophy, was to investigate causal inference across levels of complexity in the brain—across levels constituted by genomes, molecules, cells, synapses, circuits, cognition, and behavior. A challenge for such analyses lies in the “many to many” mappings across levels of complexity that limit the utility of widely used reductionist experimental approaches. In highly complex multilevel systems, of which the brain represents the non plus ultra, functioning at higher levels of integration cannot be explained by the properties of individual components at lower levels. A useful, if anachronistic, illustration of the challenges for experimental design is offered by the frustrating attempts to produce a molecular explanation of long-term potentiation (LTP) and spatial memory in the 1990s by generating scores of transgenic mouse lines. Generally, in this line of experiments, genes expressed in the hippocampus were knocked out and the resulting mouse lines were studied physiologically for evidence of LTP and behaviorally to evaluate memory using such tests as the Morris water maze. Most of the mouse lines described in published reports (which probably represented publication bias toward expected phenotypes) exhibited deficits in LTP and spatial memory. Taken together, these experiments seemed to implicate more than 100 genes but yielded no useful molecular explanation of mechanisms underlying either LTP or spatial memory (Sanes and Lichtman 1999). Conversely, many neuroscientists and philosophers don’t even try to explain cognition in terms of synapses or circuits by declaring cognition to be emergent properties of activity within circuits. Neither approach is satisfactory if neuroscience is to deliver testable explanatory models that will help generate hypotheses leading to therapeutic interventions. It seems necessary, therefore, to develop experimental approaches that, paired with computational models, will permit neuroscientists to follow causal influences across levels of complexity.

Today, my colleagues and I at the Stanley Center face just such challenges of causal inference. We participate in and perform the genomic analyses for several large international consortia that are successfully identifying both common and rare DNA variants (alleles) that confer risk for psychiatric disorders such as schizophrenia, bipolar disorder, and autism spectrum disorders (ASDs). We have found that these disorders have highly polygenic risk architectures, which at the population level, involve thousands of allelic variants associated with many hundreds of genes (Schizophrenia Working Group 2014). Each risk allele exerts only a small additive effect on phenotype. The occurrence of illness, such as schizophrenia or bipolar disorder, in any individual person results from genetic loading for some subset of the risk alleles found in the population, acting together with stochastic developmental events and environmental risk factors. Even if we focus only on the genetic component of risk, causal models are difficult to formulate, yet they are critically important if disease-altering therapies are to be discovered. We must ask how diverse combinations of modestly penetrant risk alleles influence the transcriptomes and proteomes of a subset of neural cell types and their synapses to produce damaging effects on cognition and behavior (McCarroll and Hyman 2013; Hyman 2018). Is there convergence on shared mechanisms across individuals? The development of causal models of polygenic disorders will almost certainly prove critical in guiding the development of therapeutic interventions. Unsurprisingly, most clinical neuroscience remains focused on rare monogenic illnesses, which appear to be far more tractable, but ultimately, neuroscience must address the common polygenic disorders that are so damaging to both individuals and to the public health.

Another problem that gained my interest, and that connected with later periods in my career, was the question of why some scientific fields stagnate. Much attention has been paid by historians to dramatic scientific advances (such as Newtonian mechanics and relativity) and to catastrophic failures (such as the disastrous application of Lamarckian inheritance to Soviet agriculture in the 1940s), but I became interested in the human factors that can impede scientific progress. As I will discuss later, such issues, which I had considered only theoretically when at Cambridge, became major real-world concerns for me during my tenure as director of NIMH.

Returning to my practical concerns of 1975, however, it seemed that with one year left in my Mellon Fellowship, it was high time to commit to a more focused intellectual trajectory, and perhaps even a career. I thought that I would be intellectually engaged by academic philosophy, but as much as I enjoyed reflecting on problems of mind and brain from that vantage, I realized that I would find it more stimulating to participate in brain research directly. In addition, I incessantly wondered how I might make the greatest positive difference in the world and concluded that it was by becoming a scientist. These thoughts reminded me, however, that I had dug a bit of a hole for myself. Given my academic background, I could not imagine anyone admitting me to one of the few graduate programs that focused on neuroscience in the mid-1970s. Ultimately, I decided on a plan: I could enter into a scientific career via medical school followed by extensive postdoctoral training. This plan had the additional charm that it would temporarily make my parents happy—they had wanted me to be a doctor like my father and his brother—although once I followed through with the plan, I knew that they would be disappointed, which, in fact, they were. My plan was based on the fact that while medical schools in the United States favored science majors, they accepted some students from other disciplines. It helped that I had done well in undergraduate science courses; I realized, however, that there was no way around taking organic chemistry. I did so at Harvard during the summer of 1975 and to my surprise and delight, I enjoyed this highly logical subject enormously.

I applied to several schools and entered Harvard Medical School in the fall of 1976. To my horror, I discovered that the two initial classroom-based years of medical school in the 1970s were intellectually execrable—dreary exercises in rote learning. I was often bored, and in truth, frequently unpleasantly irritable because of the unrelenting intellectual poverty of the curriculum—a notable exception being the glorious neurobiology course taught by Ed Furshpan, David Potter, Ed Kravitz, and David Hubel. One silver lining was that being blessed with a good memory, I did not find the coursework challenging. This allowed me the time I needed to begin working in a research lab, which I did throughout medical school. My research in the lab of Wayne Alexander on regulation of angiotensin II receptors eventually resulted in my graduating with honors. In stark contrast to the first two years, the clinical courses of the third and fourth years were engaging, demanding, and extremely well taught by the remarkable clinical faculty of the Harvard-affiliated hospitals.

I decided to follow medical school with residency training and assumed that it would be in neurology. I was particularly enthralled by a series of evening lectures given by Norman Geschwind, a pioneering behavioral neurologist, who was also a riveting speaker. He started his series by reanalyzing the work of the great 19th-century neurologists Broca and Wernicke who had correlated careful clinical observation with postmortem brain lesions and thus had identified anatomic regions associated with the production and decoding of speech. Geschwind illustrated cases in which Wernicke’s and Broca’s areas had been disconnected from each other by lesions in the arcuate fasciculus to produce a conduction aphasia. He then elaborated his connectionist model of brain function and illustrated it with fascinating clinical and neuropathological observations made on patients with aphasias, alexia, and apraxias.

During my neurology clerkship, I was not disappointed by the senior neurologists with whom I interacted at the Peter Bent Brigham Hospital (now Brigham and Women’s). They possessed encyclopedic knowledge and applied impressive deductive skills to the clinical presentations of the patients we saw. The patients, however, were nothing like the cases that Geschwind had described in his mesmerizing lectures, often the result of small, focal strokes that serendipitously revealed fine distinctions in the functional architecture of the cerebral cortex. In stark contrast, the conditions that afflicted the hospitalized patients on the neurology service were typically devastating hemispheric strokes, spinal cord injuries, advanced Parkinson’s disease that was refractory to L-DOPA, and late-stage multiple sclerosis. These patients were severely impaired even with respect to the most basic aspects of self-care and communication, and we had little to offer therapeutically. In the late 1970s, the exquisite neurologic exams we learned and the logical processes by which we deduced the location of the patients’ lesions (recognizing that at the time, there was usually no way to confirm these conclusions antimortem) yielded little of benefit to patients and families. Among the older, highly respected clinicians, I also detected an undercurrent of animus directed at neuroscience as a pursuit that was irrelevant to practice but somehow luring talented young people away from the wards.

I had a very different, almost opposite experience in psychiatry. I was deeply moved by the patients, fascinated by talking to them, and recognized that the existing treatments, although far from perfect, were nonetheless often quite beneficial. In contrast to the neurologists, whose rigor and well-grounded anatomic knowledge I admired, many of the psychiatry faculty—of course with notable exceptions—were intellectually off-putting. The largest number of faculty with whom I crossed paths were psychoanalysts or practiced related treatment approaches, such as psychodynamic psychotherapies. They eschewed the idea of diagnosis, which was so fundamental to the rest of medicine, and construed the symptoms of their patients as manifestations of unresolved unconscious conflicts. The brain, or indeed any consideration of biology, was utterly foreign to many, even those who treated severely ill patients with schizophrenia or bipolar disorder. The majority of the teaching faculty members exhibited calm certainty in describing the theoretical underpinnings of their psychoanalytic practice—something that never failed to elicit outrage in my younger self as I heard a litany of “just-so” stories with scant empirical basis. The exceptions among the psychiatry faculty were often, however, among the most thoughtful and caring clinicians I met during my medical school years, and I have maintained contact with some of them. I believe that these clinicians, most of whom treated patients with very severe illnesses, demonstrated remarkable humility, impressive commitment to this highly stigmatized and marginalized patient population, and effective pragmatism in looking out for their patients that had to extend far beyond the confines of the clinic.

The 1970s and 1980s were characterized by pitched battles between proponents of the still-dominant, but waning, clinical approaches grounded in psychoanalytic theory and the insurgent psychopharmacologists (Klerman 1990). In their zeal to vanquish the psychoanalysts and to be recognized as “real doctors,” some of the self-styled biological psychiatrists rather bizarrely discounted the role of environmental factors or lived experience in the pathogenesis and clinical outcomes of mental illness. Many could find no role for talk therapies in treatment—unlike cardiologists, for example, who, implicitly confident in the biological basis of their therapeutics, thought it no disgrace to address diet, exercise, and stress reduction along with medications or surgery in treating cardiovascular disease. I was in full sympathy with the rejection of psychoanalytic theory with its preposterous ideas about the nature of mental illness, but I was unimpressed by the reductive explanations offered as alternatives by the biological psychiatrists who taught my medical school classes. The fetishization of neurotransmitter levels in the brain, as if the brain were an endocrine organ as simple as the thyroid gland, and their seeming ignorance about synaptic plasticity and neural circuit function seemed inexplicably backward given that I had been taught by David Hubel, Torsten Wiesel, and Norman Geschwind at the same medical school. This is not to suggest that disease mechanisms underlying psychiatric disorders could readily have been identified with a bit of better theory—we are still at the very beginnings of mechanistic understandings. What bothered me was that instead of seriously embracing neurobiology, many biologically oriented psychiatrists had walled themselves off intellectually and thus had failed to recognize that there was more to the human brain than could be revealed through pharmacology.

The question of whether to study neurology, psychiatry, or both was challenging and frustrating—after all, these are two disciplines grounded in diseases of the very same organ—but often in unrecognizably different ways. Finally, it struck me that I would be spending the vast preponderance of my clinical hours with patients, not with my colleagues, and decided that I should weight my choice of specialization based on the patients with whom I would interact and the diseases that would be most compelling to study in the lab. I never regretted my decision to train primarily in psychiatry, although I did complete part of a neurology residency. Indeed, being intellectually cantankerous, I rather enjoyed the many edgy discussions I have had with colleagues in psychiatry over the years. I also imagined that it was an opportune time for a physician-scientist at the beginning of a career to pursue basic neuroscience relevant to mental illness. I believed that the tools were emerging that would elucidate the processes that go awry in the brain to produce disorders such as schizophrenia and depression. I obviously did not recognize the complexities that would stymie attempts to understand psychiatric disease mechanisms for several more decades. Notwithstanding these unforeseen scientific hurdles, the mystery of psychiatric disease mechanisms gained a hold on me, not only because of the terrible effects of these disorders on many people, including some members of my extended family, but also because so much remained tantalizingly unknown. That seemed to offer a great opportunity, assuming that much-needed new tools and technologies would emerge during the course of my career.

After a year of medical internship at MGH, I began psychiatry residency at McLean Hospital, an MGH affiliate that was, at the same time, proudly independent. I spent the first year of my residency on a unit, North Belknap-1, that specialized in treating patients with acute psychoses. In practice, this meant I treated patients with first psychotic episodes of schizophrenia and psychotic relapses; patients with acute episodes of mania; and, less commonly, individuals with severe depression who had psychotic symptoms, such as voices telling them that they were worthless or delusions that they were rotting, emitting a stench, or otherwise debased. The unit was run by two pragmatic young psychiatrists who were skilled psychopharmacologists and excellent physicians. They based their therapeutic approaches on clinical trial evidence when it was available, and eschewed participation in the ideological battles that roiled psychiatry. My year on this unit permitted me to interview a large number of patients with diverse psychotic illnesses and to oversee the treatment of scores of patients (with the gentle oversight of the psychiatrists in charge). I also gained significant experience in the properties of psychiatric medications, including both their benefits and their many side effects.

One powerful example of the way in which my clinical experience further ignited my scientific curiosity came from my caring for a young woman of 19 with acute mania. She was a college student from Maine, said by her family to have been demure, conservative in her behavior, and studious. Over a period of a few weeks, she had undergone a remarkable change that had reached a crescendo in the days before her hospital admission. She had begun sleeping for only about two hours per night but had remarkable levels of energy. She had become uncharacteristically sexually promiscuous and had started drinking large quantities of alcohol. When I first saw her, she was shouting loudly that she wanted to go bear hunting. She had most of the canonical symptoms and signs of acute mania, including rapid, pressured speech and grandiose ideas.

For the first few days of her hospital stay, I prescribed a benzodiazepine and an antipsychotic drug to help calm her ceaseless motion and yelling and also to help her get some sleep. At the same time, I initiated treatment with lithium, which must be started slowly to minimize side effects, and then takes weeks to exert its antimanic effects. Over about six weeks, the quiet and rather shy young woman who had been described by her family reemerged. By what neurobiological mechanisms, I wondered, did manic-depressive illness cause such dramatic alterations in physiology, thought, speech, and behavior? And how was it that if we brought her to a serum concentration of 1 mM lithium we were able to return this young woman to herself? It seemed to me in 1981 that genetics, molecular biology, and neurobiology would soon provide us with answers. Unfortunately, we still do not know how lithium treats mania, nor do we possess even rudimentary insight into its pathogenesis (Hyman 2012).

My wonderful year on North Belknap-1 came to an end, and I began rotations that were supposed to last several months each on other clinical services at McLean Hospital. I found myself in what seemed a waking nightmare. Depending on the units to which patients were admitted—something partly determined by the chance occurrence of an empty bed—they might receive shockingly different treatments for the same illness at the same stage of life. Had the young woman with mania that I described been admitted to one of the units at McLean that I rotated through, she would have received sedatives and antipsychotic drugs, but not lithium, and her main treatment would have been a version of the psychoanalysis that had been developed at Tavistock Clinic in London. In short, she would have had her manic symptoms interpreted to her by the staff and her therapist as their central therapeutic intervention. Given what we knew at the time about the treatment of bipolar disorder, this seemed unethical and even abusive, a set of conclusions that I shared with peers and with faculty to a decidedly mixed reception.

At one point, I was assigned to spend several months on an inpatient children’s unit that was directed by a rigid man who espoused yet another school of psychoanalytic theory. The unit housed children with a range of conditions, including what we would now diagnose as ASDs, psychoses, mood disorders, and borderline and antisocial personality disorders. Treatments were prescribed and administered, not according to diagnoses, which were eschewed except for the purpose of billing insurance. Instead, treatments were based on case formulations grounded in psychoanalytically inspired developmental theories. When medications were administered, it was generally to control anxiety, agitation, or aggressive behavior, rather than as treatment for the underlying illness. These clinicians were not skillful in psychopharmacologic therapeutics; indeed, typically, drug doses were too high. Thus, excessive sedation and the Parkinson-like motor side effects of first-generation antipsychotic drugs were much in evidence.

Quite upset by what I was seeing on the unit, I complained to the director of the McLean psychiatry residency, Philip Isenberg. This warm and flexible psychiatrist was not at all surprised by what I told him, although that did not assuage the moral outrage I felt at the treatment of ill children based on antediluvian psychoanalytic theories. Indeed, his calm handling of my concerns betrayed a kind of fatalism, as if he had been defeated too many times in trying to intervene in the successful businesses that the individual clinical fiefdoms seemed to be. Surprisingly, however, his response to my litany of complaints about the clinical practices I observed, their risks to the patients, and (in my view) their profound disutility for my training, was “so don’t go.”

I took him at his word, and from then on Dr. Isenberg allowed me to slip away from putatively required clinical rotations so long as I never shirked my assigned service responsibilities (such as night call) and promised to keep learning psychiatry, so that I would pass the specialty boards—which I later did without much trouble. I used my newfound free time to start working in a laboratory again, and I also took a series of moonlighting jobs at outside clinics. These helped me supplement my very meager salary—my wife and I had a 16.75 percent mortgage, which was better than many on offer in the early 1980s, on our small starter house. Moonlighting gave me independence from theory-ridden supervisors and the intense learning experience conferred by responsibility for sick people. My most interesting experience was a daytime job at an outpatient clinic on the grounds of the old Boston State Hospital in Dorchester, Massachusetts, where once a week, I was the prescribing physician for patients, mostly with schizophrenia, recently discharged from the state hospital.

At the time, the de-institutionalization movement was in full swing, and the campus felt like a ghost town with many red brick buildings dating from the 1930s sitting eerily empty on the enormous, ill-tended grounds. The other staff at this clinic, officially named the “aftercare” clinic, were older, experienced nurses who had seen every possible clinical situation over the years and who were unflappable and often charmingly cynical. True to my promise to Phil Isenberg, I read the clinical literature with ferocious intensity—and learned an enormous amount from these nurses and, above all, from the patients. Looking back, I am amazed by my temerity, but I codified my reading and my moonlighting experiences by writing and editing three clinical manuals that were published by Little, Brown (later merged into larger publishers) as components of a successful medical handbook series (Hyman 1984; Hyman and Arana 1987; Hyman and Jenike 1990). The first two went through multiple printings and several editions and were translated into diverse languages, including not only Spanish but also Japanese, Turkish, and Croatian. Without doubt, one never learns better than when teaching and explaining—and, in this case, because I knew that clinicians would act on my advice, I obsessively made sure that the advice I gave was as accurate as the literature permitted.

In lieu of a final year of residency at McLean, I received permission to substitute a year of neurology residency at MGH. It was not only informative but also awe inspiring to examine patients with the great neurologists Raymond Adams and C. Miller Fisher and to spend several months in the clinical neuropathology lab with E. P. Richardson. As in medical school, I felt deep respect for the neurology faculty, but I remained frustrated by how little could be done for the patients. Despite the possibility of getting board certification in both psychiatry and neurology with yet one more year of neurology residency, I was not seriously tempted to do so. I had observed and learned about a wide swath of diseases of the nervous system, which had been my goal for residency training, but I was 31 years old and experiencing diminishing returns at the intellectual level. It was high time to embark upon laboratory neuroscience full time. My parents, in fact, had been disappointed when I told them that I would do a residency in psychiatry rather than internal medicine. When I explained to them that I was about to begin a postdoctoral fellowship in molecular biology, they could not fathom what I was up to.

Can Molecular Neurobiology Help Elucidate the Pathophysiology of Psychiatric Illness?

Many of the Harvard Medical School affiliated basic scientists studying aspects of mental illness had their labs in the Mailman Center at McLean Hospital. The center had been built for the arrival of Seymour Kety, who had first moved from Johns Hopkins to MGH in 1967 and then to McLean 10 years later. In the 1940s, he had pioneered methods to study blood flow in the brain, and later he did foundational work in psychiatry by demonstrating genetic transmission of schizophrenia using well-designed adoption studies based on the Danish national birth registry. He found a fivefold greater risk of schizophrenia when the disease was present in an adoptee’s biological family than when it occurred in members of an adoptive family. Dr. Kety was in the process of winding down his lab, however, and was not taking new trainees. Other accomplished investigators at the Mailman Center included Ross Baldessarini, who had characterized the ligand-binding properties of several neurotransmitter receptors and also had an encyclopedic grasp of the clinical and translational psychopharmacology literature.

Although I appreciated the work of many of the investigators at the Mailman Center, their commitment to well-established methods grounded in pharmacology seemed too narrow for someone at the start of a career. I was drawn instead by the promise of genetics and the emerging discipline of molecular neurobiology. The McLean faculty were surprisingly discouraging about the relevance of molecular biology to the problems of psychiatry. I therefore sought the advice of John Potts, chair of the Department of Medicine at MGH, whom I had met during my medical internship. He introduced me to Joseph Martin, chair of the Department of Neurology at MGH. I was delighted and surprised by the fatherly interest both of them showed in my future—surprised because psychiatry ranked low in the academic pecking order—indeed, several professors during my medical school years were unreservedly horrified that I was going to train in that discipline. Years later, it was Joe Martin who provided me with space and startup funds to begin my independent lab, and who made valiant, but unsuccessful, attempts to bring clinical training in neurology and psychiatry closer together.

In contrast to the senior psychiatrists at McLean who had tried to discourage me, Drs. Potts and Martin were optimistic about the tools that molecular biology would provide for understanding brain disease. Joe Martin had already worked together with David Houseman (MIT) to connect Houseman’s former postdoctoral fellow Jim Gusella with the human geneticist Nancy Wexler, a collaboration that would eventually lead to identification of the mutation that causes Huntington’s disease. Together, Drs. Potts and Martin recommended me to Howard Goodman, who had just arrived at MGH from the University of California, San Francisco (UCSF) to found a department of molecular biology. The MGH department would be a branch of the Harvard Medical School Department of Genetics, which had been started and was chaired by Philip Leder, who had developed the first transgenic mouse cancer model. The MGH Department of Molecular Biology was founded with a then-unprecedented $70 million grant from the German pharmaceutical company Hoechst (which several years and many mergers later, was absorbed into Sanofi). Howard was initially skeptical of accepting a postdoc with an MD, no PhD, and no experience in molecular biology. I committed to staying in the lab long enough, however, so that early investments in getting me up to speed might be repaid with experimental results and publications. The transition to Howard’s lab was difficult as I moved from a position of relative expertise in my clinical discipline to the status of basic learner. I was fortunate that a fellow postdoc, Michael Comb, who was talented and experienced in molecular biology, generously helped me get started and then became a collaborator. Mike moved with me later to the Molecular Neurobiology Unit in the Neuroscience Center. He eventually decided that he preferred the biotech industry to academia and founded a successful company, Cell Signaling Technologies.

The Goodman lab had other challenges for me. It was built around molecular technologies rather than core biological questions. Thus, few in the lab were interested in neurobiology. Indeed, by the time I left Howard’s lab, more than half the people were working on plant molecular biology. On the positive side, Howard began to recruit junior faculty members, who were smart and creative, and for the most part, highly collaborative. These included Brian Seed, Robert Kingston, and the future Nobel Laureate Jack Szostack. Brian Seed, on learning of my interests, would share papers with me related to the neurobiology of psychiatric disorders as well as providing much appreciated scientific advice.

On the basis of his graduate work with Ed Herbert at the University of Oregon, Mike Comb brought an interest in endogenous opioid peptides to the Goodman lab and had set out to understand the regulation of their synthesis at the level of gene transcription. Endogenous opioid peptides are cleaved from precursors encoded by three separate genes (i.e., proenkephalin, prodynorphin, and proopiomelanocortin), each of which had been cloned. I was happy to be offered the opportunity to collaborate with Mike on regulation of proenkephalin gene expression, partly for the intrinsic interest of the problem and partly because of the potential relevance of endogenous opioids to emotion, reward, and analgesia. However, investigation of gene expression in brain reward circuitry would have to come later. Little was known yet about the basic mechanisms by which neurotransmitters, second messengers, or pharmacologic agents influenced gene expression (Comb et al. 1987). It was exciting to be involved in working on relevant aspects of signaling to the nucleus, and the identification of enhancer elements that mediated gene regulation by second messengers and their associated protein kinases. I stayed in the Goodman lab for five years, and I learned much from members of the lab and others in the department. As Howard grew more interested in plants and less in animal systems, I was forced to become increasingly independent, which was frustrating at times, but ultimately helped me learn the necessary skills to develop my own lab.

In 1989, after publishing several papers on gene regulation (and working on a side project helping Elizabeth (Betsy) Ross, who had recently joined the Goodman lab, clone the gene encoding phenylethanolamine-N-methyl transferase, the enzyme that converts norepinephrine to epinephrine, I felt that I had reached a natural transition point. MGH was in the process of renovating a vast amount of lab space in a former torpedo factory in the nearby Charlestown Navy Yard with an entire floor dedicated to a new Neuroscience Center. Joe Martin offered me space and startup funds. Moreover, my wife Barbara Bierer had the opportunity to establish an independent immunology lab at the Harvard-affiliated Dana Farber Cancer Institute in Boston. Given the challenges of searching together for positions in the same city and given the attractive offers we both had in Boston, we decided to stay. Over the years, we have both been offered interesting positions at other universities, but Harvard had the attraction of talented colleagues, wonderful students, and good positions for both of us. Except for the years when I was at NIMH in Bethesda, and Barbara served in several positions, including acting clinical director of the intramural research program at the National Heart Lung and Blood Institute, we have stayed in the Boston area.

Regulation of Gene Expression by Dopamine

As I thought about projects for my lab, I focused on connecting my scientific trajectory studying gene regulation to mechanisms involved in psychiatric disorders. Psychiatric disorders clearly are not cell autonomous; to the contrary, their symptoms and functional impairments represent abnormal functioning of synapses and distributed circuits underlying cognition, emotion, and behavioral control. Such considerations already had led me to focus on trans-synaptic and drug-regulated gene expression, which could be studied initially in cell culture but later was applied to studies in laboratory animal brains. A challenge was to select experimental paradigms that would credibly have relevance to psychiatric illness but remain tractable to mechanistic analysis.

I have long been skeptical of putative animal models of psychiatric disorders. I was even more skeptical of the traditional criteria for validation of such models, especially of “face” validity, which invites anthropomorphic fantasies, and ill-advised follow-up studies focused on traits that might reflect convergent evolution rather than shared mechanisms. Another problematic “validator” was predictive validity, that is, a model in which drug modification of a trait in the animal predicted drug efficacy in humans. This type of correlation is hardly a validator of underlying mechanisms in the model, but rather the use of an animal as a kind of black box assay system. I later published these ideas with my friend Eric Nestler (Nestler and Hyman 2010), but since then, we have both grown further skeptical of the third traditional validator, construct validity. My skepticism is based on the recent discovery that risk of psychiatric disorders is highly polygenic and often involves regulatory regions of the genome that are not well conserved across evolution (Hyman 2016, 2018). My philosophy, as I chose my first projects, was to consider what I did, including work in animals, to be basic science that would inform research on psychiatric disorders by providing intellectual building blocks, such as potentially relevant molecular mechanisms.

Even if I considered my research to be basic, it was still difficult to make it relevant to psychiatric disorders because I would have to find appropriate systems in which to perform studies that involved living brains. I can illustrate my concerns as follows. Lesions of midbrain dopamine neurons with 6-hydroxydopamine or MPTP do not produce a veridical model of Parkinson’s disease. The neuronal loss is acute rather than insidious as it is in humans, and the deficits are only in motor systems, whereas in humans, sleep, mood, cognition, and other functions are affected. It is possible, however, to learn much of relevance from living animals that lack dopamine neurons as a result of such lesions and thus, even if imperfectly, gain insights into motor aspects of Parkinson’s disease. However, no such compelling approximation existed for depression, bipolar disorder, or schizophrenia. For example, putative models of depression most often were based on chronic stress. These resulted in behaviors that could (with some imaginative effort) be analogized to those of depressed humans; however, there was no evidence that these behaviors shared underlying mechanisms with human depression. Credible animal models of schizophrenia and bipolar disorder simply do not exist.

I came to the view that of all psychiatric conditions, addiction was the best candidate for studies of molecular mechanisms because the critical causal factors were known—the addictive drugs themselves. The transition from voluntary drug administration to compulsive use, which is central to understanding addiction, could not be fully captured in animals given the important role in humans of cognitive control implemented by a human prefrontal cortex as well as the vast contextual differences under which human versus experimental ‘addiction’ occur. In analogy with dopamine lesions to study aspects of Parkinson’s disease in animals, however, an extensive literature demonstrated the importance of associative learning in reward-related behavior in animal models and of cue-dependent drug-seeking and relapse in drug-addicted humans. I hypothesized that if addiction involved abnormal synaptic plasticity in reward circuitry, then drug-induced changes in gene regulation could play a critical role in initiating and maintaining the relevant synaptic changes. In addition, the long-lived nature of addiction, with its protracted risk of relapses was also consistent with a role for associative memory in pathogenesis and thus, potentially, with altered regulation of gene expression.

As the lab grew, we focused largely, but not entirely, on the actions of increased and decreased dopamine release and dopamine receptor activity using a variety of pharmacologic agents and 6-hydroxydopamine lesions in rats and in both transgenic and wild-type mice. We studied phosphorylation of the cyclic AMP and Ca²⁺ regulated transcription factor cAMP response element binding protein (CREB) in response to such manipulations and the induction of immediate early genes. We also began to discover dopamine-inducible genes in the dorsal and ventral striatum that were potential candidates for roles in altering behavior. I was able to obtain the needed levels of grant funding, and my MD-PhD postdoctoral fellows were almost universally successful in obtaining individual career development awards—that is, K08 awards from the National Institute of Neurologic Disorders and Stroke (NINDS). On the basis of my frequent scientific interactions with him, Gerry Fischbach proposed that I move my lab from MGH to the Harvard Medical School Department of Neurobiology, and started renovations for me in the Medical School Quadrangle in the Longwood Medical Area. Then, literally out of the blue, NIH came calling and everything changed.

NIMH

In 1994, the director of NIMH, Frederick Goodwin, was forced to step down by the secretary of health and human services at the behest of Congress. Goodwin’s departure eventuated from public remarks that he made in the context of a “violence initiative” that he had championed as a way of mitigating high rates of youth violence then occurring in cities. Goodwin drew an analogy between violence observed in young male monkeys and violence perpetrated by inner-city youth. He also pointed to research that had been performed in rhesus macaques that reported associations between low levels of serotonin metabolites in cerebrospinal fluid and high levels of aggression—an association similar to one that had been reported in Finland in a study of suicidal humans. Some members of Congress took umbrage at Goodwin’s seeming to equate inner-city youth, interpreted as code for minorities, with nonhuman primates and saw him as favoring the kinds of deterministic biological explanations that previously had inspired eugenics.

Harold Varmus had become NIH director in 1993, and it fell to him to replace Goodwin, which under the circumstances was an even greater challenge than usual, given that issues concerning mental health and human behavior seemed always to draw scrutiny from diverse advocates and from members of Congress. Varmus had shared a Nobel Prize with Michael Bishop in 1989 for discovering that oncogenes arose from mutations in normal cellular genes. Of particular note, he had almost no administrative experience before becoming a very successful and influential NIH director. Perhaps generalizing from his own (exceptional) experience, Harold decided that he wanted to replace retiring NIH institute directors, who typically had been career administrators, with working scientists who like himself would continue to run labs while directing their institutes.

Varmus appointed a search committee with instructions to identify a psychiatrist—a qualification that was demanded by members of the mental health community—with an active laboratory research program. The committee identified a short list that included a plausible senior psychiatrist, but before the process finished, he unfortunately died while jogging at a scientific meeting. The other candidates, as I heard the story later, were prominent psychiatrist, including department chairs, whose work did not pass muster with Harold. He decided, therefore, that a new search was necessary, and after that one failed to identify a candidate that could meet his expectations, he asked for a third search. As my wife reminds me, I was the product of the third failed search. By the time the third search was initiated, Zach Hall, Harold’s colleague from the UCSF had arrived to lead the neurology institute, NINDS. Zach Hall, now retired, was a superb basic neuroscientist who had chaired the Department of Physiology at UCSF. He and Alan Leshner, then Director of the National Institute on Drug Abuse (NIDA) cochaired the third search for an NIMH director.

Federal searches have very formal procedures, including clearly specified start and end dates. As Zach Hall later told me, he had looked through the candidate’s CVs on a day before the search was to close. He saw that once again, there would be no candidate acceptable to Harold Varmus, and therefore started calling a few younger neurobiologists with psychiatry training who would not have imagined applying for such a role, but whose research might appeal to Harold. I was traveling when Zach called my office—he reached me at home a few days later during the weekend to explain what he had done. On the Friday on which the search was to close at 5 p.m., my tricky friend had managed to convince my assistant to fax my CV to him; he then used my CV to enter me into the search. I was flabbergasted and flattered—I had enormous respect for Zach, whom I had gotten to know from writing a chapter for his book, Introduction to Molecular Neurobiology (Hall 1992). That said, I had little idea of how NIH worked despite reasonable success in obtaining grants from NIMH, NIDA, and NINDS, and no sense at all of what institute directors did.

I then learned I was to be interviewed on the NIH campus in Bethesda, and soon, a stack of paper and brochures arrived that described current intramural and extramural personnel and programs, and also contained recent program announcements, press releases, and reports. I was troubled by what I read, although based on my familiarity with the science relevant to mental illness, I confess that I was not surprised. Although I had not published in psychiatry journals—my lab’s work belonged in neuroscience and molecular biology journals—I did keep up with the psychiatry literature. Based on the materials I received, it was clear that NIMH supported some excellent basic neuroscience that ranged from the molecular to the neural circuit levels of analysis; there was even a small, but superb, portfolio of computational neuroscience. However, the basic neuroscience portfolio represented a surprisingly small fraction of the NIMH investment, and indeed, the percentage of its extramural funds spent on investigator-initiated (R01 grant funded) basic science was among the lowest among all NIH Institutes. The NIMH portfolio was dominated by large and often intellectually amorphous center grants. The largest expenditure in the portfolio went to center grants that supported research in psychiatry departments. The funds were largely expended on departmental infrastructure and internally selected pilot projects—skating fairly close to the Platonic ideal for slush funds. Most of these center grants had been renewed many times over the years and had devolved very nearly into an entitlement.

There was also a portfolio of individual projects and four large center grants focused on the prevention of mental disorders. The most troubling feature of this costly investment was the complete lack of any empirical basis on which to base primary prevention of any serious mental disorder. Lacking any insights into pathogenesis, these centers largely focused on epidemiological risk factors, such as a childhood history of abuse, neglect, poverty, and stress. These are all bad things to be sure, indeed already known to exert broad negative effects on health. Not forthcoming, however, was any evidence of specific, actionable mechanisms associated with any of the mental disorders to be prevented. As a result, most of the recommendations coming from this research program argued for large-scale social and economic policy interventions well outside the remit or expertise of NIH.

Within the large and costly intramural program, many of the clinical branches, like a large number of extramural grants, purported to be translational in nature. As in the case of the prevention grants, there were no credible, replicated basic research findings on which to base such an extensive translational investment. At best, the research projects seemed premature; many relied on questionable animal models or on human studies, most often underpowered, that enrolled subjects according to Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria, and therefore were studying a heterogeneous grab-bag of conditions.

I have little capacity or desire to suppress my honest views in the service of diplomacy, although I do often soften confrontations with humor. In any case, it seemed preposterous to me that I might be a serious candidate for the directorship, and I assumed that the committee would agree. I therefore saw my interview as an opportunity to share my concerns with influential leaders in the field of mental health and related disciplines, such as neurology. I was critical, but also clear about what I would do if selected (and later did do). I described the goals that I would pursue to the committee and later to the science press (Marshall 1996). These included increasing investment in basic neuroscience and basic cognitive and behavioral science relevant to the NIMH mission, scrutinizing the center grants with a view toward eliminating those that were unproductive, investing in the technology and computational tools to advance the analysis of genetically complex disorders, rolling back support for weak and premature translational research investments, and recasting the clinical trials program to involve fewer but better-powered trials—and in the absence of interesting new compounds—using our trials program to address questions that could significantly inform clinical practice. I also noted that given the low quality of intramural research compared with the possibilities extramurally, I would commission an in-depth review of intramural research at NIMH.

I reassured my wife Barbara, pregnant with our third child, happy with her lab and clinical work (pediatric bone marrow transplantation) at the Dana Farber Cancer Institute, and very much against a move, that after my enfant terrible performance I was sure I would never hear from NIH again. Once again, I was wrong. A few weeks later, Harold Varmus invited me to interview with him, after which he began a process of recruitment. From my first interactions with Harold, I was deeply impressed with him, and initially intimidated by his breadth of understanding and penetrating intellect. It mattered to me that he had successfully recruited Zach Hall to NIH, which indicated that it was possible for there to be a new generation of institute directors who were different in scientific acumen, taste, and rigor than some of the prior generation. Nonetheless, I was happy at Harvard, and a move seemed to promise only disruption with no benefit for my family.

I was in the midst of planning new space at the Medical School with Gerry Fischbach and it was early enough in my career that I worried about what would become of me if I were to become NIMH director. I certainly did not intend to remain an institute director for life, which seemed a recipe for growing stale and bureaucratic, and I also recognized that my personal laboratory would have to take a back seat to the serious work I would be taking on. I talked to Zach Hall, Alan Leshner, and Harold Varmus about my uncertainties for four months—my angst must have grown wearying to them. By March 1996, it was past time for me to decide, and I was leaning against moving to NIH for all of the rational reasons I have adduced. However, my temperament was brewing a different outcome for me. I felt growing within me an intense drive to fix what was broken at NIMH. I would wake up at night thinking about what I would do. I suspect that Harold recognized this as my Achilles’ heel. More than once he told me that my ability to influence the science I cared about would be far greater from the vantage of NIMH than from my lab at Harvard. He reeled me in by acknowledging how weak the NIMH portfolio was, saying something to the effect that NIMH was broken, that it had to be fixed, and looking right at me, said that it was my job to do it.

There is a Jewish concept of Tikkun Olam, which can be translated as a duty to repair the world. In Reform Judaism (and in my atheist, materialist version of secular Judaism), this can be interpreted as a call to act constructively, but it can also mean that some things in the world are broken and thus in need of repair. I was definitely not thinking about such Jewish concepts during that conversation in Harold’s office in Bethesda, although I have often returned to them when reflecting on why I disrupted my family and risked my long-term career as a laboratory scientist. In any case, Harold hit the mark, and I accepted. He then added that he needed me to start in two weeks since Congressional budget testimony was in the offing, and he was unwilling for the acting NIMH leadership to represent NIH. Over the years, Harold more than held up his end of what was a powerful implicit bargain. He was a great mentor to me, invariably supporting me when, after the appropriate consultations, I made the changes that NIMH needed. Harold was himself an exemplar of fearlessness in the defense of high scientific standards and academic freedom and, while I am no shrinking violet, his example gave me courage when I told furious incumbents that NIMH programs on which they had long relied were coming to an end.

After arriving at NIMH, I spent much time analyzing the portfolio and trying to understand how funding decisions were made. I was curious about variations in the functioning of study sections (initial review groups) that rank grants by scientific and technical merit. I also wondered whether NIMH slavishly followed study section rankings or whether the staff and the advisory council—more properly the National Advisory Mental Health Council or NAMHC—made alterations in the ordering of grants based on such criteria as mission relevance, portfolio balance, or demonstrable errors by a reviewer. With regard to mission relevance, I quickly learned that the defense of basic science was a consuming and never-ending effort.

Patient advocates often confronted me at meetings, wrote critical op-eds, and complained to Congress about what they saw as wasteful distractions from discovering new treatments but that I saw as the critical foundations for progress, albeit unpredictably so and in the long term. Making matters worse, a small but vociferous fraction of clinical and translational scientists publically agreed with my critics, arguing that if only they had the resources being diverted to basic science, there might have been cures already. The well-known advocate E. Fuller Torrey kept recycling attacks on the basic research that NIMH funded, with a special venom reserved for behavioral science. A favorite target for Fuller was research on bird song as the epithet of “bird-brains” seemed irresistible to him (Torrey 2001). I had to respond to multiple Congressional inquiries over the years—indeed, I proactively visited key members of Congress who I learned were susceptible to the denigration of basic science—educating them, albeit very respectfully, about such facts as that the mechanisms by which birds learn their songs were our best window into the relationship between learning and brain plasticity.

Returning to peer review and decision making, I learned that NINDS had a history of funding grants strictly in percentile order coming from study sections. NIMH intervened, albeit modestly, in setting the order in which grants were paid, but I was surprised to learn that there were no formal criteria for doing so. Based on my sitting as an observer at some study sections and reading many summary statements, I was concerned by the significant variation in the quality of judgments. Many peer review groups exercised appropriate rigor, acted as good stewards of their disciplines, supported reasonable risk taking, and even tolerated occasional heresy if proposed by credible investigators with well-reasoned proposals. At the other extreme were peer review groups that seemed like closed-minded sects on a mission to protect the funding of their members. Like any human endeavor, the quality of peer review depends on many factors, including its overall organization, assignment of applications, instructions provided to reviewers, the strength and competitiveness of the field being judged, and the people participating in the review process.

Over time and based on discussions with colleagues at the weekly 90-minute meetings of institute directors, I concluded that the strength and vitality of the fields supported by NIMH had unusually large variance. Important factors included historically based intellectual commitments of fields (e.g., in some areas of psychology and other areas of social science, the idea that genes contribute to human behavior was treated as anathema, notwithstanding much compelling evidence from twin and adoption studies). Other important factors included the maturity and power of the technologies available to the field, the tractability of the field’s problems, and the number of well-trained scientists engaged in that research area. Large fields supported by NIMH for which significant weaknesses were apparent during the 1990s included neuroimaging to identify correlates of mental illness (in contrast with robust, replicable results achieved when neuroimaging was applied to well-defined questions in cognitive neuroscience), biological candidate gene studies of various disorders, investigations of disease mechanisms that relied on the putative face validity of animal models, and studies that employed pharmacologic or hormonal perturbations of patients to probe disease mechanisms or identify biomarkers. It was apparent that too many studies were based on surmise rather than strong prior evidence; many were poorly designed (in some cases, because investigators were forced to rely on DSM criteria to select their subject populations); essentially all lacked power calculations; and most did not test any crisply stated hypotheses. What was apparent was that practitioners within such fields seemed to have blind spots for such weaknesses (many would have been addressable if recognized). Especially in the clinical branches of the intramural program, I was struck by the number of intelligent, well-trained, and well-intentioned people who had devolved into a state of torpid incumbency within scientifically stagnant communities. In the intramural research program, the risk factors were clear: generous funding year after year, along with relaxation of the competitive selection pressures that characterized extramural science. This is not to say that the extramural research portfolio was immune to such problems, but they were far less common.

These observations reminded me of my studies at the University of Cambridge and, in particular of Thomas Kuhn’s The Structure of Scientific Revolutions (1962). Although much attention and debate focused on Kuhn’s analysis of scientific revolutions, such as that engendered by Copernicus, I was more interested in his analysis of what he called “normal science.” Kuhn’s view was starkly different from Karl Popper’s heroic view of science as an ongoing process of hypothesis testing. According to Popper (1959), hypotheses could never be proved, only falsified; however, falsification served to clear out the intellectual underbrush making way for better hypotheses. In contrast, Kuhn described normal science as being typified by long periods of incrementalism constrained by the need to fit new observations and theories within a settled explanatory framework or, in his terminology, paradigm. When working within a paradigm, Kuhn argued, scientific communities behave conservatively. They do not boldly test hypotheses with a view toward discarding them, but rather, resist falsification. Scientists tend to explain away or turn a blind eye to evidence that does not fit the accepted framework. A classic example of this phenomenon was the addition of epicycles to models of planetary orbits to preserve the Ptolomeic understanding of the solar system in the face of otherwise highly destabilizing observations.

In Kuhn’s view, only when anomalous observations and negative evidence accumulate to a breaking point might a revolution occur, precipitating a wholesale replacement of the old paradigm, such as the replacement of Ptolemaic with Copernican astronomy. Kuhn’s dichotomy is too simplistic and Procrustean to capture much of the history of science, including the history of biology. Although there are instances when his concept of a revolutionary paradigm shift fits, it is also true that normal science often exists for many years in parallel with clear-eyed hypothesis testing. Kuhn’s views combined with more recent work, such as that of Kahneman and Tversky documenting such cognitive distortions as confirmation bias, help explain this strange phenomenon by which scientific communities insulate themselves and resist needed change.

In any case, Kuhn might not have been surprised by what I observed. Several large scientific communities in the NIMH orbit ignored well-established methodologic advances, especially if they were developed within another discipline and violated their consensus explanatory frameworks. For example, from before my time at NIMH to the present, scientists who study psychopathology within psychology or psychiatry continue to accept candidate gene by environment (G X E) interactions as an established truth; within these fields, investigators still attempt to extend existing findings. Yet the population and statistical genetics communities that represent the sophisticated stewards of the relevant methods have definitively rejected candidate G X E approaches to psychopathology as conceptually confused (excessively reductive and positing more than additive effects for which there is no evidence), guilty of reliance on vaguely defined and ascertained environmental effects, and statistical sins such as failure to correct for multiple testing or attain reasonable statistical power (reviewed in Duncan and Keller 2011).

I came to the view that the only way to reprogram resources from backward, entrenched scientific communities was through structural reorganization and changes in policy. Rational discourse is no match for the powerful incentives that affect the worldview and actions of well-funded incumbents. Fortunately, when I arrived at NIMH, I was given a mandate from Harold Varmus to integrate the review of NIMH neuroscience and behavioral science grant applications into the larger NIH review system. NIDA and the National Institute of Alcohol Abuse and Alcoholism (NIAAA) had received similar mandates. Like NIMH, they had been overseeing the review of their own grants—a most unhealthy practice—as a result of a prior bureaucratic separation of our extramural grant-making into a now defunct Alcohol, Drug, and Mental Health Administration (ADMHA) that also made block grants to the states for service provision. Now extramural review was to be integrated into the broader NIH system. Instead of tinkering at the margins, I was able to convince my open-minded colleagues Zach Hall, Alan Leshner, and Richard Hodes (National Institute on Aging) to rethink the review of neuroscience and behavioral science proposals at NIH and start entirely afresh. NIAAA, which in those days exerted great efforts to separate itself from NIDA, based on considerations of turf instead of the needs of science, opted out and decided to integrate with a liver toxicology study section.

The reforms entailed much analysis, work, and engagement with investigators who served on the many committees that had been invited to design the new study sections. As would be expected from such a complex reform, the result needed adjustments when put into practice. This reorganization, however, permitted us to recognize the emergence of new fields and methodologies, to take account of newly formed intellectual connections, to break up groups that previously had acted like protective guilds, and to ensure that no study section was dominated by any one institute. The reform successfully created a larger and more open marketplace of ideas—for a time. Like any such human activity, the benefits waned over time as new self-regarding groups coalesced. It would have been ideal to renew such a process every decade or so, building in better evaluative tools than we did. The amount of work for everyone and anxiety for investigators was simply too great, and thus changes in review organization since that time have tended to be more piecemeal.

As promised before I took up my post, I commissioned an in-depth analysis of NIMH intramural research by a “blue ribbon” panel. One of their foremost observations was that there had been similar reviews in the past, but that the recommendations had not been acted on seriously. I did not disappoint this panel. The panel found some great strengths such as the primate neuropsychology program led by Mortimer Mishkin and the basic neuroimaging program, both world leaders. It also made many trenchant criticisms not only of individual basic laboratories and clinical branches, but also of governance processes. In response I strengthened the periodic reviews of the laboratories and branches (many of which had budgets of several million dollars each year) and gave them teeth. These subsequent reviews were organized and led with integrity by the two scientific directors who led the intramural program in succession, Susan Swedo and Robert Desimone. While recognizing the difficulties created for some investigators, we closed many of the irretrievably weak programs over the years, and I reprogrammed much of the money to extramural grant-making, with the greatest beneficiary being the extramural division that funded basic neuroscience.

I doubt that I would have wanted to start an intramural program if it had been up to me many years before; but the decision had been made long ago and I was responsible for the program and the more than $100 million in taxpayer funds that it spent. An important question was how to maximize the program’s strengths, which in many areas, were considerable. I worked on this issue together with my old friend and colleague Gerry Fischbach, who had replaced Zach Hall as director of NINDS—I had cochaired the search. We asked ourselves how we could lower barriers to collaboration across the two institutes, share expensive equipment, and increase cooperation on recruitments in a manner that would enrich the community intellectually. I give Gerry full credit for recognizing that the optimal solutions would require a new building.

The idea was to replace the old and incommodious Building 36 shared by our neuroscience programs with a modern building designed to maximize collaborative interactions. Building 36 seemed to have been constructed on the plan of a medieval monastery. The walls between the small, often depressing lab spaces were constructed of cinderblocks so that renovations required a jackhammer. Ultimately, we convinced Harold Varmus, Donna Shalala (then secretary of health), the White House Office of Management and Budget, and finally the U.S. Congress of the need for an upgraded neuroscience facility at NIH. The plan was a building large enough to bring together as many of the neuroscientists at NIH as possible and to configure the space to maximize collaboration. Although the full construction took years longer than planned, and was finished long after I left, the John Porter National Neuroscience Center seems to have accomplished what Gerry and I had envisioned. I worked closely and happily with Story Landis who replaced Gerry as NINDS director when he left to become vice president of Columbia University and dean of its Medical School. We ensured implementation of our vision of interdisciplinary collaboration, open collaborative spaces, and shared core facilities and equipment. After I left NIH at the end of 2001, Story shouldered the burden of fighting the human tendency to prioritize administrative silo-building over scientific collaboration.

I initially worried that some judgments I was making might be unfairly severe. However, discussions over many months with Harold Varmus, Zach Hall, Alan Leshner, Rick Klausner (National Cancer Institute), Tony Fauci (National Institute of Allergy and Infectious Disease), and other colleagues convinced me that the problems I had perceived were quite real—and that there was a strong expectation that I would take them seriously. From my savvy colleagues, I also got the good advice not to take on too many issues at once and not to assume an excessively confrontational stance. At the same time, however, I was intensely aware that NIMH received significant public funds and that I had been entrusted to oversee the allocation of those funds to the best science that would contribute to our mission of elucidating the pathogenesis of mental illness in the service of making much-needed advances in diagnosis and treatment—critical public health needs that had been languishing for decades. It helped me that I had no desire to remain an institute director for life. I mused that if I were somehow forced out of my position for acting on my convictions, my “punishment” would be a speedier return to academia.

That said, scientific groups that detect threats to their funding—and thus to their livelihood and sense of dignity—often react with fury, and I was, on more than one occasion, the object of such anger. For example, a group from the American Psychiatric Association (APA) complained to members of Congress and to Harold Varmus when I terminated the mechanism that awarded large, indefinitely renewable center grants to psychiatry departments. My recollection is that Harold declined to meet with the APA delegation. I did create a new, far smaller center program aimed at incentivizing interdisciplinary research, and named it for Silvio Conte, a congressional appropriator who had been a champion of NIH research. I insisted that the program permit only one renewal, on the assumption that after 10 years of funding, it would be time for members of a collaborative network to find other partners with new technologies and new questions. Overall, however, I preponderantly ended centers programs, thus creating a large infusion of money into investigator-initiated grants with a significant focus on basic neuroscience. Given that NIMH was one of the few institutes with no Mendelian disorders in its purview, I also supported investment in the development of genomic and computational tools to advance the analysis of polygenic disease.

A few other surprises awaited me. For example, I discovered that the lion’s share of NIMH career and training funds went toward the salaries of the most senior scientists in the field—despite their access to many other sources of funding—through a renewable career award mechanism (K05). After far more consultation and analysis than was really necessary to enact a just and sensible policy change, I terminated this mechanism and reprogrammed the funds to junior investigators. There was a campaign of outraged editorial writing (Holzman et al. 1998) and complaints. These did not change my view or the new policy, but they did reinforce my dark Augustinian-Hobbesian view of human nature.

There was no shortage of areas in need of attention, and on occasions in which there were topics of significance to the institute, I appointed a group from my advisory council (NAMHC) to work along with NIMH staff and extramural scientists to devise new policy recommendations. I made sure to provide clear charges to these groups, with encouragement to be bold, and made myself available for questions they might have. One example was a Genetics Workgroup that I commissioned in 1997. It was chaired by Sam Barondes (USCF) and included as members, Aravinda Chakravarti, Mary Claire King, Eric Lander, Robert Nussbaum, Ted Reich, Joe Takahashi, and Steve Warren.

This group was constituted in recognition of the failure of candidate gene and linkage studies in psychiatry, and in light of the growing recognition of the polygenic nature of these disorders, signifying that extremely large samples would be needed for genomic analysis. The workgroup recommended, and I implemented policies to establish, a repository to store DNA samples and associated phenotype data with the goal of facilitating large-scale genetic studies that would become feasible as genomic technologies matured. In concert, the workgroup recommended that NIMH require sharing of these banked DNA samples after a proprietary period of 12 to 18 months (which in retrospect was excessively long).

I also implemented the recommendation of a strong requirement for data sharing (one of the earliest such policies at NIH) with the goal of facilitating meta-analyses needed to achieve adequate statistical power as well as secondary analyses. The workgroup also recommended that informed consents be redesigned to permit wide sharing of data, encouraged international studies and studies of diverse populations, and recommended that NIMH genetics studies attain the scale necessary to investigate genetically complex disorders. This last recommendation militated against the inefficient and inevitably underpowered “biological candidate” gene studies common at the time. With the agreement of the NAMHC, no extramural grant applications with candidate gene designs were subsequently funded. However, within the intramural program, projects are reviewed retrospectively, not prospectively. For an intramural program this is the right procedure because prospective review could focus too much on feasibility and impede risk-taking. In this instance, however, it meant that several intramural clinical branches ignored the best advice of professional geneticists and NIMH policy and continued to perform wasteful and unscientific candidate gene studies. This had the further ill effect of influencing the work of neurobiologically oriented translational scientists worldwide who did not have the training to reject such false leads. Indeed, failures of translation across the yawning interdisciplinary gulf that lies between human genetics and neurobiology continue to trouble psychiatry research to this day (Hyman 2018).

In addition to my deep engagement with NIMH science, there were opportunities to engage through Congressional testimony in policy discussions on such issues as fighting for parity of health insurance coverage of mental disorders with general medical disorders, pushing for the broader adoption of evidence-based treatment of mental disorders, and advancing the idea that many juveniles in the criminal justice system deserved diagnostic workups for potentially treatable neuropsychiatric disorders. In June 1999, I participated in a White House mental health conference with President Bill Clinton, Hillary Clinton (who introduced me to the audience), and Al and Tipper Gore. Beyond the heady nature of such interactions, the conference had important practical results, most importantly, the president extended parity of mental health insurance to all federal employees. Many ethical issues also arose during my years at NIMH. Some related to the knotty problem of standards for informed consent when people suffered a severe mental illness. Other raised concerns that extended beyond traditional bioethics, touching on issues such as the effects of illness and treatment interventions on personal identity, moral agency, and other human characteristics dependent on the functioning of our brains. These considerations rekindled my interest in philosophy and ethics that contributed to my later becoming a founder of the International Neuroethics Society.

Given the rapidly changing technologies relevant to neuroscience and genetics, the remarkable advances in computing, and my unfinished business with respect to modernizing the scientific outlook and investments of NIMH, I could have fruitfully spent 10 years as director, but I did not. One piece of unfinished business for me was the system of disease definitions and classification in mental illness that were systematized in the American Psychiatric Association’s DSM, then in its fourth edition. Although knowledge of etiology and pathophysiology that would be necessary for a valid diagnostic system were clearly lacking at the turn of the 21st century, and is only very slowly emerging today, there was already much evidence that the DSM was grounded in conceptual errors. The major errors, about which I subsequently wrote (Hyman 2010) are (a) conceptualizing mental illnesses as discrete, discontinuous categories (like smallpox—either you have it or you don’t), instead of quantitative deviations from health (like diabetes mellitus); and (b) the elaboration, without evidence, of a large number of narrowly defined disorders so that many patients who receive a single DSM diagnosis receive many.

The problem for research was that the DSM system had been adopted as a shared language with the false view that it would enhance replicability—in fact, inter-rater reliability is quite poor using DSM definitions for many disorders. Moreover, major depression, the most common serious brain disorder afflicting humanity, is diagnosed by a person having to meet five of nine criteria for at least two weeks. This gives 256 different ways of meeting criteria, and some individuals in a study cohort might overlap on a single criterion. Because study sections and journal referees had come to demand DSM criteria in the selection of patients for study cohorts, many studies have been vitiated by enrolling extremely heterogeneous populations but imagining them as a valid class.

I had thought of initiating the development of a new set of research diagnostic criteria for 10–15 serious, common disorders. I never initiated such an effort because the state of the science seemed too premature. In particular, genetics had yet to yield useful results that might provide some partial grounding of diagnostic groupings in nature, instead of committee consensus. Perhaps if I had stayed at NIMH longer, I would have initiated such an effort, but even now, 17 years after my departure, it seems too early scientifically for a wholesale overthrow of existing diagnostic manuals, even though some such efforts have been made, and despite the fact that the DSM system remains a millstone around the necks of investigators.

In December 1999, Harold Varmus resigned from NIH to become the president of Memorial Sloan Kettering Cancer Center in New York City. NIH was left with indecisive acting leadership and thus much greater vulnerability to the whims of the Congress. I had gotten to know Al and Tipper Gore quite well. She was particularly committed to mental health issues, and it was clear that if Mr. Gore were elected, NIH and NIMH would flourish. Of course, George W. Bush was elected, and although he supported rapid growth of the NIH budget in the first years of his presidency, life at NIH quickly became difficult.

President Bush has a complex legacy in health care. His powerful support for the President’s Emergency Plan for AIDs Relief (PEPFAR) to distribute antiretroviral drugs to treat individuals with HIV/AIDS is arguably one of the most important large-scale medical interventions in history. It saved countless lives in the developing world, especially in sub-Saharan Africa, and President Bush deserves enormous credit. However, notwithstanding early acquiescence to Congressional plans to increase the NIH budget in his first three years, there was no evidence that the new administration supported science as an activity and, indeed, substantial evidence of hostility. Best known are the severe limitations the Bush administration placed on investigations of climate change and on federal funding of stem cell research.

For NIMH, this significantly impeded our ability to support development of much needed human cellular models with which to study molecular mechanisms that contribute to psychiatric disease. In addition, the administration exhibited profound distrust of scientists and science agencies. They instructed the NIH institutes that they were not to have their own press officers, who had long served to share discoveries and important health messages with the public. Instead any communication to be externally released was to be overseen by the Department of Health and Human Services, which was not staffed to understand biomedical research, and which was politicized. Most institute directors had developed close relationships with some members of the House and Senate and with their staffs, as I certainly had. Members were often interested in diseases that affected their own families and their constituents—matters unrelated to partisanship—and also wanted to understand the manner in which we spent the considerable discretionary funds that the Congress had entrusted to NIH and the peer review system.

The Bush administration instructed us that we could no longer have a Congressional liaison on our staffs and that we were no longer permitted to initiate meetings with the Congress. Furthermore, if a member of Congress requested a meeting, we were to inform the Department of Health and Human Services. The department would then send a watcher to sit in on our meetings to ensure our loyalty on matters such as budgets, stem cell research, and other topics that they deemed controversial. After about six months, I concluded that I could not, in good conscience, work in such an administration and quietly began thinking about alternatives.

As I thought about leaving NIMH, I was struck by how much I valued the staff, many of whom I had recruited, and how guilty I felt that I would not stay longer to watch out for them during a difficult time for science. I also began to realize that my personal scientific goals had evolved. For more than five years, I had worked flat out to advance the science of mental disorders. My personal lab was doing well, but it still focused on dopamine and second messenger regulation of gene expression. As I contemplated a move, I realized that I would want to change my personal scientific focus, so that I could help make progress on diseases, such as schizophrenia and mood disorders, to which I had dedicated myself as NIMH director. These thoughts were accompanied by a sense of despair because there was not an iota of scientific traction on disease mechanisms in 2001. Based on the high heritabilities of these disorders, it was clear that genetics would eventually yield molecular clues to pathogenesis, but not yet.

Based on the advice of the Genetics Workgroup of 1997 I had begun to put programs in place to maximize the likelihood of eventual success. The technology did not yet exist, however, that would permit genotyping and DNA sequencing inexpensive enough and accurate enough to identify specific alleles that conferred risk for highly polygenic conditions, such as schizophrenia and mood disorders. Without molecular clues that would eventually come from genetics, I saw no basis on which neurobiological investigation could proceed. It was during my period of scientific pessimism that Lawrence Summers, the new president of Harvard University, and U.S. treasury secretary during the last years of the Clinton administration, called me about the possibility of serving as provost (chief academic officer) at Harvard.

A Decade in the Scientific Time-out Box

Just as I had never imagined becoming NIMH director, it had never crossed my mind that I might become a university provost. In truth, when Larry first called me, I was not sure what a provost was. Yet Larry Summers’ vision for Harvard was compelling. One of his most important goals was to promote cross-disciplinary academic inquiry with a focus on science and engineering. He was thus seeking a scientist, ideally one who knew Harvard, who had experience in the leadership and administration of a large enterprise. If I took this position, it would permit Barbara and me to return to Boston with our three children—although once again, it would disrupt Barbara’s work and, for a second time, her local social networks.

Larry began recruiting me by stating that he saw interdisciplinary life sciences as perhaps the most important intellectual venture of the early 21st century. He recognized that Harvard had a strong faculty in diverse areas of biology as well as a large and accomplished clinical faculty based at the affiliated hospitals—in 2001, the hospitals had approximately 11,000 faculty members and currently about 14,000 of which approximately 2,000 are principal investigators with grants. Despite Harvard’s strengths, Larry thought that the university was not living up to its potential in the life sciences primarily because the different labs and departments across the Faculty of Arts and Sciences, Harvard Medical School, the Harvard School of Public Health, and the hospitals were highly balkanized. The possibility of taking on an entrepreneurial institution building role in light of Harvard’s resources was quite attractive.

There were negative aspects to the position as well. Most obviously, the provost position was relatively new at Harvard with poorly established responsibilities. Compared with essentially all other major research universities, the Harvard provost’s office was small and weak. Larry supported the idea of a strong provost and building a modern provost’s office at Harvard because he recognized that some central authority would be necessary to pull together scattered and often fractious elements of the university. That said, I was well aware of the skepticism of the faculty and the antagonism of many of the deans toward a stronger central administration. In considering the options, I increasingly felt alienated from the Bush administration—I had spent considerable time with the secretary of health and human services and with Bush administration staffers who were no friends of science. As Larry and I talked further, the prospect for strengthening science and engineering at Harvard seemed to outweigh the worrisome aspects of academic administration.

I began at Harvard at the end of December 2001. I did build a strong and effective provost’s office. More gratifying was the broad intellectual engagement that came from such diverse roles as chairing ad hoc committees that were the final step in tenure decisions across schools and disciplines, overseeing deans, hiring and supervising the director of a great art museum, reorganizing the world’s largest private library system, and finding some time to teach bright undergraduates. In terms of enhancing the life sciences, I negotiated the Harvard side of the agreement with MIT (represented by their provost Bob Brown) and the philanthropist Eli Broad that established the Broad Institute of MIT and Harvard, where I now spend the preponderance of my time. I worked with another philanthropist, Hansjoerg Wyss, to create an interdisciplinary and cross-school institute that works at the boundaries between science and engineering. I also helped create the first department at Harvard that spans the Faculty of Arts and Science and Harvard Medical School.

The plan was for me to serve as provost for about five years, and to make the kind of progress that I described. But plans do not always survive contact with reality. Larry was brilliant and visionary but also brusque and—I think that he would himself agree—remarkably impolitic. By the spring of 2006, he was on his way out of the Harvard presidency, and the university was in turmoil. A new president, Drew Faust, begin in 2007 but soon thereafter markets crashed, and the great recession began. My hopes of moving on were impeded by the circumstances: I did not think it ethical to abandon the university and a new president at such a troubling time. In the end, I served for nearly a decade, far longer than I had planned.

I was repaid for these extra years because the Broad Institute, which I had been deeply involved with early in its history, had matured and was a wonderful place for collaborative science. Most unexpectedly, during my decade as provost (and from a scientific perspective, my decade in the “time-out” box), genomic technology and computing resources had advanced to the point at which psychiatric genetics could succeed. In addition, stem cell technologies and genome engineering had come of age and single-cell transcriptomics was on the horizon. New approaches to systems-level neurobiology were also moving ahead quickly, later to be accelerated by President Obama’s BRAIN Initiative in the United States and by diverse national and international brain projects across the world. There was no longer reason to despair about psychiatric research. Although still exceedingly difficult, it was now possible, beginning with genetics, to gain traction on disease mechanisms.

I was particularly fortunate that a psychiatric disease program had been initiated at the Broad Institute by Ed Scolnick, who had retired after many years as president of Merck Research labs. The plan for the center was to attack the biology of serious mental illness beginning with insights gleaned from genetics, but the main goal was to use emerging knowledge to advance therapeutics. Thanks to the philanthropy of Ted and Vada Stanley, the program was renamed the Stanley Center for Psychiatric Research at the Broad Institute. Ed Scolnick wanted to be able to focus on therapeutics research in the years before his second retirement. Thus, in spring 2012, I became director, the start of a new adventure.

I have had to learn a great deal about the design, implementation, and analysis of large-scale, unbiased human genetic studies. Because these studies are yielding results (with nearly 100,000 schizophrenia patients studied by genome-wide association, and nearly 30,000 by whole exome sequencing), I have had the opportunity, along with brilliant colleagues, to advance the development of model systems that permit us effectively to interrogate hundreds of allelic variants of small effect (McCarroll and Hyman 2013; Hyman 2018). These include thousands of patient-derived pluripotent cell lines that increasingly can be differentiated into specific neural cell types and studied in massively parallel experiments that minimize technical variability while permitting examination of genome-engineered variants against large numbers of human genetic backgrounds. In addition, emerging model systems include human brain organoids with diverse genetic backgrounds and engineered mutations, and marmosets genetically engineered with CRISPR-Cas 9. The interrogation of polygenic human brain disease will be extremely challenging. Nonetheless, especially in light of the despair that I felt upon leaving NIMH, I now feel quite fortunate to have great colleagues, remarkable philanthropic and federal funds, and access to the technologies that are beginning to elucidate the mechanisms of schizophrenia, bipolar disorder, ASDs, and other dreadful illnesses.

References

Comb M, Hyman, SE, Goodman, HM. Mechanisms of trans-synaptic regulation of gene expression. Trends Neurosci 10:473–478, 1987.

Duncan, LE, Keller, MC. A critical review of the first 10 years of candidate gene-by-environment research in psychiatry. Am J Psychiatry 168(10): 1041–1049, 2011.

Egeland JA, Gerhard DS, Pauls DL, Sussex JN, Kidd KK, Allen CR, Hostetter AM, Housman DE. Bipolar affective disorders linked to DNA markers on chromosome 11. Nature. 325(6107): 783–787, 1987.

Galison, P. Einstein’s Clocks, Poincare’s Maps: Empires of Time. New York, Norton, 2003.

Hall, Z, Ed. Introduction to Molecular Neurobiology. Sunderland, MA: Sinaeur Associates, 1992.

Holzman, PS, Kupfer, DJ, Andreasen, NC. On preserving the National Institute of Mental Health Career Scientist Award. Arch Gen Psychiatry 55(1): 12–14, 1998.

Hyman, SE, Ed. Manual of Psychiatric Emergencies. Boston: Little, Brown, 1984; 2nd edition, 1988.

Hyman, SE. The diagnosis of mental disorders: The problem of reification. Annu Rev Clin Psy 6: 155–179, 2010.

Hyman, SE. Revolution stalled. Sci Transl Med 4(155): 155cm11, 2012.

Hyman, SE. Back to basics: Luring industry back into neuroscience. Nat Neurosci 19: 1383–1384, 2016.

Hyman, SE. The daunting polygenicity of mental illness: Making a new map. Philos Trans R Soc Lond B Biol Sci 373(1742): 20170031, 2018.

Hyman, SE, Arana, GW. Handbook of Psychiatric Drug Therapy. Boston: Little, Brown, 1987; 2nd edition (GW Arana and SE Hyman), 1991; 3rd edition (SE Hyman, GW Arana, and JR Rosenbaum), 1995.

Hyman SE, Jenike, M., Eds. Manual of Clinical Problems in Psychiatry. Boston: Little, Brown, 1990.

Klerman, GL. The psychiatric patient’s right to effective treatment: implications of Osheroff v. Chesnut Lodge. Am J Psychiatry 147(4): 409–418, 1990.

Kuhn, TS. The Structure of Scientific Revolutions, 2nd edition. Chicago: University of Chicago Press, 1962.

Marshall, E. New NIMH director offers institutional stimulant. Science 271(5256): 1662–1663, 1996.

Marshall, E. NIMH to screen studies for science and human risks. Science 283(5401): 464, 1999.

McCarroll, SA, Hyman, SE. Progress in genetics of polygenic brain disorders: Significant new challenges for neurobiology. Neuron 80(3): 578–587, 2013.

National Institute of Mental Health. Genetics and mental disorders: Report of the National Institute of Mental Health’s Genetics Workgroup. https://www.nimh.nih.gov/about/advisory-boards-and-groups/namhc/reports/genetics-and-mental-disorders-report-of-the-national-institute-of-mental-healths-genetics-workgroup.shtml#acknowledgments (accessed January 1, 2018).

Nestler, EJ, Hyman SE. Animal models of neuropsychiatric disorders. Nat Neurosci 13(10): 1161–1169, 2010.

Popper, K. The Logic of Scientific Discovery. London: Routledge, 1959.

Sanes, JR, Lichtman, JW. Can molecules explain long-term potentiation? Nat Neurosci 2(7): 597–604, 1999.

Schizophrenia Working Group of the Psychiatric Genomics Consortium. Biological insights from 108 schizophrenia-associated loci. Nature 511: 421–427, 2014.

Torrey, EF. Bird brains. The Washington Monthly, May 1, 2001.

Eve Marder

BORN:

New York City, New York

May 30, 1948

EDUCATION:

Brandeis University, Waltham, Massachusetts, AB (1969)

UCSD, La Jolla California, PhD (1974)

APPOINTMENTS:

Assistant Professor, Biology Department, Brandeis University (1978–1984)

Associate Professor, Biology Department, Brandeis University (1984–1990

Professor, Biology Department and Volen Center, Brandeis University (1990–present)

Cornelius Wiersma Visiting Professor of Biology, Caltech (1994–1994)

Victor and Gwendolyn Beinfield Professor of Neuroscience, Brandeis University (1994)

Chair, Biology, Brandeis University (1996–1997; 1998–1999)

Head, Division of Science, Brandeis University (2010–2014)

Senior Fellow, Janelia Research Campus, (2015–present)

HONORS AND AWARDS (SELECTED)

Fellow of the American Association for the Advancement of Science

Elected American Academy of Arts and Sciences (2001)

Miriam Salpeter Lifetime Achievement Award, Women in Neuroscience (2002)

W. F. Gerard Prize, Society for Neuroscience (2005)

Elected National Academy of Sciences (2007)

Fellow of the Biophysical Society (2008)

President, Society for Neuroscience (2007–2008)

Honorary Doctor of Science, Bowdoin College (2010)

George A. Miller Prize, Cognitive Neuroscience Society (2012)

Karl Spenser Lashley Prize, American Philosophical Society (2012)

Gruber Prize in Neuroscience (2013)

Elected National Academy of Medicine (2013)

Fellow of the International Society for Neuroethology (2014)

Education Award, Society for Neuroscience (2014)

Inaugural Fellow of the American Physiological Society (2015)

Kavli Prize in Neuroscience (2016)

Member, Norwegian Academy of Sciences (2016–present)

Honorary Degree, Tel Aviv University (2017)

Marder studies the dynamics of small neuronal networks, and her work was instrumental in demonstrating that neuronal circuits are not “hard-wired” but can be reconfigured by neuromodulatory neurons and substances to produce a variety of outputs. For the past 25 years, Marder’s lab has combined experimental work with insights from modeling and theoretical studies. Together with Larry Abbott, her lab developed the programmable dynamic clamp, now used widely in laboratories around the world. Her lab pioneered studies of homeostatic regulation of intrinsic membrane properties, and stimulated work on the mechanisms by which brains remain stable while allowing for change during development and learning. Marder is now studying the extent to which similar network performance can arise from different sets of underlying network parameters, opening up rigorous studies of the variations in the individual brains of normal healthy animals.

Eve Marder

Introduction

Initially, I set out to write a chronological account of my development as a neuroscientist, weaving together my personal and professional development and, hopefully, maturation. I realized that sadly, I do not have the space to write about the beautiful work of all of the 27 PhD students, 46 postdocs, and many undergraduates who have worked in my lab since 1978. I apologize that I have not had the space to do justice to all of your beautiful work and to the myriad contributions of all of our collaborators. I have focused more on my early years because when I travel around the world, I meet many young people who are curious how I got started and what the world was like at the beginning of my career. Moreover, there are my writings and online lectures from my later years, but none of that existed when I was beginning my career.

Many of my previous trainees have remained in academic science, and many have moved into a variety of other careers in which their discipline, intellectual integrity, and sense of humor have allowed them to shine. I am proud of them all. I learned much from every member of my laboratory and thank you all for your time, intelligence and thoughtfulness. Indeed, perhaps the single and most important message one learns as the head of a laboratory is that no matter how smart or intuitive any one of us is, the collective intelligence of a laboratory is always richer and more insightful than any one person can be. I can trace most of the best science with which I have been associated to my willingness to listen to what people of my laboratory were saying. I suppose it has helped that I have always attracted interesting and adventuresome people, so all I had to do was to make sure that they looked carefully at their data.

