The History of Neuroscience in Autobiography

VOLUME 6

The History of Neuroscience in Autobiography

VOLUME 6

Edited by Larry R. Squire

2009

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Contents

Previous Contributors

Preface to Volume 1

Preface to 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

Index of Names

Previous Contributors

Volume 1

Denise Albe-Fessard

Herbert H. Jasper

Julius Axelrod

Sir Bernard Katz

Peter O. Bishop

Seymour S. Kety

Theodore H. Bullock

Benjamin Libet

Irving T. Diamond

Louis Sokoloff

Robert Galambos

James M. Sprague

Viktor Hamburger

Curt von Euler

Sir Alan L. Hodgkin

John Z. Young

David H. Hubel

Volume 2

Lloyd Beidler

Jerry Lettvin

Arvid Carlsson

Paul MacLean

Donald Griffin

Brenda Milner

Roger Guillemin

Karl Pribram

Ray W. Guillery

Eugene Roberts

Masao Ito

Gunther Stent

Martin Larrabee

Volume 3

Morris H. Aprison

Ainsley Iggo

Brian B. Boycott

Jennifer Lund

Vernon B. Brooks

Edith and Patrick McGeer

Pierre Buser

Edward R. Perl

Hsiang-Tung Chang

Donald B. Tower

Claudio A. Cuello

Patrick D. Wall

Robert W. Doty

Wally Welker

Bernice Grafstein

Volume 4

Per Andersen

Andrew F. Huxley

Mary Bartlett Bunge

JacSue Kehow

Jan Bures

Edward A. Kravitz

Jean Pierre G. Changeux

James L. McGaugh

William Maxwell (Max) Cowan

Randolf Menzel

John E. Dowling

Mircea Steriade

Oleh Hornykiewicz

Richard F. Thompson

Volume 5

Samuel H. Barondes

Lynn T. Landmesser

Joseph E. Bogen

Rodolfo R. Llinás

Alan Cowey

Alan Peters

David R. Curtis

Martin Raff

Ennio De Renzi

Wilfrid Rall

John S. Edwards

Mark R. Rosenzweig

Mitchell Glickstein

Arnold Bernard Scheibel

Carlton C. Hunt

Gerald Westheimer

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, regardless 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 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 on 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.

Preface to Volume 6

This sixth volume of The History of Neuroscience in Autobiography includes 14 autobiographical chapters by senior neuroscientists. The authors tell about the experiences that shaped their lives; the teachers, colleagues, and students with whom they worked; and the scientific work that has absorbed them during their careers. Their essays serve as enduring records of a lifetime of discovery and achievement.

Volume 6 was prepared with the support and advice of the Publications Committee at the Society for Neuroscience, which serves as editorial board for the project. With input from the Committee, from the Council of the Society for Neuroscience, and from many other individuals, names were compiled to contribute to the volume.

At the Society for Neuroscience, Maisha Fleming-Miles (Editorial Manager) coordinated the project with enthusiasm and efficiency. Although the volumes are official publications of the Society for Neuroscience, Oxford University Press became a partner in the project in 2008 and has coordinated the technical editing, printing, and marketing. Volume 6 proceeded under the very capable direction of Craig Panner (Executive Editor, Neuroscience and Psychology) and David D’Addona (Editorial Assistant). I hope readers will find Volume 6 as interesting and enjoyable as earlier volumes.

Larry R. Squire
Del Mar, California
March, 2008

Bernard W. Agranoff

BORN:

Detroit, Michigan

June 26, 1926

EDUCATION:

University of Michigan, B.S.

Wayne State Medical School, M.D. (1950)

Fellow, National Foundation for Infantile Paralysis, Department of Biology, MIT (1951)

APPOINTMENTS:

Laboratory of Neurochemistry, National Institute of Neurological Diseases and Blindness (1954–1960)

Mental Health Research Institute and Department of Biological Chemistry, University of Michigan (1960–2003)

Director, MHRI (1985–1995)

Director UM Neuroscience Research Building (1983–2002)

Ralph Waldo Gerard Professor of Neurosciences in Psychiatry (1995–2003)

HONORS AND AWARDS (SELECTED):

President, American Society for Neurochemistry (1973)

Fogarty Scholar-in-Residence, NIH (1988)

Henry Russell Lecturer, University of Michigan, (1988)

Chairman, International Society for Neurochemistry (1989)

Institute of Medicine (1991)

Distinguished Alumnus Award, Wayne State University (1993)

American Academy of Arts and Sciences (2002)

Bernard Agranoff initially became known for his elucidation of the enzymatic synthesis of inositol lipids via the liponucleotide precursor CDP-diacylglycerol, a crucial step in signal transduction cycling. He also pioneered studies in memory and more generally neuroplasticity. His behavioral studies in the goldfish employed puromycin and other inhibitors of macromolecular synthesis to demonstrate that acquisition of a light coupled-to-shock avoidance task did not require ongoing brain protein synthesis, whereas in contrast, long-term memory formation did. He and his colleagues demonstrated the decay of short-term memory as well as an environmental trigger that initiated the memory fixation process. He also employed the goldfish visual system to identify proteins associated with nerve regrowth and synaptogenesis in the adult vertebrate brain following optic nerve crush.

Bernard W. Agranoff

After looking through autobiographies of fellow neuroscientists in this series, as well as those of fellow biochemists elsewhere, I find that my childhood is not as unique as I had thought: son of Jewish immigrants from Eastern Europe, influenced in my teens by books about biomedical discoveries, and so on. Yet, from our origins, each of us travels a different path. My research career unfolded in the last half-century during which neuroscience arose as a discipline. I will relate here how I became a biochemist, a neurochemist, and then a neuroscientist. Now, in my retirement, I am honored to have been invited to share my reminiscences. I apologize in advance for errors or omissions that may have crept into or out of my memory.

Early Years

I was born in Detroit, Michigan, in 1926, the youngest of three, with an older sister, and a brother who died in infancy. My mother was born in Dovid Horodok, a shtetl near Minsk. She crossed the ocean alone and disembarked at Ellis Island. She then traveled to Detroit, where an older brother and other relatives preceded her. She soon found work as an assistant in the Detroit Public Library. My father was born in Pogorelitz, a village in the Ukraine near Kiev. He came to Detroit in his teens around 1910. He entered the United States at Galveston, Texas, and found his way to Detroit, where he had relatives. He soon was happily on the Ford Motor Company assembly line, a beneficiary of the Henry Ford $5-a-day policy. He eventually had a job at Parke, Davis and Company as a shipping clerk, then in partnership with his brother started a grocery store that was to sustain our families for the next 40 years. We lost our home during the Great Depression and lived in rented flats thereafter but never went hungry.

My parents had met through a circle of friends who can best be described as Yiddish-speaking immigrant anarchists (not communists, to my good fortune, as will be elaborated). In retrospect, they were hard-working, independentthinking, secular Jews. They shared a common atheistic bent, were married in civil ceremonies, but were unlikely to have wed a gentile. None of them, including my mother, wore a wedding ring. Our parents spoke Russian only occasionally, as an infuriating parental secret code. My mother was a “culture vulture,” and I am grateful now for the concerts and plays, English and Yiddish, to which we were dragged. She was an ardent supporter of territorialism, a movement seeking to establish a Jewish Homeland. I recall Tasmania and Uganda, among other suggestions. I’m sure that part of the appeal for her was the secular nature of Jewish territorialism. The movement declined sharply in 1948, when Israel was recognized as a Jewish state. Like most neighbors, my parents loved Roosevelt, and we listened together on the radio to his “Fireside Chats.”

I attended public schools but also went to a secular Yiddish school for an hour each day after public school let out. I learned to read and write in Yiddish. In our high school years, we had classes on weekends, reading Yiddish newspapers and novels, occasionally slightly sexy ones that alleviated the boredom. We read the Old Testament, translated into Yiddish, as literature.

My mother was loving, intelligent, a good cook, and had a great sense of humor, shared with my father. There was often much laughter among us. Unfortunately, she suffered off and on from severe depression. She was subjected to various treatments, including electroshock and insulin shock therapies, and convalescent stays. There were no mood-modulating drugs other than barbiturates and bromides for insomnia. During such periods, it was hard on all of us, off to school or work, leaving her at home alone, disconsolate. This may have influenced my sister’s decision to become a psychiatric social worker and resulted in my being exposed by osmosis to the mysteries of psychoanalysis and psychobabble, perhaps replacing a craving for occult fantasies that religion might have provided. For me, this fitted in well with my aunt Anna’s library. Anna, like my mother, was an assistant librarian at the Detroit Public Library. She lived nearby and had a large, crammed bookcase. Only many years later did it occur to me that much of her home library must have consisted of deacquisitioned public library books that now served a purely decorative role. There were books on Mesmerism, phrenology, and animal magnetism that piqued my curiosity and engendered an interest in the mind and the brain. I tried hypnotizing myself and some of my friends without success.

I had two major interests growing up: art and science. My sister was a born musician. She began playing the piano by ear at age 3 or 4 and had a beautiful singing voice. I had no such talent but staked out drawing and painting for which I had some talent. This landed me in a Saturday morning art class in the Detroit Institute of Arts for 20 or so lucky city school students, who were given unlimited access to art supplies and, should we request it, guidance. Across Woodward Avenue from the Art Museum was the Main Public Library. There was a room filled with U.S. patents that fascinated me, and I thought that maybe I would be an inventor. I was especially into stratospheric balloons and rockets (a Jules Verne influence). My major passion was chemistry, learned almost entirely from library books. Like several of my friends, I had set up a little lab in our basement and bought, traded, or blew my own glassware and scrounged chemicals from pharmacies and local commercial vendors. A common pursuit among budding basement chemists was, of course, making explosives, starting with gunpowder, as well as stink bombs and hydrogen gas to put into balloons that were launched with stamped postcards, This was back in the Zeppelin days, before helium became freely available.

When I was about 14, I learned of a college student, about 6 years my senior, who lived across Monterey Street who, it was rumored, once had a basement chemistry lab. I was interested in what he might be willing to sell or give me, but we didn’t connect until 20 years later when we met in Washington, D.C., as fellow neurochemists. Eugene Roberts (see Volume 2 in this series) is well known for his elucidation of the structure and function of γ-aminobutyric acid (GABA) and more generally for his keen insights over the years into the molecular basis of brain function and dysfunction. We met thereafter at various scientific committees and meetings and remain close friends. Each of us served as president of the American Society for Neurochemistry. The nearby public schools from elementary through high school were of high quality, but my closest friends and I opted to attend Cass Technical High School, three of them in the Science curriculum, and I in Art, actually called Commercial Art.

Two disturbing events during that first semester in the fall of 1941 stand out in my memory. The first relates to my first day of classes in a course titled Mathematics for Art Students. The teacher, who had written a textbook of the same name, stood at the blackboard, having drawn two triangles that she declared to be similar. I raised my hand and asked what the proof was? She answered, “You feel it in your bones.” I was able to switch to the Science curriculum math course that day but was already shaken regarding my choice of the Art curriculum. I found myself unhappily drawing letter fonts, not what I had envisioned as part of becoming an artist. On the positive side, there was a wonderful art history course, in which a competent and enthusiastic teacher reviewed the emergence of art, primarily architecture, by means of hundreds of beautiful lantern slides, from Egyptian, Grecian, and Roman eras, through the middle ages, renaissance, and on to the twentieth century.

The second event occurred a day after the Sunday, December 7, 1941, when Japanese aircraft launched a surprise attack on Pearl Harbor. On Monday morning, our art curriculum homeroom teacher instructed the 20 or so of us 15-year-olds to pull our stools into a semicircle. She then launched into a venomous racial rant that even outrage over the attack could not justify. Her tirade, and a lack of any disbelief or embarrassment I could infer on the part of my fellow art students, reinforced my conclusion that I needed to reconsider my educational prerogatives. I switched to the Architecture curriculum, which replaced my tedious lettering with drafting. I should add that neatness was not my forte. Fortunately, by the time I graduated, I had been able to finish 3 years of chemistry, 2 of math, as well as a year each of Physics, Biology, and Bacteriology, all with excellent grades, more than satisfying the requirements for graduation, but not for college entry, because I had not fulfilled a foreign language requirement. This was not a worry for me, because I would turn 18 in the month I graduated, and would doubtless soon be serving in the armed forces. Military service against the Nazi-led Axis in World War II was clearly a just cause. I applied to the Air Force Cadet program, under the assumption that my envisioned demise by plummeting from the sky would be more merciful than would be sinking into infantry mud. There was a long shot—the Navy V-12 program that would send one directly from high school to an officer’s training program at a university. I would guess that a third or more of the males in our graduating class of about 500 applied for this. I saw my chances as bleak, based on poor grades as an art/ architecture student during my first year of high school, and a neurasthenic, unathletic affect that probably didn’t look much like one’s concept of officer material. In addition, the Navy required a supporting letter from a clergyman. I managed to get a letter from my (atheistic) Jewish school teacher but was not hopeful that it would withstand scrutiny. I was thus pleasantly surprised to learn from our Monterey Street neighbors that federal agents had made inquiries about my family’s political affiliations—my application was being considered! The agents were looking for possible communists in our family who might also be enemy foreign agents, as the USSR had initially been allied with Germany. This remained an issue even after Russia had been invaded in Hitler’s Operation Barbarossa (by then 1944). Sometimes the enemy of your enemy is still your enemy.

Our neighbors reassured the feds that we were merely socialists or anarchists, and that apparently made everything O.K. At any rate I was even more amazed when a thorough physical exam found me to be fit. I believe I was one of only two graduating seniors to be admitted to the V-12 program. During the enlistment process, I discovered that what I thought was my birth certificate was just a souvenir from the hospital. When I obtained a valid one from the State, I found out that I had a middle name, my father’s. It was a surprise to all of us.

Thus, a week after my high school graduation, I found myself living in a University of Michigan dormitory in Ann Arbor, 30 miles from Detroit, in a white sailor suit, ideal for hitch-hiking home on weekends, and uncertain of how, or whom, to salute. I was an apprentice seaman in the U.S. Navy and a freshman at the University, one of about 15 V-12’ers in an accelerated premedical program that was to put us in medical school in 2 years.

I had not envisioned a career as a physician. On the other hand, as alluded to in my introduction, I had indeed been inspired in my early teens by two books: Arrowsmith, by Sinclair Lewis, which dealt with a scientist who discovered bacteriophage, and Microbe Hunters by Paul de Kruif, which described the exciting discoveries of Louis Pasteur, Robert Koch, Ehrlich, and many others. Only later did I learn that Lewis and de Kruif had been acquaintances at the University of Michigan and had inspired one another regarding the thrill of biomedical research. The fictional Dr. Max Gottlieb in Arrowsmith was said to be the combination of bacteriologist Frederick Novy and chemist Moses Gomberg, both world-acclaimed professors at the University at the time. In October of 1945, 16 months after I entered the Navy, the war was over, and I suddenly became an impoverished undergraduate student, living in an Ann Arbor student co-op. I worked part-time in the Chemistry Building, filling student laboratory reagent bottles at night, and occasionally dispensing supplies from the Chemistry Building store. I was thrilled to fill an order (I recall it was for ammonium chloride) for a pleasant emeritus professor—it was Moses Gomberg!

I learned that I would have to wait at least a year for entry into the UM Medical School. I surmised that there were many returning Jewish war veterans who filled the unspoken Jewish quota and decided, rather than wait, to attend Wayne State Medical School, a decision that had the additional financial advantage of free room and board with my parents, and more opportunities for part-time work as an “extern” at night in various small Detroit hospitals during my last 3 years of medical school. Most of my medical school classmates were war veterans, 4 to 10 years my senior, and academically a bit rusty. I found medical school unexciting and reconsidered my future. I made plans to drop out after my second year, to pursue a future in histochemistry, a quest that began with my infatuation with the beauty and the mystery of stained eosinophilic white blood cells. What were those microscopic red jewels made of? I lined up a graduate student fellowship at the University of Minnesota but was dissuaded by my Professor of Medicine, who urged me to finish the M.D. degree before pursuing my scientific interests. My girlfriend at the time concurred. Professor Gordon Scott, who taught my Histology course, took an interest in me and arranged for me to spend the summer of my sophomore year in the laboratory of Anatomy Professor Ernest Gardner, looking for stained nerve endings in joint capsules of cats.

My third-year clinical lectures were boring, but to my surprise I enjoyed seeing and treating patients, in the medical school setting and moonlighting as an extern. I was thrilled on the rare occasions when I detected a major treatable medical condition that had been overlooked. I interned at the Robert Packer Hospital and Guthrie Clinic in Sayre, PA. Its attractions for me included a month’s rotation in a Pathology laboratory. There were connections with the Mayo Clinic, should I elect further clinical training. Last, the rustic setting appealed to me. In a few months, I disabused myself of a fantasy that I could spend my life as a country doctor, although I did become enthusiastic about horseback riding in the beautiful surrounding hillsides. During that internship year, my father came out to visit me. I was delighted and touched. He was a kind person, worked hard, and was worn down by my mother’s illness, leaving little time for dad and son time, growing up. We had some good talks in Sayre that made up for years of uncommunicativeness.

Over the year, I came to recognize that my future was to be in experimental bioscience and preferably in an urban setting. I contacted Dr. Scott (he eventually became Dean of Wayne State Medical School), who had offered to help me should I opt for a research career. He suggested the names of two colleagues from his past: Keffer Hartline at Johns Hopkins University, and Francis O. Schmitt, at MIT. I decided to visit MIT first, and was so impressed with the fancy and massive equipment that I might be able to put my mitts on, such as the electron microscope and the analytical ultracentrifuge, that I did not look further. Some of this love of big equipment I attribute to the elusive toy electric train I campaigned for unsuccessfully as a child.

I arrived in Cambridge, Massachusetts, in the fall of 1951 pretty much broke but had lucked into the position of night physician at the MIT Homberg Infirmary before arriving. This took care of my room and board. I would take an elevator in what was then the main MIT building to the “roof level,” where the elevator lobby opened into a single room and bath, with the Infirmary one flight down. There were usually two to five students in the Infirmary with flu or stomach upset, and the occasional appendicitis, which in the latter instance meant that I’d do a white blood cell count and, if high, contact an on-call surgeon to confirm the diagnosis and ship the patient off to a hospital. I continued this until I was able to secure a research fellowship. I recall being interviewed before a sizeable group of reviewers at a conference room in the Roosevelt Hotel in Manhattan. My application was directed at training in basic research in the nervous system but was not very specific. I was asked why The Infantile Paralysis Foundation (now March of Dimes) should sponsor me. I responded that only by training more basic research scientists would the treatment or prevention of polio be advanced. There was a silence, followed by a perfunctory “thank you very much.” I interpreted this as a death knell for the application. To my surprise, it was awarded. That permitted me to devote more of my time to graduate study and uninterrupted sleep. Schmitt, my sponsor, was also Chair of the Department of Biology. The departmental research emphasis was on ultrastructure of proteins, using mostly biophysical techniques. The study of proteins of the giant axon of the squid, as well as of collagen and myosin from various other sources, were major themes. There was little research on living creatures or even on cultured cells. I recall a framed sign on the wall over the desk of one of the postdoctoral fellows that said it all: “If it moves, step on it.”

Schmitt and I agreed on several graduate courses that I would take, including a physics course for MIT students from elsewhere, a physiology course on size and shape of proteins, electron microscopy and physical chemistry, but not the biochemistry course, which at that time was part of the departmental Microbiology program. Although I had not considered going for a Ph.D., at Schmitt’s suggestion I took and passed the graduate prelim exam. After I delivered a graduate seminar on the physical properties of white blood cells, including my beloved eosinophil, Bert Vallee, a faculty member, approached me about a possible research project to physically separate white cells. I was happy to get my hands wet and devised a differential centrifugation method on a sucrose gradient that we eventually published. I never did get back to the eosinophil. My future plans were curtailed by the Korean conflict (war). It seems that my V-12 stint had included an obligation to serve as a Naval physician if called up. The Navy was quite good about delaying my orders to report for duty, but then my draft board insisted that I report for induction as an Army private. When it became clear to me that they meant business, I reluctantly asked the Navy to reissue my orders, cutting my stay at MIT short. In October 1952, I reported to the Naval Medical School in Bethesda, Maryland, as a naval officer.

Bethesda: The Naval Medical Center, Then National Institutes of Health

It turned out that I had been assigned to what was then called the Naval Medical School to lecture on topics in medical biochemistry, such as acidbase balance, laboratory tests, and so on. This was part of a refresher course for Navy physicians, who were delighted with a month or two of respite from sea duty. The chemistry lab was responsible for all of the hospital blood analyses, and miscellaneous other duties, including supervising the hospital’s blood drawing facility, and training courses for Navy lab techs. Mostly, we let experienced petty officers who knew the ropes do their thing, and to step in when a Medical Officer’s approval was needed.

My predecessor as Officer-in-Charge was Roscoe Brady, who had been researching fatty acid synthesis at the University of Pennsylvania, and was also fulfilling a 2-year military obligation. When his tour of duty was over, he moved across the road to the National Institutes of Health (NIH) to join a large newly established Laboratory of Neurochemistry as head of a Section on Lipid Chemistry. The Scientific Director of the new facility was Seymour S. Kety, famous for his development and application of the nitrous oxide method for measuring cerebral brain flow. He was, in addition, Scientific Director of the National Institute of Mental Health and the National Institute of Neurological Diseases and Blindness. This is described in detail in the autobiographies of Seymour Kety, and also of Louis Sokoloff (both are in Volume 1 of this series). When my tour of duty was over, I accepted an offer from Brady to join his Section on Lipid Chemistry. This appealed to me more than did the option of returning to MIT. My immediate neighbors on the third floor of the newly constructed Building 10 of NIH included Alex Rich’s Section on Physical Chemistry, Kety’s (later Sokoloff’s) Laboratory of Cerebral Metabolism, and Giulio Cantoni’s Laboratory of Cellular Pharmacology. An orthogonal wing of the third floor housed the Laboratories of Biophysics, and Neurophysiology, which included the laboratories of Ichiji Tasaki, “K. C.” Cole, and Wade Marshall. The geographical separation of the neurochemical and neuropharmacological sections from the biophysical and electrophysiological sections mirrored a long tradition in brain research that has been referred to as “soups” and “sparks” (see section on Gerard). We had in common a bank of elevators. The new labs at NIH included psychologists and anatomists, including Bill Windle, also in Building 10, and a bit more distant, geographically and otherwise. Some 10 years later, we would all be referred to as neuroscientists. Much later, in 1988, I was a Fogarty Scholar-in-Residence at the NIH. We lived in the same apartment house as Seymour and Josie Kety and got to know and enjoy their company again after a 30-year hiatus.

The years from the fall of 1954 to the fall of 1958 were busy ones for me at NIH. I had the freedom to engage in a project of my choosing, preferably one having relevance to the brain, lipids, or both. Most important, it was expected that findings would be written up, approved, and coauthored by Brady, my section chief, and would be published in a respected journal. A prior interest in carbohydrate metabolism led me to an unsolved mystery: how inositol lipids were synthesized. This was an exciting problem to me for many reasons. The brain was known to be enriched in phosphoinositides, and I found the stereochemistry of inositol, its isomers, and their phosphate esters intriguing. The laboratory of Eugene Kennedy had already made the important discovery that cytidine nucleotides played a central role in the formation of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine, but how phosphatidylinositol and its further phosphorylated family members were formed remained an enigma. An added point of great interest to me was the report of Hokin and Hokin (1953) that carbamylcholine stimulated the incorporation of radiolabeled inorganic phosphate selectively into phosphatidylinositol in pancreatic tissue slices. The concentrations of carbamylcholine required to produce this effect were high (millimolar), casting doubt on the physiological significance of the effect. However, it was blocked by 10 micromolar atropine, an indication to me that their observations had great physiological relevance.

After many false leads, I experienced that rare eureka moment that was at once exhilarating and fulfilling. I had initially assumed that a hypothetical cytidine diphosphate (CDP)-inositol would react with diacylglycerol to form phosphatidylinositol in analogy to the biosynthesis of the other known phospholipids. My results suggested otherwise: They were compatible with the existence of a cytidine liponucleotide intermediate that would react enzymatically with free inositol, with the production of phosphatidylinositol and cytidine monophosphate (CMP). I performed the critical experiment with a fragile sense of confidence. When it worked out as predicted, I felt at last that I was a player in the game of biochemical research. Brady was not directly involved in the research project or writing the paper but wisely insisted that I submit the paper before going off for a year on an NIH off-campus assignment to work in the laboratory of Feodor Lynen, in the fall of 1958. During that year away, Kennedy’s lab confirmed the proposed liponucleotide intermediate and its role in phosphatidylinositol synthesis. I could have been scooped.

Many other events important for me transpired in those first 4 years at NIH. In those early days, the NIH Library was also in Building 10, and I routinely spent Saturday mornings scanning the latest journals. I was also looking for ways to more directly relate my research to brain function. One such morning, I read what was then known about Miltown (meprobamate), a blockbuster prescription drug described as a tranquilizer. Despite the fact that it was being prescribed widely, nothing had been reported regarding its disposition in the body. It appeared to be a highly stable lipophilic molecule, the dicarbamate of a branched-chain propanediol. I was sure it would be excreted pretty much intact.

I consulted a pharmacologist neighbor in Building 10 who was pretty much a one-man operation at NIH and who had received his doctorate only after he had published independently. I told him that I was able to produce a colored product by heating the drug in sulfuric acid but was disappointed that it wasn’t fluorescent and would not lead to a sensitive assay. He convinced me that the visible spectrum would suffice and agreed it mostly likely would be excreted largely intact, as a glucuronide. So I swallowed four Miltowns, collected my urine for several days, added glucuronidase to samples, extracted the lipid material with ether, reacted it with sulfuric acid, and voila, a paper by me, my technician, and Julius Axelrod (14 years before he won the Nobel Prize, not for this!) with the first evidence of human metabolic disposition of meprobamate (using an N of 1, myself).

This paper had an interesting consequence. Some months later, a tall slim reddish-haired man stormed into my lab module, shouting with a Germanic/ Balkan accent, “I am looking for Berrrnard Agrrranoff.” He was Frank Berger, “Mr. Miltown,” president of Wallace Laboratories, who was visiting NIH, and had decided to look me up. He was grateful for what we had done and invited me to consult with his company, which I did, once I left the Public Health Service. He enters my story by way of a meeting he organized in 1956 at the New York Academy of Sciences on Meprobamate (Miltown). As it happened, I had been radiolabeling a number of substances of interest by “Wilzbaching,” subjecting them to highly radioactive tritium gas, which resulted in displacement of covalently linked hydrogen atoms by tritium. One of the substances that I labeled was meprobamate. At the meeting, I heard a talk by Eckhart Hess of the University of Chicago on the effects of meprobamate on imprinting of ducklings. I had been searching for an animal model of memory that could be studied biochemically, and imprinting ducklings sounded attractive. Hess offered to show me his setup in a bird sanctuary that by my good fortune was located in nearby Maryland. I was impressed with the demonstration and accepted his offer of a few eggs near hatching along with instructions about how to imprint the newly hatched ducklings. I took the eggs back to my NIH lab and, as instructed, I was the first moving thing the ducklings saw after hatching. As I walked away, they followed. In fact they subsequently followed anyone with a long white lab coat, with preference for males. On further consideration of proceeding further, I concluded that though meprobamate prolonged the period in which the ducklings could be imprinted, this was likely a nonspecific effect of delaying an anxiety response, and was not specifically related to memory formation. I also disabused myself of the naïve idea that labeled meprobamate would be localized in brain regions directing the imprinting response. Our dishwashing assistant was not enthusiastic about cleaning the duck cages, and eventually “a place in the country was found for them,” a fate that befell some Easter chicks of my childhood. My initial foray into animal behavior had failed.

In March of 1957, I met a beautiful and charming young woman at a party. We went on many walks through Georgetown, talking into the wee hours about her childhood in Boston, of living in the Philippines for several years with her father, and our many mutual interests. Ricky (Raquel Schwartz) and I were married that September, and a year later, we were off for a year in Germany.

Munich

The Max Planck Institut für Zellchemie was then located in central Munich, and I was privileged to participate in an exciting race to elucidate the biosynthesis of cholesterol. Feodor Lynen was a brilliant and inspiring scientist, with a good sense of humor. By the end of the year, he was a good friend as well. In addition to work, the year provided a good way to improve my German language skills. Before leaving for Europe, I contacted Lyle Packard of Packard Instruments to locate a liquid scintillation counter near Lynen’s Institute. There indeed was one, in a Munich hospital. This information, my experience in scintillation counting, and the generosity of the hospital proved helpful during the year in counting radioactivity in volatile metabolic intermediates. I worked on the isomerization of a terpene precurser, isopentenyl pyrophosphate to dimethylallyl pyrophosphate, an early step in the biosynthesis of sterols, including cholesterol.

We were fortunate to be able to travel on weekends to neighboring Austria, Switzerland, France, and Italy in our VW convertible. In the summer, we drove and camped our way to Ricky’s father and family in Barcelona. During this year, my budding interest in behavior was on hold. However, I did manage to visit Konrad Lorenz, who was a neighbor of Lynen in the outskirts of Munich. I am hazy on the details of our discussion, but fish behavior did come up because I remember him telling me that he had been bitten by a parrotfish while swimming.

When we returned to Bethesda, it became clear that it was time to move on. My working relationship with Brady had soured, and I wanted to be on my own. Prospects for new independent positions at NIH were some years off.

I look back at my NIH years as happy ones. The community was filled with bright scientists, senior and junior. Guilio Cantoni’s journal club and the meetings of the NIH-Johns Hopkins Enzyme Club were informative and convivial. We had many good friends. Even so, I began to explore possible moves.

Moving to Ann Arbor

I was attracted by an offer at the University of Michigan. I knew and liked Ann Arbor. In addition, my parents were getting on and still lived in Detroit, and I felt Ricky and I could be of help when needed. The offer was from the University of Michigan’s Mental Health Research Institute, a wide-ranging microcosm of academia put together by James G. Miller, an M.D./Ph.D. psychiatrist, and psychologist, who left the Psychology Chair at the University of Chicago to form the Institute in 1955 under the aegis of Raymond Waggoner, Chair of Psychiatry at the University of Michigan Medical School. Miller brought with him several University of Chicago colleagues, among them Ralph W. Gerard, as Director of Laboratories.

Ralph Waldo Gerard

I interrupt my narrative to pay homage to the remarkable man who offered me the position. Gerard had been a bona fide child prodigy, receiving his Ph.D. from the University of Chicago when he was 21. Among his many discoveries, he is perhaps best known for developing the microelectrode together with Gilbert Ling. He also wrote several well-received readable books that clearly presented what was then known about cellular biology and especially about the brain. I had first heard him speak at scientific meetings in Washington, D.C., in the mid-1950s. He spoke unhesitatingly, without notes and in measured tones, as if from a script. When asked in advance for a manuscript, he would suggest that his words be recorded and transcribed. The commas and periods seemed in place, and no infinitives had been split. Gerard was frequently invited to present a summary of a morning or afternoon program. His genius shone; without notes, he would accurately restate each speaker’s salient points, often better than did the speaker, and would weave the talks together into an aesthetic whole. If you had the temerity to ask a question after he spoke, as I once did, you took your life in your hands—he cut me off at the knees.

It was thus with some apprehension that I entered my interview with him in Ann Arbor. Fortunately, he seemed not to remember me. I was also a bit concerned that he might press me into a scientific collaboration at a time that I was looking forward to being completely independent. There was no problem. Ralph was, and remained, cordial and helpful. He was at the time engaged in a large project at a state mental hospital that involved extensive questionnaires, laboratory tests and measurements, and by design without an hypothesis. Answers were to appear via correlations, using a new and magical tool: the computer, and tens of thousands of punch cards. The approach seems inelegant today, but in the late 1950s it was cutting-edge stuff to psychiatrists. Gerard also kept a small lab and, with a student, was developing a spinal learning paradigm in frogs. He asked me for advice about a possible biochemical intervention. I recommended trying 8-azaguanine, based on studies by Dingman and Sporn (1961; also cited by Sam Barondes in Volume 5 of this series). I first heard from Ralph about the historical “soups and sparks” dichotomy in approaches to understanding neurotransmission. The “soups” were the biochemists and pharmacologists, who identified chemical messengers, and the “sparks” were the neurophysiologists who recorded nerve impulses. The orthogonal corridors on the third floor of Building 10 at the NIH came to mind. It is unclear who originated the “soups and sparks” phrase (perhaps it was Gerard), chronicled by Valenstein and also by Van der Kloot, who credits Ling and Gerard’s micropipets as key in demonstrating chemical transmission at the synapse and resolving the issue. Gerard had been well prepared in both camps. After completing his Ph.D. and M.D., he studied nerve impulses in the laboratory of A. V. Hill in Cambridge, England, then nerve metabolism in the laboratory of renowned biochemist Otto Meyerhof, in Germany. In his travels, Gerard also visited Ivan Pavlov in Moscow, and shortly thereafter Sigmund Freud, in Vienna. Three years after I came to Ann Arbor, Gerard left to become Dean of Graduate Studies at UC Irvine, where he remained until his death in 1974.

A Dual Research Career

For me, an attraction of the Michigan offer was that I would have a tenured joint appointment in the Department of Biological Chemistry and could remain a card-carrying biochemist, and at the same time wade into murky waters, that is, to pursue my conviction that biochemistry could make an important contribution to our understanding of behavior. Because my labs were in the Institute rather in Biological Chemistry Departmental space, I would be spared the possible embarrassment of being categorized by my biochemist colleagues as an odd duck or as it turned out, a strange fish. I found the lab space I was being offered more than adequate, but somewhat isolated. I suggested the Institute also recruit Norman Radin, a colleague I had met through Federation of American Societies for Experimental Biology (FASEB) and other meetings, who studied brain glycolipids, then at Northwestern University in Chicago. This worked out very well.

Thus I began my independent professional life with two divergent interests: phospholipids and behavior, with precious little overlap. I had no idea this would continue for my entire professional career. It was a bit like Sophie’s choice: which child would I desert? I have cautioned my students and postdoctoral fellows not to pursue this double research strategy. “Do as I say and not as I do!” In today’s climate of restricted grant support, I probably would not have so easily been able to pursue divergent interests. Shortly after arriving, I applied for and was awarded an NIH grant to further explore phospholipids. I also began to consider how I would at last get into brain and behavior. I began by determining the amounts of total deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) in brain tissue. Quantitative methods then used were based on phosphorus content and worked well for DNA and RNA of most organs but were troublesome in brain. We found this was mostly due to the contamination of nucleic acid preparations with the very acidic phosphoinositides. We devised a new method that worked well for rat brain. To apply the method, I turned to Tryon maze-bright and maze-dull rats that were being bred and studied anatomically by David Krech, Mark Rosenzweig, and their collaborators. Mark suggested sending me frozen brains, but I preferred, and he agreed, that he send me live rats because I was concerned about the time interval following death that the brains would be frozen. I was surprised to see that the two inbred strains that he sent us looked very different in appearance. My naïve concept of specific genes that regulated maze behavior quickly evaporated. We found no significant differences in total brain DNA or RNA between the two strains.

Flatworms and Memory Transfer

Shortly after coming to Ann Arbor, I met Jim McConnell, a psychologist who had attracted considerable attention as a result of his behavioral experiments on the flatworm, planaria. The paradigm was simple. Light from a gooseneck lamp over a small glass dish containing a planarian was paired with an electric shock administered through the water, resulting in a whole body contraction. After many trials, the worms were reported to have been conditioned: they “scrunched up” following light alone. McConnell further claimed that if trained worms were cut in half, and the head and tail segments were allowed to regenerate so that each formed a complete planarian, both regenerated halves displayed the trained response. Additional variants, including feeding chopped up bits of trained worms to naïve ones, reportedly worked as well. Much of this was published in McConnell’s Worm Runner’s Digest, a circulated pamphlet/periodical with separate experimental findings and humor sections.

I observed inexperienced undergraduate students collecting data firsthand. They were motivated to get positive results and, in my opinion, were poorly monitored to boot. I concluded that the results I saw being gathered from McConnell’s lab were untrustworthy. Yet I remained hopeful that these simple creatures might serve well as experimental subjects, if a more objective means of measurement of the response could be devised, other than deciding whether the little critters scrunched up or not. I hired a lab assistant, Paul Klinger, and had him build a multicompartmented apparatus that would allow six planaria to each escape from the lighted end of a small chamber to the dark end to avoid electric shock. The chambers’ illumination was directed by a relay from a toy train set sitting in the image plane of a photographic enlarger. A summer student whom I hired from the McConnell lab mob spent a summer working for me faithfully with this apparatus, and we gradually lost hope of seeing an escape response, let alone a learned avoidance. At long last, I sent him to the pet store to purchase a dozen guppies. They were about the same size as planaria but with eyeballs, a brain, spinal cord, and so on. It was truly amazing to see the guppies demonstrate the escape and even some shock avoidance behavior after only a few trials.

This marked the end of my interest in flatworms. We didn’t publish our failure. Over the subsequent years, people would occasionally confuse my goldfish research with McConnell’s worms. On occasions when asked for my opinion of the planaria research, I attempted to be diplomatic and not criticize a colleague at the same institution. My stance was, and is, that if a reproducible robust experimental paradigm produced clear data supporting memory transfer, I would be willing to listen. McConnell once proposed to bet a bottle of Scotch on whether memory transfer in planaria would ever be widely accepted. I asked him how we would make the decision, say 5 years hence. He proposed that we sum up all of the papers that are confirmatory and those that are not, winner take all. We got hung up on the details and never made the wager. I recall discussing this issue with Ralph Gerard. He told me about the mitogenetic rays of Alexander Gurevitch, a Soviet scientist who proposed in the 1940s that dividing cells emit faint ultraviolet light that stimulate mitotic activity in cells in their optical path. There were dozens of papers, even doctoral theses, elaborating on the reported observations. Ralph made the point that, though no one categorically disproved the hypothesis, fewer and fewer citations and publications on the topic appeared. Authors are not as motivated to publish a failure to reproduce a scientific claim as to report a new discovery. He predicted accurately the demise of memory transfer research. The reports of Georges Ungar in the 1960s and 1970s that injection of a peptide extracted from the brains of mice trained in an auditory extinction task into naïve mice conferred the learned response, created much excitement. Despite Ungar’s published structure of the peptide, interest waned, probably because of the lack of a robust objective behavioral assay. Louis Irwin has summarized his attempts and those of others in search of a demonstration of memory transfer.

Training Fish

Paul Klinger and I continued working with fish after the guppies trounced the flatworms. We began training giant danios (related to zebrafish) to maintain a fixed position in a donut-shaped rotating tank, as measured by a photodetector and recorder. I don’t know where this project was taking us, but a freeze in Florida put an end to our fish supply, and we needed a new experimental species. I was drawn to the ready availability of goldfish and only then discovered a rich literature on training them. At this time I had became intrigued by the experiments of Louis and Josepha Flexner on the block of memory formation in mice by the protein synthesis inhibitor puromycin. Gabriel de la Haba, a former NIH colleague who had codiscovered the mechanism of action of this antibiotic, and was now in Flexner’s Department of Anatomy at the University of Pennsylvania, had recommended the use of the agent to them. As it happened, I was now making regular visits to nearby Cranbury, New Jersey, to consult for Frank Berger on the development of a cholesterol-lowering drug. In connection with one such trip, I arranged with Gabe to visit the Flexners’ lab in the morning and made an appointment for that afternoon to meet with psychologist Geoff Bitterman in his lab at Bryn Mawr, a few miles away. Bitterman showed me his many goldfish setups and remarked that one of his problems with using goldfish, for example in establishing visual or appetitive preferences, was their memory, which interfered with his experiments. Memory! I recall leaving in a daze. I walked, deep in thought, to the train station, found a payphone, and called Geoff back to be sure I had heard correctly what I thought I had. When I got back to Ann Arbor, I had Paul build a bank of six goldfish-size shuttle boxes, each fitted with photodetector beams on either side of a midtank barrier We could inject enough puromycin intracranially to block brain protein synthesis in a 10 µL volume quickly and reproducibly by means of a Hamilton gas chromatography syringe. We soon demonstrated that the puromycin had no measurable effect on acquisition of a light coupled-to-shock avoidance task but did block long-term memory formation, as measured in a retraining session a few days later. We reported this in Science, as well as at an American Association for the Advancement of Science (AAAS) National Meeting in Berkeley, in 1964. Memory disruption became insusceptible to the injected agent an hour after training. Roger Davis, a zoologist, joined as a postdoctoral fellow and brought much needed fish and behavioral expertise. He designed and conducted experiments to demonstrate the time course of decay of short-term memory and also characterized an “environmental trigger” that was required for the onset of the memory fixation process. We surmised that disruption of protein synthesis in the fish brain had no measurable effect on acquisition of the light–shock avoidance response, but blocked the process whereby long-term memory is formed in a consolidation process that began after the training. The process was complete in about an hour, after which the fish were no longer susceptible to the blocker. We later learned that initiation of the consolidation process required that the fish be removed from the stressful training environment. A similar phenomenon, called “detention,” has been described in rodents. Memory consolidation of an aversive task did not begin until the animals were removed from the experimental environment and returned to the safety of their home cages. A hypothesis that there was a “shreckstoffe” in the training tank water that kept the fish aroused was short lived; it turned out that the delaying cues were probably visual. Roger later found that the vulnerability of memory to various blocking agents could be reinstated for a period some time after protein blockers were thought to be no longer effective.

Fig. 1    This lithograph by Honoré Daumier (1808 –1879) of fish being trained came from a Paris bookstall. Daumier’s intent was to satirize the establishment of a scientific oceanographic station in Concourneau, Brittany, according to a letter to the author from the late Professor A. Fessard. A companion lithograph depicts fish dancing to the teacher’s toodling.

In 1967, I was invited to write an article for Scientific American magazine on our work on goldfish memory. The magazine reprinted over 100,000 copies of the article, presumably many of them for high school and college classes. It has been rewarding over the years to be approached by neuroscientists at a Society for Neuroscience meeting, recognizing me from my nametag, to tell me how this essay was their introduction to neuroscience. The fact that research was being performed on fish memory engendered public and academic interest, some of it in unexpected ways. Following an invited lecture at Harvard, my host, E. O. Wilson, presented me with a John Macdonald detective novel. The plot turned out to be relevant to our research. There were many invitations to lecture, often at symposia where other ongoing biochemical and pharmacological studies on memory were reported. I met Sam Barondes and his former mentor Murray Jarvik, as well as Ed Glassman, Art Cherkin, Jim McGaugh, Felix Strumwasser, Eric Kandel, Stephen Rose, and numerous others at such “road shows,” each of us working on his favorite creature, most commonly rodents. For the next 5 years, we examined many parameters of the behavior of various other macromolecular synthesis blockers and began to look for possible changes in goldfish brain protein synthesis that could be correlated with behavior.

The Neuroscience Research Program

Francis Otto Schmitt had by now formed his Neuroscience Research Program (NRP) and convened meetings periodically on exciting subjects in a “castle” in Brookline, a Boston suburb. He was not only the Scientific Director, but also impresario, and developmental officer rolled into one. He was also the prime student. He sat in the front row of each session, took notes, and asked good questions. He foresaw not only that the “soups” and “sparks,” but the microscopists, biophysicists, and behaviorists as well had intersecting interests. It has been said that Ralph Gerard coined the term “neurosciences,” but Schmitt and his NRP group must be credited with bringing neuroscience to the fore as an entity. Following NRP meetings, always on timely topics, the NRP circulated blue and white-covered meeting summary bulletins, which were widely circulated.

After participating in one of his thematic meetings, Schmitt invited me to a week-long course to be held in the summer of 1965 at MIT, to which about 10 world-famous scientists, unfamiliar with the nervous system were to immerse themselves in the excitement of neuroscience by dissecting a human brain—one apiece. I was invited as a kind of docent, already having a medical degree, and being relatively knowledgeable on brain structure. The instructor was Walle Nauta. His assistants were Jay Angevine and Gardner Quarton, a psychiatrist and NRP Staff Director. Ricky and our 4-month-old son Will stayed at a cottage on Cape Ann overlooking a cemetery and beyond that the Atlantic. I was billeted at an MIT dormitory next door to Melvin Calvin, celebrated for his discovery of the mechanism of carbon dioxide fixation in photosynthesis. His laboratory at U.C. Berkeley had an ongoing interest in brain and behavior, headed by Edward Bennett.

I have tried in these pages not to wander off my narrative too much but am tempted to tell a little side story. Calvin and I were dorm neighbors. As I left my room one morning, I found him in the hallway, talking on a payphone. He motioned to me that it wouldn’t take long and to wait for him, so I stood there, waiting. I overheard him say, “Well, tell ’em to put ’em in a plastic bag” and then hung up. As we started to walk toward the classroom building, my curiosity got the better of me. At last I said, “What was that all about?” Calvin replied, “Oh, there are these astronauts meeting down in Wood’s Hole. They’re trying to figure out how to handle the Moon rocks.” At the time there was much speculation among scientists and in the press about potential chemically toxic or infectious perils of anything brought back to Earth from the Moon. I had just borne witness to how such weighty problems end up being handled in the real world. Fortunately, we seem to have survived—this time.

Fig. 2    Photographs from The NRP’s Brain Dissection Course, in 1965. An F. O. Schmitt production, being filmed, perhaps for television. The instructor, Walle Nauta, in white lab coat, Jay Angevine at the blackboard. Seated facing the camera is Gardner Quarton. In the foreground, left, myself; right, Melvin Calvin.

Another attendee was the late Seymour Benzer, who had not yet begun (as far as anyone knew) his move from bacterial genetics at Purdue to his ingenious behavioral studies with drosophila at Cal Tech. We enjoyed interesting food and tested Boston’s most obscure restaurants together. A few years later, he invited me to give a talk at Cal Tech and asked me to select the kind of cuisine I’d like to sample for dinner. In an attempt to stump him, I suggested Albanian. Unfortunately, he found a place.

Two years after the MIT brain dissection course, Schmitt and his NRP staff convened a month-long NRP meeting in Boulder, Colorado, the first of four to be held over the next few years. I was invited to the first of them in 1967, with my wife and children as well as my postdoctoral fellow, Roger Davis and his family. It was a stimulating month-long adventure in science and a wonderful treat for our families. I presented a lecture on our goldfish research and prepared a chapter for the resulting massive tome, the first the series of four. My chapter included further confirmatory results of our original goldfish study with a different protein synthesis blocking agent, acetoxycycloheximide. I was so favorably impressed with the skills of Helene Jordan Wadell, an editor assigned to the book, that I contacted her a few years later to edit the first edition of the textbook Basic Neurochemistry. She served in this capacity for the next three editions as well, working closely with the chief editor, George Siegel.

Schmitt had asked me, in addition to my own lecture and book chapter, to take on a review of recent studies on memory transfer, that is, McConnell’s planaria experiments, Ungar’s studies in mice, and so on. I balked at the assignment, and the task fell on Gardner Quarton, Schmitt’s NRP associate. I knew “Q,” as he was called, from my previous NRP activities, including the “brain dissection” class. Eventually, Q moved to Ann Arbor in 1969 as Director of the University of Michigan Mental Health Research Institute (MHRI), succeeding Jim Miller. He remained in this position until his death in 1985. Q was a great colleague and friend. He was idolized by the psychiatry residents, whom he enjoyed counseling. At Boulder, Melvin Calvin introduced me to David Samuel, a biochemist at the Weizmann Institute in Israel, then on sabbatical with him in Berkeley. Samuel later invited me to teach a 6-week neurochemistry course at the Weizmann Institute in Rehovot in 1971.

Neuroplasticity

For the next 5 years, we examined many parameters of the behavior of various other macromolecular synthesis blockers and began to look for detectable changes in protein synthesis that could be correlated with behavior. Our research on goldfish memory and protein synthesis blockers can be categorized as interventive, more pharmacological than biochemical. Interventive approaches permit investigation of complex phenomena such as animal behavior but bear the serious caveat that the agents being administered may have multiple effects not directly related to the process being addressed. Molecular genetic interventions may have similar drawbacks. The ideal complementary experiment would be correlative: to observe memory formation without disrupting it (a bit like astronomy). Such a correlative biochemical approach is offered by the administration of radioisotopically labeled precursors followed by a search for changes in precursor incorporation, under experimental, compared with control conditions. We had been able to distinguish short-term from long-term forms of memory behaviorally but had no inkling of where in the brain to look biochemically nor what the magnitude of putative relevant biochemical changes might be. We nevertheless felt obligated to examine incorporation of amino acid precursors into protein with the tools then in hand, gel electrophoresis of proteins from brain regions, subcellular fractions, and so on. We concluded that this was not a useful approach.

We stepped back and sought a model system that would permit us to detect proteins that are being made in the developed adult brain undergoing neuroplastic synaptogenesis, analogous to what we infer happens during memory formation. These conditions are met in regeneration of the teleost optic nerve. In memory formation and in regeneration, we are dealing with an adaptive response of an adult nervous system to an external input that we believe involves synaptogenesis. The optic tracts are completely crossed, so we began by injecting labeled amino acids intraocularly and looking for labeled proteins arriving at various times in the contralateral tectum. We found that the sensitivity of this procedure was compromised by the use of labeled amino acids that leave the eye via the circulation and then enter both right and left tecta, where they are incorporated into tectal proteins that were not transported from the retina. We overcame this problem by using [³H]-proline, a nonessential amino acid for which the brain had no transport system through the blood–brain barrier. This proved to be an ideal agent for radiolabeling nerve pathways, and an improvement over the then prevalent use of essential amino acids, that do cross the barrier, such as [³H]-leucine. At this point, in 1974, we went on sabbatical to the laboratory of R.M. Gaze, at the National Health Institute at Mill Hill in England. I tried my hand at tissue culture, using adult frog retinal explants, with little success. Tadpole eyes did better but were too tiny to manipulate. Mike Gaze suggested crushing the optic nerve in an adult frog, waiting a few days, and then explanting. This worked very well, and we did the same with goldfish when we returned to Ann Arbor. The goldfish retinas were large enough to cut into multiple squares by means of a McIlwain tissue chopper, yielding retinal “baklava” for explant culture. We studied the microscopic behavior of neurites, and the effects of the growth media and matrix. Anne Heacock observed a marked tendency for the outgrowing neurites to rotate clockwise along the culture dish surface, which we attributed to the sliding of growing and spiraling helical fibers over the matrix.

We returned to comparing 2-D gels of [³H]-proline-labeled, axonally transported proteins produced in intact retinas that of retinas following nerve crush. We decided to pursue a labeled doublet that appeared a few days after nerve crush and began to wane in 2 weeks after nerve crush, a time that optic nerve regeneration was reaching completion. This doublet was known to be axonally transported as well. That is, it originated in the denervated retinal ganglion cells. We isolated the doublet, and dubbed the pair G68 and G80, based on their presumptive molecular weights (kDas). We employed an antibody to the doublet to verify its localization in retinal ganglion cells during regeneration. A partial sequence was used by Mike Uhler’s lab to clone complementary deoxyribonucleic acid (cDNAs). These RICH (Regeneration-Induced-CNPase-Homolog) proteins are neuronal in origin and are part of a superfamily that includes 2'-3' cyclic nucleotide 3'phosphodiesterase (CNPase). RICH protein is present in zebrafish as a single protein (zRICH). This is as far as we got. The biological bases of vertebrate memory formation have come a long way since then but are still far from understood. Molecular biology and genetics, together with innovations in in vivo imaging, ranging from the microscopic level to human brain imaging, presage exciting challenges and discoveries. There will be plenty to do for quite a while.

Phospholipids

I maintained my interest in inositol and phospholipids, trying to go beyond our work on phosphatidylinostol synthesis to relate it to cholinergic signaling. It was ultimately the contributions of Berridge and of Nishizuka and their collaborators that finally unraveled the role of inositol lipids in signal transduction, with the demonstration of inositol 1,4,5-trisphosphate and diacylglycerol as second messengers. We had made much use of a high voltage paper electrophoresis (HVE) technique for separating [³²P]-labeled inositol phosphates. Using it, we confirmed the release of [³²P]-labeled inositol trisphosphate, in this case from human platelets (mine).

myo-inositol is one of six possible stereoisomers of hexahydoxycyclohexane. It is the most common isomer and the one present in the inositol lipids. It has one axial and five equatorial hydroxyls. There are many phosphorylated derivatives of inositol that play roles in signal tranduction. To clarify a then existing confusion in numbering the six ring positions of phosphorylated inositol, I proposed the use of a three-dimensional turtle cartoon, in which the axial hydroxyl is the head, and the four limbs plus the tail constitute the five equatorial hydroxyl groups. This visual device has been associated with my name and ironically may well outlive my other contributions to science. My lipid research is detailed in a forthcoming “Reflections” essay in The Journal of Biological Chemistry.

Neurochemistry and Neuroscience

With attendance of the Society for Neuroscience annual meeting exceeding 30,000, it is bemusing to recall that one of the justifications for starting the Society in the early 1970s was that the annual meeting of the FASEB, which had over 10,000 registrants in the 1960s, was thought to be getting too large. It cannot be denied, however, that the interdisciplinary approach to basic questions regarding brain function has proven exciting and rewarding. As a biochemist working in the nervous system, “neurochemistry” pretty much describes my scientific interests. I first heard the term in 1953 as the name of Kety’s new laboratory at NIH. He was also a founding editor of the Journal of Neurochemistry. The International Society for Neurochemistry (ISN) was formed as an outcome of several international symposia, the first of which was held at Magdalen College, Oxford, in 1954 (also described by Kety in Volume 1 of this series). The first ISN meeting was held in Strasbourg, France, in 1967. There was considerable interest on the part of several U.S. members of the ISN to form an American Neurochemical Society (ASN), and its first meeting was held in Albuquerque, New Mexico, in 1970. The first meeting of the Society for Neuroscience was held in Washington, D.C., in 1971. Ralph Gerard was named its first (honorary) president. The ASN annual meetings were, and have remained, relatively small, about a thousand attendees, and are focused on biochemical and molecular neuroscience. They are usually held in the spring in relatively small towns. This is in sharp contrast to Society for Neuroscience meetings, which are limited to one of a few large convention centers. Attendees select from a huge menu of scientific offerings, with little possibility of absorbing more than a fraction of the program. Yet its breadth is also its strength. My research on biochemical correlates of behavior found a receptive home at these meetings.

For the Society for Neuroscience meeting in Atlanta, Georgia, in 1979, I was invited to host a neurochemical evening mixer. For this, I organized a light-hearted, yet scientific symposium on Molecular Gastronomy. Invited speakers addressed the chemical properties of a specific food. The speakers and subjects of their talks were Henry Mahler on truffles, myself on onions, and Louis Sokoloff on glucose. It was well received, and I was persuaded to organize a second such symposium for the 1980 Society for Neuroscience meeting in Cincinnati. To my knowledge, though tongue-in-cheek, this marked the first use of the term molecular gastronomy, now employed somewhat more seriously. For neurochemists, there is an additional connection. J. L. W. Thudichum is considered by many of us to be the founder of neurochemistry. His identification of various phospholipids, sphingolipids, and brain fatty acids, as well as his treatise on brain chemistry is a neurochemical historical cornerstone. He also wrote treatises on the chemistry of wine, on gallstones, and a cookbook.

The ISN meetings have brought together colleagues throughout the world that had known one another only by name. In addition, of course, we have traveled to places we might never have experienced and gained insight into how others live. Participation as a council member and society officer was educational in scientific matters as well as diplomacy (and sometimes lack thereof) as well. I am convinced that international professional organizations are valuable channels for breaking down national and ethnic barriers that become increasingly important issues as the world shrinks.

Table 1.    Students, Postdoctoral Fellows 1960–2003

Inositol and Phosphoinositides, Signal Transduction

Joyce A. Benjamins

Gary A. Davis

Stephen K. Fisher

William Jackinovich, Jr.

Yaakov Lavie

Prushpa P. N. Murthy

James E. Novak

Gary Petzold

Harry Rittenhouse

Ulrich Seiffert

R. Michael Snider

Evan B. Stubbs, Jr.

Lucio A. A. Van Rooijen

Fatty Acids, Acyl Dihydroxyacetone Phosphate (DHAP), other Lipids

John E. Bleasdale

Carl A. Boast

Cinda Sue Davis

J. Lindsley Foote

Amiya K. Hajra

Joshua Hollander

John M. Hollenbeck

Frank R. Masiarz

Robert J. Pollack

William D. Suomi

Brain Imaging

Lance L. Altenau

Oliver G. Cameron

Kirk A. Frey

Biochemical and Behavioral Correlates of Memory

Fred Baskin

Jerry J. Brink

Harry R. Burrell

Luigi Casola

Roger E. Davis

Linda A. Dokas

Howard Eichenbaum

Ramon Lim

Elaine A. Neale

Joseph H. Neale

Richard J. Santen

Jochen Schacht

W. Michael Schoel

Alan Springer

Goldfish Retinal Regeneration, Explants, Axonal Transport RICH Protein

Rafael P. Ballestero

Keith A. Cauley

Joseph A. Dybowski

John S. Elam

Eva L. Feldman

Thomas Ford-Holevinski

Anne M. Heacock

James M. Hopkins

Shinichi Kohsaka

Gary E. Landreth

Kenneth C. Leskawa

Michael L. Leski

Pamela R. Raymond

Michal Schwartz

Lawrence R. Williams

George R. Wilmot

James L. Olds

Barry L. Shulkin

I am indebted to the doctoral students and postdoctoral fellows with whom I shared my laboratory, ideas, and collegiality. I was extremely fortunate to have had the able technical assistance of Roy M. Bradley at the National Institutes of Health, and at the University of Michigan Edward B. Seguin (in lipid biochemistry) for 38 years, and Paul K. Klinger (in behavioral equipment design, measurements and statistical analysis) for over 25 years.

Acknowledgments

I have been fortunate in many ways. By a stroke of luck, I was assigned by the Navy to the University of Michigan right out of high school. My medical education served me well; it piqued my interest in biomedical research and did not deter me from continuing my preparation for a research career. At the NIH, I was immersed in a stimulating environment created by Seymour Kety, an inspiring role model. When we moved to Ann Arbor from Bethesda in 1950, I thought that we would not stay more than a few years. We had several opportunities to leave over the years for warmer climates, particularly in the winter, and for the excitement of big-city life. The anchors have been my happy professional life with friendly colleagues, good students and postdocs, and excellent facilities. Ricky became deeply involved in various culinary activities, culminating in, together with two other faculty wives, a restaurant named the Moveable Feast that was set in an historic house and that continued on for 20 years, until it was sold and renamed. I thank her for putting up with me these past 50 years.

The schools for our two boys were excellent. Will is a graphic designer and creative director of a communications company in Seattle, Washington. Adam is a physician and lives nearby. Each of them and their wives have provided us with a grandson and a granddaughter (four total).

I am particularly grateful to the NIH and NSF, the Markey Charitable Trust, and to the late Ralph and Elsie Colton, for research support. I thank my successors, codirectors, Huda Akil and Stan Watson, who renamed MHRI as MBNI (Molecular and Behavioral Research Institute) for leaving the welcome mat out. Thanks to Mary Driscoll for help with the bibliography and James Beals with the graphics.

Selected Bibliography

Agranoff BW. Inositol metabolism. Fed Proc 1957;16:379.

Agranoff BW. Low level tritium counting techniques. In Bell CG, Hayes FN, eds. Liquid scintillation counting. New York: Pergamon Press, 1958;220–222.

Agranoff BW. Molecules and memories. Perspect Biol Med 1965;9:13–22.

Agranoff BW. Agents that block memory. In Quarton GC, Melnechuk T, Schmitt FO, eds. The neurosciences: A study program. New York: Rockefeller University Press, 1967;756–764.

Agranoff BW. Memory and protein synthesis. Sci Am 1967;216:115–122.

Agranoff BW. Macromolecules in brain function: A 1969 Baedeker of neurobiology. In Progress in molecular and subcellular biology, Vol. 1. Heidelberg, Germany: Springer-Verlag, 1970;203–212.

Agranoff BW. Effects of antibiotics on long-term memory formation in the goldfish. In Honig WK, James PHR, eds. Animal memory. New York: Academic Press, 1971;243–258.

Agranoff BW. Biochemical concomitants of learning and memory. In Kiger JA, Jr., ed. Biology of behavior. Corvallis: Oregon State University Press, 1972;1–9.

Agranoff BW. Ralph Waldo Gerard (Obituary). J Neurochem 1974;23:5.

Agranoff BW. Memories of Munich. In Hartman GR, ed. Dieaktivierte Essigsaure und ihre Folgen. Berlin-New York: W deGruyter Publishers, 1976;213–216.

Agranoff BW. Cyclitol confusion. Trends Biochem Sci 1978;3:N283–N285.

Agranoff BW. Symposium report: Inositol trisphosphate and related metabolism. Fed Proc 1986;45:2627–2628.

Agranoff BW. Exploring brain and mind (1988 Russel Lecture, University of Michigan). Michigan Quarterly Rev Spring, 1989;216–228.

Agranoff BW. Brain food. Gastronomica 2008;8.

Agranoff BW. Reflections. J Biol Chem (in preparation).

Agranoff BW, Benjamins JA, Hajra AK. Biosynthesis of phosphatidylinositol. Ann NY Acad Sci 1969;165:755–766.

Agranoff BW, Bradley RM, Axelrod J. Determination and physiological disposition of meprobamate. Proc Soc Exp Biol Med 1957;96:261–264.

Agranoff BW, Bradley RM, Brady RO. The enzymatic synthesis of inositol phosphatide. J Biol Chem 1958;233:1077–1083.

Agranoff BW, Davis RE. Further studies on memory formation in the goldfish. Science 1967;158:523.

Agranoff BW, Davis RE, Brink JJ. Memory fixation in the goldfish. Proc Natl Acad Sci USA 1965;54:788–793.

Agranoff BW, Eggerer H, Henning U, Lynen F. Isopentenolpyrophosphate isomerase. J Amer Chem Soc 1959;81:1254.

Agranoff BW, Field P, Gaze RM. Neurite outgrowth from explanted Xenopus retina: An effect of prior optic nerve section. Brain Res 1976;113:225–234.

Agranoff BW, Hajra AK. The acyl dihydroxyacetone phosphate pathway for glycerolipid biosynthesis in mouse liver and Ehrlich ascites tumor cells. Proc Nat Acad. Sci USA 1978;68:411–415.

Agranoff BW, Klinger PD. Puromycin effect on memory fixation in the goldfish. Science 1964;146:952–953.

Agranoff BW, Murthy PPN, Seguin EB. Thrombin-induced phosphodiesteratic cleavage of phosphatidylinositol bisphosphate in human platelets. J Biol Chem 1983;258:2076–2078.

Agranoff BW, Seguin EB. Preparation of inositol triphosphate from brain: GLC of trimethylsilyl derivative. Prep Biochem 1974;4:359–366.

Agranoff BW, Vallee BL, Waugh, DF. Centrifugal subfractionation of polymorphonuclear leukocytes, lymphocytes, and erythrocytes. Blood 1954;9:804–809.

Agranoff BW, Van Rooijen LAA. Polyphosphoinositide turnover in the nervous system, In Bleasdale JE, Eichberg J, Hauser G, ed. Inositol and phosphoinositides: Metabolism and regulation. Clifton, NJ: Humana Press, Inc., 1985;621–635.

Altenau LL, Agranoff BW. A sequential double-label 2-deoxyglucose method for measuring regional cerebral metabolism. Brain Res 1978;153:375–381.

Ballestero RP, Dybowski JA, Levy G, Agranoff BW, Uhler MD. Cloning and characterization of zRICH, a 2,'3-cyclic-nucleotide 3'-phosphodiesterase induced during zebrafish optic nerve regeneration. J Neurochem 1999;72:1362–1371.

Ballestero RP, Wilmot GR, Agranoff BW, Uhler MD. gRICH68 and gRICH70 are 2,'3-cyclic-nucleotide 3'-phosphodiesterases induced during goldfish optic nerve regeneration. J Biol Chem 1997;272:11479–11486.

Ballestero RP, Wilmot GR, Leski ML, Uhler MD, Agranoff BW. Isolation of cDNA clones encoding RICH: a protein induced during goldfish optic nerve regeneration with homology to mammalian 2,'3-cyclic nucleotide 3'-phosphodiesterases. Proc Natl Acad Sci USA 1995;92:8621–8625.

Baskin F, Masiarz, FR, Agranoff BW. Effect of various stresses on the incorporation of ³H-orotic acid into goldfish brain RNA. Brain Res 1972;39:151–162.

Benjamins J, Agranoff BW. Distribution and properties of CDPdiglyceride: Inositol transferase from brain. J Neurochem 1969;16:513–527.

Berridge MJ. Unlocking the secrets of cell signaling. Ann Review Physiol 2005; 67:1–21.

Brink JJ, Davis RE, Agranoff BW. Effects of puromycin, acetoxycycloheximide and actinomycin D on protein synthesis in goldfish brain. J Neurochem 1966;13: 889–896.

Burrell HR, Dokas LA, Agranoff BW. RNA metabolism in the goldfish retina during optic nerve regeneration. J Neurochem 1978;31:289–298.

Burrell HR, Heacock AM, Water RD, Agranoff BW. Increased tubulin messenger RNA in the goldfish retina during optic nerve regeneration. Brain Res 1979; 168:628–632.

Casola L, Lim R, Davis RE, Agranoff BW. Behavioral and biochemical effects of intracranial injection of cytosine arabinoside in goldfish. Proc Nat Acad Sci USA 1968;60:1389–1395.

Chiba T, Fisher SK, Agranoff BW, Yamada T. Carbamoylcholine and gastrin induce inositol lipid turnover in canine gastric parietal cells. Amer J Physiol 1988;255: G99–G105.

Davis, GA, Agranoff BW. Metabolic behavior of isozymes of acetylcholinesterase. Nature 1968;220:277–280.

Davis RE, Agranoff BW. Stages of memory formation in goldfish: Evidence for an environmental trigger. Proc Natl Acad Sci USA 1966;55:555–559.

Dingman W, Sporn MB. The Incorporation of 8-azaguanine into rat brain RNA and its effect on maze learning by the rat: An inquiry into the biochemical basis of memory. J Psychiatr Res 1961;1:1–11.

Drabkin DL.Thudichum, Chemist of the brain., Philadelphia: University of Pennsylvania Press, 1958.

Eagle H, Agranoff BW, Snell EE. The biosynthesis of meso-inositol by cultured mammalian cells, and the parabiotic growth of inositol-dependent and inositolindependent strains. J Biol Chem 1960;235:1891–1893.

Eichenbaum H, Butter CM, Agranoff BW. Radioautographic localization of inhibition of protein synthesis in specific regions of monkey brain. Brain Res 1973; 61:438–441.

Elam JS, Agranoff BW. Rapid transport of protein in the optic system of the goldfish. J Neurochem 1971;18:375–387.

Elam JS, Goldberg JM, Radin NS, Agranoff BW. Rapid axonal transport of sulfated mucopolysaccharide proteins. Science 1970;170:458–460.

Feldman EL, Axelrod D, Schwartz M, Heacock AM, Agranoff BW. Studies on the localization of newly added membrane in growing neuritis. J Neurobiol 1981; 12:591–598.

Fisher SK, Agranoff BW. Calcium and the muscarinic synaptosomal phospholipid labeling effect. J Neurochem 1980;34:1231–1240.

Fisher SK, Frey KA, Agranoff BW. Loss of muscarinic receptors and of stimulated phospholipid labeling in ibotenate-treated hippocampus. J Neurosci 1981;1: 1407–1413.

Fisher SK, Klinger PD, Agranoff BW. Muscarinic agonist binding and phospholipid turnover in brain. J Biol Chem 1983;258:7358–7363.

Ford-Holevinski TS, Dahlberg TA, Agranoff BW. A microcomputer-based image analyzer for quantitating neurite outgrowth. Brain Res 1986;368:339–346.

Frey KA, Agranoff BW. Barbiturate-enhanced detection of brain lesions by carbon-14-labeled 2-deoxyglucose autoradiography. Science 1983;219:879–881.

Frey KA, Ehrenkaufer RLE, Agranoff BW. Quantitative in vivo receptor binding II: Autoradiographic imaging of muscarinic cholinergic receptors. J Neurosci 1985; 5:2407–2414.

Frey KA, Ehrenkaufer RLE, Beaucage S, Agranoff BW. Quantitative in vivo receptor binding I: Theory and application to the muscarinic cholinergic receptor. J Neurosci 1985;5:421–428.

Frey KA, Hichwa RD, Ehrenkaufer RLE, Agranoff BW. Quantitative in vivo receptor binding III: Tracer kinetic modeling of muscarinic cholinergic receptor binding. Proc Natl Acad Sci USA 1985;82:6711–6715.

Gerard RW. International physiology (an address celebrating the 75th Anniversary of the American Physiological Society). Physiologist 1963;6:332–334.

Hajra AK, Agranoff BW. Acyl dihydroxyacetone phosphate, a new phospholipid from mitochondria. Fed Proc 1967;26:277.

Heacock AM, Agranoff BW. Clockwise growth of neurites from retinal explants. Science 1977;198:64–66.

Heacock AM, Agranoff BW. Enhanced labeling of a retinal protein during regeneration of the optic nerve in goldfish. Proc Nat Acad Sci USA 1976;73:828–832.

Heacock, AM, Uhler MD, Agranoff BW. Cloning of CDP-diacylglycerol synthase from a human neuronal cell line. J Neurochem 1996;67:2200–2203.

Hokin MR, Hokin LE. Enzyme secretion and the incorporation of P32 into phospholipides of pancreas slices. J Biol Chem 1953;203:967–977.

Hopkins JM, Ford-Holevinski TS, McCoy JP, Agranoff BW. Laminin and optic nerve regeneration in the goldfish. J Neurosci 1985;5:3030–3038.

Irwin LN. Scotophobin. Lanham, MD: Hamilton Books, 2007.

Jakinovich W, Jr., Agranoff BW. The stereospecificity of the inositol receptor of the silkworm bombyx mori. Brain Res 1971;33:173–180.

Johns PR, Heacock AM, Agranoff BW. Neurites in explant cultures of adult goldfish retina derive from ganglion cells. Brain Res 1978;142:531–537.

Johns PR, Yoon MG, Agranoff BW. Directed outgrowth of optic fibers regenerating in vitro. Nature 1978;271:360–362.

Kennedy EP. The biosynthesis of phospholipids. In Op den Kamp JAF et al., eds. Lipids and membranes: Past, present and future. Amsterdam: Elsevier, 1986; 171–206.

Koeppe RA, Mangner T., Betz LA, Shulkin BL, Allen R, Kollros P, Kuhl DE, Agranoff BW. Use of 11C-aminocyclohexanecarboxylate for the measurement of amino acid uptake and distribution volume in human brain. J Cereb Blood Flow Metab 1990;10:727–739.

Kohsaka S, Dokas LA, Agranoff BW. Uridine metabolism in the goldfish retina during optic nerve regeneration: Cell-free preparations. J Neurochem 1981;36: 1166–1174.

Landreth GE, Agranoff BW. Explant culture of adult goldfish retina: Effect of prior optic nerve crush. Brain Res 1976;118:299–303.

Landreth GE, Agranoff BW. Explant culture of adult goldfish retina: A model for the study of CNS regeneration. Brain Res 1979;161:39–53.

Lee C, Fisher SK, Agranoff BW, Hajra AK. Quantitative analysis of molecular species of diacylglycerol and phosphatidate formed upon muscarinic receptor activation of human SK-N-SH neuroblastoma cells. J Biol Chem 1991;266: 22837–22846.

Leski ML, Agranoff BW. Purification and characterization of gp68/70, regeneration-associated proteins from goldfish brain. J Neurochem 1993;62:1182–1191.

Ling G, Gerard RW. The normal membrane potential of frog sartorius fibers. J Cell Comp Physiol 1949;34:383–396.

MacDonald, JD. The girl in the plain brown wrapper. New York: Fawcett, 1968. McIlwain H. In the beginning: To celebrate 20 years of the International Society for Neurochemistry (ISN). J Neurochem 1985;45:1–10.

Neale JH, Elam JS, Neale EA, Agranoff BW. Axonal transport and turnover of proline- and leucine-labeled protein in the goldfish visual system. J Neurochem 1974;23:1045–1055.

Neale JH, Neale EA, Agranoff BW. Radioautography of the goldfish after intraocular injection of 3H-proline. Science 1972;176:407–410.

Nishizuka Y. Discovery and prospects of protein kinase C Research: Epilogue. J Biochem 2003;133:155–158.

Petzold GL, Agranoff BW. Biosynthesis of cytidine diphosphate diglyceride by embryonic chick brain. J Biol Chem 1967;242:1187–1191.

Santen RJ, Agranoff BW. Studies on the estimation of DNA and RNA in rat brain. Biochim Biophys Acta 1963;72:251–262.

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Schacht J, Agranoff BW. Phospholipid labelling by [³²P]-orthophosphate and [³H]-myo-inositol in the stimulated goldfish brain in vivo. J Neurochem 1972; 19:1417–1421.

Schwartz M, Axelrod D, Feldman EL, Agranoff BW. Histological localization of binding sites of a-bungarotoxin and of antibodies specific to acetylcholine receptor in goldfish optic nerve and tectum. Brain Res 1980;194:171–180.

Schwartz M, Ernst SA, Siegel GJ, Agranoff BW. Immunocytochemical localization of (Na+,K+)-ATPase in the goldfish optic nerve. J Neurochem 1981;36: 107–115.

Schwartz M, Siegel GJ, Chen N, Agranoff BW. Goldfish brain (Na+,K+)-ATPase: Purification of the catalytic polypeptide and production of specific antibodies. J Neurochem 1980;34:1745–1752.

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Emilio Bizzi

BORN:

Rome, Italy

February 22, 1933

EDUCATION:

University of Rome, Rome Italy, M.D. (1958)

University of Pisa, Pisa, Italy, Docenza (Ph.D.) (1968)

APPOINTMENTS:

MIT, Eugene McDermott Professor in the Brain Sciences and Human Behavior (1980–1983)

MIT, Director, Whitaker College of Health Sciences, Technology, & Management (1983–1989)

MIT, Chairman, Department of Brain and Cognitive Sciences (1986–1997)

MIT, Eugene McDermott Professor in the Brain Sciences and Human Behavior (1997–2002)

MIT, Institute Professor (2002– )

HONORS AND AWARDS:

Medical degree with highest honors (summa cum laude) (1958)

Alden Spencer Award (1978)

Hermann von Helmholtz Award (1992)

Secretary of The American Academy of Arts and Sciences (1999)

Italian National Academy (Accademia dei Lincei-Rome) (1998)

American Academy of Arts and Sciences (1980)

National Academy of Sciences (1986)

Degree “honoris causa” in Biomedical Engineering, University of Genova, Italy (2004)

Empedocles Prize (2005)

Institute of Medicine of the National Academies (2005)

President of Italy Gold Medal for achievements in science (2005)

President, the American Academy of Arts and Sciences (2006)

Early in his scientific career, Emilio Bizzi studied the neurophysiological mechanism of sleep and discovered a functional connection between an area of the brain stem and the visual areas of the brain. Later on, his research focused on the physiological mechanisms underlying complex, coordinated movements. His results have formed the basis of a comprehensive theory—the equilibrium-point hypothesis—which accounts for how the central nervous system solves the complex computational problem of executing limb movements. Recently, his laboratory has provided evidence that internal representations of limb dynamics are built by combining modular primitives found in the spinal cord as well as other building blocks in higher brain structures. He has also investigated motor learning and the problem of consolidation of motor memories.

Emilio Bizzi

In the 1950s when I enrolled in Rome’s medical school the word neuroscience did not exist. Scant instructions on the brain’s anatomy and physiology were of course imparted as part of teaching of human physiology, but greater prominence was accorded to the heart, the kidney, and especially the digestive apparatus. No wonder that in my somewhat anxious and idle speculations about my professional future the idea that that I would have ended up as a neuroscientist never occurred to me.

While “neuroscience” was not part of my horizon, it very soon became clear to me that I had a sharp interest for the scientific underpinnings of medicine—I did not know what kind of research I wanted to do—I simply had a yearning for a life devoted to biological investigations rather than the practice of medicine. It is now obvious to me that my early inclinations toward a research career derived to some extent from my family environment. My maternal grandfather, an outstanding surgeon in Milan, was highly regarded in the family more for his contributions to innovative methods in medicine than for his remarkable surgical skills. Another close relative, an uncle, who became Professor of Gynecology at the University of Parma, was known for his investigations of the biological mechanisms of reproduction. But the person that I found most impressive was my grandmother’s brother. A well-known botanist, an enthusiastic, passionate man, totally committed to his research, a member of the Italian National Academy (Accademia dei Lincei, who had had Galileo among its members), he used to visit us when he travelled to Rome to attend the Academy’s sessions. His engaging, passionate descriptions of his searches for exotic plants and flowers in the most remote corners of the Italian mountains are still on my mind as an example of a happy, fulfilling life in the pursuit of knowledge.

In addition to my family environment, my professional future was shaped by the sociopolitical environment that was prevalent in post–world war Italy. Science and intellectual pursuits were highly regarded values, at least in the social circles to which I belonged. After the years of a repressive regime and a devastating war, Rome in the 1950s was a city eager to catch up with modernity; its citizens, deeply involved in political-ideological controversies, generated an environment foreign and perhaps even unfriendly to middle-class, bourgeois values. I was excited to be centered in this uniqueness and was like a sponge absorbing all of these novelties that represented to me a totally different experience from the rigid, somewhat puritanical background of my parents.

Inevitably, as prosperity slowly took roots and as a consumer-oriented environment became prevalent in Italy, that special postwar atmosphere changed. I often still think of those years with a nostalgic feeling, and I am fond of reminiscing about specific events and people I met, but, most of all, I recognize the powerful formative role of those years.

On balance, at medical school I had 6 happy years. In the first 2 years I acquired a decent background in the basic sciences such as chemistry organic and inorganic, physics, lots and lots of human anatomy, and biology. The last 4 years were more fun; I learned about pathology, human physiology, and the clinical specialties. Because students were not compelled to attend the lectures, I had time on my hands that I utilized by working as an intern in the Department of Pathology. I choose pathology because this discipline’s approach allowed a mechanistic understanding of the devastations induced in the body’s organs by disease. In addition, the Department had an outstanding reputation. All of this made sense to me, and I still remember how happy I was when the Chair of Pathology told me that I had won the highly competitive privilege of becoming an intern. What I had not taken into account was that the “privilege” really entailed an out-of-the-ordinary daily routine that I was obliged to follow.

My duties, I was told, were relatively simple: while the pathologist went on with his business of dissecting a cadaver by extracting and then examining one by one all of the deceased’s organs, I was to write down the pathologist’s comments and findings. And, this was in addition to doing my own job every morning—five days a week! The first weeks were really tough—the revolting stench and the gruesome, horrific sights of the procedures were hard to take. But, surprisingly, in the course of a month or two I became used to this unusual universe and began gradually to take an interest in the erudite medical discussions among the pathologists and the physicians that had treated the diseased. Discussions that, incidentally, took place right there in that foul-smelling room.

In retrospect, I still wonder what compelled me to begin my days in this definitely out-of-the-ordinary way. Granted I learned a great deal about medicine, but at what price?

As an intern my duties were not limited to taking notes but included work toward an experimental thesis. My task was to collect tissues from patients that in spite of robust treatment with antimitotic drugs had died of leukemia. This was my “research” assignment, and I dutifully collected all the samples I could in the 2½ years of my internship. I then prepared the samples for histological examination, and in the process I learned much about classical staining technique and how to be familiar with the cellular patterns of different organs. In the end, my diligent efforts were rewarded with a cum laude degree.

I must confess that as I proceeded with my thesis I felt an intense boredom for the type of work I was doing—if this type of descriptive work passes for “research” I was not going to select a career in science. Part of my discomfort was the oppressive intellectual narrowness of the scientific environment of the Pathology Department, which in a sense prevented me from acquiring a broader view of science. The faculty consisted of very serious, hard-working, quasi-monastic investigators whose sense of moral superiority left me cold. The Department was a very inward-looking place; scientists from the outside world would rarely visit, and I do not recall having ever attended a seminar in my 2½-year tenure there. Quite a contrast with today’s departments where the opposite is the norm, and we are constantly flooded by a stream of talks presented by scientists frenetically on the move from place to place.

Clearly research in pathology was not what I was going to consider, but the dislike for the type of descriptive science to which I had been exposed made me question the idea of a career in science. Not surprisingly, the day after my degree was awarded, I felt uncomfortably directionless.

If a career in the unappealing science to which I had been exposed during my student years looked doomed, maybe work in medicine was worth exploring. I therefore applied to the university hospital in Siena and became a member of the staff of the Internal Medicine Department. Siena, an attractive small medieval city about 50 miles south of Florence, had a good medical school, a good teaching program, and, surprisingly for a small provincial, out-of-the-way university, an excellent research program focused on the physiology of the hypothalamus and the reticular formation of the brain stem. I was fortunate in that the leader of the group, Alberto Zanchetti, needed an assistant and asked me to join his research team. From that time forward my days were divided by clinical duties and research.

The combination of clinical service and laboratory work meant long hours, 7 days a week. But in spite of the heavy time commitment, and the almost total disappearance of my social life, I had 2 happy years in Siena. I found medicine and research to be exciting. To be at the bedside collecting the clinical history of a newly admitted patient, to perform the physical examination, and then attempt a diagnosis was an exciting and entirely novel experience. I quickly realized that the body of medical knowledge I had acquired during my pathology days was immensely useful for the understanding of medical riddles and in formulating a diagnosis. The training in pathology I had acquired through the observation of countless autopsies gave me a systemic view of medicine. For instance, when confronted with patients whose liver had been affected by years of heavy Chianti drinking (Siena is at the heart of the Chianti region), I could not only visualize the macroscopic aspects of the diseased liver and the altered cellular configurations, but could also understand its systemic consequences on other organs and the panoply of symptoms could be logically deduced.

Research turned out to be equally exiting. I began as a lowly assistant in charge of cleaning up the surgical instruments and the mess after small animal surgery. However, I did not mind the drudgery of these tasks because I felt privileged to be able to observe, for the first time, “real” scientific work deployed before my eyes. At that time, the late 1950s, some of the leading neuroscientists were investigating the functional properties of the reticular formation. The seminal paper that sparked a great deal of research on this topic had been published in 1949 by Moruzzi and Magoun. This paper, which resulted from a collaboration between Horace Magoun, a neuroanatomist at the University of Chicago and a visiting professor from Pisa, Giuseppe Moruzzi, showed that electrical impulses delivered to the reticular formation (RF) could change the cortical electroencephalogram (EEG) from a pattern characterized by slow waves (like in sleep) to a desynchronized, high-frequency pattern similar to the one present during waking, arousal, and attention. Incidentally, the reticular formation is an anatomical structure located in the pons and the mesencephalon made up of groups of highly interconnected interneurons, of cells receiving input from spinal cord, from cortical and subcortical areas, and from the cerebellum. In addition these are the cells of origin of long fibers projecting to a number of subcortical areas. The anatomy is very complex, but at that time the reticular formation was conceived to be a functional entity capable of regulating the sleep/wake cycle as well as other behaviors.

The project in which I became involved was aimed at understanding some aspect of the reflex regulation of the reticular formation. The model system involved removing all the central nervous system (CNS) structures rostral to the posterior hypothalamus in the cat. The resulting preparation, when appropriately stimulated, displayed the behavior of “sham rage,”—the behavioral sign that activation of the reticular formation and the rostral hypothalamus had occurred. The goal of the research was to explore whether a sham rage attack could be evoked by manipulating the level of blood pressure in a reflex way. We tested the hypothesis that the receptors from the carotid body were conveying impulses that exerted an inhibitory influence to the rostral part of the reticular formation and posterior hypothalamus. We found that by lowering abruptly the blood pressure, thus eliminating the steady flow of impulses originating in the carotid body receptors, an attack of sham rage could result.

I must admit that I found these experiments fascinating—controlling behavior, albeit a highly bizarre behavior like sham rage, through a simple reflex manipulation and localizing to a specific neural structure a highly complex and integrated behavioral response meant getting in touch with a dynamic world of doing science that contrasted with the static experience I had with pathology. What fascinated me and ultimately hooked me to the field of neuroscience was the possibility of studying in a mechanistic way the neural underpinnings of important brain functions.

To me the exposure to experimental science in Siena was similar to the sudden love for classical music that happened when I first heard Beethoven’s symphonies. I went from a person indifferent to classical music to a passionate pursuit of more and more classical music. Needless to say that as I began work in Siena in the late 1950s, I was actually entering the field of neuroscience with no idea of its future developments. But the limited exposure to neurophysiological research experienced in Siena was so compelling that I decided to leave the medical department and a career in academic medicine to get full-time training in neurophysiology. At that time the best place for brain science in Italy was at the University of Pisa in the institute directed by the famous Giuseppe Moruzzi.

The Years in Pisa

In 1960 when I began my training at the Institute of Human Physiology of the University of Pisa, Giuseppe Moruzzi was the uncontested, the highly respected leader, and the absolute ruler of the department. He was a deeply serious person, physically imposing, with a passion for scientific ideas, courteous, but distant and somewhat intimidating; a person totally committed to research who I came to admire, but perhaps not love. At that time, Moruzzi was pursuing a number of lines of research all connected to his main interest: the functional properties of the reticular formation.

In the early 1960s research was poorly funded in Italy, but the Institute in Pisa was a lucky island because Moruzzi had been able to set up a fairly large department, where six to seven groups could conduct investigations with fairly up-to-date equipment. Incidentally, some of the funds came from the U.S. Air Force program, which provided badly needed support in the postwar years. Another feature of the department was the presence of a significant contingent of foreign investigators. As a rule each Italian investigator was teamed with a foreign fellow. To each team he assigned a research theme, he told what experimental approach we were expected to follow and what outcome he expected. He was perfectly comfortable with discussing the details of the investigations, the strategic approach, but he made it clear that the team was going to purse the research topic that he proposed. Naturally, this top-down display of authority did not sit well with some of the more mature foreign visitors; for me, there was no problem. I was a beginner, and it would have been impossible for me to put forward a research plan of my own.

During my first year I was lucky. I was teamed with Alden Spencer, a talented young investigator from Portland, Oregon, who had worked at the National Institutes of Health (NIH) where he had learned the technique of intracellular recording while investigating the properties of the hippocampal cells in collaboration with Eric Kandel. I learned a lot from Alden. He liked to talk about his U.S. neuroscience experience; the people he met at the NIH, the various areas of research he thought were promising and exciting. His stage at the institute was, however, almost a total failure. He did not like the research theme assigned to us, we did not accomplish anything scientifically relevant, and Alden ended up the year quite unhappy. Although I understood and sympathized with Alden’s disappointment, I was not too unhappy; I had learned a lot even from the failed research experience, but especially from Alden.

During my second year my foreign collaborator was Dana Brooks, a neuroanatomist from Cornell Medical School. Moruzzi told us to investigate the origin of the slow potentials that appeared in certain areas of the pontine reticular formation during rapid eye movement (REM) sleep. These slow potentials had been described by Michel Jouvet, a French investigator who was one of the major forces behind research on the neural mechanisms underlying the different phases of sleep. Dana, who had visited Ed Evarts laboratory before coming to Pisa, brought with him a copy of the Evarts microdrive. This microdrive allowed us to position recording electrodes in almost any corner of the cat’s brain. With this device, which we connected to the skull of the animal, we were able to map the pontine slow potentials during the REM phase of sleep. The mapping experiment lasted a few tedious months, and after a while it became gradually clear to us that we would not be able to draw interesting functional conclusions by this exercise. We would have produced a map of electrical events during sleep, but the “so what” thought began creeping in our daily conversations. Before discouragement really set in, something unexpected occurred. At that time I had the habit of reading everything that was published on sleep, and I happened to read a small abstract describing the presence of strange slow potentials in the lateral geniculate of the cat during sleep. I spoke to Dana, and immediately we implanted electrodes in the pontine reticular formation (in the areas we had mapped) and the lateral geniculate. We were thrilled when during the first episode of REM we observed the almost synchronous appearance of slow potentials in the pons and the geniculate. That meant that an extraretinal input was reaching a structure devoted to the transmission of retinal impulses to the visual cortex. In the months following this observation we figured out that the pons was the site of origin of the slow potentials and that the potentials were transmitted from the geniculate to the visual cortex. These ponto-geniculate occipito (PGO) potentials became well known because they were related by others to the visual imagery of dreams.

Before Dana departed for Cornell we wrote a paper that was published in Science. I have often reflected on the serendipitous and lucky circumstances that led us from a tedious, undistinguished mapping experiment to an exciting finding. Later on I had similar experiences where luck, not skills or deep insights, changed the course and the relevance of my research.

During the third and final year of my stage at the Institute in Pisa, my collaborators were Professor Ottavio Pompeiano and a Hungarian postdoctoral fellow, I. Somogyi. We again worked on REM sleep but focused on the pattern of discharge of the cells of the vestibular nuclei. In particular we wanted to record from the cells of origin of the lateral vestibular nucleus. From these cells originate the descending vestibulo-spinal tract, which makes monosynaptic connections with spinal motoneurons. This pathway plays a major role in the control of vertebrate posture. During REM sleep there is complete disappearance of muscular activity especially in postural muscles. Hence, it made sense to ascertain the role of the vestibulo-spinal pathway. Technically, these were not easy experiments, but somehow we managed to record from the vestibular nuclei during REM and found that the cells of the lateral vestibular nucleus did not change their firing rate during the disappearance of the muscular activity in postural muscles. This was clearly a counterintuitive result that suggested the existence of an inhibitory activity conveyed by other descending tracts; a suggestion that was later pursued successfully by Pompeiano. We described the cells we had recorded from the four main vestibular nuclei and published a short paper in Science.

At this point I was ready to move to another environment and begin to be independent. Although the research on sleep had been satisfactory, I was not sure that I wanted to pursue that line of investigation. I was quite certain that I would not have been able to understand the origin and the function of sleep with the electrophysiological techniques I had learned. Certainly, I could have continued to accomplish a number of descriptive studies in the area of sleep, but I felt as if that was like nibbling at the problem on the periphery.

St. Louis, Missouri

The opportunity to have a laboratory of my own and investigate problems of interest to me presented itself quite unexpectedly when I met Rita Levi-Montalcini in Rome. She had recently discovered the nerve growth factor, a discovery that made her famous and earned her the Nobel Prize. When I met her she had an active laboratory at Washington University that included a fully equipped neurophysiology set up. She needed somebody to run it, and when she offered me the position of research associate, a laboratory with technical assistant and start-up funds to carry on my research, I instantly and happily accepted her offer. The prospect to visit and work in the United States and to get to know and interact with the vast U.S. research community was very appealing and played a role in my decision to leave the Italian academic community. By the middle of July 1963, I was in St. Louis, Missouri, getting acquainted with the new world.

St. Louis had been an important center for brain science. Erlanger and Gasser, who had earned the Nobel Prize for neural transmission were emeriti professors, but still active members of the community, and so were O’Leary and Bishop. On the main campus, the neuroembryologist Victor Hamburger was an intellectual force and, naturally, Rita Levi-Montalcini with whom I established a lasting friendship, was the star of Washington University. The importance of the nerve growth factor was already widely recognized, and there were many demands on her time from all the corners of the world. I did not join her group but pursued a theme that was related to my previous work on PGO waves. I wanted to establish that the visual pathways, at the level of the cells of the lateral geniculate, received an extraretinal input during the slow potentials of REM. Not surprisingly, I found that the geniculate cells were activated when the animal in complete darkness went though the REM phase of sleep. I quickly described these findings in a paper for the Journal of Neurophysiology. This paper has the unique distinction to be the only paper I ever had accepted without any revision.

Toward the end of my year in St.Louis, I considered yet another move to a larger and more active scientific community. I also felt that I needed additional training. After visiting various east coast laboratories I opted for a stage at the NIH with Ed Evarts.

The Years at the NIH

There is no question in my mind that Ed Evarts, the Director of the section on motor control of the National Institute of Mental Health, was an outstanding scientist. His approach to the study of the way in which the CNS generates voluntary movements has had a lasting influence on the field of motor control. His style of research and the methods that he invented have been adopted by large number of investigators in the United States and abroad. But if Ed Evarts the scientist was unquestionably admirable, the man was something else: difficult, cold, and to a certain extent, mean spirited. To this day, when Tom Thach, Peter Strick, Mahlon DeLong (all of them have been postdoctoral fellows in Ed’s lab), and I get together at meetings, we rehash memories of humiliation and fears.

When I entered Ed’s lab in the summer of 1964, I had a simple plan; I wanted to learn his methods and his approach to motor control. After all, this is why I had left first Pisa and then St. Louis. I needed to find new research avenues because sleep research was no longer my choice. At our first meeting, I naively told him, “I am here to work with you”; Ed’s facial expression left no doubt in my mind that I had made a gigantic faux pas. After a long silent moment, and without answering my question, he told me that I was going to be on my own and that I should tell him what kind of project I wanted to do. After a somewhat painful discussion—many of the projects I was mentioning were scornfully rejected—he agreed that I could explore the idea that the REM slow potentials in the lateral geniculate could represent massive presynaptic depolarization of the optic tract terminals. He expressed skepticism about the viability of my project but reluctantly gave me his O.K. Although this was not the outcome I had hoped for, I was not unhappy with the presynaptic project; it was, after all, my idea and presynaptic inhibition was a hot topic at that time. In addition, there were no experiments showing that presynaptic inhibition was working in vivo in a behavioral context.

I started experimentation immediately in the miniscule, underground cubicle I was going to occupy for the next 2 years. For the first 3 to 4 months I had no results, and as time went by, I was spending more and more frantic hours in the cubicle but to no avail. Each time I emerged from underground I was aware of Ed’s glare, indicating that my reputation was crumbling. Finally, the dreaded moment came; Ed told me that I should end the unproductive project right away. I pleaded for more time and, surprisingly, he agreed: “One more month and that’s it,” he said.

My pleading was not a desperate attempt at prolonging what so far had been a failure but was based on my reading a recent paper that described a novel way to test for presynaptic inhibition. After the dreadful conversation with Ed, I implemented the new approach and got clear evidence for depolarization of optic tract terminals during the slow potentials of REM sleep. This observation was important because it decreases the retinal influence on the visual pathways during REM sleep while the neural signals from the pons reach the visual cortex via the lateral geniculate body.

In the following days I repeated the experiments a number of times, and when I finally became convinced that the result was real, I asked to see Ed. His response left me deeply disappointed and angry—he simply did not believe the results. He asked for a series of controls and without additional words ended our meeting. In the following days I started to look around the Washington area for another laboratory. Then something totally unexpected happened. One morning I arrived in the laboratory late and to my great surprise I noticed a smiling and welcoming Ed waiting for me. He told me that he had just read that Japanese investigators had achieved results essentially similar to mine. In a normal environment such an event would be considered almost a disaster—being scooped is one of the fears of scientists. In this case I jumped for joy because not only had I gotten external confirmation of my results, but this event transformed Ed’s attitude toward me. From that time on I was a kind of hero, I could do no wrong, and my opinions were considered with interest and respect. To understand what Ed’s volte-face meant to me, one should consider that the position of postdoctoral fellow is very precarious. Lack of support from the head of the laboratory may spell doom for the fellow’s career, and a foreign postdoctoral fellow is even more vulnerable.

After the completion of the presynaptic work, I was finally allowed to utilize Ed’s technique of single neuronal recording in behaving monkeys. I recorded from the cortical motor area controlling the eyes—the so-called frontal eye field that is located in the frontal lobe along the arcuate sulcus. Technically this experiment turned out to be easy, and in a short amount of time I was able to provide, for the first time, a description of the pattern of discharge of cortical cells during saccadic and smooth pursuit eye movements.

Recording from the frontal eye fields revealed a number of unexpected results. Unlike the cells of the classical motor cortex (area 4), most of the eye-related cells discharged during or after the saccades. Only a few seemed to be active prior to an eye moment. These observations suggested different functional properties between these two motor areas.

The recordings from the frontal eye field ended during the summer of 1966. At that point I was ready to be on my own. During the years in Pisa, St. Louis, and Bethesda I had gained technical knowledge with instrumentation and the surgical skill necessary to conduct animal experimentation. I also had a clear idea of what I wanted to do in neuroscience. My problem was to find a suitable environment to pursue an academic career. It was also clear to me that I wanted to be at a university rather than a scientist in a government laboratory such as the NIH.

The opportunity to obtain a university position arose when I met Hans Lukas Teuber. Teuber, an outstanding neuropsychologist who had been appointed in 1964 as chair of the MIT Department of Psychology, was known for the excellent appointments he had made. The faculty he had hired reflected his goal to establish a neuroscience group rather than a traditional psychology department. Because behavioral neurophysiology was going to be the central core of his department, Teuber was keen on importing the recording techniques Evarts had developed. And when he asked Evarts if he knew of anybody willing to move to Boston, Evarts mentioned my availability and I got an offer that I could not refuse.

The Years at MIT

I was thrilled to be at MIT. The department was a lively place; in addition to Teuber, the leading investigators were Walle Nauta, Richard Held, and Jerry Fodor. But brain science was also well represented in other departments and centers. For instance, in biology Jerry Lettvin, Pat Wall, and W. McCulloch were extraordinary scientists, colorful, irreverent personalities, always ready to engage in vigorous discussions and great fun to be with.

Motor Coordination

During my first year, in collaboration with Peter Schiller, we recorded from the monkeys’ frontal eye field neurons during the coordinated movements of eyes and head. In the following years I became more and more interested in the way in which the CNS succeeds in coordinating the movements of different body parts.

I thought that the coordination between the eyes and the head was a good way to begin. The head, a big mass relative to the eyes, is controlled by a large number of muscles and moves with a relatively slow velocity compared with that of the eyes.

Eye–Head Coordination

In foveate and unfoveate species, the most common response to target presentation is the coactivation of eye and head muscles. To direct the eyes and head toward a target and then fixate it with the fovea, an animal must solve three problems. First, it must compute the angular distance between its foveal lines of sight and the target. The absolute magnitude of this distance, called “retinal error,” will determine to a first approximation the amplitude of the saccadic eye movement that will be produced. Second, the animal must initiate a head movement that will be compatible in amplitude with the saccadic eye movement. Third, because the eyes usually move first and with higher velocity than the head, their lines of sight will reach and fixate the target while the head is still moving; to maintain fixation on the target, the animal must make a rotational eye movement counter and proportional to the movement of the head. This maneuver, which keeps the fovea constantly on the target, is called a “compensatory eye movement.” I will consider these problems separately.

Saccades During Head Movement

Because the head may begin to move before, at the same time, or a few seconds after the eyes move, saccades often take place while the head is moving. The data we collected indicated that the animal fixated the target with the same precision with and without head movement. However, the saccadic eye movements during unrestricted head movements were decreased in amplitude, duration, and peak velocity.

This finding that I published in Science in 1971 (in collaboration with R. Kalil and V. Tagliasco) raised the question whether the decrease in saccade amplitude, duration, and peak velocity during head turning was the result of an adjustment of the central oculomotor program caused by head movement. We found that the central mechanisms responsible for programming saccades takes account only of target position and that no information is transmitted from a head programming mechanism to the oculomotor system. Hence, the decrease in saccade amplitude, duration, and peak velocity must be mediated by reflex activity originating from structures excited by head turning: the vestibular apparatus and neck proprioceptors.

In the monkey, vestibular afferent signals are responsible for modulating saccadic eye movement. I demonstrated the crucial role of these signals by surgically interrupting the pathway linking the vestibular receptors to the vestibular nuclei. For several weeks after the operation (before the monkey had learned to compensate for the loss of vestibular input), saccades made with and without head movement were identical in amplitude. During head turning, the unmodulated eye movement was simply added to the head movement and the gaze overshot the target (work in collaboration with J. Dichgans).

The reflex mechanism is clearly more advantageous to the animal than a central mechanism for modifying saccades. Because the vestibular system automatically nullifies any displacement of the fovea from the target as a result of head movement, the motor programming systems responsible for eye–head coordination can program eye and head movements independently. Because the vestibular reflexes monitor the actual movement of the head, they can adjust saccadic eye movements to compensate for any unpredicted peripheral load or resistance that changes the course of a centrally initiated, intentional head movement.

Compensatory Eye Movements

The modification of saccades is only one aspect of the interaction between central oculomotor programming and reflex activities generated by head turning. Although this interaction plays a decisive part in the process of target acquisition, feedback from peripheral sensory organs also plays a role in the control and generation of compensatory eye movements. These movements by being counter to head motion, but of equal amplitude and velocity, keep the eyes on the target during head turning. Such movements have been observed in every species that has moving eyes. Compensatory eye movements are critically influenced by input from vestibular, and only minor effects derive from visual receptors and neck proprioceptors.

Head Movement

In collaboration with Morasso and Tagliasco, I showed that the events that follow the sudden and unexpected appearance of a target in the visual field occur in the following order: the saccadic eye movement begins first, and then, after 20 to 30 milliseconds, the head begins to move in the same direction. The electromyographic (EMG) records show, however, that the eye muscles begin to contract 20 milliseconds after the neck muscles are activated. The overt sequence of eye and head movements thus does not reflect the order of neural commands.

Simultaneous recordings from several neck muscles during horizontal head rotation have shown that all of the neck agonists are activated synchronously. Concurrently activity is suppressed in all of the antagonists. The agonist muscles are synchronously activated regardless of initial head position; however, the amplitude and duration of initial bursts of neck muscle activity are related to the starting position and amplitude of the head movement.

In the simple case in which the monkey’s eyes are centered in the orbit and triggered head movement begins from the straight-ahead position, there is a consistent relationship between the magnitude of the target displacement and the amplitude and velocity of the head movement. This relationship is qualitatively very much like that between target displacement and saccadic movements of the eyes.

In general there is no fixed relation between retinal error and the amplitude of the head response. Thus for head movements to be coordinated with eye movements, the system controlling head movement must have constant access to information about the position of the eyes in their orbits. This information could be supplied by eye proprioceptors or by oculomotor collaterals. Indeed eye muscle afference has already been described. Furthermore there is evidence suggesting that the position of the eyes in their orbits is coded by corticofugal neurons in the frontal eye fields, and a population of brain stem cells that encode eye position has been found.

Schematic Outline of Eye–Head Coordination

In the very simple case in which a single target light is flashed in the visual field of a monkey looking straight ahead, the eye–head sequence begins with the detection of the target. Motor programs involving the head and eyes are activated and send impulses to eye and neck muscles. These impulses produce saccadic eye movement and a head movement that activates vestibular receptors. Signals from these receptors modify saccadic duration and velocity and generate a compensatory eye movement that allows the fovea to remain fixed in relation to a point in visual space during head rotation. The fixation permits a second visual sampling, then a third, and so on, with opportunities for correcting errors at each sampling. This closed-loop scheme makes it clear that the role of the central motor program in eye–head coordination is simply to initiate eye and head movements. Because there is no central programming of saccadic adjustment or compensatory eye movement, the functional, or behavioral, coordination of head and eye movements depends on the modification of centrally initiated movements by signals triggered by receptors in the vestibule of the inner ear. This conclusion simplifies our view of the neural mechanism underlying motor coordination insofar as, contrary to common assumptions, there is no need to postulate a special population of “executive” neurons with exclusive responsibility for coordinating eye and head movements. Coordination is an emergent property of the CNS.

Eye–Head Coordination During Smooth Pursuit

Human beings, monkeys, and cats use a combination of eye and head movements to track a moving visual stimulus. These two kinds of movements are coordinated through the integration of centrally generated commands to the motor systems of the eye and the head with afferent activity originating from visual and vestibular receptors and neck proprioceptors. In experiments with J. Lanman and J. Allum, I found that the gaze (the sum of eye and head movements) remained on a moving target just as accurately when the head was free as it did when the head was fixed. The eye movements, however, differed greatly in the two conditions. With the head free, the eyes remained fairly stationary in the center of the orbit, and smooth pursuit was accomplished almost entirely by the head movement system. To investigate the mechanism for coordinating eye and head movements during smooth pursuit, I used a brake to suddenly and unexpectedly arrest head movements during tracking. The eye movement accelerated within 15 milliseconds after the brake was applied. This acceleration was so fast and so accurate that the gaze continued almost uninflected, with no detectable change in retinal error. Acceleration of eye movements must be caused by the release of a signal representing target velocity in space or gaze velocity from the opposing action of vestibular input, because the latency of the visual loop is too long and the neck afferents are too slow (70 to 80 milliseconds) and has a very low gain in monkeys. Presumably this signal drives the circuits of eye and head movement. During normal smooth pursuit with the head free, the head must follow this command with a lag that depends on the activation time of the neck musculature and on the amount of prediction involved in the pursuit strategy. The eyes, however, appear to receive not only the postulated smooth pursuit signal but also a signal generated by the activation of the vestibular system. This latter signal specifies movements counter and proportional to the head movement. The combination of the two signals in some part of the oculomotor system results in an eye movement with an amplitude nearly equal to the difference in amplitude between the target and head movements. This difference is small, so smooth pursuit with eyes and head consists mainly of head tracking.

Little is known about the derivation of the postulated signal representing target velocity in space or gaze velocity. Visual information certainly plays an important role in generating it, a role recognized by the many investigators who have considered a retinal-slip servo model for smooth pursuit. There is, however, a growing body of information suggesting that retinal slip is only one of several inputs driving eye movements during smooth pursuit.

Possible single cell correlates to the postulated central representation of target velocity or gaze velocity have been found. Miles and Fuller recorded from Purkinje cells in the monkey flocculus during smooth pursuit and found cells that fired at a rate proportional to the target’s velocity in space whether or not the head was moving. Because the gaze is very nearly on target during smooth pursuit, these cells may encode either target velocity in space or gaze velocity. These physiological findings are complemented by the results of lesions and psychophysical investigations. On the basis of one such study, my colleague, Larry Young, recently proposed that a central process, identified as “perceived target velocity,” is the stimulus for smooth pursuit.

Plastic Changes in Central Organization of Eye–Head Coordination

In collaboration with J. Dichgans, I have shown that bilateral elimination of the vestibular apparatus in monkeys and humans profoundly disturbs eye–head coordination. For the first few days after surgery, the animals attempt to bring the fovea to the target and maintain fixation in several ways: by delaying initiation of the head movement, by relying almost exclusively on head movement, or by greatly reducing the velocity of head movement. Although these patterns are present for only a short time, they show that there is great flexibility in the programming of eye and head movements.

The process of recovery is already evident at the end of the first postoperative week, and in monkeys ocular compensation equivalent to abut 50% of the amplitude of the head movement is present by the 10th day. Ordinarily ocular stabilization continues to improve until it reaches 90% of the normal value at the end of the first month.

Several compensatory mechanisms that stabilize the eyes during head movement in humans and monkeys account for this impressive recovery. One of the most important is the potentiation of the cervico-ocular reflex. In humans and normal monkeys, the cervico-ocular reflex contributes little to ocular stabilization because the vestibuloocular reflex ensures gaze stability during rapid head movements. In chronically labyrinthectomized monkeys and humans, however, the gain of the cervico-ocular reflex during passive head movement increases to about 0.3. A phasic enhancement of this loop during active head turning has also been observed. In patients with bilateral loss of vestibular function, the gain of the cervico-ocular reflex is also significantly enhanced.

Centrally programmed compensatory eye movements have also been found to contribute to ocular stabilization during active head turning in vestibulectomized monkeys. In vestibulectomized monkeys, though, the oculomotor system is capable of taking over (albeit in a crude and incomplete way) functions previously elicited by afferent vestibular activity. I have shown that this eye movement persists after cervical deafferentation and is thus not due to feedback from any remaining peripheral afferents, such as joint afferents. It therefore represents a new functional property of the central oculomotor system.

We have shown that the central oculomotor mechanism responsible for compensatory eye movements acts according to information transmitted from the head programming center. It follows that recovery of ocular stability in vestibulectomized monkeys entails not only a reorganization of motor function—the generation of compensatory eye movements—but also the development of functional connections between motor centers (head and eye) that are ordinarily functionally independent. Humans with defective labyrinthine systems in whom head movement was stopped during gaze changes also showed evidence of central programming of compensatory slow movements.

The third compensatory mechanism in chronically vestibulectomized monkeys involves a recalibration of saccadic eye movements with respect to retinal error signals. We found that the amplitude of saccades with the head free was significantly decreased in such monkeys. This mechanism is useful in preventing gaze overshoot and compensating for inadequate compensatory slow movement. In humans and monkeys, the saccades fell short of the target when the head was unexpectedly blocked but were accurate (in the same subjects) when the head was persistently immobilized.

In conclusion the studies in monkeys and humans have shown that the recovery of ocular stability is a complex process entailing parallel development of functional properties along three different lines: the potentiation of the cervico-ocular reflex, the central programming of compensatory eye movements, and the recalibration of the relationship between retinal error signals and the amplitude of the saccade.

The Control of Limb Posture

In parallel with the study of the eye–head coordination, I investigated the mechanisms related to the termination of a voluntary movement and the acquisition of a stable posture. As a model system, Polit and I selected the movements of the head and the arm of the monkey. To gain some understanding of the actual processes underlying posture we disturbed centrally initiated head movements by applying loads; our goal was to observe the effect of the resulting proprioceptive response on the final position of the head. When we applied a constant torque load whose effect extended beyond the dynamic phase, we observed a constant degree of head undershoot. Although the constant load was being applied, there was an increase in muscle spindle discharge, indicated by an increase in EMG activity. Presumably, tendon organ activity also increased, and there was a modification of postural information from joint receptors. However, in spite of these changes in the flow of proprioceptive activity, the head reached its “intended” final position after the constant load was removed. This final head position was equal to (on average) that reached when the load had not been applied, suggesting that the program for final position was maintained during load application and was not readjusted by proprioceptive signals acting at segmental and suprasegmental levels. We concluded that the central program establishing final head position is not dependent on a readout of proprioceptive afferents generated during the movement but is preprogrammed.

To test this hypothesis further, we investigated the way in which our monkeys reached final head position when they were deprived of neck proprioceptive feedback in addition to visual feedback. The goal here was to observe how monkeys moving their heads in an “open-loop” mode dealt with a constant torque applied during centrally initiated movements. We showed that following the unexpected application of a constant torque load at the beginning of a visually triggered movement, the head attained a posture short of its intended final position. Again, the position that the head attained after removal of the constant torque was found to be statistically equal to the position that the head reached when the load was not applied. These results indicate that the behavior of the motor system with respect to head posture is the same before and after deafferentation.

The result of this series of experiments contributes to our understanding of the mechanism whereby movement is terminated and a newly acquired position is maintained. If we assume that the “program” for head movements and posture specifies a given level of alpha motoneuron activity to agonist and antagonist muscles, and that the firing of these neurons will determine a particular length–tension curve in each muscle, then we must conclude that the final resting position of the head is determined by the length–tension properties of all of the muscles involved. This hypothesis explains the head undershoot when a constant load is applied and the attainment of the intended final head position following the removal of the load. Although the process of selecting a new equilibrium between the length–tension properties of agonists and antagonists should result in movement and the attainment of a new head position, it should be clear that our experiments did not rule out the presence of other parallel processes.

In a complementary set of experiments involving arm movement, we extended the previously described findings on the final position of the head. Adult rhesus monkeys were trained to point to a target light with the forearm and to hold the arm in that position for about 1 second to obtain a reward. The monkey was seated in a primate chair and its forearm was fastened to an apparatus that permitted flexion and extension of the forearm about the elbow in the horizontal plane. A torque motor in series with the shaft of this apparatus was used to load the arm. The experiments were conducted in a dark room to minimize visual cues; at no time during an experiment was the animal able to see its forearm. At random times, we displaced the initial position of the forearm. In most cases, the positional disturbance was applied immediately after the appearance of the target light and was stopped just prior to the activation of the motor units in the agonist muscle. Hence, when the motor command specifying a given forearm movement occurred, the positional disturbance had altered the length of the agonist and antagonist muscles, and the proprioceptive stimulation resulting from this disturbance had altered their state of activation. In spite of these changes, the intended final arm position was always reached; this was true whether the torque motor had displaced the forearm further away from, closer to, or even beyond the intended final position. To evaluate the proprioceptive reflex activity we retested the monkey’s pointing performance after it had undergone a bilateral C1-T3 dorsal rhizotomy. Remarkably, we could elicit the pointing response very soon after the surgery (within 2 days in some of the animals). The forearm was again displaced (at random times) immediately after the appearance of the target light and released just prior to the activation of motor units in the agonist muscles. Because the arm was not visible to the animal and the proprioceptive activity could not reach the spinal cord, the arm reached its intended final position “open loop.” The fact that we never observed any sign of reflex response or reprogramming in the EMG activity corroborates this supposition. We found that the final arm position was reached even when the initial position was displaced. This finding suggests that what is programmed is an intended equilibrium point, resulting from the interaction of agonist and antagonist muscles.

Although we had detected a process underlying arm and head movement, we were aware that there were other processes that occurred during the movement. It is quite clear, for instance, that the head (or arm) movements that monkeys use to reach a given position can vary in velocity. Consequently, the mechanism by which an intended posture is achieved must coexist with a mechanism specifying intended head (or arm) velocity. Second, the successful execution of the hypothesized “programs” in the deafferented animal is contingent upon the animal’s knowing the position of the arm relative to the body. Whenever we changed the usual spatial relationship between the animal and the arm apparatus, the monkey’s pointing response to the target was inaccurate. The dramatic inability of the deafferented monkey to execute accurate pointing responses in an unusual postural setting underscores the great importance of afferent feedback in the control of movement.

Trajectory Formation: The Equilibrium Point Hypothesis

The observation that posture is maintained by the equilibrium between the length–tension properties of opposing muscles led to the idea that movements result from a shift of the equilibrium point caused by a change in neural input. Around 1980 investigators of motor control had become increasingly aware of the computational complexities in the production of muscle forces. Some proposed that the CNS derives a motion of the joints from the desired path of the end point (inverse kinematics) and that it then derives the forces to be delivered to the muscles (inverse dynamics). The idea that the CNS performs these inverse computations implies that it can somehow estimate precisely limb inertias, center of mass, and the moment arm of muscles. Small errors in the estimation of these parameters can result in inappropriate movements. Robotic experience with similar approaches has shown that inertial parameter errors as small as 5% can result in instability. Most motor control investigations regard this type of computation as rather unrealistic. As an alternative, we and others proposed a different solution to the inverse dynamics problem: the equilibrium-point hypothesis.

The equilibrium-point hypothesis was first proposed by Feldman (1966), who viewed joint posture as an equilibrium resulting from the length-dependent forces generated by agonist–antagonist muscles. A key feature of the equilibrium-point hypothesis is that muscles have spring-like behavior. Experimental evidence has indicated that muscles behave like tunable springs in the sense that the force they generate is a function of their length and neural activation level. The force–length relationship of individual muscle fibers was studied by Gordon and his colleagues, who related the development of tension at different muscle lengths to the degree of overlap between actin and myosin filaments. This overlap limits the formation of cross-bridges. The increase in muscular stiffness observed when the motoneuronal drive increases is considered a direct consequence of the generation of new cross-bridges.

A central postulate of the equilibrium-point hypothesis is that the CNS generates a temporal sequence of signals that specify, at all times, an equilibrium position of a limb and the stiffness of the muscles acting on the limb. Although the terminology of the equilibrium-point hypothesis is firmly rooted in the literature, the term equilibrium position was a source of some confusion. We used the term in the following sense: It is the location at which the limb would rest if the centrally generated commands were “frozen” at any given value and the limb were free to move in the absence of external loads or forces. In the presence of static external loads or forces, the actual equilibrium position of the limb, will in general differ from this position. We introduced the term virtual position to distinguish the two. A time sequence of central commands gives rise to a time sequence of virtual positions, which is called a “virtual trajectory.” Evidence supporting this important hypothesis has been provided by three sets of experiments, which I will briefly summarize here (Bizzi et al., 1984). The movements used in these experiments were single-joint elbow flexion and extension, which lasted approximately 700 milliseconds for a 60-degree amplitude.

The first set of experiments was performed in intact monkeys and in those deprived of sensory feedback. The monkey’s arm was briefly held in its initial position after a target that indicated final position had been presented. Then, the arm was released. It was found that movements to the target were faster than control movements performed in the absence of a holding action. It was found that the initial acceleration after release of the forearm increased gradually with the duration of the holding period, reaching a steady-state value no sooner than 400 milliseconds after muscles’ activation. These results demonstrated that the CNS has programmed a slow, gradual shift of the equilibrium position instead of a sudden, discontinuous transition to the final position.

The same conclusions were supported by a second set of experiments in which the forearm was forced to a target position through an assisting torque pulse applied at the beginning of a visually triggered forearm movement. The goal of this experiment was to move the limb ahead of the equilibrium position with an externally imposed displacement in the direction of the target. It was found that the forearm, after being forced by the assisting pulse to the target position, returned to a point between the initial and the final position before moving to end point.

This return motion was caused by a restoring force generated by the elastic muscle properties. Note that if muscles merely generated force or if the elastic properties were negligible, we would not have seen the return motion of the limb. Because the same response to our torque pulse was also observed in monkeys deprived of sensory feedback, it was inferred that proprioceptive reflexes are not essential to the generation of restoring forces. Taken together, these results suggest that alpha motoneuronal activity specifies a series of equilibrium positions throughout the movement.

Finally, in a third set of experiments, the arm was not only driven to the target location, but also held there for a variable amount of time (1 to 3 seconds) after which the target light at the new position was activated. A cover prevented the animal from seeing its arm. After the monkey reacted to the presentation of the light, it activated the arm muscles to reach the target position. At this point, the servo that held the arm was deactivated.

The results were as follows. The arm returned to a point intermediate between the initial and the target positions before moving back to the target position. Note that during the return movement, requiring extension, flexor activity was evident. The amplitude of the return movement was a function of the duration of the holding action. If enough time elapsed between activation of the target light and deactivation of the servo, the arm remained in the target position upon release.

These observations provided further support for the view that motoneuronal activity specifies a series of equilibrium positions throughout a movement. If the muscles merely generated force during the transient phase of a movement, we would not have seen the pronounced return motion of the limb during flexor muscle activity.

The sequence of static equilibrium positions encoded during movement by the motoneuronal activity has been labeled a “virtual trajectory,” to be distinguished from the actual trajectory followed by the limb (Hogan, 1984). The virtual trajectory is based on length–tension relationships under static conditions. By contrast, the actual trajectory is the observable result of the interaction between the elastic forces and other dynamic components such as limb inertia, muscle velocity–tension properties, and joint viscosity.

Because the biological actuators are springlike, the inverse-dynamics problem does not need to be solved. In fact, according to the equilibriumpoint hypothesis, the CNS can express the desired trajectory of a limb directly as a sequence of equilibrium positions. Then the muscles’ springlike properties transform the difference between the actual and the desired position of the limb into a springlike restoring force. The actual motions that result are inexact but are produced without computing any dynamics. Consequently, there is no need to postulate neural structures to perform these complex computations.

Of course, the equilibrium-point hypothesis does not eliminate all computational problems; a pattern of neural activity may define a virtual trajectory, but there remains the formidable problem of how to select an appropriate pattern of neural activation to produce a desired virtual trajectory. Nevertheless, because it is based only on the static characteristics of muscles and their reflex connections and requires no knowledge of the dynamic parameters of the limbs (e.g., the inertias), this problem is significantly simpler than the direct computation of muscle forces or joint torques.

One major weakness of the equilibrium-point hypothesis is that it is difficult to test. The central concept is that posture and movement are subserved by the same processes. Static stability is arguably one of the defining requirements of posture; consequently, the equilibrium-point hypothesis makes the assumption that during movement as well as posture the limbs exhibit stability. Note that this is not a requirement for the motion of a mechanical system. Nor is it a fundamental requirement for a biological system, although it is physiologically plausible given the known springlike behavior of muscles and their reflex connections.

The theory that motor intentions are expressed and transmitted to the periphery using the virtual trajectory has direct implications for studies of cell discharge in the brain. The important point is that according to the theory, neither the forces generated by the muscles nor the actual motions of the limbs are explicitly computed; they arise from the interplay between the virtual trajectory and the neuromuscular mechanics. Hence, neither the forces nor the motions need be explicitly represented in the brain. If this theory is correct, then cell discharge studies might be better interpreted in terms of virtual trajectories and neuromuscular stiffness (or, more generally, impedance) than in terms of forces or motions.

Motor Learning, Generalization, and Consolidation

After investigating arm trajectory formation, I moved my research in the direction of motor learning. In collaboration with F. A. Mussa-Ivaldi and F. Gandolfo, I investigated how humans adapt to forces perturbing the motion of their arms. We found that as we adapt to the environment, the motor control system must learn to predict the perturbing forces that the limb will encounter so as to cancel them out while carrying out the desired movement. There are at least three ways for the motor control system to achieve adaptation. One is by representing the perturbing forces as a lookup table—that is, as a map that associates these forces to the states (positions and velocities) where perturbations have been experienced. An alternative is that the adaptation is not strictly limited to the visited states but to a small region around them. In this case, we would say that adaption is local to the visited states. A third hypothesis is that the pattern of forces experienced locally generalizes over the entire arm’s workspace. To find which alternative is most likely to be implemented by the motor control system, we investigated how subjects change their performance after prolonged exposure to a novel mechanical perturbation.

The protocol we used was designed by Reza Shadmehr and Mussa-Ivaldi when they were visiting my laboratory. Subjects were asked to execute arm movements toward visually specified targets. Once a baseline was established, force perturbations proportional to the movement velocity were applied to the subject’s hand. Initially, the trajectories were significantly distorted by the applied forces. But after a period of practice within this altered mechanical environment, subjects recovered the original performance to a remarkable degree. In addition, when the mechanical perturbations were removed, the resulting trajectories displayed a compensatory response, which was a mirror image of the perturbed trajectory. This compensatory response has been termed “aftereffect.” The presence of aftereffects is an indication that subjects adapted to the novel environment not by a generic strategy, such as by making their limb more rigid, but by generating end-point forces that exactly compensate for the applied perturbation.

Our experiments demonstrated that the motor control system builds a model of the environment as a map between the experienced somotosensory input and the output forces needed to counterbalance the external perturbations. Our results indicated that this map is local; it smoothly decays with distance from the perturbed locations.

Consolidation in Human Motor Memory

Learning a motor skill sets in motion neural processes that continue to evolve after practice has ended, a phenomenon known as “consolidation.” In collaboration with T. Brashers Krug and Reza Shadmehr, we showed that consolidation of a motor skill was disrupted when a second motor task was learned immediately after the first. There was no disruption if 4 hours elapsed between learning the two motor skills with consolidation occurring gradually over this period.

Previous studies in humans and other primates have found this timedependent disruption of consolidation only in explicit memory tasks, which rely on brain structures in the medial temporal lobe. Our results indicated that motor memories, which do not depend on the medial temporal lobe, can be transformed by a similar process of consolidation.

Neuronal Correlates of Motor Learning

In collaboration with R. Li and C. Padoa-Schioppa, we analyzed neuronal activity recorded in areas M₁, dorsal, ventral premotor, and supplementary motor areas in monkeys in a force field adaptation task. The animals adapted to a viscous force field imposed upon their visually guided reaching movements—the perturbations of the arm trajectories decreased and eventually disappeared as the monkeys adapted to these force fields. When the force field was removed, the movement trajectories curved in the direction opposite of that observed when the force field was first imposed. The existence of this afteraffect suggested that the animals develop an internal model of the force field. By recording from the motor areas of the frontal lobe we identified two classes of memory cells—these cells encoded the adaptation through a change in forcing rate and special turning properties.

Because we were able to maintain the contact between cells and the microelectrode only for a single session, our results are only relevant to shortterm learning.

The Problem of Controlling the Large Number of Degrees of Freedom of the Motor System

In the natural world, some complex systems are discrete combinatorial systems—they utilize a finite number of discrete elements to create larger structures. The genetic code, language, and perceptual phenomena are examples of systems in which discrete elements and a set of rules can generate a large number of meaningful entities that are quite distinct from those of their elements. A question of considerable importance is whether this fundamental characteristic of language and genetics is also a feature of other biological systems. In particular, whether the activity of the vertebrate motor system, with its impressive capacity to find original motor solutions to an infinite set of ever-changing circumstances, results from the combinations of discrete elements.

The ease with which we move hides the complexity inherent in the execution of even the simplest tasks. Even movements we make effortlessly, such as reaching for an object, involve the activation of many thousands of motor units in numerous muscles. Given this large number of degrees of freedom of the motor system we, as well as a number of investigators, have put forward the hypothesis that the CNS handles this large space with a hierarchical architecture based upon the utilization of discrete building blocks whose combinations result in the construction of a variety of different movements. In particular, investigators influenced by the artificial intelligence perspective on the control of complex systems have argued for a hierarchical decomposition with modules, or building blocks, as the most effective way to select a control signal from a large search space.

In the last few years, my colleagues and I have asked a specific question: Are there simple units that can be flexibly combined to accomplish a variety of motor tasks? We have addressed this fundamental and long-standing question in experiments that utilize spinalized frogs, freely moving frogs and rats. With an array of approaches such as microstimulation of the spinal cord, N-methyl-D-aspartate (NMDA) iontophoresis, and an examination of natural behaviors in intact and deafferented animals, we have provided evidence for a modular organization of the frog’s and rat’s spinal cord. A “module” is a functional unit in the spinal cord that generates a specific motor output by imposing a specific pattern of muscle activation. Such patterns, in which a group of muscles are activated in a fixed balance, have previously been considered as muscle “synergies.” Other investigators have generated corroborative evidence in cats. A clear-cut example of a recombination of synergies is from locomotion with the different limb central pattern guidelines (CPGs). Each CPG can operate independently, but the four-limb CPG can also be combined in different patterns as in a walk, a trot, or a gallop.

Recently, our laboratory has developed a novel method to identify muscle synergies with help of a computational analysis. This approach was first used by Tresch et al. (1999) who described the muscle activation patterns evoked from cutaneous stimulation of the hind limb in spinalized frogs.

The Construction of Movements with Muscle Synergies

For a long time, investigators have recognized that one of the basic questions in motor performance is whether the cortical motor areas control individual muscles or make use of synergistically linked group of muscles. Given that no natural movement involves just one muscle, any motor act, a fortiori, involves a “muscle synergy,” the question then has been whether the synergistic activation of muscles derives from a fixed common neural drive or is merely a phenomenological event of a given motor coordination.

Despite the history of this issue, the vast literature on this question indicates little consensus either for fixed synergies or for individual control of muscles.

Even though most investigators doubt the existence of fixed synergies, they are nevertheless reluctant to accept the idea that a separate control signal must be computed for each muscle to achieve the appropriate movement. Various alternative mechanisms have been suggested such as hierarchical control. According to these investigators there is a hierarchy of parameters or strategies that are controlled in any motor act. Once the strategy is chosen a coordinated pattern of muscle activity is selected, but the muscle groupings are not considered to be fixed—they are formed and reformed each time.

Summing up, there is little doubt that the issue of muscle synergies has remained unsettled. However, there is a reason for this predicament—the approaches that have been used to investigate this issue have been based on correlation methods, which in this case are less than ideal for settling the muscle synergy question. The recent introduction of novel computational procedures has opened a different way to approach the issue of synergies. In 1999, Tresch and collaborators developed a variety of essentially similar computational methods to extract synergies from the recorded muscle activations. In general, these methods try to decompose the observed muscle patterns as simultaneous combinations of a number of synergies. This decomposition is obtained using iterative algorithms that are initialized with a set of arbitrary synergies. The nonnegative weighting coefficients of these arbitrary synergies that best predict each response are then found. The synergies are then updated by minimizing the error between the observed response and the predicted response. This process is then iterated until the algorithm converges on a particular set of synergies. The algorithm extracts a set of synergies and the weighting coefficients of each synergy used to reconstruct the EMG responses.

Note that there are a number of factorization algorithms to assess the hypothesis that motor behavior might be produced through a combination of a small number of synergies. Tresch and his colleagues have compared different algorithms and found that, in general, most of the algorithms used to identify muscle synergies perform comparably. In particular, nonnegative matrix factorization, independent component analysis, and factor analysis performed at similar levels to one another.

In experiments we have evaluated this issue by examining several motor behaviors in intact, freely moving frogs. We recorded simultaneously from a large number of hindlimb muscles during locomotion, swimming, jumping and defensive reflexes (d’Avella and Bizzi, 2005; d’Avella et al., 2003), and we have shown that linear combinations of a small number of muscle synergies may be a strategy utilized by the CNS to generate diverse motor outputs. Furthermore, most of the synergies used for generating locomotor behaviors are centrally organized, but their activations might be modulated by sensory feedback so that the final motor outputs can be adapted to the external environment. Such an organization might help to simplify the production of movements by reducing the degrees of freedom that need to be specified by providing a set of units involved in regulating features common to a range of behaviours

Conclusions

I have been lucky in my career. It was a privilege to have met in my formative years outstanding scientists like Moruzzi, Evarts, Rita Levi-Montalcini, and Hans Lukas Teuber. As I settled at MIT, I was fortunate to conduct my research in collaboration with a superb group of students, postdoctoral fellows, and colleagues. They vastly enriched the scope of my investigations on the motor system—whatever I accomplished would not have been possible without them.

Early on, my research was conducted predominantly through collaborations with postdoctoral fellows with degrees in electrical or mechanical engineering or computer science. Vincenzo Tagliasco, Pietro Morasso, both from the university of Genova, Italy, and Parvati Dev from the University of Massachusetts were all trained in bio-engineering and in my laboratory became involved in the study of motor coordination. As they left I started a long-lasting collaboration with Neville Hogan from the MIT Department of Mechanical Engineering. Aware of the risks of too much engineering and wishing a healthy balance between biology and the hard sciences I then invited Johannes Dichgans, a young German trained as a neurologist in Freiburg, to join my laboratory.

As I moved from the investigations of motor coordination to the study of the motor programs underlying arm trajectory formation, my collaborators were graduate students Andreas Polit, Doug Whittington, and Joe McIntyre, postdoctoral fellows William Chapple, Francis Lestienne, William Abend, Neri Accornero, and again my colleague Neville Hogan.

During the 1990s when I started to investigate the modular organization of the motor system, Sandro Mussa-Ivaldi, now a professor at Northwestern University, and Simon Gizster provided crucial input to the development of this project. Gerry Loeb and Philippe Saltiel joined the modularity theme later. Incidentally, we are still working on modularity, and I’d like here to acknowledge the contributions of Matt Tresch, Andrea d’Avella, Vincent Cheung, Simon Overduin, Andrew Richardson, and Jin-Sook Roh.

Next to modularity my current interest is motor learning. My involvement in investigating this topic began when Sandro Mussa-Ivaldi and Reza Shadmehr developed a way to evaluate quantitatively the acquisition and retention of a simple motor task in normal volunteers. This important study got everybody excited and spawned three new lines of research that are still being pursued in my laboratory. One theme began when Brasher-Krug and Reza Shadmehr investigated the time course of consolidation of motor memories in humans. This topic was then recently pursued by Simon Overduin who was able to specify critical behavioral features necessary for the establishment of consolidation. Working with patients affected by cortical strokes, Maureen Holden explored the power of augmented feedback using virtual environment to promote reprogramming of motor functions. In our second line of work we have focused on a description of the pattern of discharge of cortical neurons located in the primary motor, premotor, and supplementary motor areas of the monkey. Francesca Gandolfo and Brian Benda began this work that was then continued by Ray Li and Camillo Padoa-Schioppa and Andrew Richardson. The results of this extensive investigation of motor cortical areas revealed the presence of a population of cortical neurons that changed their firing rate during learning and then retained these changes afterward. On the basis of this outcome we felt we could label these cells as “memory neurons.” However, because current techniques did not allow us to record from the memory cells for more than a few hours, it remains to be seen whether this label may or may not apply. Other interpretations are possible as shown by Uri Rokni in a modeling study based on the cells we had recorded.

Although the collaborators I have just mentioned contributed in fundamental ways to the scientific productivity of my laboratory, I want also to gratefully mention that the indispensable financial resources came mostly from the NIH granting system, which provided my laboratory with more than 40 years of uninterrupted funding. Last but not least I want to acknowledge Margo Cantor, who for many years provided indispensable technical assistance in my laboratory, and Charlotte Potak, whose administrative expertise in the office and laboratory has been invaluable.

Finally, considering more than 40 years of research on the motor system, my own and that of others, I believe that the study of action systems has an exciting and a scientifically rewarding future. By now a lot of basic, sometimes pedestrian, but useful work has been done, and we have reached the point where the next generation of investigators might attack what I consider the major challenges in this area: generalization and motor learning.

To me the most wonderful and astonishing feature of the motor system is its capacity to learn a task in one context and perform it with competence in a variety of new situations. Understanding this problem is hard, no doubt, and we sorely need theoretical work to explore a variety of alternative experimental models. Of course the system that provides generalization has to retrieve the signals representing the task from circuits that have been changed by learning, but are inherently unstable as the recent data by Robert Ajemian seem to indicate. This question of synaptic instability is central to learning, consolidation, and retrieval. To investigate these problems, new theoretical models and probably new recording techniques that will permit long-term tracking of the behavior of neurons need to be developed. In addition, we should also explore whether knowledge of the genes that are involved in motor learning might generate new investigative tools. Hard to say, but one thing is certain. The next generation will need a good dose of optimism and luck to tackle these tough problems.

Selected Bibliography

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Bizzi E. Discharge of frontal eye field neurons during eye movements in awake monkeys. Science 1967;157:1588–1590.

Bizzi, E. The coordination of eye-head movements. Sci Amer 1974;231:100–106.

Bizzi E, Accornero N, Chapple W, and Hogan N. Posture control and trajectory formation during arm movement. J. Neurosci. 1984;4: 2738–2744.

Bizzi E, Brooks DC. Pontine reticular formation: relation to lateral geniculate nucleus during deep sleep. Science 1963;171:270–272.

Bizzi E, Giszter S, ad Mussa-Ivaldi FA. Computations underlying the execution of movement: a novel biological perspective. Science 1991;253:287–291.

Bizzi E, Hogan N, Mussa-Ivaldi FA, Giszter S. Does the nervous system use equilibrium-point control to guide single and multiple joint movements? Behav Brain Sci 1992;15:603–613.

Bizzi E, Kalil, RE, Tagliasco V. Eye-head coordination in monkeys: evidence for centrally patterned organization. Science 1971;173:452–454.

Bizzi E, Polit A, Morasso P. Mechanisms underlying achievement of final position. J Neurophysiol 1976;39:435–444.

Bizzi E, Pompeiano O, Somogyi I. Vestibular nuclei: activity of single neurons during natural sleep and wakefulness. Science 1964;145:414–415.

Bizzi E, Saltiel P, Tresch MC. Modular organization of motor behavior. Zeitschrift für Naturforschung 1998;53c:510–517.

Bizzi E, Tresch MC, Saltiel P, d’Avella A. New perspectives on spinal motor systems. Nat Rev Neurosci 2000;1:101–108.

Brashers-Krug T, Shadmehr R, Bizzi E. Consolidation in human motor learning. Nature 1996;382:252–255.

Cheung VCK, d’Avella A, Tresch MC, Bizzi E. Central and sensory contributions to the activation and organization of muscle synergies during natural motor behaviors. J Neurosci 2005;25:6419–6434.

d’Avella A, Bizzi E. Shared and specific muscle synergies in natural behaviors. Proc Natl Acad Sci USA 2005;102:3076–3081.

d’Avella A, Saltiel P, Bizzi E. Combinations of muscle synergies in the construction of a natural motor behavior. Nat Neurosci, 2003;6(3):300–308.

Gandolfo F, Mussa-Ivaldi FA, Bizzi E. Motor learning by field approximation. Proc Natl Acad Sci 1996;93:3843–3846.

Hogan N. An organizing principle for a class of voluntary movements. J Neurosci 1984;4:2745–2754.

Holden MK, Dettwiler A, Dyar T, Niemann G, Bizzi E. Retraining movement in patients with acquired brain injury using a virtual environment. In Wetwood JD et al., eds. Medicine meets virtual reality. IOS Press, 2001;192–198.

Li C-SR, Padoa Schioppa C, Bizzi E. Neuronal correlates of motor performance and motor learning in the primary motor cortex of monkeys adapting to an external force field. Neuron 2001;30:593–607.

Mussa-Ivaldi FA, Bizzi E. Motor learning through the combination of primitives. Phil Trans R Soc Lond B 2000;355:1755–1769.

Mussa-Ivaldi FA, Giszter SF, Bizzi E. Linear combinations of primitives in vertebrate motor control. Proc Natl Acad Sci 1994;91:7534–7538.

Overduin S, Richardson A, Bizzi E, Press D. Simultaneous sensorimotor adaptation and sequence learning. Exp Brain Res 2007;184(3):451–456.

Padoa-Schioppa C, Li C-S R, Bizzi E. Neuronal activity in the supplementary motor area of monkeys adapting to a new dynamic environment. J Neurophysiol 2004; 91:449–473.

Poggio T, Bizzi E., Learning and generalization in vision and motor control. Insight review article. Nature 2004;431:768–774.

Richardson A, Overduin S, Valero-Cabre A, Padoa-Schioppa C, Pascual-Leone A, Bizzi E, Press D. Disruption of primary motor cortex prior to learning impairs memory of movement dynamics. J Neurosci 2006;26(48):12466–12470.

Rokni U, Richardson AG, Bizzi E, Seung S. Motor learning with unstable neural representations. Neuron 2007;54(4):653–666.

Tresch MC, Saltiel P, and Bizzi E. The construction of movement by the spinal cord. Nature Neuroscience 1999;2: 162–167.

Marian Cleeves Diamond

BORN:

Glendale, California, USA

November 11, 1926

EDUCATION:

University of California at Berkeley, B.A. (1948), M.A. (1949), Ph.D. (1953)

University of Oslo, Norway, Certificate of Courses (1948)

APPOINTMENTS:

Research Assistant, Harvard University (1952–1953)

Instructor, Cornell University, (1955–1958)

Lecturer, University of California School of Medicine at San Francisco, (1958–1960)

Lecturer, University of California at Berkeley, (1960–1965)

Assistant Professor–Professor, University of California at Berkeley, (1965–)

Assistant Dean–Associate Dean of College of Letters and Science, University of California at Berkeley (1967–1972)

Director of Lawrence Hall of Science, University of California at Berkeley, (1990–1996)

Governor’s Board Rand Graduate School (1985–1996)

HONORS AND AWARDS (SELECTED):

Fellow, American Association for the Advancement of Science Fellow, California Academy of Sciences

Council for Advancement & Support of Education. Wash. D.C. award for California Professor of the Year and National Gold Medalist

California Biomedical Research Association Distinguished Service Award

Alumna of the Year—California Alumni Association

San Francisco Chronicle Hall of Fame

University Medal, La Universidad del Zulia, Maracaibo, Venezuela

Brazilian Gold Medal of Honor

Benjamin Ide Wheeler Service Award

The Distinguished Senior Woman Scholar in America awarded by the American Association of University Women

Major scientific contributions from Marian Diamond’s laboratory are threefold: One, the structural components of the cerebral cortex can be altered by either enriched or impoverished environments at any age, from prenatal to extremely old age. An enriched cortex shows greater learning capacity, an impoverished, the opposite. Two, the structural arrangement of the male and female cortices is significantly different and can be altered in the absence of sex steroid hormones. Three, the dorsal lateral frontal cerebral cortex is bilaterally deficient in the immune deficient mouse and can be reversed with thymic transplants. In humans, cognitive stimulation increases circulating CD4-positive T lymphocytes, supporting the idea that immunity can be voluntarily modulated.

Marian Cleeves Diamond

Growing up: What Constitutes an Enriched Environment?

I was born in Glendale, California, on November 11, Armistice Day, 1926, the youngest of six children. A large uterine tumor accompanied me during my growth process in my 42-year-old mother’s uterus. My 47-year-old father brought all my brothers and sisters to say good-bye to my mother because he was told the doctor could save one but not both. How wrong he was! My mother lived to be 75, and I am now 80.

Because most of my biological research efforts have dealt with the effects of the environment on the development of the anatomy of the brain, I thought it might be appropriate to describe the environment that played a role in developing my young postnatal brain during its most rapid growth period.

In the early 1920s the area north of Los Angeles appeared to be mostly sagebrush, buck wheat, and poison oak. The landscape extended through the narrow valley between the Sierra Madres to the north, rising to 5000 feet, and the Verdugo Hills to the south, but not quite as high. This southern California area was home to black widow spiders, rattlesnakes, and tarantulas. But it was also the home of dragonflies, scrub and stellar jays, humming birds, deer, opossums, coyotes, and rabbits. The air was pure and crystal clear, a delight to breathe; yet one took it for granted.

What attracted an Englishman from the green moors of Northern England to California’s dry climate? I will never know for certain, but I think he, as a physician, wanted to set up a sanitarium to cure those with respiratory problems. He saw so much suffering from the miners with lung disease acquired from working in the depths of the coal mines. Father was the only one of his large family to leave the comforts of his fine residence in England and make his home in the United States. There is no one left to ask why.

The home father carved out of the rugged brush and rocks in La Crescenta left little to be desired. First, he hired Mexican laborers to clear his 20 acres and make a stone wall completely surrounding his land, similar to the ones around the fields in Tasmania. He continued to take advantage of all the rocks of every conceivable size and shape to make his house. In front of the house he erected a rock pergola that was eventually covered with delicate, lavender wisteria, providing lunch for thousands of noisy honey bees. The rock terraces were later filled with roses for his formal garden and vegetables for the dinner table. The little rock-covered “study,” as we called it, where he wrote letters and conducted some of his medical practice, was separate from the house. Rock-lined paths led through the citrus trees to rock walls that supported the swimming pool where we spent most of our days with our friends during the hot southern California summer months. A rock semicircular alcove for sitting adjacent to the tennis court was surrounded by a low rock wall that supported a high wire fence. (Once a deer, trapped on the tennis court, dove against the wire fence with such force that she left a well-circumscribed hole.) We used the tennis court not only for learning to play tennis but for roller skating as well, often until dark.

Our orchard appeared blanketed with rocks. As my brother plowed between the trees, it seemed that all the tractor did was turn over rocks. But the soil beneath those rocks nourished every kind of fruit imaginable, such as, quince, plums—Santa Rosa and Green Gage—apricots, peaches, and nectarines. The orchard also provided black and white figs that Mother preserved or candied for our dinner table. Rows and rows of grape vines supplied plump, juicy red tokay grapes that made delightfully fresh gifts when placed on a grape-leaf, lined plate. (We used to deliver such a gift to Mrs. Beach, a Carter Ink heiress, who lived in the light pink, Italian villa across Briggs Avenue where we lived.) Father often experimented in making wine from the Concord grapes that grew over a rock wall. Blackberries flavored our favorite ice cream. Orange and lemon blossoms lent their fragrance to the whole ambience. Almond trees added their lovely delicate, white-pink blossoms in the spring, and walnuts stained our hands dark brown as we hulled them in autumn. (We ate Mother’s blanched almonds by the hand full while still warm.)

The almond trees were interspersed with carob trees. We had to pick the carob beans up off the ground after my father had knocked them down with a long stick. It seemed to us he had the easier job, as we stooped over the beans and our boxes. On the street side of the rock wall was the row of olive trees where people would come on Sunday afternoon and fill their buckets without permission. My father would send us out to ask them to leave.

Father fed the carobs we grew in our orchard to the goats, which he kept because he believed goat’s milk was healthier for children than was cow’s milk. Next to the goat shed was the chicken coop. He would stop by the side of the road on his way home from Los Angeles, where he practiced medicine, to pick mustard greens for the chickens to eat. My sister used a stick to keep the head of the chicken turned away from my arm, as I slid my hand under the hen to steal her egg. We raised Rhode Island reds, Plymouth rocks, black Manorcas, and white Leghorns. English walnut trees shaded the chicken yard below which was next to the horse stable with an adjacent house for the cooing pigeons. On warm summer afternoons we often climbed onto the roof of the horse stable to play in the shade of the over-hanging pepper tree.

Father also built us swings that sailed us up to view over the roof of the house, as well as a bar for going around and around 100 times on one knee, a see-saw, and a teeter-totter. Many a summer afternoon we picked pomegranates and ate them on the wall surrounding our property, covering our shorts, faces, legs and hands with the sweet, sticky, red juice.

Yes, my Episcopalian-raised father, Dr. Montague Cleeves, was a many talented man speaking several foreign languages, versatile with Shakespeare and the Bible and many other literary classics. He later left the Episcopal Church in favor of the Unitarian. At his memorial service in 1973, Reverend Stephen Fritchman from the First Unitarian Church in Los Angeles stated that “Today teachers and psychologists call such persons models. In my day, they were, in more elegant Tennysonian language, called exemplars.” “He was proud of his children, grandchildren, and great grandchildren, a gracious patriarch, a witty one, a keen-minded and loving patriarch indeed, far more so than some of the more celebrated ones found in the Old Testament or in Browning’s The Barretts of Wimpole Street.

To summarize all of this, down the long driveway in front of our home, Father posted a large sign, which was almost a public statement of why he left England to live in “Rock Crescenta,” SUNNYSLOPE: A PLACE IN THE SUN RESERVED FOR CHILDREN. I might add that this short description is only the tip of the iceberg of the kind of enrichment we enjoyed during the period of most rapid growth of our cerebral cortices.

Carol McLaughlin once asked when interviewing me for Women’s Forum West, “What kind of a child was I during this period?” I answered in two words: very independent. My father was an extremely strict, strong minded, yet kind, Englishman who frightened all my siblings but me. If they wanted something, I was elected to go to my father to ask permission. At an early age I learned not to be afraid of strong, dominant men. This characteristic served me well when I faced difficulties during my professional life.

It is important to point out that my father did not produce our enrichment and sculpting by himself. My Presbyterian-raised mother, Rosa Marian Wamphler Cleeves, carried a good deal of the domestic responsibilities. She was of Swiss parentage, though born in upstate New York. Her “education genes” must have been inherited from both parents, her father being a university professor in Bern and her mother a high school teacher in Interlocken, Switzerland. As a girl, she was trained to play the piano, not casually, but seriously, practicing nine hours a day. In high school and college she was a classics scholar, studying Greek and Latin for about 8 years. Later she taught Latin in Berkeley High School and in Vacaville north of Berkeley. At University of California at Berkeley (CAL) she enjoyed German literature, especially Goethe and Schiller when she could read their texts in German. At the university she worked with Monroe Deutsch, the Vice President, as she was accumulating data for her Ph.D. After she married my father, she left her home in Berkeley and her studies for her advanced degree to set up a new home to raise six children in the sagebrush of isolated La Crescenta. La Crescenta was rich with nature’s treasures, but was not, needless to say, a university town rich in academia, as was Berkeley. In her later life she regretted not having a profession and told me to work half-time while raising the children so that when they were gone, I could continue full-time with my professional interests.

Education

Being the youngest of six children, a good deal of informal education or enrichment came directly and indirectly from my five, bright, older siblings. All of us received our formal education in California public schools beginning in La Crescenta grammar school 2 miles down the hill from our home. Clark Junior High was not much farther, but Glendale High school was 7 miles away on the other side of the Verdugo Mountains. I remember most of my teachers, the good and the bad. Both provided useful learning experiences.

Then in one moment of time when I was about 15 years old, I saw my first human brain, while walking down the corridor at the Los Angeles County Hospital behind my father as he was visiting his patients. A door was slightly ajar, and in that room on a small table was a whole human brain with four men clothed in white coats standing around the table. I have no idea what they were doing, but the sight of that brain, which formerly had the potential to create ideas, was embedded in my brain forever, as clearly as if it were yesterday. The thought was mesmerizing that that brain represented the most complex mass of protoplasm on this earth and, perhaps, in our galaxy. Someday I knew an opportunity would arise for me to learn more about it. Now it was essential to continue my general education.

About the same time I had written an essay saying that when I grew up I would go to the CAL “because those who didn’t wish they did.” Though I had an appropriate academic record to go directly from high school to CAL, I chose to go to nearby Glendale Community College because I thought my parents would be depressed without some of the large family at home.

As I look back at my university education, I do appreciate several of the classes I took at the community college. Without such small classes with excellent qualified teachers, one a physician on a health leave, I might not have found my calling in anatomy, especially the esthetic side of anatomy including neurohistology with the varied structures highlighted with multicolored stains. A particular picture in Gray’s Anatomy of a beautiful profile of a head with the vascular system showing clearly was indeed attractive to me. I enjoyed the small classes in chemistry, physics, and math at Glendale College, some of them being taught by University of California at Los Angeles (UCLA) professors during the summer. (To confirm the level of my enjoyment, in my second year I became president of the student body.)

After 2 years, I was eager to attend CAL and soon majored in general biology, especially concentrating on vertebrate embryology and comparative anatomy. The first-year medical courses dealing with human material were in the same Life Sciences Building as my undergraduate biology courses. I could see the use of human material by the medical students but had no access to it, only to animals. I thought if I went to graduate school at CAL I could then study human material with the medical students. (But before graduate school I might mention that as an undergraduate, I played on the CAL women’s tennis team, earning my Big “C” at the same time I was president of my dorm, Stern Hall.)

Having graduated from CAL in June of 1948 at 21 years of age, I applied for a scholarship to attend a summer school program at the University of Oslo, Norway, established by the Norwegians to repay the Americans for their assistance during World War II. (My father could not understand why I had to go so far away from California.) I also needed to supplement my scholarship so I used the money I earned when I was 16 or 17 during summers while in high school working in the vineyards in 125-degree sunshine near Bakersfield, as a member of the Women’s Land Army during World War II. There were few men to pick the crops.

What a marvelous assortment of subjects we experienced in Oslo, including polar research, reconstruction of Norway, marine biology with field trips on the Oslo Fjord, interspersed with lectures by leading politicians and musical performances by talented Norwegians. Our trans-Atlantic ship, the Marine Jumper, a converted troop ship, provided the time and space to become acquainted with U.S. students attending other summer schools. By consensus, our Norwegian program was top of the list.

At the end of summer of 1948 I was excited, focused, and full of energy to enter graduate school in the Department of Anatomy at CAL and begin my studies of the nervous system. What a heterogeneous assortment of major professors assisted us. Herbert M. Evans and Miriam Simpson were leading histologists and endocrinologists; John B. de C.M. Saunders and William Reinhardt were the gross anatomists and Bill Garoutte and Bert Feinstein were the neuroanatomists. (Dr. Feinstein was the husband of our now U.S. Senator, Diane Feinstein.) I enrolled in the medical school courses in Neuroanatomy, Gross Anatomy, and Histology to gain the fundamentals of human anatomy, a subject that truly fascinated me. To earn my way through graduate school, I became a teaching assistant the year after I completed these courses with A grades.

How did I ever know I could teach! The first time a medical student asked me a question and I knew the answer, I felt a deep, warm glow of satisfaction radiate through my body. This is where I belong. That night I had time to recall that my Swiss grandmother, grandfather, and mother were teachers; I had possibly inherited their “teaching genes.” What a blessing to be at CAL studying the nervous system and enjoying imparting useful knowledge to eager medical students! I later discovered that having a life including teaching and research was extremely satisfying. Trying to achieve excellence in both was a difficult but desirable challenge.

Being the only woman graduate student in the department, the first “job” I was given was to sew a plastic cover for a huge, long, sliding, magnifying contraption. This I quickly did because I had learned from watching my older siblings wait for the right opportunity and sometimes they waited too long. I did “that which was present and not that which lay dimly in the distance” from Thomas Carlyle.

Because World War II had recently terminated in 1945, many of the young men were returning with missing limbs and suffering from referred pain and phantom limb sensations. A Professor Jameson asked if I would like to study referred pain induced by the injection of hypertonic saline into various muscle groups in the upper extremity and mapping the resulting pain patterns. Admittedly, this was a far cry from studying the human brain and its higher cognitive functions as I had envisioned upon coming to graduate school, but again I did that which was present. (No one was studying the anatomy of higher cognitive functions in those days.) I certainly learned a good deal about different resulting pain patterns as well as sensitivity to pain. This project culminated in my earning my master’s degree in anatomy in 1949.

Being in a department mainly interested in hormones, and again not in higher cerebral cortical functions, by now I had become fascinated with a part of the brain called the hypothalamus. How could 4 grams of nerve tissue carry out such diverse functions? For example, regulate body temperature, appetite and thirst, mating behavior, anterior pituitary hormones, form posterior pituitary hormones, sympathetic and parasympathetic functions, memory, and circadian rhythm. What an intriguing, complex little mass of tissue to study!

For my doctoral dissertation that was eventually titled “Functional Interrelationships of the Hypothalamus and the Neurohypophysis” (1953), I was interested in learning about the amount of antidiuretic hormone (ADH) in the supraoptic area of the hypothalamus and posterior pituitary after various experimental conditions including normal control rats, saline controls, hypophysectomy, posterior lobectomy, dehydration, hydration, adrenalectomy, adrenalcorticotrophic hormone (ACTH) treatment, and desoxycorticosterone acetate (DOCA) treatment.

From these experiments there are far too much data to present here, but a few examples can be offered. Histological and physiological measures using assay techniques were determined. From histological studies, Gomori positive substance demonstrating granules in the supraoptic nuclei was extremely sparse under any of the above conditions; yet large quantities were demonstrated in the normal posterior pituitary. With toluidin blue stain the Nissl substance in the neurons in the supraoptic nucleus of dehydrated rats was peripherally dispersed due to an increase in the size of the neuron. As might be expected, with hypophysectomy there was a decrease in the number of cells in the supraoptic nucleus. The amount of ADH left in the supraoptic area after posterior lobectomy was decreased in an amount comparable with that after complete hypophysectomy. The administration of a 5% NaCl solution reduced the antidiuretic activity in the hypothalamus and hypophysis.

Injection of DOCA and ACTH into normal animals did affect the ADH content of the hypothalamic-hypophyseal system. The evidence that ADH in the hypothalamus and neurohypophysis is not altered several days after adrenalectomy, and yet has been reported to increase in the circulatory system, supports the suggestion that there may be decreased destruction of the substance (by the liver) rather than increased production by the hypothalamichypophyseal system. These examples indicated that a good deal of information was gathered from these experiments, but it would take another lifetime to integrate them into a functional whole. That being said I now wish to continue with the personal side of my life that I was trying continuously to integrate with my biological interests.

While in graduate school, I first lived in an old house we called the “Ritz” close to the university with four other young ladies, Marian Melrose, Jean Cline, Florence Bevis, and Peggy Shedd, who lived with me in Stern Hall during our undergraduate days. I later moved to International House that as the name implies was a wonderful establishment for men and women from everywhere in the world who were mostly graduate students. It was here that I met a man, kind, extremely brilliant and well educated, in addition to being a very superb athlete. I loved sports, having grown up with two older brothers who were very adept with many kinds of sports. We all played tennis, skied, swam, dived, and hiked. Who is to say which I liked best. I know I liked them all as did Dick. Consequently taking many of Dick’s fine traits into consideration, on December 20, 1950, I married Richard Martin Diamond who received his Ph.D. in nuclear physics/chemistry at CAL under the direction of Professor Glen Seaborg. Dick’s first academic appointment was in the Chemistry Department at Harvard University where he taught for a year before I could join him.

Family

The greatest thrill in my life up to that moment was when I held my first newborn child in my arms against my breast. I knew why I existed. This experience was beyond any other I had ever contemplated and was repeated with each of my next three children. I loved being a new mom just as much as I presently love being an older grandmother or “muti,” as I like to be called.

Catherine Theresa Diamond was born May 6, 1953, in Boston, Massachusetts. At CAL, she majored in cross-cultural aesthetics, concentrating in Chinese and European art. After receiving a masters degree in creative writing, she wrote three works of fiction based in Asia. She obtained her doctorate in comparative drama at the University of Washington, and is currently a Professor of Theatre in Taipei, Taiwan. She has published extensively on the contemporary theater of Southeast Asia and is the director of an English-language troupe in Taipei, Phoenix Theater.

Richard Cleeves Diamond was born on October 10, 1955, in Ithaca, New York. He came into the world a month early, possibly because I was mowing the lawn on a nice Fall afternoon. He asked to play the violin when he was only 4 years old and began taking lessons when he was 6. He joined the Berkeley Symphony Orchestra in 1973 soon after it was established and is still playing there. He majored in visual and environmental studies as an undergraduate at Harvard, completed his Ph.D. in architecture at CAL in 1986, and enjoyed a postdoc at Princeton, before accepting a position as a staff scientist at the Lawrence Berkeley National Laboratory. His research at the lab presently is on energy, behavior, and buildings, when he is not looking after his 4-year-old twin sons, Aaron and Paul, with his wife, Alice Kaswan, a Professor of Law at the University of San Francisco.

Jeff Barja Diamond was born on March 20, 1958, in Ithaca, New York. Jeff’s unusual middle name came from Professor Caesar Barja who, with his wife, Jean, at UCLA, were guardians of the two little boys, Dick and Phil Diamond, after their parents unfortunately died when the boys were very young. We are extremely grateful to the Barjas. As a young boy, Jeff enjoyed exploring and looking for birds and other animals, becoming an avid amateur bird guide. In the late 1960s and 1970s he was a political activist and went by himself to Central America during political unrest. Needless to say, we were not too comfortable with that move. Jeff completed his M.A. in political science at Amherst College in Massachusetts, and his Ph.D. in political theory at McGill University in Montreal, Canada. After that time he became an assistant professor in the Department of Social Sciences at Boston University. He now teaches political science at Skyline College in San Bruno, California, and has an 11-year-old son, Will, who plays soccer and video games.

Ann Diamond was born on May 1, 1962, in Berkeley, the easiest of the four C-sections. In those days there was no ultrasound. Determining the sex before birth was not routine, so we took to the hospital the application for the University Day Care Center to note the sex immediately after birth to reserve a place at the Center. Ann always loved her sports, playing varsity soccer at Harvard College in Massachusetts while studying geology and botany. Ann did not want a conventional urban family medical practice. After completing her medical degree at the University of California at San Francisco, she now has her own County Clinic in Winthrop, Washington, where she lives on a meadow surrounded by pine trees with her partner, Jerry Laverty, a superb contractor. With Ann’s assistance, he has built their family home and clinic, with company from son, Cory, and the family dog, Poi. Because Ann has practiced and traveled widely, she brings a world of experience to her patients.

Family Rearrangement

In the 1970s CAL had an arrangement with other UC campuses to pay transportation for UC faculty to give lectures on other UC campuses. In 1979 I had a seminar that followed my graduate neuroanatomy class with more complex, in-depth topics given by invited speakers who were suggested by the class. One of these was Professor Arnold Scheibel, a neuroanatomist from UCLA. I had heard of Professor Scheibel but had never seen or met him. When I went to pick him up at the airport, I took Ruth Johnson with me because I had heard he was a rather formidable, intimidating man who always wore a bowtie. I soon learned he was quite the opposite, a quiet spoken, highly intelligent, witty, innately intense, caring man with a winning smile and calm demeanor. Coming to Berkeley from his southern California home, where for decades he had taken care of his now-deceased wife, Mila, was rather like a caged bird flying through an open door for the first time and finding the outside life refreshing, stimulating, and challenging. I had never met a man so exuberant about his environment, one who could spontaneously express his emotions so warmly, clearly, and deeply about nearly everything.

That afternoon his lecture was about consciousness and the reticular formation. When he described how the nucleus reticularis thalami “opened the gates to the cerebral cortex,” I was completely enchanted. In the months that followed after this first encounter, we found we had a great deal in common to share professionally and personally as well as a great deal not so common to share, he having lived and trained mostly in public schools in New York City and I having lived essentially in open countryside, with highly educated parents, and trained in public schools in California.

We continued to see one another at professional conferences, and I all the time considering my personal family situation with my husband and children. Fortunately, the children, who already were quite independent since I had been working professionally half-time, were each on their way with their desired educational paths. Dick was completely consumed with his profession, and I was caught in a stressful, difficult void. It was by chance I had met Professor Arne Scheibel at this time. Considering my personal circumstances, our relationship slowly blossomed. Our varied combination of positive commonalities provided a possible reason to consider our spending our lives together permanently so I made a decision to end my marriage to Dick. Arne and I were married in 1982. His broad, yet in-depth range of academic and cultural topics and my broad range of firsthand experiences in various parts of the world provided growth for each in many directions. For example, he loved learning about airplanes and flight, and I loved climbing mountains, both finding means to extend ourselves to great heights. At present I feel the whole family has integrated smoothly in a most congenial manner. At family gatherings Dick and Arne can be seen sitting together and talking about problems in physics!

A few months after I had completed the preceding paragraph, Dick, a nuclear chemist and senior staff scientist emeritus with the Lawrence Berkeley National Laboratory, passed away on September 14, 2007, following a brief illness. He was 83. Colleagues say that he and his partner at the Lab, Frank Stephens, pioneered and then revolutionized the field of highspin physics with their work building the High-Energy Resolution Array (HERA) and, later, contributing to the “gammasphere” at the 88-inch cyclotron. In 1981 he and Frank won the Bonner Prize of the American Physical Society for their contributions to the understanding of high-spin states of nuclei. According some, this work had a profound impact on all of nuclear structure physics, particularly in the area of gamma-ray spectroscopy. In 1993, he received the Seaborg Award in Nuclear Chemistry from the American Chemical Society, being one of the few recipients of major prizes from the American Physical Society and the American Chemical Society.

James Symons, Division Director for Nuclear Science, said that “Dick had a long and distinguished career (37 years) at the laboratory.” “He was also one of the nicest men one could ever hope to meet, and will be much missed by all who knew him.” On this his family can concur.

In Transition

In May 1953 I received my Ph.D. the same month I gave birth to my first child, Catherine, as mentioned previously. Unfortunately, due to a mishap in the hospital, phlebitis occurred after this birth, culminating in bifemoral ligations that necessitated a home-bound recovery with limited outside activities. During this period I had a delightful encounter with Mrs. James Conant, the wife of the President of Harvard. She later asked if I would consider becoming the Hospitality Chairman for the wife of the new President of Harvard, Nathan Pusey. I accepted only to learn after several months that such a role was not one I wished to continue because I didn’t get the deep pleasure that I found with teaching and doing research.

At this time, Harvard decided that biochemistry with F. H. Westheimer and K. E. Bloch, and not nuclear chemistry with R. M. Diamond and G. Wilkinson (later a Nobelist), was the appropriate direction to develop science in the future. Fortunately, Dick was quickly hired at Cornell University where many distinguished nuclear scientists were working after World War II. I was pleased with this move because Marcus Singer, a neuroanatomist formerly at Harvard Medical School, was now a professor in the Zoology Department at Cornell. Because I did not have an academic appointment there, I hired a babysitter for my now two children and began a research project part time with Singer in the Zoology Department when an extremely unusual event took place.

An Unexpected Turn of Events

In 1954 Singer was indicted for contempt of Congress during the McCarthy era because he would not state which other Harvard students had accompanied him to some communist meetings to learn what communism was all about. The President of Cornell stated that he could not maintain someone on his faculty who had been associated with communists and dismissed Singer in the middle of the semester. At this time Singer was teaching a course for 250 students in Human Growth and Development. Who could continue to teach his course? Singer turned in my name, and I began the next day, the initiation of 3 years of rich experiences as an instructor teaching one new course after another in Comparative Anatomy, Histology, and Embryology. Actually each course was repeated each morning, one at 8:00 and one an hour later at 9:00.

As I looked back years later, I realized what a marvelous type of postdoctoral experiences I had. Giving these lectures while raising two small children, Cath and Rick, provided a wide intellectual base for future teaching and research. Also while living in Ithaca, I became vice president of the Tompkins County Democrats and resigned after my first assignment when I was asked to sign something I did not agree with. I knew then I was not meant for this role.

One afternoon while at Cornell when the children were sleeping I was reading an article in Science magazine by three researchers at CAL who had been studying the brain chemistry of maze-smart and -dull rats. David Krech, Edward Bennett, and Mark Rosenzweig used one strain of “maze-bright” rats that ran the maze quickly and another strain of “maze-dull” rats that ran the maze more slowly and laboriously. The team compared the amount of acetylcholinesterase in the brains of the two different strains of rats. The maze-bright animals had significantly more of this chemical than the maze dull animals. They showed for the first time a link between the chemistry in an animal’s brain and its ability to learn.

What a thrill I had when my mind jumped immediately to the question, “I wonder if the anatomy of these brains would also show a difference in learning ability?” This is exactly the kind of problem I would like to solve. When a few months later Dick Diamond received an invitation to return to Berkeley to continue his research, I could not have been happier to pack up the children and all our possessions.

Upon returning to the San Francisco Bay Area in 1959 with our now three children, having added Jeff, my first teaching job was at the University of California in San Francisco. I began in the School of Pharmacy giving the lectures in Gross Anatomy and sharing the teaching load in the gross lab. The next year I was promoted to teaching anatomy to the dental students, and by the third year I was teaching Neuroanatomy to the medical students.

Being in San Francisco while my family was in Berkeley created a strong pull. Specifically, the heavy bridge traffic between Berkeley and San Francisco warned me of a problem that might occur in case of an emergency. How could I ever arrive home quickly in such a stressful situation. I soon turned in my resignation.

The new research direction that happened afterward back in Berkeley has been reported in our book Magic Trees of Mind by Diamond and Hopson in 1998 written so everyone could learn to appreciate their brains and their potential. We had reason to believe many people might be interested in our book when it was first published because I had sent a copy to Professor Xie Xide, a physics professor and former President of Fudan University in Shanghai, as well as a personal friend who had scraped carrots with me in my kitchen in Berkeley. She had given Magic Trees to a publisher who asked permission to copy many specific pages from the book to distribute to pregnant women presently in China and in the future. We were told these messages from our book would affect the lives of 10 million babies and more!

First Anatomical Enrichment Experiment

Now I wish to quote directly from our book to give an introduction to our first experimental results showing the plasticity of the anatomy of the mammalian cerebral cortex, an important finding which opened the doors for our experiments to follow for the next 37 years.

By the time I got settled in, taught a few courses, and went down to their offices to see Krech, Rosenzweig and Bennett, they had moved on to an even more exciting project. Their new work was inspired by a man named Donald Hebb at McGill University. It turns out that the Hebbs allowed their children’s pet rats to run freely around the house, and this gave Hebb an inspiration. After a few weeks of free roaming, Hebb took the rats to his lab to run mazes and compared the results with maze-running by rats living in laboratory cages. Interestingly, the free-ranging rodents ran a better maze than the locked-up rats. Hebb speculated that rats confined to small unstimulating cages would develop brains worse at solving problems than animals growing up in a stimulating environment like a large house with hallways, staircases and human playmates.

From Hebb’s observation the Berkeley team got the idea of deliberately raising baby rats in two kinds of cages: a large “enrichment cage,” filled with toys and housing a colony of twelve rats; and a small “impoverished cage,” housing a solitary rat with no toys. Indeed, the rats growing up in a deliberately enriched environment ran better mazes than the “impoverished rats” raised in unstimulating confinement. And like the bright and dull rats that Krech and his colleagues had already tested, the deliberately enriched rats had more of that particular brain chemical, acetylcholinesterse, than the impoverished rats. This time, however, it was apparently nurture at work, not nature.

When I showed up at the Krech, Bennett and Rosenzweig lab, full of enthusiasm for their work and anxious to look at the rats’ brains, they were surprised but accepting In those days, money was readily accessible to add new people to scientific projects. So within days, my wish was coming true.

The research process involved removing the brain of a laboratory rat, chemically fixing, or preserving, the brain tissue and making thin slices of it (20 micra thick), viewing the slices under a microscope, then very carefully measuring the thickness of the cerebral cortex from the rats raised in both kinds of cages, enriched and impoverished. I did see variations: The enriched rats had a thicker cerebral cortex than the impoverished rats, but the difference was not the sort you could observe casually. You had to compare the brain tissue under the microscope, and the cerebral cortex of the enriched rats was only 6 percent thicker than the cortex of the impoverished rats. Nevertheless, it was highly statistically significant; nine cases out of nine showed a 6 percent difference. This was the first time anyone had ever seen a structural change in an animal’s brain based on different kinds of early life experiences. Could it really be true?

I took another year and repeated the experiment with nine more animals. Then I started to get excited. It was about 1963 by then, and my life was really hectic. I now had four children, Catherine, Rick, Jeff, and Ann and was only at the university half time, doing demanding, pioneering work in the lab. In some ways, that period is hard to recall. But I do remember very clearly the day I took the results over to show David Krech. I ran across campus with the papers in my hand and laid them out on his desk. He stared at them, then at me, and immediately said, “This is unique. This will change scientific thought about the brain.” it was a great thrill—truly an emotional high—to sit with him and share that moment.

In 1964, we published the results in a paper by Diamond, Krech, and Rosenzweig called “Effect of Enriched Environments on the Histology of the Cerebral Cortex.” And a year after that I found myself standing in front of a session on the brain at the annual meeting of the American Association of Anatomists.

We were at a hotel conference room in Washington, D.C., and I was truly scared. There were hundreds of people in the room—very few of them women—and this was the first scientific paper I had presented at a big conference. I explained the projects as calmly as I could, people applauded politely, and then—I’ll always remember this—a man stood up in the back of the room and said in a loud voice, “Young lady, that brain cannot change!”

It was an uphill battle for women scientists then—even more than now—and people at scientific conferences are often terribly critical. But I felt good about the work, and I simply replied, “I’m sorry, sir, but we have the initial experiment and the replication experiment that shows it can.” That confidence is the beauty of doing anatomy. Ed Bennett used to say to me, “Marian, your data will be good from here to eternity, because it’s based on anatomical structure.” Eternity is a long time, of course. But so far—and it’s been thirty-four years—Bennett has been right. And the man in the back row? My entire research career and some of the many scientific findings that stemmed from it will continue to show how wrong he was in the pages ahead.

Excerpts from Later Research

Normal Cortical Development

Before we could make sense of our measurements of the cerebral cortex from enriched and impoverished rats, we first had to map the normal developing and aging pattern of the cerebral cortex to serve as a standard for comparison. The cerebral cortex was of greatest interest to me because it is not only the seat of higher cognitive functions, but also one of the last structures to develop embryologically and is one of the most recent phylogenetically. No baseline for the dimensions of the rat cortex, for example, was available for the young, adult, and old-aged animal. Roger Sperry, the Nobel laureate from California Institute of Technology, once said, “Marian, all you are doing with your enriched environments is stimulating the maturation of the cortex.” We did not know whether he was right or not. You will shortly see he was half-right.

Were the stimulating environmental conditions increasing a growing, maturing cortex, or a cortex that had reached a plateau, or a decreasing, shrinking cortex? When does the cortex stop growing, and how does it age under “normal” laboratory conditions?

To answer these questions, we accumulated, over a 7-year span, information on the patterns of development and aging in the male and female cortex (Diamond, 1988b). Not only was it important to examine the cortex as a whole, but we wondered whether the right and left cortices followed similar patterns during development and aging because new information was accumulating about functional differences in the two hemispheres of human beings. Would structural differences help us to understand the basis of the functional aspects?

First, I mention the results of growth curves of cortical depths of the combined right and left cerebral cortex from histological sections of the frontal, somatosensory, and occipital cortex. In the male and female, we have two basic slopes: a positive rapidly growing cortex for the first month after birth and then a gradual negative slope throughout life. However, though the direction of the slopes of the curves was similar, we found a different developmental pattern at birth when the female was initially more highly developed than the male but the male became thicker by 3 weeks after birth.

When comparing the right and left cortical thickness differences there was no doubt there were significant sex differences in general (Diamond, 1984). In general, the male cortex was significantly thicker on the right side, and the female cortex was not significantly asymmetrical. There were exceptions, however, with the area 2 of the male cortex being symmetrical early in life, and the very old male cortex became symmetrical like the female younger cortex, possibly explaining why many older males prefer either to stay at home or let their wives drive the cars while they relax beside her.

Anatomical Brain Changes with Varied Environmental Input

Having presented the initial experimental data showing that the enriched and impoverished environments could alter the structure of the rat cerebral cortex, now I might expand upon what is considered to be an enriched environment for a rat. At Berkeley, an enriched environment contained 12 rats in a large cage with a variety of novel objects for the rats to explore; whereas, the impoverished animals were caged singly in small cages and had neither the objects, nor companions, nor the large living space. All rats had free access to food and water.

For many reasons, the feral condition, the natural outdoor environment for the rat, could not be duplicated. I admit that the laboratory conditions were sterile, controlled, and protective by comparison, and even at the very best, not like living in the rat’s natural habitat. Therefore, all types of our laboratory environments had to be considered relative to the natural one. Nonetheless, the results from the experimental conditions in the laboratory can be validly compared to each other; one condition is more enriched than the other.

With the magnitude of new experiments requiring much more work, additional help was needed. Over time, six new technicians worked in the lab: Ruth Johnson, Bernice Lindner, Carole Ingham, Fay Law, Lennis Lyon, and Alma Raymond. All were extremely capable, intelligent, and became lifetime friends.

After the initial anatomical experiment, published in 1964, when the rats were in their respective environments for 80 days (from 25 days at weaning until 105 days of age), and showed a 6% (p < 0.001) cortical depth change in initial and replication experiments, I wondered if we could find differences in the brains of preweaned rats before 25 days of age, rats who lived in the experimental conditions along with their mothers?

The thought of this project stimulated the imagination of a very bright, new graduate student, Dennis Malkasian (Ph.D. in 1969 and now an M.D., a neurosurgeon and Associate Clinical Professor of Neurology at UCLA). His experiment included an enriched cage with three mothers with three pups each (multifamily) and an impoverished cage with one mother and three pups (unifamily). All pups were 6 days old when they entered their conditions and were removed from these conditions at 14 days of age. (Before 6 days of age, the mothers destroyed the pups in the multifamily condition.)

Because the eyes had only opened in the preweaned enriched babies at 13 days of age and at 14 days in the impoverished babies, no visual cortical depth changes were found. However, the largest change that we have ever seen in the cerebral cortex of enriched versus impoverished rats was a 16% difference in an association area 39 in this group of 6- to 14-day-old experimental animals! (Malkasian and Diamond, 1971)

Here I wish to repeat that the cortex in our developmental study, presented earlier, was rapidly increasing during these first 26 days. Thus, these new preweaned data indicated that enrichment could increase the rate of maturation, as previously suggested by Roger Sperry.

Now to return to the first group of postweaned rats in our original study published in 1964, who were in their experimental conditions for 80 days from 25 to 105 days of age. At this period in our developmental study the thickness of the cortex was slowly decreasing. Now we found by measuring cortical thickness that enrichment could counteract this downward slope

A logical next question was “What does cortical thickness mean?” “What constitutes cortical thickness?” We counted nerve cells and glial cells in each microscopic field, reading vertically from the pial surface to the underlying white matter. Nerve cells were significantly 7% fewer per field in the enriched than in the impoverished occipital cortex, suggesting that further development of dendritic branching had occurred. We also found that the soma of the nerve cells was significantly larger in enriched animals (Diamond, 1967; Diamond et al., 1975) and the dendrites increased in length and number as shown by several investigators, (Holloway, 1966; Uylings et al., 1978), and (Connor et al., 1981). In addition, the glial to neuron ratio was greater with enrichment (Diamond et al. 1966); dendritic spine increases were noted (Globus et al., 1973); synaptic junctions were larger in the enriched brains (Diamond et al., 1975) as were the capillaries (Diamond et al., 1964) In summary (Diamond, 1988b), all the constituents that we measured which play a role in cortical thickness showed increases in dimensions as a consequence of enriched environments.

The fact that the glial cells increased with enrichment led to my hypothesis that Albert Einstein might have more glial cells in his enriched cortex, specifically right and left association areas 9 and 39, when compared to the cortical average in these areas from 11 other males. We found all four regions had more glial cells than the other males, but only the left 39 had statistically significantly more (Diamond et al., 1985).

Another question to be asked was, “Does it really take 80 days for cortical nerve cells to create measurable changes in their structures? How about reducing the experimental days to 30 days or 15 days or 7 days or 4 days or just one day?”

Designing similar experimental conditions to the initial ones, but using these various new time frames, we learned that we could create significant experimental differences in the cortical thickness between enriched and impoverished rats at every time period except in the brains of rats exposed for only one day. (Yet we know that one good moment can last a lifetime; some kind of changes must occur.)

As might be expected, fewer cortical thickness changes were noted in those rats exposed to their respective conditions for the shorter periods of time. A 30-day experimental period from 60 to 90 days of age proved to show the thickness increases in more cortical areas than did the other time periods. Therefore, this time period was consistently adopted for additional studies.

Another most competent, considerate, graduate student, James Connor (Ph.D. now Chairman of Neurosurgery and a professor at Penn State University Medical School) found cortical differences in their 630-day-old rats after being exposed to enrichment or impoverishment for a 30-day period. However, in this old age group a few of the enriched animals died shortly thereafter.

How could we get our enriched rats to live longer? When I would speak to folks in retirement homes, I noted that something was missing. In the early 1970s, where in their lives was the genuine, warm caring for others? (I was told that now retirement homes have introduced much more enrichment and loving care.) Perhaps, by adding some “tender loving care” (TLC) to the daily routine of our enriched rats would prove to be beneficial to their longevity.

Now we planned a new experiment where our rats lived three to a cage until 766 days of age and then they were separated into the enriched or impoverished conditions. For TLC we held the enriched rats against our chest covered by our lab coats and petted them for a few minutes as their cages were cleaned each day. Such TLC was added to the daily routine by Ruth Johnson, my faithful technician, and me. At 904 days of age when we lost an animal, we stopped the behavioral aspect of the experiment and measured the cerebral cortex for cortical thickness. Three conscientious undergraduates, Ann Marie Protti, Carol Ott, and Linda Kajisa (Linda is now an MD, an oral surgeon with her own practice) assisted with the measurements which showed that the enriched rat cortices were significantly thicker by as much as 10% (p < 0.05) compared with the impoverished rat’s cortex (Diamond, Johnson, Protti, Ott, and Kajisa, 1985). This finding provided us with immediate joy! To our knowledge no one had ever shown plasticity in such very old rat brains or in any other comparably aged animals. These were indeed welcome results.

With our ever-increasing aging population, this result was considered to be a most optimistic finding, to know the cortex could still show plasticity in very old age! This finding gave us another reason to continue to include “love” along with enrichment into our daily human encounters. Under normal circumstances why do we wait until a valued friend dies before we say how much we loved that friend.

Crowding, Super Enrichment, and Enrichment Following Brain Injury

Even though factors affecting responses to crowding are complex, we sought to illuminate at least some of them by examining the effects of crowding on brain development in our enriched rats. All rats were in their enriched or super enriched conditions for 30 days, from 60 to 90 days. We found no significant difference in cortical thickness growth, 4% to 6% with either 12 rats or 36 rats in the enrichment cages with toys when compared with controls, 3 rats per small cage with no toys. We hypothesized that interaction with the toys might be diverting the rats’ attention or entertaining them sufficiently to mitigate the stress of the crowded condition.

With an overabundance of children’s enrichment toys these days, pediatricians have asked me, “What is the effect on the cerebral cortex of too much stimulation provided by playing with too many toys?” To find an answer to this question, in the enrichment cage the toys were changed every hour for three consecutive hours, 8, 9, 10 at night for 4 weeks instead of changing toys daily or a few times each week for 4 weeks.

We did not find excessive growth with additional input. Instead we found the cortex changed less with this super enrichment than with our routine enrichment. Other investigators have shown that stress-related adrenal cortical hormones, such as cortisone, will reduce the size of the cerebral cortex. When the adrenals were removed in young animals, we saw the greatest growth in cortical thickness developed in any of our experimental conditions, indicating once more that adrenal hormones can inhibit cerebral cortical growth.

A practicing physical therapist, Alison Mckenzie, was interested in learning if she could find significant neurological changes in the injured rat cerebral cortex after 30 days exposure to an enriched environment. She found a significant increase in dendritic growth around the lesion in the left motor cortex, as well as in the right unlesioned motor cortex. Unexpectedly the somatosensory cortex adjacent to the right and left motor cortices also showed increases in dendritic growth as a consequence of an enriched environment. Indeed compensatory hypertrophy of the dendrites was evident with enrichment following injury to the motor cortex and somatosensory cortex.

In summary, our results have shown at least five factors which are important for a healthy brain according to our research.

Diet

Exercise

Challenge

Newness

Love

Gender Differences in the Anatomy of the Cerebral Cortex

We first noted cortical asymmetry in the Long-Evans male rat in a developmental and aging study. Using rats 6, 10, 14, 20, 41, 55, 77, 90, 185, 300, 400, and 650 days of age, we observed in coronal sections that the right cerebral cortex was thicker than the left in 92 out of 98 areas. Later 900-day-old male rats showed no statistical differences between the right and left hemispheres, indicating that the very old male cortex had become very much like the younger females, as seen in the next study (Diamond, 1984).

In considering the right–left differences in the cortex of the female LongEvans rat, out of 54 areas 50 showed a nonsignificant right–left difference, using rats at 7, 14, 21, 90, 180, 390, and 800 days of age. Although nonsignificant, in 36 locations, the female left cortex was thicker than the right (Diamond, 1984). (The fact that the male and female cortex showed such striking cortical depth differences actually made me feel good. There was a reason why I approached my scientific studies differently from my male colleagues.)

It has been reported that male rats are superior to females in visual spatial ability and that spatial laterality may be important for territoriality in the male. Right structural dominance in the visual spatial region of the cortex fits these male roles.

One might offer the following hypothesis for the fact that symmetry in the female cortex might prove advantageous in allowing her to respond in any behavioral mode when protecting her young. An asymmetrical cortical pattern might prove a hindrance. Many further studies were carried out to determine the role of sex hormones on laterality. For one example, if the testes were removed at one day of age and the rats were autopsied at 90 days of age, the right greater than left cortical thickness was reversed everywhere in the cortex except in the visual cortex where significant right–left differences were retained.

An example showing that female sex steroid hormones might influence the dimensions of her cortex appeared quite by accident. Upon comparing the cortical thickness of enriched postpartum females with the impoverished postpartum females, we unexpectedly found no significant differences in initial and replication experiments. The reason was that both the enriched and impoverished postpartum females had increased their cortical thickness during pregnancy. In essence, the impoverished cortex had caught up with the enriched. Should we try to benefit from this knowledge and apply more educational lessons during this enhanced period?

Immune Regulation and the Cerebral Cortex

With genes for the disease of Lupus Erythematosus rampant in my family, I promised my sister when she was dying at 26 years of age and I was 19 that someday I would try to shed light on the role of the cerebral cortex with the immune system. I have since lost a brother, a niece, and a nephew because of this horrible disease, lupus. In the early 1980s I read a publication by some French scientists (Renoux et al., 1980) showing that lesions in the cerebral cortex resulted in enhancing or inhibiting effects on the immune system. Inspired by these initial investigations, we studied the congenitally athymic nude mouse to identify areas of the cerebral cortex that might be affected by the T cell-deficient state.

In 1986, we published our first research project dealing with the cerebral cortex and the immune system (Diamond et al., 1986). Essentially this project demonstrated that the dorsal lateral frontal cortex was bilaterally deficient, as measured by microscopic thickness, in the female, immune incompetent, nude mouse when compared with the cortical thickness of an immune competent mouse from the BALB/c strain. In 1996 and 1997, two more studies of ours confirmed this cortical deficiency. In addition, Gary Gaufo, a talented and reliable graduate student (now an assistant professor at the University of Texas, San Antonio) learned to transplant the thymus and reverse the cerebral cortical and blood immune deficiencies in the nude mouse (Gaufo and Diamond, 1996, 1997).

Other findings with rodents suggest that cortical immune responses can be generalized across both sexes and in different species and possibly in human beings. With this information, I was ready to take this project to human subjects instead of rats.

The functions of the dorsal lateral frontal cortex in humans include working memory, changing set, judgment, initiative, planning ahead, sequencing data, etc. Some investigators have utilized the xenon dynamic single photon emission-computed tomography (SPECT) during the performance of the Wisconsin Card Sorting Test (WCST) to demonstrate activation of the dorsal lateral frontal cortex in humans. Individuals with dorsal lateral prefrontal lesions do poorly on the WCST. Instead of using the WCST we chose the well-known card game of contract bridge.

We hypothesized that while individuals played bridge, this area of the cortex might be stimulated and possibly influence the production of T lymphocytes. Therefore, we planned to take blood samples before and after adult women played 1½ hours of contract bridge and to quantify the number of T lymphocytes in the blood samples, including CD3, CD4, CD8, and CD56 cells types. In 2001 (Diamond et al.) we published our results obtained by comparing the venous blood sample before and after playing bridge, showing a significant increase in CD-4 positive T lymphocytes as measured by the Wilcoxon signed rank test and the sign test. No significant increases were found in CD3, CD8, or CD56 cells. Also no significant CD4 cell increases were found between the two samples of blood drawn from each of three women who did not play bridge but only sat quietly listening to gentle music at the same time the other women played cards.

Our data suggest that people might be able to improve their immune functions with more purposeful demanding activities related to frontal lobe tasks. For example, because CD4 cells are decreased in AIDS, might it be possible for people with this devastating disease to learn to play bridge or a comparable mental stimulating activity?

Overseas Enriched Experiences

Australia

In 1977 during a 6-month stay, Professor Richard Mark from the Biology Department at the Australia National University in Canberra, asked if I would present a seminar on my enriched and impoverished research at Berkeley. I was delighted because I had some new data on the environmental influences on the female brain when previously we only worked with male brains.

I submitted my title stating, “Environmental Influences on the Female Brain.” On the day of the seminar, the folks from Richard’s lab were present, but that was all. Only three people came. Little did I realize how chauvinistic the Australian men were in those days. There were no women professors at their university, I was told. When asked by Professor Mark a year or so later to give another seminar, I offered the title, “The Effects of the Environment on the Mammalian Brain” and had a full house. We had found gender differences in response to identical environments. The male showed greater growth in the occipital cortex and the female in the somatosensory cortex.

I had another unusual experience with brains in Canberra. Keith Crowley, the Principal of Village Creek primary school in Kumbah, Canberra, agreed to allow me to teach an anatomy class to his children after I had successfully given a course to the parents. First, I needed a real human brain and gathered courage to go to the main Health Center in Canberra and spoke with an administrative official. When I asked to have a real human brain to use for teaching in the schools, his reply was the following: “If I gave you a brain and if you stored it in a classroom closet, then a child might decide to take it home. The child might leave it out so the dog could eat it. The headlines of the Canberra Times would read ‘Dog eats Mr. Jones’s Brain’.” Needless to say, I obtained no brain from him. But the nurses at the Health Center had heard of my plea and brought me a brain!!!

I later had a World Health Fellowship from The World Health Organization in Geneva, Switzerland, to continue with the teaching I had started. Each morning a car and driver awaited to take me to the different schools. A possible indication that the Australian officials approved of my teaching human anatomy to their children is shown by the following example. One morning an unusually fine car arrived, and the driver informed me that the car belonged to the Prime Minister’s wife; no other car was available that day. They could have said no car was available.

China

I had originally visited The People’s Republic of China in 1978, as the wife of Richard Diamond and his colleague, Professor John Rasmussen, both of whom were invited by professors in the Department of Physics at Fudan University in Shanghai. Our daughter, Catherine, a professor in Taiwan, and Louise Rasmussen also accompanied us.

At this time I had the privilege of witnessing several surgeries on the nervous system performed with acupuncture anesthesia. In one laboratory the investigators had learned they could reduce pain by stimulating two thalamic nuclei, the centromedial and parafascicularis. I asked if they knew the level of endorphins in these nuclei. They had not heard of endorphins. When arriving home, I looked up this subject and found indeed both nuclei were rich in endorphins. I also witnessed surgery removing schwannomas on the VIII nerve within the skull; three such operations were occurring simultaneously in that one surgical room.

In 1985 I returned to China for 6 weeks with my second husband, Arne Scheibel, in response to an invitation from two professors I had met during my previous trip. This time scientific lectures were in order. In the Biology Department in Fudan University on the hottest days of the year, Professor Bo, a leading biologist, introduced me to speak about our work with enriched and impoverished environmental effects on the brain. My next lecture covered my experiments on increased glial cells in Albert Einstein’s brain with students sitting in the windowsills in an overcrowded auditorium. Professor Bo kindly paid back us a visit in Berkeley after our return.

One particularly memorable enrichment/impoverishment talk took place in a Naval Research Institute with a huge, tiered amphitheater filled with uniformed attendants complete with formal white military hats. We were told we were the first foreign visitors invited to speak at this Institute whose specialty dealt with submarines. Our experimental results showing the detrimental effects on brains of isolated rats may have been one reason for their interest in our work. Since our visit, other foreigners have enjoyed visits as well.

Before leaving Shanghai, we made arrangements to obtain small blocks of cerebral cortex including Broca’s area from the brains of Chinese who had recently died. We studied these brain tissues in comparison with Englishspeaking Americans and have yet to decipher the results.

In 1998 I returned to Shanghai to present a keynote address in the hotel Pudong Shangri La, with Jane Goodall and Robert Haas, the poet laureate for the year. The administrators of Independent Schools in South East Asia asked me to speak on plasticity of the brain induced by the environment, experiential and nutritional. The data of one of our graduate students, Arianna Carughi (Carughi et al., 1989), was of particular interest, showing the detrimental effects on rat brains caused by low-protein diets during pregnancy. However, if low protein was maintained during pregnancy, but after birth, a high-protein diet was provided during lactation and for the first month following weaning, the dendrites in the cerebral cortex showed growth but not as complete as normal. Nonetheless, these dendrites did show a response to an enriched environment; whereas the protein-deprived ones did not.

Nairobi, Kenya, Africa

In 1988 Professor James Kimani, the Chairman of Anatomy at the medical school in Nairobi, invited Arne and me to spend 6 weeks lecturing about the brain, both environmental influences, and a theory on the biological basis of schizophrenia and aging. Dr. Kimani’s wife, a practicing obstetrician, was the one who informed us that the women in Nairobi did not like to eat protein while they were pregnant because they delivered too large a baby. I wonder if our lectures on the importance of protein during pregnancy and thereafter had any effect on turning this practice around in hopes of developing better brains.

We delivered lectures on basic neurohistology as well as our research data from our enriched and impoverished studies with rats. We asked for a round table discussion with the medical students as we have done in other countries with success, but here our request was refused because we think they were afraid of our political ideas coming from the United States. However, the last day of our visit, we were granted permission to have our round table discussion. The amphitheater was filled with doctors and medical students. The very first question: “How did Arne and I meet?” I answered satisfactorily evidently. Needless to say, we were surprised after all of our lectures about the brain. Another question: “Are people north of the equator more intelligent that those south of the equator?” I answered, “What is your definition of intelligence?” Then I continued that I am certain in relation to your society you are much more intelligent than I and vice versa. We learned the girls did not want to become doctors because the boys would not be attracted to them.

The two nonprofessional highlights in Africa were spending a few days in the Masai Mara in Kenya with the marvelous wild animals in their natural habitat and climbing to 12,000 feet on Mount Kilimanjaro in adjacent Tanzania where I had a fireside chat with two men, one of whom was former President of the United States, Jimmy Carter.

Cambodia

After successfully working on the effects of enriched and impoverished environments on the structure of rat brains for many decades, I developed a project to apply any successes and benefits from those results. My new project, Enrichment In Action (EIA), is funded by private donations. The main goal of EIA is to enrich the lives of very impoverished children, mentally and physically, in order for them to find meaningful employment while living healthy, productive lives.

In December 2001, a friend, Carole Miller, a former research associate at CAL, and I worked for 5 weeks with orphans living in a Buddhist compound in the forest adjacent to the famous Angkor Wat temples in Siem Reap, Cambodia. We began our project with three objectives: (1) enrich their diet of fish and rice with supplementary vitamins and minerals in addition to education about a more balanced diet, (2) enrich their knowledge and mental capabilities with English and computer lessons for them to obtain good jobs in the future, and (3) enrich their interactions with foreigners by playing physical and mental games. We wanted the children to know we sincerely cared about them by providing as much interaction, kindness, consideration, and love as we knew how.

Utilizing the theme Each One Teach One where those who know teach those who do not, our Cambodian children have progressed very well from many perspectives. (I have used this theme in Berkeley schools for about 30 years.) Initially the age range of the Cambodian children was between 10 to 19 years of age, with one 19-year-old having completed the second grade. We soon learned age alone was not adequate criteria from which to judge these children. Since 2001, I have returned for 2 weeks each year to provide new directions and ideas for their education. Some have become quite proficient with the computer and with their English lessons. At present I have requested Mr. Som Chamroeun, who manages the project most of the year when I am here in Berkeley, to provide me with papers written in English by the children. I wish to evaluate their progress to see how much they have learned to date. A few of those papers have already arrived and are quite impressive, not only in terms of their English but also in terms of their sensitive content.

Teaching at Berkeley

Here I wish to highlight only four courses, which include the nervous system, and which I have designed or taught for decades; others have not been offered as frequently. In the Fall semester I have two courses, General Human Anatomy dealing with both gross and microscopic anatomy, and Applied Anatomy. In General Human Anatomy, though the nervous system is covered by twice the number of lectures as the other systems, I want the students to realize all systems work together. In the Applied Anatomy lectures, the range of topics includes Neurosurgery, Neuropathology, Neurology, Pediatrics, Healthy Environments, Neuroradiology. What is Applied Anatomy? This is a course where former anatomy students return after they have applied their anatomy to become professionally successful in their chosen, medically related fields. These young professionals give lectures to the present Berkeley students to indicate how basic anatomy and neuroanatomy are fundamental to their disciplines.

Why do I continue to present these courses? Because I believe if more people understood the structure and function of their bodies, influenced so intricately by the nervous system, and took care of themselves early in life, then the period of their lives after 50 would be more healthy and enjoyable. At present, look at the cost of health care for the disabled elderly. Many are not even aware that the simple phrase “Use It or Lose It” applies to their brains, bones, and muscles! In the Fall of 2006 alone, I had 736 students, including mostly undergraduate students, with some graduate students as well, taking Human Anatomy, a kernel that could eventually make a difference in health education.

In the Spring I offer two courses: Human Neuroanatomy and Anatomy Enrichment. The graduate Human Neuroanatomy course for about 50 students covers gross and microscopic anatomy of the nervous system and the associated structures. To aid in the study of the structure and function of the brain and the spinal cord, their protective coverings and vascular supply, we designed and wrote an unconventional book, The Human Brain Coloring Book (Diamond et al., 1985.) Arne and I use this book for our classes: he at UCLA, and I at Berkeley. Learning neuroanatomy is not conceptually difficult but is rich in detail and is essential to remember as a foundation for research as well as clinical practice. For these reasons when we were invited to write a Brain Coloring Book by Larry Elson, Ph.D., the author of the Anatomy Coloring Book, we accepted wholeheartedly. Using one’s kinesthetic sense in coloring enhances the learning and memory processes. What a pleasure knowing we have a resource to offer students of all ages to enhance their learning challenge. The Human Brain Coloring Book has been continuously in print since 1985 and has been translated into German and Spanish.

The Anatomy Enrichment course was established in 1977, 30 years ago, but under a different title. This course includes those Berkeley students who earn an A or B in the undergraduate Human Anatomy course. They are then eligible to use their anatomy notes to design lessons to teach gross and neuroanatomy in the Berkeley and Albany public schools, K through 7th grade. The children see their first human brain in first grade. One little boy was wise enough to say it was “awesome.” The nervous system is taught more thoroughly in the seventh grade when the schoolchildren are advanced enough to comprehend a bit more detail.

New Horizons

In 1980 Dee Dickinson in Seattle, Washington, established New Horizons for learning, a very successful international educational network and on-line resource for educators. She had the foresight before the field became popular to value the role that the brain plays in education. As logical as it seemed, this relationship was not accepted as fact when we first showed that anatomical brain changes could be measured microscopically in response to enriched or impoverished experiential conditions, in other words, with different levels of education. Dee was very supportive by including these findings on her Website at www.newhorizons.org that now receives around eight million hits a month. Over decades we constantly added new data, providing examples of brain plasticity to a wider audience on the Web. At one time a national senior organization used our article, “Successful Aging of the Brain,” for a topic for their Website interaction conference. Thanks you, Dee, for this means of sharing neuroscience and education with a greater audience.

Administration Roles

Now, I wish to mention some of the administrative positions I carried out at the same time I was raising my family, teaching, and running a research laboratory.

In 1967 Dean Walter Knight asked if I would like to become an Assistant Dean in the College of Letters and Science at CAL. I had previously criticized the quality of academic advising for our undergraduate students so I responded positively to his invitation to serve this administrative position. The major role, in addition to everyday commitments, I accomplished in my opinion, was to survey about 20 or more universities in the United States to inquire about their best academic advising programs. When all were evaluated, I learned that a most effective system was having senior, honor students serve as major advisers because they knew the quality of the present faculty and their courses, the present requirements of the college, appropriate work loads, and so on. After a 5-year term, I resigned thinking I had set up a good path for the new dean to follow, only to learn he had taken the job to earn money for his golf lessons!

In 1970 I accepted the position to be the first woman Associate Dean of the College of Letters & Science. I served for many years before I was invited to be the Dean of the College. I knew I loved my family, teaching, and research too much to attempt taking on this demanding responsibility. I declined. When I returned to my academic department, Physiology and Anatomy, the Chairman, Nello Pace, told me that the faculty had voted to invite me to become chairman of the department. Once again I declined. Later on former President Clark Kerr asked if I would like to be Chancellor of the University of California at Santa Cruz campus, and I declined for the same reasons as mentioned previously. I honestly felt I could serve our CAL students and the health of our society better by teaching anatomy and neuroanatomy and at the same time contributing new information from my research on how to develop and maintain a healthy brain and body throughout our lives. Without a doubt, I still gained most satisfaction from following these roles for many decades.

Being invited to take on such demanding roles within our great University of California system, inspired me to write my 4 Ps.

Personal priority…. Family and friends

Professional priority…. Brains, friendly colleagues and students

Perseverance…. Essential for everything

Positive attitude…. Look at the alternative

One year I took a survey of nine CAL Nobelists who had earned their prize in science. I asked each of them, “What or who inspired you to go into science?” All but one replied, “a great high school teacher.” What inspired the “missing” one? His parents had hired a young woman directly out of teacher’s college to live in their home and teach their child as much as she could about everything. This Nobelist kept track of this special teacher until she was 90 years old!

If good teachers were responsible for producing so many Nobel Laureates, such an accomplishment should inspire generations of teachers new and old!

In the 1980s I was asked if I would like to become the Director of the Lawrence Hall of Science (LHS) up in the hills overlooking the campus. After inquiring about various aspects of the administrative role of this position, I learned there was a large debt lurking in the background, convincing me that I did not wish to become entangled in such a large, negative, financial web and declined. When I was asked again in 1990, my primary responsibilities on campus were in a manageable condition. I knew of no major problems at the Hall so I accepted and held the position for 5½ years.

What major accomplishments at the science hall brought me satisfaction? Working with Dr. Jenny White and Cathy Barrett we designed and set up exhibits about brains. At first I provided an assortment of animal brains from a whale, a dolphin, a monkey, a sheep, a bird, a cat, a mouse, and a rat for the visitors to compare the broad spectrum of their sizes and shapes. (One science museum on the East Coast had a cockroach brain!) We displayed a cocaine addict’s brain compared to a normal with a label saying that “the choice is yours.” Many concerned mothers alerted their children to this exhibit. We developed a large, interactive exhibit based on the optimistic data we had collected from our laboratory rat experiments on campus with enriched and impoverished environments. Thousands of visitors to the Science Center learned how their brains could “grow with use” and “decrease with disuse.” This exhibit was sent to at least seven other science centers in the United States. In addition, on many weekends each year we held 2-day Brain Conferences for hundreds of California public school teachers to benefit from ours and other scientific investigator’s new, brain research. Using the LHS vans, the staff took brain materials around to the Bay Area public schools to accompany the brain skits they had created.

One other original creative effort at the Hall was a “jungle gym” in the shape of a deoxyribonucleic acid (DNA) molecule 60 feet long and 5 feet high. I wanted children to associate fun with solid science. This 60-foot molecule was constructed in Michigan and carried in three parts on a flatbed truck across the country to LHS. Now when young people encounter DNA in their textbooks they will recall playing on it at LHS. I am deeply indebted to Ken Hofmann, a successful local contractor, for financing this structure.

When I finished my 5½-year term at the Hall, I hoped that most of the LHS staff knew what dendrites were, that the local public knew their brains could change favorably with use or unfavorably with disuse and that children were familiar with DNA!

Special Berkeley Colleagues

I might begin this section with an obvious statement indicating how nearly impossible it is to write an autobiography about my neuroscience career of 60 years upon the required 30-plus pages during 3 summer months between my teaching classes in the Fall and Spring semesters. Undoubtedly, many worthwhile experiments and lovable, long-term colleagues have been omitted, definitely not willingly. I offer my deepest apologies. Maybe some day I will tackle a more extensive creative effort.

That being said, I have one colleague who has been directly involved in my neuroscience contributions here at Berkeley so I would like to expand on this relationship. Over a 23-year period Professor Robert Knight M.D. repeatedly came to Berkeley from Davis to help teach in my graduate, neuroanatomy laboratory course. Now he gives a lecture each year to my Applied Anatomy class, bringing us up to date on his research dealing with electrophysiological techniques to study cognitive processing. What a pleasure to have a competent, friendly, practicing neurologist work with our students! More recently he has become the Director of the Helen Wills Neuroscience Institute at Berkeley. In my opinion to have him fill such a position at Berkeley is the wisest choice our administration could make as shown by the growth of the budget, number of faculty with their varied research projects and quality students, and so on under his direction.

Two other colleagues, Professors George Brooks and Steve Lehman, have combined their teaching efforts with mine to make two successful, popular, undergraduate courses in Human Anatomy and Human Physiology. I definitely value their long-time friendship and effective scholarship. Thank you, Bob, George, and Steve as well as many others for making my professional life at Berkeley an incomparable, enriched experience!

In Closing

At this time I wish to express my sincerest gratitude to Larry Squire and the Society of Neuroscience for inviting me to join my colleagues in presenting a collection of thoughts and facts about my professional and personal life as a neuroscientist. I am deeply indebted to my family, administrators, colleagues, students at all levels, technicians, and other friends for their contributions of time, valued assistance, and support. To have spent decades investigating and teaching about brains has provided incomparable satisfaction.

Finally, let me share something of precious significance to me from one of my children. About a year ago in the evening, I walked into my bedroom and saw lying on my pillow a note containing just three words; MOM, DOC, EXTRORDINAIRE … Who could ask for more when I was doing what I loved best!

Selected Bibliography

Bennett EL, Diamond MC, Krech D, Rosenzweig MR. Chemical and anatomical plasticity of the brain. Science 1964;146:610–619.

Carughi A, Carpenter KJ, Diamond MC. Effect of environmental enrichment during nutritional rehabilitation on body growth, blood parameters and cerebral cortical development in rats. J Nutr 1989;119:2005–2026.

Connor JR, Melone JH, Yuen AR, Diamond MC. Dendritic length in aged rats’ occipital cocrtex: An environmentally-induced response. Exp Neurol 1981;73: 827–830.

Connor JR, Diamond MC. A comparison of dendritic spine number and type of pyramidal neurons in the visual cortex of old adult rats from social and isolated environments. J Comp Neurol 1982;210:99–106.

Diamond MC. Functional Interrationships of the Hypothalamus and the Neurohypophysis. PhD Thesis 1953; University of California at Berkeley.

Diamond MC, Law F, Rhodes H, Lindner B, Rosenzweig MR, Krech D, Bennett EL. Increases in cortical depth and glia numbers in rats subjected to enriched environments. J Comp Neurol 1966;128;117–126.

Diamond MC. Extensive cortical depth measurements and neuron size increases in the cortex of environmentally enriched rats. J Comp Neurol 1967;131: 357–364.

Diamond MC, Lindner B, Johnson R, Bennett EL. Differences in occipital cortical synapses from environmentally-enriched, impoverished, and standard colony rats. J Neurosci Res 1975;1:109–119.

Diamond MC. The aging brain-some enlightening and optimistic results. Am Sci 1978;Jan-Feb:66–71.

Diamond MC, Connor JR, Orenberg EK, Bissell M, Yost M, Krueger A. Environmental influences on serotonin and cyclic nucleotides in rat cerebral cortex. Science 1980;210:652–654.

Diamond M. Age, sex and environmental influences. In Geschwind N, & Galaburda AM, eds. Cerebral dominance-The biological foundations. Cambridge, MA: Harvard University Press, 1984;134–146.

Diamond MC. Sex differences in the brain. Brain Res Rev 1988a;12:235–240.

Diamond MC. Enriching heredity. New York: Free Press, 1988b.

Diamond MC. Hormonal effects on the development of cerebral lateralization. Psychoneuroendocrinology 1991;16:121–129.

Diamond MC. Enrichment, response of the brain. Encyclopedia of neuroscience 3rd edition. Elsevier Science, 2001a.

Diamond MC. Response of the brain to enrichment. Annals of the Brazilian Academy of Sciences 2001b;73:211–222.

Diamond MC, Dowling GA, Johnson RE. Morphologic cerebral cortical asymmetry in male and female rats. Exp Neurol 1981;71:261–268.

Diamond MC, Hopson J. Magic trees of the mind. New York: Dutton, 1998.

Diamond MC, Johnson RE, Gold MW. Changes in neuron and glia number in the young, adult, and aging rat occipital cortex. Behav Biol 1977;20:409–418.

Diamond MC, Johnson RE, Ingham C. Brain plasticity induced by environment and pregnancy. Neuroscience 1971;2:171–178.

Diamond MC, Johnson RE, Ingham CA. Morphological changes in the young, adult and aging rat cerebral cortex, hippocampus and diencephalon. Behav Biol 1975; 14:163–174.

Diamond MC, Johnson RE, Mizono G, Ip S, Lee CL, Wells M. Effect of aging and environment on the pyriform cortex, the occipital cortex and the hippocampus. Behav Bio 1977;20:325–336.

Diamond MC, Korenbrot CC. Eds. Hormonal contraceptives, estrogens, and human welfare. New York: Academic Press, 1978.

Diamond MC, Krech D, Rosenzweig MR. The effects of an enriched environment on the histology of the rat cerebral cortex. J Comp Neurol 1964;123:111–120.

Diamond MC, Law F, Rhodes H, Lindner B, Rosenzweig MR, Krech D, Bennett EL. Increases in cortical depth and glia numbers in rats subjected to enriched environment. J Comp Neurol 1966;128:117–126.

Diamond MC, Lindner B, Johnson R, Bennett EL, Rosenzweig MR. Differences in occipital cortical synapses from environmentally enriched, impoverished and standard colony rats. J Neurosci Res 1975;2:109–119.

Diamond MC, Johnson RE, Protti AM, Ott C, Kajisa L. Plasticity in the 904-day-old male rat cerebral cortex. Exp Neurol 1985;87:309–317.

Diamond MC, Rainbolt RD, Guzman R, Greer ER, Teitelbaum S. Regional cortical deficits in the immune deficient nude mouse: a preliminary study. Exp Neurol 1986;92:311–322.

Diamond MC, Scheibel AB, Elson LM. The human brain coloring book. New York: Harper and Row, 1985.

Diamond MC, Scheibel AB, Murphy GM Jr, Harvey T. On the brain of a scientist: Albert Einstein. Exp Neurol 1985;88:198–204.

Diamond MC, Weidner J, Schow P, Grell S, Everett M. Mental stimulation increases circulating CD4-positive T lymphocytes: a preliminary study. Cognitive Brain Research 2001;12:329–331.

Gaufo GO, Diamond MC. Prolactin increases CD4/CD8 cell ratio in thymus-grafted congenitally athymic nude mouse. Proc Natl Acad Sci 1996;93:4165–4169.

Gaufo GO, Diamond MC. Thymus graft reverses morphological deficits in dorsolateral frontal cortex of congenitally athymic nude mice. Brain Res 1997;756: 191–199.

Globus A, Rosenzweig MR, Bennett EL, Diamond MC. Effects of differential experience on dendritic spine counts in rat cerebral cortex. J Comp Physiol Psychol 1973;82:175–181.

Greer ER, Diamond MC, Murphy G Jr. Increased branching of basal dendrites on pyramidal neurons in the occipital cortex of homozygous Brattleboro rats in standard and enriched environmental conditions: a Golgi study. Exp Neurol 1982;76:254–262.

Holloway RL. Dendritic branching: some preliminary results of training and complexity in rat visual cortex. Brain Res 1966;2:393–396

Malkasian D, Diamond MC. The effects of environmental manipulation on the morphology of the neonatal rat brain. Intern J Neurosci 1971;2:161–170.

Mohammed AH, Zhu SW, Darmopil S, Hjerling-Leffler J, Ernfrs P, Winblad BK, Diamond MC, Eriksson PS, Bogdanovic N. Environmental enrichment and the brain. Prog Brain Res 2002;138:109–133.

Renoux G, Biziere K, Renoux M, Guillaumin GM. The cerebral cortex regulates immune responses in the mouse. CR Acad Sci D (Paris) 1980;290:719–722.

Rosenzweig MR, Bennett EL, Diamond MC. Cerebral effects of differential environments occur in hypophysectomized rats. J Comp Physiol Psychol 1972;79:56–66.

Rosenzweig MR, Bennett EL, Diamond MC. Modifying brain chemistry and anatomy by enrichment or impoverishment of experience. In Newton G, Levine S, eds. Early experience and behavior. Springfield, IL:Charles C Thomas, 1968;258–298.

Rosenzweig MR, Krech D, Bennett EL, Diamond MC. Effects of environmental complexity and training on brain chemistry and anatomy: A replication and extension. J Comp Physiol Psychol 1962;55:429–437.

Uylings HBM, Kuypers K, Diamond MC, Veltman WAM. The effects of differential environments on plasticity of cortical pyramidal neurons in adult rats. Exp Neurol 1978;62:658–677.

York AD, Breedlove SM, Diamond MC, Greer ER. Housing adult male rats in enriched conditions increases neurogenesis in the dentate gyrus. Soc Neurosci Abstracts 1989;15(383.11):962.

Charles G. Gross

BORN:

New York City

February 29, 1936

EDUCATION:

Harvard College, A.B. (Biology, 1957)

University of Cambridge, Ph.D. (Psychology, 1961)

APPOINTMENTS:

Massachusetts Institute of Technology (1961)

Harvard University (1965)

Princeton University (1970)

VISITING APPOINTMENTS:

Harvard University (1963)

University of California, Berkeley (1970)

Massachusetts Institute of Technology (1975)

University of Rio de Janeiro (1981, 1986)

Peking University (1986)

Shanghai Institute of Physiology (1987)

Tokyo Metropolitan Institute for Neuroscience (1988)

University of Oxford (1990, 1995)

HONORS AND AWARDS (SELECTED):

Eagle Scout (1950)

Finalist, Westinghouse Science Talent Search (1953)

Phi Beta Kappa (1957)

International Neuropsychology Symposium (1975)

Society of Experimental Psychologists (1994)

Brazilian Academy of Science (1996)

American Academy of Arts and Sciences (1998)

National Academy of Sciences (1999)

Distinguished Scientific Contribution Award, American Psychological Association (2004)

Charlie Gross and his colleagues described the properties of single neurons in inferior temporal cortex of the macaque and their likely role in object and face recognition. They also pioneered in the study of other extra-striate cortical visual areas. Many of his students went on to make distinguished contributions of their own.

Charles G. Gross

I was born on February 29 in 1936. My parents, apparently anxious of my feeling deprived of an annual birthday, celebrated my birthday for 2 or 3 days in the off years and even more in the leap years.

I was technically a “red diaper baby.” My parents were active Communist Party members. In fact, however, I never heard the term red diaper baby or knew of my parents’ longstanding party membership until I was in graduate school, years after my father had lost his job because of his politics. Rather, my parents hid their formal communist affiliations and made every effort to bring me up with all the experiences and options of a normal American boy. Yet they managed to transfer their political worldview to me and even, for a long time, their fear of speaking or acting on that worldview. (For more about red diaper babies, see Kaplan and Shapiro 1998.)

My Parents

My father came from the Pale of Settlement in Russian Poland to Manhattan’s Lower East Side when he was a year old or perhaps two. His birthday was on the sixth Chanukah candle, but whether in 1900 or 1901 was not clear. For school he needed a Gregorian date, and his Rabbi calculated it was December 25, but as this was deemed inappropriate for a Jewish boy he was assigned December 15, 1900. Because of the uncertainty about his true birth date, when I was a kid we celebrated my father’s birthday on several December dates.

My father’s father never held a regular job after being fired in a furrier strike when my father was age 12. My father was then sent out to sell chewing gum on the street, in between household duties like carrying coal to their sixth-floor tenement. Their two-room apartment was filled with five siblings as well as various uncles and aunts and more obscure relations on their way from steerage to a new life. His family had predicted my father’s success because when the mattresses and blankets were laid out for the night, he hid his shoes in a crevice under the dining table and thus was the only person to effortlessly find his shoes in the morning chaos. Many of the transient relatives were of various anarchist and socialist persuasions, and so political arguments saturated family life.

About once a year, when I was a schoolboy my father took me to see his parents, then in the Boro Park section of Brooklyn. (We lived in the Flatbush part.) Like the halls of their apartment house, my grandparents smelled of chicken fat, as they greeted me by rubbing their bristly faces against mine. My father spoke to them in Yiddish. This was still their only language; it sounded weird to me. I was struck by the absence of books and magazines. The only decorations on their blotched walls were my father‘s diplomas.

My father was a student at Townsend Harris High School, a 3-year high school attached to City College of New York. He then went on to City College itself followed by a master’s degree in history at Columbia. By this time my father was an active Communist Party member. He was working on his doctoral thesis when the Party asked him to quit graduate school and go to work as a high school teacher of history and economics. (This wasn’t such a bad deal: many young communists were sent to organize in factories and fields.) He spent 29 years, one less than the number required to retire on a pension, at Seward Park High School on the Lower East Side as a fulfilled, successful, and beloved teacher. In the evening, my father taught educational sociology in the City College School of Education and economics in its Business School.

My mother was a Party member too. She was born in the States, but her parents also came from the Pale. Although my mother spent about 7 years in and out of college she never got a B.A. degree, perhaps because she felt it was too bourgeois at that time in her life. In my childhood, she worked as a secretary in the public school system and was active in the American Labor Party (ALP), an organization that had supported Henry A. Wallace’s third party Presidential campaign and that was accused of being a communist front.

The only political activity of my father that I knew about as a child was in the Teacher’s Union. I would read about it in The New York Teacher News. This was not a bread-and-butter union concerned primarily with wages and working conditions. Rather it was a politically activist union particularly interested with improving the educational and social programs of the school system. It introduced Negro and Women’s History week into the curriculum. It agitated successfully for more Black teachers, more schools, and more educational resources for Harlem. It strenuously advocated racial integration for the schools long before this became a national issue. It put out pamphlets to fight discrimination, racism, and prejudice (for an account of the Teacher’s Union activities, see Zitron, 1968).

As I later learned, the Teachers Union was thrown out of the AFL (The American Federation of Labor, the first national alliance of unions) in 1941 as communist dominated. It then joined the more left CIO (Congress of Industrial Organizations) but was thrown out in the great purge of left-wing unions in 1950. Starting then, its leaders were gradually eliminated from the school system, and its main activity became defending academic freedom in general and, more specifically, its own members from being fired. Perhaps 200 or 300 members were fired, and a similar number resigned to avoid public exposure (Caute, 1978; Ravitch, 1983).

In 1953, when I was applying for college, my father was called before the Feinberg Commission, the New York investigatory body set up to free the New York City school system of anyone “advocating the overthrow of the Government by force, violence, or any unlawful means … and any member of a society or group that taught or advocated such action.” My father, in the parlance of the day was asked to “name names.” Naming names of those seen at a Communist Party meeting decades ago was necessary to establish “good faith” to keep one’s teaching job, assuming one was not a Communist Party member in which case dismissal was immediate. He refused to cooperate but made a successful plea to be allowed to finish out the school year. Then he quietly resigned, missing a full pension by one year, but avoiding the publicity of exposure, which in similar cases often resulted in the families having to change their names and leave town.

My parents gave me my political orientation, my interest in history, and my concern for social justice.

Childhood Education

At Lake George

From before I was born, my parents spent every July and August camping on a state-owned island on Lake George in the Adirondacks (Leonbruno, 1998). Up until the time I was about age 10, I spent the summer camping with them. Then I started going to conventional camps and eventually worked as a nature or swimming camp counselor or busboy and spent only a month or less with my parents on Lake George. My Lake George experience produced a deep and lasting love of the outdoors. It probably helped lead me to the Boy Scouts and biology, both crucial for my subsequent career. After I came back from graduate school abroad, I continued to occasionally camp on Lake George with my wife and kids or members of my laboratory. Today, no matter what the season or weather, trail walking still gives me an enormous sense of pleasure.

In Elementary School

My experience in elementary school was an unmitigated disaster. I was often sent to the Principal’s office and then exiled to the kindergarten for days for being “disruptive.” My mother was constantly summoned to school and yelled at because I “talked” (the sin that followed me at least until college), did not do my work, made trouble, and generally was bad. My long-suffering mother came to school with pages of yellow-lined paper describing my reading and intellectual interests, but it was to no avail. My grades were poor, and I am sure that today I would have been classified, at best, as hyperactive and having an attention disorder. Needless to say, I was not allowed to get anywhere near the various programs for the smart kids.

In the Boy Scouts of America

Baden-Powell’s imperialist Scout movement saved me. Inspired by my Lake George experience and encouraged by my parents, I joined the Cub Scouts as soon as I was old enough. There I was fiercely achievement oriented and rapidly rose through the Cub and Boy Scout “ranks,” earning lots of merit badges and becoming the youngest Eagle Scout in Brooklyn at the time. Later, getting A’s in high school and college and publishing papers and getting grants as a young academic felt just like getting merit badges in cooking, civics, and bird study.

My central experience as a Boy Scout was spending a month for four summers at Ten Mile River Boy Scout Camps. We slept in open lean-tos, wore uniforms, had formal flag raising and lowering ceremonies and other than waking up, cleaning our bunks, taking a dishwashing turn, and going to bed to taps there were no required scheduled activities. Most of my “troop” spent their time hanging around the bunk, reading comics or playing baseball, and maybe joining the afternoon general swim. By contrast, I ran around frantically taking classes and exams to get merit badges in every possible thing. The guys in my troop seemed unperturbed by my weird achievement intensity. They elected me to the honorific “Order of the Arrow”; and when I became an Eagle Scout they took over my turns at dishwashing, as that duty seemed to them below the dignity of such a station.

In the general swim we had “buddies,” whose hands we had to raise when the waterfront director up in a white tower blew his whistle; if separated from your buddy you were “docked” (not permitted to swim) for some days. A few years later I was the waterfront director. The feeling of power standing on the white tower blowing the whistle for “buddies” was only equaled when, much later, I stood on the podium teaching physiological psychology in the same classroom where I had taken it as an undergraduate. (Actually, I was only assistant waterfront director. I strongly disliked the director but luckily he broke his leg early in the season, so that tower was mine, and my required subservience was restricted to the half-hour each day that I visited him in the infirmary. He was not the last boss that I had trouble with.)

Education at Home

There was a good public library near where we lived. Accessible by public transportation, there was a bigger one near the high school and a very big one in the center of Brooklyn. Each week I would take out the maximum number of books allowed from one or more of them. Too much of my reading, especially in elementary school, was of classic novels I could not have possibly understood, like Madame Bovary and Crime and Punishment. Once my mother and I happened to be reading Lord Jim at the same time. From her casual remarks I realized, but never told her, that not only did I have no idea what the book was about but I had missed the central plot element where the captain abandoned ship. I am still deprived of many classics because I thought I had “read” them already.

My parents carefully kept me away from communist summer camps and the network of activities for children of communist and far-left parents (for a description of these camps and activities, see Mishler, 1999). Yet my father systematically transferred his politics to me, particularly by regularly going over the New York Times with me. In addition, leftist periodicals such as I.F. Stone’s Weekly lay around the house, as did novels from the leftist Book Find Club, although most of his Marxist library had been removed to someone’s cellar before I could read. I was told never to mention in school Paul Robeson, whose huge form had once towered over me at a concert, or indicate I knew who Saco and Vanzzeti, Spartacus, Joe Hill, or any of the left pantheon were, not even Pete Seeger. This anxious exhortation not to talk about politics, let alone act, extended well into my adult life. “Don’t jeopardize your grades,” my father said, “until you get into college.” He repeated the plea when I was in college and again in graduate school: “Don’t sign anything too radical until you get a job.” When I did get a job: “Wait until you get tenure.” “Wait. Wait, until you can be effective.” I tended to take his advice. As we’ll see, I waited until I had tenure as a full professor before getting arrested, finally, at an anti-Vietnam war demonstration.

Education Around the City

Starting in elementary school I would go often, alone or with a friend, to the American Museum of Natural History in Manhattan. Besides the exhibits, I went to talks (I remember one on diatoms), joined clubs (like the Jr. Astronomy Club), and went on bird-watching walks they sponsored.

Another major activity was exploring the miles of used bookstores that once existed on Fourth Avenue in the City. Many of the bookstores in which the books were arranged by subject were out of our price range. We specialized in the ones where the books were shelved by acquisition or size but were only 19 cents or so apiece. I still have a few of these like College Physiography.

Erasmus Hall High School

I had been afflicted with a severe and long-standing stutter. I remember being pulled out of class in the sixth grade and sent to special stuttering classes for a half-hour each day and then another half-hour class for my lisp. Nothing got better so my parents took the initiative and arranged for me to go to weekly sessions for what they called an “indirect approach to my stutter.” After about a year of this a new person was assigned to me, and the first thing he said was “Do you know why you are here?” I said, “Of course. I am here for an indirect approach to my stutter.” “No,” he said, “you are here to discuss your emotional and personal problems.” So I went to my parents and suggested a “direct approach” to my stutter might be more successful. They arranged for speech therapy to substitute for the psychotherapy. By now I was ready to start high school, and fortuitously the stutter was very useful.

My local high school, Erasmus Hall High School, was then a very mixed school of about 6000. Except for putting the students taking Latin together, and a few “honors” classes, there was no “tracking” by academic ability because that was considered to be antidemocratic. Rather, segregation by academic ability was done more covertly and efficiently. Programming the classes for 6000 students was a formidable challenge before computers. A “program committee” of the students with the highest grades as freshman carried it out. As a reward they were allowed to make their own programs, and they put themselves together in the same classes with the best teachers.

My parents went to the Erasmus authorities and successfully argued that “because of [my] stutter” I should be allowed to take Latin instead of a spoken language. Only the very best students usually took Latin as their first language, so in spite of my lousy grades and terrible disciplinary record I got tossed in with them. In that very rich soil I suddenly flowered into a highly engaged and competitive student, no longer bad (except in gym that I almost failed each year). In that adolescent memory, the top 20 or so boys and girls around me at Erasmus seem among the smartest and most intellectual group I ever knew. Actually, I enjoyed Latin, and it was a pretty good idea to take it because I never did learn to pronounce any spoken language correctly. In fact, my ear was so bad that I never lost my Brooklyn accent, which was later called an affectation in view of the years I spent among phony English accents in Cambridge, Massachusetts, and real ones in Cambridge, England.

In high school, I took all the science possible—5 years of science and 3½ of math. I was an editor of the school newspaper, the editor of the math magazine, and founder/editor of the science magazine. In spite of my bad stutter I spoke up often, especially in History, English, and Economics classes. These classes were easy and fun for me: everything fit into the all-encompassing (Marxist) framework I had absorbed at home. I did keep away from the honor math and creative writing courses, which were taken only by the math whizzes or real writers, respectively.

In the summer before my senior year, I carried out a research project in plant ecology for the Westinghouse Science Talent Search. I studied plant succession in a one-acre plot near my family’s campsite on Lake George. Plant succession refers to the orderly temporal progression of plant communities starting, for example, from bare rock and proceeding to the “climax” forest for that region. Each new stage changes the environment making it more adapted for the plants of the next stage. Plant succession, it seemed to me, was actually a better example of dialectical materialism in nature than many of the examples given by my heroes, the Marxist scientists J. B. S. Haldane and J. D. Bernal, although I never breathed a word of this in my report. As a result of this project and a written examination, I was one of 40 Finalists.

As a high school senior, I applied to several Ivy League Colleges. The financial forms required for aid presented a problem. At this time, my father had just been called before the Feinberg Commission routing out subversives from the school system and, as mentioned above, because he would not inform, he knew he would lose his job that year. So what was he to put on the form: that he had a schoolteacher’s salary now but had no income prospects for the future? Every potential employer in the city knew why a highly rated schoolteacher was suddenly unemployed (and unemployable, at least as a teacher).

Undergraduate at Harvard

I was offered small scholarships at several good places, and somehow my father was able to get them to bid against one another until Harvard finally gave me enough to go. Tuition was $600 the year I was admitted. At my Yale interview the interviewer had asked whether my trench coat was a Burberry and then whether I was Jewish. At that time the Jewish quota at Yale was about 12% (Karabel, 2005). I didn’t get into Yale. My Harvard class was about a third Jews.

Making Beds and Pete Seeger

The entire freshman class lived in dormitories in Harvard Yard; seven of us shared a suite. On the first night, after I was in bed, the three from North Dakota came in and sat on my bed. They had somehow figured out I was a Jew and, never having met one before, they were eager to talk about religion, one of the few subjects in which I had almost zero interest. Although all seven of us were from public schools, I had by far the longest latency to get into a Harvard uniform (grey flannels or khaki chinos, button-down shirt, tweed jacket). The ones from North Dakota took about one day whereas I took about 3 years. I never made it to the acculturation stage of Harvard mugs or stationery.

As part of my Harvard scholarship I was assigned a job making the beds and cleaning the rooms of other freshmen. One of my clients was very embarrassed by this and helped me make his bed. I later discovered that his father was a blacklisted folksinger. In the middle of the term I quit the job, claiming falsely that it interfered with my lab courses, but they raised my scholarship anyhow. Ever since, I have been a totally, completely, and proudly retired bed maker.

Although my ex-client and some other red diaper babies in my class (including one whose father was killed serving in the Abraham Lincoln Brigade) remained in the closet, I got close to three other freshmen from left backgrounds: Emile Chi, Jim Perlstein, and Mike Tanzer. We were active in the Harvard-Radcliffe Society for Minority Rights. The only thing I remember our doing was organizing a Pete Seeger concert, actually a very daring act for the time. Somebody in the audience was taking notes—we thought it was the FBI.

Biology and Skinner

I wanted to major in history. But soon my competitive drive to get A’s conflicted with political fear. I realized I probably was not smart enough to get A’s and express my political opinions, if indeed that were possible. I knew it was time to find another major after I started getting back papers with comments, like “A: I’m glad to see how well your papers have progressed from the Marxist jargon that characterized your earlier papers” and writing papers arguing that Edmund Burke was really a great liberal and Victorian England was heaven on earth. Biology was the obvious alternative: it was relatively apolitical, I had lots of nature merit badges, I was a former plant ecologist, and it was a simple way to be a premed (like 70% of my freshman class had planned to be). In fact, I took a minimum of hard-core laboratory course in biology and was particularly attracted to related courses in psychology.

The most influential freshman course I took was The Science of Human Behavior with B. F. Skinner, the great prophet of radical behaviorism. The lectures were all from his textbook of that name. It contained no illustrations of any kind, no experiments, no data, and no references. Pavlov did get a few paragraphs, and Freud was reinterpreted into Skinner’s system in parts of a few chapters. There were chapters on applying his “laws of operant behavior” to government, law, religion, economics, education, and most everything else.

There was something about the power of his charisma and the all-inclusive nature of his theory that absolutely captured me. It seemed to mesh perfectly with my materialistic view of the universe. Of course, I was far from alone. Well into the 1960s, Skinner and his disciples were the major force in psychology departments with the experimental study of learning at their core and their influence pervasive beyond the rat in a Skinner box to education (“teaching machines”), and social and clinical psychology (“behavior therapy”). Eventually Skinner’s central lessons about careful experimental control, misuse of statistics, rejection of hypothetical “physiology” were generally absorbed and it was time to move on, in the “cognitive revolution,” to the mental phenomena he tended to overlook or simplify such as attention, language, and consciousness. I worked in Skinner’s lab that summer under his research associate’s direction. I was a complete incompetent: putting the wrong pigeon in the wrong box, throwing the wrong switches, and being incapable of the simplest experimental psychology skill like drilling a hole or soldering a wire. I never saw Skinner that summer except when I mowed his lawn. For at least several years I continued to spout Skinnerian jargon, and it was not until about 40 years later when I was forced to teach introductory psychology that I fully realized how totally inadequate an account of learning and life his formulations had provided.

I was also pretty awful in the only lab courses I could not avoid like Organic Chemistry. There I ran up an enormous bill by always shutting my drawer on expensive burettes and flasks in a rush to escape. We were marked on the quality and quantity of our yields, which I usually had to mop up from the floor or off my lab coat. I got so hot from anxiety that I would open the lab window and start ether fires that would sweep down the lab bench never endearing me to the other premeds.

I was such a “grind” that when the Sunday New York Times arrived I would hide it in the bottom of the closet until my day’s work was done. I resolved that as soon as I graduated my first priority each day would be to read the Times, no matter what. I have kept this resolution pretty well although when living in Beijing and Shanghai I had to cycle to a tourist hotel to obtain as a substitute, the Herald Tribune, and in places like Tibet and Cuba I had to read the Times on-line at Internet cafés while everybody around me was frantic on video games.

History of Science

To escape the usual large lecture courses, I took a graduate seminar in The History of Ideas on Reproduction before Harvey with I. B. Cohen, a distinguished scholar of Isaac Newton. Seven of us sat in easy chairs in his small cozy living room while he fingered his watch fob and his wife served tea and fruitcake on a tea trolley. In class, I reported on Ashley Montague’s Columbia Ph.D. thesis on “coming into being” among the Australian Arunta. The Arunta were an aborigine group that, apparently, did not understand the origin of paternity, how birth was related to sexual intercourse. Montague never saw an aborigine but had extensively reviewed a huge literature of missionaries, travelers, anthropologists, and theorists. His sources plagiarized, misquoted, trashed, ignored, interpreted, and misinterpreted one another in ways that made them sometimes seem even weirder than the Arunta. This was my first close encounter with professional scholarship, and it made a lasting impression. (Montague was born Israel Ehrenberg in East London in 1905, became for a while Montague Francis Ashley-Montagu and eventually a leading feminist and antiracist author of anthropology pop- and text books and finally, a colleague at Princeton.)

My term paper (the only written work in the course) was on Theophrastus, Aristotle’s successor as head of the Lyceum and known as the “father of botany,” largely because most of his nonbotanical works were lost. The only comment Cohen put on the paper was “A,” which was the modal length of comments I received on my papers at Harvard. I try to remember that when all I can think of putting on a student’s paper is “interesting” or “well written” and a grade. That term I also took History of Psychology with E. G. Boring, the leading historian of experimental psychology. Those two courses solidified my interest in the history of neuroscience, a subject I have continually worked on since I was in graduate school.

Neuroscience Begins

As a junior I took a summer course in Woods Hole in invertebrate zoology, with lots of graduate students, led by Ted Bullock, then the doyen of invertebrate neurophysiology. We had lectures all morning and then labs with great live material that we were supposed to design experiments on, but I could never quite figure out an experiment to do. That summer I also worked in the Woods Hole lab of Valy Menkin, a boyhood friend of my father. Menkin had worked with Walter B. Cannon at Harvard Medical School and was an iconoclastic student of inflammation. His disaffected son was around so I tried to ingratiate myself with him by saying the lab work was boring. So he told his father, and that was the end of what would have been my first scientific publication (Menkin, 1955).

A course in physiological psychology with Phil Teitelbaum (of hypothalamic feeding mechanisms fame) fixed my interest in what we now call “neuroscience.” I then took a seminar with Don Griffin (the great experimental naturalist and codiscoverer of bat navigation) on The Biological Bases of Behavior. A paper I wrote for that course, “A Critical Review of a Theory of Bird Navigation,” became my first scientific publication (Griffin and Gross, 1956). I then worked in his lab trying to measure the visual acuity of pigeons with a view to seeing whether it was adequate for current ideas on sun navigation. Sometimes I helped on his bat experiments. One day he said to me, “Gross, bring me the car battery from the next room” for use in an experiment. This Brooklyn boy answered, “What does a car battery look like?”

One of the perks of being elected to the National Academy of Sciences decades later was that I wrote the entry on Griffin for its Biographical Memoirs; I emphasized his poor performance in school, that he never put his name on his graduate student’s papers, and that he attributed consciousness to animals rather “low” on the scale, for example, to bees. This was my first close experience with a highly original and accomplished scientist, and it profoundly affected me.

I got friendly with two biology graduate students, originally my teaching fellows, Bill Harvey and Frank Carey, students of the premier insect developmental endocrinologist Carroll Williams. I would take tea and hang around the Williams lab; there, one term I tried hard and failed to condition proboscis extension in the blowfly. Other later well known biologists were also my teaching fellows. Don Kennedy said my final in physiology was written by a chicken with its left leg, and Tom Eisner really gave it to me for borrowing a bicycle from a senior professor’s house (where I was house sitting with Bill Harvey) and getting it stolen.

The Biology Department was a lively place. Jim Watson had just arrived as a new assistant professor and was busy bad mouthing all the senior professors. Even the Nobelist George Wald, an early pioneer in molecular biology, was dismissed by him as “just a flower picker.”

Life as a Harvard undergraduate was certainly not as much fun as high school or graduate school, but I did sample a few of its very many worlds and earned some merit badges giving me several options for the next stage in life. As I took no courses in graduate school (there were none), the undergraduate ones with Skinner, Boring, Teitelbaum, and Griffin formed the core of my formal education in neuroscience.

Cambridge University: Graduate School

Finding My Way

As a senior I had to decide what to do next: medical school or graduate school. My father, given his experience, thought an M.D. was a safer bet than a Ph.D. as it could give me an independent income. So I applied for medical school as well as National Institutes of Health (NIH), National Science Foundation (NSF), and Fulbright fellowships, all with success. I postponed admission to medical school (the Dean said, “come back anytime”) as well as the NIH fellowship and took the Fulbright.

I had applied for a Fulbright to Great Britain because I spoke not a word of anything but English (though my stutter was gone by then except when I have to identify myself in the still-traumatic “around the circle” introductions). I couched my project in ethology because at that time ethology, the naturalistic study of animal behavior, in Great Britain was almost entirely done at Cambridge (under Bill Thorpe) or Oxford (under Niko Tinbergen), and that’s where I wanted to go. I was awarded a Fulbright to study with Thorpe, at Jesus College and the Cambridge Zoology Department.

Cambridge (and Oxford)

To greatly oversimplify, Cambridge and Oxford are made up of financially independent colleges (e.g., Jesus) that admit, tutor, feed, and house undergraduates, whereas departments like Zoology give lectures, admit graduate students, have laboratories, and set examinations. Most faculty (“dons”) have appointments in both colleges (to eat, drink, take snuff, and tutor) and in departments (to lecture and research). At Cambridge, unlike Oxford, the tutorial sessions were called “supervisions” and the tutors “supervisors.” Cambridge and Oxford, being more or less identical institutions, had to give different names to virtually everything, for example, the spring term is the Lent term at Cambridge and the Hilary term at Oxford; the final exam is the tripos at Cambridge, the examination at Oxford; the doctorate is the Ph.D. at Cambridge, the D.Phil. at Oxford; philosophy is called “moral science” at Cambridge; the length of the gown worn by undergraduates is much longer at Cambridge; the requirement for undergraduates to wear gowns at night when in the streets was still enforced in Cambridge but abolished in Oxford; the clothing required for sitting an examination was subfusc or formal only at Oxford; the biddie (female) cleans your room and washes your tea cups at Cambridge, but the scout (male) does it at Oxford, the end of the punt that you stand on when punting is opposite at the two places and so on.

U.S. graduates coming to study at “Oxbridge” usually came as undergraduates, that is, “read” for a “second B.A. degree” because (1) there was no formal graduate education like courses or exams but only writing a doctoral thesis, many of which were rejected, (2) U.S. bachelor degrees were rather looked down on, and (3) most important, being smoked at by your undergraduate tutor (cf. Stephen Leacock’s classic essay on Oxford dons) was considered the pinnacle of educational enlightenment, enabling its students to go out and make most of the globe red (i.e., British).

THORPE AND ETHOLOGY

So I arrived in September 1957 in the elegant eleventh-century rooms of Bill Thorpe in Jesus College, Cambridge (rooms that had once been part of a brothel and before that a nunnery). Thorpe was one of the founders of ethology, the study of species-specific behavior, and one of the few ethologists interested in animal learning, but under natural conditions in contrast to the Skinner boxes or mazes of U.S. psychology. More specifically, he had pioneered in the study of the interaction of experience and innate wiring in the development of bird song. We were not sure what to do with each other, but I wrote a few tutorial essays to ensure Thorpe that I knew the line on the ethological approach to animal behavior as opposed to that of contemporary experimental psychology. I went for another “supervision” to Richard Gregory in psychology who assigned me an essay on Hebb’s Organization of Behavior, but then he complained that my essay was just a book review. Although I was later viewed as a highly successful undergraduate psychology tutor at Jesus, as measured by the degree results of my tutees, I never really knew what a tutorial session was supposed to be. As a tutor, I would assign a subject, and then run to the library to read about it (as I had not taken any hard core experimental psychology courses) and return the books a few days later before my student wandered into the library for them. I did know, from my own few Cambridge tutorial sessions, that you were supposed to start the session by praising the student’s efforts before chopping him up into little pieces or at least trying to.

In my search for a home department at Cambridge I looked around the Zoology Department (where Thorpe was attached), but it seemed mostly cutting up formalin-fixed animals. Then I applied to the combined psychology and physiology course (but my background was inadequate they said), and finally, the physiology course (where they really rejected me out of hand). The new History and Philosophy of Science program seemed attractive, but it would not start until the following year.

JESUS COLLEGE

So I wandered about sampling the social, intellectual, and political life that I had thought eluded me at Harvard. Jesus College was a big rowing college. Other colleges had portraits like of Darwin and Newton on their dining hall walls. Jesus had “Big Splash,” a famous oarsman. The college had seen a succession of 7-foot Yale oarsmen, so the college servants seemed to think all Americans were rowers so they pressed me into the Jesus crew. I was put into the lowest, the seventh boat. (Even lower creatures, the ones whose glasses were on crooked and usually taped were relegated to the stationary “tubs” with holes in their oars.) It was the only organized sports I ever did in my life, other than required calisthenics in high school gym, until some postdocs turned me into a (slow) marathon runner in the 1990s. (Actually I ran only two New York Marathons because the first was such an extraordinary, high experience that the second was an anticlimax.)

In my first term at Jesus I lived in two magnificent lead-windowed rooms only a few centuries younger than Thorpe’s ex-brothel. There was no heat in the bedroom (would have been unhealthy), but a little room was attached for the biddie to wash my teacups. Reputedly there were baths in some other building, but I never found them or looked hard. We ate in a huge hall lined with tables the length of the hall. Thus, to reach the bench on the far side of the tables the students would step up on the near bench and walk along the table, their gowns fluttering after them, until they found a place on the other side. We took bread from a passed silver platter and arranged it next to us between the inevitable muddy footprints. There was some meat thing served in silver chafing dishes and some pale green substance appropriately called “veg” because there was no way of distinguishing its origins as probably Brussels sprouts or peas or maybe green beans. One could order beer or hard cider in a pewter mug from one of the waiters. This was followed by huge serving bowls of a “trifle,” some sweet pudding concoction of cream, cake, and gelatin. The undergraduates bolted their food wordlessly and then hurried across and along the table, if on the far side, and out the hall. Meanwhile the Fellows at High Table at the far end of the hall were just beginning their nightly banquet. Once to try to get the attention of my fellow students and start a conversation, any conversation, I waved a little silver dish that said Col. Jes. on it and yelled, “Hey look, I’m stealing the college silver” and stuck it in my pocket. Nobody blinked. I still have it, stashed among obsolete stuff like ashtrays and Japanese tea ceremony brushes. Eventually, I started getting little cards in my college mailbox from undergraduates inviting me for (hand-ground) coffee in their rooms after dinner, the appropriate site for conversation.

One day in Hall I attempted to sit down at the Boat Club table where special delicacies like orange juice for breakfast were served. At the head of the table, The Captain of the Boats, d’-_________________(some long Norman name), explained that this was the Boat Club table, apparently not recognizing my service in the galleys. That seemed a good time to end my athletic career. I don’t know how long the seventh boat waited for me that day before promoting someone from the tubs or finding another American. Anyhow it had been hard work keeping the guy in back of me from jamming his knees into my back and from “catching a crab” and being catapulted into the water. So I missed rowing in the “bumps” the first big race of the season. In fact, I never saw a boat race except on TV.

At Harvard I had been a premed grade grubber shunned, I imagined, by the literary sets, so at Cambridge I set out to write an article for every single literary magazine. I wrote an article “Science and the Control of Behavior” for Granta (not yet a famous magazine), film and book reviews and a special issue on science for Cambridge Review, “Understanding Men and Monkeys” for Varsity, and “Psychodrama” for The Play’s the Thing, a theatre magazine that failed before they published me.

It was strange and liberating to be in an environment where being a communist was just another political persuasion or perhaps just another English eccentricity. There were even Communist Party officers among the senior dons. I was an officer of a club called “The Heretics” that had been founded before World War I. My principal duty was to have fancy dinners with the interesting speakers we invited.

Life as Larry Weiskrantz’s Student

MEETING LARRY

Finally, after 6 months of sampling, I trudged back to the Psychology Department to try to get into its undergraduate program. I was ushered into the office of its Professor (i.e., Chair) O. L. Zangwill. He was the son of the distinguished Anglo-Jewish writer Israel Zangwill (who coined the term “melting pot” for the United States, though he had never been there and also wrote the classic “King of the Schnorrers”). O. L. Zangwill was a founder of modern neuropsychology and one of the first to grasp the perceptual functions of the right hemisphere. He sat there in a pin stripe suit, chain smoking, and never looking me in the eye (or anybody else’s I discovered later). I told him I wanted to read psychology. He asked me if I knew any psychology. I used to cram for my finals in a cubicle in Lamont Library at Harvard surrounded by psychology textbooks and suddenly the rows of titles that had surrounded me in that aroused state flashed across the screen and, tired of being rejected by all the other Cambridge departments, I started to read off the titles. After a few rows of bookshelves, he stopped me and suggested I should become a research (i.e., graduate) student rather than an undergraduate and sent me off to a Dr. Weiskrantz.

So I went through the creaky wooden halls looking for that old German and came across a young American fellow in a tan lab coat and sunglasses (science faculty wore white lab coats in lieu of the Arts faculty’s clerical gowns; and technicians and janitors wore this tan coat). It turned out he was Larry Weiskrantz. The dark glasses were because his regular pair had been broken in an accident. Larry had just been hired by Zangwill to start a new monkey research lab. I told Larry who I was, and he invited me to join him to work on “the effects of brain lesions and drugs” on monkeys. That seemed interesting and lo, then and there, I became Larry’s research student and for more than the next 50 years his colleague and friend. Larry came from the Girard Orphanage in Philadelphia, studied psychology at Swarthmore, got a MSc. from Oxford and a Ph.D. from Harvard. He was Karl Pribram’s graduate student. Pribram along with his students, particularly Larry and Mort Mishkin (D. O. Hebb’s student at McGill), set the standards for the modern experimental study of the functions of the primate cerebral cortex in the use of surgical techniques (Pribram had been a human neurosurgeon), behavioral analysis, and anatomical reconstructions.

At about this time, at the end of my first Michaelmas (fall) term, an Indian Prince was given my rooms and I moved out into digs. I rarely returned to Jesus. Work was beginning as I was now Larry’s research student and I was starting to meet my kind of English people. Thus began among the best intellectual and social years of my life, but this is not the place for the social part.

The only requirement for the Ph.D. was a dissertation and an oral defense. There were no required courses, seminars, or examinations. I did go to a variety of lecture series over the 4 years I was at Cambridge such as by Horace Barlow on cerebral cortex, Giles Brindley on the visual system, Zangwill on neuropsychology, and Richard Gregory on perception. Alas, but the great Lord Adrian, founder of modern neurophysiology, had retired the previous year, so my only contact with him was when he introduced visiting speakers or when I almost ran over the little man when I was in my girlfriend’s car and he on a bicycle

PH.D. THESIS: FRONTAL CORTEX

My dissertation research was on the effects of lesions of the frontal cortex (now usually called “prefrontal cortex”) in macaques. In the 1930s Carlyle Jacobsen and John Fulton had shown that frontal lesions made monkeys and apes unable to perform “delayed response.” In this task the monkey sees a peanut hidden under one of two cups and after a brief delay tries to retrieve the peanut from one of the cups. This was actually the first objective evidence for a severe and permanent cognitive deficit after experimental damage to a specific region of the brain. It also led directly to the tragedy of many tens of thousands of humans receiving frontal lobotomies. (Fulton reported at an International Congress in 1935 that two chimpanzees, Becky and Lucy, had delayed response deficits after frontal lesions and, incidentally, that Becky was no longer upset at all when she made errors on the task, unlike before the operation. The Portuguese neurologist Egas Moniz was in the audience. Hearing how unperturbed Becky was after her surgery, he rushed home to begin the frontal lobotomy craze for which he received the Nobel Prize in 1949.)

Jacobsen and Fulton thought the delayed response deficit was one of “recent memory,” but this was only one of several interpretations when I began my work. Frontal lesions also produced impairment on auditory discrimination learning. Finally, a third effect of frontal lesions was the production of locomotor hyperactivity. My research had two main questions. First, could the three symptoms be produced by different lesions of frontal cortex: could the syndrome be fractionated? The second question was what was the nature of the delayed response deficit. This was approached by studying what other tasks animals with frontal lesions could and could not perform in order to infer the underlying dysfunction.

Previously, most primate learning and cognition studies were carried out manually, particularly in the “Wisconsin General Test Apparatus.” For example in the delayed response task, the experimenter would bait one of the two cups in the monkey’s view but out of his reach, lower a screen between the cups for a few seconds, then raise the screen and let the monkey choose a cup. I set out to automate this task and other tasks such as visual discrimination learning. Not only did this eliminate interaction between the experimenter and the monkey but by using drops of water or small sugar pellets as a reward, the animal could be trained and tested for an order of magnitude more trials per day. Some of my ideas for all this had probably come from my time working in Skinner’s lab where all the experiments and data collection were automated, often ingeniously. (Similar automatic apparatus are now in widespread use for primates, but not in my time.)

Before I started this work, about the only tools I had ever used were an axe, a knife, a hammer, and, inadequately, maybe a simple screwdriver. When a chair in our house broke, my father would put it in the cellar until his “handy” friend would arrive with his toolbox to fix it. So to build my research devices I had to learn from scratch about the many kinds of screws and nails, about taps, dies, and drill bits, about power saws and drill presses. I controlled my devices with electromagnetic switching circuits identical to the ones I failed to build or understand when I worked in Skinner’s lab but now had to master. Although I was proud of learning these skills, they really gave me little intrinsic pleasure. So as soon as I had research assistants or graduate students or money to pay shop personnel, I was happy to abandon these hard-learned skills except for wiring an occasional lamp or hanging a picture at home. However, this experience helped me later in dealing with shop technicians, and I always encouraged my students to acquire machine shop skills.

I renewed my Fulbright for a second year. At the end of that year, taking what the Harvard Medical Dean had told me literally, I wrote to Harvard Medical School and said I would like to enter the following September. Some secretary sent me the entire application for admission, either by mistake or by design as some motivational test. I took one look at that massive pile of forms on why I wanted to be a doctor and so on and pushed it off my desk into the waste basket at which point I was transformed from a premed into a psychology graduate student. I reactivated my NIH predoctoral fellowship for my two remaining years in England and lived rather royally on it.