As I started writing, I realized that I have made many professional choices for reasons that were not overtly scientific. Some of these choices were determined by personal ethics as related to science, community, and publication processes. It has become a truism that all science is done by community. Nonetheless, many of our present practices create conflicts between what is best for the individuals who are actually generating data and what is best for lab heads. Likewise, many of our attitudes toward publication create dynamics that are potentially wasteful of both human capital and funds that are used to generate data. And, although we collectively embrace a commitment to diversity in our professional lives and institutions, I continue to encounter situations that show the commitment to diversity does not extend to action. As a female scientist, soon to be 70 years old, I could not move through our profession without watching and listening carefully, and then deciding what to emulate and what to ignore. Those of us women who became “successes” from those years had to be either profoundly clueless (a very useful strategy, if one can pull it off) or very good at listening and watching. So, intermingled into this autobiography are some of the lessons I learned about our scientific culture as I moved through my career.

Beginnings

I was born on May 30, 1948, at the Columbia Presbyterian Hospital at 168th Street in Manhattan. My father was just 23 and my mother was 21. My father was born in Vienna and came to New York when he was 14. My father went to City College, along with many of his generation of Viennese immigrants. My mother was born in the Bronx. Sadly, her mother died from a childbirth infection associated with my mother’s birth, and she spent the first four years of her life in an orphan asylum. Her father eventually remarried and took her to live with him, her older sister, and his new wife. My mother left home at 17, as she wished to go to college, and her father wanted her to get a job. My mother was one of the first women to enter City College, where she met my father. She dropped out of school when she became pregnant, but eventually she returned to school to earn her bachelor’s degree when she was in her 60s.

My earliest memories come from the days we lived on Manhattan’s Upper West Side, on 84th Street between Columbus and Amsterdam Avenues. It was walking on Central Park West that my mother taught me that north was uptown, south was downtown, west was the Hudson River, and east was Central Park. As a three-year-old, I had a flawless sense of direction, given a universe on a grid, and somehow, being so carefully taught the four directions of the compass has stayed with me much of my life.

My parents were poor in those early years. We lived in a walk-up on a high floor (the slum building was later torn down to build Brandeis High School). My parents didn’t have enough money to pay for a nursery school, but my mother managed to get me a scholarship to a nursery school because “I played well with others.” I remember my mother carrying groceries and my stroller up many flights of stairs when she was pregnant with my brother, who was born in October of 1951.

The first scientific experiment that I remember carrying out was in the 86th Street Central Park playground. The Central Park playgrounds have vertical bar railings, and at the ripe age of three or so, I was curious if my head would fit through the railings. So, I did my experiment and put my head through the railing and promptly got stuck. This was a life-defining moment for me, because as I sat there with my head between the rails I felt unbelievably stupid, as I realized I could have used my hands to measure the relevant distance. Indeed, I date this as my first self-conscious awareness of myself as a critical decision-making person.

As all the mothers at the playground started panicking, my mother calmly walked over, picked me up, twisted my body sidewise, and pushed me through the railing, saying that babies were born head first, and she figured that my head was more important than a few scrapes on my arms or legs. I never doubted that my mother would “save me,” but I remember being incredibly proud and comforted by her commonsense problem-solving intelligence.

When I was four and a half, we moved to Ridgefield, New Jersey, just across the Hudson River. We lived in a small garden apartment in a modest suburb. My parents made no particular attempt to teach me to read before I started school, and in first grade, we were taught to memorize words with the now-infamous “Dick, Jane, Spot” books. After a month of first grade, my father asked me if I could read, and I said I could read the words I had been taught. He said either I could read or I couldn’t, and he handed me the New York Times and said “read.” Thus, I discovered that I knew how to read. My mother took me to get a card at the small public library next to the elementary school, and over the next few years, I systematically read every book in the children’s section of the library. One day as I happened to be reading a science book, my aunt asked me what I wanted to be when I grew up, and I answered, “a scientist.” She nodded happily, and from then on whenever grownups asked me that question, I said “scientist” because it deflected all further conversation.

I was 10 years old when we moved to Irvington, New York, a small town on the Hudson River, a 45-minute train ride from Grand Central Station. My father took the train to work, and I entered the fifth grade. I discovered that I loved stringing words together in essays. Unusually, I had a young male teacher. He taught us “math” by organizing the class into teams for “math races,” which made us fast and accurate at adding up long strings of numbers and at doing complex long divisions on the blackboard. In fifth grade, I realized that I could remember my textbooks almost verbatim, by imaging the pages in my head and rereading those stored images for names and dates. Only much later did I learn that this kind of eidetic memory is relatively rare, and usually goes away as children mature. In me, it persisted to a greater or lesser degree throughout high school, and this made it easy for me to remember names and dates of kings and queens of European countries, or for that matter, the Krebs cycle. Sadly, by the time I reached organic chemistry, it had mostly deserted me. It remained to some extent, as for many years I remembered the authors, years, and journals of the scientific papers I had read by visualizing the front page of the article.

In 1960, I was 12, my sister was born, and my father started a market research firm. My sixth-grade teacher let us work on our own, and she spent most of her time with the students who needed help. A few of us raced to finish our sixth-grade math workbooks and did so in a few months. She then gave us eighth-grade math books. In the spring, when I had finished eighth-grade math, she came back with an algebra book. A few days before the end of the school year, I went up to my teacher and told her I wasn’t going to do eighth-grade math again, because I had done it. I don’t know what impelled me to be so brazen, but I just couldn’t face redoing endless problems about percentages and interest rates. My teacher looked at me, and said, “Oh.” On the last day of class, I was promoted into the eighth grade and was placed in ninth-grade algebra, with students two years older.

I only realized much later how good Irvington High School was in the early 1960s. I learned grammar, algebra, geometry, calculus, chemistry, and physics. I learned the amendments to the U.S. constitution (quite relevant today). In advanced biology, I studied respiration and photosynthesis and first learned about action potentials and synaptic potentials from Scientific American articles. But most important, I wrote long and detailed term papers, several of them 100 pages in the days before word processors. In 10th grade, I did an analysis of how black history was treated in the American history textbooks used in high schools. To do this, I read W. E. B. Du Bois, and other African American scholars and discovered, not surprisingly, that the history books used in our schools told a very different story than that depicted by the scholars of the civil war and later. In 11th grade, I did a term paper on Karl Marx. In 12th grade, I wrote a 100-page paper on Walt Whitman’s poetry. To do the research for these papers, on Saturdays, I would take the train to New York City and go to the reading room of the New York Public Library, which was a magical place. At that time in my life, I didn’t have a particularly favorite subject, probably because it was all new, and therefore interesting. My wonderful biology teacher, Bernice Essenfeld, gave me an advanced biology textbook when I announced I wanted to take the Biology SAT at the end of my sophomore year. So I read the entire book from cover-to-cover on the subway and trains on my trips to NYC, and I remembered enough to score an 800, which my teacher promptly told me wasn’t as difficult as getting a 100 on the NY State Regents exam, because you could miss a question on the SAT and still score an 800!

At age 16, when I was applying to college, I knew that there were many people smarter than I. I was rejected by Radcliffe College (the women’s branch of Harvard) after an interviewer told me that they didn’t know how to evaluate my grades because they had never before seen an application from Irvington High School. When I told her that I thought the whole purpose of the SAT exams was to provide more objective criteria (all of my SATs were very good), she said, “Well, I guess you are academically strong enough, but we are looking for young women who belong here.” I understood that was code for saying that I was a smart Jewish girl from Westchester County but not special enough for them to overlook that I was a smart Jewish girl from Westchester County. When I started college in the fall of 1965 at the recently established Brandeis University, I knew that I would get an excellent education and not be part of the “in-group” provided by an elite institution. The same was true four years later when I started graduate school at the even younger University of California, San Diego (UCSD).

College Years

I was at Brandeis from 1965–1969, at the peak of the 1960s. Brandeis was center-stage for much of the civil rights and antiwar foment, and it had attracted a large number of interesting and quirky students. Many of my friends were politically active, and they studied (or not) philosophy, art, sociology, comparative literature, math, and everything in between. My favorite freshman year courses were humanities and politics, in which we read the greats of political theory and classics of literature. I thought about being an English major, but became a politics major, because at the time, I wanted to become a civil rights lawyer. I struggled with my math course, which was an introduction to formal analysis. I went through the motions and worked hard, but I knew it was over my head (I don’t know whose brilliant idea it was to teach freshmen analysis rather than calculus or linear algebra). I enrolled in biology and honors chemistry my sophomore year because I reasoned it would be easier to go to graduate school in English with a biology major than to graduate school in biology with an English major. I was horribly bored by my sophomore biology course because it largely repeated what I had learned in high school. I detested my course on the politics of post–World War II Europe. It seemed to consist primarily of learning the names and policies of endless political parties, all of which had alphabetic acronyms that defied understanding in terms of what their politics actually were. I switched my major to biology.

My favorite course that year was Yeats and Joyce, taught by the poet Allen Grossman. Grossman spoke in a remarkably rich and redolent prose that used the whole of the English language, and I was fascinated that he spoke language that I had only ever seen written. To this day, I remember some of his lectures, as they addressed some of the deepest and most subtle issues of how humans make flawed and heroic decisions. It wasn’t until my junior year that I hit the biology courses that spoke to me as deeply as reading Joyce, Faulkner, or Virginia Woolf. First semester, I took genetics, with Chan Fulton, who taught with classic original papers. Also that semester, I took a course in abnormal psychology. The professor made a comment suggesting that schizophrenia might arise from deficient inhibition in the brain. I had never heard about inhibition in the brain, so I did a term paper to discover whether it is possible that deficient inhibition could account for schizophrenia. I went to the science library and read everything I could find about inhibition in the brain. This was 1967, and it was still possible to read a fair bit of what was known about inhibition in the brain. But, more important, in so doing, I decided I was going to be a neuroscientist.

The next semester, I took Andrew Szent-Gyorgyi’s course on nerve and muscle, and a course on schizophrenic language. The latter was really an introduction into what today would be cognitive neuroscience, and the former led to my senior year thesis in Szent-Gyorgyi’s lab, doing experiments on muscle protein polymerization, as there were no neuroscientists then at Brandeis. I kept reading neuroscience and turned all the papers I wrote for other biology courses into neuroscience topics. I was fascinated by the work being done on denervation supersensitivity, as well as the early work on the specificity of connections in the retinal-tectal pathways. I was drawn to functional questions that eventually would be addressed with cellular or molecular approaches.

When it came time to apply to PhD programs, I wanted to go to the West Coast. So I applied to the University of Oregon, Berkeley, Stanford, and UCSD. Additionally, I applied to the Neurobiology Department at Harvard because Szent-Gyorgyi was a close friend of Steve Kuffler’s, and he said it was the best place in the world to do neurobiology. I had strong grades, albeit not spectacular ones, having been perpetually unable to get A’s in courses that bored me, and had (I know now) outstanding GRE scores. I knew it unlikely that I would get into Stanford biology because they were widely said to have a quota on women (2 out of 12). Additionally, Stanford would take only one student from any undergraduate institution, and one of my classmates already had been offered admission. I was offered admission by UCSD, Berkeley, and the University of Oregon, but I was waiting to hear from Harvard.

In 1968, it was unusual for departments to interview applicants, but Harvard Neurobiology invited three of us for a whole day interview in the department. That day was the beginning of a career-long friendship with Ron Calabrese, who eventually went to Stanford, and now is an eminent neuroscientist at Emory University. The third interviewee, Bruce Wallace did enter the Harvard program. I waited until April without word from Harvard, until I called to find out that I hadn’t been offered admission, cried for 20 minutes and decided that fate was sending me west.

At the time, UCSD biology had no neuroscience faculty, but the Brandeis faculty advised me to learn modern molecular biology and then “specialize” in neuroscience. I decided against Oregon because I was told it rained all the time. Someone from Berkeley called to tell me I was the strongest applicant in their pool, so declined their offer, as I wanted to be with people smarter than I was. UCSD was on the beach, and I had fantasies of putting an experiment into the ultracentrifuge for two hours, going to the beach, and coming back to work.

I accepted the UCSD offer, graduated from college, and headed off for a summer of hitchhiking all over Europe, with Europe on $5/day. At the end of the summer, I hitched from Italy back to London in two days, alone. These were the days before the Internet or cell phones, but I sent my parents and sister daily postcards.

That summer, I saw lot of museums and monuments, but most notably, I walked many miles as I was happiest just exploring the streets and watching people. I loved Rome, although I realized years later that I was there in August and most of the Romans were gone, and the only people on the streets were tourists. It rained for five days when I was in Paris, and it was years later that I saw Paris’s beauty. In those days, you could tell the nationality of someone from his or her clothes and shoes. I came home from Europe, strong, tan, and the thinnest I had been since graduating from high school. In thinking back to that summer, I see that I was adventure-seeking but with extraordinary caution.

UCSD

When I flew off to southern California to start at UCSD, a brand-new institution with an extraordinary faculty, I felt it only fitting, to once again find myself at an institution just building itself, with excellence but no track-record. UCSD, as Brandeis before, gave me the freedom to find my own voice.

Allen Selverston joined the faculty in biology at UCSD the same year I started in the PhD program. In retrospect, I could not have had a better thesis supervisor. Al knew how to do things, to build things, and how to make things work. He had, even at the beginning of his career, outstanding biological intuition, and the work in his laboratory presaged much of what is happening today in circuit analysis and connectomics. Indeed, Al articulated quite clearly in the 1970s what many working in circuits today are only beginning to understand. Most important for me, he provided an environment and space that allowed me to make my own mistakes and my own discoveries. So when I completed my PhD, I knew that I had done the work independently, and I credit him, to his day, with understanding that independence was the best gift a thesis supervisor could have given to the student I was at that time.

It was only many years later that I realized that 1969 was a watershed moment for the entrance of women into life sciences PhD programs in the United States. The year before, the draft laws were changed and PhD programs were no longer eligible for draft deferments. Consequently, many young men went into MD programs (which were still draft deferrable) and into a number of new MD and PhD programs. Others left the country, were drafted, or became conscientious objectors, and ended up working jobs that delayed their entrance into PhD programs. So the entering pool of male PhD applicants dropped. Thus, while in 1968 and the prior years there were 2 women in a class of 30 at UCSD, my class had 13 women in a class of 30. Over the next few years, entrance into life sciences PhD programs became virtually 50:50 across the country. By the end of the Vietnam War, and its associated draft, the barriers for admission to PhD programs in life sciences were mostly gone. When we arrived that fall of 1969, the faculty were wondering what they would do with all of us. By May, when we were settling into labs, everyone had forgotten it was an issue. What I find most astonishing, looking back at this time, is how normal and acceptable the quotas on female admission to graduate programs were.

While we put up with incidents that would be actionable harassment in today’s world, we mostly rolled our eyes when the guys said preposterous and overtly sexist things. One of my rotation supervisors kept telling me to quit graduate school and get married and have six babies. After five weeks of this, I got so annoyed that I told him I was going to spend the last two weeks of the rotation in the library. He smiled and said he thought that was a great idea. Eventually, my rotation class figured out that this faculty member didn’t want any PhD students, but was obliged to take rotation students. He therefore designed a different torture for each rotation student, and none of it was personal. He and I eventually became tennis friends.

The women of my peer group found excellent advisors, and many of them went on to successful careers, despite the fact that there were few female faculty, and certainly no one with whom I could identify. This was a world before “mentoring” and “professional development,” but the young and forward-thinking faculty of UCSD had among them enough reasonable people to allow the female students to find advisors. I believe that the men and women students succeeded approximately equally.

Selverston and many of his generation came from PhD programs in which graduate students were supposed to earn their PhDs by demonstrating their ability to do independent work. When I started in Al’s lab, he gave me a pile of brand-new equipment (which thankfully had manuals written in English), and told me, “Go play for a couple of months and then tell me what you want to do for your thesis.”

I had become fascinated with transmitters and receptors as an undergraduate. Therefore, it was no accident that my PhD thesis project was to determine the identity of the transmitters used in the stomatogastric ganglion (STG). Don Maynard, at the University of Oregon, had developed this preparation to use it as a model system to understand how central pattern generators (CPGs) worked. The STG was ideal because it had a small number of large neurons, all of which could be identified, and it continued to be rhythmically active when removed from the animal. Selverston went to Bermuda the summer between my first and second year in graduate school to work with Maynard. He came home with the STG preparation, and he worked exclusively on it from then on. Although the STG has only about 30 neurons, it generates two different motor rhythms. The faster pyloric rhythm is pacemaker driven and is always active. The slower gastric mill rhythm is episodic and is seen only after the animal has fed or is exposed to food. Selverston and his lab did important work on the synaptic and cellular mechanisms of the generation of both rhythms.

My goal was to determine the identity of all of the chemical signaling molecules in a complete circuit, rather than study individual transmitter molecules in isolation. Even then, I had the intuition that there were insights to be gained by trying to understand the choreography of all transmitter (and now modulator) action in functionally active circuits. To this day, my laboratory continues to work on these questions.

The early 1970s were simpler days for a graduate student. I read a considerable fraction of what was published on transmitters, receptors, and pharmacology in invertebrates. I discovered Dick McCaman, Jimmy Schwartz, David Barker, JacSue Kehoe, Philippe Ascher, Ed Kravitz, and Hirsh Gershenfeld from the literature. Dick McCamon, Jimmy Schwartz, and Ed Kravitz had pioneered methods of single neuron transmitter identification (Otsuka et al. 1967; Giller and Schwartz 1971; McCaman et al. 1984). Most notably for me, Jimmy and Dick had worked on single neuron choline acetyltransferase assays (McCaman and Dewhurst 1970; Giller and Schwartz 1971). Dick was 120 miles up the road, in Los Angeles, so one day I got in my car and drove up to City of Hope to learn his methods. He became a great friend for years. I met Jimmy Schwartz when he came to UCSD for a seminar, and he also became a very special friend, who read and critiqued my first grant proposal several years later. David Barker was a postdoc in Ed Kravitz’s lab where he identified octopamine in lobsters (Barker et al. 1972) and became interested in amine modulation. It was he who first understood the results I had obtained when I had applied every transmitter candidate known then to neuroscience on the STG. And it was the extraordinarily elegant papers of Kehoe, Ascher, and Gerschenfeld (Ascher 1972; Kehoe 1972a, 1972b, 1972c; Gerschenfeld 1973; Gerschenfeld and Paupardin-Tritsch 1974a, 1974b) that pointed the way to the kind of clean neuropharmacology that I aspired to do. It was not an accident that on finishing my thesis, I decided to spend a year in Oregon in David Barker’s lab before I was able to move to Paris to work at the Ecole Normale Supérièure, in the Kehoe–Ascher–Gerschenfeld group.

My days at UCSD were happy. Soon after I joined the lab, Brian Mulloney came as a postdoc, and he was a source of daily encouragement and much knowledge. Largely inspired by the work on denervation supersensitivity, I was fascinated by the question of how a neuron that received synaptic inputs from many different neurons would regulate the number and distribution of its receptors. I had the notion that answering this question in the STG would provide critical insight into what central nervous system neurons might be doing. This was before slice preparations, so it was easy to see the allure of asking this question with the STG. To that end, I learned the STG preparation, and I tried all of the agonists I could buy on the STG. I discovered that every putative transmitter I applied to the STG changed the pyloric rhythm in a different way. I decided that this wasn’t going to tell me very much about the transmitters used by the STG neurons, but this observation was the first indication of the extent of neuromodulation that eventually would be one of the major foci of my scientific work.

I turned to trying biochemical methods for transmitter identification. I spent a while developing micro-dansyl chloride chromatograms, which told me that there was a lot of taurine in the STG. Eventually, I visited Dick McCaman and learned his method of single-neuron dissection after ethylene glycol freeze substitution. When it was clear that this was going to work on single-STG neurons, Dick told me that Dave Schubert at the Salk Institute was also doing choline acetyltransferase assays, and I should talk to him. When I went over to see Schubert at the Salk, Schubert invited me to do the choline acetyltransferase assays in their lab—so that is what I did. At the time, the Salk group in which I worked included Dave Schubert, Jim Patrick, Yoshi Kidokoru, and Steve Heineman. They were young, were extraordinarily patient and kind with me, and became an endless fount of relevant expertise, both with regard to biochemistry and cellular electrophysiology. It was Kidokoru and Heineman who gave me advice on ACh iontophoresis.

My routine was to physiologically identify the STG neurons, dissect them into tiny individual glass test tubes, and freeze them on dry ice and to put the ice bucket into the freezer for a day or two until I had enough identified neurons. At that point, I took the ice bucket to Salk for the choline acetyltransferase assays. Statistics weren’t part of our training, but I was concerned that the single-neuron enzyme signal was small. I ran as many blanks as neurons in each assay (usually 10–15 in each run) and used a cut-off for what I called “signal” that was 5–10 cpm higher than the highest of the blanks. My logic was that the range of the blanks, if I ran enough of them, would allow me to sample the random error in the assay. In retrospect, I realize I had created an experimental p-value.

The choline acetyltransferase assays showed strong positive signals in several classes of identified neurons and were consistently negative in other classes of neurons. Most of the STG neurons are motor neurons that make excitatory synapses on specific stomach muscles and inhibitory synapses on other neurons in the STG neuropil. I quickly figured out that the muscle targets of these neurons provided an easy place to assess the possible transmitter candidates. Among the choline acetyltransferase–positive neurons were the pyloric dilator (PD) neurons that innervate four sets of extrinsic stomach muscles. Using these muscles, I determined that the muscles contracted in response to ACh and carbachol, that iontophoretic applications of ACh produced muscle depolarizations, and that curare blocked the synaptic potentials in the muscles evoked by nerve stimulation. The muscles innervated by the neurons that did not have choline acetyltransferase contracted in response to glutamate, which we now know is the transmitter used by those neurons, both at their excitatory neuromuscular junctions and at their inhibitory junctions in the STG neuropil. At the end of my PhD, I had a tentative transmitter candidate for each of the identified motor neurons in the STG (Marder 1974, 1976).

Postdoc Years

After a year at the University of Oregon in David Barker’s lab where I did iontophoresis onto STG neurons and discovered that they responded to amines and amino acids, I packed up to move for a postdoc in the Kehoe–Ascher–Gerschenfeld and colleagues group at the Ecole Normale Supérieure under the auspices of a Helen Hay Whitney Fellowship.

Because I had worked entirely independently as a graduate student and had dealt successfully with Selverston’s version of benign hands off advising, I assumed I would have no problem adapting to the Paris lab. But moving to Paris presented unexpected challenges.

I had studied French in high school and college, but I had never spoken it, or really heard it. Nine years after my last French class, I arrived in Paris and did not understand a word. Everyone in the lab spoke English, but all lab conversations were uncompromisingly in French, except those that were one-on-one with me. I learned French for the second time; this time it wasn’t the conjugation of the future subjunctive, but it was lab and Parisian slang. While in Paris, I had the frustrating sensation that there was a wall between the part of my brain that had studied French from books when I was in school and the part of my brain that became reasonably fluent in conversational French. I never lost my American accent and was reminded of that whenever a Parisian cab driver willfully refused to understand the way I pronounced “Rue Descartes.”

I had come from a laboratory at UCSD that was part of the “simple systems, circuit cracking” field (doing then with electrophysiology and dye-fills what people today are doing genetic lines, optogenetics, and so on in flies, worms, and mice), and I was entering the world of channel biophysics. Consequently, I had to learn French and biophysics at the same time, just to follow the conversations at the lunch canteen. My new French colleagues were friendly and supportive, but when I arrived, I was woefully ignorant of quantitative membrane biophysics. Philippe Ascher, whom I eventually grew to love dearly, terrified me, as I had the impression that stupid things fell out of my mouth whenever I talked to him. JacSue Kehoe was unbelievably generous; she fed me dinner multiple times every month, made sure I was okay and introduced me to people she thought I might like. JacSue had more energy than anyone I had ever met before: She did extraordinary experiments, raised her young sons, and adopted any number of stray foreigners. When I first arrived, she asked me to make a preparation so that she could replicate some of my experiments (which she did). She taught me to make microforge hand-pulled electrodes, and then she left me to get on to do what I wished, which was to characterize the receptors on STG neurons.

At UCSD, I had worked with Panulirus interruptus, the Pacific spiny lobster. In Paris, lobsters were trop cher (too expensive), so I went to the local fish market at Rue Mouffetard in search of a cheaper large marine crustacean. I found Cancer pagurus, the local crab, and much to the amusement of the fishmongers, used to go to the market in search of crabs that were bien vivant for experiments. When I first brought the crabs back to the lab, I had to find the STG, only to discover that although the pyloric rhythms of crabs and lobsters were similar, the different body architectures resulted in appreciable differences in the gross morphologies of the stomach and the STGs. One of the problems I had not anticipated is that the crab STG is very flat and translucent, so optics that were adequate for Panulirus or Aplysia were less than ideal for the crab STG.

I was extremely fortunate in my time at the Ecole Normale that Danièle Paupardin-Tritsch agreed to work with me. Danièle and I conversed in a strange mélange of French and English: She spoke French to me, I tried to answer in French and then flipped into English whenever I needed to. Somehow, even early on, Danièle understood me. Danièle had just finished her PhD thesis with Gerschenfeld on serotonin actions in Aplysia (Gerschenfeld and Paupardin-Tritsch 1974a, 1974b) and wanted a change of pace, so we worked on ACh, glutamate, and GABA responses on STG neurons and muscles (Marder and Paupardin-Tritsch 1978, 1980). The work we did then set the stage for the characterization of transmitter responses that my lab did years later.

During those Parisian years, I became friends with a number of other remarkable people, including Alain Marty, Anne Feltz, and Paul Adams, all of whom were outstanding receptor and synaptic biophysicists. There were incessant discussions of science, films, and politics in the lab, and it was the first time I felt that everyone around me was smarter than I was. Alain knew a number of cheap, good restaurants, and we went to a lot of films. I loved walking the streets of Paris, despite the inevitable “draggeurs” who followed and harassed American women in the streets. I got into the habit of walking in the middle of the street to avoid the inevitable dog excrement on the sidewalks and to make sure no one could jump out of bushes to attack me when I was walking alone at midnight coming back from a movie or dinner. But Paris was magic and the 4th, 5th, and 6th Arrondissements where I mostly traveled were very beautiful.

Home Again as an Assistant Professor

When I left for my foreign postdoc, “they” (the same “they” who tell my undergraduates that two majors are better than one) told me I would never find a job in the United States while abroad. But I had two offers for good faculty positions, and I returned to the United States in the fall of 1978 to start as an assistant professor at Brandeis. In retrospect, I realized that those offers came precisely because I had followed my own instincts, thus differentiating myself from many of the other very talented people who were also on the job market that year. When I left in 1975 to move to Europe, I wasn’t sure I would ever want to return, as this was at the end of the Vietnam War, and I wasn’t proud to be American. Three years later, I had come to understand that as distasteful some features of American politics and culture were (and are today), I was at the end of the day, American.

Having lived in the 4th and 5th Arrondissments in Paris, upon my return to the United States, I immediately looked for places to live in the most urban environment I could find and afford (walking distance to films, coffee houses, and book stores). After a month of desperate looking for a rental, I ended up buying a tiny place in the heart of Harvard Square with wood floors, fire place, white walls, a minimal kitchen, and a sketchy bathroom. It had big bow windows, and a southern exposure. Given that I had no furniture, the fact that it was tiny was an asset, as after all, I was returning from microscopic Parisian apartments. I had no money and ended up with two mortgages. By today’s standards the $27,500 price tag was almost nothing, but my salary was $16,000/year, and there were months that I would have to put together quarters and pennies to buy coffee or milk. But I loved that little apartment and being three blocks from the middle of Harvard Square. I also explored the rest of Boston and wistfully looked at the beautiful buildings in the Back Bay (where we later lived for 20 years). I went to the Italian section of town (the North End) when I missed France and Italy. We still go to the Café Vittoria, which I discovered in 1978 had the best cappuccino in Boston.

It was eerie to return as a faculty member to the place I had left as an undergraduate nine years previously. In some ways, the Brandeis campus was much the same; in other ways, it was totally changed, and not for the better. I returned to the consequences of nine years of deferred maintenance. Buildings that had been new when I left in 1969 had leaking roofs and were unpainted in 1978. I had left a campus of 1,800 undergraduates and came back to one whose enrollments had been expanded to cover budget deficits. Happily, the senior faculty members who remembered me were wise enough to leave me to find my own way.

When I arrived in my new lab, it was filled with years of departmental detritus. I started at Brandeis only a few weeks after Ron Calabrese started his new lab at the Harvard Biolabs. Ron was incredibly helpful, as he shared advice about amplifiers, recordings, coffee shops, and restaurants. Also important was a friendship I early established with Kalpana White, a fly developmental geneticist, who started a year ahead of me at Brandeis. Kalpana was then (and remains so now) unusually wise, and her friendship was critical to me as I tried to maneuver through the rocky times of starting a lab.

I was hired ostensibly to teach animal physiology (something I had never taken). I wasn’t particularly worried about this: I obtained the undergraduate text that was considered the best. I bought two different medical school physiology textbooks and proceeded to read the medical school texts, and then the undergraduate text, staying a lecture or two ahead of the students. Although I had 90 students in physiology, by the end of the semester, I knew all of their names, something I can no longer do.

I set up our first rig, purchased with grants from the McKnight Foundation and the National Science Foundation (NSF). Unlike today, my set-up funds were more symbolic than actual, and it was necessary for me to get grant funding to buy my first electrophysiology set-up. Happily, I had submitted grants during my last postdoc year, and they were awarded by the time I was ready to set up my lab. Chris Lingle (today a world-class channel biophysicist at Washington University), whom I had met when I was in Oregon, joined the lab as a postdoc. Shortly thereafter, I benefited from a terrible tragedy: Fred Lang, a wonderful developmental neurobiologist working at Woods Hole, was killed by a drunk driver, leaving eight graduate students, including Judith Eisen (now an eminent developmental neurobiologist at the University of Oregon), who joined my lab. Judith was already an accomplished scientist, and within a few months, we were working together as peers, colleagues, and friends. Soon afterward, I hired Michael O’Neil as a technician (several years later he wrote our first dynamic clamp program) and Scott Hooper (professor at Ohio University and University of Cologne) joined us as my second PhD student. I remember walking around the lab one evening to discover three rigs were running simultaneously, wondering how it had all happened.

One day in August 1981, I was sitting outside at the student union eating my lunch and reading the New York Times, when a gust of wind blew away the paper, and Art Wingfield, a professor in the psychology department, rescued it and returned it to me. In a few months, Art had moved in with me in the tiny Cambridge apartment. After 20 years of living together, we got married in 2001. When we met, Art’s youngest of three children was 15, and living with his mother in England. Over the years Art’s children grew up, established interesting careers, married wonderful people, and in turn had two children each, who have developed into fascinating people. Each of Art’s kids lived with us for several months at different times in their lives, as did my two nieces. As they all lived with us when they were almost “grownup,” I had the pleasure of spending time with them without the worries of their early years.

The work that Judith Eisen and I did was the beginning of mechanistic studies of circuit neuromodulation, and presages much of today’s work in C. elegans and Drosophila. We knew from my thesis work that the PD neurons were cholinergic and suspected that the anterior burster (AB) neuron, to which the PD neurons are strongly electrically coupled, was not. Judith and I realized that the electrical coupling between the PD and AB neurons created confounds for circuit analysis, as an inhibitory postsynaptic potential (IPSP) recorded in a follower neuron, such as pyloric (PY) or lateral pyloric (LP), might come as a result of transmitter liberated from either the PD, AB neurons, or both of them. Likewise, an IPSP evoked by the LP neuron that could be recorded in both the AB and PD neurons might be direct on either or both of the neurons showing the IPSP. To disambiguate the circuit, we used Miller and Selverston’s Lucifer yellow photoinactivation technique (Miller and Selverston 1979). We showed that both the PD and AB neurons inhibited the pyloric follower neurons, but that the LP neuron inhibited the PD neurons but not the AB neuron (Eisen and Marder 1982).

With this knowledge, we wanted to ask how much of the IPSP evoked by the simultaneous depolarization of the AB and PD neurons came from each of the two presynaptic neurons. To do this, we applied picrotoxin to block the AB-evoked IPSPs. We became completely frustrated, as each time we did the experiment, we got a different answer: Sometimes the IPSP was blocked to a small extent, other times almost completely. Finally, it dawned on us that if the contribution of the two components varied under different physiological conditions, then that was exactly what should be expected!

This experience taught me an important lesson as a scientist and mentor: Often the most important new insights come from being stuck and being forced to think differently about a problem by data that at first blush seem inconsistent or unreliable. Judith realized that a neuromodulator or an input synapse that would preferentially activate or inhibit the transmitter released from the AB or PD neurons would alter the transmitter mix in the IPSP, and consequently the time course of the IPSP and the firing phase of the follower neurons (Eisen and Marder 1984). The four papers that constituted Judith’s PhD thesis were arguably the first clear mechanistic description of circuit modulation, and a clear demonstration that circuits are not hard-wired, but rather are flexible.

At the same time Judith and I were working on neuromodulation in the STG, Pete Getting, working in Tritona, was developing the idea that circuits could be reconfigured by sensory and other inputs, so that the same circuit could produce different outputs (Getting and Dekin 1985; Getting 1989). Pete and I spent hours talking, and he was an enormous intellectual support for our initial work on neuromodulation. To this day, I miss the conversations we never had the chance to have (Marder 2015b).

In 1983 Barb Beltz, then a postdoc in Ed Kravitz’s lab, published a beautiful paper on serotonin immunohistochemistry in the lobster nervous system (Beltz and Kravitz 1983). Shortly thereafter, Barb and I tried this method on the stomatogastric nervous system. One look through the microscope changed my life, as I immediately saw the bright 5-HT-stained gastropyloric receptor (GPR) neurons, the stained neuropil in the STG, and fibers and neurons in the esophageal and commissural ganglia. This taught me how much one can learn by “just seeing.” That experience has always made me value discovery science and to be uncomfortable with people who dismiss new science as “only descriptive.” Seeing something for the first time can often tell you in a glance something you would have no way of otherwise knowing or predicting.

In 1984, we published eight papers, most of them on neuromodulation, and I received tenure. Between 1984 and 1990, Art and I moved to a dramatic fifth-floor apartment in the middle of the Back Bay, we made important strides forward in understanding neuromodulation and circuit switching, and I started working with theorists. In 1990, I was promoted to professor.

Taking My Voice

Although I was by the standards of the day, assertive for a young woman, the signals from many of my peers and colleagues that I was too pushy were always there, and I must have internalized many of them. Nonetheless, I was acutely aware that I was not “heard” as well as Peter Getting and some of my other male colleagues. I marveled at how well Pete was heard and knew some of it was due to his remarkable clarity. But I also knew that our message was as fundamental and important as his was. At the time, there were few female speakers at Society for Neuroscience (SfN) and other scientific meetings. In 1985, Janis Weeks and I cochaired an SfN symposium with the two of us, Ron Calabrese, and Pete Getting, to highlight some of the best work on small circuits. When Janis and I first discussed this symposium, we thought about asking only female speakers, but decided it would have been such a strong statement that it would detract from our scientific message. Janis and I decided that two women out of four speakers was revolutionary enough but couldn’t be criticized. In 2008, when I was president of SfN, I invited four female speakers (I was just fed up enough by this point to not care what “they” might say, and there were so many wonderful women available). Many young women thanked me for doing it, and a number of older men grumbled behind my back (not daring to complain to my face), despite the fact that the speakers were all outstanding.

I didn’t realize how unconsciously influenced I was by the attitudes around me until 1987 when Mary Kennedy, who had become a good friend, invited me to give a seminar at CalTech. I gave a talk that I thought was daring and adventuresome, in which I was trying to articulate a change in conceptual framework. Afterwards, Mary came up to me and said my talk was fine, but there was no reason for me to be so “tentative.” At that moment, I realized that my internal calibration system was entirely untrustworthy, as it still reflected years of having been told I was too assertive. Learning to “take one’s voice” is something that many of us have had to do, and it demands listening well, as well as on occasion being willing to insist on being heard. It required me to be willing to be viewed as shrill or a witch, and it has forced me to be willing to interrupt men who were talking through me or ignoring me. This happens less to me today, but I suspect it still happens to younger women all the time.

Neuromodulation

I had never done any anatomy, but Kalpana was an expert light microscopist and taught me a great deal. This started a profitable time in the lab, as we routinely screened any antibody that I could beg or buy that had been raised against transmitters and neuropeptides. This quickly revealed the very large number of peptide modulators in the stomatogastric nervous system. To this day, my lab continues to combine anatomical characterization of modulator and neuronal projections with electrophysiological investigations (Beltz et al. 1984; Marder et al. 1987a; Nusbaum and Marder 1988, 1989a).

One of my favorite papers is still Scott Hooper’s major thesis paper on the effects of proctolin on the pyloric rhythm (Hooper and Marder 1987). Scott had previously shown that proctolin modulated the pyloric rhythm, but he wished to account for proctolin’s actions on the intact network in terms of its actions on individual target neurons. To that end, Scott isolated each identified neuron from its network inputs, and described proctolin’s actions (or lack thereof) on each neuron type. Scott noticed that when he isolated the AB neuron, it went faster than it did when it was left attached to its electrically coupled neighbors, the 2 PD and 1 ventricular dilator (VD) neurons. He then designed a beautiful set of experiments that argued that the non-proctolin-sensitive neurons were effectively slowing down the pacemaker AB neuron (Hooper and Marder 1987). This was initially surprising to us, but it made sense once we had seen the data and thought about it.

I learned an important lesson from working with Scott. One day he walked into my office and started explaining his data and his thoughts about it, and I realized that I was learning from him. He had complete ownership of his data, and he had obviously thought more deeply about it and understood it better than I had. At that moment, I knew he was intellectually ready to graduate. Indeed, over and over again, I have been able to mark, almost to the day, when I knew my students were ready to graduate as they came in to show me something in their data that marked their transition to an independent scientist.

Mike Nusbaum joined the lab as a postdoc at the end of 1984, and from the very beginning, Mikey’s interest was the circuitry of the descending modulatory inputs to the STG. Mikey and I spent many nights eating pizza in the lab at his desk in those halcyon days when we were allowed to have food in the lab, and he identified an important pair of modulatory proctolin neurons, the MPNs (Nusbaum and Marder 1989a, 1989b). In his own lab, at the University of Pennsylvania, Mikey has continued to work to describe the complex circuitry between the descending modulatory neurons and the STG, with a marvelous dedication to picking apart a tangle of pathways and modulator actions. To this day, we continue to collaborate on some projects.

By the end of the 1980s, we had unambiguously demonstrated that many neuromodulators influenced the STG, and each did so to reconfigure the STG in a different way (Marder et al. 1987b). At the time, we argued that this was important to provide behavioral flexibility to the animal.

A major change in the way we identified new peptide modulators in the stomatogastric nervous system benefited years later by development of new mass spectroscopy methods. Lingjun Li spent a short postdoc in the lab and has since carried out extensive identification of the neuropeptides in crustaceans. Therefore, after years of difficult purification of neuropeptides, state-of-the art chemistry has shown the presence of hundreds of neuropeptides in the stomatogastric nervous system (Christie et al. 2010; Li et al. 2003).

Switching

When Jim Weimann joined the lab as a PhD student, he wished to study the gastric rhythm of the crab, Cancer borealis. To that date, we had not seen gastric mill rhythms in the crab. After several months of work, Jim announced to me that there were no gastric mill neurons in the crab, because all of the neurons he found appeared to be firing in time with the faster pyloric network. I told him to properly identify the somata using paired intracellular recordings from the gastric mill muscles and the STG somata. By so doing, Jim discovered that many of the gastric mill neurons fire in time with the pyloric rhythm (Weimann et al. 1991; Weimann and Marder 1994). This observation became one of the first clear examples of neurons that could switch between being part of different central pattern generating circuits. This kind of switching is seen very clearly in the crab, and in the Maine lobster Homarus americanus (Bucher et al. 2006), but it is less evident in Panulirus interruptus, the Pacific Coast spiny lobster.

At the same time, Patsy Dickinson, on sabbatical from Bowdoin College, showed that red pigment concentrating hormone (RPCH) created a conjoint rhythm from neurons of disparate circuits in Panulirus interruptus (Dickinson et al. 1990). These examples led to our understanding that different modulatory conditions could dramatically alter the participation of neurons in different functional circuits.

Moving to Theory

Avis Cohen at Cornell who worked on the lamprey spinal cord CPG, insisted on introducing me to Nancy Kopell, an applied mathematician (then at Northeastern University, now at Boston University), who was working on theory of coupled oscillators. Nancy and I became friends in the late 1980s, and that friendship continues today. When I first met Nancy, she was looking to neuroscience for interesting math problems, while today Nancy is using mathematics to illuminate neuroscience problems. Nancy and I published together during the 1990s on oscillator function.

Nancy was catalytic in fostering a collaboration between me and Irv Epstein, a world expert on chemical oscillators in the Brandeis chemistry department. Ron Harris-Warrick had found that oscillations in different modulators were differentially sensitive to tetrodotoxin, and he suggested that there could be different oscillation mechanisms, some preferentially dependent on sodium channels, others on calcium channels (Harris-Warrick and Flamm 1987). Irv’s simulations showed that that it was possible to obtain similar-looking bursting behavior by very different sets of conductances (Epstein and Marder 1990). This was, for me, the first inkling of the extent to which degenerate cellular and circuit mechanisms play a role in neuronal and circuit activity.

When Jorge Golowasch joined the lab in the late 1980s, he wanted to characterize biophysically the voltage and time-dependent currents in STG neurons, with the goal of understanding how neuromodulators altered the intrinsic properties of their target neurons. Jorge determined that the peptide, proctolin, activated a voltage-dependence inward current that was blocked by extracellular Ca²⁺ (Golowasch and Marder 1992). This current is ideally tuned to activate and enhance bursting, and it is of prime importance for the action of numerous peptide modulators (Swensen and Marder 2000). Jorge also used voltage-clamp methods to measure a number of different membrane currents in the LP neuron, and then together with a postdoc in Irv Epstein’s lab, constructed a semirealistic model of the LP neuron (Buchholtz et al. 1992).

Although this model was no less successful than many of its era, I found its construction frustrating because it showed us that (a) the currents we couldn’t measure accurately were critical for the model’s performance; (b) we didn’t know whether we should use our “best” or our “mean” data to model each current; and (c) the model was fragile, and juggling one conductance required juggling others to compensate. Despite its limitations, or because of its limitations, the intellectual understandings that grew from this work shaped our work profoundly for the next 25 years. Indeed, much of the work that I did with Larry Abbott, Astrid Prinz, and others had its roots in the frustrations that I experienced in this attempt to build a biophysically realistic STG model neuron.

When I met Larry Abbott in the late 1980s he was a just minted full professor of particle physics in the Brandeis Physics Department. Like others of his generation, Larry became attracted to neural network theory, and he was working with his student Tom Kepler on memory in artificial neural networks. By happenstance, Jim Weimann and Tom Kepler were recipients of a graduate fellowship that required them to go to the same lunch for the fellowship donors. Afterward, Jim invited Tom back to the lab to show him a biological circuit in operation. Tom immediately ran over to Larry’s office to get him, and the rest is history. From then on, Larry set about to educate himself about neuroscience, and in so doing, taught me how to educate physicists interested in moving into neuroscience.

When Larry asked me what he should read, I handed him Kandel, Schwartz, and Jessell. Larry started at the beginning and dropped into my office almost every day with questions. After several months, he stated happily that he “was starting to see the same words over again,” which gave him comfort because he was afraid that there were an infinite number of words he had to learn. Although he made a joke of this, it showed me that the biggest barrier that a physicist had to learning neuroscience was that the knowledge in neuroscience is not derivable. Instead, it requires learning a lot of cellular mechanisms with strange names or parts of the brain with even stranger names, before it is possible to understand the literature and think creatively.

Larry, like many physicists transitioning into neuroscience, found the fact that the pyloric rhythm maintained constant phase over a substantial frequency range fascinating (Abbott et al. 1991). I was equally curious to understand the way that the PD neurons influenced the frequency of the AB neuron (Kepler et al. 1990). The LP neuron model that Jorge Golowasch and Frank Buchholtz were working on posed a very difficult question. Although each biological neuron was successful at finding a balanced set of conductances that gave rise to a reliable and characteristic set of intrinsic properties, it was shockingly difficult to tune a conductance-based model to replicate the biological neuron’s behavior. This told me that we must have been missing an important principle about how electrical excitability is controlled. For the better part of a year, I badgered Larry to think about this problem. For months he said it was “too hard.” Then, one day Larry came in and said he thought he had a simple solution, and it was this solution that gave rise to the notion that neurons and networks could self-tune to a desired activity state.

Homeostasis

In 1992, there was a rich tradition of ion channel biophysics. But, any self-respecting biophysicist would wish to study a single kind of channel, or voltage-gated current, in isolation, uncontaminated by all of the other conductances in the neuron. So there were experts on Na⁺, K⁺, and Ca²⁺ currents, but different labs usually studied these currents. Likewise, others were working on the molecular regulation of these currents. Again, it was characteristically different people working on the regulation of different currents.

In contrast, Larry realized that if the neuron used a simple negative-feedback, activity-dependent control of its activity to regulate all of its conductances, then the control problem no longer required that the neuron measure and match the expression of each of its conductances in the way that all of us who were fine-tuning models found so difficult. The first of these self-tuning homeostatic models was published in 1993 (LeMasson et al. 1993), followed by Gina Turrigiano’s papers that provided experimental support for the idea of activity-dependent tuning of conductance densities (Turrigiano et al. 1994; Turrigiano et al. 1995). Of course, homeostatic negative feedback mechanisms are core to the regulation of many physiological processes. What was novel with these models is that they applied a well-understood principle in the context of many physiological processes to the control of all of the conductances in a neuron, rather than assuming that each type of channel was independently regulated.

In the first generation of the homoestatic models, intracellular Ca²⁺ concentrations were used to create a global target of the neuron’s activity, and then to guide changes in conductance densities. This was followed by a second-generation model (Liu et al. 1998) that used three Ca²⁺ sensors. More recently, a third generation of more biologically plausible integral control models was implemented in which the rate of change of each conductance is regulated separately (O’Leary et al. 2013; O’Leary et al. 2014; O’Leary and Marder 2016). Using simple rules, these models find sets of “neurons” that capture much of what is present in the biological data.

When Gina Turrigiano moved to her own lab, she rapidly switched to studying rat neurons in culture, and very shortly thereafter, she and Sacha Nelson published their landmark paper on synaptic scaling (Turrigiano et al. 1998). Because synaptic scaling provided a counterpoint to long-term potentiation and Hebbian plasticity, almost immediately its importance was recognized. Today, homeostasis of intrinsic excitability and activity-dependent scaling of synaptic strength have become central to our understanding of circuit development and function.

Dynamic Clamp

One of the first projects that Larry Abbott and I envisioned was to create circuits of defined connectivity by coupling cultured neurons in varying configurations that would allow us to create artificial electrical and chemical synaptic connections but give us control of the strength of these connections. My first idea was to use the membrane potential of one neuron to control the current through an iontophoretic electrode-delivering transmitter to a postsynaptic neuron. Larry immediately realized that a simple electronic circuit could provide the electrical simulation of a gap junction. Together with Andy Sharp and Michael O’Neil, we started to build these circuits (Sharp et al. 1992). Helped by an early conversation with John Rinzel during a summer course at Woods Hole, these efforts turned into the concept of a fully programmable dynamic clamp.

The dynamic clamp creates an artificial conductance, either a voltage-dependent conductance or an artificial chemical synapse (Sharp et al. 1993a, 1993b), using intracellular recordings and equations that model the applied conductance. This allows the investigator to do simulations using biological neurons. Our initial dynamic clamp program was extremely difficult to implement because of the limitations of the hardware at the time. The code was written in machine language by Michael O’Neil, because computers and boards were so slow by today’s standards. A less general, but faster system was developed by Hugh Robinson (Robinson and Kawai 1993) to study Na⁺ currents. Over the years, a large number of different dynamic clamp systems have been developed by investigators around the world (Butera et al. 2001; Prinz et al. 2004a), and we have used a number of different dynamic clamp programs to study the dynamics of small circuits or the actions of single voltage-dependent currents (Sharp et al. 1996; Turrigiano et al. 1996; Bartos et al. 1999; Grashow et al. 2009, 2010; Goaillard et al. 2010). Today, the dynamic clamp is routinely implemented and used by many investigators wishing to investigate the sensitivity of neuronal excitability to a particular conductance.

Multiple Solutions

In the late 1990s, Mark Goldman, then one of Larry Abbott’s students and now a world-renowned professor at the University of California, Davis, wished to ask how many different sets of conductances could give rise to similar behavior. Therefore, he constructed a population of about 5,000 model neurons, each with five voltage-dependent conductances and a leak (Goldman et al. 2001). Mark found that similar electrical behavior could result from different sets of conductance densities, and that in some cases, even small changes in conductance densities produced quite disparate intrinsic properties (Goldman et al. 2001; Golowasch et al. 2002). Measurements of K⁺ currents in identified neurons were consistent with a range of conductance densities (Golowasch et al. 1999; Goldman et al. 2001). This work showed that the value of no single conductance was sufficient to predict the neuron’s activity (Goldman et al. 2001) but that predicting the neuron’s output required knowing the correlated values of three different conductances. This work also provided a lovely example of what we called “failure of averaging” (Golowasch et al. 2002), which can occur when averages of a population fail to represent the behavior of all of the individuals that contributed to that average.

Following on Goldman’s lead, postdoc Astrid Prinz (now at Emory University) wished to find models of the pyloric rhythm. She first created a database of 1.7 million model neurons, each with eight conductances (Prinz et al. 2003), and then used some of these neurons to create a database of more than 20 million circuits, built with the architecture of the pyloric rhythm (Prinz et al. 2004b). This paper gave examples of virtually identical circuit outputs that resulted from disparate sets of underlying conductance densities (Prinz et al. 2004b). This result was an example of a computational study that completely changed the way in which we subsequently designed, implemented, and analyzed experiments. The lessons we took from this work were as follows: (a) much of the variability in measurements we saw across animals is likely biological, and not merely a result of experimental error; (b) it is important to obtain as many measurements as possible on each individual, and to look for correlations across parameters; and (c) if each animal is an individual solution, within a range of parameters, they would be differentially sensitive to perturbations.

In a more recent study, Gabrielle Gutierrez and Tim O’Leary studied five-cell networks of coupled oscillators. They showed that changes in network performance that look identical at the network level can result from changes in three different synapses (Gutierrez et al. 2013). This work shows that degenerate solutions to circuit performance arise easily from parallel pathways resulting from electrical coupling. The implications of this work are obvious: Without a connectome that reveals where parallel pathways in circuits are likely to be found, pharmacological or optogenetic approaches may lead to incomplete or misleading results, by finding only one of several circuit mechanisms that could be responsible for a change in circuit output.

Animal-to-Animal Variability

In response to Astrid’s 2004 paper, we set out to determine how much variability is biologically present across individuals in the parameters that determine intrinsic excitability and synaptic strength. We did this by combining single-cell polymerase chain reaction measurements of the mRNA copy numbers for single ion channel genes with voltage-clamp measurements of synaptic strengths and voltage-dependent conductances (Schulz et al. 2006, 2007; Goaillard et al. 2009; Tobin et al. 2009). These studies showed an approximately two- to sixfold variability in the same parameter in the same identified neuron across animals, and also revealed interesting sets of correlations in the expression of ion channel genes and conductances (Schulz et al. 2006, 2007; Goaillard et al. 2009; Tobin et al. 2009). This highlights the importance of plotting all of the data points in a study, and not only reporting means and standard errors. We were very encouraged that similar data were soon forthcoming from Ron Calabrese’s work on leech (Roffman et al. 2012) and can be seen in studies of vertebrate systems (Swensen and Bean 2005; Sobie 2009).

As a follow-up to these initial experiments, Rachel Grashow used the dynamic clamp to make artificial networks by coupling single neurons of various cell types to the same oscillator model (Grashow et al. 2010). These experiments provided direct evidence for compensation of one set of variable properties with another variable process.

Interestingly, not only are the intrinsic and synaptic currents in the pyloric cells and circuit variable, but neurons of the same cell type are also morphologically variable (Bucher et al. 2007; Otopalik et al. 2017a), but this may not be important for the operation of the STG because the neurons are electronically compact (Otopalik et al. 2017b).

Animal-to-animal variability arises automatically in Tim O’Leary’s integral control models as they self-assemble (O’Leary et al. 2014). Taken at face value, we have learned that many solutions produce similar behavior, but these nonetheless represent a small fraction of solutions that would arise with randomly varying parameters. My personal take on all of these data is that the molecular machinery of real neurons can achieve a two to six range of many parameters (synaptic strengths, channel number) in the same identified neurons across the population, but these neurons would be hard-pressed to achieve a 5 percent precision of those same parameters. Likewise, maintaining a target activity profile means restricting values to a certain part of parameter space, and this is the space that biology has found.

Perturbations

If each individual animal or person has a different set of underlying parameters, then there should be a range of perturbations that all healthy individuals can deal with or withstand. But if a perturbation is more extreme, one might expect that some individuals would be more successful than others (Marder et al. 2015). To test the predictions of these premises, we have been studying the effects of temperature on the STG motor patterns (Tang et al. 2010; Tang et al. 2012 Rinberg et al. 2013; Caplan et al. 2014; Soofi et al. 2014; O’Leary and Marder 2016). Modest changes in temperature produce robust and reliable responses across preparations. But as the temperature is increased to extreme levels, close to or outside of the range that the animals would routinely encounter in their natural habitats, preparations crash (i.e., they lose their characteristic functional outputs). Each animal crashes with unique and diverse sets of dynamics, as expected if each individual starts with a different set of intrinsic and synaptic properties. This work is instructive for thinking about how individual humans respond differentially to stresses of all kinds. More recently, we have started to study other global perturbations, including changes in pH and K⁺ concentrations, to determine whether individual animals differ in their robustness to several perturbations.

Time Sharing and Interruptions

My office has always adjoined my lab, and my door is open except in the unusual case that someone wants to talk confidentially. In my last office, I could hear many of the conversations that took place as people worked. My present office is further from the dissection bays so I hear fewer routine conversations unless I wander down to the back of the lab. I worked at the bench myself until after I was a full professor, and of course during those years, I knew a lot more about the status of the freezers and daily lab dramas than I do today.

Because my office door is always open, there are days and weeks that I am interrupted almost continuously during normal work hours. I unconsciously developed strategies to deal with these interruptions. I have always been good at switching back and forth between tasks. I learned that if I leave documents open where I was working, that the page cues me back into the mind-set of where I was. I routinely work between 5 P.M. and 8 P.M., when the day has quieted down, and I am less distracted. Of course, clever members of my lab have also figured out that if they wish my undivided attention, those are good hours. I often work Sunday afternoons, and again this allows me quieter times.

More than 20 years ago, after one particularly disrupted day when I was trying desperately to get a manuscript or a grant finished, I realized that many of my colleagues restrict their availability and time much more than I do, and this perhaps translated into greater productivity. I decided then that I couldn’t give up being who I was, even if it meant I wouldn’t rise to the top of our profession because I might publish one or two fewer papers each year. In retrospect, who knows whether I might have published more papers had I not allowed these interruptions, but I also know it would have made me a much unhappier person to close my door. And, I have received more than my fair due of honors and accolades.

The Larger Scene

I have spent and continue to spend considerable time and energy working on the national and international level. I was first asked to serve on a study section when I was still an assistant professor, as there were so few women that we were roped in when we were still young and inexperienced. Since that first study section, I have served on a series of study sections or review panels for the National Institutes of Health (NIH) and NSF. I was on the Board of Scientific Counselors for the National Institute of Neurological Disorders and Stroke (NINDS) Intramural Program, I served on the NINDS Council, the Working Group for the Brain Initiative, and now serve on the Brain Advisory Council. I also serve on the Council of the National Academy of Sciences, as well as on scientific advisory boards for various institutions around the world.

At the onset of my career, there were immediate positive dividends from national engagement. It was interesting, and I met investigators from other institutions, who were working on a variety of problems. Of course, the negatives were that all of these activities took me away from my own work. On balance, for many years, I was able to balance effectively my engagements off-campus with my work on-campus. I read and write quickly (or at least do so when I am pushed by deadlines), so some tasks that are time-consuming for some people are less so for me. That said, as I have gotten older, I find traveling increasingly unpleasant. This is partly because traveling has become vastly more unpleasant and because I have a learned aversion to airplanes.

So why do I continue to say yes to as many of these activities? Especially to those that require riding on airplanes? If I am honest, I think I continue to serve because I feel an obligation to be an advocate for small laboratories, for people working on unconventional species, for women, for young people, and for people working at nonelite institutions. A very strong part of me is concerned by the concentration of power and resources in the hands of few. As science increasingly demands expensive technologies, this has become a major problem. I believe deeply that the strength of American science has always been its distributed and random nature: Someone in Wyoming, Oklahoma, or Puerto Rico can do wonderful experiments that could change the way we think about some important biological process. I worry that unless strong voices remind us that we have to treasure our scientific diversity and innovation across the myriad institutions that make up American science, we risk the foundational premises on which American science rests. I don’t enjoy having to remind my colleagues that they should think before knee-jerking to award favors to our most elite institutions, no matter how deserving their scientists, but I continue doing so. The positional information of where we work is as important in the progress of science as it is in the development of an organism.

I was editor in chief of the Journal of Neurophysiology from 2002 to 2008. I changed the gender balance of the editorial board, but I tried to maintain the journal’s position as an excellent venue for the publication of substantial and thorough reports of systems and cellular neuroscience. At the Journal of Neurophysiology, I prided myself in trying to ensure that reviews were fair and that papers were improved by the review process.

I joined the editorial board of eLife as a senior editor at its inception, and now I am one of its deputy editors. eLife takes a good deal of my time, and my husband periodically urges that I quit eLife as its duties follow me daily and around the world. I was attracted to eLife because I hoped we would publish important and outstanding science while allowing manuscripts to retain the personality and flavor that their authors wished. Unlike many of the most prestigious journals, eLife has no length or word limitations, and instead employs many features that allow authors to present complete stories, with appropriate controls in the body of the paper. Importantly, eLife uses a consultative review process that is designed to remove conflicting reviews before an author has to try to make sense of inconsistent or inaccurate reviews. And, importantly, eLife tries to avoid reviewers and authors “upping the ante” on authors by asking for more and more experiments.

eLife has become a very well-respected journal and has published many important papers in all areas of biology. I always felt that my support for eLife was one way to make our postdocs believe that excellence could triumph over the stranglehold represented by the most elite journals. In some ways, eLife’s commitment to excellence, and therefore its selectivity, is both its strength and its weakness, as we also make decisions partially on the basis of our assessments of novelty and significance. But, on balance, I continue to believe in eLife’s mission to improve the transparency and immediacy of scientific publication. Nonetheless, eLife does not function in a vacuum, and our authors, reviewers, and editors are influenced strongly by today’s culture of scientific publication. I keep trying to remind our editors and reviewers that our job is to publish the science that our authors have done and that our job is not to create arbitrary hurdles and publication delays. It is a real editorial challenge to strive for rigor and innovation without letting reviewers and editors destroy author autonomy. Interestingly, the most common complaint that reviewers and editors make about the papers we review is that the authors are trying to “oversell” the novelty and significance of their work. Thus, we all recognize the deleterious consequence for our science of the dominance of elite publications, but most of us have learned to sell and oversell our work.

I have served the SfN (and other scientific societies as well) in many capacities, including on the Program Committee, Publication Committee, Committee on Committees, and Council. In 2007—2008, I was SfN president. Because the SfN staff is so professional and expert, my time as SfN president was considerably less onerous than I had feared, and it was an interesting challenge to help steer SfN in ways that helped the international community of neuroscientists. I found it fascinating to watch an organization that needs to remain flexible enough to respond to changes in our world and stable enough to resist whims of an ever-changing leadership. In some ways, SfN as an organization parallels the adult nervous system: It must be both plastic and robust, and this is a never-ending challenge both for the permanent staff and its scientific leadership.

Over the years, I have written and published many scientific review articles, some of which have been influential (Harris-Warrick and Marder 1991; Marder and Calabrese 1996; Marder and Goaillard 2006; Marder and Bucher 2007; Marder 2012). One of the reasons I continue to write and publish reviews is because I am fully aware that the idiosyncrasies of the stomatogastric nervous system make it difficult for an outsider to find the important take-home messages embedded in the literature on this preparation. I am also aware that many experimentalists find the theory literature difficult, so sometimes reviews that capture messages from theory are helpful (Marder and Taylor 2011; Marder et al. 2014; Marder et al. 2017). This is also why I continue to ride on airplanes more than I would like, as I know that the messages of our work are more readily accessible when the logic of many papers is presented in a 50-minute talk than it ever could be in the individual papers.

Over the past 20 years I have published about 20 short opinion pieces, first in Current Biology and more recently in eLife. These pieces are usually born in frustration with aspects of our scientific and educational lives and enterprises (Marder 2000, 2015a). Some of these papers are funny in places, but they all are part of my attempt to remind myself and others of what is important in how we live our lives as scientists and educators. We all struggle to stay on a path that leads to the discovery of new knowledge and the nurturing of our trainees. But there are many dangers on those paths, and I struggle with them daily.

2018

Art and I now live on the Boston waterfront, just outside of the North End and its Italian restaurants and markets. We see glorious sunsets and watch the endless varieties of boats, large and small. In the summer, I swim in an open-air public pool, right on the water’s edge two blocks from our apartment. In the winter, the cold winds blow off the harbor. We sometimes take the water taxi from our building to the airport, but usually I opt for the seven-minute drive through the tunnel from our home to the airport terminal.

This past semester I once again taught Principles of Neuroscience to 80 students. I still love the first half of this course because it starts with the fundamental principles of cellular neuroscience, and I know that most of what I cover in that part of the course will remain “true” in 10 or 20 years. I don’t enjoy the second half of the course as much because it deals with problems and processes that still feel fundamentally unexplained. I feel less comfortable with trying to explain the mechanisms underlying higher cognitive processes. That said, I enjoy watching the light go on in students’ eyes as they understand a new concept. I have the sense that while my students are as smart as ever, they learn differently. I still teach on the black board with colored chalk, and still require students to write answers in their own words on exams. I know that our students are better at doing oral presentations than they were in the past, but they seem less adept at extracting the logic of a scientific argument from the literature.

I still have an open door in the laboratory, and 95 percent of the time, I stop what I am doing when someone puts their head in my door, whether they are colleagues, random undergraduates, or one of my lab members.

I have stayed at Brandeis University for 40 years. I am now the fourth oldest of the full-time faculty in my department. All of us were hired as beginning assistant professors, and we have matured in place. Among the 30 or so active research faculty in the biology and biochemistry departments, five are members of the National Academy (Jim Haber, Chris Miller, Michael Rosbash, Gina Turrigiano, and myself) and have been here since starting their labs. Michael Rosbash and Jeff Hall (who went emeritus several years back) were just awarded the Nobel Prize, and a number of us have received other prestigious international awards. Other eminent senior faculty (Jeff Gelles, Dan Oprian, Doro Kern, Liz Hedstrom, Leslie Griffith, Sue Lovett, Sacha Nelson, Bruce Goode, and Piali Sengupta) also have been here since they started as assistant professors.

Until recently, people would invite me to apply for positions as deans, provosts, chairs, and institute directors at various institutions. During the past year or two, those invitations have largely stopped, which is fine because I never applied for a job at another institution. Instead, in the last year or so, people have started asking me if I have retirement plans. I do not. I was lucky enough to get an NINDS R35 award that will provide me with good grant funding for another seven years, as long as we continue to be productive. Thus far, I am still attracting excellent postdoc and graduate students, and I have a list of 15 or so manuscripts that are 50–80 percent completed, so there is much work to be done. I have stayed at Brandeis largely because of my colleagues. They are wicked smart, compassionate, have great senses of humor, and share the belief that the creation of new knowledge is one of the most important of human endeavors.

What has changed in me is that I have far less patience, or for that matter interest, in university politics and procedures, and in other national and international activities. I have grown to abhor memos, and I really don’t care the way I used to about the requirements for our degrees, or how other institutions govern themselves. Although it is important to sometimes offer advice to colleagues at other institutions about their graduate programs, it just isn’t as interesting as it might have been 25 years ago. Likewise, individual students are as compelling as always, but decisions about the formal mechanisms we use to evaluate and educate them seem increasingly pointless, as I have decided that some of them will become real scientists regardless of what we do, and others will not, regardless of what we do. We aren’t good at predicting which ones will do great work and which will become discouraged. Sometimes, the right conversation is more important than all our programmatic activities. Thus, my door remains open.

When I walk back to the rig rooms and watch recordings of the rhythms of our preparations, I find myself in the same state of wonder that I first felt as a beginning graduate student. Peeking into the mysteries of life never gets old.

References

Abbott, L.F., Hooper, S.L., and Marder, E. (1991). Oscillating networks: Control of burst duration by electrically coupled neurons. Neural Comp 3, 487–497.

Ascher, P. (1972). Inhibitory and excitatory effects of dopamine on Aplysia neurones. J Physiol 225, 173–209.

Barker, D.L., Molinoff, P.B., and Kravitz, E.A. (1972). Octopamine in the lobster nervous system. Nature New Biol 236, 61–62.

Bartos, M., Manor, Y., Nadim, F., Marder, E., and Nusbaum, M.P. (1999). Coordination of fast and slow rhythmic neuronal circuits. J Neurosci 19, 6650–6660.

Beltz, B., Eisen, J.S., Flamm, R., Harris-Warrick, R.M., Hooper, S.L., and Marder, E. (1984). Serotonergic innervation and modulation of the stomatogastric ganglion of three decapod crustaceans (Panulirus interruptus, Homarus americanus and Cancer irroratus). J Exp Biol 109, 35–54.

Beltz, B.S., and Kravitz, E.A. (1983). Mapping of serotonin-like immunoreactivity in the lobster nervous system. J Neurosci 3, 585–602.

Bucher, D., Johnson, C.D., and Marder, E. (2007). Neuronal morphology and neuropil structure in the stomatogastric ganglion of the lobster, Homarus americanus. J Comp Neurol 501, 185–205.

Bucher, D., Taylor, A.L., and Marder, E. (2006). Central pattern generating neurons simultaneously express fast and slow rhythmic activities in the stomatogastric ganglion. J Neurophysiol 95, 3617–3632.

Buchholtz, F., Golowasch, J., Epstein, I.R., and Marder, E. (1992). Mathematical model of an identified stomatogastric ganglion neuron. J Neurophysiol 67, 332–340.

Butera, R.J., Wilson, C.G., DelNegro, C.A., and Smith, J.C. (2001). A methodology for achieving high-speed rates for artificial conductance injection in electrically excitable biological cells. IEEE Trans Biomed Eng 48, 1460–1470.

Caplan, J.S., Williams, A.H., and Marder, E. (2014). Many parameter sets in a multicompartment model oscillator are robust to temperature perturbations. J Neurosci 34, 4963–4975.

Christie, A.E., Stemmler, E.A., and Dickinson, P.S. (2010). Crustacean neuropeptides. Cell Mol Life Sci 67, 4135–4169.

Dickinson, P.S., Mecsas, C., and Marder, E. (1990). Neuropeptide fusion of two motor pattern generator circuits. Nature 344, 155–158.

Eisen, J.S., and Marder, E. (1982). Mechanisms underlying pattern generation in lobster stomatogastric ganglion as determined by selective inactivation of identified neurons. III. Synaptic connections of electrically coupled pyloric neurons. J Neurophysiol 48, 1392–1415.

Eisen, J.S., and Marder, E. (1984). A mechanism for production of phase shifts in a pattern generator. J Neurophysiol 51, 1375–1393.

Epstein, I.R., and Marder, E. (1990). Multiple modes of a conditional neural oscillator. Biol Cybern 63, 25–34.

Gerschenfeld, H.M. (1973). Chemical transmission in invertebrate central nervous systems and neuromuscular junctions. Physiol Rev 53, 1–119.

Gerschenfeld, H.M., and Paupardin-Tritsch, D. (1974a). Ionic mechanisms and receptor properties underlying the responses of molluscan neurones to 5-hydroxytryptamine. J Physiol 243, 427–456.

Gerschenfeld, H.M., and Paupardin-Tritsch, D. (1974b). On the transmitter function of 5-hydroxytryptamine at excitatory and inhibitory monosynaptic junctions. J Physiol 243, 457–481.

Getting, P.A. (1989). Emerging principles governing the operation of neural networks. Annu Rev Neurosci 12, 185–204.

Getting, P.A., and Dekin, M.S. (1985). Mechanisms of pattern generation underlying swimming in Tritonia. IV. Gating of central pattern generator. J Neurophysiol 53, 466–480.

Giller, E., Jr., and Schwartz, J.H. (1971). Choline acetyltransferase in identified neurons of abdominal ganglion of Aplysia californica. J Neurophysiol 34, 93–107.

Goaillard, J.M., Taylor, A.L., Pulver, S.R., and Marder, E. (2010). Slow and persistent postinhibitory rebound acts as an intrinsic short-term memory mechanism. J Neurosci 30, 4687–4692.

Goaillard, J.M., Taylor, A.L., Schulz, D.J., and Marder, E. (2009). Functional consequences of animal-to-animal variation in circuit parameters. Nat Neurosci 12, 1424–1430.

Goldman, M.S., Golowasch, J., Marder, E., and Abbott, L.F. (2001). Global structure, robustness, and modulation of neuronal models. J Neurosci 21, 5229–5238.

Golowasch, J., Abbott, L.F., and Marder, E. (1999). Activity-dependent regulation of potassium currents in an identified neuron of the stomatogastric ganglion of the crab Cancer borealis. J Neurosci 19, RC33.

Golowasch, J., Goldman, M.S., Abbott, L.F., and Marder, E. (2002). Failure of averaging in the construction of a conductance-based neuron model. J Neurophysiol 87, 1129–1131.

Golowasch, J., and Marder, E. (1992). Proctolin activates an inward current whose voltage dependence is modified by extracellular Ca²⁺. J Neurosci 12, 810–817.

Grashow, R., Brookings, T., and Marder, E. (2009). Reliable neuromodulation from circuits with variable underlying structure. Proc Natl Acad Sci USA 106, 11742–11746.

Grashow, R., Brookings, T., and Marder, E. (2010). Compensation for variable intrinsic neuronal excitability by circuit-synaptic interactions. J Neurosci 30, 9145–9156.

Gutierrez, G.J., O’Leary, T., and Marder, E. (2013). Multiple mechanisms switch an electrically coupled, synaptically inhibited neuron between competing rhythmic oscillators. Neuron 77, 845–858.

Harris-Warrick, R.M., and Flamm, R.E. (1987). Multiple mechanisms of bursting in a conditional bursting neuron. J Neurosci 7, 2113–2128.

Harris-Warrick, R.M., and Marder, E. (1991). Modulation of neural networks for behavior. Annu Rev Neurosci 14, 39–57.

Hooper, S.L., and Marder, E. (1987). Modulation of the lobster pyloric rhythm by the peptide proctolin. J Neurosci 7, 2097–2112.

Kehoe, J. (1972a). Ionic mechanisms of a two-component cholinergic inhibition in Aplysia neurones. J Physiol (Lond) 225, 85–114.

Kehoe, J. (1972b). The physiological role of three acetylcholine receptors in synaptic transmission in Aplysia. J Physiol (Lond) 225, 147–172.

Kehoe, J. (1972c). Three acetylcholine receptors in Aplysia neurones. J Physiol (Lond) 225, 115–146.

Kepler, T.B., Marder, E., and Abbott, L.F. (1990). The effect of electrical coupling on the frequency of model neuronal oscillators. Science 248, 83–85.

LeMasson, G., Marder, E., and Abbott, L.F. (1993). Activity-dependent regulation of conductances in model neurons. Science 259, 1915–1917.

Li, L., Kelley, W.P., Billimoria, C.P., Christie, A.E., Pulver, S.R., Sweedler, J.V., and Marder, E. (2003). Mass spectrometric investigation of the neuropeptide complement and release in the pericardial organs of the crab, Cancer borealis. J Neurochem 87, 642–656.

Liu, Z., Golowasch, J., Marder, E., and Abbott, L.F. (1998). A model neuron with -activity-dependent conductances regulated by multiple calcium sensors. J Neurosci 18, 2309–2320.

Marder, E. (1974). Acetylcholine as an excitatory neuromuscular transmitter in the stomatogastric system of the lobster. Nature 251, 730–731.

Marder, E. (1976). Cholinergic motor neurones in the stomatogastric system of the lobster. J Physiol 257, 63–86.

Marder, E. (2000). Bitter and twisted. Curr Biol 10, R1.

Marder, E. (2012). Neuromodulation of neuronal circuits: Back to the future. Neuron 76, 1–11.

Marder, E. (2015a). Bars and medals. eLife 4, e05787.

Marder, E. (2015b). Lost voices. eLife 4, e06536.

Marder, E., and Bucher, D. (2007). Understanding circuit dynamics using the stomatogastric nervous system of lobsters and crabs. Annu Rev Physiol 69, 291–316.

Marder, E., and Calabrese, R.L. (1996). Principles of rhythmic motor pattern generation. Physiol Rev 76, 687–717.

Marder, E., Calabrese, R.L., Nusbaum, M.P., and Trimmer, B. (1987a). Distribution and partial characterization of FMRFamide-like peptides in the stomatogastric nervous systems of the rock crab, Cancer borealis, and the spiny lobster, Panulirus interruptus. J Comp Neurol 259, 150–163.

Marder, E., and Goaillard, J.M. (2006). Variability, compensation and homeostasis in neuron and network function. Nat Rev Neurosci 7, 563–574.

Marder, E., Gutierrez, G.J., and Nusbaum, M.P. (2017). Complicating connectomes: Electrical coupling creates parallel pathways and degenerate circuit mechanisms. Dev Neurobiol 77, 597–609.

Marder, E., Haddad, S.A., Goeritz, M.L., Rosenbaum, P., and Kispersky, T. (2015). How can motor systems retain performance over a wide temperature range? Lessons from the crustacean stomatogastric nervous system. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 201, 851–856.

Marder, E., Hooper, S.L., and Eisen, J.S. (1987b). Multiple neurotransmitters provide a mechanism for the production of multiple outputs from a single neuronal circuit. In Synaptic Function, G.M. Edelman, W.E. Gall, and M.W. Cowan, eds. (John Wiley & Sons), pp. 305–327.

Marder, E., O’Leary, T., and Shruti, S. (2014). Neuromodulation of circuits with variable parameters: Single neurons and small circuits reveal principles of state-dependent and robust neuromodulation. Annu Rev Neurosci 37, 329–346.

Marder, E., and Paupardin-Tritsch, D. (1978). The pharmacological properties of some crustacean neuronal acetylcholine, gamma-aminobutyric acid, and L-glutamate responses. J Physiol 280, 213–236.

Marder, E., and Paupardin-Tritsch, D. (1980). The pharmacological profile of the acetylcholine response of a crustacean muscle. J Exp Biol 88, 147–159.

Marder, E., and Taylor, A.L. (2011). Multiple models to capture the variability in biological neurons and networks. Nat Neurosci 14, 133–138.

McCaman, M.W., Ono, J.K., and McCaman, R.E. (1984). 5-hydroxytryptamine measurements in molluscan ganglia and neurons using a modified radioenzymatic assay. J Neurochem 43, 91–99.

McCaman, R.E., and Dewhurst, S.A. (1970). Choline acetyltransferase in individual neurons of Aplysia californica. J Neurochem 17, 1421–1426.

Miller, J.P., and Selverston, A. (1979). Rapid killing of single neurons by irradiation of intracellularly injected dye. Science 206, 702–704.

Nusbaum, M.P., and Marder, E. (1988). A neuronal role for a crustacean red pigment concentrating hormone-like peptide: Neuromodulation of the pyloric rhythm in the crab, Cancer borealis. J Exp Biol 135, 165–181.

Nusbaum, M.P., and Marder, E. (1989a). A modulatory proctolin-containing neuron (MPN). I. Identification and characterization. J Neurosci 9, 1591–1599.

Nusbaum, M.P., and Marder, E. (1989b). A modulatory proctolin-containing neuron (MPN). II. State-dependent modulation of rhythmic motor activity. J Neurosci 9, 1600–1607.

O’Leary, T., and Marder, E. (2016). Temperature-robust neural function from activity-dependent ion channel regulation. Curr Biol 26, 2935–2941.

O’Leary, T., Williams, A.H., Caplan, J.S., and Marder, E. (2013). Correlations in ion channel expression emerge from homeostatic tuning rules. Proc Natl Acad Sci USA 110, E2645–2654.

O’Leary, T., Williams, A.H., Franci, A., and Marder, E. (2014). Cell types, network homeostasis, and pathological compensation from a biologically plausible ion channel expression model. Neuron 82, 809–821.

Otopalik, A.G., Goeritz, M.L., Sutton, A.C., Brookings, T., Guerini, C., and Marder, E. (2017a). Sloppy morphological tuning in identified neurons of the crustacean stomatogastric ganglion. eLife 6, DOI: 10.7554/eLife.22352.

Otopalik, A.G., Sutton, A.C., Banghart, M., and Marder, E. (2017b). When complex neuronal structures may not matter. eLife 6, DOI: 10.7554/eLife.23508.

Otsuka, M., Kravitz, E.A., and Potter, D.D. (1967). Physiological and chemical architecture of a lobster ganglion with particular reference to GABA and glutamate. J Neurophysiol 30, 725–752.

Prinz, A.A., Abbott, L.F., and Marder, E. (2004a). The dynamic clamp comes of age. Trends Neurosci 27, 218–224.

Prinz, A.A., Billimoria, C.P., and Marder, E. (2003). Alternative to hand-tuning conductance-based models: Construction and analysis of databases of model neurons. J Neurophysiol 90, 3998–4015.

Prinz, A.A., Bucher, D., and Marder, E. (2004b). Similar network activity from disparate circuit parameters. Nat Neurosci 7, 1345–1352.

Rinberg, A., Taylor, A.L., and Marder, E. (2013). The effects of temperature on the stability of a neuronal oscillator. PLoS Comput Biol 9, e1002857.

Robinson, H.P., and Kawai, N. (1993). Injection of digitally synthesized synaptic conductance transients to measure the integrative properties of neurons. J Neurosci Methods 49, 157–165.

Roffman, R.C., Norris, B.J., and Calabrese, R.L. (2012). Animal-to-animal variability of connection strength in the leech heartbeat central pattern generator. J Neurophysiol 107, 1681–1693.

Schulz, D.J., Goaillard, J.M., and Marder, E. (2006). Variable channel expression in identified single and electrically coupled neurons in different animals. Nat Neurosci 9, 356–362.

Schulz, D.J., Goaillard, J.M., and Marder, E.E. (2007). Quantitative expression profiling of identified neurons reveals cell-specific constraints on highly variable levels of gene expression. Proc Natl Acad Sci USA 104, 13187–13191.

Sharp, A.A., Abbott, L.F., and Marder, E. (1992). Artificial electrical synapses in oscillatory networks. J Neurophysiol 67, 1691–1694.

Sharp, A.A., O’Neil, M.B., Abbott, L.F., and Marder, E. (1993a). The dynamic clamp: Artificial conductances in biological neurons. Trends Neurosci 16, 389–394.

Sharp, A.A., O’Neil, M.B., Abbott, L.F., and Marder, E. (1993b). Dynamic clamp: Computer-generated conductances in real neurons. J Neurophysiol 69, 992–995.

Sharp, A.A., Skinner, F.K., and Marder, E. (1996). Mechanisms of oscillation in dynamic clamp constructed two-cell half-center circuits. J Neurophysiol 76, 867–883.

Sobie, E.A. (2009). Parameter sensitivity analysis in electrophysiological models using multivariable regression. Biophys J 96, 1264–1274.

Soofi, W., Goeritz, M.L., Kispersky, T.J., Prinz, A.A., Marder, E., and Stein, W. (2014). Phase maintenance in a rhythmic motor pattern during temperature changes in vivo. J Neurophysiol 111, 2603–2613.

Swensen, A.M., and Bean, B.P. (2005). Robustness of burst firing in dissociated purkinje neurons with acute or long-term reductions in sodium conductance. J Neurosci 25, 3509–3520.

Swensen, A.M., and Marder, E. (2000). Multiple peptides converge to activate the same voltage-dependent current in a central pattern-generating circuit. J Neurosci 20, 6752–6759.

Tang, L.S., Goeritz, M.L., Caplan, J.S., Taylor, A.L., Fisek, M., and Marder, E. (2010). Precise temperature compensation of phase in a rhythmic motor pattern. PLoS Biol 8, e1000469.

Tang, L.S., Taylor, A.L., Rinberg, A., and Marder, E. (2012). Robustness of a rhythmic circuit to short- and long-term temperature changes. J Neurosci 32, 10075–10085.

Tobin, A.E., Cruz-Bermudez, N.D., Marder, E., and Schulz, D.J. (2009). Correlations in ion channel mRNA in rhythmically active neurons. PLoS ONE 4, e6742.

Turrigiano, G., Abbott, L.F., and Marder, E. (1994). Activity-dependent changes in the intrinsic properties of cultured neurons. Science 264, 974–977.

Turrigiano, G.G., LeMasson, G., and Marder, E. (1995). Selective regulation of current densities underlies spontaneous changes in the activity of cultured neurons. J Neurosci 15, 3640–3652.

Turrigiano, G.G., Leslie, K.R., Desai, N.S., Rutherford, L.C., and Nelson, S.B. (1998). Activity-dependent scaling of quantal amplitude in neocortical neurons. Nature 391, 892–896.

Turrigiano, G.G., Marder, E., and Abbott, L.F. (1996). Cellular short-term memory from a slow potassium conductance. J Neurophysiol 75, 963–966.

Weimann, J.M., and Marder, E. (1994). Switching neurons are integral members of multiple oscillatory networks. Curr Biol 4, 896–902.

Weimann, J.M., Meyrand, P., and Marder, E. (1991). Neurons that form multiple pattern generators: Identification and multiple activity patterns of gastric/pyloric neurons in the crab stomatogastric system. J Neurophysiol 65, 111–122.

Roger A. Nicoll

BORN:

Camden, New Jersey

January 15, 1941

EDUCATION:

Lawrence University, Appleton, Wisconsin, BA (1963)

University of Rochester, School of Medicine, MD (1968)

University of Chicago Hospitals and Clinics, Intern (Medicine) (1969)

APPOINTMENTS:

Public Health Service, Research Associate (1969–1973)

Research Associate Professor, SUNY at Buffalo (1973–1975)

Assistant Professor, University of California, San Francisco (1975–1976)

Associate Professor, University of California, San Francisco (1977–1980)

Professor, University of California, San Francisco (1980–present)

HONORS AND AWARDS (SELECTED)

Borden Award: Best Research completed during Medical School (1968)

National Institute of Mental Health, Merit Award (1987–1997)

National Academy of Sciences (1994)

National Institute of Mental Health, Merit Award (1997–2007)

Lucie R. Briggs Distinguished Achievement Award, Lawrence University (1998)

Fellow, American Academy of Arts and Sciences (1999)

Morris Herzstein Endowed Chair (1999)

Heinrich-Wieland-Preis (2004)

Perl/UNC Neuroscience Award, with R. C. Malenka (2005)

Gruber Award for distinguished accomplishments in neuroscience, with M. Ito (2006)

National Institute of Mental Health, Merit Award (2007–2017)

24th Annual J. Allyn Taylor International Prize in Medicine, with M. Greenberg (2008)

National Academy of Sciences-Neuroscience Award (2009)

23rd Annual Pasarow Award in Neuroscience, with C. F. Stevens and R. C. Malenka (2011)

Axelrod Prize, awarded by the Society for Neuroscience (2011)

Scolnick Prize, Massachusetts Institute of Technology (2012)

Ralph Gerard Prize, with Richard Tsien (2014)

Grass Lecture, Society for Neuroscience (2014)

Warren Alpert Foundation Prize, with S. H. Snyder and O. Hornykiewicz (2014)

Roger Nicoll is a pioneer in elucidating the mechanisms underlying neuronal communication in the brain. The classical concept that each central neuron integrates an ongoing barrage of transient excitatory and inhibitory postsynaptic currents to produce output spike trains is incomplete, failing to account for the sustained excitability changes that account for such important aspects of brain function as emotion and memory. In electrophysiological experiments of clarity and rigor, Nicoll has revolutionized our understanding of synaptic plasticity in the mammalian central nervous system, revealing a rich repertoire of slow “metabotropic” actions of neurotransmitter. Our current understanding of long-term potentiation (LTP) in the hippocampus is based, to a considerable extent, on Nicoll’s contributions. Based on a series of tightly controlled publications, he has demonstrated that LTP is due to the rapid recruitment of glutamate receptors to the synapse. More recently, he has discovered a family of novel auxiliary receptor proteins that are essential for trafficking of glutamate receptors as well as their gating. Based on Nicoll’s findings, the molecular underpinnings of memory are beginning to emerge.

Roger A. Nicoll

I am honored to have been asked to write an autobiography for the Society for Neuroscience’s The History of Neuroscience in Autobiography. This invitation has generated quite a strange feeling for me, because my life has been driven by what comes next. Looking in the rearview mirror has not been part of my character. Once a study has been completed and published, it is history, and I immediately turn to the next challenge in front of me. In addition, writing about myself makes me feel uncomfortable and self-conscious. So I write this as if it will be stored away in some file.

My Parents

I was born in Camden, New Jersey, in 1941. My father was a physicist and worked for RCA, which had its research division in Camden. Shortly thereafter we moved to Princeton, New Jersey, where RCA had built its new research facility. My parents both grew up in Saskatchewan. They had very different upbringings. I know a fair amount about my parents’ upbringing because they both wrote about their experiences and passed their accounts on to their children. This has stimulated me to look at my own past. My mother’s father was a physician in England, but he had been forced into this profession by his father, also a physician, and had little desire to practice medicine himself. He and my grandmother had a family of eight, living in Surrey, England. Although he saw some patients, he and his wife appeared to rely on a modest inheritance that my grandmother had received. This was not a viable long-term solution. Unlike my grandfather, who was a sedentary bibliophile, my grandmother was restless and had a pioneer spirit. It was largely based on her initiative that the family of 10 set off on a ship in 1906 on a journey that ended up in Earl Grey, on the plains of Saskatchewan, Canada. My mother (nee Neatby) was born in 1907. My grandfather reluctantly continued to see some patients, but, again, not enough to support the family. Thus, my grandmother decided to move the family to a homestead on the prairie and try farming. Farming was even more distasteful than medicine to my grandfather, and this task of running the farm fell on my mother’s older teenage brothers. The brothers had help from neighbors, in particular two Swedish brothers who not only helped with the farming but also ended up marrying my mother’s sisters.

The family was unlike others on the surrounding homesteads and, except for the Swedish brothers, did not integrate well into the community. My grandparents had come from an educated, conservative, Victorian upbringing and were deeply religious. Reading in the family was valued above all else, and many of my mother’s siblings went on to have distinguished academic careers. Thus, it is not surprising that the Neatby family was seen as eccentric, aloof, and judgmental. One example of this uncomfortable societal relationship occurred after my grandmother voiced concerns about the morals of a neighbor’s daughter. When the daughter’s parents found out about this, they sued my grandparents and won the case. In 1919, the oldest son took over the farm, and the family moved to Saskatoon, Canada, where my mother finished high school and then went on to the University of Saskatchewan. In time, my mother came to the conclusion that her father suffered from depression and was deeply aware of his shortcomings.

My father’s upbringing was demonstrably more “normal.” His great-grandparents on both his father’s and mother’s side came from the United Kingdom and settled near Peterborough, Ontario. My grandfather trained as a pharmacist, and as a young man had moved with my grandmother to Battleford, Saskatchewan. He remained in Battleford, where he worked as a pharmacist for the rest of his life. My father and his siblings grew up in a reasonably well-off environment. The family had one of the first cars in town, a Model T Ford. At an early age, my father became interested in electrical gadgets, such as telegraph, telephones, wet batteries, and radios and how they worked—thus, began his lifetime interest in physics. He went to the University of Saskatchewan, majored in physics, and received a scholarship to attend Cambridge University in England for graduate studies. This was the heyday of the Cavendish laboratories run by Lord Rutherford. I have a group picture of my father and the rest of the members of the Cavendish laboratory. In the picture are nine Nobel laureates, all of whom were still active scientists. At the University of Saskatchewan, my father met my mother who was a classmate. She followed him to England where they were married. Following graduation, he worked for a few years in London at EMI, an electronics and gramophone company. The conditions in Europe in the mid-1930s were rapidly deteriorating, and my parents decided to return to North America. He took a job at RCA, which had its research division in Camden, New Jersey, but soon after we moved to Princeton.

I was the third of four surviving children. The oldest, Patricia, lives in Bloomington, Indiana, and is four years older than I am. Ruth is next in line and has remained in Princeton; she is two years older. Finally, there is Matthew who is five years younger and lives in Minneapolis. Looking back on my childhood, it seems that we lived in cramped quarters. It was an English Tudor–style house with steep slate roofs, located a few blocks from the university stadium. For a family of six, we had three bedrooms and one bathroom, which sounds like a logistical nightmare in the morning; however, I don’t remember it causing much of a problem. We shared many outdoor activities while growing up, including two weeks in the summer at our cottage on Lake Newboro on the Rideau Canal, about 30 miles from Kingston, Ottawa. The trip to the cottage was a two-day drive, and we would camp at various state parks on the way. Our favorite was Whetstone Gulf in New York, which is built in a 400-foot-deep gorge. We befriended the ranger, who remained in charge of the park throughout our upbringing. We would spend much of the time looking for fossils, which were plentiful in the riverbed.

My mother devoted her efforts to raising the four of us. She was very important to me. She realized early on that I had a reading handicap and did everything she could to help me out. Most important, she read to me all the time, which I thoroughly enjoyed. For example, she read The Adventures of Sherlock Holmes in its entirety. My father was extremely important to me as a boy as well, although I didn’t fully appreciate it at the time. As I was growing up, I spent much of my free time with him, either in the workshop, canoeing, sailboat racing, skate sailing, or skiing—the list goes on and on. In thinking about his influence, there are a number qualities and traits that I most admired and have tried, usually unsuccessfully, to emulate. My father was modest. Despite his impressive education and research achievements, he was one of the most unassuming people I have encountered. There was absolutely no pretense or showiness about him, and with his modesty, came an extraordinary level of integrity. Another remarkable trait of his was his child-like, insatiable curiosity. This is probably the trait I admire most about him, and he maintained it until the very end. I had been worried that when he retired he would be at loose ends because his work meant so much to him. I couldn’t have been more wrong. Everything he encountered became a project for him. He would make long lists and spend hours in the Princeton University library researching various topics. Importantly, he would share his findings and his enthusiasm with those around him. He was not merely intellectual, but action-oriented; he would take his ideas to his workshop in the basement. It was an elaborate setup, with drill press, circular saw, band saw, lathe, and glass-blowing equipment. I spent much time with him or on my own there, playing with crystal radios, electric generators, ruby lasers, and many other exciting contraptions. He was a very practical person and both at work and at home he was a hands-on problem solver. He passed on to me the power of the direct approach to answering questions. The idea of having a repairman come to the house never entered his mind. If an appliance broke, he would disassemble it to locate the problem and find a way to fix it. He showed me the power of one’s hands in solving problems. My father had difficulty displaying affection, but in retrospect, I can see that he was extremely supportive and nonjudgmental. Although I was doing poorly in school, there was little criticism and instead he encouraged me in those things where I could excel. When I finally found myself and ended up in medical research, he was most supportive. He would keep track of all my papers and, having become an expert at bookbinding in his later years, bound my papers into volumes, until his motor skills prevented him from continuing.

A Couple of Childhood Memories

In high school, I spent the summers doing construction work. The first job was Kendall Park, New Jersey, a massive housing project similar to Levittown. They offered two model houses, priced at ∼$16,000 each and the goal was to build ∼50 houses that summer. The first day I went to the building site with a couple of my friends, and we were hired. It was hard work in the blazing sun and at the end of the day one friend quit. But two of us stayed on for the entire summer. We were on the framing crew and were paid $1.75/hour. I was told that one of the workers was overheard talking about unions and was immediately fired. Besides framing, there was also an option to do piecework, where you were paid a set amount for each defined project that you completed. We saw a couple of Latinos doing piecework, and they were clearly making more than the hourly wage we were making. So we asked the foreman if we could also do piecework. He agreed. We were excited at the thought of making lots of money. However, by the end of the first day, we learned to appreciate how efficient the Latinos were, because we ended up making less on the piecework scale than on the hourly wage. We sheepishly went back to the foreman and begged to be put back on the hourly wage. He agreed, fortunately. After that first summer, I worked for individual contractors for the next two summers. I enjoyed construction, especially the framing. There was something fulfilling about creating a lasting structure with your own hands. I visited Kandall Park some years ago and the houses were still standing!

Another formative moment was discovering the book The Silent World by Jacques Cousteau when it came out in 1953. This was the most amazing book I had ever encountered. Cousteau recounts the history of man’s obsession with exploring the oceans, untethered to the world above. He masterfully conveyed this irresistible desire and described his key role in developing the self-contained underwater breathing apparatus (SCUBA), which made this dream a reality. At the time, I was snorkeling off the rock jetties at the New Jersey shore, and it wasn’t until much later that I took up SCUBA diving. Cousteau was a hero of mine early on, but I became disenchanted with him. My image of him as an inventor driven by curiosity, was replaced by the image of an egocentric showman who marketed his films in the cloak of science and discovery, when, in fact, they were basically contrived adventure stories, solely for entertainment. However, I do admire him for his early, strong advocacy for the environment and still credit his book for opening up a whole new world and inspiring me with the freedom to explore it.

A Slow Start

By the third grade, both my teachers and my mother realized that I had dyslexia. So during the second and third grade, my mother arranged for me to have extensive psychological testing and tutoring. However, as anyone with dyslexia well knows, tutoring has no effect. The neuronal wiring in the part of the brain that is responsible for reading is faulty, and, unfortunately, one cannot correct faulty wiring. My only hope was to develop alternative strategies around this handicap, which I finally did, but it took many, many years. My reading is no better now than it was in grade school. Based on reading the English subtitles of foreign language movies, which I rarely go to, I estimate that my reading speed on average is at best a third of what is normal. The one “advantage” to being dyslexic is that it enforces a slow and methodical reading of one word at a time, which firmly imprints the contents of passages into my brain. I am hopeless at spelling. In grade school there were spelling bees. The teacher would select two captains who would stand on either side of the room. They would then alternate selecting their team members from the class. I was invariably the last person chosen. I used to have a paperback dictionary at my side all the time. The only problem is that my spelling was so bad that it was often impossible to find the word. The computer spellcheck program was an improvement because it would at least tell me that the word was misspelled. However, more often than not, the selections of words it offered did not include the word I was looking for. Google has been a lifesaver for me. I use it all the time and it almost invariably, after a couple of tries, finds the word I am searching for.

Dyslexia is a word that is thrown around a lot nowadays, such that its meaning has become rather vague and misleading. For instance, a number of high-profile individuals who are in such professions as law and business claim that they have dyslexia, yet they attended Ivy League schools and are in fields that depend heavily on massive reading tasks. I can only conclude that they must have a different variant of the malady than I do because such accomplishments are absolutely inconceivable to me. There is no way I could come close to performing adequately on the language part of the SAT to be competitive or to complete the test on time. The first time I took an intelligence quotient test, I scored 70 (which at the time was equated with “feeble mindedness”). Fortunately the school psychologist let me take an untimed test and I scored better (118). In those days, having reading problems was more or less equated with being mentally impaired. Thus, for me, it was the stigma associated with dyslexia that was most crippling. I spent much of my energy trying to conceal this defect, and when I failed, the resulting ridicule was unbearable. Thus, I felt terribly vulnerable and had low self-esteem. Above all else, I was frustrated, because deep down inside, I was convinced that my performance didn’t accurately reflect my true abilities. It is this frustration, this inability to express myself and be recognized for who I am that became the overriding driving force in my life. It is this handicap that has given me a special empathy for those with similar issues that impair performance, but that do not reflect traits such as intellect, curiosity, and drive, which are equally or more important.

I went to Princeton High School. Princeton was a most unusual place and was dominated by the university. The university was a world-class center for math and physics. My classmates included the offspring of famous physicists, such as Peter Oppenheimer (son of Robert Oppenheimer), David Wigner (son of Eugene Wigner), and Alison Wheeler (daughter of John Wheeler). Not surprisingly, I struggled and did not do well graduating 128 out of a class of 305 with a grade point average (GPA) of 2.13/4.0. It is hard to explain my internal turmoil when surrounded by classmates and friends who were deciding on which Ivy League school to attend, while I was just hoping to go to college anywhere. Eventually, I came across an advertisement in a magazine that saved me. Would-be students submitted their applications to a pool and colleges would look over the application and accept anyone that seemed promising to them. Remarkably, I was suddenly in great demand. It was a great ego boost, even though I had not heard of the majority of these schools. Lawrence College (now Lawrence University) in Appleton, Wisconsin, contacted me, and it looked like a pretty good place. So what did they see in me? Their student body at the time was overwhelmingly from the Chicago area and as an Easterner, I would bring some “diversity” to the school. This notion was quickly confirmed at the social for the first-year students. I bumped into the head of admissions who glanced down at my nametag and said, “Oh, you are the one with the low SAT scores.” It was not an encouraging start.

As was entirely predicted by my high school record, the first year in college did not go well. I was placed on academic probation and had one semester to bring my GPA up to a C or I was out. This was a major turning point in my life. My only hope was to focus on science courses and put off course requirements that involved extensive reading. That summer I immersed myself completely in two semesters’ worth of biology at Rutgers University and did very well. The credits were acceptable at Lawrence and they brought my GPA up to a C. This was a huge confidence builder. It was the first time I realized that my handicap didn’t automatically doom me to mediocrity and that with intense effort, I could take control of my future. From that point forward, I felt that anything was possible. I then focused on science courses and managed to turn things around. In the end, I still had a very mixed record, but my final GPA of 2.5/4.0 represented an improvement over high school. To this day, I owe Lawrence an enormous debt of gratitude for taking a chance with me and sticking with me through those turbulent transitional years. Thus, it was a very special moment for me when I was invited back to receive their Distinguished Alumni Achievement Award in 1998.

In the summer of my third year of college, I worked at the New Jersey Neuropsychiatric Institute, a mental hospital referred to as Skillman. There was a lab run by an internist who practiced medicine in Princeton. There were four or five people in the lab. He would show up about once a week to go over data. The study involved the use of rabbits as a model for arteriosclerosis. A high-cholesterol diet resulted in cholesterol deposits in the arterial vasculature. My recollection is that the research was to determine whether feeding rabbits a modified rabbit chow had any effect on high-cholesterol-induced plaque formation. I can’t remember what was actually changed in the chow; however, I was extremely disappointed with this experience. There was little oversight to the project, and those carrying out the experiments were all technicians. No one ever seemed to ask any questions. Indeed, no one seemed to be at all interested in what they were doing. My recollection is that they would drift in around 10–11 A.M. and then leave around 4 P.M. They also took long lunches. I can remember discussing my disappointment about the research experience with my father. He felt that at my naïve stage, it was rather arrogant for me to be so judgmental. Two years later, I learned that the funding for the project had been terminated, and I felt a sense of validation that I had assessed this situation correctly. In any event, I took a job as an orderly at Princeton Hospital on the evening shift, in addition to the day job, to see what a hospital environment was like. This was a very positive experience. I had time to talk to the attending physicians, who were more than happy to answer my questions. I also got to observe autopsies and learn some anatomy. My hospital experience prompted me to apply to medical school. This is not to say that I was in any way rejecting research, but I concluded that going to medical school would open up the most options for my future.

Medical School

Of course, before you can go to medical school, you have to be accepted into medical school, and with my less-than-stellar college record, my prospects were not bright. Nevertheless, despite a GPA of 2.5/4.0, I got into one: in fact, I got into a fantastic medical school, the University of Rochester School of Medicine. So, how did that happen? The only explanation besides blind luck that I can come up with is that my mother, who was a very eloquent and forceful writer, wrote my essay. The first two years of medical school were heaven to me. The only frustration was that there was no time to “push the pause button” and delve into something I found fascinating.

Given that I ended up turning my back on clinical medicine, one might think that pursuing a PhD degree would have been a more logical path. For me, however, the medical education, at least the first two years, was essential. My tendency from early on had been to find something of interest and then to focus on it relentlessly; I was pretty deep but pretty narrow. The first two years of medical school forced me to step back and take a panoramic view of all of the latest developments in biomedical science. It was invaluable. It confirmed my love for what would eventually become neuroscience (the word had not been coined yet). I had developed an interest in neuroscience in college. Although there were no courses dedicated to the nervous system in college, the profound lesson that evolutionary biology impressed upon me was the supreme importance of the nervous system in coordinating and determining behavior of organisms as they became more and more complex. I was fascinated by the cephalization of the nervous system, and there was no doubt that the human brain is evolution’s crowning achievement. I immediately began considering various approaches by which one might unlock the mysteries of the brain. I thought about neurology, but concluded that it was impossible to carry out rigorous controlled observations. It seemed obvious that, to understand the brain, you had to actually look inside the skull. I turned briefly to neurosurgery as an alternative and attended a number of operations. However, the way neurosurgeons treated the brain, sucking out surprisingly large and irregular chunks of it, made a very negative impression on me. It was hard to imagine how precise data could come out of such coarse procedures.

In the first-year neuroanatomy course, I began to see how one might go about studying the brain at the level that interested me. I was initially attracted to the sheer beauty of the cellular morphology and architecture of the brain, particularly of the cerebellum. Why are the Purkinje cells lined up in a single layer, each with their enormously elaborate dendritic trees? Why does each Purkinje cell receive only a single climbing fiber, which entwines itself around the dendrite, forming hundreds of synapses with it? Because the cells and connections in the cerebellum are unique to the cerebellum, surely answering some of these questions would give us insight into what the cerebellum does. It seems to me that the most tractable approach to understanding the brain would be to focus on the individual building blocks (i.e., the neurons). As the Spanish neuroanatomist Ramon y Cajal so elegantly put it in his autobiography, “The inscrutable mystery of the organization of the brain attracted us irresistibly. We saw that an exact knowledge of the structure of the brain was of supreme interest for the building of a rational psychology. To know the brain, we said, is equivalent to ascertaining the material course of thought and will” (Cajal 1989).

The extraordinary beauty of the cellular architecture that had been so carefully revealed by Cajal, however, tells us very little about what the neurons are actually doing. During my first year, medical students got a demonstration on intracellular recording from frog skeletal muscle. The resting membrane potential, action potentials, and the endplate potential were demonstrated. The idea of being able to record from a single cell was very appealing to me, and I searched around the medical school for someone who was doing intracellular recording and who would take me on during the summer. I came across a professor in the pharmacology department who was using intracellular recording to study the effects of drugs on the heart. I explained that my interest was to use this technique in the CNS. He suggested that I look at the effects of a drug (I can’t remember which one) that he had found to have effects on spinal cord reflexes. He proposed that I examine the drug’s effects on the excitability of dorsal horn interneurons using intracellular recording. Unfortunately, he had never actually recorded either extracellularly or intracellularly from nervous tissue; indeed, I don’t believe that he had ever done a spinal laminectomy. There was a technician in the lab doing intracellular recording in cardiac tissue. Although he was very helpful, I was largely on my own, and I only had 10 weeks! I borrowed a stereotaxic apparatus from another professor, built my own Faraday cage, and cobbled together a setup with micromanipulators, amplifiers, loudspeaker, stereotactic instrument, oscilloscope, and a Grass kymograph camera.

I soon began to have doubts about the project and I went to the professor to get help on what to look for when I inserted a microelectrode into the spinal cord. He admitted that he really couldn’t help me, but he gave me a copy of The Physiology of Nerve Cells by Eccles (1957). Because, as always, reading was a challenge and because I had very little time, I looked up spinal interneurons in the index and was disappointed to find very little on this topic. I put the book aside and forged ahead on my own. However, in no time, it became clear to me that I was in over my head. I had no background whatsoever, not even the neurophysiology section of the physiology course, which was given in the second year. So I reversed directions and started at the beginning of the book to find out what this field of neurophysiology was all about. By the end of the first couple of chapters, I realized that the hunch I had during the demonstration on intracellular recording from muscle was correct. Intracellular recording was unquestionably going to be the way to study the brain. The book documented that with glass microelectrodes it was possible to go deep into the brain and record the private synaptic communications occurring within a single identified neuron. Here was a technique that could bring the beautiful but static cellular architecture of Cajal to life. I spent much of my time during the summer and the next year of medical school devouring the contents of The Physiology of Nerve Cells and The Physiology of Synapses (1964), which had just been published, along with reading essentially all of Eccles’s papers that were listed in the reference sections. I didn’t give up completely on the experiments and managed to make a few recordings from motoneurons, which let me examine antidromic action potentials and primary afferent monosynaptic excitatory postsynaptic potentials. Given the conditions, and my rank inexperience, I am amazed that I got anything at all.

I had the pleasure of being taught all of neurophysiology by Bob Doty. He was an early role model of mine and he contributed an autobiography to this series a long time ago. His lectures were unlike the typical medical school lecture. He used no notes, relying entirely on drawing on the backboard. He would focus on presenting the classic papers in neurophysiology. This course was the highlight of my first two years. My fellow medical students were most irritated with this style of lecturing. They just wanted the facts. The second year also introduced me to neuropharmacology. At the time, a great deal was known about the peripheral nervous system (PNS). It was well established that synaptic transmission in the PNS was mediated by the release of neurotransmitters, in particular acetylcholine (ACh) and norepinephrine (NE), which acted at specific receptors on the postsynaptic cell to control its excitability. On the basis of this fundamental information, a rich and rational pharmacology developed that allowed precise control of normal and abnormal peripheral synaptic function, such as cardiac arrhythmias, hypertension, asthma, and myasthenia gravis. In striking contrast to this sophisticated knowledge of peripheral synapses, virtually nothing was known about synaptic transmission in the CNS—only ACh release onto spinal Renshaw cells had been established. This void, this complete mystery, drew me irresistibly to the brain. Should it not be possible to identify the transmitters and their receptors and with this knowledge construct a rational pharmacology to decipher and treat disorders, such as schizophrenia, depression, Parkinson’s disease, or dementia? I was convinced of this and remember presenting to a small-group session in the pharmacology course a recent paper in which Eccles and colleagues (Eccles et al. 1963) carried out a pharmacological study implicating gamma-aminobutyric acid (GABA) as the transmitter for presynaptic inhibition in the spinal cord. The other students were polite, but not nearly as excited as I was about it. I was getting restless.

A Monastic Life

My summer research experience had tantalized me with the unbelievably powerful technique of intracellular recording, but also showed me that the only way to master this technique was to go to a lab that specialized in it. There were not many, so I shot for the top and wrote to Eccles, who was at the Australian National University in Canberra, asking if I could join his lab for a year. He had just won the Nobel Prize and was in great demand. The closest I could get was a brief rejection letter from him. So I looked at other possibilities and, with help from a neurologist at Rochester, I was put in contact with Dr. Gian Salmoraghi at the National Institute of Mental Health (NIMH) at the National Institutes of Health (NIH).

Dr. Salmoraghi was receptive to my request, and I decided to take a year off after the second year of medical school and join his lab at St. Elizabeth’s Hospital in Anacostia in Washington, DC. I felt confident in my knowledge of electrophysiology, but less sure of my abilities in the lab. I needed to test myself to see whether I could actually do experiments on my own and discover something, anything. St. Elizabeth’s hospital used to be the largest mental hospital in the country, housing 8,000 patients with dozens of buildings on a sprawling campus. I rented a room on the grounds for $20.00/month and led a monastic life focusing 100 percent of my time on research. I ate all my meals at the hospital cafeteria and rarely left the hospital grounds. The only diversion was regularly attending the free concerts by the Juilliard String Quartet, which recently (1962) had been invited to be in residence at the Library of Congress, under the auspices of the Gertrude Clarke Whittall Foundation. Thanks to the foundation, the Library of Congress has a complete set of Stradivari accompanied by Tourte bows, which are used by the quartet. The Juilliard still plays at the Library of Congress.

The year at St. Elizabeth’s was the turning point in my life. By its end, I was convinced, rightly or wrongly, that I could hold my own experimentally with anyone in the field. What was so transformative about this experience? Experimental science, especially electrophysiology, provided an exciting level of control. You could essentially have a dialogue with the experimental tissue in real time. You probe the preparation, expecting a certain response. Much to your surprise something else happens. What could that possibly mean? You come up with possible explanations, modify the ongoing experiment, and probe the tissue with another test, and so on. There is nothing more exciting than testing your wits against Nature. You are in the driver’s seat, but Nature has the final say. In this process you are led down paths that no one else has ever taken. It is interesting to compare electrophysiology to other disciplines, such as biochemistry and molecular biology, where there isn’t this intense immediacy of discovery. I wonder whether I would have been so smitten with research if my first exposure had been in one of these disciplines.

In any case, it was in this mental hospital in Anacostia, that I had finally found my voice. I felt freed from my childhood frustrations and inadequacies. With this new-found freedom, came a sense of empowerment and confidence. It is through carefully crafted and controlled experiments that I communicate. In fact, it’s all in my figures. Ideally a figure should be a self-contained narrative, a short story. There should be just enough labeling to guide the reader. The key finding is presented in the first panel, which has to be dramatic and compelling—no statistics required. Hopefully, the reader buys and is intrigued by the initial finding, but immediately comes up with a series of possibility explanations, which then are addressed one by one in the following panels. The goal is that there is no need to read the text, or the figure legends, or, for that matter, to listen to me talk about my work. It’s all in my figures. You either believe the figures or you don’t. If I have to try to persuade you, I have failed. This is why I have always strived to make figures stand alone, without forcing the reader to dig through the complex figure legends. I try to present data in a way that is intuitive, without extraneous text, to communicate directly via the evidence. I remind the people in my lab when they go back to their computers to make yet another series of changes that, if their story is remembered at all, it will be because of the figures. When a paper is presented in journal club, it is the figures that are discussed.

It is my belief that the underlying drive of a scientist is little different from that of an artist, broadly defined. The motivation is to discover and create something beautiful. Scientists have a constraint, however, in that the product of their creativity has to be “true,” that is, reproducible. For most individuals, this act of creation is not enough. In both endeavors, there is a need for validation—that others also find your creation beautiful. Artists and scientists are both needy. Thus, for example, artists go to art fairs to exhibit their work, with the hope that others will appreciate it (and buy it). They are also subject to the judgment of critics. Scientists publish their findings, a process that can be most painful (particularly when the reviewers do not share the same enthusiasm for your creation as you do). They also seek praise when presenting their findings at meetings.

Even with my newfound self-confidence, presenting my results in public gave me intense anxiety, and for many years, I didn’t get a moment’s sleep the night before a presentation. Going up onto a stage in front of a crowd was terrifying, bringing out all my worst insecurities and self-doubt. I would write out the introduction and memorize it word for word. I always had the written introduction in front of me, even though I never looked at it—it just served as a security blanket. I would insert the minimal number of words between each slide and focus on the individual traces of electrical recordings on the slides. My goal was to always direct the attention of the audience to the data and away from me (you can imagine the discomfort when I started to write this autobiography).

A Medical Interlude

After my year at NIMH, I returned to medical school. At this time, the Vietnam War was at its peak and all medical graduates were drafted into the military. The only other option was to obtain a medical research position at NIH, which would fulfill one’s military requirement; those of us who took this path earned the irreverent moniker “Yellow Beret” (in contrast to the revered Green Berets in the war). It wasn’t meant as a compliment. As I was finishing up the year at NIMH, I discussed my future with Dr. Salmoriaghi, specifically asking whether he would take me back into the lab after my internship. Having a position was critical if I was not to be drafted into the regular military. He agreed and assured me that I would not have to put my name into the pool of applicants because of this agreement. He would arrange things so I would be assigned directly to his lab. This looked to be a great bonus for having decided to spend the year at NIH.

As a part of the medical school curriculum, we had a 10-week elective period. By this time, Eccles had moved to Chicago, and I wrote to him again asking to join his lab for this elective period. This time the rejection letter was longer and more positive, but in the end concluded that it really didn’t make sense to have me spend such a brief time in his lab. Soon, however, I had a bigger problem. Having completed medical school, I was just finishing up my medical internship at the University of Chicago and was waiting to hear about my assignment to Dr. Salmoriaghi’s lab. Other interns were receiving their appointments and I started to panic. I called Dr. Salmoriaghi, and he initially began hemming and hawing. In desperation, I interrupted him and reminded him of his promise, while at the same time imploring him to help me out. He said he would get back to me, and after a short time he did. It seemed that Dr. Salmoriaghi had assumed a higher position and had recruited Floyd Bloom to take over his lab and needed to discuss the situation with Floyd. Shortly thereafter, Floyd phoned me and said he was delighted to accept me into his lab. I have never felt such relief in my life.

Given the pleasure that I derived from doing experiments, it may not be too surprising that I found clinical medicine to be quite alien. Putting on a white jacket made me feel uncomfortable, especially as a student. I felt like I was pretending to be a doctor. The fact that patients attributed unwarranted wisdom to me, just because I was wearing this jacket, made me feel all the more uneasy. Add to this the fact that as an intern, one has to make very serious decisions and yet has to base them on only limited and imperfect data, made my discomfort all the more acute. I never got entirely over a feeling of inadequacy and responsibility around sick patients. I also couldn’t connect to the reward system. In medical school, the intern would ask me to do a ton of scut work and, as a reward, would let me do the next lumbar puncture. The problem was that I didn’t really have a burning desire to do a lumbar puncture, but I had to pretend otherwise.

I have grappled my whole adult life trying to understand why my feelings toward the practice of clinical medicine and basic research are so opposed to each other. I have concluded that the two disciplines could not be more fundamentally different. Clinical medicine follows extremely fixed protocols. If you don’t follow this protocol and something goes wrong, you will rightly be held accountable. For basic science an immutable protocol is anathema to experimental inquiry. The only constraint in the laboratory is the limit of one’s imagination. You are led into uncharted territory by what Nature, the experimental preparation, presents. As a physician, you make an effort to tie together a variety of symptoms into a coherent diagnosis. You consider various possibilities, but can have only limited confidence as to whether they have any validity. A treatment plan is initiated and the symptoms diminish. Was the diagnosis correct? Did the treatment actually work? You will never know for sure. The prospect of following this path was extremely unsatisfying to me.

I am, of course, most thankful that there are individuals who are dedicated to taking care of patients and not distracted by the “academic” details about which I obsess. Indeed, some recent medical problems have reminded me that I literally owe my life to skilled clinicians. Still, even in retrospect, it is clear that the idea of practicing medicine was never an option for me. I had taken and passed the medical boards at the end of my internship. Years later, I was asked whether I would write a prescription for someone. Only then did it dawn on me that I had not paid the nominal fees to get my medical license.

Some of My First Studies

Because my times at St. Elizabeth’s Hospital, both during my year off and upon my return after my internship, were so pivotal to my career, I would like to share with you a few of my first studies. At the time, the neurotransmitters of the brain were a complete mystery. There was good evidence that GABA was a transmitter in invertebrates and was present in high amounts in the brain. Eccles (Eccles et al. 1963) had recently published evidence implicating GABA as the transmitter for presynaptic inhibition. So I looked to see whether GABA might mediate postsynaptic inhibition in the olfactory bulb (Nicoll 1969, 1971). The relay neurons, referred to as mitral cells, form excitatory contacts with the spines of inhibitory granule cells. The granule cells form inhibitory synapses immediately next to the excitatory synapses back onto the mitral cell, an arrangement referred to as reciprocal synapses, the substrate for dendrodentritic inhibition. I used multibarrel microiontophoresis to test the sensitivity of mitral cells to GABA. Similar to its action on other neurons in the brain, GABA inhibited mitral cell activity, and this action was reversibly and selectively blocked by the GABA antagonist picrotoxin (Nicoll 1971). During these experiments, I noticed that application of a glutamate agonist often caused an inhibition, a most puzzling observation. This inhibition was reversed into an excitation by co-applying picrotoxin. These results indicated that in many cases the granule cell spine was more sensitive to the agonist than the mitral cell and activated the reciprocal synapse: Thus, blocking this feedback inhibition with picrotoxin revealed the direct excitatory action on the mitral cell. This result provided strong evidence that the transmitter being released from granule cells is GABA.

During these experiments (Nicoll 1972) I noticed that whenever I gave a supplementary injection of the general anesthetic pentobarbital, the mitral cell inhibition was massively prolonged and doses in humans that would just cause drowsiness prolonged inhibition. Halothane, a volatile anesthetic, had the same effect. These effects occurred in the complete absence of any effect on the synaptic excitation of the granule cell spine, so I proposed that anesthetics and sedative hypnotics act selectively on synaptic inhibition and more specifically on prolonging the action of GABA. This remains a widely accepted explanation for the anesthetic–sedative hypnotic effects of barbiturates and other general anesthetics. This work was initiated during my year’s leave of absence from medical school and was completed upon my return to the lab now under the leadership of Floyd Bloom. It is important to note that the three papers that I have discussed about GABA are all single-author papers, and I owe Floyd Bloom an enormous debt of gratitude for his graciousness. When I joined him, he said that I clearly already had developed a number of ideas and projects, and I was free to pursue them on my own. Such generosity is rare.

Working with Eccles

As I was finishing up at St. Elizabeth’s Hospital, I had to decide on my next step. I had one remaining piece of unfinished business. I wrote to Eccles who was now at SUNY at Buffalo and asked, once again, if I could join his lab. Third time’s a charm, and he invited me to join his group. Why this obsession to work with Eccles? I had read virtually every one of his papers backward and forward, and I wanted to have a context for these discoveries. I also wanted to see how he approached problems and went about doing experiments. It was a crucial stage in my journey. My only regret is that I had not been able to join Eccles in Canberra when I first wrote to him. Eccles was consumed by, and passionate about, science. He maintained a child-like curiosity, just like my father. I can recall him coming down the hall waving a copy of a journal article he had come across that he wanted to share with me. He had an immense ego, and you had to show him the appropriate deference; otherwise, he had little interest in you. We had a wonderful relationship because I wanted to go back and discuss the context of all of his papers. At this stage, I knew their details better than he did, and he loved to regale me with the backstories. When Eccles died I had the honor of writing his obituary for Science, reflecting on his contributions to science, which were many (Nicoll 1997). However, I lamented that many of these findings are now taken for granted, and appreciation for his seminal contributions in shaping our understanding of the brain has faded.

He also would bring up philosophical topics because he was writing a book with the philosopher Karl Popper. Eccles had by that time become a “dualist,” someone who felt that there must be more to nature than atoms moving in space. I found these discussions excruciatingly painful. His search for something more than materialism left me cold. I remember his returning from a meeting where he debated with the well-known philosopher John Searle from the University of California at Berkeley. It was clear to me that Eccles was way out of his league, but he persisted. Another area of disagreement concerned politics. Eccles was extremely conservative. It was the peak of the Watergate hearings. Eccles was solidly supportive of Nixon and considered the hearings a conspiracy. He also considered John Dean’s testimony a series of lies. However, when the Watergate tapes finally appeared and one could listen to the sleazy and profane level of discourse in the Oval Office, Eccles never again brought up politics. He realized from then on that our interaction had to focus entirely on science.

Our initial project was a continuation of a series of experiments that Eccles had pursued for a number of years, which involved studying the flow of information into and out of the cerebellum. In our study, we recorded extracellularly from antidromically identified reticulospinal brain stem neurons (Eccles et al. 1975). Eccles would arrange his schedule so that experiments could be carried out when he was present in the lab. Thus, he was involved in each of the experiments from the surgery to the recordings, which typically lasted late into the night. The speed with which he did a spinal laminectomy was amazing. The experiments involved stimulating a variety of peripheral sensory nerves and constructing histograms of the effects that the stimulation had on the firing of the reticulospinal neurons. These histograms allowed us to make inferences about the effects of the cerebellum in sculpting the firing of these neurons. Many of the responses of the reticulospinal neurons were of long latency, and although the involvement of the cerebellum in shaping these responses was likely, it was impossible to rule out the possibility that other pathways were importantly involved. Although I learned a great deal about how Eccles went about doing experiments, I found these experiments unsatisfying, and I think he realized that my heart was not in them.

Meanwhile, when Eccles was traveling and not able to carry out experiments, he encouraged me to set up my own experiments in a vacant room. I had been working on the isolated frog spinal cord preparation while I was at NIH. I was interested in using the frog spinal cord to examine the idea that the Cl⁻ gradient across neurons was not passively distributed, as had been assumed by Eccles and almost everyone else. Previous results by others had found that ammonium (NH₄) ions caused a depolarizing shift in the reversal potential of inhibitory postsynaptic potentials (IPSPs) in spinal motoneurons, suggesting that Cl⁻ was not passively distributed. To try and get some direct evidence, I examined the effects of NH₄ ions in the isolated frog spinal cord where one could apply drugs in known concentrations. I was able to show that NH₄ ions were very effective in blocking the hyperpolarizing action of both GABA and glycine, consistent with previous in vivo results. Eccles showed a keen interest in what NH₄ might be doing and suggested that we do some experiments in the hippocampus where IPSPs were unusually large. I reminded him of an earlier conversation when he told me that he had cut a deal with Per Andersen, a former postdoc who had introduced the hippocampus to Eccles. The arrangement was that he, Eccles, would not touch the hippocampus if Per did not touch the cerebellum. With a smile, Eccles assured me that the statute of limitations had long since run out on this pact.

For these studies, we would begin each experiment by anesthetizing the cats with nitrous oxide (NO), and when we obtained our first stable records of IPSPs from a hippocampal pyramidal cell, we would inject increasing amounts of barbiturate. This would permit us to directly record the effects of barbiturates on IPSPs. I wanted to follow up on my earlier extracellular recording experiments on the effects of anesthetics on synaptic inhibition in the olfactory bulb (Nicoll 1972). The experiments in the hippocampus went very well, and we clearly established that even very small amounts of barbiturate, equivalent to doses that would just cause drowsiness in people, so that they were clinically relevant, caused a prolongation in the IPSP. Anesthetic doses caused as much as a fivefold increase in duration. I wrote up the first draft of a short paper for Nature with these results and listed the authors alphabetically, as I believe Eccles had done without fail throughout his career. Much to my surprise, he put my name first, rather than his own, and made a number of other suggestions (Nicoll et al. 1975). It is hard for me to express how honored I was for this courtesy.

The main purpose of these experiments was to carry out a detailed characterization of the anionic permeability of the channels activated during the IPSP and to determine whether the hyperpolarization was generated solely by the movement of Cl⁻ (Allen et al. 1977). Using a series of different-sized anions in our recording electrode, we concluded that the anion permeability of hippocampal IPSPs was the same as that reported previously by Eccles for spinal motoneurons. Much to our surprise, however, NH₄ ions, even in high concentrations, had very little effect on IPSPs. Thus, although most of our results were consistent with a selective increase in Cl⁻ permeability, it appeared that the mechanism that maintains intracellular Cl⁻ at a low concentration differed from that at work in motoneurons. One of the first projects that I initiated after setting up my own lab was to examine the effects of NH₄ ions on IPSPs in hippocampal slices where known concentrations of drug could be applied. Although Brad Alger and I (Alger and Nicoll 1983) eventually confirmed the resistance of the IPSPs to NH₄ ions, it is still not clear why NH₄ ions are so much more effective on motoneurons than they are in pyramidal cells.

Perhaps the most important thing I took away from my relationship with Eccles was his championing of Popper’s notion of falsification and how it is the fabric of experimental science—it guides every thought and every experiment. There is nothing more rewarding than coming up with an experiment that is so tightly controlled that the result must be accepted, especially if it definitively puts to rest your most cherished idea. It frees you to move on. Psychologically, of course, there is nothing more beautiful than having your pet idea survive the most frontal assault that you can marshal. Your idea survives to live another day! But you must be the harshest critic of your own data, if you want to experience the greatest joy at its success.

A number of years ago I had a discussion with my former postdoctoral fellow, Massimo Scanziani. He mentioned that he had come across a paper that he thought I would be interested in. It was by John R. Platt and entitled “Strong Inference” (Platt 1964). I can’t believe that I had not previously come across it. It is my manifesto. I love the “in your face” style of writing. The paper begins: “Scientists these days tend to keep up a polite fiction that all science is equal… . This keeps us all cordial.” He quotes W. A. H. Rushton: “A theory which cannot be mortally endangered cannot be alive” (p. 349). He elaborates eloquently on Popper: “The difficulty is that disproof is a hard doctrine. If you have a hypothesis and I have another hypothesis, evidently one of them must be eliminated. The scientist seems to have no choice but to be softheaded or disputatious” (p. 350). I have been accused of being disputatious my entire scientific life, and I wear that badge with honor. It is not surprising that I think in black and white, and it is this view that drives the crafting of experiments with the least amount of wiggle room. It is only with great reluctance that I give in to a touch of gray. I am afraid that the long-term potentiation (LTP) field suffers to a degree from soft-headedness. Perhaps this is why I have never felt fully accepted into the LTP club.

I also have acquired the reputation of being competitive, an accusation that I also accept. Both in sports and science I am, indeed, competitive. The rules of the game have to be well accepted by all. Thus, there is a question in the field that everyone agrees is important. The goal is to come up with the most compelling and elegant experiment that will, ideally, convince your fiercest opponents that your wits outsmarted theirs. Of course, sometimes my competitors outsmart me, and I graciously tip my hat to them. My reaction to reading an excellent paper by an opponent is a mixture of extreme joy and intense envy. The competition is one of the things that I find so exhilarating about science. Most important, you have to play by the rules, just as with tennis, for example. No fudging of data/line calls, and graciously hopping over the net when you are bested.

Confidence in my own abilities and experiments has coexisted with the lingering insecurities and lack of self-esteem from my childhood. Psychiatrists refer to this as reaction formation. Depending on the circumstances, either the confidence or the insecurities hold sway. This has resulted in a lifelong, wild, emotional roller coaster ride. The contradictory emotions have had a profound effect on everything from initiating new projects to taking on a new trainee. These mood swings are also linked to the evolution of a project. As a project takes clear form, my excitement ramps up and reaches exhilaration when the paper is finally accepted. Shortly thereafter, the mood turns to despair, because there is no guarantee that this process of discovery can be repeated. At this point, I would lament “the cupboard is bare.”

Launching a Career

My period with Eccles was an essential part of my journey. But I then had to find a job. I applied to around 15 medical schools for a faculty position and received very little response. I was surprised because I had published 16 papers, many appearing in Science and Nature, where I was either the sole, first author, or last author. I suspect that this was partly because Eccles had never been accepted into the neuroscience establishment in the United States. He was seen as a brash, overbearing Australian and felt as an outsider. He confided in me his regret that the community never embraced him. Thus, amazingly, my association with this Nobel Prize winner may have actually been a detriment in finding a job. Nevertheless, I had applied to two jobs at the University of California, San Francisco (UCSF): one in the physiology department and the other in the pharmacology department. I was invited out for an interview, the only such invitation that I got. Evidently, I did very well, having read all the recent papers of the individuals with whom I interviewed. Yet it wasn’t clear where, if anywhere, I’d end up. The two departments could not have been more different. Physiology was a well-respected department with a number of prominent researchers. Pharmacology, on the other hand, was considered to be a backwater, an embarrassment. Physiology took the position that, since pharmacology was initially responsible for inviting me, the offer would come from pharmacology. To me it made no difference. All I wanted was a job where I could do my own research. When the offer from pharmacology came, I leapt at it. As the two years with Eccles were coming to an end, it was a very poignant and bittersweet time. We were both packing our belonging, and I helped him fill piles of mailbags with his collection of volumes of the Journal of Physiology, which went back uninterrupted to the 1920s. While he was retiring to Switzerland, I was moving to California to begin my career. It is amusing to recall that not long after I arrived at UCSF, I encountered a biochemist with whom I had interviewed. He was in disbelief that I had accepted a job in the pharmacology department. How pathetic! But I’ve had no regrets. Pharmacology was extremely supportive of me and protected my time for research.

I have been fortunate to have had a long and productive career (and, hopefully, it’s not over); far too long to cover in detail. In the following few sections, I’ll just review a bit of the first work and some recollections of other work. My selections should not be interpreted as meaning that this work is the best or most memorable. Indeed, I wish I had time and space to discuss all of the projects that my students, postdocs, and colleagues were able to accomplish. I am proud of what we did, and I look back on our work and times together with fondness.

The Hippocampal Slice

While I was at NIH, a frustration was developing in the new field of neuroscience. The use of anesthetized animals greatly constrained the types of experiments one could do. Stable recordings were difficult and the use of iontophoresis for pharmacology experiments was extremely limiting; you never knew exactly where the drug was applied or its concentration. During this period, many neuroscientists decided to move to invertebrate model systems, where one could visually identify the large neurons and precisely control solutions bathing the neurons. I was very envious but hesitant to leave the vertebrate CNS. I developed the isolated frog spinal cord, which had first been used in the late 1930s together with sucrose gap recording, which offered many of the advantages of invertebrate models. The primary goal for adopting this preparation would be to understand the mechanism of action of both excitatory (e.g., glutamate) and inhibitory (e.g., GABA) amino acids on primary afferent terminals and motoneurons. This was a compromise between high resolution and physiological relevance, however, and the neuroscience field never really embraced the frog spinal cord preparation.

Shortly after I got to UCSF, a very bright graduate student, Craig Jahr, asked if he could join my lab, and, after overcoming some internal anxiety about taking on this major responsibility, I agreed, and Craig became my first student. It was a great decision, and Craig was soon making excellent progress in working up an in vitro preparation of the turtle olfactory bulb. The turtle bulb was closer, but still not quite the warm-blooded brain preparation, that neuroscience was after.

Some years earlier, two papers appeared from Per Andersen’s lab in Oslo. The first by Skrede and Westgaard (1971) showed that one could make transverse slices of the guinea pig hippocampal formation, maintain them in vitro for hours, and record field potentials from them. The second paper by Schwartzkroin (1975) showed that one could stably record intracellularly from pyramidal cells in the slices and replicate all of the findings that previously had been made with intracellular recording from anesthetized animals by Kandel and Spencer (Kandel et al. 1961). With this slice preparation, one could now do experiments as elegant as those being carried out in invertebrate models and yet could be recording from the real thing—mammalian cortical tissue! Upon my arrival at UCSF, my number one goal was to set up the hippocampal slice preparation, but by the mid-1970s, there were still only a handful of laboratories in the world that had the slice preparation working, and I had no direct access to any of them. Fortunately, Brad Alger had written to me about working in my lab. He was completing his PhD in Tim Tyler’s lab at Harvard using field potentials in the hippocampal slice. He wanted to learn how to do intracellular recording and wondered whether I might be interested in getting the slice preparation. I was, and it was off to the races. Given that we knew virtually nothing about the neurotransmitters in the brain, there was a ton of low-hanging fruit. I consciously decided not to study excitatory synaptic transmission and glutamate. First, a great deal of work had been done characterizing the excitatory action of ACh at the neuromuscular junction, and it seemed to me that, although the receptors–transmitters might be different in the brain, the ionic mechanism would be similar. Second, the pharmacology of excitatory amino acids was in its infancy, and there was no solid evidence that glutamate was, in fact, a transmitter in the brain. I was more interested in GABA, which had been shown to be a transmitter at the crustacean neuromuscular junction and was present in very high amounts in the brain.

GABA and Synaptic Transmission

As discussed earlier, my initial interests were in understanding the role of GABA in inhibitory synaptic transmission. This involved identifying somatic and dendritic inhibitory pathways in the hippocampus (Alger and Nicoll 1982) and the role of GABA in dendrodendritic inhibition in the olfactory bulb (Jahr and Nicoll 1982). Remarkably, in one of our first efforts, we found that the opioid peptide encephalin selectively reduced synaptic inhibition in the spinal cord, olfactory bulb, and hippocampus (Nicoll et al. 1980), a previously unsuspected unity, which also demonstrated the power of the in vitro approach. During these studies, we noted that the action of GABA antagonists was complex. Although the antagonists clearly reduced the IPSP, there was a slower component that actually increased in size (Newberry and Nicoll 1984a). Furthermore, this component was not mediated by an increase in chloride conductance. Detailed studies indicated that it was mediated by an increase in potassium conductance (Newberry and Nicoll 1985). What was responsible for this slow IPSP? The fact that it actually increased in the presence of GABA antagonists, which greatly enhance the excitability of interneurons, suggested that it might be mediated by the interneurons. This notion was further supported by the finding that enkephalins, which selectively silence interneurons, also reduced the slow IPSP (Newberry and Nicoll 1984a). During this period, Norman Bowery published a series of truly elegant papers showing that GABA had a presynaptic inhibitory effect that was not blocked by GABA antagonists and that baclofen was an agonist at this receptor. He termed this new receptor the GABAB receptor and termed the classical receptor the GABAA receptor. Remarkably, we found that baclofen activated a potassium conductance in pyramidal cells (Newberry and Nicoll 1984b, 1985) and that this effect was mediated via G-proteins (Andrade et al. 1986). Finally, the moment that a GABAB receptor antagonist became available, we showed that this antagonist selectively blocked the slow IPSP (Dutar and Nicoll 1988). GABAA and GABAB receptor signaling provides a fascinating example of how profoundly different the signaling properties of two receptors, activated by the same transmitter, can be. GABAA receptors are primarily synaptic, low affinity, and fast, and they convey highly reliable point-to-point signaling. In striking contrast, GABAB receptors are extrasynaptic, high affinity, and slow, and they require high-frequency synaptic activation or the activation of multiple neighboring synapses, thus allowing for spillover and for “pooling” of GABA. This “diffuse” action of GABA on GABAB receptors is strongly controlled by GABA uptake (Isaacson et al. 1993).

Neuromodulation

I was also fascinated by such “peripheral” transmitters as NE, ACh, serotonin, and dopamine. Although present in the brain, how they exerted their actions there was a complete mystery. The advantage to examining these transmitters was that they each had a very rich pharmacology of agonists and antagonists. With Dan Madison, my second graduate student, I decided to look at the action of NE in the hippocampus. The application of NE caused a highly variable and modest hyperpolarization of pyramidal cells—rather underwhelming. We wondered whether it affected excitatory synaptic transmission and decided to mimic excitatory synaptic actions by iontophoresing glutamate onto the cells. Much to our amazement, pulses of glutamate, that only elicited a couple of spikes normally, evoked a train of high-frequency spikes in the presence of NE (Madison and Nicoll 1982). We showed that this profound effect was due to NE blocking a calcium-activated potassium current (IAHP), which normally provides a break to repetitive action potential firing. Interestingly, we found that the response to a barely suprathreshold ramp depolarization was blocked by the direct NE-induced hyperpolarization, while at the same time, the response to a step depolarization was greatly enhanced (Madison and Nicoll 1986). We concluded that NE greatly enhances the signal-to-noise ratio, suppressing weak signals and enhancing strong signals. We attempted to duplicate this action of NE by stimulating NE containing fibers in the slice. Indeed, stimulating the slice resulted in a blockade of IAHP. Disappointingly, NE antagonists failed to block this effect, but we later found that ACh muscarinic receptor antagonists did block it (Cole and Nicoll 1983). ACh has the same effect as NE on IAHP, but it uses a different second messenger pathway. The elucidation of the actions of NE, ACh, serotonin, and dopamine kept me busy for a good decade. These studies revealed that different neurotransmitter receptors that use either the same or different coupling mechanisms converge onto the same ion channel. Conversely, virtually all neurotransmitters act on more than one distinct receptor subtype, coupled to different ion channels in the same cell. Thus, the existence of both convergence and divergence in neurotransmitter action results in a remarkable diversity in neuronal signaling (Nicoll 1988).

LTP

Despite the continued allure of GABA and the other neurotransmitters, my attention was increasingly being drawn to an area in neuroscience that I had steadfastly ignored. Based primarily of the work of Jeff Watkins, the pharmacology of excitatory amino acids was blossoming. It was also abundantly clear that excitatory synaptic transmission was not, as I had erroneously concluded from the motoneuron excitatory drive of muscle, simply a stereotypic way of depolarizing the cell. Instead, multiple glutamate receptor subtypes provided a remarkable richness in neuronal communication. Most important was the discovery of LTP (Lomo 1966; Bliss and Lomo 1973). This was certainly the most extraordinary synaptic behavior that I have encountered in my career. And the fact that it had all the hallmarks expected for the cellular basis for learning and memory did not escape my attention or that of others. Nevertheless, it is interesting to note that it took approximately 10–15 years after the discovery of LTP before a mechanistic understanding of the phenomenon began to emerge. The reason for the long delay after the discovery is threefold. First, initially, the pharmacology was extremely poor and it wasn’t even clear that glutamate was the transmitter at these excitatory synapses. Second, one was greatly constrained in the types of experiments that could be done in vivo. Third, LTP was irreversible; once the effect occurred, that was it; it seemed that the only way to study it would be to do group studies, comparing a set of control slices to experimental ones, and analyze the results statistically. This approach was anathema to me, especially because of the large variability in the magnitude and even the occurrence of LTP; I wanted to be able to tackle problems more directly. The irony is that Brad Alger was one of the first to demonstrate long-term potentiation in the slice and is credited with the first use of the acronym LTP (Alger and Teyler 1976). We had many discussions about LTP, but in the absence of any knowledge about the pharmacology of excitatory synapses, we were unable to come up with any interesting experiments. Perhaps LTP is the field that I am most associated with. I recently reviewed the history of LTP describing all of its twists and turns, and my participation in many of them (Nicoll 2017).

Here I will highlight a few of events that had the biggest impact on me. When I entered the field, it was established that LTP initiation required the activation of postsynaptic N-methyl-D-aspartate (NMDA) receptors. However, there was much debate on how LTP was expressed: What actually changed at the synapse? Was the increase in synaptic strength due to a postsynaptic modification or, alternatively, to an increase in the release of glutamate? The latter mechanism would necessitate a retrograde factor, because it was established that postsynaptic NMDA receptor activation was required. We published a paper with the provocative title “A Persistent Postsynaptic Modification Mediates Long-Term Potentiation in the Hippocampus” (Kauer et al. 1988) in which we showed that LTP is expressed primarily as an increase in alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA) receptor responses compared with NMDA receptor responses. We argued, and showed experimentally, that increasing synaptic glutamate release by post-tetanic potentiation caused an identical increase in both components. These findings pointed to a selective postsynaptic modification of AMPA receptor transmission during LTP. Gary Lynch published a paper in the same year with similar results and conclusions (Muller et al. 1988). Although there was some debate as to whether there was any change at all in the NMDA component, all subsequent studies have confirmed that LTP is primarily expressed on the AMPA receptor component. It seemed to me that these experiments had very little wriggle room for a presynaptic expression mechanism.

Nevertheless, within little over a year after publishing the paper with Kauer and colleagues, two other papers appeared in Nature, one by Dick Tsien, entitled “Presynaptic Mechanism for Long-Term Potentiation in the Hippocampus” (Malinow and Tsien 1990) and one by Chuck Stevens entitled “Presynaptic Enhancement Shown by Whole-Cell Recordings of Long-Term Potentiation in Hippocampal Slices” (Bekkers and Stevens 1990). Both papers examined the probabilistic trial-to-trial fluctuation in transmitter release, including examination of the “failure” rate, before and after LTP. They elegantly showed that both the fluctuation and the failure rate decreased following LTP. Based on the classical studies of Del Castillo and Katz at the neuromuscular junction (NMJ), these results seemed to definitively establish a presynaptic modification, the opposite conclusion from mine. These papers were devastating. How had I screwed up? It seemed as if I had a 50:50 chance and blew it. The evidence in these experiments was compelling and was immediately embraced by the neuroscience community. By far the lowest point in my scientific career was a Cold Spring Harbor meeting that took place from May 31 to June 6, 1990. Although their papers had not yet appeared in Nature, everyone was aware of their findings, so there was a lot of buzz. I had decided to talk about something unrelated to LTP—to get as far away from LTP as possible. Much to my chagrin, I discovered at the beginning of the meeting that Dick, Chuck, and I were included in one session. It was clear that I had to say something about LTP. I had brought no slides on LTP, so I went to the library and made a few overheads of figures from my papers in an attempt to explain how I had reached my conclusions. I followed their two talks. Their talks were universally acclaimed as the highlight of the meeting. After my talk, I literally picked up my bags, left the auditorium, went to the train station, and took the train to Princeton to recover with my parents.

There is more to this story. Dick and Chuck were the rising stars in neuroscience. Dick had attended MIT, majoring in electrical engineering and went to Oxford as a Rhodes Scholar, where he carried out quantitative biophysical studies on cardiac pacemaking currents. He had recently completed a series of truly elegant studies defining the subclasses of calcium channels. Chuck graduated from Harvard, obtained an MD from Yale and then a PhD from the Rockefeller University. Among a number of landmark studies, he had applied voltage clamp analysis of ACh-induced fluctuations at the neuromuscular junction to infer the conductance of single Ach receptors and their kinetic properties. They were both highly respected for their quantitative rigor. I found them both overwhelmingly intimidating. They brought to the surface all my childhood feelings of inadequacy. At the time, they were both at Yale University. Much to my horror, Chuck became interested in the hippocampus and recruited my first graduate student Craig Jahr to join his lab. This horror was compounded when Dick soon after recruited my second graduate student Dan Madison to do postdoctoral work in his lab. I was certain that it was only matter of time before I was exposed as a lightweight. I was a nervous wreck. When the two Nature papers appeared, my worst nightmare had come true.

My first reaction was to admit defeat and move as far away from LTP, Dick, and Chuck as possible. On reflection, however, I really had no choice other than to find out where I had gone wrong; not to do so would have been an admission that somehow my papers were simply wrong. LTP became an obsession—I could not get it out of my mind. There must be an answer to this conundrum—both positions could not be true. So the very first experiments were to see whether we could repeat the basic results presented in the two Nature papers. These results were quickly repeated (Kullmann and Nicoll 1992; Manabe et al. 1993); thus, the findings were unimpeachable. The bottom line is that both sets of data, that is, the preferential enhancement of the AMPA component during LTP and the decrease in failures, are correct. This immediately elevates the discussion to a higher plane because, all too often, the argument degenerates into a failure to replicate. However, one must face the fact that one of the conclusions must be wrong. Which one and why? During this period, my close colleague David Julius had, in my absence, modified my screen saver to repeatedly flash, “It’s presynaptic!”

At this time there were many studies, many of them my own, that implicated a postsynaptic mechanism for the expression of LTP, reviewed in (Nicoll 2003)—the only generally accepted evidence for a presynaptic change involved the change in “failure rate,” the frequency that a stimulus did not evoke a synaptic response. Therefore, I designed a number of experiments as alternative approaches to directly interrogate the release of glutamate during LTP (Manabe et al. 1993; Manabe and Nicoll 1994; Luscher et al. 1998). Despite the high sensitivity of these assays, we came up empty-handed; we could find no direct evidence that glutamate release was actually facilitated. The most definitive series of experiments for me was entitled “Long-Term Potentiation: Evidence Against an Increase in Transmitter Release Probability in the CA1 region of the Hippocampus” (Manabe and Nicoll 1994), which involved the drug MK-801, a use-dependent irreversible NMDA receptor antagonist. When glutamate is released, it opens NMDA receptors, and MK-801 immediately enters and irreversibly blocks the pore of these activated receptors. Repeated activation of the synapses results in a gradual decrease in the size of the NMDA receptor current and, most important, the rate of this decrease is dependent on the amount of glutamate that is released per stimulus. If LTP was expressed by an increase in the release of glutamate, we should see an increase in the rate at which MK-801 enters and blocks the channels at synapses that had undergone LTP compared with unpotentiated synapses. Yet, despite the exquisite sensitivity of this assay, we could detect no change in the amount of glutamate released during LTP. We summarized our findings as follows: “How can the present results be reconciled with studies using quantal analysis? The decrease in failures is usually interpreted as an increase in Pr (probability of release). Alternatively, the decrease in failures could reflect the appearance of patches of functional AMPA receptors on the postsynaptic cell.” Within a year, we (I was now collaborating with Rob Malenka) were able to provide experimental evidence for the presence of “silent synapses” that were converted to active synapses during LTP (Isaac et al. 1995). Remarkably, a substantial number of hippocampal synapses are normally silent, in the sense that there are no functional AMPA receptors, although they do contain a normal complement of NMDA receptors, whose electrical activation cannot be detected at resting membrane potentials. Thus, from an electrical point of view, such a synapse is “silent.” LTP rapidly unsilences these synapses with the all-or-none insertion of a population of AMPA receptors. Identical findings were reported by Malinow and colleagues (Liao et al. 1995) as well as by many other subsequent studies. With this new insight into the basic physiology of hippocampal synapses, we were able to provide a postsynaptic explanation for the decrease in failures of synaptic transmission, which had been the only apparently direct evidence for a presynaptic change. These findings quickly swayed public opinion back to the postsynaptic side of the synapse. Since the publication of these findings, virtually all the work on NMDA receptor-dependent LTP has focused on the nature of the postsynaptic modification. Thus, although the pathway to this conclusion seemed torturous and was bewildering, the answer as to the site of LTP expression turned out to be quite simple. The data on both sides of the argument were correct. It was the interpretation of the data that had to be modified, which had to await new insight into basic properties of hippocampal excitatory synapses. This is a saga of science at its best.

With the evidence that the increase in the number of functional AMPA receptors is the dominant mechanism in LTP, attention has shifted to the underlying mechanisms that control synaptic AMPA receptor trafficking. I remain disputatious. AMPA receptors in CA1 pyramidal cells are composed of heterotetramers of the subunits GluA1-3. It has long been held that both basal synaptic transmission and LTP are dependent on the subunit composition of the AMPA receptor (Malinow and Malenka 2002; Huganir and Nicoll 2013). Specifically GluA1-containing receptors are excluded from the synapse and require LTP for their insertion (Hayashi et al. 2000; Shi et al. 2001). We took a genetic approach to address this issue by systematically deleting these subunits in conditional knockout (KO) mice, either individually or together (Lu et al. 2009). With this approach, we could delete all endogenous AMPA receptors by generating mice in which GluA1-3 were floxed and then by replacing the endogenous receptors with genetically modified subunits (Granger et al. 2013). Much to our surprise, we found that homomeric GluA1 receptors trafficked to the synapse constitutively. Furthermore, we could find no subunit specificity to either basal or activity-dependent AMPA receptor trafficking. In fact, expression of a kainate receptor, which has limited homology with AMPA receptors and is not normally expressed at these synapses, showed normal LTP. Thus, in contrast to prevailing opinion, LTP appears to be quite promiscuous. So once again we are confronted with two seemingly incompatible observations. The only difference between our experiments and the previous ones was that the previous experiments used subunits in which GFP was inserted in the extracellular amino terminal domain (ATD), whereas we used untagged receptors. Remarkably, the presence of GFP on GluA1, but not GluA2, prevents basal trafficking, but LTP overcomes this inhibitory effect of GFP (Diaz-Alonso et al. 2017). Thus, once again, we could repeat all of the previous findings and provide an explanation for the differences.