As recounted in an oversize doctoral thesis and several papers, I found that different partial frontal lesions could produce the delayed response and auditory discrimination deficits independently (reviewed in Gross and Weiskrantz, 1964). I suggested that the delayed response deficit was due to the inability to use information near the time of its input. This view was not all that different from Jacobsen and Fulton’s original interpretation, or for that matter from the contemporary one of a deficit in “working memory.” The changes in locomotor activity were interpreted as due to increased reactivity to external stimulation and unrelated to the other symptoms. Today, none of these papers is ever cited except by my students, and then rarely. Sic transit gloria.

About 6 months after I started writing the historical introduction to my thesis, I had reached Galen in the second century (who had actually studied the effect of frontal lesions in piglets.) At that point Larry said that I “had better get on with the more empirical parts of the thesis.” So my thesis never had any historical introduction at all. However, that 6 months provided the seeds for my book Brain, Vision, Memory: Tales in the History of Neuroscience (1998) as well as for several other papers not included in that book.

MY FIRST SCIENCE PAPER

My first science paper was with Larry and Buba Mihailivic showing that the frontal delayed response deficit could be produced reversibly by electrical stimulation of lateral frontal cortex (Weiskrantz et al., 1960). We published an expanded version to Brain. Buba was visiting from Belgrade and stayed with me. You could not win a political argument with him because he would always resort to the fact that when captured by the Nazis as a Communist partisan he at one point had to dig his own grave and lie in it, thereby making his political opinions inviolate. He was a chain smoker and threw his butts and empty cigarette packs on the floor because cleaning them up was “women’s work.” Actually his wife had been a Communist partisan too, but she stayed in Belgrade so I don’t know how she dealt with this problem.

MY FIRST NATURE PAPER

One day at the Departmental tea, Professor Zangwill expressed some skepticism of the practice in the United Kingdom of awarding support for graduate work only to students who received a First Class Degree. This refers to the grade on the final (and only significant) exam at Cambridge and Oxford. In terms of frequency it might be similar to a summa cum laude in the United States, but it requires much more originality, (“cleverness” in the British sense) and less rote learning. Zangwill wondered whether all Fellows of the Royal Society had received Firsts. I turned to the graduate student sitting next to me, Liam Hudson, a recent Oxford graduate and said, “Let’s find out.” Because the class of degree of graduates of Oxford and Cambridge was readily available in any large library, as was the roster of the Royal Society, we checked one against the other and wrote a letter to Nature that about one quarter of the F.R.S.’s who went to Cambridge or Oxford had not received Firsts (Gross and Hudson, 1958). This, my first Nature paper, yielded more correspondence and more immediate press coverage than any paper I ever wrote until my paper with Liz Gould on cortical neurogenesis (Gould et al., 1999a). Although apparently upsetting to the British notions of hierarchy and cleverness, our results did not surprise me. Some F.R.S.’s had gotten in as explorers or inventors and never went to graduate school. A few were ill during exam time. At least some must have just had the drive and brilliance to circumvent the usual path to academic success, hardly a surprise to somebody from a country that had produced Benjamin Franklin and Thomas Edison.

LIFE IN LARRY’S LAB

Besides my thesis work I had several little projects. I collaborated with Larry and another graduate student, John Oxbury, on several drug studies. I presented one at a meeting in Rome and hitchhiked there by way of Athens. This was the beginning of my infatuation with travel especially on a shoestring. Among my other nonthesis nonpop publications was one on the effect of gymneic acid on rat’s taste. Gymneic acid is from an herb that blocks sweet taste in humans, and we claimed it did so in rats too. Among the studies that never got published was one with Alan Cowey, Larry’s third research student, on learning in planaria, including after they had been cut in half. We collected an obscure local species and chuckled that its rarity would make it hard for others to fail to repeat our results because they couldn’t get the species. However, we never got any reliable results ourselves. We continued to collaborate after graduate school, rather more successfully, and Alan became a lifelong friend.

A study of the effect of hypothalamic and amygdala lesions in rats on adulterated food also got nowhere because, unlike the control and unoperated animals, the lesioned rats just totally stopped eating and would have starved if I had not given them palatable food. After my roommate CareyMcIntosh saw me operate on a rat, he couldn’t eat for a while either.

In England, one could not do surgical procedures on a monkey without a Home Office license, and one could not get such a license without experience in surgery. Larry got around that because he had been trained by Pribram in the United States, but technically Alan and I could not do surgery except with Larry. However, when Larry went on sabbatical leave in my third year, I needed a frontal cortex lesion made on a trained animal so Alan and I operated anyhow. We intended to remove the principal sulcus, a very prominent sulcus on the lateral surface. During surgery, it looked a bit “atypical” and a year later, on autopsy, it turned out that we had only removed half of the sulcus. (Alan was not responsible: this was “my” part of the brain.) So I learned two (obvious) lessons about surgery: (1) make the opening as big as you need to really see where you are and (2) if something looks “atypical” or different, you may just be lost (a lesson good for map reading too). Larry had left without putting any one of us “in charge.” Later, when I had a lab of my own I realized the value of that approach. Usually when I went away for, say, 3 months to China or someplace, I just said good-bye and in my absence everything ran more or less fine because everybody had his or her responsibilities. One year I left someone in charge, and that person was transformed into a petty dictator even complaining about the time other people came to work.

Once, in collaboration with Larry, I was supposed to film some monkeys with brain lesions reaching for food. Somehow I had held the camera upside down so I when I showed my results to Larry I had to hold the projector upside down. Nary a criticism came from Larry, but the next time he locked the door and did the filming himself.

APPRECIATION OF LARRY

I am now very embarrassed about how little I appreciated Larry while I was a graduate student. As I was leaving Cambridge I even commented how little I had learned as his graduate student: I complained that I still had only the faintest idea what the frontal cortex did. About a year later I was invited to write a review of my thesis results for a small meeting on the frontal lobes to be followed by a book. I asked Larry if he wanted to be a coauthor of my contribution (Gross and Weiskrantz, 1964) and he said, “Yes, please. After all you could not have done the work without me.” I suddenly realized that this was equally true for four of the five empirical papers from my thesis I had already submitted without even showing them to him, let alone making him a coauthor (e.g., Gross, 1963a, 1963b). Now, more than 40 years after he took me as a student I understand how supportive and tolerant he had been and how absolutely critical he was for my development as a scientist.

Even outside of the laboratory, my 4 years in Cambridge, England, were probably among the richest years of my life. I met a number of wonderful and very special people, including my first wife, Gaby Peierls. Many of these have continued to be close friends even when years and an ocean intervened. I lived in several extraordinary households and traveled widely in Europe. I sat at the feet (or at least at the tables) of unique savants such as Sol Adler, Rudy Peierls, Joseph Needham, and Jerzy Konorski and acquired several permanent friends particularly Maggie Berkowitz (nee Angus) and Bob Young. I hope to recount these marvelous adventures in the future when there is more time and space.

As Larry’s student I became a permanent if junior member of an extended family studying the behavioral functions of the cerebral cortex. That family included my seniors such as Karl Pribram (Larry’s teacher), Brenda Milner (Zangwill’s student), Mort Mishkin (Hebb’s student and Pribram’s postdoc), and H.-L. Teuber (my postdoc advisor), as well as peers such as Pat Goldman (later Goldman-Rakic) and Charlie Butter. Everyone in this group has always been amazingly friendly, supportive, and collegial to me and I assume to each other.

YOU CAN’T GO HOME AGAIN

Although this is true in profound and trivial ways I often tried to anyhow. I returned to England on sabbatical leaves twice. Both times were to Oxford rather than to Cambridge because Larry Weiskrantz and Alan Cowey had moved there, Larry as head of the Department. The first time, in 1990, Larry had arranged a Visiting Fellowship for me in Magdalen College. I was given magnificent rooms overlooking the deer park. The only problem was that, given the college’s monastic tradition, my wife Greta was not allowed to stay in my room so we had to rent a flat. Conversation at dinner at high table was often very exciting, except when one would get stuck next to a local vicar. I wasn’t supposed to bring my wife there either, although some fellows would just bring each other’s wives as guests. Toward the end, I actually did bring in Greta a few times. They even offered her snuff when we retired to the “dessert” room for brandy. England, with its toleration for nonconformity, often treated women as slightly eccentric men.

On my second sabbatical to Oxford, I was a visiting fellow of Wolfson College. This was a new college consisting only of graduate students and faculty. It had no high table at all, and we were given nice coed rooms. It may have been democratic and nonsexist but, frankly, it was rather dull after the medieval tomfoolery of Magdalen. Besides jogging and kayaking around, I spent valuable time in the Physiology Department’s magnificent history library. I also visited Cambridge for the first time since I had left. The office that I had shared as a graduate student with Alan Cowey and about four others seemed tiny and dirty. This was also true of some of the houses I had lived in. Apparently, things often look smaller when you go back to them, although I was certainly about the same size, if not a bit shorter and wider.

Coming to MIT

Hans-Lukas Teuber

When I received my doctorate in September 1961 and asked Larry from whom I would learn the most on a postdoctoral fellowship, Larry said, “Teuber—he could not stop teaching every time he opened his mouth.” Hans-Lukas (“Lukas”) Teuber had just been appointed the head of a new Psychology Department at the Massachusetts Institute of Technology (MIT). A man of great erudition and charm, Teuber and his colleagues at New York University-Bellevue Medical Center had played a major role in establishing human neuropsychology as an experimental science closely linked with contemporary neurophysiology and experimental psychology. When he came to MIT, psychology was only a section of the Department of Economics and Social Science. It had no undergraduate or graduate program, and very few undergraduates took its courses. Yet it had a number of distinguished psychology faculty members such as David Green, John Swets, Ron Melzack, Roger Brown, and Michael Werheimer. Teuber brought two postdocs from New York University (NYU): Steve Chorover and Joe Altman. They and I went along with Lukas to the psychology faculty meeting as voting members, which enraged the older faculty, a rage directed at Lukas, not especially at us. After a turbulent year, the entire previous psychology faculty had departed, and we were a Department of Psychology with a graduate program and a building of our own, and Altman, Chorover, and I were assistant professors. Walle Nauta was the first senior appointment and probably the first distinguished neuroanatomist in a Psychology Department. Emilio Bizzi, a single neuron physiologist, was another unique appointment, and the philosopher Jerry Fodor was hired as a junior appointment. Our new department was well on its way to becoming the first Neuroscience Department, combining what would be called “cognitive psychology” with neurophysiology, neuroanatomy, linguistics, and computer science and would be a model for neuroscience departments around the country.

A major factor in the growth of the department was Teuber’s extraordinary success in teaching introductory psychology. He was a marvelous lecturer and gave all the lectures twice in the fall and spring term. The course soon became the most popular one in the Institute. Along with some of the junior faculty I taught a discussion section in the class. Although as a naïve and hypercritical purist I was often disturbed by the way he oversimplified and distorted the evidence, pandered to the audience, and graded very easily, I learned an enormous amount from Lukas about how to lecture.

I had come to Teuber to learn neuropsychology: to work with braininjured human patients. He had no access to patients but arranged for me to go over to Norm Geschwind’s aphasia unit at the Boston V.A. hospital to work with Harold Goodglass. Goodglass, understandably, thought I was coming to work on his research whereas Teuber somehow thought I could gain access to the V.A. patients for his own work. So after a few very instructive weeks watching Norm examine patients and Harold and Edith Kaplan give psychological tests and giving a few myself I went back to MIT. That was the end of my training in human neuropsychology.

We had not yet moved into our building at MIT and were in Building 20, a “temporary” three-story wooden structure built in 1943 and a legendary hotspot of creativity. Among our neighbors were Walter Rosenblith’s Communications Biophysics lab with cat auditory physiology and the early use of small computers in neurophysiology, Jerry Lettvin’s frog neurophysiology lab, and Noam Chomsky.

Rat Lesions and Hamster Curiosity

While I was waiting for the monkey colony to be built in the new building, I carried out some studies on brain lesions in rats with Steve Chorover (e.g., Gross et al., 1965). In one we studied the effects of circumscribed cortical lesions on several maze and discrimination tasks. Our results suggested that Karl Lashleys’s finding that the size of the cortical lesion, not its site, determined the size of the deficit in maze learning could be accounted for by the fact that larger lesions encroached more and more on multiple, distributed mechanisms important for different aspects of maze learning.

With an undergraduate Peter Black we measured spontaneous alternation as a function of intertrial interval and found that the hippocampal lesioned rats seemed to learn less but forgot at the same rate as the controls (Gross et al., 1968). This rather clean result got lost in the morass of contradictory results on hippocampal lesions in rats. I was bitten too often by the rats and avoided them in the future.

My first graduate student at MIT was Jerry Schneider, who had never studied psychology before. His wife had bought him a pet hamster but would not let him train it by food depriving it and using food reward, as was the wont of experimental psychologists. So he rewarded it on various learning tasks by letting it run around his apartment for a few minutes. Using this reward he replicated many of the laws of learning as part of his introduction to psychology. We brought 27 nonpet hamsters into the lab and studied the use of exploration as a reward and wrote a paper on it called “Curiosity in the hamster” (Schneider and Gross, 1965). We also carried out some learning experiments on the tree shrew, Tupia glis, and tried unsuccessfully to breed them. Tree shrews were of some interest because they were very visual and were thought at the time, erroneously, to be primitive primates. When I left MIT, Teuber held on to Jerry; and for his dissertation Jerry contrasted, in hamsters, the spatial functions of the superior colliculus with the pattern recognition functions of striate cortex and anticipated Ungerleider and Mishkin’s (1982) deeply influential two visual system idea (Schneider, 1967). I worked with another MIT graduate student, Michael Potegal, on the effects of caudate nucleus lesions in rats and cats.

Beginning to Study the Cortex of the Temporal Lobe of Monkeys

The macaque colony I designed at MIT for about 40 monkeys was based on Larry’s in Cambridge copied in turn from Pribram’s. It made life simple that this colony was exclusively for the use of my students and that we were our own veterinarians.

Discouraged by my inability to understand the frontal lobe, I decided it lay in an inaccessible limbo bearing little relationship to anatomy, physiology, and psychology. (How completely wrong I was demonstrated by Pat Goldman’s [-Rakic] subsequent brilliant application of anatomy and physiology to understanding the frontal lobe.) So I decided to turn my attention to the cortex on the inferior convexity of the temporal lobe: inferotemporal cortex later known as inferior temporal (IT) cortex.

This story begins in 1938 with Klüver and Bucy’s demonstration that temporal lobectomy produces an impairment in object recognition and visual learning as well as a variety of other, somewhat weird, behaviors for a monkey, such as docility, indiscriminate sexuality, and eating ordinarily inedible objects like feces and bolts. This complex of symptoms became known as the “Klüver–Bucy” syndrome. Chow, Mishkin, and Pribram then “fractionated” the syndrome by showing that the changes in visual recognition and visual learning could be produced independently by lesions of IT cortex and that the other changes, like docility and indiscriminate sexuality could be produced by lesions confined to the amygdala, a large subcortical nucleus within the temporal lobe. A number of subsequent studies, particularly from Pribram’s laboratory, showed that the IT deficit in visual recognition is only visual, exists in the absence of any changes in visuo-sensory thresholds, and occurs for a great variety of visual learning tasks as long as they are sufficiently difficult. The IT deficit in visual cognition is similar to human “visual” agnosia, a term first used by Freud. The tale is told in Gross (1973).

At first, it was puzzling how an area so far from striate (or primary) visual cortex could be visual in function. By the time I began my work at MIT it was realized that the visual functions of IT cortex depended on a multisynaptic cortico-cortical input from each striate cortex. Later, it became clear that the monkey’s cortical mantle between striate and IT cortex contained a multiplicity of visual areas now known as V4, TEO, and others.

My initial work on monkeys at MIT involved studying the effect of IT lesions on visual perception and learning (see below; reviewed in Gross, 1973). But then, as this was the time of the brilliant successes of Hubel and Wiesel in using single neuron recording to study visual cortical function, I had the rather obvious thought that single neuron recording might help in understanding the role of IT cortex. But I had never seen a microelectrode or turned on an oscilloscope, so I decided to seek a new postdoctoral position where I could learn the requisite techniques. When I told this to Teuber he said, “don’t go” and offered to pay to set up an electrophysiology lab for me. When I told him I wouldn’t have a clue as to how to use it he suggested I collaborate with George Gerstein, a postdoc in the Communications Biophysics lab at MIT, and he had agreed to do so. George was doing single-unit studies of the auditory system of cats and knew about electrodes and oscilloscopes. Even then he was a pioneer in the development of computer analysis of single neuron activity, having been the first to use poststimulus time histograms.

George and I set out to record from IT cortex in awake monkeys during the performance of visual discrimination tasks because, as he often chanted, “the cortex dissolves in anesthesia.” We decided to begin by recording surface potentials from IT cortex during visual discrimination learning on the grounds (that now seem silly) that this would help us to know what to look for with single-unit recording (Gerstein et al., 1968). At about this time, Herb Vaughan (visiting from Albert Einstein Medical School) and I carried out a study of the effect of optic tract and various cortical lesions on cortical evoked responses (Vaughn and Gross, 1969). Both studies convinced me of the futility of recording gross potentials from the cortical surface, at least in my hands.

In 1964, before we recorded from our first inferior temporal neuron, Gerstein left for the University of Pennsylvania. (This was related to a disagreement with his lab head Walter Rosenblith. They, with others, were involved in developing early laboratory computers such as the LINC-8 and the dispute involved money, power and status.) Because George was now a long-distance collaborator, I decided to radically simplify the planned experiment so that I could carry it out without him holding my hand. The simplest experiment I could think of was just to ask whether IT neurons responded to visual stimuli and to use anesthetized animals. Because Teuber had raised the “double dissociation” paradigm to a commandment, for control stimuli we used auditory stimuli and, for a control area we recorded from the superior temporal gyrus, believed to be an auditory analogue of IT cortex. Soon another postdoc who had also come to work with Teuber, Peter Schiller, joined me. He had been trained as a clinical psychologist and had then done very innovative work on visual masking. (His father was the ethnologist Paul von Schiller and his stepfather no less than Karl Lashley: name-dropping was one of the habits I acquired from Teuber.) Even for the time, our experiment was beyond simple: it was naïve and simplistic. For example, the standard visual stimuli we used were diffuse light, already known to be rather ineffective for cortical neurons. Moreover, the monkey’s eyes were uncorrected and merely covered with a viscous silicone fluid to prevent drying out; the fovea and other retinal landmarks were not located. The animals were immobilized and anesthetized.

By vigorous averaging of the responses to 100 or more stimulus presentations, we managed to get IT responses to diffuse light in about a quarter of our sample; no IT cells responded to the auditory stimuli. We found the opposite pattern in the superior temporal gyrus. For “about 30 units” in IT we did try “moving and stationary circles, edges and bars of light projected on a screen” and found no responses and therefore “an absence of evidence for receptive fields.” We interpreted these results as reflecting one or more of the following: (1) “an organization fundamentally different from that found” by Hubel and Wiesel in visual cortex of the cat; (2) failure to use sufficiently “adequate,” “optimal,” or “appropriate” stimuli; or (3) use of anesthesia (Gross et al., 1967). The unfocused eye was another possibility.

So we decided to return to our original plan of recording from awake behaving animals and, because of some of my concurrent behavioral experiments on IT lesions and attention, to study unit activity during “attention” rather than during visual learning. On Peter’s suggestion, we set up a board in front of the monkeys with little windows to which we could apply our eye or present such objects as a wiggling finger, a burning Q-tip, or a bottle brush, stimuli that elicited attention until the animals got bored. Most of the units responded vigorously to such stimuli, and we classified them as “attention units” because they fired to any stimulus that seemed to draw the animal’s attention, or, at least, any stimulus that would elicit continued fixation at the stimulus as reflected in an electrooculogram. These observations were made on several monkeys and with a number of collaborators, such as Peter Schiller, George Gerstein, and Alan Cowey, my friend from graduate school, and were published over a decade later (Gross et al., 1979). We interpreted these results as suggesting that these neurons either were involved in some attentional mechanism, had foveal receptive fields, or both.

AN ARREST IN THE LAB

My first tech at MIT did everything: brain histology, assistance at surgery, data analysis, training animals in Wisconsin Boxes and automatic boxes. Then, one Friday afternoon, federal, local, and university agents showed up to arrest for her for having sold LSD to an undercover federal agent in the lab. She kept them waiting 2 hours until she had finished an experiment. I found about the arrest only the following Monday morning from a barrage of phone calls from MIT officials as to whether we were making LSD in the lab. When, furious, I asked the other lab members why they had not told me about her arrest, they said, “We assumed you knew all about it … as usual.” That was my first lesson that I would be the absolutely last person to hear about nonscientific happenings in the lab (especially who was sleeping with whom). Later, she was the link to my visiting appointment at Berkeley and still later a Professor of Behavioral Sciences.

On the Harvard Faculty

Just a Visitor

In 1963, I readily accepted an invitation from the Harvard Psychology Department, presumably on Teuber’s recommendation, to teach an undergraduate course in physiological psychology as a part-time “visiting lecturer.” This was the same course in the same lecture room that I had taken with Teitelbaum and that had really got me into the field. Thus, as I mentioned before, it was a very big thrill for me. I worked very hard preparing my three lectures a week, almost every night, most weekends, and any days I was not recording or operating. There were no adequate textbooks then, so all the readings were from primary sources. As this was before the time of photocopying services for course readings I got Harper and Row to publish a three-volume set of some of the reading for the course (Gross and Zeigler, 1969). When good textbooks started to appear such as the third edition of Morgan’s Physiological Psychology (1965) and Thompson’s Foundations of Physiological Psychology (1967), I was really annoyed because they were so similar to my lectures and figures, that I saw no point in trying to publish my own text. I continued to use my lecture notes, with yes, some updates, for the next few decades.

Two woman students came to work with me from Harvard. (They were still called Radcliffe students and given Radcliffe degrees although Radcliffe had had no classes or faculty of its own for the previous decades!). Martha DiNardo, later Neuringer, studied classical conditioning in monkeys with IT lesions for her undergraduate thesis and became a lifelong friend and, after a week with my wife and me on Lake George, she and her husband became permanent outdoor people. Rhoda Kessler came from a Brooklyn workingclass background to Richard Herrnstein’s lab at Harvard. He refused to even talk to her. So I took her on as my student, and she did a thesis on the effect of caudate lesions on behavior in rats. Later, as Rhoda K. Unger she became a major feminist scholar and activist. Her account of the intense gender oppression she was subjected to at the beginning of her career is worth reading (Unger, 1998).

The situation for women in neuroscience has improved since then. Yet, although for some time women have made up a large proportion of undergraduate majors in biology and psychology and of graduate students in neuroscience, they are still markedly underrepresented at the top of the profession as, for example, in the National Academy of Sciences. Attrition occurs at many stages for several reasons (Committee on Maximizing the Potential of Women, 2007). Attrition at the postdoctoral level seems to be particularly related to the conflict between career and child care and could be markedly ameliorated by greater University financial support for child care and a change in the division of function between parents.

At this time I taught my first graduate seminar, which was one of the most exciting I ever ran. The topic was Comparative Psychology. The students were a heady mix of Harvard Skinnerians, MIT Chomskyites and physiological psychologists and included Bill Baum, Alan Neuringer, Laurel Furamoto, Larry Marks, Don Pfaff, and Whitman Richards. I really feel that my undergraduate and graduate classroom teaching was at its best in those early years and then steadily declined, hopefully at a slow rate. Perhaps only at the beginning of my career did I have a grasp of a wide swath of the field, maybe just because the field was so much smaller.

I Move to Harvard

Harvard offered me an assistant professorship in 1965. Everybody advised me strongly against leaving MIT and taking it: you’ll never get tenure, they said (as I very well knew from the department’s past behavior). Teuber was devastated and offered to go the MIT Dean at once to try and get me tenure there. With no hesitancy I decided to take the Harvard offer. The reasons I gave myself were that my life at MIT under Teuber’s protection was not the real world. For example, he had already gotten me onto, successively, two NIH study sections, sent me to represent him at fancy meetings, bought anything I wanted while I had a little NIH grant of my own (for the façade of independence) and what was perhaps most valuable, immeasurably so, he gave me copious suggestions, corrections, and rewrites for the multiple drafts of my papers from my thesis and after. Exactly why I was in a hurry for the real world, and why Harvard in a twisted way was that, I am not sure. The call to Harvard, at least to its graduates, is irrationally powerful. When I decided to leave, Teuber not only would not talk to me but also turned and went in the opposite direction when he saw me. Since, subsequently, I was satisfied with my research and teaching at Harvard, it probably was not an error to have left MIT to go to Harvard, however strange the reasons seem now. As had been the case with my graduate advisor Larry, I greatly underestimated how much I had learned from Lukas. I have written several appreciations of him and his building of the first neuroscience department in the world (e.g., Gross, 1994, 1999).

As I was designing my new monkey quarters for Harvard, two papers came out that claimed memory could be transferred from one rat to another by injections of brain RNA extracted from the first rat and injected into the second. I thought if this were true, maybe I didn’t need monkey cages to study memory. So Frank Carey, my teaching assistant friend from undergraduate days, and I tried to repeat this memory transfer and failed (Gross and Carey, 1965). After an attempt, a few years later, to test an idea of Karl Pribram’s with an undergraduate Phil Schwartzkroin, class of 1968 and Alan Cowey (Schwartzkroin et al., 1969), I finally realized, a bit belatedly, that spending time trying to falsify an intrinsically absurd idea was a waste of time.

Studies on the Temporal Lobe

RECORDING WITH ROCHA-MIRANDA AND BENDER

At Harvard I continued my IT single-unit work now with Carlos Eduardo Rocha-Miranda and David Bender. Carlos was a Brazilian aristocrat who had worked with Madame Denise Fessard and Wade Marshall and really wanted to work with me on developmental visual physiology in opossums not on IT cortex. He later did it with brilliant success and became Brazil’s leading visual neurophysiologist. Dave Bender was the son of a famous Harvard Dean (cf. Karabel, 2005) and had taken my undergraduate Harvard course in physiological psychology. When he came in for a recommendation and I discovered he was an engineering major, I said “You’re hired, start work this afternoon.” Carlos stayed 3 years and then sent some of his former students to collaborate with me. Dave worked with me for about a dozen years as undergraduate, technician, graduate student, postdoc, and research associate. He recently retired as Professor of Physiology at SUNY Buffalo. The three of us worked and argued vehemently for days and nights for those 3 years about everything from where to put a bolt in the relay rack to what it all meant. It was the heyday of Kuhn’s “scientific revolutions” and from the beginning we thought that, for better or worse, we were doing “nonparadigmatic” science.

We were not sure how to test the “some attentional mechanism” hypothesis about IT neurons, so we decided instead to test the “foveal receptive field” idea by trying once more to plot receptive fields in an immobilized animal. This time we used nitrous oxide and oxygen for anesthesia, and we set out to teach ourselves how to use an ophthalmoscope, a retinoscope, find the fovea, use contact lenses, measure expired CO2, etc., etc. The full story of this “learning experience” is some place between a stand-up comedy routine and a morality tale about letting total ignoramuses unfettered into a lab with expensive equipment and monkeys. A few examples. We couldn’t find instructions on using a retinoscope that we could understand. When we asked ophthalmologists about the multiple images we were seeing instead of a single one, they were frightened off, thinking we scientists knew something that they didn’t. (First-year medical students quickly learn to suppress the irrelevant images, I discovered later.) Finally we found a “Flight Surgeon’s Manual” that started: “aim the beam at the center of the patient’s chest, then follow the buttons up”), and we could follow its instructions. One Sunday we accidentally lost a monkey by attaching the air input to the output valve of our new respirator. (At first we thought this taught us a lesson about working on Sundays, but it never stuck.) At the start we used a number of monkeys before we found a single IT cell that we held long enough to see if it responded to visual stimuli. One very important lesson we did learn is never, never argue with your collaborators when sleep deprived. (Pity the poor undergraduates who tried to complain about something as I was staggering home after an all-night-plus recording session.)

Eventually, we got all the many pieces working at once, and lo and behold, IT cells responded to visual stimuli but only in certain parts of the visual field and that part had to include the fovea (which we had eventually learned to find with an ophthalmoscope and then, with a prism, project back onto the screen). That is, we had found that IT cells do have visual receptive fields, and unlike those previously described in other visual areas these receptive fields were not retinotoptically organized and always included the fovea. Their large size was unusual, and it was unique that the receptive fields sometimes extended into the ipsilateral half-visual field. Although light slits and dark bars would sometimes elicit a response from IT cells, we soon realized that more complex stimuli including colored pictures and three-dimensional objects were almost always better in driving IT cells. A few cells responded best to faces and a very few to hands (Gross et al., 1969, 1972). A “hand” cell was found before the first “face cell.” Here is an early description of that finding (Gross et al., 1972):

One day … having failed to drive a unit with any light stimulus, we waved a hand at the stimulus screen and elicited a very vigorous response from the previously unresponsive neuron. We then spent the next 12 hr testing various paper cutouts in an attempt to find the trigger feature for this unit. When the entire set of stimuli used were ranked according to the strength of the response that they produced, we could not find a simple physical dimension that correlated with this rank order. However, the rank order did correlate with similarity (for us) to the shadow of a monkey hand. (pp. 103–104).

There was no mention of the “hand unit” in the draft of our 1969 Science article when I asked Teuber to read it, in part because of how helpful he had been with my previous papers and in part to help “make up” for abandoning him for Harvard. He knew about the “hand cell” and urged us to put it in the article and we did.

WHY WE FOUND FACE AND HAND CELLS

The stimuli we soon began to commonly use to elicit responses from IT cells, namely, brushes, faces, hands, feathers, pieces of fur, and other objects, were far from the usual visual stimuli of the time like bars and slits. Why did we use them, and more important why were we primed to notice responses to such stimuli? There were several factors that probably lowered our threshold to use such stimuli and to find cells responding to them.

First, a few years earlier I had been the guest of the Polish scientist Jerzy Konorski who was unusual in being both very smart and very knowledgeable about human clinical neurology and visual physiology and animal learning and the cognitive effects of lesions in monkeys. Integrating data from these fields he had postulated the existence of “gnostic neurons” such as ones selective for faces, facial expressions, body parts, simple objects, or scenes and had suggested they would be found in inferior temporal cortex (Gross, 1968; Konorski, 1967).

Second, we had begun these IT studies at MIT in the department of neuropsychologist Lukas Teuber who would often tell stories about prosopagnosia (agnosia for faces) after temporal lesions.

Third, our first lab at MIT in Building 20 was down the hall from Jerry Lettvin’s lab. He was working on bug detectors in the frog (Lettvin et al., 1959) and had invented the term “grandmother cell (Gross, 2002). It was Horace Barlow (1953) who first used the term bug detectors, and I had heard him lecture on the subject when I was a student in England.

Finally, we were in the same institution, if across the river, from Hubel and Wiesel who had just published on hypercomplex cells in V2 of the cat and had suggested that cells with even more complex properties would be found beyond V2 (Hubel and Wiesel, 1965).

Thus it is not surprising that we found face and hand cells in this environment! What is surprising is that for some time our findings on the unusual receptive field properties of IT cells and our finding of face and hand-selective cells seemed to have little or no impact on the field. Although we published in such high profile places as Science and the Journal of Neurophysiology there were no attempts to replicate and extend (or deny or even comment in print on) any of our results until 12 years after our initial paper. One of the reasons for the skepticism or sheer disbelief in our results may have been because of our somewhat sparse use of quantitative methods, objective data collection, and mechanical stimulus presentation. Another reason may have been our use of even more unconventional stimuli than hands and faces, such as a toilet brush, a picture of which we had published (Gross et al., 1977). The editor had demanded we remove the figure with the toilet brush so we just eliminated a different figure and renumbered the remaining ones. I am still not sure why oval-shaped toilet brushes were often good stimuli for IT cells. One suggestion was that it was because all the experimenters had beards. One of the very first groups to finally test and replicate some of our basic findings successfully used a toilet brush too (Richmond and Wurtz, 1982).

Whatever the skepticism about our claims, it did not seem to interfere with our ability to get published or to obtain grant support or jobs. When replications of “hand” and “face” first appeared they were by two Brits, Edmond Rolls and Dave Perrett who were considered “a bit flakey” themselves by many in the field, perhaps further delaying general acceptance of our findings (Perrett et al., 1982).

Are the face and hand cells found in IT cortex examples of the “grandmother cells” of Lettvin (in Barlow, 1995), cells that respond only to a specific visual concept, such as your own grandmother “however displayed, whether animate of stuffed, seen from behind, upside down, or on a diagonal, or offered by caricature, photograph or abstraction”? Are they examples of the “gnostic” cells of Konorski (1967), neurons that represent “unitary perceptions”? The available evidence provides an overwhelming “no” to both possibilities. IT cells that respond only to a specific object, such as the face of one individual, and continue to do so across various transformations have never been seen. Rather IT face cells respond in varying degrees to a set of faces and never solely to one. Different IT cells show a different pattern of responses to a set of faces. Thus the coding of faces (and presumably other objects) appears to be done by the pattern of firing over a set of cells, that is, by what has been termed “coarse coding,” “ensemble coding,” “population coding,” or “cross-fiber pattern coding.” This absence of one cell–one visual concept is true for both natural stimuli such as faces as well as for arbitrary stimuli that evoke responses of IT cells after explicit training (Gross, 1992, 2002).

However, something closer to true grandmother cells may exist elsewhere than monkey IT cortex. Quiroga et al. (2005) reported cells that certainly seem to fit the criterion for a grandmother cell in the medial temporal lobe of human patients. For example, one such cell in the hippocampus fired only to a variety of images of one individual (known to the patient) including in various costumes and views and even to her name in letters and not at all to images or names of a number of other individuals also known to the patient.

BEHAVIORAL EFFECTS OF IT CORTEX LESIONS ESPECIALLY WITH ALAN COWEY

Starting at MIT and continuing at Harvard, we carried out a number of experiments on the behavioral effects of IT lesions parallel to the single-unit recording experiments. One series was carried out with Alan Cowey, who came from Cambridge to Harvard for a year, and Harvard graduate student Rick Manning. We compared the effects of lesions of Area TE (or anterior IT cortex) with those of a more posterior region area we called “foveal prestriate cortex” (a combination of Area TEO and what is now known to be the central representation of visual area V4). We thought the results indicated that the more anterior lesion affected primarily visual memory and the posterior lesions impaired visual perception (e.g., Cowey and Gross, 1970; Manning, 1971; Manning et al., 1971; reviewed in Gross, 1973). Although this idea, deriving from Mort Mishkin (Iwai and Mishkin, 1969), is still widely accepted, it is only a first preliminary step in understanding the role of the temporal lobe in visual recognition.

Earlier experiments, largely from Pribram’s lab, had failed to find effects of IT lesions on visual acuity, visual perimetry, or critical flicker frequency. My very long time collaborator, Dave Bender (1973) extended these findings of no sensory losses after IT lesions by finding negative effects on backward masking and on detection of a brief stimulus.

One of the major subcortical outputs of IT cortex is to the caudo-ventral putamen. To see whether it was part of a circuit involved in visual pattern recognition Al Buerger, a postdoc, Carlos, and I studied the effects of its destruction on visual and auditory learning and a delayed response task. Its damage only impaired visual learning, supporting the idea that the caudo-lateral putamen is part of a circuit specific for visual pattern learning (Buerger et al., 1974).

Marlene Oscar-Berman, a postdoc in my lab and Simon Heywood, a graduate student from Oxford, showed that animals with IT and prestriate lesions during visual discrimination tasks look longer at one stimulus and switch less frequently between stimuli, perhaps because they have trouble recognizing it (Oscar-Berman et al., 1971).

The Psychological Round Table (PRT)

After a few years at Harvard I was invited to become a member of the Psychological Round Table (PRT). This was a secret, self-perpetuating club who seemingly thought themselves the best and the brightest psychologists under age 40. It had been founded in 1936 as a Young Turk rebellion against the elite Society of Experimental Psychology founded by Titchner in 1904. When I was elected, PRT was all male and consisted almost entirely of experimental psychologists, mostly from Harvard, Yale, Princeton, Penn, McMaster, and a few other Eastern schools. There was no program distributed; you had to be prepared to give your talk (“revelation”) at any moment. The discussion was superficially “lively” but usually more jocular than serious. The gavel was a brass penis and testicles. The big event was the Saturday night lecture that was, to be generous, rather crude pornography, slides of women in various states of undress. Later, slides of various varieties of sexual activity became more common.

In the late 1960s I stopped going on the grounds it was sexist and antidemocratic but never really communicated my views to the membership. I returned in 1974 with Naomi Weisstein, a distinguished perception student and militant feminist, to raise these issues. By this time there were woman members, the officers were still self-perpetuating but known, and there was a greater range of departments represented. The Saturday night porno lecture continued often with woman speakers and male genitalia. Members were still expected to be quiet about the organization.

Many PRT members were really upset when they heard I was planning to write an article on it (Gross, 1977). They felt I was trying to destroy “the most important intellectual event of the year” for them. PRT presumably helped me get my job at Princeton because at that time, I think all the tenured members of the Princeton Department under age 40 were members. In 1994 I was elected to the grown-up version of PRT, namely the Society of Experimental Psychologists. Now it was all right to put membership on your resume, because, I guess, when you’re old it’s acceptable to announce you’re a member of an “elite” club. I have gone only to the two meetings that were held in Princeton. There were no porno lectures.

Antiwar Activities and the Harvard Strike

My time teaching at Harvard coincided with rising protests against the Vietnam War. Although my anguish and anger over the war filled a not small part of my consciousness, my antiwar activities were pretty trivial compared to those of many around me. I was active in the Boston Area Faculty Group on Public Issues (BAFGOPI), which organized teach-ins, marches, and demonstrations and raised money and signatures for advertisements against the war. Our leader was Salvador Luria who was the most marvelous combination of a Jewish and Italian comic besides having won a Nobel Prize. Although I went to many antiwar events and had members of various student antiwar groups in my lab, I knew little about what was brewing among student leaders.

On about noon, April 9, 1969, a group of students led by SDS (Students for a Democratic Society) “occupied” University Hall, central home of the Harvard deans, and they and their staff left or were pushed out. Many students milled around the occupied building or entered it out of support. By 4:15 Franklin Ford, the Dean of the faculty, over a loud speaker had announced “anyone failing [to depart] will be subject to criminal trespass.” When I had entered in my professorial tweeds, someone rushed over and yelled, “Get this faculty member out: he will report our names.” Somebody with more clout, apparently, said, “Don’t worry. He can stay. He’s just a ‘CP-liberal’.” And so, after all these years being semicloseted as a clandestine red diaper I was suddenly a “Communist Party-liberal,” the SDS leadership being so far left that the difference between the “old left” CP and a liberal was insignificant.

There were about 400–500 students and a few faculty members in the Hall. Assembled in a large, packed room, the group voted nonviolence toward the police, decided to leave the doors open, and set up various rules and committees to get food, keep things clean, and other housekeeping on the general assumption that, as at Columbia University the previous year, the occupation would go on for days. Finally, the meeting was over, and most of the crowd left for their rooms, planning, as I did, to come back the next day to the occupied building, now “Che Guevera Hall.” I drove home to work on my next day’s lecture. About 150, including some teaching fellows and one faculty member, stayed overnight.

At dawn Over 500 helmeted and face-shielded police came in swinging. About 50 students required medical attention, some for serious injuries. The student body was outraged, and an overwhelming majority eventually supported a total strike demanding the end of ROTC, stopping Harvard expansion into poor neighborhoods, establishing a Black Studies Department, and not punishing the building occupiers (collectively known as “the eight demands”). Much of rest of the term was spent in interminable meetings, from small faction planning groups to an estimated 10,000 assembled in Harvard stadium. The faculty was split into a “conservative” and a “liberal” caucus. Stephen J. Gould, then another assistant professor, and I were in a minuscule “radical” caucus led by Hilary Putnam, perhaps the leading philosopher of the day. We essentially supported the SDS positions. As a group we even walked out of the Commencement exercises. We were so inconsequential that I could not even find us mentioned in the several detailed histories of the strike I examined recently (e.g., the even-handed Eichel et al., 1970 and the conservative Rosenblatt, 1997).

There was a great flowering of strike art and rhetoric. One poster summed it up:

STRIKE FOR THE EIGHT

DEMANDS STRIKE BE

CAUSE YOU HATE COPS

STRIKE BECAUSE YOUR

ROOMMATE WAS CLUBBED

STRIKE TO STOP EXPANSION

STRIKE TO SEIZE CONTROL

OF YOUR LIFE STRIKE TO

BECOME MORE HUMAN STR

IKE TO RETURN PAINE HALL

SCHOLARSHIPS STRIKE BE

CAUSE THERE’S NO POETRY

IN YOUR LECTURES

STRIKE BECAUSE CLASSES

ARE A BORE STRIKE FOR

POWER STRIKE TO SMASH THE

CORPORATION STRIKE TO MAKE

YOURSELF FREE STRIKE TO

ABOLISH ROTC STRIKE BECAUSE

THEY ARE TRYING TO SQUEEZE

THE LIFE OUT OF YOU STRIKE

-poster by striking students at Harvard Graduate School of Design.

During the summer, when no one was around to protest, about 15 SDS leaders were expelled or otherwise punished, and the one faculty member arrested in the building was fired. In the longer run, the University mostly met all the “eight demands.”

A moment of activist glory came a year later on May 5, 1970, when I cochaired a mass meeting to protest the U.S. invasion of Cambodia. Over 3000 convened in Harvard’s four large lecture halls linked electronically. The meeting voted to strike against the Southeast Asia war, the oppression of political dissidents, particularly the Black Panthers, and the multiple involvements of universities in the war. The Harvard Crimson said, “The chairmen generally succeeded in keeping the heated meeting in order.” My picture was in the upper left of the front page; on the lower right was the now iconic woman with outstretched arms over the dead body at the Kent State shootings by the National Guard the previous day.

Getting Fired from Harvard

In 1970, as expected, I did not receive tenure at Harvard. The previous year my title had changed from assistant professor to lecturer so maybe I was at risk of becoming a graduate student again. My years at Harvard had been very good. I had superb students and plenty of space. Originally, I was given space for a monkey colony and a few rooms and offices. But as a senior appointment in physiological psychology was never made, I expanded until I occupied the entire eighth floor of William James Hall except for the shops, which we were the principal users of anyhow. I taught what I wanted when I wanted. I had no committee assignments or administrative duties. Not only did I not feel obliged to suck up to the senior faculty but I had little contact with them. They never came on my floor, and there were no social occasions.

The only time I saw the senior faculty was at the monthly departmental meeting, and those were always entertaining. B. F. Skinner was constantly feuding there with S. S. Stevens, the founder of modern psychophysical scaling. Both spoke only the hermetic jargon each had created so no communication was possible. George Miller, a past-president of the American Psychological Association who had among many other accomplishments introduced computers to psychology, cofounded cognitive psychology, and started experimental psycholinguistics, had been a Harvard graduate student so the older faculty continued to treat him as one. (Later, he became my colleague at Princeton and was a close friend and mentor of my high school age son.) Georg Von Bekesy who received a Nobel Prize for his work on audition couldn’t even come to the meeting because he did not have a teaching appointment. He would have liked a professorship, but I doubt if he cared about the meeting. The chairman when I arrived was E. B. Newman who wasn’t even deemed worthy of a professorship but was a lecturer. One day he turned to another assistant professor (who was an ordained rabbi) and asked, “What do you people do with sour cream? Pour it over your head?” That this remark continues to rattle around in my head suggests I am still sensitive to anti-Semitism.

I did have some trouble with Richard Herrnstein, who was the chairman for most of my sojourn at Harvard. He was a Skinnerian who had written an inflammatory racist article in the Atlantic Monthly and later expanded it into a book, The Bell Curve, with Charles Murray. He was on the floor below me, and the waste plumbing from my monkey colony occasionally leaked into his lab and some of my rats escaped to his office. Off Harvard grounds he did secret research for the Army, teaching pigeons to recognize Viet Cong and radio their location back to airbases. Whereas I thought his racist writing was well within his academic privilege, I made it clear that I thought his secret research put him in the category of a war criminal. (This was at the height of the Vietnam War.) Luckily, my secretary, Maureen Ashby, was a tony Cantabrigian M.A. that intimidated him, so she dealt easily with him and I never had to.

Berkeley Interlude

Although I had been appointed Professor of Psychology at Princeton in 1970 I did not arrive until 1971. I spent the intervening time as the guest of Walter Freeman in the Department of Physiology and Anatomy in Berkeley (and with the help of an NIH fellowship). He was the son of the Freeman that brought us outpatient frontal lobotomies with an ice pick; he was a great guy as well as an early prophet of computational neuroscience. My first contact with him had been when he had called me for help with my first tech at MIT (the one arrested in the lab) who was now working for him. She had been arrested again, this time for possession of marijuana and had used her one phone call to tell him she would not be in to get the cat ready for the day’s experiment. He needed my help for her bail because all his cash was tied up in bail for anti-Vietnam War demonstrators. (In the end, a third phone call got her mother to bail her out.)

There were many things surprising and wonderful about Berkeley. It was really puzzling how Berkeley could be invariably rated as one of the two or three greatest research universities in the country (or world) when, as far as I could see, the faculty spent hours daily eating fabulous lunches at outdoor cafes. Maybe it was a Heisenberg uncertainty problem: they were only sitting around in the sun drinking Chardonnay because they were entertaining me.

Politics in Berkeley, at least to a visitor like me, was like Nirvana. The day we arrived there was a massive demonstration at city hall demanding 24/7 free child care. It was less weird when I discovered the City already provided more child care than virtually any U.S. municipality does even today. The City Council was dominated by the left with nary a Democratic let alone Republican member. When we had visitors the first tourist stop was the COOP, the first food store we had ever seen whose primary purpose didn’t seem to be to steal your money and make you obese or otherwise ill. It is gone now, but stores across the country now try to imitate it. I did my first and last door-to-door political canvassing for a major party candidate, Ron Dellums, the long-time Congressman from Berkeley and now mayor of Oakland. Life in Berkeley deserves another memoir, especially if I have to go back for data. When I left, my friends gave me a little sachet of dirt labeled “holy soil.” I still miss the place (and the time).

At Princeton University

Getting Arrested

One of the first things I did at Princeton, or, at least, one of the first memorable things, was to get arrested at an anti-Vietnam War event. It was for trespassing on the grounds of the Institute for Defense Analysis (IDA), a federally funded think tank on campus that carried out war-related secret research. That day 225 demonstrators including seven Princeton faculty were arrested and charged with “interfering and molesting.” As we filed into the Trenton courthouse, one cop, on seeing me said to the cop standing next to him, “Hey, there’s an old one.” And I was in my mid-thirties! We were released after paying $100 bail. Most of us eventually paid $100 in fines; a few, not me, instead went to jail for 10 days.

Although my father asked a bit nervously what my colleagues thought of my arrest, he seemed more proud than anxious and stopped asking me to wait. I am embarrassed to say, that when later I obtained my FBI files under the Freedom of Information Act, the arrest in Princeton was the major item. I guess I had taken my father’s advice.

The afternoon after the arrest, Mother’s Day, I chaired a mass (for Princeton) “Mother’s Day Rally/Teach In for Peace.” In preparing this memoir, I found my opening statement:

Today is mother’s day and this meeting is dedicated to the millions of mothers who have been murdered and maimed by this horrible war, who have seen their children and husbands destroyed, burned and tortured, who have experienced the devilish ingenuity of American technology—the bombs that flatten the area of football fields and the plastic flechetes that defy x-rays, designed by our own IDA and finally to the mothers who for countless generations will bear misshapen monsters due to the genetic effects of the defoliants sprayed by American planes.

There doesn’t seem to be many rallies against the Iraq War in Princeton.

Another Monkey Colony

At Princeton, for the third time, I set up a monkey colony. As at MIT and Harvard, for about the first 15 years at Princeton, we handled all aspects of the colony ourselves and very rarely called for veterinarian help. Then the University hired a “consulting veterinarian” who stopped in occasionally and eventually took over supervising the cleaning of the colony. More recently a full-time University vet was hired and then an “animal facilities manager.” These steps were due to increasing regulation of primate facilities by the federal government and more recently the stricter Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC). The animals and experimenters may or may not be better off now, but life was certainly much simpler in the old days.

Life In My Lab

Perhaps the greatest satisfaction in my scientific life has been the success of so many of the people who spent time in my lab at MIT, Harvard, and Princeton. Of course, to what extent their success was due to entirely to their own efforts and to what extent due to the environment we created is impossible to assess. What is clear is that my success depended on their efforts.

LAB TECHS

The group I am really most proud of, and perhaps most unjustifiably, are the women who worked as lab techs. Many had not been biology or psychology majors. After a few years in my lab, most of them went to graduate school and are now accomplished figures in neuroscience research. This cohort includes Charmane Eastman, Rush University, Laura Frishman, University of Houston, Christine Curcio, University of Washington, Vicky Ingalls, Marist College, and Susan Volman, NIH. I doubt if my record of techs into full professors has often been surpassed, even today. A few went into medicine and are on medical school faculties such as Carolyn Wells, Yale, and Lynn Seaford, Washington University. I would not be writing this memoir except for their intelligence, competence, and loyalty. The only explanation I have for this high yield is that I was so incompetent, bumbling, and all thumbs in the lab that they thought if I could get by in neuroscience, they certainly could. It might be noted that during most of this period there were initially almost no women and then very few tenured women at the institutions I was at and only a very few senior women in all of neuroscience.

GRADUATE STUDENTS

I have had only a small number of graduate students, and never more than two or three at a time. Fortunately, the universities I was at often attracted good graduate students, even when, as was the case at Harvard, the only neuroscientist on the faculty (outside of the medical school in far away Boston) was one unknown starting assistant professor (me). I did spend a lot of time and energy recruiting and selecting graduate students. They usually spent 2 or 3 days visiting my lab, including hanging out during long boring experiments. They often stayed at my house and visited twice, before and after they were admitted. Several had worked in my lab as undergraduates or technicians. Thus by the time the prospective students and I had to make our decisions to commit to each other, we had more of an idea of what we were in for than is usually the case. For whatever reasons, virtually all of my Ph.D.’s have been professionally successful and continue to do neuroscience. So far, they include two members of the National Academy of Sciences, two members of the American Academy of Arts and Sciences, two National Academy of Sciences Troland Awardees and one former Howard Hughes Professor. (The weaker graduate students I may have driven out by my sarcasm or something.)

At least by the time I was at Princeton certain customs were established. On their arrival, I would tell the new student what was going on in the lab and provide a copy of the last grant. In the next few weeks, they would usually choose to work with an advanced graduate student or postdoc on an ongoing project. Starting their own project before they knew how to do anything usually did not work. The senior and junior students would then publish together and then either continue collaborating or, more often the formerly new student would find his or her own project, later to be joined by a new incoming student.

We had weekly lab meetings for at least 90 minutes over lunch (during one decade everybody ate quarts of yogurt) that took priority over experiments, surgery, life, everything. There we would take up proposed experiments, recent results, paper drafts, new directions, papers, and grants that I was given to review, critiques of a recent speaker and if there was nothing else, some recently published papers. Frank critiques, often rather brutal, were the tradition, especially with regard to new experimental proposals and interpretation of results. Meetings were often heated, which, at least I thought, was really healthy. (Sometimes visitors were shocked by what they perceived to be sibling rivalry, hostility, and excessive competition.) Usually I would work with a student alone in preparation for the meeting and then again after the meeting to pick up the pieces, if needed. Administrative things like ordering animals and equipment, scheduling surgery were dealt with and the tech often had “who left the mess?” business. During a dull experiment I once complained to a student that the Iliad was a bloodthirsty bore. He replied, that, on the contrary, the story of Achilles was a key to understanding a certain arrogant and difficult colleague. So we spent the next lab meeting on the Iliad, and he convinced me of his point.

There were separate sessions for practicing talks, especially because sessions for job and other long talks often went on at great length. For some students a single session with little comment was enough, whereas some otherwise equally good students would require a dozen sessions to mold a job or colloquium talk into shape.

Someone leaving the lab, getting his or her degree, or my birthday were occasions for spit roasting a goat, pig, or lamb in my backyard. This was an all-day affair with much basting and drinking. Over the years we had lab expeditions to the White Mountains (when we were in Boston), canoeing on the Delaware, camping on Lake George, hiking from my house in Woodstock, N.Y., and, lately, often to the local authentic Szechwan restaurants.

I really understand nothing about being a student in my lab, but some hints come from their comments:

“When I came to Charlie’s lab it was like another, very different world unlike anything I had previously experienced or heard about.”

“Charlie does not just work with you; he moves in with you.”

Sometimes the students would come in to carp. Once a male in jeans, sandals, and work shirt came in to complain about a female graduate student’s outfit of heavy makeup, high heels, long red fingernails, etc. being inappropriate for a monkey lab. I told him, perhaps too vehemently, (1) that in my day no one in his outfit and without their tweed jacket etc. would be allowed in the lab, (2) that it was none of his business what anybody wore, and (3) to get out of my office. I think I did complain about students walking around the lab and in the monkey room barefoot. Now, under current rules, my normal clothing prevents me from even entering the animal quarters.

POSTDOCS, VISITORS, AND UNDERGRADUATES

About half the people who got doctorates from my lab stayed as postdocs (and then sometimes research associate or lecturer) for 1 to 15 years, about 4 years being the mode. I would joke that this was because they had learned so little in the first 4 or 5 years, they would try again. In fact, it was a great deal for them because by this time they were usually working and publishing independently, and I was doing the fund-raising, housekeeping, supplying them with tech help or eager undergraduates, teaching and dealing with the world. Several people came back to the lab after a few years of graduate student or postdoc experience elsewhere (3 days in one case), usually claiming they had more freedom in my lab. I also had several great postdocs who had not been my graduate students.

I was really lucky to have super faculty visitors who stayed from 1 to 3 years and usually returned for shorter periods such as Alan Cowey, Carlos Rocha-Miranda, Ricardo Gattass, and Charlie Butter. Besides collaborating with me on experiments they played a very major role in training, keeping me and the students sane, and helping run the place.

A number of undergraduates researched in my lab and some first authored papers. Of course, many students in my undergraduate classes became successful at whatever, including neuroscience, but that has little to do with me and more with the good students that MIT, Harvard, and Princeton had gathered.

AUTHORSHIP OF STUDENT PAPERS

The basis of assigning authorship was never explicit, but in practice was someplace between that of my undergraduate advisor Don Griffin and what is common today. Griffin never put his name on any of his students’ research papers, and they were only coauthors when they helped with Griffin’s own research. What seems common today is that every paper that comes out of a Principal Investigator’s lab or was supported by his or her funds gets the P.I.’s name on it. About 20% of the papers from my lab did not have my name on them, usually because they were from a student’s thesis, by a postdoc, or because I had little involvement.

GRANTS

I always enjoyed writing grants. It was a very intense and very social cooperative effort with all members of the lab involved. The main support for the lab came from a single NIH grant started in 1964 and renewed about every 5 years through 2004. We would usually start working on the renewal 3 months before it was due. I managed to expand the scope so that in its last year it was supporting, among other things, research on parietal and premotor cortex, adult neurogenesis, functional magnetic resonance imaging (fMRI) on monkey temporal lobe, and, as usual, some neuroscience history. Sometimes there were ancillary grants from NSF, NIH, or private sources, sometimes with postdocs as the PI. The role of my students working on my grants is reflected in the fact that their own early grants looked just like mine even when very different in content (just as when visiting their labs I saw reflections of mine).

The first Study Section I sat on was exclusively for psychology fellowships. A small group of us, particularly Colwyn Trevarthan, would delight in awarding people who looked promising and had no relevant background at all, especially none in psychology. Some are now successful neuroscientists. The second Study Section I sat on was for research grants and more serious. When Roger Sperry joined, I hoped I would find out how the brain worked. But it turned out his ratings were simply inversely proportional to the budget and the only equipment he thought worth buying was a dissecting microscope. By my third Study Section I was already a tenured professor and could not understand many of the applications. So thereafter I usually refused to serve on Study Sections as it was a bit depressing to realize how out of it I seemed to be (or less likely, how misguided the field was).

Research in My Princeton Lab

When I was at MIT and Harvard I was willingly to be the advisor for undergraduate or graduate research on a wide range of topics as long as the student was really enthusiastic and the project seemed feasible. Thus, besides monkeys, we worked with iguanas, owls, rats, hamsters, tree shrews, and cats. At Princeton I became more focused (or narrow) and would usually only support experimental research on brain mechanisms of vision or memory.

Major exceptions were when I collaborated with other faculty particularly Marc Bornstein on babies and Liz Gould on adult neurogenesis and in advising undergraduates. All Princeton undergraduates have to do an experimental or “library” thesis. Given that Princeton is inundated by jocks, I supervised (too) many library theses by women on exercise-induced amenorrhea and by men on traumatic amnesia.

Recording from the Temporal Lobe

How does visual information reach IT cortex? In collaboration with Mort Mishkin, we showed that the visual responses of IT cells depend on input from striate cortex over a route that includes the corpus callosum and anterior commissure (Gross et al., 1977; Rocha-Miranda et al., 1975). By contrast, lesions of the inferior pulvinar, which might have provided an alternative pathway for visual information to IT cortex did not eliminate IT responses to light. We also continued our studies in awake monkeys trained in visual discrimination and on Konorski’s “recent memory” task. We found that the activity of about half the IT cells sampled reflected the animal’s recent experience; the IT cells were coding short-term memories (Gross et al., 1979).

BORDERS OF IT CORTEX

The first new graduate student to work on IT neurophysiology at Princeton was Bob Desimone, who came in 1974 and then stayed, eventually as a postdoc until 1980. A few days after he arrived he came into my office and told me the various ways the running of the lab could be improved. Eventually that skill made him the Scientific Director of the National Institute of Mental Health and then the Director of the McGovern Neuroscience Institute at MIT. He showed his dedication to science equally early. He was learning to perfuse a monkey over a sink and had forgotten to take out its contact lenses, which then went down the drain. As Dave Bender, who had been teaching him later reported to me, “Desimone will do. He took apart the whole plumbing of the sink until he found the contact lenses, then put it back together.”

Previously, we had sampled from only a limited portion of IT cortex. Desimone developed methods for repeatedly recording from the same animal when immobilized and anesthetized that enabled him to sample the visual properties of neurons throughout the temporal cortex. He found that the basic properties of IT neurons, as described above, were similar throughout cytoarchitectonic area TE: receptive field size, inclusion of the fovea, laterality were all similar. However when moving dorsal, ventral, or anterior to Area TE the cells were no longer only visual but were polysensory: they were always visual but sometimes also responded to auditory and/or somesthetic stimuli (Desimone and Gross, 1979).

SUPERIOR TEMPORAL POLYSENSORY AREA AND BIOLOGICAL MOTION

Charlie Bruce (postdoc, 1977–1979), Bob and I then studied the area dorsal to Area TE, which we termed the “superior temporal polysensory” area or STP. Neurons in STP had several intriguing visual properties. Like IT neurons they were not retinotoptically organized but had larger receptive fields. Like in IT cortex, some responded best to faces. Most were sensitive to some type of motion including complex movements such as in depth or radially symmetric about the center of gaze or more extraordinary movements, as in this description from the original paper (Bruce et al., 1981).

a person walking within the visual field was more effective than any other stimulus tested … the pattern of movement generated by walking and not the person per se was crucial … a person seated in a moving chair or a person walking with the lower part of the body shielded elicited little or no response. Inanimate moving objects also elicited little or no response. The angle subtended by the person … and the persons … size and clothing were also irrelevant. Half of these units responded preferentially to particular directions of walking. (p. 374)

This was the first published description of neurons sensitive to “biological motion.” For some reason we never explored this phenomenon much further, devoted only a few sentences to it, and didn’t even mention it in the paper’s abstract. Dave Perrett and his colleagues, at St. Andrews, soon replicated and greatly extended these observations (e.g., Perrett et al., 1989). Much later, in a collaborative effort with Lucia Vaina of Boston University and Harvard Medical School, we had evidence for a similar superior temporal area in humans involved in biological motion (Vaina and Gross, 2004).

Another unusual property of many superior temporal polysensory (STP) neurons was their multisensory responses: responding to sounds and/or touch as well as visual stimuli. Later Earl Miller (graduate student, 1985– 1990), and Carol Colby (postdoc, 1983–1989) had evidence that the visual and auditory responses were correlated. Bruce, Desimone, and I found that the properties of STP depended on striate cortex and the superior colliculus, unlike IT cortex, which is totally dependent on its striate input (Bruce et al., 1986.)

Perhaps the reason why we never further studied the biological motion and polysensory properties of STP is that we already had enough “unbelievable” results on face and hand cells. In retrospect, it was a mistake not to have done so.

MORE FACE CELLS AND STIMULUS INVARIANCE

As I mentioned above, most of our early evidence for face and hand cells might be thought of (especially by hard-core visual physiologists) as rather informal. Finally, in 1984, Desimone, Bruce, and Tom Albright (graduate student and postdoc, 1979–1987), and I submitted a more quantitative description of face and hand cells to the Journal of Neuroscience (Desimone et al., 1984). The editor, Max Cowan, rejected it on the grounds that these phenomena had been reported, and this paper was nothing new. I wrote back telling him to just view the paper as a replication of previous results, which would be useful because no one had believed them. He accepted the paper by return mail without comment. That and an earlier paper with Eric Schwartz, then of NYU, Bob, and Tom also showed that IT cells showed invariant responses to shape over changes in size, contrast, or retinal location (Schwartz et al., 1983). The cells acted like perceiving organisms!

INFANT MONKEYS

Are monkeys born with face cells or do they develop them with experience? Hilary Rodman (graduate student, 1981–1986; postdoc etc., 1986–1989; 1992–1995) and I received a grant to study this. We were going to raise monkeys from birth without their seeing faces and then determine if they had face cells. We had solved all the technical problems but could not bring ourselves to actually deprive infant monkeys of seeing faces. So instead with Jim Skelly (graduate student, 1985–1990, later renamed Seamus O’Scalaidhe) we studied normally raised infants and found face cells as early as 6 weeks of life that was as early as we could record in awake monkeys (e.g., Rodman et al., 1991, 1993).

One of the difficulties of working with monkeys was that it was very upsetting to me and most lab members when a monkey died or had to be “sacrificed” at the end of an experiment to locate its electrode tracks or lesions. It was particularly traumatic when an infant monkey died.

I also worked with C. Y. Li on face cells in infant monkeys in Princeton and in his lab in Shanghai. Going to work each day in a Shanghai lab as I did on one sabbatical or teaching in Peking University on another added a dimension to being in China besides that of the usual tourist. Overall, over seven visits I traveled around China for a total of many months by boat, bus, truck, four-wheel drive, plane, bicycle and worst of all, horseback, including to Tibet, Inner Mongolia, Xinjiang, the borders with Vietnam and Burma, visited innumerable temples and monasteries, climbed several holy mountains, and ate a lot of really great street food.

LEARNING AND CIRCUIT PROPERTIES OF IT CELLS

Paul Gochin came as a postdoc (1987–1995) from my old collaborator George Gerstein, thereby reviving our joint efforts. With Earl Miller, a graduate student (1985–1990), we studied the circuit properties of IT neurons and their ensemble coding (e.g., Gochin et al., 1991, 1994). Paul also wrote a number of modeling papers on IT cortex (e.g., Gochin, 1996). Paul and Earl carried out several innovative studies on the attention and habituation properties of IT cells (Miller et al., 1991, 1993). Earl later expanded this work into an important series of studies when he went to work with Bob Desimone at NIH. Earl was an unusual graduate student because he never stayed as a postdoc. Instead, he went to work with Bob Desimone who had moved to NIH, but maybe that was a little like staying in the lab.

IT AND HIPPOCAMPAL NEURONAL ACTIVITY DURING SHORT-TERM MEMORY

Mike Colombo (Rutgers graduate student; Princeton postdoc 1989–1992) compared the responses of IT and hippocampal neurons during visual and auditory short-term memory tasks and examined the role of activity in the delay period as a possible “mnemonic trace” (Colombo and Gross, 1994). Later, with Tom Fernandez a class of 1992 undergraduate, and Kotuku Nakamura, a postdoc from Japan, we found that the posterior hippocampus tended to be more involved in spatial processing and the anterior hippocampus in directing movements to points in space (Colombo et al., 1998).

ON AREA MT

Area MT, the middle temporal area, is an extrastriate cortical visual area that was known to be particularly sensitive to the direction of stimulus motion. As a graduate student and a postdoc, Tom Albright made major contributions to understanding its organization and functions. First he demonstrated that MT was organized into cortical columns sensitive to the axis or direction of movement (Albright et al., 1984). This was the first demonstration of cortical columns in a visual area outside of striate cortex. Then he showed that there were two types of MT cells, one sensitive to movement of contours and one to movement of an entire pattern (Albright, 1984; Rodman and Albright, 1989). His demonstration of pattern motion selectivity in MT was actually prior to that of Adelson and Movshon (Movshon et al., 1985), but theirs was so much more elegant that Tom’s earlier observations were lost, which never seemed to bother him. In work begun at Princeton, Albright (1992) showed that MT cells were sensitive not only to luminance contrast borders but also to borders defined by motion contrast and by texture contrast, that is, their motion sensitivity was form invariant.

Hilary Rodman, Tom, and I found that after the inactivation or removal of striate cortex, the majority of MT neurons were still sensitive to the direction of stimulus motion (Rodman et al., 1989, 1990). We showed that this residual motion sensitivity depended on input from the superior colliculus. Thus the superior colliculus may be responsible for the sensitivity to direction of visual stimulus motion that survives striate lesions in humans and monkeys, that is, for blindsight.

Behavioral Effects of Temporal Cortex Lesions

INTERHEMISPHERIC TRANSFER

Why is a rose a rose wherever its image falls over the central retina? Lynn Seacord (undergraduate class of 1975, then tech, 1975–1977), Mort Mishkin and I found an absence of interhemispheric transfer of visual pattern information after IT lesions. We suggested that the similar response properties of IT neurons in both halves of the visual field were the basis of perceptual equivalence for patterns in the left and right visual fields. By extension, we suggested, the large receptive fields of IT cells provide for perceptual equivalence across retinal translation within as well as between each visual half field (Gross and Mishkin, 1977; Seacord et al., 1979).

DISCRIMINATION OF ROTATED FIGURES

On very easy visual tasks animals with IT lesions may be essentially normal, whereas they usually find very difficult visual tasks virtually impossible to learn. There is one interesting exception: Animals with IT lesions can learn to discriminate normally between two identical objects rotated 60 degrees or more from each other. Ed Holmes (graduate student, 1974–1980) and I suggested this was because the control animals have normal shape constancy, view the rotated stimuli as being the same things and therefore hard to tell apart, whereas the animals with IT lesions have impaired shape constancy, see the objects as different, and therefore can tell them apart more easily, thus eliminating the difference between the groups (e.g., Gross, 1978; Holmes and Gross, 1984).

EFFECTS OF SUPERIOR COLLICULUS LESIONS ON ORIENTATION

Although the superior colliculus had been implicated in visual orientation and localization, there was little direct evidence of such functions in primates. Working with Diane MacKinnon (undergraduate, 1971–1973), Dave Bender, and Visiting Professor Charlie Butter, we obtained such evidence (Butter et al., 1978; MacKinnon et al., 1976).

EFFECTS OF SUPERIOR TEMPORAL ASSOCIATION CORTEX LESIONS ON AUDITORY LEARNING

Mike Colombo, working with Hilary Rodman and me, showed that lesions of superior temporal association cortex (Area TA) impaired short-term auditory memory thereby supporting the view that this area plays a role in audition that is homologous to that of IT cortex for vision (e.g., Colombo et al., 1996).

Mapping Retinotopic Organization

PULVINAR NUCLEUS

Although Dave Bender, who holds the record as my longest continuous collaborator, continued to work with me on IT at Princeton, he also began his own studies of the pulvinar, a large subcortical structure of obscure function but major connections to the superior colliculus, striate cortex, and extra-striate visual cortex, including IT cortex. He carried out the first electrophysiological mapping of the pulvinar and found a complete representation of the contralateral hemifield in the rostral inferior pulvinar and evidence for two adjacent retinotoptically organized areas (e.g., Bender, 1981).

EXTRASTRIATE VISUAL CORTEX

When we came to Princeton very little was known about the organization of the visual cortex beyond striate cortex. This changed in part as the result of two visitors from the Federal University of Rio de Janeiro sent by my old friend Carlos Eduardo Rocha-Miranda. Ricardo Gattass and Aglai de Sousa stayed initially for 3 years, and then Ricardo returned several times for shorter visits. Under Ricardo’s leadership we mapped with multiunit electrodes the topographic organization of a number of extra-striate visual areas, usually for the first time, including Areas MT, V2, V3, V4, TEO, and PO (e.g., Gattass, and Gross, 1981a, 1981b; Gattass and Sousa, 1985; Gattass et al., 1988). These mapping studies became the basis for study of these areas in many other laboratories. This project and some associated anatomical connectional studies involved, in addition to Ricardo and Aglai, Carol Colby, Ellen Covey, postdoc (1980–1981), Carl Olson, Princeton Assistant Professor, Sue Fenstemaker, graduate student (1981–1986), Julia Fleming (1978–1979) a physician from Australia, and Julie Sandell (1975–1979) an undergraduate (who wins the prize for the undergraduate in the lab with the most papers in prestigious journals).

BRAZIL

My relationship with Carlos Rocha-Miranda, Ricardo Gattass, their families, and their Brazil was long, warm, and involved many visits to Brazil. On my first 6-week visit, the young Rio scientists found me so different from the stiff English visitors that they had known that they took me out dancing virtually every night. Other visits involved a lecture tour of about five Universities scattered around northern Brazil requiring armed guards when going out, getting marooned on an island in the mouth of the Amazon, eating large rats, and, unknowingly until too late river dolphins, touring the Amazon out of Manaus with Charlie Bruce and Harriet Freeman, living in a zoo in Belem, and visiting the Iguazu falls on the border of Argentina with Tom Albright.

Ricardo had a connection with Pope John Paul II through his mentor Carlos Chagas, the President of the Pontifical Academy of Sciences, so we organized a small symposium in 1984 in the Vatican Gardens (Chagas et al., 1985). There was so much wine and food at lunch that most of us fell asleep in the afternoons with the striking exceptions of the aged John Eccles and Albert Szent-Gyorgyi, who were amazingly indefatigable.

Blindsight and Attention

Monkeys and humans have the ability to detect and localize visual stimuli in the absence of striate cortex. This phenomenon in humans is called “blindsight” because it occurs in the absence of any conscious awareness of the stimulus. Tirin Moore when he was a graduate student (1990–1995) and Hilary Rodman, then a postdoc, showed that the vision that survives striate lesions in monkeys has the same characteristics as human blindsight, that is, monkeys show “blindsight” (e.g., Gross et al., 2003; Moore et al. 1995, 1998). Cowey and Stoerig (1995) came to the same conclusion in a different experiment at about the same time. Maz Fallah (graduate student, 1996– 2001), Alan Repp undergraduate class of 1994 and Paul Azzopardi (a visitor from Cowey’s lab in Oxford) also worked with us on blindsight (e.g., Azzopardi et al., 2003).

The visually guided behavior of monkeys who received their striate lesions in infancy was much better than that of the animals that received their lesions as adults (Moore et al., 1996). Unlike the adult monkeys they probably had normal sensation of the visual stimuli and not merely blindsight. This seems to parallel the case of humans who sustained their striate lesions early in life.

When he finished his dissertation on blindsight, Tirin went off to Peter Schiller’s lab at MIT as a postdoc and then came back to my lab for another

3 years (1999–2003). In that period Tirin showed the close relationship between the circuits that process shape and those that control eye movements (e.g., Moore, 1999). With graduate student Maz Fallah he found that microstimulation of eye movement areas alters circuits that modulate visual attention (Moore and Fallah, 2001). Then with Katy Armstrong, another Princeton graduate student, he demonstrated that such microstimulation actually modulated the activity of neurons in Area V4 (Moore and Armstrong, 2003). These studies were the first demonstrations of specific relationship between mechanisms of eye movements and mechanisms of shape recognition.

Body-Part–Centered Receptive Fields in Premotor Cortex

Michael Graziano started in the lab as an undergraduate helping Hilary Rodman. Then in his senior year (1989) he set out to record from the claustrum, a mysterious structure but supposedly a visual one. He continued in the summer and came down on weekends from MIT where he had just gone as a graduate student. Because we thought we were recording from a visual structure, we used visual stimuli and sometimes got visual responses. We accidentally discovered that touching the animal often also gave responses, and the somatosensory receptive fields formed a map of the body. In the face and arm portions of this map, neurons were bimodal, responding to visual and tactile stimuli. The visual receptive fields of these bimodal cells were attached to the body and extended out into space, usually about 10 cm. Most extraordinary, if the arm or head was moved, the visual receptive fields stayed attached to the somatosensory receptive fields and moved with the arm or head. Thus, these visual fields were in a body-part-centered coordinate system, the first that had ever been reported. Upon sectioning the brain later we found that we had been recording not from the claustrum but from the adjacent ventrolateral putamen, which had been known to have a somatotopic organization, but its visual properties had never been noticed (Graziano and Gross, 1993).

Graziano left MIT graduate school after 2 years and returned to Princeton as a graduate student (1991–1996) and postdoc (1996–2001) where we continued these studies. Rizzolatti and his colleagues had earlier found visuotactile receptive fields in the ventral premotor cortex or PMv (Area F4 in their terminology) as we had in the putamen (e.g., Fogassi et al., 1992). We repeated their results and found that the bimodal receptive fields in PMv would also move with the hand or arm, like those in the putamen (e.g., Graziano and Gross, 1996; Graziano et al., 1997). At that time we interpreted the body-part-centered bimodal RFs in the putamen and PMv cortex as playing a role in sensory-motor integration. Some of these experiments were carried out with undergraduate Greg Yap, class of 1995, and new graduate student Xin-Tien Hu (1994–2000).

With Xin-Tien we found that a subset of bimodal visual-tactile PMv neurons would keep track of stimuli near the head or arms even in the dark: They had mnemonic properties (Graziano et al., 1997a). That study put us into Glamour magazine with the head “Kissing in the Dark.” Xin-Tien’s thesis was on spatial properties of parietal neurons. Later he returned to China, and I took several fantastic trips with him there (e.g., across a landslide to Leaping Tiger Gorge, around the Buddhist holy mountains at Yadin, to a three day Tibetan horse race festival in Litang, to Shitoucheng, an ancient village carved into cliffs over the Yangzi and reachable only by many hours in a four wheel drive and then a footpath and to Lugu Lake with its “walking marriages”). Graziano, undergraduate Lina Reiss class of 1997, and I found a representation of auditory space in PMv: neurons with trimodal visual, somesthetic, and auditory receptive fields that would only respond to auditory stimuli and visual stimuli near the head (Graziano et al., 1999).

When Graziano, Moore, and Charlotte Taylor, a graduate student (1999–2004), stimulated PMv, they produced integrated complex movements (Graziano et al., 2002). About this time, Graziano became an assistant professor at Princeton and continued working on this phenomenon in his own laboratory.

History of Neuroscience

My then wife, Greta Berman, gave me a copy of a new biography of Charles Darwin, because it had a deservedly enthusiastic jacket blurb by our friend Stephen J. Gould. The book talked about a controversy and a “lobe” of the brain I had never heard of, the “hippocampus minor” controversy. The story turned out to be a splendid “case history in the social construction of neuroanatomy” (Gross, 1993a, 1993b). The leading Victorian anti-Darwin scientist was Sir Richard Owen, and his main argument against evolution was that the human brain was unique, particularly in having a hippocampus minor. Thomas Huxley, Darwin’s ferocious defender, set out to discredit Owen, not merely by demonstrating the hippocampus minor in a variety of primates but by painting Owen as a fraud and charlatan. The tale illustrates the political and social matrix of brain study and the extraordinary persistence of ideas in biology. The hippocampus minor is now known as the “calcar avis” and is actually only a slight indentation into the lateral ventricle caused by the calcarine fissure. This was a return to my long-standing interest, from high school on, in the social context of science.

The success of my papers on the hippocampus minor spurred me to write more than a dozen additional history of neuroscience papers, several of them deriving from the unfinished introduction to my thesis. Some of them were collected in Brain, Memory, Vision: Tales in the History of Neuroscience (Gross, 1998) and another volume is almost finished, to be entitled From the Paleolithic to the Internet: More Tales in the History of Neuroscience. Aristotle, Galen, trephining, the evil eye, Leonardo, Swedenborg, psychosurgery in Renaissance painting, Rembrandt, Alhazen, Claude Bernard, phrenology, the discovery of motor cortex, and adult neurogenesis are some of the historical topics I have written on.

Collaborating with Other Princeton Faculty

Bornstein, Babies, and Color

Marc Bornstein was a faculty colleague who did important work on color and babies. We wrote a really neat paper “On Left and Right in Science and Art” for the journal Leonardo. It ranged over physics, chemistry, brain laterality, anthropology, art criticism, and stage craft and had pictures by Pouissant, D’Arcy Thompson, Cajal, native Americans, ancient Greeks, our colleague Julian Jaynes, and, of course, Leonardo. We made predictions about dyslexia and explained Leonardo’s mirror writing (Gross and Bornstein, 1978). The essay inspired several collaborative findings on human infants: that infants confuse lateral mirror images as do many other animals and that vertical symmetry is very special for infants (Bornstein et al., 1978, 1981). With undergraduate Julie Sandell, Marc and I demonstrated that monkeys divide the spectrum into the same four-color categories that human infants and adults do (Sandell et al., 1979).

fMRI Imaging of Monkey Cortex

In monkeys, face selective cells are found throughout inferior temporal cortex but are concentrated in the vicinity of the superior temporal sulcus including in STP. In humans, faces especially activate one limited region on the ventral surface of the temporal lobe and another in the dorsal and anterior superior temporal sulcus, perhaps corresponding to Area STP. To relate face mechanisms in humans and monkeys, my faculty colleague Sabine Kastner, Marc Pinsk (graduate student, 2001–2005 and currently postdoc), and I, studied fMRI in awake monkeys as they looked at face, body parts, and other objects. We found two areas of activation by faces and one by body parts. These seemed to be similar to the areas activated in humans by the same stimuli (e.g., Gross, 2008; Pinsk et al., 2005).

Adult Neurogenesis and Elizabeth Gould

From the time of Ramon y Cajal a central dogma of neuroscience has been that no new neurons are added to the central nervous system of adult mammals. This dogma was challenged in the 1960s by Joe Altman (who was in Teuber’s department at MIT when I was). Altman reported new neurons in the hippocampus, olfactory bulb, and cortex of adult rats, guinea pigs, and cats. Few believed him; he failed to get tenure at MIT and eventually turned to more conventional subjects. (This history is reviewed in Gross, 2000.) Then in the early 1990s Elizabeth Gould and her colleagues at Rockefeller University confirmed Altman’s results on neurogenesis in the hippocampus of adult rats (e.g., Cameron et al., 1993; Gould et al., 1992). Many others then began to report similar results in rats. Gould went on to show adult neurogenesis in the hippocampus of tree shrews and marmosets, a New World monkey, and how experiential factors such as stress, hormones, and learning could modulate adult neurogenesis in the hippocampus (e.g., Gould et al., 1997, 1998a, 1999a, 1999c). Gould then moved to the Princeton psychology department and we began to collaborate. We demonstrated hippocampal neurogenesis in the adult macaque (Gould et al., 1999c). We also reported neurogenesis in the frontal, temporal, and parietal cortex of adult macaques and noted that the new cortical neurons, like new neurons, in the adult rat and adult macaque hippocampus tended to have a transitory existence (Gould et al., 1999c, 2001), perhaps related to a role in learning (e.g., Gould et al., 1999c; Gross, 2000, Leuner et al., 2006). Since our first report of adult neurogenesis in the cortex there have been a number of confirmations as well as some failures to do so, and thus the issue is still unsettled, and the controversy unpleasantly fierce (see review by Gould, 2007).

More recently, in collaboration with Gould’s postdoc Ben Leuner and her graduate student Genia Kozorovitskiy, Gould and I showed a decline in hippocampal neurogenesis with aging in the marmoset, the first such report for a primate (Leuner et al., 2007). In another marmoset study with Kozorovitskiy, Leuner, and Gould, experience in an enriched environment produced structural and biochemical changes in the brain, the first such demonstration in primates (Kozorovitskiy et al., 2005).

Marriage and Family

I decided not to scatter bits of my family life in among my experiments and graduate students. They were much too important for that and deserve much more space than is possible here. So until I publish my real (i.e., personal) memoir a few sentences will have to suffice. In 1961 I married Gaby Peierls, an Oxford graduate whose father was Professor Sir Rudolph Peierls, Professor of Theoretical Physics at Oxford. He was born in Germany and was one of the leading theoretical physicists of his day. Her mother was born in the Soviet Union and was an exaggerated fusion of a Jewish and a Russian mother and features in many of the biographies of physicists of her generation. Both came from totally assimilated Jewish backgrounds but that made no difference to Hitler or Stalin. Gaby was successively a stock analyst, economics graduate student at MIT, ran the local New Jersey American Civil Liberties Union (ACLU) office, went to University of Pennsylvania law school, and worked until very recently as an advocate for children, abused women, and recent immigrants. She was a wonderful wife and mother to our four children and crucial to every aspect of my academic life. She is retired now and lives near our eldest daughter, Melanie.

Melanie went to Barnard College and Robert Wood Johnson Medical School and is Assistant Professor of Internal Medicine at the University of Gainesville and has two boys, Sam and Noah, and a Physics Professor husband Steve Hagen. My youngest daughter Rowena lives in Princeton and managed until recently a “Ten Thousand Villages Store” that sells fair-trade products from peasant cooperatives worldwide and lectured on fair trade in local businesses and churches. I had another daughter Monica who died in an accident at the age of 2 on Mt. Washington and a son, Derek who died of cancer at age 27. He went to Simons Rock and Oberlin as an undergraduate and the University of Rochester as a linguistics graduate student and worked in the computer/linguistics/ publishing world.

I was with Iris Fodor for about 8 years. We knew each other since MIT days. Iris is a red diaper baby, Professor of Psychology at NYU, and a psychotherapist. She has a house in Woodstock, N.Y., where we spent a lot of time with our five kids. One summer we went around Italy with the four youngest. Iris and I spent 6 amazing weeks in India together. As a result we got seriously into photography at the same time, and she now teaches photography to Tibetan and Peruvian children when she is not teaching psychology or seeing patients.

I was married to Greta Berman for 14 years. Greta was another red diaper baby. Greta went to Antioch, got her doctorate at Columbia, and teaches art history at the Juilliard School. We had a good life together in Princeton, Manhattan, and Woodstock, N.Y., and traveled widely. Greta often told of following me to the end of the earth, and it was true (Tibet, Papua New Guinea.). She was a great comfort when my son Derek died. Greta was also very supportive of my photography efforts. She dismissed my early efforts as “like post cards or National Geographic pictures” and acted as a muse and informal curator for my first one-person show.

The Twenty-First Century

Students and Teaching

In the new century I stopped taking new graduate students and postdocs but continued to collaborate with colleagues. Until recently, my undergraduate and graduate teaching was mostly physiological psychology, now called “cognitive neuroscience” with an occasional more specialized course such as the history of neuroscience. A few years ago I introduced a course for psychology graduate students in “Responsible Conduct of Research,” which deals with such matters as authorship, mentoring, peer review, conflict of interest, and the use of animals and humans in experiments. I have also started to teach courses in Neuroethics for undergraduate and graduate students. They deal with the ethical implication of developments in neuroscience such as brain imaging and drugs that change mood and performance as well as more traditional questions such as when does life begin and end and the involvement of scientists in the military. In the past I taught in Brazil, China, and Vietnam and, more recently, in Uganda and in Cuba. I hope to do more of this outreach teaching in the future.

Inferior Temporal Cortex and Processing the Facial Image

My contribution to understanding IT cortex was largely confined to the sensory properties of its neurons. Since then their cognitive properties, particularly in attention and memory, have been extensively explored by my former students such as Desimone, Miller, and Albright and by many others. Furthermore, the processing of objects and faces by human IT cortex is now being widely studied by imaging techniques. Models of IT cortex are coming close to the anatomical, physiological, and perceptual facts. Disturbances in temporal lobe face processing have been implicated in a variety of human disorders such as autism. I continue to be astonished by the growth and vitality of the inferior temporal-face industry (Gross, 2005, 2008).

Overview

This memoir comes at a major change in my life: I have closed my laboratory and have full time for teaching, writing, travel, and photography. Until now I have been very fortunate indeed. I have had wonderful companions in research, good students in the classroom, more-than-deserved recognition from the field, generous and continuous financial support, and institutional affiliations that were never onerous. May the future be as rewarding.

Selected Bibliography

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Albright TD. Form-cue invariant motion processing in primate visual cortex. Science 1992;255:1141–1143.

Albright TD, Desimone R, Gross CG. Columnar organization of directionally selective cells in visual area MT of the macaque. J Neurophyiol 1984;51:16–31.

Azzopardi P, Fallah M, Gross CG, Rodman HR. Response latencies of neurons in visual areas MT and MST of monkeys with striate cortex lesions. Neuropsychologia 2003;41:1738–1756.

Barlow HB. Summation and inhibition in the frog’s retina. J Physiol 1953;119: 69–88.

Barlow HB. The neuron in perception In MS Gazzaniga, ed. The cognitive neurosciences Cambridge, MA: MIT Press, 1995; 415–434.

Bender DB. Visual sensitivity following inferotemporal and foveal prestriate lesions in the rhesus monkey. J Comp Physiol Psychol 1973;84:613–621.

Bender DB. Retinotopic organization of macaque pulvinar. J Neurophysiol 1981; 46:672–693.

Bornstein MH, Ferdinandsen K, Gross CG. Perception of symmetry in infancy. Dev Psych 1981;17:82–86.

Bornstein MH, Gross CG, Wolf JZ. Perceptual similarity of mirror images in infancy. Cognition 1978;6:89–116.

Bruce C, Desimone R, Gross CG. Visual properties of neurons in a polysensory area in superior temporal sulcus of the macaque. J Neurophysiol 1981;46:369–384. [Database]

Bruce C, Desimone R, Gross CG. Both striate cortex and superior colliculus contribute to visual properties of neurons in the superior temporal polysensory area of the macaque. J Neurophysiol 1986;55:1057–1075.

Buerger AA, Gross CG, Rocha-Miranda CE. Effects of ventral putamen lesions on discrimination learning by monkeys. J Comp Physiol Psych 1974;86:440–446. [Database]

Butter CM, Weinstein C, Bender DB, Gross CG. Localization and detection of visual stimuli following superior colliculus lesions in rhesus monkeys. Brain Res 1978; 156:33–49.

Cameron HA, Woolley CS, McEwen BS, Gould E. Differentiation of newly born neurons and glia in the dentate gyrus of the adult rat. Neuroscience 1993;56: 337–344.

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Chagas C, Gattass R, Gross CG. Eds. Pattern recognition mechanisms. Vatican City: Pontificia Academia Scientarum, 1985.

Colombo M, Fernandez T, Nakamura K, Gross CG. Functional differentiation along the anterior-posterior axis of the hippocampus in monkeys. J Neurophysiol 1998;80:1002–1005.

Colombo M, Gross CG. Responses of inferior temporal and hippocampal neurons during delayed matching-to-sample in monkeys (Macaca fascicularis). Behav Neurosci 1994;108:443–455.

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Desimone R, Albright TD, Gross CG, Bruce C. Stimulus selective properties of inferior temporal neurons in the macaque. J Neurosci 1984;4:2051–2062.

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Gattass R, Gross CG, Sandell JH. Visual topography of V2 in the macaque. J Comp Neurol 1981b;201:519–539.

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Gross, CG., Hans-Lukas, Teuber. In Wilson RA, Keil FC, eds. MIT encyclopedia of the cognitive sciences. Cambridge, MA: MIT Press, 1999;832–833.

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Richard Held

BORN:

New York, New York,

October 10, 1922

EDUCATION:

Columbia College, B.A. (1943), B.S. (1944)

Swarthmore College, M.A. (1948)

Harvard University, Ph.D. (1952)

APPOINTMENTS:

Instructor, Assistant Professor, Associate Professor, Professor and Chair, Department of Psychology, Brandeis University (1953–1963)

Member, Institute for Advanced Study, Princeton, NJ (1955–1956)

NSF Senior Research Fellow, and Visiting Professor (1962–1963)

Department of Psychology, Massachusetts Institute of Technology (MIT) (1962–1986)

Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT) (1986)

New England College of Optometry (1995)

HONORS AND AWARDS (SELECTED):

American Academy of Arts and Sciences (1967)

Society of Experimental Psychologists (1971)

National Academy of Sciences (1973)

Honorary Degree of Ocular Science (The New England College of Optometry) (1977)

Glenn A. Fry Award (American Academy of Optometry) (1979)

Howard Crosby Warren Medal (Society of Experimental Psychologists) (1983)

Doctorat Honoris Causa, Free University of Brussels, Belgium (1984)

Kenneth Craik Award, Cambridge University, England (1985)

Galileo Award (American Foundation for Vision Awareness) (1996)

Since childhood Richard Held was intrigued by the illusions of vision and their motor consequences. He and his colleagues made extensive studies of the effects of sensory rearrangement and have modeled the adaptive processes that reduce, and sometimes eliminate, the induced errors. He pursued studies of the visual capacities of animal and human neonates so as to test the implications of plasticity for early development of spatial vision and motor control in accord with the following logic. If the adaptive process yields full and exact compensation in the mature animal, then it should be capable of compensating for any neonatal errors and may even account for development itself. Although Held pursued many sidelines, he always returned to this issue.

Richard Held

Childhood

I distinctly remember seeing the phenomenon and puzzling about it on that boat ride so long ago. It was 1928 and I was a 5-year-old and only child. My parents had taken me for a holiday ride on the excursion boat that sailed across New York Harbor from Battery Park to Coney Island. It was a bright sunny day, and once the boat was in the channel I scanned the water idly looking at birds and boats. At one point I shifted my gaze to the deck on which our chairs sat. I felt a mild shiver as I watched the deck. It was moving under me. What was happening? After a minute or two, I realized that the deck was not going anywhere, it just appeared to move: I would much later learn that this was a paradox that exemplifies the difference between perception and physics. After a time, the motion slowed and then stopped. What was this motion? Could it be confused with real motion? What was real? I asked my parents, but they couldn’t or didn’t clarify the mystery.

Of course at the time I didn’t suspect that this incident might be the first indication of a line of interest that has remained throughout my life. What is the relation between the physical description of the world and its perception? Clearly, we all require what has been called “veridical vision” to survive. We always need to distinguish a lion from a lamb, and we continually need to grasp the sizes and distances of objects to manipulate and locomote without damage to ourselves. The issue posed by illusions, transient ones in particular, is how do their perturbations of appearance square with the need for stability and permanence of the perceived environment?

This incident says still more about me and my origins. The idea of taking the family on an excursion through New York Harbor to Coney Island and back was a very bourgeois notion. It was cheap. It was relatively safe. In the hot summer the harbor breezes were cooling. The watery scenes were mildly interesting, and the destination was a long pier leading to an amusement park and hot dog stands that provided entertainment and an economical lunch. And, indeed, my immediate family, father and mother, were quite a conventional couple. My father, whose education was limited by the early death of his own father, was an export broker whose business was a marginal success. My mother was an artist who worked for a time at fashion design. She took courses at the Metropolitan Museum of Art and often took me there for visits, which gave me an early familiarity with visual arts. She lived to be age 97 and encouraged my interest in all aspects of vision except for the idea of becoming a vision scientist or, for that matter, any kind of scientist. After all didn’t scientists live on the fringes of society and how did they make a living?

Growing up my interests turned first to taking things apart—clocks, locks, and other expendable gadgets—to see how they worked. Then on to making things—electric motors and radios. I was the typical boy-scientist, boy-engineer. My favorite fiction was the Tom Swift series of the adventures of a boy inventor. I soon moved on to books on electricity and other scientific topics. My grammar school was the same one my father had attended before me, Public School 6, Manhattan, whose students walked to school through what was called the Silk Stocking district. The elderly teacher of the first grade even remembered my father. To my parent’s surprise I did well in school. They hadn’t expected their child to excel in school. After all, they hadn’t. I remember one particular revelation. During my seventh grade, a school psychologist gave a test to each and every student in my class. A few days later I was called out for an interview with the psychologist together with a girl named June. It so happened that I was enamored of June but painfully shy about any expression or discovery of my secret. To be called out together with her was upsetting because I thought the psychologist had somehow discovered my secret and was about to reveal it to her. But this was of course my fantasy. I must have had more faith in psychologist’s insight then, than I have now. It turned out that he had only chosen to interview the two of us because we had had the two highest scores in what turned out to be his intelligence test.

As I grew older, when not in school I spent a lot of time roaming Central Park with my good friend and schoolmate Alfred Halliwell. In warm weather we roller-skated on the hard-topped paths from one end to the other of the Park. In snow we did the same on Flexible Flyer sleds. We always stopped for a hot dog at the small lakeside tavern.

We talked about what we wanted to do when we grew up. Alfred wanted to build things. Last I heard of him he was an electrical contractor in Connecticut. Occasionally we were joined by Robert Primoff, a boy who was more interested in ideas than athletics. We spent a lot of time talking about science and propounding notions of truth and reality; questions of epistemology and ontology as I later learned when I took one of several courses in philosophy. In the interests of science we broke apart a large single-cell dry battery that made an epic mess resulting in the phrase, “Remember the battery!” a cautionary phrase we used when confronted with potential disaster.

Stuyvesant High School

During my eighth grade it was time to apply to high school, the next 4-year step in our educational system. The best high schools selected applicants on the basis of admission tests. Stuyvesant High School was known as the science high school and remains to the present as one of several in New York City. I applied and was admitted. I enjoyed it immensely, especially science and mathematics and shopwork that was still considered important for budding scientists and engineers. Stuyvesant was then housed in an old and grubby building at an address called in New Yorkese Fifteent Street and Foist Avenoo in downtown Manhattan. The campus was the street. Stuyvesant had an excellent faculty and was the springboard for many students who went on to study science and engineering at MIT and other universities A surprising number of them became faculty members at MIT.

Stuyvesant High School was not merely the selective school of science. It had a very diversified student body and a politically alert faculty that was the source of a social and political education. The roll call at Stuyvesant read like a delegation from the United Nations. A few of the more exotic names of classmates that I remember included Pasquale Pasquale, Lazlo Szabo, John Bruzza, and Hannibal Castiglia who, incidentally, was the nephew of the notorious Mafia boss, Frank Costello, to mention a few. Many were the children of immigrants, and they traveled to high school from all over the city. I rode the now-extinct Second Avenue Elevated train back and forth from 92nd Street to 14th Street twice a day. The income range of the students’ families was almost as broad as that of the entire country. I became a close friend of a thin fellow named Joe Hurley who wore ill-fitting shabby clothes. We often had lunch together either at the White Tower, where a hamburger cost a nickel, or at Nedicks where you got a hot dog and an orange drink for 10 cents. He couldn’t afford more. On the other hand there were a few well-heeled students whose fine clothes betrayed their origins. These years were the mid and late 1930s and the country was just emerging from the Great Depression. The school had some racial variety, but the samples were relatively small. Confronted with this diversity, one could not help but expand social horizons and knowledge of different ways of life.

The faculty of Stuyvesant was almost as diverse as the student body. Half of them were Ph.D.s and were addressed as doctor. There was Dr. Kaplan who was rumored to have designed submarines in Russia but had a hard time controlling his class, Dr. Schur who taught us biology and took a deep interest in his students, a teacher of French language, Miss Popo, a short stocky woman in frilly dresses who dyed her hair deep red and reminded me of a small Pekinese dog. Dr. Myers taught us physics and coached the swimming team on which I got my letter. We used the pool in the local public bathhouse for practice. Economics proved to be an interesting course of thinly disguised Karl Marx. Actually, leftist politics seemed to be the rule among the interested faculty and students, a fact that became apparent years later when during the reign of Joseph McCarthy many of New York City’s teachers were persecuted by that demagogue. This prewar period was perhaps the heyday of leftist politics in the States. The first World War had not brought a satisfactory peace, and the Depression had disillusioned many people who then looked for political change.

Seeing and feeling the injustices in society of this period, I sympathized with the left in an abstract way, but I was not about to leave school or go on other radical adventures such as joining the Spanish Loyalist army as did some of my radicalized contemporaries. Instead I was drawn further to science. I thought much of the ills of society stemmed from irrational thinking. The antidote was logical thinking and science was its epitome. It took a long time before I saw the naivete of my “thinking.”

Columbia College

During my senior year at Stuyvesant High School, I applied for admission to Columbia College that my parents and I thought offered the best education in Greater New York. We were told that admission was difficult for a student from New York City because there was said to be a quota on local applicants: one that was a thinly disguised reflection of anti-Semitism. Perhaps foolishly I applied nowhere else, including other Ivy League schools. I simply did not want to leave New York City. Fortunately I was accepted in the Columbia class of 1943 and looked forward to attending in September 1939. In retrospect I recognize that my senior year in high school was a high water mark in my sense of feeling on top of things. I thought I knew more and had more opportunities than I would ever again believe. But that confidence and trust in progress was soon shattered by events. The very month I began to attend college (September 1939), the Germans invaded Poland and World War II began.

For my family and friends the implications of those events in Europe were profound. In a sense we were prepared to hate Germany. As a small child the Germans, opponents in the last war, were still the enemy in play and games. My father was a veteran of the War. The hated Spanish Nationals were supported by the fascist countries of Europe. Information about cruel treatment of Jews had been leaking out from Germany for some time. Much as war seemed an outrageous mistake to the rational mind, this particular war seemed justified, and one needed to contemplate joining the defense forces. Although the threat of war hung over our heads throughout my college career, we students managed to continue our education and other activities that go with college ages. As a freshman I tried out for the rowing crew but gave that up after realizing how filthy the Harlem barge canal was. Any cut that got a drop of its water was infected by nasty microbes—a specialty of the Harlem and East rivers. I then tried the wrestling team, and although I once defeated my good friend Eddie Marwell I was not a general success at that sport. I joined a fraternity against my better judgment and rarely attended its meetings. Then there were the Barnard girls ensconced across Broadway. Various social events brought us together with them, and many long-term relationships were started. I am still reminded occasionally of my own connection of the time: Edith Schmidt, a sweet young woman from Texas.

In those days any student who was proficient in science and math was assumed to be on the road to becoming an engineer. After all that was where the jobs and careers were. Pure science was as remote a profession as the study of Etruscan epigraphy. Columbia offered a 5-year combination AB-BS program in addition to the regular 4-year engineering option. That arrangement suited me fine, and the addition of the extra liberal arts courses played an important role in the development of my career.

Meyer Schapiro

Why did I opt for liberal arts as well as engineering? Because I wasn’t sure that engineering was for me. I imagined myself in some occupation that engaged more of my interests in the arts, and what later I recognized as the field of what may be called “perceptual science.” I looked into architecture as an alternative. That profession seemed to combine art with building and planning, both of which interested me. But I was told by knowledgeable older friends that that view of the profession was more of an ideal than a reality. Moreover, the school of architecture at Columbia was dominated by the Beaux Arts approach which seemed neither innovative nor interesting. Then in the course of my junior year I had what I might call an epiphany.

I encountered Meyer Schapiro by taking a couple of courses with him in art. He was Professor of Art History and Criticism, a polymath who in brilliant lectures brought all sorts of information from historical, scientific, iconographic, and other sources into his discussions of works of art. He transported his audience to exotic places when they sat in a dimmed seminar room watching slides and raptly listening to him lecture. He assigned homework in the following way: Go forth, find an object or work of art you like, and write about it. That was all. But of course we students would try to emulate the teacher and probe as deeply as we could. On one of the assignments I chose to examine the Starry Night of Vincent van Gogh hanging on a wall in the Museum of Modern Art. That painting had always struck me as strangely exciting. As you will recall, the scene portrays a bright sun surrounding a crescent moon with stars surrounding them and a great vortex in the sky with no obvious identity as an astronomical object. From the earth below a church steeple points to the sun-moon. In the process of reading Vincent’s letters to Theo, his brother, I discovered that he attributed the appearance of the moon as a crescent to occlusion by the earth’s shadow that is, of course, incorrect because that is a description of a partial eclipse of the moon by the earth. I discovered that there was no such eclipse at the time. And considering that Vincent always painted natural scenes, however he may have transformed them, one might conclude that some kind of subconcious process was influencing this portrayal. Being interested in symbols at the time, I proposed that this was a cryptic portrayal of the holy trinity: sun:father, moon:son, and vortex:holy ghost; church steeple proclaiming: BEHOLD!

A day after I handed in the assignment, Schapiro asked me to come to his office where he showed me an illuminated manuscript with a sentence describing a scene from the Apocalypse reading: “In the sky was a woman clothed with the sun with the moon under her feet and stars surrounding them.” My interpretation of the Starry Night was off but not too far. Schapiro published this discovery in a footnote to an article in the magazine View, attributing it to me. Apart from the excitement of recognition by this greatly admired teacher, the event had the following significances for me. It showed me that with motivation, effort, and devotion, one could discover the underlying truths in the world and its artifacts: what I later learned to call research. And, just as important, I COULD DO IT. But would I have the opportunity if I continued in engineering? I doubted it. What should I do? For the moment, the question had to be shelved. The war in Europe was escalating. Everyone knew that we would have to enter it. It was not the time for me to quit engineering before I at least had the degree. Moreover, being in engineering training gave deferment from the military draft that by then had been instituted. The military believed that in the long run a trained engineer would be more valuable to the service than immediate induction into the defense forces. Service in the military at the time was at least a relatively egalitarian affair—every young man was subject to the draft—unlike the situation in the current fiasco. In any event, imminent and actual military service was to be my major concern for the next few years.

War

Not many weeks after I received my engineering degree, I applied for an officer’s commission in the United States Naval Reserve. I had discovered that holders of such degrees were eligible to apply directly, and I preferred the watery road as an officer to being drafted into the Army as a private. After a thorough physical examination and a cursory intelligence test I was told that a decision would take several months. In the meantime I learned that the draft was threatening to take me for the Army and would not wait for the Navy’s decision. Soon after I was formally drafted and spent 2 months in the Army before the award of the Navy commission as Ensign finally came through. Fortunately I was able to transfer to the Navy, although as I handed back my Army equipment the quartermaster announced that I was going from the frying pan into the fire. I was assigned to what was called Indoctrination School on the campus of Princeton University for 60 days. Students in the school were taught how to act like officers, distinguish port from starboard, and learn a few nautical skills that would be useful on board ship. On completion we were derisively called “60-day wonders.” After Princeton I opted for further training in tactical radar, then a very hushhush new technology for target identification, fighter direction, and coastal navigation. I got so interested in it that I was asked to stay on after course completion to help out at the radar training school in Hollywood Beach, Florida. Because winter was on its way, I had no objection to remaining there. Most of my teaching was as a coach going through the motions drilling on simulated operations. However, at one point I got my first experience lecturing in front of a class of seasoned officers. I had my trepidations. But I was unprepared for the panic response I felt soon after I began to address the group. Being in Florida it was a hot day—the large windows were open—and as I glanced out one of them to apparent freedom, I had a terribly strong impulse to jump out the window. It took a while for me to overcome this reaction to addressing groups of people. After several months in Florida I was sent to Saint Simons Island in Georgia for further radar training in fighter direction. A few weeks later I was ready for sea duty as a tactical radar officer on an aircraft carrier.

My orders directed me first to San Francisco by slow stages on a Boeing DC3 across the country. Then on an even slower unescorted freighter to Honolulu where I was to pick up a berth on one of the carriers that was in from the western battle zones.

After some months of cruising the ocean aboard the escort carrier CVE Kadashan Bay the long-awaited new weapon was dropped while we were anchored at Eniwetok atoll in the mid-Pacific ready for the final push. But the war ended, and for me further duty consisted of having my ship converted to a troop carrier and, as such, visiting several exotic ports of the Pacific Ocean including Saipan, Okinawa, Shanghai, and finally the Panama Canal and its locale.

In retrospect the war for me was quite an adventure, but apart from shipboard duties I was not entirely idle. Even before joining the Navy I had been reading in the literature of perception. Ernst Mach’s book on The Analysis of Sensation particularly intrigued me. Then early during my time on shipboard I received a letter from Meyer Schapiro in which he said he was sending me under separate cover a thick monograph written by Wolfgang Koehler and Hans Wallach. Knowing of my interests in vision he thought I would be fascinated by its contents. Koehler, was the eminent Gestalt psychologist who had left Nazi Germany on principle and was living and teaching in the States. The monograph was titled Figural Aftereffects: An Investigation of Visual Processes. Essentially it showed how the study of what can be called an “induced visual illusion” can support a theory of brain function via a linking assumption. I pored over that monograph with increasing enthusiasm. Here was a subject I could really dig into with pleasure. In detail, the monograph describes a long series of experiments illustrating how an observer’s prolonged gaze (inspection) at a particular figure will alter the appearance of a second (test) figure presented after the first is removed. The second figure, or parts of it, will appear displaced in space for some time after it has appeared. These aftereffects might well be called “illusory” because they distort what is normally seen. They obviously belong to the large category of illusions, among which is that of motion with which I had been intrigued as a child. The fascinating aspect of his account is the theory that Koehler propounded to explain how the brain managed to produce these illusory aftereffects and how they related to the normal state of spatial vision. Finding that the aftereffect could be produced when one eye has inspected only the first figure and the other eye only the second figure implied that the neural processing was going on at the level of the cerebral cortex where information from one eye is first combined with that from the other. The theory then proposed that the shape of perceived forms was represented by the distribution of field potentials in cortex resulting from excitation originating at the retina. That distribution was in turn influenced by the distribution of electrotonus (a form of electroionic resistence) in the cortex left as a residue from previous potentials. This was the notion that Koehler would try to prove experimentally as I discuss.

Wolfgang Koehler and Swarthmore College

On learning of my enthusiastic reaction to the monograph, Schapiro offered to introduce me to Koehler when I returned to the States. And, true to his word, he did exactly that. Very soon after I returned to the States, still wearing brass buttons and epaulettes, I called Schapiro to announce my return and then made an appointment to meet Koehler at Swarthmore College. As I recall we met at his house just off the Swarthmore campus. At some point his wife, a pleasant Swedish woman he called Flicka, joined us for a time in part, I suspect, to check me out. I mention her presence because much later on, after I had become quite familiar with both, I learned that there was something about that visit that they found very amusing. Although they were too polite to tell me directly, I gleaned enough information to reconstruct the cause of their amusement. As I imagine seeing myself through their eyes: one day there arrived into the laid-back academic environment this 6-foot-tall 24-year-old Lieutenant junior grade in formal naval uniform who proceeded to engage Kohler with a formality matching his attire. They had probably not experienced anything so military since they left Germany. But apart from their amusement, Koehler did decide that I, with my scientific and engineering training, would be useful to have available as his assistant, and he set in motion my engagement at Swarthmore. Now it was his intent to confirm the existence of the electric fields in human brains that he had hypothesized, and I was to be his collaborator in the endeavor.

We set out to do so with only the crudest equipment; an old electroencephalograph with crude electrodes to be pasted on the scalp of the observer or patient. To cut out external sources of ambient radiation we built a cage of wire mesh within which the observer sat. We volunteered Koehler’s services as observer because I was busy with running the experiment. Because we pasted fairly large electrodes on the scalp, it was desirable to cut off the hair at their sites. Because Koehler had a healthy head of hair, albeit silvery gray, I had to serve as barber. I got so skilled at it that I wondered if I ought to change my profession. In any event, Koehler appeared in public with two holes in his hair which he pointed to almost proudly. Once hooked up for recording we saw periodic fluctuations of potential and the alpha rhythm but nothing very clearly related to the visual patterns that the observer watched. Koehler concluded that the potentials he sought would be of small magnitude and slowly changing with the movements of a visible pattern that moved slowly across a screen. To record such potential changes was a challenge at that time. We needed an amplifier that could handle near DC levels with minimal drift. We needed nonpolarizable electrodes that would eliminate the drift caused by polarization at the electrode–skin surface. We obtained both, the latter as a result of my learning how to manufacture a silver-silver chloride interface at the scalp electrodes. Still, even with all the equipment we had developed over at least a year’s work, we had not found the potentials that Koehler believed should be present. We were disappointed, but Koehler was indefatigible and would simply say, “we have not yet found them.”

One evening he called me at the laboratory. “Held,” he greeted me. I should say that by this time we had worked together in close contact for more than a year. Previously, he had always addressed me as Mr. Held. Calling me Held was a big step in informality and intimacy. It presaged an important message. I listened with bated breath. “Held,” he continued, “what do you do if you have an ordinary cell (like a flashlight battery) whose voltage is insufficient for a job?” My immediate response was, “Why you get several cells and wire them in series of course.” And with that response came a premonition that brought gooseflesh to my skin. “Yes,” continued Koehler, “and that is exactly what we shall do on our next trip to Princeton (where we were working). We shall recruit four willing Princeton undergraduates, wire them in series, have them all stare at a spot in the screen as we pass an edge across it, and we shall record the summed potentials from their heads.” The audacity of this bizarre proposal shook me. But that was Koehler. He would not be stopped. He often spoke admiringly of “bold” proposals, and surely this one was an exemplar. Accordingly, a few days later at Princeton four undergraduates appeared. I performed the necessary tonsorial modifications, attached electrodes, and connected the necessary wiring. When all was set, Koehler rotated the projector that cast an image on the screen they viewed. The needle, on the paper recording the potential changes swung over and back. We repeated the procedure again and again with the same result. Finally we had seen a substantial potential shift related to the passage of the image moving across the retinae of our four subjects. Soon after we managed to find these potential changes recording from one head only (Koehler and Held, 1949). Koehler had found his Holy Grail. He would continue working on these potentials, and not long after he gained the help of a new assistant (Donald O’Connell) because by this time I was approaching the end of my 2½-year stay at Swarthmore College (Koehler et al., 1952).

The Wild West

During the years that I spent at Swarthmore, I attended several courses. Those of Hans Wallach were most instructive, perhaps even more in style than substance although the latter was not lacking. He lectured in a laidback manner with long pauses to ponder and raise questions so that the students were challenged to respond thoughtfully. I spent some time with Solomon Asch and even participated in his early group influence experiments, although the field of social psychology was not my cup of tea. I got to know the zoologist Robert Enders. Through his contacts I became one of several students who received summer fellowships to do field observations of animal behavior at the Jackson Hole Wildlife Station in Moran, Wyoming, observing animal behavior. Like a cattle ranch in the old West, The Station was composed of a bunkhouse and a couple of utility cabins supervised by a local couple whose wife served as cook. Originally I proposed to study the behavior of packrats, which were supposed to be plentiful in the area. There were signs of the animals, but they turned out to be nocturnal, and I was not prepared for night observation. The small herd of bison were much more accessible, and I tracked their activities, under the supervision of Margaret Altmann, long enough to gather sufficient information for a short paper (unpublished) on their grazing patterns. Margaret was an interesting character who gained fame through her book on the red deer of German forests. Her project was to observe the elk of the area. However, the elk had migrated to higher ground, and although Margaret had brought her own horse for transportation, the elk were hard to locate. Because there was a corral in nearby Moran, Margaret took it on herself to teach several of us to ride. Once we gained sufficient skill, she took us out on trips seeking the elk. They culminated in a pack trip for several days in the wilderness. Here I can’t forebear mentioning what Abe Maslow might have called a “peak experience.” By late summer my jeans were well worn, I wore boots and chaps and a wide brimmed hat, and I had grown a straggly beard. I even carried a small pistol to scare off the bears. One day I was riding down a dirt road when an open car pulled up and the driver called out to me, “Hey buddy, you want to join us for the roundup?” He had taken me for a cowhand. It was the peak realization of my fantasy life. There were lots of fun and games that summer with Margaret Altmann, Howard Schneiderman, Trudy Enders, and others, and the animal work was a good background for appreciating the increasing influence of the ethologists who were just beginning to come into prominence in this country.

During my last year at Swarthmore I began a research program of my own that served me well, as I explain, when I went on for further training. I had become interested in what I later learned was the classic prism adaptation problem. Look through a transparent prism and you see the world displaced and distorted. If you wear such prisms as eyeglasses you will see a slow reduction of all the distortions and displacements. If you reach for an object seen through the prism you will initially misreach, but with repeated efforts slowly regain accuracy. It is this ability to return to accurate performance despite the transform, called “adaptation,” that has intrigued experimenters at least since Helmholtz wrote about it in the nineteenth century. These experiments returned me to my earlier question on how perceptual and motor stability is maintained despite perturbations of the system.

Harvard Psychology Department

At the time, for me the practical question was should I continue my education in experimental psychology or possibly go to medical school where I might study the real brain as well as gain the security the profession offered. I decided that I was already too old to begin medical school and instead applied to the Harvard Psychology Department. Koehler had close friends at Harvard and approved my choice. Before I left Swarthmore I asked Koehler, “How does one make one’s way in this field?” He answered shortly, “Make discoveries.” This answer has had many ramifications for me over the years, but at the time it encouraged me to continue in the field that I did at the Harvard Department of Psychology. Soon after leaving Swarthmore I joined my graduate class in studies and social activities. In the beginning I was quite excited at the prospects and gung ho to go.

It was only much later that I realized how radical a change in culture was my shift from Swarthmore to Harvard. Of the faculty I knew, those of Swarthmore contrasted strongly with those of Harvard. In gross terms, the Swarthmoreans tended to be European in the image of Koehler: a subtlethinking, historically and esthetically oriented group. The Harvard psychologists were all American educated. The ethos was “entrepreneurial intellectuality” to coin a phrase. The general aim was to show how smart one could be. Prizes were awarded to the chosen, as for example, appointments to the Society of Fellows. With a few exceptions, the students seemed to be more interested in succeeding than in the substance of what they were doing and planned to do. Who would write the first book, be elected to an honorific society, be called to take a professorship in a prestigious university? These were the Harvard-defined goals of academia.

A few years before I joined the Harvard Department of Psychology it had split into two parts: the experimental psychologists on one hand and the Department of Social Relations in which the more social and clinical aspects of psychology were joined with sociology and social anthropology.

E. G. Boring was the putative head of the experimental group. He was a person with whom it was difficult to communicate—he seemed constantly uneasy in one’s presence. He had a generous policy of taking graduate students to lunch one at a time at the Faculty Club. At my lunch occasion I remember that he asked me about my experience with Wolfgang Koehler and talked about him extensively. How whatever Koehler did seemed to turn to gold. He was clearly quite envious of him. Gossip would have it that after Koehler delivered the William James lectures Harvard wanted to appoint him permanently in the Psychology Department, but Koehler couldn’t stand Boring. Although Boring was not renowned for his work in experimental science, he did write the most scholarly books on the history of sensation and perception.

S. Smith Stevens, known to everyone as Smitty, was Director of the Psychoacoustic Laboratory, which was established during the war to serve the military. He was another person with some difficulties communicating with people. He was quite friendly to me and claimed that I put him on a research track that he followed for many years after our encounter. As he reports the incident, he had been lecturing on scaling sensation, and I had quizzically asked if it might be possible to directly assign numbers to the qualities of sensation. For example, if you told a listener that he would hear two sounds with loudnesses 0 and 100, would all the intermediate loudnesses be assigned a series of numbers that varied in some rational order? He urged me to work on this problem of scaling sensation on the grounds that the results would be printed and reprinted in the handbooks until time immemorial. But I was too young at the time to be concerned about that issue.

Fred Skinner was to me somewhat of an enigma. He was a cultivated and talented individual, facts that seemed incompatible with his simplistic theory of behavior. He claimed that most behaviors were products of reinforcement schedules. You could do anything with appropriate reinforcement. He was truly the heir of J. B. Watson, who famously said “Give me the child and I shall make the man.” Like so many believers in simplistic theories, whose downfalls seem to result from life’s complexities—witness the Frenchman LaMettrie who wrote L’Homme Machine and then died of overeating—Watson found his downfall having illicit relations with young female students. Skinner managed to avoid such a fate. Then there was a younger group including George Miller and Jerome Bruner of computational and cognitive fame respectively and Edwin Newman who administrated.

Georg von Bekesy

My Ph.D. thesis committee was composed of Boring, Stevens, and Newman; but the person who really advised me knowlegeably was Georg von Bekesy, although he took no part in formal supervision. It was some time after I had begun working as a graduate student in the basement of Memorial Hall that I first saw Bekesy. As I stood in the hall one day a stooped-shouldered baldheaded man of medium height shuffled by paying no attention to either his surround or the people in it. Although his substantial reputation had preceded him, this peremptory passage left me with an initial impression of a shy and unimpressive man. Little did I suspect his depth of sensitivity and intelligence until considerably later when I had gotten to know him. Bekesy had been persuaded to join the Psychoacoustic Laboratory at Harvard, leaving behind positions he had held for many years in Sweden and before that in Hungary, his native land. He had worked as an engineer and troubleshooter for the Hungarian telephone company, which was a very important job because at that time Hungary was the telephone hub for central Europe. Telephone signaling was of poor quality, and Bekesy determined to find out why. After solving some of the purely physical problems, including the earphone to ear coupling, he realized that remaining problems of signal quality were in the ear itself. Undaunted, he proceeded to study the fate of signals in that organ. In an extraordinary research program he solved the classic problem of how the cochlea of the inner ear works and how lateral inhibition among neurons accounts for the high degree of pitch resolution that the ear displays. For that work he won the Nobel Prize.

How did I get to know Bekesy? In the laboratory it was customary to have a research meeting almost every week. Usually, one of our colleagues presented his or her work or an outsider was invited to do so. Bekesy often attended these meetings. My turn came, and with much trepidation I presented my far-out ideas. They were not greeted with much enthusiasm. But after the meeting Bekesy came up to me and said, “You presented too much.” He added, “When you speak to a group like that you should present only what they already know for the first forty minutes, then say one new thing.” I’ve tried to follow that advice. Although Bekesy prized his privacy, he usually left open the door to his laboratory. I passed by it often, and every time I did so I noticed a small sculpture or other icons on his laboratory bench. They seemed to change regularly. When I had become friendlier with him I often stepped into his laboratory for a better view. Occasionally he made comments on a particular piece. One I remember was a rather obtrusive and ugly wooden head peeking over onto his bench. He referred to it as the Lab Director. I began to realize that Bekesy must have a substantial collection of exquisite antique objects which was indeed the case. He had collected a set of Oriental and other antiquities that were the envy of the best museums in the world. He bequeathed the collection to the Nobel organization, which I learned disseminated it among several Swedish museums.

Independent Research

I mentioned earlier that I had begun to develop a research program of my own while still at Swarthmore College. One might have thought that I would follow my mentor and continue along lines that he had laid out and in which I had aided and abetted him during the 2½ years I spent at Swarthmore. But as I began to learn something about contemporary neuroscience—after all I had begun knowing nothing—I increasingly realized that however ingenious were Koehler’s ideas, they were far removed from current thinking among those who were practicing neuroscientists. The idea that field potentials played an appreciable role in brain function was diametrically opposed to the prevailing nerve cell doctrine in which the brain consists of vast numbers of neurons playing different roles and much information was transmitted by impulses traveling down axons at relatively high speed. Thus though Koehler’s work with my assistance was not taken seriously by most neuroscientists of the day, Koehler commanded respect for his long and productive history that could hardly be true for a newcomer to the field. Besides, I had already become interested in other researchable questions.

To trace the origin of my research I return to the waterfall illusion and the questions it raises. It is one of a large class of aftereffects that have intrigued observers and kept scientists busy for several centuries. The underlying issue these illusions raise is: what does it mean to claim that one sees the world correctly—We recognize that if our perceptions were habitually false we would be in deep trouble. How do we generally keep our perception of the world correct? Or is that the question to ask? Two general types of answer have been traditionally proposed. The first is to propose that the habitual state of adaptation is fairly uniform and keeps perception stable. For example, prolonged motion in one or another direction is relatively rare, and when it does occur, we learn to anticipate and counter its consequences. The second is the claim that perception has its own rules—sometimes referred to as Gestalt properties. That such rules lead to correct perceptions of the world could conceivably result from some sort of evolutionary selection of rules that are in accord with the properties of the environment. But there is a third possibility, namely, that the concept of correctness is misleading. That an illusion simply reflects an extreme case of the operation of the process of perception. When those processes are understood, so will the illusions. As Johannes Purkinje wrote in the early nineteenth century: “Illusions are the truths of perception.”

When I became a graduate student at Harvard and sought a research position I soon discovered that such positions were possible if one worked in the domain of hearing, not vision. That situation resulted from the fact that the major source of research funding was the PsychoAcoustic Laboratory headed by S. Smith Stevens. At that point I had sufficient confidence in my theory of adaptation to what I called “visual rearrangement” that I was ready to apply it to audition as well. Consequently, I developed an auditory analog of prism rearrangement. In effect, I rotated the ears of experimental subjects by a small angle around the head. This was done by interposing microphones connected to hearing aid amplifiers over the natural ears. The positions of the substitute ears and their separation determine the interaural differences in times of arrival of sound at the two ears. And those differences determine the perceived positions of sound sources. The outcome of prolonged wearing of this device was indeed a shift in the direction of heard sound sources. Most interesting was the doubling of the apparent source of sound after the wearer had spent hours wearing the device and walking around Harvard Square to the amusement of passersby. This research became incorporated into my Ph.D. thesis, demonstrating adaptation of auditory localization and published in the American Journal of Psychology (Held, 1955).

After completion and acceptance of my thesis, I applied and was awarded a National Science Foundation postdoctoral research fellowship that kept me at Harvard for another year and a half. During that time I explored the process of adaptation to the edge colors caused by dispersion of wavelengths of white light seen through a wedge prism. I came close to discovering the startling aftereffect found by Celeste McCullough a few years later; but her work, which demonstrated the orientational selectivity of edge colors, followed the very significant discovery of orientation selective cells in visual cortex by Hubel and Wiesel, which gave her the idea of testing for the orientational selectivity (Held, 1980).

Brandeis University

At some point during my stay at Harvard I began to wonder about the future. By that time Doris Bernays, a student at Radcliffe College and I had married and had settled in the area. But where would I find a job? Once again Meyer Schapiro supplied an answer. He suggested that the new university, named after the celebrated jurist Louis Brandeis, and supported by the Jewish community, was looking for young faculty, and he would recommend me to the appropriate people. I made an appointment to interview Abraham Maslow who was chairman of the Psychology Department. We found each other congenial. When Meyer Schapiro and Wolfgang Koehler supported my application I was quickly appointed as an Instructor in 1953 with a salary of $4,000 per year. I can’t say that I was overcome by the magnitude of this salary. Quite the contrary, I had already been offered more to work at one of the local government-supported laboratories. But I wanted to set up my own laboratory and to teach subjects I enjoyed. The transition to Brandeis was easy. The only practical change would be the 20-minute commute to Waltham.

At that time Brandeis was in its fourth or fifth year of existence. It would grow greatly during the next decades, giving new faculty the opportunity to shape many aspects of the growing entity. Already the faculty was an unusual group of people for an academic entity. The political left was well represented by people who wrote for the Partisan Review and its offspring, Dissent. They included literary luminaries of the left such as Irving Howe, Bernie Rosenberg, and Philip Rahv among others. The political sociologists included Lewis Coser and Herbert Marcuse. It was an intellectually stimulating place.

From the top down the faculty of Psychology were a mixed group of theorists. They were a likeable bunch, but as scientific colleagues I didn’t find them challenging that ultimately was a reason for my departure from Brandeis. In 1953 when I joined the Brandeis Faculty there were five of us in the Department of Psychology. The Chair was Abraham Maslow, a congenial man who led with a light touch. Having himself chosen the faculty, he was quite supportive of us as well as generously laudatory. At the time he was propounding his theory of self-actualization—a sort of peptalk exhorting people to develop their assets wherever they might lead. His ideas must have been in accord with the Zeitgeist because they caught on among various strata of people ranging from rebellious young men like Abby Hoffman, who at the time was a student at Brandeis, to Business School professors seeking to energize their students. Maslow became an icon for diverse people eager for new ideas. I must confess that as much as I liked him, I couldn’t take his ideas seriously. I can’t resist mentioning a bizarre experiment he got some students to perform. Conjuring up the idea that female breast size had something to do with maternal instinct, he had students measuring the diameters of the breast aureolae of their female classmates as well as taking a verbal test of their maternal predilections. There were no scientific review boards at the time. I never learned whether a correlation was found.