There are many outstanding and intriguing questions in this field. What is the glue at the postsynaptic density (PSD) that captures and holds AMPA or kainate receptors at the synapse? Presumably, these receptors have something in common that is recognized by proteins in the PSD. Perhaps the most important unresolved issue in the field of LTP is the mechanism underlying its persistence, that is, the memory. It is this property that makes LTP such an attractive model for a cellular substrate for memory. Calcium-calmodulin kinase II (CaMKII) has received the most attention, but there remain many seemingly conflicting observations. Stay tuned!

Endocannabinoids

During the 1990s, I became intrigued with a curious discovery that Brad Alger had made in the hippocampus, which he termed depolarization-induced suppression of inhibition (DSI; Pitler and Alger 1992). Since leaving my lab, Brad had continued to work on GABA-mediated synaptic inhibition. On the basis of a series of meticulous experiments, he had clearly established that DSI was induced by depolarization of the postsynaptic cell but was expressed as an inhibition of GABA release. This was extremely interesting because it was the first compelling example of retrograde transmission, in which a signal was released from the postsynaptic cell and traveled backward to act on the presynaptic terminal. A great deal of discussion and many claims were embedded in the literature about retrograde factors and LTP. This reached a fever pitch with LTP and NO. In my lab, we could find no support for any involvement of NO in LTP, and I was quite sour about the concept of retrograde transmission in general. However, with DSI we had a very simple phenomenon, which unequivocally involved retrograde transmission.

I found DSI irresistible, and Rachel Wilson, a student in my lab, decided to examine this robust phenomenon in detail (Wilson and Nicoll 2001). Rachel first carried out a series of experiments characterizing some of the intriguing properties of DSI. By recording from pairs of nearby pyramidal cells, she found that the spread of DSI was spatially restricted to about 20 μm from the originating cell. She also found that uncaging Ca⁺² induced DSI, but that the action of Ca⁺² did not involve a classic SNARE-based exocytotic process. Around this time I visited the University of Washington, and I met with my former student Jeff Isaacson, who was then a postdoc in Bertil Hille’s lab. He was studying dendrodendritic inhibition in the olfactory bulb and had demonstrated that glutamate could spill over from excitatory synapses in the olfactory bulb. I had a chat with him, and out of the blue, he asked me what I thought of DSI. This caught me totally by surprise, because DSI was at that time rather obscure. He was about to start talking about it, and I immediately stopped him, telling him that I was actually working on DSI and felt uncomfortable exchanging information at that point. I left that meeting wondering why Jeff was thinking about DSI at all, but decided that it was due to his interest in glutamate spillover. One of the ideas in the DSI field was that glutamate was released from the pyramidal cell and acted on presynaptic metabotropic glutamate receptors on inhibitory terminals, and I satisfied myself that this was the connection that Jeff was making. Rachel and I continued our studies on DSI, and Rachel nailed down a number of key steps. She also tried several possible candidate chemical messengers that might mediate DSI, as the holy grail of this project was the identification of the retrograde factor. At about this time, Jeff passed through the Bay Area on his motorcycle and arrived at my door unannounced. We started chatting about all sorts of things, and then he brought up our previous discussion about DSI. He told me his interest in DSI had been sparked by some immunohistochemical results that Ken Mackie had presented in one of Hille’s lab meetings. Ken had an antibody for the CB1 cannabinoid receptor, the main brain receptor for the active constituents of marijuana, and showed heavy labeling of the terminals surrounding the cell body of pyramidal cells. This piece of evidence had suggested to Jeff that an endocannabinoid might be involved in mediating DSI. I am embarrassed to confess that my knowledge of endocannabinoids was very limited. It is my recollection that Jeff had tried some direct experiments to test this idea, but without obtaining a definitive answer. Nevertheless, based on Jeff’s input, we ordered the CB1 antagonist AM251 and the CB1 agonist WIN55212-2. The antagonist completely blocked DSI. Furthermore, the CB1 agonist mimicked and occluded DSI. My goal for this project had simply been to identify the retrograde messenger, even if it turned out to be a boring molecule. However, the fact that the molecule had such unusual signaling properties, unlike any previously characterized neuronal signaling molecule, and that it helped to explain the cellular actions of marijuana in the brain was beyond belief.

The SfN meeting was fast approaching and Rachel had submitted an abstract describing her work on DSI, before the linkage to endocannabinoids had been made. We had submitted a full-length paper to Science describing the endocannabinoid story, but we had nothing in print that would establish our claim to priority for the discovery. Nevertheless, we decided to totally spill our guts and announce the story, even though the paper had not been accepted for publication. However, I felt that of all the papers I have published this one would be a slam-dunk. As Rachel was presenting her poster at the meeting, the word spread and she was soon inundated with attention; everyone there, it seemed, wanted to know the details. Shortly after the meeting, we received the decision from Science. The paper was rejected! We got the most maddening and disingenuous reviews I have received in my career: Reviewer 1: “This is a nice study that provides new information on the mechanisms underlying DSI … While the results are compatible with this proposal, I cannot agree with the authors when they imply that their evidence is conclusive.” Reviewer 2: “The manuscript presents an intriguing premise… . However, it is unclear whether alternative explanations for the results can be entirely eliminated.” Reviewer 3: “The major merit of the paper is that the authors provide experimental data indicating that cannabinoids are the most likely agent responsible for the induction of DSI… . Nevertheless, the significance of these results for the function of the nervous system remains unclear… . Thus, while the paper contains useful results, I doubt that it is warranted to have it published in Science.”

We strongly suspected that our paper had been reviewed by people in the endocannabinoid field, who simply couldn’t accept the idea of total strangers stepping on their turf. Worst of all, we had let the cat out of the bag, informally publicizing our findings, and yet had no insurance that our priority would be properly acknowledged. We’d have to resubmit to another journal, but the delay meant that the paper would not appear in the year 2000. We immediately reformatted it for Nature and waited for what seemed like forever to hear back from them. It was now early 2001, and Dan Madison, now at Stanford, asked me about the status of our paper. He had been asked to write a commentary for two papers, one by Kreitzer and Regehr (2001) and the other by Ohno-Shosaku and colleagues (2001), to be published in Neuron on endocannabinoids and retrograde transmission at synapses in the cerebellum and the hippocampus, respectively. He was wondering whether we had anything in press that he could cite. We were about to be scooped. The reviews from Nature arrived and two of the reviews were very positive, but the third reviewer said that Alger had published evidence that glutamate was the retrograde factor and so who was she or he to believe? By this time, Brad had repeated the CB1 antagonist experiments and had backed away from glutamate, so I asked him if he would be willing to send me a letter summarizing his own position on DSI. He graciously provided a letter, which I forwarded to Nature. Finally, our paper found a home (Wilson and Nicoll 2001). What a harrowing experience. In an interesting footnote, all three papers, ours, Regehr’s and Kano’s, plus a theoretical paper by Elphick and Egertová (2001) proposing that endocannabinoids might be retrograde messengers, all appeared in print on the very same day, March 29, 2001, in three different journals. Although we may have missed a 2000 publication date, everyone got a piece of the pie, while broadly confirming and complementing each other’s findings (Wilson and Nicoll 2002).

TARPs

At around this time, Lu Chen from Richard Thompson’s lab inquired about joining my lab as a postdoctoral fellow. She showed me her data from the waggler/stargazer mutant mouse in which a putative neuronal calcium channel subunit was mutated (Chen et al. 1999). Stargazer was discovered as a spontaneous mutation resulting in a bizarre set of behavioral abnormalities characterized by distinctive head-tossing, an ataxic gait, and spike-and-wave seizures characteristic of absence epilepsy (Noebels et al. 1990). Some of the behavioral abnormalities were similar to those of other mutant mice, tottering and lethargic, harboring defects in genes encoding calcium channels, suggesting that the mutated protein in stargazer might be a calcium channel subunit. Indeed, the mutated gene was Cacng2 with structural similarity to the gamma auxiliary subunit of the skeletal muscle voltage-gated calcium channel (Letts et al. 1998). Although Cacng2 showed structural similarity to Cacng1 of skeletal muscle, the effects on calcium channel function are variable and modest.

Examination of the stargazer mouse by Masanobu Kano (Hashimoto et al. 1999) and Chen and colleagues (1999) revealed the most extraordinarily selective synaptic defect imaginable. Mossy fibers are the primary excitatory input to the cerebellum. They synapse on granule cells, which then form excitatory synapses on Purkinje cells via parallel fibers. In wild-type animals, the mossy fiber to granule cell synapse is a classical excitatory synapse activating both AMPA and NMDA receptors; however, in this mutant mouse, the AMPA component was entirely missing, but the NMDA component was normal: a genetic mutation that creates “silent synapses!” What an unbelievable gift of Nature. Remarkably, within the space of a year or so, Masanobu Kano and I both had stumbled onto endocannabinoids as retrograde messengers and the use of the stargazer mouse in elucidating AMPA receptor trafficking. Thus began a wonderful collaboration with David Bredt and the emergence of the role of transmembrane AMPA receptor regulatory proteins (TARPs) as auxiliary AMPA receptor proteins. Surprisingly, the studies on PSD-95 (El-Husseini et al. 2000; Schnell et al. 2002) and membrane-associated guanylate kinases (MAGUKs), which began in David’s lab, dovetailed perfectly with the study of TARPs, because it turned out that the MAGUKs’ role in trafficking AMPA receptors is mediated through its binding to TARPs (Nicoll et al. 2006).

Collaborations

I developed scientifically as a loner. All I needed was some space and equipment to do experiments. I asked nothing from those around me, nor did I expect anything from them. Whether I survived or failed was entirely up to me. In my opinion that’s the way it should be. It is the control of one’s own destiny that I found so empowering about science. Although I eventually became comfortable sharing my science with postdocs and graduate students in my lab, I did not collaborate with other colleagues for 13 years. I felt extremely uncomfortable at the possibility of losing any control over my science and the potential political conflicts over who did what. This issue of freedom has been a recurring theme throughout my career and all aspects of my life. Whenever I discuss science with a colleague, I am most sensitive to the colleague bringing something up that I am either working on or interested in working on. If this happens, as it did with Jeff Isaacson, I immediately interrupt the conversation and confess that the topic is too close to my own interests. What I most want to guard against is the possibility that a colleague could look back and feel that I had ripped him or her off. I was obsessed with being independent.

This all changed with Rob Malenka. He had spent a number of highly successful years as a postdoc in my lab. He then joined the psychiatry department at UCSF, which was awkward for me and, once again, brought up the issue of freedom and independence. Given my own obsession with controlling the science around me, the only arrangement that I felt I could live with was a complete separation; we would have no meaningful intellectual interactions at all. Needless to say, this was most uncomfortable for both of us. For instance, one of his students approached me to be on their thesis committee. I explained how this put me in a difficult position: If this project overlapped with what I was doing, then I would either have to give it up, which I was most reluctant to do, or enter into competition, which was also unacceptable.

Rob had established his own independence, producing a series of elegant papers on the mechanisms underlying long-term depression, a field in which I had never worked. Nevertheless, the tension between us was unhealthy. Rob was weighing an attractive offer from Stanford which would have completely severed our relationship, which had remained one of great mutual respect, and we finally sat down to confront the situation. We decided to essentially join our labs together. For someone who had avoided collaborations for so many years, this seemed totally out of character; however, the merger went well. There was twice as much data to chew on and twice as many people to work with. Also, and quite surprisingly, I found that this arrangement allowed me to finally relax. What I had worried most about with collaborations never occurred. Not once did we have a disagreement about authorship or credit. On projects that originated from Rob’s lab, he was senior author, and visa-versa. Rob was always very upfront in his interactions, and I was never caught by surprise. It was an extremely productive period; we collaborated on a total of 50 papers. My collaboration with Rob was pivotal to my science. We had just published our paper on silent synapses (Isaac et al. 1995), providing a compelling postsynaptic explanation for the changes in failure rate during LTP. Public opinion dramatically turned to a postsynaptic expression mechanism. Suddenly, LTP was now a receptor trafficking problem. However, neither Rob nor I had any knowledge about cell biology or molecular biology. So Rob initiated a collaboration with Mark Von Zastrow on the activity-dependent trafficking of tagged AMPA receptors. This collaboration drove the point home that to remain a competitive researcher in the field of LTP, it was essential to collaborate. Rob was again offered a very attractive package from Stanford and this time he could not refuse and decided to move. Since Rob had initiated the collaboration with Mark, future collaboration with me alone was not an option. I was in a state of panic.

It was during this period of crisis that I began talking with David Bredt. Eric Schnell, a student who transferred to my lab after Rob moved to Stanford, had done a rotation in the Bredt lab. He worked with Alaa El-Din El-Husseini, a postdoc in David’s lab and tagged PSD-95 with GFP. Alaa had found that expression of PSD-95 enhanced postsynaptic clustering of glutamate receptors and thus it was of interest to examine the physiological consequences (El-Husseini et al. 2000). This resulted in a long and exciting collaboration with David Bredt and members of his lab, focused largely on the role of TARPs and MAGUKs in AMPA receptor trafficking and function. After many highly productive years, David decided to try his hand at developing pharmaceuticals at Ely Lilly Co. Yet another marriage ending in divorce!

Also, around this time it was my good fortune that Katherine Roche at NIH expressed interest in the possibility of setting up some collaborations. Her focus on the role of protein phosphorylation nicely complemented my approach based on functional assays. Our studies on neuroligins are a great example of the interplay between these strengths (Shipman et al. 2011; Bemben et al. 2014). The study that stands out as one of the most complicated mysteries that I have ever encountered was the understanding of how the auxiliary AMPA receptor protein cornichon (CNIH) controls AMPA receptor trafficking and gating (Shi et al. 2010; Herring et al. 2013). Solving the mystery took us on a torturous, winding path that had many blind alleys. This study ended up with our generating CNIH2 and CNIH3 conditional KO mice, and the use of GluA1 KO mice, GluA2 KO mice, γ-2 KO mice, and γ-8 KO mice. Despite its enormous complexity, this turned out to be one of my more satisfying stories because, although so many pieces initially didn’t make sense, the role of CNIH appears to be rather simple: It is necessary for the selective forward transport of GluA1 out of the endoplasmic reticulum and is entirely consistent with its trafficking role in yeast and flies. Ironically, while this study is one of the ones that I am most proud of, it has basically fallen on deaf ears; the community at large has been slow to embrace it. Why some results are immediately accepted while others languish without attention is a puzzle that I have never solved.

Balance to a Life in Science

Family

While I was working at St. Elizabeth’s Hospital, I passed a woman in the hall carrying a couple of beakers. She was a new face, a postdoctoral fellow in a neighboring lab, so I started chatting with her. Diana had just arrived from London, and we hit it off very quickly. In three months, we were married. I owe an enormous amount to Diana, who had the onerous task of educating me and exposing me to everything outside of science. I was as opposite to “well rounded” as anyone could be. Somehow, I convinced her to relocate to Buffalo, a striking contrast to Washington, DC, and London. She completed medical school there, and we then moved to San Francisco. Diana has been at UCSF and the VA Medical Center for her entire career, where she has led as chief of staff for more than two decades. Unfortunately, after 18 years, our marriage ended in divorce. I take much of the responsibility for this, being consumed with my own scientific world while failing to provide the emotional bonding required of a relationship. I regret not having found the balance in life that would have made for a more successful marriage.

Despite these shortcomings of the past, Diana and I maintain a positive relationship sharing someone who is amazing, our son David. I was 40 years old and a full professor when he was born, so my career was fully established, and I was able to devote time to him. He was a gifted student, which was most exciting for me, given my own childhood academic problems. I was and am extremely proud of him, and like most parents, I enjoy vicariously his many successes. Much of the time I spent with him involved outdoor activities. Skiing was the most important sport that I introduced David to when he was just four years of age. We would regularly spend long weekends at Lake Tahoe during the winter. We skied at virtually all of the resorts in the area but settled on Squaw Valley both because of the variety and the challenge of the slopes. During the summer, we did a lot of hiking and some camping. As mentioned earlier, we had a family cottage in Canada, and when David was young, we would spend time there in the summers. So many activities to keep us busy—canoeing, swimming, water skiing, fishing, and hiking!

When Diana and I got divorced, we both agreed that David was the most important part of our lives, and we shared equally in bringing him up. We protected him from any issues that the two of us might have had. He went to the East Coast to university and worked in hedge funds for a number of years in New York City and Boston. Much to our delight, he moved back to the Bay Area and is married to a wonderful woman, Patricia, with whom he has two fantastic sons, Andrew, who is five, and Edward, who is three. Now that David and his family are back in the Bay Area, Diana and I spend time together sharing in the joy of having grandchildren.

More than 20 years ago, I met a very engaging woman on the public tennis courts. JoAnn Blomgren and I have been very close ever since. Aside from tennis, which we play virtually every weekend of the year, we have many things in common and enjoy being together. It never ceases to amaze me as to how she can put up with all of my idiosyncrasies. She is a very forgiving person and has brought me much pleasure and comfort.

Sports

Sports have played a central role throughout my life. I played the usual sports—soccer, basketball, and baseball in grade school—but was only average in these team sports. I preferred solo sports.

Pole vaulting: During my first year of high school, the math teacher, who was the football coach and the track coach, suggested that I should try pole vaulting. I had never met this teacher, although my older sister was a favorite student of his, and I hadn’t a clue as to what pole vaulting was all about. I decided to give it a try. Pole vaulting is not easy. To be perfectly honest, my goal during the first year was to clear a height that was higher when using a pole than when not. One of the more humiliating moments during that first year was when the baseball practice on the neighboring field had finished and one of the baseball players was walking by and asked if he could try out my pole. He picked up the pole, and holding it improperly, ran down the runway and cleared a height that was beyond what I was capable of doing at the time. Afterward he picked up his baseball mitt, said thanks, and ran off. So why did I keep pole vaulting through high school and college? My father was not very encouraging and felt that I should pick up a sport that I could enjoy for the rest of my life. Yet I persevered. It appealed to me in the way that many things did: The only explanation I can come up with is that the goal is very simple, and you can track your progress precisely. As the Russian Sergey Bybka, arguably the greatest pole vaulter of all time, said, “I love the pole vault because it is a professor’s sport. One must not only run and jump, but one must think… . I love it because the results are immediate and the strongest is the winner.” The other benefit, perhaps not as lofty, is that it was not a popular sport. This, I suspect, was the reason that the coach approached me about pole vaulting in the first place. Anyway, depending on the track meet, there were either three or five ribbons and medals awarded, and quite often, there would be fewer contestants than there were medals. So all I had to do was clear the first height to be assured a medal of some kind. The first height was decided by the contestants and had to begin with the lowest height requested. The others could pass the low heights if they felt it was beneath them. I never took a bye and always made my first height. Now it should be clear as to why I had a drawer full of medals. Interestingly, Eccles had also been a pole vaulter in college. He never confessed to his highest height, and you may have noticed that this piece of information is missing from my summary as well.

Skiing: Skiing was my real passion. I started skiing when I was about four years old. My father had obtained old skiing equipment at a rummage sale. It was rudimentary, but it allowed us to go out in the fields behind the house and do primarily cross-country skiing. There were, however, a few gentle slopes, which gave me a taste of the thrill of downhill. When I was around 7 to 10 years old, there were a few special occasions when I got to go to a hill called Peapack about 30 miles north of Princeton. This was normally a pasture, but the farmer had installed a rope tow that was powered by an old truck engine. They had night skiing with floodlights. When it snowed hard, we would have to put snow chains on our car tires to get to Peapack. All I can remember was that this hill was unbelievably daunting—it seemed so steep. Years later when we would drive by this hill, it was hard to imagine how I could have felt the way I did. It was certainly not above the grade of novice. At some point, the farmer stopped setting up the rope tow. Eventually, many years later, other places like Great Gorge in northern New Jersey and Camelback in Pennsylvania came into being. When I was a bit older, the family would go on skiing vacations to New England. We would stay in Albany with friends of my parents and ski at local places. This included Bousquet Ski Area, which is still going strong, but other areas didn’t fare so well. For instance, Dutch Hill was a favorite place in southern Vermont. It closed in 1985, and many years later, there was an article in the sports section of the New York Times on the demise of New England’s small ski resorts. There was a picture of the old rusted chair lift still standing at Dutch Hill—very sad. During high school, I never missed a winter without a trip to New England, and I have been to the vast majority of the New England ski resorts since.

One of the activities at the top of the list for my son David was skiing. Lessons started when he was four. At first, I would put him into a ski school in the morning and then ski with him in the afternoon. However, this didn’t last long. He gave me an ultimatum. Either we skied together, or he wasn’t interested. David eventually developed into a fantastic skier, far better than I am. We’d spend all our time on Double Black Diamond slopes with huge moguls. I would always push myself to the limit and although falling more often than most skiers, I rarely got injured. I loved the challenge. My other favorite type of skiing was powder on wide-open slopes or glades. There are few moments in life that can beat a day of skiing in deep, fluffy powder and the feeling of floating and freedom that you get. Unfortunately, of all the sports I enjoy, skiing is the one that is most affected by aging. I just no longer have the reflexes or strength to link the moguls together and thus fear has, appropriately, crept in and taken the fun out of it.

Tennis: One thing that I regret is not taking up tennis when I was young. My father played doubles every once in a while, but he did not really encourage us to play tennis, unlike other sports. It wasn’t until I moved to Marin County, California, that I became obsessed with the sport. I took lessons and joined a tennis club and U.S. Tennis Association teams. I had a very unorthodox style of play. For starters, my groundstrokes were not all that reliable. Thus, I developed a very aggressive style of play that involved serve and volley and rushing the net when receiving serve. At the level that I was playing, this usually caught my opponent off guard. The trick was to get the match over with before he could adjust. As a result, I could often beat players who were considerably more skillful than I. It would drive them crazy. Unfortunately, if they did catch onto my game, the result was most embarrassing. I would look like a fool, rushing the net and repeatedly being passed. Nowadays, all I play is doubles, which lends itself to my style of tennis, since controlling the net is critical.

Sailing: When growing up I did a lot of sailing with my father. He bought a used “Penguin” international class of dingy (11 foot). It used to be the third largest international class of boat. What made it popular was that you could buy a kit with all the plywood pieces cut and assemble it on your own. As a watercraft, it did not have many other attributes and it has been replaced by far better designed boats. However, the local sailing club had about 15 or so owners of Penguins and summer races were held every Sunday. When there was wind, the races could be very exciting, but when there was no wind, it was really boring. Crewing could also be boring. Thus, I negotiated with my father that we would alternate being skipper. There was one incident that I vividly remember. There was a big international regatta on the Barnegat Bay, by the ocean, with about 70 Penguins—so some of the top-ranked sailors in the world were there. One of the participants was Britton Chance, a famous biochemist from the University of Pennsylvania, who had won a gold medal in sailing at the 1952 Summer Olympics. He had named his boat the “Snark” and everybody knew it. In one of the races we were, not surprisingly, in the middle of the pack, when a boat approached on starboard. My father was sailing and we were on port, and he felt that he had enough time to get past the approaching boat. However, this forced the approaching boat to make a minor adjustment and the sailor on it unloaded a long barrage of obscenities at us. It was Britton Chance in the Snark. I am sure he felt frustrated having to share the middle of the pack with us and we had probably cost him a few seconds. My father and I both felt very small. Interestingly, his son Britton Chance Jr. became a renowned Naval architect who played a critical role in the design of a number of America’s Cup vessels.

In the winters, my father would skate-sail and bring me along. The sail consisted of two long large aluminum poles assembled in the form of a cross upon which the sail was rigged. My father made all of his hardware and sails from scratch. One of his sails was made with Army Surplus fluorescent pink signaling panels. This seemed so out of character; I guess there must have been a bit of the showboat in him. The sail would be positioned to windward, and the boom rested on your shoulder and leaned into the wind. Depending on the wind, one could reach outrageous speeds of about 50 mph. Unlike a sail boat, one could not control the force of the wind on the skate-sail, so if you got going so fast that you were on the verge of wiping out, the only recourse was to turn into the wind and hold the sail over your head. One could make very elegant jibes, turning down wind, because you were going much faster than the wind speed. There were three downsides to skate-sailing. First, speeding across the ice in freezing wind was really uncomfortable and, second, the pressure on your ankles, which took all of the force, was painful. For me, the pain would limit how long a reach I could endure. Finally, the skate-sailing season was unpredictable and short; it began when the ice on the lake was thick enough to skate, and ended with the first snowfall. We would regularly go to the lake and with an axe make a hole and measure the thickness. Maybe unsurprisingly, skate-sailing never really caught on as a sport and most of the images of it on the web date back to the first half of the last century.

During one of the summers early in high school, a friend of my father’s loaned us a Sailfish “boat” for the summer. It was a board-boat style and you sat on the surface. The Sailfish was a forerunner of the Sunfish, which ended up being far more popular. The Sunfish was larger and had a well on the deck for placing your feet. The wonderful thing about the Sailfish is that you were right on the water, and with a brisk wind, it would plane across the top of the water, which would really get your juices flowing. It was not all that stable, especially when pushing the limits, and so it would often capsize, although it could be quickly righted by standing on the center-board. On one of my outings, a photographer for the local newspaper the Princeton Packet took a series of photographs of me, which appeared in one of the summer editions, evidently a very slow time for news. To me, the Sailfish was the best experience one could have sailing—you were extremely close to the water, it was fast, you could plane (albeit infrequently), and if you went too close to the edge, you capsized—no big deal.

So fast-forward a few decades. As I would drive across the Golden Gate Bridge in the summers on my way home from work at UCSF, I would glance at the Bay and see these long streaks of white water. On closer inspection, it appeared that at the front of the streak was a human being; a windsurfer. Unbelievable! Here was a guy on a small board going faster than I was in my car. This was clearly a Sailfish on steroids. I identified the launching site, Crissy Field, and on the weekend went to see what was happening, and I was introduced to a totally different world. The language, not very intellectual, was devoted to the complexity of the gear, an obsession with every little minuscule detail of the wind, weather, tides, and how to decide on the sail size—it was all brand new. Observing the sailors (windsurfers call themselves “sailors”) approach the beach at high speed and then smoothly glide through a jibe was utterly mesmerizing. It was irresistible. I bought all the necessary gear, heavy wet suit, board, mast, boom, harness, and sails and headed out to Larkspur Landing, immediately next to San Quentin Prison. This is not far from my home and was the safest place in the Bay to learn how to windsurf. I would cross the channel to the other side where the water, depending on the tide, was between three and seven feet deep. It is here that I actually learned to windsurf. At first, it was extremely difficult for me, and the first season brought me little pleasure. What kept me going were the small incremental accomplishments and watching other sailors executing flawless planing jibes right in front of me. Since they could do it, I had to be able to! I slowly improved and graduated from a large board to a short board that barely floats when standing still.

Windsurfing is not just ripping across the water at 40 mph. You have to be able to turn around. This is not trivial on a board that barely floats. Jibing is what makes windsurfing such an exciting sport and it is how you judge the competence of a windsurfer. When done properly, the jibe is a thing of beauty. It is one continuous seamless series of steps in which you remain on a plane throughout and then off you go lickety-split in the opposite direction. It is very much like pole-vaulting where, in rapid succession, one step follows another, and they all have to be linked seamlessly together. I had a DVD on learning to jibe, and I would religiously watch it before going out. Then, after an afternoon session of failed or imperfect jibes, I would watch the DVD again in the evening. After watching it for hundreds of times, it finally gave out. The important point is that every once in a while, I completed what I thought was a perfect jibe and it is intoxicating—intermittent reward is a powerful reinforcer of behavior. This is what kept me going.

After a couple of seasons of sailing at Larkspur Landing, I was confident enough to sail at Crissy Field. I must confess that for a number of seasons, I felt a mixture of exhilaration and intense fear and anxiety. There was incessant boat traffic and huge container ships that cast enormous wind shadows as they approached—not good for staying upright on your board—and then there were ferries and fishing boats, which traveled at high speed and didn’t seem to care about what was in front of them, including windsurfers.

For many years, I sailed completely on my own. Although I would chat with some of the guys, I never teamed up with anyone. I was aware that Bob Stroud, a protein crystallographer and a colleague in the UCSF Biochemistry Department, was an avid windsurfer and was more advanced than I. I initially kept clear of him because I didn’t have the confidence to keep up. I finally got the courage to approach him, and we started to sail together. This was transformative for me. My confidence and skills increased enormously. Carrying a marine radio added tremendously to my comfort. The worst thing that could happen was suffering the humiliation of being rescued by the Coast Guard. This happened to me once when I broke my boom in the middle of the Golden Gate. For many years, a small group of us were sailing buddies. The group consisted of Bob Stroud; Jeff Blaney, director of computational chemistry and cheminformatics at Genentech; Jeff’s wife Leslie (the best sailor of the bunch); and Bill McCurdy, a physical chemist at the University of California, Davis. We would check in with each other in the early afternoon to decide on the best sailing site and then meet up a bit later. A particularly popular site is Crissy Field, where after launching, one sails up to the Golden Gate. Perhaps the most challenging site is off Treasure Island in the middle of the Bay. One launches directly into the full force of the wind. It was “off limits” for many years with four signs posted next to each other: “Sailboarding Prohibited,” “Warning Sudden Drop Off,” “Warning Strong Currents,” and “Warning Slippery Rocks.” Below each of these warnings was “Drowning Hazard.” Because it is such an ideal site, windsurfers ignore these prohibitions. After an afternoon of sailing, we would often end up having dinner together. For 25 years, weekends in the summer were occupied with tennis in the morning and windsurfing in the afternoon. On Mondays, I would be exhausted, and my body sore all over.

In the winter, when the wind shut down in the Bay, I took trips to windsurfing destinations, such as Baja, Mexico; Maui, Dominican Republic; and Ariel, Costa Rica. I eventually gave up traveling to far away places because one was entirely dependent on the weather and often ended up having a number of calm days with nothing to do. Also sailing from morning to evening is extremely exhausting.

What is it that makes windsurfing so exhilarating? It is for me the Platonic ideal form of sailing. You are as close to the water as you could possibly be—sometimes actually in it. This gives you an intense feeling of speed. With a short board, you are intimately interacting with the ever-changing surface, planning how to approach the water pattern in front of you. In addition, the wind is constantly changing. At every instant, you have to integrate the information from waves, chops, and swells, with the ever-changing wind speed. The output of this integration is transmitted to your feet, which guides the direction of the board, and to your arms, which controls the position of the sail. When a gust hits, you have to let the sail out to bleed the wind. This is the only time when I am conscious and yet my brain is completely freed of everything except for the moment before me. It is highly therapeutic. It clears out the cobwebs from my brain.

Reading, Music, and Art

The vast majority of my reading is devoted to scientific manuscripts. I do not read novels. The work that goes into reading a novel far exceeds any pleasure. The little nonscientific reading in which I engage is driven by the desire to learn something. Examples of books that I thoroughly enjoyed include Steve Jobs by Walter Isaacson, Fermat’s Enigma: The Epic Quest to Solve the World’s Greatest Mathematical Problem by Simon Singh, and The Making of the Atomic Bomb by Richard Rhodes.

Although I never learned to play a musical instrument, I fell in love with classical music early in college. I always had the classical music radio station on while I studied. This continued through medical school and during experiments. I also regularly have it on while driving the car. I like all kinds of classical music, but am particularly fond of chamber music and especially string quartets.

I have recently become smitten with modern glass blowing, thanks to a considerable degree to Mark Mayer. I have acquired a number of wonderful pieces by such artists as Tobias Mohl, Nancy Callan, J. P. Canlis, and Lino Tagliapietra that adorn my house. Lino is in a class of his own with unsurpassed technical and artistic skills. The DVD entitled The Time of Lino is inspirational. He is still going strong at age 83.

Mentorship and Legacy

My early obsession with going it alone immediately presented a problem as I set up my lab. It is expected that a new faculty member establish a research program and hire postdoctoral fellows and graduate students. The responsibility of having others depend on me made me feel uneasy. I did not feel at all confident that I had enough ideas to go around. It was the relentless badgering of a first-year graduate student, Craig Jahr, that finally made me cave in, and so began my doing science with others. I can’t think of anything more enjoyable about science than going over raw data with a student or postdoc and sharing in the excitement and the frustration associated with trying to understand what it all means. Ideas are thrown back and forth, forth and back; most of them go nowhere. But a few good ones pop up. The key is that the two of us are equals; there can be no hierarchy in the discussions. It is irrelevant as to who came up with the idea. What is important is to get as many ideas on the table as possible, because without this brainstorming, the clincher experiments will certainly never come up. I have to confess that, originally, part of the allure of science was the idea of discovering something great that would give me a degree of immortality. As I matured as a scientist, it became clear that the half-life of most discoveries, including my own, is rather short. Instead, one of the most exciting aspects of science is the realization that it is students and postdocs who will carry on long after your name dissociates from the discoveries. So, I finish with a list of the students and postdoctoral fellows who I have had the pleasure and privilege of working with. I thank you all for joining me in such an amazing journey. This autobiography is dedicated to you.

Craig Jahr

Bradley Alger

Martin Wojtowicz

Daniel Madison

Alison Cole

Nigel Newberry

Rodrigo Andrade

Robert Malenka

Barrie Lancaster

Patrick Dutar

Julie Kauer

Pankaj Sah

David Perkel

Robert Zalutsky

Jose Solis

Pius Renner

Jeffrey Isaacson

Dmitri Kullmann

Toshiya Manabe

Marc Weisskopf

David Wylie

Oliver Manzoni

Pablo Castillo

Massimo Scanziani

Paul Salin

Pierre-Marie Lledo

Gang Tong

Stephane Oliet

Steve Gomperts

Albert Hsia

Carl Peterson

Kaspar Vogt

Christian Luscher

Matthew Frerking

Qiang Zhou

Jack Mellor

Min Yi-Xiao

Rachel Wilson

Eric Schnell

Lu Chen

Dietmar Shmidt

Kimberly Moore

Kaiwen Kam

Nathalie Rouach

Valentine Stein

Karen Menuz

Hillel Adesnik

Guillermo Munoz

Aaron Milstein

Wei Zhou

Sandip Panicker

Anastassios Tzingounis

Seth Shipman

Kate Lovero

Jonathan Levy

Adam Granger

Wei Lu

Yun Shi

Carleton Goold

Alexander Jackson

John Gray

Sabine Blankenship

Mackinzie Howard

Bruce Herring

Nengyin Sheng

Argentina Lario

Yujiao Sun

Salvatore Incontro

Meryl Horn

Quynh Anh Nguyen

Samantha Esselmann

Wucheng Tao

Javier Diaz-Alonso

Michael Bemben

References

Alger, B.E., and Nicoll, R.A. (1982). Feed-forward dendritic inhibition in rat hippocampal pyramidal cells studied in vitro. J Physiol 328, 105–123.

Alger, B.E., and Nicoll, R.A. (1983). Ammonia does not selectively block IPSPs in rat hippocampal pyramidal cells. J Neurophysiol 49, 1381–1391.

Alger, B.E., and Teyler, T.J. (1976). Long-term and short-term plasticity in the CA1, CA3, and dentate regions of the rat hippocampal slice. Brain Res 110, 463–480.

Allen, G.I., Eccles, J., Nicoll, R.A., Oshima, T., and Rubia, F.J. (1977). The ionic mechanisms concerned in generating the i.p.s.ps of hippocampal pyramidal cells. Proc R Soc Lond B Biol Sci 198, 363–384.

Andrade, R., Malenka, R.C., and Nicoll, R.A. (1986). A G protein couples serotonin and GABAB receptors to the same channels in hippocampus. Science 234, 1261–1265.

Bekkers, J.M., and Stevens, C.F. (1990). Presynaptic mechanism for long-term potentiation in the hippocampus. Nature 346, 724–729.

Bemben, M.A., Shipman, S.L., Hirai, T., Herring, B.E., Li, Y., Badger, J.D., 2nd, Nicoll, R.A., Diamond, J.S., and Roche, K.W. (2014). CaMKII phosphorylation of neuroligin-1 regulates excitatory synapses. Nat Neurosci 17, 56–64.

Bliss, T.V., and Lomo, T. (1973). Long-lasting potentiation of synaptic transmission in the dentate area of the anaesthetized rabbit following stimulation of the perforant path. J Physiol 232, 331–356.

Cajal, R.S. (1989). Recollections of My Life. Cambridge, MASS, MIT Press,

Chen, L., Bao, S., Qiao, X., and Thompson, R.F. (1999). Impaired cerebellar synapse maturation in waggler, a mutant mouse with a disrupted neuronal calcium channel gamma subunit. Proc Natl Acad Sci USA 96, 12132–12137.

Cole, A.E., and Nicoll, R.A. (1983). Acetylcholine mediates a slow synaptic potential in hippocampal pyramidal cells. Science 221, 1299–1301.

Diaz-Alonso, J., Sun, Y.J., Granger, A.J., Levy, J.M., Blankenship, S.M., and Nicoll, R.A. (2017). Subunit-specific role for the amino-terminal domain of AMPA receptors in synaptic targeting. Proc Natl Acad Sci USA 114, 7136–7141.

Dutar, P., and Nicoll, R.A. (1988). A physiological role for GABAB receptors in the central nervous system. Nature 332, 156–158.

Eccles, J.C. (1957). The Physiology of Nerve Cells. Baltimore, MD, Johns Hopkins Press.

Eccles, J.C. (1964). The Physiology of Synapses. Berlin, Gottingen, Heidelberg: Springer Verlag.

Eccles, J.C., Nicoll, R.A., Schwarz, W.F., Taborikova, H., and Willey, T.J. (1975). Reticulospinal neurons with and without monosynaptic inputs from cerebellar nuclei. J Neurophysiol 38, 513–530.

Eccles, J.C., Schmidt, R.F., and Willis, W.D. (1963). Pharmacological studies on presynaptic inhibition. J Physiol 168, 500–530.

El-Husseini, A.E., Schnell, E., Chetkovich, D.M., Nicoll, R.A., and Bredt, D.S. (2000). PSD-95 involvement in maturation of excitatory synapses. Science 290, 1364–1368.

Elphick, M.R., and Egertová, M. (2001). The neurobiology and evolution of cannabinoid signalling. Philos Trans R Soc Lond B Biol Sci 356, 381–408.

Granger, A.J., Shi, Y., Lu, W., Cerpas, M., and Nicoll, R.A. (2013). LTP requires a reserve pool of glutamate receptors independent of subunit type. Nature 493, 495–500.

Hashimoto, K., Fukaya, M., Qiao, X., Sakimura, K., Watanabe, M., and Kano, M. (1999). Impairment of AMPA receptor function in cerebellar granule cells of ataxic mutant mouse stargazer. J Neurosci 19, 6027–6036.

Hayashi, Y., Shi, S.H., Esteban, J.A., Piccini, A., Poncer, J.C., and Malinow, R. (2000). Driving AMPA receptors into synapses by LTP and CaMKII: requirement for GluR1 and PDZ domain interaction. Science 287, 2262–2267.

Herring, B.E., Shi, Y., Suh, Y.H., Zheng, C.Y., Blankenship, S.M., Roche, K.W., and Nicoll, R.A. (2013). Cornichon proteins determine the subunit composition of synaptic AMPA receptors. Neuron 77, 1083–1096.

Huganir, R.L., and Nicoll, R.A. (2013). AMPARs and synaptic plasticity: the last 25 years. Neuron 80, 704–717.

Isaac, J.T., Nicoll, R.A., and Malenka, R.C. (1995). Evidence for silent synapses: implications for the expression of LTP. Neuron 15, 427–434.

Isaacson, J.S., Solis, J.M., and Nicoll, R.A. (1993). Local and diffuse synaptic actions of GABA in the hippocampus. Neuron 10, 165–175.

Jahr, C.E., and Nicoll, R.A. (1982). An intracellular analysis of dendrodendritic inhibition in the turtle in vitro olfactory bulb. J Physiol 326, 213–234.

Kandel, E.R., Spencer, W.A., and Brinley, F.J., Jr. (1961). Electrophysiology of hippocampal neurons. I. Sequential invasion and synaptic organization. J Neurophysiol 24, 225–242.

Kauer, J.A., Malenka, R.C., and Nicoll, R.A. (1988). A persistent postsynaptic modification mediates long-term potentiation in the hippocampus. Neuron 1, 911–917.

Kreitzer, A.C., and Regehr, W.G. (2001). Retrograde inhibition of presynaptic calcium influx by endogenous cannabinoids at excitatory synapses onto Purkinje cells. Neuron 29, 717–727.

Kullmann, D.M., and Nicoll, R.A. (1992). Long-term potentiation is associated with increases in quantal content and quantal amplitude. Nature 357, 240–244.

Letts, V.A., Felix, R., Biddlecome, G.H., Arikkath, J., Mahaffey, C.L., Valenzuela, A., Bartlett, F.S., 2nd, Mori, Y., Campbell, K.P., and Frankel, W.N. (1998). The mouse stargazer gene encodes a neuronal Ca2+-channel gamma subunit. Nat Genet 19, 340–347.

Liao, D., Hessler, N.A., and Malinow, R. (1995). Activation of postsynaptically silent synapses during pairing-induced LTP in CA1 region of hippocampal slice. Nature 375, 400–404.

Lomo, T. (1966). Frequency potentiation of excitatory synaptic activity in the dentate area of the hippocampal formation. Acta Physiol Scand 68, 128.

Lu, W., Shi, Y., Jackson, A.C., Bjorgan, K., During, M.J., Sprengel, R., Seeburg, P.H., and Nicoll, R.A. (2009). Subunit composition of synaptic AMPA receptors revealed by a single-cell genetic approach. Neuron 62, 254–268.

Luscher, C., Malenka, R.C., and Nicoll, R.A. (1998). Monitoring glutamate release during LTP with glial transporter currents. Neuron 21, 435–441.

Madison, D.V., and Nicoll, R.A. (1982). Noradrenaline blocks accommodation of pyramidal cell discharge in the hippocampus. Nature 299, 636–638.

Madison, D.V., and Nicoll, R.A. (1986). Actions of noradrenaline recorded intracellularly in rat hippocampal CA1 pyramidal neurones, in vitro. J Physiol 372, 221–244.

Malinow, R., and Malenka, R.C. (2002). AMPA receptor trafficking and synaptic plasticity. Annu Rev Neurosci 25, 103–126.

Malinow, R., and Tsien, R.W. (1990). Presynaptic enhancement shown by whole-cell recordings of long-term potentiation in hippocampal slices. Nature 346, 177–180.

Manabe, T., and Nicoll, R.A. (1994). Long-term potentiation: evidence against an increase in transmitter release probability in the CA1 region of the hippocampus. Science 265, 1888–1892.

Manabe, T., Wyllie, D.J., Perkel, D.J., and Nicoll, R.A. (1993). Modulation of synaptic transmission and long-term potentiation: effects on paired pulse facilitation and EPSC variance in the CA1 region of the hippocampus. J Neurophysiol 70, 1451–1459.

Muller, D., Joly, M., and Lynch, G. (1988). Contributions of quisqualate and NMDA receptors to the induction and expression of LTP. Science 242, 1694–1697.

Newberry, N.R., and Nicoll, R.A. (1984a). A bicuculline-resistant inhibitory post-synaptic potential in rat hippocampal pyramidal cells in vitro. J Physiol 348, 239–254.

Newberry, N.R., and Nicoll, R.A. (1984b). Direct hyperpolarizing action of baclofen on hippocampal pyramidal cells. Nature 308, 450–452.

Newberry, N.R., and Nicoll, R.A. (1985). Comparison of the action of baclofen with gamma-aminobutyric acid on rat hippocampal pyramidal cells in vitro. J Physiol 360, 161–185.

Nicoll, R.A. (1969). Inhibitory mechanisms in the rabbit olfactory bulb: dendrodendritic mechanisms. Brain Res 14, 157–172.

Nicoll, R.A. (1971). Pharmacological evidence for GABA as the transmitter in granule cell inhibition in the olfactory bulb. Brain Res 35, 137–149.

Nicoll, R.A. (1972). The effects of anaesthetics on synaptic excitation and inhibition in the olfactory bulb. J Physiol 223, 803–814.

Nicoll, R.A. (1988). The coupling of neurotransmitter receptors to ion channels in the brain. Science 241, 545–551.

Nicoll, R.A. (1997). John C. Eccles (1903–1997). Science 277, 194.

Nicoll, R.A. (2003). Expression mechanisms underlying long-term potentiation: a postsynaptic view. Philos Trans R Soc Lond B Biol Sci 358, 721–726.

Nicoll, R.A. (2017). A brief history of long-term potentiation. Neuron 93, 281–290.

Nicoll, R.A., Alger, B.E., and Jahr, C.E. (1980). Enkephalin blocks inhibitory pathways in the vertebrate CNS. Nature 287, 22–25.

Nicoll, R.A., Eccles, J.C., Oshima, T., and Rubia, F. (1975). Prolongation of hippocampal inhibitory postsynaptic potentials by barbiturates. Nature 258, 625–627.

Nicoll, R.A., Tomita, S., and Bredt, D.S. (2006). Auxiliary subunits assist AMPA-type glutamate receptors. Science 311, 1253–1256.

Noebels, J.L., Qiao, X., Bronson, R.T., Spencer, C., and Davisson, M.T. (1990). Stargazer: a new neurological mutant on chromosome 15 in the mouse with prolonged cortical seizures. Epilepsy Res 7, 129–135.

Ohno-Shosaku, T., Maejima, T., and Kano, M. (2001). Endogenous cannabinoids mediate retrograde signals from depolarized postsynaptic neurons to presynaptic terminals. Neuron 29, 729–738.

Pitler, T.A., and Alger, B.E. (1992). Postsynaptic spike firing reduces synaptic GABAA responses in hippocampal pyramidal cells. J Neurosci 12, 4122–4132.

Platt, J.R. (1964). Strong inference: certain systematic methods of scientific thinking may produce much more rapid progress than others. Science 146, 347–353.

Ramon y Cajal, S. Recollections of My Life (MIT Press, Cambridge, Mass., 1989)

Schnell, E., Sizemore, M., Karimzadegan, S., Chen, L., Bredt, D.S., and Nicoll, R.A. (2002). Direct interactions between PSD-95 and stargazin control synaptic AMPA receptor number. Proc Natl Acad Sci USA 99, 13902–13907.

Schwartzkroin, P.A. (1975). Characteristics of CA1 neurons recorded intracellularly in the hippocampal in vitro slice preparation. Brain Res 85, 423–436.

Shi, S., Hayashi, Y., Esteban, J.A., and Malinow, R. (2001). Subunit-specific rules governing AMPA receptor trafficking to synapses in hippocampal pyramidal neurons. Cell 105, 331–343.

Shi, Y., Suh, Y.H., Milstein, A.D., Isozaki, K., Schmid, S.M., Roche, K.W., and Nicoll, R.A. (2010). Functional comparison of the effects of TARPs and cornichons on AMPA receptor trafficking and gating. Proc Natl Acad Sci USA 107, 16315–16319.

Shipman, S.L., Schnell, E., Hirai, T., Chen, B.S., Roche, K.W., and Nicoll, R.A. (2011). Functional dependence of neuroligin on a new non-PDZ intracellular domain. Nat Neurosci 14, 718–726.

Skrede, K.K., and Westgaard, R.H. (1971). The transverse hippocampal slice: a well-defined cortical structure maintained in vitro. Brain Res 35, 589–593.

Wilson, R.I., and Nicoll, R.A. (2001). Endogenous cannabinoids mediate retrograde signalling at hippocampal synapses. Nature 410, 588–592.

Wilson, R.I., and Nicoll, R.A. (2002). Endocannabinoid signaling in the brain. Science 296, 678–682.

S. Murray Sherman

BORN:

Pittsburgh, Pennsylvania

January 4, 1944

EDUCATION:

California Institute of Technology, BS, Biology (1965)

University of Pennsylvania, PhD Anatomy (1969)

APPOINTMENTS:

NRSA Postdoctoral Fellow, Department of Physiology, Australian National University (1970–1972)

Assistant Professor of Physiology, University of Virginia (1972–1975)

Associate Professor of Physiology, University of Virginia (1975–1978)

Professor of Physiology, University of Virginia (1978–1979)

Professor of Neurobiology and of Anatomy, Stony Brook University (1979–1990)

Newton-Abraham Visiting Professor, University of Oxford (1985–1986)

Dr. Lee Visiting Research Fellow of Christ Church College, University of Oxford (2000–2001)

Leading Professor of Neurobiology and of Anatomy, Stony Brook University (1990–2004)

Maurice Goldblatt Professor and Chair of Neurobiology, Pharmacology, and Physiology, University of Chicago (2004–2006)

Maurice Goldblatt Professor and Chair of Neurobiology, University of Chicago (2006–present)

Professorial Fellow, St. John’s College, University of Oxford (2010)

HONORS AND AWARDS (SELECTED)

A.B. Sloan Fellow (1977–1980)

RCDA Recipient (1976–1980)

University of Oxford, MA, Honorary, (1985)

Guggenheim Fellow (2000–2001)

Editor-in-Chief, Oxford Research Encyclopedia (ORE) of Neuroscience (2015–present)

Murray Sherman has devoted his research career to the study of thalamic and thalamocortical circuitry. His efforts have led to elucidating the circuitry of the visual pathway from retina through thalamus to cortex. He and his long-term collaborator, Ray Guillery, are responsible for the introduction of the classification of glutamatergic pathways into driver and modulator categories necessitating a revision of previous ideas about circuit function. They also discovered transthalamic pathways in which direct connections between cortical areas often are paralleled by a cortico-thalamo-cortical route, the importance of which is increasingly appreciated by the neuroscience community. Finally, Murray Sherman is the founding chair of the Department of Neurobiology at the University of Chicago.

S. Murray Sherman

Preface

Although interest in the brain started well before recorded history, it could be argued that the explosive maturation of the field of neuroscience pretty much coincides with my career, from the late 1960s to the present. (This is a nice example of how a correlation does not necessarily indicate cause and effect.) When I started, “neuroscience” was not a phrase in common use. Instead, we referred to a plethora of terms that reflected the lack of unity of the field at the time: “neuroanatomy,” “neurophysiology,” “psychobiology,” “biopsychology,” and others. There were no neuroscience or neurobiology departments. Instead, brain research was largely carried out in medical schools, in anatomy or physiology departments, or in undergraduate psychology departments. As a result, the operative subgroups were pretty much separated from one another. Now, of course, research universities commonly have departments totally dedicated to neuroscience, although some are called “neurobiology” and others, “neuroscience.” Furthermore, many universities now have institutes or centers that provide umbrella support for neuroscience spanning conventional departments. Over this period of increasing interest in neuroscience the Society for Neuroscience (SfN) grew from a few hundred members in 1969 to 35,000–40,000 today. The point is that the field has matured so that neuroscience is now regarded as among the most important academic subjects, in part perhaps because the growth of the field has incorporated many nonbiological disciplines, such as mathematics, physics, chemistry, engineering, computer science, and economics. This is my perspective of the larger environment in which my career developed.

I am impressed with the sophisticated understanding shown by today’s students with regard to career options available to them. In contrast, as I recall, my view and that of my friends at early stages of our careers was poorly informed and generally feckless. Speaking for myself, when I entered graduate school, I had little or no understanding of the National Institutes of Health (NIH) or the National Science Foundation (NSF) or any idea of what being an academic scientist entailed beyond romantic ideas of “eureka” moments more informed by Hollywood than reality. Today’s students are extremely well informed and have a pretty realistic understanding of the challenges that an academic scientific career holds for them. However, I worry that they extrapolate from their enhanced understanding the sense that they have reasonable control over their career paths. If my story has any value for such students, I hope it is the understanding that several critical outcomes in their careers will be determined by factors not under their control but rather by chance and, therefore, that success will also require a large portion of plain good luck.

In the text that follows, I try to emphasize the various factors that molded my career, and perhaps most important among them is serendipity. This starts with having an early family environment that encouraged education and a wife who strongly supported my career choices; it continues with teachers and scientific supervisors who not only provided needed training and role models but also promoted my further career by helping with placement at the next stage; and it ends with having high-quality collaborators throughout my career, both in the form of my predoctoral and postdoctoral students as well as a long-time outside collaborator in Ray Guillery (more on Ray to come). I suppose the underlying message to follow is that luck will show itself at various stages in one’s career, and one has to recognize and take advantage of such occurrences.

Personal History Notes

Early Upbringing and Career Choice (1944–1961)

My early upbringing was pretty unremarkable and, frankly, a bit boring, and so I’ll keep this bit brief. On January 4, 1944, I was born in a Pittsburgh hospital to a fairly conventional Jewish family, but we lived at that time in Carnegie, a mill town just outside Pittsburgh. I have an older sister, Pepi, and a younger brother, Leon. Because of several anti-Semitic incidents in Carnegie (including a second-grade teacher who berated my cousin and me in front of the class for being Jewish, because Jews murdered Jesus), we moved to the Squirrel Hill district of Pittsburgh, a largely Jewish enclave, when I was eight years old.

My paternal grandfather emigrated from a small town in central Europe, arriving at Ellis Island in 1885 at the age of 25. His name then was Marcus Schermer, but somehow the last name was changed to Sherman, a common occurrence at Ellis Island. The name change might be related to the popularity then of General William Tecumseh Sherman; at least that’s the family story, and I’m sticking to it. Marcus developed several small businesses, the most successful of which, a tire shop in Carnegie, he turned over to the partnership of my father, Julius, and his brother, Jacob. My mother, Ida, was born in Pinsk, Belarus, and came to America with her recently widowed father when she was one year old.

My parents, neither of whom advanced beyond high school, provided a stable environment and strongly encouraged education. In my father’s case, opportunity for university education was there. He was valedictorian of his high school class, and he and his brother, Jacob, were all-state football players in high school. As a result, he was offered a full scholarship to play football at Penn State. However, he and Jacob, as the oldest sons, were put to work helping their father in his business ventures. This happened partly because my grandfather needed help with his growing business and wanted to keep it in the family and also because university education was not then seen as so important to business careers as it is today. This also made it possible for the next two sons, Ben and Sam, to become a lawyer and doctor, respectively, which they did. This was the typical Jewish family plan: have at least two sons, with one becoming a doctor, and the other, a lawyer.

My family in 1951. I’m at the upper right.

Thus, in typical Jewish tradition, my parents had the same plan for their children: I, as the first son, was to become a doctor, and my younger brother, a lawyer. My sister is perhaps the brightest among us, but women then were supposed to settle down as wives and mothers, not pursue careers, and so she did as expected: she married young and had three girls, but her marriage has been happy and her daughters have all developed into successful, lovely women. In any event, and as a testament to my parents’ encouragement, all three of us children graduated from university. My brother also followed the plan by graduating from law school, and he has enjoyed a successful law career. I did not follow the plan, as I ended up with a PhD instead of an MD. My mother never really accepted my career choice, and until the day she died, at which time I was a fairly successful senior scientist, she would typically greet me with the plea to go back to medical school to become a real doctor.

I always did well in school, from 1st through 12th grade (no kindergarten then in Carnegie). I had lots of friends and was active in sports to offset my nerdy, scholastic side. My last fistfight was in third grade against Bernie Marcus; we had argued over who was better at drawing horses. Overall, my upbringing through high school was fairly ideal and short on nasty dramatic incidents.

My early decision to pursue a science career started with the intersection of two events. One was a superb and inspiring high school physics teacher, Mr. Norris, and the other was Sputnik. The former made science, and especially physics, seem like an ideal career choice, and the latter—the satellite launched in 1957 by the USSR, an event that shocked and worried Americans—led to a patriotic call for more scientists. So I decided that science generally and physics in particular would be my calling.

Caltech, Pasadena (1961–1965)

I researched which colleges offered the best physics training, and I chose Caltech. I frankly cannot remember why I chose Caltech, because

Mr. Norris and other school advisors recommended the Massachusetts Institute of Technology (MIT) or an Ivy League school, but I do remember having my heart set on Caltech for whatever reason. Being able to attend Caltech meant convincing my parents of my choice. They had never heard of Caltech, which was more than 2,400 miles away in Pasadena, California, and thought nearer choices, like MIT or, better yet, Carnegie Tech in Pittsburgh (it became Carnegie Mellon University in 1967), would suffice. In the end, they relented, helped along no doubt by a generous scholarship offered by Caltech. I started there as a freshman in the fall of 1961.

Caltech was a special place for an aspiring young scientist, as I imagined myself to be. Very few students were accepted: there were about 150 or so in my freshman class. I suddenly found myself among incredibly brilliant peers. This was both inspiring and daunting—inspiring because the friends I made were so talented and served as wonderful early role models for me, and daunting because I was used to being the brightest student in my class, and now I was just average, at best. I noted that a number of my student acquaintances transferred after their freshman year to local, less elite universities, and the word was that they needed again to be thought of as tops in their class. I suppose this was a good experience for me, because if I couldn’t handle being average intellectually in my group, I would find my situation even more depressing when I became a research scientist. We often overlook the fact that our scientific peers are an especially brilliant subset of human beings.

Being a Caltech undergraduate was my first experience away from home, and quite distant at that, so casual weekend visits were not in the cards. Southern California and the Los Angeles area took much getting used to, and this period coincided with the height of the new surfing culture. I also arrived knowing exactly zero people there. I remember my friends in high school choosing colleges based at least partially on having friends there. And so my choice of Caltech would seem to be a recipe for homesickness and depression, but for whatever reason, I never thought about that, and it never bothered me. To the contrary, I rather enjoyed my new freedom, and I absolutely loved the fact that I made new friendships that were quite different from those I developed growing up in Squirrel Hill. Most of my friends through high school fit into a rather homogeneous group—mostly Jewish and rather conformist, although I thought highly of them and still do when I think back. Caltech students had only one thing in common—their brilliance—but otherwise I was exposed to new friends with backgrounds entirely novel to me, including the first foreign born, the first Asian, the first Mormon, and the first farm-raised. (But no African Americans and few Hispanics: Caltech was at that time pretty much white and Asian.) The students there also raised the culture of nerdiness to new heights, but whereas such types were rather shunned in my high school, here they were the norm, and I came to respect that.

A crisis arose early in my sophomore year. My father suddenly died of a massive heart attack. He had one heart attack a few years previously, but I had thought he was fully recovered from that and in reasonably good health, so this was quite a shock. It almost led to my dropping out of Caltech for two reasons. First, my state of mind was not hospitable to education, and I stopped going to classes for a period. My grades suffered. In the nick of time (or so I believe), I pulled myself together and managed to stay afloat. I once again attended classes and studied, and my grades rose back to normal, so I survived this part of the crisis.

The second reason was financial. My father had kept the family finances pretty much to himself, and when he died, we came to realize that the family’s financial state was poor. I thought I would have to drop out of Caltech and get a job, but my mother would have none of that. How she coped, I’m not entirely certain, but she managed to support my continued stay at Caltech. This lasted for a few years, when financial fortune struck. She met an older widower at my cousin’s wedding—he, the widower, was an uncle of the bride. He was also very rich. They married, and my mother’s financial woes ended. I was grateful for that and for the fact that the marriage made my mother happy, but I did not care much for the man. He was Jewish (of course) and would later treat my wife rather badly because she is not. He died a few years after our wedding and left my mother comfortably off for the remainder of her life, so she could move to Florida and mingle among friends during her final years.

I graduated from Caltech with excellent grades despite my sophomore slump. While I was a student, all Caltech undergraduates were male, since women were not finally accepted as undergraduates until 1970. I believe the consensus at the time was that date-eligible young women with any sense avoided us like the plague. Finding suitable female companionship became an ongoing and generally fruitless activity. This was somewhat exacerbated by the proximity of Pasadena City College, from which the Rose Bowl Queen was chosen each year for the annual New Year’s Day Parade. Many beautiful young women enrolled there to be eligible for such royal status, but Caltech was clearly off limits to them. Finding such pulchritude nearby but off limits was frustrating to the extreme. Chasing hopelessly after female companionship led to an awful lot of wasted energy that would have been better spent studying physics.

One skill definitely lacking among Caltech undergraduates was athleticism. This, plus the small student body, enabled me to indulge in my love of sports. Thus, the first two years, I played varsity football, baseball, and basketball. Caltech was notoriously deficient in all three varsity sports, hardly ever winning and with losing streaks often measured in decades rather than games or even years. I remember the team winning a football game on a Saturday against a nonconference rival, the Bible College of Los Angeles. This was the first football win in a decade or more, and needless to say there was a tremendous celebration on campus that weekend. Our joy was short-lived, because, on the Monday, the president of the Bible College of Los Angeles announced that his institution was forthwith giving up its football program.

Three varsity sports took far too much time from studies, so after my sophomore year, I limited varsity sports to baseball. I remember the choice as being partly because it was the least dependent of the sports on others’ skills: football and basketball rely more on teammates for success, and given the athletic quality of me and my teammates, winning even a single game in these sports was beyond hope. I thought baseball, given that I was a pitcher and thus more in control of the outcome, offered more chance of winning a game. In any event, we lost every baseball game anyway, which also says something about my skills as a pitcher. Such was sporting life at Caltech.

There is, however, one athletic record held by Caltech in football that seems unlikely to be broken. Some of our home games were played in the Rose Bowl, a cavernous football arena in Pasadena. Every Caltech game held there was played before more than 90,000 empty seats. I believe that no other college football program can boast such improbable attendance figures.

My senior year, I moved off campus with two other Caltech seniors as roommates, whom I have kept in touch with as friends ever since: Michael Rosbash, currently at Brandeis University, was trained as a molecular biologist and has made seminal contributions to neuroscience, leading to his receiving the Nobel Prize in 2017; and Arthur Niell, trained as an astronomer and currently at the MIT Haystack Observatory. Arthur’s contribution to neuroscience was fathering Cris Niell, a rising star in the field of neuroscience.

Caltech has had an interesting association with the University of Chicago along several dimensions, especially with respect to neuroscience and me. My start in neuroscience as an undergraduate was working in the laboratory of Roger Sperry, who moved to Caltech from a faculty position at the University of Chicago (more on that later). Similarly, the current president of Caltech, Tom Rosenbaum, was provost at the University of Chicago and as such played a key role in supporting the development of neuroscience when I arrived there. Finally, a surprising number of my faculty colleagues in neuroscience at the University of Chicago have Caltech ties: John Maunsell and Ruth Anne Eatock, both in my department, were graduate students at Caltech; and Dan Margoliash and Nicho Hatsopoulos, of the Department of Organismic Biology and Anatomy, also trained there, Dan as an undergraduate and graduate student, and Nicho as a postdoctoral fellow.

University of Pennsylvania, Philadelphia (1965–1969)

I started graduate school at Penn in 1965, working with Jim Sprague. A boyhood friend, Henry Berger, was a first year medical student at Penn that same year, and so we roomed together. Henry and I remained close friends until his tragic death from melanoma in 2011. That first year, there was a housing shortage for new students at Penn, and so the university purchased a decrepit motel, the University Inn, just off the medical campus, and with minimal renovations, turned it into a dormitory for first-year medical, dental, and veterinary students. I was accepted as Henry’s roommate. This was an interesting experience from at least two perspectives.

First, the sociology of these entering students was fascinating to observe. There was a distinct pecking order, with medical students carrying off an air of superiority over dental students. Veterinary students were hard for the others to characterize, but when it was revealed that they had better overall scores and grades than medical students, and several turned down medical school places to become veterinarians, they rose to the top, but they didn’t seem to care, which baffled the dental and medical students. As for me, being the only PhD student there, I was treated as a sort of exotic pet, and I rather enjoyed the whole experience.

The second interesting feature of life there was coming to realize what the University Inn was before being sold to Penn. Philadelphia is the site of a large naval base. On our very first weekend there, a group of sailors showed up in the evening, with their ladies of the night, expecting to rent a room by the hour as they had in the past. When they discovered that the motel had transitioned to a dorm, they attempted bribery to secure a room anyway. Henry and I were tempted but declined. This went on for several more weekends until the word finally spread throughout the U.S. Navy that University Inn was no longer a trysting site.

In 1968, while still a graduate student in Philadelphia, I met my future wife, Marjorie. We married in 1969. I cannot overstate the importance of Marjorie to my career. She has been unfailingly supportive, bore the brunt of raising our children as a wonderful mother, and later worked in my laboratory as a manager and administrative assistant. She has been a great help in editing manuscripts, although in one case, we failed her. She proofread the first book I wrote with Ray Guillery (Sherman and Guillery 2001) and did so flawlessly. The one section she did not proofread was the Preface (because we submitted it rather late to the publisher). We included acknowledgments here and wrote: “Majorie Sherman helped with the proofreading.”

There was one unfortunate aspect to my relationship with Marjorie. My family, extending to aunts, uncles, and cousins, were all serious about their Jewishness. Marjorie was raised as a sort of nonreligious Christian, and neither of us has been religious as adults. To much of my family, it was considered unacceptable for me to marry a shiksa, which is a rather disparaging term for a non-Jewish female. My sister and brother immediately accepted Marjorie as my future wife, and my mother did, grudgingly at first but, after getting to know Marjorie, without reservation. As I wrote earlier, my mother’s second husband never accepted Marjorie and refused to attend our wedding. Even more disturbing, when we announced our engagement, I received a telegram from my uncles telling me that, because I was marrying a non-Jew, they were sitting shiva for me. Sitting shiva is a Jewish rite that effectively means that I was dead to them. Even though growing up I was fairly close to my uncles, I never spoke to them again after this.

I received my PhD from Penn at the end of 1969.

Australian National University, Canberra (1970–1972)

For my postdoctoral training, I signed up to work with Peter Bishop in Australia, starting at the beginning of 1970. An early part of my marriage with Marjorie was defined by what we saw as a great experience involving my postdoctoral training. Living overseas for two years added to the adventure. Furthermore, we purchased around-the-world air tickets that were good for going to and returning from Australia and allowed us at no added expense to make many stops along the way as long as each leg had an eastward vector.

Marjorie and me in Canberra.

We sold all of our belongings (which actually didn’t amount to much) that didn’t fit into our suitcases and set off on our great adventure. Marjorie had found an amazing travel agent through her aunt, who was a seasoned world traveler, and the agent provided us with a fantastic itinerary that we could afford (barely). Going to Australia, we visited Turkey, Greece, Uganda, Kenya, Tanzania, Thailand, and Hong Kong; returning, we stopped at Fiji and Mexico. At each place we were provided with a private guide, and in each case, the guide was competent and most informative.

The best part of the trip was the African leg that was entirely safari. We had great luck with animal sightings. However, we did have one scary episode. While we were in Uganda, there was considerable political unrest, and it was only a few months later that Idi Amin overthrew the elected government of Milton Obote. While driving through the outback in Uganda, there was apparently an attempted coup, a rather common event then, and we were stopped at a roadblock looking for rebels. The roadblock was manned by very young soldiers—teenagers at best—who carried impressive-looking assault rifles and seemed quite nervous and trigger happy. As they pawed through our luggage, they found my photographic tripod and apparently thought it was part of a machine gun. There was a lot waving of arms of and shouting in some Bantu dialect until our native driver managed to explain to them what the tripod in fact was used for. I haven’t traveled with a tripod since.

The only other downside to our extended safari is that I used to love visiting zoos, but after Africa, I find them uninteresting and depressing.

When we reached Canberra at the end of our travels east, we were to be met at the airport by Peter Bishop. We arrived with about $20 between us, having exhausted our fortune on our journey, and the airport was empty. No Bishop, and we had no phone numbers of anyone to call. There was a hint of panic setting in, but Bishop did arrive a bit late, and we heaved a collective sigh of relief. I believe that point was the nadir of our financial status—it’s been uphill ever since.

We were given housing in a suburb of Canberra, called Garran, in the Woden Valley. Garran was a collection of newly built bungalows owned and operated by the Australian National University (ANU). For Marjorie and me, this was a rather luxurious upgrade from the seedy apartments we occupied in Philadelphia, seedy because our combined incomes didn’t support better. The two-bedroom house we occupied in Garran was roomy, airy, and completely furnished down to knives and forks in the kitchen. Most of the residents we met in Garran were postdoctoral fellows in various areas at the ANU, and it was often referred to affectionately as the “Garran Ghetto.” Our neighbors included Peter and Stephanie Hoffmann plus Jonathan and Margaret Stone; Peter, Jonathan, and I collaborated on research in Bishop’s group (more later). The Hoffmanns, Stones, and Shermans became fast friends.

Finances limited our travel within Australia, but we did manage excursions throughout much of the states of New South Wales and Victoria, and we also went on a magical trip to Tasmania. Furthermore, getting to the outback from Canberra was easy, and we often explored the interesting landscapes and animal life there. We were fortunate to have a Garran neighbor, John Baldwin, a zoologist at the ANU and an expert on the outback, to serve as our guide on numerous expeditions. Whereas Canberra remains the only capital city in Australia not sited directly on the coast, an interesting two-hour drive over a small mountain range brought us to Bateman’s Bay, a beautiful, nearly deserted, pristine beach—deserted in terms of humans but not kangaroos and wallabies.

I found that the language barrier there was surmountable and managed it reasonably well. I even learned the jargon associated with cricket. Often, however, I found English usage there somewhat puzzling. For instance, my first experiments there were intended to extend my graduate work, and this involved very delicate brain surgery on cats (e.g., splitting the optic chiasm). To support this, my mentor, Peter Bishop, told me he had arranged time in surgery for me, but also said that he would assign a trained “theater sister” to assist me. I couldn’t understand why a nun with acting experience would be much help. On a similar note, we were bemused by the fact that Sesame Street was a newly popular program in Australia, and there was much complaint among parents that their children were learning and using foreign terms: “cookie” instead of “biscuit,” “wastebasket” instead of “dustbin,” “sweater” instead of “jumper,” “gas” instead of “petrol,” “flashlight” instead of “torch,” and so on. But after a while, I became fairly fluent in the language.

As my postdoctoral period came to an end in early 1972, we needed to return to America and that meant that I must seek an academic position there. My preference, of course, would be a tenure-track faculty position at a university that would support my presumptive research career. I became acutely aware that I was greatly disadvantaged because of my geographic location: no American university would pay to bring me from Australia for an interview.

University of Virginia, Charlottesville (1972–1979)

Fortunately, serendipity intervened. Jim Sprague generously provided a postdoctoral spot at Penn for me to return to America from which I could find my first faculty position, which also owed much to his help (see later). Thus, in July 1972, I started as an assistant professor of physiology at the University of Virginia. Marjorie and I set up home in Charlottesville, where our two children were born: Erika in 1975, and Benjamin in 1978. Both received university degrees and have excellent, stable jobs. Erika works in computers for an advertising firm and lives in Detroit, but she has a second increasingly successful career as a techno musician, a calling that frequently takes her to many American cities as well as overseas to perform.¹ Ben works for Epic in computer support, and lives in Madison, Wisconsin.

Erika was born with a very clear case of esotropia (her eyes were crossed). I thought the best course of action would be to seek advice from the chair of ophthalmology at the University of Virginia Medical School, but I was wrong. The advice was just to wait, and if by the time she was six the problem remained, surgery could then be done to correct it. Fortunately for Erika, much of my research involved visual development inspired by work of David Hubel and Torsten Wiesel that defined the concept of an early critical period for visual development. I thus knew that to wait for six years at the beginning of life would likely mean that Erika’s vision in one eye would be dramatically and permanently impaired. Also fortunately, I had heard of Marshal Parks, a pediatric ophthalmologist in Washington, DC, who understood the concept of the critical period and thus championed early intervention for vision defects like esotropia. So, we took Erika to see him, and he performed corrective surgery to straighten her eyes when Erika was a little over six months old. I’ll never forget how difficult and traumatic it was to then hand over our baby to the surgical team. Nonetheless, and despite the fact that three minor corrective surgeries were later needed, overall this proved successful: Erika now enjoys excellent vision in both eyes.

My discussions with Parks during this period of treatment for Erika were quite revealing. He told us that, as a pioneer in respecting the critical period, which challenged then conventional treatment of no intervention for the first few years, he rattled a lot of cages that resulted in much negative feedback for him. He eventually prevailed, and now it is common practice in pediatric ophthalmology to attempt corrections of abnormalities like strabismus or cataract as early as is safely practical. Nonetheless, this served as a useful example of a problem regarding the recognition by clinicians of relevant basic research findings.

Charlottesville was a good place for Marjorie and me to reestablish ourselves in America. Charlottesville and the University of Virginia campus are historical and picturesque, and the beautiful countryside nearby, particularly the Blue Ridge Mountains, are quite appealing. Living in a small town like Charlottesville was pretty easy and stress-free. However, we felt a bit like the place was haunted by the ghost of Thomas Jefferson, who had lived nearby in Monticello and established the University of Virginia. Charlottesville residents continue to idolize him. While we were there, it seemed that any important decision made by civic or university leaders was first vetted by imagining what Mr. Jefferson would have done.

Eventually, the lack of cultural diversity in Charlottesville wore on us. For instance, the one local Mexican restaurant served black-eyed peas instead of refried beans. The town and university had few people of color. During the school year, local movie theaters showed typical Hollywood fare, but in the summers, when much of the University community departed, this fare was largely replaced by hillbilly porn. Perhaps unfairly, we worried a bit about raising children in this environment. Given this, the opportunity to relocate to an area culturally in the domain of New York City seemed quite compelling. And so we moved to Long Island.