Then there was Jim Klee, a huge man from the Midwest who had gained his degree in one of the departments of psychology whose faculty we, in the more enlightened departments, called “dustbowl empiricists.” He had rebelled against that ideology, as had Maslow, and was developing a new theory of behavior that I could not comprehend. He was otherwise distinguished by having had built the largest chair I have ever seen and placed it in the lecture hall. Then there was Ricardo Morant, who was my contemporary and also an experimental psychologist, although he seemed to prefer theorizing to experimenting. His family came from Catalonia, and he was very proud of that origin. He obtained his degree from Clark University and had the earmarks of a student of Heinz Werner and Seymour Wapner, who were the experimental types at Clark University among a friendly group of theorists and clinicians.

Last, but not least, was the lone female, Eugenia Hanfman, a rather distinguished person who taught and served as head of the counseling services of the University. As a young emigree from Leningrad, she had studied with Kurt Lewin in Germany and then migrated to the States with her old mother and brother, a Professor of Fine Arts at Harvard specializing in ancient artifacts. Known as Genia she was admired by all for her sense of humor and sound judgment. Occasionally I would drive her home from Brandeis. On one occasion she told me that she was going on half-time during the next semester as a partial sabbatical. I immediately asked her what she would do with the other half. She sort of sighed and said, “Why must I do something during that other half—it isn’t necessary to fill up time. You Americans!!!!” She had given me a new perspective but not one I could adopt.

Brandeis proved a good environment for young faculty including myself who were ambitious to develop their careers. The teaching load was reasonable—a class or two per semester. Over time I taught Statistics, History and Theory, Comparative Psychology, and Experimental Laboratory. The course I was best prepared to teach (perception) was already taught by Morant, and he kept doing so. That was just as well for me because I then had to learn more and having to teach was the best way. I particularly enjoyed teaching inductive statistics whose logic to me always had the intriguing sensation of getting something from nothing.

Princeton Institute

During my second year at Brandeis I received an invitation to spend a year at the Institute for Advanced Study at Princeton. Koehler was to be there and must have proposed that I join him. It was a memorable year during which I met and exchanged ideas with many interesting fellows of the Institute. Early on, I was interviewed by the Director, J. Robert Oppenheimer hero of the development of the atom bomb, who had recently had the devastating experience of being denied his security clearance for alleged disloyalty. I was ushered into his office and seated across from him. While loading his ever-present pipe he asked me what I was interested in doing in my field. I said I wanted to apply mathematics to deal with certain perceptual puzzles. He puffed his pipe and then said, “You must beware the Pythagorean Mystique.” I did not respond in like manner although I would have liked to. I spent a good bit of time with the art historian Leopold Ettlinger whose colleague Ernst Gombrich visited and took us to attend his lecture at the Smithsonian. The material was incorporated in his book Art and Illusion that I reviewed (Held, 1960). Alexander Koyre and Irwin Panofsky were two other very stimulating presences with whom I had some contact at the Princestitute, as Lukas Teuber dubbed it.

During my year at the Institute I did a lot of thinking about aftereffects and staring at stationary patterns of lines. The outcome of these experiments was a broadening of my concept of figural aftereffects and an anticipation of the extensive use of the analysis of patterns by spatial frequency and phase (Held, 1962). I wrote a grant proposal and submitted it to the National Science Foundation. The award was a great stimulus to developing an active laboratory. I was eager to do experiments and to engage graduate students who were coming in small numbers to our department at Brandeis. With grant funding we could build apparatus and even pay small stipends to student research assistants. My first graduate student was Alan Hein who, 50-plus years later, is currently a colleague at MIT. Joe Bossom and others soon followed. During my 8 years at Brandeis I had about a dozen students working in my laboratory including graduate and undergraduates. Much of our work dealt with prism rearrangement experiments: displacing, extending, and rotating the visual field and measuring the adaptive results of exposing the wearers of these optical devices to the environment. They resulted in a series of presentations at meetings and publications mostly coauthored with my graduate students (Held and Bossom, 1961; Held and Hein, 1958; Held and Rekosh, 1963; Held and Schlank, 1959; Mikaelian and Held, 1964; summarized in Held, 1965). We also introduced the disarrangement experiment in which a continuously variable prism was used and demonstrated degradation of the accuracy of reaching (Held and Freedman, 1963). At that time we began animal experiments based on conclusions drawn from the rearrangement experiments. They had shown that active movement in space was important for adaptation of the moving body or part of body that when prolonged could lead to full and exact compensation for the initial errors introduced by rearrangement. But if the adaptive process can yield full and exact return of correct function, then it should be capable of compensating for any neonatal errors and may even account for initial development, a proposal that got us into the nature–nurture arena.

Alan Hein and I set out to test our theory of the early development of visual–motor coordination in kittens based on the results of our rearrangement experiments. Alan built a small breeding colony of cats to supply us with newborn kittens and proceeded to demonstrate the importance of selfproduced movements in development in accord with our theorizing. This research involved what became known as the “kitten carousel” in which one kitten actively moved itself while pulling a coupled but passive mate so as to equate their purely visual exposure. The former developed its visual guidance of behavior while the latter remained deficient. This experiment caught the attention of the field and “Heldenhein” became a household word among experimental psychologists (Held and Hein, 1963).

Another then-contemporary graduate student, Burton White, wished to work with human infants. He found a source of infants being reared in somewhat impoverished environments in a state-supported institution. He then showed that increased opportunity to engage their environment speeded up their development of sensorimotor coordination in accord with the ideas we had developed (White et al., 1964)

Although later work was more sophisticated, the enthusiasm for research of that early group at Brandeis was never exceeded. It was during that period that my wife and I grew a family. In a period of 4 years, Lucas, Julia, and Andrew were born in succession. I rose in the professorial ranks from instructor to tenured professor within a few years. In my 7th year Maslow, the Department Chair, went on leave and I was asked to fill his position on a temporary basis. I did so but had enough of administration after a year. Moreover, Hans-Lukas Teuber, an acquaintance I had met through Koehler, was about to become the Head of the Psychology Section at MIT and had indicated an interest in having me accept an appointment. I needed to make a choice. Luckily I was eligible for a sabbatical and took the opportunity to spend the year at MIT so as to test the waters. My experiences at Brandeis had been very favorable, but MIT offered a much greater challenge and opportunity to be among people who were closer to my interests than those available at Brandeis. In addition I did not relish the thought of becoming Chair of the Brandeis department. Although I liked many of the individuals, I had no desire to take on the problems of governance of a group, much of whose interests and work was remote from mine.

MIT and Hans-Lukas Teuber

When I moved to MIT in 1963 the section had just been housed in a refurbished three-story loft building numbered E-10 that was Spartan in its furnishings but adequate. There were about a dozen faculty, several of whom had antedated Hans-Lukas Teuber’s appointment as Head of the section. Within a year or two all of the latter had left leaving open several faculty slots soon filled with new appointments. A few postdocs, and a scattering of venturesome graduate students filled out the ranks including Stuart Sutherland, a larger-than-life swashbuckling experimentalist visiting from England. After a few years the Section had grown in size, funding, and reputation to the stage where it was ready to become a Department with all its rights and privileges.

Before coming to MIT Teuber had spent years studying the sensory capabilities of brain-injured patients. At that time access to the real brain was quite limited compared to the present situation, yet Teuber and his colleagues had done creditable work with the tools available. Perhaps more important, his exposure had persuaded him that the future of our field lay in the direction of what later came to be called “neuroscience.” Consequently, he conceived of his new department as one combining the best of system neuroscience with experimental and cognitive psychologies. In so doing he anticipated the wave of the future. Accordingly, Teuber recruited faculty as diverse as Walle Nauta, the distinguished neuroanatomist, and Jerry Fodor, the young philosopher-psycholinguist, so that the Department represented a diverse spectrum of disciplines all within the potential rubric of brain and cognitive sciences, which many years later became the name of the Department. In later years several of the graduates of the Department were hired (Whitman Richards, Gerald Schneider, and Ann Graybiel), a form of inbreeding that didn’t seem to hurt the Department at all. This diversity of faculty interests was good and bad for a small Department. The good part was the strong intellectual interaction among its members. The bad part was that it put us at a disadvantage when we were compared with other departments in our field. We did not have the strength in numbers in any one specialty possessed by one or another more monolithic department.

I should mention here another pioneering group in the development of neuroscience and one which originated the name. The Neurosciences Research Program was founded and run by Frank Schmitt, an MIT Professor of Biology who was the prophet of neuroscience. The Program ran seminars and gatherings of groups of scientists, including myself, chosen by Schmitt and his advisors to come together to exchange their knowledge in the interests of making progress in understanding brain and nervous system. George Adelman and Theodore Melnechuk edited their publications, which were circulated widely. The group, fondly known as The Schmitt Circus, deserves much credit in furthering the development of neuroscience.

Department Head

Under Teuber’s benevolent leadership, the Department flourished as did its members for the most part. In addition to his administrative duties and professional obligations he managed to teach the elementary course to great acclaim and to continue his research and supervision of students. But catastrophe struck in 1977. While swimming on holiday in the Virgin Islands, he was swept out to sea by a tidal current and disappeared. In the wake of his loss I became Head of Department, first temporary then full term. My inclination was to preserve and enhance what had been a good thing: a group of about a dozen congenial faculty with a graduate program awarding the Ph.D. and a minor for undergraduates. For several years this policy succeeded in increasing the faculty with appointments, particularly in the computational area with David Marr and Tommaso Poggio. But with the rapid growth of neuroscience, we began to realize that we needed more strength in the biological areas and more space to accommodate the expansion.

It was at this point that the top administrators had a brainstorm. Under pressure from the Whitaker family, which had made a large grant for a new building to accommodate a proposed medical school at MIT, they saw a means to achieve several goals with one action. Whitaker College, in collaboration with Harvard Medical School, had set up a quasi-medical program assembled under a medical director (Irving London). It then had a motley crew of faculty, assembled from various corners of the Institute, that sparsely occupied the new building. Their proposal was to split our department into wet and dry science sections and move the wets into Whitaker College, thereby raising the number and quality of its faculty and filling the new Whitaker building. The adverse effect of breaking up our department was hardly considered despite our protests. It has been only in recent years that this fissure has been remedied by the recombination and expansion of the faculty of Brain and Cognitive Sciences and the availability of its own building. We hope that some of the original elan of the Department will be re-created.

After leaving Brandeis with our fairly extrensive laboratory it was necessary to re-create it at MIT. With the initial help of Alan Hein, who joined the faculty in the following year, we did just that. And throughout the succeeding years, including my administrative service as Department Head and beyond, I maintained my research laboratory and managed to obtain continuous funding for it from grants and contracts until I relinquished the leadership of the laboratory. Of course I had excellent help throughout, although anyone who runs a large laboratory knows that “help” is an inadequate word for the kind of support that research associates can provide. In that vein a most significant human addition to our laboratory was the employment of Joseph Bauer. After having done a fair number of studies of kitten development (Hein and Held, 1967; Hein et al., 1970), we wished to proceed to study development in a primate. For that purpose I contacted Harry Harlow, who was doing extensive research with infant monkeys and asked him if he could recommend to us a source of help in developing that capability. He quickly recommended Joe who at the time was one of his graduate students who had not yet found a thesis problem and perhaps needed a change of milieu in which to do so. It was a fateful decision for all of us. Joe not only set up a successful breeding colony of stumptailed monkeys, he managed to test them with devices he made (Bauer and Held, 1975; Held and Bauer, 1967), and in a short time became usefully involved in most of our ongoing laboratory activity to the great benefit of people in the laboratory. After 20-plus years, he had done the work of many thesis projects without receiving the award, but by then I don’t think it mattered to him.

Together with student involvement we continued with rearrangements and related experiments in the succeeding years. We kept up a barrage of oral presentations at professional meetings and of follow-up publications on the research and thinking we had done (Efstathiou et al., 1967; Graybiel and Held, 1970; Hardt et al., 1971; Held et al., 1966). One product of the diversity of disciplines within our department was the realization among a group of us that the visual system had two modes of functioning, the “what” and the “where” (Held, 1968). Evidence came from neuronal as well as behavior study (Held, 1970). A few years later Mortimer Mishkin’s group identified this distinction with the anatomical difference in function between dorsal and ventral projections from striate cortex. Another product of this distinction was our discovery that the latter mode of vision remained even when the former had been destroyed by blinding lesions of the visual cortex (Poeppel et al., 1973). Lawrence Weiskrantz subsequently made a career of exploring this phenomenon under the name “blindsight.” Still another direction our research took at this time was the exploration of adaptation of combined color and edge channels with the collaboration of Stefanie Shattuck (Held and Shattuck, 1971; Shattuck and Held; 1975; summarized in Held, 1980).

After some years our laboratory had gained sufficient notoriety to attract postdoctoral researchers and visiting faculty. Some also contributed to our research. Johannes Dichgans, Laurence Young, and Thomas Brandt initiated our studies of vection: visual motion that induces feelings of bodily movement (Dichgans et al., 1972; Held et al., 1975). Several graduate students then took up the vection research (Finke and Held, 1978; Finke et al., 1984; Merker and Held, 1981; Wolfe and Held, 1979).

By the mid-1970s our work on rearrangement had also begun to attract criticism, in good part well meant but some simply following the tendency of competitors to attempt to destroy what they hadn’t produced themselves. This discouraging criticism seemed to peak at the time of growing interest in the very early development of primate vision following the discoveries of control of neuronal development by conditions of rearing by David Hubel, Torsten Wiesel, and others. Together these factors made for a change in our research directions. For us the challenge became to develop methods of testing the vision of human infants as soon after birth as possible so as to study the human parallels to the early-rearing research with animals. Consequently we turned the direction of our efforts to that set of problems while phasing out the rearrangement work. Our first effort succeeded in showing that infant vision exhibits an oblique effect at a few months of age. In other words their acuity is less for oblique edges compared with verticals as imaged on the retinae (Leehey et al., 1975).

It was at this point that we had the good fortune to add Jane Gwiazda, a recent psychology Ph.D. from Northeastern University, to our laboratory as a postdoctoral fellow. She quickly developed the skills needed to measure the early visual capacities of human infants and, with the help of Anne Moskowitz, Sarah Brill, and Indra Mohindra, pioneered in obtaining previously unknown measurements of refraction (Mohindra et al., 1978) and visual acuity (Gwiazda et al., 1978). Our discovery of the high incidence of astigmatism in young infants was greeted by castigation from some ophthalmologists who had themselves failed to observe it. Later we discovered it had been found by an obscure Italian ophthalmologist who had published it in an obscure journal many years before. Over the years Jane’s talents enabled a progressive increase in her leadership of the infant research of the laboratory.

During those years a continued stream of infants was tested repeatedly over time to obtain various other measurements of vision, each of which provided a student with a program of research leading to a doctoral degree or postdoctoral achievement. Thus Eileen Birch worked on stereoacuity (Birch et al., 1982; Held et al., 1980), Shinsuke Shimojo on vernier acuity (Shimojo et al., 1984), and Janice Naegele on optokinetic nystagmus (Naegele and Held, 1982). We also did studies of the consequences of early pathology in conjunction with Samuel Jacobson, an ophthalmologist then stationed at the Eye and Ear Infirmary (Jacobson et al., 1981).

From the beginning of this research with infants, at each experimental session we had our subjects refracted by a participating optometrist from the New England College of Optometry situated just across the Charles River in Boston. As I recall, it was my friend Herschel Liebowitz who originally suggested that we incorporate measures of refraction in our research. At first the refracting was done by Indra Mohindra, who first found the high incidence of myopia. She was followed by Mitchel Scheiman for a time and then by Frank Thorn who was not only skilled in optometric measurements but knowledgeable in all aspects of vision science. He became a fixture in the laboratory and continues to be so. As a result of collecting time sequences of refraction measurements as our subjects aged over the years, we began to see in some the onset of myopia as they reached school age. That meant that we possessed what was to our knowledge the first-ever collected set of measurements of the developmental course of myopia over the preceding years (Gwiazda et al., 1993). With these potentially valuable data in hand we turned the laboratory’s attention to further collecting refraction and other ocular measurements in an effort to better understand the etiology of myopia, a serious health problem (Gwiazda et al., 1995, 2000; Thorn et al., 2005). By this time several investigators had shown with animal models that the development of myopia is influenced by early conditions of vision and we sought the human parallels.

New England College of Optometry

In 1986 after 9 years as Head of Department I stepped down, and Emilio Bizzi was appointed. Apart from relief of responsibility, the other change I noticed after a time was my reduced power over decision making. The latter became obvious when the time came for advancement of faculty I favored. Partly as a result of appointments that I had previously pushed through, the Department ethos had moved strongly toward favoring computational research as the promising direction of effort. Two candidates, Jeremy Wolfe, my former student, and Jane Gwiazda, by now a junior faculty member, that I favored were turned down for advancement despite excellent records essentially because they were not computationalists. When this bias was shared even by mathematically innocent faculty it seemed to me time to recall Oppenheimer’s advice to me—see page 30. The failure to advance Jane opened the possibility that she would leave, and our collaboration would end just at the time that we seemed to have a real handle on the myopia problem. But a new development saved the day. Over the years we had developed a good relationship with members of the New England College of Optometry across the river. At about this time they had developed a desire to expand their efforts in research. And what better could they do than acquire a laboratory which was doing ground-breaking research in a field of central importance to their mission? The College made us an offer we could not refuse—appropriate appointments for three of us and plenty of space to accommodate our needs. We moved the laboratory in September 1995, and it has remained there ever since under the able leadership of Jane Gwiazda. I continued my participation in this research and also retained an office at MIT convenient for participating in nonadministrative departmental activities.

Back to the Future

After 10-plus years working with Jane and colleagues at the College of Optometry, we have made a series of interesting findings, but a fundamental understanding of the myopigenesis process has so far eluded us and, incidentally, everyone else in this field. The basic genetics need to be worked out to obtain an explanation of the modulation effected by early environmental interaction. I have returned in spirit and actions to MIT to spend my time in the newly unified Department of Brain and Cognitive Sciences, aggregated in an impressive new building. The Department Chair, Mriganka Sur, kindly offered me the use of an office to be shared with Alan Hein.

However, my very congenial young colleague and friend, Pawan Sinha, made me an offer I couldn’t refuse to occupy an office in his laboratory suite among his very capable laboratory group. He also invited me to collaborate in Project Prakash, a remarkable combination of medical endeavor to restore vision in curably blind patients and of testing procedures to understand the recovered sight of the previously sightless. The work is being carried out in India, and not long ago I had the fascinating experience of visiting there as can be proved by an examination of the background of my photograph taken by a close colleague. I participated with Pawan and colleagues in the examination of several newly sighted young patients. Among other observations that have been made on these patients are those that constitute a test of the 300-year-old Molyneux question:

Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere of the same metal, . . . Suppose then the cube and sphere placed on a table, and the blind man be made to see: query, whether by his sight, before he touched them he could now distinguish and tell which is the globe, which the cube?

Currently we are preparing reports of the outcomes of these tests. Apart from participating in the activities of the laboratory, here I sit at MIT once again reviewing the extensive body of rearrangement experiments. I now view them as having revealed only the tip of the iceberg of sensorimotor functions. We require a new and broader conception of the nature of adaptation and stability of coordination. I hope to make a contribution in that direction.

Postscript

Writing this biography has been an interesting exercise, reviving many memories of people and actions past. I view my career as a long ride with many ups and downs. I have always told my students that doing science had better be fun because you won’t earn enough to buy it. I must have followed my own advice because I wouldn’t have had it otherwise. Moreover I don’t believe in retirement for retirement’s sake and look forward to continued enjoyment in research. I hope I have done justice to the many individuals with whom I have been in contact who have enriched my work and life. If not, I regret the oversight.

Selected Bibliography

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Birch EE, Gwiazda J, Held R. Stereoacuity development for crossed and uncrossed disparities in human infants. Vision Res 1982;22:507–513.

Dichgans J, Held R, Young LR, Brandt T. Moving visual scenes influence the appparent direction of gravity. Science 1972;178:1217–1219.

Efstathiou A, Bauer JA, Greene M, Held R. Altered reaching following adaptation to optical displacement of the hand. J Exp Psychol, 1967:73:113–120.

Finke R, Held R. State reversals of optically induced tilt and torsional eye movements. Percept Psychophys 1978;23:337–340.

Finke RA, Pankratov M, Held R. Dissociations between perceptual and oculomotor effects induced by rotating visual displays. In Wooten B, Spillmann L, eds. Festschrift for Ivo Kohler: Sensory experience. Adaptation and perception. Hillsdale, NJ: Erlbaum Associates, 1984;303–316.

Graybiel AM, Held R. Prismatic adaptation under scotopic and topic conditions. Journal of Experimental Psychology 1970;85:16–22.

Gwiazda J, Bauer J, Thorn F, Held R. A dynamic relationship between myopia and blur-driven accommodation in school-aged children. Vision Res 1995;35: 1299–1304.

Gwiazda J, Brill S, Mohindra I, Held, R. Infant visual acuity and its meridional variation. Vision Res 1978;18:1557–1564.

Gwiazda J, Grice K, Held R, McLellan J, Thorne F. Astigmatism and the development of myopia in children. Vision Res 2000;40:1019–1026.

Gwiazda J, Thorn F, Bauer J, Held R. Emmetropization and the progression of manifest refraction in children followed from infancy to puberty. Clin Vision Sci 1993;8:337–344.

Hardt ME, Held R, Steinbach MJ. Adaptation to displaced vision: a change in the central control of sensorimotor coordination. J Exp Psychol 1971;89:229–239.

Hein A, Held R. Dissociation of the visual placing response into elicited and guided components. Science 1967;158:390–392.

Hein A, Held R, Gower EC. Development and segmentation of visually-controlled movement by selective exposure during rearing. J Comp Physiol Psychol 1970; 22:181–187.

Held R. Shifts in binaural localization after prolonged exposures to atypical combinations of stimuli. Amer J Psychol 1955;68:526–548.

Held R. Perception and representation. E. H. Gombrich’s Art and Illusion, Yale Review 1960;49: 607.

Held R. Adaptation to rearrangement and visual-spatial aftereffects. Psychologische Beitrage 1962;6(3/4):439–450.

Held R. Plasticity in sensory-motor systems. Sci Amer 1965;213:89–94.

Held R. Dissociation of visual functions by deprivation and rearrangement. Psychologische Forschung 1968;31:338–348.

Held R. Two modes of processing spatially distributed visual stimuli. In Schmitt FO, ed. The neurosciences: Second study program. New York: The Rockefeller Press, 1970;317–324.

Held R. The rediscovery of adaptability in the visual system. In Harris CS, ed. Visual coding and adaptability. Hillside, NJ: Lawrence Erlbaum, 1980;69–94.

Held R, Bauer JA. Visually guided reaching in infant monkeys after restricted reaching. Science 1967;155:718–720.

Held R, Bauer JA. Development of sensorially-guided reaching in infant monkeys. Brain Res 1974;71(2–3):265–271.

Held R, Birch EE, Gwiazda J. Stereoacuity of human infants. Proc Natl Acad Sci 1980;21:5572–5574.

Held R, Bossom J. Neonatal deprivation and adult rearrangement: complementary techniques for analyzing plastic sensory-motor coordination. J Comp Physiol Psychol 1961;21:33–37.

Held R, Dichgans J, Bauer, JA. Characteristics of moving visual scenes influencing spatial orientation. Vision Res 1975;15(3):357–365.

Held R, Efstathiou A, Greene M. Adaptation to displaced and delayed visual feedback from the hand. J Exp Psychol 1966;72:887–891.

Held R, Freedman SJ. Plasticity in human sensorimotor control. Science 1963;142:455–462.

Held R, Hein A. Adaptation of disarranged hand-eye coordination contingent upon reafferent stimulation. Percept Mot Skills 1958;8:87–90.

Held R, Hein A. Movement-produced stimulation in the development of visually guided behavior. J Comp Physiol Psychol 1963;56:872–876.

Held R, Rekosh J. Motor-sensory feedback and the geometry of visual space. Science 1963;141:722–723.

Held R, Schlank M. Adaptation to disarranged eye-hand coordination in the distance-dimension. Amer J Psychol 1959;12:603–605.

Held R, Shattuck SR. Color and edge sensitive channels in the human visual system. Science 1971;174:314–315.

Jacobson SG, Mohindra I, Held R. Age of onset of amblyopia in infants with esotropia. Doc Ophthalmol, Proceedings Series 1981;lQ:210–216.

Koehler W, Held R. The cortical correlate of pattern vision. Science 1949;110: 412–419.

Koehler W, O’Connell D, Held R. An investigation of cortical currents. Proc Amer Philos Soc 1952;96:290–330.

Leehey SC, Moskowitz-Cook A, Brill S, Held R. Orientational anisotropy in infant vision. Science 1975;190(4217):900–902.

Merker B, Held R. Eye torsion and the apparent horizon under head tilt and visual field rotation. Vision Res 1981;21(4):543–547.

Mikaelian H, Held R. Two types of adaptation to an optically-rotated visual field. Amer J Psychol 1964;22:257–263.

Mohindra I, Held R, Gwiazda J, Brill S. Astigmatism in infants. Science 1978;202: 329–331

Mohindra I, Jacobson SG, Thomas J, Held R. Development of amblyopia in infants. Trans Ophthal Soc UK 1979;99:344–346.

Naegele JR, Held R. The postnatal development of monocular optokinetic nystagmus in infants. Vision Res 1982;22:341–346.

Poeppel E, Frost D; Held R. Residual visual functions after brain wound involving the central visual pathways in man. Nature 1973;243:295–296.

Shattuck S, Held R. Color and edge sensitive channels converge on stereo-depth analyzers. Vision Res 1975;12(2):309–311.

Shimojo S, Birch EE, Gwiazda J, Held R. Development of vernier acuity in infants. Vision Res 1984;2i:721–728.

Thorn F, Gwiazda J, Held R. Myopia progression is specified by a double exponential growth function. Optometry and Vision Science 2005;82(4):286–297.

White BL, Castle P, Held R. Observations on the development of visually-directed reaching. Child Dev 1964;22:349–364.

Wolfe J, Held R. Eye torsion and visual tilt are mediated by different binocular processes. Vision Res 1979;12:917–920.

Leslie L. Iversen

BORN:

Exeter, England

October 31, 1937

EDUCATION:

Cambridge University, B.A. (Biochemistry) (1961)

Cambridge University, Ph.D. (Pharmacology) (1964)

APPOINTMENTS:

Postdoctoral Fellow, National Institutes of Health (1964–1965)

Postdoctoral Fellow, Harvard Medical School (1965–1966)

Research Fellow, Trinity College, Cambridge (1966–1967)

Locke Research Fellow, Cambridge University (1967–1970)

Director MRC Neurochemical Pharmacology Unit, Cambridge, (1970–1983)

Director Neuroscience Research Centre, Merck Sharp & Dohme Ltd, Harlow, UK (1983–1995)

Vice-President Neuroscience, Merck Research Labs (1986–1995)

Visiting Professor of Pharmacology, Oxford University (1995–)

Director, Wolfson Centre for Age Related Diseases, King’s College, London (1999–2004)

HONORS AND AWARDS:

Gaddum Lecturer, British Pharmacological Society (1971)

F. O. Schmitt Lectureship, MIT, USA (1974)

Associate of Neuroscience Research Program, MIT, USA (1975–1984)

Fellow of the Royal Society, London (1980–)

Honorary Member, American Academy of Arts and Sciences (1981–)

Rennebohm Lecturer, University of Wisconsin, USA (1984)

Ferrier Lecturer, Royal Society, London (1984)

Foreign Associate Member, National Academy of Sciences USA (1986)

Honoured Professor, Beijing Medical University, China (1988)

Hans Kosterlitz Memorial Lecturer, British Physiological Soc (2000)

Wellcome Gold Medal in Pharmacology, Brit. Pharm. Soc (2003)

Lifetime Achievement Award, Brit. Assoc. Psychopharmacology (2006)

Leslie Iversen has been at the forefront of research on neurotransmitters and neuropeptides and understanding the mode of action of CNS drugs. In his early work on catecholamines he was among the first to describe the detailed properties and pharmacological specificity of the noradrenaline transporter (NAT) in sympathetic nerves and brain, and he helped to strengthen the concept of antipsychotic drugs as dopamine receptor antagonists. In his work on GABA he participated in the first demonstration of the release of GABA on activation of an inhibitory synapse, and was the first to describe GABA uptake into inhibitory nerve endings in mammalian brain. In the field of neuropeptide research his efforts were eventually rewarded whilst working at Merck Research Laboratories by the development of the substance P receptor antagonist aprepitant as a novel treatment for nausea and vomiting associated with cancer chemotherapy. He has been keen to explain the complex scientific issues associated with the use of psychoactive drugs to a general audience, and has written books about marijuana and amphetamines.

Leslie L. Iversen

I was born in the West Country of England, in the beautiful cathedral city of Exeter, in October 1937. My parents came to England from Denmark in the 1920s, so I was almost a first-generation immigrant. My father was the 10th child in a poor farming family, and he was sent to England to be educated and to work for the Danish farmers’ cooperative movement—which had established the Danish Bacon Company to help sell Danish agricultural produce in England. He eventually became manager of the company branch in Exeter—responsible for distributing Danish produce to the many small grocers throughout the West Country.

By the standards of the 1930s, our family was reasonably well-off. We lived in a large house with enough land to grow our own vegetables and fruit, and to keep pigs, chickens, and a cow. These proved very valuable assets when the World War II brought severe shortages of food with strict rationing. I was also doubly fortunate in escaping the 5 years of Nazi occupation that the rest of our family suffered in Denmark. Although neither of my parents had been to the university, our home had plenty of books, and education was much prized. I was fortunate to succeed in gaining a place at the local grammar school, Hele’s School, at the age of 11 and received a firstrate education there. It soon became clear that science was what fascinated me—and I developed a strong interest in biology and the natural world.

My elder half-brother Niels, who was studying botany at Exeter University, inspired me to become interested in plants—and I soon amassed a large collection of pressed wild plants—and learned the precise Latin names of most of them. This stood me in good stead later when I applied for a scholarship at Cambridge University. I applied to read botany, and during the interview at Cambridge I was shown a long bench on which local plants and wild flowers had been laid out. To the surprise of the interviewer I was able to walk along the bench identifying virtually every specimen with its correct Latin name! This surely helped in gaining me the scholarship and led to me to many happy years as a student and scientist in Cambridge. In retrospect this was a very lucky break. My parents as recent immigrants were quite unfamiliar with educational system in England—and without good advice from my schoolteachers I would never have thought of attempting a place at one of Britain’s top universities.

But before enjoying the privileges of a Cambridge education I had first to serve for 2 years in Her Majesty’s Royal Navy—military service was obligatory in those days.

I was trained to operate the coding machines used for secure communication at sea and sent to the island of Malta for the remaining 18 months of my service. I was attached to a submarine depot ship that never went to sea—but was able to get some sea voyages on destroyers—and enjoyed the Mediterranean recreations of dinghy sailing and scuba diving. My time in the Navy was good for me; as a shy child I had to learn how to live in close quarters with others and to fend for myself.

Student Life in Cambridge

In October 1958 I entered the new world of Cambridge, where I was a member of Trinity College. Here I studied natural sciences—initially physiology, chemistry, and botany. Trinity College had many famous physiologists, the Nobel Laureates Edgar Adrian, Alan Hodgkin, and Andrew Huxley, together with visual physiologist Horace Barlow and neurologist Patrick Merton. I remember vividly one of my first tutorials with Andrew Huxley in 1958, 5 years before he was awarded the Nobel Prize for Physiology and Medicine. Tutorials were and are one of the very special features of a Cambridge or Oxford education. In addition to the University lecture courses, students spend an hour each week in their College with an expert in each of the subjects they are studying—sometimes alone, more often in groups of two or three.

Immediately after 2 years of military service it was struggle to get back to the world of learning. Huxley launched into a discussion of how action potentials were transmitted along nerve fibers and soon got into an analysis of this in terms of “cable theory” that involved some fairly complicated mathematics. My partner (who had also recently ended military service) and I compared notes later and found that we had not understood most of this. Next week at the tutorial I plucked up courage to tell Huxley that we were having difficulty following him, particularly the calculus involved. He was amazed that anyone at Trinity could have difficulty in understanding calculus and said, “In that case, I hope that you are not contemplating a career in research.” Fortunately I did not take his advice seriously!

Although I went to Cambridge with a scholarship to study botany, the classical manner in which the subject was taught in Cambridge in those days soon put me off—it emphasized taxonomy and classification, which was no longer exciting to me. At the end of my first year I abandoned botany in favor of the far more glamorous biochemistry—which was entering one of its most flourishing periods in Cambridge—this was only a few years after Crick and Watson described the double helix. Biochemistry became my sole focus for the final year, in a class of 40 students, and it was very well taught.

Meanwhile I had met and fallen in love with Susan Kibble, another grammar school student, also studying natural sciences. We met in the practical laboratory when studying physiology—and despite this prosaic beginning we have lived happily together ever since. We married at the end of our undergraduate years in 1961. Sue developed a very successful research career in experimental psychology, and later became Head of the Department of Experimental Psychology in Oxford and subsequently a Pro-Vice Chancellor of the University.

Sue and I almost automatically assumed that we would stay in Cambridge for postgraduate studies if at all possible—although making satisfactory arrangements for Ph.D. study that would suit both of us was not easy; but again we were lucky. Sue joined the Department of Experimental Psychology, to be supervised by Larry Weiskrantz, an expert in the study of higher brain functions in primates. She worked on memory mechanisms in monkeys. I was also committed to studying the brain—having been strongly influenced by another member of the Huxley family on reading Aldous Huxley’s books The Doors of Perception and Heaven and Hell, which described his experiences after taking the psychedelic drugs mescaline and later LSD. Although never tempted to try these myself, I found these books absolutely fascinating. The mystery, which Huxley described so beautifully, was how could minute amounts of these chemicals so totally alter your perception, your consciousness, and your view of the world, even to the extent of believing that you have had a visionary experience? I was looking for someone to teach me about brain biochemistry, but there was no one in the Cambridge Biochemistry Department who was doing anything like this. Fortunately, in the nick of time Gordon Whitby, a former member of the Department of Biochemistry in Cambridge returned to Cambridge after working in Julius Axelrod’s laboratory at the National Institutes of Health. He offered to supervise my Ph.D. on the catecholamine research that he had been involved in there.

Gordon had worked with Julie Axelrod at a very critical time. They had acquired tritium-labeled epinephrine and norepinephrine of high specific radioactivity, so for the first time it was possible to administer doses to animals that were in the normal physiological range. Julie had discovered a novel enzyme in catecholamine metabolism, catechol-O-methyl transferase and was particularly interested to see how much of an administered dose was disposed of by that route. Much to their surprise, although a significant proportion of the radiolabelled catecholamine did end up as O-methylated metabolites, a substantial proportion of the injected dose persisted in tissues unchanged (Whitby et al., 1961). Further experiments by Hertting and Axelrod (1961) showed that what was happening was an uptake of radiolabelled norepinephrine by sympathetic nerve endings, from which the amine could subsequently be released again by nerve stimulation. This revealed an entirely novel mechanism for inactivating neurotransmitters after their release by means of a reuptake mechanism. This was the key discovery for which Julie shared the Nobel Prize in Physiology and Medicine in 1970. Thus, by having Gordon Whitby as my supervisor I was one of the first people outside the Axelrod lab to get involved at a very early stage in what proved to be an exciting branch of neurochemistry and neuropharmacology, and to use the techniques that he had just learned in one of the world’s top laboratories.

I started out in 1961 by repeating some of the whole animal disposition studies in mice, comparing H3-epinephrine with H3-norepinephrine. We found that a higher proportion of labeled norepinephrine was retained unchanged (54%) than for labeled epinephrine (34%), suggesting that the tissue uptake process preferred norepinephrine as a substrate. We also found that as the injected dose of either catecholamine was increased less was retained unchanged, suggesting that the uptake process was saturable. These results were sufficient to gain me my first peer-reviewed paper (Iversen and Whitby, 1962). After that I switched to using the Langendorff isolated perfused rat heart preparation, which remained viable in vitro for several hours. H3-norepinephrine was rapidly accumulated from the perfusate by the sympathetic nerve endings in the heart—and this allowed control of the exact substrate concentration and time of exposure, and the study of potential uptake inhibitors. I was able to make detailed measurements of the kinetics of norepinephrine uptake; to show that it was stereospecific for the (-)enantiomer; to see how exogenous catecholamine equilibrated with the endogenous amine stores; and to investigate numerous inhibitors and to find out precisely how potent they were (Iversen, 1963). This latter exercise was facilitated by a change of supervisor which occurred at the end of my first year when Gordon Whitby left to take a Chair in Edinburgh, and I came under the wing of Arnold Burgen, the newly appointed Head of the Department of Pharmacology in Cambridge. Arnold was able to get free samples of most of the drugs we needed to test, and he taught me about the many different catecholamine analogs that exist among the sympathomimetic amines. This allowed us to explore the structure-activity relations of the norepinephrine uptake process in some detail (Burgen and Iversen, 1965). My most original finding was the unexpected discovery of a second uptake process in the heart, of low affinity and high capacity, that emerged at high substrate concentrations, and which I called “Uptake₂” (Iversen, 1965). Uptake₂ is not located on sympathetic nerves but is present in several peripheral tissues and in the brain. It is not dependent on Na+ or Cl–, has a low affinity for substrates and a high capacity. It is sensitive to inhibition by O-methylated catecholamine metabolites and by steroids. The Uptake₂ transporter has been cloned in animals, where it is termed “organic cation transporter 30” and in man where it is called “extraneuronal monoamine transporter.” This uptake system may represent a second line of defense that inactivates monoamines that have escaped neuronal uptake, and thus prevents uncontrolled spread of the signal.

Arnold Burgen was a wonderfully knowledgeable and supportive mentor, with an encyclopedic knowledge of science and the arts. At this time he was building the Department of Pharmacology in Cambridge—independent for the first time from Physiology. In time the Department became one of the strongest in Britain. My work moved ahead well, and data and publications accumulated fast. The drawback of the isolated heart work was that each data point involved the sacrifice of a rat; to complete the studies in my Ph.D. thesis several thousand were needed. Nowadays one could do all this in a few tissue culture dishes, and one would work with the human transporter protein, but rats were inexpensive in those days, and the modern techniques of molecular pharmacology were not yet available. Research funds were difficult to obtain in postwar austerity Britain. I had access to one of the only liquid scintillation counters in Cambridge to measure the radioactivity in my samples, but we could not afford to buy the many special glass vials needed to feed samples into this machine. Consequently many hours were spent carefully washing these for reuse!

I was able to submit a modified form of my Ph.D. thesis to Trinity College and was successful in gaining the award of a College Research Fellowship. Subsequently this dissertation was worked up to a monograph The Uptake and Storage of Noradrenaline in Sympathetic Nerves, published by Cambridge University Press in 1967, which gained some popularity among scientists working in the burgeoning catecholamine field.

Postdoctoral Work in the Axelrod Laboratory

At the end of our Ph.D. studies Sue and I again almost automatically assumed that we would be going to the United States to continue our research training. The “BTA” (Been To America) qualification was almost a sine qua non for young British scientists in the 1960s.

But arranging Fellowship support and finding suitable laboratories and supervisors in the same town was not so easy; however, we were fortunate once more. Sue gained a NATO Fellowship; and I was awarded a Harkness Fellowship. I was accepted to work in Julie Axelrod’s laboratory (having been introduced by Gordon Whitby), and Sue worked with a world leader in experimental psychology, Mort Mishkin (who knew Larry Weiskrantz well); both laboratories were at the National Institutes of Health. We traveled to the United States in September 1964 aboard the Queen Elizabeth.

Working in the Axelrod lab was a mind-blowing experience. The National Institutes of Health (NIH) was in period of expansion and unlike the austerity I had encountered in Cambridge, resources seemed almost unlimited. There was no question of washing the scintillation counter vials there!

Julie Axelrod was something of a “late starter.” He gained his Ph.D. late in life, having worked for many years as a laboratory technician for the famous pharmacologist Bernard Brodie. Julie did not have his own research group until he was in his forties. But he soon made up for lost time, and his research was enormously productive for almost another 50 years. He trained many young scientists from all over the world, many of whom went on to successful careers in neuroscience, but I was among the first generation of foreign visitors and postdocs in his lab. It was a great time. So many things remained to be discovered in the field of catecholamine research, following the availability of the radiolabelled amines and the discovery of the tissue reuptake mechanism. Jacques Glowinski, a French visitor, and I worked closely together, capitalizing on work that he had already started with Julie in the previous year. The project was based on the idea that one could study catecholamine metabolism and drug effects on the brain by labeling the catecholamine-containing neurons with radioactive amines. But the amines could not pass the blood–brain barrier, so they had to be injected directly into the brain. Jacques had devised a simple technique for injecting radiolabelled catecholamines into the ventricular system of rat brain and had already confirmed that tricyclic antidepressant drugs inhibited norepinephrine uptake in the brain as had been found previously in the periphery by Georg Hertting (Glowinski and Axelrod, 1964). This was a key new insight into how these drugs worked. Jacques and I did hundred of experiments together, and we were able to throw new light on the differing rates of turnover of catecholamines in various brain regions, their subcellular distribution, and the actions of various classes of central nervous system (CNS) drugs. Thousands of scintillation vials were stacked up outside the lab door each day, and we worked from morning to night. We published several papers from this hectic period of activity (e.g., Glowinski and Iversen, 1966), and we remain close friends. He went back to France and he developed a highly successful neuropharmacology laboratory at the Collège de France in Paris, where he brought modern neuropharmacological approaches and trained a whole generation of French neuroscientists

Julie gave us great encouragement, on the one hand he had more research ideas than we could possibly handle, but he also gave us an extraordinary degree of freedom. He was always interested in what we were doing. He had no office but had a small desk in a laboratory in which he would daily carry out his own experiments. The desk was immediately adjacent to the only balance in the lab, so everyone would have to use this at least once a day—and Julie could find out what they were up to! Julie also had a masterful technique for writing papers. We would all sit down at his desk and write the paper from start to finish—with his clear corrections and lucid explanations. The three of us would move our wheeled chairs together from one end of the room to the other—and the end result would be typed and ready for revision (there were no word processors in those days, so revisions had to be patiently retyped). We had no electronic calculators either, let alone computers, so data were analyzed by slide rule or by what we considered quite advanced mechanical calculator machines—which resembled large cash registers. The one piece of equipment that was really modern was the scintillation counter, and we would hang around watching the data come off this machine—often setting it to count each sample for only a short period of time, so that we could see if the experiment had worked. Julie was also an enthusiast for this “look-and-see” approach and would join us to watch the flashing red lights on the front of the machine.

The NIH was an enormously stimulating place to be doing research during this period. Part of the reason for this was that the best output from U.S. medical schools had decided quite reasonably that a couple of years of military service doing research at the NIH would be preferable to the alternative in the jungles of Vietnam. There was a rapid turnover of such extraordinarily bright people. The 1960s was an immensely optimistic period for biological psychiatry. We had the naïve belief that we would be able to understand the biochemical basis of mental illnesses and to treat them far more effectively. The 1960s saw the introduction in a very short space of time of the first really effective drugs to treat schizophrenia, depression, and anxiety. I suppose we all felt that progress like this would continue—and there would be more and more rational ways of approaching the development of drugs to treat psychiatric conditions. We didn’t realize that the discoveries of the 1960s were to represent the only major advances in drug treatment for the rest of the century. What happened later was far less spectacular.

During my stay at the NIH many other long-lasting friendships and contacts were made. Sol Snyder was beginning his research career in Julie’s lab, not working on catecholamines but on another of Julie’s favorite topics, the pineal gland and on histamine. But Sol and I became close friends and have remained so—I have followed his subsequent research in great detail and with much admiration. He is a person of extraordinary intellect and originality who knows when to jump into a field and when to move on, which is equally important. He says that he owes a great deal of that way of doing research to his mentor Julie Axelrod—who was a fountain of creativity and originality. Julie would say, “Don’t read the literature because it will only confuse you. You should just get on and do your own thing.” That has been very much Sol’s way—and he has been very successful not only in contributing to numerous topics in neuroscience, but also in training a whole group of people, many of whom have gone on to important senior positions in U.S. medical research.

There were other famous neuropharmacologists at the NIH while I was there, but we never got to visit people like Erminio Costa, Sidney Spector, or Sidney Udenfriend who worked in Bernard Brodie’s laboratory, even though they were in the same building as us. The Axelrod lab was not on speaking terms with the Brodie lab—perhaps because Brodie resented the fact that his former pupil Julie Axelrod had become so spectacularly successful. I don’t know the details, but we only ever saw these people at seminars. Costa would have stand-up arguments with Jacques Glowinski at conferences about their different interpretation of measurements of CNS catecholamine metabolism. Both Jacques and Mimo sometimes let their Latin temperaments get the better of them—which made for entertaining spectator sport! But I got to know Mimo Costa quite well later and admired him as an intelligent, inventive, and ingenious person who contributed much to modern neurochemistry and pharmacology. In his 1970s he lost his job with the Fidia Research Laboratory in Georgetown, Washington, D.C., because the company went bankrupt. But he got himself a new job and a new career in Chicago. You have to admire someone who can keep going like that, wanting to research and having good ideas.

Postdoctoral Work in Steve Kuffler’s Department at Harvard

After the hectic period in Julie’s lab it was a relief to take a break before moving on to a second postdoc at Harvard. My Fellowship from the Harkness Foundation was intended to foster Anglo-American relations, and as part of this the Fellows were required to travel for several weeks each year to get to know the United States. I was provided with a large Chevrolet and told to head West. Sue and I spent a memorable 6 weeks during the summer of 1965 crossing the country from Washington, D.C., to the West Coast and back—and visiting a variety of academic labs en route—a fantastic experience. We Europeans had no idea just how big a country the United States was until we had driven 700 miles in one day along a dead straight road in Kansas!

In September 1965 we arrived in Boston. Again Sue and I had been fortunate to arrange excellent positions for a second period of postdoctoral research. Sue joined the group of Peter Dews at Harvard and learned new skills in behavioral pharmacology, and I went to the newly formed Department of Neurobiology at Harvard Medical School. This was headed by the brilliant neuroscientist Steve Kuffler—to whom my mentor Arnold Burgen had introduced me. I was supervised by Ed Kravitz, a biochemist who had joined Steve Kuffler’s group from the NIH, where he had been a contemporary of Roy Vagelos—who later became head of Merck & Co., Inc., where I was subsequently to work. I was to be Ed’s first postdoc, and we got on very well together—he taught me a great deal.

To be in Steve Kuffler’s lab for a year was a great privilege and a joy. At Harvard I met a group of quite different scientists. They were much more interested in neurobiology, physiology, and cell biology and less biochemistry or pharmacology oriented than the Axelrod group. They also favored the use of invertebrate organisms with their simpler nervous systems—so I worked on lobsters instead of rats. I joined the “GABA project” which had already been under way for some years by a team that included Steve Kuffler, David Potter, and Ed Kravitz. We worked on the inhibitory motor nerves of the lobster. Unlike mammals, where inhibition goes on only in the CNS, lobster muscles receive a dual innervation by inhibitory and excitatory motor nerves. A meticulous comparison of the neurophysiological actions of γ-aminobutyric acid (GABA) on lobster muscle with the inhibitory synaptic potentials elicited by stimulating inhibitor motor nerves had convinced Steve that GABA was most likely the neurotransmitter released at such synapses. But proof of this was lacking. By careful dissection of inhibitory versus excitatory nerves and sensitive biochemical assays the team had established that GABA was indeed present at high concentrations in the inhibitory fibers, but not at all in the excitatory ones. Ed and I set out, with the collaboration of a Japanese visitor Masanori Otsuka, and occasional help from a graduate student Zach Hall, to demonstrate that GABA was selectively released when inhibitory nerves were stimulated. Ed devised an ingenious preparation of the large crusher claw of the lobster in which most of the shell was removed to leave a single large muscle exposed together with its inhibitory and excitatory nerves. The preparation was constantly superfused with sea water, and the efflux collected at timed interval. I helped to devise a method for isolating the tiny amounts of GABA that were released and assaying them—not easy as we were trying to isolate amounts of GABA in the subnanomole range from 40 to 50 milliliters of seawater! Masanori would set up the stimulating electrodes to separately stimulate inhibitory or excitatory nerves and would check that they were working correctly by recording synaptic potentials in muscle fibers after impaling these with a microelectrode. After the many technical difficulties had finally been overcome—and with only a few weeks of my stay remaining—we were able to carry out some successful experiments, showing the selective release of GABA when inhibitory but not excitatory nerves were stimulated, and showing furthermore that the amounts released were dependent on the stimulation frequency and required the presence of calcium. We were thus able to provide what we felt was the final piece of evidence that GABA was the inhibitory motor neurotransmitter. Ed Kravitz and Zach Hall had to finish the experiments after Masanori and I had left to return home—but by that time we all knew that it was in the bag! We published a paper describing our results in Proceedings of the National Academy of Sciences USA (Otsuka et a1., 1966), and we awaited the acclaim that we all felt to be our due—after all this was only the third neurotransmitter whose identity had been proved! But initially far from acclaim our results were met with skepticism and derision. Ed gave a paper at the U.S. Federation Meetings in the spring of 1966 and was met by hostile questioning from an audience not yet ready to admit that GABA had any function in the nervous system other than as a metabolite. At a meeting of the Physiological Society in England in the autumn of 1966 I experienced a similarly skeptical reaction, and I was only rescued from the hostile questioning by the intervention of the Chairman of the session, Bernard Katz (who was later to share the 1976 Nobel Prize with Julie Axelrod). He reminded the audience that it was customary for members to be more courteous to a young member who was giving his first paper to the Society! Acclaim or no acclaim we were all very proud to have been involved in the final stages of Steve Kuffler’s “GABA Project”—and in due course GABA became to be recognized as one of the most widely used inhibitory neurotransmitters in invertebrates and vertebrates.

Steve Kuffler was an extraordinary genius and a man of great charm and modesty. He had the knack of choosing the right people and finding the right sort of preparation to solve particular problems in neurobiology. While I was there he was working on electrophysiological recordings from the large glial cells found in the optic nerve of the mud puppy. This work showed that far from being nonfunctional, glial cells exhibited electrical potential changes as the surrounding nerve fibers were activated. At the same time in another part of the lab Hubel and Wiesel were carrying out their ground-breaking work on the visual cortex, showing that there were individual neurons that recognized the direction and orientation of visual stimuli, work that had originated from Kuffler’s earlier research on ON and OFF fields in the retina. This was a great introduction for me to the wider world of neuroscience, in one of the first academic departments anywhere in the world devoted solely to this field.

Return to Cambridge

I returned to the Department of Pharmacology in Cambridge—where Arnold Burgen continued to offer me every support. I was personally supported by my Trinity College Fellowship and later by a named research fellowship from the Royal Society, the Locke Fellowship. This meant that I was not a member of the teaching faculty and could spend all my time on research, apart from some College tutorial work in the evenings at Trinity. Initially I shared a laboratory with a lecturer in the department, Brian Callingham who was extraordinarily tolerant of the increasing number of graduate students and postdoctoral visitors that I continued to squeeze in to the limited space. My first graduate students, Bevyn Jarrott from Australia and Patrick Salt joined, and were followed soon by another Australian graduate student Ian Hendry and my first postdocs, Norman Uretsky from Chicago, Mike Simmonds from London, and Ira Black, who had just completed a period in Julie Axelrod’s lab.

During the next 4 years research ranged widely as I gradually developed my own research group. Research topics included the inhibition of Uptake₂ by steroids (P. Salt); distinctions between monoamine oxidase A and B (B. Jarrott); effects of ambient temperature on catecholamine turnover in brain (M. Simmonds); nerve growth factor (I. Hendry); and synaptic plasticity (I. Black). I was also able to maintain an interest in GABA by collaborating with another faculty member, Mike Neal. We were the first to show the presence of a high affinity saturable uptake of GABA by rat brain slice preparations in vitro (Iversen and Neal, 1968). Forty years on, we now know that there are no fewer than four different high affinity GABA transporters in brain. In similar experiments with Graham Johnston, a visitor from David Curtis’ lab in Australia, we showed that a high affinity uptake of glycine could also be demonstrated in spinal cord in vitro (Johnston and Iversen, 1971). My interest in GABA continued with collaboration with James Mitchell, a senior faculty member, who had devised a cortical cup technique that allowed the collection of samples from the cat visual cortex, while applying various stimuli. Using the sensitive GABA assay technique that I had developed for the lobster studies, we were able to show that there was an increase in GABA release from mammalian cortex associated with inhibitory activity.

Having demonstrated that a high affinity uptake of GABA was present in mammalian central nervous system (CNS) the question remained of how to show whether or not this was localized on GABAergic nerve endings as a reuptake mechanism, equivalent to the norepinephrine uptake system in sympathetic nerves. One way would be to use radiolabelled GABA and then to attempt to localize this in tissue sections by autoradiography. But at the light microscope level this would not have sufficient spatial resolution to give an unequivocal answer about the cellular location of the uptake sites. This could only be done at the electron microscope level. So I ambitiously sought to obtain funds to purchase an electron microscope for the Department and to hire an experienced technical assistant. With help from Arnold Burgen this was successfully accomplished in 1969, and I set out to teach myself how to use the microscope and how to go about getting ready to do some autoradiography. I would never have achieved this without a lot of help from my friend Floyd Bloom, who was an expert in this methodology. Floyd had not worked at the NIH campus in Maryland, where Julie’s lab was, but he was in another NIH-supported research group at St. Elizabeth’s Hospital in downtown Washington, D.C. He had developed a very successful research career combining expertise in neurophysiology and neuroanatomy to studies of neurotransmitters, and I had got to know him and visited his lab several times. We became good friends, and remain so. Floyd offered detailed advice about what was needed to set up light and electron microscopic autoradiography and even offered to come over himself to help me get started. He came to Cambridge in the summer of 1970, and although he stayed for only just over 6 weeks we accomplished an amazing amount, largely because of careful planning beforehand. With the electron microscope method we were able to study in detail the cellular location of H³-GABA that had been accumulated by slices of rat cerebral cortex. Floyd taught me how to apply quantitative morphometric methods to this analysis, and although the preservation of tissue structure in such small tissue slices was poor, we were able to conclude that the majority of the H³-GABA had accumulated in synaptic nerve endings, and furthermore showed that only a subpopulation of nerve terminals was labeled. We were able to publish our results quite rapidly (Bloom and Iversen, 1971)—and this was just as well because Tomas Hökfelt in Sweden was also publishing similar studies of the autoradiographic localization of H³-GABA uptake sites. Tomas and I are contemporaries and have had a friendly competition on a number of topics over the years.

The autoradiographic studies with H³-GABA were later extended to examine the localization of H³-glycine that was again found to be localized to nerve terminals. In homogenates of spinal cord it was possible to show that each amino acid labeled a separate population of synaptic terminals, amounting to approximately 25% of the total in each case. But autoradiographic studies of H³-GABA uptake in retina done with Mike Neal produced a surprising result. Instead of labeling a population of inhibitory interneurons as we had expected, the radiolabelled GABA was prominently accumulated by a particular population of large retinal glial cells, the Müller Cells (Neal and Iversen, 1972). A study of H³-GABA uptake in slices of rat cerebellum conducted with a graduate student Fred Schon also showed a prominent glial localization (Schon and Iversen, 1972). In retrospect this is no longer surprising, as we know that GABA transporters are located on neuronal and glial sites in mammalian CNS, but at the time we were puzzled. The failure to observe glial uptake sites for GABA in our previous experiments using small brain slices or homogenates was probably due to the poor preservation of glial cells in such preparations.

In the catecholamine arena Norman Uretsky and I were among the first to show that the selective neurotoxin 6-hydroxydopamine worked on adrenergic neurons in CNS in the same way that Hans Thoenen had demonstrated for sympathetic nerves in the periphery (Uretsky and Iversen, 1970). When administered into the brain this chemically reactive catecholamine analog is selectively taken up into catecholamine neurons (noradrenergic and dopaminergic) and subsequently kills them. 6-Hydroxydopamine has since become widely used as a tool for studying the functions of CNS adrenergic neurons by using local microinjections of the toxin to create selective lesions of particular pathways. Such methods were adopted by Sue and the students in her laboratory and yielded many important advances in understanding the role of the various dopaminergic and noradrenergic circuits involved in the behavioral responses to drugs, particularly the amphetamines. There was a frequent interchange of students and postdocs between our laboratories. Sue and I also worked together to write a much-needed student textbook Behavioral Pharmacology, published by Oxford University Press in 1981.

Particularly exciting for me was the work that was done in collaboration with Ira Black and Ian Hendry and a graduate student Angus Mackay on the role of nerve growth factor, and the way in which nerve activity affected the expression of key enzymes in adrenergic neurons. We found that the level of the biosynthetic enzyme tyrosine hydroxylase in sympathetic ganglion cells or in the adrenal medulla was elevated by sustained increases in the activity of presynaptic fibers, and decreased if these fibers were lesioned (Black et al., 1971). These were among the first models available for studying how neuronal activity affects gene expression. Ian Hendry showed that the effects of increased nerve activity could be mimicked by administration of nerve growth factor (NGF)—and went on to propose that NGF might act as a retrograde signal picked up by sympathetic nerve endings and transported back to the cell bodies (Hendry and Iversen, 1973). When Ian completed his Ph.D. and left to join Hans Thoenen’s lab in Switzerland we continued to collaborate for a while, and I was able to provide the first direct autoradiographic evidence for the retrograde transport of radiolabelled NGF that he had posulated (Hendry et al., 1974). The concept of NGF as a retrograde cell signaling mechanisms is by now widely accepted.

MRC Neurochemical Pharmacology Unit (1970–1983)

In 1970 my research career received another boost. During the previous year I had applied to the Medical Research Council (MRC) (the main government funding agency for biomedical research in Britain) for the Directorship of the MRC Neurochemistry Unit at Carshalton in Surrey, a vacancy created by the retirement of its founding Director Derek Richter. I was short-listed for this post but in the end was not appointed. However, as a consolation prize the MRC offered something even better—my own small Unit in Cambridge! So the MRC Neurochemical Pharmacology Unit was formed, and I spent the next 12 years very happily as its Director. In those days the MRC gave Unit Directors a very free hand in determining their research programs, and although the resources available to the MRC were not as great as those of the NIH we did not complain about any lack of equipment or staff positions. The Unit’s core budget was entirely funded by MRC, so I no longer had to write grant applications. The Director had to submit a written report for review every 3 years, and the Unit had a site visit once every 6 years—this was not a very onerous regime! Although we were always short of space, the Unit—colloquially known as “Nick Pooh”—was very productive and attracted a wonderfully talented cohort of students, postdocs, and overseas visitors. At that time it was relatively easy for Americans to obtain Fellowship support for a period of research training overseas, and we benefited greatly from this. “Nick Pooh” was always a very warm and friendly lab—we were never more than about 30 people, and often had parties (usually hosted by Sue at home) or picnics together.

As the Unit became established several research projects developed. John Kelly had joined the Unit from Kres Krnjevik’s laboratory at McGill University. John brought the latest neurophysiological techniques to the Unit, including intracellular single cell patch-clamp recordings; multibarreled iontophoretic microelectrodes; and computer analysis of data. The Unit purchased the latest PDP8 lab computer, its flashing red lights and apparent miles of cabling always impressed visitors! John developed his own group of staff and visitors, focused mainly on amino acid neurotransmitter pharmacology.

My own interests stayed initially with the catecholamines, but later became increasingly focused on the neuropeptides.

In the catecholamine field I was particularly struck by a lecture that Sol Snyder gave at a Summer School in Boulder, Colorado, sponsored by the Neuroscience Research Program (NRP). This was a so-called invisible university of the brain based at MIT, founded by the charismatic polymath Frank Schmitt. I was fortunate to be among the small group of Associates of the NRP for almost 10 years (1975–1984) and attended its meetings in Boston three to four times a year—it gave me an invaluable continuing contact with leaders of neuroscience in the United States, and I benefited greatly from my membership. In 1972, prior to becoming an Associate, I was invited to lecture at the Summer School. Sol Snyder gave a lecture on the “dopamine hypothesis” of schizophrenia, putting together the gathering evidence for what was then a very new concept. I had not appreciated how strong this evidence was, and I became convinced that this was a field that the Unit in Cambridge should get involved in. Fortunately at that time an outstanding new graduate student Richard Miller joined me, straight from a Biochemistry degree in Bristol University. A recently published paper by John Kebabian and Paul Greengard had described a dopamine-sensitive adenylate cyclase in rat pituitary gland, which seemed to offer for the first time a biochemical test tube model for dopamine receptors. Richard soon found that a similar dopaminesensitive adenylate cyclase could be demonstrated in the dopamine-rich basal ganglia of rat brain, and he rapidly established this as a model system for studying drug actions on brain dopamine receptors. In particular we were excited to be able to test a key tenet of the “dopamine hypothesis,” namely that the drugs used to treat schizophrenia all acted as dopamine receptor antagonists (Miller et al., 1974). At first our results seemed to support this hypothesis. Among the phenothiazines and thioxanthenes there was a close correspondence between the antagonist affinities of the drugs against the adenylate cyclase and their known behavioral or clinical potencies. But anomalies soon emerged—whole classes of potent antipsychotic drugs—the butryophenones and substituted benzamides were virtually inactive as antagonists in the adenylate cyclase model. Meanwhile Kebabian and Greengard were coming to the same conclusions, having also studied a dopamine-stimulated adenylate cyclase in rat brain (Clement-Cormier et al., 1974). It was not until Phil Seeman and Sol Snyder independently discovered a second dopamine receptor in brain by measuring the binding of a radiolabelled tracer that the true target of the antipsychotic drugs was found—now called the dopamine D₂ receptor (Creese et al., 1976; Seeman et al.,1975). What we had been studying is now known as the dopamine D₁ receptor, and molecular cloning studies later revealed a further three dopamine receptors exist in mammalian brain. But of course we did not know any of this at the time.

Another way of testing the “dopamine hypothesis” of schizophrenia was to see if abnormalities could be detected in the dopamine systems in the brains of schizophrenic patients postmortem. In the Unit we had started to collect postmortem human brain tissue because of the enthusiasm of an U.S. visitor, Ted Bird, who had the idea of looking for neurochemical abnormalities in the brains of patients dying with Huntington’s disease. Although I was initially skeptical of the value of biochemical measurements in postmortem human tissue, Ted went ahead anyway, and it soon became apparent that a number of neurotransmitters and associated biochemical markers were remarkably stable in postmortem human brain—so that valid measurements could be made. In Huntington’s disease Ted showed that were gross deficiencies in the inhibitory transmitter GABA in basal ganglia, which we thought might be associated with the uncontrolled movements that such patients suffer (Bird and Iversen, 1974). It was an obvious next step for us to start collecting postmortem brain tissue from patients dying with a diagnosis of schizophrenia, and Ted Bird and Angus Mackay, who planned a career in psychiatry, soon got this started. What proved more difficult, however, was the interpretation of the biochemical data. Although like others we did find elevated levels of brain dopamine, and increased densities of dopamine receptor binding sites in schizophrenic brain it was not clear if these were really associated with the illness, or merely the result of chronic treatment with dopamine-blocking antipsychotic drugs, which were known to elicit such changes in the brains of experimental animals. In the small number of patients in our collection who had not been treated with antipsychotic drugs no abnormalities in dopamine or dopamine receptors were seen, but the sample was very small (Mackay et al., 1980). We concluded that this approach would not yield any unequivocal answers, although others disagreed. Other labs have continued to search for dopamine excess in schizophrenia in recent years, using ever more sophisticated brain imaging tools to examine dopamine systems in the living brain. The latest imaging findings do suggest that dopamine hyperactivity does occur in the brains of patients who are in the florid stages of psychosis.

Later, in the 1980s, the work on human postmortem brain was extended to Alzheimer’s disease. This project was led by Martin Rossor, a trainee in Neurology who was taking time out to do research. We carried out an extensive series of studies on neurotransmitters and neuropeptides, confirming in detail the cholinergic lesion and observing differences in the pattern of cholinergic damage in young versus old Alzheimer’s disease patients (Rossor et al., 1981). During a brief visit to Floyd Bloom’s lab at the Salk Institute I was able to confirm that in addition to the cholinergic damage Alzheimer’s disease there is a profound loss of noradrenergic cells from locus coeruleus (Iversen et al., 1983) A useful off-shoot of our activities on human postmortem brain was that we were able to establish the MRC Brain Tissue Bank as a resource in Cambridge and supplied samples of frozen tissue for biochemical analysis to researchers in many different laboratories around the world. This was one of the first “brain banks” to be established in the United Kingdom, and it still continues to operate today—although the restrictions and regulations surrounding work on human tissues are now far more onerous than they were 30 years ago.

In the 1970s I became fascinated by the rapidly growing field of neuropeptide research, which had been boosted by the discovery of the first of the endogenous opioid peptides, the enkephalins by John Hughes and Hans Kosterlitz in Aberdeen. Hans Kosterlitz was a remarkable example, like Julie Axelrod, of someone whose best research was done after he reached the normal retirement age! He had to retire from his post as Head of the Department of Pharmacology at the University of Aberdeen but was able to continue his research on opiate pharmacology there through support from the National Institute on Drug Abuse in the United States. After the discovery of the opiate receptor by Sol Snyder and Candice Pert it became obvious that naturally occurring ligands for these receptors must exist in brain, and the search began in several different laboratories. I attended a meeting of the Neuroscience Research Program devoted entirely to this topic in May 1974, and there was considerable sparring between the rival camps—notably Sol Snyder, Lars Terenius, and John Hughes, all of whom were close to discovering the enkephalins. John Hughes came to Cambridge shortly after to give a seminar, and I invited Howard Morris, an expert in the mass spectrometry of peptides and proteins. At the end of the seminar Morris challenged John by saying that if he could have a few milligrams of the peptide that John has isolated, the structure could be worked out quickly. John did not initially take up this challenge, although some time later he did, and Morris helped to solve the conundrum that Hughes had struggled with—he had isolated not one peptide but two closely related substances, Leuand Met-enkephalin.

My entry to this field came with another neuropeptide, substance P (SP). Although discovered in 1936 by Ulf von Euler and John Gaddum, the structure of this undecapeptide was only revealed for the first time by Susan Leeman in 1970, but the peptide was not commercially available for some time thereafter. Shortly after the establishment of the MRC Unit, however, I was fortunate to receive a generous gift of 25 mg of the synthetic peptide from Ralph Hirschman a peptide chemist working at Merck Research Laboratories.

Research Laboratories in the United States (someone I would come to know very well when I later joined this company). Although this was a small amount of peptide, it was more than enough to sustain our SP research program for many years to come. We were able to use some the peptide to prepare antibodies that were used to develop sensitive immunoassays or for immunohistochemical mapping studies. Claudio Cuello, an Argentinean visitor who was very well trained in neuroanatomy, prepared a complete map of the SP-containing neurons in rat brain and spinal cord (Cuello and Kanazawa, 1978)—competing directly again with Tomas Hökfelt and his team at the Karolinska Institute in Sweden.

Tom Jessell, a new graduate student, used a radioimmunoassay to demonstrate the calcium-dependent release of SP from superfused brain slices in vitro on depolarization. Although there were many SP-containing neuronal pathways within the brain, we were particularly interested in the presence of SP in a class of primary sensory neurons, where it was thought to be involved in the transmission of pain information into CNS. My former colleague from Harvard Masanori Otsuka had carried out a meticulous series of neurophysiological studies suggesting the possible role of SP in these nerves as a sensory neurotransmitter. Tom Jessell was able to establish an in vitro preparation of rat brainstem slices in which SP release from primary sensory nerve endings could be demonstrated. Most importantly he went on to show that morphine could suppress the stimulus-evoked release of SP—suggesting a novel way in which opiate analgesics might act as inhibitory modulators at the first sensory relay carrying pain information into CNS (Jessell and Iversen, 1977).

Another graduate student, Chi Ming Lee from Hong Kong, studied the pharmacological actions of peptides related to SP on a variety of in vitro smooth muscle preparation and provided evidence for the existence of multiple receptors—one category preferring SP itself, another preferred the related naturally occurring peptides eledoisin or kassinin (Lee et al., 1982). This work was carried forward further by Steve Watson later. We also provided evidence for the existence of a second SP-related peptide in mammalian CNS, which we called “neuropeptide K.” These findings proved to be the forerunner of our present understanding that there are three naturally occurring peptides in the SP family: SP and neurokinins A and B, and they are recognized by three related receptors: NK1, NK2, and NK3. We were also interested in understanding how SP was enzymically degraded, with the idea that inhibitors of such enzymes might provide a way of pharmacologically enhancing SP actions in vivo. Together with Bengt Sandberg, a Swedish chemist visiting the lab, and Michael Hanley a postdoc we made some progress in purifying a SP-degrading enzyme and devised and synthesized metabolically stable synthetic analogs of SP (Sandberg et al., 1981). But because of their broad specificity peptidases have not so far proved useful drug discovery targets for this or other neuropeptides.

My interest in SP continued after I joined the pharmaceutical industry, but meanwhile a summer visit to Floyd Bloom’s laboratory at the Salk Institute in California and a collaboration with Wylie Vale (a former colleague of Roger Guillemin) allowed the demonstration for the first time of the calcium-dependent, stimulus-evoked release of enkephalins (Iversen et al., 1978b) and somatostatin (Iversen et al., 1978a) from mammalian brain slices in vitro. During a subsequent summer visit to Salk, I showed that in the posterior pituitary, as in primary sensory nerves, opiates acted presynaptically to suppress the stimulus-evoked release of vasopressin. In Cambridge, Piers Emson, a staff member of NCPU, carried out extensive studies of the neuropeptide vasoactive intestinal polypeptide (VIP) and neurotensin in rat brain, and studied these also in human postmortem brain.

Not all aspects of my plans for NCPU succeeded. My biggest disappointment was the failure to establish a clinical research presence in Cambridge. Angus Mackay, now a fully qualified psychiatrist and a talented scientist, rejoined the Unit, and we had plans to start a small clinical research effort in schizophrenia. But despite every encouragement from the newly appointed Professor of Psychiatry Martin Roth and positive support from MRC this proved impossible. Angus eventually left to become a very successful director of one of the largest psychiatric hospitals in Scotland. The problem was that British psychiatry during the 1970s and 1980s was very much oriented to the fashionable concepts of group therapy and counseling—and if not antagonistic toward biological research, psychiatrists were largely indifferent to it. The local psychiatric hospital in Cambridge was no exception. Even the new Professor of Psychiatry found it difficult to establish a clinical research presence there, and we had no chance.

Being Director of NCPU (1970–1983) was one of the most satisfying jobs I ever had. Election to the Fellowship of the Royal Society of London toward the end of this period came as an unexpected surprise and privilege and helped to round out this phase of my career. The MRC gave me every support and freedom, and we attracted a group of very talented people to work in the lab—many of whom have gone on to highly successful research careers and to senior academic positions. It is hard to imagine a better environment in which to do productive research—but being a restless person I decided to move on.

Merck Research Laboratories (1983–1995)

In 1981 I was visited in Cambridge by two senior research directors from the U.S. pharmaceutical company Merck, Clem Stone and Paul Anderson. They told me of an ambitious plan that the company had to establish a large new research laboratory in England, which would become the focus of Merck’s drug discovery research in the neuroscience field. Merck had been through a very successful period and wanted its research to become more global in coverage, to reflect the international status of the company; during the next decade new laboratories would be opened in France, Italy, and Japan in addition to the one in England. Another factor in England was that because of the National Health Service the U.K. government was the sole purchaser of Merck’s prescription medicines. As such the government could control the prices that Merck was allowed to charge. If the company established research or manufacturing facilities in Britain, however, they could gain some concessions in such price negotiations. Merck did both—establishing the Neuroscience Research Centre in Harlow, Essex, and a large new manufacturing plant in Newcastle.

What Clem Stone and Paul Anderson wanted to know was whether I would be willing to act as a consultant to Merck and offer advice on this big new project. They were unfamiliar with the neuroscience research scene in Britain or the rest of Europe. In particular they wanted advice on who they might appoint as the Director of the new laboratory. I found the project ambitious and exciting, although at first the idea that I might personally become the Director of this new venture hardly crossed my mind.

At that time the MRC, which had hitherto not encouraged its research staff to have much to do with industry had announced new rules that permitted their scientific staff to act as consultants to industry. Thinking that this would allow me to work as a consultant to Merck I asked MRC Head Office to confirm that this was permissible. To my dismay the answer was no; consultancies would only be permitted if the company in question was British—thus ruling out formal approval for me to work for Merck. I found this patently absurd because the new Merck research laboratory would offer a considerable boost to research in Britain. So I decided to ignore the MRC ruling and went ahead informally as Merck’s consultant anyway. As I did so I got to know and respect the Merck people involved, and as I learned more about the details of their plans I became more and more enthusiastic about what the project had to offer. Eventually in 1982 I accepted Merck’s offer to become the Director of the Neuroscience Research Centre and joined the company in temporary lab facilities at their commercial headquarters in Hoddesdon, Herts, in October 1983—after a rather uncomfortable year in Cambridge trying to ensure a soft landing for NCPU—which eventually happened with the appointment of the very talented Eric Barnard as my successor.

Some of my former academic colleagues were shocked to see me move into the world of commerce, or “trade” as some snidely called it, but most expressed admiration, and my move was soon followed by other academics who left their ivory towers to join industry—as other companies followed Merck’s lead and established neuroscience research laboratories in the United Kingdom. John Hughes went to direct the Parke Davis laboratory in Cambridge, Humphrey Rang to the Novartis Institute at University College, London, and Richard Green to Astra Zeneca.

The appointment at Merck was an opportunity of a lifetime. I had the freedom to recruit an entirely new scientific team (the existing members of Merck’s small CNS group in the United States declined the offer to move to England), to plan a whole new program of drug discovery research, and to be involved in the development of a wonderful modern research centre on a green-field site. The site was in 30 acres of parkland near Hoddesdon, which had formerly been the grounds of a country house, known as Terlings Park. My first priority was to recruit some senior staff members. Sue was to join the lab as Director of Behavioral Pharmacology, and initially we appointed Geoff Woodruff, an academic pharmacologist from the University of Southampton as overall Head of Pharmacology. Biochemistry was under the direction of Ian Ragan, another ex-Southampton academic; and with help from Merck chemists we appointed Ray Baker, also from Southampton, to be head of the Medicinal Chemistry group; Bill Raab who had overseen the development of the laboratory stayed on as a very professional administrator. We were to be completely self-sufficient, with our own large chemistry group equipped with all the analytical equipment and computer modeling facilities that they needed. Fortunately for us, research and development (R&D) efforts other pharmaceutical companies in Britain were not in a particularly expansionist mode at the time, so we were able to recruit numbers of very well qualified scientists. The Neuroscience Research Centre built up over the years to total of more than 300 people working on-site.

We quickly established a number of major research projects. One of the first aimed to discover a muscarinic agonist drug to treat the cholinergic deficiency in Alzheimer’s disease. Despite heroic efforts this proved a very difficult objective. Although our chemists synthesized some novel and highly potent agonists (Freeman et al., 1990) we did not have the molecular pharmacology tools in 1983 to study the selectivity of drugs on human muscarinic receptors, and finding compounds that were selective for the target—the M1 receptor—that were safe to use eventually proved too difficult. It was not a goal that anyone else was able to achieve either. Despite decades of research by many major pharmaceutical companies the muscarinic agonist approach has still not reached fruition.

Another way of enhancing cholinergic synaptic function is to use inhibitors of the acetylcholine inactivating enzyme acetylcholinesterase, and this led eventually to the compounds now available for the symptomatic treatment of Alzheimer’s dementia. In the late 1980s we adopted this approach by licensing an analog of physostigmine from the Italian company Mediolanum. Physostigmine had already been show to have beneficial actions in treating the cognitive deficits in Alzheimer’s patients—but it suffered from a very short half-life in humans and was not a practical therapy. The simple analog heptylphysostigmine was far longer lasting, at least in animals (and we subsequently found in humans). In animal behavioral studies it showed considerable promise in reversing cholinergic deficits, and we quickly took this compound forward into development at Merck’s facilities in the United States. The compound seemed to be safe and well tolerated in human volunteer studies, and it was possible to achieve a significant degree of inhibition of the cholinesterase (as measured in red cells). But when the compound entered Phase II clinical trial in Alzheimer’s patients, there were a couple of instances of white cell abnormalities in patients, and Merck considered these to be sufficiently serious to abandon any further work with the compound. Mediolanum continued the clinical development of heptylphysostigmine for a few more years, but they too eventually had to give up. This was very sad, as Merck could have been one of the first to offer an acetylcholinesterase inhibitor for the treatment of Alzheimer’s disease—compounds from other companies have since become the front-line medicines for this indication. I soon learned that no matter how smart you think you are, only about one development compound in every 10 ever makes it successfully through all stages of development to the marketplace. This was true for the Neuroscience Research Centre just as it was elsewhere in pharmaceutical R&D.

We developed a strong interest in excitatory amino acid pharmacology early on. The Merck CNS group in the United States a few years earlier had discovered that the compound MK-801(dizocilpine) possessed powerful anticonvulsant activity in animal models and had considered developing it as an antiepileptic. I was asked to see whether we could work out its mechanism of action, which was unknown. The approach we adopted was to prepare radiolabelled MK-801 and to see if we could identify specific binding sites for it in rat brain membranes. Eric Wong succeeded in doing this and tested a range of neurotransmitters, peptides, and drugs on these binding sites to see if they corresponded to any known receptor in brain. Almost nothing competed with MK-801 for binding, except for a few psychotomimetic drugs—notably ketamine and phencyclidine. This was not much help because no one knew how these compounds worked. But just before then the neuropharmacologist David Lodge had reported that ketamine and phencyclidine acted in vivo as antagonists at the glutamate receptor subtype known as the N-methyl-D-aspartate (NMDA) receptor. This gave us the clue that we needed, and John Kemp and colleagues in the neurophysiology lab were soon able to show that MK-801 was a potent noncompetitive antagonist at the NMDA receptor (Wong et al., 1986). This was an important discovery; MK-801 was already known to be an orally acting long-lasting compound, so if we could identify a clinical use for it the compound could rapidly become a development candidate.

One obvious idea was to see if MK-801 could protect neurons against excitotoxic damage and death that resulted from exposure to an excess of L-glutamate. As a corollary, could MK-801 protect neurons against damage in animal models of stroke—because cerebral ischemia was thought to cause damage in part because it released an uncontrolled flood of L-glutamate from excitatory nerve endings? We soon obtained positive results in a variety of animal models that were run in-house. Positive results were also obtained in what was then regarded as the “gold standard” rat model of stroke, which involved the surgical occlusion of the middle cerebral artery in brain—one which is commonly affected in human stroke cases. Such studies required great surgical skill and were beyond our competence, but we were fortunate in collaborating with Jim McCulloch in Glasgow, who was an expert in this field. He showed that MK-801 treatment was able to reduce the cerebral infract size by as much as two thirds, and there appeared to be at least some time window available in which the drug remained effective even when given after the ischemic insult. We were keen to see MK-801 advanced to a “proof of concept” clinical trial in stroke, but there many hurdles to overcome. Clinical trials in human volunteers showed that small doses of the drug appeared to be safe and well tolerated, but at slightly higher doses it had adverse effects on blood pressure, and subjects reported subjective feelings of “dissociation”; feeling, for example, that their limbs were no longer part of the rest of their body. Although these were not frank hallucinations the worry remained that the drug might prove to be psychotomimetic—as ketamine and phencyclidine were known to be. A further complication arose in 1989 when James Olney, a respected figure in glutamate pharmacology and father of the concept of glutamate as an “excitotoxin,” published a paper describing what appeared to be brain damage in rats treated with moderate doses of MK-801. Neurons in circumscribed regions of cerebral cortex developed large vacuoles and looked sick (Olney et al., 1989). We immediately attempted to repeat these findings, and although we did observe numerous vacuolated neurons after treatment with MK-801, these changes were almost completely reversible with time. Olney’s findings were taken very seriously, and in the United States the regulatory agency Food and Drug Administration (FDA) convened a special meeting to discuss the development of MK-801 and other NMDA antagonists in light of these data. I was summoned as a witness—my only experience of being questioned by an FDA panel. Although we argued that the neuronal vacuolation was essentially a reversible phenomenon, Dr. Paul Leber, Head of the Neuropharmacology Division of FDA, and well known as a hard-liner, continued to refer to the “brain lesion” caused by the drug. This culminated in a series of exacting requirements by FDA for further animal studies, including experiments in primates, before MK-801 could be allowed to enter clinical development. Given these demands, and the worries about whether the drug might prove to be psychotomimetic, Merck senior management decided to abandon further development of the drug in 1990. Although we were disappointed at the time, in retrospect this was not such a bad decision. Other companies fulfilled the FDA requirements and brought NMDA antagonists into clinical trials but found them to be potent psychotomimetic agents; none of these compounds survived to adequate “proof of concept” trials in stroke, and subsequent trials of many other pharmacological approaches to the treatment of stroke have all ended in failure. Despite showing promise in animal models a number of compounds failed to show significant clinical benefits. It seems that stroke is a far more variable condition, with varying outcomes, that cannot be simulated in any of the animal models. Stroke provides a salutary lesson about the reliability of animal models of complex illness: although animal models are an indispensable part of pharmaceutical R&D, they do not always provide reliable predictors of clinical outcome.

But we did not give up the idea that the excitotoxic actions of glutamate acting at NMDA receptors might play a key role in the secondary damage caused by stroke or other cerebral ischemic insults. In 1987, Philippe Ascher and colleagues in Paris discovered that glycine could markedly facilitate NMDA responses. Glycine achieved this effect by binding to a distinct site within the NMDA receptor complex that allosterically regulates receptor function. This effect of glycine is so great that virtually no response can be elicited in the absence of glycine, suggesting that it acts with L-glutamate as a coagonist. It soon became clear that two existing NMDA antagonists, kynurenic acid and the aminopyrrolidone HA-966, acted by blocking the effects of glycine (Singh et al., 1990). We used these compounds as the basis of a substantial medicinal chemistry program aimed at discovering potent glycine-site directed NMDA antagonists as alternatives to MK-801. Our chemists synthesized several very potent compounds of this type, and in vivo these compounds proved to be neuroprotective in the same models used to test MK-801—and as a bonus they did not cause cortical neuron vacuolation (Leeson and Iversen, 1994). But the compounds were very insoluble in water, and they bound strongly to plasma proteins that limited their utility. We were not able to find a suitable development compound, and the project was abandoned. Other companies persisted with the approach, however, and Glaxo Smith Kline (GSK) took the glycine-site directed NMDA antagonist gavestinel into advanced (Phase III) clinical trials for the acute treatment of stroke—but gavestinel failed to provide significant clinical benefit, and it too had to be abandoned.

By the late 1980s the Neuroscience Research Centre had entered the new era of molecular pharmacology, with a molecular biology group ably headed by Dr. Paul Whiting. We decided to embark on a long-term project to analyze the subunit composition of the NMDA receptor in different CNS regions, in the hope that subtype-selective drugs might in future offer more selective pharmaceutical weapons. This was a formidable undertaking, as the NMDA receptor was known to contain a mixture of different subunits, comprising NR1 (with various different splicing isoforms) together with one or more of the NR2 subunits, A, B, C, or D. By cloning and expressing these various subunits and preparing antisera, it was possible to use immunochemistry to gain insight into the composition of native NMDA receptors, and we were able to show that some contained more than one of the NR2 subunit categories. Clearly this was going to be a long task, and I was not at the laboratory long enough to see it come to fruition. An advantage of working for a strong science-led company such as Merck in those days was the willingness to tackle major long-term basic research questions such as this.

Another of the projects initiated at the Neuroscience Research Centre was one related to the inhibitory amino acid GABA. We started collaboration very early on with a Danish research group who were then working in the company Ferrosan. Their head Jorgen Buus-Lassen, and the chemist Frank Watjen became close colleagues, and we learned a great deal from their experience and knowledge of pharmaceutical R&D—which was at first unknown territory to me and to most of my colleagues in the Merck lab, who had largely been recruited from academia. The objective of our collaboration with Ferrosan was to discover drugs that acted as Partial agonists at the benzodiazepine modulatory site in the GABA-A receptor. Conventional benzodiazepine tranquilizers, such as diazepam (“Valium”) were full agonists at the site and suffered from disadvantages such as sedation, ataxia, and dependence liability. Preliminary data from “BZ partial agonists” suggested that they might retain the desired anticonvulsant and antianxiety effects while lacking these disadvantages. Frank Watjen undertook an imaginative medicinal chemistry program, synthesizing oxadiazole derivatives of the imididobenzodiazepine antagonist drug flumazenil. The compounds were assessed in the behavioral pharmacology lab at Terlings Park, headed by my wife Sue. Some of these compounds showed considerable promise as potent anticonvulsants and were active in animal models of anxiety, with greatly reduced sedative or ataxic properties (Tricklebank et al., 1990). Long-term tests showed that the lead compounds also had reduced dependence liability. One of our lead compounds entered formal development in Merck in the United States, but it failed early on in toxicology. By then both sides of the collaboration were running out of chemistry space in which to work—we found ourselves isolated on small islands of patent-free chemical territory surrounded by an ocean of very broad patents, written by the Swiss company Roche, who were also pursuing the idea of benzodiazepine partial agonists. It was my first experience of the monopoly power that patents can confer. In fact the concept of benzodiazepine partial agonists has never been shown to work in humans—several compounds with this profile did enter clinical trials, but it was found that the animal models were not accurately predictive—in particular most of these compounds continued to exhibit unacceptable levels of sedation.

We continued to believe that drugs that modulated GABA-A receptor function could prove attractive as psychoactive agents. Our approach switched to targeting different subtypes of the GABA-A receptor. From the molecular pharmacology studies of Eric Barnard (who succeeded me at the MRC Unit in Cambridge) it was known that the GABA-A receptor was composed of several different protein subunits. There were four families: 6 α-subunits; 3 β-subunits; 3 γ-subunits; and one δ-subunit. At least one α, one β, and one γ-subunit were needed to form a functional receptor complex, but no one knew which combinations actually existed most commonly, or whether these differed from one brain region to another. Keith Wafford, Paul Whiting, and Ruth McKernan set out on the heroic task to answer these questions. By preparing antibodies to the different subunits and using immunoadsorption methods they painstakingly discovered which receptor subunit combinations were commonly found in mammalian brain. Although in theory there were thousands of possible subunit permutations, in fact fewer than 20 such combinations accounted for most of the GABA-A receptors in brain. At the time I left Merck this work was still ongoing, but it later matured and led to the discovery of novel drugs that targeted specific receptor subtypes—and some of these showed early promise as anxiolytics, cognitive enhancers, or antialcohol agents.

But my own personal research interest was increasingly focused on research on the neuropeptides, which allowed me to continue the fascination with the subject that I had acquired while in Cambridge. At the Neuroscience Research Centre we developed two major projects—one based on the concept that cholecystokinin antagonists might prove valuable as a novel class of antipanic/antianxiety drugs, the other based on the concept of substance P antagonists as potential novel analgesics.

The cholecystokinin project was inherited from earlier work in the Merck labs in the United States. By the traditional approach of screening natural products Merck scientists had discovered the naturally occurring benzodiazepine compound asperlicin—which proved to be a selective antagonist of the CCK-1 receptors found in the gut. Merck chemists went on to synthesize simplified compounds based on the asperlicin structure, and one of these, devazepide, was a thousand times or potent than the natural product—retaining a high degree of selectivity of the CCK-1 receptor subtype. Merck chemists undertook further structural modifications to obtain the first “brain selective” compound L-365,260, which had selectivity for the CCK-2 receptor subtype most commonly found in brain. At the time these were breakthroughs in the field of neuropeptide pharmacology because outside the opiate field almost no nonpeptide drugs were known that acted with potency and selectivity at neuropeptide receptors.

We started to explore the CNS pharmacology of these compounds in animals. We were attracted by the findings published at that time of the effects of C-terminal fragments of CCK in human volunteers. The Canadians Bradwejn and De Montigny in Montreal reported that the intravenous injection of microgram amounts of such peptides reliably caused a psychic panic reaction in the volunteers, which was mercifully short lived, but clearly dose-dependent. When such intravenous challenges were administered to patients who suffered endogenous panic attacks they reported that the chemically induced panics were identical to those which they experienced spontaneously. Although there were no reliable animal models of panic, we were able to show that L-365,260 possessed some anxiolytic effects in animal models of anxiety. The compound entered development as a potential new antipanic agent—and initial clinical trials data were encouraging. It was possible to show that pretreatment with an oral dose of L-365,260 could completely protect human volunteers from the panic attack normally elicited by intravenous challenge with a CCK fragment (Bradwejn et al., 1994). Furthermore, the effect of L-365,260 was dose-related, so it was possible to determine just how much was needed for the antipanic effect. But unfortunately when the clinical trials of this compound were extended to a 6-week, placebo controlled trial in patients with endogenous panic attacks the results were entirely negative—there was no reduction either in the frequency of spontaneous panic attacks, or the level of anxiety patients experience between attacks (Kramer et al., 1995). We seem to have fallen for the logical non sequitur: “CCK Causes Panic, Therefore Panic is Caused by CCK.”

Although we had invested a considerable effort in discovering secondgeneration back-up compounds for L-365,260, Merck senior management decided to stop further development of the CCK antagonist program. A number of other major companies had CCK antagonist programs, but these rapidly faded from sight, and no other CCK antagonist has so far reached the market as an antipanic/anxiolytic agent.

Apart from the antipanic idea, we had considered other possible applications for CCK antagonists—particularly in the field of pain control. The CCK system in spinal cord and brainstem appears to represent a parallel but distinct neuronal system to the system of neurons containing enkephalins and other endorphins, and the CCK system seems to act as an “antiopioid” control mechanism. In some chronic pain conditions an imbalance between the CCK and opioid control systems may develop, so that CCK overrides the pain-relieving actions of the endogenous opioids. We were able to show in animal models that CCK antagonists could enhance the pain-relieving actions of morphine and related opiate analgesics (Dourish et al., 1988) and we wanted to see if this might extend to the clinic. But I was unable to pursue this idea until after I left Merck in 1995—when I was able to negotiate a license to acquire the rights to all of the Merck CCK antagonists—and to purse the idea of their potential utility as adjunct of opiates—for more details see below.

The largest neuropeptide project at the Neuroscience Research Centre was the Substance P (SP) program that was an extension of my earlier interest in this peptide while in Cambridge. We set ourselves the task of discovering potent SP receptor antagonists that could be used to test the idea that such compounds might prove to act as novel centrally acting nonopioid analgesics. This was not easy, as no nonpeptide drugs were known that acted on SP receptors. Brian Williams, a peptide chemist in our lab, set out to design more rigid molecules by synthesizing cyclic peptide derivatives. He discovered a series of such peptides that acted as moderately potent antagonists (McKnight et al., 1991)—but these were still peptides, with all the disadvantages that these possess—including lack of oral availability, failure to penetrate into the CNS, and susceptibility to metabolism. An effort was made to identify a nonpeptide antagonist lead through natural product screening, which had proved so successful for CCK. Using Merck Research Laboratories Spanish natural products screening laboratory, parallel assays using I125-SP and I125 eledoisin binding to rat brain membranes (NK-1 and NK-3 respectively) were established. During a 2-year period more than 50,000 fermentation broths were screened in each of these assays, but no positive leads were identified. The breakthrough eventually came in 1991, when chemists at the Pfizer company published the structure of the first subnanomolar potency nonpeptide SP antagonist, CP-96,345. It was remarkable how quickly after this other companies were able to discover their own SP antagonist leads, usually by computer searches of their chemical collections, using the pharmacophore defined by the Pfizer compound. Merck launched a substantial medicinal chemistry program initially at Terlings Park but later accompanied by an equally large chemistry effort in the U.S. laboratories at Rahway. Ed Scolnick, who was head of Merck’s research, was a passionate believer in the SP project—and occasionally he liked to generate some inhouse competition by setting up rival teams with the same objectives!

Both chemistry teams generated some remarkably potent compounds, with picomolar affinity for the NK-1 SP receptor subtype—which by then had been selected as the key target. Although pain remained a key clinical target, we used other animal models to quickly sort out orally active potent compounds—among these models the antiemetic actions of the SP antagonists in the ferret and blockade of SP-induced extravasation in guinea pig skin proved particularly useful, and there were several compounds whose potencies were measured in micrograms per kilo in these assays. The biological aspects of this work were complicated by the finding that lead compounds from various chemical classes proved to have much lower affinities for the NK-1 receptors in rats and mice than for human or other mammals. This meant that standard rodent models could not be used, and new tests had to be devised in such species as ferrets, gerbils, and guinea pigs. By the time I left Merck we had begun to deliver development compounds into the Merck system—and within a few years the first disappointing results had been generated in clinical trials of these compounds against various human pain conditions—they were not sufficiently effective to justify any further development for this indication. For a while Merck became excited by the possibility that the SP antagonists might act as novel antidepressants, but the positive clinical data obtained in an early trials could not be repeated in a Phase III trial.

At the end of the day it was the antiemetic properties of the SP antagonists that translated reliably into the clinic. The SP antagonist aprepitant was launched as Emend® for the treatment of nausea and vomiting associated with cancer chemotherapy, an increasing problem with the new powerful cytotoxic drugs such as taxol or cisplatin. Aprepitant is usually added to a 5-HT₃ receptor antagonist, and the combination provides better overall protection; the SP antagonist seems particularly valuable in protecting against the delayed phases of emesis experienced several days after the initial chemotherapy (Gralla et al., 2005). Although emesis was not in our original plan, it is very gratifying to see the first genuine medical use for a SP-based medicine—particularly for someone like me who has worked on SP off and on for more than 30 years!

We were more successful in another project aimed at pain relief compounds—in this case for the treatment of migraine headache. In 1987 Glaxo scientists discovered a radical new approach to the treatment of migraine in the form of the drug sumitriptan, a serotonin agonist that for the first time was able to stop a migraine headache even after the attack had already begun. Migraine is a very common and distressing condition, and sumitriptan was immediately recognized as an important breakthrough. Along with several other companies we decided to see if we could discover a secondgeneration version of sumitriptan with some advantages over the original compound. A weakness of sumitriptan is its poor oral bioavailability; the first version of the drug to be marketed was a subcutaneous self-injectable form. Patients on the whole do not like injecting themselves, and the product was also extremely high priced. We launched a medicinal chemistry project to see if we could discover compound with better oral absorption properties, and thanks to some excellent chemistry we were able to develop rizatriptan, which had a far more rapid oral absorption, and as it proved in the clinic, a faster onset of headache relief. Merck combined these properties with a freeze-dried “wafer” formulation that dissolved instantly in the mouth so that patients found the product easy to take (Goldstein et al., 1998). Rizatriptan was launched on the market soon after I left Merck, and under the trade name Maxalt® it has competed successfully with the several other “triptans” now available. Although rizatriptan was undisguisedly a “me too” project, like many other such products in the pharmaceutical world it did offer some real advantages, and from a morale point of view it was good for the Neuroscience Research Centre to see that we really could discover and launch a new medicine! During my 12 years as Director we saw only two products coming near to registration—rizatriptan and aprepitant—and we had seen a number of development candidates fail at various stages in the development process.

My 12 years working for Merck Research Laboratories were hectic but rewarding. I learned a great deal about research in an industry that is highly competitive and demanding. I was fortunate to work for Merck—one of the leading research-based companies in the pharmaceutical world—led at that time by Roy Vagelos, originally an NIH scientist. Roy brought his work and ideas on cholesterol metabolism with him to Merck and successfully pioneered the first “statins” to control excess cholesterolemia—drugs that have had an impact on mortality from cardiovascular disease at least as great as that of the earlier antihypertensive medicines. During my period at the company Merck and Vagelos were riding high—with double-digit increases in income and profits every year and the accolade of Fortune magazine’s annual survey as “America’s Most Admired Company” for three straight years (1987–1989). With the remit to build a completely new research laboratory, and great freedom to choose which projects to work on, I had a unique opportunity and enjoyed taking it. Of course there were pressures to deliver results—I found it curious that basic research scientists at Merck were asked to state their annual objectives in very specific terms—to discover a new drug by a particular point in the year was hardly something one could guarantee to deliver! But management by objectives and reward by achievements were the principles by which U.S. companies operated—even though both ideas were at first unfamiliar to the academic mind. I soon realized that my job necessitated a good deal of transatlantic travel, if only on the principle that it was a good idea to be in the room when your program and budget were being discussed! Fortunately I had many excellent colleagues in Merck, who patiently helped to teach me all the things that I needed to know about the complexities of pharmaceutical R&D—my first boss Clement Stone and my later boss Bennett Shapiro were particular strengths—although Bennett like me came straight from an academic job as Chair of Biochemistry in Seattle overnight to be in charge of all preclinical research at Merck! It is sad to see Merck now suffering from the withdrawal of one of its leading new products, the anti-inflammatory agent Vioxx. In the subsequent cost-cutting exercise that was needed it was decided that the Neuroscience Research Centre should be closed down, and Merck withdrew from most of its research activities in the CNS arena, choosing instead to focus on the company’s traditional strengths in vaccines and in the cardiovascular field.

Life After Merck

In 1993 Sue was offered the chance to apply for the Chair of Experimental Psychology at Oxford University—which had previously been held by her former mentor Larry Weiskrantz. This was one of the premier departments in the country, and one that Sue had always admired. She applied and was offered the job; this was a big decision but the opportunity was too good to miss and she accepted. Sue entered Oxford University where there was only a handful of other female Heads of Department at the time, compared to several hundred men, although this gender imbalance has improved a little in the past decade! Under her leadership the Department continued to flourish as one the leading centers for experimental physiological psychology, with a considerable emphasis on studies of animal behavior. Sue later moved from her post as Head of Department to join the Vice-Chancellor’s office as a Pro-Vice Chancellor, in charge of planning and resource allocation—two concepts that were difficult to explain to most academics!

I stayed on at the Neuroscience Research Centre for a couple of years after we moved our home to a village near Oxford—but I found it increasingly stressful to commute to work each day on the busy motorways around London—with a journey time that could vary from one to several hours. Also becoming somewhat restless after having done the job for more than 12 years, I opted to take early retirement and left Merck in March 1995.

Fortunately I discovered that “life after Merck” was possible, and even enjoyable. I was able to obtain a license from Merck for all of the CCK antagonist compounds that we had worked on, and developed a start-up company, Panos Therapeutics Ltd., to continue the development of some of these drugs. I was fortunate in finding a business partner, Michael Clark, with considerable knowledge of the pharmaceutical business, and we formed a collaborative partnership with a small British pharmaceutical company, ML Laboratories. Their scientists planned and undertook several clinical trials aimed at seeing whether the addition of a CCK antagonist to strong opiate analgesics might improve pain relief. The culmination of the studies was in the form of two parallel “proof of concept” Phase II clinical trials which compared the CCK-1 antagonist devazepide with the CCK-2 antagonist L-365, 260. The results were clear, whereas devazepide offered significant improvements in pain relief, L-365,260 did not. This probably reflects the fact that the CCK-1 receptor predominates in human spinal cord and brainstem—the most likely sites for the CCK/opiate interaction. Unfortunately after a boardroom takeover, ML Laboratories was no longer interested in pursuing further research on our compounds—and we parted company from them. Subsequently we were also able to get release from any further obligations to Merck. I continue to hope that Panos Therapeutics will be able to continue developing devazepide as an adjunct to opiates because the preliminary clinical data were promising.

In Oxford I was fortunate to be offered an honorary appointment as a Visiting Professor in the Department of Pharmacology, by the head of department, David Smith. This entailed a small amount of student lectures and tutorials in return for an office in the department; a place to park a car in the center of Oxford (a considerable perk!); and the ability to use the title of professor in the University of Oxford. This privilege has continued to this day. In addition I acquired several other academic jobs over subsequent years. From 1996–1999 I acted as a part-time consultant to the MRC Cyclotron Unit at the Hammersmith Hospital campus in west London. This was the country’s leading brain imaging research centre, specializing in positron emission tomography—but the MRC were keen to see it develop more collaborative relationships with external groups, particularly those in industry. I learned a great deal about the fascinating field of positron emission tomography (PET) imaging—which is becoming increasingly important to pharmacology as a means of visualizing receptors in the intact human brain through the binding of selective radiotracers and assessing drug interactions with such receptors. Subsequently this laboratory was partly “privatized” and now earns a considerable segment of its income through contracts with industry. Another challenging job was at King’s College, London where I was a part-time professor (1999–2004) helping to develop a new research laboratory, The Wolfson Centre for Age Related Diseases. This was sponsored by a grant from the Wolfson Foundation, which allowed the building of a modern new research wing on the Guy’s Hospital campus of the medical school. Although this was an exciting new venture, I also learned just how starved of resources our major British universities had become. I was keen to attract a “high flier” in the Alzheimer’s disease research field from overseas to take over from me as Director—but I found that what little King’s had to offer in any “package” could not compete with what was available in the United States or Europe to attractive candidates. We eventually made a very satisfactory internal appointment, and the Centre has flourished with an excellent combination of basic and clinical research.

Some of my most interesting jobs since leaving Merck have been at the interface between science and business, where I feel that my experience of both worlds may have something particular to offer. I have acted as a member of the Scientific Advisory Board for a Danish venture capital fund, BankInvest, for the past 10 years, and found this an intriguing job—trying to assess the scientific merit and the commercial reality of new start-up companies in the human health field—and assessing the performance of the existing portfolio companies. In the United States, where Sue and I have continued summer visits to San Diego, California, on a regular basis, I have acted as an informal consultant to the local fund Forward Ventures, from whom I also learned a great deal about the biotechnology boom there. Also in San Diego I serve as Chairman of the Board of Directors for Acadia Pharmaceuticals Inc., a local company developing products for CNS indications. I have known the scientific founder of Acadia, Mark Brann, since he was a summer student in my lab in Cambridge more than 20 years ago—and have followed Acadia’s development from the beginning. The company is now at an exciting stage of growth—having moved several products into advanced stages of clinical development. I attend Board meetings every quarter and spend some weeks in the company each summer.

Back at home I developed an interest in the pharmacology of cannabis and other illicit psychoactive drugs. I was coopted by the UK House of Lords Science and Technology Committee to act as their scientific advisor for their inquiry into cannabis (1998). I knew virtually nothing about the subject but soon learned and found the process of summoning witnesses for questioning by the Select Committee in the grand surrounding of the House of Lords an intriguing new experience. Our report, which advocated more research on the medical uses of cannabis, and deflated some of the more aggressive claims about the harmfulness of the drug, was greeted with instant dismissal by the government of the day—but it may have had some delayed impact. The U.K. government permitted a small company, GW Pharmaceuticals, to establish a cannabis growing facility and to undertake clinical trials of cannabis-based medicines. Their herbal cannabis extract “Sativex” has recently been approved in Canada and awaits probable European registration in the next few years. Meanwhile, a liberal-minded British Home Secretary, David Blunkett, recommended that cannabis be downgraded from Class B to Class C (which carries reduced criminal penalties), and this was duly done in 2001. Since then various politicians have sought to reinstate cannabis to Class B—which eventually happened in 2008. My own view is that the harmfulness of all psychoactive drugs (including the legal ones, alcohol and nicotine) needs to be reassessed using scientifically objective evidence. If this were done I believe that cannabis would rate at about the same level of harm as alcohol—and it does not deserve the criminal penalties incurred for its use on both sides of the Atlantic. Although the misuse of psychoactive drugs is a major social problem in the Western world, our current “war on drugs” has failed to stem the increased use of such drugs, and it may be time for a radical reappraisal of policies. In many ways the criminalization of psychoactive drug use may have done more harm than good, both to individuals and to society. I have become a member of the U.K. government’s Advisory Council on the Misuse of Drugs whose job it is to advise into which classes various illicit drugs should be placed, so I am right in the firing line now! My newly acquired expertise in the cannabis field was distilled into a monograph The Science of Marijuana published by Oxford University Press in 2001, intending to bring what is known about the scientific and medical aspects of cannabis to a nontechnical readership. The scientific field has since moved on rapidly, particularly with the discovery of the naturally occurring endocannabinoids, and a second edition of my book was completed in 2007. This gave me a taste for scientific writing, and I followed the cannabis book with a short volume in the Oxford University Press series of “Very Short Introductions,” A Very Short Introduction to Drugs, published in 2001 covered the medical and recreational uses of drugs. It was a considerable challenge to condense everything one knew about pharmacology into 40,000 words! This small book proved to be a success and has been translated into several languages. I also wrote a popular science monograph on the amphetamines, titled Speed, Ecstasy, Ritalin: the Science of Amphetamines, which was published also by Oxford University Press in 2006. I greatly enjoyed these writing jobs and intend to continue. The next challenge is to complete a student text with Sue and my friends Floyd Bloom and Bob Roth as coauthors, titled Introduction to Neuropsychopharmacology— combining basic neuropharmacology with information on how psychoactive drugs are used medically and recreationally. Stemming from a conference held in 2007 in Sweden to celebrate “50 Years of Dopamine,” I will also coedit the Handbook of Dopamine to record the advances in research on this most productive of all monoamines.

In Conclusion

I consider myself very fortunate in having often been in the right places at the right times that allowed me to achieve some degree of success. I had the good fortune to enter research on a “hot” area of neuroscience at a very early stage in its development. Although I have never had the innate creativity or originality of a Julie Axelrod or a Sol Snyder, being in the right places enabled me to take advantage of opportunities as they arose. Research on the catecholamines and other neurotransmitters has since grown beyond all recognition. The past 50 years have seen amazing advances in the techniques now available for their study—including the ability to visualize the function of these chemicals in the living intact human brain through imaging techniques. In the same period the treatment of psychiatric illnesses has been transformed by drugs that act in one way or another on the brain monoamine systems. Although the pace of such medical advances has slowed, we look to the genetic revolution to bring us the next generation of such drugs, including the ability to treat hitherto intractable conditions such as Alzheimer’s disease. For the first time we may gain a real understanding of the fundamental molecular basis of psychiatric illness.

Apart from the privilege of having taken part in some small way in the explosive growth of neuroscience in the past few decades I have also been blessed by association with the many talented colleagues who came to work in Cambridge or in Terlings Park as students, visitors, postdocs, or staff. Many have gone on to their own productive research careers and it is a wonderful pleasure to see their creativity and success.

Selected Bibliography

Bird ED, Iversen LL. Huntington’s Chorea—post-mortem measurement of glutamic acid decarboxylase, choline acetyltransferase and dopamine in the basal ganglia. Brain 1974;97:457–472.

Black IB, Hendry IA, Iversen LL. Differences in the regulation of tyrosine hydroxylase and dopa decarboxylase in sympathetic ganglia and adrenals. Nature New Biol. 1971;231:27–29.

Bloom FE, Iversen LL. Localizing 3H-GABA in nerve terminals of rat cerebral cortex by electron microscopic autoradiography. Nature 1971;229:628–630.

Bradwejn J, Koszycki D, Couetoux du Tertre A, van Megen H, Den boer J, Westenberg H. The panicogenic effects of cholecystokinin-tetrapeptide are antagonized by L-365,260, a central cholecystokinin receptor antagonist, in patients with panic disorder. Arch Gen Psychiatry 1994;51:486–493.

Burgen ASV, Iversen LL. The inhibition of noradrenaline uptake by sympathomimetic amines. Br J Pharmacol 1965;25:34–43.

Clement-Cormier YC, Kebabian JW, Petzold GL, Greengard P. Dopamine-sensitive adenylate cyclase in mammalian brain: a possible site of action of antipsychotic drugs. Proc Natl Acad Sci USA 1974;71:1113–1117.

Creese I, Burt, DR, Snyder SH. Dopamine receptors and average clinical doses. Science 1976;194:546.

Cuello AC, Kanazawa I. The distribution of substance P immunoreactive fibers in the rat central nervous system. J Comp Neurol 1978;178:129–156.

Dourish CT, Clark ML, Iversen SD. Enhancement of morphine analgesia and prevention of morphine tolerance in the rat by the cholecystokinin antagonist L-364,718. Eur J Pharmac 1988;147:469–472.

Freedman SB, Harley EA, Patel S, Newberry NR, Gilbert MJ, Mcknight AT, Maguire J, Mudunkotuwa NT, Baker R, Street L, Macleod A, Saunders J, Iversen LL. A novel series of non quaternary oxadiazoles acting as full agonists at muscarinic receptors. Brit J Pharmac 1990;101:575–580.

Glowinski J, Axelrod, J. Inhibition of uptake of tritiated-noradrenaline in the intact rat brain by imipramine and structurally related compounds. Nature 1964;204:1318–1319.

Glowinski J, Iversen LL. Regional studies of catecholamines in the rat brain I: the disposition of H3-norepinephrine, H3-dopamine and H3-DOPA in various regions of the brain. J Neurochem 1966;13:655–669.

Goldstein J, Ryan R, Jiang K, Getson A, Norman B, Block GA, Lines C. Crossover comparison of rizatriptan 5 mg and 10 mg versus sumatriptan 25 mg and 50 mg in migraine. Rizatriptan protocol 046 Study Group. Headache 1998;38: 737–747.

Gralla RJ, de Wit R, Herrstedt J, Carides AD, Ianus J, Guoguang-ma J, Evans JK, Horgan KJ. Antiemetic efficacy of the neurokinin-1 antagonist, aprepitant, plus a 5HT3 antagonist and a corticosteroid in patients receiving anthracyclines or cyclophosphamide in addition to high-dose cisplatin: analysis of com bined data from two phase III randomized clinical trials. Cancer 2005;104: 864–868.

Hendry IA, Iversen LL. Reduction in the concentration of nerve growth factor in mice after sialectomy and castration. Nature 1973;243:500–504.

Hendry IA, Stockel K, Thoenen H, Iversen LL. The retrograde axonal transport of nerve growth factor. Brain Res 1974;68:103–121.

Hertting G, Axelrod J. The fate of tritiated noradrenaline at the sympathetic nerve endings. Nature 1961;192:172–173.

Iversen LL. The uptake of noradrenaline by the isolated perfused rat heart. Br J Pharmacol 1963;21:523–537.

Iversen LL. The uptake of catecholamines at high perfusion concentrations in the isolated rat heart: a novel catecholamine uptake process. Br J Pharmacol 1965; 25:18–33.

Iversen LL, Iversen SD, Bloom FE, Douglas C, Brown M, Vale W. Calcium-dependent release of somatostatin and neurotensin from rat brain in vitro. Nature 1978a;273:161–163.

Iversen LL, Iversen SD, Bloom FE, Vargo T, Guillemin R. Release of enkephalin from rat globus pallidus in vitro. Nature 1978b; 271:679–681.

Iversen LL, Neal MJ. The uptake of 3H-GABA by slices of rat cerebral cortex. J Neurochem 1968;15:1141–114.

Iversen LL, Rossor MN, Reynolds GP, Hills R, Roth M, Mountjoy CQ, Foote SL, Morrison JH, Bloom FE. Loss of pigmented dopamine-beta-hydroxylase positive cells from locus coeruleus in senile dementia of Alzheimer type Neurosci Lett 1983;39:95–100.

Iversen LL, Whitby LG. The retention of injected catecholamines in the mouse. Br J Pharmacol 1962;19:355–364.

Jessell TM, Iversen LL. Opiate analgesics inhibit substance P release from rat trigeminal nucleus. Nature 1977;268:549–551.

Johnston GAR, Iversen LL. Glycine uptake in rat CNS slices and homogenates: evidence for different uptake systems in spinal cord and cerebral cortex. J Neurochem 1971;18:1951–1961.

Kramer MS, Cutler NR, Ballenger JC, Patterson WM, Mendels J, Chenault A, Shrivastava R, Matzura-Wolfe D, Lines C, Reines S. A placebo-controlled trial of L-365,260, a CCKB antagonist, in panic disorder. Biol Psychiatry 1995;37: 462–466.

Lee CM, Iversen LL, Hanley MR, Sandberg BEB. The possible existence of multiple receptors for substance P. N S Arch Pharmac 1982;318:281–287.

Leeson PD, Iversen LL. The glycine site on the NMDA receptor: structure-activity relationships and therapeutic potential. J Med Chem 1994;37:4053–4067.

Mackay AV, Bird ED, Spokes EG, Rossor M, Iversen LL, Creese I, Snyder SH. Dopamine receptors and schizophrenia: drug effect or illness? Lancet 1980;2: 915–916.

Mcknight AT, Maguire JJ, Elliott NJ, Fletcher AE, Foster AC, Tridgett R, Williams BJ, Longmore J, Iversen LL. Pharmacological specificity of novel synthetic cyclic peptides as antagonists at tachykinin receptors. Br J Pharmac 1991;104: 355–360.

Miller RJ, Horn AS, Iversen LL. The action of neuroleptic drugs on dopaminestimulated adenosine cyclic 3,’ 5’-monophosphate production in rat neostriatum and limbic forebrain. Mol Pharmac 1974;10:749–766.

Neal MJ, Iversen LL. Autoradiographic localization of 3H-GABA in rat retina. Nature New Biol 1972;235:217–218.

Olney JW, Labruyere J, Price MT. Pathological changes induced in cerebrocortical neurons by phencyclidine and related drugs. Science 1989;244:1360–1362.

Otsuka M, Iversen LL, Hall ZW, Kravitz EA. Release of gamma-aminobutyric acid from inhibitory nerves of lobster. Proc Nat Acad Sci USA 1966;56:1110–1115.

Rossor MN, Iversen LL, Johnson AJ, Mountjoy CQ, Roth M. Cholinergic deficit in frontal cerebral cortex in Alzheimer’s disease is age dependent. Lancet 1981; 2:1422.

Sandberg BEB, Lee CM, Hanley MR, Iversen LL. Synthesis and biological properties of enzyme-resistant substance P analogues. Eur J Biochem 1981;114: 329–337.

Schon F, Iversen LL. Selective accumulation of 3H-GABA by stellate cells in rat cerebellar cortex in vivo. Brain Res 1972;42:503–507.

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Singh L, Donald AE, Foster AC, Hutson PH, Iversen LL, Iversen SD et al. The enantiomers of HA-966 (3-amino-1-hydroxypyrrolid-2-one) exhibit distinct CNS effects: (+)-HA-966 is a selective glycine/NMDA receptor antagonist but (-)-HA-966 is a potent gamma butyrolactone-like sedative. Proc Nat Acad Sci USA 1990;87:347–351.

Tricklebank MD, Honore T, Iversen SD, et al. The pharmacological properties of the imidobenzodiazepine FG-8205 a novel partial agonist at the benzodiazepine receptor. Br J Pharmacol 1990;101:753–761.

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Whitby LG, Axelrod J, Weil-Malherbe H. The fate of H 3-norepinephrine in animals. J Pharmacol Exp Ther 1961;132:193–201.

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Masakazu Konishi

BORN:

Kyoto, Japan

February 17, 1933

EDUCATION:

Hokkaido University, Sapporo, Japan, B.S. (1956)

Hokkaido University, Sapporo, Japan, M.S. (1958)

University of California, Berkeley, Ph.D. (1963)

APPOINTMENTS:

Postdoctoral Fellow, University of Tübingen, Germany (1963–1964)

Postdoctoral Fellow, Division of Experimental Neurophysiology, Max-Planck Institut, Munich, Germany (1964–1965)

Assistant Professor of Biology, University of Wisconsin, Madison (1965–1966)

Assistant Professor of Biology, Princeton University (1966–1970)

Associate Professor of Biology, Princeton University (1970–1975)

Professor of Biology, California Institute of Technology (1975–1980)

Bing Professor of Behavioral Biology, California Institute of Technology (1980– )

HONORS AND AWARDS (SELECTED):

Member, American Academy of Arts and Sciences (1979)

Member, National Academy of Sciences (1985)

President, International Society for Neuroethology (1986—1989)

F. O. Schmitt Prize (1987)

International Prize for Biology (1990)

The Lewis S. Rosenstiel Award, Brandeis University (2004)

Edward M. Scolnick Prize in Neuroscience, MIT (2004)

Gerard Prize, the Society for Neuroscience (2004)

Karl Spencer Lashley Award, The American Philosophical Society (2004)

The Peter and Patricia Gruber Prize in Neuroscience, The Society for Neuroscience (2005)

Masakazu (Mark) Konishi has been one of the leaders in avian neuroethology since the early 1960’s. He is known for his idea that young birds initially remember a tutor song and use the memory as a template to guide the development of their own song. He was the first to show that estrogen prevents programmed cell death in female zebra finches. He also pioneered work on the brain mechanisms of sound localization by barn owls. He has trained many students and postdoctoral fellows who became leading neuroethologists.

Masakazu Konishi

I was taken by surprise when Larry Squire asked me to write an autobiography, because I did not expect to die soon. My mother used to say that I should not do anything for her after her death, because she could not see it. True, I shall not be able to see what will be written about me. So, here is my version that I can see. I thank Larry and his committee for including me in this group of distinguished scientists.

My Origin

I was born on February 17, 1933, in Kyoto as the only child of “Nishijin” weavers. The section of the city known by this name is famous for silk sashes and kimono. My parents lived in a rented row house and worked at home using looms and silk provided by their contractor. My parents received little education, because they too grew up in poor weavers’ homes. My father went to school only for the first 2 years to learn how to read and write simple sentences, whereas my mother was told that all she had to learn was to read price tags, because teenage girls in her social “class” tended to become maids for rich families. Apparently, her father neglected the registration of her birth (1901) for 3 years. This meant that she would be 3 years older than other kids in her school class. Her father avoided this potential embarrassment for her by not sending her to school. My mother was forever bitter about her father’s misjudgment.

The pacific war (1941–1945) started when I was 8 years of age. The first bad thing that emerged with the war was the militarization of schools. Teachers treated little children like soldiers. The whole school started daily with the broadcasting of the national anthem and a speech by the principal. Otherwise, the war did not seem to affect the life of ordinary people until the United States started to bomb cities and food shortage became acute. To cope with this situation, we planted edible plants wherever we could find space, including schoolyards. One half of the playground in our school was converted to underground bomb shelters and arable lands by the little hands of pupils. I raised edible plants in our backyard and on the roof of our house where I used boxes filled with soil to grow plants such as pumpkins. My pet rabbits, which I raised on weeds, became important sources of proteins. As the country was entering the last phase of the war, the differences between rich and poor became small, because there was little that money could buy. This equalization was perhaps the only unintended benefit of the war. My mother appeared to thrive under these conditions, because she was so used to deprivation. While my father had to work in a military factory in another city, she managed to find a source of black market beef for distribution with profit.

The people of Kyoto were lucky, because the city was never bombed, when all major cities were literally reduced to ashes. I recall seeing hundreds of miserable looking and crippled refuges in the Kyoto train station immediately after the bombing of Osaka, which is a large city some 40 kilometers away. Although Kyoto was spared, we suffered from food shortages, which were more severe after the war than during the war, because an economic chaos followed the war’s end. My father and I would go to countryside to buy rice or anything edible including watermelons from farmers. They did not take cash, because there was nothing the money could buy. We took used clothes including my mother’s for exchange. This experience also prompted my father to buy and sell used clothes. This was the first time my father succeeded in business well enough to rent a nice store near the center of the city. As the postwar chaos subsided, so did his business.

My mother lived and worked alone since my father’s death at 60 years of age. My grade-school friend Tatsuo Naito kept me informed of her after my departure for the United States, because he delivered mail in her neighborhood. When he wrote me that she could no longer take care of herself at 81 years of age because of senility and deafness, I decided to bring her to Pasadena, California. I had no other choice as her only son. Putting one’s parent in an old people home was thought to be the worst thing a child could do to his parents. Nothing was harder than taking care of my mother, because we could not communicate with each other. Judging from her attitude, I was different from other people, although she would tell my guests that I was her “brother.” Fortunately, she had no other illnesses until her death at 89 years of age. Despite the hardship, I experienced some enlightening moments. Watching TV about marine life, she said “I did not know the octopus swims the head first.” This was her first time to see an octopus that moved. Another time, when I took her out for a drive, she was amazed to see men running on the street with their upper body uncovered. She said “They are naked.” Even then grown men did not run “naked” on city streets in Japan, while some women walked bare-breasted in our neighborhood. People did not see any sexual connotation in the milk-producing organ. My mother also caught a live quail that flew into our house and kept it in a cage until I came home. I had never expected this depth of observation and reasoning by a person who seemed to have lost her rational mind.

Early Schooling

My father read storybooks for me before I learned how to read in school. My mother occasionally asked our janitor neighbor to help me with arithmetic. I am bad with numbers to this day. When I was a third-year pupil, our teacher, Mr. Goto, asked our science class how we could turn two wheels in opposite directions with one belt. I instantly answered that twisting the belt would do it. He looked astonished and said emphatically “Yes, you are right.” I knew this trick, because I used to play with my mother’s spinning wheels. Nothing gave me more confidence than his praise, and I began to get better grades. As the only child, my best playmates were animals including insects, fish, birds, rabbits, and dogs. When Mr. Goto showed us how two spiders fought upon meeting each other on a stick he held horizontally, I was so happy to see that even our teacher (God for us) played like me.

When I finished my grade school education, I did not have any role model to follow. My parents did not have any ideas, although my mother complained that our relatives were against giving me higher education. One of my school friends told me that he was going to a private agricultural middle school in the southern suburb of the city. I decided to join him because of my aspiration for ranching. I loved American cowboy movies mainly because of the animals that appeared on the screen. However, the school quickly disappointed me, because I was bored by the subjects taught and by the bad teachers. I looked around to find that there was a new public high school with an agriculture section near the opposite end of the city. The question was how to transfer to this school. My parents knew a local politician who had some connection to the city school board. He apparently smoothed the way for me to move to the new school. Later I returned his favor by volunteering to work for his election to the city government. All I did was to broadcast loudly his name from his small election headquarters as Japanese politicians still do today. I liked the new school, but I quickly switched from agriculture to the liberal art section that was added after my arrival, because I started to mix with kids who were preparing for college entrance examinations. These kids also had middle-class hobbies such as tennis and skiing. Because I was already hiking a lot by myself or with my dog, I joined the mountaineering club. Most of its members also belonged to the biology club, which I led. The club activities helped me come out of my only-child cocoon.

There was only one biology instructor, Mr. Yoshida who was also my homeroom teacher with whom we had lunch everyday. He did not teach well, but I liked him because of his bear stories. He had gone to Hokkaido University in Sapporo. This island is known for big brown bears like the grizzly bear of North America. They kill a few people every year. The teacher had a little book that contained scary yet fascinating stories about how bears murdered people. The university was also known for the impact of an American professor named William S. Clark from Amherst College. When he was leaving Sapporo after 2 years as the head of the then Sapporo Agricultural College, he told his disciples (24 students), “Boys be ambitious.” Indeed, some of them became leaders in the Meiji era (1868–1912), which signaled the rise of modern Japan. Every Japanese child read about William S. Clark, because this story was in a school textbook. Our high school principal also worshipped William S. Clark. I thought that I should prepare for the entrance examinations of this university. Japanese universities use only written tests for deciding admission or rejection. Neither high school grades nor letters of recommendation are used. This was a saving grace for me, because not only were my grades average but also few teachers would have written good letters for me. Our principal once confronted several members of my biology club to ask if they were seriously studying for the college examinations. He said that he asked us because our parents had asked him about us. I was sure that my parents never asked such a question, because they did not know how one gets in a college. Because applicants from Hokkaido alone did not make the entry competitive enough, the university let the applicants from far away areas to take the tests in Tokyo. I traveled to the capital for the first time. When I told my biology teacher Mr. Yoshida that I passed the exams, he was incredulous at first. No wonder, because I pretended not to study for the tests. The principal congratulated me and asked me to send him a portrait of William S. Clark if I found one in Sapporo. I gladly obliged.

College Years

My parents gave me money to travel to Sapporo and live there for a while. Although my expenses were low, I knew that my parents could not afford even that level of expenditure on a continual basis. I earned some money as a day laborer and a private tutor for high school kids. My first rented room was like a prison cell of 3 m long by 2 m wide without any furniture, although all I needed was a low wooden table. I brought from home a set of bedding materials and a bicycle. I ate potatoes and herrings day after day because they were the cheapest items. To compensate for this “hardship,” the beautiful campus gave me a peace of mind and hopes. It had large elm trees and deep green lawn (the only Kentucky blue grass in Japan), meadows, streams, forests, apple orchards, and barns with horses and cows. This campus differed radically from all other former imperial universities, which had small gardens of white sand and pine trees. I was fortunate enough to receive a government loan for my undergraduate years. I even saved enough money to help my parents during the fatal illness of my father.

After the war, Japan adopted the U.S. system of college education in which students took general subjects for the first 2 years before specializing. This was a saving grace for me, because I was again thinking of majoring in agriculture for which this university was famous. As I compared zoology courses taught by the science faculty and those taught by the agricultural faculty, I became convinced that I should choose the former. Nevertheless, I found that most lectures in zoology were quite boring with a couple of exceptions. The neurophysiology course given by Professor Mitsuo Tamashige was sophisticated and interesting. He took a liking to me and invited me to use his equipment in his office, a rare privilege for a Japanese student. My project was to show that the rhythmic movement of the foot in land snails was centrally controlled. He and his assistant Dr. Mitsuhiko Hisada also took us to the university’s beautiful marine station to study the behavior and physiology of marine invertebrates. Dr. Shoichi Sakagami also gave an interesting course in which I was made aware of The Study of Instinct by N. Tinbergen. I thought that this was the field for me. One gets paid and praised for fooling animals with dummies. I was already doing it as a child. Sakagami and I also did field work together on great reed warblers in a large reed bed near our building. I was particularly interested in studying the response of a single territorial male to tape-playback of his own song. Portable tape-recorders were not available, and tapes were made of paper. I had to borrow a long electrical cable for my project. The vigorous response of the bird to tape-playback of his song was very exciting to me. However, I ended up writing my master’s thesis on brood parasitism by cuckoos, which lay eggs in the nests of reed warblers.

I was thinking of studying abroad since my early college years. I diligently went to English conversation classes at the American Cultural Center and an Episcopal church in Sapporo. I also made a few English-speaking friends including Christian ministers, diplomats, and U.S. army officers. Among them Mr. Daniel Meloy, the U.S. consul of Sapporo, was most supportive of me. A couple of times we went on long Jeep trips across Hokkaido. He would ask whether I wanted to speak English or Japanese, which he spoke fluently. Of course, I always chose English. He gave me one of his Brooks Brothers jackets after having seen me in a black university uniform at one of his official cocktail parties for local political and business leaders who seemed to look down on me. I kept and wore the jacket for many years in the United States. Judging from what my American friends told me, the United States offered a lot of academic opportunities, although I had briefly thought about going to Oxford, because two people I knew went there to get training in avian ecology. I carefully studied the catalogues of U.S. universities at the American Cultural Center and wrote for application forms. I applied for admission to several universities including the University of California, at Berkeley (UC Berkeley), the University of Michigan, and Yale University. I chose these schools, because they were known for vertebrate zoology. UC Berkeley was the first to send me a letter of acceptance. This fast response influenced my decision. Also, my roommate told me that his father liked Berkeley as a graduate student. Yale and Michigan also accepted me. Now, my problem was how to say no to these schools without offending anyone. In Japan, this “double dealing” would have caused problems for me. So, I wrote very polite letters profusely apologizing for declining their offers. Professor Francis Evans of Michigan wrote me back congratulating me for my success at Berkeley. This gesture profoundly impressed me. I learned later that this is how most U.S. professors would respond. In contrast, Dr. Sakagami told me that I should have not directly asked for a letter of recommendation from his boss Professor Tohru Uchida who was on a sabbatical leave at the University of Iowa. I flatly told Sakagami that it was my own business. A few days later, he told me that I could not stay for further graduate study, although I had no intention to continue there any way. It was exactly this kind of hierarchical system that I wanted to leave. I never looked back. It was ironic that I should later receive an honorary doctor’s degree from Hokkaido. Sakagami came to see me in Berkeley before I finished my degree there. We did not discuss the past. I respected him as a fine scientist.

Graduate Study

I was fortunate to receive a Fulbright travel fellowship to cross the Pacific. I had only 50 borrowed dollars upon my landing in Seattle, Washington. I arrived in Berkeley on September 9, 1958. I was impressed by the streamlined administrative procedures to get me started. I got a teaching assistantship, which meant a salary of about $1500 for two semesters in addition to a tuition exemption. I also earned additional $300 by assisting a summer course. I originally wanted to study under Professor Alden H. Miller who was well known for his study of avian speciation. I thought I would investigate the role of behavior in speciation. However, while I was still in Sapporo I heard that Miller was abroad on sabbatical and that there was a new assistant professor named Peter Marler. Because I had read and liked his paper “Some Characteristics of Animal Calls,” I immediately asked him for admission to his group. I was incredibly lucky. In addition to the teaching assistant duty I spent much time taking a few required and other courses. It took me about 2 years before I could do research full time.

I was lucky again to receive an excellent fellowship in my third year. My first project in the Marler laboratory was to determine the acoustic properties of song that birds use for species recognition. I chose birds with simple songs like the Oregon junco (Junco oreganus) to be able to modify the song with ease. The laboratory had a portable tape recorder (Magnemite 610) in which turning of the reels was done by a coiled spring as in old phonographs. I had to spin a heavy flywheel by hand to start the machine turning and crank up the spring every so often. The machine basically worked flawlessly and I recorded many songs in the Berkeley hills. I used my first Kay sonagraph in the Marler laboratory to look at the acoustic properties of songs. How do I change recorded songs though? Computers were not available then. I recall asking people at the Haskins Laboratory whether they could synthesize birdsongs with their Visible Speech machine, which scanned and converted cutout patterns (holes in paper) into sounds. Years later I got to know Alvin Liberman, who was one of the designers of the machine. He did not remember any letter from me. He said that he would have helped me, if he had read my letter. If I could see sounds on magnetic tapes, I might be able to cut and paste together different parts of a song. I either figured it out by myself or learned from someone that the magnetized parts of the tape might pick up fine iron particles. I got hold of iron powder and passed tape through a mound of it. I was delighted to see patches of iron powder corresponding to the song syllables in the trill type song of Oregon juncos. Assuming that the constant silent interval between syllables was important for species recognition, I cut and pasted tape to make the interval highly variable. When I played back this type of song in the field, wild juncos responded to it. This result was a great disappointment for me, because I had expected no response. Also, this project turned out to be very time-consuming; I could do field experiments only during the spring breeding season. I had to become realistic, because I was in my third year of graduate study.

Also, graduate students had to take an oral examination before submitting their theses. Although I was far from writing a dissertation, I decided to take the examination in my 4th year. I had a star-studded exam committee consisting of Ledyard Stebbins (plant evolution), Michael Lerner (population genetics), and Sherwood Washburn (human evolution). Because Stebbins and Washburn liked my term papers, they basically passed me without asking any hard questions. I was afraid of Lerner, because he was more quantitatively oriented than the others, but he asked what I had expected from him. He also asked if I knew anything about Lysenko. I knew a lot about this crazy Russian agronomist, because he was a hero among communist students in Sapporo. Later when I happened to see Professor Lerner in the cafeteria, he invited me to his table. He told me about new things he was thinking about. I did not understand anything he said!

So far as my dissertation research was concerned, I decided to go in a new direction. The idea of central coordination was hotly debated between ethologists and psychologists. It goes back to the turn of the last century when people like Friedländer and Biedermann carried out simple but clever experiments to prove or disprove the theory. Later people like Erich von Holst and James Gray performed sophisticated behavioral experiments to obtain evidence for or against central coordination. Peter Marler covered central coordination and endogenous rhythms quite extensively in his animal behavior course, because central coordination was at the core of the Lorenz-Tinbergen model of instinctive behavior. It was Donald M. Wilson who used neurophysiological methods to provide the most convincing evidence for central control of wing beating in the locust. While I was in Berkeley, Wilson joined our department and served on my thesis committee, which also included the famous Frank Beach of sexual behavior from the Department of Psychology. Wilson later moved to Stanford and invited me from Princeton to give a couple of lectures in the course he and Donald Kennedy were teaching. Shortly after this visit Wilson died in a rafting accident. I always wonder what Wilson would be doing if he were alive today. His work triggered a bandwagon effect in which other people tried to replicate his finding in every possible preparation. In retrospect, it is interesting to realize that the idea of central coordination did not affect the students of birdsong at that time, because few of them were interested in neurophysiology. Also, mechanistic views of birdsong simply did not exist.

I thought that the relationship between vocalization and hearing resembled that between motor coordination and sensory feedback. It was already known that humans could not speak normally when auditory feedback was removed or delayed. I thought that similar experiments in birds had to be done. I was also aware that I could not fail in this project, because either positive (deafening affects song) or negative results were worth publishing. I checked the literature on the subject and found Johann Schwartzkopf who developed a method for removing the avian cochlea in 1949. He also reported that the flute-like quality of a learned social call in adult bullfinches (Pyrrhula pyrrhula) gradually became shrill after deafening, although this operation did not affect other vocalizations. Similarly, Messmer and Messmer, for whom Schwartzkoff deafened blackbirds (Turdus merula), heard some abnormal sounds from these birds. However, I could not check the accuracy of their impressions, because they had no pictorial way to visualize birdsongs before the age of the sonagraph, which apparently did not reach German zoology laboratories until after 1956.

I read Schwartzkopf’s paper in German to learn his methods. This was not a big problem, because I had learned enough German in my undergraduate years in Sapporo. His illustrations of relevant anatomical structures and head-holding devices were very helpful. The main problems were the tools that I needed for his methods. The Marler laboratory was not equipped to do surgeries. The most advanced surgical technique the laboratory used was laparotomy, that is, making a hole in the bird’s body wall to see the gonads. I learned this method from Alden H. Miller and introduced it to the Marler laboratory. Deafening and laparotomy methods required a dissecting microscope and a light source that could illuminate the bottom of a small hole. The question was how to direct a light beam into a small hole without obstructing the view with the light source itself. Today, we can buy a dissecting microscope like the Zeiss Operating Microscope that comes with a vertical illuminator. Another graduate student who knew the method of vertical illumination told me how to solve the problem. According to his idea, I should use a mirror, which is coated only on one side, and place it 45 degrees relative to the optical axis of the dissecting scope. So, what this arrangement did was to allow me to see the bottom of the hole through the mirror, while this was directing some light into the hole. Where do I get such a mirror? He told me how to make one by exposing one side of a large cover glass to smoke from a candle.

My next problem was to find materials for making fine fishhooks. Schwartzkopf put a small wire hook at the end of a probe like a thin chopstick. He inserted the hook through a hole made in the bony cavity containing the cochlea. I looked for fine but relatively stiff wires without success. Then, it occurred to me that light bulbs contained wires holding the filaments. I collected a few burned out light bulbs. They did contain fine tungsten wires that were just perfect for making those hooks. Actually, I have never found a better material. As soon as I discovered this fact, I asked everyone around to save burned-out light bulbs. The remaining problem was how to adjust the angle of the bird’s head relative to the optical axis of the dissecting microscope, because the scope was on a fixed stand. I needed a small table that could be tilted around a pivotal point. I went to a junkyard and found a material suitable for the above purpose and that was an automobile rear-view mirror. I replaced the mirror by a plastic plate and constructed a simple device for holding the bird’s head. The plastic table could be moved up and down around the ball joint that came with the mirror. When I was almost finished with my research, the Marler laboratory got a National Science Foundation (NSF) grant that included a dissecting microscope with a vertical illuminator! I gave my operating table to Fred (Fernando Nottebohm) who used it for his thesis on chaffinches in Cambridge, England. I recall seeing the table in one of Fred’s laboratories at the Rockefeller University years later.

I operated on several species of songbirds using the Schwartzkopf methods. Most of the data in my thesis came from these species. As I worked on larger birds and also more abundant species like the domestic chicken, I found that I could remove the cochlea through the ear canal instead of a hole made in the skull. In recent years, I have taught several people to deafen zebra finches (Taeniopygia guttata) with this method using Zeiss Operating Microscopes. The Marler laboratory had a menagerie of animals ranging from fish to unusual mammals like kinkajous and a badger. No one seemed to be bothered by the crowing of my roosters, which I kept in an old greenhouse for plants in the central courtyard of the building. When the Animal Behavior Field Station was built up on the Berkeley hills, I moved some of the chickens there to make clean recordings. When Fred and I met there, we would return to his apartment for lunch with steaks and red wine as in his country, Argentina. Because we did not have enough soundproof boxes to house a large number of birds individually, I put all my deaf passerines in separate cages within a penthouse on the roof of the Life Science Building. I lined the penthouse walls with cheap sound absorbing materials. I spent most of my daytime sitting there listening and recording, because nothing was automated as it is today. I made about 3000 sonagrams for my thesis. I still have them in my office. To make one sonagram took a few minutes. I sometimes read a book while I was making sonagrams. The first set of data came from the chickens, because they matured much faster than wild birds. I knew enough about the vocalizations of chickens from my childhood experience. It was particularly interesting to see how deaf chickens failed to respond to vocal signals such as cackling and aerial alarm calls of their flock mates. Sonagrams of several vocalizations showed no systematic differences between normal and deaf roosters.

Around this time a German named Erich Bäumer published a paper on chicken vocalizations. I could guess what vocalizations he was referring to from his German descriptions. He was kind enough to send me his tape recordings upon my request. I made sonagrams of his recordings and compared them with my own recordings. He and I agreed on all identifiable adult vocalizations. Pictorial catalogues of animal voices with their functional significance were rare at that time except for the one by Marler for chaffinches. I also noted that there were graded and discrete signals (I used the terms analogue and digital; D. Wilson did not like the term digital, because the signal was not digital in the true sense of the word). Marler had already pointed out this distinction in his theoretical essay of 1961. Later he also found examples in the voices of several primate species. The chicken results were neither discouraging nor encouraging. Had I just worked on chickens, what would I have concluded? Auditory feedback is not necessary for avian vocalizations?

I had reasons to expect that deaf songbirds would develop abnormal songs. It was already known from the work of Thorpe in the chaffinch and also from the work in progress in the Marler laboratory with the white-crowned sparrow (Zonotrichia leucophrys) that young birds memorize tutor songs before they can sing. This fact suggested to me that auditory feedback should be indispensable for vocal reproduction of tutor song. I thought that the only way this expectation could be shown wrong would be to have a situation in which vocal memory somehow directly controls vocal motor centers of the brain. This possibility was inconceivable, because birds have to know how their song sounds to know the degree of match between the memorized and vocalized songs. I was, therefore, delighted to see the dramatic effects of deafening on the development of song in the white-crowned sparrow. All other songbirds I used also developed abnormal songs. In my thesis, I summarized my thoughts above in a model in which birds use auditory feedback to match their vocal output with a stored song template. I also reported that deafness did not affect the song of adult white-crowned sparrows. Although recent studies appear to contradict this conclusion, a systematic study of the relationship between age and the effects of deafening in zebra finches by Lombardino and Nottebohm showed that the song of birds 5 to 6 years of age remained unchanged after the operation for a much longer time than that of younger birds.

Of many memorable events in the Marler Laboratory, trips to Inverness (a coastal area north of San Francisco) were my favorites. White-crowns nest in coastal chaparrals. We would arrive there the night before and camp out on the meadows. Peter always brought the whole family including his wife Judith, their young son Christopher, and a Basenji dog. In the evening, we would talk around the campfire. Chris would babble before going to sleep. His babbles appeared to contain some elements of English to my ears, which were accustomed to the babbling of Japanese babies. Peter was very interested to hear my impression. Another story that must be told is about Fred. When Peter took us to the Chiricahua Mountains in New Mexico to collect nestlings of slate colored juncos (Junco hyemalis), Fred got lost and spent all night wandering the mountains. He was carrying a nest with young birds until they died. Fortunately, a passing ranger truck picked him up as he finally hit a road in the morning. As he came back to our campsite, he gobbled a breakfast and threw it up right away before he went to his tent to sleep half a day. Had he disappeared, would we know of the existence of the song control system today?

Postdoctoral Period

After I finished my thesis work in Berkeley, I had to go out of the country, because I had an exchange visitor visa. Instead of going back to Japan where I had no place to return to anyway, I chose to go to Germany for 2 years. This duration may sound very short by today’s standard, but many of my graduate classmates opted for teaching jobs right after getting their doctorate. At 30 years of age I was also younger than many of them who had families to feed. On my way to Germany I attended my first International Congress of Ethology in Leiden, the Netherlands (1963). Peter Marler managed to send two of his students, Keith Nelson and me, as speakers, which were more like plenary speakers of today. I could see big stars like Konrad Lorenz, Niko Tinbergen, William Thorpe, and Otto Koehler in the audience. After my talk Don Wilson congratulated me and Koehler came to me to ask if I would publish my results in “his” journal, which was then called Zeitschrift für Tierpsychologie. I was so flattered that I simply said yes and kept my promise. John Emlen of the University of Wisconsin approached me to ask if I would be interested in a position in his department. My ego was boosted again later when the German Ornithological Society invited me to speak at their annual meeting in Berlin. The eminent president of the society, Erwin Stresemann, introduced me as “Ein Wandervogel aus Japan, der Deutsch spricht.” (A German-speaking migratory bird from Japan). My talk received very favorable comments in the society journal (Journal für Ornithologie).

Although my primary purpose in Germany was to learn more about the auditory system of birds under Professor Johann Schwarzkopf, it did not work because his new laboratories in Tübingen were not ready. I was also appalled to see primitive university laboratories in postwar Germany. In sharp contrast, facilities in Max-Planck Institutes were close to the U.S. standard then. Because my time was limited, I decided to move to the MaxPlanck group led by Otto Creutzfeld in Munich to map the receptive fields of neurons in the cat’s visual cortex using intracellular recording methods. I learned a lot about the techniques from my coworker Satoru Watanabe from Japan. This work did not go far, because we could not hold neurons long enough to map their receptive fields. However, this failure was well compensated by my frequent visits to the Max-Planck Institut für Verhaltensphysiologie in Seewiesen where Konrad Lorenz was the director. I thought that the Institute was a heaven for ethologists. Lorenz told me that I should feel like a member of the institute. Their seminar series brought interesting speakers including the young Jane Goodall fresh from Africa. Her slide showing a chimpanzee inspecting a dead mouse deeply impressed Lorenz. He said, “That is human!”

There were several Seewiesen people whose work caught my attention, including Dietrich Schneider (silkworm moth pheromone), Friedlich Schutz (sexual imprinting in ducks and geese), and Jürgen Nicolai (African parasitic birds). Walter Heiligenberg who later became one of my best friends was a graduate student under Lorenz. Jürgen Aschoff, who was famous for his study of circadian rhythm, invited me to come to see his department in a nearby village, Erling-Andechs. He had a lot of Japanese art objects that his famous father (medical professor) received from some 40 Japanese medical students he trained. There was not a dull moment, because Aschoff knew how to spend time for useful purposes. He asked me to give a talk for him alone. When I used the term “template” in this talk, he proposed an equivalent German term “Sollmuster” I really liked this term, because it is so expressive. Soll means “should or must” and Muster “pattern.” I used it in the German summary of my white-crown paper in Koehler’s journal. Koehler liked the word and asked me how I got this nice term.

Once Konrad Lorenz invited me to his apartment to dine with a Japanese guest who spoke neither English nor German fluently enough to carry on conversation. I had no time to translate for them, because the guest nodded his head saying “yes” every time Konrad stopped talking. This response did not bother Konrad at all, and he kept talking. Later Konrad told me how he fooled a teacher who came to see him for the purpose of meeting a famous man. When Konrad saw a brightly colored male duck and a dull colored female duck dive alternately, he told the teacher “look how the duck changes its plumage colors.” The teacher said “Yes.” Konrad and I seldom discussed science in private conversations. One time I left a reprint of my white-crown paper on his desk in his office. Later, he thanked me and said he seldom read anything, because he did not want to change his ideas. I knew he read the paper, because he mentioned my name and work in an interview with Joseph Alsop of The New Yorker a year or so later. Either Lorenz or Alsop mixed the species when quoting my work. I wrote Alsop that I enjoyed his interesting article except for a small error in the story. Alsop wrote back “glad the error was small.” My chairman at Princeton, John Bonner, was very excited about the article and told me that he would put a copy in my file for future reference. I did not know that The New Yorker was such an influential journal.

Assistant Professorship

The U. S. consulate in Munich asked me for an explanation for returning to the United States, because my exchange visitor visa required me to return to Japan. I explained this situation to John Emlen in Madison. He might have intervened on my behalf through his connections. When I had an interview with a consular official, I explained that I really grew up as a scientist in the United States. This plea worked and I was granted a new visa to return to the United States. Also, because President Kennedy had abolished the discriminatory immigration policy against Asians, I could subsequently apply for a green card, opening my road to citizenship later. I liked the campus and surrounding areas of the University of Wisconsin. I was very sorry to miss John Emlen from the beginning of my stay there. He was not well and had to spend a large part of the year in Arizona to avoid certain maladies. I was also bit disappointed to know that I had to negotiate for set-up funds after my arrival. Apparently, offering set-up money to a new faculty member was not a norm then as it is now. While this issue remained unclear, Berkeley and Princeton approached me about a possible appointment. Because Peter Marler was moving to the Rockefeller University, his position was informally offered to me. Although Berkeley was obviously my first choice, I wondered how I would feel among my former teachers. My Japanese background came back to haunt me about the prospect of calling my former teachers by their first names. I chose Princeton in the end mostly because I was curious about good private universities in the United States.

My laboratories in Princeton were in the basement of the former psychology building where Wever and Bray discovered “cochlear microphonics” in 1930. Their hand-made wooden soundproof room was still there for my use. Wever’s group had moved to a new set of buildings outside the main campus. He and his people were very friendly and helpful to me. I learned from them about the instruments and methods for calibrating sound pressures near the eardrum of birds. Wever was conducting comparative studies of reptilian and amphibian ears. It was no accident that my first graduate student there, Geoff Manley, now an emeritus professor at the Technical University of Munich, conducted a comparative physiological study of the reptilian auditory system in my laboratories.

Although the introduction of the sonagraph revolutionized research on birdsong, little was known about what songbirds could hear. I chose neurophysiological methods to answer this question. My research strategy was simple; I collected or bought birds whose songs differed clearly in the frequency domain. I recorded single neurons in one of the cochlear nuclei and determined their threshold sensitivities. The results were clear-cut: Birds that produced high frequencies in their song had auditory neurons that responded to these frequencies. However, all birds could hear low frequencies whether their song contained these sounds or not. I found that the threshold of the most sensitive neuron in a given frequency range was close to the sensitivity measured by behavioral methods for that frequency range. Fortunately, Bob Dooling (now at University of Maryland) who was doing his thesis work under my friend Jim Mulligan from my Berkeley days had a behavioral audibility curve for canaries. I compared it with my neurophysiological results from canaries to find a very good match between the two sets of data. So, if one draws a curve connecting the most sensitive neurons in all frequency bands, one gets a curve similar to the bird’s audibility curve. This relationship has been established not only in birds but also in other species including cats.

Having learned the usefulness of single-unit recording, I addressed another issue that occupied my mind. Recall how Daniel Lehrman used Kuo’s interpretation of behavioral development in chicks to argue that we had to know more about behavioral development before birth instead of assuming the inborn nature of behavior. This line of argument spread fast to make ethologists apprehensive. For example, according to Gilbert Gottlieb, mallard duck embryos, which were prevented from vocalizing, discriminated poorly between the maternal call of their own species and that of chickens. He also reported that duck embryos responded to the maternal call a week before hatching. These studies got me interested in hearing in avian embryos. I checked if and when duck embryos began to hear in the egg. I showed that neurons of the cochlear nucleus in embryos became sensitive to low frequency sound about a week before hatching. As embryos developed further, neurons became more sensitive and responded to higher frequencies. The sensitivity and the range of frequency became adult-like two days before hatching.

I also did a behavioral study of song development in white-crowned sparrows. My aim was to test whether or not white-crowns reared in complete isolation from the egg could distinguish the song of their own species from that of multiple other species sharing the same habitat. I had this plan despite the fact that Peter Marler had shown not only the inability of nestlings under 10 days of age to learn even the song of their own species but also the ability of older nestlings to choose the song of their own species over the song of another species. This work showed that nestlings younger than 10 days of age could or did not reproduce the tutor song in adulthood. If such birds had been given a second chance of choosing between the original tutor song and a new song during the normal critical period, which song would they have chosen? The question is whether an early exposure to song affects a later choice of song. This was the rationale for raising white-crowned sparrows in complete isolation from the earliest stage of embryogenesis. I wanted to answer this question by collecting newly laid white-crown eggs and incubating them and raising chicks without exposing them to any birdsong before tutoring. This project required logistical planning. For example, I took a graduate student with me to the Inverness area where we collected a few eggs. We wrapped each of these eggs in cotton and slid it into a test tube. We connected the test tubes side by side with strings into a belt, which we wore across our belly. Our own body heat kept the eggs alive. We brought back the eggs to Princeton and next morning the student drove up to Millbrook, N.Y., where Peter put the eggs in canary’s nests. Incredibly, most eggs hatched. Despite this success, I began to think that the number of nestlings we could raise per year severely limited our progress. I also thought that we had to raise nestlings entirely artificially without the help of canaries. So, I decided to suspend the white-crown work.

Full Professorship

The sequence of events that led me to move to Caltech in 1975 seemed simple. Jack Pettigrew who was then an assistant professor at Caltech came to see me in Princeton, mainly because he wanted to see my owls, I thought. Shortly after this visit, I got an invitation to give a talk at Caltech. I was offered a full professorship, and I was quite impressed by the size and quality of space they could provide. This was in sharp contrast to Princeton where my laboratories were in the basement of one of the oldest buildings on campus. However, I had to overcome the anti–Los Angeles prejudice I acquired in Berkeley. I had to think very hard and long, before I could make up my mind. I excused myself by convincing me that even Southern California is better than New Jersey.

Caltech turned out to be a very exciting new center of neurobiology. There were already some well-known neuroscientists such as Roger Sperry, James Olds, “Kees” Wiersma, Anthonie Van Harreveld, and Felix Strumwasser. Also, Seymour Benzer was starting his famous genetic study of Drosophila behavior and neurobiology. I always admired Seymour for his courage to venture into this new field despite criticisms and for his devotion to science. He supported me from the day of my job interview in 1975 to the day of his death (November 30, 2007). We taught a course titled “Behavioral Biology” together until he “retired from teaching.” Seymour regularly attended our lunchtime meeting called “Neurolunch” in the new Beckman Laboratory of Behavioral Biology, which housed mostly new junior faculty members including John Allman, Jack Pettigrew, Jim Hudspeth, and David Van Essen. Jim Olds and I were the only full professors in the building. This concentration of youthful neurobiologists quickly became attractive to graduate and postdoctoral applicants. I had enough space to accommodate several students and postdoctoral fellows. I could pursue songbird and owl studies simultaneously at the behavioral and neural levels.

Birdsong Neurobiology

I resumed my work on the white-crowned sparrow mentioned earlier. We had to solve a few important practical problems in bird rearing. First, we had to develop a new method of holding and transporting eggs. Our electrical engineer Mike Walsh built a battery-operated portable incubator. This allowed us to stay days at collecting sites at elevations up to 8000 ft in the Sierra Nevada where mountain white-crowns breed. Also, we did not have to drive many hours nonstop to rush the eggs to the laboratory incubator. He also built an incubator, which periodically changed the orientation of eggs as in chicken egg incubators. It was generally thought that passerines could not be raised from birth on the so called “steak food”, which consisted of beef and other ingredients as originally used for raising nestling song birds by W. E. Lanyon of Cornell University. My able assistant Gene Akutagawa found that liquid from the crop of canaries raising nestlings contained something that enabled chicks (of other passerines) to consume the steak food. We raised white-crowned sparrows from birth in complete individual isolation with this method. Gene further found that the “liquid” was not necessary if he fed predigested food for human babies to newborn white-crowns. He even figured out how to raise new born zebra finches, which normally receive partially, digested seeds from their parents. The trick was to feed babies dehusked millet, which is available in health food stores. We showed that young white crowns isolated as eggs preferred the song of their own species to alien songs sung by other inhabitants in the same area. However, some of these white-crowns initially developed a copy of the white-crown tutor song and a copy of one of the alien songs. As the season progressed, these birds dropped the alien song.

In my early days at Caltech, all postdoctoral fellows wanted to work with owls, but I began advising graduate students to work in the field of songbird research, which was to become very attractive to neurobiologists because of the discovery of the brain song control system by Nottebohm and his associates in 1976. I always liked and encouraged graduate students to start new things in my laboratory. I had some adventurous students who would do anything. Larry Katz, who tragically passed away a short while ago, was the most adventurous and skillful. I was so charmed by him that I allowed him to rent a small airplane to fly to Stanford to get a new histological tracer. Next, he suggested that we introduce brain slice techniques. So, he and I drove down to the University of California in Irvine to see slice setups. On our way home, we bought a couple of components, which Larry assembled into a functioning system within a few days. He developed a powerful new method to study the anatomical organization of neural tissues. He would inject a fluorescent tracer into the target area of neurons residing some distance away. He would then make slices of the tissues containing the somata of the neurons. He discovered that neurons in the same area that project to different targets had different soma and dendritic morphologies. I told him that he could make big contributions, if he would apply these methods to the cat visual cortex, which was the darling of the time. So, Larry wrote his thesis on the cat’s visual cortex in my laboratory. It was a big loss to the birdsong field, but it promised a big future for Larry. Rich Mooney later inherited Larry’s setup to do his very original thesis work on the nature of synaptic inputs to RA, which receives signals from LMAN by N-methyl-D-asparate (NMDA) receptors and from HVC by non-NMDA glutamate receptors. His project was the first extensive in vitro and intracellular study of the song system in my laboratory and in the birdsong field. This was his idea, because I did not know what NMDA was. His work started a new NMDA cottage industry in the birdsong community.

Mark Gurney was another adventurous student. The Nottebohm laboratory and we independently discovered sexual dimorphism in the song system of the zebra finch. I had this conversation with Mark Gurney who said “These gender differences may be genetic.” I responded, “Genetics is molecular biology.” He said, “You are right.” He did the simplest experiment by injecting sex hormones into developing zebra finch eggs and newly hatched chicks. Mark found that estrogen masculinized the female song system. These birds sang when treated with testosterone in adulthood. Why estrogen instead of androgen? The brain (of rodents and birds) contains an enzyme that converts testosterone from the gonads into estrogen, which induces masculine differentiation in some areas of the brain. After Mark left, Gene Akutagawa and I took over the hormone project. Using radioactive markers to identify neurons, we showed that the neurons that migrated into RA (one of the brain song control areas) were born on the 7th day of incubation. These neurons are large and equal in size in both sexes on the first day of hatching. However, they undergo gradual atrophy and ultimately die in the female RA, whereas they grow in size in the male. We further showed that exogenous estrogen could prevent the atrophy and death of these marked neurons. There was a gradient of estrogen action; the earlier it was injected, the more effective it was in preventing cell atrophy and death. Today, estrogen is thought to be good for postmenopausal women not only for the maintenance of normal physiological conditions but also for preventing the death of their brain cells, although some experts disagree on this point. Who would have thought of a link between women’s health and songbirds?

Mark Gurney and Larry Katz were good buddies when they were exploring something new. One day they set up the necessary gear to do intracellular recordings in HVC (another brain song control area) of a zebra finch. I told them to clap hands to see if neurons responded to sound. To their great surprise, they saw responses in HVC. I showed them how to use auditory instruments and measure sound levels. At any rate, they wrote up a simple report. It was flatly rejected twice as an artifact, although it was eventually published. Another student, Jim McCasland, was recording multiunits (many neurons with a single electrode) in the HVC of behaving canaries. I told him to play canary song. He found that neurons responded much better to the song of a bird of the same breed than to the song of another breed of canary. Jim also showed that HVC neurons did not respond to playback of the bird’s own song, while the canary was singing and immediately after the end of song. These preliminary findings were exciting, because the presence of auditory responses within the vocal control pathway suggested a possible link between the auditory and vocal control systems. Former postdoctoral fellows Marc Schmidt and Teresa Nick who joined me much later continue their work on the related problems of song selectivity and gating in zebra finches.

The discovery of neurons selective for the bird’s own song was exciting, because they might represent the song template. I wanted to know what features of song these neurons were detecting. This study required analysis and synthesis of sounds. The song of zebra finches was too complex for analysis and synthesis at that time. I suggested to Dan Margoliash to undertake this project with white-crowned sparrows with simple tonal song, because Dan was the only student who could use computers. His results clearly showed the importance of both syllable structure and sequence. Separate groups of HVC neurons project to RA and X. When Allison Doupe joined my group as a postdoctoral fellow, she decided to check for auditory responses in the anterior forebrain pathway. She found selectivity for the bird’s own song (BOS) in LMAN and X. Furthermore, she showed that injections of a local anesthetic to HVC abolished auditory responses in X and RA, suggesting that these nuclei received their song-selective property from HVC.

Caltech has a graduate program called Computation and Neural System (CNS). CNS students are bright. When these students appreciate biological problems, they can do excellent research. I was telling my group in one of our luncheon gatherings that I had heard about new methods of recording from neurons in vitro called “whole cell clamp.” I told my group that it would be interesting to try the methods in vivo. No one said anything at that time, but Mike Lewicki, a former mathematics student from Carnegie Mellon, came to my office to ask if the methods would work in vivo. I said “why not?” He started right away. He read that he could count the number of bubbles to measure the tip diameter of a capillary electrode. Because this method was too crude for him, he took electrodes to a scanning electron microscope on campus. When he plotted the tip diameters measured with this method and those with the bubble method, he got a straight diagonal line. T his episode impressed me very much, because I like students who go beyond my knowledge and ability. Then, we heard that an assistant professor elsewhere was doing in vivo whole cell clamping. Mike went to see the person and came back to tell me that their methods were similar. Mike turned out to be a very good neurophysiologist. He showed that the sensitivity of HVC neurons to syllable sequences involved inhibition; for example, a neuron responded preferentially to syllable A followed by syllable B. The reverse order induced inhibition in the neuron. He developed a simple circuit model that detected specific syllable orders.

From my time in the Marler laboratory, one topic stuck in my mind. It is about designing experiments to test whether or not delayed auditory feedback affects song. I got some people interested in the subject at Caltech. I read that someone designed a theater in which the audience wore wireless headsets and listened to music. This alone is not new, but coils surrounding the theater transmitted the electrical signals. When I told Dan Margoliash about this story, he got interested and built a small version of this setup. He wore magnetic earphones and stuck his head in the coils he made. This was a short-lived project, because Dan heard no sounds! More recently another ambitious student took this topic seriously and got excellent results by different methods. Anthony Leonardo, another CNS student from Carnegie Mellon, was not only smart but also technically skilled. He built a computerbased system to detect song and play back its delayed versions. Although birds heard natural and delayed feedback, they gradually changed the probability of syllable sequences and also syllable structure in some cases. Remarkably, the original song gradually recovered after normal feedback was restored. One summer, he went to the Bell Telephone Laboratory to work with Michale Fee in designing and testing the now well-known microdrive for zebra finches. He assembled two microdrives for his use in our laboratory. He quickly figured out how to place electrodes in LMAN. Recording single neurons in the LMAN of singing birds would answer the most important question about its role in the feedback control of song. Anthony did not find any effects of delayed feedback on the firing patterns of LMAN neurons. Despite these advances the control of song by auditory feedback remains one of the most important issues in birdsong research.

Owl Research

I became interested in barn owls when I heard Roger Payne present his thesis work on prey capture by barn owls in the 1963 International Congress of Ethology in Leiden, the Netherlands. My associations with barn owls started shortly after I moved to Princeton in 1966. A nice university employee who was curious about my research perhaps spread the word that I was interested in barn owls. Before long a local bird watcher brought three nestling barn owls to my office. Another person made an arrangement for me to obtain mice for free from a big pharmaceutical company nearby. As soon as the owls could fly, I moved them to a large room in an old house on campus. The owls grew fast, but one of them died perhaps because of fighting. I installed a large nest box for the remaining two. One day the graduate student who was interested in studying the owls found one of the owls incubating eggs. The owl pair reared one set of young twice a year in spite of seasonal changes in day length and temperature. It seemed that the breeding of the owls depended only on the availability of mice. I also found that male and female owls could be distinguished by the coloration of their facial and breast feathers, white males versus brownish females. This finding made it possible to set up breeding pairs, making all future laboratory studies of barn owls feasible. I advised several Princeton seniors to do their thesis projects with owls. Hand-reared owls became so tame that the students could use behavioral criteria for memorization and discrimination of sound signals. Anything that the students did or found was new and worthy of publication.

I shipped 21 home-bred owls from Princeton to Caltech a day or so before my own departure for the West. Jack Pettigrew and I started to work on the visual system of the owl immediately after my arrival, partly because my main soundproof chamber was not ready yet. He already had a computercontrolled system of visual stimulation and data collection. We studied the response properties of neurons in a forebrain area called the visual Wulst mainly because the area was readily accessible without major surgery. We did find several interesting response properties. Jack kept telling me that the Wulst cells were just like those in the visual cortex of the cat, for example, with respect to their sensitivity to stimulus orientation, binocular disparity, and direction of movement. He told me that a blind folded physiologist would not be able to tell whether he is recording neurons from the cat visual cortex or from the owl visual Wulst. At any rate, we published a couple of papers on this subject. My big sound chamber was completed after Jack and I worked together in his laboratories for about a year.

Jack asked me what I was going to do. My original intent was to continue to analyze sound localization behavior by owls in a much more acoustically better defined environment than anything I had used before. Well, this idea ceased to occupy me after Jack and I had studied the visual Wulst cells. I naively thought that central auditory neurons might have spatial receptive fields like the visual cells. I also thought that these auditory cells might form a map of auditory space. There had been some reports of auditory neurons with spatial receptive fields, but systematic approaches to this question seemed lacking. Jack was more than enthusiastic about my ideas. He asked the legendary Herb Adams of Caltech to design and build devices and instruments necessary for this project. I do not know to this day who paid the bill, because I did not have any seed money or grant for this project. We wanted to move a small loudspeaker around an owl’s head at a constant distance in the horizontal and vertical directions. Herb built a light semicircular rail along which the speaker could travel. Herb’s “hoop” could be moved up and down either manually or electrically so that we could place the speaker anywhere around the owl’s head.

My first postdoctoral fellow Eric Knudsen arrived around this time. Using this system, he and I quickly found auditory neurons that responded only when the speaker was in a particular area in space, that is, auditory receptive field. Although this finding was exciting, we did not find anything like a map. I did not realize that an auditory map was not expected, because unlike the visual system in which the sensory periphery, the retina, maps the visual field, the cochlea maps only sound frequencies. Because, as I pointed out earlier, auditory spatial receptive fields as such were already reported if sporadically, the value of our initial findings was limited. When Eric and I discussed what to do next, we agreed that we shift our focus to the midbrain auditory area. An exploration of the brain or earth without a map is precarious; we have to be lucky. We also could not afford to kill an owl for making a brain atlas, although we should have done it in retrospect. I cut a frozen owl brain along its midline with a band saw. Eric who had previously studied the midbrain auditory area of catfish could see the homologous area in the owl’s brain. Somehow his measurements of depth and so forth on this specimen were useful enough to target the midbrain area.

We were lucky to insert an electrode into a midbrain area packed with auditory neurons with small spatial receptive fields. We named them “space-specific neurons.” However, we could not go back to the same area without better landmarks on the skull or brain. When I was in Munich, I learned how to remove brain tissue by suction. I could expose the optic lobe of the owl by removing the overlying forebrain. Using surface blood vessels as landmarks, we probed the midbrain as systematically as we could. However, often the brain would start pulsating as I had seen in the cat. Also, any small damage to the surface of the exposed area would cause swelling, making it impossible to sample neurons at a fixed interval. The main problem in finding a map was the small number of neurons that we could sample during one penetration with a single electrode. Our electrodes were much too hard to make and too fragile. One day we were lucky enough to record some 16 neurons with the same electrode in the area that we subsequently named the “external nucleus” of the inferior colliculus. The loci and the sequences in which we encountered these neurons clearly indicated a map of auditory space as we depicted in the map we published. We published our papers describing auditory receptive fields and map in Science. The first of the papers was chosen as the best paper to appear in Science in 1977, and each of us received a medal from the American Association for the Advancement of Science (AAAS). Eric, Jack, and I were overjoyed, because it was our first award for writing a scientific paper.

Things around us started to change when laboratory computers appeared on the horizon. Jack’s postdoctoral fellow Gary Blasdel set up and programmed computers for his laboratories. When Gary took part in one of our behavioral experiments, he programmed our first computer a PDP 11. After Eric’s ascent to assistant professorship at Stanford, I was lucky enough to get a new postdoctoral fellow, Andy Moiseff, who could not only program computers but also make digital instruments for auditory physiology. The subsequent arrival of computer-savvy graduate students Jamie Mazer, Larry Procter, Björn Christianson, and our first professional programmer, Chris Malek, modernized our stimulus delivery and data collection systems. Knowing the response properties of space-specific neurons, I wanted to investigate how their stimulus selectivity is created in the pathways leading to the site of the auditory space map. Our first step was to sample neurons in all brain areas leading from the cochlear nuclei (first brain auditory station) to the external nucleus of the inferior colliculus. We (including Moiseff, Sullivan, Terry Takahashi) obtained anatomical and physiological evidence suggesting the presence of two separate pathways leading to the external nucleus. One pathway deals with “time” leading to the creation of neuronal selectivity for the interaural time difference (ITD), and the other pathway deals with sound “level or intensity” leading to the creation of neuronal selectivity for the interaural intensity difference (IID). These discoveries led to studies of the mechanisms that give rise to the ITD and IID selectivity.

We placed much emphasis on the most important part of the time processing pathway. This part consists of axonal delay lines provided by the axons of neurons in magnocellular nucleus (the first brain auditory station) and coincidence detectors provided by neurons of nucleus laminaris (the second station). The laminaris turned out to be a very difficult site to investigate, because holding single neurons was hard. Using evoked potentials, Sullivan and I observed a map of ITDs in each frequency band in the nucleus laminaris. Later, Catherine Carr and I not only managed to record single laminaris neurons to confirm the existence of ITD maps but also figured out the neuronal circuits underlying the coding of ITD. This set of circuits resembles the famous model proposed by Lloyd Jeffress in 1948. My group has published papers to show how our findings are consistent with this model. Our exploratory study of the IID processing pathway identified the first binaural station called VLVp in the anterior part of the hindbrain. Manley, Köppl, and later Adolphs found how this station encodes IID. VLVp neurons receive excitatory input from the contralateral nucleus angularis (first brain station of the intensity processing pathway) and inhibitory input from the contralateral VLVp, and the degree of inhibition varies systematically to form a map of IID’s.

The space-specific neurons require combinations of ITD and IID. This fact indicates that the time and intensity pathways converge on single neurons. The convergence of the two pathways occurs first in each frequency band in a midbrain area called the “lateral shell” of the central nucleus of the inferior colliculus. Different frequency bands converge on each single neuron in the next area called “external nucleus” where the map of auditory space resides. Next I wanted to know how the requirement for the ITD and IID combination is created. I advised Jose Luis Peña that he might try intracellular recording of cells in the external nucleus to see how postsynaptic potentials change with combinations of ITD and IID. When I casually showed the data to Partha P. Mitra, a physicist, he said that multiplication of postsynaptic potentials for ITD and IID would account for the combination sensitivity. We proved him right by carrying out mathematical analyses with the help of Fabrizio Gabiani who was a postdoctoral fellow in the laboratory of my colleague Gilles Laurent.

The results of all these efforts eventually led to the formulation of an outline of signal processing in which major events leading to the genesis of the stimulus selectivity of space-specific neurons were identified. I am proud of this accomplishment, because few other vertebrate sensory systems are understood at this level. A notable exception is the work of Walter Heiligenberg and his associates. Walter had come to the laboratory of Ted Bullock in San Diego a couple of years before my move to Pasadena. I saw Walter and his wife Zsuzsa often at their home in Del Mar. Walter was killed in a plane accident, and Zsuzsa died of cancer. I still think of them all the time. The jamming avoidance of electric fish Eigenmannia was the subject of his research. This species emits low frequency sinusoidal electrical signals for navigation in muddy waters. The fish raises or lowers its signal frequency in response to frequency differences between it and other individuals in the vicinity. This response is called the “Jamming Avoidance Response.” Unlike our owl project, Walter went from the peripheral sensory organs to high-order areas in the brain to figure out how the fish determines which way it should change its frequency. The decision to lower or raise the fish’s own frequency involves separate time and amplitude pathways, and their convergence in the midbrain as in the owl. Just as the owl’s space map area, the highest area in the fish contains single neurons that respond selectively to the sign of frequency differences between the two fish. I have published essays comparing the owl and electric fish algorithms. This experience has convinced me that there should be some universal rules by which complex sensory signals are processed by the brain.

Echolocation in Birds

Jack Pettigrew and I worked very hard in the laboratory, but we also needed time off to move from indoor to outdoor adventures. In late November 1976, I organized an expedition to Colombia, South America to study oilbirds (Steatornis caripensis), which use echo-location for obstacle avoidance and nest site recognition in deep and completely dark caves. I obtained a grant from the National Geographic Society for the Columbian expedition and recruited experts on avian brain, (Sven Ebbesson, Harvey Karten), echolocation (Nobuo Suga), and Jack Pettigrew. Rodolfo Llinás who is originally from Bogota helped us with local arrangements including establishing contact with the U. S. Embassy to have someone who could help us with customs clearance. However, Jack and I caused a big problem by sending a couple of boxes containing instruments by a separate flight. When we told the Embassy Liaison that those boxes were coming in another flight, he said “oh no,” meaning that he would not be able to arrange their safe passage through the customs. While we were waiting for the resolution of the problem, we assembled whatever we had in a hospital laboratory, which Rodolfo secured for us. One day Jack and I rented a car to go to one of the oilbirds caves. We were really impressed by their habitat and behavior.

A few days after our trip to the cave, the U.S. Embassy wanted to give us some information about Columbia. Because most members of my expedition did not want to bother with this invitation, Nobuo Suga and I, who were not even U.S. citizens, went to the Embassy. We were shown a large map of the country in which many places were marked with some symbols. The attending official told us that those markings indicated the sites of guerrilla activities by various groups. One of the areas was close to the cave Jack and I visited! On the whole, we lost too much time to do any serious experiments in the laboratory. As Jack and I were walking to the airport terminal where we were to board a plane for Los Angeles, an official approached and took Jack away, because Jack was conspicuous with his beard, long hair, and short pants. Jack returned after a few minutes. We wrote off Columbia after these experiences.

I saved enough grant money to stage two more expeditions to continue the oilbird project. In November, 1977 Jack and I went to Trinidad after I had carefully arranged our safe passage through the customs and a permit to catch oilbirds. I also learned about the well known oilbird cave and the old research station (William Beebe Tropical Research Station) where we could set up our neurophysiological laboratory. The research subject was vision this time, partly because we were curious to know whether oilbirds’ brain visual areas contain neuron types that respond to the same stimuli to which the owl’s Wulst neurons respond. This topic was also relevant to the controversy that was going on between Hubel and Wiesel on one hand and Blakemore, Pettigrew, and Barlow on the other with regard to the innateness of neuronal responses to stimulus orientation and the direction of movement. Jack and I went to the deepest and totally dark part of the cave to collect oilbird chicks from their nests. We carried them in a completely dark box back to the laboratory. We recorded neurons in their visual Wulst as we had done before with owls. We used the types of stimuli that were used for the study of the cat’s cortical neurons. Jack was amazed to find neuron types that responded to stimuli that also drove those of the cat’s visual cortex. He had to admit that these types of neurons do not need any visual experience to develop their preference for orientation and the direction of movement. He said “It’s innate,” the word he had never uttered before.

Pleased with the outcome of the vision research, I staged another expedition to Trinidad in May 1978, this time with Eric Knudsen to study hearing in oilbirds. Eric and I did field experiments in which we put up a two dimensional array of discs of different diameters across the flight path in the cave to see the smallest disc they could detect by echolocation. We used an infrared search light and an infrared telescope to watch the birds. We also recorded auditory responses in the forebrain auditory area and the cochlea of anesthetized birds to determine their auditory threshold for different frequencies. We learned that the oilbird’s ear was most sensitive to 2 kHz and that its highest audible frequency is no higher than 8 kHz, although the clicks they emit during echolocation contain frequencies as high as 15 kHz.

There is another bird species called “cave swiftlet” (Collocalia fuciphaga) that uses echolocation for navigation in caves. In September 1980, I went to Chillagoe, Australia with a group of bat researchers including Don Griffin, Roderick Suthers, Jim Simmons, and local participants Jack Pettigrew and Roger Cole. I was much impressed to see Rod Suthers record tracheal air flows in a tethered swiftlet. I told him that he could use the same method in singing birds, and he later did just that to discover many interesting facts about song production. Chillagoe is an old mining town in northern Queensland. In Southeastern Asia, cave swiftlets provide nests for Chinese bird nest soup. Fortunately, their nests are protected in Australia. These birds are tiny compared with the crow-sized oilbirds. We saw many of them flying over their nesting caves in the day time unlike oilbirds that come out of their caves only at night. They begin to emit echolocation calls when they approach the entrance of their home caves. Three of us set up our gear in the same motel room where we slept. The temporary laboratory was better equipped than my home laboratories. We used neurophysiological methods to determine their auditory threshold. We showed for the first time that the frequency range of hearing in cave swiftlets did not include ultrasound frequencies.

My Other Activities

Academic High Society

My introduction to academic high society began in 1975 when I was invited to join a discussion group called the Neuroscience Research Program (NRP) led by Francis O. “Frank” Schmitt of MIT. This group included not only neuroscientists but also people from other fields such as Manfred Eigen. I did not know why a relatively young (42) person like me was invited to a group of famous senior scientists like Walle Nauta, Ted Bullock, David Hubel, Seymour Kety, and Vernon Mountcastle. The members met twice a year in Boston. The NRP organized other meetings and symposia in addition. I met practically all leading U.S. and foreign neuroscientists at the NRP. In fact, many of them are contributing to the present volume! Individual encounters seemed to remove the potential barriers due to age and status. I learned a lot more from private conversations with my senior colleagues than from formal lectures. As Frank was slowing down, the NRP moved to the Rockefeller University and thence to San Diego with Gerald Edelman as the new director.

Creation of a Scientific Society

In 1981, I attended a conference on vertebrate neuroethology in Kassel, Germany. Ted Bullock, who was one of my heroes, rounded up several people during this meeting to discuss the possibility of organizing an international society for neuroethology including vertebrate and invertebrates researchers. There was a division between these two groups of neuroethologists. For example, the late Graham Hoyle ranked invertebrate researchers like himself in “A” class and vertebrate researchers like me in “B” class. His criterion for the A class was the cellular level of analysis with identifiable neurons, which few vertebrate researchers could achieve. Ted who worked on both invertebrates and vertebrates emphasized the need to bring the two groups together. He asked me to contact potential members around the world. It took me about 2 years to collect enough names, because I was writing letters and waiting for replies. I still have a vast number of letters I sent and received during the above period. After I completed this phase of organization, I suggested to Ted the possibility of organizing the first international congress of neuroetholgy in Tokyo, because my good friend Kiyoshi Aoki of Sophia University in Tokyo offered to raise funds for the congress. Aoki graduated from Hokkaido University a couple of years after me. He told me that the rich father of one of his graduate students would support the congress, if funds from government sources were unavailable. Aoki singlehandedly raised funds and took care of all logistic aspects of the congress. Ted and I made a list of potential plenary speakers including Edward Evarts, Eric Kandel, Seymour Kety, and other big names, even though some of them were not bona fide neuroethologists, because they were not studying the neural mechanisms of natural behaviors. When I asked Ted how we should make the final list of speakers, he said that we the committee of two could decide by voting! Thus, I learned a new form of democracy, and the first congress was held in 1986. Aoki later told me that Japanese participants were much impressed by the final list of speakers. They wondered how a young chap like Aoki could attract such foreign luminaries, reflecting the Japanese hierarchical system I mentioned before. I succeeded Ted as president to consolidate the society and prepare for the next congress in 1989 in Berlin. The eighth congress was held in Vancouver this past summer (2007). I am pleased to see the fruit of our early efforts.

Prizes

The number of monetary prizes given to scientists seems to have been increasing in recent years especially in United States. It is refreshing to know that people of means support arts and sciences. Prizes always took me by surprise, that is, I had neither worked toward them nor expected them. Thus, I do not know if prizes motivate scientists to work harder and more creatively. Nevertheless, I admit that recognition by respected members of my field is important and encouraging to me. I would like to record here my most extraordinary experience in connection with the receipt of the 1990 International Prize for Biology, which was established in 1985 in honor of the Showa emperor of Japan who was a biologist. As I was being taxied from my hotel to the Japan Academy building in Tokyo, I saw empty streets with policemen standing at various corners, because the streets were on the route that the imperial limousine was taking to the Academy. I could not believe that I caused such massive public measures, even if they were done for the imperial procession. As soon as I arrived at the Academy, I was given a long minute-by-minute list of events that would occur during the day. The quality of the paper used for this list was something I had never seen before. It looked like a modern version of an ancient scroll. The first item was a private audience with the emperor (son of the Showa emperor) and the empress in a small room. The imperial couple came in silently without any guards or servants. We greeted and exchanged a few words. She asked me about my mother. After this brief encounter, we separately went to a large auditorium where I received the prize. On the podium, the imperial couple sat in the middle surrounded by some dignitaries such as the minister of education and the president of the academy. The audience included many university presidents, representatives from foreign embassies, my friends (by invitation), and press people. I walked to the assigned post in front of the imperial couple and faced the audience to deliver a short speech in English. I felt a bit uncomfortable to turn my back toward the imperial couple, because this was not allowed in the old days when the emperor was God. After the prize ceremony, the guests lined up behind me to greet the imperial couple. I deeply bowed in front of the couple, and they bowed lightly according to the Japanese custom, while my friend Rüdiger Wehner (University of Zürich) coming behind me shook hands with the couple. Moreover, he told me that he chatted with the empress about her youthful experience in Switzerland. When Seymour Benzer received the prize some year later, his boys hugged the empress! If I had done that, the scene would have been in all newspapers the following day.

The day after the event, someone, perhaps a reporter, phoned me to ask how I could accept the prize created in honor of the Showa emperor, a war criminal. I told him that I was selected not by the imperial department but by a committee of distinguished scientists. I know this because I served on it a few years later. A similar protest was also staged at Kyoto University where there was a symposium in my honor following the Tokyo ceremony. I saw a few placards denouncing the Showa emperor but not me personally. When this emperor came to visit Kyoto shortly after the war ended, students from Kyoto University mobbed the imperial limousine chanting “war criminal.” This incident was a front page sensation in all newspapers, because something like this had never happened before. A middle-aged teacher at our high school asked how many of us agreed with the rioters. I was the only pupil who supported the demonstration. The teacher asked “only one?” and chastised my conservative classmates. Although the emperor may have been deceived by his military advisors, the students wanted to remind the people of his possible culpability.

A few years later when I went to Japan, the imperial couple invited me to their temporary palace for a dinner. Fortunately, this time I was not alone but with my friend Kiyoshi Aoki who was familiar with the imperial court. His contact at the palace had asked him what I would prefer to eat, Western or Japanese. I opted for Japanese. Four of us dined in a little cozy room, and the food was Kaiseki, which usually consists of a sequence of small dishes. We were served many small dishes at once, spoiling the most important aspect of savoring Kaiseki. The imperial couple did not say a word about the dinner, making me wonder if they liked the food. Although they asked me questions slowly I could not find an appropriate moment to ask them a question. I do not think that they intentionally avoided questions from me. Perhaps they were trained to develop this skill by necessity. I would have asked how they liked their way of life. When a servant (I did not know his exact title) came to say “Time’s up,” the emperor asked for “10 more minutes?” The servant came back exactly after 10 minutes. I could not help feeling sorry for the couple, because they were not as free as I was. I liked them as individuals, particularly the charming empress who came from a rich commoner family. When newspaper articles about her mental state began to appear, I sent her a reel of tape containing the song of European nightingales, because she had expressed her interest in them in our previous encounter. She sent me a beautifully handwritten letter, telling me how much she appreciated them. On another occasion, I gave a private lecture on birdsong for their daughter who was interested in birds.

My Hobbies

I have been lucky, because I did not have to go far from my hobby to my scientific subjects. Playing with animals was my main hobby in my childhood. I now have only dogs. I have trained dogs to do tasks like tracking and searching. These tasks are easy from the trainer’s point of view. When I started to train Border Collies for sheep herding a few years ago, I began to realize that my previous experience was not useful for this “sport.” Most dog trainers agree that sheep herding is the hardest dog sport, although it is not a sport for real sheep herders. My explanation for the difficulty is the interaction of three different species. Border Collies are selectively bred for sheep herding by enhancing obedience and certain aspects of predatory behavior such as circling prey. This means that the dog has his own way of dealing with sheep, and the shepherd has to shape these responses to his advantage. However, sheep also have instinctive responses to dogs. If shepherds do not know these responses, they cannot herd sheep with dogs. So, I now have to train my dogs to work not for me but with me. I like this, because I have to think hard and keep moving, good antidotes against physical and mental aging!

Acknowledgments

I would not be in this volume without the indefatigable efforts of my parents to help me get out of the unkind world in which they were destined to live. I thank the tax payers of Japan, Germany, and United States for their support of my training and research through fellowships and grants administered by respective governmental agencies. I am also grateful to individuals and groups that have given me prizes and grants for my work. I thank Jack Pettigrew whose encouragement and participation in the initial phase of the owl project was the key to my decision to look for auditory spatial receptive fields and map. My special thanks go to Peter Marler who played the most pivotal role in my development as a scientist.

I list below all the people who participated in my research projects because many of them are not mentioned in my research accounts above, which emphasize only the main stream of the events. I take this opportunity to thank all for their contributions.

Former Graduate Students

Princeton era (1967–1975)

Manley, Geoffry A. (Professor Emeritus, Technical University of Munich, Germany)

Caltech era (1975– )

Owl Projects

Adolphs, Ralph (Professor, Humanities Division, Caltech)

Christianson, Björn (Postdoctoral fellow, University CollegeLondon)

Egnor, Roian (Janelia Farm)

Mazer, James A. (Assistant Professor, Yale University)

Proctor, Larry (Amgen)

Birdsong Projects

Gahr, Manfred (Dept. Director, Max-Planck Institut für Ornithologie, Germany)

Gurney, Mark (PV, deCode-Genetics, Inc. Iceland)

†Katz, Lawrence (Professor, Duke University)

Köppl, Christine (Research Associate, University of Sydney)

Leonardo, Anthony (Group leader, Janelia Farm).

Lewicki, Michael (Associate Professor, Carnegie Mellon University)

Margoliash, Daniel (Professor, University of Chicago).

McCasland, James S. (Professor, Upstate Medical University)

Mooney, Richard (Professor, Duke University)

† deceased

Former Postdoctoral Fellows

Owl Projects

Albeck, Yuda (Israel)

Carr, Catherine E. (Professor, University of Maryland)

Fujita, Ichiro (Professor, Osaka University)

Funabiki, Kazuo (Research associate, Osaka Biosciences Institute)

Knudsen, Eric I. (Professor, Stanford University)

Moiseff, Andrew (Professor, University of Connecticut)

Mori, Koichi (Section chief, NRCD, Japan)

Peňa, Jose Luis (Assistant Professor, Albert Einstein Collage of Medicine)

Saberi, Kourosh (Associate Professor, UC Irvine)

Shanbhug, Sharad (Postdoctoral fellow, Albert Einstein Collage of Medicine)

Sullivan, Ted (Private enterprise)

Takahashi, Terry (Professor, University of Oregon)

Viete, Svenja (Veterinary practice, Los Angeles).

*Volman, Susan (Program Director, NIH/NIDA)

Wagner, Hermann (Professor, University of Aachen, Germany)

* worked on owl and songbird

Birdsong Projects

Doupe, Aillson (Professor, University of California, San Francisco)

Funabiki, Yasuko (Research associate, Kyoto University)

Nick, Teresa (Assistant Professor, University of Minnesota)

Leppelsack, Hans (retired Professor, Technical University of Munich)

Perkel, David (Professor, University of Washington)

Schmidt, Marc (Associate Professor, University of Pennsyl-vania)

Striedter, Georg (Associate Professor, University of California, Irvine)

Vu, Eric (Research Associate, Barrow Neurological Institute)

Watanabe, Dai (Professor, Kyoto University)

Selected Bibliography

Akutagawa E, Konishi M. Connections of thalamic modulatory centers to the vocal control system of the zebra finch. Proc Nat Acad Sci USA 2005;102: 14086–14091.

Albeck Y, Konishi M. Reponses of neurons in the owl’s time processing pathway to partially binaurally correlated signals. J Neurophysiol 1995;74:1689–1700.

Bentley D, Konishi M. Neural control of behavior. Ann Rev Neurosci1978;1:35–39.

Carr CE, Konishi M. Axonal delay lines for time measurement in the owl’s brain-stem. Proc Nat Acad Sci USA 1988;85:8311–8315.

Carr CE, Konishi M. A circuit for detection of interaural time differences in the brain stem of the barn owl. J Neurosci 1990;10:3227–3246.

Changeux J-P, Konishi M. The neural and molecular bases of learning. Life Sciences Research Report 38, Dahlem Konferenzen. 1987.

Doupe AJ, Konishi M. Song-selective auditory circuits in the vocal control system of the zebra finch. Proc Natl Acad Sci USA 1991;88:11339–11343.

Fischer BJ, Peña JL, Konishi M. Emergence of multiplicative auditory responses in the midbrain of the barn owl. J Neurophysiol 2007;98:1181–1193.

Fujita I, Konishi M. The role of GABAergic inhibition in processing of interaural time difference in the owl’s auditory system. J Neurosci 1991;11:722–739.

Funabiki Y, Konishi M. Long memory in song learning by zebra finches. J Neurosci 2003;23:6928–6935.

Gurney M, Konishi M. Hormone induced sexual differentiation of brain and behavior in zebra finches. Science 1980;208:1380–1383.

Kenuk AS, Konishi M. Discrimination of noise spectra by memory in the barn owl. J Comp Physiol 1975;97:55–58.

Knudsen E, Konishi M. Center-surround organization of auditory receptive fields. Science 1978;202:778–780.

Knudsen E, Konishi M. A neural map of auditory space in the owl. Science 1978;200:795–797.

Knudsen E, Konishi M. Space and frequency are represented separately in auditory midbrain of the owl. J Neurophysiol 1978;41:870–884.

Knudsen E, Konishi M. Mechanisms of sound localization in the barn owl (Tyto alba). J Comp Physiol 1979;133:13–21.

Knudsen EI, Konishi M. Monaural occlusion shifts receptive-field locations of auditory midbrain units in the owl. J Neurophysiol 1980;44:687–695.

Knudsen E, Konishi M, Blasdel G. Sound localization by the barn owl (Tyto alba) measured with the search coil technique. J Comp Physiol 1979;133:1–11.

Knudsen E, Konishi M, Pettigrew JD. Receptive fields of auditory neurons in the owl. Science 1977;198:1278–1280.

Konishi M. The role of auditory feedback in the vocal behavior of the domestic fowl. Z Tierpsychol 1963;20:349–367.

Konishi M. Effects of deafening on song development in two species of Juncos. Condor 1964;66:85–102.

Konishi M. Song variation in a population of Oregon Juncos. Condor 1964;66: 423–426.

Konishi M. Effects of deafening on song development in American robins and blackheaded grosbeaks. Z Tierpsychol 1965;22:584–599.

Konishi M. The role of auditory feedback in the control of vocalization in the whitecrowned sparrow. Z Tierpsychol 1965;22:770–783.

Konishi M. Hearing, single-unit analysis, and vocalizations in songbirds. Science 1969;166:1178–1181.

Konishi M. Time resolution by single auditory neurons in birds. Nature 1969;222: 566–567.

Konishi M. Comparative neurophysiological studies of hearing and vocalization in songbirds. Z Vergl Physiol 1970;66:257–272.

Konishi M. Ethology and neurobiology. Amer Sci 1971;59:56–63.

Konishi M. Development of auditory neuronal responses in avian embryos. Proc Nat Acad Sci USA 1973;70:1795–1798.

Konishi M. How the owl tracks its prey. Amer Sci 1973;61:414–424.

Konishi M. Locatable and nonlocatable acoustic signals for barn owls. Amer Nat 1973;107:775–785.

Konishi M. Hearing and vocalization in songbirds. In Schein MW, Goodman IJ, eds. Birds, brain and behavior. New York: Academic Press, 1974;77–86.

Konishi M. In search of ethological principles in birdsong [in Japanese]. Shizen 1974;29:28–37.

Konishi M. Auditory environment and vocal development in birds. In Walk RD, Pick HL, eds. Perception and experience. New York: Plenum, 1978;105–118.

Konishi M. Ethological aspects of auditory pattern recognition. In Held R, Leibowitz HW, Teuber H-L, eds. Handbook of sensory physiology. Berlin, Heidelberg: Springer-Verlag, 1978;289–309.

Konishi M. Neuroethology of acoustic prey localization in the barn owl. In Huber F, Markl H, eds. Neuroethology and behavioral physiology, Berlin, Heidelberg: Springer-Verlag, 1983;282–309.

Konishi M. Spatial receptive fields in the auditory system. In Bolis L, Keynes RE, Maddnell SHP, eds. Comparative physiology of sensory systems. Cambridge, UK: Cambridge University Press, 1984;103–113.

Konishi M., Birdsong: From, & behavior to neuron. Ann Rev Neurosci 1985;8:125–170.

Konishi M. Centrally synthesized maps of sensory space. Trends Neurosci 1986;9: 163–168.

Konishi M. How auditory space is encoded in the owl’s brain. In Cohen, MJ, Strumwasser F, eds. Modes of communication in the nervous system. New York: John Wiley & Sons, 1986;335–349.

Konishi M. Birdsong for neurobiologists. Neuron 1989;3:541–549.

Konishi M. Brain mechanisms of sound localization in the owl [in Japanese]. Kagaku 1990;60:18–28.

Konishi M. Deciphering the brain’s codes. Neural Comput 1991;3:1–18.

Konishi M. Similar algorithms in different sensory systems and animals. Cold Spring Harbor Symp Quant Biol 1991;55:575–584.

Konsihi M. The neural algorithm for sound localization in the owl. The Harvey Lectures, Series 1992;86:47–64.

Konsihi M. Listening with two ears. Sci Amer 1993;268:66–73.

Konsihi M. Neuroethology of sound localization in the owl. J Comp Physiol A 1993;173:3–7.

Konsihi M. Similar neural algorithms in owls and electric fish. J Comp Physiol A 1993;173:700–702.

Konsihi M. An outline of recent advances in birdsong neurobiology. Brain Behav Evol 1994;44:279–285.

Konishi M. Pattern generation in birdsong. Curr Opin Neurobiol 1994;4:827–831.

Konsihi M. Why do birds sing. A book [in Japanese]. Tokyo: Iwanami Shoten, 1994.

Konsihi M. Neural mechanisms of auditory image formation. In Gazzaniga MS, ed. The cognitive neurosciences. Cambridge, MA: MIT Press, 1995;269–277.

Konishi M. Study of sound localization by owls and its relevance to humans. Comp Biochem Physiol A 2000;126:459–469.

Konishi M. Coding of auditory space. Annu Rev Neurosci 2003;26:31–55.

Konishi M. Synthesis of neural representation of auditory space in barn owls. In Berlin CI, Weyand TG, eds. The brain and sensory plasticity: Language acquisition and hearing. Clifton Park, NY: Thomson Delmar Learning, 2003;1–24.

Konishi M. The role of auditory feedback in birdsong. Ann NY Acad Sci 2004;1016: 463–476.

Konishi M, Akutagawa E. Neuronal growth, atrophy and death in a sexually dimorphic song nucleus in the zebra finch. Nature 1985;315:145–147.

Konishi M, Akutagawa, E. Hormonal control of cell death in a sexually dimorphic song nucleus in the zebra finch. Ciba Foundation Symposium 126, Selective Neuronal Death, 1986;126:170–185.

Konishi M, Akutagawa G. Growth and atrophy of neurons labeled at their birth in a song nucleus of the zebra finch. Proc Natl Acad Sci USA 1990;87:3538–3541.

Konishi M, Emlen ST, Ricklefs R, Wingfield JC. Contributions of bird studies to biology. Science 1989;249:465–492.

Konishi M, Knudsen E. The oilbird: hearing and echolocation. Science 1979;204: 425–427.

Konishi M, Nottebohm F. Experimental studies in the ontogeny of avian vocalization. In Hinde RA, ed. Bird vocalizations. Cambridge, England: Cambridge University Press, 1969;29–48.

Konishi M, Takahashi, T, Wagner, H, Sullivan, WE, Carr, CE. Neurophysiological and anatomical substrates of sound localization in the owl. In Edelman G, Gall WE, Cowan WM, eds. Auditory function: Neurobiological bases of hearing. New York: John Wiley & Sons, 1988;721–745.

Kroodsma D, Konishi M. A suboscine bird (eastern phoebe, Sayornis phoebe) develops normal song without auditory feedback. Anim Behav 1991;42: 477–487.

Leonardo A, Konishi M. Decrystallization of adult song by perturbation of auditory feedback. Nature 1999;399:466–470.

Manley GA, Koeppl, C, Konishi M. A neural map of interaural intensity differences in the brain stem of the barn owl. J Neurosci 1988;8:2665–2676.

McCasland JS, Konishi M. Interaction between auditory and motor activities in an avian song control nucleus. Proc Natl Acad Sci USA 1981;78:7815–7819.

Moiseff A, Konishi M. Neuronal and behavioral sensitivity to binaural time differences in the owl. J Neurosci 1981;1:40–48.

Moiseff A, Konishi M (1983) Binaural characteristics of units in the owl’s brainstem auditory pathway: Precursors of restricted spatial receptive fields. J. Neurosci. 3: 2553–2562.

Mooney R, Konishi M. Two distinct inputs to an avian song nucleus activate different glutamate receptor subtypes on individual neurons. Proc Natl Acad Sci USA 1991;88:4075–4079.

Nick T, Konishi M. Dynamic control of auditory activity during sleep: Correlation between song response and EEG. Proc Natl Acad Sci USA 2001;98: 14012–14016.

Nick T, Konishi M. Neural auditory selectivity develops in parallel with song. J Neurobiol 2004;62:469–481.

Nick T, Konishi M. Neural song preference during vocal leaning in the zebra finch depends on age and state. J Neurobiol 2004;62:231–242.

Nick T, Konishi M 2004 Neural auditory selectivity develops in parallel with song. J. Neurobiol. 62: 469–481.

Peña JL, Konishi M (2000) Cellular mechanisms for resolving phase ambiguity in the owl’s inferior colliculus. Proc. Natl. Acad. Sci. USA 97: 11787–11792.

Peña JL, Konishi M. Auditory spatial receptive fields created by multiplication. Science 2001;292:249–252.

Peña JL, Konishi M. From postsynaptic potentials to spikes in the genesis of auditory spatial receptive fields. J Neurosci 2002;22:5652–5658.

Peña JL, Konishi M. Robustness of multiplicative processes in auditory spatial tuning. J Neurosci 2004;24:8907–8910.

Peña JL, Viete S, Albeck Y, Konishi M. Tolerance to sound intensity of binaural coincidence detection in the nucleus laminaris of the owl. J Neurosci 1996; 16:7046–7054.

Peña JL, Viete S, Funabiki K, Saberi K, Konishi M. Cochlear and neural delays for coincidence detection in owls. J Neurosci 2001;21:9455–9459.

Pettigrew JD, Konishi M. Effects of monocular deprivation on binocular neurons in the owl’s visual Wulst. Nature 1976a;264:753–754.

Pettigrew JD, Konishi M. Neurons selective for orientation and binocular disparity in the visual Wulst of the barn owl (Tyto alba). Science 1976b;193:675–678.

Pettigrew JD, Konishi M. Some observations in the visual system of the oilbird (Steatornis caripensis). Nat Geograph Soc Res Report 1984;16:439–449.

Phillips LH, Konishi, M. Control of aggression by singing in crickets. Nature 1973;241:60–65.

Quine DB, Konishi M. Absolute frequency distribution in the barn owl. J Comp Physiol 1974;93:347–360.

Saberi K, Farahbod H, Konishi M. How do owls localize interaurally phase-ambiguous signals? Proc Natl Acad Sci USA 1998;95:6465—6468.

Saberi, K, Takahashi Y, Albeck, Y, Arthur, BJ, Farahbod, H, Konishi M. Effects of interaural decorrelation on neural and behavioral detection of spatial cues. Neuron 1998;21:789–798.

Saberi K, Takahashi Y, Farahbod H, Konishi M. Neural bases of an auditory illusion and its elimination in owls. Nat Neurosci 1999;1:656–659.

Schmidt M, Konishi M. Gating of auditory responses in the vocal control system of awake songbirds. Nat Neurosci 1998;1:513–518.

Sullivan WE, Konishi M. Neural map of interaural phase difference in the owl’s brainstem. Proc Natl Acad Sci USA 1986;83:8400–8404.

Sullivan WE, Konishi M. Segregation of stimulus phase and intensity coding in the cochlear nucleus of the barn owl. J Neurosci 1984;4:1787–1799.

Takahashi T, Konishi M. Projections of the cochlear nuclei and nucleus laminaris to the inferior coliculus of the barn owl. J Comp Neurol 1988;274:190–211.

Takahashi T, Konishi M. Projections of nucleus angularis and nucleus laminaris to the lateral lemniscal nuclear complex of the barn owl. J Comp Neurol 1988; 274:212–238.

Takahashi T, Konishi M. Selectivity for interaural time difference in the owl’s midbrain. J Neurosci 1986;6:3413–3422.

Takahashi T, Moiseff A, Konishi M. Time and intensity cues are processed independently in the auditory system of the owl. J Neurosci 1984;4:1781–1786.

Takahashi T, Wagner H, Konishi M. Role of commisunal projections in the representation of bilateral auditory space in the barn owl’s inferior colliculus. J Comp Neurol 1989;281:545–554.

Viete S, Pena JL, Konishi M. The effects of interaural intensity difference on the processing of interaural time difference in the owl’s nucleus laminaris. J Neurosci 1997;17:1815–1824.

Volman S, Konishi M. Spatial selectivity and binaural responses in the inferior colliculus of the great horned owl. J Neurosci 1989;9:3083–3096.

Volman SF, Konishi M. Comparative physiology of sound localization in four species of owls. Brain Behav Evol 1990;36:196–215.

Volman SF, Konishi M. Adaptations for bi-coordinate sound localization in owls. In: Eds. K. Schildberger and N. Elsner, Neural Basis of Behavioral Adaptations. Progress in Zoology1994;39:1–11.

Wagner H, Takahashi T, Konishi M. Representation of interaural time difference in the central nucleus of the barn owl’s inferior colliculus. J Neurosci 1987;7:3105–3116.

Lawrence Kruger

BORN:

New Brunswick, New Jersey

August 15, 1929

EDUCATION:

Wagner College, B.S. (1949)

Yale University, Ph.D. (1954)

APPOINTMENTS:

Research Associate, Institute of Living, Hartford, CT (1954)

Fellow, Johns Hopkins Medical School (1955)

Instructor, UCLA School of Medicine (1957)

National Research Council Fellow, Institut Marey, Collège de France, Paris (1958)

National Research Council Fellow, Oxford University (1958)

Senior Research Fellow, Department of Anatomy, UCLA (1959)

Department of Anatomy, UCLA (1960)

Department of Anatomy and Cell Biology, UCLA (1966)

Department of Anesthesiology, UCLA (1976– )

Distinguished Professor of Neurobiology, Emeritus, UCLA (1995– )

HONORS AND AWARDS (SELECTED):

Lederle Medical Faculty Award (1963–1966)

Editor-in-Chief Somatosensory and Motor Research (1983–1995)

Cajal Club–Nucleolus (1985–1986) and President (1986–1987)

Fogarty Senior International Scholar (1977, 1989)

Wellcome Visiting Professor, Albany Medical College (1981)

Javits Neuroscience Investigator Award (1984, 1991)

Horace W. Magoun Lecturer, UCLA (1997)

Getty Research Institute, Resident Getty Scholar (2001–2002)

Fellow AAAS (American Association for the Advancement of Science) (2006)

Endowment of Lawrence Kruger Neuroscience Scholarship at UCLA (2007)

Lawrence Kruger began his research with electrophysiological mapping and anatomical studies of visual and somatosensory systems. In somatosensory systems, he characterized the distinctive ultrastructure of peripheral nociceptor terminals, he described the C-fiber thalamic “pain” projections, and he compared the representation of the “lemniscal” and “anterolateral” systems at the brain stem level. He also carried out broad studies of sensory mapping and comparative neurobiology. This work led to some of the early studies characterizing the fine structure of normal and reactive astrocytes and oligodendrocytes. He described the migration of microglia, studied axonal degeneration in the periphery, and provided the earliest evidence of “continuous growth” of axons following laminar lesions of the cerebral cortex, a finding later supported by in situ hybridization. His later work on pain centered on characterizing the specialized peripheral distribution of lectin and peptide-labeled thin nociceptor fibers and on developing his concept of a sensory axon “noceffector” response to injury. He has also studied the early history of experimental neuroscience.

Lawrence Kruger

Controlling the narrative of one’s life is a rich privilege that allows one to be more generous than is demanded of serious biographers, for autobiographies are easily imbued with callous self-promoting stigmata. The events in a scientist’s life may engender the curiosity of those working in the same sub-specialties but will hardly be of sufficient interest to later generations of non-specialists to whom such memoirs might be addressed. Accordingly, this personal narrative includes events and scientific pursuits that seemed adventurous at the time and perhaps are still worthy of retrospection. It is directed toward revealing the context, driving force, and excitement in the scientific enterprise of academic research, including a brief description of the setting as well as the changes in the “establishment” that provide the fundamental materials of historiography. A personal retrospective of the limited and more intimate world of neuroscience as it blossomed in the last half of the twentieth century, before research teams became a dominant pattern, is presumably most valuable if it extends beyond individual scientific accomplishment and conveys some sense of success (and failure) in pursuit of scientific ideas and the seemingly extraneous factors that shape careers.

I grew up in the culturally and academically rich environment of Brooklyn, New York, the son of minimally educated Polish Jews who emigrated to New York before World War I. My father, possessing tailoring skills, opened a garment factory and manufactured ladies and children’s coats until his retirement in his seventies, and my mother remained an energetic and witty “homemaker” for a full century. Summers were spent largely on a New Jersey country farm near New Brunswick, where I was born in 1929, the youngest of three children, during the great economic “depression” that enveloped the United States. Our family name, Kpykr in Cyrillic, is Polish for “crow,” the bird, and was variously anglicized by Ellis Island officials—thus Kruger.

Music

While seemingly not germane to a scientist’s memoir, it would be remiss to omit commenting on how music shaped my life significantly at many stages, but most profoundly when in junior high school. Probably the singular event in my early development was being taken by my younger sister to a concert by cellist Emanuel Feuermann, performing works for cello (with an orchestra I later played in), including a performance of the Dvorak concerto, providing a moment akin to an epiphany and a strong desire to study the cello. The impact was immediate, and I knew I wanted a cello but was unable to persuade my parents to provide one for me until my Bar Mitzvah approached. By then, having progressed from agnosticism to an attitude more akin to antitheism, I was not above compromising and performed the ceremonials despite some distaste for the stultifying impact of religious practices. In return, I extorted the cello from my parents and agreed to perform the ritual ceremony, complete with speeches in Hebrew, Yiddish, and English in exchange for a decent instrument and lessons—an agreement that ultimately brought them almost as much pleasure as it did in altering my own life and developing a sense of dedicated self-discipline. This also ended the daily after-school Jewish education that had already developed the strong contrarian and occasionally iconoclastic tendencies of many youngsters who later pursued careers in science.

An abiding enthusiasm for classical music persisting into adulthood has been central to my personal development and daily activities throughout my entire career. Growing up in New York City where there were many amateur community orchestras and opportunities to play the major repertory and attend numerous low-cost concerts propelled what seemed a normal human propensity toward music into a passion that has been a central force in my life. I probably became a serious reader in my teens because I averaged hours each day on the subway with books in my cello bag. The details of my musical life somewhat reflect the narrative path of traditional autobiography that follows in relating scientific endeavors, but “musicophilia” is a common childhood occurrence that has enabled the development of an ability to organize and memorize intricate sequential patterns and huge quantities of seemingly meaningless retrievable information that persists throughout life. To the extent that my memory has served me well (despite recent signs of decline), I suspect this derives largely from the mnemonic power of music. Many of the happiest events of my life have been associated with music—especially the years of playing chamber music with friends, academic colleagues, and occasionally, outstanding professionals.

Early Education

My early education in the New York City public education system was generally excellent, especially the years at New Utrecht High School in Brooklyn. In addition to providing a quite decent orchestra program, most of my teachers sported Ph.D.s, a consequence of the desperate job situation that developed during the great economic depression. Its aftermath was evident in succeeding years in the general mind-set of seriousness that drove many youngsters to become dedicated book readers. The World War ended exactly on my 16th birthday, and in the next years colleges were inundated with returning GIs, making the choice of a college difficult. I was tempted by music scholarship offers but opted for a small liberal arts college (Wagner) closer to home where I was able to reside on campus and complete preparation for a career in science in 3 years, quickly recognizing I was unreceptive to a career in medicine. Although initially drawn to psychology, I decided that study of the physiology of the nervous system was precisely what I wanted, easily choosing Yale because of its emphasis on, and reputation in, neurophysiology.

Yale Years

Arriving at Yale, a rather immature and insecure graduate student in physiology 2 weeks after my 20th birthday was initially intimidating, but the warmth and kindness of the faculty assembled by the chairman, John Fulton, created an atmosphere of breadth and intensity that was especially embraced by the steady flow of neurologists and neurosurgeons who fulfilled the year of research then required for completion of 5-year residency programs. Fulton’s lab provided access to primates, good surgical facilities, and staff. Working with laboratory primates provided rich experiences and such personal memorable pleasures as my bottle-feeding a baby gorilla given to Dr. Fulton by celebrity hunter Frank Buck. In later years, primate experience and interest fostered my participation in the federal Regional Primate Centers program. Opposite my first “office”—best described as a closet for the department reprints and supplies that contained two student desks—was the Brain Tumor Registry originated by celebrated neurosurgeon Harvey Cushing and then supervised by Louise Eisenhardt, who trained the steady flow of clinicians in neuropathology in preparation for specialty board exams. She also served as editor of the Journal of Neurosurgery—funded personally by Dr. Fulton, who also created and funded the Journal of Neurophysiology and eventually relinquished ownership of both, among his philanthropies.

There were many sources of unusual kindness and generosity—especially from Fulton. An invitation to the spacious, elegant Fulton home was customary on an almost weekly basis following the weekly seminar whose speaker was the guest of honor, frequently a neurologist or neurosurgeon. The food and drink provided a lively party spirit as well as the joys of “shop-talk.” Fulton enjoyed dictating letters to his secretary, seated with him in the back seat of his chauffeured limousine, composing his many letters as if they were to be read posthumously. No letter failed to receive a rather prompt reply. His lifestyle and extraordinary generosity plus his editorship of the first advanced, quality, multiauthored, influential book on the Physiology of the Nervous System had great impact abroad, as well as in the United States, and his hobby of book collecting was supplemented by an ardent interest in fostering neuroscience history. John and Lucia Fulton’s Hamden home was built by the Swiss for the Chicago World’s Fair and was transported for reassembly in Connecticut in the years after he was appointed to the Yale Sterling Chair of Physiology at age 29. The extensive library of antiquarian books, largely in the history of science, was redolent of a book odor and atmosphere that has remained a source of comfort and excitement throughout my life. Dinners and parties at his home provided an extraordinary social milieu for the major figures in clinical neuroscience as well as basic scientists in mid-century, but the latter part of his career was marred by advancing poor health and such pressures as the red-baiting of the McCarthy era, which resulted in his being removed from the Physiology Chair and into the library with a newly created Chair in Medical History. The medical school Dean who removed him took over the Sterling Chair of Physiology himself, and the Department waned visibly with many staff and student departures in my latter years there.

The Yale graduate program in physiology was designed to produce teachers of the entire field of physiology rather than mere researchers. The five students who entered the program with me departed principally to enroll in a medical school curriculum elsewhere. Graduate students took courses with the medical students but were obliged to take the exams under customary controlled, competitive conditions whereas medical students took their exams home and submitted their papers anonymously. We also were obliged to take lecture and lab courses in each major specialty of physiology. We trained in other demanding disciplines as well, including physical chemistry and biophysics and had the pleasures of a history of medicine seminar (with Fulton) and seminars in the Biology Department where I met several extraordinary influential minds, including an aged, but exhilaratingly stimulating Ross Harrison, pioneer of neuronal tissue culture (then Emeritus and about my current age). Courses extended over 4 years and slowed the progress of thesis research, but there were many pleasant features of life at Yale. I dawdled and indulged in a rich musical life but finally completed my dissertation research after 5 years when pressed by the call to military service. Financial support at Yale came from a variety of sources, including my parents, but much came from research jobs, first from neurosurgeon Leonard Malis constructing various pieces of apparatus, and then from Lloyd H. Beck and Walter R. Miles in Psychology, which led to publication of my first psychophysical experiments in vision (Kruger and Boname, 1955) and the earliest attempts at establishing a scaling metric for subjective magnitude estimation in olfaction by scaling the intensity of aliphatic compounds of varying carbon chain length (Kruger et al., 1955a, 1955b); an idea derived from an introduction to S. S. Stevens at Harvard by Karl Pribram.

I was immediately attracted to several neurosurgeons arriving at Yale, choosing Karl Pribram as my advisor and then as thesis advisor. His support nurtured much of my professional and personal growth and provided a sense of being part of his family—a friendship of great importance in my early development. I also began working with two young neurosurgeons—Leonard (Len) Malis and A. J. (Joe) Berman, starting experimental work in my first year despite the heavy load of the medical curriculum and other courses. My earliest research experience exposed me to the rigors of surgical technique in primates, which seemed more glamorous than neurological exams, and the behavioral testing of monkeys with various motor cortex lesions (Berman et al., 1954). Our findings ultimately convinced the open-minded Fulton that rostral frontal lesions involved the proximal musculature rather than a specific extra-pyramidal spasticity; a view that Fulton had previously espoused. The distinction between localization of sites underlying production of flaccid and spastic paralysis was a “hot” subject at that time for clinicians. But recording electrically evoked potentials from the motor cortex proved most promising and led to the major theme of my Ph.D. dissertation and first neurophysiological paper (Malis et al., 1953) using a primitive lab setup left behind by Warren McCulloch that Len Malis helped me modernize. In turn, I helped Len in construction of a number of devices of his design (notably a cassette changer for cerebral angiography and the electronics for a bipolar split-forceps tissue coagulator for surgery). We later worked together pursuing an electrophysiological analysis of the complex triple wave response evoked in cat visual cortex (Malis and Kruger, 1956). This provided valuable experience in the use of the machine and electronics shops while adding to financial support and developed a strong friendship through continuing collaboration with a brilliant, supportive mentor (Malis became Chief of Neurosurgery at Mt. Sinai Hospital in New York and later was a dominant figure in microneurosurgery).

Fig. 1    Team assembled in research laboratory at Marineland, Florida in 1956 to map the sensory cortex of the dolphin (in tank). From left to right: Joe Hind (Wisconsin), Jerzy Rose and Larry Kruger (Johns Hopkins), Len Malis (Mt. Sinai Hospital, New York), John Lilly (NIH), and Karl Pribram (Institute of Living, Hartford). Vernon Mountcastle (Johns Hopkins) snapped the photo and Clinton Woolsey (Wisconsin) is beyond the camera view.

Malis and Berman urged me to switch to medical school and offered personal financial assistance, but observing their travails in medical practice during my summer “vacation” easily convinced me that dealing with human illness on a daily basis was not my ambition. I also was engaged in behavioral studies (Pribram et al., 1956) and received an invitation to write a review article with Pribram on the rhinencephalon that would be presented at a symposium on olfaction at the NY Academy of Science in which we systematized primary, secondary, and tertiary connections of the olfactory bulb as a set of “limbic” systems, a construct instigated by Paul MacLean. Surveying the literature and writing with Pribram was a joyous experience and was supplemented by a valuable, instructive critique delivered personally in a most kind all day visit by Hans-Lukas (Luke) Teuber (who then invited me to give my first invited seminar at New York University [NYU]). This was spoiled when my draft board decided that I should consider giving up graduate school to serve my country in the Korean War! The day I presented this paper preceded my plea that evening at my draft board to continue student deferment. The presentation went fine, but I was reclassified 1A and realized I must focus on completing my degree requirements quickly. The paper (Pribram and Kruger, 1954) was enormously successful, was reprinted in a book of readings, and elicited far more reprint requests (common in that era) than any dozen subsequent original research efforts. My dissertation research revealed the nature of cutaneous and muscle afferent projections to the monkey “motor” cortex, including their independence from the thalamic and postcentral tactile projection, and also presented a variety of experiments on the nature of the electrical response and the spinal pathway (Kruger, 1956).

Before reporting for military induction, I had arranged with Bob Galambos to work in his lab at the Army’s Walter Reed Hospital after basic training but, fortunately, military induction was interrupted by a perceptive orthopedist who noticed my scoliotic back and asked whether it was painful. Answering truthfully that it was not problematic, I was doubted and soon sent home with a 4F designation. The impending induction into the army had provided strong impetus for completing my dissertation and its defense, but the prospect of fighting in the Korean War left me with an uncertain future and many loose ends in my research and personal life. Fortunately, I was able to continue work in Pribram’s lab, which had recently moved to a hospital setting—the Institute of Living in Hartford, Connecticut. There I found an intellectually compatible, interactive group with two others (Mort Mishkin and Larry Weiskrantz) completing their Ph.D. theses with Karl. I also was able to complete the behavioral study for my thesis on the effects of total ablation of somatosensory areas I and II in monkeys. This was the first such study to reveal virtually complete degeneration of the putative thalamic tactile neurons while preserving some somatosensory performance ability despite a profound tactile defect (Kruger and Porter, 1958). This required building an infrared scanning device for observing the animal’s performance in the dark by employing the Nipkow disk “flying spot” principle. Developing new techniques seemed of paramount performance, and I soon embarked on making and implanting multiple-lead electrode pads across the preand postcentral gyri of monkeys (methods learned from Jose Delgado at Yale). This offered an opportunity to learn some basic electroencephalography with Charles Henry, head of the electroencephalographic (EEG) lab and a wry, stimulating teacher. The resulting report (Kruger and Henry, 1957) was received with unexpected enthusiasm, but it also helped me realize how limited such methodologies were then for clinical practice, resulting in a premature bias that the EEG was a poor indicator of neuronal activity and would yield little, further reinforcing my commitment to basic science. This transition period enabled arranging a postdoctoral fellowship with Jerzy Rose in the Physiology Department at Johns Hopkins to learn some neuroanatomy, having become painfully aware of my deficiencies in preparing the rhinencephalon review (Pribram and Kruger, 1954). A trip to Baltimore led to the decision to obtain dolphin brains to study the cerebrum of a mammal lacking a peripheral olfactory system.

I learned of the possibility of obtaining dolphins from a fellow student I knew while living at the Yale Hall of Graduate Studies, F. G. Wood, Jr. (“Woody”), who later became Curator in Marineland Florida. He offered two specimens, and Pribram prevailed on Kao-Liang Chow and Karl Lashley to remove the brains and ship them to Baltimore for me. Shortly after, with Lashley’s impending mandatory retirement at age 65, an attempt was made to recruit Pribram as his successor as Director of the Yerkes Laboratory of Primate Biology. This served as an excuse to drive to Florida with Pribram and spend a few days with Lashley, as well as to visit Marineland where we were able to perfuse and optimally preserve the brains from another two dolphins, which were brought to Baltimore en route home. The time spent with Lashley was fun, but rather strange. He was ardent about music, collecting chamber music parts that he crudely bound by hand and later gave to the Jacksonville music conservatory. He played the cello in an unorthodox position with the left thumb pointing upward. He had also built window boxes with light bulbs to contain the instruments and fight the moisture, although that proved rather ineffective. I enjoyed arguing with him about his ideas of “equipotentiality” and “mass-action” in cerebral cortex function, maintaining that this was as wrong-headed as his notions about cortical cytoarchitecture. Remarkably, that had a salutary outcome, and I heard stories of his days as a graduate student in parasitology at Johns Hopkins, living with psychophysicist Carney Landis and John B. Watson. Watson who later was the Chairman of Psychology at Johns Hopkins and proceeded to revolutionize the Madison Avenue world of advertising. Such intimate encounters and brashness have largely disappeared in the contemporary world of “big science.”

Johns Hopkins

I approached Jerzy Rose at Hopkins specifically to gain a foundation in neuroanatomy but also because the rhinencephalon review with Pribram had proved unexpectedly “popular.” Jerzy suggested that I engage in something original, and we had agreed that a description of the “olfactory brain” of dolphins, lacking an olfactory organ, might be an instructive anatomical exercise. However, publication of such an account in a smaller porpoise by Breathnach proved a propitious excuse for me to turn instead to the thalamus—for which Rose was an internationally recognized authority. The dolphin brain was challenging, and I decided to pursue an arduous analysis of thalamic nucleus volumes in a series of mammals, including a dense series of the sheep brain that I cut, stained, and mounted myself. This was the only time I ever indulged in routine histological preparation of significant scale in my entire career, and it taught me the value of a capable technician. Preparing the illustrations of the very large dolphin thalamus was a time-consuming ordeal and outlining the various nuclei in serial photomicrographs for each species to make measurements involved many instructive discussions with Jerzy and extensive planimetry. This was my trial by fire in trying to become an anatomist. The sheer size of the sections presented a difficult problem for producing illustrations, and employed the tedious task of inking individual neurons on montaged direct positive 8×10” prints and then bleaching the photo. Nevertheless, a hefty 66-page paper ultimately was accepted by Elizabeth Crosby (serving briefly as editor for the Journal of Comparative Neurology) with congratulations for the rare feat of requiring no corrections or changes—a tribute to the typist never again repeated. The findings indicated that the “association” or “intrinsic” thalamic nuclei were enormously expanded in the cetacean brain, paralleling primate evolution, and also exhibited some specialized features (Kruger, 1959). Jerzy had an enormous impact upon my personal, as well as scientific development. He imparted his brilliance with brio or a feigned humility that quite failed to conceal a remarkable wit and warm heart that delighted those few who had the good fortune of knowing him well.

A subsequent trip to Marineland with a distinguished team to study the dolphin sensory cortex electrophysiologically proved a difficult adventure, largely because of difficulty with anesthesia. Mountcastle courageously intubated the trachea with a human size cannula while we wedged blocks to keep the jaw open. But barbiturates and the mechanical respiratory pump designed by John Lilly at National Institutes of Health (NIH) proved inadequate for long-term mapping. The cortex was successfully exposed by craniotomies performed by Malis, Pribram, and Clinton Woolsey, and we obtained some surface electrocorticograms. The perfused brains provided suitable material for morphological study of the whole brain (Kruger, 1966), in addition to the thalamus (Kruger, 1959).

Life as a postdoc in the Hopkins Physiology Department was vastly more stimulating than I had expected, with most of the department usually attending lunch together and engaging in vigorous, often argumentative discussions that displayed impressive critical capacities and competitive spirit. Having been reared as a “compleat” physiologist, trained to teach all subjects, I was tapped by the Chairman, Philip Bard, to teach in the cardiac and renal lab exercises for medical students. But I had no contact with the neurophysiological aspects except for demonstrating the cardiac and respiratory effects of sympathetic and vagal stimulation in large dogs and in turtles. I widened my horizons across the street in the hospital where I frequently enjoyed my first coffee with Earl Walker (Chief of Neurosurgery), who usually had completed his first procedure and “rounds” by the time I was beginning my workday. I also found David Bodian enormously stimulating and kind, but it was in Steve Kuffler’s lab in Ophthalmology where I found my closest friends—Charles Edwards, Torsten Wiesel, Bob Bosler, and others, who incorporated me into their personal lives and also helped me ripen into a scientific world that was blossoming rapidly. Monthly meetings with drinks and dinner at the then new NIH or Bethesda Naval Hospital brought regular contact between the Baltimore/Washington neuroscience communities, resulting in a high level of camaraderie and sophisticated “shop talk.”

Fig. 2    Nissl-stained section of a laminar lesion in rabbit occipital cortex 42 days after irradiation with a monoenergetic beam of 20 million electron volt deuterons. The thin lamina lacking neurons was shown by other methods to reveal prolific growth of axons within weeks after the lesion.

In addition to the scientific world, my musical life in Baltimore was glorious. The new principal cellist of the Baltimore Symphony, Richard Kay, was a colleague in various amateur orchestras during our teen years in New York and lived near my apartment (and also helped me get Damien Kuffler started studying the cello). He provided cello tutelage and introduced me to professionals in the orchestra. Within a year I was invited to impose my musical tastes for an hour each week upon the listeners of WBJC-FM, broadcasting from Baltimore Junior College. For the next 3 years I studied and played the string quartet repertory weekly with a great quartet violinist, William Kroll, at the Peabody Music Conservatory, and I practiced regularly at the home of our fine first violinist, Janet Lehninger, wife of the Chairman of Biochemistry. I also formed a close friendship with the concertmaster of the Baltimore Symphony, Lotze Steinhardt, who could sight-read almost anything and with whom I gleefully explored twentieth-century chamber music. On various occasions he helped me entice key Symphony players to record unusual combinations at the WBJC studio for my weekly radio broadcasts.

In the lab, working strictly on morphology every day was a difficult discipline, and observing the quality of single-neuron recording obtainable with the new, low-impedance, platinized indium microelectrode developed by Jerzy had me champing at the bit to do experimental work again. I started by recording from the olfactory bulb of the turtles left over from those purchased for teaching the medical cardiac physiology labs but found that recording and isolating single neurons was far easier than controlling the delivery of odorant stimuli. I soon gave up and used the remaining turtles to make forebrain lesions to study thalamic projections in reptiles using the retrograde neuronal atrophy technique under the tutelage of Rose, the master of this method. This also soon was abandoned (although I later pursued the problem elsewhere in lizard and alligator). Instead, we attempted to employ this method to analyze the cortical terminations of thalamic projection neurons by making lesions of different laminar depth in the cerebral cortex.

Laminar Lesions

The ordeal of descriptive and quantitative neuroanatomy had frustrated my desire to do experimental work on thalamic degeneration. We finally hit upon developing a method for making cerebral cortex lesions of varying depth to elicit retrograde thalamic neuronal atrophy, which then was still a major tool for studying connectivity. An earlier attempt by Dusser de Barenne at Yale employing thermocoagulation brought minimal success, and our attempts to construct a device controlling the depth of a high-speed rotor proved impractical. Destroying the surface vasculature was critical and this was uncontrollable, but the frustration of failure led me to discuss the problem with Len Malis, who continued to nurture much of my development. He semiseriously suggested employing a mono-energetic particle beam of ionizing radiation that theoretically would penetrate the cortex down to a fixed depth with accuracy. Crude estimates suggested that this would require a highenergy particle generator, and after consulting physicist colleagues it became evident that we would need a linear accelerator or cyclotron of substantial size. A phone call to the Brookhaven National Laboratories, near Cold Spring Harbor, elicited interest. When we examined the range-energy (“Bragg”) curves for positive-charge particles, it became evident (assuming the brain approximated water in density) that the Brookhaven cyclotron would be suitable, and that it might be possible to destroy a layer in depth due to the “Bragg effect”—essentially an increase in energy release as particles slowed and increased their collision rate. This idea intrigued physicist Charles Baker, who supervised the Brookhaven cyclotron facility. Len and I soon irradiated the striate cortex in two cats in which we crudely guessed at dosage and irradiated the cortex through two bone trephinations. A few weeks later, I perfused the brains and gave them to Jerzy’s technician, Cecilia Bisson (who had prepared the dolphin brain sections). This enabled us to examine the cytoarchitecture, with taunts from Jerzy that this was a “shot in the dark” (indeed, it was). But it seemed interesting to observe the effects of controlled, focal ionizing radiation of the brain in the puzzling “atomic era” following the Hiroshima bomb.

When the first sections emerged the result was startling. There was a layer devoid of neurons in the striate cortex but a seemingly normal neuronal population above and below. The irradiated site revealed a thin layer with neurons destroyed (basically absent) and apparent minimal gliosis, with a sharp border (∼10 μm or one neuron wide) at the end of particle range. We knew of the sharp “Bragg curve” peak of energy release at the end of range of positive-charge particles, but a precise laminar lesion in the middle of the cortex seemed a wild dream, especially after we were able to vary lesion depth and width. Jerzy, recognizing a potential powerful new tool, mobilized us into launching a large study of the smooth rabbit striate cortex, and we were soon immersed in a project that dominated much of my effort for the next decade. Later the work continued with the better controlled measurable radiation beam obtainable from a larger cyclotron at University of California at Berkeley (UC Berkeley).

By the time we published our first report on the two cats in Science (Malis et al., 1957), we already were deeply immersed in extensive material from dozens of rabbits irradiated at Brookhaven. When we finally were able to measure dose accurately, our guess estimate proved wrong by about 17fold, indicating we had stumbled on the correct dosage range fortuitously. Malis designed an ionization chamber that enabled suitable measurement, and we soon geared up to extend our findings in a larger series of cortical lesions. We assembled a team and obtained approval, lab appointments, and support from the Atomic Energy Commission to design and perform experiments at the Brookhaven cyclotron. We spent 2 days (the maximum cyclotron time they would allot to our study) briefly irradiating the cortex of each batch of rabbits. Jerzy and I then drove them back to Hopkins where over the next 2 years I anesthetized, perfused, and removed the brains of ∼300 rabbits at a fixed schedule of postirradiation intervals. As the youngest team member, I was obliged to wear a film badge although it is doubtful that I ever was exposed to harmful dosages. (The badge proved irrelevant for the particle energies employed, and I was not even required to wear it regularly.) I mounted the anesthetized rabbit with open scalp and a lead shield with an opening at the end of the beam pipe over the lesion area we sought. I then emerged for the several minutes of irradiation, retrieving the animal for wound closure and recovery, repeating this routine for each animal. Only years later, looking back on this as a contribution to dosimetry—the first and most extensive study of neuronal, glial, and vascular sensitivity to ionizing radiation measured in suitable physical (rather than radiological) units—did we realize the importance of our efforts to the pioneering radiation-hazard studies begun by Tobias and Gofman at UC Berkeley.

The neuroanatomical findings proved far more interesting than expected. We soon examined features other than neuron injury and death over a wide range of parameters and discovered to our surprise that the laminar zone of neuronal loss revealed apparent destruction of axons in the early stages but that later the axonal pattern exhibited what we interpreted as “luxuriant growth.” The dictum that axonal regrowth after injury was feeble at best in the mammalian central nervous system (CNS) was firmly inculcated since the work of Cajal on degeneration and regeneration, which led him to conclude that neuronal connectivity was “fixed and immutable.” Profuse growth was quite unexpected and with lesions that resulted in a glial scar, the axonal regrowth failed to penetrate the glial “scar.” As a result, the lamina resembled the axon-rich non-neuronal zonal lamina (layer I) of cerebral cortex, thus forcing us to consider that axonal growth might be a basic property of all neurons but was aborted here by the glial obstruction. The axonal pattern of the laminar lesion basically resembled the proliferation seen at the edges in plant pruning. While static morphology could not directly establish the principle of functional “plasticity”, it nevertheless opened the door to considering possibilities of dynamic network growth as a basic feature of neurons. The reception of the initial documentation in the Journal of Comparative Neurology (Malis et al., 1960, Rose et al., 1960) elicited great interest and invitations (Kruger, 1965) and in the long run profoundly altered the direction of my career.

California Summer

An interlude in the hectic pace arose in the spring of 1957 from my attendance at a seminar on the history of neurology conducted by Oswei Temkin, an extraordinary medical historian with remarkable language skills and broad training in medicine and history. We were joined each week by a visitor on sabbatical leave at NIH, Horace W. (“Tid”) Magoun, who had a passionate interest in neuroscience history. He drove from Bethesda weekly with his wife Jean, and after several dinners together he invited me to University of California at Los Angeles (UCLA) for the summer. This was my first academic position, “Acting Instructor” in the History of Medicine division of the Department of Anatomy, where I would prepare a poster presentation on illustrations of the brain before 1800 for the 75th-year celebration of the American Anatomical Association. Baltimore summers were miserably hot and uncomfortable (the air-conditioning was lacking in the lab and my apartment). Work was less than optimally productive the previous year, and most people escaped for long vacations. I had never been far from the East Coast and finally arranged driving cross-country to Los Angeles in early June, a great adventure that changed my future in ways that I could hardly imagine. Before leaving I easily found most of the rare works in the excellent Hopkins Medical Library with Temkin’s help and guidance. Others came from the National Library of Medicine and Yale, all professionally photographed at Hopkins and billed to the UCLA Biomedical Library through Magoun. Mountcastle encouraged me to read H. L. Menken (the “sage of Baltimore”) on the subject of southern California, who raged that the “place stinks of orange blossoms,” was filled with “morons,” and that everything is “bigger and better” and rather vulgar, but once I reached the Rockies the West looked enchanting.

Finding a cello was my first concern after landing a simpatico place to live, and the assistant conductor of the Baltimore Symphony arranged contact with his brother in Los Angeles (LA), Ennio Bolognini; a flamboyant, fabulous cellist who opened doors into the music world of LA, including an introduction to a luthier near UCLA who offered a practice room in his shop, loaned me a “factory” instrument and introduced me to people to play chamber music. Within 2 weeks, my musical life had blossomed, and I was allowed the use of an instrument on consignment in the shop, the Stradivarius cello that once belonged to composer Felix Mendelssohn. The first concert I attended at UCLA’s Royce Hall was a celebration of Igor Stravinsky’s 75th birthday, with the composer conducting a world premiere of his ballet “Agon” and attended by many world-famous local musicians, all of whom I naturally imagined lived in New York!

The music world, the invariably comfortable warm days and cool evenings, the exotic beautiful greenery and the warmth and spirit of the people I met was enchanting. In addition, I started doing experiments with an enthusiastic young scientist, Ellis Berkowitz (later a distinguished otolaryngologist). Together we electrophysiologically mapped the olfactory, somatic, visual, and auditory projections to the cerebral cortex of alligators and prepared a series of ablations for later thalamic degeneration studies (Kruger and Berkowitz, 1960).

In addition to all of these happy developments, I drove to UC Berkeley one week, accompanied by another visiting scientist, Herbert J. A. (“Bert”) Dartnall from the Institute of Ophthalmology in London. Together we removed a California grey whale brain from an estimated 35 ton specimen brought in by a commercial whaling company operating in San Francisco Bay. I quickly fixed and blocked it for shipment back to Baltimore for histological study. In addition, with darkroom facilities at UC Berkeley provided by Gordon Walls, I was able to dissect the whale eyes and the retina for Dartnall (a trained chemist reluctant to dissect the eye), who later made rhodopsin extracts from the retina, revealing that cetacean visual pigments were essentially similar to those of other mammals. I originally had arranged this trip to visit Cornelius Tobias (at the cyclotron facility of the UC Berkeley Physics Department), who had published the suggestion that the Bragg peak theoretically could achieve hypophysectomy in humans without surgery. I presented a seminar to a small group showing the initial results of our experiments, which had employed this principle with the Brookhaven cyclotron, and was received with considerable excitement. The Director, John Lawrence (brother of Nobelist Ernest Lawrence, who devised the first cyclotron), expressed enthusiastic interest, and I was encouraged to consider returning to California to continue the radiation lesion experiments using the vastly superior accelerator facilities in UC Berkeley. There was another inducement to return to California. I was enamored of my productive summer experience at UCLA, and the Anatomy Department there was courting me to join the faculty after a postdoctoral stint I planned in Europe. The UCLA position was enabled by the NIH Senior Scholar program, which provided faculty salary plus research grant support with a nonbinding commitment of the institution to pick up the tenure-track salary within 5 years. Ultimately, the courtship from UC Berkeley could not compete with the prospect of Magoun’s planned new Brain Research Institute at UCLA or with the attractions of the cultural life in LA, especially its music world. But UC Berkeley’s interest later enabled me to continue with a very large series of cortical laminar lesions in rats, begun in UC Berkeley in the summer of 1960 where I also taught in a summer biophysics course with Tobias. Clearly, it would not be an exaggeration to acknowledge that the California summer sojourn in 1957 abruptly transformed my future.

Transition to Europe

I returned to Hopkins with a sense of exhilaration and excitement and the unexpected trophy of a decently preserved large mysticete whale brain to compare with the dolphin material, plus the brain of an Indian elephant that I had perfused at the Baltimore zoo the previous spring. It seemed I might have been destined to become an authority on large brains per se, but the lure of experimental work prevailed, and I prepared the dolphin brain studies for publication. My last year in Baltimore was quite full, with trips to the Brookhaven National Labs, where I was appointed a Research Associate. Between the trips to and fro with the rabbit cages in my car, the regime of timed removal of irradiated brains and a significant contribution to teaching in the physiology labs for medical students, I doubt that I could have sustained my good spirits in that era if not for the richness of my personal musical life. I worked hard in the lab, including weekends, but managed to play regularly with two string quartets and continued to study at the Peabody Conservatory and to play in its orchestra under Elliot Galkin, with whom I periodically played string quartets.

I applied for and received a National Research Council (NRC) Fellowship and by the summer of 1958 I was ready to start a new postdoctoral position at the invitation of Sir Wilfred Le Gros Clark at Oxford, with plans for experiments with Tom Powell on the reptilian thalamus, but the new lab building where I was to work was not yet completed and I was asked to postpone coming, although I had already accepted the NRC Fellowship. The happiest solution seemed accepting Denise Fessard’s invitation to come to Paris and work with her until late fall, and this was rapidly arranged. This was a richly rewarding experience of life and work in a style I could never have fantasized.

Paris

Meeting Denise Albe-Fessard at the 1956 International Physiological Congress in Brussels, my first European visit, had resulted in a stimulating exchange about a somatic projection to the thalamus that she had reported. This was distinct from the established tactile map, which is confined to the ventrobasal complex as detailed by my Hopkins mentors and friends—Rose, Mountcastle, and Henneman. Albe-Fessard had described a non-somatotopic projection to the region of the thalamic centre médian while employing chloralose anesthesia. This was evidently distinct from the controversial crude “map” that approximated the posterior group, with unit activity driven by putatively noxious stimuli as reported from Hopkins by Poggio and Mountcastle. Their technique employed a cumbersome fully-awake cat preparation requiring surgical denervation of the head. Inviting a young investigator from the Hopkins Physiology Department struck her as a potentially beneficial means of entering the fray, so she invited me to her Paris lab as a presumptive neutral observer, (although admittedly I was not unbiased), and she loved the challenge.

The Institut Marey was a marvelous place to work, located next to the tennis stadium (Stade Roland Garros) and demolished before the end of the century when the French Open tennis tournament became commercially important and expanded into the space of the two huge College de France installations. A huge lab had been built there for Professor Etienne-Jules Marey, largely devoted to recording physiological activity. It became a center for the emergence of cinematography in the late nineteenth century. Marey in Paris, and Muybridge at Penn collaborated with the Stanford “farm,” and both independently obtained multiple frame images of animals and people in motion. Alfred Fessard, Institute Director and distinguished Collège de France Professor, who had obtained postdoctoral training in physiology at Cambridge, was writing extensively from his broadly informed and imaginative outlook, and was no longer a bench scientist like his physicist wife turned neuroscientist, Denise. In addition to the Fessards, Pierre Buser was another group leader with broad interests, and all three shared a focus on cellular neurophysiology, having exploited the technology of using glass micropipettes to obtain intracellular recordings from electric organs and neurons of a variety of electric fishes. Alfred Fessard was also a key figure in fostering invertebrate cellular neurophysiology in postwar France and in developing the marine station in Arcachon.

Life in Paris was like entering into a series of fortuitous dreams. On arrival I was invited for Sunday dinner by a family in Boulogne close to my friend Roger Hahn (a UC Berkeley science historian). By the end of the day I was invited to live in their house close to the lab as a guest “boarder.” It was a large wooden chalet built by the Swiss for a nineteenth-century Paris Exposition, wedged into an idyllic lot between the Bois and the orangerie of the adjacent Rothschild estate. Other guests at my first Sunday dinner included the brother-in-law of host Mme. Nelly Cahen, who arrived with his “musical friend,” composer Francis Poulenc. Nelly had studied cello with the great cellist Pierre Fournier, and when I moved in the next day, she invited me to choose one of her two instruments and brought me boxes of music. The cello again proved key to a copious life of music and exhilarating work. Inexpensive housing, though lavish for my needs, rendered my stipend sufficient for purchase of my first new auto, a Renault Dauphine. Whenever time permitted I explored the wonders of France and also managed to visit Switzerland and Germany, including a trip to visit Oskar and Cecile Vogt, in whose lab Jerzy had trained glorious first experiences.

The lab experiments were demanding, often extending into early morning of the next day, but the results proved fruitful from the very beginning. The thalamic map, obtained by employing limb nerve volleys in chloraloseanesthetized cats seemed quite different in distribution and properties from the tactile or “posterior group” projections reported from Hopkins. Most surprisingly, there were very late responses (> 0.5 seconds), suggestive of peripheral C-fiber latencies. While awaiting tissue processing so that I could reconstruct the electrode tracks in transverse and sagittal planes, we moved ahead trying to record intracellularly using glass micropipettes with a sealed chamber system and microdrive that Denise had built. The results were exhilarating, yielding not only what were apparently the earliest intracellular thalamic recordings but also the discovery of responses with long but remarkably fixed latency. These were suggestive of a creditable, slow specific thalamic “pain” projection generated from C-fiber input. I completed the anatomical reconstructions later in Oxford and, with several trips back that winter and spring, produced seemingly important papers detailing a new thalamic pain projection before returning to the United States (Albe-Fessard and Kruger, 1959, 1962; Kruger and Albe-Fessard, 1960). My last trip was during the Oxford spring vacation in time to finish a decent draft with Denise amid grimaces portentive of the onset of childbirth. When we agreed the paper was finished, she calmly and radiantly announced that the contractions were now strong and more frequent, prompting me to hurry to my car as le patron, Alfred Fessard, mobilized to prepare and bring her downstairs, and I drove them to the clinique in Boulogne where Jean Francois Fessard was born several hours later. Denise beamed with pride but was distressed that she would miss the first lecture at the College de France the next day by Vernon Mountcastle.

In addition to the experiments, I became language-proficient in French and made several new friends at the Institut Marey through the Fessards. These included an elderly Englishman, Lucien Bull, (Marey’s assistant in the late nineteenth century who was still experimenting with high-speed photography and cinematographic methods), Yves Galifret, Pierre Buser, Arlette Rougeul, Jean Massion, Jan Bruner, and two eastern Europeans, Tauc and Szabo (both of whom I helped to come to UCLA). The diversity of ideas and techniques used by this group was amazing in their originality, excitement, and technical achievements. They also exposed me to the irresistible culture of French lifestyle.

Oxford

By fall the new labs at Oxford were ready and I pursued my original plan. The move to Oxford by car via the Dover ferry on Guy Fawkes Day in 1958 (wondering why effigies were being burned to greet my arrival) seemed a harsh diversion into cold and wet weather. After a week living at Halifax House, I found “digs” on Holywell Street, the oldest part of the city, with a chilling ceiling and three walls to the outside. This “rooming house” near the lab housed a collection of delightful people—including several undergrads (one, Verne Caviness, later became a neuroscientist) who had elected not to live in college, as well as those who could not (postdocs and others). The “Prof,” Sir Wilfred Le Gros Clark, who often introduced me as a “former colonial,” initially installed me in an office with a Russian neuroanatomist, Tatiana Leontovitch, from the Moscow Brain Research Institute, expecting to see feathers fly between the American and Russian “cold warriors.” But we got along famously, sharing jokes about English academics and having much enlightening political discussion. Her stay was short, and the remainder of my time was in an office/lab shared with Max Cowan, who had just returned from completing his clinical training and was ready to start new experiments and a significant teaching load. He and his wife Margaret became lifelong friends, although Max periodically “blamed” me for luring him to the United States, where he developed a remarkable and influential career.

I devoted more of my time at Oxford working on the electrophysiological studies from Paris than on the studies of experimental degeneration in the lizard thalamus and telencephalon with Tom Powell (Powell and Kruger, 1960), but life was full. I had obtained a fine eighteenth-century William Foster cello and found a rich musical life in Oxford and London. I also had opportunities to present my work in various places, including the Anatomical Society where I showed the results of the cortical laminar lesion experiments performed at Brookhaven and analyzed at Hopkins. This was received with unusual kindness and enthusiasm by the chair, Frank Goldby, Professor of anatomy at St. Mary’s and elicited an invitation from J. Z. Young at University College, London. I also presented to the Physiological Society the electrophysiological sensory mapping study of the alligator olfactory, somatic, visual and acoustic cortex (from the previous summer at UCLA). There was much interest and encouragement, including comments from Lord Adrian (who amusingly confessed that he had demonstrated the “cochlear microphonic” at the Physiological Society in alligator decades earlier but discovered that the heart had stopped—although the cochlear potential endured). Andrew Huxley questioned why the thin reptilian cortex should display larger evoked potentials than the thicker cat and monkey cortex. Visits to Cambridge as a guest of William Rushton and Sir Brian Matthews who at that time was interested in modeling the dolphin acoustic system led to other invitations, including presenting a seminar in Edinburgh followed by warming up in the cold winter by playing cello sonatas with my host David Whitteridge at the piano. Whitteridge and Adrian later provided moral support at a Ciba Foundation symposium organized by Yngve Zottermann on Pain and Itch in the spring, where I first presented the putative pain projection findings from Paris and met several European pain researchers.

UCLA

While in Europe I was courted for an academic position in biophysics at the Berkeley Lawrence Lab at UC where I would have access to excellent accelerator facilities for continuing the laminar lesion work and was also sought by Magoun and Sawyer (Chairman of Anatomy) at UCLA where a new Brain Research Institute was under construction. The UCLA offer and the musical life of LA were clearly more tempting. The NIH Senior Fellowship I had applied for was awarded, so I returned to Hopkins for the summer of 1959 to work on the laminar lesion papers with Jerzy Rose and in September arrived at UCLA/NIH funding a decently equipped lab being vacated by Carlo Terzuolo, who left for Minneapolis a few months later. His pharmacologist postdoc, Bob Siminoff, was still there trying to finish some experiments but was most willing to work with me on single neuron recording in the medulla. My initial plan was to map the tactile “lemniscal” projection in the dorsal column nuclei, producing the first figurine maps of the cat medulla, and contrast the “lemniscal” properties of the dorsal column nuclei with trigeminal neurons of the “spinothalamic” anterolateral system believed to contain putative “pain” neurons (Kruger et al., 1961). We were joined in this study by Paul Witkovsky, a graduate student in zoology after Siminoff left, a similar study in a few alligators (Kruger and Witkovsky, 1961) with Paul brought similar results and also a refutation of George Bishop’s argument that the dorsal columnlemniscal system was a recent acquisition of mammalian evolution. Later I was joined by my first postdoc, Francois Michel from Lyon, and we proceeded to map the trigeminal system in detail, searching for “pain” neurons but finding only tactile-driven discharges (Kruger and Michel, 1962a, 1962b, 1962c). I naively concluded that Pat Wall was correct in denying the existence of “nociceptors” but continued to pursue trigeminal studies for over a decade, eventually realizing that my initial well-received ideas about pain were as erroneous as my negative assumption, an important lesson learned slowly.

While applying for grant funds to gear up for continuing the cortical laminar lesion work, I was fortunate in being offered access to the superior cyclotron facilities at UC Berkeley. There was a smaller cyclotron at UCLA (the first, built by Ernest Lawrence) and run by David Saxon (later University of California President) who was most encouraging helpful in gaining access to the high-energy UC Berkeley accelerator provided sufficient range to make lesions deep into squirrel monkey striate cortex and the opportunity to perform many hundreds of laminar lesions in rat cortex. This proved logistically complicated as it involved shipping animals, assembling a large team and obtaining funds from the Atomic Energy Commission, although obtaining a contract and ample funding proved rather easy.

No longer a postdoc trainee and arriving at UCLA a ripe bachelor, there were predictions that my status was susceptible indeed, within a matter of weeks I met Virginia (Ginny) Findlay, my future wonderful partner in life. It was love at first sight, and a year later we married and soon started a family with the birth of our daughters, Erika and Paula—mothers of our treasured grandchildren. My musical life was largely devoted to playing string quartets but also in the UCLA and community orchestras and the Chancellor’s Committee on Fine Arts Productions, the last five as Chair. I also became deeply involved in fund-raising for the arts and presided over a newly formed organization, The Friends of the Performing Arts at UCLA.

Raising a family in LA on a modest academic salary wasn’t always easy, and job offers all involved administrative responsibilities something I knew I didn’t want and for which I felt unsuited. But most important, we loved life in LA and wanted to stay there. We were rescued from temptation by a surprise initiated by the Chairman of physiology, Wilfried Mommaerts, who, unknown to me, had instigated my nomination for the Lederle Medical Faculty Award, ten of which were awarded nationally; each year each medical school allowed one nominee. Receiving the salary supplement that came with this award enabled our family and work to thrive at a critical time in my career and the subsequent generosity of the UC Academic Senate review process propelled me forward to professor rank at age 36.

My first UCLA lab was in the Religious Conference Bldg. In 1959, I planned, together with my new lab neighbor Susumu Hagiwara (whom I met in Steve Kuffler’s lab), to move into adjacent labs of the new Brain Research Institute (BRI) where I would launch into diverse areas of research. Grant funds were readily available, and all of my applications were funded! I also applied to the new Eye Institute at NIH for funds to explore the alligator nervous system. My first graduate student was Tom Heric, who had a special interest in reptiles and sought me out when he learned I had worked with alligators. We worked together on the properties of the electrical response of the optic tectum and obtained the first retinotopic reptilian map in the alligator (Heric and Kruger, 1965, 1966). Tom then left to obtain a medical degree, not an uncommon event with our graduate students in that era. Horst Schwassmann, a zoologist postdoc from Clinton Woolsey’s lab, soon followed, and we mapped the visual projection in a variety of teleosts (Schwassmann and Kruger, 1965a, 1968). He soon persuaded me to import foveate fish, including the species with the most specialized vertebrate eye, Anableps, the “four-eyed” fish. Fortunately, he developed independent research projects on circadian rhythms in electric fishes and the early development of the brain and visual system in fishes because we were unsuccessful in keeping imported Anableps alive. Nevertheless, the Office of Naval Research offered me a grant and military air transport of our equipment into Brazil, leading to our arranging teams to work at the Museu Goeldi in Belem, where Horst and I set up to successfully map the Anableps tectal projection. We also described the operation of the remarkable “double” pupil and the dioptric mechanism, and we quantified the retinal sense cell population (Schwassmann and Kruger, 1965a)—a most successful project we enjoyed immensely. We were joined by teams from the Hagiwara and Bullock labs working on electric fishes of the Amazon basin, and while they were using the setup, I plunged into netting the exotic regional butterflies for Hagiwara’s collection.