Stony Brook University, Long Island (1979–2004)

After seven years in Charlottesville, I took up a position at Stony Brook University. And so we moved in 1979 to the small village of Belle Terre, just outside Port Jefferson, which in turn is just east of Stony Brook, on the north shore of Long Island. We spent 25 years there. Our home was a few hundred yards from the beach, which was privately owned and maintained by Belle Terre strictly for its residents. We spent much time on the beach and exploring the bucolic east end of Long Island. Life there was very good.

We had expected when we moved to Long Island that we would spend much time in Manhattan. But this turned out to be an unrealized goal largely due to the combined ineffectiveness of the Long Island Railroad and Long Island Expressway. The former took nearly two hours, and an unreliable two hours at that, and the latter could take much more time; both are testaments to our national failure to maintain infrastructure. As a result, after the first few years, we more or less ignored Manhattan except for very special occasions.

The area of Long Island we lived in was a bit unusual politically and culturally. It has a long history, being settled mostly by the English in the 17th century. There was strong Tory (i.e., British) support during the Revolutionary War, and even when we lived there, the local population seemed quite conservative politically. Culturally, the area was predominantly white, with very few people of color. Into this mix was thrust Stony Brook University, which occupied its present campus in 1962. This brought to the area the expected liberal and diverse culture, and to us it seemed that the university was never completely welcomed by the residents. This created a “town–gown” divide. One result was that amenities usually associated with university domains, such as culturally diverse theater, music, and restaurants, were slow to develop.

Our children basically grew up on Long Island and left home to establish their current career paths, starting with university. With this, we experienced an “empty nest” lifestyle. This made it easier for us to leave Long Island when I took up my present position at the University of Chicago. Of course, the main attraction for me was a leadership position in developing neuroscience at a great institution.

University of Chicago (2004–present)

The move to Chicago marked a dramatic change in life style for Marjorie and me. This was our first experience in big city living since our earlier experience in Philadelphia: Canberra and Charlottesville are small towns and Belle Terre is barely a village. We moved to Chicago without much knowledge of the city itself: neither of us had spent any appreciable amount of time there, not counting endless periods of waiting at O’Hare airport for flight delays. So it was a delightful surprise to discover the city of Chicago and come to realize that we love living there. It seems to us like a much cleaner and friendlier version of Manhattan, with wonderful architecture plus excellent music, theater, and restaurants. We also love the fact that the frontage along Lake Michigan from south of Hyde Park north almost to Evanston has been kept pretty free of private development and, as a result, is one long park. The lakefront is a source of beautiful recreation much admired by the people of Chicago. We quickly adapted to city living.

We settled in the Hyde Park section of the city, where the University of Chicago is located and which is about six miles south of the city center, right along Lake Michigan. Houses are hard to find in Hyde Park, and so we spent the first two years there living in a university-owned apartment, all the while looking for a house suitable for us. After two years, we did so and moved into our present abode. I love the fact that this provides me with a 12-minute walk to my office. Our move to Chicago also places us closer to our children: Erika lives in Detroit and Ben lives in Madison, Wisconsin. We get to see them much more often than we did while we were living on Long Island.

The Sherman family in Chicago. From left: Erika, Benjamin, Marjorie, and me.

Hyde Park is ethnically and racially quite diverse. It is dominated by the university, and roughly two-thirds of the faculty live in Hyde Park. It is thus a sort of academic ghetto. But Hyde Park also includes a large segment of non-university people. What is odd (to me) is that a large and vocal segment of Hyde Park residents resents the university and sees it as an undesirable element in the area. This seems partly to stem from the fact that the university is a major landlord, owning many of the residences and properties rented out to various businesses, and so the university is a vehicle for change, which is not acceptable to many. I suppose these sorts of town–gown conflicts are inevitable.

Oxford University (1985–1986, 2000–2001, 2010)

I took three sabbaticals, all at Oxford University in England. The first two (1985–1986 and 2000–2001) were for a little more than 12 months, and the last (2010) was for the summer. For the first one, Marjorie, Erika, and Ben all came with me, but for the last two, our children were out of the house, and so it was just Marjorie and I.

The city of Oxford and its university present a spectacular scene, with its numerous colleges housed in buildings of architectural and historical splendor, many of the buildings being in constant use for centuries. Oxford University is sort of like Disneyland for academics.

There is no American equivalent to Oxford University, so it takes some explaining. The university is a rather loose confederation of its colleges. There are 30–40 Oxford Colleges, unclear to me exactly how many, because the exact number seems to depend on how various Oxford establishments are classified. The college is the academic heart of the university, and undergraduate hopefuls apply to a college, not the university, for a place. The colleges are quite variable in size, stature, and history. For example, Lincoln College is a fairly small college, currently with 35 fellows (the equivalent of faculty, although the actual term varies among colleges), whereas Christ Church College currently has 53 fellows (although at Christ Church, these are rather confusingly known as “students”). The oldest colleges were formed in the 13th century, and the newest, in the 20th. Much of the fortune at Oxford University is concentrated in the colleges, and the older ones are generally the wealthier.

Each college acts as a nearly independent academic unit. It provides room and board for most of its students and fellows. The meals, especially dinners, can be quite splendid in some of the wealthier colleges: Fellows dine berobed at high table in medieval splendor. Also, these same colleges have extensive wine cellars where fellows are offered premium wine, brandy, and port, at huge discounts. It is said that as impressive as the stately and historic architecture of the colleges is above ground, the cellars are even more impressive. Most teaching is done in the college by fellows leading “tutorials” with students, typically just three to four students per fellow at each tutorial, and this is supplemented by classes provided outside of the college by traditional academic departments. The tutorial system means that each college must have a range of fellows able to cover the range of requisite topics. Thus, Oxford Colleges are built for breadth of subjects rather than depth.

If, during a prolonged stay, one is lucky enough to obtain a visiting fellowship at one of these colleges, as I did, then one benefits from the same privileges, above and below ground, as enjoyed by the permanent fellows.

First Sabbatical (1985–1986): A wonderful family experience for us involved my first sabbatical in Oxford with my long-term collaborator, Ray Guillery, from August 1985 to September 1986. I had a special and rather extravagant fellowship—the Newton-Abraham Visiting Professorship—organized by Ray. He was chair of Human Anatomy and in a position to deliver such a splendid appointment for me. The fellowship was generously supported by a trust based on the proceeds from royalties associated with the discovery of cephalosporin at Oxford University by Edward Abraham and Guy Newton. They were working in the group headed by Howard Florey, who, along with Alexander Fleming working separately in London, was credited with the discovery and clinical development of penicillin. The fellowship included a beautifully furnished modern house on the edge of University Parks, an ideal Oxford location close to the science area, as well as a visiting fellowship in Lincoln College. Having been founded in 1427, Lincoln College is rolling in wealth, and at the time of my sabbatical, was the richest college per fellow.

The appointment also led to my receipt of an honorary MA from Oxford University at the beginning of my fellowship. This involved a brief ceremony held entirely in Latin during which I had to provide a short speech prepared for me, also in Latin. I had no idea what was said to me or what I said, but no one present seemed shocked, which means either that their Latin was no better than mine or that I did okay. It all reminded me of my Bar Mitzvah.

Being a fellow at Lincoln College was a real treat for me. Its wealth was a significant factor in my sabbatical, because its fellows were treated generously and had access to the college’s dining hall and wine cellar. Regarding the former, Lincoln had one of the best chefs in all of England, and so I very often had lunch, and occasionally dinner, there (family obligations limited these feasts, and except for rarely held special dinners, spouses were not welcome). Lunches were attended by many or most of the other fellows, and because of the breadth of disciplines covered by the fellows noted above, this meant lunch interactions involved learning something, often rather eclectic, about a wide range of academic disciplines. One day I might have lunch sitting next to an Egyptologist, the next day, a nuclear physicist, and the next, an economist. For me this was very different from my experience at American institutions in which we tend to interact nearly exclusively with colleagues working in fields close to our own.

My first sabbatical expanded my horizons in addition to the scientific ones I gained from association with Ray and other top academics there. My devotion to the Lincoln College wine cellar provided me with a real education of the best French wines and an appreciation of good port. I learned how to eat a banana with a knife and fork, which I understand is very proper.² Indeed, this is how Queen Elizabeth II eats bananas. Also, I learned (sort of) to punt, and by this I don’t mean kicking an American football but rather using a pole to propel a boat down a stream.

For me, the benefits of the sabbatical, in addition to my enological schooling, involved my association with Ray: The time spent together took our collaboration to a higher, more intense level. But there were others at Oxford that also contributed to my academic development, particularly Tom Powell and Kevan Martin. Ray gave me an office in his department that was next to that of Tom Powell, a celebrated neuroanatomist working on the mammalian visual system. I was cautioned about Tom before my arrival.For instance, Jim Sprague, an old friend and colleague of Tom, warned me that he was a major curmudgeon who often could be quite harsh with those he took a dislike to. For whatever reason, in my case, Tom was nothing but pleasant and supportive; I had many interesting discussions with him about the visual system. However, I did see the other side of Tom, when Irving Diamond arrived for a several-month stay in Oxford the spring and summer of 1986. Irving shared my office at the time. Tom, again for whatever reason, seemed to dislike Irving—there was obvious history there of which I remain ignorant—and Tom was constantly and openly critical and dismissive of Irving.

Irving was one of the Old Boys, along with Jim Sprague, who helped me secure my first faculty position, and he remained a supporter. As anyone who knew him could attest, Irving was a quite a character and oversized personality; he was also a dapper dresser. During his stay at Oxford, he seemed to regard my personal appearance in terms of dress with patient disdain. After a few days, he insisted on taking me on a stroll through the main shopping area of Oxford around the High Street, whereupon he introduced me to his tailor, shirt maker, and bootmaker (i.e., English for shoemaker) with the urging that I avail of their services. This was too rich for me, so I resisted, but in the end, I relented enough to buy a pair of shoes from his bootmaker. Maybe Irving had a point: I still wear those shoes today, more than 30 years later.

The other important personal relationship I further developed in Oxford was with Kevan Martin. I had a productive interaction with Kevan soon after our move to Stony Brook: he came to work with us (mainly Mike Friedlander) to learn the technique of intracellular recording and staining individual neurons in vivo. We hit it off, and I was looking forward to interacting with him in Oxford, where he was working with David Whitteridge as a research fellow. We spent much time discussing issues of circuitry of the mammalian visual system. I particularly enjoyed sitting in on his recording sessions of visual cortex, where Whitteridge often stopped by for lengthy periods, regaling us with wonderful stories of his earlier life spent in India. But Kevan also became a close family friend, spending much time with Marjorie, Erika, and Ben, as well as with me, and he provided much useful insight into British culture.

For my family, and especially my children, the experience of living in another country with a different perspective on life was priceless. We traveled all over Britain, and we became enthusiastic Anglophiles. We particularly enjoyed the cathedrals and castles we wandered through. This included York Minster, which had a devastating fire in 1984 that pretty much destroyed its south transept and roof. This gave our daughter, Erika, an opportunity to demonstrate her artistic ability. Blue Peter, a very popular children’s program on BBC television, announced a contest for their young viewers for the best designs of bosses to be used in the reconstruction of the damaged vaulted ceiling of York Minster. (Architecturally, bosses are ceiling knobs common to cathedrals with rib vaulted ceilings and are found at the intersections of the ribs; they are often intricately carved and colored.) The six best designs would be used. Erika entered a wonderful design that made runner-up, which was quite an achievement and made us proud.

My son, Ben, who was seven at the time, picked up a delightfully genuine Oxford accent. Soon after we returned home to Long Island and he began third grade, he brought home a note from his teacher telling us that he had a serious speech impediment and needed to see a speech therapist as soon as possible. (On Long Island, the word “dog” is pronounced “dwohog,” and so you can imagine how strange an Oxford accent would appear to a local.) We could not convince the teacher that this was a case of accent and not impediment, so Ben was examined by the therapist who duly reported that he talked like an Englishman, which is not usually considered to be an impediment. Unfortunately, Ben soon lost his posh accent, but this whole experience may have inoculated him against developing a Long Island accent.

One hiccup was culinary: There were no Cheerios or grape jelly to be found in England for Ben and Erika, and these were major food groups they relied on. They were unable to breakfast suitably and had no proper accompaniment for their peanut butter. A partial solution involved several trips I had to take back to the United States. I thus traveled with our largest suitcase, empty, and returned to England with it filled with Cheerios and grape jelly. I worried that a U.S. customs agent might spot check my bags on entry and become very suspicious at the large empty suitcase, but fortunately that did not happen. However, on one of my return trips, a British customs officer asked to see the contents of my luggage and was positively stunned at the sight of the boxes of Cheerios and jars of grape jelly. I thought I’d be put up on smuggling charges. Fortunately, the agent accepted my explanation with understanding and humor (or humour?).

A final factor helped in acclimatizing us to Oxford. Tony Movshon and his family (wife plus young son and daughter, just like us) also spent the year on sabbatical at Oxford. The Movshons were housed just around the corner from us. Our families were already on very friendly terms before the sabbatical, and our close association with them during the year was just one more benefit added to the experience.

There were two dark clouds to the year for us. One was mad cow disease, which was discovered in England in 1986. We had eaten some British beef before the announcement, and that was a cause for concern. The symptoms may not show up for decades, which means that we and our children can never be completely sure that we don’t harbor the infection. In any event, we do not actually spend time worrying about it. However, because we lived in England during this period, we are banned from giving blood. Perhaps the worst part of this for us was having to refrain from beef for the remainder of our stay there. The other concern was the Chernobyl accident, which occurred in April 1986. The fear was that an unfavorable wind would deposit a lethal, radioactive cloud over England. This, fortunately, did not occur, and the concern dissipated after a few weeks.

Second Sabbatical (2000–2001): For this sabbatical, it was just Marjorie and I. My stay there was supported again by a visiting fellowship from a prestigious college: I was the Dr. Lee Visiting Research Fellow of Christ Church College from August 2000 to September 2001. (Matthew Lee was an early 18th-century physician who was a member of Christ Church College and endowed the fellowship.) Christ Church College is similar to Lincoln College in terms of age, wealth, and the privileges it provided for its fellows. One difference is size, because whereas Lincoln College is among Oxford’s smallest, Christ Church is among its largest. One of the privileges the fellowship afforded was a furnished apartment across the street from the College in a prime location within the city.

Ray Guillery was at this time a visiting professor at the University of Wisconsin, so although we continued our collaboration during this year, it was at a distance. My sabbatical instead was spent with Ian Thomson, a visual neurophysiologist then in the Department of Physiology at Oxford. At the time, Ian worked on ferrets, doing single-cell receptive field analysis of neurons in the lateral geniculate nucleus and primary visual cortex. I sat in on many of these experiments, but mostly served as a passive observer. Nonetheless, I gained much from this experience. I learned new ways to study visual receptive fields, and after my exposure to the ferret as an animal model for my future studies (I was considering a switch to ferret or mouse), I realized that, for my interests, I should look elsewhere. Perhaps more important, my scientific interactions with Ian, his students, and others at Oxford once again proved critical to the development of my theoretical framework underlying my research program.

Marjorie and I once again thoroughly relished our time in England. In addition to Oxford itself, we enjoyed the countryside, especially the nearby Cotswolds and beyond, and we particularly enjoyed long walks there. However, the year of our stay, England suffered from two major ecological disasters that limited our rambling. One was historic rainfalls that preceded our arrival and led to severe flooding. Many of the rights-of-way for walkers were vast lakes and thus impassable, and any long walk meant the likelihood of a certain amount of wading. The other problem was foot-and-mouth disease, a dreaded and deadly disease that particularly plagues cattle and sheep. Since many of the hiking trails in England involve rights-of-way through private land used for grazing of these beasts, and because one way of spreading the disease is through hikers carrying it from one field to another, many or most of the best hiking trails were closed for the year.

A special treat was our return home. We arranged through a special deal with the Cunard Cruise Line to return home on the Queen Elizabeth II in 2001. Traveling by ocean liner was a great luxury: lovely food, wonderful entertainment (mostly musical), and leisurely travel. We arrived on the piers of the Hudson River in Manhattan on September 4, 2001, exactly one week before 9/11.

Third Sabbatical (Summer 2010): My final sabbatical (so far) was briefer, covering the summer of 2010. Again, Marjorie accompanied me. I received support as a professorial fellow of St. John’s College, which also afforded a furnished apartment in an excellent location within north Oxford. St. John’s College was very much like Christ Church College in age, size, wealth, and generous treatment of its fellows. The fellowship was arranged by my host, Andrew Parker, a professor in the Department of Physiology and also a fellow of St. John’s; Andrew performs single-cell analysis of neuronal responses in the monkey extrastriate visual cortex.

Oxford University and its colleges are largely shut down from normal functioning during the summer, and the lively academic environment is largely replaced by language programs in which students from the continent spend the summer in various colleges learning English. Thus one doesn’t experience the intense academic milieu of Oxford in the summer months. However, this disappointment was more than offset by the benefits to my scientific thinking of once again interacting with Oxford neuroscientists. The fact that Ray Guillery had returned to Oxford as a professor emeritus meant that, for the first time in 25 years, we were physically reunited for an extended period allowing us to pursue our collaboration with greater intensity. But more than that, I was installed in the Department of Physiology by Andrew, and that meant daily quite productive discussions with him and others in the neuroscience community, including Kristine Krug, Andy King, Zoltan Molnar, Peter Somogyi, Paul Bolam, and Colin Akerman.

Serendipity

How I decided on a career in neuroscience, starting with my time as a graduate student, involved a lot of serendipity. It also involves serious name-dropping, for which I apologize in advance, but it is central to the story. Without considerable good fortune at several stages of my career, I would not have been invited to write this.

My decision ultimately to choose neuroscience for a career was taken during my Caltech years. Caltech students were required to take two full years of physics in their freshman and sophomore years. What made this especially memorable for us was the fact that Richard Feynman (Nobel Laureate and name drop #1) decided to teach us these two years as the sole lecturer. I believe ours was the only undergraduate class formally taught in a classroom environment by Feynman. He was a remarkable lecturer: creative, superb at explaining complex concepts, and especially entertaining. His lectures were one event that we almost never missed. Occasionally during class, he would interrupt his physics instruction with personal stories and sometimes career advice for us. Several times he suggested the following: that, while many of us came to Caltech to become physicists, the real scientific frontier, more challenging and interesting than physics, was study of the brain; we should consider going into brain research (“neuroscience” was a term for the future).

I would like to think that Feynman’s suggestion had a decided effect on my career choice, and it may well have, but in truth, my memory of the impact of his proselytizing for brain research is somewhat questionable. In any case, after my first year, I needed a summer job, and because of its availability and possibly also because of Feynman’s suggestion, I took up a position in the laboratory of Roger Sperry (Nobel Laureate and name drop #2). I liked it and stayed on for the next three years, until my graduation.

My time in his laboratory was well spent. I worked with a senior research fellow of his, Evelyn Lee-Teng, and my collaboration with her led to a PNAS publication (Lee-Teng and Sherman 1966). Sperry was an imposing, imperious figure who did not interact with me very much. Thus, in spite of the productive time spent in his laboratory, even after two years I wasn’t sure that he knew that I existed. Imagine my surprise (and anxiety) when, at the beginning of my senior year, he called me into his office. The conversation I remember quite clearly, almost word for word, although I cannot guarantee that what is written below is an exact transcription:

Sperry: I’ve been watching you [I feared the worst at this point]… . You show promise. If you’re interested in a career in brain research, I’d like to offer advice …

Me [much relieved]: As a matter of fact, I am interested in brain research as a career, and I’ve started to look at grad schools.

Sperry: Excellent. Which schools are you considering?

Me: Right now, my first choice is the University of Chicago. [At that time, the University of Chicago had one of the few brain research programs I was aware of.]

Sperry: If you go to Chicago, I’ll never speak to you again!

His response dumbfounded me. Being naïve and rather passive, I asked what he would suggest instead. He told me that I would do well to go to Penn to work with Jim Sprague. I did. I never learned with any certainty what led to his astonishing response to Chicago (or, for that matter, why he recommended Sprague), but I later found out that, as a junior faculty member at the University of Chicago, he was denied tenure—thus the relocation to Caltech. Perhaps he retained bitterness over this and developed sustained animosity to the University of Chicago. Of course, the irony here is that I am now at the University of Chicago.

Another case of serendipity involved my choice of postdoctoral training. I remained feckless in my plans for my career, except for the notion that I needed postdoctoral training. I flirted with various options, rather superficially, until one day Jim Sprague came to me and suggested that I go to Australia to work with Peter Bishop. I’m not sure where that recommendation came from, but I followed it. The serendipity came with respect to the Vietnam War, which was raging at the time. My 2S student deferment was about to expire, and to leave the country, I needed written permission from my draft board. They gave permission with the caution that I would likely be selected for possible drafting, meaning that I would have to report to the nearest military facility at my expense for a physical examination in preparation for being drafted. I decided to go anyway. After five or six months in Australia, I received a letter from my draft board requiring me to appear on the specified date at a military facility in Hawaii for my physical. The specified date had already passed by several months! This is because they sent the letter by surface mail, which took months to arrive. I was panicked, thinking that my no-show would result in extradition and prosecution, so I fired off a letter to my draft board (sent via air) explaining my absence and asking for another date. I never heard from them again. Rather than being drafted, I was able to resume my embryonic career. This was made possible only by the curious decisions of my draft board both to communicate either via surface mail or not at all and also to not pursue prosecution. It wasn’t until my return to American soil via air ended with no U.S. marshal greeting me with a warrant that I felt completely safe.

These events at the beginning of my scientific career relate to two issues. First, for better or worse, my career path was largely dictated by unpredictable forces over which I had no control. The curious outburst against the University of Chicago by Sperry and his suggestion to opt instead for Penn and Sprague remains somewhat enigmatic, but I likely would have otherwise started research training at the University of Chicago instead with unknown results for my career. The suggestion by Sprague to go to Australia for my postdoctoral training allowed me to continue my career, because if I had opted for the much more common and likely choice of an American laboratory for further training, my draft board’s letter would have arrived in time, and I would have been taken from science into the military with a likely end to any further research training. Second, the reason I followed Sperry’s and Sprague’s advice was my rather passive, uninformed nature, which I find in stark contrast to today’s students, who, to their credit, are much better informed and in charge of their careers. In my case, I regard myself as extremely lucky at the turn of events, but a lesson for all, I believe, is that successful academic research careers require luck: skill, intelligence, and hard work are necessary but insufficient ingredients.

Professional Positions

Graduate Training (1965–1969)

I entered the PhD program at Penn as a graduate student in the Department of Anatomy in the summer of 1965. My graduate training would likely be unrecognizable to current students. Science at that time (latter 1960s) was very different than now: It had a leisurely, laid-back style dominated by an “Old Boy” network; competition for grant money, high-impact publication space (impact factors were a future concept), and recognition was considerably less than today. Only one other neuroscience student, Dennis Stelzner, matriculated with me—Allan Basbaum and Peter Strick arrived a year or two later. So it was a very small program. Also, the neuroscience faculty component consisted only of very senior members: Jim Sprague, Bill Chambers, Peter Hand, Louis Flexner, John Liu, Adrian Morrison, and Elliot Stellar. Peter Sterling arrived a few years after I began as the only junior faculty presence in the group. Also, unlike a modern research department, anatomy at Penn had little in the way of recognized laboratories run by principal investigators. Instead, there were mostly communal spaces shared by all, such as a large histology facility, rooms for training animals, a microscope room, and rooms for basic electrophysiology. Thus, I didn’t actually work in a laboratory cheek by jowl with other students and postdocs but rather worked mostly on my own in these spaces. In these regards, the department was very old fashioned.

One result of the makeup and character of the department was that it had few rules for graduate students, and I felt my requirements were mostly determined ad hoc. This suited me well. In this environment, I believe the most important lesson I learned as a graduate student came from observing my mentors, especially Jim Sprague, Elliot Stellar, Bill Chambers, and John Liu: They were wonderful role models for how to behave as an academic and scientist. I would like to think that their examples served me well in this regard. What I did not get much from my graduate experience were examples of modern research laboratories and practices. In any event, I ended up with a thesis that was adequate (barely, in my opinion, so no more said about that) for my PhD in 1969.

However, my PhD in anatomy should come with an asterisk. When I arrived at Penn in 1965, the course for medical students in gross anatomy was under way. We could tell when the course was in session, because the air stank of formaldehyde and all the doorknobs were greasy. I decided immediately that I wanted to avoid taking the course. When the departmental chair, Louis Flexner, a small but authoritative figure, heard about my request, he called me into his office. He was rather annoyed at my attitude and asked for a good reason why I should avoid the course. My answer was that if I never took the course, I never would be expected to teach it. He burst out in laughter (a shocking relief to me) and said that was the best reason he ever heard, and he immediately gave me permission to skip the course. So I have a PhD in anatomy but don’t know my whatever from my elbow.

Postdoctoral Training (1970–1972)

I experienced a different research environment when, at the beginning of 1970, I moved as a postdoctoral fellow on an NIH F32 fellowship to the Department of Physiology at the John Curtin School of Medical Research of the ANU in Canberra. Peter Bishop was chair of the department, and the department was entirely composed of laboratories working under his overall guidance on vision research. These were very active and productive laboratories run by creative and industrious colleagues: These included Bill Levick and Geoff Henry when I arrived, and Jonathan Stone soon afterward. Postdocs who were contemporary with me were Peter Hoffmann, Bogdan Dreher, Mark Dubin, and Brian Cleland; Ken Sanderson was the sole graduate student. For much of my two-year period there, Horace Barlow was present on sabbatical with Bill Levick, and he added much in the way of scholarly value. This was a dynamic group, and it was during this time, that I received real training in how to do research effectively.

It may be hard for students today to appreciate the quality of this laboratory group. Peter Bishop replaced John Eccles (a Nobel Laureate) as head of the department just before I arrived, so the department already had a superb reputation. At the time, the Bishop laboratory was considered one of the best in the world for vision research, its main competitor being that of Hubel and Wiesel. I find it somewhat sad and a bit bewildering that few students today know of Peter Bishop and his contributions.

My first research assignment was to help Ken Sanderson, then a graduate student, with his thesis experiments. This was my first opportunity to learn electrophysiology and single-cell recording, because Ken’s thesis was all about understanding receptive field properties of cells in the cat’s lateral geniculate nucleus, the thalamic relay of retinal information to visual cortex. I had the good sense to understand that our roles were reversed: As a postdoctoral fellow, I was the trainee to Ken, even though he was a graduate student. In any event, Ken was an excellent trainer, and we published two papers together (Sanderson and Sherman 1971; Sherman and Sanderson 1972). After Ken, I moved on to work with Geoff Henry on receptive field properties of cat V1 cells. We investigated many receptive fields in great detail (Bishop and his colleagues in Australia were pioneers in the use of computers to analyze receptive field properties quantitatively), and I learned a lot from Geoff, even though no publications derived from this work. During my first year in Canberra, Jonathan Stone joined the group and was assigned his own laboratory. Soon after, Peter Hoffmann and I joined Jonathan and formed a productive team concentrating on properties of the parallel X and Y streams in the cat visual system, and I remained with Peter and Jonathan for the duration of my stay in Australia.

Much of the research I was involved in for my postdoctoral training represented my first experience at the grueling schedule required for the continuous recording from an animal kept alive in an anesthetized state for two or three days. This approach was one I followed for the next decade or so. Although that approach served me well as a mainstay to the beginning of my independent research career, I’m happy to say that experimental approaches in my laboratory evolved to be less physically grueling.

From a training point of view, two things about my postdoctoral environment strike me. First, experiments generally were not based on specific hypotheses to be tested. They were mostly investigations about how things worked without preexisting biases. Can we find any responses to the nondominant eye in geniculate cells? What are the detailed patterns of excitatory and inhibitory parts of V1 receptive fields? How similar are geniculate X and Y receptive fields to their retinal counterparts, and how do these change with eccentricity? Today, it seems that the powers that be (e.g., various granting agencies) dictate that good science must start with hypothesis testing. Second, and perhaps related to this unbiased approach to science, the Bishop style was based on a detailed quantitative study of parameters, with the idea that such detail could eventually uncover interesting principles. This dependence on quantification may be seen as the antithesis to the more qualitative approach that depends for success on great insight, ingenuity, and originality—not qualities present in all—plus good luck. The problem with this latter approach is that the requisite qualities for success cannot easily be learned or developed, whereas the approach involving observation with a strong quantitative focus can. In any case, I believe this is one important lesson I acquired from my postdoctoral experience.

There were several other striking features of my postdoctoral environment. One is that everyone in the department worked on similar projects, all involving the cat visual system from the retina through the lateral geniculate nucleus to V1. Peter Bishop oversaw all of this somewhat loosely, allowing for considerable independence in approach, and in this capacity, he was also very supportive. This included three major laboratories: one headed by Geoff Henry, another by Bill Levick, and the third by Jonathan Stone. Working on similar problems provided benefits in the form of useful collaboration, but it also created some problems. Bill’s group (including Brian Cleland and Mark Dubin) and Jonathan’s (including Peter Hoffmann and me) worked on largely the same issues involving the parallel organization of X and Y pathways. Bill and Jonathan are strong personalities, and this turned into a sometimes-unpleasant competition that, frankly, detracted from the overall otherwise-excellent research environment. One example among many involved terminology: We referred to the cell types as “X” and “Y” (and, later, “W”), whereas Bill’s group insisted on “sustained” and “transient” (and “sluggish”). As a testament to how unpleasant this became, several papers were later published representing these two points of terminological contention, papers notoriously lacking in collegiality (see Rowe and Stone 1977 versus Hughes 1979).

Perhaps the most unusually dramatic feature of the environment was the isolation of the Bishop laboratories from the rest of the world’s scientific community. In those days, there was no internet, and journals arrived via surface mail, which took months to arrive in Australia (recall earlier about how this affected my military career, or rather, lack thereof). As a result, we operated in a vacuum with little or no idea of what the rest of the scientific world was up to. This is hard to imagine in today’s internet-tempered research environment in which we are far too aware of what’s going on in other laboratories, especially in those of our competitors.

One result of this is that the work in Bill’s and Jonathan’s groups on parallel processing was developed to a state of some maturity before being made public. Christina Enroth-Cugell and John Robson first described X and Y cells in the cat retina in 1966 (Enroth-Cugell and Robson 1966), but not much was made of this until various papers came out from the Canberra groups in the early 1970s (e.g., Cleland et al. 1971; Hoffmann and Stone 1971; Stone and Hoffmann 1971; Hoffmann et al. 1972; Sherman et al. 1972; Stone and Dreher 1973; Fukuda and Stone 1974). From my perspective, this new way of looking at the organization of the central visual pathways seemed to hit the field as a fully formed new concept from out of the blue. That novel, mature concepts could appear so suddenly seems quite unlikely today, when we know far too much about ongoing research issues at very early stages.

I saw the reaction to this firsthand at a memorable meeting held in Canberra in early 1972, just before I left to return to America. Many leaders in vision research attended, and a list of participants plus the proceedings were published in a 1972 issue of Investigative Ophthalmology (volume 11, no. 5). I vividly recall the astonishment and responses of the visiting participants as one after another of us presented our research results on parallel processing. Because these accounts challenged views of visual processing current at the time, the responses were not always positive. This meeting effectively came at the end of my postdoctoral experience.

Overall, my postdoctoral period was very productive for me and made me a viable candidate for a faculty position when I returned to America. My name as author or coauthor appeared on nine research papers derived from my stay of two years in Canberra. I attribute much of this to the environment created by Peter Bishop.

University of Virginia (1972–1979)

When my postdoctoral period was nearing its end, I knew that I wanted to pursue an academic research career, which meant that my next move would be to secure a faculty position at a research-oriented university. I wanted to return to America. My prospects seemed up in the air, however, and my situation was further exacerbated by the fact that I was far from home. Fortunately, Jim Sprague anticipated the problem and continued to provide generous support for me. This was then demonstrated by his offer of a temporary position with him at Penn that would allow me ready access to appropriate positions in America. Marjorie and I arrived back in Philadelphia in March 1972.

Soon after, during the first week of April, I attended my earliest major meeting at which I could present my experimental results on research I had done in Canberra. This was at the annual meeting of the American Association of Anatomists held in Dallas, and I saw it as my first opportunity to present my credentials as a potential tenure-track faculty member. I was excited at the opportunity and viewed it as extremely important to my career development.

In those days, the SfN was still neonatal and not yet the dominant venue for neuroscience, and in any case, its meeting would not be held until fall. The anatomy meetings had, up to that time, actually been the main setting for neuroscience. There were still few if any neuroscience departments, and most of what we would consider today to be neuroscience was then housed in anatomy departments. Also, presentations at major meetings were different in those days. Posters were rare, and most information was passed on in the form of 15-minute talks. And talks were illustrated not by PowerPoint but rather by old-fashioned slides imaged by Kodak Carousel projectors. The norm was that, as the speaker before you started, you loaded your slides in the empty Carousel to be used for your talk.

As I started to load my slides, I was horrified to discover that they did not fit: my slides were mounted in Australia in thick binders designed for European style Zeiss projectors, and they were too fat for the Kodak equipment. I panicked. There are two versions of what happened next, mine and that provided by Jon Kaas who had given the talk just before the current speaker. I’ll try to give both. In my version, I realized that Jon had slides with the proper binders for Kodak projectors. I went over to him and explained my plight, and asked for his help. He jumped right in, and we proceeded to unbind both sets of slides and refitted mine in his binders just in time for my talk. In Jon’s version, I went to him to ask to look at his slides. He thought that I was so enamored by his talk that I wanted to go over it again in more detail, but he was shocked as I began to tear his slides apart. In both versions, Jon did realize the problem and gallantly helped me to avoid disaster.

So, I had navigated my first test as a potential faculty candidate thanks to Jon. Soon after, I visited the University of Wisconsin to look at a faculty position there, but this failed effort will be described in more detail, because it represented an early attempt for Ray Guillery and me to get faculty positions at the same place. At that point, I did not expect to resume looking seriously for a faculty position until after the summer of 1972, the season then as now when most faculty hiring commenced. However, Jim Sprague then took matters largely into his own hands to set me up with possible positions immediately. Recall that the Old Boys network was still up and functioning at that time, and Jim was definitely one of the Old Boys. He was close friends with Irving Diamond of Duke University, another Old Boy and venerated neuroscientist, and the two of them explored their network to come up with a promising position for me at the University of Virginia. The two major neuroscience figures there who supported my hiring were John Jane and David Cohen. John was chair of neurosurgery and a close friend and associate of Irving Diamond, and I believe that was the link that mattered most. David was then a professor in the Department of Physiology, the department into which I was recruited as an assistant professor. David immediately became my mentor, and his tutelage was a catalyst to my successful transformation from a rather feckless and rootless wannabe to a respectable faculty member.

I quickly set up a productive laboratory, greatly assisted by my first graduate student, Jim Wilson, and I followed up research threads from my postdoctoral period. I was able to get NSF and NIH funding right away, and began publishing a steady stream of research papers. As a result, I was promoted rapidly, to tenured associate professor in 1975 and full professor in 1978.

The University of Virginia was a great place for me to begin my independent research career. My chair, Bob Berne, was a renowned cardiac physiologist and coauthor of a major medical textbook (Berne and Levy, Physiology). Although not a neuroscientist, he strongly supported neuroscience generally and me specifically. Although there were only two other neuroscientists in the department (David Cohen and John Hackett), other departments contributed to a small but collegial neuroscience group. This included John Jane, Sven Ebbeson, Ozzie Stewart, and Ed Rubel in neurosurgery as well as Steve Edwards and Lennart Heimer in anatomy.

Although the neuroscience community was collegial and of high quality, it was small and limited, and it became clear toward the end of my time there that the University of Virginia was not likely to invest more heavily in neuroscience to take it to the next level. Attempts to form a neuroscience department or even a neuroscience graduate program led nowhere. This particularly bothered David Cohen, whose attempts to develop the area at the University of Virginia were frustrated. In 1979, he was recruited by Stony Brook University to establish a new neurobiology department there. Harvey Karten, who was a close friend of David and later become one of mine as well, was then at Stony Brook and a key factor in the recruitment. David encouraged me to join him, and I was ready to make the move both because I was also frustrated by the limited future for neuroscience at the University of Virginia compared with the possibilities at Stony Brook and also because Marjorie and I were ready for a change of scenery. We made the move in the summer of 1979.

Stony Brook University (1979–2004)

Because of a misplaced sense that I needed to establish some independence from David, I chose to take a position at Stony Brook in the Anatomy Department rather than in David’s. That was a nearly disastrous decision for me, because I immediately ran afoul of the chairman of that department, and after one year, I was again saved by a mentor: David offered me a position in his department, which I eagerly accepted.

Moving my laboratory to Stony Brook was greatly expedited by the fact that two of my senior postdoctoral fellows at the University of Virginia, Mike Friedlander and Larry Stanford, made the move with me. They did the bulk of the hard work in setting up the new laboratory and did so quite quickly and efficiently. Also, as noted earlier, after the first year at Stony Brook, we moved departments, from Anatomy to Neurobiology, involving occupation of a new space and meaning that the laboratory had once again to be broken down and reconstructed. As a result of the efforts and efficiency of Mike and Larry, we were able quite quickly to resume our experimental program.

This was an exciting time for me, for reasons apart from my own experimental program, because I was from the beginning able to work with David Cohen to build a new department from scratch, which obviously involved a lot of faculty recruiting. David did a great job in doing so, and thus I enjoyed being in a department filled with first-rate neuroscientists. In spite of the fact that the final result was a success, I did have differences of opinion with David concerning the faculty recruiting, including the strategy behind it. This made me realize that I was actually quite interested in the possibility of playing the role of leading the development of my own department if the right opportunity came along. Eventually, it did in Chicago, but I’m getting ahead of the story.

As the department grew, I benefited from interactions with virtually the entire faculty, but my closest colleagues during this period, besides David, were Harvey Karten, who was already at Stony Brook when we arrived, and new recruits Craig Evinger, Paul Adams, and Lorne Mendell.

The department had a curious structure, as it was considered both part of the Medical School as a Basic Science Department and also part of the undergraduate College of Arts and Sciences, which was practicable, because the Medical School and undergraduate colleges were part of the same campus. This meant that David reported to two deans and that our teaching involved both medical students and undergraduates as well as graduate students. Despite the dual nature of the department, each faculty member had to be administratively in one or the other college (Medicine or Arts and Sciences). As I recall, only three of us (David, Harvey, and I) were appointed in the Medical School with 12-month contracts; the others were all Arts and Science faculty with 9-month appointments. This strange arrangement might seem to be a cause for concern and internal strife, but it became irrelevant. This was largely because David as chair, and Lorne as his successor, ignored the differences in appointment when it came to salary, teaching assignments, and so on.

Stony Brook University was an odd place academically. Overall, it was a second-rate institution, and I was often bemused at the relentless self-promotion by the leadership to claim first-rate status, but such shameless institutional self-promotion seems quite common in academia today. Despite the limited overall quality, there were some programs that were especially strong and decidedly first-rate. Among these were the sciences, especially physics, and mathematics. I would include the Basic Science Departments of the Medical School in this category. Unfortunately, the clinical departments, in my estimation at the time, were mediocre academically, and this severely limited our horizons as biomedical scientists. Also, despite the relatively rare situation of a medical center located at the undergraduate campus, few successful examples existed of programmatic cross-fertilization between entities. Thus, it felt like the potential to extend neuroscience more broadly across campus went unrealized, something that played a role in my later decision to relocate to the University of Chicago. Nonetheless, and much more important to me, I regarded the Department of Neurobiology at Stony Brook as outstanding, and so my immediate environment was nurturing and exciting.

An unusual aspect of my laboratory at Stony Brook was its makeup: it consisted almost entirely of postdoctoral fellows and technicians. I did have two graduate students during my time at Stony Brook, but they entered from other programs: Alev Günlük (now Erişir) from the psychology program and Iva Reichova, a transfer from Northwestern University. In my 25 years there, not a single student from our neurobiology PhD program entered my laboratory. This is particularly odd, because I had graduate students at the University of Virginia and currently do so at the University of Chicago. I would have been happy to have graduate students at Stony Brook, but none were interested in my laboratory. I never got a real explanation for this.

University of Chicago (2004–present)

I was basically very happy at Stony Brook, and by the time my stay passed the 20-year mark, I fully expected to remain there for the rest of my career. As noted earlier, however, I was on the lookout for the right opportunity elsewhere to build a first-rate program of neuroscience. I had several criteria to be met that set the bar for the right situation pretty high: The institution had to be top-notch; the leadership position (e.g., a department chair) had to be structured in a way that would not significantly impede my laboratory’s research program; and there had to be widespread institutional support for further development of neuroscience.

I had looked at a few possibilities after 2000, but none met these criteria. And then the possibility of Chicago came up. This intrigued me, because the quality of the institution clearly met one of my criteria, but I was a bit concerned that as a neuroscience entity, the University of Chicago was not even on my radar screen at the time. However, during my first visit, I came to appreciate that there were in fact many superb neuroscientists there. The problem seemed to be that, because there was no neuroscience department or institute with control of hiring to follow any strategic plan for the development of the field, the neuroscience community was spread over a number of departments, both in the Medical School and undergraduate campus, and it was also spread over a number of subdisciplines. Thus, in my view, despite having real strength among individuals, the neuroscience community was broad but not deep, and because there were no critical masses representing any single research topic, the community was not well recognized.

The University of Chicago had made a strategic decision early in the millennium to significantly enhance neuroscience. The Medical School dean who hired me, Jim Madara, was a strong believer in neuroscience, and together we concocted a strategy to move forward. The ultimate plan had two parts: first, to create a new Basic Science Department of Neurobiology to establish an initial focus and strategic center for developing the field; and second, to form a Neuroscience Institute with real resources that could be the strategic center for developing neuroscience campus wide, by encouraging departments other than Neurobiology (e.g., Psychology, Statistics, and Organismal Biology and Anatomy) to recruit neuroscientists.

This was an ambitious plan that would require strong support from both faculty and the administration. Administration support was already in hand. To generate faculty support, which is a sine qua non at the University of Chicago for accomplishing anything as ambitious as we had in mind for the development of neuroscience, Madara formed a committee cochaired by Dan Margoliash and me to come up with a strategic plan. In the event, this meant agreeing to the plan Madara had already formulated. Dan’s effort here was indispensable, and we were able to get widespread faculty support for this plan with considerable enthusiasm.

Thus, in my second year at Chicago, the Department of Neurobiology was created, which is no small feat and required lengthy hearings and approval by a very conservative faculty senate. We immediately and quite successfully started recruiting faculty. For the next step, we needed to establish the Neuroscience Institute, and things were progressing nicely regarding necessary funding for it when the financial crisis of 2008 hit. This put the establishment of the institute on the backburner, which at the time I viewed as only a delay. But then another crisis hit: Madara was replaced as dean by Ken Polonsky. Not knowing the new dean, I immediately worried that he would lack the passion for neuroscience shown by his predecessor and allow it to languish. In fact, Polonsky has been even more of an enthusiastic sponsor of neuroscience than Madara and supported the continuing development of neuroscience quite generously. We were back on track.

The next set of tasks involved securing the funding for the institute, which was done in due course, and then recruiting a director. The latter took considerable time and effort, but in the end, we succeeded in luring John Maunsell to the position. He arrived in 2015 and immediately succeeded in partnering with various departments to recruit top-notch neuroscientists. As I write this, things are definitely on the ascent for neuroscience at the University of Chicago.

Also, from the perspective of my own research program, the move to Chicago has been a boon. Whereas, I very much liked my time at Stony Brook and thought highly of my colleagues there, there has been an added benefit of my move to Chicago. That is, at Stony Brook, there was no research focus that was close to mine, so my efforts were pretty much isolated. At Chicago, we recognized early on the need to develop critical masses within neuroscience, and as department chair, I had some influence over the areas chosen. As a result, there are numerous faculty here with whom I maintain active collaborations, especially with Jason Maclean. Such local collaborations are new to me, and I very much enjoy them.

Ray Guillery

As I was drafting this section, Ray Guillery died after a brief illness on April 7, 2017.³ He was my most important mentor, colleague, collaborator, and friend. Our relationship spanned most of my life. I was heartened but not surprised at the vast number of people who expressed sadness and loss at his passing. I’ll end this before getting too maudlin.

My work has benefited enormously from collaboration with Ray Guillery that spanned most of my scientific career (Ray, by the way, was short for Rainer, and it always irritated him when someone decided to be more formal with him and called him “Raymond”). I always thought of Ray as my mentor, and many people seem surprised when I tell them that Ray was not my predoctoral or postdoctoral advisor. Ray always treated me as an equal. This collaboration has served me particularly well: It has made my scientific efforts far more interesting, fun, and significant. Indeed, I don’t believe the SfN would have asked me to write this memoir were it not for my interactions with Ray. I think it best to emphasize and describe this before relating in any detail what sort of science issues dominated thinking in my laboratory, because these largely reflect my interactions with Ray.

Ray Guillery and me in front of the “Bean” in Chicago.

I first met Ray in 1968. This was the same year I met my future wife, and in both cases the meetings led to a long and fruitful partnership. Ray then was a professor at the University of Wisconsin and I was still a graduate student at Penn. We hit it off immediately and began a long correspondence that started with snail mail and now is mainly represented by thousands of e-mails. Most of the correspondence is about neuroscience, but some is rather naughty gossip that is best kept private.

I was quite impressed that a senior, already famous neuroscientist could take a mere graduate student so seriously, and that reflects well on Ray, who has a pretty independent view of what is interesting scientifically. Our collaboration started off relatively slowly, but we hit on questions of mutual interest in visual development of cats that led to three coauthored research papers in the mid-1970s (Sherman et al. 1974; Sherman et al. 1975b; Sherman and Guillery 1976). Our collaboration moved onto a more theoretical plane in the early 1980s and received a boost when I spent a year-long sabbatical in 1985–1986 with Ray at Oxford University (he had moved there in 1984 to become chair of Human Anatomy). This sabbatical involved rather intense discussions on various aspects of the nature of the thalamus and thalamocortical relationships. Often these were arguments that led to one of us changing the view of the other as our different perspectives began to blend. Often one of us would offer an out-of-the box idea that the other tried to shoot down during further discussion. Often the shots hit their targets, but occasionally such ideas survived our early skepticism to become more fully developed as hypotheses we used to challenge conventional wisdom regarding thalamus and thalamocortical relationships. Starting in 1986, we began to put down our thoughts on paper, and published 11 reviews or opinion pieces (Sherman and Guillery 1996, 1998, 2002, 2004a, 2004b, 2011, 2014; Guillery and Sherman, 2002a, 2002b, 2011) and three books (Sherman and Guillery 2001, 2006, 2013).

Ray and I made several attempts to get faculty positions at the same place. The first attempt was soon after I arrived back in America: Ray had arranged for me to visit his Department of Anatomy at Wisconsin to explore a possible position there. Unfortunately, the timing was bad, because Ray was away in London on sabbatical, and his chair, who was not enthusiastic about further development of neuroanatomy in his department, pretty much nipped this idea in the bud. Ray was pretty furious about all of this, feeling he was stabbed in the back. I soon ended up at the University of Virginia. When it became clear to me that Virginia would not be a place likely to develop neuroscience significantly and to Ray that Wisconsin was also decreasingly suitable for him, we looked at three other places more or less together: the University of California at San Francisco, the University of Utah, and the University of Chicago. The problem was that we each had criteria to be met, and satisfying both of us turned out to be too challenging. The offer I received at University of California at San Francisco represented a pay cut, because I was told that UCSF was so wonderful that I should jump at the opportunity to move there and not worry so much about salary. That did not sit well with me. As for Utah, my wife and I were already worried about raising our children in a setting dominated by religion (although Charlottesville was fine, the surrounding area was in the realm of the Moral Majority, which was housed in Lynchburg, just down the road from Charlottesville), and Utah did at the time seem dominated by religious tenets. Ray did end up at Chicago, but my wife and I were simply loath to raise our young family in any inner city at that time, and so I made my move to the bucolic environs of Stony Brook.

Together, Ray and I developed three major ideas that, we believed, challenge current views of thalamocortical processing (details to follow): glutamatergic pathways are inhomogeneous and can be classified into at least two types that we named driver and modulator; based on their driver input, thalamic relays can be divided into first and higher order, the latter representing a link in transthalamic corticocortical processing; and driver inputs to thalamus may play a role as efference copies.

My Predoctoral and Postdoctoral Trainees

In addition to being enormously lucky in my collaboration with Ray Guillery, I feel equally lucky with the quality of young scientists who spent time in my laboratory over the years. Table 1 lists them. It shows the general high level of accomplishment they achieved as a group by noting their current or last known positions. I can claim little credit for their successes, because, as any of them would certainly testify, my role was mostly to offer support but to generally get out of the way of productive, energetic researchers who, as a group, deserve the vast bulk of credit for the reputation of the laboratory. I am very proud of them.

Research Perspectives

My research career has had one common theme, namely, understanding the circuitry of the thalamus and thalamocortical interactions, although there have been a few minor detours. I would rate my major research accomplishment overall as longevity and relative consistency in productivity rather than being able to boast of any special individual breakthroughs. It has been a career of steady but modest advances. I have also been very fortunate in my collaborators. My association with Ray Guillery has been described, but I must also emphasize the quality of the graduate students and postdoctoral fellows who worked in my laboratory over the years. These are listed in Table 1.

Two other themes have played a role in my thinking about the brain. One is that there is too much emphasis on cortex and a failure to take into account that many behaviors, some fairly complex, do not involve cortex at all. Even those that involve cortex succeed only if cortical outputs can play effectively through subcortical circuitry. That is, despite all the beautiful and complex circuitry of cortex, it would be pretty useless except for the fact that it can influence motor circuits in brainstem and spinal cord via its subcortical projections, specifically those from layer 5. The other theme is the importance of evolution in my thinking about brain organization. The two points are actually intimately related. My view of evolution, which is certainly not original with me, is that our early vertebrate ancestors, before cortex evolved, had complex behaviors subserved by brainstem and spinal pathways, and as cortex evolved, these subcortical circuits did not disappear to be replaced by newer cortical ones. Instead, these older circuits remain in our central nervous systems and operate independently or in partnership with corticofugal pathways to continue to control behavior. Another way of stating this is to point out that the evolution of cortex did not occur with the coevolution of a motor plant to which cortical circuitry is privileged; instead, cortex evolved outputs that affected the older motor circuits and had to do so in cooperation or competition with other, older brain areas to affect those same motor control areas.

It is my sense that, especially in the visual system, cortex has been overemphasized and thalamus ignored. This is perfectly exemplified by an experience I had about 30 years ago in London. The Museum of Natural History there had just announced a new exhibit involving the human brain, so I decided to stop by to see it. On entering the exhibit, I initially encountered a large three-dimensional model of the human visual system. In this model, the retina projected directly to the visual cortex. My snail mail correspondence with those responsible for the exhibit is another story (this is well before e-mail when people actually used the post office to communicate), but this model was eventually removed.

Table 1    Previous Trainees

*retired †deceased

The various themes and their progression are described in the following sections, divided into periods defined by my various positions over the years.

While a Graduate Student at Penn

I started graduate school with Jim Sprague just at the time the Sprague Effect was described. Jim published his results in Science in 1966 (Sprague 1966). To my mind, this is a historically important paper, and rather than try my hand at summarizing it, I simply copy the abstract:

Total contralateral hemianopia follows unilateral removal of the entire occipito-temporal neocortex in the cat. This deficit is classically ascribed to interruption of visual radiations serving cortical function (“cortical blindness”) and is considered permanent. Return of vision to the hemianopic field after subsequent removal of the superior colliculus contralateral to the cortical lesion demonstrates that neither assumption is correct. The initial hemianopia is apparently due to depression of function of the colliculus ipsilateral to the cortical lesion, a depression maintained by influx of inhibition from the crossed colliculus. Thus, removal of the contralateral tectum, or splitting of the collicular commissure, abolishes this inhibition and allows the return of function in the ipsilateral colliculus, and with it the recovery from hemianopia. These findings emphasize that visually guided behavior is mediated at both cortical and midbrain levels, and that there is a marked interaction between these sites. (Sprague 1966)

In essence, this says that much visually guided behavior can be performed in the absence of cortex. The initial observation that cortical lesions cause apparent blindness continues to be misinterpreted to mean that cortex is pretty much the end-all and be-all for vision, but this and subsequent work (Wallace et al. 1990; Ciaramitaro et al. 1997) make clear that such blindness is due partly to the secondary effects of the cortical lesions that somewhat denervate and thus incapacitate critical subcortical sites, such as the superior colliculus. Note that the recovery of vision that the Sprague Effect documented following collicular manipulation was supported by subcortical structures that are themselves damaged because of the removal of cortical input. Thus, the role in vision of such structures as the superior colliculus in normal, intact animals may be even greater than that noted by the Sprague Effect.

What I find surprising is that this seminal (to me) observation seems lost in history. During the past few SfN meetings, I have noticed posters describing experiments that are eerily similar to or complement the Sprague Effect, but each time I have asked the presenter (invariably a graduate student or postdoctoral fellow) if he/she has ever heard of Jim Sprague or the Sprague Effect, I have been greeted with blank stares. I suppose sometimes it’s easier to repeat classical experiments than to comb through the literature.

In any case, the Sprague Effect was one of the earliest scientific discoveries I was exposed to, and it clearly had an impact on me. Ever since, I championed the idea that many behaviors have a significant subcortical substrate, a view that has been consistently ignored. I often took the notion too far, relegating cortex too much. Nonetheless, this philosophical bias has stayed with me. I regard this as perhaps the main scientific point of view I absorbed while a graduate student.

While a Postdoctoral Fellow in Australia

Two different research questions began to emerge as a carryover from my graduate experience as I started my postdoctoral stint, and eventually they more or less coalesced. First, I rather passively allowed myself to be recruited into ongoing projects at the beginning of my time in Canberra. This suited my subcortical bias, because the initial experiments with Ken Sanderson involved mapping of the lateral geniculate nucleus, and my later collaboration with Jonathan Stone and Peter Hoffmann also involved the lateral geniculate nucleus. Second, like many of my generation, I became fascinated with and affected by the science of Hubel and Wiesel, especially their work on the critical period.

I joined the experiments on X and Y cells with Jonathan and Peter, which started a research line that formed the basis of my efforts for the next several decades. I was a bit of a latecomer to this effort. This was transformative for me, because prior to this, I was in search of research themes that could start to define my career, and these experiments provided me with exactly what I needed to develop a sustainable research approach.

Part of my reason for wanting to join Jonathan and Peter had to do with a hunch related to visual development. That is, Hubel and Wiesel showed that visual deprivation by early lid suture in cats led to severe loss of input to cortical cells from the deprived eyes (Wiesel and Hubel 1963b, 1965). They also reported “normal” responses among geniculate cells in these cats despite finding that these same deprived geniculate cells were anatomically shrunken (Wiesel and Hubel 1963a). I found the incongruity between the anatomy and physiology of geniculate cells odd and thought that perhaps a cell type was selectively affected and shrunken, leaving other cell types with normal properties. Testing the possibility of differential deprivation effects on geniculate X and Y cells seemed like a logical next step, and this fit perfectly with the sort of experiments Jonathan and Peter had planned. They accepted the hypothesis as reasonable, and so in addition to studying geniculate X and Y cells in normal cats, we also did so in visually deprived animals.

The result served as the basis for a great deal of my future research (Sherman et al., 1972). Much of this had to do with studies of binocular competition during development, often in collaboration with Ray Guillery. Here, the concept of binocular competition bears some explanation. The extreme nasal retina sees peripheral visual field that is beyond the image formed on the other eye’s temporal retina, and so this segment of visual field is seen by only one eye: This is the monocular segment, and the central, majority of visual field is the binocular segment. The representations of these segments in central visual structures, such as the lateral geniculate nucleus and visual cortex, are known as the binocular and monocular segments of those regions. The idea of binocular competition during development is that circuits from the two eyes compete for control of neural connections and, with normal development, a balance is struck. However, during development under visual deprivation, circuits related to the deprived eye are at a competitive disadvantage because of the deprivation, allowing the nondeprived eye’s circuits to dominate. However, this happens only in the binocular segment, where competition can occur, because circuits mapped to the deprived monocular segment by definition do not suffer from a competitive disadvantage. Thus, the deprived monocular segment can develop relatively normal connectivity.

Getting back to my studies with Jonathan and Peter of geniculate X and Y cells, we found that, in cats reared with monocular deprivation, X cells in deprived geniculate layers were normal but that there was a drastic loss of Y cells. Furthermore, the Y-cell loss was limited to the deprived binocular segment, echoing a result from Ray Guillery’s laboratory that geniculate cell shrinkage from monocular deprivation was limited to the binocular segment (Guillery and Stelzner 1970). In both instances, Y cell loss and cell size, the deleterious effects of deprivation were limited to the binocular segment, observations that helped to establish binocular competition as a major mechanism for visual development.

Our finding of Y cell loss never had the impact I thought it should, which I suppose is a complaint common to many scientists, founded or otherwise. My view is that there are two related reasons for this. One is the cortico-centric bias of the field. The idea that interesting deprivation effects could have a partial subcortical basis was hard for cortical chauvinists to accept. Related to this was the suggestion that the observation of a Y cell loss was some sort of sampling artifact. That is, Y cells were shrunken and thus harder to isolate for recording, as if even this explanation made sense: Why would one expect shrunken cells to be normal? While this result of failure to record normal numbers of deprived geniculate cells may still be open to interpretation, I believe that subsequent results point pretty clearly to deprivation affecting Y cells considerably more than X cells (Friedlander et al. 1982; Sur et al. 1982; Sur et al. 1988).

A final research direction I started in Australia was to apply the perimetry approach in cats that Jim Sprague used to define the Sprague Effect. Basically, this perimetry technique determined in which parts of the visual world a cat could detect the appearance of a novel target. I used perimetry testing to evaluate the effects of visual deprivation on this detection behavior. Perimetry testing of cats formed another theme, along with visual deprivation and parallel processing, that I carried from Australia to my next academic destination.

While a Faculty Member at Virginia

Perimetry Testing: The perimetry testing of cats that I carried over from Australia had two related goals. The lesser goal was to extend the Sprague Effect to normally reared cats with cortical and midbrain lesions, whereas the more important (to me) goal was to use this extension as control data for technically similar studies of visually deprived cats. The deprivation experiments had two main findings. First, monocularly deprived cats had normal vision for stimulus detection in the deprived monocular segment, which provided a behavioral correlate to the finding of normal geniculate cell sizes and Y cell presence in the deprived monocular segment (Sherman 1973). Second, the asymmetry between perimetry in the two eyes of monocularly deprived cats (i.e., the nondeprived eye had normal perimetry, whereas the deprived eye was blind except for the monocular segment) disappeared after visual cortical lesions, and after such lesions, normally reared and visually deprived cats exhibited the same perimetry behavior, which also means that the cortical lesion actually improved vision for the deprived eye (Sherman 1974). This latter result indicates that perimetry defects associated with early visual deprivation had neuronal substrates largely limited to geniculocortical circuitry and that retinotectal circuits developed normally during deprivation.

A Key Early Collaboration with Tom Norton and Vivien Casagrande: Here again, I note the loss of one of my best friends and key collaborators in neuroscience: Vivien passed away at the end of 2016. Like my relationship with Ray Guillery, mine with Viv was long lasting and enduring. We first met in 1972 just after I returned from Australia, and we remained close ever since. Viv was one of the most remarkable women I ever met: She was generous, dedicated, loyal, and talented, and she packaged all of this with a great sense of humor. I along with all of her colleagues miss her greatly.

Tom, Vivien and me at Duke in 1977.

Early in my stint as a University of Virginia faculty member, I collaborated on experiments carried out at Duke University with Tom Norton and Vivien Casagrande. Tom was a faculty member there and served as our host; Viv and I commuted for the experiments, she from her position as a postdoctoral fellow with Ray Guillery at the University of Wisconsin. My commutes involved horrid bus trips from Charlottesville to Durham. The main purpose of these experiments was to determine whether the X/Y concept of parallel processing could be extended to species other than the cat. The species we chose for this was the tree shrew, because it seemed an important species from the point of view of evolution of mammalian vision and is a species that Vivien had worked on extensively as a graduate student with Irving Diamond at Duke.

There was a clear scientific yield of this collaboration: The identification of X and Y cells in the tree shrew’s lateral geniculate nucleus as well as loss of geniculate Y cells in visually deprived tree shrews (Sherman et al. 1975a; Norton et al. 1977). But for me, there were two other less easy-to-measure benefits. First, working with Tom and Vivien, despite the appalling hours of all-night experiments, was sheer fun. I also enjoyed my experiences as a graduate student in Philadelphia and postdoctoral fellow in Canberra, but those environments were created by my mentors there, and this was my first experience with an environment I created with my close peers. This gave me confidence that my ongoing career would continue to be fun, if nothing else. The other benefit came from my interactions with Vivien. Her approach to neuroscience was driven by principles of evolution. Before this, evolution was an abstract notion for me that played little or no role in my neuroscientific thought; since this interaction with Vivien, I have shared her perspective on evolution, and it has definitely shaped my thinking, for better or worse.

A Key Early Collaboration with Ray Guillery: Another collaboration early in my faculty stint at the University of Virginia was with Ray Guillery. During this early period of my time at the University of Virginia, our efforts together moved from somewhat-casual discussions to a more formal and productive level. The catalyst for this was our shared interest in the concept of binocular competition as a major mechanism of visual development as described earlier. This started with Ray’s demonstration noted previously of normal geniculate cell sizes in the deprived monocular segment (Guillery and Stelzner 1970), and he followed this up with his ingenious artificial monocular segment model—that is, he sutured one eye of a kitten and simultaneously made a small lesion in the central temporal retina of the open eye. This lesion created an artificial monocular region (which he called the “critical segment”) mapped to the deprived eye, and Ray demonstrated that deprived geniculate cells grew to normal size in the deprived geniculate region mapped to the artificial monocular segment (Guillery 1972). This crucial supplement to the earlier observations more firmly established that the relevant factor in visual development is binocular competition and not some property of peripherally versus centrally mapped regions of the visual pathways. Once this initial observation was made, Ray and I extended it by testing the artificial monocular segment model for other evidence of binocular competition. Thus, we showed that in both natural monocular and artificial monocular segments there was normal development of geniculate Y cells, normal responses of cortical cells to visual stimuli, and normal location of objects in perimetry testing (Sherman et al. 1974; Sherman et al. 1975b).

Further Visual Deprivation Studies: Most of the rest of the research effort of my Virginia laboratory was devoted to studies of the effects of visual deprivation on the central visual pathways and visual behavior of cats. Much of this may be seen as a failed effort to convince the field that there were effects of deprivation outside of those described in visual cortex. However, there was one finding we reported that I believe is critical to this issue and that has not received much attention. The basic finding was that visually deprived cats had much poorer visual capabilities than did normally reared cats with bilateral lesions of visual cortex (areas 17 and 18) (Lehmkuhle et al. 1982; Lehmkuhle et al. 1984). Our conclusion can be appreciated by our final summary point in one of the papers:

Finally, because the amblyopia of normally reared cats with lesions of striate cortex is far less severe than that of the lid-sutured and dark-reared cats, it follows that the constellation of deficits reported for striate cortex in these visually deprived cats cannot provide an adequate neural explanation for their amblyopia. Attempts to relate deprivation amblyopia to striate cortex abnormalities should thus be reconsidered. (Lehmkuhle et al. 1982)

Sticking and Staining: A final research line that started toward the end of my tenure at Virginia and carried over through my move to Stony Brook was the technique of labeling physiologically identified neurons recorded intracellularly with a dye that enabled post hoc morphological reconstruction of the same cell, also known as “stick-and-stain.” Although this approach had been used successfully for some time in invertebrate preparations with large and accessible neurons, it was a paper that accomplished this approach with cat caudate cells (Kitai et al. 1976) that really caught my attention. However, this seemed like hopeful pie-in-the sky to me until the arrival of a very talented postdoctoral fellow in my laboratory, namely, Mike Friedlander. Mike never saw a challenge he feared to attack and immediately agreed that it would be a good thing to adopt this approach to study the structure–function relationships of geniculate X and Y relay cells and interneurons in the cat. So we did, largely through Mike’s ability to make it all work (Friedlander et al. 1979, 1981; Friedlander and Sherman 1981).

This was the start of a series of studies that investigated the different functional organization of these parallel pathways, and it benefited in the beginning by the addition of Larry Stanford, another postdoctoral fellow committed to these studies. We continued such studies after the move of the laboratory to Stony Brook in 1979, a move that was greatly supported by the fact that Mike and Larry made the move with me, and it was the two of them who did the bulk of the work reestablishing the laboratory.

While a Faculty Member at Stony Brook

More Sticking and Staining: We immediately began extending the stick and stain approach in several ways. We added W cells to the mix (Stanford et al. 1981); we described the morphology of both retinogeniculate and geniculocortical X and Y axons (Sur and Sherman 1982; Humphrey et al. 1985a; Humphrey et al. 1985b); we succeeded in taking this analysis to the electron microscope level (Wilson et al. 1984; Hamos et al. 1985; Hamos et al. 1987); and we also applied this approach to the study of visual deprivation and development, providing further evidence for selective deprivation effects on the Y system (Friedlander et al. 1982; Sur et al. 1982; Sur et al. 1984). All of this provided what I would describe as useful insight into the differential functional organization of the parallel pathways in the cat visual system, details of which can be found in the cited publications.

Through the 1980s, there was considerable, sustained interest in parallel processing, especially after the concept successfully extended to primates, where the cat’s W/X/Y streams appear respectively homologous to the monkey’s K/P/M equivalents (reflecting inputs through the geniculate koniocellular, parvocellular, and magnocellular layers). Parallel processing remains as important as ever, but for reasons that elude me, interest in this topic has all but evaporated from mainstream questions regarding the organization of visual pathways.

Details of Geniculate Circuitry: The extension of structure–function relationships to the electron microscope level encouraged us to continue using mainly morphological techniques to dig deeper into the functional circuitry of the cat’s lateral geniculate nucleus. Key to this was a very talented and long-serving technician, Sue Van Horn, who coauthored many of the resultant publications; a graduate student Alev Erişir; and two postdoctoral fellows, Jim Hamos and Martha Bickford. This led to a certain amount of new understanding, most details of which are beyond the scope of this writing, but included X/Y differences, the location of synapses onto dendritic trees of relay cells, the organization of triadic circuitry in glomeruli, and details of circuits involving GABAergic interneurons.

One surprise was our finding from a detailed analysis of inputs to geniculate relay cells. In spite of the fact that we’ve known for decades that the main information relayed to cortex by these cells is carried by the retinal input, we concluded that retinal synapses represent only about 5 percent of all synapses onto relay cells (Van Horn et al. 2000), which lowered this estimate from the earlier one of 15–20 percent proposed by Ray Guillery (1969). This has implications for our ideas about “drivers” and “modulators” expressed in the following sections.

Tonic and Burst Firing: Much as the report of intracellular staining of basal ganglia cells (Kitai et al. 1976) inspired us to try this approach for geniculate cells in the cat, back-to-back papers from the laboratory of Rodolfo Llinás (Jahnsen and Llinás 1984a, 1984b) caught our attention. I thought the idea that thalamic relay cells had different firing modes controlled simply by their background membrane voltage offered exciting new possibilities for control of thalamocortical transmission. This thinking was further supported by an influential idea—the “searchlight hypothesis“— proposed by Francis Crick (1984) that suggested that these firing modes underlie key attentional mechanisms. We thus decided to explore the possible functional significance of these firing modes.

Several students and postdoctoral fellows were key to our progress here, most notably Bill Guido. We provided three main advances: We showed how the different firing modes could be identified in extracellular recording, we showed some of the neuronal circuitry that seemed effective in controlling which firing mode presented at any given time, and we suggested a role for the firing modes (Guido et al. 1995; Sherman 1996). We found that tonic firing offered a more linear relay of information, and so information relayed during tonic firing would not suffer the nonlinear distortions imposed by burst firing; thus, tonic firing would be better for stimulus discrimination. However, the nonlinearities seen during burst firing would enhance signal-to-noise ratios; thus, burst firing would be better for stimulus detection and could serve as a “wake-up call” to cortex that a new stimulus has appeared.

This idea turned out to be quite controversial because of the prevailing view that burst firing occurred only during sleep or epilepsy and was not an effective relay mode: Tonic firing was the only mode employed during normal waking behavior. That is, the hypothesis that burst and tonic firing both provided different advantages for thalamic relays during waking behavior requires that both firing modes, and not just tonic firing, be present during such behavior. The strongest advocate against our idea of a useful relay function for burst firing was the late Mircea Steriade, who insisted that bursting never occurred during waking behavior (e.g., Steriade 2001). Mircea was a remarkably productive scientist who made many seminal contributions to thalamocortical processing. In this case, however, his stubborn intransigence baffled and frustrated me, because there was ample evidence then and contemporary evidence still being produced that makes pretty clear that bursting does occur during waking behavior in a number of different species and systems tested. Furthermore, many of these studies provide evidence for the “wake-up call” hypothesis for burst firing (for a few examples, see Fanselow et al. 2001; Swadlow et al. 2002; Lesica and Stanley 2004; Ramcharan et al. 2005; Lesica et al. 2006; Andolina et al. 2013; Ortuno et al. 2014; Hu and Agmon 2016; Whitmire et al. 2017). The issue of burst and tonic firing in thalamic relay cells remains an important topic that needs to be better understood.

First and Higher Order Thalamic Relays, Drivers, and Modulators: Following my 1985–1986 sabbatical in Oxford with Ray Guillery, we started in earnest to discuss and argue about general issues regarding thalamocortical relationships. It took some time for us to realize that our discussions could be productively developed into publications, first with reviews and finally with monographs. Two themes took shape in this way in the 1990s: the concepts both of first and higher order thalamic relays as well as of driver and modulator classes of glutamatergic afferents.

Ray wrote a 1995 review that for the first time proposed that thalamic relays could be divided into first and higher order, the former relaying a subcortical input (e.g., retinal input for the lateral geniculate nucleus) and the latter, an input from layer 5 of a given cortical area as a link in a transthalamic corticocortical information route (Guillery 1995). In our review that followed soon after (Sherman and Guillery 1996), we extended this idea and made it a central theme of our further collaborative work.

The driver/modulator distinction for glutamatergic inputs evolved from two perspectives. First, there was a prevailing view that saw information processing as involving glutamatergic pathways to carry the information, with other pathways (e.g., cholinergic, noradrenergic, and GABAergic) playing a more subtle modulatory role by affecting how glutamatergic pathways were processed. This, in turn, suggests a more or less homogeneous function for glutamatergic afferents, with them acting in some sort of anatomical democracy to affect or control their targets—that is, the larger the input, the more powerful it must be. However, our knowledge of geniculate circuitry belied this view, because the two prominent glutamatergic inputs onto relay cells, inputs from retina and layer 6 of visual cortex, did not follow these rules. This is because these inputs clearly seemed quite different, and only the retinal input appeared to carry the basic information to be relayed. This made the retinal input the more prominent in driving geniculate relay cells, and yet it has a much smaller anatomical footprint with only about 5 percent of the input synapses versus about 40–50 percent for the cortical input.

We struggled with this until a paper appeared from David McCormick’s laboratory showing that corticogeniculate input activates metabotropic glutamate receptors, as well as ionotropic ones, but retinal input activates only ionotropic receptors (McCormick and Von Krosigk 1992). This is another example of a paper triggering a new approach both in the development of ideas with Ray as well as the design of experiments in my lab. Ray and I started to look for and find more general patterns associated with different kinds of glutamatergic input, focusing initially on what we knew of thalamic circuitry. We realized that these different patterns could be a basis for a straightforward classification of glutamatergic synapses. Following this notion, we concluded that these synapses could be divided into two quite different classes, which we called drivers and modulators, and we listed a number of parameters that could be used to distinguish them. Eventually, we published this perspective (Sherman and Guillery 1998). We tried to put it all together in a monograph, our first of three (Sherman and Guillery 2001). We continued to refine and expand our ideas in a series of reviews and thought pieces (Sherman and Guillery, 2002, 2004a, 2004b; Guillery and Sherman 2002a, 2002b), culminating in our last two monographs (Sherman and Guillery 2006, 2013).

After Ray and I established fairly clear hypotheses regarding first and higher order thalamic relays and drivers and modulators, my laboratory began an experimental plan designed to test these ideas. This was started at the end of my tenure at Stony Brook via a PhD thesis by my graduate student, Iva Reichova. She slightly adapted the mouse thalamocortical slice preparation pioneered by Ariel Agmon and Barry Connors (Agmon and Connors 1991) to demonstrate that the layer 5 input from barrel cortex (primary sensory cortex, or S1) to the posterior medial nucleus, a higher order thalamic relay, exhibits driver characteristics, just like retinogeniculate synapses, whereas layer 6 corticothalamic synapses show modulator properties (Reichova and Sherman 2004). This study also established a number of criteria to distinguish drivers from modulators; chief among them was the short-term plasticity—depression for drivers versus facilitation for modulators—and activation of both ionotropic and metabotropic glutamate receptors by modulators but only ionotropic receptors by drivers.

After its move to Chicago, my laboratory continued this research line as its main theme.