The appeal of comparative neurology was much influenced by Ted Bullock and Hagiwara, both of whom were superb mentors and wonderful friends with brilliantly original minds. They chose exotic animal models to address fundamental problems. Although I did not collaborate and publish with them, I doubt that I would have remained at UCLA without the support of their friendship, scientific impetus, and inspiration. Both recognized those key scientific questions that are amenable to analysis and then chose the optimum preparation for solving the problem. Susumu’s impact was enormous on a daily basis, and I was in awe of his prodigious insights that led to developing the giant squid synapse for simultaneous intracellular preand postsynaptic recording, illuminating sensory coding mechanisms in lowand high-frequency electroreceptors, and discovering calcium currents in the barnacle eye. These were among several high points in the career of one of the truly great neuroscientists of the twentieth century.

The first of my comparative sensory physiology papers was derived from the experiments in the summer of 1957 in which we mapped the olfactory projection to the lateral pyriform cortex of the alligator by electrically stimulating the olfactory bulb or tract and the dorsal pallial overlapping projections from visual, acoustic, and somatic inputs. I added the thalamic degeneration that followed cortical lesions to the report on sensory mapping (Kruger and Berkowitz, 1960) and for several years proceeded with mapping sensory projections in various animals. During this period, I was diverted by Magoun (to whom I was much indebted for nurturing my career at UCLA) because of my past experience with dolphins. On his sabbatical leave in 1957, Magoun had worked with John Lilly at NIH and had become interested in Lilly’s work on dolphin behavior. He also learned that Per Scholander at the Scripps Oceanographic Institute at University of California at San Diego (UCSD) was interested in building a lab in La Jolla for dolphin research and asked me to contact him about possible collaboration with the UCLA-BRI. Scholander wanted to build a lab and a research vessel and already had preliminary architectural plans for both by the time of our first visit to La Jolla. I thought it unlikely that the University of California and federal funding agencies were likely to support this fanciful and expensive project, and I confessed my reticence about getting further involved with this to Ted Bullock, who in stern fatherly fashion admonished my negativity and advised me to cooperate. If the proposal lacked sufficient merit, it presumably wouldn’t be funded. Our proposal to NSF seemed anomalous but was apparently strengthened by the component from the UCLA-BRI requesting lab space and financial support for work and construction at UCSD! To my amazement, this huge installation was enthusiastically approved and we were delighted, but Scholander was disconcerted that they wanted the research vessel the Alpha Helix built in the United States rather than the shipyard in Norway that he had his heart set on for its construction. All of this stretched over several years and by the time it was completed, Bullock and Hagiwara had agreed to move to Scripps at UCSD and to join the country’s first Neuroscience Department in the new medical school. The same temptation was also dangled to me by my former Yale colleague, Stanley Mills, who was deeply involved in forming the new medical faculty. I planned my first sabbatical at NIH and after a few months moved to UCSD in 1968 where I worked in the lab assigned to me for the UCLA-BRI. I later happily turned this over to Horst Schwassmann, who was obviously qualified and suited for the Scripps environment. Ginny and I, with our two young children, broadened our outlook in this stimulating milieu and continued to visit over the years for social and scientific reasons, but we were attached much too closely to the big city of LA, with its vibrant music, art, and theater scene, and I had become deeply immersed in the performing arts program at UCLA.

The laminar lesion project was my principal focus during my first decade at UCLA, largely driven by the necessity for obtaining more persuasive evidence for axonal amputation followed by prolific re-growth than could be obtained within the limitations of silver “staining” methods. The fortuity of contacts and cooperation that developed from the many directions that I pursued while studying anatomical growth and degeneration in the cortex and thalamus can hardly be overstated. The electron microscopy derived much of its impetus from numerous technical advances made in Dan Pease’s lab in the Anatomy Department; particularly with respect to the rapid perfusion of neural tissue with aldehydes, and details such as tissue oxygenation, embedment, staining, and so on. Dan was preparing a monograph on electron microscopy (EM) methodology and his promising student, David Maxwell, who was immediately given an assistant professor position, expressed an interest in examining the fine structure of laminar lesions. A fast fastgrowing friendship between our wives and kids, as well as our personal camaraderie and mutual scientific interests, led to a warm, intense collaboration. This involved preparing many hundreds of laminar lesions at various cortical depths, doses, and survival times to gain insight into the fine structure and sequence of events using the modern electron microscopic techniques recently mastered by David.

Light microscopy proved unexpectedly successful in visualizing a profound vascular response in the laminar lesion zone by employing vascular injection (Rose et al., 1960), but the seeming proliferation of vessels required electron microscopic analysis. The first glimpse proved dramatic, largely because we employed very rapid intra-cardiac aldehyde perfusion of the brain. At the lowest magnification there appeared a horizontal black stripe. At higher magnification the stripe encompassed a zone that apparently lacked neuron somata but that was replete with profiles permeated with small dense granules that we soon identified as glycogen. It immediately became evident that small vessel walls, especially those of capillaries, displayed profiles surrounded by glycogen-filled (and thereby “labeled”) processes that we reasoned must be astrocytes. Indeed, glycogen and microfilaments proved the distinctive “markers” of astrocyte processes, and we soon learned the necessity of maintaining the oxygen supply during perfusion so as to avoid the very rapid depletion of gycogen (Maxwell and Kruger, 1965a). The ease of identifying astrocyte processes, especially in damaged tissue, also enabled us to characterize normal and reactive oligodendrocytes (Kruger and Maxwell, 1966a, Maxwell & Kruger, 1966). Most gratifyingly, the production of a circumscribed lesion without vascular disruption provided an unanticipated insight into the origin of microglia from vessel wall elements. We also attempted to understand the source and “reactive” process that involved the elusive “microglial” cell and soon realized that vascular “pericytes” of small vessels became devoid of the distinctive amorphous, extracellular “basal lamina” that normally demarcated the boundary between mesodermal and ectodermal cells and tissues. Our account of the fine structure of the reactive “microgliocyte” (Maxwell and Kruger, 1965b) was well received but not without controversy, and our views on the classification of all normal and reactive glia elicited some excitement as well as greatly appreciated friendly encounters with two invited seminar speakers, David Bodian and Alan Peters, who were then the leaders in this field. I pursued this again years later, with postdoc Murray Matthews from Bill Willis’s lab. Murray was interested in pursuing the electron microscopy of reactive glia, and I prepared a series of rabbit sensory cortex ablations to examine the “gliosis” in the thalamic projection nuclei accompanying retrograde neuronal atrophy. The findings largely mirrored what we had seen in irradiated cortical laminar injury sites. But without direct injury the perivascular changes were more readily amenable to analysis, and we obtained some excellent micrographs demonstrating the passage of hematogenous elements across the vascular basal lamina and into the neuropil (Matthews and Kruger, 1973a, 1973b). I gained considerable technical knowledge from Murray, who continued with this project in his first academic post.

The other striking finding made earlier (Rose et al., 1960) was that it was possible to destroy neurons and their processes with minimal gliosis in a sharply demarcated layer, the edges of which revealed apparently intact neurons 10 to 15 microns above and below the laminar lesion zone. But the big surprise was that within a few weeks the zone of neuron soma destruction was filled with “silver-stainable” axons thus indicating rapid and prolific axon growth in the mammalian cerebral cortex. This defied the established dictum that little more than “abortive” growth could be seen in the adult CNS. With higher radiation doses, gliosis became quite apparent, and a scar blocked the radial growth of axons and gave the laminar lesion zone the appearance of the normal zonal lamina (layer I). But regardless of dose, the growth of axons appeared to be “luxuriant.” Although initially based on quantitatively unreliable silver impregnation methods, the later electron microscopic observations confirmed the rich bed of axons while revealing that silver methods did not reliably “stain” all axons. These observations thus supported the hypothesis of “continuous growth” of axons in adult CNS (Kruger, 1965). The findings also indicated that on a quantitative basis the characterization of axonal growth was more complicated than we initially had envisioned, although the general principle was apparently correct. Although EM of laminar lesions importantly provided the means for characterizing the specialized features of irradiated neuropil, and yielded insight into the process of continuous axon growth that had previously eluded neuroanatomists, the phenomenon was not yet susceptible to rigorous quantitative analysis.

We inferred from Nissl-stained preparations that dendrites also grew back into the aneuronal lamina, a finding later supported by an EM study when I was joined at UCLA by a talented and energetic visiting scientist from Hungary, Joseph (Joscka) Hamori. This collaboration and friendship brought much pleasure to my family and worklife, and resulted in the first fine-structural account of the process of degeneration in dendrites (Kruger and Hamori, 1970), something that could not have been achieved by any other known method. Dendritic growth proved even more exotic than the expansive axonal growth pattern that resembled the “pruning” effects seen in gardening (although I was admonished for considering this analogy openly and later avoided it). Our hypothesis of continuous axon growth was largely ignored, perhaps in part because others could not follow up the observations without first mastering the costly and cumbersome methods from particle physics. Its implications for connectional “plasticity” became apparent decades later while studying neuronal growth with GAP-43 mRNA autoradiography (Kruger et al., 1993).

The large UC Berkeley cyclotron provided a larger range of particles, including particles with high enough energies to penetrate to the deep layers of the cortex. This made it possible to produce a critical lesion in the smooth striate cortex of squirrel monkeys and demonstrated that such a lesion, which destroys all projections to the bottom of the granular layer (IV), elicits profound neuronal retrograde atrophy of the thalamic dorsal lateral geniculate nucleus and that the geniculate cells are not sustained by their projections to layers V and VI. These findings were consistent with and were published together with a large study of the afferent and efferent connections of the rabbit striate cortex (Kruger and Malis, 1964).

The UCLA team, which was organized with David Maxwell to work at UC Berkeley, also amassed a collection of several hundred animals where we had accurate measurement of radiation parameters as well as control of size, depth, and site of lesion placement. However, human factors sometimes intervene to alter what seem like the best of circumstances. I naively failed to recognize obvious signs of my close friend’s faltering health. David’s first hospitalization and bout of seizures signaled serious disease problems and interrupted the closest and happiest daily work collaboration I could have hoped for. It took some time before I was able to recognize and come to grips with its horrific impact. The gradual decline and ultimate demise of someone I deeply admired and cared about took an enormous toll on our personal lives and especially the lives of his family. The ties of our wives and children helped for awhile, but the work situation could not endure the complexity of a dysfunctional disease state and forced us to recognize that we had run “out of steam” in pursuing a very demanding project. Having written all of the applications for funding, I felt obliged to inform the funding agencies of our decision to wind down the laminar lesion project. I was fortunate in having continued my electrophysiological interests and activities, which gradually enabled me to obtain funds to change direction. Twenty-first century readers may be astonished to learn how research funding has changed in just a few decades. Individual researchers, rather than lab teams, were the general rule, and the granting agencies, principally the NIH and the NSF (but also the Atomic Energy Commission), fostered productive young scientists with extraordinarily generous attention and assistance. Throughout my career they funded every grant application I submitted and with special helpfulness at each of my several transitions in research direction.

Comparative neurology studies continued during this period and included publication of an extensive series of EM papers with Maxwell. These revealed many new observations that helped characterize the fine structure of glia and the axonal degeneration patterns in nonmammalian vertebrates (Kruger, 1969; Kruger & Maxwell, 1966a, 1967, 1969) and in the transition zone of the trigeminal root (Maxwell et al., 1969). But my attention gradually migrated to further mapping studies, including the retinotopic projections to the pretectal thalamic nuclei (Siminoff et al., 1967), and the still unexplored rat superior colliculus (Siminoff et al., 1966). A pair of talented undergraduate brothers, Steve and Paul Feldon (both later distinguished medical academics), produced the first topographic map of the visual projection to the cat superior colliculus (Feldon et al., 1970) and discovered its unexpectedly specialized ipsilateral projection. I published invited reviews of some of this work (Kruger, 1969, 1970) and also completed the first map of the primate (macaque) sensory trigeminal nuclear complex with Mayo Clinic neurosurgeon F. W. L. (“Fred”) Kerr, who came over a 4-year period to learn electrophysiological methods and to escape some Minnesota winter months (Kerr et al., 1968; Kruger, 1971). In dissociated chick sensory ganglion cell cultures that I had brought back from Silvio Varon’s lab at UCSD, Penny Coates unexpectedly discovered EM evidence of distinct synaptic contacts between the ganglion cells, despite their absence in mature mammalian ganglia (Miller et al., 1970). This project fizzled, largely for technical reasons.

An important diversion arose when Ed Perl invited me to Salt Lake City to observe experiments that he and Dick Burgess had been pursuing in their study of “nociceptor” fibers. Although I had read Perl’s findings with Bessou on C-fiber specific nociceptors and was also aware of Ainsley Iggo’s findings in visceral C-fibers, I had maintained that there were no observable specific “pain” neurons in the “anterolateral system.” Perl felt that I should observe an experiment in his lab, serving as critic. Flattered by the friendly invitation from someone I had long admired, and confident in my biased view, I was delighted to participate in this challenge. However, I was quickly persuaded that they were indeed on solid ground and that my negative observations could be easily discounted. This manner of resolution of scientific differences fostered further collaboration with Perl’s lab after he moved to the University of North Carolina. It also developed into a lifelong friendship and led to later collaborative publications (Kruger et al., 1981; Perl and Kruger, 1996) as well as his help in constructing a more accurate, controlled tactile stimulator. But all of this was not without bringing turmoil into my scientific life. I was joined by a recent UCLA physics Ph.D., Bernard Kenton in pursuing quantitative studies of slowly-adapting mechanoreceptors and by UCLA neurosurgery residents, James Mosso and Douglas Kirkpatrick, in analyzing the brain stem trigeminal nuclear complex. These latter studies were motivated by the claim of Ian Darian-Smith’s trigeminal study, which had suggested that the difference between “lemniscal” and “spinothalamic” properties were simply quantitative in nature, an idea that incited my periodic contrarian tendencies.

The thrust for studying quantitative differences between “lemniscal” and “anterolateral” properties collapsed rather quickly for lack of evidence. Yet it was not a totally wasted effort because the first experiment with Jim Mosso in which we recorded from the spinal trigeminal nucleus caudalis yielded an unexpected surprise—certainly for me. After demonstrating the pattern of sensitive mechanoreceptor representation in the first microelectrode penetration, the first isolated unit in the next puncture yielded a large spike that I couldn’t seem to activate. Mosso insisted that this surely might mean it could be a pain or temperature-driven cell. To my amazement we found it was excited by cold, hardly surprising to a neurosurgeon, and he immediately became confident that we also would find cells driven by noxious stimuli capable of eliciting pain in an awake animal. Indeed, he was correct, and we proceeded to re-map the trigeminal sensory complex in anesthetized cats. We found superficial neurons with properties of the nociceptor afferents that Perl and Burgess had demonstrated to me in Utah, and we excitedly published our findings (Mosso and Kruger, 1972, 1973). By then, Ed Perl had completed a superb analysis of the spinal cord marginal layer dorsal horn units, and our findings basically confirmed his results for the “anterolateral system” component of the trigeminal representation, something not found in the “lemniscal” principal trigeminal sensory nucleus (Kirkpatrick and Kruger, 1975).

Extensive quantitative data with Bob Siminoff on reptilian cutaneous receptors (Siminoff and Kruger, 1968) followed by more extensive data with Bernie Kenton (Kenton and Kruger, 1971; Kenton et al., 1971), soon revealed that the application of S. S. Stevens’ “power law” and the application of “information theory” advocated by Gerhard Werner and Vernon Mountcastle was problematic. Every mechanoreceptor neuron, by its very nature, displays a somewhat variable threshold followed by a sigmoid function that ends in a plateau. While plotting the results on log-log coordinates can yield a power function, Kenton, using the resources of UCLA’s new computer center soon discovered that the “best fit” curve was rarely, if ever, best described by a power function. We ended up writing an extensive review using our new data, as well as previously published findings of others, arguing that it seemed unreasonable to ascribe the same power function value to neurons from the periphery to the somatic cortex as well as to behavioral estimates derived from subjective magnitude scaling (thus implying that the nervous system was simply a net linear operator). We sent a copy to Baltimore and to Dominick Purpura for consideration for publication in Brain Research. He advised me as a friend that, despite the failure of referees to counter our arguments, we were treading on dangerous ground and perhaps should reconsider what promised to become controversial. Werner and Mountcastle understood our arguments but disagreed with our conclusions. After an awkward but friendly phone conversation with Gerhard Werner and Kenton’s urging that it was “healthy” to subject such issues to the judgment of the scientific community, we decided to proceed with publication (Kruger and Kenton, 1973). In retrospect, there are no victories in such controversies and, although our arguments were never effectively attacked and refuted, I later came to regret succumbing to iconoclastic urges—especially risking my relationship with Mountcastle, who continued to treat me with the same level of kindness as in the past, during my Hopkins years.

Multisensory Projections

Electrophysiological mapping studies were becoming less appealing when I was fortunate in recruiting a truly outstanding, talented postdoc in Barry Stein. He immediately displayed leadership and independence and developed imaginatively designed experiments with other postdocs. He became a treasured lifelong confidant, and I look back bemused about his complaint that I would not put my name on his papers from my lab unless I had participated in them. This was a policy copied from Jerzy Rose that has largely disappeared in this era of large research teams. I greatly enjoyed working with Barry Stein and Elemer Labos from Budapest on visual development in the kitten midbrain but recognize with clear hindsight that my criticisms may have hindered the progress of the studies that emerged (Stein et al., 1973a, 1973b, 1973c). When Labos returned to Hungary and Braulio Magalhaes-Castro arrived from Brazil, Barry was intent on demonstrating the overlapping of sensory patterns in the cat superior colliculus. Again, my role as critic probably slowed completion of a quick report to Science followed by detailed accounts (Stein et al., 1975, 1976). Barry continued to pursue the theme of interaction between sensory systems and built a vigorous program at Bowman Gray, where he developed and chaired an excellent Neuroscience Department. When he left UCLA, I decided to relinquish further work on the visual system except for completing a study characterizing the properties of the tactile neurons of the cat superior colliculus with a postdoc from Japan (Nagata and Kruger, 1979). I informed the Eye Institute (NEI) at NIH that I was not planning to apply for grant renewal. This resulted in a phone call and letters from NEI staff offering assistance to enable me to continue, something that now would seem most unlikely. But I was becoming aware that I was spread too thin and that my interests were moving in other directions, particularly toward the possibility of exploiting the development of what promised to become truly powerful anatomical tracing methods.

Axonal Transport Labeling

Acquiring new techniques from scratch with inexperienced young people was among the great delights of “teaching” or, more accurately, reciprocal mentoring. Learning together equalized personal relationships and provided a stimulus for continuous questioning and testing of new ideas. In this, I was most fortunate in welcoming the arrival of a psychologist postdoc from University of Southern California (USC), Sam Saporta, who felt some need of learning neuroanatomy, and also a youngster clearly headed for college and medical school, Sanford (Sandy) Feldman, who was energetic, original, imaginative, and open to anything new and challenging.

Sam and I started by using the newly introduced method of retrograde transport tracers for exploring the thalamic projection to the somatic cortex in the rat (Saporta and Kruger, 1977) and cat (Saporta and Kruger, 1979). We observed a distinctive pattern that was different between species, suggesting that the cat possessed a distinctive interneuron population lacking in rats. We also pursued anterograde axonal tracing in the primate visual system with tritiated adenosine, which proved elegant but represented a last gasp of our visual grant (Kruger and Saporta, 1977). That summer we indulged in the luxury of a last stab at adventurous “field work” by planning experiments at the newly established International Brain Research Laboratory in Kotor on the Yugoslavian Adriatic coast, with which UCLA just had formed a collaboration. We had hoped to study the highly specialized visual system of the large species of the strange teleost Hippocampus, which was resident in the Adriatic Sea, but our hosts were unsuccessful in obtaining specimens. We then turned to demonstrating the new tract-tracing methods to the Yugoslavs, while exploring some of the Dalmatian coast and the mountains, meeting many interesting people and especially those with artesanal skills. A stop en route in England elicited an invitation from Aidan Breathnach to spend a sabbatical at St. Mary’s, London. The idea was to learn their advanced methods in freeze-fracture replication, with the aim of rapidly preserving unfixed tissue and with the longer-term goal of achieving antibody labeling at the EM level as well as learning from the leading expert on cutaneous fine structure. Although no publishable scientific results emerged from our summer adventure, we returned from a memorable, invigorating experience eager to move forward.

Our interests attracted Larry Furstman, a retired orthodontist from the UCLA Dental School faculty, whom I had met while lecturing to dental students on the specializations of trigeminal innervation that were relevant to the dentistry curriculum. Furstman was interested in learning new techniques, and I asked Sam Saporta to help him with horseradish peroxidase retrograde axonal tracing from the dental pulp to the trigeminal ganglion. This resulted in the first demonstration of this strategy in the peripheral sensory nervous system (Furstman et al., 1975) and launched our serious interest in applying new technologies to the study of the peripheral sense organs. During this period Sandy Feldman, then a college student working in successive summers, completed a remarkable and comprehensive study of the retrograde and anterograde labeled lemniscal pathway in the rat, which included early studies of the complex trigeminal pathways (Feldman and Kruger, 1980; Kruger, 1979) and was followed by further studies with a longtime neurosurgeon friend Ronald Young (Kruger and Young, 1981; Young and Kruger, 1981). In addition, Sandy and Sam helped my histology technician, Sharon Sampogna, in preparing a rat brain stereotaxic atlas, which was to be illustrated in the three major axes in matching, closely spaced fiber and cell-stained sections. The initial photographs were completed largely by Sandy, but this project was placed “on hold” until many years later.

Freeze-Fracture

A 7-month sabbatical leave fostered an exhilarating family vacation in Europe, enabling our now adolescent daughters to freely explore the world in ways that were impossible while living in the Los Angeles hills. It was a profound change of pace and in the fall, when Ginny returned home for the girls to continue in their home school, I immersed myself in the hands of Breathnach’s staff in the Anatomy Department at St. Mary’s, London, trying to master the skills of freeze-fracture replication in unfixed peripheral nerve. It was a tough task in an arduous discipline. The findings revealed original, interesting specializations of the membranes and cytoplasmic channels of the Schwann cell sheath (Kruger et al., 1979) and elicited invitations in Europe and the United States to present my findings. However, the aim of antibody labeling of axonal membranes, which we also pursued in some abortive attempts upon returning to UCLA, was not achieved until others exploited the technology successfully almost two decades later. Although the sojourn was only a rather limited success, it expanded my understanding of the ultrastructure of cutaneous innervation from Breathnach’s extensive material that he had accumulated for his EM atlas of human skin.

Return to Somatosensory Research

With this background I felt emboldened to pursue the electron microscopy of nociceptor endings in the skin, a project Ed Perl and I had discussed over several years after we felt convinced that there truly were discrete punctate “spots” constituting the receptive field of high-threshold mechanoreceptors. This involved fruitful and enjoyable trips to Perl’s lab, where “spots” were identified and marked with fine insect pins. Thus began the long, slow process of thick and ultrathin sectioning which resulted in the first electron micrographs and characterization of loci containing physiologically identified nociceptor endings penetrating into the stratum spinosum of the epidermis (Kruger et al., 1981). I also found great pleasure in studying polysaccharide changes and the fine structure of chromatolysis in spinal motoneurons (Magalhaes-Castro and Kruger, 1981) with visiting Brazilian postdoc, Heloisa Magalhaes-Castro. But by the late 1970s, neuroscience was expanding too fast for me to continue dabbling in whatever caught my fancy or to indulge in the serendipity of pursuing the interests of visitors, unless they were directly related to the somatosensory system that was now the basis for my entire funding. Nevertheless, opportunistic play still hovered irresistibly when I received a joint appointment in anesthesiology from Ronald Katz, the new Chairman recruited to UCLA, whose principal clinical interest was in pain research. This appointment not only widened my horizons and interactions but also brought me into contact with an ingenious engineer, Arnold Lee, who designed a fine air-jet tactile stimulator that moved across the skin surface in a controlled manner that my expanding lab group used to study more complex features of CNS sensory discharge properties (Castiglioni and Kruger, 1985; Golovchinsky et al., 1981; Ray et al., 1985). This stimulator, in addition to a controlled displacement device designed by Ed Perl, attracted the interest of Tom Woolsey, with whom I became closely associated in the creation of a new specialty journal, Somatosensory Research. Tom reasoned that if we could control the mechanical parameters of single vibrissa movement, and especially if we could achieve better spatial resolution, it should be possible to study metabolic labeling with tritiated 2-deoxy-D-glucose, a recent tool for functional labeling. I had become interested in exploring “bifunctional reagents” (binding sugars by oxidation with periodate to form aldehydes to be cross-linked with lysine), thereby limiting migration of sugar moieties. Tom happily agreed to visit UCLA to conduct some experiments and perhaps enjoy our summer weather. Working together was a joyous undertaking, and Tom took the brain tissues back to St. Louis, Missouri, where his graduate student, Dianne Durham, had been using a variant of this method of “metabolic labeling” for her thesis on whisker representation. Astonishingly, in addition to labeling known sites of vibrissal representation, we radioautographically visualized individual labeled neurons for the first time (Durham et al., 1981). Such diversions glow among the happiest adventures in a scientific career, although this particular adventure had little impact on the direction of my lab. Its greater impact secured a friendship that fostered our incursion into scientific publishing and the creating of a new journal.

The Publishing World

The original impetus for a specialty journal in the somatosensory field came from Seymour Weingarten of Guilford Press, an entrepreneurial enterprise in a world suddenly exploding with new journals. Seymour discussed the feasibility, need, and leadership issues with numerous leaders in the field, myself included, and I confess feeling flattered when he concluded from his various discussions that he wanted me to assume the role of founding Editor. I was reticent about the large responsibility and the danger of still another distraction, recognizing that I was easily vulnerable to such “sidebars” in my career. I already served on several journal editorial boards, including the Journal of Comparative Neurology, which I eventually served energetically for three decades, but the challenge of forming a new enterprise, selecting an editorial board, and forming the policies and style proved an irresistible temptation. I agreed to assume this responsibility for a term not to exceed 10 years, with the proviso that Tom Woolsey would serve as Associate Editor and later follow as editor at the end of my tenure. It actually took 12 years before Tom could arrange to take over the continuously evolving structure of Somatosensory and Motor Research. In the next decade it became one of the many smaller journals swallowed up by larger publishing conglomerates, and it has thrived under Woolsey’s able guidance. In retrospect, insistence on a limited term as editor proved a sound decision.

The opportunity to set up our own rules for the journal was actually fun, and I enjoyed wrestling with policy together with Tom and Seymour. My role model was Journal of Comparative Neurology editor Sandy Palay, who personally copy-edited many articles and often insisted on evaluating referee reports in his comments to the authors. This is a rare practice but proved most gratifying when my remarks to the authors included critical appraisal of the review. I tried hard to serve the cause of authors and to protect their egos from unfair battering, and I often doctored their fumbling with English usage especially for the Anglophone-deficient. Guilford Press supplied a salary for a part-time secretary—a speed typist who knew the cello literature and who also possessed the organizational skills requisite for managing a journal. Our mutual interest in music and her nurturing of a new flock of students and postdocs brought a fresh spirit to the lab, but later her unexpected cancer and death reinforced my decision to relinquish journal editing as originally planned.

Broader exposure to the publishing world brought new projects, including the organization and publication of a symposium on pain mechanisms with John Liebeskind, my distinguished colleague and pal in Psychology (Kruger and Liebeskind, 1984). I also returned to our rat brain atlas material after working with Sidney Landau on the neuroscience component of a Wiley dictionary in 1986. When Landau moved to Cambridge University Press (CUP), he convinced me to publish the material accumulated for our stereotaxic atlas. After some discussions with Larry Swanson at the Salk Institute (whom I met when he was a postdoc in Max Cowan’s lab), I phoned Sam Saporta in Tampa, with whom I had initiated this project when he was a postdoc in my lab. We agreed to move forward with what we nicknamed “The Ratlas”—a title unfortunately nixed by the CUP “syndicate” just before going to press. The final product (Kruger, Saporta & Swanson, 1995) contained a compact series of closely spaced, labeled photomicrographs of fiber and cell-stained matching sections in the three major axes with a text explaining the principles employed for nomenclatural assignments. Unfortunately, CUP failed to get the atlas reviewed in Science or Nature, and it was not marketed energetically, although reviews in smaller journals were consistently positive. A larger format atlas by Paxinos and Watson containing far fewer photomicrographs but numerous drawings of outlined structures remained far more popular. Also, Swanson soon followed with an excellent, huge new outline atlas of his own using an advanced and freshly reasoned large format that proved successful. Although still accessible, sales of our atlas have dwindled as it became apparent that labeled photos without outline drawings was not the wave of the future and certainly not a commercial success. Nevertheless, this did not deter later successful book projects (Kruger, 1996b, 2001; Kumazawa et al., 1996).

Deafferentation

By the mid-1980s, the activities of my lab had shifted primarily to the peripheral nervous system and to electrophysiological studies of the spatial organization of cutaneous sensitive mechanoreceptors (Castiglioni and Kruger, 1985; Kruger, 1983; Ray and Kruger, 1983, 1985). I soon learned that the directional effects of hair stimulation were largely determined simply by the pattern of hair innervation, such that the nerve spike sequence was reversed when moving in the opposite direction. Recruiting new people, the morphological studies soon dominated my interests, and postdoc Barbara Rodin wanted to pursue her behavioral observations on deafferentation with anatomical studies of the putative sprouting that might account for the apparent self-mutilation of denervated limbs. We learned that axonal transport labeling did not support earlier reports of putative sprouting (Micevych et al., 1986; Rodin and Kruger, 1984a; Rodin et al., 1983) and soon became immersed in controversy concerning whether deafferentation leads to pain, thus explaining the self-mutilation of denervated limbs in rats. Rodin discovered that simply housing males and females together eliminated the strange self-mutilatory behavior. We submitted a paper to the journal Pain that editor Patrick Wall rejected, strenuously defending his belief that denervation elicits pain and unpersuaded by the private facetious suggestion that “love conquers all.” We responded by assembling discordant findings and submitted an extensive review elsewhere (Rodin and Kruger, 1984a). The debate eventually ended in heated controversy with Wall at a conference in Alsace (Kruger, 1991). I knew Wall from Yale, where he was an instructor whom I had admired enormously in the neurophysiology course, and I had fond memories of his quirkiness as well as his inspirational arguments. He was already embroiled in controversy, initially in his futile denial of the existence of specific nociceptors (a view that I too had once erroneously supported), and then more recently in defense of his “gate control” theory, the details of which were in serious conflict with several findings concerning dorsal horn organization from Ed Perl’s lab. Wall’s ideas were widely admired among pain clinicians at that time, and the combative exchanges were less than pleasant, enduring for another decade when Perl and I joined in writing an historical account (Perl and Kruger, 1996). But one learns from such experiences that insights derived from original observations, rather than competing ideas, constitute the principal propelling force of scientific progress. Final judgment of such controversies must await the hindsight of future students.

Labeled Pathways and Pain

Axonal labeling and the effects of selective denervation became the promising morphological tools for exploring peripheral nociceptors. With the help of a talented electron microscopy technician from China, Yung Yeh, and new colleagues using the new tools of immunohistochemistry, we propitiously timed applying these powerful methodological advances to the study of the somatosensory system. We began with the inner surface of the tympanic membrane of the rat, which (although sparsely innervated) is supplied solely by C-fibers. We first did an EM study of the readily characterized “nociceptive” endings of this structure and also examined the effect of sympathectomy (which was negative for the epithelial innervation) and the effect of neonatal capsaicin treatment (which selectively destroys thin sensory fibers). These important findings were most gratifying (Yeh and Kruger, 1984), providing new insights and incentive to pursue such methods and combine them with peptide antibody labeling in cutaneous fibers (Kruger et al., 1985).

My research direction was now moving toward newly emerging molecular tools. During this period Nick Brecha was recruited to the VA Hospital and the Department of Medicine at UCLA to establish a lab to study peptidergic innervation of the gastrointestinal (GI) tract and to continue his studies of peptides expressed in the retina. I soon started working with him and the young people in his lab, enabling us to visualize the substance Pimmunoreactive epidermal innervation and also to eliminate these fibers by neonatal capsaicin treatment (Kruger et al., 1985). When Catia Sternini in Brecha’s lab developed a robust antibody to calcitonin gene-related peptide (CGRP) by conjugation to limpet hemocyanin, we decided to explore distribution patterns of this peptide as a possible nociceptive fiber marker throughout the body as well as in the central nervous system. We already had clues about the importance of CGRP (the earliest example of alternative gene expression) from Larry Swanson at the Salk Institute, who was working on its expression in the brain with Geoffrey Rosenfeld at UCSD. The effectiveness of Catia’s antibody in withstanding some limitations of routine immunohistochemistry in aldehyde-fixed tissues, a seemingly small technical advance, profoundly accelerated her career as a leader in gastroenterology research and enabled us to progress rapidly. I also formed a close friendship with Patrick (Pat) Mantyh, who introduced receptor-binding techniques to Nick’s lab. I became intrigued with how these techniques might identify the functional (but non-synaptic) tissue targets of the peptides we were visualizing. Pat was surveying sections of entire animals and asked me to see if together we could make sense of the odd array of putative tissue targets for atrial natriuretic factor (ANF), a peptide expressed by right atrium cardiomyocytes. Aside from expected localization sites in the kidney, there were several puzzles, e.g., sites in brown fat pads and endocrine organs. I enjoyed the challenge of returning to my early physiology training and examined tissues of the entire body in several species including humans (Mantyh et al., 1986) and also in the brain (Mantyh et al., 1987). Pat was enormously inventive as well as energetic, and he managed to obtain surgical specimens from human cases of ulcerative colitis and Crohn’s disease, which provided the first evidence of quantitative changes in substance P binding levels in small blood vessels and lymph nodes in the pathological tissues (but not changes in other relevant peptides). I found great pleasure in working with Pat and his brother Chris (Gates et al., 1988). The insight gained from this diversion was far more important for the future direction of where I was headed than I could have realized at the time (Kruger and Mantyh, 1985), and it led Pat to examine alterations in peptide receptor-binding sites in disease (Mantyh et al., 1988a, 1988b, 1994). After leaving UCLA, he made important strides with an animal model of bone cancer pain.

Our first papers reported the CNS distribution of the CGRP components in the somatic pathways traceable to the rat thalamus and provided further evidence that the “pain” pathway was somewhat distinct from the “classical” somatic afferent system (Kruger et al., 1988a). Comparison of CGRP immunoreactivity with its receptor-binding sites (Kruger et al., 1988b) revealed unexplained “mismatches” that we explained in “quasi-hormonal” terms.

By this time, having reached the decision to focus on the versatile and idiosyncratic molecular biology of nociceptors, I had the good fortune of joining Gerald Edelman’s newly formed Neuroscience Institute at Rockefeller University, a “think tank,” where on sabbatical leave for several months I was able to confer with various experts. This proved a valuable respite from the mind-set of bench work, and it enabled me to prepare a new NIH proposal devoted to what seemed some critical questions in the anatomy related to pain This resulted in my receipt of an NIH Jacob Javits Award, which provided generous support for my next decade of research. Among the several other dividends of being in New York was learning from Jane Dodd and Tom Jessell at Columbia University, about their survey of monoclonal antibodies relevant to sensory ganglion cells, which included new insight into glycoconjugate expression. Returning to UCLA, I was joined by a truly brilliant and talented Johns Hopkins medical student, Jim Silverman, a precocious pianist who shared my passion for music and possessed a fierce, expansive, and open intelligence. He was interested in everything emanating from my lab. The decalcification of whole rat heads enabled examination of the peptidergic innervation of the interior of teeth, bones, and other tissues of special interest, including cornea and tympanic membrane. These tissues (and later the testicular wrapping) proved to be excellent transparent specimens for thin whole-mount preparations and allowed detailed topographic analysis. Jim decided to explore galactose epitopes, and we started reading about lectins together as he started testing relevant candidates. This later led to finding lectin substitutes for FRAP-like staining in nonrodent mammals, solving the mystery of its seeming absence in these animals (Silverman and Kruger, 1988a, 1988b). Eventually, we realized that lectin-positive sensory ganglion cells and their axons constituted a distinctive phenotype of the thin fiber population associated with nociceptors, as discussed below.

The study of CGRP innervation in the peripheral nervous system, employing the strategy of examining the entire body of small rodents, altered my outlook on the meaning of peptide targets. We were soon discovering specialized regions in decalcified heads that revealed unexpected patterns lacking in conventional accounts. If there was a moment resembling an epiphany, it was when we examined the amazingly rich CGRP innervation of teeth, especially the molars. The molars contained fibers seemingly entering all the dentinal tubules. The quantity of dentinal tubule fibers in molars exceeded the number in “biting” teeth, skin, tongue, and even the cornea (Silverman and Kruger, 1987). Although the corneal surface plays a critically necessary role in detecting, and protecting from, potentially damaging stimuli, the interior of the enamel of most molar teeth would rarely, if ever in a lifetime, be exposed to noxious stimuli. This seemed to make little sense from a functional point of view because the tooth pulp and the dentinal tubules of the grinding teeth presented the densest innervation anywhere in the body. Yet these were among the least likely loci to be exposed to sensory stimuli of any imaginable kind! I soon learned from dentist colleagues that denervation of teeth often leads to their fracture and deterioration, but it was not obvious why the interior of the most densely mineralized tissue of the body would require more than a few nociceptive axons for signaling noxious stimuli, axons that would never be excited from the interior of most teeth. We proceeded with an extensive account of the variety of peripheral patterns of CGRP innervation where the functional role might not be limited to pain per se. In describing cutaneous and deep limb structures, we acknowledged that periosteal sensory fibers could be excited by a strong mechanical blow to the limb, but we questioned why the interior of long bones required such sensory nerve supply (Kruger et al., 1989). I opined that this meant that the thin “sensory” fibers in the interior of bones, as in teeth, must surely be specialized for an effector “trophic” function, although Mantyh consistently maintained they were important for nociception (Kruger and Mantyh, 1985; Mantyh et al., 1994). Indeed, he later proved his point in a series of contributions from his lab in Minnesota. Our collaboration was one of my richest learning experiences, as well as the basis for a highly gratifying friendship.

We were aware that CGRP immunoreactive fibers were rich in the vicinity of blood vessels, but we had never seen anything even vaguely suggestive of a synaptic contact with a vessel wall despite the presence of dense peptide receptor-binding sites. What if the several peptides then called “sensory peptides” were not sensory at all but served their known vasoactive function? It suddenly appeared possible to question whether “pain” fibers were principally serving a sensory role or an efferent effector role via the nonsynaptic terminal release of peptides that would reach distant specific peptide receptorbinding sites. This idea would also explain the multiplicity of neuropeptides and their various receptor-binding sites. The rich supply of peptide-containing “sensory” fibers terminating near blood vessels might be perpetually functionally active by controlling blood flow via regulation of smooth muscle wall elements and controlling permeability of capillary endothelium. Different peptides would have various functional requirements. This idea also seemed consistent with the specificity of receptor-binding site labeling patterns for different peptides. Most importantly, a continuous effector role might account for the vast number of thin “sensory” fibers that would never be activated, except in the rare event of a potentially noxious stimulus that might elicit pain. The idea that sensory ganglion cells, which we had called “nociceptors,” were normally and principally serving an effector role, and only rarely serving as detectors of noxious stimuli that might lead to the complex response known as pain, was first presented at an international meeting of pain researchers at Lake Louise, Canada (Kruger, 1987, 1988). There I suggested we recognize the role of the vast thin fiber system as “noceffector,” in recognition of their principal role. The neologism received an understandably cool reception from pain researchers unwilling to give up the sensory status of axons derived from sensory ganglion cells, but the concept was readily accepted.

We soon became immersed in further analysis of the distribution of CGRP in peripheral tissues because we predominantly labeled the small sensory ganglion cells and their thin-fiber axons associated with nociceptors. We then compared these tissues with others in a search for molecules specific to the “pain” pathways. This initiated Jim’s energetic efforts to identify those epitopes underlying FRAP-like staining in the dorsal horn of rodents that ultimately led to characterization of this phenotype in several mammals, including humans (Silverman and Kruger, 1988a). This also led to further analysis of the selectivity of thin fibers to various structures employing specific lectin “markers,” and to the realization that the IB4 lectin-positive sensory ganglion cells constitute another distinctive nociceptor population that is unrelated to the peptidergic-innervated blood vessels. Armed with Catia’s “super” CGRP antibody, and exploiting whole-mount preparations (e.g., cornea and tympanic membrane), we embarked on exploration of other botanical lectins specific to sensory neurons, which was a key important step in identifying nociceptor subclass markers (Silverman and Kruger, 1990a, 1990b). This work resulted from the rash of original findings and from some new ideas about nocicieptor functional classification and anatomical distribution alluded to above. It culminated in a particularly arduous, but rather complete account, of the distribution of peripheral “sensory” fiber distribution, especially the rich variety of CGRP fibers in the head. This provided even more numerous examples of structures that were not likely to be sources of “pain,” including autonomic ganglia, the broad variety of chemosensory epithelia that we had reviewed for a handbook (Kruger and Mantyh, 1989), and even the acoustic and vestibular apparatus (Silverman and Kruger, 1989, 1990a).

The enormously interesting details of this work serve as testimony to the scholarly energy of Jim Silverman, who returned to Johns Hopkins to complete his medical degree and ultimately entered a neurology residency in St. Louis. My close personal involvement with him and the psychiatrists dealing with his anorexia and other psychiatric problems left me profoundly depressed for some time when I learned of his suicide, the sadness of having failed a talented, brilliant mind. Without the stimulus of a capable, younger mind unintimidated by the emerging wonders of molecular biology, my momentum inevitably wavered and waned, but I was fortunate to hook up with Jen Yu Wei, who came to UCLA from Dick Burgess’s lab. He was exceptionally adept at C-fiber recording and readily persuaded to the “noceffector” concept, which enabled productive collaborative efforts, including early attempts to ascertain peptidergic control of mast cells (Kruger and Wei, 1991; Wei et al., 1992, 1994). He later exploited his expertise in supervising my final Ph.D. student, David Adelson, whose fine thesis work in splanchnic C-fibers revealed their sensitivity to reactive oxygen species and their polymodal character (Adelson et al., 1996, 1997).

Nociceptor Morphology

An earlier serendipitous meeting with Takao Kumazawa, through Ed Perl, suggested that perhaps the ideal preparation for studying nociceptor fine structure might be the specialized layer of specific “polymodal” nociceptors on the surface of the testis tunica vasculosa of dogs. Kumazawa’s lab had begun characterizing these, recording from single fibers in an in vitro preparation. An invitation to work in Kumazawa’s lab in Nagoya led to tantalizing initial electron microscopic findings (Kruger et al., 1988a) and repeated visits to Japan. Two visits included my wife and provided opportunities for unforgettable tourism in that beautiful and extraordinarily hospitable country. When Kumazawa was forced into mandatory “retirement” on the day of his 65th birthday, the project continued in what became the laboratory of his student and successor to his chair, Kazue Mizumura, the first woman neurophysiologist in Japan to reach this status. This seemed destined to become a long, ambitious project, but a fruitful one.

At UCLA we had applied lectin and peptide labeling to peripheral nociceptors in whole-mount preparations of the tunica vasculosa of the rat testis and found a striking dichotomy between the specific distribution of peptidergic and lectin-positive termination sites as well as selective ganglion-cell labeling (Silverman and Kruger, 1988b). The perivascular distribution of CGRP peptide-labeled fibers in the testicular whole-mounts was distinct from the distribution in lectin-labeled fibers. I had already obtained successful electron micrographs of the electrophysiologically characterized and marked receptive fields from the dog testis experiments in Kumazawa’s lab (Kruger et al., 1988a). Having markers for two distinct populations of nociceptors seemed an exciting prospect, but it was apparent that the peptide labels would prove complicated, as studies of the densities of neuropeptide receptor-binding sites in the spinal cord of arthritic rats were reduced for several peptides but surprisingly not for CGRP (Mantyh et al., 1988a). Pursuit of this project became a prolonged arduous task, and the EM reconstruction became my final laboratory venture, as described below (Kruger et al., 2003a).

Italy

My final sabbatical (1989–1990) was spent in Marina Bentivoglio’s lab in Verona learning new EM labeling methods with Giancarlo Balercia and reviewing joint interests with Marina (Balercia et al., 1992; Bentivoglio et al., 1991). Ginny and I found immersion in Italian life, especially the camaraderie, food, and music, one of our happiest and most productive experiences, not least of which were the enduring friendships and a habit of subsequent Italian summer vacations. I also loved the bemused tolerance of the Italians when I attempted lectures brutalizing their language. Interspersed time was spent in Milan where a musical friend, Alfredo Leonardi, Associate Director of the Mario Negri Institute, was consistently able to arrange concert and opera tickets at the Teatro alla Scala. He introduced me to Caterina Bendotti in his Institute, who serendipitously was in need of my anatomical expertise. Working with her in Milan and learning methodologies for in situ hybridization by studying the neuronal growth marker GAP-43 mRNA in the adult brain provided a propitious introduction to the wonders of gene expression. Initially, I couldn’t make sense of the pattern nor devise a sensible hypothesis relating to the earlier immunoreactivity findings. On returning to UCLA I obtained two additional probes from Rachel Neve, reconfirmed the findings and prepared extensive autoradiographic illustrations (Kruger et al., 1992, 1993). Then it suddenly dawned on me that the simplest, most parsimonious explanation of select labeled granule cell populations must lie in the concept of continuous growth in adult axons. The idea derived from the enormity of the cerebellar granule cell’s fiber expanse as well as the pattern in the hippocampal CA3 field. The submitted lengthy paper was accepted with most gratifying reviews and editorial praise, and I seemed to have come “full circle” with the “continuous growth” hypothesis. But I did nothing to “advertise” the idea and, to my great disappointment, later articles citing the paper seemed to have missed the point. The discouragement added to the frank depression I suffered following Jim’s death. My final anatomy student, Daphne Bolden, continued with these probes in sensory and autonomic ganglia for her thesis (Bolden et al., 1996), but it was becoming increasingly evident that my training was inadequate for the oncoming explosion of molecular biology techniques. Within a decade, in vivo neurite fluorescence enabled direct visualization of the dynamics of axon growth with elegant 2-photon videomicroscopy.

Neuropathic Pain

Extending into my sixties, I decided to venture into devising a new model of painful neuropathy, stimulated by the confluence of several ideas, people, and circumstances. An animal model for producing a painful mono-neuropathy had been developed at NIH by Gary Bennett who simply tied several loose sutures around the rat sciatic nerve. This resulted in nerve swelling accompanied by limb withdrawal when the affected foot was exposed to innocuous tactile and thermal stimuli. I had long puzzled about the role of the perineurial epithelial sheath, in part due to conversations with Rafael Lorente de Nó, whom I lunched with regularly during his declining years at UCLA. Rafael had published pioneering work on the ionic mechanisms of nerve conduction in desheathed nerves some 50 years earlier and was still obsessed by this subject. He called my attention to how, upon slitting the perineurial nerve sheath, fluid emerged under pressure as the fibers splayed through the opening. I had seen this again recently at the lab bench with Wei and Adelson, and I had wondered about the source of the intraneurial pressure. I also became aware of clinical observations of painful nerve entrapment and serendipitously (once again) was approached by Jack McDonald, then Chair of Anesthesiology at Ohio State, who arranged his sabbatical year with me. Jack had established an impressive clinical reputation employing peripheral nerve block for painful compression neuropathies, and he agreed to join us in devising a satisfactory method for measuring intraneurial pressure. We recruited for this task the ingenuity of engineer Arnold Lee in anesthesiology. The project was hardly trivial, and together we exerted considerable effort foundering with measurements but ultimately abandoned the project. Nevertheless, I did entice my postdoc, Tony Mosconi, to divert some of his effort to EM examination of nerve entrapment “compression.” Rather than tying a series of loose ligatures, as in Bennett’s model, we applied longitudinally split polyethylene tube “cuffs” of various internal diameter to control the magnitude of sciatic nerve compression and to observe related behavioral effects. To our surprise, compression was not the critical factor. Cuffs ranging from loose bracelets to tight constrictions consistently produced pain-like behavior, and Tony proceeded with an attempt to correlate nerve fiber morphological changes with pain behavior. A crude correlation of altered nerve fiber spectrum with “pain behavior” proved unpersuasive (Mosconi and Kruger, 1996), but we had devised a controllable new experimental animal model of peripheral neuropathy-induced pain that remains in use in the lab of my close colleague Igor Spigelman (Neubert et al., 2000). Failure to obtain suitable intraneurial pressure measurements, McDonald’s departure, and Lee’s sudden death made abandoning this failing project inevitable, and I felt obliged to evaluate seriously my future plans.

My NIH pain grant renewal application was voted a second Javits Award by the Study Section, enabling continued support, but I was aware of running low on steam and self-esteem as a result of the unpromising future of the neuropathic pain project, especially after Mosconi and my EM technician found tenure-track teaching positions in southern California. Reaching the age of 65 suddenly underscored the need to ponder the future just as a propitiously timed University “Very early retirement incentive program” provided several incentives for replacing costly full-time positions by younger faculty with growth potential. My department (now Neurobiology) was in serious turmoil downward and in need of fresh talent. Our other retirement-age faculty were already long beyond their period of NIH grant support, and their contributions to teaching was also in obvious decline. My interest in teaching had declined as well, and the offered incentive of a “Recalled-Emeritus” position with gradually diminishing teaching obligations over a 5-year period and a full pension proved quite tempting. A generous recall stipend, supported incrementally from my extramural grant funds as my teaching dwindled, rendered the decision rather irresistible. Discussing the matter with Ginny, we agreed that it was indeed apposite to plan the “retirement” that neither of us had contemplated seriously, recognizing that the putative “golden years” would prove meaningless without a productive lifestyle. Ginny had returned to work earlier as we approached the costly college years of our girls, and she had grown into a gratifying niche in the office of an LA County Supervisor. Her work focused largely on mountain open-space protection, and she then became deeply immersed in the County museums as well as art and music issues, a job for which she proved ideally suited and that also enriched both our lives.

The decision proved easier than I imagined, enabling gradual winddown of lab operations, the making of arrangements for my associates, and the possibility of dedicating myself primarily to serial reconstruction of characterized nociceptor terminals while preparing for future research and writing activities. I pragmatically arranged with Alan Light and his expert EM technician Anahid Kavookjian to continue with the serial thick and thin sectioning of nociceptor receptive field “spots” that had been delimited and marked while in Japan. The trips and long-distance Chapel Hill interactions fared better than working in relative isolation. Much of the task required gaining skill in using software for serial reconstruction that, with impatient perseverance, finally enabled me to characterize and illustrate the illusive “pain” sense organ, whose fine structure was inadequately understood. It was probably the most time-consuming project of my entire career (Kruger et al., 2003a).

The long-accepted designation of nociceptors as “free” nerve endings was misleading and inaccurate. Each axon remained ensheathed in thin Schwann cell processes that extended to its ending. There is little in life that is truly “free.” Most interesting and unexpected was the generally ignored elaborate membranous and ultimate vesicular network within the most distal part of the terminal. The network was continuous with narrow strands of the smooth endoplasmic reticulum within axons that had been recognized decades earlier by Droz as the “axonal reticulum.” But the axons were not easily identified as ending in a granular arrangement without serial sections. The atypical axolemmal accumulations of uniform, clear, spherical “synaptic” vesicles could only be established by serial reconstruction. These are clearly non-synaptic vesicles, and they are distinct from the granular variety we had already shown to contain peptides by EM labeling and that have distant targets identifiable by their receptor-binding sites (Kruger, 1996a; Kruger and Halata, 1996). The functional significance of the nociceptor axonal reticulum and granules and their relation to clear vesicles remains ambiguous. But these findings led to writing a modern account of sensory terminals and their variety of vesicular arrangements with colleagues active in the field, Felix Schweizer and Alan Light (Kruger et al., 2003a). This was for a “festschrift” dedicated to the original discoverer of synaptic structure, my Yale neuroanatomy teacher, Sanford (Sandy) Palay. “Winding down” from my original scientific trajectories, I was drawn into joining other lab programs where my anatomical expertise was needed, and I soon became involved with the morphological analysis of Brian Koos’s interesting exploration of the role of the thalamus in control of respiratory function in newborn sheep and specifically the contribution of adenosine receptors (Koos et al., 1997, 1998, 2000). I also more energetically turned my attention to several promising original neuroscience history projects that I had held in abeyance, should they remain unexplored. These concerned the seventeenth-century development of comparative neurology and its subsequent impact on early animal experimentation (Kruger, 2003, 2004, 2005; Kruger and Swanson, 2007). I also became more deeply involved through service on the History Committee of the Society for Neuroscience (SfN), including a period as Chair, which brought (thanks to the efforts of Gordon Sheperd) the opportunity to join with 17 national scientific organizations in setting up “recent” history Web sites for our respective disciplines. This was organized and funded by the Sloan Foundation, inspired by their belief that the Internet would be required as a storage medium in the digital age and that we might otherwise witness the disappearance of our historiographic documentation. They encouraged each society to devise and implement its own approach, later gathering us together for evaluation and future planning. I enjoyed this exercise immensely for the 2 years that were devoted to building the initial Society for Neuroscience’s Web site for Recent Neuroscience (WReN). Having served for 4 years on the initial Council of the SfN, and having served a term on most of the committees over the years, this seemed a logical finale.

The return to history pursuits in my “waning” years encouraged me to follow up on other neglected aspirations from the past. It maintained the discipline of going to “work” on a daily basis, but with freedom to indulge diverse interests, especially my passion for music and art. The latter was fostered by finding a copy in the UCLA Library of the history of cinematography written in French in the 1920s by Lucien Bull (assistant to Marey, the Collège de France Professor of Physiology in the late nineteenth century). It was Lucien who had befriended me when I arrived at the Institut Marey in 1958. He had remained active into his eighties, in addition to writing a history of cinematography. I was soon immersed in examining the history of multiple frame imaging from Marey’s perspective, as a physiological recording device, but also in the context of modern knowledge of how we observe the world in frames between saccades. Learning that the Getty Research Institute in Los Angeles was planning a year-long theme, “Frames of Viewing,” a colleague recommended my inclusion as a resident scholar. To my amazement and delight I was invited to be the solitary neuroscientist Getty Scholar among 12 art “historians” in 2001–2002. This shifted my interests to reading recent literature on the neural mechanisms underlying human vision, and it fostered an intense interest in the recent evolution of the art world and its scholarly activities, though I did wander at times into arenas related to neuroscience (Kruger, 2005). My current scholarly activity is devoted largely to more recent perspectives that an aging neuroscientist might bring to the profound change in modern understanding of synaptic and non-synaptic neuraI interaction (Kruger and Otis, 2007) as well as to more recent perspectives that I might bring to understanding artistic expression. Having formed fulfilling collegial friendships at the Getty Research Institute, my latter years have been immeasurably gratifying enriched by interaction with their programs and facilities.

Looking back on over 50 years of active neuroscience research, I realize that much of the most joyous and precious aspects of the quest for discovery were the shared moments, whether as student, coinvestigator, or teacher. Our academic positions (and salaries) have largely been justified by lecturing increasingly larger classes of professional students of medicine and dentistry in steadily diminishing hours—despite the enormous expansion of knowledge. The joy of “teaching” is found in the intimate moments of interactive intellectual experience and discourse that derive from training and collaboration. The richest gratification has been the individual contacts with faculty colleagues, postdoctoral, and graduate students and the mentoring of undergraduates undertaking a project in my lab. Several of these proudly published papers as sole or lead author. A few recently have touched me in expressing their appreciation by honoring me with the endowment of a student neuroscience scholarship in my name at UCLA, one of the most gratifying of the pleasures of our profession. Of course, nothing quite beats the exhilaration of vigorous “journal club” discussions of recent critical papers or, best of all, the bench discovery of something wondrously beautiful and unexpected, the best motivation for a career in neuroscience

Writing a memoir, in the opinion of novelist Ian McEwen, is to “become an employee of your former self.” This is someone horribly difficult to accommodate, especially when somewhat older and wiser. Having indulged in the athleticism of self-recognition, this exercise emerges as somewhat dismaying because of its dearth of shared anecdotes that would probably be of greater interest to modern readers than my research contributions. Looking back has enabled me to recognize that everyone has his own ghosts, and mine were notably the illness and demise of productive minds that participated prominently at critical times in my career, thereby shaping shifts in direction. My career immersion in attempting broad “hands-on” versatility perhaps would not be countenanced favorably in the modern era, nor would funding be accessible without tight boundaries of research interest. Yet I was permitted the adventure of dabbling in several distinct fields, which provided a constant stimulus for learning new techniques and challenging the hypotheses of the ever “new” neurobiology. The adventure and thrill of each discovery becomes ephemeral retrospectively because its impact seems progressively less important. Even the most profound advance in twentieth-century biology, the “discovery” of the structure of DNA, surely would soon have been uncovered without Watson and Crick. By the same token, technological progress usually provided the landmarks of new discovery and research direction in neuroscience. What Henry James, a century ago, called “the poor, palpable, ponderable, probeable laboratory brain” remains the most challenging subject of scientific inquiry. Perhaps each account of earlier careers may illuminate some of the larger changes in the ongoing development of neuroscience research.

Selected Bibliography

Adelson DW, Wei JY, Kruger L. Sensitivity of splanchnic afferent C-fiber units in vitro. J Neurophysiol 1996;76:371–380.

Adelson DW, Wei JY, Kruger L. Warm-sensitive splanchnic C-fiber units in vitro. J Neurophysiol 1997;77:2989–3002.

Albe-Fessard D, Kruger L. Dualité des réponses des cellules du centre median du thalamus à des stimulations naturelles ou electriques. Acad Sci 1959;248:299– 301.

Albe-Fessard, D, Kruger L. Duality of unit discharges from cat centrum medianum in response to natural and electrical stimulation. J Neurophysiol 1962;25:3–20.

Balercia G, Bentivoglio M, Kruger L. Fine structural organization of the ependymal region of the paraventricular nucleus of the rat thalamus and its relation with projection neurons. J Neurocytol 1992; 21:105–119.

Bentivoglio M, Balercia G, Kruger L. The specificity of the nonspecific thalamus: The midline nuclei. In Holstege G, ed. Prog Brain Res 1991;87:53–80.

Berman AJ, Kruger L, Fulton JF. Recovery of function following lesions of frontal agranular cortex in monkey. Tr Am Neurol Assn 1954;79:178–180.

Bolden DA, Sternini C, Kruger L. GAP-43 mRNA and calcitionin gene-related peptide mRNA expression in sensory neurons are increased following sympathectomy. Brain Res Bull 1996;42:39–50.

Castiglioni AJ, Kruger L. Excitation of dorsal column nucleus neurons by air-jet moving across the skin. Brain Res 1985;346:348–352.

Durham D, Woolsey TA, Kruger L. Cellular localization of 2-[2H] deoxy-D-glucose from paraffin embedded brains. J Neurosci 1981;1:519–526.

Feldman SG, Kruger L. An axonal transport study of the ascending projection of medial lemniscal neurons in the rat. J Comp Neurol 1980;192:427–454.

Feldon S, Feldon P, Kruger L. Topography of the retinal projection upon the superior colliculus of the cat. Vision Res 1970;10:135–143.

Furstman L, Saporta S, Kruger L. Retrograde axonal transport of horseradish peroxidase in sensory nerves and ganglion cells of the rat. Brain Res 1975;84:320–324.

Gates T, Zimmerman R, Mantyh C, Vigna S, Welton M, Passaro E Jr, Maggio J, Kruger L, Mantyh P. Receptor binding sites for substance P are ectopically expressed in high concentrations by arterioles, venules and lymph nodules in surgical specimens obtained from patients with inflammatory bowel disease. In MacDermott, RP, ed. Mechanisms of chronic infection and inflammation, Int. Symp. on Future Research Approaches in Inflammatory Bowel Disease. Amsterdam: Elsevier, 1988;37–42.

Golovchinsky V, Kruger L, Saporta S, Stein BE, Young DW. Properties of velocitymechanosensitive neurons of the cat ventrobasal thalamic nucleus with special reference to the concept of convergence. Brain Res 1981;209:335–376.

Heric T, Kruger L. Organization of the visual projection upon the optic tectum of a reptile (Alligator mississippiensis). J Comp Neurol 1965;124:101–112.

Heric TM, Kruger L. The electrical response evoked in the reptilian optic tectum by afferent stimulation. Brain Res 1966;2:187–199.

Kenton B, Kruger L. Information and transmission in slowly adapting mechanoreceptor fibers. Exp Neurol 1971;31:114–139.

Kenton B, Kruger L, Woo MY. Two classes of slowly adapting mechanoreceptor fibres in reptile cutaneous nerve. J Physiol (Lond) 1971;212:21–44.

Kerr FWL, Kruger L, Schwassmann HO, Stern R. Somatotopic organization of mechanoreceptor units in the trigeminal nuclear complex of the macaque. J Comp Neurol 1968;134:127–144.

Kirkpatrick DB, Kruger L. Physiological properties of neurons in the principal trigeminal nucleus in the cat. Exp Neurol 1975;48:664–690.

Koos BJ, Chau A, Matsuura M, Punla O, Kruger L. A thalamic locus mediates hypoxic inhibition of breathing in fetal sheep. J Neurophysiol 1998;79:2383–2393.

Koos BJ, Chau A, Matsura M, Punla O, Kruger L. Thalamic lesions dissociate breathing inhibition by hypoxia and adenosine in fetal sheep. Am J Physiol 2000;278: R831–R838.

Koos BJ, Kruger L, Murray TF. Source of extracellular brain adenosine during hypoxia in fetal sheep. Brain Res 1997;778:439–442.

Kruger L. Characteristics of the somatic afferent projection to the precentral cortex in the monkey. Am J Physiol 1956;186:475–482.

Kruger L. The thalamus of the dolphin (Tursiops truncatus) and comparison with other mammals. J Comp Neurol 1959;111:133–194.

Kruger L. Morphological alterations of the cerebral cortex and their possible role in the loss and acquisition of information. In Kimble, DP, (ed). The Anatomy of Memory, Science and Behavior Books, Palo Alto,CA. 1966:88–139.

Kruger L. Specialized features of the cetacean brain. In Norris, KS, ed. Whales, dolphins and porpoises. Los Angeles: University of California Press, 1966;232–254.

Kruger L. Experimental analysis of the reptilian nervous system. Ann NY Acad Sci 1969;167:102–117.

Kruger L. The topography of the visual projection to the mesencephalon. A comparative survey. Brain Behav Evol 1970;3:169–177.

Kruger L. A critical review of theories concerning the organization of the sensory trigeminal nuclear complex of the brain stem. In Dubner R, Kawamura Y, eds. Oral-facial sensory and motor mechanisms. New York: Appleton-CenturyCrofts, 1971;135–158.

Kruger L. Functional subdivisions of the brain stem sensory trigeminal nuclear complex. Adv Pain Res Ther, 1979;3:197–209.

Kruger L. Information processing in cutaneous mechanoreceptors: Feature extraction at the periphery. Fed Proc 1983;42:2519–2520.

Kruger L. Morphological correlates of “free” nerve endings—a re-appraisal of thin sensory axon classification. In Schmidt RF, Schaible H-G, Vahle-Hinz C, eds. Fine afferent nerve fibers and pain. Weinheim, Germany, Basel, Switzerland: VCH Verlagsgesellschaft, 1987;3–13.

Kruger L. Morphological features of thin sensory afferent fibers: A new interpretation of “nociceptor” function. Prog Brain Res, Transduction and Cellular Mechanisms in Sensory Receptors 1988;74:253–257.

Kruger L. Deafferentation—The name of the game ain’t mainly in the pain. In Besson JM, Guilbaud G, eds. Lesions of primary afferent fibers as a tool for the study of clinical pain. Amsterdam: Elsevier, 1991a;117–133.

Kruger L. The “noceffector” principle and the classification of thin sensory axons. Biomed Res 1991b;12(Suppl 2):211–214.

Kruger L. The functional morphology of thin sensory axons: some principles and problems. Prog Brain Res 1996a;113:255–272.

Kruger L. Ed. Pain and touch. In series Handbook of perception and cognition 2nd ed. Academic Press, 1996b;394 pp, San Diego, CA.

Kruger L. Edward Tyson’s 1680 account of the “porpess” brain and its place in the history of comparative neurology. J Hist Neurosci 2003;12:339–349.

Kruger L. An early illustrated comparative anatomy of the brain: Samuel Collins’ A Systeme of Anatomy (1685) and the emergence of comparative neurology in 17th century England. J Hist Neurosci 2004;13:195–217.

Kruger L. The scientific impact of Dr. N. Tulp, portrayed in Rembrandt’s “Anatomy Lesson.” J Hist Neurosci 2005;14:85–92.

Kruger L., Albe-Fessard D. The distribution of responses to somatic afferent stimuli in the diencephalon of the cat under chloralose anesthesia. Exp Neurol 1960;2:442–467.

Kruger L., Bendotti C, Rivolta R, Samanin R. GAP-43 mRNA localization in the rat hippocampus CA3 field. Mol Brain Res 1992;13:267–272.

Kruger L, Bendotti C, Rivolta R, Samanin R. The distribution of GAP-43 mRNA in the adult rat brain. J Comp Neurol 1993;333:417–434.

Kruger L, Berkowitz EC. The main afferent connections of the reptilian telencephalon as determined by degeneration and electrophysiological methods. J Comp Neurol 1960;115:125–114.

Kruger L, Boname JR. A retinal excitation gradient in a uniform area of stimulation. J Exp Psych 1955;49:220–224.

Kruger L, Feldzamen AN, Miles WR. Comparative olfactory intensities of the aliphatic alcohols in man. Am J Psych 1955a;68:386–395.

Kruger L, Feldzamen AN, Miles WR. A scale for measuring supra-threshold olfactory intensity. Am J Psych 1955b;68:117–123.

Kruger L, Halata Z. Structure of nociceptor “endings.” In Belmonte, C, Cervero, F, eds. Neurobiology of nociceptors. Eds. Belmonte, C. & Cervero, F. Oxford University Press, 1996;37–71.

Kruger L, Hamori J. An electron microscopic study of dendritic degeneration in the cerebral cortex resulting from laminar lesions. Exp Brain Res 1970;10:1–16.

Kruger L, Henry C. Electrical activity of Rolandic region in unanesthetized monkey. Neurology 1957;7:490–495.

Kruger L, Kavookjian AM, Kumazawa T, Light AR, Mizumura K. Nociceptor structural specialization in canine and testicular “free” nerve endings. J Comp Neurol 2003a;463:197–211.

Kruger L, Kenton B. Quantitative neural and psychophysical data for cutaneous mechanoreceptor function. Brain Res 1973;49:1–24.

Kruger L, Kumazawa T, Mizumura K, Sato J, Yeh Y. Observations on electrophysiologically characterized receptive fields of thin testicular afferent axons: A preliminary note on the analysis of fine structural specializations of polymodal receptors. Somatosens Res 1988a;5:373–380.

Kruger L, Kruger, L. and J.C. Liebeskind JC. (Eds.): Neural mechanisms of pain. Advances Pain Res. Ther., 1984;6:364 pp.

Kruger L, Light AR, Schweizer FE. Axonal terminals of sensory neurons and their morphological diversity. J Neurocytol 2003b;32:205–216.

Kruger L., Malis LI. Distribution of afferent and efferent fibers in the cerebral cortex of the rabbit revealed by laminar lesions produced by heavy ionizing particles. Exp Neurol 1964;10:509–524.

Kruger L, Mantyh PW. Changing concepts in the anatomy of pain. Semin Anesthesia 1985;4:209–217.

Kruger L, Mantyh PW. Gustatory and related chemosensory systems. In Björklund A, Hökfelt T, Swanson LW, eds. Handbook of chemical neuroanatomy, Vol. 7: Integrated systems of the CNS, Part II. Amsterdam: Elsevier, 1989;323–411.

Kruger L, Mantyh PW, Sternini C, Brecha NC, Mantyh CR. Calcitonin gene-related peptide (CGRP) in the rat central nervous system: Patterns of immunoreactivity and receptor binding sites. Brain Res 1988;463:223–244.

Kruger L, Maxwell DS. Electron microscopy of oligodendrocytes in normal rat cerebrum. Am J Anat 1966a;118:411–436.

Kruger L, Maxwell DS. The fine structure of ependymal processes in the teleost optic tectum. Am J Anat 1966b;119:479–498.

Kruger L, Maxwell DS. Comparative fine structure of vertebrate neuroglia: Teleosts and reptiles. J Comp Neurol 1967;129:115–142.

Kruger L, Maxwell DS. Wallerian degeneration in the optic nerve of a reptile: An electron microscopic study. Am J Anat 1969;125:247–270.

Kruger L, Michel F. A morphological and somatotopic analysis of single unit activity in the trigeminal sensory complex of the cat. Exp Neurol 1962a;5:139–156.

Kruger L, Michel F. Physiological excitation of single elements in the trigeminal sensory complex of the decerebrate cat. A reinterpretation of the representation of pain. Exp Neurol 1962b;5:157–178.

Kruger L, Michel F. A single neuron analysis of the buccal cavity representation in the sensory trigeminal complex of the cat. Arch Oral Biol 1962c;7:491–503.

Kruger L, Otis TS. Whither withered Golgi? A retrospective evaluation of reticularist and synaptic constructs. Brain Res Bu11 2007;72:201–207.

Kruger L, Perl ER, Sedivec MJ. Fine structure of myelinated mechanical nociceptor endings in cat hairy skin. J Comp Neurol 1981;198:137–154.

Kruger L, Porter P. A behavioral study of the functions of the Rolandic cortex in the monkey. J Comp Neur 1958;109:439–470.

Kruger L, Sampogna SL, Rodin BE, Clague J, Brecha N, Yeh Y. Thin-fiber cutaneous innervation and its intraepidermal contribution studied by labeling methods and neurotoxin treatment in rats. Somatosens Res 1985;2:335–356.

Kruger L, Saporta S. Axonal transport of [³H]-adenosine in visual pathways. Brain Res 1977;122:132–136.

Kruger L, Saporta, S, Swanson LW. Photographic atlas of the rat brain: The cell and fiber architecture illustrated in three planes with stereotaxic coordinates. Cambridge, NY: Cambridge University Press, pgs. 299, 1995.

Kruger L, Silverman JD, Mantyh PW, Sternini C, Brecha NC. Peripheral patterns of calcitonin gene-related peptide (CGRP) general somatic sensory innervation: Cutaneous and deep terminations. J Comp Neurol 1989;280:291–302.

Kruger L, Siminoff R, Witkovsky P. A single neuron analysis of the dorsal column nuclei and the spinal nucleus of the trigeminal in the cat. J Neurophysiol 1961; 24:333–349.

Kruger L, Sternini C, Brecha NC, Mantyh PW. Distribution of calcitonin generelated peptide immunoreactivity in relation to the rat central somatosensory projection. J Comp Neurol 1988b;273:149–162.

Kruger L, Stolinski C, Martin BGH, Gross MB. Membrane specializations and cytoplasmic channels of Schwann cells in mammalian peripheral nerve as seen in freeze-fracture replicas. J Comp Neurol 1979;186:571–602.

Kruger L, Swanson LW. 1710: The introduction of experimental nervous system physiology and anatomy by François Pourfour du Petit. In H Whitaker, CUM, & Smith, S Finger, eds., Brain, mind and medicine: Essays in 18th century neuroscience. New York: Springer, 2007;99–113.

Kruger L, Wei JY. Noxious environmental activation of noceffector mechanisms. Environ Med (Japan) 1991;35:31–35.

Kruger L, Witkovsky P. A functional analysis of neurons in the dorsal column nuclei and spinal nucleus of the trigeminal in the reptile (Alligator Mississippiensis). J Comp Neur 1961;117.

Kruger L, Young RF. Specialized features of the trigeminal nerve and its central connections. In Samii M, Jannetta PJ. eds. The cranial nerves. Berlin: SpringerVerlag, 1981;274–301.

Kumazawa T, Kruger L, Mizumura K. (Eds.) The polymodal receptor: A gateway to pathological pain. Prog Brain Res 1996;113:547 pp.

Magalhaes-Castro HH, Kruger L. Polysaccharide and cytoplasmic changes in motoneurons during “chromatolysis” in the opossum spinal cord. J Comp Neurol 1981;196:53–72.

Malis LI, Baker CP, Kruger L, Rose JE. Effects of heavy ionizing monoenergetic particles on the cerebral cortex. I. Production of laminar lesions and dosimetric considerations. J Comp Neurol 1960;115:219–242.

Malis LI, Kruger L. Multiple response and excitability of cat’s visual cortex. J Neurophysiol 1956;19:172–186.

Malis LI, Loevinger R, Kruger L, Rose JE. Production of laminar lesions in the cerebral cortex by heavy ionizing particles. Science 1957;126:302–303.

Malis LI, Pribram KH, Kruger L. Action potentials in “motor” cortex evoked by peripheral nerve stimulation. J Neurophysiol 1953;16:161–167.

Mantyh CR, Gates T, Zimmerman RP, Kruger L, Maggio JE, Vigna SR, Basbaum AI, Levine J, Mantyh PW. Alterations in the density of receptor binding sites for sensory neuropeptides in the spinal cord of arthritic rats. In Besson JM, Guilbaud G, eds. The Arthritic rat as a model of clinical pain? Amsterdam: Elsevier Science Publishers B.V., 1988a;139–152.

Mantyh CR, Gates TS, Zimmerman RP, Welton ML, Passaro EP Jr, Vigna SR, Maggio JE, Kruger L, Mantyh PW. Receptor binding sites for substance P, but not substance K or neuromedin K, are expressed in high concentrations by arterioles, venules, and lymph nodules in surgical specimens obtained from patients with ulcerative colitis and Crohn disease. Proc Natl Acad Sci USA 1988b;85: 3235–3239.

Mantyh CR, Kruger L, Brecha NC, Mantyh PW. Localization of specific binding sites for atrial natriuretic factor in peripheral tissues of the guinea pig, rat and human. Hypertension 1986;8:712–721.

Mantyh CR, Kruger L, Brecha NC, Mantyh PW. Localization of specific binding sites for atrial natriuretic factor in central nervous system of rat, guinea pig, cat and human. Brain Res 1987;412:329–342.

Mantyh PW, Allen CJ, Rogers S, DeMaster E, Ghilardi JR, Mosconi T, Kruger L, Mannon PJ, Taylor IL, Vigna SR Some sensory neurons express neuropeptide Y receptors: Potential paracrine inhibition of primary afferent nociceptors following peripheral nerve injury. J Neurosci 1994;14:3958–3968.

Matthews MA, Kruger L. Electron microscopy of non-neuronal cellular changes accompanying neural degeneration in thalamic nuclei of the rabbit. I. Reactive hematogenous and perivascular elements within the basal lamina. J Comp Neurol 1973a;148:285–311.

Matthews MA, Kruger L. Electron microscopy of non-neuronal cellular changes accompanying neural degeneration in thalamic nuclei of the rabbit. II. Reactive elements within the neuropil. J Comp Neurol 1973b;148:313–346.

Maxwell DS, Kruger L. The fine structure of astrocytes in the cerebral cortex and their response to focal injury produced by heavy ionizing particles. J Cell Biol 1965a;25:141–158.

Maxwell DS, Kruger L. Small blood vessels and the origin of phagocytes in the rat cerebral cortex following heavy particle irradiation. Exp Neurol 1965b;12:33–54.

Maxwell DS, Kruger L. The reactive oligodendrocyte. An electron microscopic study of cerebral cortex following alpha particle irradiation. Am J Anat 1966;118: 437–460.

Maxwell DS, Kruger L, Pineda A. The trigeminal root with special reference to the central-peripheral transition zone: An electron microscopic study in the macaque. Anat Rec 1969;164:113–125.

Micevych PE, Rodin BE, Kruger L. The controversial nature of the evidence for neuroplasticity of afferent axons in the spinal cord. In Yaksh T, ed. Spinal afferent processing. New York: Plenum Press, 1986;417–443.

Miller R, Varon S, Kruger L, Coates PW, Orkand PM. Formation of synaptic contacts on dissociated chick embryo sensory ganglion cells in vitro. Brain Res 1970;24:356–358.

Mosconi T, Kruger L. Fixed-diameter polyethylene cuffs applied to the rat sciatic nerve induce a painful neuropathy: ultrastructural morphometric analysis of axonal alterations. Pain 1996;64:37–57.

Mosso JA, Kruger L. Spinal trigeminal neurons excited by noxious and thermal stimuli. Brain Res 1972;38:206–210.

Mosso JA, Kruger L. Receptor categories represented in spinal trigeminal nucleus caudalis. J Neurophysiol 1973;36:472–488.

Nagata T, Kruger L. Tactile neurons of the superior colliculus of the cat: input and physiological properties. Brain Res 1979;174:19–37.

Neubert JK, Maidment NT, Matsuka Y, Adelson DW, Kruger L, Spigelman I. Inflammation-induced changes in primary afferent-evoked release of substance P within trigeminal ganglia in vivo. Brain Res 2000;871:181–191.

Perl E, Kruger L. Nociception and pain: Evolution of concepts and observations. Pain and touch in Kruger L, ed. Handbook of perception and cognition 2nd ed. San Diego, CA: Academic Press, 1996;179–211.

Powell, TPS, Kruger L. The thalamic projection upon the telencephalon in Lacerta viridis. J Anat (Lond.) 1960;94:528–542.

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Pribram KH, Kruger L, Robinson F, Berman AJ. The effects of precentral lesions on the behavior of monkeys. Yale J Biol Med 1956;28:428–443.

Ray RH, Kruger L. Spatial properties of receptive fields of mechanosensitive primary afferent nerve fibers. Fed Proc 1983;42:2536–2541.

Ray RH, Mallach LE, Kruger L. The response of single guard and down hair mechanoreceptors to moving air-jet stimulation. Brain Res 1985;346:333–347.

Rodin BE, Kruger L. Absence of intraspinal sprouting in dorsal root axons caudal to a partial spinal hemisection: A horseradish peroxidase transport study. Somatosens Res 1984a;2:171–192.

Rodin BE, Kruger L. Deafferentation in animals as a model for the study of pain. Brain Res Rev 1984b;7:213–228.

Rodin BE, Sampogna S, Kruger L. An examination of intraspinal sprouting in dorsal root axons with the tracer horseradish peroxidase. J Comp Neurol 1983;215: 187–198.

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Silverman JD, Kruger L. An interpretation of dental innervation based upon the pattern of calcitonin gene-related peptide (CGRP)-immunoreactive thin sensory axons. Somatosens Res 1987;5:157–175.

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Susan E. Leeman

BORN:

Chicago, Illinois

May 9, 1930

EDUCATION:

Goucher College, B.A. (1951)

Radcliffe College, M.A. (1954)

Radcliffe College, Ph.D. (1958)

APPOINTMENTS:

Harvard Medical School (1958)

Brandeis University (1959)

Harvard Medical School, L.H.R.R.B. (1972)

University of Massachusetts Medical School (1980)

Boston University School of Medicine (1992)

HONORS AND AWARDS (SELECTED):

Lillian Welsh Memorial Award, Goucher College (1951)

Astwood Award, The Endocrine Society (1981)

Van Dyke Award, College of Physicians and Surgeons of Columbia University (1982)

Charles C. Pinderhughes Lecture, Boston Veterans Administration Medical Center (1984)

Christianna Smith Lecture, Mt. Holyoke College (1984) American Academy of Arts and Sciences (1987)

National Academy of Sciences, U.S.A. (1991)

Burroughs Wellcome Visiting Professorship Award, University of Kentucky (1992)

Honorary D.Sc., State University of New York, Institute of Technology at Utica/Rome (1992)

FASEB, Excellence in Science Award (1993)

Honorary Degree, Goucher College, Maryland (1993)

Fred Conrad Koch Award (1994)

197th Lilly Lecture (1994)

Fogarty Scholar-in-Residence (1994)

14th Annual Isadore Rosenberg Lecture (1999)

Mika Salpeter Lifetime Achievement Award, Women in Neuroscience (2005)

American Association for the Advancement of Science, Fellow (2007)

Susan Leeman’s research has focused on the two peptides, substance P and neurotensin, which were isolated and chemically defined in her laboratory subsequent to her detection of a sialogogic and a vasoactive substance in hypothalamic extracts. The determination of their amino acid sequences and the synthesis of these peptides have opened up fruitful fields of research for many investigators. Her recent work has explored the roles of these peptides in the inflammatory responses of various tissues.

Susan E. Leeman

I have found the task of writing my autobiography rather daunting, as I am not sure how finished I feel my life is or what it has all been about. I have conflicting and changing thoughts about my experiences, and particularly about how private to keep them. My career path has been laced with feelings from my own psychological development; and, surprisingly at my age, I continue to feel impaired by having been brought up in a sporadically dysfunctional family. How much to attribute my many times of uncertainty about my professional course to the institutions in which I have found myself working, or to general societal attitudes toward working women, and certainly women in science, and how much to attribute to my own personal issues has been a problem for me.

Whether my reflections and the recounting of my experiences will be of value to other scientists who may have periods of doubt themselves is not clear. Maybe there are others out there whose motivation has occasionally flagged, and even whose feelings have sometimes been hurt. But, on balance, I feel that there have been many rewards; and I would like to declare that, overall, I finally feel that I was worth the investment. I would like to encourage others to persevere, if they want to.

So here goes.

Early Years and Influences

I was born in Chicago in 1930. My father was a metallurgist for the U.S. Steel Company in Chicago, a job he took after leaving the Bureau of Standards in Washington. My father was a scientist with very high standards, and he was a very academically driven person. When he was 9 years old he won a medal from the New York Times for an essay on Abraham Lincoln. I came upon it in junior high school in a bureau drawer. I never spoke to my father about his prize.

My mother attended Hunter College during the flapper era. This was somewhat surprising as not many women went to college in those days. My father was 10 years older than she, and he could be very intimidating—an academic tyrant. He did not think my mother was particularly smart, although I could sense that she was.

My father’s family had emigrated from Russia to New York City when he was barely 7 years old. They were a very striving people who had been persecuted in the country they had left and wanted to do well in their new country. My father was always grateful for the opportunities that the United States had to offer; for example, he felt that paying income taxes was a privilege. He had two brothers and a sister. One of his brothers became a teacher, the other a patent lawyer, and his sister also became a teacher and a very successful poet.

I always felt myself to be a somewhat peripheral and unimportant member of the family. I had one older brother, Henry, who was born in Washington, D.C., when my father was working for the Bureau of Standards. Things were expected of my brother, but not much was expected of me. I concealed an inner “how about me?” attitude because of this, which I believe continues to this day. I did not and do not want to be overlooked, but I have found it hard to be a serious academic. I have always known that I have a very silly side.

My mother’s mother, Grandma Gittel, was from a fairly large estate in Vitebsk, Russia, the same place that Marc Chagall was from. There were no public schools. Her father had hired a tutor for the boys, her brothers, but not for the girls, and she took issue with that. At age 13, she stole money from her mother and bought a ticket to Odessa, a two-and-a-half day train trip away, to go live with relatives. She knocked on their door, explained who she was, and they took her in to be a babysitter and household help. She never saw her parents again, and that was certainly part of her lifelong depression.

The relatives in Odessa also had a dairy business that was run from their house, and my grandmother was soon incorporated there as a helper. Because she was so smart and hardworking, at age 15 she was given a cow of her own. She went on to develop her own route and create a successful business without being able to read or write. Years later, when she lived with us in Bethlehem, Pennsylvania, she used to tell me how frustrating this was for her. She had used hieroglyphics to keep the accounts of her dairy route. She would draw on a piece of paper the particular characteristics of each house; for example, a broken fence, or an asymmetric placement of the windows. With this system she was able to keep her records, make correct deliveries, and flourish as a dairymaid.

After several more years, the family began to worry about her future. She was getting older and the prospect of her becoming an old maid was fearsome. After all, she was 22 or 23! When she met a big burley, dashing Jewish soldier in the Russian army, the family advised her to accept his offer of marriage. Their words of advice to her echoed in my ears when, years later, it came time for me to consider getting married: “Who knows, maybe nobody will ever ask you again.”

She once confided in me that she hardly had known him and had considerable misgivings about the match. But, they were married; and she and my grandfather lived in Odessa for several years. There they had a baby who died. Then, around 1903, my grandfather was told that he would have to fight in the Russo-Japanese War. He decided to run away to the United States instead. He and my grandmother made plans to reunite in New York City.

My grandmother traveled by herself to Hamburg am Bremen and booked passage on a very crowded boat to the United States. She said it was a miserable trip with many seasick passengers. She landed on New York’s East Side, located my grandfather, and they began life together in the new country.

My grandfather was a boisterous man who loved music, sang Italian arias at the top of his lungs, learned to speak Italian before English—because that was the neighborhood they were living in—and earned his living as a customer-peddler. Eventually, they moved to the Bronx and had six more children. My mother, the eldest, was heavily relied upon as a housekeeper and babysitter. She was also an excellent student, graduating at the top of her class. After graduation, her father wanted her to work in a hat store. But she wanted to go to Hunter College, which was a free public school in New York. My grandmother, who had had a similar problem with her own father, supported my mother’s education and won. So my mother went to college!

After her first year, a school friend introduced my mother to my father. She was 19 years old; he was 29, a college graduate, and already started on his career. My father lived in Brooklyn and she lived in the Bronx, and there was a definite attitude on my father’s part as to who were the peasant immigrants and who were the striving immigrants of cultural superiority. My father was a Litvak—taller, blonder, more intellectual, and, in his mind, of a superior quality to my mother’s family. That was always a bit of a struggle.

My father went to City College and, when he was drafted, he was sent to Carnegie Tech in Pittsburg because he was also very smart and wanted to be a scientist. He got an education in the emergent field of metallurgy, which was of military-industrial value.

When he proposed, my mother accepted, partly to get away from home. It was 1918, and the war was over. He was then employed at the Bureau of Standards in Washington, D.C. She transferred to George Washington University and graduated from there, shortly before my brother was born in 1928. Soon, my father was offered a job at the U.S. Steel Company in Chicago, where I was born 2 years later.

When I was 6 weeks old, we moved to Columbus, Ohio, where my father accepted a job at the Battelle Memorial Institute. The focus there was more on research than his previous position had been at U.S. Steel, and he enjoyed this. But after 6 years there, the family story is that he was informed by the Battelle administration that, because he was Jewish, it was unlikely that he would advance much farther in his career there. He was still academically ambitious, so he decided to accept a job at the Bethlehem Steel Company in Pennsylvania. We moved to Bethlehem in 1936.

Somewhat before the World War II, there were very serious strikes in the steel industry. The Council of Industrial Organizations was getting the steel workers to organize. My father’s position as a researcher was neither management nor labor but somewhere in between. He felt it was very tenuous.

Bethlehem was also largely anti-Semitic. We were not allowed to join the country club; and we knew that we were second class. I remember when I was elected president of the seventh grade and a classmate, Danny W., shouted, “Hey, Jewface!” at me from across the room. I had thought that my high office had spared me from that kind of thing. We forget what a bigoted country we have been for a long time.

Well, we joined the public country club.

My mother’s mother moved in with my family in Bethlehem when I was in the fourth grade. Her sons were drafted in World War II, and she could not support herself. My father was a fairly well-recognized metallurgist by this time, and we lived a middle-class life. When she needed a place to live, he said that she could come stay with us.

My grandmother and father got to be good friends, and I think my mother was very jealous. He used to read aloud to my grandmother the Sholom Aleichem stories about the shtetl, and other tales from the Lower East Side. They seemed to be revisiting the old country together, enjoying the safety of being Jewish in our living room. I can remember the look on her face when Khrushchev came to the United States and took off his shoe and banged it on the desk at the United Nations. She had a look of such nostalgia to be hearing Russian again on the radio.

Meanwhile, my grandmother’s relationship with my mother was deteriorating. My brother and I could never figure out why. My mother was becoming more and more incapacitated. During the war, she was volunteering as a nurse’s aid, and had gone back to school to take a course in ferrous metallurgy so that she could get a research job at the U.S. Steel Company. She was a technician of sorts. On V-J Day, my mother was fired. All the women who had joined the workforce were gone, without exception. She took it badly.

My grandmother had also displaced my mother’s role in the house. After my mother was fired from her job, two women in the household became too much. Eventually, she exploded and ordered my grandmother out. Then Grandma Gittel went back to New York to live with one of the other children.

I think that my grandmother knew when the Russians killed her family back home. There was a lot of slaughter of people, but those who got to the United States were mostly O.K. We heard about the gas ovens in Europe and that millions of people were being murdered. I do not know how people in Germany claimed they had no idea what was going on, when I knew in Pennsylvania. Delegations of Jews were going to see Roosevelt to beg him to bomb the railroad tracks leading to the gas ovens, and he would not do it.

During the war, my father was very anxious. Although he was an American citizen, I think he could not be sure that he was going to be safe. The Pope never spoke out against the slaughter of the Jews, so we could not count on the church. I think I picked up this anxiety too. I can remember thinking on my way home from school, “Where would I hide?”

Bethlehem was full of people from Romania, Poland, and the Eastern European countries, which had been the most efficient at slaughtering the Jews. We lived in the Christmas city of the United States, and the Jews were thought to be Christ killers. That was another thing that would be shouted at me in school.

I can remember when my daughter Eve was invited to sing in a church at Christmas in Newton, Massachusetts, and I thought, “What?!” I had been petrified just to walk into a church. It is probably something like what Muslims feel now in our country.

I spent a lot of time as a child raising money for Israel. My mother made me go around the neighborhood selling movie tickets door-to-door. It was considered very important that there be a country for the Jews, but I hated this task. Now I look at Israel and think, “How can you be so treacherous? What are you doing building walls?” But then we thought somehow that it would spare us from anti-Semitism. Today, I continue to have mixed feelings about Israel.

In those days, Bethlehem seemed against most things that you could think of. I remember the family drama that ensued when my Aunt Molly, my mother’s sister, married Paul Robeson’s bodyguard, Homer Sadler, a Black man. Molly and Homer had two daughters and many grandchildren, all of whom have gone to college. When I went to the Endocrine meetings in California to receive the Koch Award, my uncle took me to the horse races. He would bet and he always made money, and my Aunt Molly did not like this at all. They were a fun side of the family for me; but my parents were unable to accept that she had married a Black man. My mother was afraid that if they visited us in Bethlehem that the neighbors would see him, and that somehow this would hurt my father’s position at the Bethlehem Steel Company.

Later at Harvard graduate school, when I encountered discrimination against women wanting to become scientists, I did not think of protesting or objecting to this biased treatment even in my heart of hearts. I think this was because I had lived so many years in Bethlehem accepting discrimination as a way of life.

Looking for escape as a youngster, I consented to attending Hebrew School, and joined the Girl Scouts. As a teenager, I tried to get out of the house whenever I could, especially summers when my father took his 2-week vacation. My parents often quarreled then with great bitterness.

I became inseparable from my best friend Nancy Schrader. We lived near each other. She was the youngest child of a Pennsylvania Dutch family and she was not Jewish. Her father did not approve of me. I remember a story at Christmas time when her father came down the stairs and wished her a merry Christmas and she replied, “Bah, humbug!” and he said “You are not to play with that Susan Epstein anymore!”

Nancy and I used to laugh ourselves silly. She was really a good friend. When we were in high school, we would play hooky a lot. I can remember going to see Ingrid Bergman in Casablanca. Here was this new Swedish star! I would steal money from my mother, and we would pay adult prices so no one would know we were kids. Our other friend Sylvia had a car, and we would drive for miles, sometimes halfway to Harrisburg. We would go swimming in the creek and have other adventures.

Because of her poor grades, the guidance counselors at my school tried to help Nancy, while I, who really needed help, was ignored because my grades put me near the top of the class. I was a straight-A student but could not commit to anything in particular because I was interested in so many different things. I was in several school plays and toyed with dreams of becoming an actress. I always knew that I did not have a life plan, and I still don’t. I just knew that I wanted to get out of Bethlehem at some point, so I figured I had better apply to college.

My brother was living at home and going to Lehigh University at that time. Sometimes I would go to his fraternity parties. There were no girls’ colleges within commuting distance, so I ended up applying to go away to Goucher College in Maryland.

I went with my father and brother to the interview at Goucher; and they talked to the admission’s officer the entire time. I did not say a word; and I remember thinking, “Gee, why did they bring me along?!” But I was accepted, and I went.

Goucher at that time was a women’s college that supported the notion that it was acceptable for women to want to think seriously about things. Being in an all-girls’ school made participation in class discussions more comfortable.

I decided to major in physiology, which was unusual at the undergraduate level, and it was only offered as a major at Goucher because of unique circumstances. The Chair of the department, Phoebe Crittenden, had been turned down for tenure at George Washington University Medical School. In those days, there were almost no women on medical school faculties. She gave up wanting tenure, but because she wanted to stay in the area, she created the undergraduate Physiology Department at Goucher. I remember her as a nice woman—although I did not want to view her as a female role model. She was unmarried, lived with her dog, and seemed to have had to give up her femininity to survive in the academic-medical environment.

At Goucher, I became good friends with my roommate, Francis Hackett. She was a history major, who, later with her husband, went on to establish a highly respected and profitable publishing company, The Hackett Publishing Company.

I remember one day coming back to the room after class, and Francis said to me, “You look really terrible today. You look just like a science major.” That did give me pause.

In my senior year, I had the nerve to try out for a part in a play that was to be presented at Goucher, Aristophanes’ “The Birds.” I was given a funny part, and the drama coach asked if I had ever thought of going on the stage. I said that I had. She said she would not suggest going into theater for my looks, but that I had a funny sense of comedy. Her comments lasted with me for quite a while, and later when I had a talk with my father about what my life plans could be, I shyly told him that I sometimes thought of an acting career. He said to me, “Well, if that is what you want,” with a slight tone of desperation. The option was always in the back of my mind.

When I graduated from Goucher, I went to live with my Aunt Eunice and Uncle Sam in their New York City apartment on Riverside Drive. I think they expected me to be something of a babysitter. My Aunt Eunice deConti was an accomplished Brazilian violinist, and incredibly talented groups of musicians and ballet dancers would come traipsing through the apartment. That was where I really had my first lessons in music criticism. I once treated my aunt and uncle to a concert at Carnegie Hall, and my aunt turned her critical judgment on the violinist. She said that he had no talent and that he was not even playing in time. She was devastating, and so incredibly sophisticated. I could see why she later became so well respected and important in the music life of Sao Paulo. Eventually, my grandmother got over the fact that my Aunt Eunice was not Jewish.

My aunt had won a scholarship from the Brazilian government to study at Yale. She spent a summer at Tanglewood and that is where she met my Uncle Sam, a music lover who had been discharged from the U.S. Coast Guard. They got married in San Paulo and came back to live in New York; but my aunt did not like American family living because there was not enough focus on family contact.

The summer I went to New York, I accepted a job as a technician working at New York University (NYU) in the laboratory of two clinicians, Herbert Chassis and William Goldring. Their project did not interest me. It seemed to have no rhyme or reason, and I was unimpressed by the quality of the science. They were just doing endless renal clearances on very sick patients who had been treated with nitrogen mustard. There was not a hypothesis in sight. After doing these analyses, the results would be tacked on the wall. Chassis would walk in, throw his camel’s hair coat on a chair, put his feet up on the desk and say, “My how the data seems to accumulate!”

I began to get intellectually restless. One of the perks of the job was that I was allowed to take courses at night at NYU. I studied the history of mathematics. It was a very well taught and interesting course. Then I started to get the idea that maybe I would like to go to medical or graduate school. I had not taken any organic chemistry yet so I enrolled in another night course.

I met my friend Jean Blumberg at NYU. She had had the job the year before and she taught me to do the inulin assays, which was the methodology used to measure the renal clearances. We got to be friends then, and we still are. That summer, when she suggested that we go on a youth hostel trip to Europe together, I was happy for the adventure.

When we returned from Europe, I think I had some of my grandmother’s worry that I was getting old and that it was time to get serious, settle down, and get married. I remember thinking, “Someday I will be 25, and then what am I going to do?!”

Graduate School and Career Beginnings

That fall, I went to live with Jean Blumberg’s family. I worked as a technician at the Rockefeller Institute and took various philosophy classes at Columbia University at night. I studied Aesthetics with Irwin Edman, and attended John Randall’s course in the History of Philosophy. However, I soon realized that I had no particular talent as a philosopher, nor did I care to turn my mind to such questions as, “When is a sentence not a sentence?” I figured, “Maybe I had better go measure something!”—and that meant going to graduate school.

My brother was getting his doctorate degree at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, so I applied to graduate school at Harvard to be close to him and to explore another city. I assumed I had applied to the graduate school in Cambridge, but they sent my application to the medical campus in Boston where they were starting a brand new program emphasizing basic medical sciences. I qualified for this because I had been a physiology major as an undergraduate at Goucher, and this subject was taught mainly at Harvard Medical School.

Because I hated filling out the forms, I applied to only one graduate school. Harvard accepted me, but my academic program was administered through Radcliffe. There, we were a group of 13 students. We spent all day every day together. There was a lot of faculty tension because the professors who were assigned to teach were temporarily shunted aside from their main career track at Harvard Medical School. The students did not like it because we were an odd mix of people. There were four top-of-the-class medical students mixed in with the rest of us graduate students, and we were very different kinds of people. The medical students memorized everything, whereas the graduate students endlessly questioned methodology. What I disliked most was the constant contact with the same, small group day after day.

We were part of an experiment on how to revise medical school curricula through a grant from the Commonwealth Foundation; but we were not even the right subjects. It was odd. It was a one-year program, and I could not wait to get out of there. I took pottery classes at night.

At the end of that year, we had to pick the department we wanted to enter. I had problems with that because I had had a miserable time at graduate school and was considering applying to medical school. I applied and was accepted to NYU, but then I had reservations. I did not want to take the spot away from someone else who really wanted it.

Ultimately, I decided that I did not want to take care of sick people. My mother had taken a course in nurse practitioning during World War II. She and later my daughter who went to medical school to become a psychiatrist were far more interested in caring for the sick; but it was not for me.

During graduate school, I was engaged to the son of a well-known Italian composer. My fiancé was drafted during the Korean War and sent to Alaska. I had been a bit swept off my feet by his elegance, although I had reservations about him being a Republican. He was actually pro-Nixon! When he was drafted, I was sort of stuck thinking, “Well, now what do I do?” So I stayed in graduate school with the idea that it would just be until he came back.

When it came time to choose which department to go into, what really mattered to me was that I had to like the person I was going to be working with. The Physiology Department at Harvard just seemed so stodgy, autocratic, and old-fashioned. But then I met Dr. Paul Munson in Pharmacology. He was working in this new area called neuroendocrinology and was one of the few professors interested in it.

I thought neuroendocrinology was intriguing because it offered an anatomical pathway by which emotions, thoughts, and feelings could travel through the central nervous system (CNS) and connect to the anterior pituitary gland to regulate the release of many hormones from the anterior and posterior pituitary glands. These hormones are then secreted to the rest of the body. This pathway explained how many peripheral physiological responses could be mediated by emotional stimuli.

Although I was interested in physiology, I was particularly interested in questions of the mind–body bridge. I was taken by the idea that some specialized nerve cells in select places in the brain not only function as nerve cells but also function as endocrine cells. They are true neurons in that they can accept and transmit electrical stimuli, but substances released at their terminals are passed—not onto the next neuron—but rather, into the vasculature. Their transmitter agents are released into blood vessels, and they reach a distant target by way of the circulation.

I asked Dr. Munson whether he would consider taking me on as a graduate student, and he agreed. He was a socialist, and I loved that. He was also a jazz lover, and he was very supportive of his wife’s career as a researcher. In fact, he was so prowomen that when I was getting married, he tried to talk me into keeping my maiden name.

Dr. Munson and I were friends until the end of his life. I was honored to speak at his memorial as one of the few graduate students that he ever had. He was an important influence in my scientific career. He impressed upon me the value of a bioassay, the basis of my two discoveries. As the years go on, I am more and more impressed with the value of a good bioassay, and the need not to drift too far from the dock.

If it had not been for Dr. Munson, I would not have stayed in graduate school—at least not at Harvard, which at the time, in my opinion, provided a dreadful atmosphere in which to educate young women scientists. In my class of 13, there were 4 women. One, Biljana Nikitovitch-Winer, left the medical sciences program after receiving a failing grade, earned a degree from Anatomy and later became the Chair of an anatomy department. The circumstances of her failure were absolutely unfair. Another one of the female students, Maria Michaelides, finished in the Bacteriology Department and worked for some years at Washington University, although she gave up before achieving tenure. The third student, I believe, quit. I think I was the only one who survived the experience to continue in a career in science.

Dr. Munson was very supportive of my career. When it came time for my thesis defense, someone from the Anatomy Department completely attacked my work. The topic was the neuronal control of adrenocorticotrophic hormone (ACTH) secretion from the anterior pituitary. I had established an in vivo bioassay whereby one could detect a corticotropin-releasing factor (CRF) that acted on the anterior pituitary to stimulate ACTH secretion. It was secreted by nerve cells into the hypophyseal portal circulation, illustrating the neuroendocrine pathway.

It turned out that it was not just ACTH secretion that was controlled, but it was all of the anterior pituitary hormones that were under neural control through this neurovascular–neuroendocrine pathway. The basic hypothesis was there, but no one had as yet isolated the so-called releasing factors that were responsible for the pathway from the neuron to the anterior pituitary. My thesis did not carry the project very far, but it established an in vivo assay that would be useful for the purification of the releasing factor for ACTH.

I do not know what the Anatomy Professor did not like about my doctoral thesis. It just seemed like graduate students were fair game to be attacked at their final thesis presentations. On my part I was terrified and still suffer mild terror when it is time for my students’ defenses.

Dr. Munson had to muster all the support he could get to prevent me from being judged a failure. It was terrifying to see how vindictive a faculty member could be toward a student. In recent years, safeguards have been put in place to avoid such situations.

I do remember that there were two professors in the Physiology Department who took me out to lunch before my qualifying exams and tried to convince me to quit graduate school. They said it was not a place for women. They believed that I would probably just get married, and that training me would be a big waste of funds.

Meanwhile, I was still waiting for my fiancé to be discharged from the service. I waited a year-and-a-half before ending the relationship. What ultimately got to me was when he came back from Alaska, he went to visit his parents before he came to Boston. I was irate and figured it was indicative of something. He was a psychiatrist and I thought, “Do I really matter or don’t I?” I decided to break off the engagement, which was a relief considering the difference in our political philosophies.

I had also met Cavin Leeman, another medical student, while at Harvard. He was also going into Psychiatry. He proposed, and I do not fully understand why I accepted. My former fiancé had not really wanted me to work on a career of my own, but with Cavin it was sort of O.K. By this time, I was 27 years old; and I thought it was about time I got married and had a family because that was what I really wanted to do.

So we married, and after a while Cavin did not want me to work anymore. I did not know how to handle that because I did not think I could just stay home and raise children. I thought I would drive them crazy. I have too much energy, and I did not think I had a rich enough inner life to fill the day without having something more serious to think about.

Our conflict over my working was a real hardship, and over time, it turned out Cavin had more antiwomen sentiments than I had originally thought. I remember arguing with him about whether they should increase the enrollment of women at the medical school. Harvard was one of the holdouts. The whole women’s movement had to overcome them before they increased the number of women in the medical school class to 50%.

Cavin had finished medical school at that time, and then he interned at the Massachusetts General Hospital (MGH). Interns were paid $300 per year, and that was not enough to live on. I had just finished my degree, and it seemed like I should have a job.

Dr. Munson came to my rescue then. I was offered a one-year position at Harvard Medical School as an instructor in the Physiology Department. I taught all of the animal experiments. They offered me $3,000 per year to teach, and Dr. Munson increased that stipend to $4,500. But the Chair of the department made it very clear to me that I should in no way consider myself to be on the academic ladder. I was just there to be a fill-in.

What I wanted to do anyway was continue working on the CRF problem. I wanted to try to use my own bioassay to see if I could detect the presence of a CRF. I did not know if I could purify it, as I was not a biochemist; but I was game to give it a try.

I only had the job at Harvard for a year, and then it was Dr. Munson who heard about a new program at Brandeis. His wife had been offered a job in the Biochemistry Department there, and they had recently gotten a neurochemistry training grant. He thought that I would qualify, so I went to Brandeis and they took me into the lab to start on the purification of a CRF.

In those early days, I was balancing early career and family life, which included care of my dysfunctional mother. The whole mix was nearly overwhelming at times.

The first time I knew that I was going to have a baby, I went to the chair at Brandeis and said I had to quit. He would not let me. He told me I would never come back if I quit, and he was willing to arrange it with me so that I would not have to work full-time. Three years later, I went back to speak with him again—this time, I was going to have twins. But we continued; and the chair sanctioned my getting a Career Development Award where I got paid two-thirds time. This was enormously helpful, and something I believe should be done more often. The NIH has never had part-time fellowships for women or men.

When she was a baby, I would take my daughter Eve with me to Brandeis, which had a nursery school. They talk about providing day care facilities to women workers now, and I was lucky to have had that through Brandeis. Eve would go while I worked, and then I would pick her up there and take her to a local babysitter’s house. I picked her up there at about 2 or 3 PM.

Then with the twins, I hired a woman, Fanny, to be in the home with them when they were babies. When they were old enough for nursery school, I took them with me to Brandeis. I would pick them up and take them home to Fanny and the au pair girls living in the house, and those arrangements mostly worked out. There was anxiety, but the fact that Fanny was there was an enormous help. When she cut down to 3 days a week, I just managed.

I tried not to talk about juggling family and work too much because there seemed to be this unspoken rule that if you got your work done and accomplished what you were going to accomplish, then no one would bother you. If you asked people for permission, then you could forget about it. It was not going to happen.

Substance P

At Brandeis, the Chair of the Biochemistry Department allowed me to have a graduate student named Richard Hammerschlag. Richard had transferred into the department from MIT and had been floundering around. When I asked him to join the corticotropin releasing factor (CRF) project, he was excited to accept.

We collected hypothalami from a local Boston slaughterhouse, the New England Dressed Meat and Wool Company; but only a few at a time were available. Using these hypothalamic extracts, we established to our satisfaction that a CRF activity could be detected by our bioassay.

With Dr. Nathan Kaplan’s encouragement, we decided to scale up because CRF was present in such low amounts. I went to slaughterhouses in Chicago to show the workers where the hypothalamus was located and how to do the collecting. They sent back bags of hypothalami to our lab. We started working with about 2,000 hypothalami. I do not know how I got into working with all of that sludge. I imagine that my mother had wanted me to wear laces.

Our plan was to first attempt purification of CRF on Sephadex columns that would separate CRF from other constituents of the extract by size and then by charge. Then we would devise whatever additional steps were necessary for the final purification. For detecting the biological activity of CRF, we anesthetized rats without stressing them and injected samples of extract into rats via the tail vein. We would kill the animals 15 minutes later, collect the trunk blood after decapitation, and measure circulating levels of adrenal steroids to see whether the extract could stimulate an ACTH secretion. This was before radioimmunoassay of ACTH.

The division of labor was such that Richard would make the extracts, start the initial purification steps, and I would do the biological testing. We monitored eluates of Sephadex columns by following the O.D.280. Earlier studies (Guillemin and Shalley) had shown that releasing factors were likely to be peptides and O.D.280 would be a rough indication of the presence of peptides. Because I had no allegiance to the meaning of O.D.280, I insisted that we test for CRF activity across the entire column instead of just testing the peaks of the O.D.280.

One day, when testing some of the eluates from a Sephadex G75 column, I noticed, after intravenous injection of material pooled from a trough of the O.D.280 activity, that fluid welled up in the mouths of the test animals. I was very surprised and wondered what was happening. I thought the fluid must be saliva, but I was not sure. I was also amused because I had done my doctoral research work in Dr. Munson’s laboratory, which was located at the Harvard Dental School, and I thought that perhaps I should know something about secretions of the oral cavity. I remember also racing upstairs from the animal quarters to find Dr. Morris Soodak, a true friend in the Biochemistry Department, to show him this discovery.

Fig. 1    Gel filtration on a column of G-75 Sephadex of bovine hypothalamic extract: 1.9g was applied in 60 ml of column buffer to a 4.7 × 69 cm column run in 0.1 M pyridine acetate, pH 2.8, at room temperature; 16-ml fractions were collected at a rate of 60 ml/hour. The region of effluent volume from which sialogogic activity was recovered and the region containing material that caused cutaneous blanching in the test rats are indicated. From Leeman and Hammerschlag (1967).

Shortly afterwards, I collected the fluid with a pipette and bulb and decided to measure the activity of a constituent of saliva, alpha amylase. The results were clearly positive. The sialogogic activity was running on the first purification column as if it were larger than either acetylcholine or catecholamines, and so I suspected it was not a classical neurotransmitter.

The next step was to test whether this activity could be destroyed by proteolytic digestion. We set up a bioassay based just on measuring the volume of saliva. Increasing the dose of extract injected increased the volume of saliva that could be collected simply using a pipette and bulb. We subjected our active fractions to broad-spectrum proteolytic digestion and found that the biological activity was completely destroyed.

I was so relieved because by this time because there were two huge groups, Guillemin and Shalley, purifying the releasing factors, and I did not think I could compete. I thought I had found something different, and I decided to go after it instead. I changed the direction of our entire project. We were now no longer going after CRF, but rather a peptide that could stimulate the secretion of saliva.

That was the industrial part of the preparation. By the time we had finished we extracted over 70 kilograms of bovine hypothalami. Once we had lyophilized the extract, we solubilized the material on the trays and ran the initial purification columns—approximately 20 liters of Sephadex—at Tufts’ New England Enzyme Center. We had outgrown the Biochemistry Department at Brandeis and moved to find large-scale homogenizers and lyophilizers. The New England Enzyme Center was set up by the National Institutes of Health (NIH) for people exactly like me, who were working in a classical biochemistry department, but who needed a huge increase in the capacity to extract biological tissue. That facility later became what is now a huge company, Genzyme Corporation.

We brought trays of rats into downtown Boston to test which fractions had the sialogogic activity we were trying to isolate. We then pooled these fractions, took them back to the Biochemistry Department at Brandeis, and continued on with our next purification steps.

We published the first paper just on the detection of “sialogen.” Then, when Richard graduated from Brandeis, I had a new student in the Biochemistry Department named Michael Chang. It took 3 more years for Michael and I to isolate the peptide that was causing this secretion of saliva. It was only when it became time for Michael to write his thesis that we began reading the literature on hypothalamic peptides seriously, and we came upon a study about the discovery of something called “substance P.”

Substance P had been found in the 1930s by von Euler and Gaddum. In 1931, they were looking at the tissue distribution of acetylcholine and discovered something in horse brain and intestine that caused the contraction of various isolated smooth muscles. Unlike acetylcholine, whose activity could be inhibited by atropine, this new activity was not inhibited.

In 1934, Gaddum and Schild realized that they were dealing with a peptide because it was destroyed by proteolytic digestion. Von Euler and his collaborators ended up naming this peptide “substance P” because it was the substance in the preparations that had this constellation of biological activities: contraction of various smooth muscles, and lowering of blood pressure.

They were unable to isolate the peptide, however, and this became an unfinished project. In their most highly purified preparations, they did have a partial amino acid composition, but they could not decide if there were two amino acids or one.

At Brandeis, we had our pure material and looked to see if it had the biological activities described by Von Euler et al. We did not have rat blood pressure equipment so I went back to the Physiology Department at Harvard asking to borrow theirs. I injected our material into the rats, waiting to see if it would lower their blood pressure, and sure enough, it did.

There was no way out. Our material had the various properties attributed to substance P. We had unintentionally isolated this peptide that had defied isolation for 40 years. We published in the Journal of Biological Chemistry in 1970.

One day soon after, I met Von Euler. He was attending a fancy neuroscience meeting at MIT. I had not been invited, but I thought that he might be interested in our story. This was, after all, the peptide that he discovered during his first postdoctoral fellowship in England after getting his degree at the Karolinska Institutet in Stockholm.

Von Euler was aware of our work on the isolation of substance P, and he immediately agreed to meet with me at Harvard Medical School. I told him I could pick him up at his hotel, and we ended up sitting in the parking lot as he asked me for the whole story of our discovery. Meanwhile, the Neurobiology Department at Harvard was wondering where we were, and who was detaining him. It was very nice to talk to him about our work. He really was a gentleman, and very complimentary.

Later he organized a symposium in Stockholm on substance P, and I was invited to come. I went with my husband and three children, and it was an exhilarating affair.

Neurotensin

It was during the course of purification of substance P that I made my second important discovery at Brandeis. This was a vasoactive peptide that we detected in the eluate of an ion-exchange column that was clearly separable from the sialogogic activity. I showed this activity to a graduate student, Robert Carraway, in the Biochemistry Department who happened to be looking for a thesis project. I asked whether he would consider trying to isolate the peptide using this vasoactive assay. He agreed. The complete purification of this peptide took several more years. We named it “neurotensin” because of its presence in neural tissue and its impact on blood pressure.

Neurotensin has a very broad distribution throughout the CNS, the gastrointestinal tract, the immune system, and so on. Research on neurotensin has become a rather large field. Dr. Carraway has remained on the faculty at University of Massachusetts (UMass) Medical School and continues to be a leader in this area.

At this time, my Career Development Award was coming to an end. I approached the Chair of the Biochemistry Department at Brandeis to discuss my future there and asked whether he was going to recommend me for tenure. He told me that I could stay as long as I wanted and as long as I could bring in my own funding, but that he, for one, would vote against me if asked. He said he would be willing to discuss it with the Department, but he was pretty certain they would all vote against me too. Much to my self-disappointment, the tears began to run down my face. I decided it was time to leave.

Many years later, I was told by a member of the Department that a meeting of the faculty was held to consider my promotion, and that the sentiment of the faculty was in favor of my staying.

Fig. 2    Ion-exchange chromatography of a bovine hypothalamic extract on sulfoethyl Sephadex C-25. Neurotensin activity (cutaneous vasodilatation) and substance P (sialogogic activity) were detected using bioassays and protein concentration was monitored at 280 mµ. Pyr. Ac. = pyridine acetate. From Carraway and Leeman (1973).

But I had made up my mind and was beginning to look for a place to relocate. At the Federation of American Societies of Experimental Biology (FASEB) meetings, where Dr. Robert Carraway presented the isolation of neurotensin, I saw John Pappenheimer, a Professor of Physiology at Harvard. He asked me how things were going, and when I said, “Well, not so wonderful,” he asked whether I would be interested in joining a new institution at Harvard Medical School, the Laboratory of Human Reproduction and Reproductive Biology (LHRRB). I agreed to look into the matter and made an appointment with Dr. Roy Greep, head of the LHRRB, to interview for a position. My laboratory would be in the Physiology Department.

In 1972, I moved my laboratory to the LHRRB and continued working on both of these peptides, substance P and neurotensin. After I had been at Harvard for some time, a committee headed by Alice Huang began investigating the low salaries of women at Harvard Medical School. As a result of her efforts, I was given raises and was presumably on the academic ladder. The question of being promoted to associate professor with tenure at Harvard was still unaddressed. This mattered very much to me then, and it began to take a toll on my self-respect.

Toward the end of my time at Harvard, Dr. Joseph Martin became the chair of the Neurology Department at MGH. He asked me whether I would move from the LHRRB to his department at MGH, and he said he would support me for a tenured position, feeling that this would not be a problem.

Because my tenure at the medical school was not being supported by the chair of the Physiology Department, I somewhat hesitantly agreed. I gave notice to Dr. Kenneth Ryan, then head of the LHRRB.

I distinctly remember reporting for work at MGH in September, right after Labor Day, only to be told by Dr. Martin that things would not be as he had promised, and that a tenure appointment for me would be much more difficult than he suspected. I was, needless to say, horrified.

After a short deliberation, I decided to ask Dr. Ryan if I could remain at the LHHRB, and, to my relief, he was very welcoming. Still, the question of tenure was haunting me. Now, thank heaven, I don’t care about such things.

While still trying to recover from this last experience, Dr. Maurice Goodman, a friend of mine, and a former graduate student in the Physiology Department at Harvard, offered me a position as full professor with tenure in UMass Medical School’s Physiology Department, where he was chair. It had the disadvantage of being nearly an hour’s drive from my home in Newton, but nonetheless I accepted.

By this time, my older daughter, Eve, was an undergraduate at Harvard, and my two younger children were in high school. I felt concerned about the long commute and being so far from home. But, on the positive side, it seemed like UMass was a much friendlier institution than Harvard, and with less pressure. Many excellent scientists were working on the biology, molecular biology, and pharmacology of the two peptides that my laboratory had isolated, and I still felt like working. I was elected into the National Academy. My salary was raised, and work was going well.

I was asked to consider several different positions as chair; and I most seriously considered going to Mt. Sinai Medical School in New York. I gave up this idea when my husband said that maybe I should consider going by myself. His comment shocked me as I felt that maintaining the family was important. Our marriage was having difficulty, especially around the issue of my professional success compared to his academic career, but I hadn’t fully realized how much we had grown apart. During that year, our marriage ended.

Soon after, I was fortunate enough to meet Dr. Lippman Geronomus, an infectious disease expert at Harvard Medical School. He had a wonderful sense of humor, and I admired him for raising three wonderful daughters on his own after death of his wife. Six years into our relationship, he died suddenly at my son’s graduation from Oberlin. It took me a long time to get over his death.

These many personal traumas have taken a toll, I believe, in reducing my energy to cope with all the strains of continuing a career in science.

Continuing a Career in Science

I never moved from Newton to Worcester. When David Farb was hired as the chair of Pharmacology at Boston University (BU) Medical School, and he asked me to consider coming to work for him as a professor in his department, it was as much a transportation issue as it was a career move. I had been getting extremely tired on my way home from work, and I wanted to be more available to my family. Of course, by this time, most of my children had been through college and were not around all that much, but I had a feeling of distance. I looked forward to the idea of working closer to Boston.

I had known David as a graduate student at Brandeis and later as a postdoctoral fellow Harvard Medical School. We had even collaborated on a project together.

In 1992, I moved to BU, bringing several people with me. At that time, I was working with Dr. Norman Boyd on the photolabeling of the substance P receptor, and in defining its binding site and other biological functions. Dr. Mark Alexander and I were working on the role of neurotensin in the hypothalamus to stimulate the secretion of the luteinizing hormone-releasing hormone (LHRH). This was a project that I had started with Dr. Craig Ferris when I was still at the LHRRB.

Working at BU has been a difficult but fruitful time. Because I am essentially a team player, I have trouble holding opinions that are in conflict with the administration of the place I work in. There is one thing that BU is doing now that I do not agree with, however. They are building a BSL4 Bioterrorism Research Laboratory without really having obtained permission to open it because the land does not belong to BU. In many of the public hearings on this topic, BU has not treated the community with dignity. This has not helped community relations for the medical school.

One of the really enjoyable experiences at the school has been to supervise the Ph.D. training of graduate students. Morris Tansky, in particular, has been—with a few rocky times—a real pleasure.

Interactions with other faculty members have been very productive. The involvement of the pharmaceutical industry in the production of antagonists both substance P and neurotensin has opened up new fields of investigation for the possible clinical usefulness of halting the activities of these two peptides. In recent years, I have worked with Drs. Harry Pothoulakis, Arthur Stucchi, and James Becker on anti-inflammatory diseases of the gastrointestinal tract, and with Drs. Stucchi, Becker, and Karen Reed on the ability of substance P antagonists to inhibit cell adhesion formation after surgery in the peritoneal cavity.

Over the years, despite considerable recognition, I sometimes have felt disappointed in myself for not taking on bigger administrative jobs, such as Department Chair. There are many advantages to those types of positions; and there has been pressure for women being offered these opportunities to not refuse because they were not available to them for so long. I have found, however, that I am more interested in ideas, research, and mentoring. To me, the best part of my job is the science—not empire building.

Lately, I find myself getting less and less excited about the general work atmosphere of the biomedical establishment in this country. As time has passed, it has become increasingly difficult to obtain grant funds. I have continued working as a professor and tried to be content making those contributions.

Most recently, I have wanted to think more about how basic neuroscience might contribute to psychiatry. I began working with my daughter, Eve, who is a psychiatrist, on how to think about this link with psychiatric matters—not so much cognitive, but more emotional—that is, thoughts, feelings, anxieties. Although her father is a psychiatrist, I credit her interest in psychiatry as coming as much from me as from him.

I wanted to explore whether there might be any particular insights that would come because of my interest in basic neuroscience. That is when I started thinking about the importance of relationships amongst neurons—with influences from other cells too—on development and function.

It turns out that huge excesses of neurons are born in the nervous system during embryogenesis. Most die off, and only those that establish functional relationships with other cells survive. I thought it was very startling that survival depends, not only on development, but also on function at the cellular level. It seemed to me that this fits as a metaphor for emotional properties.

I asked my daughter if she would think neuronally with me, and she said, “Mom, how else would I think?!”

“OK,” I said, “You’re plenty smart for me.”

I have had a very good time working with her and we published a paper called “Neuronal Metaphors—Probing Neurobiology for Psychodynamic Meaning,” which met with no notice whatsoever. We sought to apply the functional properties of neurons in their microscopic relationship-networks to the macroscopic world of human emotional properties. We felt that an understanding of neurons at the cellular level as they form and break relationships could inform the psychotherapeutic process in a way that an isolated understanding of receptor chemistry cannot. These neuronal metaphors can powerfully influence the way psychiatrists approach their work in the clinical setting.

I think this is such an interesting idea that I would like to pursue it further. We are planning to present a panel at a psychiatric meeting where we would invite two basic scientists to show the real importance of relationships to the development of neuronal function. Then Eve would give some clinical examples, and we would invite another psychiatrist to also review some patients’ progress in psychotherapy. Finally, we would include a philosopher to elucidate the importance of metaphorical thinking in the advance of scientific understanding.

I do get excited about the possibility, although, at the moment, biological psychiatry has swung so far the other way that I do not know how our ideas will be received. Everyone talks about specific transmitters, and these drugs have been useful, but there is also a need for more psychodynamic thinking.

Life as a Working Grandmother

Family remains a priority in my life these days, and I try to stay connected to my children and grandchildren as much as possible. My oldest daughter, Eve, and her husband, Alberto, have three children, Elena, Claudia, and Alejo. Alberto, a Columbian citizen, works in international affairs with a company that has many dealings with South America.

My son Raphael works nearby in downtown Boston at the investment firm Eaton-Vance. His wife, Dana, is on the faculty at Simmons School of Social Work and has a busy homemaker career life also. They have two children, Marissa and Gabriel. I play ping-pong with them and, occasionally, tennis.

My younger daughter, Jenny, is a completely lovely and accomplished person. She and her husband, Hector, a Peruvian photojournalist, live in Washington, D.C. Jenny is a Professor of Linguistics at George Mason University and is admired in her department as an excellent teacher and a researcher.

These days, my friend, Nelson and I spend summers at our house in Maine, right near Bowdoin College. During the academic year, I have been trying to host more social events—like an afternoon of music in the garage—instead of worrying about work all the time. Nelson and I stay active playing hard-fought games of ping-pong.

I have seen a lot in the news recently about the changing role of grandmothers, and it really is a new phenomenon. We are a generation of older working women, now less available to babysit and participate in family care. Grandmothers today are better off financially than in generations past, and they are looking for better lifestyles for themselves in travel and entertainment. When their daughters and sons have children, they may be busily involved with their own careers and social lives, and less available to help out. This is getting national recognition.

Because I like to make myself available to my family, I find that life as a working grandmother can get complicated. This conflict is just one more that I did not entirely anticipate.

On balance, although it has been fraught with difficulties, my life as a scientist has been very rewarding. It has really been a pleasure to work with graduate students, and to watch them mature into critical, capable investigators. I have found that really fun. As a consequence of having been elected into the National Academy, I have met persons who have asked me to help in editing their manuscripts. That has been a very positive experience as well.

Either as a result of my schooling in elitist male institutions or my own personal problems, I never felt safe to fully commit myself to a career in science. Perhaps things have changed with the greater participation of women at high positions in academia and in the political arena, but that sense of security at work has always eluded me. In this current climate of reduced support for small individual research projects at the NIH, I see signs of the old anxiety now not limited to women, but also applicable to men. I feel a great sadness about this situation.