While a Faculty Member at Chicago

Transthalamic Pathways: The presence of transthalamic pathways (i.e., cortico-thalamo-cortical pathways involving higher order thalamic relays) has been a major theme of our work in Chicago. The clearest example of such a pathway was provided by two talented members of my laboratory: Brian Theyel, an MD-PhD student, and Dan Llano, a postdoctoral fellow who had been an MD-PhD student and just finished a residency in neurology. In brain slices from the mouse, they clearly demonstrated a transthalamic pathway from S1 through the posterior medial nucleus to S2 (Theyel et al. 2010). We also provided evidence for transthalamic pathways in the visual and somatosensory systems.

Based on these examples, there seemed to be a pattern: When a direct corticocortical connection exists (e.g., S1 to S2), there is also a transthalamic one (e.g., S1 to the posterior medial nucleus to S2). Currently, we are working to extend this to cortical areas beyond purely sensory ones. A good start beyond purely sensory circuits has been the work of a current postdoctoral fellow, Christina Mo, who has just demonstrated parallel direct and transthalamic pathways between S1 and the primary motor cortex, the transthalamic pathway involving the posterior medial nucleus.

This work has raised a number of questions we are currently focused on: How common is the pattern of parallel direct and transthalamic connections between cortical areas, or, how commonly are cortical areas connected by only one or the other? What is different in the information carried by each route? Why is one of these circuits relayed by thalamus?

Drivers and Modulators: Our work on drivers and modulators followed three main themes. One was to demonstrate the significance of this classification, another was to extend the classification from thalamus to cortex, and the last was to gain some understanding of the function of modulatory inputs. Regarding the last point, our hypothesis is that driver inputs carry the main information for circuits to work on, whereas the modulators affect how driver information is processed, much like the classical modulatory inputs (e.g., cholinergic, serotonergic, etc.). A key to all of these modulatory synapses is that they commonly activate metabotropic receptors; for instance, cholinergic inputs typically activate muscarinic receptors, which are metabotropic, and, as noted, the glutamatergic modulatory inputs activate metabotropic glutamate receptors. Activation of metabotropic receptors seems to be a key factor in providing modulatory functions for all of these inputs. However, a difference between classical versus glutamatergic modulatory systems is that the former is relatively diffusely organized and relates to overall behavioral stages, such as level of alertness, whereas glutamatergic modulators are the only ones with precise topography, which is needed for many processes such as spatial attention, adaptation, and so on.

I’m afraid at this point we may have introduced some terminological confusion to the subject. That is, I was concerned that our use of the terms “driver” and “modulator” suggested their functions—information bearing for driver and modulatory for modulator—a terminological approach that I have criticized earlier to favor “X” and “Y” as terms over “sustained” and “transient.” The driver/modulator functional hypothesis, while plausible and attractive, remains unproven. Therefore, we started calling these glutamatergic inputs “Class 1” (driver) and “Class 2” (modulator). I received some criticism for this, because the Class 1 and 2 terms confused people. So I’ve become inconsistent, going back and forth a bit: mea culpa. For clarity, I’ll stick to “driver” and “modulator” in the remainder of this piece, with the important proviso that the evocative functions for these classes remain a hypothesis.

An example of the importance of the classification is work first carried out mainly by Charles Lee, another postdoctoral fellow in my laboratory, who identified the properties of the glutamatergic inputs from the inferior colliculus to both the ventral and dorsal divisions of the medial geniculate nucleus (first and higher order, respectively). Conventional wisdom at the time held that these inputs represented links in parallel information streams through thalamus to cortex. Charles, however, showed that while input to the ventral division was all driver, and hence a likely information route, input to the dorsal division was all modulator, and so, instead of a parallel information route, the pathway to the dorsal division seems more likely to modulate the transthalamic pathway—that is, the pathway from primary auditory cortex through the dorsal division of the medial geniculate nucleus to the second auditory area (Lee and Sherman 2010). Thus, applying the driver/modulator classification changes rather dramatically the perspective of the functional organization of this part of the ascending auditory system.

Quite recently, work from a graduate student (Angela Viaene) and two postdoctoral fellows (Christina Mo and Iraklis Petrof) in my laboratory extended this analysis to the somatosensory inputs to thalamus in the mouse (Mo et al. 2017). (Angela and Iraklis formed quite a productive team in the laboratory, and furthermore joined together in matrimony and, recently, parenthood.) Here, the conventional view is that there are parallel information routes to cortex, the lemniscal one involving medial lemniscal input to the ventral posterior medial nucleus to S1, and the paralemniscal one involving input from the spinal nucleus of the fifth nerve to the posterior medial nucleus to S2. Although the lemniscal pathway is all driver, the paralemniscal input to thalamus is mostly modulatory, again suggesting that the conventional view needs rethinking.

Much of our effort has been devoted to extending the classification of glutamatergic pathways from thalamic circuits to cortical ones. Three postdoctoral fellows (Charles Lee, Roberto DePasquale, and Iraklis Petrof), a graduate student (Elise Covic), and an MD-PhD student (Angela Viaene) were critical to this effort (Lee and Sherman 2008, 2009; Covic and Sherman 2011; DePasquale and Sherman 2011; Viaene et al., 2011a, 2011b, 2011c; Lee and Sherman 2012; Petrof et al. 2015). Our expectation was that, when we investigated the more complex circuitry of cortex, we would identify classes in addition to drivers and modulators. We found instead that all glutamatergic pathways we could identify, both thalamocortical and corticocortical, easily fit into the driver or modulator category. However, we did find that driver pathways in cortex could further be divided into three subtypes. It now appears to us that there are two basic types of synaptic input seen in thalamus and cortex—the types we have identified as driver and modulator—and that the properties of each in thalamus mirror those in cortex.

Ideas Regarding Efference Copies: The final conceptual development from Ray and me relates to the speculative relationship between driver inputs to thalamus (i.e., the input relayed to cortex) and efference copies. Efference copies, also known as corollary discharges, are an essential feature of neuronal processing for any creature with complex behavior, because they enable the animal to disambiguate events in the environment from apparent environmental changes caused by the animal’s own behavior. A good example is eye movements: Every time we move our eyes, and we make roughly three saccades per second, the visual image of the outside world moves in the opposite direction on our retinas. Yet we don’t perceive the visual world as unstably spinning about—it remains stable. This is because a copy of the command to move the eyes is fed back into the visual processing stream so that the effects of the motion can be subtracted from our visual perception.

As I recall, the evolution of the ideas Ray and I developed on this subject was as follows. We were engaged in long-standing discussions about transthalamic pathways, and particularly the layer 5 parts of the circuits, when we belatedly had our attention drawn to a series of papers from the laboratory of Martin Deschênes, papers that described the morphology of layer 5 corticofugal exons from several cortical areas (Deschênes et al. 1994; Bourassa and Deschênes 1995; Bourassa et al. 1995; Levesque et al. 1996). Those axons that innervated thalamus as the first stage in transthalamic circuits all branched, some quite heavily, to innervate numerous other subcortical structures. This reminded me of an earlier study from my laboratory showing that all labeled retinogeniculate axons in the cat branched to innervate midbrain structures as well (Tamamaki et al. 1995).

Ray and I started to generalize and speculate. It seemed that many, and perhaps all, driver inputs to thalamus arrived via branching axons. This seems to be a clear anatomical fact for the relatively few examples that have been documented, but what does it mean? We struggled to come up with an explanation. One aspect of branching axons that seems clear is that this is arguably the most efficient and foolproof means of delivering exactly the same message, or more precisely, the same temporal pattern of action potentials, down all branches to multiple targets. This does not mean that all targets respond identically, because synaptic differences play a role here, but if the goal is to send multiple copies of a message from one neuron to many, using branching axons seems the best solution.

Thus, we reasoned, the message sent to thalamus for relay to cortex was in many cases, if not most or all cases, a copy of messages sent to multiple other subcortical targets. When we looked through the literature regarding these extrathalamic targets of these branched axons, lightbulbs went off: Many of these targets appear to be motor control centers, such as bulbospinal centers, and some of these layer 5 axons that branch to innervate thalamus are corticospinal neurons, directly innervating spinal circuits via these extrathalamic branches. Indeed, these layer 5 projections represent the one and only means for cortex to influence behavior by targeting older motor centers, and so these connections are plausibly considered to be motor messages or commands sent from cortex. It thus follows that the branches of these axons that target thalamus carry copies of the motor commands: This is a nice definition of an efference copy. It also follows that if cortex sends out motor commands via layer 5 corticofugal cells, which is the only known pathway for cortex to influence behavior, it logically follows that these commands must be accompanied by efference copies sent back into cortical processing centers involved with those commands. The branching of layer 5 corticothalamic axons provides a plausible neuronal substrate for this, and it is hard to imagine other likely pathways for such efference copies of cortical motor commands. Ray and I have written extensively about this—further details can be found there—and this remains an idea I hope to continue to develop, one that now dominates much of the thinking in my laboratory to design experimental tests of these ideas.

Coda

Writing this piece has been a real pleasure for me. I haven’t previously taken much time to ponder where I am in my life and how I got here, and preparing this brief autobiography has forced me to do so. It’s an exercise I recommend to everyone.

I’ve had a very successful and rewarding life and career as judged by the only arbiter who counts—me. How others view this is frankly of less concern to me. But in recollecting how I arrived at this point in my journey, I’ve come to appreciate how much blind but good luck has determined my fate. It is certainly humbling to come to appreciate just how much factors over which one has no control play in one’s ultimate fate. In my case, I have been extraordinarily lucky, something I have tried to document here.

My luck has been expressed both in terms of random incidents and people with whom I’ve interacted and collaborated. The two most important people have been my wife Marjorie and Ray Guillery. Interestingly, I met both the same year, 1968, and in each case that was the start of an ongoing and very successful collaboration. I am also very proud of the fact that most of the predoctoral and postdoctoral students who have passed through my laboratory went on to very successful scientific careers (see Table 1), which is more a testimony to my good luck in attracting them than any pixie dust I covered them with—indeed, it was their productivity in my laboratory that is the chief factor in my own professional success.

I often wonder what path I’d choose if I were a student today and had the same interest in science I did when I was young. Would my fascination with science and research and the attraction of an academic career be a sufficient drive to take the path I took when younger? Or would my current knowledge of the difficulties involved with that path, especially the shortage of both appropriate academic positions and government (read, NIH) funding, deflect me toward less risky paths, like medical or business school? I’d like to think I would take the risk, because of the wonderful and fulfilling career academic science offers and also because I don’t think I’d relish being a physician or businessman. I’ve tried to imagine what my answer would be, but I really don’t know.

But that’s all speculation, and the fact is that I’ve enjoyed a wonderful, fulfilling career. On reflection, it’s clear that, during my time in the field, neuroscience has made remarkable advances, and I feel good about playing some part in that. I have no plans to retire, because why should I stop doing what I enjoy so much? It’s as if I’m being paid rather handsomely for a hobby I’m passionate about. And I’m just as excited about the research ongoing in my laboratory as I ever was.

The trip has been well worth it.

Acknowledgments

I thank the following for offering useful advice on various drafts of this manuscript: Ruth Anne Eatock, Elizabeth Grove, Jason MacLean, and Marjorie Sherman.

References

Agmon A, Connors BW (1991) Thalamocortical responses of mouse somatosensory (barrel) cortex in vitro. Neurosci 41:365–379.

Andolina IM, Jones HE, Sillito AM (2013) Effects of cortical feedback on the spatial properties of relay cells in the lateral geniculate nucleus. J Neurophysiol 109:889–899.

Bourassa J, Deschênes M (1995) Corticothalamic projections from the primary visual cortex in rats: A single fiber study using biocytin as an anterograde tracer. Neurosci 66:253–263.

Bourassa J, Pinault D, Deschênes M (1995) Corticothalamic projections from the cortical barrel field to the somatosensory thalamus in rats: A single-fibre study using biocytin as an anterograde tracer. Eur J Neurosci 7:19–30.

Ciaramitaro VM, Todd WE, Rosenquist AC (1997) Disinhibition of the superior colliculus restores orienting to visual stimuli in the hemianopic field of the cat. J Comp Neurol 387:568–587.

Cleland BG, Dubin MW, Levick WR (1971) Sustained and transient neurones in the cat’s retina and lateral geniculate nucleus. J Physiol (Lond) 217:473–496.

Covic EN, Sherman SM (2011) Synaptic properties of connections between the primary and secondary auditory cortices in mice. Cereb Cortex 21:2425–2441.

Crick F (1984) Function of the thalamic reticular complex: The searchlight hypothesis. Proc Natl Acad Sci USA 81:4586–4590.

DePasquale R, Sherman SM (2011) Synaptic properties of corticocortical connections between the primary and secondary visual cortical areas in the mouse. J Neurosci 31:16494–16506.

Deschênes M, Bourassa J, Pinault D (1994) Corticothalamic projections from layer V cells in rat are collaterals of long-range corticofugal axons. Brain Res 664:215–219.

Enroth-Cugell C, Robson JG (1966) The contrast sensitivity of retinal ganglion cells of the cat. J Physiol (Lond) 187:517–552.

Fanselow EE, Sameshima K, Baccala LA, Nicolelis MAL (2001) Thalamic bursting in rats during different awake behavioral states. PNAS 98:15330–15335.

Friedlander MJ, Lin C-S, Sherman SM (1979) Structure of physiologically identified X and Y cells in the cat’s lateral geniculate nucleus. Science 204:1114–1117.

Friedlander MJ, Lin C-S, Stanford LR, Sherman SM (1981) Morphology of functionally identified neurons in the lateral geniculate nucleus of the cat. J. Neurophysiol 46: 80–129.

Friedlander MJ, Sherman SM (1981) Morphology of physiologically identified neurons. Trends in Neurosci 4:211–214.

Friedlander MJ, Stanford LR, Sherman SM (1982) Effects of monocular deprivation on the structure-function relationship of individual neurons in the cat’s lateral geniculate nucleus. J Neurosci 2:321–330.

Fukuda Y, Stone J (1974) Retinal distribution and central projections of Y-, X-, and W-cells of the cat’s retina. J Neurophysiol 37:749–772.

Guido W, Lu S-M, Vaughan JW, Godwin DW, Sherman SM (1995) Receiver operating characteristic (ROC) analysis of neurons in the cat’s lateral geniculate nucleus during tonic and burst response mode. Visual Neurosci 12:723–741.

Guillery RW (1969) A quantitative study of synaptic interconnections in the dorsal lateral geniculate nucleus of the cat. Z Zellforsch 96:39–48.

Guillery RW (1972) Binocular competition in the control of geniculate cell growth. J Comp Neurol 144:117–130.

Guillery RW (1995) Anatomical evidence concerning the role of the thalamus in corticocortical communication: A brief review. J Anat 187:583–592.

Guillery RW, Sherman SM (2002a) Thalamic relay functions and their role in corticocortical communication: Generalizations from the visual system. Neuron 33:163–175.

Guillery RW, Sherman SM (2002b) The thalamus as a monitor of motor outputs. Philos Trans R Soc Lond [Biol] 357:1809–1821.

Guillery RW, Sherman SM (2011) Branched thalamic afferents: What are the messages that they relay to cortex? Brain Res Brain Res Rev 66:205–219.

Guillery RW, Stelzner DJ (1970) The differential effects of unilateral lid closure upon the monocular and binocular segments of the dorsal lateral geniculate nucleus in the cat. J Comp Neurol 139:413–422.

Hamos JE, Van Horn SC, Raczkowski D, Sherman SM (1987) Synaptic circuits involving an individual retinogeniculate axon in the cat. J Comp Neurol 259:165–192.

Hamos JE, Van Horn SC, Raczkowski D, Uhlrich DJ, Sherman SM (1985) Synaptic connectivity of a local circuit neurone in lateral geniculate nucleus of the cat. Nature 317:618–621.

Hoffmann K-P, Stone J (1971) Conduction velocity of afferents to cat visual cortex: A correlation with cortical receptive field properties. Brain Res 32:460–466.

Hoffmann K-P, Stone J, Sherman SM (1972) Relay of receptive-field properties in dorsal lateral geniculate nucleus of the cat. J Neurophysiol 35:518–531.

Hu H, Agmon A (2016) Differential excitation of distally versus proximally targeting cortical interneurons by unitary thalamocortical bursts. J Neurosci 36:6906–6916.

Hughes A (1979) A rose by any other name… on “naming of neurones” by Rowe and Stone. Brain Behav Evol 16:52–64.

Humphrey AL, Sur M, Uhlrich DJ, Sherman SM (1985a) Projection patterns of individual X- and Y-cell axons from the lateral geniculate nucleus to cortical area 17 in the cat. J Comp Neurol 233:159–189.

Humphrey AL, Sur M, Uhlrich DJ, Sherman SM (1985b) Termination patterns of individual X- and Y-cell axons in the visual cortex of the cat: Projections to area 18, to the 17-18 border region, and to both areas 17 and 18. J Comp Neurol 233:190–212.

Jahnsen H, Llinás R (1984a) Electrophysiological properties of guinea-pig thalamic neurones: An in vitro study. J Physiol (Lond) 349:205–226.

Jahnsen H, Llinás R (1984b) Ionic basis for the electroresponsiveness and oscillatory properties of guinea-pig thalamic neurones in vitro. J Physiol (Lond) 349:227–247.

Kitai ST, Kocsis JD, Preston RJ, Sugimori M (1976) Monosynaptic inputs to caudate neurons identified by intracellular injection of horseradish peroxidase. Brain Res 109:601–606.

Lee CC, Sherman SM (2008) Synaptic properties of thalamic and intracortical inputs to layer 4 of the first- and higher-order cortical areas in the auditory and somatosensory systems. J Neurophysiol 100:317–326.

Lee CC, Sherman SM (2009) Modulator property of the intrinsic cortical projection from layer 6 to layer 4. Front Syst Neurosci 3:1–5.

Lee CC, Sherman SM (2010) Topography and physiology of ascending streams in the auditory tectothalamic pathway. Proc Nat Acad Sci USA 107:372–377.

Lee CC, Sherman SM (2012) Intrinsic modulators of auditory thalamocortical transmission. Hear Res 287:43–50.

Lee-Teng E, Sherman SM (1966) Memory consolidation of one-trial learning in chicks. Proc Natl Acad Sci USA 56:926–931.

Lehmkuhle S, Kratz KE, Sherman SM (1982) Spatial and temporal sensitivity of normal and amblyopic cats. J Neurophysiol 48:372–387.

Lehmkuhle S, Sherman SM, Kratz KE (1984) Spatial contrast sensitivity of dark-reared cats with striate cortex lesions. J Neurosci 4:2419–2424.

Lesica NA, Stanley GB (2004) Encoding of natural scene movies by tonic and burst spikes in the lateral geniculate nucleus. J Neurosci 24:10731–10740.

Lesica NA, Weng C, Jin J, Yeh CI, Alonso JM, Stanley GB (2006) Dynamic encoding of natural luminance sequences by LGN bursts. Plos Biol 4:e209.

Levesque M, Gagnon S, Parent A, Deschênes M (1996) Axonal arborizations of corticostriatal and corticothalamic fibers arising from the second somatosensory area in the rat. Cereb Cortex 6:759–770.

McCormick DA, Von Krosigk M (1992) Corticothalamic activation modulates thalamic firing through glutamate “metabotropic” receptors. Proc Natl Acad Sci USA 89:2774–2778.

Mo C, Petrof I, Viaene AN, Sherman SM (2017) Synaptic properties of the lemniscal and paralemniscal pathways to the mouse somatosensory thalamus. Proc Nat Acad Sci USA. 114: E6212–E6221.

Norton TT, Casagrande VA, Sherman SM (1977) Loss of Y-cells in the lateral geniculate nucleus of monocularly deprived tree shrews. Science 197:784–786.

Ortuno T, Grieve KL, Cao R, Cudeiro J, Rivadulla C (2014) Bursting thalamic responses in awake monkey contribute to visual detection and are modulated by corticofugal feedback. Front Behav Neurosci 8:198.

Petrof I, Viaene AN, Sherman SM (2015) Properties of the primary somatosensory cortex projection to the primary motor cortex in the mouse. J Neurophysiol 113:2400–2407.

Ramcharan EJ, Gnadt JW, Sherman SM (2005) Higher-order thalamic relays burst more than first-order relays. Proc Nat Acad Sci USA 102:12236–12241.

Reichova I, Sherman SM (2004) Somatosensory corticothalamic projections: Distinguishing drivers from modulators. J Neurophysiol 92:2185–2197.

Rowe MH, Stone J (1977) Naming of Neurones: Classification and naming of cat retinal ganglion cells. Brain Behav Evol 14:185–216.

Sanderson KJ, Sherman SM (1971) Nasotemporal overlap in visual field projected to lateral geniculate nucleus in the cat. J Neurophysiol 34:453–466.

Sherman SM (1973) Visual field defects in monocularly and binocularly deprived cats. Brain Res 49:25–45.

Sherman SM (1974) Monocularly deprived cats: Improvement of the deprived eye’s vision by visual decortication. Science 186:267–269.

Sherman SM (1996) Dual response modes in lateral geniculate neurons: Mechanisms and functions. Visual Neurosci 13:205–213.

Sherman SM, Guillery RW (1976) Behavioral studies of binocular competition in cats. Vision Res 16:1479–1481.

Sherman SM, Guillery RW (1996) The functional organization of thalamocortical relays. J Neurophysiol 76:1367–1395.

Sherman SM, Guillery RW (1998) On the actions that one nerve cell can have on another: Distinguishing “drivers” from “modulators.” Proc Natl Acad Sci USA 95:7121–7126.

Sherman SM, Guillery RW (2001) Exploring the Thalamus. San Diego, CA: Academic Press.

Sherman SM, Guillery RW (2002) The role of thalamus in the flow of information to cortex. Philos Trans R Soc Lond [Biol] 357:1695–1708.

Sherman SM, Guillery RW (2004a) Thalamus. In: Synaptic Organization of the Brain (Shepherd GM, ed), pp 311–359. Oxford: Oxford University Press.

Sherman SM, Guillery RW (2004b) The visual relays in the thalamus. In: The Visual Neurosciences (Chalupa LM, Werner JS, eds), pp 565–591. Cambridge, MA: MIT Press.

Sherman SM, Guillery RW (2006) Exploring the Thalamus and Its Role in Cortical Function. Cambridge, MA: MIT Press.

Sherman SM, Guillery RW (2011) Distinct functions for direct and transthalamic corticocortical connections. J Neurophysiol 106:1068–1077.

Sherman SM, Guillery RW (2013) Thalamocortical Processing: Understanding the Messages that Link the Cortex to the World. Cambridge, MA: MIT Press.

Sherman SM, Guillery RW (2014) The lateral geniculate nucleus and pulvinar. In: The New Visual Neurosciences (Chalupa LM, Werner JS, eds), pp 257–283. Cambridge, MA: MIT Press.

Sherman SM, Guillery RW, Kaas JH, Sanderson KJ (1974) Behavioral, electrophysiological and morphological studies of binocular competition in the development of the geniculo-cortical pathways of cats. J Comp Neurol 158:1–18.

Sherman SM, Hoffmann K-P, Stone J (1972) Loss of a specific cell type from dorsal lateral geniculate nucleus in visually deprived cats. J Neurophysiol 35:532–541.

Sherman SM, Norton TT, Casagrande VA (1975a) X- and Y-cells in the dorsal lateral geniculate nucleus of the tree shrew (Tupaia glis). Brain Res 93:152–157.

Sherman SM, Sanderson KJ (1972) Binocular interaction on cells of the dorsal lateral geniculate nucleus of visually deprived cats. Brain Res 37:126–131.

Sherman SM, Wilson JR, Guillery RW (1975b) Evidence that binocular competition affects the postnatal development of Y-cells in the cat’s lateral geniculate nucleus. Brain Res 100:441–444.

Sprague JM (1966) Interaction of cortex and superior colliculus in mediation of visually guided behavior in the cat. Science 153:1544–1547.

Stanford LR, Friedlander MJ, Sherman SM (1981) Morphology of physiologically identified W-cells in the C laminae of the cat’s lateral geniculate nucleus. J Neurosci 1:578–584.

Steriade M (2001) To burst, or rather, not to burst. Nat Neurosci 4:671.

Stone J, Dreher B (1973) Projection of X- and Y-cells of the cat’s lateral geniculate nucleus to areas 17 and 18 of visual cortex. J Neurophysiol 36:551–567.

Stone J, Hoffmann K-P (1971) Conduction velocity as a parameter in the organisation of the afferent relay in the cat’s lateral geniculate nucleus. Brain Res 32:454–459.

Sur M, Frost DO, Hockfield S (1988) Expression of a surface-associated antigen on Y-cells in the cat lateral geniculate nucleus is regulated by visual experience. J Neurosci 8:874–882.

Sur M, Humphrey AL, Sherman SM (1982) Monocular deprivation affects X- and Y-cell retinogeniculate terminations in cats. Nature 300:183–185.

Sur M, Sherman SM (1982) Retinogeniculate terminations in cats: Morphological differences between X and Y cell axons. Science 218:389.

Sur M, Weller RE, Sherman SM (1984) Development of X- and Y-cell retinogeniculate terminations in kittens. Nature 310:246–249.

Swadlow HA, Gusev AG, Bezdudnaya T (2002) Activation of a cortical column by a thalamocortical impulse. J Neurosci 22:7766–7773.

Tamamaki N, Uhlrich DJ, Sherman SM (1995) Morphology of physiologically identified retinal X and Y axons in the cat’s thalamus and midbrain as revealed by intra-axonal injection of biocytin. J Comp Neurol 354:583–607.

Theyel BB, Llano DA, Sherman SM (2010) The corticothalamocortical circuit drives higher-order cortex in the mouse. Nat Neurosci 13:84–88.

Van Horn SC, Erişir A, Sherman SM (2000) The relative distribution of synapses in the A-laminae of the lateral geniculate nucleus of the cat. J Comp Neurol 416:509–520.

Viaene AN, Petrof I, Sherman SM (2011a) Properties of the thalamic projection from the posterior medial nucleus to primary and secondary somatosensory cortices in the mouse. Proc Nat Acad Sci USA 108:18156–18161.

Viaene AN, Petrof I, Sherman SM (2011b) Synaptic properties of thalamic input to layers 2/3 in primary somatosensory and auditory cortices. J Neurophysiol 105:279–292.

Viaene AN, Petrof I, Sherman SM (2011c) Synaptic properties of thalamic input to the subgranular layers of primary somatosensory and auditory cortices in the mouse. J Neurosci 31:12738–12747.

Wallace SF, Rosenquist AC, Sprague JM (1990) Ibotenic acid lesions of the lateral substantia nigra restore visual orientation behavior in the hemianopic cat. J Comp Neurol 296:222–252.

Whitmire CJ, Millard DC, Stanley GB (2017) Thalamic state control of cortical paired-pulse dynamics. J Neurophysiol 117:163–177.

Wiesel TN, Hubel DH (1963a) Effects of visual deprivation on morphology and physiology of cells in the cat’s lateral geniculate body. J Neurophysiol 26:978–993.

Wiesel TN, Hubel DH (1963b) Single-Cell responses in striate cortex of kittens deprived of vision in one eye. J Neurophysiol 26:1003–1017.

Wiesel TN, Hubel DH (1965) Comparison of the effects of unilateral and bilateral eye closure on cortical unit responses in kittens. J Neurophysiol 28:1029–1040.

Wilson JR, Friedlander MJ, Sherman SM (1984) Fine structural morphology of identified X- and Y-cells in the cat’s lateral geniculate nucleus. Proc Roy Soc Lond B 221:411–436.

¹See Interdimensional Transmissions, http://interdimensionaltransmissions.com/artists/erika, and Resident Advisor, https://www.residentadvisor.net/dj/erika.

²See Etiquette School, “Banana, Plantain Etiquette,” https://www.etiquettescholar.com/dining_etiquette/table_manners/dinner_etiquette/fruits/bananas.html.

³Society for Neuroscience, “Member Obituaries: Rainer W. Guillery,” http://www.sfn.org/Member-Center/Member-Obituaries/GM/Ranier-W-Guillery.

Douglas G. Stuart

BORN:

Casino, New South Wales (NSW), Australia

October 5, 1931

EDUCATION:

Sydney Teachers’ College, NSW, DPE (1950)

Michigan State University (MSU), BS, MA (1955, 1956)

University of California-Los Angeles (UCLA), PhD, Postdoctoral (1961, 1963)

APPOINTMENTS:

NSW Department of Secondary Education: Teacher, Hurlstone Agricultural High School, Sydney (1951–1953)

MSU: Graduate Research/Teaching Assistant (1955–1956)

UCLA: Postdoctoral Fellow, Department of Anatomy (1961–1963); Assistant Research Professor, Department of Physiology (1963–1965)

UC-Davis: Associate Professor, Department of Physiological Sciences (1965–1967)

University of Arizona (UA): Associate Professor (1967–1970), Professor (1970–2002), Head (1988–1991) of Physiology; Regents’ Professor of Physiology (1990–2002), Regents’ Professor Emeritus of Physiology (1992–present)

HONORS AND AWARDS (SELECTED)

USPHS Predoctoral Fellow, UCLA Mental Health Training Program: Mentor Professor Allan Hemingway, Department of Physiology (1959–1961)

Postdoctoral Medical Research Fellow, Bank of America-Giannini Foundation: Mentor, Professor Earl Eldred, Department of Anatomy, UCLA (1961–1963)

USPHS Special Research Fellowship: Studies with Professor Anders Lundberg, Department of Physiology, University of Göteborg, Sweden (1971–1972)

Guggenheim Fellowship: Studies with Dr. David Burke, Unit of Neurology, University of New South Wales (1976–1977)

Honoree at “Pre-festschrift” Symposia, University of Arizona (1998) and Phoenix (2007)

Honorary DSc degree, University of Arizona (2011)

Lifetime Achievement Award, International Motoneuron Society (2012)

Douglas Stuart led the charge at the University of Arizona for interdisciplinary programs in neuroscience and physiological sciences and the recruitment of an invertebrate neurobiology group. He also facilitated the recruitment of a learning and memory group, and an interdisciplinary program in biomedical engineering. Throughout Arizona and beyond, he promoted the development of movement neuroscience research and training. His 1959–2006 experimental research focused on spinal motor mechanisms and their relation to tremors, locomotion, muscle fatigue, and the overall control of movement. In recent years, he has continued to provide overviews on motor control and the history of movement neuroscience.

Douglas G. Stuart

Australian Background

My early attitudes and behavior had much to do with being a fourth-generation Australian. My father, Gordon Khartoum Stuart (1900–1933) and his eight siblings were in a family whose activities were traced in recent times back to 1137, when they owned land in the Scottish Highlands north of Inverness. This land was lost in 1746 after the Battle of Culloden near Inverness, where troops of the British government soundly defeated the largely Scottish Jacobean rebels. My ancestors who took part in this uprising were forced to flee down the west coast of Scotland to the Peninsula of Ardnamurchan above the Isle of Mull. They settled there as poor sheepherders in a location known to this day as Bourblaige, named by earlier Scandinavian invaders. My family remained there until 1839, when the opportunity arose to have free passage to Sydney, Australia. The British government (and the Presbyterian Church to some extent) made 20 ships available to Scottish Presbyterians and some Roman Catholics. These included poor highlanders like my Ardnamurchan family, which then consisted of a husband, wife, and five children. They arrived without incident in Sydney in January 1840, where they all passed a government-controlled reading and writing test. Such free-passage immigrants were frequently given the same opportunity offered to selected convicts who had completed their sentence there: work for a farmer for up to 10 years and then be granted by the government a generous allotment of arable land. (See chapters one and two in Megalogenis [2015] for the more liberal treatment of “farming” convicts during the earlier days of the food-deficient NSW settlement under Governors Arthur Phillip [1738–1814] and Lachlan Macquarie [1762–1824]).

My Stuart family forbears spent several years working first for a farmer in Raymond Terrace, 16 miles north of Newcastle and 116 miles north of Sydney. They then spread out in the Raymond Terrace, near the Port Stephens area working largely on farms owned by others. In 1857, they rented and later owned (by the late 1890s) a farm on the banks of Carr’s Creek, about 2 miles north of the town of Grafton and 20-plus miles southwest of the village of Maclean and town of Yamba, a Pacific Ocean resort, about 420 miles north of Sydney. The farm was suitable for dairying and for growing maize and sugar cane. I have no record of whether or not they received government assistance for the purchase of this farm. Thus, my father and his eight siblings were born in Maclean or Grafton and raised in an attractive rural area near the Pacific Ocean.

In contrast, my mother, Martha Monteith Stuart (1901–1996), and her eight siblings in the Monteith family were of Northern Irish and English/Australian extraction. Her father, Joseph Monteith (1853–1925), had emigrated with assisted passage from Londonderry, North Ireland to Sydney in 1872. By dint of hard work, probably native common sense and intelligence, and much drive, he developed a successful 1,200-acre property, which he named the Red Bank Farm. It was 3 miles outside Guyra, a small town about 24 miles north of the larger town of Armidale in the Northern Tablelands of New South Wales (NSW) about 300 miles north west of Sydney. It was here that my mother attended primary school in Guyra (riding most happily there and back with two siblings on a horse) and high school in Armidale. Her mother, Elizabeth Willis Monteith (1857–1950), a first-generation Australian, was of English background. Her first husband, Richard Moore, whom she married in 1880, was also of English origin. He died in 1887 leaving her with three children to whom six were added after her second marriage to Joe Monteith in 1888. From all accounts, my Londonderry grandfather was well known in Guyra and Armidale for his colorful personality and strong-mindedness about most issues.

Early Family Life (1931–1947)

I was born in the Richmond Private Hospital, which was located in Casino, a small, attractive town located in the northeast coastal area of NSW. This hospital was owned and run by my aunt, Chrissie Stuart, who was a registered nurse. A local doctor, Dudley Small, delivered me. He was married to Chrissie’s sister, my Aunt Jessie, who also had once been a registered nurse. I had much contact with her until leaving for America in late 1953.

My mother was widowed one and a half years after my birth, leaving her to raise her two young children, the other my brother Ian, who was two and a half years older. We lived 20 miles east of Casino in the larger town of Lismore, which is 460 miles north-northeast of Sydney, and 22 miles west of the Pacific Ocean. At that time, Lismore had a population of about 7,000 people, in contrast to the more than 40,000 people who live there today.

My father had been rising rapidly in local government in Lismore before his death at a young age in 1933, due possibly to rheumatic heart disease. In 1927, after his marriage to my mother in Kyogle, a small town 20 miles north of Casino, he had become the shire clerk (equivalent to a U.S. county manager) of the Gundarimba Shire, which extended in rich agricultural land southeast from Lismore toward the ocean. As a youngster, I took pride in what was written in obituaries about him, and what was told to me by his close friends—he was a pleasant, effective, and well-regarded shire clerk; popular with other administrative constituencies and his many friends; an excellent cricketer and good golfer; and clearly headed for a rapid rise in local government to much larger shires or possibly toward a political career in the conservative, farmer-focused Australian Country Party. My mother dearly loved and admired him and remained that way throughout her entire life, which extended until a few weeks before the age of 96. She had been a graduate of Sydney Teachers’ College and a primary school teacher in Kyogle where she met and married my father. After his death, she returned to teaching, much later in Sydney becoming for a short time, albeit reluctantly, a primary school principal.

Our home was about a mile from the center of Lismore, adjacent to the town golf course, which my father had helped found, and with views of attractive green hills, many covered with pineapple and banana plants. Our home was constructed of wood, and like many in Lismore, it was elevated a few feet above the ground to allow circulation for home cooling in the semitropical climate. Multicolored hydrangea plants concealed the space between the ground and our home’s base. The front and backyard grass was very green and fast growing. One of my jobs as a youngster was to reluctantly mow the grass twice a week under the watchful eye of my much bigger and stronger brother. Outside the town, there were patches of rain forest. As youngsters, my friends and I bicycled there on weekends for a swim in their rock pools. All in all, it is hard to imagine a more attractive Australian rural town than was Lismore in the 1930s and 1940s, and its nearby beaches.

In the early to late 1930s, a Scottish orphan, Mary, lived in our home, arriving at the age of 17 as an economic migrant, following free ship passage from Scotland. While treated as a relative of ours, Mary’s low-salaried responsibilities were to look after my brother and me and to do much of the housework and cooking. My brother and I dearly loved Mary, who was very vivacious and spent much time with us. She later married a local journalist and then lived happily in Lismore with her own family. This turn of events was much to the delight of my mother, Ian, and me. I mention this because Mary’s story had a very strong effect on me—the start of a lifelong empathy and support for financially poor immigrants irrespective of the countries involved in their emigration desire, and the process involved in their immigration.

As for my mother, she was an attractive, scholarly, hardworking, and vivacious person, with several close friends, a great sense of humor and usually fun loving, which made our home a popular one for my brother’s and my friends from throughout our childhood to young adulthood. Later, she had similar close relationships with my brother’s family in Sydney, and much later was greatly admired and liked by my American wife and our four children.

Up to the mid-1940s and particularly on the weekends, the focus in our Lismore home was on reading, with each of the three of us in a different room or on a verandah reading all manner of books. I still remember the full name and conversations with the main librarian at the Lismore Municipal Library in the late 1930s.

When Ian and I were quite young, our mother took us on long hikes in the hills around Lismore, and arranged holidays for us at local beaches during school breaks. Early on, we also had two December weeks in a suburb of Newcastle, 400 miles south of Lismore where one of her married sisters lived. Later, when Ian was in his very early teens, she went alone to Newcastle in December for two or three weeks to see this sister, leaving us to delightfully fend for ourselves in a tent at a local beach. There we body surfed all day with other young teenagers who had similar tents, including some of our Lismore friends.

Superimposed on all of this was our mother’s strong desire that we take schoolwork extremely seriously, this being of great ease and interest to my brother, but of less concern to me throughout high school. This was a great and permanent disappointment to my mother, even after she visited the University of California, Los Angeles (UCLA) many years later for my PhD thesis defense.

What I admired most about my mother was her strong personal commitment to social fairness and insistence that Ian and I should always behave with societal concern. She was deeply religious and in later years did much volunteer administrative work for the Presbyterian Church in Sydney. However, she never tried to indoctrinate her religious beliefs into her two children. In return, Ian and I attended Sunday school and a church service with her the same day until we graduated from high school in Lismore, because we knew this pleased her.

There was, however, an intermittent sad side to my mother, which had a very strong, lifelong effect on me and influenced my much later behavior as an academician. She greatly missed my father and considered his early demise the one great tragedy in her life. When I was about six years of age, we walked one weekend day to the Lismore churchyard where my father was buried, about two miles from our home. I sat on the concrete bed of his gravestone and watched my mother as she cleared weeds from around it, crying softly and mournfully. Without speaking to her, I contemplated her intermittently sad behavior and vowed to go through life with a consistently cheerful and positive attitude no matter what was to befall me. This I have done consistently, despite several reverses, which were invariably of my own making.

My brother Ian was an outstanding high school student, particularly in mathematics, and he topped this subject in the NSW five-year Leaving Certificate, which was the university entrance examination. He also had some close friends in high school, a good sense of humor (some called it odd), was a renowned rugby footballer, and a feared street fighter. He gained notoriety by breaking the nose of a well-known bully, two years ahead of him in high school. Later, much to my mother’s horror, Ian thrashed a street thug who had tried to enter a school dance.

In much later years, Ian and I discussed how many good times we had had as youngsters in Lismore, and how much of this was due to our mother’s total commitment to us. This included, I am ashamed to now confess, her pleasure in bringing me breakfast in bed until I left for the United States in late 1953 at the age of 22. The reader can imagine my future American wife’s reaction when she learned of this behavior.

Kindergarten–Grade 11 Schooling (1935–1947)

The quality of teaching could be very high in rural towns in NSW up to the early 1960s. Many teachers wished to work in Sydney for its cultural and other advantages. Those who wished to do this were rotated through the rural towns before achieving this goal. As a result, one’s education in a place like Lismore could be as advanced as that in Sydney. I, for example, was doing differential equations in my fourth year of high school when barely 15. This quality of instruction and demand for advanced student performance in mathematics was matched in my other high school subjects; in all for me, English, French, Latin, history, math I and II, chemistry, and physics for high school years one to three, with two subjects dropped for years four and five (Latin and history by me) when the focus was exclusively on six subjects for university entrance. Strangely and sadly, however, the local culture was for boys not to take biology courses, these being for girls, and girls alone. I have no knowledge of when this absurd fashion changed.

I still remember the name and physical features of my kindergarten teacher, and many of the subsequent elementary (grades one–six) school ones, too. They were strict in a nonthreatening way, and seemed to me at that time to be very committed when imparting their knowledge. The single exception to strictness was my sixth-grade primary school teacher. He was younger, friendlier, and more personable and intimate with his class than was usual at that time. At the beginning of the school year, he told us he was very religious and had “known God for 14 years.” However, by the mid-year, he was writing letters to the local newspaper claiming to be Lismore’s only Communist and first public atheist. In class, we had great fun with him when one of us had to stand facing our classmates, and recount a feature of our life, or show the ability to express strong emotions like happiness, fear, and rage. In return, our classmates would comment boisterously on the quality of our presentation. This teacher taught us our academic material quite well, but when we went on to high school, some of my classmates and especially I continued our rowdy ways, which were far less tolerated in the serious precollege environment.

For me, a serious flaw in rural high school education at that time was the lack of career counseling. The number of options seemed very few to me: become a teacher, engineer, or clinician. None appealed to me. From elementary school onward, I was a staunch Republican: that is, a person who believed that Australia should secede from the British Empire and, as a republic, trade with our neighboring countries. In retrospect, I first felt this way based on my Scottish origin, but by high school, I had read much about the United States, its history in becoming a republic, and its multiple ways of life. How I could use my republican beliefs in an interesting career in Australia was a puzzle for me, except for the vague thought that I might eventually become a politician. I discussed this with no one, and it may help explain my casual approach to high school work, which greatly frustrated my mother, and my teachers, particularly those in mathematics, who thought I would perform as well and be as committed to this subject as my brother, who was two years ahead of me. Indeed, the only teachers who tolerated me were those interested and supportive of my performance as an athlete, which is discussed later. However, I had the strong support of my brother, who always, indeed throughout his lifetime, thought that down the road I would achieve much in something or other. Even in his own case, however, and despite his academic success in high school, he was given bad local advice, and began his university training in engineering, when mathematics and physics would have been far more appropriate for his interests.

Despite my lackadaisical approach to high school education, I did sufficiently well in university entrance exams to be awarded a university scholarship, which could be applied to any field. However, two months before the early December examinations for the five-year High School Certificate, when I was barely 16, a calamity beset our family. My brother had a manic bipolar incident in Sydney near the end of his second-year university courses. I was told nothing about the details, except for the fact that he had been committed to a mental hospital. My mother left immediately for Sydney to grasp the full details of his mental health status, secure a new teaching position there, and find a house for us to live in. I remained in Lismore, studying intensely for my final high school examinations. Then, in early January 1948, I left the nirvana of Lismore and the far north coast of NSW for an uncertain future in Sydney, particularly in relation to the problem that had beset my brother.

Sydney Teachers’ College (1948–1950)

My vow to remain cheerful was severely challenged after I arrived in Sydney and visited my brother at the mental hospital where he was incarcerated. It was a truly ghastly place, and he told me he was being given electroconvulsive shock therapy that could ruin his brain. This was true at that time, the refinement of such treatment not occurring until much later.¹ It was also painfully obvious that no one in the Stuart or Monteith family was going to help solve the problem of why and how my brother had been put in a mental hospital, or how to get him out. Like most large former farming families at that time, the adults in the Stuart and Monteith families ranged from uneducated laborers at one end of the economic and social spectrum to doctors, lawyers, and other prominent folk at the other. None of them seemed interested in Ian’s calamity. His incarceration was beyond my mother’s capability, and my Aunt Jessie, an ex-nurse who could have been of great help, was still up north in Casino, managing her business affairs. It would be up to me, at barely the age of 16, to solve Ian’s problem, and I quickly developed a strategy to do this. But how could I bring about my strategy while beginning an intense university program?

What seemed best for me academically at that time was a major in economics or political science and a minor in mathematics, but it would be too demanding for the strategy I had in mind. Also, I had to earn my keep, easiest done with some type of college scholarship that gave me adequate time to get my brother out of the hospital for short periods to give his doctors confidence that he could be released from incarceration. Thus, I chose a three-year Diploma in Physical Education (PE), the well-paid scholarship for which was funded by the NSW Department of Education in return for five subsequent years of high school teaching. It was quite competitive, being limited each year at that time to 20 females and 20 males, with 15 of the latter having to be former World War II (WWII) servicemen with repatriation benefits equivalent to the GI bill in the United States. I was certainly attracted to the PE field by virtue of my enthusiasm for the state’s support of national fitness camps, which I have discussed previously in the Living History Project of the American Physiological Society.² Ironically, my becoming a neuroscientist and subsequently having a very fulfilling all-round life in the United States was due to my decision to enter a college program in PE.

To get my brother out of hospital for brief periods, I enlisted the help of a much older married cousin with children. He was a welder by trade and on the weekends made extra money in his own welding shop. He was an ex-serviceman who had fought in the demanding New Guinea campaign near the end of WWII and had much sympathy for those of his army unit who had been subject to shell shock. Ian’s doctors were quite willing for this cousin to take my brother out on Saturdays, accompanied by me. He, as an ex-serviceman, was widely respected by all, including Ian’s doctors. This was in contrast to me, a callow 16-year-old about to become a college student.

After a few Saturdays, my cousin convinced the doctors that I, while only 16, could take Ian out alone. Once this was achieved, I cut college classes as much as was possible and took my brother out several times a week to all kinds of interesting places; historical and science museums, art galleries, harbor rides to the zoo and Manly Beach, sports events, and Chinese and Italian restaurants. This was necessary for just a few weeks and after much harping by me to his doctors, and further support from my welder cousin, Ian was released from hospital. He immediately went to work for a government research agency with which he stayed successfully for his entire professional life, while also returning to the University of Sydney for a BS and MS in mathematics and physics and an MS in applied mathematics from the University of Cambridge. Despite two or three subsequent minor bipolar hiccups, he also had a fine married life, with a very intelligent, sensible, and friendly wife, and three children who have excelled in their adult professions.

Although my strategy and actions had been a success for Ian, they had a bad effect on me. Without mentioning it to anybody, I became far too confident that I had the ability to solve difficult problems without advice from anybody. This internal arrogance led to many errors of judgment in subsequent years.

With Ian’s problem seemingly solved by mid-1948, I elected to stay in the PE program, which was interesting in many ways. First, I appreciated the teaching faculty’s primary interest being their subject matter rather than how individual students were reacting to their material, as seemed to be the case in my high school years. Instruction in English was as outstanding as it had been in high school, and even more enjoyable, this also being a feature in physics. In contrast, educational theory seemed trivial despite the efforts of several truly earnest, well meaning, and likeable faculty. A major disappointment was the teaching of exercise science, biomechanics, and kinesiology. This surprised me, because the Australian U.S.-trained instructor who headed the PE program had written an interesting textbook on the physiology of exercise.

In many nonclassroom ways, three college years in PE was a maturing and unforgettable experience. I had two close post–high school friends in the PE program, with whom I had many adventures: hitchhiking for hundreds of miles in different directions while on class breaks; body surfing at the marvelous Sydney beaches; classes at a private sector central Sydney gymnasium under the tutelage of a famous instructor, who taught tumbling and trampoline gyrations to well-known dancers, divers, and gymnasts; and interacting with “White Russian” immigrants of many ages at their lively post WWII club in central Sydney.³

In college, I associated with hard-bitten ex-servicemen, who were my senior by many years. I greatly respected those who had actually fought for Australia in WWII against Nazi Germany, Italy, Vichy France, and Japan. One such person, who was the oldest in my PE class, took a particular interest in one of my college friends and me, and he often found odd jobs for us where we could make some money while attending all of our college classes. He had been a laborer before the start of WWII in 1939. He enlisted immediately and spent the next six years as an infantryman in the volunteer portion of the Australian Imperial Force (2nd AIF; see Lambert 1951), which often had disastrous battles. He told us that the worst part was seeing so many of his army unit die during this long ordeal. Nonetheless, he was quite upbeat in college and was looking forward to post–college life as a high school teacher rather than as a laborer. From this fine person, I developed a lifelong enthusiasm for the concept of “Up from the ranks,” and I still try to help such people, particularly disadvantaged college students at my university.

The second ex-serviceman for whom I had much empathy was two years ahead of me in college. He had been a tailgate gunner in a bomber, which made raids over Germany in the 1944 to May 1945 stage of WWII. He had been the sole survivor of four consecutive plane crashes on English airfields after returning from such raids. He, when a high school PE teacher, arranged for me to have an after-class job in a Police Boys’ Club as a gymnastics instructor for 10- to 14-year-olds. This was the best-paying and most enjoyable after-school job I had while in the PE program. It left me with tremendous respect for Police Boys’ Clubs, which are quite prevalent and effective in the United States, and it reinforced the irony of life, me too young to fight in WWII, and the tailgate gunner a victim of its horrors.

Hurlstone Agricultural High School (1951–1953)

My state-supported college funding required that I subsequently teach for three rather than five years because after graduation I was assigned to Hurlstone Agricultural High School on the southwest outskirts of Sydney. This well-known school had 500 students, 250 there by day, and 250 boarders. They ranged in age from 12 to 18 for largely a five-year course of study. While I was in college, there had been many discipline problems among the boarders. A decision was made by the NSW Department of Secondary Education to hire two PE teachers who would work long hours four days per week, with both there on Wednesday, when there was a city-wide sports program in the afternoon. Our combined goal was to (1) give traditional 40-minute PE classes throughout the classroom day, (2) solve the boarder discipline problem with much emphasis on post-class physical activities, (3) improve the Wednesday afternoon sports program of all students not engaged in interschool sports, and (4) get the interschool sports competition back on track.

My partner in this venture was a very likeable and well-known halfback on a renowned rugby football team. We worked together harmoniously and enjoyably for the three years I was at Hurlstone. In addition, we contributed to the camaraderie of our group of four or five teachers who lived at the school in a plain multibedroom house to attend to the needs and discipline of the 250 boarders. Because of this extra work, we all owed the state three rather than five years of teaching. Another benefit was that our room and board was free and available seven days a week for the entire year.

In addition to my PE assignments I took it upon myself to teach folk dancing to the boarders, a shock to these “aggie” students and their visiting parents, and to produce plays. In 1953, one of my productions with 15- and 16-year-old boys won a citywide competition (my one-act version of Maxwell Anderson’s 1935 “Winterset,” which addressed the 1920–1927 Saccho-Vanzetti case). This experience is still a vivid and particularly enjoyable memory of my high school teaching days.

Transition from Australia to the United States

Despite the many successes that my colleague and I had in meeting our objectives as high school PE teachers and how enjoyable the student contact and experience were, I realized by late 1952 that my main interest in the students was how they performed their various physical activities—that is, the physiology and biomechanics of their exercise movements. This convinced me that the time had come to secure a track and field scholarship to attend a college in the United States. After WWII, this type of scholarship became known in Australia, particularly for elite swimmers. My plan was to undertake a BS and MS in PE and exercise physiology and then return to Australia to a university position. At that stage, I had no knowledge or concern about the role that research might play in this plan.

My next step involved writing to the presidents of several universities in the United States and explaining my ambitions. A few weeks later, I heard from several track and field coaches in the United States, who sent inviting brochures about their universities and their educational and sports programs. After a few ups and downs, I accepted a scholarship offer from Michigan State College (MSC) to begin classes there in January 1954. I was to be given two and a half years of a four-year undergraduate BS degree for my three-year Sydney Teachers’ College transcript and would have one year of undergraduate eligibility for athletic competition. An Australian sprinter two years my junior was already there and his support was valuable in securing the scholarship. We knew each other to some extent having both been members of the NSW Track and Field team in 1950. The NSW Department of Secondary Education provided me with a three-year leave of absence to complete both a BS and an MS or MA in the United States. I accepted this as a form of security rather than thinking of it as a command to return to its governance.

On October 10, 1953, five days after my 22nd birthday, I left Sydney on a 1,000-passenger Italian liner bound for Genoa. My purpose was to first visit my brother, who was then studying at the University of Cambridge, and then visit a friend in London, Ontario, before beginning classes at MSC in early January 1954. In retrospect the one-month trip from Sydney to Genoa was an abrupt jump in my ever-widening academic experience. I spent much time with young men of my own age from largely Germany and also from France and Italy. They were returning to their homelands after saving money in Australia since 1949 by using their skillful work on the technically advanced Snowy Mountains Hydro-Electric Project.⁴ The intent of these young Europeans was to use their savings to attend various universities in their native countries. I had great respect and interest in their academic intent and the long hours they had worked in the Snowy Mountains of southeast Australia. In academe to this day, I have always preferred colleagues, trainees, and classroom students who have met challenges external to a purely academic environment and these young “shipmates” were about to become the epitomes of this background.

On this voyage, I also worked out two to three hours a day with two affable professional wrestlers, whose names I still remember. One was from Buffalo, New York, and the other from Hawaii. After completing a tour in Australia, they and their female companions were headed to Europe for a similar tour. These were very tough workouts, and by the time I saw my brother in Cambridge, I was the strongest and supplest I had been to that point.

Visits to London and Cambridge were interesting, to say the least, as were the educationally rich trip to New York City on the Queen Mary passenger liner and the week I spent in Canada with students at the University of Western Ontario. The latter experience was the beginning of a lifetime of contact with Canadian universities, and their faculty and student contributors to movement neuroscience.

Move toward Physiology at MSC/MSU (1954–1955)

My stay at MSC, whose name changed to Michigan State University (MSU) in 1955, was eventful in many ways, and it aided my self-imposed, painfully slow conversion to the field of neuroscience.

MSU Coursework and Research

My undergraduate BS requirements included two quarters of compulsory humanities. The teaching was of high quality, particularly social science, which I had not had previously. As an undergraduate, I was most attracted to physiology and its laboratory exercises, particularly as taught by two outstanding instructors: Princeton-trained Professor W. Duane Collings (1914–1981) for cardiorespiratory mechanisms, and a recent German-born University of Chicago graduate, Assistant Professor Hermann Rudenberg (1927–1994), for experimental neurophysiology. Both emphasized the role of research in a university career, which was the beginning of my understanding of this possibility. I also took a superbly taught course in plant biology and most mistakenly did not follow up with a course in animal cell biology. This error was to cost me dearly, as I will explain below.

These academic pluses were countered by the poor quality of courses in PE and the inadequate research possibilities in my major, which foolishly was still PE. Fortunately, I continued to take physiology courses in 1955–1956, and in the last of these, which was on endocrinology, I learned a lesson that greatly aided my subsequent performance as a PhD trainee and subsequent director of my own research laboratory and its various trainees and visiting collaborators. In that endocrinology course I did all of my study with an older classmate, who later also became a neuroscientist. We profited greatly from our extensive interactions because the more we studied together and challenged each other, the better we did. This emphasis in our interactions was on dialogos, an ancient Greek term, which I define idiosyncratically as “dialogue without rancor.” It became a feature of all of my subsequent academic activities.

My MA thesis topic was quite naive. However, it required that I review literature about a variety of physiological indices that were being used at that time in the study of physical fitness. Throughout execution of this study, I became fully committed to the field of physiology and the certainty that I would next pursue a PhD in this area.

Part-Time Work

My athletic scholarship was very meager. It provided free tuition and part of my room and board in a dormitory. The moment I arrived I needed a 20 hour per week paying position, which had already been arranged for me. For two quarters I was one of the telephone switchboard operators in my dormitory, a job I actually enjoyed by chatting with the operator on the other end of the line. Their regional accents and my then-strong Australian one was always of interest and amusement to the other operator and me. Fortunately, MSU helped accommodate my financial needs by giving student athletes part-time employment. This work involved largely assembling and dissembling bleacher rows and seats for various college functions. In addition, we worked on the grounds and gardens of this attractive campus. While doing this work, it never occurred to me that my U.S. visa was a student one, which another state might not recognize as legal for part time nonacademic work. This issue became a major problem when I later transferred to UCLA.

Association with a Faculty Couple

Within my first few weeks at MSU, I met John Cowan Messenger (1920–2010) a cultural anthropologist who, with his wife, Betty (who later also became a cultural anthropologist), was engendering much renown. In 1951–1952, John had studied the Annang people of Nigeria and often referred to this experience and his findings. I became a good friend of this lively, friendly, and distinguished couple, and had many discussions with them, which I found fascinating because of the nature and range of their research. John was a groomsman at my wedding at MSU in 1957. He was an outstanding teacher of undergraduates, which I found out more than a year later from my future wife, who had taken one of his courses while an undergraduate at MSU. John and Betty’s love of their research further opened my eyes to the possibility of a research career. Their long-range effect on me was the extent to which knowing them encouraged me to seek contacts in areas other than neuroscience when I later entered this profession, a habit that persists to this day.

My Best Luck at MSU

I met my future wife, Jean Rassbach, in September 1955 when she was a third year undergraduate at MSU. She, as the head of a sorority, and I, as an assistant manager of a large dormitory, were on a panel to meet with a group of principals of Michigan high schools to discuss what beginning students should be aware of when they started their college life at MSU. My initial impression of Jean was how attractive and interesting she was. A few months later I met her by chance at the main library and she agreed to go out with me. On our first date, this sparkling and intelligent young woman with a truly sunny outlook explained to me the nature of her college major, her philosophy about marriage, the number of children she would like to bear, and how she would like to raise them. We only had about five dates before we decided on marriage after she completed her BA degree in June 1957. Within the short epoch of these dates, I had decided that I would indeed try to undertake a PhD in physiology at UCLA, marry Jean if she would agree, and stay subsequently in the United States to pursue a career in physiology. All of this came to fruition, including her acceptance of my selfish desire to make one final trip to Australia in the fall of 1956 before beginning my PhD training at UCLA in January 1957. In other words, as luck would have it, she agreed to a marriage in early June 1957 and barely seeing me throughout the preceding 10 months. Her most likeable parents made no attempt to discourage Jean from her atypical and indeed risky marital plan. In retrospect, this too was quite remarkable.

Break before UCLA (August 1956–January 1957)

At this stage in my story, I have to return to 1946, the year I began to advance as a high school athlete in cricket, swimming, rugby football, and high jumping. The latter was my favorite athletic pastime, even though landing pits (then usually filled with sawdust) were not used in NSW in 1946–1947, even for statewide contests held in Sydney. As a result, one had to use an old-fashioned style of jumping, which permitted landing without injury on a hard grass surface. This denied the possibility of using one of the two most advanced styles of jumping in that era, the western roll and straddle. With the encouragement and support of three of my high school teachers (all ex-servicemen just returned from WWII), I was given school travel funds to compete in the combined public high schools track and field championships in Sydney. There, I broke the NSW under-15 high jump record in 1946, albeit a higher jumper beat me. The subsequent newspaper accounts emphasized that I had jumped in bare feet on damp grass. After reading about this, my Aunt Jessie immediately sent me funds to buy customized, spiked shoes such that in 1947 I won the NSW competition and set an Australian record. Later, I set an Australian under-19 record, was a member of the NSW Track and Field team in 1950–1953, and the Australian team for the British Empire Games (1950) in Auckland, New Zealand, and British Commonwealth Games (1954) in Vancouver, Canada.

In the United States, I was denied one year of eligibility in university events, because of an argument between the MSU and University of Michigan track and field coaches, but this was a boon in my path to neuroscience. It enabled me to take a four-hour neuroscience laboratory course at MSU on Saturday mornings in the winter of 1955, after which I would fly to various cities for evening Amateur Athletic Union contests, which were mostly on board surfaces on which I jumped more consistently. Interestingly, I won the high jump on the hard cinder surface at the University of Michigan Fieldhouse in 1954 and 1956, setting a record in the latter event. My ambition going back to 1946 was to be the first man to jump 7′. However the highest height I achieved was 6′ 8 15/16” (6′ 9” would sound much better) in 1956, the year that another jumper leaped 7′. Nonetheless, I wanted one more crack at hopefully the Melbourne Olympic Games in late 1956. I had little money then, and did not wish to ask my mother for financial help. However, with a New York advertising friend and beginning track and field journalist of renown, Jim Dunaway (1928–2015), I had the opportunity to share the owner’s cabin with him on an empty Norwegian oil tanker’s trip from San Francisco to Indonesia (4 weeks) and another full tanker from there to Sydney (1.5 weeks). This plan was strongly disapproved by the team physician at MSU, James Feurig (1916–1975), whom I greatly respected. He emphasized that I would arrive in Sydney with “dead legs,” no matter how hard I practiced on the two ships. In my then-headstrong way, I ignored his advice and set out from San Francisco for Indonesia on September 9, 1956, after a Dunaway-organized car trip across the United States.

Throughout the trip to Indonesia, I practiced physical exercises assiduously, wrote two pages a day to my fiancée, played endless rounds of chess with Dunaway, and had long discussions at our daily meals with our erudite Norwegian ship captain. Our tanker was delayed by bad weather near the Philippines, and we arrived one day late for the next oil tanker to Sydney. Our tanker berthed at a Caltex facility at Sungai Kampai where the Siak River flows into the ocean in the Straits of Malacca, with jungle all around this small port. While Caltex tracked down my mother in Sydney, we spent two days there before taking a small boat up the Siak River to a much larger Caltex facility in Pekanbaru. The Siak River is very narrow and one could see the wildlife on both sides of the boat, a truly awesome experience.

I spent two or three days in Pekanbaru (still training every day as I had at Sungai Kampai) before taking another small boat back to Sungai Kampai and on to Singapore. The following morning I flew to Sydney, where I was met by my delighted mother, who scolded me for not asking her for funds to fly from MSU to Sydney!

Two days later in Sydney, I resumed high-jump training for the Olympic Trials: that is, the first actual jumping I had done since leaving San Francisco. I was horrified to find that just as Dr. Feurig had predicted, I still had dead legs for jumping, even though I was very fit in other ways. This continued in Melbourne in the high-jump contest at the Melbourne Cricket Ground, which had a temporary hard cinder track for the Olympic track and field events. The selection committee was very sympathetic and arranged for me to stay in Melbourne for a week and then compete in a jump-off for the third and final high-jump spot on the Australian team. I jumped higher in the jump-off, but was again beaten. As I lay in the landing pit after my third and final failing jump, I reflected that I now had to find a way to make some money to return to the United States and begin my PhD courses at UCLA. However, this had already been arranged for me. Jack Metcalfe (1912–1994), a Sydney lawyer and outstanding prior Australian Olympic athlete and coach whom I had known well in 1950–1953, was in charge of all the equipment used or constructed for the 1956 Games. Before explaining what he wanted me to do, he took me up to the bar at the Melbourne Cricket Ground to meet someone who wanted to have a chat with me. This was Richard Casey, a well-known and popular diplomat and Australia’s then ambassador to the United States. He had heard good things about me from Metcalfe and others, and he offered me the opportunity to return with him to the United States as a member of the Australian Department of External Affairs, where my job would be to give talks throughout the country, the purpose being to strengthen the already strong relations between Australia and the United States. I thanked him for this opportunity, but told him I was fully committed to a post-PhD career in physiology. He looked at me in amazement and politely asked me, “What the ##### is a physiologist?” I explained, and our conversation continued pleasantly for another hour.

The next day, a Sunday, I began work at 8:00 A.M. with Jack Metcalfe’s unit. My job was to design and have built the nonelectronic scoreboards used for over a dozen sports (including basketball, boxing, diving, gymnastics, rowing, swimming, water polo) at the Olympic Games, which would begin a few weeks hence, and to continue throughout the Games as the scoreboard troubleshooter. Amazingly, a person had been hired two years earlier to have all this already prepared, but he was indifferent to his assignment, albeit doing well on other ones. I was paid a particularly generous salary and worked about 80 hours per week for several weeks, including giving many lunch-hour talks to various service groups about life in the United States. As a result, I had more than sufficient funds to return to the United States by plane, and in addition, bring attractive gifts for my fiancée and her parents.

After the Olympic Games, I returned to Sydney for a few weeks to spend time with my family and await the postal arrival of my UCLA acceptance as a graduate student, which was needed for a new student visa. Mercifully it arrived in time for my arrival back at my fiancée’s home in Cleveland, Ohio, on Christmas Day. While waiting for my visa in Sydney, I was requested to meet with a high administrator in the NSW Department of Education. He had assumed that I would return to a new and very attractive position under his jurisdiction. At the suggestion of Gordon Young (1904–1974), the director of physical education in the same Department of Education, this was to develop track and field clubs throughout NSW and coach the more promising of the athletes, who would accrue from my efforts. Such a position would have enhanced my statewide visibility and paved the way for a subsequent political position in the House or Senate of NSW. This administrator and Gordon Young were surprised and quite annoyed that my plans had changed irrevocably. Reflecting on this much later, it is quite obvious that I had been treated most honorably by the NSW Department of Education, at least two of whose directors had my best interests at heart.

In summary on this Australian adventure, I had certainly had a memorable and unusual trip, but it was a stupid thing to do in terms of my ambition of competing in the Olympic Games. Also, it had interrupted what should have been my more important goals of augmenting my fiancée’s social activities during her final college year and taking a hard look at my academic deficiencies before leaving MSU to begin a PhD program in physiology at UCLA.

UCLA (February 1957–May 1961) and Wedding at MSU (June 1957)

My selection of UCLA for a PhD program had been the suggestion of my MSU professor, Duane Collings. He felt that I should not give up on my interest in exercise physiology, and he was impressed with the work of an eclectic bioengineer, bio-mathematician, and exercise scientist, Craig Taylor (1909–1958), who had a joint appointment at UCLA in physiology and engineering.

My First UCLA Semester

Before coming to UCLA, the deans of students at MSU and UCLA had arranged for me to have one semester of free room and board at a fraternity near the UCLA campus. In return, I was to give regular physical exercises to the fraternity members, which I did with much success and the enthusiasm and enjoyment of the participants. I also became by chance the announcer for the UCLA rugby union team, a position I kept and greatly enjoyed throughout my PhD experience. However, there were no meals at the fraternity house between Friday and Monday breakfasts, and I was very short of money because student visa regulations were much stricter in California than in Michigan. As a result, I had no regular part-time work and I struggled financially throughout this first semester.

An even more serious problem was the demands of the class work. Before leaving San Francisco, the preceding August I had hitchhiked down to UCLA to meet with Professor Victor Hall (1901–1981; Field et al. 1981), who then administered the physiology department’s graduate program. I explained to him my plan to travel by oil tanker to Australia via Indonesia in the hope of competing in the 1956 Olympic Games, and then returning to UCLA to also hopefully begin my PhD program in physiology. His response was to say sternly, “Mr. Stuart, you neither look, act, nor speak like a physiologist! This did not offend me. From the outset, I liked this short, pugnacious-looking professor, a polio survivor who used crutches when standing and walking, and who was later to play a major role in my training to become a physiologist. Rather, I smiled and replied, “Dr. Hall, I think I am going to surprise you!” When we met again after my return from Australia, he told me that my acceptance into the physiology PhD program was contingent on getting satisfactory (B or better) grades in several courses in my first UCLA semester. I found excellent study partners, and with intense effort did well in this challenge, and was then accepted by the department of physiology and told to look around for a research position with one of the faculty. I began with Craig Taylor, who suggested that I work on the steady-state oxygen consumption rate of longshoreman at the San Pedro Waterfront. My MS thesis research had soured me on chronic studies on humans but not on comparing the human maximum oxygen consumption rate in various groups with different levels of health and physical fitness. Taylor was impressed with my well-informed interest in this latter area, which was about to explode with international studies, but he had no such funded study available, so we parted amicably.

The only other faculty member who offered me a position was Professor Allan Hemingway (1902–1972; Anonymous 1972) who was not opposed to people with a PE background, having had a successful WWII research collaboration with a well-known exercise scientist at Wright Field, a U.S. Air Force (USAF) research facility in Texas. Hemingway wanted me to analyze expired respiratory gas for its oxygen and carbon dioxide content using a Scholander gas analyzer in studies going on in his laboratory group, and in parallel have the opportunity to develop my own PhD thesis project using this among other techniques to study an aspect of the neural control of body temperature, for which area he had a grant from the USAF Arctic Aeromedical Laboratory, which included a research assistant salary for me. I took this position and told Hemingway that I would start work with him two weeks hence after getting married back at MSU.

Marriage on the MSU Campus

Before flying back to MSU, I had arranged for a new drive-away car for the trip back to Los Angeles. For such cars, one was given free gasoline for a drive from an automobile company to a car dealer at the destination. However, when I arrived at East Lansing, the person organizing the availability of a car had lost his connection to the auto industry. Fortunately, the MSU football coach, Duffy Daugherty (1915–1987) arranged another car for us. Duffy had fought with Australians in New Guinea during WWII, and he greatly liked them, including those who were or had been athletes at MSU.

Jean had been very busy in her final quarter at MSU, which involved her BA completion and making all the arrangements for our wedding and reception at the Alumni Memorial Chapel on the grounds of the MSU campus. She held up admirably, however. At a prewedding Rassbach family reception, Jean’s Uncle George from Los Angeles asked me how much money I had. I replied truthfully and dispassionately, “I have 35 dollars to my name.” He chuckled and said, “Aha, I knew you were an adventurer!” We instinctively liked each other.

Two days after our wedding, Jean and I took off for Los Angeles. We found an apartment in Westwood and helped pay the first month’s rent with money we had been given as wedding presents. Jean immediately began teaching at a Santa Monica elementary school in the Los Angeles School District. This required two bus trips and long walks to and from work, whereas I walked less than a mile to the physiology department in the UCLA School of Medicine. Note that we had no time or funds for a honeymoon, and in reality, we barely knew each other. Thus, began our West-Coast married life, which has now reached 60 years, the platinum duration. For the next year (1957–1958), we were very poor, to say the least, because Jean stopped teaching to begin a family. However, we had several friends who were married couples in the same financial situation, and we look back on that year with much amusement, fondness, and pride in our fortitude.

Work in the Hemingway Laboratory

I worked with Allan Hemingway from late June 1957 until late March 1961. He and his charming and lively wife Claire, who was a biochemist, went out of their way to be hospitable to Jean and me. In addition, Allan gave me an open invitation to bring my local and visiting friends to his nearby Westwood home in the late afternoon for refreshments and spirited conversation. He greatly enjoyed all of my invitees, and particularly the UCLA rugby players from Australia, New Zealand, and South Africa, and also those at the University of British Columbia. (Both Allan Hemingway and Victor Hall were originally from nearby Victoria on Vancouver Island.)

Hemingway ensured that both locally and at national meetings of the American Physiological Society, I had discussions with as many senior physiologists as he deemed desirable for the advancement of my career. In the laboratory, he left me alone to do my temperature regulation experiments and he edited carefully our coauthored six refereed articles and three book and symposium chapters, which were published between 1959 and 1964. When I left his laboratory, he followed my subsequent appointments with great support and interest. In many ways, he was a model mentor, whose friendship and support I will always respect. However, there was one serious problem. For my PhD research, he wanted me to recheck classical shivering studies using old-fashioned techniques (see Hemingway and Stuart 1963). In contrast, I wanted to continue along the lines of Lucy Birzis (1919–2008), his most recent previous PhD student. She and Hemingway had become the first experimentalists to record the unitary activity of hypothalamic neurons using extracellular microelectrodes. As a former physicist and skillful instrument maker, I thought Hemingway would revel in such work. However, he was politely adamant that he preferred other work for me. I also tried to tempt him with the idea that I should work on the determinants of the motor rhythm of shivering, a topic in which we both had interest. Again, his background in physics made him an ideal mentor for this project, which also would have given me a far better start in movement neuroscience. His counter was that this could be my main postdoctoral project, as subsequently occurred.

Another person in Hemingway’s UCLA group also had a strong impact on me. I consider him my comentor in becoming a physiologist. This was Walter Freeman III (1927–2016), a Yale MD, and postdoctoral associate in the Hemingway group until leaving in 1959 for a faculty position at UC-Berkeley. Walter was a fourth-generation U.S. clinician. One of his great-grandfathers, William Williams Keen (1837–1932), was the first brain surgeon in the United States and a particularly successful and innovative one. Walter’s father, Walter Jackson Freeman II (1895–1972), was also a prominent, if controversial, clinician. A neurologist among other specialties, he co-coined the term “psychosurgery” during his mentorship under the Portuguese 1949 Nobel Laureate neurologist Egas Moniz (1874–1955). Together, they and Freeman II’s American collaborator, the neurosurgeon James W. Watts (1904–1994), were leaders in the development of prefrontal lobotomy (leukotomy), a controversial way to alleviate selected psychiatric disorders.

I greatly enjoyed my association with Walter Freeman III. He had a towering and highly original intellect⁵ and was a great conversationalist. We became good friends, and I learned a great deal from him about all manner of neuroscience developments, including importantly how hard one has to work to advance knowledge by even a smidgen.

Other Aspects of PhD Training at UCLA

I relished my experiences as a PhD trainee at UCLA, entering the program with much naiveté in the summer of 1957 and defending my PhD thesis in early 1961 with far more knowledge about the field of physiology, in general, and neuroscience, in particular.

Faculty: During my PhD training, three of my professors were elected to the National Academy of Sciences: Ted Bullock (1915–2005) for invertebrate neurobiology; Horace (“Ted”) Magoun (1907–1991) for neuroanatomy and the reticular activating system; and Donald Lindsley (1908–2003) for physiological neuropsychology. Shortly thereafter, Tom Sawyer (1915–2006) was elected for neuroendocrinology. Several of my other UCLA professors were well known at the international level. They included W. Ross Adey (1922–2004), Bernard Abbott (1920–2006), Earl Eldred (1919–), John Green (1917–1964), Wilfred Mommaerts (1917–1994), Arnold Scheibel (1923–2017), Fritiof Sjostrand (1912–2001), Robert Tschirgi (1925–1997), and Victor Hall, my ever-alert critic and unwavering supporter. They were all very friendly and supportive of the biomedical trainees of my era, and all were excellent classroom teachers, the best being Adey, Hall, and Tschirgi.

Magoun and Hemingway, and many other of these noted faculty, ensured that leading U.S. and foreign neuroscientists, who worked at or visited UCLA, had substantial scientific and social interactions with the pre- and postdoctoral trainees. This was how I developed my lifelong interest in interdisciplinary neuroscience, and the advantages of exposing pre- and postdoctoral trainees to the very best of international neuroscience, both intellectually and socially.

Course Work: In the spring semester 1958, I topped the physiology course taken by 100 medical students and about 20 PhD trainees. Of more local interest was that I co-topped the interdisciplinary neuroscience course taken by the same medical students and even more PhD trainees. The “co-topper” was Don Wilson (1932–1970), whose mentor was Ted Bullock. Don later did brilliant postdoctoral pattern generator work on the locust before further such work at UC-Berkeley followed by Stanford University. Tragically, he died during a river trip at far too young an age.⁶

Overall, the UCLA basic and clinical neuroscience faculty were sufficiently pleased with my academic performance that I was granted for 1959–1961 a far better paying predoctoral position in the interdisciplinary National Institutes of Health (NIH)–supported UCLA Mental Health Training Program.

The Tragic 1958 Death of Craig Taylor: Throughout early 1958, I maintained my contact with Craig Taylor, who was tempting me with a PhD project on improving electronically driven artificial arms. However, when the Russians launched Sputnik 1 on October 4, 1957, there was a hue and cry in Washington, DC, about why had we fallen behind the Russians at the beginning of the Cold War space race in the number of competent mathematicians and bioengineers required for our own nascent space program. Craig Taylor’s advice was more or less demanded by various think tanks in Washington, DC, along with that of many others with his eclectic bio-mathematical talents. He began flying regularly and quite often to Washington, DC, for such meetings. This involved travel on commercial planes far too many times, these being pre-jet, 10-hour flights between Los Angeles and Washington. The terrible result was that in a moment of exhaustion and despair, he committed suicide on April 24, 1958, by jumping off the top of the UCLA engineering building. Allan Hemingway knew this far too well because before Taylor’s next-demanded Washington trip just before his suicide, he was totally exhausted and begged Hemingway to take his place for that final meeting. Hemingway declined on the grounds that he was too busy at that time, a decision that he subsequently regretted with much guilt for the remainder of his life.

A Training Gift from Professor Ross Adey: In 1958, Ross Adey decided he should give four of his trainees and me (a fellow Australian and his good friend) informal (noncredit) training, which he felt would benefit our subsequent careers in research. We met for four hours on Saturday mornings throughout the fall of 1958 and the spring and summer of 1959. The 1958 sessions were devoted to electronics and its application to electrophysiological instrumentation. In 1959, we presented summaries to our fellow classmates on the neurobiology of brain structures from the medulla oblongata to the forebrain, with all five of us carefully studying the reading list for each session such that we could interact optimally with the speaker. We worked far harder for this informal training than for our credited coursework. Adey was an intense and highly motivated taskmaster throughout these sessions, and we all recognized that we were being given a unique and extraordinarily valuable experience. In my own case, it was of inestimable value for my future electrophysiological research and for when I began teaching as a faculty member. Clearly, my classmates and I owed much to Ross Adey for his commitment to our development as neuroscientists.

PhD Written and Oral Exams: I did well in my 1959 PhD written examination, writing for a total of 17 consecutive hours. In the subsequent oral examination, however, it became painfully obvious to the committee that I had a serious deficiency in fundamental cell biology. This deficiency had not been obvious in my previous UCLA physiology exams because their focus had been at the systems level of understanding. Accordingly, I was given six months to rectify this deficiency before another oral exam would be given. During those months, the faculty in the physiology department gave me three informal but intensive oral exams to establish the full extent of my deficiencies. I took all this quite philosophically because I needed and respected their brutal probing, which had come about by my own making. My problem had begun at MSU by not following an excellent course in plant cell biology with a similarly in-depth one on animal cells. This cavalier approach continued at UCLA, where I had ignored detailed histology and focused on its broad principles as taught quite cleverly by Fritiof Sjostrand. Fortunately, I survived this six-month reappraisal of my broad biological knowledge and did well on the subsequent oral examination. Several years later, I would tell my own PhD trainees about this experience when they were preparing for their own written and oral examinations. I always exhorted them to consider principles of importance in physiology and neuroscience from the cellular to the systems to the organismic level of understanding. Remarkably, our modern trainees can do this, with the added ability to precede cellular principles with molecular ones.

Association with Professor Youjira Kawamura (1921–2013): This remarkable Japanese neuroscientist, a former neurosurgeon, became the youngest (at 38) full professor of physiology in Japan at the University of Osaka Dental School. Kawamura went on to train more than 40 department heads of clinical dentistry, neuroscience, and physiology in Japan’s then-20 schools of dentistry. For this effort, together with his scientific renown, he was honored with a prestigious award from the emperor of Japan and similar awards from many foreign countries.

Kawamura came to UCLA in late 1959 on a Rockefeller Foundation award for one year of research at UCLA and six months visiting laboratories in Europe after which he was to write a report for his sponsoring foundation. He had just published the world’s first textbook of oral physiology and neurophysiology. Kawamura had hoped to collaborate at UCLA with a leading neuroscientist. However, there were no open spots for him except in Hemingway’s laboratory to work with me, a lowly PhD trainee. He took this letdown in cheerful stride, and we had a great year together. He recently had studied some mechanisms of tremor and was not averse to working with me on the central control of shivering. In addition, Kawamura spent much time with the first UCLA dean of dentistry, Raider Sognnaes (1910–1984), who wanted him to transfer to UCLA as head of physiology in the dental school, which was to take its first class in 1964.

I arranged for Kawamura and his wife, Haru, to rent an apartment near Jean and mine such that Haru could spend most of each day with Jean and our two very young children, who were then tentatively learning their first words of English from their mother, as did Haru. Thirty-six years later, she told Jean and me in Osaka, Japan, how much she still remembered about this experience and how much she had enjoyed it.

Kawamura taught me how to keep our experimental results in better systematic order and other fine points about the electrical stimulation of brain structures (e.g., see Stuart et al. 1961). In all, we coauthored two refereed articles, a technical report, and two book chapters on the neural control of shivering and, together, we discussed this work at several other institutions. He also presented a talk at the 1960 Fall Meeting of the American Physiology Society at Stanford University. For this talk, a fellow graduate student and I had him practice intensely for his presentation of one of his own Japanese projects, an intracellular iontophoretic stimulation and recording study on hypoglossal motoneurons in the cat, which was no mean feat in 1960. I also improved his written English for several of his subsequent publications, a practice I am still undertaking over 57 years later for many Japanese colleagues.

Finally, I should add that Kawamura and I met several times subsequently in Tucson, India, and Japan. Our wives and we had become great friends at UCLA, this being one of the best features of collaborative research with colleagues in both one’s own country and abroad.

PhD Thesis Research: I enjoyed writing my 259-page PhD thesis, with its 260 citations on the prosencephalic modulation of the hypothalamically controlled shivering tremor. Admittedly, it involved use of old-fashioned techniques, but the effort put into it was substantial as was the knowledge I had about this subject by the time of its completion. In all, it resulted in three refereed publications, and five technical reports for the U.S. Arctic Aeromedical Laboratory, the latter being a valuable experience for subsequent progress reports to other extramural granting agencies.

Shortly before defending my thesis, Hemingway was visited by Sir Otto Edholm (1909–1985), a famous and very pleasant (indeed charming) English worker on all-round physiology, including temperature regulation. He was then Head of the Division of Human Physiology at the National Institute of Medical Research in London. He came to my tiny so-called office for a chat about shivering. At the outset, I said, “Sir Otto, before we begin I should tell you that I know more about this topic than any other living person!” He laughed and said, “Proceed.” I did for more than two hours, with him adding valuable comments and questions along the way. After this delightful and valuable interaction, my PhD thesis defense was effortless.

Postdoctoral Research at the Long Beach VA Hospital (April 1961–1963)

While completing my PhD thesis, I was awarded a postdoctoral medical research fellowship by the Bank of America–Giannini Foundation. It paid sufficiently for me to take my family to any laboratory in the United States or abroad. However, I felt it best if we could stay in California such that Jean could have as stress-free time as possible while raising our ever-expanding family, with our third child born the night before my PhD defense. For this reason, I chose to work with Professor Earl Eldred as my PhD mentor in my own laboratory at the Long Beach Veterans Administration Hospital (VAH) in a program supported financially by both the hospital and the UCLA Brain Research Institute (BRI). My laboratory was equipped superbly, and it included the full-time services of two fully paid and very capable technicians; a very creative electronics technician, and a masterful one in experimental animal surgery. On the home front, it was particularly helpful that Jean’s parents helped us purchase a fine home in the town of Rossmoor, about four miles east of my laboratory, and on a street where Jean made several friends who had children of the same ages as ours. In summary, the four years spent with my family in Rossmoor and at work at the Long Beach VAH were very happy ones, quite scientifically productive, and very pleasant except for one incident with Ross Adey, as explained below.

Two Then-Atypical Research Collaborators

A High School Collaborator of Great Talent: Shortly after beginning work in Long Beach, I requested technical advice from Lawrence Ott (1905–1978), a PhD physicist at a Hughes Aircraft research facility in Culver City. He gave it willingly and asked if in return I could provide a research experience for one of his twin sons, who was a high school senior in Altadena, California. Thus began the research of Ken Ott (1944–) in my postdoctoral research program. On Saturday mornings, he made the one-hour drive from Altadena to my laboratory in Long Beach, and we then undertook an electrophysiological experiment on surgically reduced spinal cats. These experiments ended in the late afternoon. That summer, he worked full time with me, just as he did in subsequent summers while an undergraduate at Yale University, and for two further summers while a medical student at UC-San Francisco. During medical school, he spent a summer as an ex-tern at the National Hospital for Neurology and Neurosurgery, Queen Square, London, England. After medical school, Ken was an intern and resident in the Harvard program in neurosurgery at the Massachusetts General Hospital. He is still very active in private practice in San Diego. Ken established the Gamma Knife Center for radiosurgery, the first radio-surgical unit in San Diego. Additionally he developed a movement disorders surgery program at Scripps Memorial Hospital and Sharp Memorial Hospital. He is a past president of the California Association of Neurological Surgeons. In all, Ken had seven publications with me on a variety of topics, all of which involved electrophysiological recording in anesthetized cats and conscious humans. Ken is still carrying out stereotactic surgery and laminectomies (in humans) just as he did (in cats) long ago in my labs in Long Beach and Davis California. People like Ken, who participated in experimental neuroscience in high school, were relatively rare in the early 1960s but are now far more prevalent, and neuroscience has profited accordingly.

My First Postdoctoral Research Fellow: In the early 1960s, it was very unusual for a beginning research assistant professor to have the services of a nationally funded postdoctoral research fellow, particularly one from abroad. However, this was my good fortune in 1963 shortly after completing my postdoctoral traineeship. A Japanese neurologist on leave from the department of neuropsychiatry at Chiba University requested that I meet him in my Long Beach office. Koichi Ishikawa (1932–), a former neurophysiology trainee of Professor Sabura Homma (1923–2014) at Chiba University, who himself had trained previously with a later Nobel Laureate, Ragnar Granit (1900–1991) in Stockholm, was working at that time with a senior American neuroscientist at a university in Southern California. Koichi was very unhappy in this position and asked if he could work with me. Homma was a good friend of Eldred, who had also worked with Granit, so I told Koichi that I would try to help him. I considered the very limited number of possibilities for providing a U.S. fellowship to a non-U.S. citizen and together we applied to the Foundations’ Fund for Research in Psychiatry. To my great astonishment, the application was successful, and Koichi spent the next four years with me as his supervisor; two at Long Beach, which were very happy ones for Koichi, his wife, and two young sons; and two years at UC-Davis, where he was most unhappy because he felt far more at home in a large city. It was in my Davis laboratory that he met the 1963 Australian Nobel Laureate, Sir John Eccles (1903–1997), who later provided him with a two-year position at SUNY Buffalo, so in subsequent years, he felt much better about his association with me in Davis.

During our four-year collaboration, I learned far more about overall neurobiology from Koichi than he did from me. He was a fourth-generation Japanese clinician, going back to late Samurai times. Together, we coauthored seven refereed articles and one book chapter. These featured my transition from work on the neural control of shivering at UCLA to extracellular neuronal recording in the cat central nervous system (CNS) and in human spinal cord injury subjects at Long Beach, and finally intracellular recording of motoneuron properties in cats at UC-Davis. This progression involved his enthusiastic participation in the experiments and editorial criticisms, delivered with typical Japanese politeness, of our articles and my various seminars and national meeting presentations.

Research Projects at the Long Beach VAH

Work on the Rhythm of Shivering and Other Tremors: This work was my main postdoctoral research project with Eldred as my mentor and collaborator. He participated actively and imaginatively in many of our key experiments on shivering, which were accomplished on anesthetized cats and conscious humans, the latter using some procedures that were quite novel at that time. The work resulted in three consecutive reports on the control of the shivering rhythm, general sensory, proprioceptive, and central contributions and a chapter written for a symposium volume. The findings were summarized as follows:

It was concluded that under experimental conditions, the contributions to the shivering tremor of general sensory inflow, proprioceptive input, mechanical factors and central influences could be recognized and each even shown to be essential. In the intact animal and human the rhythmicity of shivering would appear to involve a complex yet smooth interaction between all these contributions. (Stuart et al. 1966c)

These findings should have been of general interest to an emerging group of movement neuroscientists, who were beginning to study the overall control of movements by blending “inside-out” and “outside-in” approaches. Inside-out involves determining the properties of single cells within the CNS and then ascertaining how these properties influence the operation of CNS microcircuits, single reflexes, groups of reflexes, and generators of central patterns of movement. This information is then used to theorize about CNS control of overt motor behavior. In contrast, the outside-in approach begins with analysis of the biomechanics of posture and movement and then uses this information to theorize on how the mechanics are solved by the CNS and its pathways, circuitry, and even single cells (Stuart 2007; see also Wetzel and Stuart 1976). Sadly, our shivering rhythm articles were largely ignored for two reasons. Shivering movements had less general appeal than other forms of movement, with breathing and locomotion being the most popular. Also, our three articles were published in the then relatively insignificant American Journal of Physical Medicine, as urged by Magoun, who at that time was trying to help the field of physical medicine advance its scientific visibility. I was too naive at that time to see the disadvantage of not submitting our work to a leading journal where publication would occur only following rigorous peer review. This would have improved our own thinking on the topic, and there would have been a far wider readership. Later, this point was drilled into my own pre- and postdoctoral trainees.

Extracellular Recording in the Hypothalamus: Using steel microelectrodes, I did a great deal of extracellular recording of the firing patterns of hypothalamic neurons in response to local changes in temperature (with one collaborator), visceral and somatic inputs from lower brain structures (two collaborators), and the relation between such firing patterns and direct current (DC) shifts in the hypothalamus and cerebral cortex (two other collaborators). Among the collaborators, Ross Adey was most helpful, teaching me several nuances of extracellular microelectrode recording that greatly aided my subsequent work using intracellular recording in the spinal cord, which ironically was never undertaken by him. Fortunately, I was given the opportunity to summarize all of this work in a single unifying chapter (Stuart et al. 1963), which was written for an international symposium to which I was invited, as held in Villahermosa, Mexico, in 1963. Admittedly, I wrote this chapter with tongue in cheek because I knew that I would not stake my subsequent neuroscience career on the hypothalamus, even though other of my articles on this structure would have to be written following their completion. Rather, shortly after I began my postdoctoral research with Eldred, I became fully committed to research on the neural control of movement using both inside-out and outside-in approaches, as explained previously. Interestingly, however, our 1963 summary of my work on the hypothalamus was well received, probably because the neuronal patterns of its discharge were still largely unexplored.

An Impromptu 1963 Talk in San Francisco: By late 1963, I had given several fully prepared reports at national meetings of the American Physiological Society, and at three international symposia. However, the talk I remember with the most pleasure was a totally impromptu one-hour talk given at the Mt. Zion Hospital in San Francisco, where the audience included Ben Libet (1916–2007). Many consider Ben to have been not only a Nobel-standard cognitive neuroscientist but also a far better neurophysiologist for his work on the mammalian cervical ganglion than he was usually given credit for. We met several times subsequently, and when Ben was almost 90, he provided a chapter for one of the publications I arranged and edited.

Work on Spinal Cord Injury Patients: During and after WWII, three clinicians were well known for their attention to the clinical needs of allied servicemen and ex-serviceman with a spinal cord injury (SCI). Ludwig Gutmann (1899–1980) was a German-born neurosurgeon who became a British subject in 1939 when he began directing a SCI unit at Stoke Mandeville Hospital. Donald Munro (1889–1973) was an American neurosurgeon at the Boston City Hospital, and Ernest Bors (1900–1990) was a Czech urologist until 1938, when he became a U.S. citizen. Bors led a major SCI center first at the Birmingham General Army Hospital in Van Nuys, California (1945–1958), and then at the Long Beach VAH (1958–1970). I had the good fortune to interact with Bors on two aspects of his Long Beach SCI program. First, he selected the patients for a study I led on fluctuating spinal reflex patterns in SCI patients. Second, I spent many hours with him observing the unusual reflex patterns of many of our test subjects and his other SCI patients. This experience reinforced my intent, which was supported by Bors, to study spinal cord mechanisms in the cat using intracellular recording from spinal motoneurons and, hopefully, later from spinal interneurons. I greatly admired Bors, who was one of the finest and most motivated clinicians I was to meet throughout my time as an experimental movement neuroscientist.

A Blow Up on the Alleged Measurement of Impedance in the CNS: It was well known at UCLA and indeed internationally that Ross Adey had an explosive temper. Even as a graduate student, when I was known to be his close friend, I was often asked to mediate with him about a faculty member or student who had been the victim of his wrath. Eventually I, too, became such a potential victim, but I chose to combat Adey rather than ask someone else to intercede on my behalf.

In mid-1963 Adey provided my laboratory with a recording device, which he claimed was appropriate for measuring impedance in the CNS, such that I and two other research assistant professors could compare this measurement to DC shifts in the hypothalamus and cerebral cortex in response to stimulation of the midbrain reticular formation. The three of us came to the conclusion that his method for the measurement of impedance was fallacious. This opinion was shared by some in Adey’s UCLA group who spoke with us, including a very bright English physicist, who returned to England in disgust about this issue, and a similarly upset Australian neurophysiologist, who returned to his homeland where he had a long-standing and distinguished subsequent career.

We urged Adey to publish a retraction of his recent two publications using this instrument, which was an adaptation of one that had been used successfully and legitimately for the measurement of peripheral blood flow responses (Kolin and Kado 1959). Adey’s response was to try to get me fired from the BRI and the Long Beach VAH and in his words drive me “out of neuroscience.” His ire required the support of Jack French, the director at the main BRI component at UCLA and Bob Porter, a Jack French–trained neurosurgeon who was also the head of neurosurgery and director of the smaller Long Beach VAH component of the UCLA BRI. Porter was not prepared to get involved. Rather, he would have liked me to again become a colleague of Adey. French, too, was not prepared to get involved once I told him that my two colleagues and I had the theoretical support on the impedance issue of Don Jenden (1926–2013), a professor of pharmacology who many recognized as the leading quantitative neuroscientist at the UCLA School of Medicine and its BRI (Jenden 1996). French did not intercede, however, when Adey succeeded in having the BRI component of my salary abolished. This cut my overall salary by 10 percent, and it occurred just a few weeks before our fourth child was born, when Jean and I were very short of money. The cut was not for long—just the few minutes it took for me to go from the seventh floor BRI business office to the fourth floor of the adjacent medical school where my former PhD mentor had his office. After telling Allan Hemingway my tale of financial woe, he picked up his phone, called an administrator, and told her to put me on one of his grants as an advisor, at a stipend level identical to what the BRI had taken from me. These hijinks became widely known throughout the BRI, the Long Beach VAH, and far beyond. Indeed, I received phone calls and had personal discussions with some leading neurophysiologists across the entire United States about this issue, these being neuroscientists who doubted the validity of Adey’s work on impedance.

My two colleagues and I never published our impedance results, of course, but we did publish the work we had done on DC shifts in the hypothalamus and cerebral cortex because we were sure of the validity of our measurements. As for Adey, he never did publish a retraction. Rather, he published 10 further reports on alleged impedance up to 1971, but I do not know whether he made changes to his recording instrument or whether his subsequent measurements have been critically evaluated in the overall impedance literature. Certainly, he made his mark in other areas of neurobiology, including in particular the effects of electromagnetic fields on biological tissues. Adey had many other battles at UCLA, both scientific and political, but he retained the support of French and Porter for several more years. Eventually, however, his fight with a UCLA chancellor forced him in the late 1970s to leave UCLA and take a position at Loma Linda University and set up a laboratory at the Loma Linda VAH where he stayed until his demise. He appears to have undertaken sound work at Loma Linda on the role of power frequency of electromotive forces for the alleviation of some cancers, but he again became beset in controversy when he promulgated the possibility of potential cancer risks following exposure to cell phone radiation. Nonetheless, I still owe Adey a great debt of gratitude for his role in my PhD and early postdoctoral training.

The impedance brouhaha soured me on the BRI at UCLA, and I planned to leave there once an appropriate faculty position became available in the UC system, which did not occur until 1965.

Continued Contact with the Department of Physiology at UCLA: In 1963–1965, my title was “assistant professor of physiology in residence.” This was a non-tenure-track title, which at other state universities was equivalent to “assistant research professor.” I taught the full 12 one-hour lectures on respiration to the medical school and graduate student classes of 1963 and 1964. Victor Hall attended many of these lectures and gave me valuable critiques just as he had done when I was a PhD trainee. I also became friends with two new assistant professors of physiology. Together, we taught the new first-year dental school class of 24 members in 1964 and 1965.

UC-Davis (1965–1967)

Our transfer to UC-Davis had many pluses and minuses for our family life and largely pluses on the work front for both Jean and me.

The Home Front

We were “house poor” in Davis, because we found but one home large enough for our family, and it was quite expensive to purchase. Mitigating this problem was that the elementary school for our three older children had excellent teachers, and it was just around the corner from our home. At that time, our older son of seven was already committed to becoming accomplished at horseback riding. At Davis, he had a superb instructor who taught him how to make a horse jump over obstacles, a talent he progressively refined in his subsequent outdoor action career in movies and TV.

On Sunday mornings, it was a tradition for me to take our three older children to see the wide variety of animals that were housed on the campus, always ending at the veterinary school’s surgery recovery barn where one could see championship horses with their grooms, who slept close to their charges. There were several other social advantages. We frequently drove over to Napa Valley to taste wines at various vineyards. Our route was via Lake Berryessa, as attractive a car trip as can be imagined. Amusingly, our home became a bed and breakfast stop for many of our LA friends who found it convenient to stay overnight with us on skiing and summer trips to nearby Lake Tahoe. Most important, Jean began teaching again, and she greatly liked her young students whose parents were Mexican agricultural workers. These children’s kindergarten to sixth-grade school was in the town of Dixon, just a nine-mile car ride southwest of Davis, with most of the drive on a freeway. In 1966, Jean’s older sister and her husband and four children transferred from Columbus, Ohio, to San Francisco such as to enhance our family activities and possibilities. However, despite these pluses, by mid-1966 our departure from Davis was inevitable. The climate, with its damp Tule fogs in the winter and excessive agriculturally produced pollen counts in the spring, were too harsh for the respiratory system of our six-year-old daughter. Clinicians at UC-San Francisco were adamant that she would have to leave Davis as soon as was possible, and live in a dryer, less pollinated environment. Fortunately, this would be possible if I could secure a position in physiology at the University of Arizona (UA), where a new medical school was to open in the fall semester of 1967.

Hostility of the UC-Davis Chancellor

While at UC-Davis, I had an extremely heavy teaching load in the department of physiological sciences, which after my arrival was composed of nine faculty, three each in biochemistry, pharmacology, and physiology. Shortly after I arrived, it was announced that the size of the veterinary school class would be immediately doubled from 50 to 100 students. This came as a complete surprise and shock to the entire veterinary school faculty, except for the dean, who lost much face by his lack of honesty about this issue. For the first-year physiology course, it meant that we would have to increase our number of four-hour laboratory exercise sessions in the spring semester from three to six per week—that is, five on Monday to Friday afternoons and a session on Saturday morning. My two new physiology colleagues were furious and asked me to cosign a letter to the dean with a copy to the chancellor in which we demanded that a salary be provided for an electronics specialist to maintain the electronic recording equipment used in these laboratory sessions. Naturally I complied and thereby gained the enmity of the chancellor, Emil Mrak (1901–1987), a short, rotund, somewhat unkempt-looking person, who was known affectionately to the faculty as “Fats.” He provided us with the requested salary but was annoyed by our aggressiveness. Before the beginning of the fall semester 1965, he held a social function one Saturday afternoon for the new faculty and their significant others. When Jean and I met him in his reception line he snarled and said, “Ah Stuart, you have just arrived and you are already complaining.” Jean was not impressed. She said rather coldly, “Dr. Mrak, my husband does not discuss business on the weekends.” He muttered under his breath and from then on referred to me as “that young son of a ### from UCLA.” However, I admired Mrak. He was respected throughout the overall UC system because of the proximity of UC-Davis to the state legislature in nearby Sacramento. This helped make him a valuable lobbyist for the UC system as a whole and indeed an advocate for state-supported higher education and research throughout all of California. Also, he was the driving force in the conversion of UC-Davis from a first-class agricultural and veterinary science campus to a similarly first-class all-round one like those at UCLA, UC-Berkeley, and UC-San Diego. He had begun his academic career at Berkeley as a food scientist and microbiologist and had developed an international reputation on the biology of yeasts.

I never again interacted personally with Mrak, but his antipathy to me was further enhanced a few months later, when the planned new dean of medicine decided not to leave the University of Washington. Mrak panicked, and without consulting his original search committee for this position, he offered it to a person who the committee had ranked as 37th on their original list of potential candidates. With encouragement from the dean of the veterinary school, I made enquiries about this person and foolishly relayed my concerns to one of my former UCLA professors, Robert Tschirgi, who had become the vice president for academic planning of the entire UC system. He shared my reservations and relayed them to the president of the UC system, Clark Kerr (1911–2003). Tschirgi’s and my concerns did not impress Kerr, so he phoned Mrak and told him that I should be “restrained” from attempting to play a role in the issue. The reader can imagine Mrak’s reaction: “That young son of a ### from UCLA had done it again!” From then on, I would hear from various Davis colleagues how Mrak had castigated me in various meetings. This was always told to me with great humor and laughter, and it did not worry me in the slightest because I was a tenured associate professor. The affair was a valuable lesson, however and I never again came on too strongly or too quickly when confronting a difficult academic issue. My future strategy was to give much thought to how to accomplish a difficult goal in academic politics, rather than simply stir the pot of contention. Interestingly, I got on quite well with the new dean of medicine, who did a good job in getting his new school off to a sensible start. This, too, was a valuable lesson for me, as I will discuss.

Recruitment of Bob Reinking

The electronics expert hired to assist our teaching program was Bob Reinking (1941–), who was superbly trained and experienced for what we needed him to do in our department. As a bonus, Bob was young, imaginative, inventive, and hard working, as well as being naturally pleasant with a great sense of humor. My department decided he should work more or less exclusively with one of the pharmacologists and me, and within a few months this changed to virtually me alone.

One of Bob’s and my joint laboratory exercise triumphs was to have the veterinary students chronically implant electrodes into cat brains for subsequent stimulation of the awake animal. Bob also played a major role in our development of an electronically sophisticated electrophysiological laboratory for spinal cord research. With the help of Professor Sabura Homma, when on a visit from Japan, Koichi Ishikawa, Bob Reinking, and I began to record intracellularly from mammalian spinal motoneurons (Homma et al. 1970).

Meeting Ted Goslow

Shortly after my beginning at UC-Davis, Ted Goslow came to my office to discuss measurements of muscle length-tension during dynamic movements. He was a PhD graduate student in zoology working on a most imaginative thesis project. It involved analyzing the lower limb and foot movements of six species of raptors (birds of prey) as they descended to strike a mouse on the ground. These movements were photographed in Ted’s backyard against a scaled backdrop for subsequent kinematic measurements of the movements. I was amazed by the originality of the project. Later, I emphasized that we should collaborate when we both came to Arizona at the same time: he to Northern Arizona University (NAU) in Flagstaff, and me to the UA in Tucson. We had a very successful collaboration from 1970 to 1984, I, a late-trained neurophysiologist learning much from an exceptionally well-trained and imaginative comparative morphologist and vice versa (e.g., see Goslow et al. 1973).

Interactions with Leo Bustad

Within a few days of beginning work at UC-Davis, I met Leo Bustad, DVM, PhD (1920–1998), a former American prisoner of war in Germany during WWII, and later the dean of veterinary medicine at Washington State University, where the veterinary school building is named in his honor.⁷ At UC-Davis, Leo was the director of a long-standing research program on the effects of radiation on beagle puppies. He attended virtually every lecture I gave at Davis to veterinary students, and he gave me advice on innumerable issues confronting the university as it developed its new academic programs. Leo was very shrewd politically, which was combined with a wonderful sense of humor and true bon vivantism. We became close friends, and I attribute much of my later subsequent success at the UA in dealing with contentious issues to his advice, which was always sound.

A Visit by John Eccles

As mentioned earlier, my quarrel with Ross Adey over the validity of recording impedance in the hypothalamus and cerebral cortex attracted much attention, both in the United States and abroad. The Australian Nobel Laureate John Eccles heard about it and wrote me a letter suggesting we should meet. I arranged for him to spend a week at UC-Davis in 1966, where he was to present two seminars and interact with faculty in the veterinary school. On a Saturday morning, Koichi Ishikawa and I met him at the San Francisco Airport after his flight down from Vancouver, where he had been visiting the University of British Columbia. With Koichi driving the car, Eccles and I sat in the back seat for the trip back to Davis. His first words were, “Now tell me about Adey.” I summarized the controversy and he then gripped my arm and said, “Well done, your Australian toughness got you through that business.” He then explained that years earlier in Australia, he had been the external examiner on Adey’s PhD thesis committee, and he had refused to sign off on the thesis, about which he had scientific and perhaps ethical concerns. From that car conversation until our last meeting in Helsinki Finland in 1989 we remained close friends, and this accounts for my subsequent publications about him (Stuart and Pierce 2006; Stuart and Zigmond 2006; Stuart and Brownstone 2011; Callister et al. 2018; in preparation).

After closely examining my Davis laboratory, Eccles requested that we send him the details on how to acquire or have constructed our then unique (for its size) electromagnetic, servo-controlled muscle-stretching apparatus. He wanted it for one of his own new laboratory setups at the American Medical Association’s short-lived Institute for Biomedical Research in Chicago (Stuart and Pierce 2006). He also emphasized quite strongly that I had insufficient training in the nuances of spinal cord neurobiology, particularly aspects introduced by Charles Sherrington (1857–1952) and refined subsequently by his trainees, including Eccles. Accordingly, he personally recommended me to Anders Lundberg (1920–2009) in Göteborg, Sweden (see the section Latter Day Mentors). He also began describing to me his perception of the history and strategy of neurophysiological research and, in particular, the impact of Sherrington on the field. This continued until our last meeting in 1989.

Bioengineering Graduate Students and Veterinary Postdoctoral Trainees

At that time, the NIH wanted to attract more bioengineers into neuroscience, and I was successful in securing very attractive fellowships for four such people. In addition, two veterinary graduates from other schools came to my laboratory with postdoctoral fellowships arranged by the dean of the veterinary school. These were all first-class young people. If we had stayed at Davis, I would certainly have had an active research group. However, none of them transferred with me to the UA. They wanted to remain at UC-Davis rather than join what they thought would be a risky academic environment in a state not known for its financial support of the overall academic enterprise.

Intramural Service

I greatly enjoyed all of my interactions with faculty in my own department, and many faculty in other departments of not only the School of Veterinary Medicine but also in the long-established School of Agriculture and the newly developing School of Engineering, particularly its department of electrical engineering. Many of these associations came about as a result of my finding time for a type of university service that became a feature of my subsequent academic goals: the pioneering of new multidisciplinary ventures. For example, I served on the first committees at UC-Davis for the establishment of university-wide programs in physiology and biomedical engineering, and the incorporation of computers into campus-wide research. For these efforts and the success of several research article submissions, UC-Davis rewarded me with a double-step promotion to step III associate professor, barely two years after my arrival. Interestingly, this promotion could have been blocked by Fats Mrak, but he chose not to do so, either out of respect for his promotion and tenure committee or his pleasure that “the young son of a ### from UCLA” was about to leave his beloved university.

In summary about UC-Davis, our two years there were a maturing experience not only for me as an academician but also for Jean in her return to teaching, and our children adapting to a new environment, countering some irritating obstacles, and supporting our older daughter as she contended with her health problems there.

University of Arizona (1967–present)

This article is being submitted 50 years after I joined the faculty of the UA as a nontenured associate professor on August 15, 1967. Neither Jean (originally a Philadelphian), our children, nor I have ever regretted the decision to come to Tucson nor have we ever lost our enthusiasm for the physical beauty of Arizona, and Tucson’s Spanish and Native American history and culture, which are strongly influenced by the city’s proximity to Mexico and the relatively high percentage (∼36 percent) of Hispanics and other Latinos who live here, the majority being Mexican Americans. Ironically, this enthusiasm coexists with our distaste for the abject failure of the state legislature and many of the governors over the years to support public education from kindergarten to the postdoctoral level. Indeed, Arizona currently ranks among the worst of our 50 states for its support of public education, a situation that seems bound to continue for many more years.

The Home Front

Jean went down to Tucson in the early summer of 1967 to find a home for us. She chose one on a street with friendly and enjoyable neighbors, many having children the same age as ours. This made for very neighborly living on the home front, which was greatly appreciated by all six of us. Jean’s career and those of our four children have blossomed here, as has their enthusiasm for the city and its overall lifestyle, and the physical beauty and uniqueness of the entire state. Our older daughter’s respiratory problems immediately abated to some extent and finally disappeared after she reached puberty, suggesting that her initial problem was more due to allergies than to a respiratory defect. Interestingly, I have little more to add here about the home front because all has gone well and most enjoyably, as described at the end of this autobiography. It can be summarized by stating that all of our family members have exploited the charms and advantages of Tucson in a manner that suited our individual needs and aspirations, while also having as maximum a set of interfamily interactions as was possible for six strong-minded individualists who nonetheless believe implacably in the concept of a united family.

In all, we had 16 years in our original home, the next 16 years in a nearby townhouse once all four of our children had left to pursue their own careers, and the next 18 years to the present in a small attractive home for just Jean and me on the far east side of Tucson with awe-inspiring views of the Rincon and Catalina mountain ranges.

My one regret is that I did not appreciate for many years the extent to which I overloaded Jean with requests that enhanced my university goals, particularly in home entertainment, much of which could have been undertaken in restaurants. This occurred not so much because I was self-obsessed but rather because I truly believed she was an all-conquering person when it came to taking on so many functions and responsibilities.

Acquiring a UA Position and Early Colleagues in Physiology and Other Areas

In late 1966, I asked my Phoenix colleague and good friend, Eduardo Eideleberg (1930–2003), to submit my CV and his recommendation to the dean of the new medical college at the UA that I be considered for a position in the department of physiology when it was appropriate to do so. A few months later, I received a letter from the new head of physiology, Paul Johnson (1928–), suggesting that I fly down to Tucson for a weekend chat about a potential position in his new department. That initial meeting in early 1967 was very pleasant and thoughtful, and all of our subsequent interactions have remained so up to the present, with Paul now retired in California but still visiting Tucson and still interested in the progress of his former department and its history.⁸ Similarly, interactions were and remain optimal with the other new faculty members of the physiology department who included, in the chronological order of their arrival, Bob Gore (1939–), appointed in December 1967 on one of Paul Johnson’s grants as a research associate; Bill Dantzler (1935–), Paul Johnson’s first actual pick, who arrived as an associate professor in February 1968; and George Hedge and Raffi Gruener (both 1939–), who were appointed as tenure-track assistant professors in August 1968. All four of these colleagues are now emeritus professors after very successful careers as experimental physiologists. They also excelled or continue to excel in other endeavors—for example, Gore scaling the Mt. McKinley Denali peak in Alaska when he first became emeritus; Dantzler as head of physiology at the UA (1991–2005) and president of the American Physiological Society (1993–1994); Hedge as chair of physiology at the University of West Virginia (1977–1998) and vice president for research at Washington State University (1998–2002); and Gruener, not only an emeritus professor of physiology at the UA but also a research professor in our College of Agriculture and Life Science, where he is undertaking research on crop production under hydroponic conditions as supported by his own U.S. Department of Agriculture grant.

In the beginning years, I also had very close, pleasant, and stimulating contact with Jay Angevine (1928–2011), a neuroanatomist from Harvard University, and Bill Sibley (1925–2015), a neurologist from Case Western Reserve University. For several years, we three taught an interdisciplinary neuroscience course to first-year medical students and some PhD trainees in relevant disciplines.

Academic Responsibilities

When I joined the UA Department of Physiology as an associate professor, I clearly understood the responsibilities of an academician at a research university, as based on my prior experience at UCLA and UC-Davis. I knew that my job would be to contribute enthusiastically to teaching; research, including research training; and service, the latter having both extramural and intramural components. As I will emphasize, our research universities would be in much better shape today if a far higher percentage of their faculty took on all five of these commitments with enthusiasm.

Teaching

Getting Started: Bob Reinking came with me to the UA, where he was paid on my primary NIH grant until June 30, 2000. This meant giving up the security of his state-funded position at UC-Davis, which he claimed recently he has never regretted. Together, we spent most of the fall semester of 1967 preparing laboratory exercises for the physiology course we would give to a class of 32 medical students in the spring semester of 1968. These exercises included the electrical stimulation of a cat brain, which we had undertaken previously for veterinary students at UC-Davis; design and use of a muscle-stimulating device, which we improved progressively in subsequent years (Reinking et al. 1971); and, to the best of our knowledge, the first intracellular recording by medical students, using the abdominal ganglion of Aplysia Californica as the experimental preparation. For the latter exercise, which required eight recording setups for four students per setup, we received much help from José Segundo (1922–) at UCLA and Felix Strumwasser (1934–2007), who was then at the California Institute of Technology. We repeated the latter exercise in the spring semester of 1969, but when the class grew to 64 students in 1970, we had to discard it for logistical reasons. Similarly, we had to discard the cat brain stimulation experiment after but one year because the cats’ postoperative maintenance was too burdensome and worrisome for our veterinary staff, an understandable problem, which we had not had at UC-Davis in the veterinary school.

Subsequent Teaching Contributions: From 1968 onward, I taught virtually all aspects of cellular and systems neuroscience to a wide variety of constituencies (e.g., upper and lower division undergraduates; graduate students in engineering and the life sciences; professional students in medicine, occupational, and physical therapy; clinical residents in neurology, neurosurgery, and orthopedics; teachers of special education; and members of the lay public). In addition to this substantial teaching at the UA, I remain the only Regents’ Professor in the State University System who has had voluntary regular teaching commitments statewide. I was a yearly instructor for 10 hours of lectures at NAU for 16 years (1991–2000, biology and exercise-science students; 2001–2007, physical therapy students) and I also began a 16-hour graduate course at Arizona State University (ASU) in 1993–1998 for largely bioengineering students and also some in biology and exercise science. I finally turned this over to the bioengineering faculty at ASU with the suggestion that they make it a full-length, one-semester course. This occurred and the course still prospers.

Research and Research Mentoring

Technical Help from Ed Perl and Motoy Kuno 1967: Shortly after arriving in Tucson and still conscious of Eccles’ 1966 criticisms of aspects of Bob Reinking’s and my recording setup at UC-Davis, Bob and I took advantage of our relatively short flying time between Tucson and Salt Lake City to visit Ed Perl (1926–2014) and Motoy Kuno (1928–2009) for a few hours in the department of physiology at the University of Utah. Ed had graciously complied with my request that we have an afternoon visit with them to review their setup for experimental electrophysiological spinal cord research, which was internationally renowned. During our visit, Ed and Motoy were most helpful, and we took back to Tucson several ways to improve our own recording setup. This proved to be most advantageous for our subsequent intracellular research with Bill Willis in Tucson and Anders Lundberg and Elzbieta Jankowska in Göteborg.

A Valuable Collaboration with Bill Willis 1970: Bill Willis (1934–2015) was one of the most intelligent all-round biologists it was my privilege to know and have as a good friend from 1964 until bad health overtook him a few years before his death. He completed his MD in 1960 at the University of Texas Southwestern Medical School and earned his PhD in physiology in 1963 under Eccles at the Australian National University. While there, Bill became a fully trained and skillful spinal neurophysiologist in the Eccles’ tradition. He then spent a few months in Italy as a postdoctoral research fellow under Professor Giuseppe Moruzzi (1910–1986) at the University of Pisa before returning to his Dallas medical school as an assistant professor of anatomy in 1963. One year later, Bill became a full professor and chairman of this department. This was the year I met and began a series of conversations with him, which culminated in Bill spending the summer of 1970 in my Tucson laboratory when he was between positions in Dallas and Galveston, where his career continued to flourish. While with us, Bill showed us how to undertake an intracellular recording spinal cord study in the Eccles’ tradition. Eccles heard me summarize this work in 1971 at an international meeting in Munich. Bill was most impressed with our recording setup for spinal cord recording, thereby giving me confidence that we were now technically “competitive” for the work I would next undertake with Lundberg and Jankowska in Göteborg.

Latter Day Mentors: Anders Lundberg and Elzbieta Jankowska (1971–1972). In 1971–1972, I, as a full professor, had the opportunity to work for seven months at the University of Göteborg with Anders Lundberg and his main collaborator Elzbieta Jankowska (1930–). At that time, they were clearly the world’s leading workers in the field of spinal cord neurobiology, and I profited greatly from our coexecuted research (Jankowska et al. 1974). As predicted by Eccles in 1966, I was also able to return from Göteborg to the UA with a far-more-complete armamentarium of spinal cord techniques, as taught to me largely by Jankowska for surgical techniques and Erling Eide (1934–) for instrumentation and data processing. Following this experience, my UA laboratory changed little in structural arrangement, albeit our data processing continued to improve.

Just as important was Lundberg’s generous allotment of time (three to four hours every Saturday morning for six months) to review the complete history of motor control science, and its prospects and possibilities. In 2008, I paid tribute to Lundberg’s stellar career in a review article written in collaboration with one of Lundberg’s former PhD trainees, Hans Hultborn (1943–; University of Copenhagen).

Interactions with the London group of Tony Taylor: It was purely by a chance meeting in Paris in 1971 that I came in contact with Tony Taylor (1928–) and his recent PhD graduate John Stephens (1946–) from the Sherrington School of Physiology at the St. Thomas’s Hospital Medical School in central London.⁹

Subsequently, they both undertook research in Tucson where their lively, friendly personalities were much appreciated in both my laboratory and the entire department of physiology. John came first for two very productive years of research in 1972–1974 on the properties and interactions between mammalian motor units and Golgi tendon organs (e.g., Reinking et al. 1975). Tony came next for six months in 1975. It was with him; my recent PhD graduate Edward Stauffer; Doug Watt, a postdoctoral trainee from McGill University; and the ever-valuable Bob Reinking that I put into good effect all that I had learned in Göteborg about intracellular recording. Our work, using spike-triggered averaging to record very small motoneuronal excitatory postsynaptic potential and inhibitory postsynaptic potential responses to the input from single spindle Ia and group II afferents and Golgi Ib afferents, created much initial discussion as to its validity (e.g., see Watt et al. 1976). Within a few years, however, our results were all confirmed in other laboratories, and even from the beginning, we had strong supporters among the motor control community. If one is to do all-night experiments of extreme technical difficulty it is well to have urbane, good-humored coworkers like these.

Another International Research Experience (1977): A few years later (1977), when supported by a Guggenheim Fellowship, I undertook six months of microneurographic neurophysiological research with David Burke (1944–) in the Division of Neurology, University of New South Wales (UNSW), Sydney, Australia. This division was headed at that time by James Lance (1926–), with whom I had once shared an interest in the genesis of various normal and abnormal tremors in humans. I had met Jim and his research group in late 1970 on a quick two-day trip to Australia for a family issue. My brief visit included a four-hour interaction with the Lance group at the Prince Henry Hospital just north of Botany Bay in Sydney. Several months later, I had extensive discussions with David Burke in Brussels and Göteborg, which have continued until the present.

With Burke and Lance in 1977, I honed my experience in the optimization of interactions between fundamental and applied (clinical) neuroscientists. Burke was later head and professor of neurology, UNSW, followed by professor of neurology and dean of research, faculty of medicine, University of Sydney. When my family and I arrived in Sydney in December 1971, he had just returned from an intensive two-year experience with Karl-Erik Hagbarth (1926–2005) at the University of Uppsala. I helped Burke restart his Hagbarth-improved microneurography research (Burke et al. 1979) in his new Australian laboratory, which subsequently became world renowned.

Recruitment of Pat Pierce (1980): I was most fortunate in having the opportunity in 1980 to hire Pat Pierce as a research assistant and technical editor. At that time, she was a substitute science teacher in the secondary schools, and she asked whether she could bring her skills to my research group. I complied immediately, the result being her 26 years of first-class work in both areas. Pat’s first-ever learning to become an excellent experimental surgeon, preparing surgically reduced anesthetized in vivo cats and later turtles, required much disciplined time and effort on her part. In parallel, however, her technical editing was first class from the start, and greatly appreciated by my coauthors and me. Our laboratory’s experimental work actually ended in 1998, after which her focus was solely on technical editing. The NIH grant that supported Pat’s salary ended in mid-2002, after which I paid her a meager salary from my private funds until all of our experimental work had been submitted for publication, which occurred in August 2006. Clearly, I owe a great deal to Pat for her dedicated and talented effort, just as I do to Bob Reinking.

My Lineage in the Field of Neuroscience

Table 1 summarizes my lineage in neuroscience, including those who trained me, whom I then trained, with whom I collaborated for refereed articles, and symposium volumes many of which I helped referee, as well as the best-known positions these various collaborators held. For the latter, the majority continued in research. Some of this group of more than 150 individuals held administrative titles, which are largely not provided in the table, where my focus is on their research. (Some comments on administrative positions are provided in the following sections.) With but three exceptions for local UA colleagues, the collaborations are limited to people with whom I had one or more published interactions, that is, either an article or review, or a publication involving me as an editor or coeditor and reviewing a person’s submission before a symposium volume was published or vice versa with me being the article submitter. Some other people who greatly influenced my understanding of some aspect of neuroscience are discussed in the following sections.

In preparing this table, I was struck by how much I enjoyed collaborative research and other academic interactive activities, how much I learned from my collaborators, and among those who are living, how much I know about their current activities, and how often we communicate with each other.

Four other people greatly influenced my development in the field of neuroscience, in general, and movement neuroscience, in particular. The following vignettes on each of these individuals are provided in the chronological order of our first interaction.

Pablo Rudomin (1934–): I first met Pablo in 1963 at an international symposium held in Villahermosa, Tabasco, Mexico. At that meeting, Pablo presented a sophisticated talk on a novel way to study baroreceptor function. He received excellent PhD mentoring in Mexico City from the renowned cyberneticist, Arturo Rosenblueth (1900–1970; Monnier 1975). Pablo is still delving deeper and deeper into the phenomenon of spinal presynaptic inhibition, which he has explored for more than 50 years, using advanced intracellular recording techniques and in recent years taking advantage of computer and mathematical simulations of its neuronal basis.

Don Maynard (1929–1973): In the mid-1960s, I had several detailed conversations with Don, a former UCLA PhD trainee of Ted Bullock, who had very advanced and sophisticated views on what invertebrate neurobiology could and could not contribute to overall neuroscience. My nascent interest in invertebrate neurobiology was greatly widened and deepened by these spontaneous “tutorials” provided by Don. It was a great tragedy that he died at such a young age.

V. Reggie Edgerton (1940–): Reggie and I met at a meeting in Birmingham, England, in mid-1971 and had the first of a detailed set of still ongoing interactions at UCLA in the summer of 1972. He has worked for almost 50 years on the adaptive properties of muscle and the spinal motor system, going from strength to strength on strategies to increase the mobility and movement quality of SCI patients. His work spans and integrates fundamental and applied clinical research, and includes several advances in computerized control of movement and its robotic assistance.

Table 1 Academic lineage of Douglas G. Stuart (1931–), including mentors, trainees, visiting scientists, and other collaborators. Column 1: Life Spans unavailable for 2/151 entries. Column 2: Origins are for country of birth or in which pregraduate school training was undertaken. Column 3: Contact year(s) for duration of training or collaboration. Citations provided in footnotes when collaborative articles not readily available on the Internet. Column 4: University positions presented do not usually include administrative titles. Nor do they include university subdivisions unless they are required for further clarification of the address. For country (three-letter) and U.S. state (two-letter) codes, see http://kirste.userpage.fu-berlin.de/diverse/doc/ISO_3166-1&2.html. Minimal addresses are provided, there being none for well-known institutions in the United States and abroad.

Summary: DGS was himself trained, and then trained and collaborated with 155 people born in 20 countries, including Australia (11), Belgium (2), Bulgaria (7), Canada (6), Switzerland (1), Republic of China (2), Cyprus (1), Czech Republic (2), France (2), Great Britain (6), Germany (4), India (1) Israel (1), Japan (10), New Zealand (2), Norway (1) Poland (1), Russia (1), Sweden (4), Turkey (1), and the United States (89).

Abbreviations: ASU-BNI, Arizona State University-Barrow Neurological Institute; BRI, UCLA Brain Research Institute; CNRS, French abbreviation for National Center for Scientific Research; MDA, Muscular Dystrophy Association; N/A, Not available; NINDS, National Institute of Neurological Disorders and Stroke; NHNN, National Hospital of Neurology and Neurosurgery; NIPS, National Institute of Physiological Sciences; NYS, New York State; Pr, present; RAS, Russian Academy of Science; S/A, See above; STH, St. Thomas’s Hospital; SUNY, State University of New York; VAH, Veterans’ Administration Hospital.

Footnotes (with citations appearing in the reference section of the text): ¹Also in 1983. ²Continued training and research collaboration throughout undergraduate and medical school years. ³Research assistant in 1967–71. ⁴Undergraduate major in electrical engineering and minor in music. ⁵Spent 32 years at UCLA and the Los Angeles film and recording industry advancing electronic music, computer-aided music instruction, psychoacoustics research, film scoring, and audio archive preservation and restoration. ⁶This mentoring was unofficial while on a sabbatical leave at the University of New South Wales, when Colebatch was a 5tth year medical student undertaking an undergraduate honors degree in physiology. His official Australian mentor, Dr. J. David Gillies (1940–), a Senior Lecturer in Medicine, was on medical leave for the first half of 1977. ⁷“Conjoint” means salary not paid by the university. ⁸While a first- and second-year veterinary medical student at UC-Davis. ⁹MD awarded in 1973. ¹⁰Currently medical director of an interdisciplinary pain control practice in Austin TX. ¹¹A private-sector medical imaging company. In 2012 created and directs RoscoeSkies Observatory and teaches astrophotography and astronomy at the University of Wisconsin in Waukesha. ¹²A private high-tech translational medicine company including molecular diagnostics. ¹³While a medical student. ¹⁴Also Director of Undergraduate Honors Program (2005–). ¹⁵Completed PhD in 1991 then spent 2 years as postdoctoral research assistant of Bill Cameron at the University of Pittsburgh before beginning medical school there. ¹⁶Currently Professor of Physical Medicine and Rehabilitation, University of Indiana, Indianapolis. ¹⁷After PhD spent one further year w/ DGS as a postdoctoral research collaborator. ¹⁸A research collaborator in 2004–07. ¹⁹A research collaborator in 1996–2006. ²⁰Latter appointment required declining promotion to Associate Professor at McGill University. ²¹Also Director, Tang Center for Herbal Medicine Research, University of Chicago. ²²Also undertook research in the Aerospace Medical Research Unit at McGill University. ²³Generated his raw PhD data in DGS lab in 1974 while a predoctoral trainee with George Moore at the University of Southern California. A postdoctoral trainee with DGS in 1975–78. See also Binder and Mendell (1990). ²⁴Postdoctoral trainee in 1979–82. ²⁵Previously, a private-sector neurologist in Bonn for 16 years. ²⁶Postdoctoral trainee in 1986–89. ²⁷Currently Professor of Physical Therapy, University of Western Ontario. ²⁸Also 2004 and 2006. ²⁹Further collaboration in 1999–05 and 2013–Pr. ³⁰Currently responsible for research and research training as Deputy Head of the Faculty of Health and Medicine, University of Newcastle, AUS. ³¹Subsequent appointment as Neurology Nurse Practitioner with Western Neurosurgery, Tucson. ³²PhD trainee of Allan Hemingway. ³³Post MD researcher with Ross Adey. ³⁴Previously Professor of Surgery, University of Osaka. ³⁵Senior Resident in Neurosurgery, Long Beach VAH. ³⁶Like Marc Binder, generated his raw PhD thesis data in DGS lab in 1974 while a predoctoral trainee with George Moore at the University of Southern California. ³⁷A private-sector pain relief company, using spinal–cord stimulation. ³⁸An MS trainee with Roger Enoka at the University of Colorado. ³⁹A health-care company. 40Initially worked with DGS as an electronics engineer at UC-Davis. ⁴¹Also in 2016. ⁴²Subsequently an Emeritus Professor of Physiology and Research Professor of Agriculture and Life Science. ⁴³Detailed discussions with DGS helped latter advance his understanding of spinal and neuromuscular systems. For editorial interactions with DGS see Burke chapters in Grillner et al. (1985), Stein et al. (1985, 1987), and Stuart and Zigmond (2006). ⁴⁴Head of this NIH laboratory for 30 years. ⁴⁵Subsequently Professor of Biology and Medicine, Brown University. ⁴⁶Collaborated in PhD training programs in physiology. ⁴⁷Substantial discussions in 1971–Pr. See also Herman et al. (1976), Grillner et al. (1986), and Stein et al. (1997). ⁴⁸See first two volumes in footnote 44. ⁴⁹Discussions as detailed as those with Sten Grillner in 1972–Pr. See also Stein (1972, 1985) and symposium volumes in footnote 47. ⁵⁰Also in 1985 and 1986. ⁵¹Also in 2001–02. ⁵²See Fetz et al. (1979). ⁵³See footnote 52 article and Binder and Mendell (1990). ⁵⁴Forrnerly Professor of Physiology at Universities of Ataturk (1975–1999), Trabzon (1999–2002), and Adana (2002–2004), TUR. ⁵⁵Founding member of the Arizona Movement Neuroscience Group. ⁵⁶Subsequently Professor of Movement Neurosciences, University of Illinois-Chicago. ⁵⁷As in footnote 55. Also collaborated with DGS in 2004–07. ⁵⁸Biomedical Engineering is a joint program with Emory University. ⁵⁹Also Professor of Biomedical Engineering and Physiology, Northwestern University and its Chicago Campus, respectively. ⁶⁰As in footnote 55. ⁶¹First University of Arizona PhD trainee to undertake interdisciplinary movement neuroscience training along with her standard speech and hearing science courses. ⁶²As in footnote 52. ⁶³Also in 1987 and 1989. ⁶⁴Subsequent positions as Professor of Physiology included the Universities of Calgary and the University of Gaevle, Umea, SWE. ⁶⁵Subsequently, Professor of Marine Biology, University of North Carolina, Wilmington. ⁶⁶Also in 2004. ⁶⁷Co-I in footnote 68 NIH award. ⁶⁸Co-PI of NIH motor control award for PhD and postdoctoral trainees. ⁶⁹Also Research Professor of Physiology, University of Arizona, and later Professor of Biomedical Sciences and Health and Human Performance, Iowa State University. ⁷⁰As in footnote 67. ⁷¹Regularly spaced updates and advice to DGS on developments in invertebrate neurobiology. ⁷²Previously Professor of Biological Sciences, Columbia University. ⁷³As in Grillner et al. (1986). ⁷⁴Also a consultant in Neuropediatrics. ⁷⁵As in footnote 67. ⁷⁶As in footnote 67 followed by an interdisciplinary administrative research training position. ⁷⁷As in footnote 67 followed by continued similar student training. ⁷⁸Regularly spaced helpful discussions with DGS on statewide developments in experimental science in general, and neurobiology, in particular. ⁷⁹Provided advice in Tucson to DGS laboratory group on methods to study the in vivo turtle spinal cord. ⁸⁰Currently Professor of Medical Science, International University of Health and Welfare, Ohtawara (one of the seven sites of this university in JPN). ⁸¹Collaborated with DGS on development of new interdisciplinary biomedical research programs at the University of Arizona. ⁸²Also in 2001–02. ⁸³Subsequently Professor in Neurological Sciences Institute, Oregon Health and Sciences University, Portland. ⁸⁴Also in 2003–04. ⁸⁵As in footnote 67. ⁸⁶Near-weekly discussions with DGS on strategy of motor control research and research training. ⁸⁷See Ito (2011; p. ix ) followed by his comment that the editorial help he received from DGS “was not simply for English but included broad aspects of motor system physiology. It was a valuable interaction for me.” ⁸⁸Also commented that his “most unique (presumably meaning important) subsequent administrative function was as “founding director of the Riken Brain Science Institute (launched in 1997).” ⁸⁹Collaborators on previous strictly historical articles included in their chronological order Roger Enoka (1990), Jennifer McDonagh (1998, 2001), Alan Brichta and Robert Callister (2001). ⁹⁰See Stuart and Zigmond (2006). ⁹¹Shares with DGS passion for the history of neuroscience; e.g., Stuart and Brownstone (2011), Brownstone and Stuart (2011). ⁹²Also Research Assistant Professor, Dept. Biomedical Sciences, Sch. Public Health, SUNY-Albany. ⁹³Professor, Dept. Biomedical Sciences, Sch. Public Health, SUNY-Albany. ⁹⁴See, e.g., Clarac, Massion, and Stuart (2009). ⁹⁵Played a prominent role in Stuart, Schaefer, Massion, Graham, and Callister (2014). ⁹⁶Also in 2013–14 with Roger Enoka a coauthor. ⁹⁷Also researcher in the Laboratory of Applied Biology and Neurophysiology. ⁹⁸Robert Callister is the primary coauthor on this project, which is a review of the contributions of Sherrington and Eccles to central inhibition.

Daniel Kernell (1940–): Daniel is a Swede by birth. His research and conceptual ideas, like those of Bob Burke, who appears in my lineage table, led the way throughout the 32 years (1966–1998) during which I undertook intracellular recording experiments on the spinal motor control system. I first met Daniel in late 1971 at the Karolinska Institute in Stockholm while he was still working with Ragnar Granit. We have had innumerable interactions since then in several countries and in our respective laboratories. After his retirement from the University of Gronenberg in The Netherlands, he wrote a valuable monograph, which summarized much of the work on the spinal motor system, both classic and throughout his career in this field. Recently, at the age of 80, he wrote a monograph on colors and color vision, an inspiration to all of us to keep our minds sharp.

Moscow Motor Control School: The post-WWII Moscow Motor Control School also had a powerful effect on my development as a movement neuroscientist. For me, this school was epitomized by Nicolai Bernstein (1896–1966); Israel Gelfand (1913–2009); Michael Tsetlin (1924–1966); Bernstein’s last PhD student, Victor Gurfinkel (1922–); and about 22 others. Working under far-from-optimal circumstances, this largely Jewish group’s accomplishments and emphasis on interactions between invertebrate and vertebrate neuroscientists, life- and physical scientists, and basic and clinical scientists have been an inspiration to those of us who have attempted to emulate their interdisciplinary efforts in our own institutions’ research and training programs in motor control neurobiology.

The Arizona Motor Control Group: With this group in mind, four colleagues and I founded the Arizona Motor Control Group in 1982 (see Table 1). Our initial group was appropriately interdisciplinary with expertize available among us in advanced neurophysiological recording, biomechanics, comparative vertebrate motor control, mathematical modeling, normal and abnormal speech motor control, neuropsychology, and human respiratory control. Many more areas were added as our group increased to 33 members by 2000, including more faculty from not only the UA but also statewide, including ASU in Tempe, the Barrow Neurological Institute (BNI) in Phoenix, and NAU in Flagstaff. Our training faculty were more or less evenly divided among those institutions whose experimental animal models were invertebrates, nonmammalian vertebrates, and mammals, including humans. To aid our activities, Jim Bloedel from the BNI and I codirected an NIH-funded pre- and postdoctoral program in interdisciplinary motor control neurobiology. Between 1987 and mid-2002, this program mentored more than 100 American PhD students and 120 postdoctoral trainees from the United States and several other countries.

A key feature of our training program was a Friday afternoon gathering at the UA, which we entitled “Doings in Motor Control.” At this function, the attendees, including visiting speakers, presented their ideas and research, with “out-of-town” faculty and trainees frequently presenting their work and ideas. “Doings” emphasized dialogos (mentioned earlier as “dialogue without rancor”) throughout the presentations. Many found this disconcerting because there were occasions on which the speaker did not get far because of the vigorous discussion of the appropriateness of the title of her or his talk. Because of its free-wheeling, intense-discussion approach, our “Doings” became widely known and discussed in the United States and abroad.

Summary of Main Research Foci (1967–Present)

Experimental neuroscience is done by human beings, each one an individual with some unique characteristics. As a result, the reasons that some go into neuroscience are manifold, as are their contributions. Personally, I admire the most those who blaze a new trail and stick to it throughout their lifetime, with several such people in Table 1. Others, for some reason or another are like me, a player in what I call “the ultimate game.” We make contributions that help advance our field but we are not its stars. In my case, I started late and to have any success in movement neuroscience, with an emphasis on the spinal cord, I had to learn techniques whose mastery brought me great personal satisfaction. Where I was strongest was in the people I was able to attract to my laboratory, either as a trainee or an experienced collaborator. Now, at the age of almost 86+ years, I am as intrigued by the field of movement science to the same extent as more than 60 years ago, with my current interest expressed largely in the form of historical articles and reviews. Several of these have been coauthored by close, long-standing friends made while I was still undertaking experiments. As I reflect on this, it would seem that the human side of movement neuroscience has been my emphasis, expressed in experimental work, reviews, and symposium volumes.

Experimental Work Published in Refereed Journals

My areas of research emphasis were more or less undertaken and published in chronological order: the hypothalamus and temperature regulation, the rhythm of various tremors, the nature and neural control of locomotion, the segmental motor system (my main lifetime focus), and, finally, the history of neuroscience, in general, and movement neuroscience, in particular. Among these, the experiments that excited me the most were those involving intracellular recording from spinal motoneurons in surgically reduced spinal cats (usually requiring at least 24-hour experiments) and from spinal interneurons in slices of turtle spinal cord. Figure 1 shows my progression from the 19th-century-like equipment used in my PhD thesis to the late-20th-century electronic and computer equipment used in my intracellular recording work, which was progressively improved by Bob Reinking between 1965 and the early 1990s.

Fig. 1. Transition of experimental recording setup from late-19th-century respiratory and movement monitoring to late-20th-century electrophysiological recording. The top panel shows equipment used for my PhD research, whereas the bottom panel shows my late-20th-century setup for intracellular recording from spinal motoneurons in surgically reduced anesthetized cats and spinal interneurons in slices of turtle spinal cord. Bob Reinking is shown in the rear of the bottom panel. He was primarily responsible for all of the improvements made in my laboratory’s electrophysiologial and data processing instrumentation.

Coauthors of Publications

Many of my contributions have been coauthored by colleagues in several countries, the most born in America (77), and collaborating authors from 19 other countries, including Australia (11), Belgium (1), Bulgaria (2), Canada (5), China (1), Crete (1), Cyprus (1), the Czech Republic (1), France (2), Germany (3), India (3), Israel (1), Japan (7), New Zealand (2), Russia (1), South Korea (1), Sweden (4), Switzerland (1), and the United Kingdom (5). Despite the fewness of coauthors from these latter countries, they (even Australians) taught me much about the world, and the details of our discussions come instantly to mind.

Contributions in Reviews

My reviews, chapters in symposium volumes, and research monographs, which I usually also wrote with colleagues, have possibly had at least as much impact on the field of segmental motor control as my research contributions. In these conceptual contributions, my coauthors and I challenged our peers and ourselves to address key unresolved issues, and employed a “user-friendly” style to the benefit of pre- and postdoctoral trainees, the next generation of movement neuroscientists. Among these contributions, the best-known are on (1) the need to effect a stronger interface between neurophysiology and biomechanics (Hasan et al. 1995); (2) aspects of the proprioceptive contribution to the control of movement, which are still largely unexplored (Hasan and Stuart 1988); (3) a research monograph on the neurobiology of muscle fatigue, which was dedicated to the research contributions of Brenda Bigland-Ritchie (1927–; see Gandevia et al. 1995); (4) a symposium volume on sensorimotor control of posture and movement (Gandevia et al. 2002); and (5) another symposium volume on overall brain mechanisms for the integration of posture and movement (Mori et al. 2002). The Gandevia and colleagues (1995) and Mori and colleagues (2002) volumes were compiled and edited electronically in my UA laboratory and required the skillful editorial and technical editing of Pat Pierce.

Current Research Focus: The History of Movement Neuroscience

Since writing my PhD thesis, which began in the fall of 1960, I have greatly enjoyed the history of my research foci. This led to 31 solely historical publications between 1962 and August 2017, including an unusually detailed article yet to be submitted for peer review. Among this group, there were four publications in which the history was of a broad scale, whereas the other 27 focused on a specific issue, a single person, or a group of people. The latter to this point include in their original citizenship and alphabetical order four Americans (Alexander Forbes, Elwood Henneman, Harry Patton, and Walter Woodbury), four Australians (Lawrence Brock, John Coombs, David Curtis, and John Eccles), many Russians (Nicolai Bernstein, Ivan Sechenov, Fyodor Severin, Mark Shik, Grigori Orlovsky, and several others in the Moscow Motor Control Group), three British subjects (Brenda Bigland-Ritchie, Thomas Graham Brown, and Charles Sherrington), one Frenchman (Jacques Paillard), two Swedes (Sten Grillner and Anders Lundberg), and one Swiss subject (Walter Hess). In retrospect, I felt honored to write about all of them.

Faculty Collaborators for Historical Research: My collaborators for this work came from close and far. Some were my research mentors, both formal and informal; some were from my later research group; and a large group were coeditors or coauthors of relevant volumes and articles. In addition to the people I have noted, all of whom I knew quite well, I coauthored a widely read historical article with two authors I had not met at the time of our collaboration (I have still not met one of them). They were great fun to work with, like all the others. In retrospect, it amazes me how many collaborators I have had for my history projects.

Essential Help of Reference Librarians: I owe a great debt of gratitude to the five UA reference librarians who have ferreted out details for my history publications since 1976. First were two in the Arizona Health Sciences Library: Nga Nguyen, who has continued voluntarily since her retirement, and Kathy Tower. They both insisted that they relished the challenge of a difficult assignment. Next came three in the main UA library: first Ellen Knight and then joined by Joan Schlimgen and Mary Feeney. Their quiet confidence in taking on the most difficult of assignments has been a boon to my endeavors.

In addition to these stalwarts, I have interacted with many highly competent reference librarians and library administrators in several countries, including Australia, Canada, Germany, Japan, New Zealand, the United Kingdom, and the United States. In all cases I received the utmost of cooperation.

Service: Traditional Extramural Contributions

Like most researchers at major research universities I was a member of an NIH Study Section, mine having been Applied Physiology and Biomedical Engineering in 1974–1978, an impressive and enjoyable group of engineers and physiologists who were truly dedicated to assisting beginning applicants get funded to assist their emerging careers in orthopedics, biomedical engineering, and advanced forms of exercise science. This was followed by several ad hoc NIH assignments spread over many years. I was also a member of the Scientific Advisory Committee, Muscular Dystrophy Association (1987–1989); and the editorial boards of the American Journal of Physical Medicine (1975–1987), Journal of Neurophysiology (1979–1984), and Experimental Neurology (1982–1987). For the International Union of Physiological Sciences (IUPS), I was a member of the U.S. National Committee (chair, 1989–1992) and, for many years, I also was a member of the four-person IUPS Motor Control Commission, which was chaired by my close colleague, Sten Grillner. These latter appointments illustrate my interest in fostering international neuroscience, in general, and movement neuroscience, in particular. Since the early 1970s, I have undertaken a substantial amount of North American and international reviewing of physiology and neuroscience research articles and programs, and I have played a supportive role in the careers of innumerable young motor control scientists in North America and abroad.

Locomotion Research: Sten Grillner, Paul Stein (Washington University at St. Louis), and I have long believed that for study of locomotion there is need to incorporate findings made on invertebrates, nonmammalian vertebrates, mammalian tetrapods, nonhuman primates, and humans (for this approach, I coined the term, “interphyletic awareness”). We were co-organizers of three international conferences held about 10 years apart, with each followed by a symposium volume: Herman and colleagues (1976), Grillner and colleagues (1986), and Stein and colleagues (1997). The local organizers for these conferences were Richard Herman (also conference chair; now with the Good Samaritan Medical Center, Phoenix) for the Valley Forge, Pennsylvania, meeting in 1975; Grillner (also conference chair) for the Stockholm meeting in 1985; and, myself for the Tucson meeting in 1995 (conference chair, Stein). The preface to Stein and colleagues (1997) states tellingly, “The three volumes share common concepts: neuronal networks generate motor behavior, and comparisons of model systems distributed throughout the animal kingdom provide insights into general principles of motor control.” I retired from the planning group for the subsequent meeting in Stockholm in 2006 but attended the meeting, which featured a subsequent publication in a research journal to garner wider readership now that PDF files have become utilitarian.

Bulgarian International Symposia on Motor Control: These symposia were held nine times between 1969 and 2004. Their main purpose was to foster collegiality, cooperation, and scientific interactions among the international motor control community, including the means for Eastern European and Soviet faculty and trainees to have close, person-to-person contact with leading investigators from the West. I attended these meetings from 1981 to 2000, and I made four contributions to help ensure the continued success of the venture: (1) I secured U.S. National Academy of Science funds to lead a nine-person delegation of U.S. workers to the 1985 symposium. (2) I also secured an NSF award to undertake a six-person exchange (1986–1989) of motor control scientists between the UA/BNI and the Bulgarian Academy of Sciences. (3) I was a member of the four- to five-person international advisory commission, which provided input for the 1985–2000 symposia. (4) In an extraordinarily time-consuming effort, I had the 1993 symposium expanded into a volume that was edited and compiled in my UA laboratory, again working with Pierce, but in addition, soliciting the editorial help of the entire UA/BNI motor control group and many extramural peers. The result was a volume in which all of the Eastern Bloc authors’ contributions (63 of 94 chapters) were presented in polished English to optimize these investigators subsequent interactive possibilities with their Western colleagues.

The Moscow Motor Control Group: I had studied the work of some of the Moscow Motor Control School (Victor Gurfinkel, Mark Shik, Grigori Orlovsky, Yuri Arshavsky, and several others) prior to meeting Gurfinkel and Shik in person in Munich, Germany, in 1971. Since then, I have written much about their stellar accomplishments.

Aiding Japanese Colleagues: From 1960 onward, I have helped many Japanese colleagues with their usage of the English language. This emphasis was more formalized when I coedited with Shigemi Mori (1936–) and Mario Wiesendanger (1931–2017) a symposium volume entitled Brain Mechanisms for the Integration of Posture and Movement. This symposium was held in Mori’s institute in Okazaki, with the subsequent symposium volume prepared in my Tucson laboratory. All 49 chapters were subject to the technical editing of Pat Pierce, and I paid particular attention to the 22 chapters written by Japanese workers. Most recently, and at his request, I edited the third and last 2011 volume of Masao Ito (1928–) on the cerebellum. This was a challenging and enjoyable assignment requested by a remarkably gifted neuroscientist, which is discussed in detail in an upcoming review by Callister and colleagues (2018; in preparation).

Service: Intramural Contributions

My interest in intramural service extended far beyond my departmental and medical college obligations, valuable and essential as these were and will always be. I had 17 years of graduate college experience, eight as a representative (1970–1975, 1999–2002), and nine as a member of the Graduate Council. These positions strengthened my all-around interest and knowledge about the functioning of the entire university. While on the Council, we approved the beginning of a program in applied mathematics over the objections of the head of the department of mathematics and several of his henchmen. Applied mathematics became and remains one of the strongest programs of the university. Membership on the Graduate Council also indirectly gave me a way to successfully strategize and bring about a well-funded invertebrate neurobiology program and university-wide programs in neuroscience and physiological sciences. These successes also led to me gaining considerable central administrative support for a program in biomedical engineering and aiding the support for a new learning and memory group.¹⁰

Camaraderie in the Field of Movement Neuroscience

The movement neuroscientists of my and the next generation have been a remarkably affable group, indeed their interactions are a model of how international science should be conducted. This was not always the case among the generation of movement neuroscientists that preceded mine when there were far fewer participants and research groups. Also, among some other areas of current emphasis there is less affability, particularly in molecular biology. One reason for this may be the way data are generated and discussed in my generation’s movement neuroscience. Most of us use or at least keep abreast of both inside-out and outside-in approaches, such that those focusing on human studies show interest in invertebrate results and vice versa. This is not totally the case: a degree of “test-subject tribalism” still exists in movement neuroscience, but it does not extend to not giving credit when it is clearly due. Furthermore, those who have incorporated molecular biology into movement neuroscience have done a particularly good job in explaining the nature and significance of their results.