It seems to me that these changes at the NIH have occurred with the increase in business attitudes toward education, and “bottom-line” thinking. I have observed the continued rise of large sums of money invested at the top to fewer and fewer directors of laboratories, and less and less trickle down to the support of creativity at junior levels. In this hard turf, it is difficult for an old socialist like me to flourish.

I know that I should think about retiring some day, but I am not quite ready.

Vernon B. Mountcastle

BORN:

Shelbyville, Kentucky

July 15, 1918

EDUCATION:

Public Schools Roanoke, Virginia (1924–1935)

Roanoke College, B.S. (1938)

Johns Hopkins University, M.D. (1942)

APPOINTMENTS:

House officer, Johns Hopkins Hospital (1942–1943)

Fellow, (1946–1948); Assistant Professor-Professor, Department of Physiology (1948–1980)

Director, Department of Physiology (1964–1980), Johns Hopkins University School of Medicine

University Professor of Neuroscience, School of Medicine (1980)

HONORS AND AWARDS (SELECTED):

Lashley Prize, American Philosophical Society (1974)

Schmitt Prize and Medal, MIT (1975)

Sherrington Gold Medal, The Royal Society of Great Britain (1977)

Horowitz Prize, Columbia University (1978)

Gerard Prize, Society for Neuroscience (1980)

Helmholtz Medal, Cognitive Science Institute (1980)

Flyssen Foundation Prize, Paris (1983)

Lasker Award (1983)

National Medal of Science, USA (1986)

Zotterman Medal Swedish Physiological Society (1990)

Fidia-Georgetown Medal and Prize, AAAS (1990)

The Australia Prize (1993)

Prize in Neuroscience, National Academy of Sciences, USA (1998)

Cajal Prize (2000)

Vernon Mountcastle discovered the columnar organization of cerebral cortex. He pioneered the neurophysiological study of primary sensory cortex with single-cell recordings in anesthetized and awake monkeys and inaugurated the neurophysiological study of attention and action in parietal cortex.

Vernon B. Mountcastle

Ancestry and Background

I am of Scottish descent on both sides. My family name arose in Scotland in the fifteenth century, a part of the Hamilton Clan. My mother’s family names are Waugh and Robertson. How or when these ancestors migrated to the United States is unknown to me, but they appear in Virginia from early colonial times. The first census of the United States, made in 1790, is published in a large book of maps, one for each state, with the name of each landholder given, and beneath it the number of “black souls.” Three Mountcastle farms are shown in eastern Virginia, and beneath each name is the notation “no black souls.” I attribute their abstinence to their Presbyterianism. This meant that while comfortable they could not be wealthy, for they competed in the large plantation economy of Virginia in the pre-Revolutionary period. A Robertson ancestor was clerk to the Royal Governor of Virginia in Williamsburg, and it is through him that I am descended from Pocahontas, and thus from the Indian emperor Powhatan. I calculate that given 12 to 13 generations since then about half a million Virginians could claim (or disown!) that descent.

My paternal grandfather was born in 1841 in Charles City County in Virginia. He and his three older brothers rode in the 3rd Virginian Cavalry of Stuart’s command throughout the Civil War. My grandfather sustained a gunshot wound to his arm in the battle of the Wilderness, survived amateur surgery for bullet removal by his brothers, and thus avoided the military hospitals, where amputation was routine, and death probable. The four brothers were demobilized at Appomattox and returned to Charles City County to find their homes destroyed, and their farms overgrown, for this county had been a part of the battlefield of the Peninsula campaign of 1862. The Civil War generation of 1865–1890 worked indefatigably in the postwar period of reconstruction to re-create a decent life. This generation of Virginians was called by Gerald Johnson “The Boys of New Market.” My ancestors were not at New Market, but the description fits. My grandfather did not marry until 1889, which accounts for the generation gap in my family. No member of my family earlier than my own generation had a university education: they were all farmers, industrial entrepreneurs, or builders of railroads.

Childhood and Education

Our family moved to Roanoke, Virginia, in 1921, when I was 3 years old. The home office of the railroad construction firm in which my father was a partner was in Roanoke, and the move must have been impelling for that reason. Another was to provide access to the fine public schools of Roanoke for my two older sisters and myself, and eventually for my brother and a younger sister who joined us later.

We moved into a pleasant house on a street lined with maple trees, only two blocks from open country. The community was almost ideal for me. The elementary and the junior high schools were within easy walking distance, as was a branch of the public library. There were three tennis courts in the neighborhood; I began playing at 8 years and continued my favorite sport until I was forced to stop at 80. Beyond that, 12 boys all aged within 2 years of each other lived within a radius of two blocks. This led to team sports of football and baseball, with organized games with teams from other neighborhoods. This dozen remained my friends for many years, but only three now survive. I was an enthusiastic Boy Scout and found earning merit badges another education. Summer scout camp high in the Alleghenies was a thrill. It cost only $12 for 2 weeks; it must have been heavily subsidized.

My mother had been a professional teacher before marriage, and she taught me to read and write by the time I was 4 years old. Thus when I entered the public school system I was immediately moved ahead two grades. I remember many of my teachers with respect and affection, particularly my Latin teacher, Miss Sally Lovelace, who taught us the history of Rome and Greece, as well as 4 years of Latin. This accounts for my enduring interest in ancient history, of which I still read a great deal. The high school courses in the humanities and civics were excellent; I know now that those in the sciences were poor.

I graduated from high school at 16, and in September 1935 I entered Roanoke College, located in a nearby town, Salem, Virginia. I lived at home and commuted. It was the midst of the Depression, and I was lucky to go to college at all. This small college of about 300 students had a fine faculty of 14 professors, all devoted to teaching. I majored in chemistry and finished in 3 years. When I set about applying for medical school I had no schools in mind except the two in Virginia. However, my teacher of chemistry had been trained at Hopkins and suggested I apply there. I did so with no hope of acceptance. The acceptance letter arrived on Christmas Eve of 1937; my mother immediately declared that I should not go to school with “all those Yankees!” But go I did, and save for World War II I have remained all my life in that extraordinary place.

I arrived in Baltimore on October 1, 1938, and went by taxi to the School of Medicine, in East Baltimore; seeing that city was itself a depressing experience. I opened an iron gate and entered the Medical School square; except for the Welch Library, the square was formed by a number of dilapidated buildings, some undoubtedly condemned by the fire department, but exempted by special dispensation. In the center were several large cages filled with macaque monkeys, which I had never seen before. I approached the school entrance (it led to the basement, alongside the men’s latrine) and observed just outside a large hand-printed sign saying, “Watch out for falling snow”—the temperature was in the 90s! I concluded that an institution with a sense of humor like that was just for me; I entered and I never left.

What mattered were the people in those buildings.

Johns Hopkins: Medical School and Internship

The first-year class I entered contained 75 students, many graduates of Ivy League universities, with much better educations than my own. We were taught by an equal number of faculty members of the basic science departments, all active in their own fields of research. Teaching was direct and personal, largely in laboratories and discussion groups. The first year was arranged in the block system in which we took only one course at a time—full-time. The anatomy sequence occupied the first two 8-week quarters, followed by a quarter of physiology and then one of biochemistry. There were no tests or examinations at all until the final week of the year, and we were never given any grades. Failure was signaled by a private letter, and only two members of my class failed to reach the M.D.

The Department of Anatomy was an active research institute in which investigations ranged from histochemistry to physical anthropology. It was directed by Lewis Weed, known for his studies on the circulation of the cerebrospinal fluid, and staffed by Straus, Shultz, Hines, Tower, Streeter, Flexner, Howe, and half a dozen others of equal distinction. I remember well my first-year examination in Anatomy. I entered the room to find Drs. Weed and Hines standing to receive me. I was not asked to sit down, nor did they. There was long table covered with dissected specimens, and several microscopes and many slides. The questions began, for example, “Show us the branches of the brachial plexus and tell us the muscles innervated by each”; “Look at this section, identify the tissue and tell us its organization, innervation, and blood supply.” And so on, for nearly an hour. I staggered out feeling like a boxer taking a standing eight count and convinced that my days at Hopkins were over. Somehow I survived.

The course in physiology consisted largely of laboratory and small-group sessions, with the fewest possible lectures—in my year about 40. The laboratory teaching was done by the most senior faculty, with no teaching assistants. I remember a cardiovascular laboratory exercise in which Philip Bard stood for 2 hours at our table, teaching us to observe for ourselves, and to make independent interpretations of what we saw. The course in Biochemistry was equally intensive, taught by William Mansfield Clark and his staff. We all feared this course because it demanded a background in physical chemistry, which I and many of my classmates had never had. I learned later that Mansfield Clark was an amusing companion, but in the spring of 1939 he was a threat to my remaining in medical school.

We were also scheduled in this year for a course called “Psychobiology.” The major task was to write a personal life history. This was submitted to a senior member of the staff of the Department of Psychiatry, followed by an hour-long conference with a faculty member. Mine was with the Director of the Department, Adolf Meyer. He had read every word I wrote and remembered them all. He probed at some spots and left me with the message that to deal with patients one must first know and understand oneself, a lesson I never forgot. The first three quarters of the second year passed in intensive study in pathology and bacteriology, under the direction of Arnold Rich, a brilliant and somewhat eccentric man. In his first lecture he challenged us to “define what is living.” He demolished all our ideas. During the fourth quarter we were scheduled for a course labeled “Introduction to Psychiatry” for eight Friday afternoons. There was no course description, we had only to report. And we did, climbing to that ancient and dusty lecture room in the Phipps Clinic building, each seeking a seat in the back row. Before us we saw Adolf Meyer, seated at a deal table: huge head, bearded, his feet not quite reaching the floor beneath the table. He made a few introductory comments, of which we understood nothing. Then the bombshell: we were to be shown a patient—for the first time, a patient! White suits opened a door at the rear of the stage, and there bounded into the room a wild-haired man who dashed around the room shouting, “I am the king of Siam.” White suits calmed him into the chair by Dr. Meyer. The latter spoke, over cathedralized hands, “Who are you?” The patient made another trip around the room and went back to the chair. Meyer had not moved a muscle, and now he asked, “Who am I?” The quick reply from the manic patient: “You’re a little bastard with a red tie on.” We, the students, burst into laughter. White suits removed the patient, and Meyer gave us a lecture on how to behave in the presence of a patient. I have often wondered whether Meyer laid the whole thing on, but my friend Jerome Frank assured me that Dr. Meyer would never have been so duplicitous. But, having known many Hopkins professors, I remain skeptical. I left that session knowing I had been exposed to a firstclass intellect, and I have never forgotten that searing question, who am I?

I spent the summer after my second year working in the Department of Pathology at the Philadelphia General Hospital, the old city hospital where Osier had spent several of his early years in the United States. There were several autopsies each day, and what we learned was mainly gross pathology. The safety precautions were primitive, and I had a great fear of infection with the tubercle bacillus, for we frequently dealt with tuberculous empyema. In fact, my classmate and companion there, Giles Filley, did later come down with the disease.

The third year was consumed in being taught with patients and instructors in the outpatient clinics. The most memorable of these were our visits to what was called “City Hospital,” now the greatly elaborated and modern Bayview Medical Center of Johns Hopkins. That hospital in 1940–1941 was filled with chronically ill patients, and seeing them was an important part of our education. Almost every chronic disease was demonstrated to us, particularly those of the nervous system. I remember a clinic with John T. King, a distinguished Baltimore physician. He showed us a patient, just off a ship from South America, with signs of Kaposi’s disease—blood-filled subcutaneous tumors over his entire body. I have since wondered, could that have been an unrecognized case of AIDS, in 1941?

The fourth-year quarter in internal medicine was the most intensive learning experience of my life. Imagine a ward of 25 patients, 5 students, 2 interns, assistant resident Philip Tumulty, and Maxwell Wintrobe as faculty (he was then preparing for his position as Head of Medicine in the new school in Utah), and a laboratory where the students did the lab work. It was total immersion, day and night. Ward rounds were made daily by Wintrobe, and weekly by Professor Warfield Longcope, the Director of the Department of Medicine, to whom we presented our cases. He questioned us closely, remembered every detail of each patient from week to week, and insisted we follow each patient daily by direct observation. The final week of that year brought oral and written examinations in all the clinical disciplines, a period of considerable stress. It was wartime, and there was no graduation ceremony; we received our diplomas by mail.

During my time in medical school I had no objective other than to become a surgeon, and preferably a neurosurgeon. In fact I never did an experiment until my 28th year. I applied for and was appointed House Officer in surgery in the Johns Hopkins Hospital for the year 1942–1943. I had already done a good bit of interning, for the approach of the war had depleted the house staff, opening many opportunities for third-and fourth-year students to “substitute” as interns. This almost led to my dismissal from medical school, as I explain below.

The course in obstetrics was the only abysmally taught course I encountered at Hopkins—filled with interminable lists of statistics. I simply cut the course and interned in surgery. After a few days, a call: report to the Office of the Director of the Department of Obstetrics, Professor Nicholas J. Eastman. He had discovered my absence, and although attendance at lectures was always voluntary, he had taken great offense at my absence. He was furious and at once proposed to take me to the Dean’s office for dismissal from the school. I knew this was an idle threat and remained silent. Finally, he dismissed me with the warning that the final exam in obstetrics was only 2 weeks away. I immediately quit interning, bought Williams Obstetrics, moved into a third-floor bedroom on North Broadway, and memorized the book. When the exam was over, I returned to interning. Then, another call came to visit the Professor of Obstetrics. He was even more furious, his little mustache quivering on his upper lip. He had my paper on his desk. “Mountcastle, we do not give hundreds, you made ninety-eight: goodbye.” Of course, I forgot most of it rapidly.

I spent the summer of 1942 working as the intern on Dandy’s brain team. An internship at Hopkins was in those times total immersion; one was on duty 24 hours a day and there was no official time off. I spent several of the months of my intern year working in the Hopkins accident room, and there could have been no better training for my later experience in the Naval Amphibious Force. I had been a member of the Naval V-12 corps for medical students since January 1942, which allowed me to finish medical school and internship.

U.S. Naval Amphibious Force

In June of 1943 I received orders to report to the Naval Operating Base in Norfolk, Virginia, and early in July several of my classmates from Hopkins and I arrived there together: Edward Novak, George Mitchell, William Higgins, John Classen, Stuart Christhilf, and myself. Novak, Mitchell, and I were directed to the noon conference of the Chief of Surgery. We marched in and were ordered to stand at attention before him. We did so but certainly must have looked a bit sloppy, for we had never stood at attention before. He was Commander Deaver, the son of the man who devised the Deaver abdominal retractors that tortured the hands of generations of surgical interns. His first comment, delivered with a sneer, was, “So you’re from Hopkins.” We confessed we were. However, he could do us little harm, for we were in Norfolk “awaiting further orders.” Mine arrived in mid-August: report to the 3rd Naval District in New York for duty with “Glen-57”—no news of the nature of Glen-57. I went to New York and, after a 5-day delay, was sent to Bayonne, New Jersey, to board a refrigerator ship converted to a troop transport. Once at sea I learned we were headed for North Africa. After three days at sea a loudspeaker announcement ordered all Glen-57 personnel to report to the officer’s wardroom; in Navyspeak, the order was, “Lay up to the wardroom,” where as a junior officer I had not previously been allowed. There I discovered that Glen-57 was to be a shore-based general hospital, not yet constructed, near Oran, Algeria. I joined a group of physicians all one or two decades older than myself. The commander was a kindly and able regular Naval physician. It seemed a fortunate assignment. Upon arrival in Oran on September 1, 1943, I saw the hulks of the French Navy, sunk by the British to prevent their falling into German hands. I also saw a line of U.S. soldiers marching along the pier and embarking for the Salerno invasion; they were bronzed, athletic, and confident and filled me with pride. They were part of the 3rd division which, together with the 36th and 45th, bore the brunt of the fighting in the Italian campaign.

We were sent for temporary billeting to a group of French vacation huts on the sea at Arzew, 50 miles east of Oran. It was like a summer vacation at the beach, with the prospect of 2 months before the hospital was completed. This vacation in wartime disquieted me. After a few days I requested transfer for temporary duty with the Army and was sent to an Army general hospital in a French hotel in the Atlas Mountains, 50 miles south of Oran. There I served for 2 months in charge of an orthopedic ward filled with casualties from the earlier Tunisian campaign. I then returned to our completed hospital for a few weeks, but in January 1944 I was ordered to sea aboard LST 378. I served on four LSTs in the Anzio and Normandy invasions (described later) until I was ordered back to the amphibious training base in November 1944. That training was of course for the planned invasion of Japan.

The Anzio Invasion

During my time in the med I survived three life threats. The first was a typhoon in the Tyrhenian Sea with 65-mile-per-hour winds. The second was the Anzio invasion, at first a cake walk, but later a disaster. During our daily round trips from Naples to Anzio we encountered only occasional shelling, and airborne bombs launched from high-flying German planes. Here I dealt with the bravest man I ever knew. An LST (Landing Ship Tank) carries six small boats, called LCVPs; in an invasion these are lowered to the sea and carry soldiers to the hostile shore. The six are commanded by a “small boat officer,” an ensign from the LST crew. At about 3 AM on invasion day we anchored 3 miles off Anzio. Immediately the order, “Lower small boats” rang out, but no one could find our small boat officer! During the search I saw in a comer of the bridge a pile of kapok life jackets and heard emitting from the pile the beautiful sound of an Irish flute playing the “Blue Island Blues.” There the small boat officer was hidden, trembling with fear, playing his flute. I was told later that he had performed magnificently at an earlier invasion at Licata, in Sicily. A few moments of encouragement, and my promise that I would be waiting for him on his return, and this trembling young boy went over the side and led his boats onto that hostile shore.

The third was more serious. For several weeks we made daily round trips between Naples and Anzio. Upon return from one of those we were lashed out board another LST in the port of Pozzuoli, on the southern shore of the bay of Baia, where Caligula had built his bridge of ships. A sudden violent storm parted the lines from the inboard LST to the dock, and we two, bound together, were swept across the bay to land on its northern, rocky shore, we inboard. The outboard LST parted the lines and got away, but we were marooned on the rocks, our ship’s bottom torn out, with no power and nothing to do but await rescue; meanwhile, we ate all the steaks.

But doctors were not allowed to be idle for long. I was lifted off and transferred to another LST, and later back to my base in Oran. We all knew that the Normandy invasion was coming soon, and I maneuvered to be in it by getting myself ordered to another LST, the 539, which I knew was headed for Great Britain. (Those in charge were always a bit surprised but happy when a physician requested sea duty!). The skipper of the 539 was a giant of a man, in prewar times the chief boatswain’s mate on the battleship North Carolina, and heavyweight boxing champion of the Pacific fleet. His officer corps consisted of six ensigns fresh from a brief period of training, and all on their first sea voyage! We set out for Great Britain, in the usual zigzag convoy. The skipper had so little confidence in his officers that he never left the bridge during the 13-day voyage to Cardiff, Wales. He knew very well that his career as an officer depended on avoiding any disaster, such as ship collision while in convoy, always a risk. I sustained him by thrice-daily deliveries of the most atrocious drink every concocted: three ounces of Lejon brandy, a large supply of which I found in the medical stores, labeled for “resuscitation.” It worked.

The Normandy Invasion

It is difficult to describe the high state of morale and adventure that pervaded the Allied soldiers and sailors as we set out from England on the early evening of June 5, 1944. We felt we were on a noble crusade! We were garbed in heavy clothing impregnated with something said to neutralize poison gas, but no gas attack occurred.

We disrobed as soon as possible. The scene in the Channel is embedded in my memory: ships of all sorts, as far as the eye could see. The sight of this massive armada must have demoralized the German defenders when they viewed it at first light on June 6. We carried soldiers of a U.S. division slated for Utah beach. My LST had been designated a medical emergency ship and flew a special signal flag to that effect. I had been joined by two middle-aged Army physicians, one an obstetrician, the second a urologist. Neither had any previous experience in emergency surgery, but they performed magnificently in the emergency I describe below. I also had a group of Navy medical corpsmen, to whom I wish to pay tribute for their skill and dedication to the tasks we encountered. We were loaded with medical and surgical supplies, together with, for the first time, typed blood for transfusion.

Our approach to and landing on Utah beach was hindered only by occasional gunfire, and no air attack; we unloaded and withdrew without casualties. On the second day a destroyer hit two mines and blew up, near us, producing in her crew a large number of compound fractures and associated head injuries. These men were cast overboard as the crew abandoned ship. Many of them were rescued by a PT boat, which quickly drew alongside my LST. I swung by rope to the deck of the PT boat and began loading the injured into stretchers for hoisting to the deck of the LST. Summary: 39 compound fractures—in two limbs in many, and of three limbs in one (we saved him!). We stabilized the fractures as best we could, gave morphine and intravenous transfusion, and saved almost all from early death from vascular shock, which I knew well as a student of Alfred Blalock. We were then ordered to the beach to receive 200 walking wounded; many of them were, however, severely wounded and brought aboard in stretchers. We lashed the stretchers to the walls of the tank deck of the LST, three high, and began a survey of wounds. We found many of these soldiers in extremis and gave emergency treatment to those threatened by immediate death. Our 48 hours of continuous work with these wounded men saved many. However, as the death rate began to mount I became desperate. I knew there was a superb British emergency hospital in Southampton, only 5 hours sail away at flank speed. I persuaded our captain to make requests that we leave at once for Southampton. All requests were denied by the British commodore in command of our flotilla. He feared German submarine action in the channel, and perhaps correctly so, but no such attack ever occurred. We sat for 5 days as the death rate among our casualties rose. Finally we sailed to Southampton and off-loaded all surviving wounded to the hospital. I expressed some criticism of the British commodore’s refusal to allow our departure, though of course he was right, in military terms. My criticisms apparently became known and were passed up channels, for Eisenhower had commanded that no American officer utter any criticism of a British colleague! His order was the first thing I saw posted on the bulletin board when I arrived in North Africa. As a result I barely escaped being cashiered from the Navy, as I recount below.

During the months from June to November, 1944, we worked continually on the supply run between England and the French coast, and later to Cherbourg. We frequently worked out of the Tilbury docks in London, and I observed the destruction imposed on the British by the German air offensive. I was impressed by the grit and determination of the Londoners, who worked continuously through a host of continuing air attacks.

In November of 1944 I received orders to return to the United States and report to the amphibious base at Camp Bradford, Virginia. While awaiting transport I was sent to a camp in the beautiful apple country of South Devon. One day a commander came on a visit from London, and in the washroom next morning he said that they (meaning those in London) had heard of my criticisms of the actions of a British officer during the Normandy invasion. “Won’t you come up to London and tell us about it.” I knew what was up. I declined, saying that I had orders to go home, and he had no orders to force me to go to London. I escaped what could have been a disaster for me.

Shortly thereafter I went by troop train to Gurock, Scotland, and boarded the Queen Elizabeth I for Boston. I remember well the arrival in Boston. The shore was filled with cheering people—not for me but for the soldiers aboard. I soon carried out my orders to go to Camp Bradford, in Virginia. While there I was able to spend several weekends at home in Roanoke and reawaken an old but until then distant acquaintance with a charming and beautiful lady. Nancy Clayton Pierpont and I were married on September 6, 1975, and began a blissful marriage that has now (in 2007) lasted 62 years and produced three children, six grandchildren, and one greatgrandchild; we hope of more of the latter to come!

However, on August 15 the war ended. I heard the news of the Japanese surrender by loudspeaker as I walked across the parade ground at Camp Bradford. One could almost hear the weights dropping from shoulders: we would not have to invade Japan! As luck would have it, I received insufficient points for discharge from the Navy because we were married after the end of the war. That cost me an extra year in the Navy.

My Postwar Year in the Navy

I was then sent to the Norfolk Naval Hospital and given charge of a medical ward filled with 150 chronically ill sailors. That I was given this responsibility shows how thin the Naval Medical Corps was in the immediate postwar year. Some of these patients had regional ileitis and had been treated disastrously by successive resections of lengths of small bowel. The disease always recurred. Many others were survivors of severe hepatitis and had compromised liver function. Several of these chronically ill men weighed little more than 100 pounds. I worked hard to improve their nutritional states. I gave my first ever medical paper on these two conditions at a Naval medical congress held at the hospital. I cited the ileitis case histories as evidence that in the absence of perforation or obstruction, surgery is not a proper treatment for regional ileitis.

But then, sea orders again. I was named the medical officer on a new ship of the train then under construction in Tampa, Florida, the Cadmus. I was sent first to the Brooklyn Naval Supply Yard to check the medical supplies for the ship; then to Newport, Rhode Island, to care for the crew then in training there; and then for precommissioning work in Tampa. The ship was magnificent and included what was virtually a hospital: 26 beds, isolation ward, operating rooms, special rooms for treatment of venereal disease, etc. The Cadmus was a huge repair ship, designed to repair war vessels at sea. The commissioning work completed, the crew aboard and training, we departed on the shake-down cruise, from Tampa around Florida, and then north into the Chesapeake Bay. There, just as the Cadmus was to leave for extended ocean duty, I received orders to proceed to Washington for discharge from the Navy. They were the happiest orders I ever received.

Transition to Physiology: Fellowship Years

I left the Navy in July 1946 and immediately sought a residency in neurosurgery, my long-term goal in medicine. Dr. Walter Dandy had died in April 1946. I learned upon returning to Hopkins that Dr. Blalock would make no house staff appointments in Neurosurgery until Dr. Dandy’s successor was named. I immediately went to Duke University in Durham, North Carolina, for an interview with their Professor of Neurosurgery, Dr. Barnes Woodhall, a Hopkins graduate, former resident surgeon in the Hopkins Hospital, and a distinguished neurosurgeon. He was very glum, saying there were a halfdozen candidates ahead of me. I then on impulse asked him how he would regard me if I spent an intervening year working with Philip Bard at Hopkins. Woodhall jumped from his chair, tapped me on the chest, and declared that if Bard would have me around for a year, I could have his residency. I returned to Baltimore for an interview with Dr. Bard. He came in to see me in typical Baltimore August weather. He recounted his wartime experience, off Nova Scotia, in LSTs with Denny-Brown, testing candidate preventive drugs for motion sickness. Then:

BARD: Do you think there is a psychological factor in motion sickness?

VBM: NO.

BARD: Come in September.

I was astonished and suggested that he might wish to reconsider, and then asked him to write to me in Roanoke. That tore it: there was no letter, just a request to come in September. I arrived September 1 to learn by telephone that he was writing at home. He obviously did not know what to do with me. I suggested a month’s reading in the Welch Library. He was delighted, and so was I. Thus I conjecture that I am perhaps one of the few neurophysiologists of my generation who has read (almost) all of Sherrington. I also read Cannon, Bard, Woolsey, Forbes, Adrian, and a good deal of clinical neurology, and I studied neuroanatomy intensely in preparation for the coming year.

In 1946 the Department of Physiology contained five faculty members: Philip Bard, its director; Chandler Brooks, that year on leave with Eccles in New Zealand; Clinton Woolsey; Evelyn Howard, an endocrinologist; a newly arrived neuroanatomist, Jerzy Rose; and a superannuated graduate student, Reginald Bromley, just returned from six years in the Canadian Army. Bard had appointed six postdoctoral fellows in that first postwar year: H. T. Chang, from China; LeMessurier, from Australia; Evelyn Anderson, an endocrinologist; Leonard Jarcho; Elwood Henneman; and myself. The department contained a library, one telephone line, an animal room, an operating room, and an ancient electrophysiological rig Woolsey had brought back from the Johnson Foundation in the mid-1930s. That was it.

That sounds dreary, but exactly the opposite was true, for the department was pervaded with an electric excitement about research on the physiology of the brain. That atmosphere was cultivated by Philip Bard himself. He exhibited in a powerful way what was then the prevailing atmosphere at Hopkins, which I term “the expectation of excellence.” He simply assumed that we were all skilled investigators, which we were not (and he knew it); that we were all well-informed neuroscientists, which we were not (and he knew it); and that we were all in the process of making important discoveries about the function of the brain, even though we were beginners (and he knew it!). I experienced this strong pull from above from the dean, from my revered teachers of medical school years, including my Chief of Surgery, Dr. Blalock. They all seemed to think that I was better than I thought I was! This was a strong and sustaining influence on me during my early years in neurophysiological research.

I abandoned my career goal of neurosurgery and stayed a second year as a fellow. During that time I assisted Bard in a number of investigations. The first was to determine whether the visceral afferents played any role in producing motion sickness. He prepared and I nursed and tested five dogs with high spinal transections, vagotomies, and total sympathectomies. The result: no change in swinging time to salivation, the prodromal sign of motion sickness. The second was aimed to determine if any particular forebrain structure was critical in the control of rage, which he had shown in his doctoral work at Harvard to follow decortications. We studied cats with a variety of forebrain removals. The result was that removal of the neocortex alone, leaving all limbic structures intact, produced placid animals who did not display the violent rage reaction of wholly decorticated cats. Subsequent removal of the surviving limbic structures uncovered the classical rage reaction (Bard and Mountcastle, 1947). In the third study we sought to determine if the removal of any part of the temporal lobe or subjacent structures of the forebrain would convert the wild and unmanageable macaque monkey into the placid and easily handled animal produced by large temporal lobe removals. We found that bilateral removal of the amygdaloid complex produced the placidity described by others. This work was never published.

During these years I began electrophysiological experiments with Elwood Henneman, later Professor of Physiology and Chair of the Department at Harvard. We mapped with gross electrode recording the patterns of representation of the body in the thalamus of cats and monkeys (Mountcastle and Henneman, 1949, 1952).

At the end of my fellowship years I became a member of the department and abandoned my career goal in neurosurgery. I was encouraged by Bard to begin my own research program. I was given total freedom to do as I wished and allowed 6 years of daily laboratory work with no press to publish, no requests that I ask for external support, and only 9 to 10 weeks of teaching in each year. However, even though most of the departmental members were neurophysiologists, we were obligated to teach the general course in physiology for students of medicine. My first assignment was five lectures in gastrointestinal physiology. They took me a month to prepare.

During those years I taught myself neurophysiology by repeating many of the classical experiments—for example, the spinal cord preparation used by Lloyd and Eccles. This proved useful when I began a study of the central projections of deep afferents with two of Dr. Bard’s postdoctoral fellows: Miguel Covian, later Professor of Physiology at Ribeirao Preto in Brazil, and Clinton Harrison, later a prominent neurosurgeon in Baltimore. We stimulated the nerves to deep structures and monitored the composition of the afferent volleys by recording the ventral root reflex discharges they evoked. We confirmed the well-known projection of muscle afferents to the cerebellum and sought to determine which components projected to the cerebral cortex, with indifferent success. We also observed a hitherto unknown form of somatic sensibility, that light mechanical stimulation of the periosteum evokes an input to both somatic sensory areas of the cerebral cortex. The periosteal afferents are so sensitive that they respond to even a light mechanical stimulus to the overlying skin, and I believe they must play a role in tactile sensibility (Mountcastle, Covian, and Harrison, 1950).

My first postdoctoral fellow, Edward R. Perl, arrived in 1950 and expressed an interest in the small afferent fibers and the neural mechanisms in pain. Perl was already a much more experienced investigator than I; while a medical student at Illinois he had devised a method of measuring cardiac output by recording changes in impedance across the chest wall. He devised a sensitive pressure clamp, and with it he was able to block the A-fiber component of a dorsal root volley and observe the reflex discharges produced by a pure C-fiber input. He observed the widespread ventral root discharge pattern predicted by what was known of the flexion-crossed extension reflex evoked by nociceptive input. This work was left unfinished when Perl was called away in the doctor draft. Edward Perl continued his interest in the central neural mechanisms in pain throughout his distinguished career, first at Utah, and then as the long-time Chair of the Department of Physiology at the University of North Carolina, a pattern of discovery he continues to this day.

I interrupt recounting this story to express my great admiration for and gratitude to the individuals who came to work with me in CNS physiology in following years. Many of these individuals were already sophisticated investigators when they came and contributed ideas and techniques I would not otherwise have had. They number 48, of whom 33 at this writing (2007) have become professors in their own institutions. Thirteen were graduate students. I name them in alphabetical, not temporal, order.

Carlos Acuna

Richard Andersen

Sven Anderson

Pradep Atluri

Frank Baker

Alvin Berman

James Campbell

Giancarlo Carii

Mirko Carreras

Ian Darian-Smith

John Downer

Charles Duffy

Robert Dykes

Solomon Erulkar

Apostolos Georgopoulos

Edward Glaser

Gundez Gucer

Thomas Harrington

Clinton Harrison

Juhani Hyvarinen

Kenneth Johnson

Cecil Kidd

Hans Kornhuber

Robert LaMotte

James Lane

Randall Long

James Lynch

Michael Merzenich

Mark Molliver

Brad Motter

Hiroshi Nakahama

Edwardo Oswaldo-Cruz

Edward Peri

Gian Poggio

Thomas Powell

Barbara Renkin

Rodolfo Romo

Sten Skoglund

Michael Steinmetz

Tadaaki Sumi

William Talbot

James Taylor

Thomas Yin

With the progress of central nervous system (CNS) physiology over the years, the experiments became increasingly complex, particularly in the era of the waking monkey experiment, and could only be executed by the collaborative effort of individuals with different skills. William H. Talbot assumed control of our computer operations and wrote all the training and collection programs, at first on the original LINC and then with PDP 11s. Edward H. Ramey designed much of the specialized electronic equipment needed and manufactured it in our shops, with the help of Victor Meinhardt. We were fortunate to have the collaboration of a skilled engineer from our Applied Physics Laboratory, John Chubbuck, who designed and had manufactured our complex stimulating apparatus. Belan Fortune, a skilled histologist, provided serial sections of all our experimental brains. These individuals contributed magnificently to the success of our research programs, which grew to occupy four recording laboratories.

Single-Neuron Studies of the Somatic Afferent System

By the year 1948–1949, Adrian’s method of single-neuron analysis had become the dominant mode of research in CNS physiology. It is worth noting that virtually no one in the field was entranced by the study of single neurons per se, but all sought to reconstruct population events by studying neurons one by one. This of course lost what may be of critical importance: the time relations between the impulse discharges of elements of the population, now under intensive study in the new century. Jerzy Rose and I began a program using this method in study of the somatic afferent system, beginning in the cat ventrobasal complex. We made a quantitative study of the response properties of thalamic neurons but at this level of the system saw little other than a tenacious replication of the first-order input, and little sign of what we had hoped to find—some aspect of neuronal processing suggestive of perceptual operations (Rose and Mountcastle, 1954). During those long days and nights I learned a great deal about the history of Poland, and he something of Stonewall Jackson’s genius in the Valley Campaign.

We then set about separate studies of the cerebral cortex, he in the auditory cortex together with Philip Davies and a graduate student, Solomon Erulkar, later a professor of pharmacology at the University of Pennsylvania, and I in the somatic sensory cortex, together with Davies and Alvin Berman, a graduate student, later a Professor of Neuroscience at the University of Wisconsin. The technical problem of stability was solved by Davies, who devised a closed recording chamber that stabilized the cortical surface within the chamber; he then worked with both of us in the separate studies.

My own studies are described in two papers of 1957, in which I described the columnar organization of the cerebral cortex (Mountcastle, 1957; Mountcastle, Davies, and Berman, 1957), Evidence for columnar organization is simple and convincing and can be demonstrated on any experimental day. To wit: in a microelectrode penetration made vertically to the cortical surface, one encounters at each succession of depths neurons with similar functional properties, which we called “modalities,” with overlapping peripheral receptive fields. In contrast, when penetrations are made slanting across the vertical dimension of the cortex, one encounters successive blocks of tissue containing neurons with different properties. Many friends have inquired why the description of this general principle is contained in the paper authored by me alone. The answer is: by request! My two colleagues were so apprehensive over my proposal of such a radical hypothesis that they sought to disavow themselves from it! Indeed, it is not possible to exaggerate the calumny I was subjected to over this proposition, and with the most vigor by my colleague Jerzy Rose. He and most other anatomists had been trained in the schools of Nissl cytoarchitecture, Rose by the Vogts themselves, and the idea of layered cytoarchitecture dominated the scene; some even designated different layers for different functions! All this was before the revival of Cajal-type studies of the cortex. One critic said that the idea was just the “musings of an old man,” and I was only 39! Columnar organization was confirmed in a few years for the visual cortex by Hubel and Wiesel, and then by many others for the homotypical cortex as well, and it is now part of the cortical zeitgeist.

In earlier studies of the thalamus I had observed neurons in the posterior nuclear group that responded specifically to noxious stimuli. I then took up this study with my long-term colleague and friend, Gian F. Poggio, from Genoa, using the method of single-neuron analysis. We defined the posterior nuclear group as one receiving a powerful nociceptive input, and this has now been confirmed as one of the relay nuclei for the pain system in primates, including humans (Poggio and Mountcastle, 1960). Poggio remained for many years as a professor in the department, devoting his independent efforts to study of the visual cortex, with original and important results.

The Primary Sensory Cortex in the Primate

I then took up the study of the monkey postcentral gyrus in the anesthetized macaque monkey. One day, as I was laboring to clean up the lab after a long experiment, the fifth in the series, a young man wandered in and introduced himself as Tom Powell, adding that he had come from Oxford to work with me. I had no prior knowledge of his coming; I think it must have been arranged between Bard and LeGros Clark, then Head of Anatomy at Oxford. What luck for me! We began an intensive, productive, and pleasant collaboration in experiments on more than 50 monkeys, and a warm friendship that lasted until his death. We obtained convincing evidence for the specificity for place and modality from the periphery to the postcentral cortex, documented extensively the columnar organization of the cortex, showed the gradient of modality representation from area 3 to 1 to 2, and made attempts to study the temporal patterns of neuronal activity. The results are described in four papers in the Hopkins Medical Bulletin (Mountcastle and Powell, 1959a, 1959b; Powell and Mountcastle, 1959a, 1959b). This pleasant relation was sustained in several following years, in each of which Powell returned to Hopkins for a period of 2 months to join us in teaching our combined course in neuroscience for students of medicine.

However, there remained the problem of the anesthetized state, which we surmised affected powerfully the dynamic activity in the nervous system, just what we wished to study. We had long dreamed of studying the somatic system as an animal worked in a somesthetic task. It would be a decade before we reached that level.

Before that, an important event: one day a slightly built, partially bald man of early middle age appeared in my office. He declared, “I have come to become a neurophysiologist.” He was Gerhard Werner, who became a valued colleague in research, and a lifelong friend. He was subsequently Professor of Pharmacology and later for a time Dean of the Medical School of the University of Pittsburgh.

Studies in the Unanesthetized State: Position Sensibility

I made a denervated head preparation by intracranial, retrogasserian transection of the trigeminal nerves and transaction of the upper cervical dorsal roots. These animals required intensive postoperative nursing to treat the keratitis that followed and tube feeding for the first week. We devised a way of positioning the head in the Horsley-Clarke coordinate system by holders touching only denervated regions of the head. Electroencephalogram (EEG) recordings during the experiments showed that these animals varied from full wakefulness to light sleep, from which they were readily aroused by sensory stimulation, a least for the first few hours. Successful experiments with single neuron recording in the ventrobasal complex were made in 35 monkeys prepared in this way, with neuromuscular blockade and artificial respiration. We observed that the static properties of place and modality were as specific as they had previously been observed to be with deep anesthesia. However, there was a remarkable difference in the dynamic properties of the system. The recovery cycles of thalamic neurons virtually matched those of first-order fibers, and the system followed stimulus frequency to high levels (Poggio and Mountcastle, 1963).

We then planned the study of position sensibility, recording first in the monkey’s ventrobasal complex. This required a device with which we could rotate the joints of the monkey’s limbs, painlessly, at different speeds to different angles. Previous studies had shown that the first-order afferents innervating the joints and the central cells to which they are linked at successive stages of the system are sensitive indicators of the rotation of the joints. It is this relation we set out to study quantitatively. Such an experimental objective raised difficult problems. The first was what measure to use for the neural activity. We settled on frequency in each successive short interval of time, usually 200 milliseconds. The second is the ubiquitous variability of the spontaneous and evoked activity of central neurons; we studied this separately (Werner and Mountcastle, 1963).

We paid particular attention to whether the “deep” neurons we studied were true joint neurons or were activated from muscle afferents. We devised a number of controls that we applied to each neuron before designating it as one activated by joint rotation and not from muscle stretch afferents. We studied more than 1000 neurons and identified 410 as “joint” neurons. We observed a clear sign of integrative action in the system. Whereas the receptive angles of first-order joint afferents are narrow and double-ended, those of thalamic neurons are very wide and smooth, and always maximal at full extension or flexion; they respond to movement in only one direction. Thus the thalamic neuron expresses in its receptive angle and discharge pattern a running integral of the inputs from a number of first-order afferents with narrow excitatory angles scattered along the path of movement. We found the relation between joint angle and neuronal discharge to be best fitted by a power function with an exponent of 0.6 to 0.7. This finding was of interest in relation to Steven’s psychological law defining power functions for a wide variety of stimulus-intensive continua in human subjects (Mountcastle, Poggio, and Werner, 1963, 1964).

Study of First-Order Afferents

We found it relatively easy to dissect free and record from the large mechanoreceptive afferents in monkey peripheral nerves. Werner and I did this for those innervating the hairy skin of the arm (Werner and Mountcastle, 1965), and then in studies over a number of years we defined the static and dynamic response properties of each of the large mechanoreceptive sets innervating the glabrous skin of the monkey hand (LaMotte and Mountcastle, 1975; Mountcastle, LaMotte and Carii, 1972; Mountcastle, Talbot and Kornhuber, 1966; Talbot, Darian-Smith, Kornhuber and Mountcastle, 1968; Werner and Mountcastle, 1968). We used this information to determine the integrative action within the system by comparing it with recordings made at thalamic and cortical levels, and for comparison with psychophysical measures of the several modalities in monkeys and humans. The results of these studies support the general conclusion that the relation of the primate to the external world, as detailed by the somatic afferent system, is determined by the nature and transducer properties of the first-order fibers. These transduced images of peripheral stimuli are transmitted with fidelity through the system to the postcentral somatic sensory cortex. We also observed that fibers of a given modality class, with overlapping peripheral receptive fields, were segregated into bundles in peripheral nerves, a peripheral precursor of the columnar organization of the sensory area of the cerebral cortex.

Changing Responsibilities

Toward the end of the 1950s I began to receive invitations to lecture, both at home and abroad. I do not lecture easily and consider myself poor at it, but I always sought to include in each lecture original research results not previously published, and this seemed to arouse interest. In my career I gave many named lectures in the United States and foreign countries. I found these visits of great value to me because they gave me the chance to meet other neuroscientists and to see their laboratories. During the early years of the development of systems neuroscience there were so many problems evident to all that a sense of competition seldom arose; there were always new problems over the horizon. I also felt obliged to entertain requests that I serve the National Institutes of Health (NIH), and for 3 years in the late 1950s I was first a member of and then Chairman of the study section on physiology. We judged grant applications over the entire field of physiology, including neurophysiology. Ted Bullock and I were the only neurophysiologists on this committee, so decisions on grant applications in this area commonly fell to us. We had many serious but friendly confrontations, largely because Ted, as the superior biologist he was, believed that all biological structures were of equal value as research objects, while I, following the NIH charge to solve the problems of human disease, pled for research in mammals, and in primates if possible. Ted usually won. When NIH began to fund training grants, I also served on that study section, and I served a term on the Advisory Council of the National Eye Institute.

I step ahead of my story to say that in 1964 I succeeded Philip Bard as Director of the Department of Physiology. I devoted considerable effort to enlarging the purview of the department by persuading superior scientists and teachers such as William Milnor and Kenneth Zierler to join us, and I obtained sufficient resources to support a number of young physiologists in fields outside my own. The heaviest duty was participating in decisions important for the future of the Medical School. I served on seven committees to nominate new directors of departments. This involved study in fields outside my own, reading the publications and interviewing candidates, and sometimes visiting them on their home ground. At Hopkins at that time these decisions were kept in the hands of faculty committees; we passed to the Dean one name at a time. If his recruitment efforts failed, we passed him a second name. We declined occasional requests to provide the dean with a list from which he would choose.

I found the duties of Director of a department very light, particularly with the help of a talented secretary-administrator, whom I describe below, and I was able to continue my research program with sustained vigor. I usually finished all office work by 9:00 AM and then departed for the laboratory.

The Department of Neurology

I was chairman of a succession of committees working to create a Department of Neurology, which Hopkins had never had. Neurology had for nearly a century been a small unit in the department of medicine. When I made the proposal to the Advisory Board of the Medical Faculty that we establish a Department of Clinical Neurology, the most persuasive argument I could use was that of the 10 classes of Hopkins students of the 1950s, not a single student had gone into the specialty of clinical neurology! It was also possible to persuade our Professor of Medicine, A. M. Harvey, that clinical neurology went beyond the treatment of disease to the area of brain and behavior. He immediately became a strong advocate. My colleagues on the Advisory Board were persuaded by these and other arguments and quickly passed the resolution establishing the department. Our Dean, Thomas B. Turner, had just at that time obtained funds for two endowed chairs, and he assigned them to the new department; this itself contributed greatly to its success. Guy McKhann and Richard Johnson accepted our invitation to occupy those chairs, and over the years they and their successors have built a world-class department.

Earl Walker, our Professor of Neurosurgery, had worked vigorously with me on this proposition but remained doubtful that we would obtain approval of the board. In fact, we bet a bottle of champagne on the outcome. Within 20 minutes after my phone call telling him of the successful vote, he came walking down the hall to my office, a bottle in his hand! In my time at Hopkins, Earl Walker had the widest and deepest knowledge across the neurological disciplines of anyone; I admired him greatly. I learned a good lesson from this enterprise: when making a proposition that involves space and lots of money, for which every department director is necessarily hungry, it is first necessary to show your colleagues that none of the resources you ask for will rebound to yourself. This leaves the proposer in a good position, for then his arguments are perceived as genuine.

The Society for Neuroscience

One day in late 1969 I received a telephone call from Ed Perl: would I agree to stand for election as the first President of the newly forming Society for Neuroscience? I asked the identity of my opponent. He replied, “Seymour Kety.” I was so certain that Kety would win, I agreed. I was elected and have often suspected that my friend Seymour campaigned for me! It is important to note here that the creation of this society is largely due to the efforts of Ed Perl. He had worked for 2 years gathering support, in both people and funds, and in persuading the neuroscience community that one overarching society was preferable to alternatives. Ed Perl himself wrote the constitution and bylaws of the society, by which it is run to this day. He has given a description of the formation of the society in his autobiographical chapter in Volume 3 of this series.

My immediate task was the planning for the first general meeting of the society. It was held in 1971, when the society already had more than 1000 members. The meeting was a great success, marked by the obvious joy that scientists from different disciplines of neuroscience felt at being together. More than 300 papers were presented. When I went to the podium to give the first presidential address, I looked into the audience to see Ragnar Granit and John C. Eccles sitting in the front row. These then already famous neuroscientists had traveled from distant places to attend our meeting. I knew we were home.

The society has grown enormously since then, and more than 30,000 attend its annual meetings. Many of these young men and women are attracted by the problems of brain function and wish to devote their lives to solutions. That raises a problem, for it is unlikely that there will be sufficient resources to provide positions and independent laboratories for each of them. There is an increasing tendency for them to serve many years as postdoctoral fellows, often in teams clustered around a senior neuroscientist. Obviously they have not been able to initiate their own, independent programs. There is no clear solution to this problem, absent unlimited funding.

I now return to the description of my own research program.

Study of the Postcentral Cortex in Unanesthetized but Immobilized Monkeys: Choice of Flutter-Vibration as Model for Study

We first established in psychophysical experiments that monkeys and humans have similar capacities to discriminate between the frequencies and amplitudes of mechanical stimuli delivered to the glabrous skin of their hands. We had previously defined the response properties of the large mechanoreceptive afferent fibers innervating the glabrous skin of the monkey’s hand in terms of their thresholds to oscillating mechanical stimuli. We found the Meissner afferents (QA) to be most sensitive in the low-frequency range of 10 to 80 Hz, and the Pacinian afferents (PC) to be most sensitive in the high-frequency range of 80 to 300 Hz. The slowly adapting Merkel afferents (SA) entrained at very low frequencies, far below human thresholds. This was later confirmed for the SA neurons in the postcentral cortex, thus providing an example of a beautiful neural code that is not used for sensation/ perception—at least not for those we could test. The overlapping threshold curves for the QA and PC fibers blanketed the detection threshold curves for monkeys and humans. We termed this the dual sense of “flutter-vibration” and found that it depended critically upon the postcentral somatic sensory areas (LaMotte and Mountcastle, 1979). We then began to study the neural events in the postcentral somatic sensory cortex activated by oscillating mechanical stimuli delivered to the hands of monkeys. We again chose to work in unanesthetized animals, free of nociceptive input. We fixed the heads by grasping a knob previously implanted on the skull, maintained the animal under neuromuscular blockade, and held end-tidal CO₂ and body temperature within normal limits. These animals oscillated between sleep and wakefulness, as monitored by EEG recording, but after some hours passed into a state of “coma” from which they could not be aroused; we then terminated the experiment.

We found that each of the three classes of large mechanoreceptive afferents innervating the glabrous skin of the monkey hand sends projections over relatively isolated channels of the somatic system, to and through the postcentral somatic, and that each has a privileged access to perception. We confirmed in this state all the static and dynamic properties of postcentral neurons we had observed in a series of studies dating back to 1959 (Mountcastle, Steinmetz, and Romo, 1990b; Mountcastle, Talbot, Sakata, and Hwarinen, 1969). However, I concluded that the unanesthetized, neuromuscularly blocked animal was in an abnormal state, and that progress depended upon work in the waking, behaving animal. That opportunity soon arose.

The Waking Monkey Preparation

A revolution in the mode of research in CNS physiology occurred early in the decade of the 1960s. That was the introduction of the “waking monkey experiment,” which has now become the standard method of research in both human and nonhuman subjects. The principle is simple: record some aspect of behavior while observing simultaneously the brain activity thought relevant to it, in the monkey case with the method of single-neuron analysis. Simple as it sounds, the execution is complex and difficult. This was the legacy of Berger and had been pursued for many years after 1932 using EEG recording in humans. The result had been the important clinical discipline of electroencephalography. Many attempts had been made to correlate EEG patterns with behavior; significant success had followed studies of sleep and wakefulness. However, attempts to correlate EEG patterns with activity in specific cortical areas had met with only moderate success. For us, this new method allowed recording the sensory-perceptual performance of monkeys, while studying the activity of cortical neurons thought relevant to it. This major contribution was made by the late Herbert Jasper and his colleagues Ricci and Doane (Jasper et al., 1960). Jasper published a photograph of a monkey in such an experiment in the volume of the Moscow colloquium. CNS physiology has never been the same since, and one can scarcely exaggerate the thrill it was for those of us who had spent years working with anesthetized or reduced preparations to see and to work with the brain in action! The method was taken up and elaborated by the late Edward Evarts in his studies of the motor cortical mechanisms controlling movement.

In the midst of all this I visited Evarts in his laboratory to see his experiment. I left Bethesda that Friday somewhat despondent, for it was not at once obvious to me how we could immobilize the hand of the waking monkey to deliver somatic sensory stimuli controlled at the micron level. (We later achieved this by prolonged training.) The next Monday morning I glanced down the hall from my laboratory to see that same Edward Evarts striding toward me, with that great smile on his face, and carrying a large box on his shoulder. He had brought me all the gadgets—head holding and so on—for the waking monkey experiment. I used them for a year, and our adventure into this new world began.

This combination of behavioral control and electrophysiological recording in waking monkeys allows one to observe the activity of hundreds of cortical neurons, one by one, in repeated microelectrode penetrations made into a chosen area of the neocortex day after day for several weeks, in the same animal, and thus reconstruct post hoc population events. The monkeys were trained to emit the chosen item of behavior, repeated in hundreds of trials in each day’s recording session. It is of course another large step to suggest a causal relation between the two, even if they covary in a predictable way. Some other neural activity not recorded may be the critical neural event for the behavior observed! This method proved to be complex and difficult, and to depend upon the conjoined effort of several investigators with different skills. It proved so productive that I never did any other type of experiment.

The Posterior Parietal Cortex

I began the waking monkey experiments with Giancarlo Carii and Robert LaMotte, recording once again in the postcentral gyrus. We observed the specific static and dynamic properties of postcentral neurons predictable from earlier experiments, and a precise columnar organization. We also saw a direct correlation between behavioral frequency discrimination and differences in cycle lengths of the neural activity evoked by the two frequencies discriminated. This cyclic entrainment depends upon a sequential order code, for it is destroyed by a random shuffle of the temporal order of impulse intervals. We also observed in both monkeys and humans an “atonal interval,” a narrow range of stimulus amplitudes within which subjects can detect the presence of oscillating stimuli but cannot make a frequency discrimination.

In the midst of these experiments, we discovered that the postcentral neural activity evoked in correct trials did not differ clearly from that evoked when the animal made a mistake. We saw no clear neural signals of the differential discrimination process itself. Then, while recording with Robert LaMotte and Carlos Acuna we more or less in frustration moved the locus of a microelectrode penetration into the posterior parietal cortex, behind the intraparietal sulcus. What we saw on that day determined my experimental life for 15 years! Neural responses to stimuli occurred only if the animal attended to them—that is, if they seemed of interest to him. Activity occurred with projection of the arm toward objects he sought, such as food, but not during casual arm movements. Other neurons were active when the animal manipulated within a small box to obtain food, but not during casual hand movements. Neurons were observed with very large mechanoreceptive fields covering large parts of both sides of the body. Visual neurons were observed with very large and frequently bilateral receptive fields, and were sensitive to the direction of stimulus movement within those fields. Neurons defined by these functional properties are arranged in type-specific columns. All of these preliminary observations appeared as positive images of the defects we later found to follow removal of the posterior parietal cortex in monkeys (LaMotte and Mountcastle, 1979). These initial observations were confirmed and extended in the more formal studies that followed.

We then set about preparing for more extensive and better controlled studies of the posterior parietal cortex. First, I reviewed all the cases in the hospital archives labeled the “parietal lobe syndrome.” Humans with parietal lobe lesions show unusual disturbances of behavior. The most striking is a change in their perception of the body form and its relation to surrounding space, for example, in manual and visual exploration of the immediately surrounding space and a profound neglect of objects and events in that space, including their own body parts. They make errors in reaching into that space, and there are a host of other unusual signs that differ for lesions in the two hemispheres.

I made a detailed study of the cytoarchitecture of the parietal cortex and reviewed what was known of the connectivity of this region. We later found that the syndrome produced by parietal lobe lesions in the macaque monkey is a similar but somewhat fainter replica of that in humans (LaMotte and Mountcastle, 1979). John Chubbuck designed test equipment that required the animal to reach to stationary or moving targets, to fixate stationary and to track moving visual targets, to make saccadic movements between two stationary visual targets, and so on. We had already learned how to train waking monkeys to allow head fixation and to make somatic sensory detections and discriminations with stimuli delivered to immobilized hands. We now began to train them in these new tasks; it required 8 to 10 weeks of training, 2 hours daily, before monkeys were ready for recording—a major investment of time and effort for each animal. But we were ready to begin.

This experiment required the active participation of a number of investigators. Those who participated with me in the parietal lobe studies were members of successive teams: Carlos Acuna, Pradeep Atluri, Richard Andersen, Charles Duffy, Apostolous Georgopoulos, James Lynch, Robert LaMotte, Brad Motter, Hideo Sakata, Michael Steinmetz, William Talbot, and T. C. T. Yin. The two primary papers describing our initial results are Mountcastle, Lynch, Georgopoulos, Sakata, and Acuna (1975), and Lynch, Mountcastle, Talbot, and Yin (1977). Some of the papers and reviews describing the results in detail are Andersen and Mountcastle (1983); Motter and Mountcastle (1981); Mountcastle (1976, 1977b, 1978a, 1982, 1988); Mountcastle, Motter, and Andersen (1980); Mountcastle, Andersen, and Motter (1981); and Yin and Mountcastle (1977, 1979). The results of this long series of studies confirmed and extended our preliminary results given above. I will not detail them all here. The field has since attracted a number of investigators, with the result that the functions of the parietal-transcortical-frontal systems in directing attention, and in manual and visual action within the immediately surrounding space, are now well understood, at least at the first level of analysis.

The Bard Laboratories and the Department of Neuroscience

Our group in neurophysiology grew to include four separate and independent laboratories, identified as the Bard Laboratories of Neurophysiology. They were Dr. Poggio, the visual system; Dr. Georgopoulos, the motor cortex; Dr. Johnson, the somatic afferent system; and my own, the posterior parietal cortex. Together with the associated shops we put heavy pressure on space in the Department of Physiology. A grand solution was found when the Howard Hughes Medical Institute funded an additional 10th floor to the new basic science building. I suspect that my friend Max Cowan had much to do with this decision to provide new space for the Bard Laboratories. The 10th floor also housed Dr. Mark Molliver and his colleagues working in experimental neuroanatomy. The 10 years we spent in these splendid new surroundings were the happiest and most productive of my experimental life.

There was, however, another reason. The Rockefeller University was actively recruiting one of the most productive neuroscientists ever to work at Hopkins. That is Solomon Snyder, who was then a member of the Department of Pharmacology. I proposed to Dean Ross that we execute what I termed “three-cushion pool”: that we create a Department of Neuroscience, with resources sufficient to persuade Dr. Snyder to remain in Baltimore; that I step down from the directorship of the Department of Physiology, which gave the Dean freedom to develop it in other directions if he wished; and that the Bard Laboratories become a division of the new Department of Neuroscience. These proposals were executed on July 1, 1980. It seemed to be a proposal in which everyone won, and indeed, so it has evolved. I was freed from all administrative and teaching duties, and housed with all my colleagues in neurophysiology in beautiful new quarters. It was paradise! The Department of Neuroscience began in 1980 and has since established itself as a world-class center for neuroscience research, particularly in molecular neuroscience.

Study of the Motor Cortex: Output Signals of a Sensory Decision

We had never seen in all our studies of the postcentral somatic sensory cortex any neural sign of the detection or discrimination process itself. We therefore considered the hypothesis that the decision process is embedded in the multinoded, transcortical, distributed system linking the sensory area of one hemisphere to the motor cortex of the other, driving the responding arm. Pradeep Atluri, Ranulfo Romo, and I therefore undertook a study of that motor cortex in monkeys as they made discriminations between flutter stimuli delivered to their hands (Mountcastle, Atluri, and Romo, 1992). We observed a selective signal for the upcoming correct discrimination in about 25% of neurons in the motor cortex contralateral to the critical sensory cortex. The motor cortical activity began within 200 milliseconds of stimulus onset, which blankets the intracortical time for such sensory performances derived from psychophysical experiments. The motor cortical responses were aperiodic. The most interesting observation was that in trials in which the monkey made a mistake, the output of the discrimination process reaching the motor cortex was itself in error, followed by the appropriate arm response to the incorrect target. This localized the discrimination process to the transcortical system linking the sensory to the motor cortex, the transitions from sensation to action. These systems are neither sensory nor motor, in the usual sense. These problems Dr. Romo has pursued with success since his return to Mexico. This was my last experience in laboratory research. I was nearly brokenhearted to leave it, for I found no greater thrill in life than to make an original discovery, no matter how small.

The Bristol-Myers Symposium. Neuroscience: Integrative Functions

In 1989 as my first retirement loomed (I had three!), my colleagues in the Department of Neuroscience and the Bard Laboratories persuaded the BristolMyers company to hold their first symposium in neuroscience research in Baltimore. The symposium went under the title given above and was given honoring me. Some 300 scientists attended, 31 from foreign lands. Many of these visitors presented scientific posters, and major lectures were given by the following, all my longtime friends: Per Anderson, W. Maxwell Cowan, John E. Dowling, Gerald M. Edelman, Michael E. Gazzaniga, Tomas Hokfelt, David H. Hubel, Edward G. Jones, Bela Julecz, Eric R. Kandel, T. P. S. Powell, Marcus E. Raichle, and Pasko M. Rakic. A gala dinner followed the first day. I treasure the memory of this affair, and regard it as the most important honor I ever received.

The Mind/Brain Institute

In 1988, Steven Muller, President of the Johns Hopkins University, called together all members of the University working in the field of neuroscience for a general powwow on what might be done to enlarge and intensify activity in the brain sciences at Hopkins. Perhaps 50 to 60 individuals attended. I proposed to them that we create an Institute of Brain Sciences focusing on how the brain generates and governs behavior, and that such an Institute aim more toward systems neuroscience than molecular neuroscience, already blossoming in the Department of Neuroscience. Muller was enthusiastic and grasped the idea at once, and he asked me to come to his office the next Monday morning. At that time I knew Muller only casually, but over the following several years I came to recognize his superior intellect and, what was important in this case, his quick grasp of ideas foreign to his earlier experience.

Muller did not bat an eye when I said we needed $40 million for building and $60 million for endowment. He then took me aback by saying that the proposed Institute was a great thing, but that it must be on the Homewood undergraduate campus, or not be at all. This I foresaw as a handicap because the great strength in neuroscience was in the School of Medicine, where at least six departments had successful programs in this field. Finally, after much further discussion, approval of the Board of Trustees was obtained, and we went to work.

Guy McKhann stepped out of his directorship of Clinical Neurology (he was followed by Richard Johnson) to become the director of the new Institute, which then occupied a few rooms on the undergraduate campus. He planned a new building for 12 labs of a wide variety, together with all supporting shops and internal animal care facilities, including those for primates. A model of this building was constructed. Then, catastrophe struck. The University entered a period of financial stress. Guy McKhann did succeed in obtaining an endowment of $7.5 million dollars from Zanvyi Krieger, $1 million from the Merrick Foundation, and about 20,000 sq ft of space in a former physics building. The Institute began at a size reduced from that originally planned and was officially opened in 1990. Stewart Hendry, a skilled systems neuroanatomist, was the first staff appointment and has remained as an essential member of the staff since that time. The Institute was established as a part of the Department of Neuroscience of the School of Medicine, and almost all of its members have appointments in that department.

Shortly afterward, the Bard Laboratories moved with all its equipment to the Zanvyl Krieger Mind/Brain Institute, providing its critical mass. The Institute now consists of six laboratories of neurophysiology, one of experimental neuroanatomy, and one theoretical unit. This Institute, somewhat reduced in size from our original plan, has been eminently successful. Seven of the eight labs have continued external funding, and research productivity continues at a high level. I had hoped originally that such a free-standing institute, reporting directly to the President of the University, would be free of all routine teaching obligations and aim at training senior research fellows for other universities. Such was not to be the case, and the members of the Institute are now burdened with (1) their own large Ph.D. training program, (2) teaching neuroscience to students of medicine, and (3) the steadily increasing program of teaching neuroscience to undergraduates.

The existence of the Mind/Brain Institute, and its brightening hopes for the future, we owe almost wholly to the energy and foresight of Guy McKhann.

Editorial Functions

I have spent an inordinate amount of time in my life in editorial functions, mostly midnight oil work. Under some silent but powerful persuasion from Philip Bard, I assumed the editorship and wrote several chapters in two editions of the textbook Medical Physiology (13th and 14th editions). Many friends advised me not to do this, with the prediction that it would hamper my research work. I found exactly the opposite, for with these editorial duties and those listed below I enjoyed an extensive and up-to-date education in neuroscience, one which I would not have obtained in any other way. If one has to write out a chapter on a rather large subject in neuroscience, one has to know it! And, if one has to provide a critical and helpful review to an author, one has to know the subject matter! In 1957 Professor John Fulton asked me to serve on the editorial board of the Journal of Neurophysiology. Upon his death in 1960 he willed the Journal in equal parts to Yale University and to its publisher, the CC Thomas company. The American Physiological Society purchased the property rights to the journal from Yale and Thomas and asked me to become its chief editor. I accepted and recruited a distinguished group to serve with me as its editorial board, and over a few years we were able to restore this journal to its position as the leading journal for systems neuroscience, a position it retains to this day.

An even heavier editorial duty followed, in which I agreed to join my old friend John Brookhart as a co-editor of the Handbook of Physiology. Section I. Neurophysiology. This grew to nine large volumes; after the onset of Brookhart’s serious illness, the editorship fell to me alone. I had again the experience I described above, but here in spades: an intensive postdoctoral education in neuroscience.

A Decade in Semiretirement: Reviews and Monographs

After I stopped laboratory work, I enmeshed myself in scholarly endeavor and writing. During the following decade I was afforded an office in the Mind/ Brain Institute, which allowed me access to the libraries of the University and the School of Medicine, and funds to employ part-time help for library search. During that time I published a number of reviews (Mountcastle, 1995a, 1995b, 1997, 1998b) and two books: Perceptual Neuroscience: The Cerebral Cortex (Harvard, 1995) and The Sensory Hand. Neural Mechanisms in Somatic Sensation (Harvard, 2005). I retired completely from all involvement in neuroscience or in university life in November 2005, at age 87. It was about time!

Family Life

When we arrived in Baltimore in September 1946, our first child was on the way. Vernon B. III was born in March 1947, quickly followed by his sister Anne Clayton in 1948, and another son, George Earle Pierpont, in 1949. We found that having all our children so quickly, though not easy for Nancy and not exactly planned that way, was a great boon for family happiness. We lived in apartments in Baltimore for our first 6 years, but in 1952 we were able to buy a large, dilapidated brown shingle house in Roland Park. This turned out to be just the place to raise children. The house was very large, with five bedrooms, a screened back porch, and a sleeping porch off the second floor. There were a dozen children of the ages of our children in the immediate neighborhood, and a forested hill close by. We had moved there because the local public school was said to be of high quality. However, Nancy quickly returned to her premarital profession of teaching and found a wonderful opportunity at the famous Calvert School. Thus Nancy stabilized our financial life and provided a Calvert education for our three children. They went through the fine private schools of Roland Park and were admitted respectively to Brown, Vassar, and Harvard.

I look back on our children’s early childhood and adolescence as the happiest years of our lives. Our children were excellent students; each of them became National Merit Scholars, and interacted with their mother’s charm in social relations. They all participated in sports, and our youngest son was a varsity athlete at Gilman School in football, lacrosse, and wrestling. Later we all took up sailing on the Chesapeake Bay, our sons first in an International 14, and all of us later in an Alberg 30. At that time there were about 25 Albergs on the bay, mostly based in Annapolis, as we were, and there was one-design racing on every Sunday, weather permitting. After we began sailing, I took Sundays off.

Our youngest son, George, was killed in an accident in October of 1969, at age 19, while a sophomore at Harvard. We only survived this tragic period through family bonds of love and affection.

But, more about Nancy: She adapted completely to the demands of my research life. She assumed the decision-maker role in our family, saw to the education and well-being of our children, and handled with ease and charm the demands of many scientific visitors. Many of these latter were postdoctoral fellows arriving from abroad, with wives and children. Nancy housed and fed them for their first few days in Baltimore. My custom was to go to work early, come home for dinner and visits with family at 6 PM, then on many days go back to the lab and work until midnight. During those early years we made several weekend trips each year to our old homes in Roanoke and Salem, Virginia, so that our three children came to know well their four grandparents and their many first cousins.

But, more about Nancy: During her 18 years of teaching 9-year-old girls, she came to know intimately about 400 of them. Many of these are now the matrons of Baltimore. I observe a remarkable interaction whenever we go to some non-Hopkins social function in Baltimore. Nancy is quickly approached by one or more of her former students, frequently with hugs and sounds of joy. Then I observe Nancy’s remarkable performance in memory search. She first examines closely the facial features of her former student, then devolves what she sees into what that face looked like at age 9. Then the memory search begins, and within 5 to 10 seconds out comes the name, where the student went to college, whom she married, and sometimes much more. I remain the spouse in the background.

After our children finished college, Nancy and I moved to the wonderful countryside north of Baltimore and took up horseback riding, with Arabian horses. A notable event was when Nancy’s mare, whom we had bred to a famous stallion, was about to deliver. Now, the vet was late, and there was nothing for it but for me to take charge. Fortunately, I had read a good bit about it, so I delivered this colt in our barn, as two grandchildren watched through the stall door. It was an experience none of us will forget. We raised that colt with the method of never punish, only reward, with the result of a splendid horse at maturity. Finally, at our advanced ages we found it prudent to stop riding and left the country for a town house just on the edge of Baltimore City.

Mary Hilda Counselman

Every man who has led a life devoted to scientific research knows that he is indebted to a number of women who have made that life possible. I have already described the essential role of my mother and my wife in my life. There is a third, Mary Hilda Counselman, who from 1969 on was, while officially my secretary, actually the executive administrator of the Department of Physiology. She is beautifully educated, knows every rule of spelling and syntax in the English language, possesses a charming and winning personality, and knew the way to get things done within the confines of University rules. She showed throughout her career a total devotion to the welfare of the department and the people in it. Some examples: On experimental days she protected me from all except the most urgent calls and visitors, passing through only those from my wife, the Dean, or the President of the University. What is important, she could do this without offense. She welcomed fellows from abroad, found them places to live, and helped them in the sometimes difficult transition to the American culture. This was brought home to me on several occasions when, while abroad, I met with former fellows. The first question they asked was not how the research was going, or how the department was, but, “How is Mary Hilda?” She now lives in comfortable and happy retirement. My gratitude to her is unbounded.

Sunny Uplands

I made a complete withdrawal from my life in neuroscience at the age of 87 and found the sudden break just the thing for me. It had become apparent in recent years that I could no longer cope with, or enjoy, the outdoor life in our country home 25 miles north of Baltimore. In 2006 we moved to a town house just outside the city limits of Baltimore—from which the Johns Hopkins Hospital is quickly reached! I was able to fit into this new house only half the library I had accumulated (3000 volumes), but we have ready access to the University and public libraries. Here I have taken up through reading a number of old interests I had long neglected, including classical and American literature. I have been reading eagerly some of what the astrophysicists have discovered about the nature of our universe during the decades I was head down in the laboratory. What an accomplishment! I have restarted an old habit, my reading of ancient history.

The greatest delight of all is to observe the evolving lives of our six grandchildren. Our youngest granddaughter, named Nancy Pierpont Mountcastle (II), has just graduated from North Carolina State (June 2007) and is threatening to go to law school. Our next youngest granddaughter, named Julia Vemon Bainbridge, is a graduate of Boston University and has just earned a master’s degree in food science (of all things), and she wants to write in this field. She is presently an apprentice at a food magazine in New York City. Our oldest granddaughter, Leslie Mountcastle Moss, has just produced the first of the next generation, named Jacqueline Mountcastle Moss. Our three grandsons have until now escaped matrimony, but I hope for not much longer!

Selected Bibliography

Bard P, Mountcastle VB. Some forebrain mechanisms involved in expression of rage with special reference to suppression of angry behavior. Asso Res Nerv Ment Dis 1947;27:362–404.

Mountcastle VB, Henneman E. Pattern of tactile representation in thalamus of cat. J Neurophysiol 1949;12:85–100.

Mountcastle VB, Covian MR, Harrison CB. The central representation of some forms of deep sensibility. Asso Res Nerv Ment Dis 1950;30:339.

Rose JE, Mountcastle VB. The thalamic tactile region in rabbit and cat. J Comp Neurol 1952;97:441–490. [Database]

Mountcastle VB, Henneman E. The representation of tactile sensibility in the thalamus of the monkey. J Comp Neurol 1952;97:409–440.

Rose JE, Mountcastle VB. Activity of single neurons in the tactile thalamic region of the cat in response to a transient peripheral stimulus. Bull Johns Hopkins Hosp 1954;94:238–282.

Mountcastle VB, Davies PW, Berman AL. Response properties of neurons of cat’s somatic sensory cortex to peripheral stimuli. J Neurophysiol 1957;20:374–407.

Mountcastle VB. Modality and topographic properties of single neurons of cat’s somatic sensory cortex. J Neurophysiol 1957;20:408–434.

Powell TPS, Mountcastle VB. The cytoarchitecture of the postcentral gyms of the monkey Macaca mulatta. Bull Johns Hopkins Hosp 1959a;105:108–131.

Powell TPS, Mountcastle VB. Some aspects of the functional organization of the cortex of the postcentral gyrus of the monkey: A comparison of findings obtained in a single unit analysis with cytoarchitecture. Bull Johns Hopkins Hosp 1959b; 105:133–162.

Mountcastle VB, Powell TPS. Central nervous mechanisms subserving position sense and kinesthesia. Bull Johns Hopkins Hosp 1959a;105:173–200.

Mountcastle VB, Powell TPS. Neural mechanisms subserving cutaneous sensibility, with special reference to the role of afferent inhibition in sensory perception and discrimination. Bull Johns Hopkins Hosp 1959b;105:201–232.

Jasper HH, Ricci GF, Doane B. Microelectrode analysis of cortical cell discharge during avoidance conditioning in the monkey. In Jasper, HH and Siminov, GD, eds. The Moscow Colloquium on Electroencephalography of Higher Nervous Activity. (Suppl 13 of Electroencephalography and Clinical Neurophysiology). Montreal, 1960;137–155.

Poggio GF, Mountcastle VB. A study of the functional contributions of the lemniscal and spinothalamic systems to somatic sensibility: Central nervous mechanisms in pain. Bull Johns Hopkins Hosp 1960;106:266–316.

Mountcastle VB. Some functional properties of the somatic afferent system. In Rosenblith, WA, ed. Sensory communication. Cambridge, MA: MIT Press, 1961d; 403–436.

Mountcastle VB. Duality of function in the somatic afferent system. In Brazier MA, ed. Brain and behavior. Washington, DC: American Institute of Biological Science, 1961a;67–93.

Poggio GF, & Mountcastle VB. The functional properties of ventrobasal thalamic neurons studied in unanesthetized monkeys. J Neurophysiol 1963;26: 775–806.

Mountcastle VB, Poggio GF, Werner G. The relation of thalamic cell response to peripheral stimuli varied over an intensive continuum. J Neurophysiol 1963; 26:807–834.

Werner G, Mountcastle VB. The variability of central neural activity in a sensory system, and its implications for the central reflection of sensory events. J Neurophysiol 1963;26:958–977.

Mountcastle VB, Poggio GF, Werner G. The neural transformation of the sensory stimulus at the cortical input level of the somatic afferent system. In Gerard RW, ed. Processing of information in the nervous system. Amsterdam: Elsevier Press, 1964;198–217.

Werner G, Mountcastle VB. Neural activity in mechano-receptive afferents: stimulusresponse relations, Weber functions, and information transmission. J Neurophysiol 1965;28:359–397.

Mountcastle VB, Talbot WH, Kornhuber HH. The neural transformation of mechanical stimuli delivered to the monkey’s hand. In Ciba Symposium on Touch, Pain and Itch. London: C&A Churchill Ltd, 1966;326–351.

Mountcastle VB. The neural replication of sensory events in the somatic afferent system, In Eccles JC, ed. Brain and conscious experience, Pontificiae Academiae Scientarium Scripta Vera, Vol. 30. Vatican City: Academic Press, 1966a; 127–169.

Mountcastle VB. The problem of sensing and the neural coding of sensory events. In Schmitt FO, Quarton G, Melnuchuk T, ed. The neurosciences: An intensive study program. New York: Rockefeller University Press, 1967;393–407.

Mountcastle VB, Talbot WH, Darian-Smith I, Kornhuber HH. A neural basis for the sense of fluttervibration. Science 1967;155:597.

Talbot WH, Darian-Smith I, Kornhuber HH, Mountcastle VB. The sense of fluttervibration: comparison of the human capacity with the response patterns of mechanoreceptive afferents from the monkey’s hand. J Neurophysiol 1968; 31:301–334.

Hwarinen J, Sakata H, Talbot WH, Mountcastle, VB. Neuronal coding by cortical cells of the frequency of oscillating peripheral stimuli. Science 1968;162:1130.

Werner G, Mountcastle VB. Quantitative relations between mechanical stimuli to the skin and neural responses evoked by them. In Kenshalo D, ed. The skin senses. Springfield, IL: Charles C Thomas, 1968;112–138.

Mountcastle VB, Talbot WH, Sakata H, Hwarinen J. Cortical neuronal mechanisms in flutter-vibration studied in unanesthetized monkeys. Neuronal periodicity and frequency discrimination. J Neurophysiol 1969;32:452–484.

Mountcastle VB, LaMotte RH, Carii G. Detection thresholds for vibratory stimuli in humans and monkeys: comparison with threshold events in mechanoreceptive afferent nerve fibers innervating the monkey hand. J Neurophysiol 1972; 35:122.

LaMotte RH, Mountcastle VB. The capacities of humans and monkeys to discriminate between vibratory stimuli of different frequency and amplitude: a correlation between neural events and psychophysical measurements. J Neurophysiol 1975;38:539–550.

Mountcastle VB, Lynch JC, Georgopoulos AP, Sakata H, Acuna C. The posterior parietal association cortex of the monkey: command functions for operations within extrapersonal space. J Neurophysiol 1975;38:871–908. [Database]

Mountcastle VB. The view from within: pathways to the study of perception. A Dean’s Lecture at the Johns Hopkins University School of Medicine for the Academic Year 1974–75. Johns Hopkins Med J 1975;136:109–131.

Meyer RA, Walker RW, Mountcastle VB. A laser stimulator for the study of cutaneous thermal and pain sensations. IEEE Trans on Biomedical Eng 1976;33: 54–60.

Mountcastle VB. The world around us: neural command functions for selective attention. The FO Schmitt Lecture in Neuroscience for 1975. Neurosci Res Program Bull H 1976;(Supp I):1–47.

Lynch JC, Mountcastle VB, Talbot WH. TCT Yin: Parietal lobe mechanisms for directed visual attention. J Neurophysiol 1977;40:362–389.

Yin TCT, Mountcastle VB: Visual input to the visuomotor mechanisms of the monkey’s parietal lobe. Science 1977;197:1381–1383.

Mountcastle VB. The parietal lobe and selective attention. A special lecture, Soc. Neuroscience, 1976. Brain Information Service, Summaries of Symposia (Stuler, H. & C. Yingling) 1977b.

Mountcastle VB. Brain mechanisms for directed attention. The Sherrington Memorial Lecture for 1977. J Roy Soc Medicine, London 1978a;71:14–28.

Mountcastle VB. An organizing principle for cerebral function: the unit module and the distributed system. In Edelman GM, Mountcastle VB, eds. The mindful brain: Cortical organization and a selective theory of brain function. Cambridge MA: MIT Press, 1978b.

Mountcastle VB Some neural mechanisms for directed attention. In Buser P, Rougeul-Buser, A, ed. Cerebral correlates of conscious experience. INSERM Symposium No. 8. Amsterdam: Elsevier/North Holland Press, 1978c.

LaMotte RH, Mountcastle VB. Neural processing of temporally-ordered somesthetic input: remaining capacity in monkeys following lesions of the parietal lobe. In Gordon G, ed. Active touch: The mechanisms for recognizing objects by manipulation. London: Pergamon, 1978;73–77.

Yin TCT, Mountcastle VB. Mechanisms of neural integration in the parietal lobe for visual attention. Fed Proc 1979;37:2251–2257.

LaMotte RH, Mountcastle VB. Disorders of somesthesis after lesions of the parietal lobe. J Neurophysiol 1979;42:400–419.

Mountcastle VB. An organizing principle for cerebral function: the unit module and the distributed system. In Schmitt FO, ed. Neuroscience, fourth study program. Cambridge, MA: MIT Press, 1979.

Mountcastle VB. Towards a new paradigm for cerebral function. In The Hughlings Jackson Lecture for 1978 (Third Foundation Volume of the Montreal Neurological Institute). Montreal, QC, Canada: McGill University, 1980b.

Mountcastle VB, Motter BC, Andersen RA. Some further observations of the functional properties of neurons in the parietal lobe of the waking monkey. Brain Behav Sci 1980;3:485–534.

Mountcastle VB. The functional properties of the light sensitive neurons of the posterior parietal cortex and their regulation by state controls: the influence on excitability of interested fixation and the angle of gaze. In Pompeiano O, AjmoneMarsan C, eds. Brain mechanisms of perceptual awareness and purposeful behavior. New York: Raven, 1981a;676–699.

Motter BC, Mountcastle VB. The functional properties of the light sensitive neurons of the posterior parietal cortex studied in waking monkeys: foveal sparing and opponent vector organization. J Neurosci 1981;1:1–23.

Mountcastle VB, Andersen RA, Motter BC. The influence of attentive fixation upon the excitability of the light sensitive neurons of the posterior parietal cortex. J Neurosci 1981;1:1218–1235.

Mountcastle VB. State control and the cerebral cortex: directed attention and the parietal lobe. Freiburger Universitatsblatter 1981c;74:93–98.

Mountcastle VB. Functional properties of the light-sensitive neurons of the posterior parietal association cortex [in Japanese]. Seitai no kagaku 1982;33: 144–156.

Andersen RA, Mountcastle VB. The influence of the angle of gaze upon the excitability of the light sensitive neurons of the posterior parietal cortex. J Neurosci 1983;3:532–548.

Mountcastle VB. Neural mechanisms in somesthesis: recent progress and future problems. Somatosensory mechanisms, Wennergren International Symposium Series 1984c;41:3–16.

Mountcastle VB, Motter BC, Steinmetz MA, Duffy, CJ. Looking and seeing: the visual functions of the parietal lobe. In Edelman GCM, Cowan, WM, Gall, WE, eds. Dynamic aspects of neocortical function. New York: Johns Wiley & Son, 1984:150–194.

Charles HK, Massev JT, Mountcastle VB. Polyimides as insulating layers for implantable electrodes. Polyimides 1984;2:1139–1155.

Mountcastle VB. The neural mechanisms of cognitive functions can now be studied directly. Trends Neurosci 1987b;10:505–508.

Motter BC, Steinmetz MA, Duffy CJ, Mountcastle VB. The functional properties of parietal visual neurons: the mechanisms of directionality along a single axis. J Neurosci 1987;7:154–176.

Steinmetz MA, Motter BC, Duffy CH, Mountcastle VB. The functional properties of parietal visual neurons: the radial organization of directionalities within the visual field. J Neurosci 1987;7:177–191.

Mountcastle VB, Motter BC, Steinmetz MA, Sestokas AK. Common and differential effects of attentive fixation upon the excitability of parietal and prestriate (V4) cortical visual neurons in the macaque monkey. J Neurosci 1987;7:2239–2255.

Mountcastle VB. Dynamic neuronal operations within the somatic sensory cortex. In Rakic P, Singer W, eds. The neurobiology of the neocortex. New York: John Wiley & Son, 1988;253–267.

Mountcastle VB. Representations and the creation of reality. Am Soc Am Clin Climat Assn, The Wilson Lecture 1987c;99:70–90.

Mountcastle VB, Steinmetz MA. The parietal system and some aspects of visuospatial perception. In Deeke L, Eccles JC, Mountcastle VB, eds. From neuron to action. Berlin & New York: Springer-Verlag, 1990.

Mountcastle VB. The construction of reality. In Eccles JC, Creutzfeldt O, eds. The principles of design and operation of a brain. Rome, Italy: Pontificiae Academiae Scientiarum ScriptaVaria, 1990;523–548.

Steinmetz MA, Romo R, Mountcastle VB: The cortical neuronal mechanisms for frequency discrimination in the somesthetic sense of flutter. In Franzen O, Westman J, eds. Information processing in the somatosensory system. London: MacMillan, 1991.

Mountcastle VB, Steinmetz MA, Romo R. Frequency discrimination in the sense of flutter: psychophysical measurements correlated with postcentral events in waking monkeys. J Neurosci 1990b;10:3032–3044.

Mountcastle VB, Reitboeck HJ, Poggio GF, Steinmetz MA. Adaptation of the Reitboeck method of multiple microelectrode recording to the neocortex of the waking monkey. J Neurosci Meth 1991;36:77–84.

Mountcastle VB, Steinmetz MA, Romo H. Cortical neuronal periodicities and frequency discrimination in the sense of flutter. Cold Spring Harbor Symposia on Quant Biol 1990a;50:861–872.

Mountcastle VB, Atluri PP, Romo R. Selective output discriminative signals in the motor cortex of waking monkeys. Cereb Cortex 1992;2:277–294.

Mountcastle VB. Evolution of ideas concerning the function of the neocortex [in Japanese]. Adv Neurol Sci 1995a;39:698–706.

Mountcastle VB. Introduction. Computation in Cortical Columns. Cereb Cortex 2003;13: 2–4.

Books and Reviews

Mountcastle VB. Synaptic transmission. In Bard, P, ed. Medical physiology 10th ed. St. Louis, MO: Mosby, 1956b.

Mountcastle VB. The reflex activity of the spinal cord. In Bard P, ed, Medical physiology 10th ed. St. Louis, MO: Mosby, 1956a.

Mountcastle VB. Somatic functions of the nervous system. Ann Rev Physiol 1958;20:471–508.

Rose JE, Mountcastle VB. Touch and kinesthesis. Handbook of neurophysiology Vol 1. Washington, DC: American Physiological Society, 1959;387–429.

Mountcastle VB. Neuromuscular transmission. In Bard P, ed. Medical Physiology 11th ed. St. Louis, MO: Mosby, 1961b.

Mountcastle VB. Synaptic transmission. In Bard P, ed. Medical Physiology 11th ed. St. Louis, MO: Mosby, 1961e.

Mountcastle VB. The reflex activity of the spinal cord. In Bard P, ed. Medical Physiology 11th ed. St. Louis, MO: Mosby, 1961c.

Mountcastle VB. Ed. Interhemispheric relations and cerebral dominance. Baltimore: Johns Hopkins Press, 1962.

Mountcastle VB. ed. Medical physiology 12th ed. St. Louis, Mosby, 1968a.

Mountcastle VB, ed. Medical physiology, 13th ed. St. Louis, Mosby, 1974.

Mountcastle VB, ed. Medical physiology 14th ed. St. Louis, Mosby, 1980a.

Mountcastle VB. The nervous system. In Brookhart JM et al., eds., Kandel ER, sect. ed. Handbook of physiology section I. Vol I. Cellular biology of neurons, parts 1 and 2. Bethesda, MD: American Physiological Society, 1977a.

Mountcastle VB. The nervous system. In Brookhart JM et al., eds., Brooks VB, vol. ed. Handbook of physiology section I. Vol II. Motor control, parts 1 and 2. Bethesda, MD: American Physiological Society, 1981b.

Mountcastle VB. Central nervous mechanisms in mechanoreceptive sensibility. In Brookhart JM, Mountcastle VB, Geiger SR, eds., Darian-Smith I, vol. ed. Handbook of physiology section I. The nervous system. Vol III. Sensory processes. Bethesda, MD: American Physiological Society, 1984a;789–878.

Mountcastle VB. Handbook of Physiology Section I. The nervous system. In Brookhart JM et al., eds., Darian-Smith I, vol. ed, Handbook of physiology section I. The nervous system. Vol III Sensory processes, parts 1 and 2. Bethesda, MD: American Physiological Society, 1984b.

Mountcastle VB. Intrinsic regulatory mechanisms of the brain. In Mountcastle VB, Geiger SR, eds., Bloom FE, vol. ed. Handbook of physiology section I. The nervous system. Vol IV Bethesda, MD: American Physiological Society, 1986.

Mountcastle VB. The higher functions of the nervous system. In Mountcastle VB, Geiger, SR, eds., Plum F, vol. ed. Handbook of physiology section I. The nervous system. Vol V Bethesda, MD: American Physiological Society, 1987a.

Deeke L, Eccles JC, Mountcastle VB. Eds. From neuron to action: An appraisal of fundamental and clinical research. Berlin & New York: Springer-Verlag, 1990.

MountcastleVB. The evolution of ideas concerning the function of the neocortex. Cereb Cortex 1995b;5:289–295.

Mountcastle VB. The parietal system and some higher brain functions. Cereb Cortex 1995c;5:377–390.

Mountcastle VB. The columnar organization of the neocortex. Brain 1997;120: 701–722.

Mountcastle VB. Perceptual neuroscience. The cerebral cortex. Cambridge, MA: Harvard University Press, 1998b.

Mountcastle VB. Brain science at the century’s ebb. Daedalus1998a;127:1–36.

Mountcastle VB. Organizzazione modulare della neocorteccia. In Encyclopedia Italiana. 1999;3:55–73.

Mountcastle VB. The sensory hand. Neural mechanisms in somatic sensation. Cambridge, MA: Harvard University Press, 2005.

Shigetada Nakanishi

BORN:

Ogaki, Japan

January 7, 1942

EDUCATION:

Kyoto University Faculty of Medicine, M.D. (1960–1966)

Kyoto University Graduate School of Medicine (1967–1971), Ph.D. (1974)

APPOINTMENTS:

Visiting Associate, Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health (1971–1974)

Associate Professor, Department of Medical Chemistry, Kyoto University Faculty of Medicine (1974–1981)

Professor, Department of Biological Sciences, Kyoto University Graduate School of Medicine and Faculty of Medicine (1981–2005)

Professor, Department of Molecular and System Biology, Graduate School of Biostudies, Kyoto University (1999–2005)

Dean, Kyoto University Faculty of Medicine (2000–2002)

Professor Emeritus (2005)

Director, Osaka Bioscience Institute (2005–)

HONORS AND AWARDS (SELECTED):

Bristol-Myers Squibb Award for Distinguished Achievement in Neuroscience Research (1995)

Foreign Honorary Member, American Academy of Arts and Sciences (1995)

Keio Award (1996)

Imperial Award.Japan Academy Award (1997)

Foreign Associate, National Academy of Sciences (2000)

Person of Cultural Merit (Japan) (2006)

The Gruber Neuroscience Prize (2007)

In his early studies, Shigetada Nakanishi elucidated the characteristic precursor architectures of various neuropeptides and vasoactive peptides by introducing recombinant DNA technology. Subsequently, he established a novel functional cloning strategy for membrane receptors and ion channels by combining electrophysiology and Xenopus oocyte expression. He determined the molecular structure and elucidated the regulatory mechanisms of several peptide receptors as well as several G protein-coupled metabotropic-type and NMDA-type glutamate receptors. He also developed new techniques for manipulating specific components of neuronal circuitry in olfactory bulb, basal ganglia, and cerebellum, thereby illuminating aspects of the function of these networks.

Shigetada Nakanishi

Family and Childhood

I was born in a rural area called Ogaki near Nagoya on January 7, 1942, just one month after the outbreak of the World War II in Asia. Ogaki is an old castle town with a population of about 100,000 people. My ancestors up to my parents lived in Ogaki as a Samurai family for nearly 400 years. During the war, almost all areas of Ogaki were burnt by incendiary bombs. My house was relatively large for a Japanese house, having a stable, a storehouse, gardens, and a pond. Fortunately it escaped any damage from the war.

Because my sister is 8 years older than me, I received all of the attention from my parents, just like an only child. My family was relatively wealthy before the war, but inflation after the war severely hurt my family. My father was a librarian in the City of Ogaki and was too poor to adapt to the tremendous changes in the economic situation during the postwar period. My mother was a daughter of a priest near Ogaki and was forced to manage this difficult situation for my family. My parents maintained their livelihood by selling off parts of our big house one after another. However, I knew nothing about the severe situation of my family and continued to receive all of my parents’ affection during my childhood. They believed that education is the most important thing that they could give me for my future life, and they were devoted to supporting my educational career as much as they could.

During my childhood, after compulsory education of primary school and junior high school, only half of the students moved on to senior high school. Furthermore, only half of these students went on to attend universities. I went to public schools in Ogaki from primary school through senior high school. I was good in mathematics, but my most favorite subjects were chemistry and history. My parents took great care in supporting my school life and hoped that I would go to a high-ranking university in Japan. My parents, however, were very careful not to overburden me, and I enjoyed my school life during primary school and junior high school. After the war, baseball and swimming were very popular in Japan. After school, I played baseball on the school campus until sunset and enjoyed swimming in the river during summer.

Because I grew up in a rural town, I had no chance to think of my life at an international level, something which would later become necessary for my research life. When Japan opened our country during the Meiji Restoration, the Meiji government sent some elite graduates to Europe with government support to bring back the latest knowledge and technology to Japan. My grandfather was one of those engineers and was engaged in designing and constructing tunnels and bridges at the earlier time of development of the Japanese railroad after his return from England. In addition, during my childhood, several relatives of my family were university faculty members and spent several years as postdoctoral fellows in the United States. Because they often let me know about their lives abroad, I felt that the foreign countries were close to me. Particularly, one of my relatives, Koji Nakanishi, was an associate professor at the Department of Chemistry, Nagoya University after his return from Harvard University and took me to his University during my childhood. When I saw him enjoying research and discussions in the laboratory, I longed for a research life.

With respect to the choice of my major when I entered university, I wondered whether I should choose chemistry (my favorite subject) or medicine. Because my mother had a hard time after the war, she hoped that I would take a medical course and live a stable life as a clinical physician. I also thought that involvement in the cure of patients would be valuable as a life work, and I thus finally decided to major in medicine. I chose the medical school of Kyoto University, because Kyoto University is located in the quiet old capital city in Japan and the school was known to be liberal.

Medical School

In 1960, I entered the medical school of Kyoto University, in which the freshmen class consisted of 55 students. We became friendly very soon after entrance into the University. Among my classmates, Tasuku Honjo has been my best friend for more than 40 years, not only in academic life but also in family relationships. We took the same course of study in biochemistry and molecular biology, although his major concern has been molecular mechanisms of the immune system. It was not too difficult to pass the medical courses in those days. At the time I belonged to a rugby club at our medical school and played games with teams from other medical schools almost every weekend during the rugby season. During winter, I also enjoyed skiing in the Japan Alps. I played a lot of mah-jongg games with classmates, which was a most popular pastime for university students.

The medical course consisted of 2 years of premedicine, 2 years of basic medicine, and 2 years of clinical medicine. During the basic medical course, I was excited by the superb biochemistry lectures of Osamu Hayaishi who came to our school at the age of 38 after being a laboratory chief at NIH. Several student-initiated journal courses also took place among our medical students. I participated in some of these courses such as modern physiology and oncology and was impressed with some of the new developments in these fields. I had interest in the subjects of internal medicine and pediatric medicine within the clinical medical course and during the poly-clinical course. I felt that clinical practice in these fields would be valuable as a life work for my future. During the clinical course, however, the etiology of many diseases was poorly understood and, in every case, was explained by either hereditary inheritance; disorders of the immune, nervous, or endocrine systems; nutritional deficits; and so on. I was deeply disappointed with the lectures on clinical medicine.

I very much enjoyed the life of a medical student and safely passed the graduate examination in 1966. I then took a one-year internship course at Kyoto University Hospital. However, noninvasive imaging technologies such as computed tomography and magnetic resonance imaging were not available yet, and the tool of biochemical and pathological examination was not well developed. Therefore, although I was greatly interested in dealing with patients, I could have no self-confidence that I had examined and treated my patients substantively. Because the curriculum of the internship course was not well organized in those days, I made time to work in some laboratories of basic medicine and was involved in helping out their research work. Through this activity, I became gradually more interested in research on basic medicine and began to think that I should go into basic medicine to explore the mechanisms of diseases rather than to practice in clinical work.

My mother strongly opposed my decision to go into basic medicine, because she believed that I was not the type of a scientist who must work all day long conducting research, and because she hoped that I would return to my hometown as a clinician in the future. My father supported my decision under the condition that it was made under sincere and sufficient consideration. When my parents later saw that I had been heartily enjoying basic science and had been accredited for making some scientific achievements from the scientific world, they were honestly delighted that I had made a correct decision.

Graduate Course

For my graduate studies after the one-year internship, I entered the Department of Medical Chemistry in 1967, which was organized by Osamu Hayaishi and Shosaku Numa. Numa was supposed to come back from Germany one year later. I chose Numa’s laboratory and received training from an Associate Professor Masamichi Tachibana in the first year of my graduate course. The department was large, consisting of more than 50 scientists including staff, graduate students, and researchers from several companies. In this department, a journal club (seminar) took place at lunchtime every day and a progress report meeting was held on every Saturday. In the journal club, the laboratory members introduced a wide variety of topics covering many different biological fields. The members were highly talented and made very strict and effective discussions in the journal club and the progress report meetings. The policy of training by both professors was that science is an international activity, and it is essential to make scientific achievements in Japan that are widely recognized at the international level.

In the first year of the graduate course, Tachibana was indeed a good mentor. He dedicated his time to training a young scientist, which highly influenced my scientific career. He taught me several important principles of biochemical research. For example, because biochemical approaches are based on chemical analysis, it is essential to investigate the biological system as quantitatively as possible. It is also important to establish an easy and reproducible methodology to develop a new field and to perform research as logically as possible on the basis of a step-by-step progress. The subject in which Tachibana was engaged was whether the same type or different types of carbamyl phosphate synthetase are responsible for production of carbamyl phosphate, which is the first metabolite for the urea cycle and for pyrimidine biosynthesis. I simply followed the procedure by Tachibana and fortunately disclosed that two separate types of the enzyme exist in the respective metabolic pathways and are regulated differently by the end products of the two pathways. I was deeply impressed with my results, in which a metabolic mechanism was explained at molecular levels and felt that biochemical approaches were a good fit for my sensitivity and thinking about research work.

In the next year, Shosaku Numa returned from Germany and continued on his life work concerning acetyl-CoA carboxylase, which is a rate-limiting enzyme in the metabolic pathway of fatty acid synthesis. He assigned me to work on protein synthesis and degradation of this enzyme by its purification and antibody production. However, acetyl-CoA carboxylase is cold sensitive and too unstable to be purified. This enzyme was known to require an allosteric activator (citrate) to be maximally activated in the enzyme assay at room temperature. I hit on the idea that citrate may stabilize acetyl-CoA carboxylase at room temperature, which could make it easy to purify under this condition. Indeed, this was the case, and I succeeded in purifying the enzyme to homogeneity and generating an effective antibody against it. However, conflicts at the university became severe in 1969, and we had to completely stop experiments for almost one year because our campus was closed with barricades. When I restarted experiments, I found that an essentially similar study had been reported in Journal of Biological Chemistry. In spite of these setbacks, I continued working toward gaining a Ph.D. degree with this work (Nakanishi and Numa, 1970). Because most of the data from my experiments were already reported in the published paper, it was very tough for me, and I learned that I would never do overlapping works in the future.

The cessation of experimental work during the University’s closure was a big frustration, but this also gave me an unexpected opportunity to seriously consider what direction I should take in the future on the basis of my 2 years of research experience. I realized that I liked biochemical approaches but also that the biochemical approaches, particularly enzymology, had come to a very mature stage and could rarely discover new principles about biological mechanisms. The big and unexplored field of bioscience was how genetic information is encoded by genomes and how this information is expressed and regulated in the biological system. I thought that this was now the direction of my research career. However, there was no way to approach this direction in mammals of my interest. In contrast, some specific genes in E. coli were enriched by the transducing mechanisms of λ phage and investigation of their expression and regulation was extensively conducted in combination with biochemical techniques. This strategy, called “genetic biochemistry,” highly attracted me although this research direction, at the time, was not directly related to the mammalian genomes of my interest. Among several laboratories working on genetic biochemistry, I was particularly impressed with the study of Ira Pastan at the Laboratory of Molecular Biology, National Cancer Institute (NCI), National Institutes of Health (NIH). His group worked on gene regulation of the lactose operon in E. coli using a λ transduced lactose operon, and they reported a number of important findings concerning the mechanisms of the cyclic adenosine monophosphate (cAMP)-mediated induction of the lactose operon expression and its relation to catabolite repression. Although I had no personal connection with Ira Pastan, I wrote a letter to him to express my wish to work in his laboratory as a postdoctoral fellow. Because of a recommendation letter by Hayaishi and Numa, and a kind contact by Hayaishi’s NIH friend, Ira accepted me as the first Japanese postdoctoral fellow in his laboratory.

NIH

I started my research at NIH from 1971 immediately after the graduate course of Kyoto University. Because I had no experience in dealing with deoxyribonucleic acid (DNA) and because many accumulated studies were reported for both λ phage and E. coli genomes, I had to struggle to understand the background of this research field. Two leading geneticists, Max Gottesman and Sankar Adhya, in the same laboratory were very helpful and let me effectively work on the E. coli galactose operon with an in vitro transcription system. Using hundreds of mutant genes isolated by Max and Sankar, I purified galactose repressor and investigated the regulatory mechanisms of the operator and promoter of the galactose operon gene. This collaboration was fruitful, and I was able to publish several papers as first author together with Sankar, Max, and Ira in that order (Nakanishi et al., 1972). Through this, I recognized again how important and effective the use of a specifically enriched gene is to analyze gene function. I also kept my great interest in the study of mammalian genes and intently attended NIH seminars whenever topics on mammalian genes were presented.

In those days, Paul Berg and his colleagues reported the establishment of recombinant DNA technology by incorporating the SV40 genes into the λ phage (Jackson et al., 1972). From my ongoing study, I immediately realized that this was the best strategy to enrich and amplify a specific mammalian gene and would lead to a revolution of mammalian molecular biology. I therefore decided to use this technology in the near future and prepared to move to Yale University after my 3-year postdoc at NIH. At Yale University, I planned to work on how the mature SV40 messenger ribonucleic acid (mRNA) was generated from the apparently large heterogenous nuclear ribonucleic acid (RNA) reported from several laboratories. However, when I was ready to get a permanent visa for the United States to work at Yale University, I received a call from Shosaku Numa who offered me a position as associate professor in Kyoto University. I thus finally decided to return to Japan and to work at Kyoto University in 1974.

POMC and Enkephalin Precursors

In the middle of the 1970s, molecular biology of the mammalian system in Japan was far behind that of the United States and Europe. We therefore needed to prepare every material and technique necessary for molecular biology with our own hands. I decided to change the subject of my study from the very competitive field of the SV40 virus to the not-yet well-characterized field of the mammalian system. During my stay at NIH, I intently attended seminars related to mammalian molecular biology and learned that many leading laboratories had been energetically working on the possibility of using insulin and growth hormone for therapeutic purposes. In contrast, only a minor population of molecular biologists was interested in and working on other endocrine systems. I thought that the endocrine system was an attractive target for molecular biological techniques in mammals for several reasons. First, a high amount of mRNA for a peptide hormone is synthesized in a specific endocrine tissue. Thus there is an easy route to characterizing a peptide hormone mRNA. Second, the regulation of peptide hormone production had been extensively studied with respect to regulatory extracellular signaling factors such as steroid hormones, peptide-releasing factors, and so on. Third, and most interestingly, accumulated but indirect evidence indicated that a small peptide hormone is initially synthesized as a large precursor in vivo, which is in turn specifically cleaved to produce a biologically active hormone. Accordingly, I believed that investigating peptide hormone biosynthesis would be fruitful as a target of mammalian molecular biology and a good project for applying recombinant DNA technology in the near future.

Shosaku Numa agreed with my proposal, and I initiated a molecular study of adrenocorticotropic hormone (ACTH) using the in vitro translation system. ACTH is a 39 amino-acid peptide and was assumed to be derived from a large precursor. My rationale for using the in vitro translation system was that this system is devoid of any cleavage enzymes responsible for the generation of a biologically active ACTH in vivo and could thus allow us to identify an ACTH precursor molecule synthesized from the pituitary mRNA as a template. However, none of the biochemists or molecular biologists in Japan used the in vitro translation system at that time. I thus had to establish every step of in vitro translation from the initial stages, including searching for a source of wheat germ, preparation of wheat germ extracts and oligo-dT cellulose and all the other tools necessary for in vitro protein synthesis. Hiroo Imura at Kobe University had effective antibodies against several different parts of the ACTH sequence. We started collaborative work with Imura and spent 1½ years establishing all necessary procedures for in vitro translation of an ACTH precursor. We finally succeeded in proving that an ACTH precursor is about 7 times larger than the natural ACTH peptide in 1976 (Nakanishi et al., 1976).

In 1997, Mains and Eipper reported an excellent study, indicating that ACTH and an endogenous opioid peptide β-endorphin are derived from a common precursor (Mains et al., 1977). However, neither the structural organization of ACTH/β-endorphin nor more than half of this precursor sequence was clarified yet. The obvious question was what structure is present in the precursor molecule other than ACTH and β-endorphin. The best way to answer this question was to conduct molecular cloning of the ACTH complementary deoxyribonucleic acid (cDNA), followed by its sequence determination. In those days, purification of a target mRNA to homogeneity was a prerequisite for cloning of the corresponding cDNA. ACTH was generally believed to be synthesized in the anterior lobe of the pituitary. However, when a Ph.D. student, Shunzo Taii, quantified ACTH mRNA levels in the anterior, intermediate, and posterior lobes of the pituitary, he found the surprising result that the ACTH mRNA represents about 30% of the intermediate lobe mRNA. Three Ph.D. students, Taii, Toru Kita, and Akira Inoue, tried to purify the ACTH mRNA by isolating about 40 pituitaries from a slaughterhouse every day and finally achieved purification of the ACTH mRNA to homogeneity. The 1970s was a period for developing recombinant DNA technology, and none of the Japanese scientists was engaged in recombinant DNA research on mammals. Our friend, Robert Schimke at Stanford University, was invited to the annual meeting of the Japanese Biochemical Society in 1977. He told us to be ready to clone an ovalubmin cDNA and was kindly willing to help me with molecular cloning of the ACTH cDNA.

On February in 1978, I brought 1µg of a homogenous ACTH mRNA to Stanford University and started collaborative work with Schimke and Stanley Cohen. However, I found that the trial of molecular cloning by Schimke’s group was not going well. I thus had to check every process of molecular cloning, one-by-one, with my own hands, such as the optimal conditions for reverse transcription, double-stranded cDNA synthesis and insertion of a cDNA mixture into a vector DNA, selection of an appropriate cloning vector, optimal hybridization conditions, and so on. Although this was a tough time, Jack Nunberg in Schimke’s laboratory and Annie Chang in Cohen’s laboratory were very helpful and collaborative and gave me much valuable advice. Furthermore, I received very useful information about many unpublished protocols for molecular cloning during my stay at Stanford University. I am confident that, had I not worked at Stanford, I would not have succeeded in cloning the ACTH cDNA. I worked very hard, day and night, for 4 months and finally succeeded in isolating more than 10 clones constituting the ACTH cDNA. I am sure that this 4-month period is the time in which I most intensely concentrated on research work during my entire research life.

Stanley recommended extending my stay at Stanford to determine the sequence of the cloned ACTH cDNA. However, I was so tired by these 4 months of hard work that I returned to Japan, and this time I brought back cloned ACTH cDNAs with me. DNA sequencing was just at the beginning, but, fortunately, Mitsuru Takanami and his group at the Institute for Chemical Research at Kyoto University had established DNA sequencing techniques in Japan. Under the guidance of Takanami’s group, we determined the sequence of the ACTH cDNA and deduced the whole amino acid sequence of the ACTH precursor (Nakanishi et al., 1979). The deduced amino acid sequence revealed that the ACTH sequence is followed by the β-lipotropin sequence that contains β-melanocyte-stimulating hormone (β-MSH) and β-endorphin. The biologically active peptides are all flanked by paired basic amino acids in which proteolytic processing takes place. The most exciting finding was the presence of an additional new MSH sequence at the amino-terminal portion of the precursor. We termed this sequence “γ-MSH.” This precursor consists of the repetitive MSH core sequences followed by the β-endorphin sequence. Our study not only proved that recombinant DNA technology is very powerful for elucidating peptide precursors but also provided the first evidence that the peptide precursor possesses a characteristic structure consisting of repetitive core peptide sequences. In vitro cDNA synthesis or cDNA cloning may cause possible sequence errors of the cloned cDNA. (In most cases, however, the reported errors turned out to be errors in DNA sequencing rather than in cDNA cloning.) Some endocrinologists called the predicted sequence “Nakanishi’s structure” rather than the sequence of the ACTH precursor. The correctness of the ACTH precursor sequence was confirmed by a partial sequence determination of the precursor protein as well as through determination of the ACTH precursor in other mammalian species and its genomic sequence (Nakanishi et al., 1980). We simply named this precursor ACTH-β-lipotropin precursor, but it is now designated with a more attractive name, proopiomelanocortin (POMC).

The next question we were interested in was whether a polypeptide structure is common in precursor molecules for other biologically active peptides. Because endogenous Leu-enkephalin and several extending peptides containing either Met-enkephalin or Leu-enkephalin were not contained in the POMC sequence, the existence of additional enkephalin precursors was predicted. However, endogenous enkephalins are widely distributed in various brain regions and some peripheral tissues. It was thus impossible to purify the enkephalin mRNA from a particular tissue or brain region. We therefore attempted to develop a different approach to clone the enkephalin precursors.

According to mRNA–cDNA hybridization analysis, the total number of mRNA copies present in a particular tissue was calculated to be around 5 × 105 copies. It was therefore expected that at least several cDNA clones of interest exist in a cDNA library consisting of randomly synthesized 5 × 105 cDNA clonal mixture. The question was then how to identify a cDNA clone of interest from such a cDNA library. A Ph.D. student, Masaharu Noda, found an interesting report of a model experiment of the globin cDNA by Itakura’s group (Wallace et al., 1981). They reported that an oligonucleotide sequence of about 20 nucleotide residues complementary to an mRNA sequence effectively and specifically hybridized with its coding cDNA sequence. At the meeting, I met Tadaaki Hirose who was a main contributor in chemical synthesis of oligonucleotides at Itakura’s laboratory and who had just returned to Keio University. We decided to start collaborative work on molecular screening with the use of synthetic oligonucleotide probes.

Another important issue for screening a cDNA library arose. Because the location of a peptide sequence in a precursor molecule is not known, it is desirable to construct a cDNA library containing so far as possible a fulllength cDNA mixture. When I stayed at Stanford University, Hiroto Okayama, a former Ph.D. student of Hayaishi’s laboratory, worked in Paul Berg’s laboratory and aimed at designing a plasmid vector that contained a full-length cDNA. He finally developed such a vector, the so-called Okayama-Berg vector (Okayama and Berg, 1982) and kindly let me know his unpublished protocol when he visited Japan. Masaharu Noda and Hitoshi Kakidani constructed cDNA libraries and attempted to isolate cDNA clones for enkephalin precursors by hybridization with a mixture of synthetic oligonucleotides deduced from the amino acid sequences of the extending enkephalin sequences. Using this cloning strategy, we succeeded in cloning preproenkephalin and preprodynorphin (Kakidani et al., 1982; Noda et al., 1982). Preproenkephalin contains six copies of Met-enkephalin and one copy of Leu-enkephalin, whereas preprodynorphin contains three copies of Leu-enkephalin. The two enkephalin precursors and POMC all contain a cysteine-rich region preceding the peptide core sequences and followed by a signal peptide. These studies revealed the roots of all endogenous enkephalin peptides and led to the important realization that peptides acting in coordination are derived from common precursors by a specific proteolytic cleavage.

Vasoactive Peptides and Neuropeptides

Numa and I discussed almost everyday how to proceed on our projects and enjoyed the progress of our projects in the new field of the neuroendocrine system. Based on my achievements in these works, I was promoted to professor at a new laboratory of the same university in 1981. In those days, we had to leave the ongoing subject to the former laboratory and had to start a new project. Also, we could not expect any financial support from the University to open a new laboratory and had to struggle in getting research grants from the government and private foundations. In those days, there was no postdoctoral fellowship system in Japan. Hence we had to solicit undergraduate students to work together and to train them from the beginning of bench work. At the new laboratory, I therefore decided to extend my peptide project on a different biological system.

The renin-angiotensin system and possibly the kallikrein-kinin system are involved in the regulation of blood pressure (see Nakanishi et al., 1985). In the former system, the vasoconstrictive angiotensin II is generated from angiotensinogen followed by enzymic processing with angiotensin-converting enzyme. The vasodilative bradykinin is also initially synthesized as kininogen and liberated by kallikrein. Because kinase II, which degrades bradykinin, is the same enzyme as angiotensin-converting enzyme, the kallikrein-kinin system was also implicated in blood pressure regulation. However, because in most patients with essential hypertension, renin, the rate-limiting enzyme, is not high in blood plasma, little attention was paid to the influence of the renin-angiotensin system on blood pressure regulation and the pathogenesis of essential hypertension. Despite this fact, many references I read indicated that angiotensin-converting enzyme inhibitors effectively lowered hypertension in humans and could possibly be widely used as drugs for treating hypertensive patients (Ondetti and Cushman, 1982). However, the renin-angiotensin system was poorly understood at the molecular level.

Kininogen also had an interesting molecular aspect in terms of the generation of this precursor molecule. There are two kininogens, termed “highmolecular-weight” (HMW) and “low-molecular-weight” (LMW) kininogen, in which not only is the bradykinin moiety and its following 12-amino acid sequence identical, there is also complete divergence between the two kininogens in their downstream sequences. This structural relationship of the two kininogens strongly suggested involvement of alternative splicing mechanisms as revealed in SV40 and some mammalian mRNAs a few years ago. New staff researchers in my laboratory, Hiroaki Ohkubo and Naomi Kitamura, started and succeeded in molecular cloning of angiotensinogen and two kininogens by screening cDNA libraries in combination with hybridization with synthetic oligonucleotide probes. Angiotensin is located at the aminoterminus of angiotensinogen, followed by a large carboxyl-terminal sequence (Ohkubo et al., 1983). The two kininogens are identical throughout their large amino-terminal portions up to 12 amino acid residues distal to the bradykinin moiety, and they then diverge at their carboxyl-terminal sequences (Kitamura et al., 1983). In fact, genomic cloning indicated that the two kininogens are encoded by a single gene and generated by alternative RNA splicing in combination with different polyadenylation events. The large carboxyl-terminal domain of angiotensinogen and the common amino-terminal domain of kininogens both share this sequence similarity with proteinase inhibitors (Tanaka et al., 1984). In fact, kininogen turned out to be the same as the cysteine proteinase inhibitor. The angiotensinogen and kininogens possess no repetitive peptide core sequence and thus seem to evolve in a different manner from the polypeptide precursors. Rather, the multifunctional domains characteristic of these precursors implicated evolutionary significance in the process of blood pressure regulation and inflammatory reactions.

We also started one more project concerning the precursor of the neuropeptide substance P. Substance P is one of the best-characterized neuropeptides and acts as a pain-generating peptide in the sensory nervous system (see Nakanishi, 1986). This peptide belongs to the tachykinin peptide family but was thought to be the only tachykinin peptide in mammals. However, some nonmammalian tachykinins such as amphibian kassinin were reported to be pharmacologically more potent than substance P in some mammalian assays (Erspamer, 1981). I considered the possibility that one or more additional mammalian tachykinins, like opioid precursors, may exist in the substance P precursor. Using the same cloning strategy described above, a Ph.D. student, Hiroyuki Nawa, identified two types of cDNA clones encoding the substance P precursor (termed “preprotachykinin-A,” PPT-A) (Nawa et al.,1983). One (α-PPT-A) contains a single substance P sequence in the precursor, whereas the other (β-PPT-A) possesses an additional tachykinin sequence. This sequence is strikingly similar to that of kassinin and was thus termed “substance K.” Its genomic sequence and S1-nuclease mapping analysis indicated that substance K is precisely specified by one of the exons of the PPT-A gene (Nawa et al., 1984b). More interestingly, the expression of α and β-PPT-A mRNAs is regulated in a tissue-specific manner by including or excluding a substance K–coding sequence by alternative RNA splicing events. The PPT-A gene provided the first example in which alternative RNA splicing is independent of different promoters or polyadenylation and is directly involved in determining the production of a specific peptide. Substance K (also termed “neurokinin A” or “neuromedin L”) and a third mammalian tachykinin, neuromedin K/neurokinin B, were independently identified as naturally occurring tachykinin peptides from mammalian tissues. We also cloned the neuromedin K precursor (preprotachykinin-B, PPT-B) and indicated that three mammalian tachykinins are derived from the two genes (Kotani et al., 1986).

About one year before our publication of alternative splicing mechanisms of kininogens and PPT-A, Susan Amara, Ron Evans, and Michael Rosenfeld reported that a novel calcitonin-gene-related peptide (CGRP) is contained in the calcitonin precursor and its expression is regulated by tissuespecific alternative splicing in combination with different polyadenylation (Amara et al., 1982). Furthermore, a number of leading laboratories reported on their extensive studies of alternative splicing and polyadenylation mechanisms. The study of renin-angiotensin and kallikrein-kinin systems in blood pressure regulation and hypertension was also very interesting and important. We actually showed that transgenic mice carrying the renin and angiotensinogen transgenes became hypertensive and that the angiotensinogen mRNA was markedly upregulated by inflammatory reaction. However, knockout techniques were not yet available and if I were to pursue this project, I would need to shift from molecular studies to more pharmacological and physiological studies. I felt that this was not my field, and I was therefore perplexed about what direction to take next in our research.

Peptide Receptors

When we identified substance K as a new mammalian tachykinin, we chemically synthesized substance K and subjected it to parallel pharmacological analyses with substance P. This study clearly indicated that the two peptides possess common pharmacological activities but markedly differ in their potencies and kinetics (Nawa et al., 1984a). This finding strongly suggested the existence of different tachykinin receptors. The substance P receptor is coupled to intracellular G proteins, but the molecular entity of G proteincoupled receptors (GPCRs) per se remained to be clarified in those days. Membrane receptors and ion channels are composed of hydrophobic amino acid clusters embedded in plasma membranes and hydrophilic amino acid clusters exposed to the extracellular and intracellular milieus. Furthermore, membrane proteins generally represent a minor population of the cellular components. These features of membrane receptors and ion channels hamper protein purification by biochemical approaches. However, when chemical properties of membrane proteins are regarded at the mRNA level, there is no difference in the chemical constituents between soluble proteins and membrane proteins. Therefore, if we can make up a good strategy for identifying cDNA clones for a receptor or an ion channel, we would be able to isolate such clones from a cDNA library.

In 1984, I had two staff researchers and about 10 graduate students. And as a result of the above achievements, I was able to obtain government funding to maintain my laboratory. I therefore decided to move on to a more challenging project by developing a new tool. Eric Barnard and his colleagues had reported that when tissue mRNA such as brain mRNA is injected into Xenopus laevis oocytes, the functional receptor or ion channel is expressed in the oocyte plasma membrane (Barnard et al., 1982). Consequently, the voltage-gated ion channels and ligand-gated ion channels are characterized by the recording of an electrophysiological response of Xenopus oocytes after changing membrane potentials and after applying an appropriate receptorspecific ligand, respectively. Furthermore, when a GPCR is coupled to intracellular Ca²⁺ signaling, the activation of this receptor increases intracellular Ca²⁺, which in turn stimulates Ca²⁺-dependent Cl⁻ channels in Xenopus oocytes. Therefore, the expression of such GPCR is characterized by an electrophysiological recording of oocyte Cl⁻ currents after ligand application. Because the tachykinin receptors are coupled to intracellular Ca²⁺ signaling, we extended Barnard’s finding to develop a new functional cloning strategy for tachykinin receptors.

Our cloning strategy was as follows (Masu et al., 1987). We first synthesized a cDNA mixture from the brain mRNA. We then constructed a cDNA library by inserting the cDNA mixture immediately downstream into an appropriate promoter in the vector DNA. We then extracted a clonal cDNA mixture from the cDNA library and subjected it to in vitro transcription by a specific RNA polymerase. Then the mRNA synthesized in vitro was injected into Xenopus oocytes, which were then tested for expression of a receptor or ion channel by electrophysiological recording after ligand application or membrane polarization. When a positive response was observed, we serially fractionated the cDNA library until a single functional cDNA clone could be identified. This strategy does not require any protein purification and is a straightforward way to circumvent many of the problems involved in the cloning of membrane receptors and ion channels.

Because our group had no experience with electrophysiological research, I shared my ideas with Motoy Kuno of the Department of Physiology and asked for his assistance and collaboration in experiments, as well as for the training of our graduate students. This collaboration was not only very fruitful but also enjoyable because I learned some of the logic and thinking patterns of electrophysiologists, which are sometimes different from those of our molecular biologists. Two Ph.D. students, Kazuhisa Nakayama and Yasuo Masu, started experiments but encountered several unexpected problems. These included the difficulty of synthesizing in vitro a full-length cDNA mixture covering the functional protein sequences, construction of an appropriate vector that allowed the incorporation of a full-length cDNA mixture, and the variability of electrophysiological responses of individual oocytes. To solve these problems, it took a longer time than I predicted, but they finally established this technique and reported the molecular cloning of a functional substance K receptor cDNA (Masu et al., 1987). This cloning was the first cloning of peptide receptors and provided compelling evidence that the peptide receptor belongs to the family of GPCRs. Independently, David Julius and Richard Axel reported the same cloning technique for the serotonin receptor in 1988 (Julius et al., 1988). Before publication of our work, however, Lefkowitz’s group and Numa’s group had reported their success in molecular cloning of the adrenergic receptor and the muscarinic receptor on the basis of protein purification of these receptors (Dixon et al., 1986; Kubo et al., 1986).

As we intended, our cloning strategy became a widely applicable strategy for molecular cloning of membrane receptors and ion channels. This methodology was used for cloning of the endothelin receptor and the neurotensin receptor in our laboratory (Arai et al., 1990; Tanaka et al., 1990) and the PAF receptor, the histamine receptor, and the bradykinin receptor in other laboratories. Because our cloning strategy was applicable for ion channels by membrane polarization, we examined such electrophysiological responses in oocytes injected with several tissue mRNAs. A Ph.D. student, Toru Takumi, found that a kidney mRNA induced very potent voltagedependent currents in its expression in Xenopus oocytes (Takumi et al., 1988). Because the size of this mRNA was unusually smaller than those of conventional voltage-dependent ion channels, we cloned and determined the sequence of the corresponding functional cDNA. The cloned cDNA encodes a novel small protein with a single transmembrane domain but induces selective permeation of K+ by membrane depolarization. Because the structure of this protein is peculiar, it remained elusive whether it acts as a discrete K+ channel per se or modulates the channel activity of endogenous oocyte K+ channels. Later, this protein turned out to be a potently activating accessory subunit of K+ channels and its mutations cause arrhythmia in humans (Abbott and Goldstein, 1998).

A Ph.D. student, Fumihiro Yokota, elucidated the molecular entity of the substance P receptor by cross-hybridization in combination with the Xenopus oocyte expression system (Yokota et al., 1989). Another Ph.D. student, Ryuichi Shigemoto at the laboratory of Noboru Mizuno in the Department of Morphological Brain Science, came to my laboratory to learn molecular biology and cloned neuromedin K receptor (Shigemoto et al., 1990). He is a very talented scientist, and we enjoyed working on many collaborative projects after he returned to his own laboratory. On the basis of molecular cloning of the three tachykinin receptors, we demonstrated the agonist and antagonist selectivities, and the intracellular signaling mechanisms of the three tachykinin receptors by use of heterologously expressing cells. We also indicated the distribution of individual tachykinin receptor mRNAs in various brain regions and peripheral tissues as well as the interesting negative regulation of the substance P receptor by steroid hormones. Our studies thus led to a comprehensive demonstration of the mammalian system from its biosynthesis to receptor interaction and intracellular signaling mechanisms (Nakanishi, 1991).

Yokota investigated the ligand binding mechanism of tachykinin receptors by expressing a series of chimeric receptors between substance P and substance K receptors in heterologously transfected cells. This analysis showed that the extracellular domain and the transmembrane regions are involved in selective peptide binding of the tachykinin receptors (Yokota et al., 1992). However, Lefkowitz’s group characterized the detailed ligand binding mechanisms of the adrenergic receptor by analyzing binding of a small-molecule ligand to this receptor. In contrast, the peptide binding of the tachykinin receptor was too complicated to be solved at the molecular level. We also hoped to examine mechanisms underlying the different response profiles observed between substance P and substance K receptors by detailed analysis in heterologously transfected cells. However, this study failed to reproduce such differences in the heterologous expression system. This finding suggested that the different response patterns of the two receptors result from endogenous intracellular signaling mechanisms following receptor activation. More important, the tachykinin system lacks explicit evidence indicating the physiological and pathophysiological role of tachykinin peptides and their receptors in the biological system. My standpoint toward molecular biology is that molecular biology is very powerful for logically exploring mechanisms of the biological system but is not so effective for unravelling a novel physiological or pathophysiological role of the biological system. I therefore gradually moved toward investigating a more attractive system for our molecular research approach.