Faculty Attitudes at Research Universities

All of my published research and other academic activities have been undertaken at research universities: UCLA, UC-Davis, and the UA in the United States; the University of Göteborg in Sweden; and the University of New South Wales in Australia. Focusing on the United States, in general and the UA in particular, I believe that too many faculty are so imbued in their research and teaching responsibilities that they neglect the need and value of making a contribution to the type of on-campus service that strengthens their university’s academic enterprises, like new programs necessary for a balanced curriculum, and those desired by the students, themselves, and their local communities. A few years ago, I expressed this sentiment to a very wise and successful UA president. He rejected my complaint. His experience was that only about 15 percent of the faculty at a research university in the United States or abroad really care about their institution. He believed that it is up to this 15 percent to guard the “intramural service freedom” of the remaining 85 percent because among the latter so many are making research contributions of great societal benefit. For many years, I accepted this president’s point of view. Now, however, at the age of 86 and having discussed the issue with many colleagues in the United State and abroad, I believe that a 15 percent fully committed faculty are too few to keep a research university at the forefront and suggest that 40 percent with the best interests of the university at heart would be a sounder situation.

Another faculty attitude of concern is the amount of support they give to their students, both those they teach at the undergraduate and graduate level, and those they mentor in research in their own laboratories. Donald Kennedy (1931–) of Stanford University addressed this issue in his thoughtful 1997 book Academic Duty. An outstanding motor control researcher throughout his academic career, Kennedy emphasized the value of “putting students and their needs first” (1998, p. 287), an adage as appropriate for his own institution as it is for all other research universities.

Good Fortune in Combining Family and Academic Life

Finally, it is a great pleasure to end this autobiography with comments on my family life, which, together with the laboratory efforts of Bob Reinking and Pat Pierce, has been the mainstay of my academic endeavors. My wife, Jean (née Rassbach) was born (1935) and raised (until 15) in Philadelphia. Her mother, Evelyn (1901–1992), a member of the Daughters of the American Revolution, was a native of Gettysburg, Pennsylvania, and a home economics graduate (1924) of the Carnegie Institute of Technology in Pittsburgh. Her father, Phillip (1901–1970) was raised in Washington, DC, before graduating from the same institution as his future wife (1925; BS in metallurgical engineering). He subsequently had a distinguished career in the steel industry: first (1925–1950) with Midvale Steel (Philadelphia), where he rose to general manager and developed a U.S. patent on low-chromium steel; and subsequently with Union Carbide (1951–1970), where he became director of the Metals Division, and provided substantial service to the post-WWII rebuilding of the Japanese steel industry.

Jean Rassbach Stuart is a 1953 graduate of New Trier High School, Winnetka, Illinois, followed by a BA in child guidance and development from MSU (1957) and an MA in educational counseling from the UA (1972) and a certificate in gerontology counseling also from the UA (1990). For 24 years, she was a teacher and guidance counselor in California (Santa Monica, 1957–1958; Dixon, 1965–1967) and Arizona (Pima County Guidance Project, 1972–1978; Tucson Unified School District I, 1978–1993). Our four children have intriguingly diverse occupations. Michael (Monty) Stuart (1957–; married to Deborah Murphy, a former office manager; one high school daughter) is a former stuntman, and now horse-trainer, wrangler, and stunt coordinator in the Los Angeles television and movie industry, where he is still having considerable success.¹¹ Kathy (1959–; married to Thomas Lohse, a Tucson businessman; three adult children) is a UA graduate (BA, 1980; MA, 1998), a former bilingual (English/Spanish) grade-school teacher, and now a coordinator of problem-based learning with the Tucson Unified School District. Daniel (1961–) is a well-known song and music writer, concert performer, former bandleader, and author who lives in Mexico City.¹² His son, a third-year college student, lives in New York City with his Barcelona-born mother, Nuria Morgado, an associate professor of Spanish literature, at the State University New York, Staten Island and Manhattan campuses. Cynthia (1963–; married to Michael Sadowsky, a Tucson businessman; two adult children) was a preschool teacher who now writes books and poems for young children. Jean and I have a particularly active family life in Tucson with our two daughters and their spouses, and the two grandchildren still in Tucson.

Acknowledgments

For the preparation of this article, I thank Hiromi Yamaguchi, Physiological Society of Japan; some faculty colleagues, Ann Baldwin, Robert Callister, and Tim Secomb; a recent UA undergraduate physiology graduate, Roxeanne Deasis; and two librarians in the main UA library, Mary Feeney and Ellen Knight. I also thank Ann Baldwin, Robert Brownstone, Jean Massion, Tim Secomb, and Paul Stein for their comments on various drafts of the article.

Selected Works by the Author

Hypothalamus and Temperature Regulation

Hemingway A & Stuart DG (1963). Shivering in man and animals. In Temperature—Its Measurement and Control in Science and Industry, ed. Herzfeld CM, pp. 407–427. Reinhold, New York.

Stuart DG, Kawamura Y & Hemingway A (1961). Activation and suppression of shivering during septal and hypothalamic stimulation. Exp Neurol 4, 485–506.

Stuart DG, Maxwell DS, Hayward JN, Fairchild MD, Adey WR & Porter RW (1963). Unit activity in the hypothalamus. Bol Inst Med Biol Univ Nac Autom Mex 21, 349–370. Also: (1964). First Conference on Neurobiology—Feedback Systems Controlling Nervous Activity, ed. Escobar A, pp. 226–247. Sociedad Mexicana De Ciencias Fisiológicas, A.C., Mexico City.

Rhythm of Various Tremors

Stuart DG, Eldred E, Hemingway A & Kawamura Y (1963). Neural regulation of the rhythm of shivering. In Temperature—Its Measurement and Control in Science and Industry. Vol 3, Part 3, ed. Herzfeld CM, pp. 545–557, Reinhold, New York.

Stuart DG, Ott K, Ishikawa K & Eldred E (1966c). The rhythm of shivering. III. Central contributions. Am J Phys Med 45, 91–104.

Stuart DG, Wild WO & Eldred E (1966d). Comparisons between the physiological, shivering and Parkinsonian tremors. J Appl Physiol 21, 1918–1924.

Nature and Neural Control of Locomotion

Goslow Jr. GE, Reinking RM & Stuart DG (1973). The cat step cycle: hind limb joint angles and muscle lengths during unrestrained locomotion. J Morphol 141, 1–41.

Grillner S, Stein PSG, Stuart DG, Forrsberg H & Herman RM, Eds. (1986). Neurobiology of Vertebrate Locomotion. MacMillan, London.

Herman RM, Grillner S, Stein PSG & Stuart DG, Eds. (1976). Neural Control of Locomotion. Plenum, New York.

Stein PSG, Grillner S, Selverston AI & Stuart DG, Eds. (1997). Neurons, Networks, and Motor Behavior. MIT Press, Boston.

Wetzel MC & Stuart DG (1976). Ensemble characteristics of cat locomotion and its neural control. Prog Neurobiol 7, 1–98.

Segmental Motor System

Brownstone RM & Stuart DG (2011). Whither motoneurons? Brain Res 1409, 93–103.

Burke D, Skuse N & Stuart DG (1979). The regularity of muscle spindle discharge in man. J Physiol (Lond) 291, 277–290.

Fetz EE, Henneman E, Mendell LM, Stein RB & Stuart DG (1979). Properties of single cells in vertebrate motor systems revealed by spike-triggered averaging. In Summaries of Symposia, 8th Annual Meeting, Society for Neuroscience, BIS Conference Report No. 49, pp, 11–32. UCLA Brain Information Service/BR1 Publications Office, Los Angeles.

Gandevia SC, Enoka RM, McComas AJ, Stuart DG & Thomas CK, Eds. (1995). Fatigue—Neural and Muscular Mechanisms. Plenum, New York.

Hasan Z & Stuart DG (1988). Animal solutions to problems of movement control: the role of proprioceptors. Ann Rev Neurosci 11, 199–223.

Hasan Z, Enoka RM, & Stuart DG (1985). The interface between biomechanics and neurophysiology in the study of movement: some recent approaches. Exerc Sport Sci Rev 13, 169–234.

Homma S, Ishikawa K & Stuart DG (1970). Motoneuron responses to linearly rising muscle stretch. Am J Phys Med 49, 290–306.

Hornby TG, McDonagh JC, Reinking RM & Stuart DG (2002). Effects of excitatory modulation on intrinsic properties of turtle motoneurons. J Neurophysiol 88, 86–97.

Jankowska E, Lundberg A, Roberts WJ & Stuart DG (1974). A long propriospinal system with direct effect on motoneurones and on interneurones in the cat lumbosacral cord. Exp Brain Res 21, 169–194.

Reinking RM, Stephens JA & Stuart DG (1975). The tendon organs of cat medial gastrocnemius: significance of motor unit type and size for the activation of Ib afferents. J Physiol (Lond) 250, 491–512.

Watt DGD, Stauffer EK, Taylor A, Reinking RM & Stuart DG (1976). Analysis of muscle receptor connections by spike-triggered averaging: 1. Spindle primary and tendon organ afferents. J Neurophysiol 39:1375–1392.

Overall Control of Posture and Movement

Gandevia SC, Proske U & Stuart DG, Eds. (2002). Sensorimotor Control of Movement and Posture. Kluwer Academic/Plenum, New York.

Mori S, Wiesendanger M & Stuart DG, Eds. (2004). Brain Mechanisms for the Integration of Posture and Movement. Elsevier, Amsterdam.

Stuart DG, Ed. (1996). Motor Control VII. Motor Control Press, Tucson.

History of Neuroscience and Movement Neuroscience

Callister RJ, Brichta A, Schaefer AT, Graham BA & Stuart DG (2018; in preparation). Pioneers in CNS inhibition: 2. Charles Sherrington and John Eccles on inhibition in spinal and supraspinal structures.

Clarac F, Massion J & Stuart DG (2009). Reflections on Jacques Paillard (1920–2006)—A pioneer in the field of motor cognition. Brain Res Rev 61, 256–280.

Stauffer EK, Stuart DG, McDonagh JC, Hornby TG & Reinking RM (2005). Historical reflections on the after-hyperpolarization firing rate relation of vertebrate spinal neurons. J Comp Physiol A 191, 135–146.

Stuart DG (2007). Reflections on integrative and comparative movement neuroscience. Integr Comp Biol 4, 82–504.

Stuart DG & Brownstone RM (2011). The beginning of intracellular recording in spinal neurons: facts, reflections, and speculations. Brain Res 1409, 62–92.

Stuart DG & Pierce PA (2006). The academic lineage of Sir John Carew Eccles (1903–1997). Prog Neurobiol 78, 136–155.

Stuart DG & Zigmond MJ, Eds. (2006). The contributions of John Carew Eccles to contemporary neuroscience. Prog Neurobiol 78, 136–326.

Stuart DG, Clarac F, Barbara J-G, Brownstone RM, Duchateau J & Enoka RM (2011). Paths of discovery in motoneuron neurobiology. Brain Res 1409, 1–103.

Stuart DG, Schaefer AT, Massion J, Graham BA & Callister RJ (2014). Pioneers in CNS inhibition: Ivan M. Sechenov, the first to clearly demonstrate inhibition arising in the brain. Brain Res Rev 1548, 20–48.

References of Others

Anonymous (1972). Allan Hemingway 1902–1972. Physiologist 15, 394–395.

Binder MD & Mendell LM, Eds. (1990). The Segmental Motor System. Oxford University Press, New York.

Field J, Sawyer CH, Tschirgi R & Sonnenschein R (1981). Victor E. Hall, Physiology: Los Angeles. 1901-1981, Professor Emeritus. Callsphere, University California. pp.168–169. See also http://tinyurl.com/jd4qrll.

Ito M (2011). The Cerebellum—Brain for an Implicit Self. Pearson FT Press, New Jersey.

Kennedy D (1997). Academic Duty. Harvard University Press, Cambridge (MA).

Kolin A & Kado RT (1959). Miniaturization of the electromagnetic blood flow meter and its use for the recording of circulatory responses of conscious animals to sensory stimuli. Proc NAS 42, 1312–1321.

Lambert EF (1951). The Twenty Thousand Thieves. Newmont, Melbourne 1951. (Self-published but later published by Muller, London. Now in its 11th print by Penguin Publishers, Australia.

Monnier A (1975). Arturo Rosenblueth. Dictionary of Scientific Biography. Scribner’s, New York.

Megalogenis G (2015). Australia’s Second Chance. Penguin Publishing Group, Australia.

Stein PSG, Chair (1972). Workshop—Sensorimotor Integration, Session 45. 2nd Annual Meeting, Society for Neuroscience, Houston.

Stein PSG, Organizer (1985). Motor Control: From Movement Trajectories to Neural Mechanisms. Short Course Syllabus. Society for Neuroscience, Bethesda, MD.

¹Encyclopedia of Mental Disorders, “Electroconvulsive Therapy,” http://www.minddisorders.com/Del-Fi/Electroconvulsive-therapy.html.

²American Physiological Society, “Douglas G. Stuart,” http://www.the-aps.org/mm/Membership/Living-History/Douglas-Stuart.

³Wikipedia, “Russian Australians,” https://en.wikipedia.org/wiki/Russian_Australians#The_fourth_wave_1945-1960.

⁴National Archives of Australia, “60 Years of Snowy Mountains Hydro-Electric Scheme,” http://naa.gov.au/collection/snapshots/power/index.aspx.

⁵Wikipedia, “Walter Jackson Freeman III,” https://en.wikipedia.org/wiki/Walter_Jackson_Freeman_III.

⁶UC Riverside, “Donald M. Wilson,” http://faculty.ucr.edu/~currie/donald-wilson.htm.

⁷Washington State University, “Dr. Bustad, Founder of PPP,” http://tinyurl.com/hmb35ho.

⁸American Physiological Society, “Paul C. Johnson,” http://www.the-aps.org/mm/Membership/Living-History/Johnson.

⁹For more details on this meeting, see American Physiological Society, “Douglas G. Stuart,” http://www.the-aps.org/mm/Membership/Living-History/Douglas-Stuart.

¹⁰For more details on these developments, see American Physiological Society,“Douglas G. Stuart,” http://www.the-aps.org/mm/Membership/Living-History/Douglas-Stuart.

¹¹IMDB, “Monty Stuart,” http://www.imdb.com/name/nm0835811/.

¹²See Wikipedia, “Dan Stuart,” http://en.wikipedia.org/wiki/Dan_Stuart.

Index

Abbott, B., 581

Abbott, L., 440, 441, 442

Abebe, M. S., 342, 343

Abrams, T., 130

Adams, N., 370

Adams, P., 433, 532

Adams, R., 16, 397

Adesnik, H., 497

Adey, W. R., 581, 582, 585, 588, 589, 590, 594, 605

Agalliu, D., 55, 62

Aghananian, G., 247

Agmon, A., 547, 548

Agnati, L., 240, 253, 259, 261, 262, 263, 266, 267, 278

Agnew, S., 388

Aguayo, A., 92, 177

Aguirre, J., 279, 280, 281

Ahn, C., 162

Aizenmann, E., 180

Ajuriaguerra, J., 241

Akerman, C., 522

Alberini, C., 147, 150

Albers, G., 177

Albright, T., 194

Alder, J., 367

Alexander, W., 391

Alexandrescue, A., 148

Alfred, W., 164

Alger, B. E., 474, 477, 479, 483, 486, 497

Allen, G. I., 473

Allen, N., 51, 62

Altman, J., 94

Amara, S., 147

Ambady, N., 67, 68

Amin, I., 512

Anagnoste, B., 245

Anden, N. E., 234, 236, 237

Andersen, P., 113, 476, 610

Andersen, R. A., 324, 341

Anderson, D., 366

Anderson, M., 571

Andersson, K., 240, 256, 257, 258

Andolina, I. M., 547

Andrade, R., 478, 497

Angevine, J., 597

Anne, S., 372

Antonelli, T., 277

Arana, G. W., 396

Arbas, E. A., 608

Arber, W., 357

Arbuthknott, G., 237

Arbuthnott, G., 87

Arenas, E., 270, 275

Århem, P., 291

Arshavsky, Y., 619

Artis, K., 212

Ascher, P., 175, 430, 432

Atwater, A. E., 606

Axel, R., 63, 361, 364

Axelrod, J., 196, 198, 199, 200, 203, 217, 220, 238

Ayad, N., 374

Ayala, F., 142

Babcock, D., 180

Bach, J. S., 329

Bagnall, M., 141, 142, 144, 145

Bahill, A. T., 607

Bailey, E. F., 609

Bakay, R., 101

Baldessarini, R., 397

Baldwin, J., 513

Baltimore, D., 63

Balu, D., 218, 219, 220

Banker, G., 40

Barash, S., 328

Barbara, J. G., 610

Bargmann, C., 63, 365, 372, 373, 376

Barker, D., 430, 431

Barkmeier-Kraemer, J. M., 609

Barlow, C., 310, 317

Barlow, H., 526

Baron, D. See Goldberg, D.

Barondes, S., 411

Barres, B. A., 2, 19, 20, 21, 24, 25, 39, 46, 49, 63

Barres, J., 2

Bartos, M., 442

Basbaum, A., 525

Battista, A. F., 245

Baulieu, E. E., 256

Baumgarten, H. G., 88

Bear, M., 175

Beaulieu, M., 203

Bechter, K., 290

Beck, W. S., 309

Becker, L., 356

Beckett, S., 195

Beethoven, L. V., 330

Behesti, H., 374, 375

Behrens, M., 180

Bekkers, J. M., 480

Beldrum, B., 175

Belfrage, P., 111, 112

Bellido, I., 281

Belluardo, N., 258, 283, 284

Beltz, B., 436, 437

Bemben, M. A., 488, 498

Bendotti, C., 208

Benedict, R., 356

Benfenati, F., 259

Bennett, F. C., 55, 62

Bennett, M. H., 54

Benneyworth, M., 217, 218, 220

Benzer, S., 63

Berg, L., 178

Berger, H., 510

Berger, U. V., 210

Bergeron, R., 211

Bergman, S., 317, 318

Berlin, I., 216

Berlucchi, G., 338

Berne, B., 530

Berns, G., 185

Bernstein, N., 613, 617

Bertler, A., 83

Bevan, L., 604

Bhatt, R., 369, 370

Bickford, M., 538, 546

Bierer, B., 399

Bigland-Ritchie, B., 616, 617

Binder, M. D., 604

Bird, E. D., 200, 206

Birzis, L., 580

Bishop, M., 402

Bishop, P., 511, 512, 513, 524, 526, 527, 528

Bisley, J., 331, 332, 333, 338

Biziere, K., 204, 205

Bizzi, E., 316, 321

Bjelke, B., 262, 263

Björklund, A., 84, 86, 88, 89, 90, 91, 93, 99, 100

Björklund, E., 95, 96, 111

Blackstad, T., 234

Blakely, R., 210

Blaney, J., 495

Blaney, L., 495

Blankenship, S., 498

Blasis, D., 133, 135

Bliss, T. V., 498

Blitz, A., 334

Bloedel, J. R., 608, 613

Blomgren, J., 490

Bloom, F., 83, 198, 199, 236, 470, 471

Bloomfield, S., 538

Boatman, S., 356

Boch, R., 333

Bohlen, C., 54, 55, 62

Bolam, P., 80, 522

Bolme, P., 251

Borroto-Escuela, D., 260, 267, 272, 273, 275, 277, 278, 281, 282, 283, 284, 285, 286, 287, 290, 292, 295, 296, 297, 299

Bors, E., 588–589

Botterman, B. R., 604

Bourassa, J., 551

Bouvier, M., 271

Bowers, C., 167

Bowery, N., 478

Bracha, V., 608

Bredt, D., 487, 488

Brewster, K., 388

Brichta, A., 609

Bristol, A., 133, 141

Broad, E., 416

Broca, P., 392

Brock, L., 617

Brodie, B. B., 254

Brodin, E., 265

Brooks, D., 102

Brosius-Lutz, A., 43

Brouchon, M., 325

Brown, B., 416

Brown, T. G., 617

Brownstone, R. M., 594, 610

Bruce, C., 321, 322, 324, 328, 330, 341

Brundin, P., 98, 101, 103, 108, 114

Bruno, V., 172

Bryan, J., 312

Bryant, S., 142

Buchan, A., 184

Bucher, D., 439, 444, 448

Buchholtz, F., 440

Buchholz, D., 376

Buck, L., 364

Buisson, A., 180

Bujalka, H., 46

Bullock, T., 581, 602

Bunge, M., 361

Bunge, S. A., 138

Bunnemann, B., 262

Burger, M., 357, 358

Burke, D., 601, 610

Burke, R. E., 606, 613

Bush, G. H. W., 318

Bush, G. W., 413–414

Bushnell, C., 319

Bustad, Leo, 593–594

Butcher, L. L., 244

Butera, R. J., 442

Butler, N. M., 306

Bybka, S., 491

Byrne, J., 127, 130

Cabiale, D., 277

Cahoy, J., 46, 48, 61

Calabrese, R., 427, 434, 437, 444, 448

Callan, N., 496

Callister, R. J., 594, 605, 619

Calne, D., 246

Cameron, W. E., 604

Campbell, K. B., 604

Campochiaro, P., 205

Canlis, J. P., 496

Canzoniero, L., 179

Caplan, J. S., 445

Carew, A., 125

Carew, M. B., 125

Carew, T. J., 126, 128, 129, 130, 133, 134, 135, 136, 137, 138, 140, 143, 144, 145, 151

Carlsson, A., 84, 233, 234, 235, 236, 237, 238, 244, 248

Carlsson, J., 297

Carp, J. S., 610

Carpenter, D., 313

Carpenter, M., 115

Carroll, B., 539

Carter, R. E., 210

Casagrande, V., 542–544

Casey, R., 576

Castellucci, V., 127, 129

Castillo, D., 480

Castillo, P., 497

Caviness, V., 358

Cayouette, M, 62

Celani, M., 258

Chadi, G., 258

Chambers, B., 525

Chance, B., 357, 493

Chance, B., Jr., 493

Changeux, J. P., 263

Chaucer, G., 309

Chelazzi, L., 338

Chen, D. Y., 150, 265

Chen, J., 365

Chen, L., 486, 497

Cheng, T. W., 44

Cheshire, F. C., 606

Chiang Kai-shek, 162

Chiappa, K., 169

Choi, A., 187

Choi, E., 187

Choi, F., 162, 163, 164

Choi, H., 186

Choi, J., 187

Christie, A. E., 438

Christine, C., 174

Christopherson, K., 50, 62

Chun, L., 15, 16, 17, 19, 20, 24

Chung, W. S., 52, 58, 62

Churchill, W., 232

Ciaramitaro, V. M., 540

Cicerone, R., 142

Cidlowski, J. A., 180

Cintra, A., 268

Ciruela, F., 272

Clarac, F., 610

Clark, W. L., 94

Clarke, L., 52, 53, 59, 62

Clegg, D., 376

Cleland, B., 526, 528

Clinton, B., 107, 412

Clinton, H., 412

Coates, S., 31

Coates, V., 31

Coffey, P., 376

Cohen, D., 530, 531, 532

Cohen, S., 137

Cohen, A., 439

Cohen, A., 605

Colby, C., 325

Cole, A. E., 478

Collingridge, G., 175

Collings, W. D., 572, 577, 605

Colton, H., 178

Comb, M., 398, 399

Connors, B., 170, 548

Conte, S., 410–411

Cook, D., 133, 134, 135

Cooke, R., 195, 212

Coombs, J., 617

Corcoran, S., 362

Corey, D., 15, 16, 17, 19, 20, 21, 22, 23, 26, 27, 33, 35, 63, 384

Corrodi, H., 236, 237, 246

Corsi, P., 208

Costa, E., 198, 236, 243, 248, 254

Cotman, C., 175

Cotzias, G., 239

Cousteau, J., 461

Covic, E., 538, 551

Cox, L., 538

Coyle, A., 197

Coyle, D., 197

Coyle, J. T., 98, 194, 197, 198, 199, 200, 201, 203, 204, 205, 206, 207, 208, 209, 210, 213, 219, 251

Coyle, P., 197

Craig, B., 608

Crawley, J. N., 253

Creswell, G., 321

Crick, F., 309, 546

Crist, C., 321

Cross, A., 178

Crow, T. J., 126, 238

Cuenod, M., 113, 175

Culver, P., 310

Cummings, B., 336

Curtis, D. R., 206, 617

Cusanovich, M. A., 609

Dahlström, A., 82, 84, 87, 233, 234, 235, 236

Daly, J., 243

Damore, J., 68

Daneman, R., 55, 61

Dantzler, W. H., 597, 606

Darnell, B., 376

Darwin, C., 4

Das, A., 336

Das, G., 94

Dasgupta, S., 270, 279

Daugherty, D., 579

David, S., 24

Davies, J., 175

Davies, P., 206

Davis, B., 208

Davis, K., 208

Davis, J., 185

Davis, J, 4

Dean, J., 472

DeAngelis, C., 215, 216

Dekin, M. S., 436

De Lange, T., 365, 372

del Arco, A., 266

Delong, M., 311, 313

DeLong, M., 185, 207

Demediuk, P., 181

DePasquale, R., 538, 551

Descarries, L., 263, 264

Deschênes, M., 551

Desimone, B., 336

Desimone, R., 409

Deubel, H., 331

Dewhurst, S. A., 430

Diamond, I., 519, 530

Diaz-Alonso, J., 483, 498

Diaz-Cabiale, Z., 271, 281, 282, 284

Dichter, M., 169, 170, 317

Dickinson, P., 439

Didkovsky, N., 370

Diemer, N., 173

Dietz, G, 370

Dillard, R., 356

Dingledine, R., 182, 185

Dodd, J., 359, 361, 364

Dominick, P., 318

Donnelly, R. P., 603

Doty, B., 466

Drachman, D. A., 206

Dreher, B., 526, 528

Drudge, H., 355

Du, C., 179

Dubin, M., 526, 528

Du Bois, W. E. B., 425

Duchateau, J., 610

Dudai, Y., 133, 136, 137

Duffy, P., 172

Dugan, L., 172, 173, 178

Dugas, J., 40, 46, 62

Duhamel, J. R., 325, 326, 327

Dukakis, M., 320

Dunaway, J., 575

Dunn, E., 94

Dunn, J. G., 356, 358

Dunnett, S., 80, 95, 96, 97, 99, 100

Dutar, P., 478, 497

Dylan, B., 196

Eatock, R. A., 510, 553

Ebbeson, S., 239, 530

Ebbinghaus, H., 143

Eccles, J. C., 466, 467, 469, 471–474, 475, 526, 586, 594–595, 599, 600, 617

Edelman, J., 335

Edgerton, V. R., 180, 602, 613

Edholm, O., 584

Edmondson, J. C., 360, 361, 362, 363

Edwards, S., 530

Egeland, J. A., 386

Egertová, M., 486

Ehinger, B., 84

Eichenbaum, H., 217

Eichler, H. G., 187

Eide, E., 600

Eideleberg, E., 597

Eisen, J., 435, 436

Eisenberg, L., 195, 212, 214

Eldred, E., 581, 585, 586–587, 588, 603

Elion, G., 308, 309

Elkes, J., 199

Elphick, M. R., 486

Emery, B., 46, 48, 62

Emptage, N., 133, 135

Enemar, A., 83

Eneroth, P., 250, 256, 257, 258

Englund, R., 263

Enna, S., 201

Enoka, R. M., 607

Enroth-Cugell, C., 528

Epstein, I., 439, 440

Eränkö, O., 240

Eriksdotter-Jonhagen, M., 110

Erisir, A., 538, 546

Ernst, A. M., 237

Eroglu, C., 50, 62

Espinosa, K., 39

Esselmann, S., 498

Essen, D. V., 165

Essenfeld, B., 425

Eugster, C. H., 252

Euler, G., von, 235, 254

Evarts, E., 310, 311, 312, 313, 320, 345

Everitt, B., 243, 244

Evinger, C., 532

Fagg, G. E., 209

Fahrangrazi, S., 180

Fairchild, M. D., 606

Falck, B., 80, 82, 83, 84, 85, 88, 89, 90, 97, 233

Falkner, A., 343

Fang, Y., 374

Fanselow, E. E., 547

Farb, D., 168, 184

Fauci, T., 410

Faulkner, W., 426

Faust, D., 69, 416

Faust, P., 366

Feenery, M., 617

Feltz, A., 433

Ferkany, J. W., 205

Ferraro, L., 274, 277

Ferre, S., 270, 271, 275

Ferrera, V., 336

Fetz, E. E., 607

Feurig, J., 575

Feynman, R., 523

Filip, M., 273, 274, 298

Fior, D. R., 279, 280

Fischbach, G., 166, 167, 168, 182, 358, 384, 401, 404, 409, 410

Fischbach, S., 141

Fischer, B., 333

Fischer, T., 133, 135, 136

Fischer, W., 109

Fishell, G., 362, 363, 366

Fisher, C. M., 16, 397

Fisher, S., 133

Fishman, R, 362, 363

Fitzgerald, K., 133

Fitzgibbon, E., 326, 327, 335

Flamm, R. E., 439

Fleming, A., 518

Flexner, L., 525, 526

Florey, H., 518

Fonnum, F., 200

Foo, L., 48, 49, 61

Forbes, A., 617

Forssberg, H., 608

Foster, A. C., 209

Frackowiak, R., 102

Franco, R., 271, 275, 276

Frank, E., 167

Frank, J., 195

Frankowska, M., 273

Fraser, M., 362

Fraser, S., 362

Fredholdm, B., 249, 270, 276

Fredholm, B. B., 275

Fredricsson, B., 233

Freedman, D., 216

Freeman, B., 355

Freeman, W., III, 580

Freeman, W. J., II, 580, 603

Fregosi, R. F., 609

Freiwald, W., 376

French, J., 589, 590

Frerking, M., 497

Freud, S., 195

Fricker, R. A., 115

Friedland, R. P., 207

Friedlander, M., 519, 531, 538, 542, 545

Friedman, J., 376

Friedman, T., 114

Frisch, K. V., 139

Fryer, B., 374

Fu, M. M., 62

Fuchs, A., 322

Fuchs, E., 365, 372

Fuglevand, A. J., 609

Fukuda, Y., 528

Fulton, C., 426

Funkenstein, H., 311

Furley, A., 364

Furshpan, E., 310, 391

Fuxe, K., 82, 84, 87, 234, 238, 243, 245, 246, 249, 251, 253, 255, 259, 264, 267, 270, 271, 272, 274, 276, 280, 282, 283, 287, 288, 289, 292, 295, 299

Gage, M. L., 97

Gage, R., 95, 96, 97, 100, 108, 109, 114, 180, 182

Galison, P., 386

Gandevia, S. C., 609, 616

Ganguli, S, 333

Gantchev, G. N., 609

Ganten, D., 262, 280

Gantt, H., 195

Gao, W. Q., 362, 363, 365

Garattini, S., 243

Garland, S. J., 605

Garnett, E. S., 102

Garriga, P., 282

Gasser, U., 362, 364

Gattass, R., 325

Gauthier, G., 241

Gearhart, J., 208

Gee, A., 338, 339

Gehring, W., 357

Gelfand, I., 613

Gelles, J., 449

George, R., 605

Gerilovsky, L. V., 609

Gerlach, J. G., 603

Gerlach, R. L., 603

Gershenfeld, H., 430, 433

Geschwind, N., 168, 176, 392, 393

Getting, P., 436, 437

Gibbs, T., 167

Gibson, A. R., 608

Gifford, R., 172, 174

Gilbert, C, 336, 359, 376

Gilbert, R., 375

Gilfoyle, N., 356

Giller, E., Jr., 430

Gilliam, E. E., 605

Gimenez-Llort, L., 275

Gines, S., 275

Giulini, C. M., 310

Gladwell, M., 68

Glass, P., 330

Gleeson, J., 376

Glenn, J., 355

Glowinsky, J., 236

Gluecksohn-Waelsch, S., 356

Goaillard, J. M., 442, 444, 448

Godwin, D., 538

Goff, D., 217

Goldberg, D. (née Baron), 309, 310, 311, 312, 315, 316, 317, 318, 322, 329, 335, 336, 337

Goldberg, F., 309, 310

Goldberg, G, 309, 310

Goldberg, M. E., 313, 314, 321, 325, 326, 327, 328, 332, 333

Goldberg, M. P., 171, 173, 178, 180

Goldberg, J., 39, 42, 44, 45, 61

Goldberg, J., 316, 323, 330, 336, 337

Goldberg, J., 317, 329, 330

Goldman, M., 442–443

Goldman-Rakic, P., 328

Goldstein, A., 171

Goldstein, M., 239, 240, 245, 246, 254, 263

Golembiowska, K., 274

Golowasch, J., 439–440, 443

Gomperts, S., 497

Goode, B., 449

Goodman, C., 6, 360

Goodman, H., 398, 399

Goodwin, F., 401, 402

Goodwin, T., 331

Goold, C., 498

Gordon, D. A., 604

Gordon, M., 356

Gore, A., 412, 413

Gore, B., 597

Gore, T., 412, 413

Gorman, R. B., 605

Goslow, G. E., Jr., 606

Goslow, T., 593

Gottfredson, M., 142

Gottlieb, D., 180

Gottlieb, J., 330, 331, 336, 339

Govek, E., 373, 374, 375

Grabb, M., 180

Grace, A. A., 203

Grafstein, B., 182

Graham, B. A., 610

Granger, A., 498

Granit, R., 586, 613

Grant, S., 364

Grashow, R., 442, 444

Gray, E. G., 196

Gray, J., 498

Graybiel, A., 241, 242

Greenberg, M., 63

Greene, L., 359, 360

Greene, R., 217

Green, J., 32

Green, J., 581

Gregory, B., 361

Griffith, L., 449

Grillner, S., 175, 313, 346, 606, 617, 618

Gross, C., 325

Grossman, A., 426

Grove, E., 553

Gruenbaum, L., 133, 137, 138

Gruener, R., 597, 606

Grzanna, R., 198, 202

Guan, S., 328

Guido, W., 538, 546

Guillery, R. W., 113, 360, 370, 505, 510, 518, 519, 521, 522, 530, 534–536, 537, 541, 543, 544, 546, 547, 548, 551, 552, 553

Guitton, D., 334

Günlük, A., 532

Gurfinkel, V. S., 609, 613, 619

Gusella, J., 398

Gustafsson, J. Å., 255

Gutierrez, G. J., 443

Gutmann, D., 178

Gutmann, L., 588

Guttenplan, K., 57, 61

Gwag, B. J., 179, 187

Gwik, V. A., 608

Gydikov, A., 608

Gyllensten, L., 235

Haber, J., 449

Hackett, J., 530

Hagbarth, K. E., 601

Hagelberger, J., 355

Hagman, B., 251, 256

Haith, M., 164

Hall, J., 449

Hall, V., 578, 580, 581, 590

Hall, Z, 402, 403, 404, 405, 408, 409, 410

Hallett, M., 169, 311, 313, 324

Halstead, C., 210, 211

Hamm, T. M., 605

Hamos, J., 538, 545, 546

Hand, P., 525

Hanes, D. P., 339

Hans-Arne, H., 265

Hanson, M. G., 39

Hanzel, M., 375

Haraldsson, B., 98

Hardwick, E., 356

Härfstrand, A., 255, 256, 280

Harriman, P., 354

Harris, B., 359

Harris, B. P., 50, 62

Harris, J., 214, 216

Harris-Warrick, R., 439, 448

Hart, I., 24

Hartley, D., 172, 173

Hasan, Z., 607, 616

Hasegawa, R., 334, 335

Hashimoto, K., 486

Hasselmo, M., 217

Hatsopoulos, N., 510, 534

Hatten, B, 354

Hatten, M. L., 354

Hatten, J., 354

Hatten, J., 354, 355

Hatten, J., 360, 362

Hawkins, B., 130

Hayashi, Y., 483

Hayes, A., 336

Hayhoe, M., 342

Hays, A., 321

Hayward, J. N., 606

He, J., 608

Heckers, S., 216, 217

Hedge, G., 597

Hedlund, P., 280, 281

Hedstrom, L., 449

Hee, P. C., 186

Hefti, F., 109

Heide, W., 327

Heidinger, V., 180

Heimer, L., 530

Heineman, S., 431

Heinemann, U., 175

Heintz, N., 44, 362, 365, 366, 370, 371, 376, 377

Helmholtz, H. V., 323, 324, 325

Hemingway, A., 578, 579–580, 581, 582, 583, 584, 589, 603

Hemingway, C., 579

Henderson, C., 39

Hening, W., 128

Henneman, E., 607, 617

Henry, D., 198, 199

Henry, G., 526, 527, 528

Hepler, D. J., 207

Herbert, E., 399

Herkenham, M., 262

Herman, R. M., 606, 618

Herring, B. E., 489, 498

Hess, W., 617

Hewett, S., 180

Hildebrand, J. G., 608

Hillarp, N. Å., 82, 90, 233, 235

Hille, B., 484

Hillion, J., 271

Hitchings, G., 308, 309

Hite, N., 321

Hixon, T. J., 607

Hochman, B., 338

Hockfield, S., 134

Hodes, R., 408

Hoffmann, P., 512, 526, 527, 528, 540, 541

Hoffmann, S., 512

Hofstadter, P., 141

Höistad, M., 265, 266

Hoit, J. D., 607

Hökfelt, T., 85, 240

Hole, K., 243

Holmstedt, B., 233

Holtzman, D., 178

Holzman, P. S., 411

Homma, S., 586, 593, 606

Hong, S., 58, 60

Hooper, S., 435, 437–438

Hopkins, N., 66, 68, 69

Horellou, P., 114

Horn, M., 498

Horn, Z., 375

Hornby, T. G., 604

Hornykiewicz, O., 83, 84, 236

Horvath, T., 266

Horvitz, B., 63

Horvitz, R., 172

Horwitz, R., 357

Houk, J. C., 607

Houseman, D., 398

Howe, M., 61

Howell, G. R., 58

Hsia, A., 497

Hsiao, C. F., 538

Hsu, C., 178

Hu, H., 547

Huaiyu, M. I., 61

Hubbard, M., 609

Hubel, D., 165, 310, 311, 319, 320, 322, 345, 391, 393, 514, 526, 541

Huberman, A., 44, 45, 62, 63

Hudson, K, 356

Hudspeth, J., 165

Huganir, R., 370, 483

Hughes, A., 528

Huguenard, J., 170

Hull, C., 376

Hultborn, H., 600, 610

Humphrey, A., 538, 545

Humphries, C., 68

Hunter, K., 369

Hurd, Y., 271

El-Husseini, A. E., 487, 488

Hwang, K. S., 186

Hyman, B., 385, 415

Hyman, S. E., 385, 390, 396, 400, 412, 413, 417

Hynes, M., 364, 376

Inaba, N., 329

Incontro, S., 498

Ingvar, D., 101

Innocenti, G., 335

Insel, Prof., 285

Ipata, A., 338, 339, 343, 344

Isaac, J. T., 482, 488

Isaacson, J. S., 478, 484, 485, 487, 497

Isaacson, W., 496

Isacson, O., 96, 98

Isenberg, P., 396

Ishikawa, K., 586, 593, 594, 604

Ito, M., 321, 609, 619

Iversen, L., 175, 183, 200, 206

Iversen, S., 80, 96

Jackson, A., 498

Jacob, F., 309

Jaenish, R., 357

Jahnsen, H., 546

Jahr, C., 476, 477, 496, 497

James, W., 312, 331

Jan, L., 368

Jane, D. E., 176

Jane, J., 530

Jankowska, E., 599, 600, 603

Janson, A. M., 258

Jansson, A., 247, 263, 264, 265

Jareb, S, 376

Jarl, U., 98

Jefferson, T., 514

Jenden, D., 589

Jenike, M., 396

Jenkins, F., 165

Jessell, T., 359, 361, 364, 365, 367, 440

Johansen, T., 110

Johansson, L., 232

Johansson, N., 232

John, K., 375

Johns, M., 184

Johns, S., 58

Johnson, C., 355

Johnson, E. C., 219

Johnson, G., 39

Johnson, L., 318

Johnson, L. B., 186

Johnson, P. C., 597, 606

Johnston, M., 202, 203, 206, 207

Jones, J. G., 610

Jones, T., 182

Jonides, J., 331

Jonsson, G., 82, 243

Jouvet, M., 244

Joyce, J., 425

Joyner, A., 367

Joyner, M. J., 604

Julius, D., 481

Kaas, J., 530

Kado, R. T., 589

Kaitz, A., 317

Kalia, M., 256

Kam, K., 497

Kamikawa, K., 605

Kandel, E., 127, 128, 129, 130, 131, 132, 147, 313, 336, 361, 363, 364, 440, 477

Kano, M., 486, 487

Kaplan, M., 45, 61

Karachi, C., 341

Karlsen, R. L., 200

Karst, G. M., 609

Karten, H., 345, 531, 532

Kasthuri, B., 534

Katz, B., 164, 480

Katzman, B., 89, 90, 97

Kauer, J. A., 480, 497

Kaushansky, K., 185, 186

Kawai, N., 442

Kawamura, H., 583–584

Kawamura, Y., 583–584, 606

Kawano, K., 329

Keahi, D., 374

Keen, W. W., 580

Kehoe, J., 430, 432

Kehr, J., 265

Keller, E., 335

Kennedy, D., 621

Kennedy, M., 437

Kenyon, C., 372, 373

Kepler, T., 440

Kern, D., 449

Kernell, D., 613

Kerr, C., 592

Kettenmann, H., 113, 346

Kety, S., 195, 219, 397

Keys, B., 319, 322

Khacho, P., 211

Kiani, R., 329

Kidokoru, Y., 431

Kieć-Kononowicz, K., 298

Kiianmaa, K., 243

Kim, D. J., 186

Kim, J. H., 370, 372

Kim, L., 338

Kim, T. S., 186

Kim, Y., 186

King, A., 522

King, M. L., 69

Kingston, R., 399

Kinsey, F., 133

Kirik, D., 115

Kirkeby, A., 116

Kirov, G., 219

Kirschner, M., 357

Kirstein, R., 183

Kitai, S. T., 545, 546

Kitayama, I., 259, 260

Klausner, R., 410

Klerman, G. L., 393

Kleschevnikov, A. M., 208

Knight, E., 617

Knowland, D., 56

Kocabas, A., 376

Kodaka, Y., 319

Koehler, W., 605

Koh, J. Y., 172, 173, 174, 178, 179

Kohler, C., 206

Kolin, A., 589

Kopec, A., 141, 146, 148, 149

Kopell, N., 439

Kopin, I., 198

Kordower, J., 108

Korn, D., 177

Kornberg, A., 357

Koshland, G. F., 609

Kossev, A. R., 608

Kostov, K. G., 608

Kowler, E., 331

Kratz, K., 538

Krauzlis, R., 314

Kravitz, E., 310, 391, 430, 436

Kreek, M. J., 365, 372

Kreitzer, A. C., 485

Kriegstein, A., 132, 169, 170

Krishna, S., 343

Kroin, J. S., 605

Krug, K., 522

Krystal, J. H., 211, 216

Kucukdereli, H., 50

Kuffler, S., 63, 166, 310, 427

Kuhar, M., 200

Kuhn, T., 220, 407, 408

Kukushkin, N., 148, 150, 151

Kull, B., 270

Kullman, D. M., 481, 497

Kuno, M., 599

Kupfer, C., 320

Kupfermann, I., 127, 129

Kusunoki, M., 326, 330

Lacan, J., 195

Laidlaw, D. H., 605

Lam, Y. W., 539

Lambert, E. F., 569

Lancaster, B., 497

Lance, J., 601

Lander, E., 411

Landis, S., 359

Lang, F., 435

Langston, B., 105, 106

Lansing, R. W., 607

Laouris, Y. C., 605

Lario, A., 498

Larriva-Sahd, J., 288, 289

Laub, D., 32

Lauder, J. M., 199

Leavitt, J., 206

Leder, P., 398

Le Douarin, N., 358, 368

Lee, B. G., 186

Lee, C., 538, 550, 551

Lee, J., 179

Lee, K., 367

Lee, M., 521

Leenders, K., 102

Lees, G., 181

Lee-Teng, E., 523

Lefkowitz, R., 272

Lehmkuhle, S., 538, 544, 545

Leigh, J., 329

LeMasson, G., 441

Lenin, V., 308

Lennard, P., 185

Leshner, A., 402, 405, 408, 410

Lesica, N. A., 547

Lester, H., 368

Levesque, M., 551

Levey, A, 185

Levick, B., 526, 528

Levi-Montalcini, R., 40, 137

Levine, A., 357

Levine, R. B., 608

Levinson, A., 357

Levy, J., 498

Lewis, E., 184–185

Lewis, J. L., 607

Lewis, P. R., 206

Li, J., 108

Li, L., 438

Li, M., 116

Li, T., 62

Li, X. M., 276, 277, 278, 279

Liao, D., 482

Libet, B., 588, 610

Lichtman, J. W., 390

Lidbrink, P., 244

Liddelow, S., 56, 57, 62, 218

Lie, Y., 373

Lieberman, D., 246

Liebl, D., 218

Liem, R., 359, 360

Lifton, R., 377

Lightstone, A. D., 324

Lin, C. S., 538

Lindsley, D., 581

Lindvall, O., 84, 85, 86, 87, 100, 101, 102, 103, 104, 106, 112

Lingle, C., 434

Lipton, S., 169

Lisman, J., 217

Lissin, D. V., 488

Little, Mrs., 354

Liu, J., 525

Liu, X. L., 371

Liu, Z., 441

Llano, D., 538, 549

Lledo, P., 270, 497

Llinás, R., 546

Lobner, D., 180

Locke, S., 169

Lodge, D., 175

Löfström, A., 250

Lohse, T., 622

Lomber, S., 342

Lomo, T., 498

London, E., 204, 207, 210

London, I., 165

Loop, M., 538

Loren, I., 86

Lorenz, K., 139, 388

Love, D., 60

Lovero, K., 497

Lovett, S., 449

Lowry, O. H., 608

Lu, W., 483, 498

Lumsden, A., 368

Lundberg, A., 595, 599, 600, 603, 617

Lundberg, C., 114

Luria, S., 10

Luscher, C., 482, 497

Luthi-Carter, R., 210

Lynch, G., 175, 480

Lynch, J. C., 319

Lynhagen, N., 97

Lyons, D., 47

Mackie, K., 484

MacKinnon, R., 376

Mackinzie, H., 498

MacLean, J., 534, 553

MacNeil, F., 216, 220

Macquarie, L., 562

Madara, J., 533, 534

Madison, D., 478, 481, 485, 497

Magoun, H., 236, 581, 587

Mahoney, D., 336

Mahoney, H., 336

Maimon, G., 376

Majid, A., 180

Malenka, R., 482, 483, 487, 488, 497

Malinka, Prof., 286

Malinow, R., 480, 483

Mallet, J., 114, 181

Malmfors, T., 235, 242

Maloney, A. J., 206

Mamet, D., 330

Manabe, T., 482, 497

Mandel, R., 115

Mandemakers, W., 62

Mangel, S., 538

Manger, P., 293, 294

Mano, N., 313

Manzerra, P., 180

Manzoni, O., 497

Mao Tse-Tung, 162

Marcus, B., 507

Marcus, E., 130, 131, 132, 133, 134

Marder, E., 431, 433, 435, 436, 437, 438, 439, 440, 441, 444, 445, 448

Margoliash, D., 510, 533

Marinesco, S., 141, 144

Marin-Valencia, I., 376

Marois, R., 133, 134

Marowsky, A., 287

Marsden, C., 245

Marsden, D., 98, 102

Marshall, E., 404

Marshall, F., 272

Martin, J., 384, 398, 399

Martin, K., 519, 520

Martinez-Serrano, A., 109

Martini, L., 239

Marty, A., 433

Marx, K., 308, 425

Masland, R., 384

Mason, C, 360, 361, 363, 364, 377

Mason, D., 360

Massion, J., 610

Mattsson, B., 105

Mauelshagen, J., 133, 138, 143

Maugham, W. S., 308

Maunsell, J., 510, 534

Maxfield, F., 360, 361

Maxwell, D. S., 605

Mayberg, H., 185

Mayer, M., 496

Mayeri, E., 127

Maynard, D., 429, 602

Mays, L., 324

Mazziotta, J., 172

McCaman, D., 430

McCarroll, S. A., 390, 417

McCarthy, J., 308

McClurkin, J., 336

McComas, A. J., 609

McConnell, H., 357

McConnell, S., 360

McCormick, D., 170, 548

McDonagh, J. C., 604

McDonald, J., 180

McEwen, B., 256, 376

McGaugh, J., 140, 141, 142

McGeer, P. L., 206

McGonigal, R., 60

McGurdy, B., 495

McHugh, P., 213, 214

McIlwain, H., 197

McKay, R., 109, 172

McKay, S., 133, 137, 138

McLaughlin, D., 147

McLaughlin, S. C., 335

McMahan, J., 165

Megalogenis, G., 562

Meites, J., 239

Meldrum, B., 173

Mellor, J., 497

Meltzer, C., 185, 286, 293

Mendell, L. M., 182, 532, 607

Menuz, K., 497

Menzel, R., 138

Mercer, A., 133, 135

Mesirov, J., 375

Messenger, B., 573–574

Messenger, J. C., 573–574

Mesulam, M., 168–169, 216

Metcalfe, J., 576

Meyer-Franke, A., 38, 39, 46, 61

Mikami, A., 334

Miledi, R., 288

Miles, F., 320, 329

Millen, K., 367

Miller, A. J., 539

Miller, C., 449

Miller, J. P., 435

Miller, K., 333

Miller, R., 175

Millonig, J., 367

Milner, B., 334

Milstein, A., 497

Mirisis, T., 148, 149

Mishkin, M., 336, 408

Miya, K., 218

Miyamoto, M., 209

Mo, C., 539, 549, 550

Mobley, B., 182

Mody, I, 170

Mohl, T., 496

Mohler, C., 316

Mohs, R. C., 208

Molinoff, P., 198

Molliver, M., 201, 202

Molnar, Z., 522

Mommaerts, W., 581

Money, J., 13

Moniz, E., 580

Monnier, A., 602

Monod, J., 309

Montague, L., 181

Monteith, E. W., 563

Monteith, J., 563

Monyer, H., 172

Moon, K., 186

Moore, G. P., 607

Moore, K., 497

Moore, R., 563

Mora, F., 266

Mora, M. P., de la, 247, 248, 286, 287, 288

Morad, M., 174

Morales, D., 368

Morgado, N., 622

Mori, S., 609, 616, 619

Morris, J., 178

Morrison, A., 525

Morrison, J., 202

Moruzzi, G., 236, 599

Moscowitz, M., 169

Mosher, C. G., 606

Mountcastle, V., 310, 313, 319, 321, 324, 341

Movshon, T., 146, 521

Mrak, E., 592, 595

Mudo, G., 258, 283, 284

Mueller, U., 133, 136, 137

Mullen, D., 358

Muller, D., 480

Mulloney, B., 430

Munoz, D. P., 328

Munoz, G., 497

Munro, D., 588

Murphy, D., 622

Murphy, P., 538

Murphy, T., 209

Murray, B., 336

Murthy, A., 344

Nabokov, V., 319

Nacci, P., 181

Narvaez, J., 279, 281, 282, 283, 284

Nauta, W., 165, 239

Nelson, S., 441–442, 449

Nemeroff, C., 185, 277

Nemeth, P. M., 607

Nemeth, W. C., 604

Nestler, E., 400

Newberry, N. R., 477, 478, 497

Newsome, B., 63, 336

Nguyen, N., 617

Nguyen, Q. A., 498

Nichols, N., 336

Nichols, T. R., 607

Nicholson, C., 263, 265

Nicholson, M., 356

Nick, T., 133

Nicoletti, F., 172

Nicoll, A., 490

Nicoll, E., 490

Nicoll, M., 459

Nicoll, R. A., 470, 471, 473, 474, 477, 478, 479, 481, 482, 483, 484, 486, 487

Nicoll, D., 489–490, 492

Nicoll, D., 489, 490

Nicoll, P., 459

Nicoll, P., 490

Niell, A., 509

Niell, C., 509

Nilsson, J., 291

Nilsson, O., 233

Nirenberg, M., 198, 309

Nixon, R., 316, 317, 472

Noebels, J., 359

Nolen, T., 132, 133

Norberg, K. A., 235

Nordstrom, M. A., 605

Norton, T., 542, 543

Noven, S. V., 604

Nung Jan, L., 63

Nung Jan, Y., 63

Nurse, P., 372

Nusbaum, M., 437, 438

Nusbaum, R., 411

Nyberg, F., 256

Obama, B., 416

Oberdorfer, M., 30

Obote, M., 512

O’Connor, W. T., 263, 271

Odagaki, T., 269

Odagaki, Y., 260, 269

Ögren, S. O., 271

Oh, U., 186

Ohmoto, T., 245

Ohno-Shosaku, T., 485

Olds, J., 312

O’Leary, T., 441, 443, 444, 445

Oliet, S., 497

Olney, J., 170, 175, 177, 200

Olschowka, J. A., 202

Olsen, T., 185

Olson, C., 325

Olson, L., 82, 92, 237, 241, 252

Olsson, A., 265

Olton, D., 207

O’Neil, M., 435, 442

Oppenheimer, P., 463

Oppenheimer, R., 463

Oprian, D., 449

Optican, L., 320, 321, 328

Orlovsky, G., 617, 619

Ortuno, T., 547

Ory-Lavollée, L., 210

Osheroff, H., 371

Oster-Granite, M. L., 208

Osterhout, J. A., 44

Otopalik, A. G., 444

Otsuka, M., 430

Ott, K., 585–586, 603

Ott, L. H., 585, 606

Owman, C., 84

Pacheco, A., 346

Pagels, E., 356

Paige, H., 318

Paillard, J., 617

Palfreman, J., 105, 106

Palme, O., 233

Palmer, L., 338

Palmer, L. A., 322

Panicker, S., 497

Parada, L., 180

Parker, A., 522

Parks, M., 514

Parmar, M., 116

Pasca, S., 53

Pasternak, T., 331

Paton, M. C., 360

Patrick, J., 431

Patterson, P, 16

Patton, H., 617

Paupardin-Tritsch, D., 430, 433

Pavlov, I., 195

Payne, W., 354

Peabody, J, 318

Peck, B., 176, 182

Peck, C, 341

Pedley, T., 336

Penas, C., 374

Perez, E. J., 218

Perkel, D., 497

Perl, E., 599

Peroutka, S., 170, 171

Perry, E. K., 206

Pestronk, A., 181

Peters, S., 172, 174

Peterson, B., 329, 334, 335

Peterson, C., 497

Petrides, M., 334

Petrinovich, L., 125

Petrof, I., 538, 550, 551

Pfrieger, F., 49, 50, 51, 61

Phillip, A., 562

Phillips, G., 141, 143, 148

Phillips, M., 335

Phuan, P. W., 60

Piccini, P., 102, 104

Pierce, P. A., 594, 601, 605, 616, 619, 621

Pinker, S., 68

Pinsker, H., 127, 128, 129

Pintsuk, J., 275

Pitler, T. A., 483

Piven, J., 214

Placzek, M., 364

Platt, J. R., 474

Plum, F, 347

Poletti, M., 342

Pollock, J., 30

Polonsky, K., 534

Poo, M. M., 362, 367

Popoli, P., 271, 275

Popper, K., 220, 407, 472, 474

Porter, R. W., 589, 590, 605

Posner, J., 14

Potter, D., 176, 310, 391

Potts, J., 398

Pouget, A., 324

Poulenc, F., 329

Powell, K., 329

Powell, T, 519

Prasad, J., 539

Price, D., 177, 182, 207

Price, W. M., 605

Prince, D., 169, 171, 175

Prinz, A., 440, 442, 443

Prochazka, A., 609

Proske, U., 609

Proust, M., 387

Pu, L., 141, 145, 146

Purcell, A., 133, 137–138, 141, 145

Puttfarcken, P. S., 209

Qian, N, 336

Quaia, C., 328

Quinn, N., 102

Raber, J., 336

Racke, M., 178

Raczkowski, D., 538

Radicheva, N., 609

Raff, M., 18, 19, 23, 24, 25, 26, 27, 33, 35, 63

Rahamimoff, R., 165

Rajasethupathy, P., 365, 372

Rakic, P., 358, 359, 361, 364, 366, 377

Ramcharan, E. J., 547

Ramön y Cajal, S., 18, 94, 145, 465

Rankin, C., 132, 133

Rankin, L. L., 604

Ransom, B., 170

Raposo, G., 298

Rassbach, E., 621

Rassbach, J. See Stuart, J. R.

Rassbach, P., 621

Ratner, S., 356

Rayport, S., 132

Razani, H., 281

Redmond, E., 101

Rees, D., 111

Reeve, C., 183

Reeves, R. H., 208

Regan, R., 172

Regehr, W. G., 485

Rehncrona, S., 103

Reich, S., 330

Reich, T., 411

Reichardt, L., 33, 35, 38, 63

Reichova, I., 532, 548, 549

Reinking, R. M., 593, 598, 599, 600, 601, 605, 616, 621

Reis, D., 238

Reissner, K., 141, 145

Renner, P., 497

Retz, K. C., 205

Reynolds, B., 115

Rhee, D., 539

Rhodes, R., 496

Rice, M., 263, 266

Richardson, E. P., 397

Richmond, B., 317, 335, 336

Richmond, F. J., 607

Richter, C., 195

Riley, T., 330

Rimondini, R., 270

Rinberg, A., 445

Rinzel, J., 442

Rivas, R., 363, 366

Rivera, A., 266, 287

Roark, M. F., 312

Robertis, E., de, 196

Roberts, K., 344

Roberts, P., 252

Robinson, D. A., 314, 321, 322, 326

Robinson, D. L., 317, 318, 319

Robinson, G. A., 605

Robinson, H. P., 442

Robinson, M., 210

Robson, J. G., 528

Roche, K., 488

Rockefeller, D., 365

Roffler-Tarlov, S., 358

Roffman, R. C., 444

Rogawski, M., 175

Rogers, M., 40, 61

Romero-Fernandez, W., 273, 283, 285

Ronthal, M., 169

Roos, P., 256

Rosbash, M., 449, 509

Roscoe, D. D., 604

Rosell, S., 235

Rosenbaum, T., 509

Rosenberg, P., 169

Rosenblueth, A., 602

Rosengren, E., 83, 84

Rosenquist, A., 322, 335

Rosenthal, A., 59, 60, 109

Ross, E., 399

Ross, R., 214

Rosténe, W., 254

Roth, M., 206

Rothman, S., 177, 178

Rouach, N., 497

Roussel, M., 371, 372, 374

Rowe, M. H., 528

Rowland, B., 185

Rowland, F. S., 142

Rubel, L., 530

Rudenberg, H., 572

Rudomin, P., 602

Ruffner, T., 336

Rushton, W. A. H., 474

Ruta, V., 365, 372, 376

Rymer, W. Z., 607

Sadowsky, C., 622

Sadowsky, M., 622

Sager, R., 356

Saggese, M., 182

Sah, P., 497

Sahlholm, K., 291, 292

Sainz, C., 106

Sakata, H., 326

Salerio, E., 372

Salim, H., 270

Salin, P., 497

Salmoiraghi, G., 467, 469

Salzman, D., 336

Samskog, J., 265

Samuels, M., 169

Sandberg, S., 69

Sanderson, K., 526, 527, 540

Sanes, J. R., 165, 359, 362, 390

Sanfilippo, F., 184, 185

Sansoucy, G., 197, 220

Santello, M., 608

Sartre, J. P., 195

Sasaki, S. I., 607

Satterlie, R. A., 607

Sawa, A., 370

Sawyer, T., 250, 581

Scandella, C., 357

Scanziani, M., 474, 497

Schachner, M., 358

Schaefer, A. T., 610

Schaefer, B., 181

Schafer, D. P., 52

Schaffhausen, J., 141, 145

Schall, J. D., 339

Scheibel, A., 236, 581

Schell, M. J., 217

Schermer, M., 505

Schiller, P., 314

Schlimgen, J., 617

Schlossberger, H. G., 88

Schmidt, R. H., 98

Schneider, S., 372

Schnell, E., 487, 488, 497

Scholze, A., 61

Schubert, D., 430, 431

Schuetze, S., 167

Schulz, D. J., 444

Schwab, M., 43, 109, 180

Schwarcz, R., 98, 175, 200, 201, 203, 205, 216, 251–252

Schwartz, A. B., 608

Schwartz, J. H., 127, 129, 137, 361, 430, 440

Schwartzkroin, P. A., 476

Scolnick, E., 417

Searle, J., 472

Sechenov, I., 617

Seed, B., 399

Segraves, M., 335

Segundo, J., 598

Seiger, Å., 92, 241

Sejnowski, T. J., 324

Selkoe, D., 169, 358

Selverston, A., 428, 429, 432, 435

Semple, M., 343

Sendhilnathan, N., 344

Sengupta, P., 449

Sensi, S., 179

Severin, F., 617

Sexton, J., 147

Shalaby, S., 374

Shalala, D., 410

Sharma, S., 141, 143, 144, 145

Sharp, A., 442

Shatz, C., 27, 165, 359, 360, 377

Shelanski, M., 358, 359, 360, 361

Sheline, Y., 168, 169, 177, 180

Shen, S., 41, 42

Sheng, N., 498

Sherff, C., 133, 136, 141, 144, 145

Sherman, E., 513, 514, 516, 517, 520

Sherman, I., 505

Sherman, L., 505

Sherman, M., 510–513, 514, 516, 517, 520, 521, 522, 529, 531, 553

Sherman, P., 505

Sherman, S., 506

Sherman, S. M., 510, 523, 527, 528, 535, 536, 541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551

Sherman, W. T., 505

Sherman, B., 506, 520

Sherman, B., 513, 514, 516, 517, 520

Sherman, J., 505–506, 508

Sherman, J., 505, 506

Sherrington, C., 324, 594, 595, 617

Shi, J., 61

Shi, Y., 483, 489

Shik, M., 617, 619

Shipman, S. L., 488, 497

Shmidt, D., 497

Shobe, J., 141, 143

Shumilov, K., 287

Shute, C. C., 206

Sibley, B., 597

Sick, M. J., 124, 131, 140, 141, 147

Sidman, R., 358, 359, 367, 368, 377

Siegelbaum, S., 361

Simon, R., 175

Simonian, N., 209

Simons, J., 185

Simons, M., 185, 298

Singer, W., 113

Singh, S., 496

Sistrom, W., 309

Sjöberg, N., 84

Sjöqvist, F., 233

Sjostrand, F., 581, 583

Skagerberg, G., 86

Skinner, B. F., 309

Skrede, K. K., 476

Slevin, J. T., 203

Sloan, S., 49, 53, 54, 61

Slusher, B. S., 210

Small, D., 563

Small, J., 563, 567, 575

Smith, D., 111

Smith, J. L., 607

Smogorzewska, A., 365, 374, 376

Snider, J., 180

Snow, C. P., 310

Snyder, S., 63, 167, 196, 197, 199, 201, 213, 247

Sofroniew, M., 56

Sognnaes, R., 583

Solecki, D., 371, 373

Solis, J., 497

Sommer, M., 328

Somogyi, P., 80, 522

Soofi, W., 445

Sowden, J., 374

Sparks, D., 324, 328

Speier, J., 69

Spencer, A., 127, 129

Spencer, W. A., 476

Sperry, R., 509, 523–524, 525

Spielmann, J. M., 604

Spokes, E. G., 203

Sprague, J., 510, 513, 519, 524, 525, 529, 530, 539, 540, 542

Squire, L., 194

Stanford, L., 531, 538, 545

Stanley, G. B., 547

Stanley, T., 417

Stanley, V., 417

Stanton, G., 319, 322

Stark, L., 133

Stauffer, E. K., 600, 604

Steenrod, S., 335, 342

Stein, D., 185

Stein, P. S. G., 607, 618

Stein, R. B., 607

Stein, V., 497

Steinbusch, H. W., 241, 263, 264

Steinhardt, R., 356

Stellar, E., 525

Stelmach, G. E., 608

Stelzner, D., 525, 544

Stenevi, U., 90, 92, 93, 98, 99, 116

Stephan, A., 57, 58, 62

Stephens, J. A., 600, 604

Steriade, M., 547

Sterling, P., 313, 525

Sternbach, L, 167

Steullet, P., 218, 219

Stevens, B., 52, 58, 62

Stevens, C., 35, 39, 63, 480, 481

Stewart, O., 530

Stitt, T., 362

St. John, P. A., 608

Stone, J., 512, 526, 527, 528, 540, 541

Stone, M., 512

Stopfer, M., 132, 133

Stough, S., 141

Strasser, U., 180

Strausfeld, N. J., 608

Strick, P., 345, 525

Stridsberg, G, 98

Strömberg, I., 263, 271, 276

Stroud, B., 495

Strumwasser, F., 598

Stryker, M., 314

Stuart, C., 563

Stuart, D., 622

Stuart, D. G., 580, 584, 587, 588, 594, 603, 616

Stuart, G. K., 562, 563, 564

Stuart, I., 563, 564–565, 567, 568–569

Stuart, J. R. (née Rassbach), 574, 579, 583, 585, 590, 591, 592, 595, 596, 621–622

Stuart, K., 622

Stuart, M., 621–622

Stuart, M. M., 563, 564, 565

Sugiura, K., 609

Sugrue, L. P., 343

Suh, S., 179

Summers, L., 11, 66, 67, 68, 415–416

Sundler, F., 84

Sun, L., 25, 62

Sun, L., 342

Sur, M., 538, 542, 545

Sutherland, J., 330

Sutton, M., 133, 137, 141, 142, 143, 144, 145

Svendgaard, N. A., 91

Swadlow, H. A., 547

Swanson, R., 172

Swedo, S., 409

Sweeney, J. E., 208, 209

Sweet, H., 358

Swensen, A. M., 440

Sykova, E., 263

Szent-Gyorgyi, A., 426, 427

Szostack, J., 399

Tagliapietra, L., 496

Takahashi, J., 411

Talalay, P., 199

Talamo, B., 164, 166

Tamamaki, N., 538, 551

Tamayo, P., 375

Tan, U., 607

Tang, L. S., 445

Tanganelli, S., 254, 255, 274, 276, 277, 278

Tannen, D., 364

Tansey, E. M., 610

Tao, W., 498

Tarakanov, A., 289, 290, 299

Tasaki, I., 313

Taub, E., 346

Taylor, A., 607

Taylor, A. L., 448

Taylor, C., 577, 578, 582

Taylor, T., 600

Tecoma, E, 171, 173

Teichberg, V., 175

Tessier-Lavigne, M., 63, 364, 375, 377

Teuber, H. L., 10, 312, 316

Teyler, T. J., 479

Thach, T., 311

Thal, L., 109

Theyel, B., 538, 549

Thoenen, H., 87, 109, 177

Thomas, C. K., 609

Thompson, J., 116

Thompson, K. G., 319, 336

Thompson, R., 486

Thompson, S., 170

Thomson, I., 521

Tilghman, S., 367

Tinbergen, N., 139, 388

Tinner, B., 264

Tobin, A. E., 172, 444

Tolbert, L. P., 609

Tomoda, T., 369, 370, 371

Tong, G., 497

Torrey, E. F., 406

Torvinen, M., 270, 275

Tosteson, D., 214

Tower, K., 617

Trailer, R., 164

Tranzer, J., 87

Trayanova, N. A., 608

Trouillas, P., 263

Tsai, G., 210, 211, 216

Tschirgi, R., 581, 592

Tsetlin, M., 613

Tsien, R., 373

Tsien, R. W., 147, 480, 481

Tune, L. E., 213

Turrigiano, G., 441–442, 449

Tusa, R., 322

Tuszynski, M., 109

Twain, M., 177

Tyler, H. R., 168

Tyler, T., 477

Tymianski, M., 187

Tzingounis, A., 497

Uhlrich, D., 538

Ullian, E., 41, 49, 50, 61

Umeno, M., 327, 328

Ungerleider, L., 336

Ungerstedt, U., 82, 87, 97, 235, 237, 238, 243, 244, 246, 249, 270, 271, 276

Uvnäs, B., 235

Uvnäs-Moberg, K., 284

Van Aelst, L., 373, 375

Vanderhaeghen, J. J., 253, 271

van der Kooy, D., 362

Vane, J., 237

VanEssen, D., 146

Van Horn, S., 546

Varela, C., 538

Vargas, M., 42, 43, 61

Varmus, H., 402, 403, 404, 405, 408, 410, 413

Varon, S., 109

Vaughan, J. W., 538

Vedantam, S., 66

Viaene, A., 538, 550, 551

Vincent, Prof., 270

Vogt, K., 497

Volhard, J. N., 357, 367

Von Krosigk, M., 548

Voris, H. C., 194

Vosshall, L., 365, 372

Vu, E. T., 608

Vukojicic, A., 58, 60

Wagner, A., 131

Wahlberg, L., 110, 115

Wait, J. V., 606

Walker, E., 185

Walker, M., 327

Wallace, B., 427

Wallace, S. F., 540

Walters, D., 163

Walters, T., 129, 130

Walz, W., 265

Wandemakers, W., 42

Wang, S., 44, 45, 46, 61

Wang, X, 328, 329, 340, 341

Warren, S., 411

Watanabe, J., 62

Watanabe, S., 606

Watermaze, M., 97

Watkins, J. C., 170, 175, 176, 479

Watkins, T., 46, 61

Watson, J., 4, 309

Watson, S., 263

Watt, G. D. W., 600, 604

Watts, J. W., 580

Waugh, L, 181

Waxman, S., 170

Webb, W., 360

Weeks, J., 437

Wei, L., 180

Weimann, J., 438–439, 440

Weinrich, M., 170

Weiss, J., 171, 173

Weiss, S., 115

Weisskopf, M, 497

Weitekamp, D., 164

Wellcome, H., 308

Wellcome, S., 308

Weller, R., 538

Wernicke, C., 392

West, K., 89

Westgaard, R. H., 476

Westheimer, G., 320, 338

Westling, H., 112

Wetzel, M. C., 587, 606

Wexler, N., 398

Wheeler, A., 463

Wheeler, J., 463

White, K., 434, 437

Whitehouse, P., 207

Whitman, W., 425

Whitmire, C. J., 547

Whittaker, V. P., 196

Whitteridge, D., 519–520

Wickelgren, B., 313

Widner, H., 106, 107

Wieloch, T., 175

Wieschaus, E., 357, 367

Wiesel, F., 240

Wiesel, T., 165, 310, 311, 320, 345, 358, 365, 368, 376, 377, 393, 514, 526, 541

Wiesendanger, M., 609, 619

Wigner, D., 463

Wigner, E., 463

Wiklund, L., 89

Wild, W. O., 605

Wilderspin, M., 181

Wilkins, J. R., 355

Williams, L., 109

Willis, M. A., 608

Willis, W. D., 599, 606

Wilson, D. M., 581

Wilson, J., 530, 538, 545

Wilson, M., 342

Wilson, P., 374

Wilson, R., 484, 485, 486, 497

Wimmer, E., 371

Windhorst, U., 607

Wingate, R., 368, 375

Wingfield, A., 435, 436

Winzeler, A., 42, 61

Withey, T. P., 603

Wojtowicz, M., 497

Wolosker, H., 218, 220

Wolpaw, J. R., 610

Wolpe, P., 185

Woodbury, W., 617

Woods, A., 272

Woolf, V., 426

Wright, B., 133

Wu, A., 323

Wu, S., 328, 329

Wurtz, B., 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 328, 336, 345

Wydra, K., 273, 274

Wylie, D., 497

Wyss, H., 416

Xu, Y., 341, 342

Yamada, K, 178

Yamamura, H., 201

Yamanaka, S, 116

Yamashita, M., 609

Yang, S. N., 279, 280

Yantis, S., 331

Yates, C. M., 208

Ye, X., 141, 144, 148

Yeats, W. B., 425

Yednock, T, 60

Yi-Xiao, M., 497

Young, A., 167, 175

Young, G., 577

Young, L. R., 324

Young, M., 376

Yu, M., 539

Yu, S. P., 180

Yuan, C. S., 604

Zaczek, R, 200, 203, 204, 209, 210, 220

Zalutsky, R., 497

Zamanian, J., 40, 56, 62

Zastrow, M., von, 488

Zhang, M., 328, 329, 340

Zhang, W., 267

Zhang, Y., 41, 49, 53, 62

Zhang, Z., 342

Zhao, L., 365

Zheng, C., 366

Zhou, H. H., 319

Zhou, Q., 497

Zhou, W., 497

Zhu, X., 375

Zigmond, M. J., 594, 610

Ziminsky, A., 321

Zimmerman, K, 366

Zipfel, G., 179

Zipser, D., 324

Zitrin, C. M., 213

Zivotofsky, A., 329

Zoghbi, H., 367, 368

Zola, S., 185

Zoli, M., 270

Zotterman, Y., 252

Zuchero, B., 39, 47, 62

Zukin, S., 175

Zur, M., 338

Zur, Y., 338