Cloning of Glutamate Receptors

Glutamate is the main excitatory neurotransmitter in the nervous system. Numerous lines of evidence demonstrated that glutamatergic transmission plays an essential role in memory and learning, neural development, and neuronal cell degeneration (see Nakanishi, 1992; Nakanishi and Masu, 1994). Exploring regulatory and integrative mechanisms of glutamatergic transmission was thus not only one of the central subjects of neuroscience but also an intriguing target of application for our functional cloning strategy. Our colleagues wished to extend the project to molecular elucidation of glutamate receptors and to uncover regulatory and integrative synaptic mechanisms underlying glutamate-mediated brain functions at the molecular level.

Previous electrophysiological and pharmacological studies categorized glutamate receptors into two groups, termed “ionotropic receptors” and “metabotropic receptors” (mGluRs) (see Nakanishi, 1992). Ionotropic receptors are glutamate-gated cation channels and are subdivided into α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)/kainate receptors and N-methyl-D-aspartate (NMDA) receptors. AMPA receptors are responsible for the rapid excitation of neuronal cells, whereas NMDA receptors are important for neural plasticity and neural development as well as neurotoxicity. mGluRs are GPCRs and are involved in the modulation of glutamatergic transmission. In 1989, Stephan Heinemann and his colleagues reported the molecular cloning of an AMPA receptor using the functional oocyte cloning strategy (Hollmann et al., 1989). Since then, AMPA/kainate receptors have been shown to comprise diverse members of the receptor family.

A Ph.D. student, Masayuki Masu, initiated an attempt to clone mGluR as an extension of the GPCR family. This cloning took a longer time than predicted because the mGluR mRNA encoded an unusually large extracellular domain and was unexpectedly large as compared with mRNAs for other conventional GPCRs. In 1991, he finally succeeded in cloning mGluR1, which was coupled to the IP₃/Ca²⁺ signaling cascade (Masu et al., 1991).

The NMDA receptor is not only essential for memory, learning, and neurotoxicity but also is distinguished from AMPA/kainate receptors by its unique properties, including high Ca²⁺ permeability, a voltage-dependent channel block by Mg2+ and the action of a number of selective agonists and antagonists (see Nakanishi, 1992). A number of laboratories attempted but failed to identify NMDA receptors through molecular cloning with the use of conventional protein purification or with the oocyte expression system. Koki Moriyoshi was trained in recombinant DNA techniques during his medical course at my laboratory and came to my laboratory as a Ph.D. student in 1991.

I thought that there were two possible explanations for the difficulty of cloning the NMDA receptor by the oocyte expression system. One was that the NMDA receptor mRNA represents a minor population of the brain mRNA. If that were the case, we needed to increase the number of cDNA clones of the cDNA library to identify a rare NMDA receptor cDNA clone. The other possible explanation was that the current activity of a single functional NMDA receptor subunit may be too low in oocytes to identify its clone in the large population of a cDNA library. If this were the case, it would be better to decrease the number of cDNA clones from a cDNA library. I recommended that Moriyoshi reduced the number of the clonal mixture from the standard 500,000 clones to 1000 clones of a brain cDNA library. This was the case for the situation of the NMDA receptor and allowed him to isolate a number of functional receptor cDNA clones less than 3 months after the start of this project (Moriyoshi et al., 1991). The cloned functional subunit shares a common structural characteristic with ionotropic receptors and shows all the physiological and pharmacological properties reported for the NMDA receptor. We submitted this study to Nature by summarizing the sequence and electrophysiological and pharmacological properties of the cloned MNDA receptor subunit (NR1) and its wide distribution in various brain regions. Two weeks later, we received a galley proof of our manuscript by fax. This was our first and only experience thus far to correct a faxed proof of a Nature paper.

The NMDA currents of the cloned NR1 receptor subunit were much smaller than the ones that were induced with the whole brain mRNA in Xenopus oocytes. This finding strongly indicated that additional subunits of the NMDA receptors existed and that the full activity of the NMDA receptors would be expressed by a heteromeric assembly. The groups of Masayoshi Mishina and Peter Seeburg as well as a Ph.D. student, Takahiro Ishii, in my laboratory demonstrated the presence of four additional NMDA receptor subunits (NR2A-NR2D) by PCR and cross-hybridization techniques (see Ishii et al., 1993). The individual NR2 subunits, in contrast to NR1, evoked no electrophysiological response after the agonist application. However, combined expression of NR1 with the NR2 subunits markedly potentiated responses to NMDA or glutamate. Thus, NR1 serves as a fundamental subunit necessary for the NMDA receptor-channel complex, and it forms a heteromeric assembly with different kinds of NR2 subunits. The combination of NR1 with different subunits shows functional variability in electrophysiological and pharmacological properties. The affinity for agonists, the effectiveness of antagonists, the kinetics of responses, the sensitivity to Mg2+ block, and the stimulatory effect of glycine are all different, depending on the subunit composition.

Upon mutational analysis of the AMPA receptor, it was shown that substitution of glutamine for asparagine at the channel pore segment allowed the AMPA receptor to highly permeate Ca²⁺. Because asparagine is present in the corresponding pore segment of the cloned NR1 subunit, we proposed that this asparagine is a key residue for allowing the high Ca²⁺ permeability of the NMDA receptor. A fellow from the Kyowa Hakko Kogyo Company, Kazuhiro Sakurada, as well as Mishina’s group and Seeburg’s group showed that asparagine is essential for Ca²⁺ permeability and inhibition by Mg++, Zn++, and an NMDA receptor antagonist, MK801 (see Sakurada et al., 1993).

The NR1 mRNA is expressed ubiquitously in almost all neuronal cells throughout the brain. In contrast, the mRNAs for different NR2 subunits show overlapping but different expression patterns in the brain. Thus, the anatomical and functional differences among the NR2 subunits provide the molecular basis for the generation of heterogeneity in the physiological and pharmacological properties of the NMDA receptors in different neuronal cells and brain regions (Nakanishi, 1992).

Several Ph.D. students, Yasuto Tanabe, Takaaki Abe, and Naoyuki Okamoto, expanded cloning of the mGluR family by cross-hybridization and PCR techniques. They revealed the existence of seven different subtypes (mGluR1 through mGluR7) (Abe et al., 1992; Nakanishi, 1994; Okamoto et al., 1994; Tanabe et al., 1992), whereas Duvoisin reported one more subtype (mGluR8) of the mGluR family (Duvoisin et al., 1995). A fellow from the Eizai Pharmaceutical Company, Ichiro Aramori, and a Ph.D. student, Yasunori Hayashi, participated in investigating the properties of individual mGluRs by means of DNA transfection and stable expression in Chinese hamster ovary cells (Aramori and Nakanishi, 1992; Hayashi et al., 1993). Eight different mGluR subtypes were classified into three groups according to their sequence similarity, agonist and antagonist selectivity, and intracellular signaling mechanisms. Group 1 mGluRs (mGluR1 and mGluR5) react most potently with quisqualate and stimulate IP₃ formation and intracellular Ca²⁺ mobilization. The other six mGluR subtypes inhibit the forskolinstimulated accumulation of intracellular cAMP, but group 2 mGluRs (mGluR2 and mGluR3) and group 3 mGluRs (mGluR4, mGluR6-mGluR8) are different in their agonist and antagonist specificity. Interestingly, glutamate was believed to be an excitatory neurotransmitter. However, the linkage of group 2 and group 3 mGluRs to the inhibitory cAMP cascade suggested suppression rather than excitation of neurotransmission, because in many cases the receptors linked to the cAMP inhibition are involved in suppression of neurotransmission. Later on we pursued the physiological role and detailed mechanisms of mGluR-mediated synaptic modulation in some neural networks.

In situ hybridization and immunohistochemistry revealed that different mGluR subtypes show overlapping but different distribution patterns in the brain. All but mGluR6 of group 3 mGluRs are widely localized at the presynaptic sites of many neuronal cells, again indicating that these subtypes serve as inhibitory autoreceptors at the presynaptic sites. In contrast, mGluR1 and mGluR2 are more restrictedly distributed in specific neuronal cells, and the functions of these subtypes were investigated in detail as described later.

Glutamatergic Transmission in the Retina

Thanks to the molecular cloning of diverse types of ionotropic receptors, many laboratories were engaged in precise characterization of the properties and regulatory mechanisms of these receptors at the molecular level. In contrast, the physiological and functional role of mGluRs in brain function largely remained to be investigated. The receptors of the GPCR family are usually involved in the regulation of neurotransmission via intracellular signaling mechanisms. Furthermore, a single molecular entity of an individual mGluR would allow us to delineate its regulatory role in glutamatergic transmission more easily than would a heteromeric assembly of ionotropic receptors. We therefore focused on the role and mechanisms of mGluRs in the neural network.

At the time we reported the first cloning of mGluR, two groups, Nawy and Jahr and Schiells and Falk, reported a very interesting finding. A putative mGluR that responds to 2-amino-4-phosponobutyrate (L-AP4), a glutamate analogue, most likely mediates synaptic transmission from photoreceptors to ON bipolar cells in the retina through coupling to the inhibitory signaling cascade (Nawy and Jahr, 1990; Shiells and Falk, 1990). In the retina, glutamate is used as a common neurotransmitter from photoreceptors to ON and OFF bipolar cells, but this common transmitter induces opposite responses, namely, depolarization of OFF bipolar cells and hyperpolarization of ON bipolar cells, thus resulting in the discrimination of light and dark signals at the level of bipolar cells (see Nakanishi, 1995). The excitation of OFF bipolar cells by glutamate was easily explained by the involvement of the ionotropic receptor, but hyperpolarization of ON bipolar cells by glutamate could not simply be accounted for by the usual glutamate receptor. A Ph.D. student, Yoshiaki Nakajima, thus initiated screening of a retinal cDNA library and identified mGluR6, which in fact responded effectively to L-AP4 (Nakajima et al., 1993).

Several Ph.D. students, Akinori Nomura, Masayuki Masu, and Hideki Iwakabe, then characterized the role of mGluR6 in glutamatergic transmission from photoreceptors to ON bipolar cells by immunohistochemistry, immunoelectron microscopy, and intracellular signaling mechanisms. This study explicitly demonstrated that mGluR6 is confined to the postsynaptic site of ON bipolar cells (Nomura et al., 1994). We then took advantage of the restricted expression of mGluR6 in retinal ON bipolar cells and generated mGluR6 knock-out mice by gene targeting. This investigation provided compelling evidence that mGluR6 is essential for evoking ON responses in ON bipolar cells (Masu et al., 1995). Interestingly, the mGluR6-deficient knockout mice retained the ability to respond to visual input. Because the OFF response remained unchanged in mGluR6 knock-out mice, this finding indicated that not only an ON response but also an OFF response is essential as a signal for visual transmission. The mGluR6 deficiency, however, impaired the detection of visual contrast (Iwakabe et al., 1997). Furthermore, Dryja’s group recently reported that in human patients mGluR6 mutations induce an abnormal ON response electroretinogram and cause night blindness (Dryja et al., 2005), indicating the indispensable role played by mGluR6 as well in human visual discrimination.

These studies explored the mechanisms underlying light and dark discrimination at the level of bipolar cells (Nakanishi, 1995). When exposed to light, photoreceptor cells hyperpolarize, and the AMPA receptor and mGluR6 remain inactive. The inactive AMPA receptor shuts off the OFF pathway. Conversely, the inactive mGluR6 is uncoupled to the inhibitory intracellular signaling and keeps cation channels active, thus resulting in the excitation of ON bipolar cells. In contrast, when the light is shut off, glutamate activates the AMPA receptor and mGluR6, and the activated mGluR6 stimulates the inhibitory signal cascade and in turn shuts off the ON pathway. Therefore, the two types of glutamate receptors, namely mGluR6 in ON bipolar cells and the AMPA receptor in OFF bipolar cells, are effectively used for discrimination of light and dark signals at the level of bipolar cells.

Accessory Olfactory Bulb Neurotransmission

The distinctive roles of the two types of glutamate receptors seemed to be rather unusual because they are often expressed in the same neurons. We therefore investigated the cooperative function of ionotropic and metabotropic receptors in several networks. Abundant mGluR2, as analyzed by in situ hybridization and immunoelectron microscopy, is located at the dendrites of granule cells in the accessory olfactory bulb (Hayashi et al., 1993). Consequently, the AMPA receptor and mGluR2 are located at the postsynaptic site of granule cells. In the accessory olfactory bulb, mitral cells are excited by input from the vomeronasal nerve, that is, pheromonal receptor neurons. Mitral cells are known to form typical dendrodendritic synapses with inhibitory granule cells, and these synapses undergo reciprocal regulation, namely excitation of granule cells by glutamate from the mitral cell and inhibition of mitral cells by γ-aminobutyric acid (GABA) from the granule cell. The question, however, then arose as to how the odorant stimulus is transmitted to the central olfactory pathway when the granule cell-mediated GABAergic inhibition is working on mitral cells (see Nakanishi, 1995).

The development of selective and potent agonists for mGluR subtypes is indispensable for mGluR research. Ohfune and coworkers in Suntory Institute for Bioorganic Research chemically synthesized eight isomers of the conformationally restricted glutamate analogue, 2-(carboxycyclo-propyl) glycine (CCG) (see Shinozaki et al., 1989). Shinozaki and Ohfune reported that two of the L-isomers of CCGs, L-CCG-I and L-CCG-II, potently activate the IP3coupled mGluR. A Ph.D. student, Yasunori Hayashi, in collaboration with Ohfune, investigated the agonist potencies and selectivity of eight CCG isomers by examining their effects on the signal transduction of the representative mGluR subtypes and identified L-CCG-1 as a potent agonist for group2 mGluRs. He further revealed that DCG-IV, which was initially abandoned as a weak NMDA receptor antagonist, is a more potent and selective agonist for mGluR2 and mGluR3. Thus, DCG-IV is very useful for distinguishing the functions of different subtypes of mGluRs (Hayashi et al., 1993).

Hayashi in collaboration with Tomoyuki Takahashi of the Department of Physiology examined whether the activation of mGluR2 by DCG-IV can regulate granule cell-mediated GABA transmission in the accessory olfactory bulb. In slice preparations, he made whole-cell recordings of a mitral cell after electrical stimulation of a granule cell. This analysis clearly showed that the activation of mGluR2 abolishes GABA-mediated inhibitory postsynaptic currents in mitral cells. On the basis of this and other findings, we proposed an interesting mechanism for olfactory transmission (Hayashi et al., 1993). In the accessory olfactory bulb, excitation of mitral cells releases glutamate and in turn stimulates granule cells through the AMPA receptor. This stimulation of the granule cell is thought to cause self-inhibition and lateral inhibition through the inhibitory GABA transmitter. Our observation, however, also indicated that the simultaneous activation of mGluR2 relieves GABA-mediated self-inhibition. Importantly, this inhibition is restricted to synapses with the excited mitral cell and would maintain lateral inhibition with neighboring mitral cells. This mechanism evidently enhances the signal-to-noise ratio of strong odorant stimuli from background stimuli and would contribute to the discrimination of different olfactory stimuli. Our study demonstrates the importance of the cooperative function of ionotropic and metabotropic receptors in synaptic integration.

Behaviorally, the accessory olfactory bulb is known to be important for pheromonal memory formation (Brennan et al., 1990). When a female mouse mates, she forms a memory of male pheromones during mating and maintains pregnancy during exposure to familiar pheromones. However, when the pregnant female is exposed to unfamiliar pheromones, development of embryos is prevented and pregnancy is blocked. This pheromonal memory was initially discovered by Bruce and is thus named the “Bruce effect.”

Keverne and his colleagues extensively studied the mechanisms of the Bruce effect (Brennan et al., 1990). They showed that coital stimulation persistently enhances norepinephrine in the accessory olfactory bulb and in turn reduces GABA transmission from granule cells to mitral cells. This coitus-stimulated, norepinephrine-mediated excitation of mitral cells results in the formation of a memory specific to the pheromones exposed during mating. I was deeply impressed with the review article of this mechanism written by Brennan et al. (1990). My interest was the following; because norepinephrine and DCG-IV commonly reduce GABA transmission, I wondered whether DCG-IV infusion into the accessory olfactory bulb may also create a specific pheromonal memory without mating. Kaba is a rare Japanese name. Thus, I originally thought that he was a foreign scientist, but I noticed that he was a Japanese scientist working at the Kochi Medical School. I then discussed the possibility of doing collaborative work with Hideto Kaba and immediately sent Hayashi to his laboratory. Our study demonstrated that the persistent activation of mGluR2 by DCG-IV is capable of inducing an olfactory recognition memory without mating (Kaba et al., 1994). Thus, mGluR2 in the accessory olfactory bulb plays an important role in neural plasticity responsible for olfactory memory formation.

Cerebellar Neurotransmission

The cooperative roles of the AMPA receptor and mGluR were also revealed in synaptic transmission of Golgi cells in the cerebellar network (Watanabe and Nakanishi, 2003). The principal network of the cerebellar cortex consists of mossy fibers, granule cells, parallel fibers, and Purkinje cells (see Nakanishi, 2005). In addition, Purkinje cells receive excitatory input from climbing fibers. This circuit serves as the single output system of the cerebellar cortex. Coincident excitation by parallel fibers and climbing fibers results in long-term depression (LTD) at parallel fiber-Purkinje cell synapses and attenuates the inhibitory output of Purkinje cells to deep cerebellar nuclei. Such LTD is a cellular model system that has been implicated in a portion of the engram for some forms of motor learning. Besides this main network, Golgi cells receive excitatory parallel fiber input and in turn suppress granule cell excitation through an inhibitory GABA transmitter. This feedback inhibition is thought to be essential for filtering mossy fiber input before distributing input to Purkinje cells. However, this feedback inhibition is so strong that well-defined control of this feedback inhibition is necessary. Otherwise, this strong feedback inhibition would block information transmission of mossy fiber input to Purkinje cells.

To study the mechanisms of Golgi cell synaptic modulation, we focused on mGluR2, which is abundantly distributed at the postsynaptic sites of Golgi cells. A Ph.D. student, Dai Watanabe, performed whole-cell recordings of green fluorescent protein (GFP)-positive Golgi cells after electrical stimulation of parallel fibers in cerebellar slices of wild-type and mGluR2 knockout mice. A series of electrophysiological, pharmacological and biochemical experiments indicated that mGluR2 is coupled to G protein-coupled, inwardly rectifying K+ channels (GIRK) and suppresses Golgi cell excitability through the activation of GIRK-mediated K+ permeation. Our study also revealed that when Golgi cells receive glutamatergic input from parallel fibers, the AMPA receptor first excites Golgi cells and mGluR2 then suppresses Golgi cell excitability in a stimulus strength-dependent manner. As a result, postsynaptic mGluR2 is capable of sensing the strength of presynaptic granule cell input and relieving Golgi cell-mediated feedback inhibition in a stimulus strength-dependent manner. Therefore, the cooperative function of ionotropic and metabotropic receptors plays an important role in spatiotemporal processing of incoming input in the cerebellar network (Nakanishi, 2005).

We also investigated the specialized functions and intracellular signaling mechanisms of an individual subtype of the mGluR family in some specific neuronal cells and neural networks. In collaboration with my group, Hitoshi Ohishi of the Department of Morphological Brain Science showed that mGluR2 is located not only at the postsynaptic site but also at the presynaptic site of cerebellar Golgi cells. Because Golgi cell axon terminals are not directly connected with the glutamatergic synapses of mossy fibers, we proposed that glutamate spillover released from the mossy fiber terminals could activate the presynaptic mGluR2 of Golgi cells, which in turn heterosynaptically inhibits GABA-mediated inhibition of Golgi cells onto granule cells (Ohishi et al., 1994). This inhibitory mechanism of mGluR2 was supported by electrophysiological experiments reported by Mitchell and Silver (2000). Therefore, mGluR2 plays an important role in the modulation of Golgi cell transmission presynaptically and postsynaptically.

With respect to mGluR1 in Purkinje cells, Shigemoto raised antibodies against two distinct extracellular sequences of mGluR1 expressed as bacterial fusion proteins and indicated that these antibodies inhibit the mGluR1stimulated IP₃ formation in transfected CHO cells. Shigemoto and Tomoo Hirano of the Department of Physiology then revealed that both of the mGluR1 antibodies completely block induction of LTD at the parallel fiberPurkinje cell synapses in cultured Purkinje cells (Shigemoto et al., 1994). Shigemoto further extended the physiological importance of Purkinje cell mGluR1 in collaboration with Peter Sillevis-Smith of the Department of Neuro-Oncology at the University Hospital Rotterdam. We showed that an mGluR1 autoantibody is generated in patients with Hodgkin’s disease and causes paraneoplastic cerebellar ataxia (Sillevis-Smitt et al., 2000). This antibody abrogated mGluR1-induced IP₃ formation and caused severe ataxia in mice as well after injection into the subarachinoid space. This was the first report of an autoantibody associated with a neural antigen in the central nervous system.

Because many Ca²⁺ signaling molecules are highly expressed in Purkinje cells, a Ph.D. student, Jun Kitano, investigated the functional linkage of mGluR1 with Ca²⁺ signaling molecules in Purkinje cells (Kitano et al., 2003). He showed that mGluR1 forms a protein assembly with the Cav 2.1 subunit of P-type Ca²⁺ channels and inhibits Cav 2.1-mediated increases in agonist-dependent and agonist-independent manners. Furthermore, the simultaneous activation of mGluR1 and Cav 2.1 channels enhances the Cav 2.1-mediated Ca²⁺ increase, suggesting that the physical coupling of mGluR1 with Cav 2.1 ensures efficient spatiotemporal regulation of intracellular Ca²⁺ during glutamatergic transmission in Purkinje cells.

Upon single-cell analysis of Ca²⁺ responses in heterologously transfected cells, Sigeki Kawabata and Masamichi Okada from Yamanouchi Pharmaceutical Company in collaboration with our group found a clear difference in intracellular Ca²⁺ responses between mGluR1 and mGluR5 (Kawabata et al., 1996). Glutamate induces a single-peaked nonoscillatory Ca²⁺ increase in mGluR1-expressing cells but elicits Ca²⁺ oscillations in mGluR5-expressing cells. Chimeric analysis indicated that this different pattern results from a single amino acid substitution, aspartate or threonine, located at the corresponding G protein-interacting domains of mGluR1 and mGluR5, respectively. Interestingly, this threonine of mGluR5, as analyzed by pharmacology and peptide mapping, is phosphorylated by protein kinase C (PKC). Our data suggested a novel mechanism by which phosphorylation and dephosphorylation of mGluR5 can generate Ca²⁺ oscillations, whereas the absence of the corresponding PKC phosphorylation leads to glutamateinduced non-oscillatory Ca²⁺ responses in mGluR1. A Ph.D. student, Kiyoshi Nakahara, further showed that glutamate evokes oscillatory Ca²⁺ responses via the PKC phosphorylation/dephosphorylation mechanism in cultured astrocytes expressing mGluR5 but not mGluR1 (Nakahara et al., 1997). The physiological significance of mGluR5-induced Ca²⁺ oscillations remains to be clarified. However, because the frequency of Ca²⁺ oscillations is dependent on the glutamate concentrations applied, I still believe that this frequency modulation mode of Ca²⁺ signaling would be important as a distinct intracellular signal, characteristic of mGluR5.

3D Structure of the mGluR Glutamate-Binding Domain

The eight mGluRs are considerably larger than the conventional GPCRs and show a common structural architecture with an extremely large extracellular amino-terminal domain that precedes seven transmembrane segments. This structural characteristic turned out to be common in GPCR subfamilies such as pheromone receptors, GABAB receptors and the calcium sensor. A Ph.D. student, Katsu Takahashi, performed chimeric analysis between mGluR1 and mGluR2 and provided compelling evidence that the large extracellular domain of mGluR is a site for glutamate binding (Takahashi et al., 1993).

Hisato Jingami from the Biomolecular Engineering Research Institute (BELI), my former Ph.D. student, was interested in determining the 3D structure of the extracellular glutamate-binding domain of mGluR1. In collaborative work, the Banyu Company chemically synthesized 3H-labeled quisqualate, a potent and selective agonist for mGluR1. To quantitate agonist binding to the extracellular glutamate-binding domain that is free from the transmembrane and G protein-interacting domains of mGluR1, the Banyu Company kindly gave us a 3H-labeled quisqualate. Using a 3H-labeled quisqualate-binding assay, we succeeded in purifying a soluble extracellular domain of mGluR1 to homogeneity from extracts of a buculovirus expression system.

The 3D structure of mGluR1 was then elucidated by Jingami, Kosuke Morikawa, and their colleagues in BELI with the use of X-ray crystallography (Jingami et al., 2003; Kunishima et al., 2000). The glutamate-binding domain of mGluR1 forms a dimeric structure through a packed α-helical interface between the two homomers. The glutamate-free structure consists of an open-open conformation and an open-closed conformation at the glutamate-binding site. Glutamate binding exclusively shifts this structure to an open-closed conformation, whereas a glutamate antagonist such as α-methyl-carboxyphenylglycine (MCPG) fixes this structure into an open– open conformation. The active and inactive forms of mGluR thus exist in equilibrium between these two conformations. This conformational change triggers activation of intracellular G proteins, but the activation mechanism, as is the case for other GPCRs, still remains elusive.

Immunotoxin-Mediated Cell Ablation

Using multidisciplinary approaches including electrophysiology, pharmacology, knock-out/transgenic techniques, and so on., several Ph.D. students further revealed that different glutamate receptor subunits or subtypes show specialized functions in different brain regions. These include the key role of mGluR2 in induction of LTD at the mossy fiber-pyramidal cell synapses in the hippocampal CA3 region (Yokoi et al., 1996), the necessity of the heteromeric assembly of NR2A and NR2C NMDA receptor subunits at cerebellar mossy fiber-granule cell synapses for movement coordination (Kadotani et al., 1996), and the critical role of mGluR7 in fear responses and conditioned taste aversion (Masugi et al., 1999). However, such conventional approaches alone were not sufficient for investigating synaptic mechanisms of a specific network. In particular, it is difficult to target a specific neural network by conventional approaches.

After I left NIH, Ira Pastan shifted his research interest to oncogenic mechanisms and cancer therapy from the molecular biology of E. coli gene regulation. His group nicely elaborated a new immunotherapy technique termed “immunotoxin-mediated cell targeting” (IMCT). This technology was developed to treat human adult T cell leukemia, which expresses a high amount of interleukin-2 (IL-2) receptor. In this technique, the recombinant immunotoxin composed of human IL-2 receptor α-subunit monoclonal antibody fused to Pseudomonas extoxin is generated and injected to selectively kill T cell leukemia. Ira often visited Kyoto to enjoy the atmosphere of old temples and gardens in Kyoto. Once when he visited my laboratory, he emphasized that IMCT is selective for eliminating target cells by apoptosis and has no deteriorating effects on other cell types. He recommended applying the IMCT technique to neuroscience. We discussed doing collaborative work, and a Ph.D. student, Dai Watanabe, decided to apply this technique to investigate synaptic mechanisms of the cerebellar network by focusing on Golgi cells in the cerebellum (Watanabe et al., 1998).

In the cerebellar circuitry, Golgi cells mediate feedback inhibition onto granule cells. However, Golgi cells represent less than 1% of the cerebellar cell population, and the physiological and functional role of Golgi cells in the cerebellar circuitry largely remains to be determined. With the IMCT technology, we generated transgenic mice that express the human IL-2 receptor under the control of a neuron-specific promoter. We then injected the immunotoxin that is specific to the human IL-2 receptor and not cross-reactive with the endogenous mouse IL-2 receptor. The immunotoxin binds to the membrane human IL-2 receptor in transgenic mice and this complex is internalized and kills target cells, thereby leading to the elimination of a specific neuronal cell type.

We constructed a transgene that contained the mGluR2 promoter, followed by human IL-2 receptor fused to GFP. In the cerebellum of transgenic mice, the human IL-2 receptor was specifically expressed in Golgi cells. Immunotoxin injection ablated Golgi cells in transgenic mice but not in wild-type mice, and this cell ablation had no influence on any other cerebellar cell types. Golgi cell-ablated transgenic mice showed severe acute motor disorders after immunotoxin injection but, interestingly, the severe motor disorders gradually recovered in the chronic phase. However, these mice still failed to perform more complex motor tasks such as staying on a rapidly rotating rotarod.

We addressed how synaptic transmission is perturbed in the acute phase and how this perturbation is at least partly compensated in the chronic phase. We performed a series of electrophysiological and optical recordings of cerebellar slices of wild-type and Golgi cell-eliminated mice with the assistance of Keisuke Toyama of the Department of Physiology, Kyoto Prefectural University, and Masanobu Kano of the Department of Physiology, Kanazawa University. These studies allowed us to explore the novel synaptic mechanisms of the mossy fiber-granule cell-Golgi cell synapses. Under normal circumstances, GABA inhibition and NMDA receptors play an important role in the synaptic integration responsible for complex motor coordination. When Golgi cells are eliminated, GABA is depleted, and this depletion results in overexcitation of NMDA receptors and causes severe acute motor disorders. In the chronic phase, NMDA receptors are adaptively attenuated, thus relieving the overexcitation of granule cells. Importantly, AMPA receptors remain unchanged before and after Golgi cell elimination, and these AMPA receptors allow animals to perform simple motor movements. However, NMDA receptors are attenuated, thus causing functional deficits in directing more complex movement coordination. Our studies demonstrate that excitatory and inhibitory neurotransmissions concertedly act at the mossy fiber-granule cell-Golgi cell synapses, and this cooperative action is important not only for integrative brain functioning but also for the compensation of brain dysfunction.

We extended the IMCT technique to other neural networks. The basal ganglia control motor balance and reward-based learning. In the basal ganglia, cortical information reaches medium-sized spiny neurons in the striatum and is transmitted to substantia nigra pars reticulata (SNr)/ventral tegmental area (VTA) through two parallel routes termed the direct and indirect pathways. The two pathways exert opposite effects on SNr/VTA and control the dynamic balance of the basal ganglia-thalamocortical circuitry. Dopamine from substantia nigra pars compacta (SNc) is crucial for exciting and inhibiting the direct and indirect pathways, respectively. As a consequence, dopamine depletion in Parkinson’s disease causes severe motor imbalance. Acetylcholine is locally released from striatal cholinergic interneurons, which represent 1% to 2% of the striatal cell population. Because acetylcholine agonists and antagonists cause global effects on many other brain regions, previous pharmacological studies failed to indicate the physiological and behavioral role of local acetylcholine in the striatum.

Satoshi Kaneko spent 5 years as a neurologist and came to my laboratory as a graduate student. He was interested in the regulatory mechanism of the basal ganglia and looked at striatal functions of our knock-out and transgenic mice. One day, I recalled Kaneko’s finding that one specific striatal cell type showed a high intensity of GFP/IL-2 receptor fluorescence in the IMCT transgenic mice. I pointed out the possibility that this cell type could correspond to striatal cholinergic interneurons and may be a good target for the IMCT technique to characterize the local cholinergic action in the basal ganglia function. In fact, this turned out to be the case, and the immunotoxin injection selectively eliminated cholinergic neurons in the basal ganglia network. Unilateral ablation of cholinergic neurons caused an acute abnormal turning behavior and then showed a gradual recovery thereafter. This recovery, however, was incomplete, and mice continued to display abnormal turning behavior when there was an excess of either stimulation or inhibition produced by dopamine. His series of experiments led to the important conclusion that the reduction of basal ganglia acetylcholine results in dopamine having the predominant effect. Then D1 and D2 dopamine receptors are adaptively down-regulated, thus relieving the dopamine overaction and compensating acetylcholine-depleted synaptic perturbation. However, this compensation is still defective in responding to excessive stimulation and inhibition by dopamine. Therefore, we can conclude that the acetylcholine–dopamine interaction is concertedly and adaptively regulated to control the basal ganglia function.

Two more Ph.D. students, Takatoshi Hikida and Yasushi Kitabatake, came to our laboratory and worked on another important function of the striatum (Hikida et al., 2003). The nucleus accumbens (NAc), the ventral part of the striatum, is a key neural substrate in the addiction to abusive drugs such as cocaine and morphine. They showed that ablation of the NAc cholinergic neurons enhances the acute and long-lasting behavioral changes of abusive drugs, such as cocaine-induced hyperlocomotion and conditioned place preference to cocaine and morphine. Importantly, acetylcholinesterase inhibitors suppress cocaine and morphine-induced behavioral changes, and this suppression is abolished by ablation of the NAc cholinergic neurons. These studies demonstrate that acetylcholine synthesized locally in the NAc plays a key role in the acute and chronic actions of cocaine and morphine.

Another project focusing on retinal circuitry was performed using IMCT by a Ph.D. student, Kazumichi Yoshida et al. (2001). In retinal circuitry, ON-OFF ganglion cells respond maximally when a stimulus moves in a preferred direction, but little or no response is evoked when the stimulus moves in the opposite null direction. This mechanism, called “direction selectivity,” represents primitive pattern recognition of visual information. Among the diverse types of amacrine cells in the retina, one type of amacrine cell, called the “starburst cell,” forms an asymmetric connection with ON or OFF bipolar cells and ON-OFF direction-selective ganglion cells. The starburst cell was implicated in the mechanism of direction selectivity of ON-OFF ganglion cells. However, the role of the starburst cell in direction selectivity was controversial.

Consistent with our previous observation that mGluR2 is specifically expressed in starburst cells within the retina, the IL-2 receptor/GFP fusion protein was found to be highly expressed in starburst cells of the IMCT transgenic mice. Yoshida intravitreally microinjected immunotoxin into adult mice and showed that starburst cells are specifically ablated after immunotoxin injection. We then started collaborative work with Masao Tachibana of the Psychology Department, University of Tokyo. Upon measuring responses to light movement in eight directions, we showed that ON-OFF ganglion cells in starburst cell-eliminated transgenic mice respond to all directions of light movement, indicating that starburst cell elimination abolishes the direction selectivity of ON-OFF ganglion cells. Furthermore, in these transgenic mice, optokinetic nystagmus, which was observed before immunotoxin injection, became negligible after starburst cell elimination. Our study thus provided compelling evidence that starburst cells play a key role not only in originating retinal direction selectivity but also in deriving optokinetic eye movement.

Osaka Bioscience Institute: Reversible Neurotransmission Block

We are obliged to retire from Kyoto University at the age of 63. I was fortunate to have an offer to become the Director of Osaka Bioscience Institute (OBI). OBI is located in a quiet and beautiful suburb of the city of Osaka and is financially supported by the city. The aim of this Institute is to achieve research of internationally acclaimed quality in the basic fields of bioscience and medicine. My position as Director is to be responsible for the administration of OBI. But this Institute is small, consisting of only five laboratories. I can thus continue research by organizing my own group of about 10 members of postdoctoral fellows and graduate students from affiliate universities such as Kyoto University and Osaka University.

In one of our projects at OBI, we are focusing on the synaptic mechanisms underlying cerebellum-dependent motor learning. The conditioned eye-blink response is a typical cerebellum-dependent motor learning. When a conditioned sensory stimulus such as a tone is paired with an unconditioned stimulus, the trained animals exhibit a tone-dependent eye-blink response in the absence of unconditioned stimulation. Information about the conditioned stimulus is transmitted through the pons, mossy fibers, granule cells, and parallel fibers, whereas information about the unconditioned stimulus is transmitted through the inferior olive and climbing fibers. Importantly, this information converges on Purkinje cells and deep cerebellar nuclei, namely, the interpositus nucleus. However, the relative importance of these two sites and the underlying mechanism of cerebellum-dependent eyeblink motor learning have remained largely unclear.

The IMCT technology is very useful for delineating the synaptic mechanisms of a specific neural network. However, this technique irreversibly ablates synaptic transmission in the target network. We therefore developed a novel technique termed “reversible neurotransmission blocking” (RNB) that allows us to reversibly block synaptic transmission in a specific neural network. Mutsuya Yamamoto came from the Mitsubishi Pharma Company to learn mammalian molecular biology and together with a Ph.D. student, Norio Wada, developed the RNB technique during my stay at Kyoto University (Yamamoto et al., 2003). With the RNB technology, we generated two lines of transgenic mice. One line of transgenic mice selectively expressed tetracycline-activating transcription factor in granule cells under the control of the GABAA α 6 promoter. In the second line, the fusion protein of tetanus toxin and GFP was controlled by the tetracycline-activating transcription factor. Tetanus toxin is a bacterial toxin that selectively cleaves the synaptic vesicle VMMP2 and blocks transmitter release from the synaptic vesicle. When these two lines were mated, tetanus toxin was selectively expressed in granule cells, dependent on the administration and omission of a tetracycline derivative, DOX. This procedure selectively and reversibly blocked granule cell transmission to Purkinje cells. As a consequence, the conditioned stimulus is not transmitted to Purkinje cells, but this information is still conveyed to the interpositus nucleus. Therefore, a reversible blockade of granule cell transmission can delineate the role of the two information pathways in conditioned eye-blink responses.

Norio Wada performed electrophysiology and behavioral experiments on conditioned eye blink motor learning (Wada et al., 2007). We confirmed the reversibility of granule cell transmission to Purkinje cells by extracellular recording of Purkinje cells in awake animals. This blockage, however, had no influence on climbing fiber transmission. We therefore succeeded in reversely manipulating the blocking of granule cell transmission to Purkinje cells without any impairment of responses to the climbing fiber input. We then tested the conditioned eye-blink responses in this model animal. In RNB mice, the conditioned eye-blink response disappeared during the administration of DOX and was recovered by the omission of DOX. Importantly, when granule cell transmission was recovered by the withdrawal of DOX, the normal conditioned response was immediately induced at the beginning of the second conditioning session of the pretrained RNB mice. This finding explicitly demonstrated that although the conditioned response is not expressed during DOX treatment, this memory is acquired and stored in RNB mice during DOX treatment. We further confirmed that memory acquisition and storage in DOX-withdrawn RNB mice was completely abolished by a bilateral lesion of the interpositus nucleus.

These results demonstrate that the information in conditioned signals to Purkinje cells is necessary for the expression of conditioned responses, but the memory is acquired and stored despite the absence of conditioned signals to Purkinje cells. The most plausible interpretation of our study is that the blockage of granule cell transmission relieves tonic Purkinje cell inhibition, and that the interpositus nucleus induces latent neural plasticity in response to paired conditioned and unconditioned signals. This neural plasticity should be critical for memory acquisition and storage and would allow prompt expression of conditioned responses once the expression process is restored by the recovery of granule cell transmission.

Concluding Remarks

When I look back upon my research life of more than 40 years, starting from the age of 25 years old, I feel that I have performed my research work on the basis of consistent thinking and attitudes toward my research projects. First, I have maintained a great interest in the mechanisms underlying intercellular communication from the standpoint of investigating molecular constituents involving a targeted biological system. This attitude probably reflects my fondness for chemical analysis, which has certainly stimulated my imagination to explore molecular mechanisms underlying intercellular communication in various parts of biological systems. For those who have this inclination, recombinant DNA technology provides a superb approach for predicting the possible functions of a molecule of interest from its deduced structural characteristics, and for verifying its functions through various techniques related to recombinant DNA technology. I was fortunate in being able to enjoy working during a revolutionary period in the development of recombinant DNA technology.

Second and needless to say, different approaches such as molecular biology and electrophysiology have greatly contributed to establishing the principal concepts of biological systems. However, because common mechanisms often underlie apparently distinct biological phenomena, it is usually very difficult to find a novel principle using a well-established methodology. I have therefore aimed at developing new and logical approaches as much as possible and also directed our research projects toward the boundary between different fields. In this context, I like Sydney Brenner’s witty remark, saying, “Progress in science depends on new techniques, new discoveries, and new ideas, possibly in that order.” In many cases, the introduction of a new tool did not work as well as expected, but in some cases it led to a new and expected finding. More exciting, new approaches sometimes led to an unexpected and more interesting finding. To establish a new tool, it is essential to organize a collaborative team with members from different fields. In Kyoto University, we fortunately were able to organize a nice collaborative triangle between molecular biologists (our group), electrophysiologists (Motoy Kuno, Haruki Ohmori, Tomoyuki Takahashi, Tomoo Hirano, Toshiya Manabe, etc.) and morphologists (Ryuichi Shigemoto, Noboru Mizuno, etc.) This triad was not only fruitful for directing new research projects through collaborative studies but I also greatly enjoyed many exciting discussions about the different viewpoints of our colleagues in different fields.

Finally, as I mentioned, our research advances were mostly achieved by a number of Ph.D. students working with me. They had to gain the basic knowledge and techniques of bioscience and medical science at the beginning and to learn how to design and proceed in experimental research from the beginning. My graduate students were so talented and self-motivated that they came to organize their own research projects and to explore exciting mechanisms during the latter stages of their Ph.D. course. Consequently, I enjoyed not only looking at the exciting progress of their research works, but also recognizing the remarkable development in their abilities as research scientists. My 40-year research life has been a very pleasant time during which I have been able to experience the creativity of science and young talented scientists.

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Solomon H. Snyder

BORN:

Washington, D.C.

December 26, 1938

EDUCATION:

Georgetown College, Washington, D.C. (1955–1958)

Georgetown Medical School, Washington, D.C. M.D. Cum Laude (1962)

APPOINTMENTS:

Research Associate, NIH, (1963–1965)

Resident, Psychiatry, Johns Hopkins (1965–1968)

Assistant (1966–1968), Associate (1968–1970), Full (1970– ) Professor, Johns Hopkins, Pharmacology and Psychiatry

Distinguished Service Professor of Neuroscience Pharmacology and Psychiatry, Johns Hopkins (1980– )

Director, Department of Neuroscience, Johns Hopkins (1980–2006)

HONORS AND AWARDS (SELECTED):

Honorary Doctorates:

Northwestern University (1981)

Georgetown University (1986)

Ben Gurion University, Israel (1990)

Albany Medical College (1998)

Technion University, Israel (2002)

Mount Sinai Medical School (2004)

University of Maryland (2006)

Awards:

Albert Lasker Award (1978)

Wolf Prize (1983)

Bower Award (1992)

National Medal of Science (2005)

Albany Prize in Medicine (2007)

Honorific Societies:

American Academy of Arts and Sciences (1979)

National Academy of Sciences USA (1980)

Institute of Medicine (1988)

American Philosophical Society (1992)

Solomon Snyder identified receptors for opiates and neurotransmitters and elucidated mechanisms of drug action. He characterized messenger systems including IP₃ receptors and inositol pyrophosphates. He identified novel neurotransmitters including nitric oxide, carbon monoxide and D-serine.

Solomon H. Snyder

Like most other people, I am the product of my parents. Hence, a brief review of their lives may provide insight into my own. Similarly, the lives of my siblings may be informative. My dad was born in 1911 in Baltimore, the fifth of seven children. His father moved to Washington when he was 2 years old to open a small grocery store a block away from the butcher shop operated by Al Jolson’s father. Like his father and most of his siblings, Dad was musical and for many years was a semiprofessional saxophonist in dance bands, though his greatest love was classical music. Graduating high school in 1929, he meandered among clerical jobs at Federal agencies in the depths of the depression. Soon after marrying Mom in 1935, Dad became the 10th employee of a tiny government agency which emerged as the National Security Agency (NSA). Throughout World War II he led a team of a few hundred cryptanalysts addressing various Japanese codes. At the end of the war modern computers were invented and Dad was assigned to “find out if these machines might help the code breaking effort.” Within a couple of years he led an effort that made NSA the largest computer installation on earth. He became so enamored with computer programming, that when I was 10 years old he taught me to program computers in “machine language” which incorporated the binary number system. Though not technically a scientist, Dad greatly admired science and often spoke with me about science as the highest activity of mankind. However, Dad was very easy going and never ordered or even strongly urged that any of we five kids pursue particular avenues of personal development.

Mom was complex. Born in New Haven, Connecticut, she came to Washington during the depression to find work with the Federal Government. She had a decided entrepreneurial flair. Thus, when my sister Elaine and I were 4 and 2 years old, respectively, and Washington was flooded with lonely young government workers arriving from all over the country, she decided to “do something.” With Dad’s assistance she organized “The Carefree Circle,” a social club. Within a year the organization overflowed our tiny house and attracted the attention of the city’s newspapers, the Washington Post and the Washington Star. The Carefree Circle spawned a semi-professional sandlot baseball team. My mother knew nothing about baseball but appointed herself “manager.” Her main contribution was to introduce a female pitcher despite the fact that there had never been a single female sandlot player in the history of the city. As projected, this gimmick attracted further news media coverage.

After World War II, with four small kids at home, Mom perceived the enormous pent-up demand for housing (no homes were built during the war) and founded Snyder Realty Company. Soon she had a sales manager and 15 salesmen. Once the real estate boon wound down, Mom became interested in the emerging world of contesting, for example, “Write in 25 words or less why you like Ivory Soap.” Soon she emerged as one of the top contesters in the country winning several major competitions including the “Stop the Music” jackpot which yielded $10,000 (in 1952 money), a trip to Jamaica, wardrobes of the finest men’s and women’s clothes, a kitchen full of appliances and other prizes. Her creative flair led to massive numbers of innovative jingles or short essays, while Dad’s organizational abilities eventuated in an operation generating hundreds of copies of each entry (years before Xerox machines existed) as well as collating myriad box tops from diverse products that were required for entry submission. Perhaps a combination of Mom’s and Dad’s genes impacted my scientific career. One might speculate that free-floating creative associations coupled with clear, wellorganized conceptualization make up the qualities that make for success in science.

Science has never been much evidenced in our family. My late older sister Elaine was an artistic prodigy who could draw almost perfect likenesses of human faces when she was 5 years old. At Mom’s behest she developed an act in which she would sing a song which she would simultaneously illustrate. After winning various talent contests sponsored by Washington television stations, she appeared on network television. She did all the show business stuff under pressure from Mom, a notorious stage mother. Wed to an eminent entomologist, Elaine became one of the country’s leading natural science illustrators with a major retrospective of her work upon her retirement from the Smithsonian Institution. My younger sister Carolyn also performed as a singer and dancer. A natural beauty, she was a finalist in the Miss America contest, Washington, D.C. division, and ultimately became a psychiatric nurse. My younger brother Irving, though also musical, never became involved in show business and is presently a psychiatric social worker. Joel, “the baby” of the family, 15 years younger than I and 17 years younger than Elaine, has been an actor since he was 7 years old. He continues to perform semiprofessionally though he became an arts administrator to support a wife and daughter who is a professional actress.

Both sets of my grandparents immigrated to the United States in the first decade of the twentieth century. I was closest to my maternal grandfather who lived with us for much of my childhood years. In Vitebsk, Russia, he played balalaika and the mandolin and, when I was age 9, gifted me his extra mandolin. Having played the piano since I was age 5 and the clarinet for a few years, I had some musical background and glommed on to the mandolin, rapidly assimilating everything my grandfather knew. Seeking a mandolin teacher for me, Dad encountered Sophocles Papas, the leading teacher of the classic guitar in the United States and Andres Segovia’s closest friend, who also taught the mandolin. After 3 years of mandolin lessons, I switched to the guitar. Although I enjoyed the mandolin, I adored the guitar which was soon a consuming passion. Before I graduated high school I was giving public recitals and seriously considered spending a summer at master classes in Siena, Italy, with Segovia and then pursuing a musical career. However, a desire to be “one of the guys” supervened so that, like most of my friends, I went to college as a premed.

I differed from the other guys in that I had no particular interest in medicine, biology, or science. Instead, I loved philosophy and speculating about origins of the universe and the raison d’etre of life. Much of this may have come from the first 9 years of my schooling in a Jewish day school where we studied Torah every morning and participated in group prayer services. Whatever the underlying conscious or subconscious motivations, I loved to think about “big questions.” I rationalized that if I could stomach the science courses of college and medical school, I might become a psychiatrist that, to my naive way of thinking, wouldn’t differ too much from a life in philosophy.

As foolish as most of this reasoning may have been, it largely came to pass. I attended Georgetown College for 3 years (in those days you didn’t need a bachelor’s degree to enter many medical schools) and then Georgetown Medical School. I did become a psychiatrist and my life has been devoted to brainstorming about what might be construed as “big questions” though with a far more molecular emphasis then I would have anticipated.

In college I did well in most subjects but was particularly strong in English and philosophy. My success in writing was surprising considering that Calvin Coolidge public high school, which I attended after the Hebrew Academy, was replete with lazy faculty who never assigned essays simply because they were not willing to read and grade them. Freshman English was a year-long course in writing essays, a new 500-word essay each week. I recall vividly the first essay I wrote, “The Case for the Classic Guitar,” somewhat plagiarized from my high school term paper, the only piece of writing we ever did in high school. This English course was designed to shock the students into an appreciation of their weaknesses and to inspire some intellectual discipline. Every single fellow in the class (Georgetown was an all-boys college) received no higher than a C+ except for a single A+ which was me. Our English professor, the faculty advisor for the Georgetown Literary Magazine, arranged to have the essay published. Over the course of freshman year others of my essays, all on music, were published in the magazine.

In the summers following freshman and sophomore year of college my father arranged for jobs for me at NSA (even though the top-secret code word security clearance cost the government $10,000 each summer versus the $500 that I earned). In the first year, he had me work with the IBM sorters, collators, and printers that were the predecessors of computers, whereas in the second summer I worked directly with computers. Although I was suitably impressed with the elegance of the logic involved in computer programming, computers never “turned me on.” I had negligible mathematical aptitude and, while fascinated by the challenges of cryptography, I clearly lacked any gift for code breaking.

Throughout college I maintained an interest in the guitar, practicing regularly and working every Saturday at my teacher’s guitar shop, minding the shop, keeping the books, and giving lessons. I helped organize events for the local guitar society, especially when Andres Segovia performed in Washington, D.C. On one of these occasions Mr. Papas had me perform for the maestro. By this time, a junior in college, I was somewhat out of practice and knew that it would be foolhardy to attempt to impress with my virtuosity. Instead, I surprised Segovia by playing two fantasies that he had himself composed and published years earlier in a guitar magazine. They were deeply expressive pieces but with no major technical challenges, and I adored them. Segovia evidently liked the performance—at least he complimented me on my “expressive soul.”

The same year on a Saturday afternoon a young physician entered the shop and inquired about the possibility of guitar lessons with Mr. Papas. When I told him the rates, he shuddered and asked whether anybody else taught and charged less. I indicated that he could take lessons with me for a lower fee. He then asked whether I would charge still less if I came to his apartment, not far from my own home, and could thus pocket the entire fee myself. My new guitar student, Don Brown, was then in the first Research Associate class at the NIH and subsequently essentially founded the field of molecular embryology. Don and I became lifelong friends as well as teacher and student. For the summer after my junior year, just before I started medical school, Don asked whether I might work with him as a technician. Although I had no particular interest in scientific research, I thought it would be interesting to learn a little bit about the biologic underpinnings of medicine. Thus commenced a romance with the NIH. Throughout medical school I spent every summer and elective period at the NIH. This led to my time with Julie Axelrod and everything thereafter.

Medical School

The summer before medical school I worked with Don developing techniques to monitor the metabolism of histidine in animals and humans by administering [14C]histidine, then fractionating and identifying urinary metabolites. Why study amino acid metabolism? Don was doing his military service obligation in the Laboratory of Clinical Science at National Institute of Mental Health (NIMH), whose director Seymour Kety was fascinated by reports of abnormal biogenic amines in the urine of schizophrenics suggesting some metabolic abnormality in the precursor amino acids. Each Research Associate was supposed to select an amino acid and develop techniques that would ultimately be employed to compare normals and schizophrenics in the NIMH metabolic wards. Don selected histidine and subsequently showed there were no differences in the metabolism between normal controls (Mennonite conscientious objectors) and schizophrenics. In the process he identified novel metabolic pathways such as the formation of hydantoin propionic acid and developed evidence that the pathway from histidine to glutamic acid proceeded through an unstable intermediate, imidazolone propionic acid. After my first summer at the National Institutes of Health (NIH), Don completed his military service and departed for Paris to learn modern molecular biology with Jacques Monod. He designed for me a well-articulated project, namely an attempt to identify and purify the enzyme that would convert imidazolone propionic acid to formimino-glutamic acid, which then donated its forminino group to tetrahydrofolate ultimately leading to the critical methyl group of S-adenosylmethionine. I labored for a couple of summers and elective periods trying to characterize and purify the enzyme. For the majority of the time, I was working with an artefact, as imidazolone propionic acid was so unstable that it was decomposing nonenzymatically. I finally stabilized the substance by exhaustively eliminating all oxygen from the sealed test tubes, characterized and purified the enzyme about 50-fold and wrote by myself a full-length paper for the Journal of Biological Chemistry that was accepted with no revisions (Snyder et al., 1961b).

My single original contribution in the lab came when Marian Kies, the Laboratory Director, received a letter from a pediatrician in Milwaukee, Stanley Berlow, who had read publications of the laboratory about histidine metabolism. He was treating a mentally retarded 10-year-old girl whose urine was positive in the ferric chloride test for phenylketonuria, whereas paper chromatography revealed normal levels of phenylalamine but a massive histidine spot. To seek the patient’s metabolic abnormality, I journeyed to Milwaukee with a bottle of [14C]histidine. I fed her large amounts of [14C]histidine (there was no institutional review board) and personally collected her urine for a day. Back in Bethesda I fractionated her urine, just as I had done previously with monkeys and rats and, from the urinary metabolite pattern, was able to conclude that she was missing histidase, the initial enzyme in the pathway from histidine to glutamate. Thus, she suffered from a condition which, though rare, occurs in fairly substantial numbers of children and is designated histidinemia (Snyder et al., 1963). In an amazing coincidence, another group at the NIH, led by Bert LaDu and Leon Rosenberg, had been characterizing histidase and found that, besides the liver, it was localized to the stratum corneum of the skin so that one could assay the enzyme in scrapings from the underside of fingernails. When they encountered a local patient with high urinary histidine levels, they simply assayed for the enzyme in the patient and her extended family, elegantly delineating the enzyme deficiency and its genetic distribution.

Psychiatry crept into my school time research. My sister Elaine’s first husband was a Ph.D. psychologist who had developed simple paper-and-pencil tests to elucidate Gestalt phenomena such as “closing gaps.” Because there was a schizophrenia research award closely adjacent to our laboratory, I obtained permission from Dr. Kety to administer these tests to the patients, under the supervision of the distinguished psychologist David Rosenthal. The pilot studies with a few patients at the NIH were so promising that I was dispatched to St. Elizabeth’s to test larger numbers. Chronic schizophrenics displayed less “perceptual closure” than normals. Perceptual closure of normals involves closing gaps, hence copying figures inaccurately so that in this instance schizophrenics could be conceptualized as doing better than normal individuals. The studies also revealed another paradox. In many test paradigms schizophrenics are far more variable than normals. Yet for perceptual closure their variability was notably less.

The perceptual closure work resulted in two papers in the Journal of Abnormal Psychology (Snyder et al., 1961a; Taylor et al., 1963), and one in the Archives of General Psychiatry (Snyder, 1961). For me, more important than the research was the opportunity to encounter psychotic patients. Most medical students are distinctly uncomfortable in confronting people who behave bizarrely. I enjoyed sitting quietly with them, trying to absorb their “essence” and to fathom what was underlying their disordered behavior. During junior year in our medical school psychiatry rotation, we were assigned patients to “treat” in a psychotherapy setting one-on-one in a private office. I savored the experience so that my ill-formed plans to become a psychiatrist now had a foothold in reality.

Julie

Knowing I wanted to be a psychiatrist, my next challenge was how to cope with the doctor draft. In the early 1960s every male medical school graduate had to pursue 2 years of military service or figure some “way out” such as joining the Reserves or National Guard, which were perennially oversubscribed. As a component of the Public Health Service, the NIH was “military.” To attract young physicians into science, the NIH had developed a Research Associate program, essentially a 2-year postdoctoral position with “military” appointment at the equivalent level of Major. Initially, I had in mind a similar position, Clinical Associate, involving 2 years at the NIH doing clinical research as well as caring for psychiatric patients. Besides providing an entrée into academic psychiatry, the 2 years at the NIH would count for a year of psychiatric residency, shortening what seemed like an overly long period of training. In this model, I would be coming to the NIH after 2 years of psychiatric residency so there was no hurry. These elegant plans were disrupted by romance. In senior year of medical school Elaine Borko and I began dating and were engaged about Christmas time. I was set on interning in San Francisco as, for lack of funds, I had lived at home all the way through college and medical school and wanted to get far, far away. However, if we were to marry when I graduated medical school, Elaine would have another year of college, which required residency in the Washington area to fulfill her practice teaching requirements.

With the new pressure to return to Washington after a single year interning in San Francisco, I scoured the NIH seeking any laboratory with an opening for one year hence. Unfortunately, all labs were filled, because the Research Associate positions were allocated by a match program that had already closed. After a prolonged and fruitless exploration, my salvation turned out to be directly across the hall from the laboratory of Marian Kies where I had worked all through medical school—Julius Axelrod. I had met Julie during my summers working on histidine metabolism. In those days Julie was discovering one methylating enzyme after another. Because Don Brown had been working on histidine, Julie suggested that they collaborate to seek a histamine-methylating enzyme that they successfully identified. When I approached Julie, he commented that most of the applicants he interviewed were “valedictorians from Harvard or Yale.” However, the Harvard student who had matched with Julie had abruptly cancelled so there was a vacancy.

Research Associate Years

The year in San Francisco, where I interned at the Kaiser Hospital on Geary Blvd., was perhaps the happiest of my life. Newlywed, Elaine and I explored San Francisco and its environs and made close friends we have retained through the years. Whereas interns at East Coast academic hospitals worked every other night all night, we were typically on call only every fourth or fifth night and even then would get 4 or 5 hours sleep. I even had a small bit of exposure to science. On Julie’s recommendation, I spent my one month elective working in the laboratory of Alan Burkhalter at the University of California San Francisco Medical Center in the Pharmacology Department, where he had developed a novel fluoremetric assay for tissue histamine. I carried out a few experiments but mostly enjoyed the gorgeous view of San Francisco from high atop Parnassus Avenue.

Julie began all of his students with a carefully structured project to ensure positive feedback, often taking advantage of some unique feature of a student’s prior training. For instance, Dick Wurtman had spent his elective periods in Harvard Medical School working on the biology of the pineal gland whose extracts inhibited estrus and lowered ovarian weight. Julie suggested that he seek the pineal gland’s “hormone” that turned out to be melatonin. Because of my background in histidine metabolism and my brief exposure to Burkhalter’s histamine assay, Julie recommended that I monitor the disposition of exogenous histamine using the same techniques he had employed to discover norepinephrine uptake. I administered radiolabeled histamine to rats and monitored its disposition in various organs. In contrast to the experience with norepinephrine, there was no pronounced accumulation of histamine in any tissue. Instead, I found large amounts of the metabolic product imidazoleacetic acid as a riboside, raising questions about its potential biologic role (Snyder et al., 1964). Because of my sloppiness, I dismissed as artefact a prominent radioactive band at the origin of my paper chromatograms that was shown by Jack Peter Green at Yale (together with his postdoctoral fellow David Fram, my classmate from kindergarten through high school) to be imidazoleacetic acid ribotide, a novel metabolite. Yet another lesson in avoiding my inherently hasty and slovenly approach to experiments.

The real excitement in Julie’s lab at the time lay in the series of breakthroughs Dick Wurtman was making regarding melatonin acting as a pineal hormone with its biosynthesis being influenced by light exposure. Melatonin is formed from serotonin which is acetylated. N-acetylserotonin is then methylated by hydroxindole-O-methyltransferase (HIOMT), an enzyme discovered by Julie, to form melatonin. Julie showed me a paper he had noticed in a chemical journal reporting that heating serotonin with ninhydrin, a standard chemical stain for proteins, led to an intensely fluorescent product whose fluorescence was about 10 times that of serotonin itself in strong acid solution, the standard assay for serotonin. Within a week I had developed an organic solvent extraction system that permitted an assay for tissue serotonin utilizing the ninhydrin technique (Snyder et al., 1965a). With this assay, we could monitor serotonin levels in as few as two to four rat pineal glands, each weighing 1 mg. In an heroic study, consuming about 400 rats, Wilbur Quay had reported a dramatic diurnal rhythm in serotonin levels with peaks at noon of 100 μg/g (100 times brain levels of serotonin), about 10 times higher than nocturnal troughs. With far fewer rats, I was able to replicate Quay’s finding. Because relatively few rats needed to be consumed for each experiment, I was able to evaluate various experimental conditions. To prevent the effects of light, I enucleated the eyes of rats or maintained them in constant darkness. To my amazement, the serotonin rhythm persisted (Snyder et al., 1965b). I remember exclaiming to Julie, “We’ve discovered a biological clock.” Julie was even more excited than I until a brief library search the next day revealed that endogenous diurnal rhythms, biological clocks, had been well characterized in mammals since the 1920s. We learned a good deal about regulation of the circadian serotonin rhythm which we now know to reflect an opposing rhythm in serotonin N-acetyltransferase, the rate-limiting enzyme in melatonin formation, whose augmented night-time activity depletes serotonin from the pineal.

Thirty years later, I returned to the pineal gland. Jimo Borjigin, a new postdoctoral fellow, had done her doctoral work with Jeremy Nathans on the molecular biology of vision. She regarded vision as a mature area of research and wanted to explore related but relatively unmined areas. She was fascinated by the pineal gland that, in some species, is a “third eye.” It was well accepted that serotonin N-acetyltransferase (NAT) is the regulatory enzyme in melatonin formation, but no one had ever isolated or cloned it. Purifying such a protein from such a small organ seemed hopeless. Instead, Jimo decided to employ subtractive hybridization. She knew that NAT expression was vastly higher at night than during the day. Accordingly, she collected large numbers of rat pineal glands during the day and at midnight, seeking messages expressed selectively at midnight. One of these turned out to be NAT (Borjigin et al., 1995). Independently, David Klein at the NIH, who had first discovered diurnal rhythms in NAT almost thirty years earlier, cloned the same enzyme (Coon et al., 1995).

Julie allowed, indeed encouraged, his students to carry out “flyers” on their own, for which he did not assume any authorship. Thus, during my 2 years at the NIH I collaborated with Martin Reivich administering LSD to monkeys, dissecting many small brain regions and discovering marked variations in LSD levels. The paper, published in Nature (Snyder and Reivich, 1966), attracted much attention; but why LSD should display regional variations was puzzling. We now know what was going on. LSD was binding to the serotonin 1A receptors that mediate actions of psychedelic drugs. Hence, this study was the first demonstration of a serotonin receptor in an intact organism.

As part of my fascination with psychedelic drugs, I noted in a short book by the Nobel Laureate Albert Szent-Gyorgi a comment that LSD had remarkable charge transfer capacities. My medical school classmate Carl Merril was also at the NIH in a laboratory where computers were being applied to molecular orbital calculations. Together we carried out computations on a fairly extensive series of psychedelic drugs and showed a correlation between their charge transfer capacities and their psychotropic potencies (Snyder and Merril, 1965). This was my first foray into the adventure of divining how drugs exert their pharmacologic actions.

I also collaborated with Arthur Michaelson in subcellular fractionation studies. Arthur had recently completed a postdoctoral period in Cambridge, England, with Victor Whittaker participating in the pioneering subcellular fractionation techniques that permitted isolation of pinched-off nerve terminals, synaptosomes. Arthur was likely the only American scientist with expertise in the arcane sucrose gradients required for such fractionation. Together, we used these techniques to purify norepinephrine storage granules from the heart and to identify synaptosomal fractions in the brain following labeling with [³H]norepinephrine (Snyder et al., 1964). Labeling synaptosomes with [³H]norepinephrine, was done in our lab together with my good friend Jacques Glowinski, then also a postdoctoral fellow with Julie (Glowinski et al., 1966). Jacques had perfected technology for intraventricular injections of [³H]norepinephrine permitting these studies as well as the important experiments in which Jacques and Julie showed that the relative potencies of antidepressants in inhibiting norepinephrine accumulation into the brain paralleled their antidepressant efficacy. Jacques and I were together with Julie for the same 2 years, while our “third musketeer,” Leslie Iversen, was in Julie’s lab only for a year, spending the second year of his Harkness fellowship at Harvard with Steve Kuffler.

First Years at Johns Hopkins

The 2 years with Julie were exhilarating. Like all Julie’s students, I learned the joy of brainstorming new ideas, conceptualizing experiments that one could carry out in a day, digesting the results that evening, and planning the next day’s experiments. Although many experiments failed, a good number succeeded, and Julie was constantly encouraging even during the fallow periods. All of this imbued me with the science bug. Nonetheless, I never lost my desire to become a clinical psychiatrist. While I was at the NIH, two other aspiring research psychiatrists who were a couple of years ahead of me, Ernie Noble and Jack Barchas, had worked out a remarkable arrangement in the Stanford Psychiatry Department. The departmental chair, David Hamburg, was trying to build up a department with strong research psychiatrists. He offered Ernie and Jack “research residencies” during which they would be paid salaries comparable to junior faculty and would direct their own laboratories.

During a visit with Dr. Hamburg we came to a handshake agreement that he would do the same for me. At a late stage, too late for additional residency applications, the arrangement fell through, Hamburg lacking the facilities to provide a third research residency slot. I was crushed. Julie said that I could continue in the lab for another year or more. I met with Seymour Kety who indicated that his friend Joel Elkes had recently become Director of Psychiatry at Johns Hopkins and, with the associated turnover of personnel, it was likely that there were residency vacancies. Baltimore wasn’t Palo Alto, but Dr. Kety indicated, “Beggars can’t be choosers.” Elkes offered only a conventional residency which was distressing, because residents in those days were paid $250 a month. Elaine and I had been married throughout internship and the 2 years at NIH. If she had to continue working to support me throughout a 3-year residency, we would have been married 5 years before being able to have children, a seeming eternity by 1965 standards.

Just about that time Julie lectured at Case Western Reserve Pharmacology Department where the Chair, Nick Carter, was recruiting new faculty. Julie mentioned my availability but indicated that I wanted to do a psychiatry residency. Nick countered that the Dean of the medical school, Douglas Bond, was a psychiatrist and might be able to help. I visited Cleveland and was well received. Doctors Carter and Bond worked out an even more attractive arrangement than the one at Stanford. I would be appointed a full-time Assistant Professor of Pharmacology with a salary better than Stanford and a larger, better funded lab all while doing a psychiatry residency. When I phoned Dr. Elkes to decline Hopkins, he advised that he had already heard about the Cleveland arrangement from Dr. Bond and that Hopkins was prepared to do yet better.

I arrived at Johns Hopkins for Psychiatry residency July 1, 1965, under an arrangement in which I spent the first year as a full-time resident (at $260/month) but beginning with the second year, I was a full-time Assistant Professor of Pharmacology. Elaine was able to stop working, and on October 30, 1966, our first daughter Judith Rhea was born. She was joined 4 years later by her sister Deborah Lynn.

For me, clinical psychiatry was energizing and anxiety provoking. American psychiatry in the 1960s was totally dominated by psychoanalysis. Although Hopkins was far more eclectic than most other university departments, we residents still devoted the vast bulk of our time to one-on-one psychotherapy even with hospitalized schizophrenics. Sitting for an hour with patients and just listening was initially loaded with stress, as we were often dealing with agitated patients, hoping to “do something” for them. Listening didn’t seem to be accomplishing very much. With the assistance of some wise supervisors, I calmed down and learned how to balance activity and passivity in therapeutic settings. Those were also the days of the “therapeutic community” in which doctors, nurses, and patients met regularly as a group with everyone being “equal” in coming to decisions about how to run the ward. I assimilated fairly rapidly the art of handling such complicated group dynamics, lessons which served me well over the years in coping with my faculty as well as board members of our condominium, synagogue, the Society for Neuroscience, and various biotech companies. This was the era of “love and trust” as exemplified by the ongoing tumult in the HaightAshbury district of San Francisco replete with LSD, STP, and every other conceivable psychedelic agent. In those days, medical insurance was far more generous than today with policies for federal workers, who abounded in Baltimore and Washington, covering up to a year or more of psychiatric hospitalization. Of course, most adults couldn’t take off such amounts of time from work. Accordingly, Phipps Clinic, the Hopkins psychiatric hospital, was typically filled with college-aged boys and girls. Some were rebellious while others were more accommodating. One notably recalcitrant teenager, T.M., responded to group therapy by becoming far more community minded, taking over responsibility for maintaining the planters that were beautifying the ward. Every day he carefully pruned the lovely green, leafy plants. Only after 1 or 2 months did one of the aides consult a gardening text and report, “Dr. Snyder those are marijuana plants.”

During the second 2 years of residency, as Assistant Professor of Pharmacology, I devoted about half my time to the laboratory. Paul Talalay, my Chair, outfitted my laboratory and paid for a technician and my first postdoctoral fellow. I even lectured to second-year medical students on psychopharmacology. Two members of the class asked to work in my laboratory that first summer and both stayed with me throughout the remainder of medical school. Both became psychiatrists. One of them, Alan Green, now chairs the Psychiatry Department at Dartmouth, while another, Joe Coyle, formerly chaired the Harvard Psychiatry Department and is now a professor there.

In my new lab at Hopkins, I felt it important to avoid the trap of just continuing with my postdoctoral research. Hence, I terminated all work on the pineal gland, which had been my principal NIH focus. At the NIH, independently of Julie, Joe Fischer, another Research Associate with surgical training at Massachusetts General Hospital, and I had collaborated in a study demonstrating dramatic increases in the activity of histidine decarboxylase, the histamine synthesizing enzyme, in rat stomach after portocaval shunt, a surgical procedure that clinically causes gastric hyperacidity (Fischer and Snyder, 1965). At Hopkins I decided to pursue the dynamic regulation of histidine decarboxylase in the stomach and worked out the rapid turnover of this enzyme following gastrin stimulation of acid secretion, consistent with histamine being the key mediator of acid secretion (Snyder and Epps, 1968). This was of interest, because in those days, prior to the discovery of histamine H2 receptors and their acid-blocking antagonists, cimetidine and ranitidine, it was thought that gastrin rather than histamine was the final common mediator of acid secretion.

When Joe Coyle entered the lab, I was becoming somewhat bored with histamine, as virtually no one else in the world seemed to care about it, all the “action” being with the catecholamines. Up till that time, the reuptake inactivation of norepinephrine had only been studied in intact organs. When people tried to monitor uptake into isolated synaptosomes in sucrose, there was no uptake because the transporter required sodium ions. Homogenizing the brain in salt solutions disrupted synaptosomes. Joe stumbled on a simpleminded approach wherein he homogenized the brain in sucrose and then added salt-containing buffers, the sucrose protecting the synaptosomes from disruption. Utilizing a relatively crude preparation, we could monitor about 50 samples at a time, varying concentrations and working out kinetics of the uptake process (Coyle and Snyder, 1969b). In studying dopamine uptake in the corpus striatum, Joe discovered that a number of widely used antiParkinsonian drugs, thought to act exclusively as anticholinergics, were rather potent inhibitors of dopamine reuptake which thus may contribute to their clinical effects (Coyle and Snyder, 1969a). Joe was remarkably innovative and technically skilled. Most of his key experiments were conducted during a 4-month minisabbatical that Elaine and I and our 2½ year old daughter Judy enjoyed in London, Joe and I communicating regularly by letter.

This high throughput screening for neurotransmitter uptake was soon exploited for therapeutic ends. In 1970 I received the John Jacob Abel Award of the American Pharmacologic Society. Award winners were expected to give a lecture at Lilly, the sponsor of the award. I described our work, which by that time involved synaptosomal uptake of serotonin, norepinephrine, dopamine, and numerous other neurotransmitters. Many years later, in reading Peter Kramer’s volume “Listening to Prozac” I learned of the consequences of my visit. Ray Fuller, a Lilly neuropharmacologist, was impressed with the utility of our assays for pharmaceutical-level screening of candidate drugs and recommended that his colleague David Wong explore the matter. There followed a search for serotonin-specific uptake inhibitors with one of these, fluoxetine (Prozac) coming to super-successful fruition.

While a psychiatry resident, I continued my involvement with psychedelic drugs. Elliot Richelson, a classmate of Alan’s and Joe’s, worked with me making molecular models of various psychedelic drugs and showing commonalities between phenethylamines such as mescaline and indoles such as LSD and psilocybin (Snyder and Richelson, 1968). This led to my most memorable and scary episode at a scientific meeting. I was invited to a meeting at the Salk Institute where all of the eminent “Salk Associates” were assembled. When I presented the Richelson model, the world renowned chemist Leslie Orgel skewered me, remarking that the conformations I proposed were surely not the “favored” ones. I felt humiliated and froze, unable to respond. Suddenly, Francis Crick stood up and admonished, “Leslie, you are an old fuddy duddy. Don’t you realize that in biological solutions other forces may arise to induce conformations not favored in pure solution. This ‘boy’ may well be onto something important.”

I even became involved in clinical studies of psychedelic drugs. Dr. Elkes had been invited by the Dow Chemical Company research labs in Walnut Creek near San Francisco to serve as a consultant regarding the following dilemma. Alexander Shulgin, their star chemist, had been synthesizing methoxyamphetamines, derivatives of mescaline, some of which he maintained could elicit enhanced self-awareness at lower doses than those that were psychotomimetic, hence might be useful in facilitating psychotherapy. At this time, 1967, the Haight-Ashbury district of San Francisco was attracting national attention, its streets replete with “acid heads.” Besides LSD, the hippies ingested multiple drugs. The most notorious, designated STP (serenity, tranquility, peace) was said to elicit an overwhelming psychedelic effect lasting 3 days. Dow wanted to terminate the chemical program and ascertain whether anything of clinical benefit might be salvaged. Dr. Elkes dispatched me to California in his stead. I reviewed the “clinical” data that Shulgin had obtained largely by testing progressively increasing doses of the various methoxamphetamines on himself, his wife, and his son. The laboratory notebooks were impeccable, and I thought he might be on to something important.

Dow agreed to fund clinical studies at Hopkins. Accordingly, I administered low doses of DOET (2,5-diethoxyamphetamine) to Hopkins undergraduate students (clinical research standards were rather lax in those days). Just as Shulgin attested, my students reported a subjective sense of enhanced self-awareness with no psychotomimetic effects, an effect resembling low doses of marijuana. As we were completing the study, I received a phone call from federal narcotic agents indicating that they had solved the structure of STP and it was 2,5-dimethoxyamphetamine (DOM), remarkably similar to the agent I was studying.

I convinced the officials that I had nothing to do with STP. They then asked whether I would help them with the following challenge. They knew the source of all of San Francisco’s illicit LSD and STP, a skilled chemist named Audsley Stanley. Stanley couldn’t be arrested for making STP, because they had no proof that it was a psychotomimetic. Might I agree to demonstrate such effects with DOM (STP) in my student population? They offered a notably generous contract, quadruple the size of my NIH grant. I used these funds and a similar grant from Dow to outfit my lab.

Within a few weeks we gave the students increasing doses of DOM that was indeed psychotomimetic at a high-enough dose. This episode gave rise to my most successful publishing experience, a paper in Science published with record-making alacrity (Snyder et al., 1967). The top brass at the NIH as well as at the Federal Narcotics Bureau wanted the results of our study promulgated widely and rapidly. They put me in touch with John Ringle, one of Science’s senior editors, who said, “Dr. Snyder, if you provide a manuscript to me with a table but no figures I can guarantee publication in two weeks including referee evaluation.” And, indeed, in about 2 weeks the paper was published.

After completing psychiatry residency in 1968, I was promoted to associate professor and given a larger lab so that I was able to recruit additional students. My first official postdoctoral fellow was the extraordinarily energetic Diane Russell who kept rigid 8:30–5:00 hours, because she was raising two small daughters at the same time. I asked her to address a seemingly arcane issue in histamine metabolism. The Swedish physiologist George Kahlson had demonstrated massive levels of histidine decarboxylase in fetal rat liver suggesting a link to rapid tissue growth. However, in regenerating adult rat liver, the classic model for rapid tissue growth, there was no change. Histamine is a diamine. I wonder whether other diamines such as putrescine, formed by the decarboxylation of ornithine, might be involved. In short order, Diane mastered the technique of extirpating two-thirds of the rat liver, which grew back in about a week. We ordered [14C]carboxyl-labeled forms of about 10 amino acids and monitored decarboxylation. I vividly recall that first experiment. For histidine and eight other amino acids, counts were hardly above background. For ornithine decarboxylase, the counter seemed to explode with at least a 50-fold elevation of enzyme activity. This led to an opus showing a role for ornithine decarboxylase and the polyamines which it produces in tissue growth and cancer (Russell and Snyder, 1968). The extremely rapid massive increase in enzyme activity suggested that ornithine decarboxylase must be a very rapidly turning over enzyme. By monitoring its decline following inhibition of protein synthesis with cycloheximide or puromycin, Diane demonstrated that ornithine decarboxylase was the most rapidly turning over known mammalian enzyme, with a halflife of 10 to 15 minutes (Russell and Snyder, 1969). By contrast, enzymes such as tyrosine transaminase, then the height of fashion as dramatically inducible proteins, had half-lives of 1 to 2 hours.

In the late 1960s gamma-aminobutyric acid (GABA) was just being accepted as a neurotransmitter, and there were faint hints that glutamate and glycine might be excitatory and inhibitory neurotransmitters, respectively. I wondered whether the techniques that Joe Coyle developed to monitor synaptosomal uptake of neurotransmitters might be applicable to amino acid transmitters. If reuptake inactivation was “the rule” for terminating activities of neurotransmitters, then the amino acids that were neurotransmitters might display high affinity, sodium requiring uptake in contrast to classic amino acid transporters which were rather low affinity. Bill Logan, a neurologist in the lab, and Jim Bennett, an M.D./Ph.D. student, carried out the principal studies showing that in the cerebral cortex glutamate displayed high affinity sodium-requiring uptake with only low affinity systems evident for the other amino acids (Logan and Snyder, 1971). Interestingly, neurophysiologists had shown that glycine is likely an inhibitory transmitter in the spinal cord and lower brainstem but not in the cerebral cortex. We detected high-affinity uptake for glycine in the spinal cord but not in the cerebral cortex. We also showed that the accumulated radiolabeled amino acids could be released from brain slices by depolarization in a calcium dependent fashion whereas nontransmitter amino acids were not released in this fashion (Bennett et al., 1972).

Opiate Receptors

In 1970 I was promoted to full professor and given more lab space permitting assumption of additional projects. One of the most exciting events in the neurotransmitter world at that time was the identification in several laboratories of the nicotinic cholinergic receptor in the electric organ of electric fish utilizing 125I-labeled versions of the remarkably potent and pseudoirreversible alpha-bungarotoxin. A major portion of the success of this heroic opus lay in the fact that up to 20% of the protein of the electric organ of certain fish comprised the cholinergic receptor. By contrast, armchair calculations told us that typical neurotransmitter receptors should only be about one-millionth by weight of the brain. I recall conversations with my friend Leslie Iversen and others in which we concluded that the very success of the cholinergic receptor effort told us that brain receptors would probably never be identified in our lifetime.

At about this time, the news media reported frantically that thousands of American soldiers in Vietnam were heroin addicts. In the United States, New York, and many other major cities were experiencing the worst epidemics of heroin abuse in history. President Nixon declared “war on heroin” and appointed a drug czar, Jerome Jaffe. Jerry had authority to commandeer whatever he needed of the billions of drug abuse dollars in the Defense Department, NIH, and other agencies to solve the problem. Jerry, a Psychiatry Professor at the University of Chicago, was an old friend and called me about the challenges he was facing. Because of government bureaucracy, he had a negligible staff but he did have the authority to “draft” anybody from another government agency. I pointed out that Alan Green, my former medical student, was now a Research Associate at the NIH working with Erminio Costa. Alan had a long-time interest in civic affairs and had even aspired to someday be Senator from Connecticut. Within 24 hours Alan was ensconced with Jerry in a mansion directly opposite the White House and was in charge of all drug abuse research in the United States. Arnie Mandell, then Chair of Psychiatry at University of California/San Diego (UCSD), and I talked about how to ensure that these vast sums of money could in some small way be devoted to quality research. We hatched a proposal to create Drug Abuse Research Centers under the aegis of William (Biff) Bunney, then in charge of the drug abuse effort of NIMH, a division that would subsequently become the National Institute on Drug Abuse. Soon a national competition for such centers was initiated. Johns Hopkins and UCSD were among the recipients.

What was I to do? I didn’t know morphine from marijuana. I had read a paper by Avram Goldstein attempting to label opiate receptors by the binding of radiolabeled levorphanol seeking stereospecific binding. He found such binding but it was only 2% of the total binding and subsequently was shown to involve a lipid, cerebroside sulfate. Had there existed opiate receptors, Goldstein’s experiments wouldn’t have identified them. The specific radioactivity of his levorphanol was so low that he needed to employ high concentrations of the drug that would have greatly exceeded the presumed affinity constant for a potent drug interacting with its receptor. In my application to the NIH for the Center Grant, I had suggested novel binding strategies, but the study section poo-pooed that portion of the application, instead favoring our second proposal to study catecholamines and amphetamines, an area in which I already had ample experience.

At that time the only receptor sites that had been labeled biochemically were those involving peptide hormones such as insulin. Pedro Cuatrecasas had been one of the first to identify insulin receptors by the binding of 125Iinsulin. He had recently joined our Pharmacology Department at Hopkins, and his lab was adjacent to mine. I saw a paper in Science reporting the amino acid sequence of nerve growth factor and showing marked similarities to proinsulin. As I had a new postdoctoral fellow, Shailesh Banerjee, joining the lab, I suggested to Pedro that we collaborate with Shailesh doing the experimental work while Pedro would teach us how to utilize his custommade vacuum-linked filtration manifold and other gimmicks involved in the receptor art. Shailesh soon identified nerve growth factor receptors in sympathetic ganglia (Banerjee et al., 1973). He even succeeded in solubilizing and characterizing purified receptors, a remarkable achievement in those days when few membrane proteins had ever been solubilized in a functional state (Banerjee et al., 1976).

Candace Pert, a graduate student who had been working on high affinity choline uptake, which my postdoc Hank Yamamura had shown to label selectively cholinergic neurons (Yamamura and Snyder, 1972), was getting bored with the project. I suggested that we apply the strategies we had been imbibing from Pedro to a hunt for opiate receptors. The only commercially available radiolabeled opiate was [³H]dihydromorphine. We tried it and found no binding. In retrospect we know that dihydromorphine is light sensitive, and we had failed to turn off the lab lights. Instead, we reasoned that only antagonists would display receptor interactions. Accordingly, I splurged on a custom preparation by New England Nuclear Corporation of [³H]naloxone. Within a week Candace had identified receptor binding in the brain and the guinea pig intestine (Pert and Snyder, 1973). The binding was robust with specific binding exceeding nonspecific blank levels by several fold enabling us to characterize rapidly many properties of the receptor. My technician Adele Snowman (who continues as a lab manager for me today) had gifted hands and soon could conduct 500 receptor assays in a day. Lars Terenius at the University of Uppsala (Terenius, 1973) and Eric Simon (Simon et al., 1973) at New York University also detected opiate binding to brain membranes. Details of the opiate receptor story are described in a book I authored Brainstorming (Snyder, 1989).

We were able to answer all sorts of questions in short order. Neither codeine nor heroin bound to opiate receptors, because the phenolic hydroxyl of morphine, which must be unsubstituted to bind receptors, is methylated and acetylated respectively in codeine and heroin. This fit with the pharmacologic actions of these drugs. Thus, codeine (O-methyl-morphine) is slow in onset, because it must first be demethylated in the liver to enter the brain as morphine. Heroin is diacetyl-morphine. The acetyl groups permit far more rapid penetration into the brain than is the case for morphine. Within the brain, the acetyl group connected to the benzene ring rapidly falls off in a nonenzymatic fashion. Because heroin “rushes” into the brain far more rapidly than morphine, it is a more pronounced euphoriant.

In collaboration with Michael Kuhar, my first graduate student but by this time a faculty member, we dissected many small areas of the monkey brain. We unearthed dramatic differences in densities of opiate receptors that could explain diverse pharmacologic effects (Kuhar et al., 1973). Thus, discrete portions of the thalamus, involved in mediating the deep, achy pain that is relieved by morphine, were enriched with receptors, whereas thalamic regions mediating pin-prick sensations were not. Numerous areas of the limbic system were loaded with receptors, which could readily explain the euphoric actions of the drugs. Midbrain nuclei that regulate pupillary diameter had high densities of receptors that can account for the pinpoint pupils of opiate addicts.

One important question that eluded our initial studies had to do with the differentiation of agonists and antagonists. Minor variations, such as changing an N-methyl to an N-allyl group, transformed morphine into the antagonist nalorphine. Of particular interest were the mixed agonist–antagonists that offered promise as less addicting analgesics but that were not readily detected by conventional tests in intact animals. In our initial experiments matched agonists and antagonists displayed identical affinities and displacement curve slopes. A breakthrough came when we were studying the effects of ions. Gavril Pasternak, an M.D./Ph.D. student, found that sodium decreased receptor binding, while Candace said that it increased or didn’t affect binding. Adele Snowman agreed to conduct experiments to resolve this dispute. The answer is that both were right. Gavril was working with the agonist dihydromorphine while Candace was using as a ligand the antagonist naloxone. We quickly developed a means of screening large numbers of drugs for the “sodium effect” by measuring their potencies for inhibiting [³H]naloxone binding in the presence or absence of sodium. Agonists became up to 40 times less potent in the presence of sodium, while pure antagonists were unaffected and the mixed agonist–antagonists behaved in an intermediate fashion.

To this day we don’t know exactly what the “sodium effect” represents. It clearly was telling us that in our ligand binding experiments we were not only monitoring the recognition site for the drug but also mechanisms, which we now know to involve G proteins, that linked receptors to second messenger systems inside the cell. By its effects on G proteins, guanosine 5'-triphosphate (GTP) similarly differentiates agonists and antagonists, while sodium and GTP synergize in this action.

Man was not born with morphine in him. Why do we have opiate receptors? Might there be an endogenous opiate-like substance, a pain/affect regulating neurotransmitter? In our lab Gavril Pasternak discovered an activity in protein-free brain extracts that competed for the binding of [³H]naloxone to receptors and whose density varied markedly throughout the brain in parallel with variations in opiate receptor concentration (Pasternak et al., 1975). This ensured that we were not dealing with some nonspecific inhibitory substance. In Aberdeen, Scotland, John Hughes and Hans Kosterlitz demonstrated in brain extracts a substance that mimicked morphine’s inhibition of electrically induced contractions of the mouse vas deferens and whose effects were blocked by naloxone (Hughes, 1975). Both labs proceeded to purify the substance. Gavril finished his thesis work and returned to the clinic, while an Israeli postdoctoral fellow, Rabi Simantov, took up the challenge of purifying the active ingredient. In 6 months he had what appeared to be a single small peptide and had done some sequencing when Hughes and Kosterlitz reported their isolation and sequencing of the two enkephalin peptides, which differed only in the C terminal amino acid, leucine for one and methionine for the other (Hughes et al., 1975). Rabi completed the sequencing of the same two peptides about 4 weeks later (Simantov and Snyder, 1976).

Characterizing the disposition of the enkephalins proceeded with extraordinary speed. With antibodies raised against the enkephalins, Rabi mapped their localization at a microscopic level (Simantov et al., 1977). At about the same time Mike Kuhar had developed autoradiographic techniques enabling him to map the localization of opiate receptor microscopically (Pert et al., 1976). The two maps coincided with considerable precision. This provided the most compelling evidence that the enkephalins were indeed the physiologic neurotransmitters for the opiate receptors. This conclusion was of importance, as numerous other larger peptides that incorporated the enkephalin sequence were being identified about this time; but, in general, these had somewhat different localizations. With the appreciation of multiple subtypes of opiate receptors whose localizations more or less matched those of different opioid peptides, the situation became somewhat muddy.

Other Receptors

The New England Nuclear Company made large sums of money marketing tritiated versions of various opiates. Accordingly, they were willing to provide complimentary radiolabeled versions of any drug I might suggest as a potential tool to identify neurotransmitter receptors. One of the first was [³H]strychnine as a ligand for glycine receptors, because strychnine was well known to block the synaptic actions of glycine. My M.D./Ph.D. student Anne Young initiated this effort, which presented far greater challenges than the opiate receptor work. For a long period of time she could not identify receptor binding. We subsequently appreciated that though strychnine had high affinity for the glycine receptor, it dissociated very rapidly from the receptor. Its high affinity reflected a correspondingly rapid association rate. After overcoming these technical hurdles, Anne characterized the receptor (Young and Snyder, 1973) and uncovered an important physiologic correlate (Young and Snyder, 1974). Glycine exerts its inhibitory synaptic effects by opening chloride ion channels. Neurophysiologists had established the relative potencies of various anions in permeating the glycine-associated chloride channel. Anne observed inhibition of strychnine binding by chloride and by other anions in proportion to their ability to pass through the channel. Thus, as with the opiate receptor, ligand binding was being modulated by a second messenger system, in this case the associated ion channel.

Rapid dissociation popped up again in Anne Young’s second project, a search for the benzodiazepine receptor. Valium (diazepam) was then the best-selling drug on earth. No one had any idea just what sort of neurotransmitter it was mimicking or blocking so that speculation was rampant that there might exist an “endogenous Valium” comparable to the enkephalins. In her first experiments examining the binding of [³H]diazepam Anne saw robust, saturable binding with some indications of drug specificity. However, try as she might, using all the tricks of the trade she had employed with strychnine, she could not obtain reproducible enough binding to complete the study. Moreover, it was time for her to return to her clinical training so the project was dropped. Subsequently two European groups led respectively by Hans Mohler and Claus Braestrup obtained saturable binding of [³H]diazepam and elegantly characterized the receptors. They succeeded simply by conducting the binding experiments at low temperatures to slow down dissociation, whereas Anne had restricted herself to 37°. As for the endogenous ligand, John Tallman at the NIH subsequently showed that the benzodiazepine receptor is simply an allosteric site on GABA-A receptors.

Hank Yamamura, a postdoctoral fellow, joined our lab to identify muscarinic cholinergic receptors following a semibizarre interaction. Shortly after our initial work on the opiate receptor, I was giving a seminar at Yale and visiting my close friend George Aghajanian. George suggested the muscarinic receptor as a target based on his experiences during military service at Edgewood Arsenal close to Baltimore. Edgewood Arsenal was, in part, devoted to the chemical warfare effort with concerns that the Russians might spray mind-altering drugs over U.S. cities or on our troops in the battlefield. Accordingly, George participated in experiments administrating LSD and related agents to soldier “volunteers.” One of these agents was an extremely potent muscarinic anticholinergic drug, quinuclidinyl benzilate (QNB). He assumed that QNB was still classified and not readily available. I was at that time in the process of recruiting Hank who was doing his military service at Edgewood Arsenal. I phoned Hank and asked what he knew of QNB. After a long pause, he nervously replied, “How did you know about that?” I told him about the conversation with George. A few months later when Hank reported to Hopkins, he brought along a small bottle of QNB. I asked no questions. [³H]QNB labeled muscarinic receptors impeccably with extremely low levels of nonspecific binding (Yamamura and Snyder, 1974). Used by the pharmaceutical industry to screen for drugs with potential anticholinergic side effects, [³H]QNB is likely the most widely and successfully employed neurotransmitter receptor ligand. Muscarinic receptor studies answered some important questions about neuroleptic antipsychotic drug action. As discussed below, neuroleptic drugs elicit antipsychotic actions and Parkinsonian, extrapyramidal side effects by blocking dopamine receptors. Though neuroleptics vary widely in their affinities for dopamine receptors, at therapeutically effective doses they all occupy about 50% of receptor sites. Assuming that receptors mediating therapeutic effects are similar to those mediating extrapyramidal side effects, then at comparable therapeutic doses the incidence of such side effects should be the same for all drugs. Yet we knew that there were major differences. Some drugs, such as clozapine, elicit few such effects, whereas a majority of patients receiving haloperidol suffered these influences. The answer came when we evaluated the affinities of various neuroleptics for muscarinic receptors (Snyder et al., 1974). Since the days of the French neurologist Charcot in the 1870s, antimuscarinic agents had been used to lessen Parkinsonian symptoms. We found that the drugs, such as clozapine, with the least incidence of Parkinsonian side effects displayed the greatest anticholinergic activity. Thus, neuroleptics tend to elicit extrapyramidal side effects by blocking dopamine receptors and relieve the same effects by blocking muscarinic receptors with the ratio of affinities for dopamine and muscarinic receptors determining the incidence of side-effects.

Our initial receptor successes had used radiolabeled antagonists whose dissociation constants for receptor binding were 1 to 5 nanomolar (nM) that seemed to be the affinity range necessary to obtain binding that would be stable enough to withstand the vigorous washing necessary to remove nonspecific binding. We assumed that neurotransmitters themselves, agonists, would have affinities in the micromolar range and so would not be useful ligands. This prejudice was erased when Anne, together with a medical student Steve Zukin, successfully labeled GABA receptors with [³H]GABA (Zukin et al., 1974). This study opened a minor floodgate of new receptor research, as tritiated versions of most neurotransmitters were readily available commercially eliminating the burden of designing novel ligands and enabling our labeling serotonin receptors with [³H]serotonin (Bennett and Snyder, 1976b) and α and β-adrenergic receptors with [³H]norepinephrine or [³H]epinephrine (U’Prichard and Snyder, 1977).

David Burt, a postdoctoral fellow who had just provided our first identification of peptide receptors utilizing [³H]TRH (thyrotropin releasing hormone) (Burt and Snyder, 1975), had some free time and successfully labeled dopamine receptors with [³H]dopamine (Burt et al., 1975). Ian Creese, a new postdoc in the lab, had done his Ph.D. thesis with Susan Iversen characterizing behavioral roles of dopamine and was eager to join the dopamine team. By this time we had obtained [³H]haloperidol to investigate antagonist binding to dopamine receptors (Creese et al., 1975). To our surprise, the drug specificities for dopamine receptors labeled with agonists and antagonists, respectively, were quite different. Most strikingly, butyrophenones, such as haloperidol and spiperone, were extremely potent at sites labeled by [³H]haloperidol but about a thousand-fold weaker at sites labeled with [³H]dopamine. Spiperone was the champion in terms of receptor potency, with a dissociation constant of 0.3 nM. How might we explain this discrepancy? The research showing that sodium differentiates agonists and antagonists at opiate receptors had suggested that opiate receptors exist in distinct, interconvertible conformations respectively preferring agonists and antagonists. Hence, we initially supposed that what we were observing were simply distinct agonist and antagonist preferring conformations of dopamine receptors. Work from numerous labs, especially John Kebabian’s, clarified that we were studying two separate receptor proteins that are now designated D1, for the dopamine preferring form, and D2, for the butyrophenone preferring form.

Identifying dopamine receptors permitted us to test the hypothesis of Arvid Carlsson that antipsychotic neuroleptic drugs act by blocking dopamine receptors. His hypothesis was based on the augmentation of dopamine metabolites in rats treated with neuroleptics. Arvid speculated that neuroleptics block dopamine receptors leading to a feedback causing dopamine neurons to fire more rapidly and generate larger amounts of metabolites. While we were carrying out our initial dopamine receptor studies, Paul Greengard published a paper describing a dopamine-sensitive adenylate cyclase, presumably associated with a dopamine receptor, whose activity was blocked by neuroleptic drugs. Butyrophenones were quite weak as inhibitors of the cyclase, so we presumed that his enzyme activity reflected the receptor sites labeled with [³H]dopamine. Moreover, because butyrophenones are far and away the most potent antipsychotic drugs, these findings suggested that blocking the adenylate cyclase linked dopamine receptors was not the mechanism of antipsychotic drug effects. We examined the relative potencies of an extensive series of drugs in competing for [³H]dopamine and [³H]haloperidol binding sites. The correlation of clinical potencies with affinity for the [³H]haloperidol sites was extraordinarily high, with a correlation coefficient of about 0.9 (Creese et al., 1976). Such a correlation was particularly remarkable considering that the clinical potencies reflected effective doses in human patients, values separated from receptor affinities by drug absorption, metabolism, and penetration into the brain. Yet, over an extensive series of drugs, these factors evidently equalized out. Independently, Philip Seeman in Toronto also labeled dopamine receptors with [³H]haloperidol (Seeman et al., 1975) and observed similar influences of neuroleptic drugs (Seeman et al., 1976).

Dopamine receptors enabled us to characterize dynamic changes in receptor number/sensitivity. Ian had devoted his Ph.D. thesis to selectively lesioning dopamine neurons unilaterally and monitoring the behavioral consequences in terms of circling behavior, reflecting a unilateral loss of the dopamine regulation of motor activity. This process reflected receptor supersensitivity on the lesioned side, as such rotation was elicited by administering dopamine agonist drugs such as apomorphine. One could quantify the extent of receptor supersensitivity simply by monitoring the number of rotations. Following such lesions Ian observed a notable increase in numbers of dopamine receptor binding sites on the lesioned side (Creese et al., 1977). The increased number of receptors correlated closely with the increased rotational behavior in individual rats establishing that increased receptor number accounted for behavioral supersensitivity.

The notion that receptor supersensitivity was determined by altered numbers of receptors enabled us to address the question of tardive dyskinesia. Patients treated for long durations with high doses of neuroleptics develop abnormal movements that can be so severe that they interfere with eating. Clinical features suggested that dopamine receptor supersensitivity was involved. Thus, the abnormal movements resembled the side-effects of high doses of L-dihydroxyphenylalanine (L-DOPA), were worsened when neuroleptic drug administration was stopped, and were improved by increasing the doses of neuroleptics. We created an animal model of tardive dyskinesia by administering neuroleptics for a month or more leading to significant increases in numbers of dopamine receptors that could account for receptor supersensitivity in tardive dyskinesia (Burt et al., 1977).

Receptor research elucidated other side effects of neuroleptics. Thus, David U’Prichard, Steve Peroutka, and David Greenberg showed that the sedating effects of neuroleptics correlate well with their blockade of alphaadrenergic receptors (U’Prichard et al., 1978). For many years thereafter, we didn’t work much on neuroleptics. Recently, the psychiatric community has been distressed by the sometimes massive weight gain caused by atypical neuroleptics such as olanzapine (Zyprexa) and clozapine. Sangwon Kim, a postdoctoral fellow, discovered that these drugs very potently stimulate hypothalamic adenosine monophosphate (AMP) kinase, an enzyme that regulates the body’s response to altered energy states (Kim et al., 2007). Thus, when energy consumption depletes adenosine triphosphate (ATP), AMP levels are elevated to activate AMP kinase. In supraoptic and paraventricular nuclei of the hypothalamus, which are eating centers, leptin that decreases eating behavior, depresses AMP activity, while orexigenic agents stimulate AMP kinase. Orexigenic neuroleptics very potently activate hypothalamic AMP kinase, whereas those that don’t increase appetite are without effect. I was puzzled by the extraordinary potency of these drugs in stimulating enzyme activity, something one rarely sees with enzymes. I wondered whether the effects on AMP kinase might be secondary to blockade of some receptor, as nanomolar effects of receptor antagonists are commonplace. Sangwon showed that the orexigenic neuroleptics are extremely potent inhibitors of histamine H1 receptors whose blockade increases AMP kinase activity. All of this made good sense as there was already a substantial literature about the importance of neuronal histamine in regulation of hypothalamic eating centers. These findings may provide a way to develop safer, more effective neuroleptics.

Definitive evidence that binding sites we were labeling with agonists and antagonists reflected two different receptors came from experiments of Steve Peroutka and David Greenberg, M.D./Ph.D. students, and David U’Prichard, a postdoctoral fellow, investigating alpha-adrenergic receptors. We could label these sites with an alpha antagonist [³H]WB4101, agonists such as [³H]epinephrine, [³H]norepinephrine, [³H]clonidine or the ergot derivative [³H]dihydroergokryptine, a mixed agonist-antagonist (Peroutka et al., 1978). Numbers of agonist and antagonist labeled sites differed markedly in various brain regions. Moreover, we could abolish binding of [³H]antagonists with unlabeled antagonists while completely preserving [³H]agonist binding and vice versa. These and other experimental results provided compelling evidence that we were labeling two distinct alpha-adrenergic receptors which are now designated alpha1 for the antagonist-preferring sites and alpha2 for the agonist-preferring ones.

Discrimination of two distinct receptors with different physiologic functions came with Steve’s elegant studies of serotonin receptors (Peroutka et al., 1981). These could be labeled with [³H]serotonin, [³H]LSD, a mixed agonist–antagonist, or [³H]spiperone, an antagonist. Interestingly, in cerebral cortical membranes we could label serotonin receptors exclusively with [³H]spiperone, while in the corpus striatum the same ligand labeled only dopamine receptors. Steve monitored the behavioral “serotonin syndrome” in rats and its blockade by various drugs. Drug potencies in blocking the serotonin syndrome closely paralleled their potencies at the [³H]spiperone sites which we designated serotonin-2 (5-HT-2) receptors. Regulation of [³H]serotonin binding by GTP and other properties suggested that these sites that we designated 5HT1 receptors, reflected the known serotoninstimulated adenylate cyclase. We now know of about 12 distinct serotonin receptor subtypes whose differentiation has led to important new drug classes such as the antimigraine triptans and numerous atypical neuroleptics.

Receptor studies that most “turned me on” were those that might explain the therapeutic actions of drugs and/or were decidedly atypical. For instance, Fred Bruns, a postdoctoral fellow, in collaboration with John Daly at the NIH, identified two populations of adenosine receptors labeled with agonists and antagonists, respectively (Bruns et al., 1980). Adenosine was well known to be generated in large amounts from ATP during hypoxia. No one had ever considered a role for adenosine as a potential neurotransmitter in the brain. Karen Braas, a postdoctoral fellow, immunohistochemically mapped adenosine to populations of large neuronal cells with relatively few adenosine containing nerve terminals (Braas et al., 1986). Ted Rall at the University of Virginia had monitored adenosine effects on cyclic AMP and reported blockade by caffeine (Sattin and Rall, 1970), and John Daly had characterized such effects in considerable detail (Smellie et al., 1979). At that time pharmacology textbooks attributed the stimulant effects of caffeine to inhibition of phosphodiesterase, but such effects required concentrations 100 times higher than those that occur in the brain following coffee ingestion. Jefferson Katims, a student working in the lab while applying to medical school, monitored the relative stimulant effects of a variety of methylxanthines and compared their behavioral potencies to affinities for adenosine receptors. There was a close correlation with the adenosine receptors labeled by a xanthine derivative and which we designated “A2” (Snyder et al., 1981). Numerous studies had shown that caffeine facilitates psychomotor performance so that derivatives lacking the cardiac effects of the drug might be useful therapeutic agents. Accordingly, we carried out structureactivity analysis leading to xanthine derivatives 100,000 times more potent than caffeine in blocking adenosine receptors (Bruns et al., 1983). It is now accepted that the stimulant effects of caffeine derive from blockade of adenosine receptors. It is interesting that it took so many years to come up with a mechanism of action for the most widely ingested psychoactive agent in the world.

In terms of atypical receptors, we had much fun seeking odorant receptors and coming up with the odorant binding protein. The project arose as a product of a dinner hosted by the Neuroscience Research Program. My dinner partner was Hank Walters, CEO of International Flavors and Fragrances (IFF) the largest manufacturer of odorants and a devotee of neuroscience. He commented, “Sol, all the receptors you guys study in the brain aren’t nearly as sensitive as those in my dog’s nose. Why isn’t anybody looking for odorant receptors?” I explained that the NIH focuses on major diseases, whereas nobody ever died because he or she can’t smell. Hank retorted, “I’ll put my money where my nose is.” For the next 10 years he supported our laboratory generously to study olfaction. To seek odorant receptors, IFF prepared for us a series of tritiated odorants. I asked a newly arrived graduate student, Jonathan Pevsner, to work on the project, which turned out to be fortuitous, because, unbeknown to me, Jonathan since birth had been totally anosmic, unable to smell, a secret he had hid from everyone including his parents. Jonathan did discover high affinity binding of [³H]odorants to olfactory tissue with no such binding evident in any other organ (Pevsner et al., 1985). Further investigation revealed that we weren’t dealing with physiologic odorant receptors, as the binding involved a small soluble protein, which Jonathan purified and cloned with the help of Randy Reed, a molecular biologist (the first foray of our laboratory into molecular biology) (Pevsner et al., 1988b). The odorant binding protein (OBP) bound a wide range of odorants of greatly varying structure. We showed that it is made in the lateral nasal gland whose secretions are dispersed from the nose to the outside world in an atomizer-like spray. Jonathan developed evidence that the function of OBP is to collect odorants in the ambient air and whisk them back to the odorant receptors in the back part of the nose (Pevsner et al., 1988a). Many years later Linda Buck, in her Nobel Prize oration described how reading our papers on OBP motivated her successful quest for the true odorant receptors.

Peptide Research

The identification of the enkephalins led to an explosion of research characterizing numerous peptides as putative neurotransmitters. The emergence of immunohistochemistry of peptides in the brain, led notably by the efforts of Tomas Hokfelt, showed distinct neuronal pathways for individual neuropeptides. For instance, substance P, recently isolated by Susan Leeman, was highly localized to unmyelinated sensory nerve fibers suggesting a role in pain perception. We investigated a number of neuropeptides (Snyder, 1980). Bob Innis, an M.D./Ph.D. student, mapped cholecystokinin (CCK) neurons in the brain (Innis et al., 1979). He also characterized CCK receptors demonstrating two distinct subtypes, which subsequently have had important pharmacologic and therapeutic relevance (Innis and Snyder, 1980). Another M.D./Ph.D. student, George Uhl, identified neurotensin receptors (Uhl et al., 1977a) and mapped novel neurotensin pathways in the brain (Uhl et al., 1977b). Jim Bennett characterized angiotensin receptors (Bennett and Snyder, 1976a).

Bob Innis and Don Manning, a graduate student who subsequently also earned a Hopkins M.D. degree, identified receptors for bradykinin, not known primarily as a neurotransmitter but rather as a presumed inflammatory mediator (Innis et al., 1981). Working together with Larry Steranka at the Nova Pharmaceutical Company, Don localized bradykinin receptors to the terminals of sensory neurons and demonstrated analgesic actions of bradykinin-blocking drugs (Steranka et al., 1988). This spawned major efforts in the pharmaceutical industry to develop therapeutically useful bradykinin antagonists.

Ken Murphy, an M.D./Ph.D. student, and Robert Gould, a postdoctoral fellow, characterized receptors for the dihydropyridine calcium antagonist drugs employing [³H]nitrendipine. As with the glycine receptor, they were able to identify linkages of the drug recognition site to the physiologic calcium channel, as [³H]nitrendipine binding was absolutely dependent on the presence of calcium, stimulated by cations that mimic calcium and inhibited by cations that block calcium channels (Gould et al., 1982).

Other atypical receptors included those for neurotransmitter transporters that several labs, including our own, labeled with [³H]antidepressants. Chi-Ming Lee, a postdoctoral fellow, identified norepinephrine transporters with [³H]desipramine (Lee and Snyder, 1981). A fascinating adventure labeling transporters and enzymes involved the neurotoxin 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP). In the early 1980s MPTP attracted attention when it was shown to be a contaminant of crude synthetic opiates that elicited devastating Parkinson’s disease in young drug users. Others had shown that monoamine oxidase converted MPTP to 1-methyl-4-phenylpyridinium (MPP)+ which in animals models appeared to be the active ingredient in destroying dopamine neurons. Mysteriously, MPTP/MPP+ in rather low doses selectively destroyed only dopamine neurons. Jonathan Javitch, an M.D./Ph.D. student, attacked this problem by monitoring high-affinity binding of [³H]MPTP that appeared to label monoamine oxidase-B (Javitch et al., 1984). This afforded a means of studying the MPTP–MPP+ conversion but didn’t explain why dopamine neurons were selectively damaged. Using preparations of monoamine oxidase, Jonathan synthesized [³H]MPP+ and discovered that it mimicked dopamine at transporter sites and could explain the unique dopamine-specific toxicity of MPTP (Javitch et al., 1985). Jonathan showed that MPP+ is concentrated in dopamine neurons several thousand fold over the external media. At these high concentrations, MPP+, a free radical, simply burned out dopamine nerve terminals. But this didn’t account for the long-term destruction of dopamine cell bodies. Another M.D./Ph.D. student, Bob D’Amato, discovered that MPP+ binds to neuromelanin with high affinity. Thus, the neuromelanin that is greatly enriched in dopamine cells serves as a depot for MPP+, releasing it continuously until it destroys the cells. Proof that neuromelanin binding of MPP+ mediates neurotoxicity came from Bob’s experiments with the antimalarial drug chloroquine (D’Amato et al., 1987). Bob discovered that chloroquine, which has high affinity for melanin, blocked MPP+ binding to neuromelanin binding and, in monkeys treated with MPTP, protected them from dopamine neuronal destruction and Parkinsonian motor abnormalities.

Inositol Phosphates

In the mid-1980s inositol 1,4,5-trisphosphate (IP3) was identified as a major second messenger generated by neurotransmitter-hormone stimulation of phospholipase C and that released intracellular calcium. It was assumed that inside cells small sacs of endoplasmic reticulum loaded with calcium possessed sites on their surface that responded to IP3. Efforts by other labs to identify IP3 receptors by ligand binding revealed only small amounts of saturable binding that might be associated with receptors. To identify an enriched source, Jay Baraban, a psychiatrist, and Paul Worley, a neurologist, both doing postdoctoral training in our lab, took advantage of our facilities for radioligand autoradiography. They found enormous amounts of [³H]IP3 binding sites in the cerebellum, virtually exclusively associated with Purkinje cells (Worley et al., 1987a). Cerebellar membranes provided an abundant source for characterizing the receptor. One of the earliest observations was that modest increases of calcium above physiologic intracellular levels led to inhibition of the receptor, which is now appreciated as a major regulatory mechanism (Worley et al., 1987b). An M.D./Ph.D. student, Surachai Supattapone, successfully solubilized IP3 receptors and was able to purify them to homogeneity (Supattapone et al., 1988). This enabled us to address a major question, did the IP3 binding protein we had isolated represent only the IP3 recognition apparatus or did this single protein also contain the relevant calcium ion channel? We approached this question by collaborating with Rick Huganir, who, as a Ph.D. student with Ephraim Racker, had reconstituted the acetylcholine receptor into lipid vesicles loaded with radioactive sodium and demonstrated that the isolated receptor included a sodium channel. Chris Ferris, an M.D./Ph.D. student, carried out the studies reconstituting IP3 receptor protein into lipid vesicles loaded with radioactive calcium (Ferris et al., 1989). IP3 released calcium from the vesicles with an inositol phosphate specificity identical to that of IP3 binding sites. Chris was able to use the reconstituted receptors to learn a great deal about their regulation. For instance, he demonstrated a potent activation of calcium release by low concentrations of ATP that diminished as ATP was increased to physiologic levels (Ferris et al., 1990). This may provide a physiologic mechanism to regulate calcium release coincident with the filling of calcium stores by the calcium activated ATPase pump. He also showed that IP3 receptors are regulated by phosphorylation via numerous kinases and that the receptor autophosphorylates (Ferris et al., 1992).

Upon reading our papers on IP3 receptors, Katzuhiko Mikoshiba realized that the IP3 receptor might be identical to a protein he had purified years ago when he was working as a postdoctoral fellow with Jean-Pierre Changeux in Paris and discovered a cerebellar/Purkinje cell enriched protein which he was now cloning. The cloned IP3 receptor turned out to be a very large protein with a small IP3 recognition site at the N-terminus and a small calcium channel domain at the C-terminus with more than 1,000 amino acids of unknown function in the intervening area (Furuichi et al., 1989). In recent years, Randen Patterson and Damian van Rossum, postdoctoral fellows in our lab, utilizing yeast two hybrid methodology, discovered other proteins that bind IP3 receptors such as RACK1 (Patterson et al., 2004) and DANGER (van Rossum et al., 2006). A postdoctoral fellow, Darren Boehning, together with Randen and Damian, identified cytochrome C as an IP3 receptor binding protein (Boehning et al., 2003a, 2003b). Darren showed how this interaction mediates calcium-dependent apoptosis. There is a vast body of literature indicating an important role for calcium release in apoptotic cell death thought largely to be mediated by calcium-dependent proteases. There was a separate large literature on cytochrome C being released from mitochondria by apoptotic processes. Because IP3 mediated calcium release takes place in the endoplasmic reticulum and cytochrome C functions in mitochondria, no one had ever linked the two systems. Darren discovered that as little as 1 nM cytochrome C blocks the feedback system whereby released calcium inhibits further release from IP3 receptors. Other workers had established that the external membranes of mitochondria are closely juxtaposed to endoplasmic reticulum. Darren showed that cytochrome C, released from mitochondria, enters the endoplasmic reticulum to block the calcium inhibitory feedback so that larger amounts of calcium are released from the endoplasmic reticulum to enter mitochondria and trigger further release of cytochrome C in a feed-forward vicious cycle that is amplified throughout the cell to initiate apoptosis.

Concentrations of IP3 are only 1 μM, while substantially higher levels of other inositol phosphates exist in most tissues. For instance, levels of IP6 can be 100 times greater than those of IP3. As inositol has only six hydroxyl groups, most people assumed that IP6 would be the “highest” inositol phosphate. Accordingly, I was amazed to read papers by Steven Shears at the National Institute of Environmental Sciences (NIH) in North Carolina and Len Stephens in England identifying IP7 and IP8 in which certain hydroxyls of the inositol ring contained two attached phosphates, forming inositol pyrophosphates. I wondered whether these energetic groups might carry out functions similar to the pyrophosphates of ATP, such as phosphorylating proteins. It was clear that the only way to make progress in this field would be to find the biosynthetic enzymes. Susan Voglmaier, an M.D./Ph.D. student, embarked on what she assumed would be a project of a few months, purifying and then cloning IP6 kinase. The protein turned out to be extraordinarily labile and nonabundant. After three years full of frustration she purified to homogeneity IP6 kinase (Voglmaier et al., 1996) and then returned to the clinics. A new postdoctoral fellow, Adolfo Saiardi, prepared large batches of IP6 kinase enabling him to obtain partial amino acid sequence and clone what turned out to be a family of related enzymes (Saiardi et al., 1999). He discovered three IP6 kinases and a fourth enzyme that could phosphorylate multiple inositol phosphates so that we called it inositol polyphosphate multikinase (IPMK). In what turned out to be an extraordinarily arduous undertaking, Adolfo successfully employed IP6 kinase to manufacture [³²P]IP7 and demonstrated that it phosphorylates proteins to a similar extent as ATP with almost as many targets (Saiardi et al., 2004). Phosphorylation by IP7 is nonenzymatic even though it displays many of the same properties as ATP phosphorylation, such as requiring magnesium. In this way it resembles other nonenzymatic post-translational modifications such as S-nitrosylation by nitric oxide. Why should the body utilize a second mode of protein phosphorylation when ATP phosphorylation was doing quite well? The answer came in experiments of Rashna Bhandari, a postdoctoral fellow, who demonstrated that IP7 doesn’t simply phosphorylate proteins, it pyrophosphorylates them (Bhandari et al., 2007). Although the IP7 mediated pyrophosphorylation is more labile to chemical insults than ATP phosphorylation, it resists the many phosphatases that degrade ATP-phosphorylation. Hence, in intact organisms IP7 pyrophosphorylation may be more stable.

What might be the physiologic role of this pyrophosphorylation of proteins? We attacked this question in yeast with deletion of IP6 kinase. Vesicular endocytosis is markedly distorted in yeast lacking IP6 kinase (Saiardi et al., 2002), and ribosomal function is aberrant (Saiardi et al., 2000). These findings fit nicely with evidence that the best substrates for IP7 pyrophosphorylation are ribosome-associated proteins and clathrinrelated proteins involved in vesicular endocytosis.

Inositol pyrophosphates play a role in cell death. Robert Luo and Anutosh Chakbraborty, postdoctoral fellows in the lab, have provided insight into this arena. Daniel Lindner at the Cleveland Clinic had screened the effect of antisense libraries on cell death of ovarian carcinoma cells seeking new apoptotic molecules. He uncovered IP6 kinase-II (Morrison et al., 2001), one of the enzymes that Adolfo had cloned. Robert Luo and Eiichiro Nagata, postdoctoral fellows in our lab, established that IP6 kinase-II selectively mediates cell death, as antisense to this enzyme but not to its two isoforms prevents apoptosis in multiple cell lines (Nagata et al., 2005). Anutosh Chakraborty, a more recent postdoctoral fellow, has shown how the system works (Chakraborty et al., 2008). Under basal conditions, IP6 kinase-II is maintained in the cytoplasm bound to the heat shock protein HSP-90 that sequesters IP6 kinase-II in an inactive form. Apoptotic stimuli block the binding of the two proteins with IP6 kinase-II translocating to the nucleus and killing cells. Anticancer drugs such as cisplatin, at therapeutic concentrations, block the binding, and lose their apoptotic effects when IP6 kinaseII is depleted from cells. Hence, the anticancer effects of such drugs may reflect inhibition of IP kinase II-HSP 90 binding more than deoxyribonucleic acid (DNA) damage. Selective inhibitors of the binding may afford less toxic anticancer drugs.

IPMK is the principal enzyme generating IP5 in cells. Adam Resnick, a graduate student, together with Adolfo Saiardi, discovered a novel function for IPMK, as a phosphoinositide-3-kinase (PI-3-kinase) (Resnick et al., 2005). PI-3-kinase had been discovered in the early 1990s by Lewis Cantley as an enzyme that adds a phosphate to the #3 position of phospholipids generating phosphatidylinositol(3,4,5)-trisphosphate (PIP3). PIP3 in turn activates the kinase Akt that stimulates protein synthesis and elicits other anti-apoptotic effects. Only a single PI-3-kinase was thought to exist, but IPMK is just as robust in mediating this function as the classic enzyme. The relative roles of the two enzymes are a hot area of inquiry in our lab these days.

Immunophilins

Why should a psychiatrist explore the immune system? Immunophilins are a family of proteins discovered as receptors for the classic immunosuppressant drugs that have made organ transplantation possible. The cyclophilins were identified as small soluble proteins that bound the first important immunosuppressant drug cyclosporin. The other prominent immunosuppressant, FK506, binds to a group of proteins called FK506 binding proteins (FKBPs). Although I knew nothing about immunosuppressants, I was entranced by the publication in Nature reporting the isolation of the first and most prominent FKBP, a 12 kilodalton protein designated FKBP-12, which bound [³H]FK-506. Since the early days of receptor binding, I had remained a consultant to New England Nuclear and thought that [³H]FK-506 would be a splendid addition to their catalog. The company asked me to test whether the product they manufactured was biologically active. Besides checking out conventional immune tissues such as lymphocytes, I asked my new postdoctoral fellow Joe Steiner to screen a wide range of tissues—for good measure. He was amazed to find massive levels of binding in the brain, about 50 to 100 times greater than immune tissues (Steiner et al., 1992). Together with Ted Dawson, a neurologist doing postdoctoral training in our lab, he noted an association of the binding sites with growth cones and other sites relevant to nerve growth. Ted and his wife Valina, along with a graduate student Ernie Lyons, examined influences of FK-506 upon the extension of nerve processes from the neuronal-like PC12 cell line (Lyons et al., 1994). FK-506 stimulated neurite extension from these cells and was even more potent in enhancing the outgrowth of neuronal processes from sympathetic ganglia, with effects in the low nanomolar range. In intact animals FK-506 enhanced the regrowth of damaged facial and sciatic nerves. Most impressive was the ability of the drug to restore dopamine neurons following treatment with the neurotoxin MPTP. FK-506 was neurotrophic and neuroprotective, preventing the loss of dopamine neurons if administered prior to MPTP.

The obvious therapeutic potential of such drug actions was somewhat muted by concerns about administering immunosuppressant drugs to neurologic patients. Immunosuppressant actions of cyclosporin and FK-506 involve the following mechanism. The drug-immunophilin complex binds to the calcium-activated phosphatase calcineurin inhibiting it and preventing the nuclear translocation of the transcription factor NFAT which normally turns on interleukin-2 synthesis in the nucleus. Certain drugs could bind to immunophilins but, for some unknown reason, the drug-immunophilin complex failed to interact with calcineurin so that these agents were not immunosuppressants. We found that nonimmunosuppressant derivatives of FK-506 and cyclosporin were just as neurotrophic/neuroprotective as the immunosuppressant derivatives (Steiner et al., 1997). Johns Hopkins licensed its patents on these discoveries to Guilford Pharmaceuticals, a neuroscience-biotech company I had cofounded. Guilford chemists were able to fabricate derivatives of FK-506 which were much smaller and more “drug-like” yet quite potent in neurotrophic/neuroprotective animal models. In monkeys with MPTP-induced Parkinsonism, regrowth of dopamine neurons and clinical improvement with these drugs were dazzling.

The third classic immunosuppressant drug, rapamycin, acts somewhat differently than the first two. It binds with extremely high affinity to FKBP-12. However, the drug-immunophilin complex does not bind to calcineurin. In a search for a “target of rapamycin,” my M.D./Ph.D. student David Sabatini discovered a large protein that binds to the rapamycin/FKBP-12 complex which he purified, cloned and designated RAFT (Rapamycin and FKBP-12 Target) (Sabatini et al., 1994). Independently, two other groups identified this protein which is now designated mTOR (Mammalian Target of Rapamycin). mTOR has become one of the hottest areas of molecular biologic research as it transmits information about amino acid availability to the protein synthetic machinery. We have recently developed new insights into how the system senses amino acids with a key component being our friend from the inositol phosphate world, IPMK. IPMK was identified in yeast some 20 years ago as a gene whose deletion alters the influence of amino acids, especially arginine, upon yeast. David Maag, a postdoctoral fellow, has found that deleting the gene for IPMK impairs mTOR responses to altered nutrient status. This signaling cascade involves the binding of IPMK to Akt which in turn signals to mTOR.

Our separate efforts on immunophilins and IP3 receptors converged when Andy Cameron, an M.D.-Ph.D. student discovered that IP3 receptors bind FKBP12 that regulates the receptor’s calcium flux (Cameron et al., 1995).

Gases as Neurotransmitters

In the mid-late 1980s ligand binding to neurotransmitter receptors was becoming a “mature” field. Subtleties of drug actions at subtypes of receptors was of interest and being exploited by the drug industry for novel therapeutic agents, but many of the big questions had already been answered. There was fun in applying ligand binding to novel targets such as the IP3 receptor and odorant binding proteins, but I was ready for new challenges. I read a magnificent paper in Nature by Salvador Moncada identifying the gas nitric oxide (NO) as endothelial derived relaxing factor (EDRF). I had vaguely heard of EDRF and was fascinated that such a strange molecule as NO, a noxious free radical, should turn out to have a biological function. There were even hints, from a publication by John Garthwaite, that an NO-like substance is formed in the brain. I discussed all of this with a new M.D./Ph.D. student in the lab, David Bredt. We decided to seek a brain function for NO. It was already known that NO relaxes blood vessels by stimulating guanylyl cyclase to form cyclic guanosine monophosphate (cGMP). In the brain glutamate, acting through N-methyl-D-aspartate (NMDA) receptors, stimulates cGMP formation in the cerebellum. Arginine derivatives, such as N-methylarginine, which block the conversion of arginine to NO, were readily available. David soon established that the stimulation by glutamate of cGMP in the brain could be blocked by N-methylarginine (Bredt and Snyder, 1989), findings obtained independently by Moncada and Garthwaite (Garthwaite et al., 1989). This convinced us that NO was worth exploring as a potential neurotransmitter.

The only way to really understand NO functions would be to find the enzyme that generates it. Numerous groups had tried to purify the putative NO synthase (NOS), which would convert arginine to NO, but the enzyme seemed to be terribly labile. In his initial efforts, David also found a total loss of enzyme activity whenever he poured brain extracts over a column. He couldn’t believe that any protein could be so incredibly labile and suspected that the column purification was separating out some cofactor Recombining fractions restored enzyme activity, supporting this notion. Based on hints in the literature that calcium was involved in NO formation, he tried adding calmodulin back to extracts and obtained total restoration of enzyme activity (Bredt and Snyder, 1990). If NO were a neurotransmitter, calcium–calmodulin activation would make sense. Classic neurotransmitters are stored in synaptic vesicles with large storage pools of excess vesicles available for release upon neuronal depolarization. A gas can’t be stored in vesicles. Accordingly, each successive nerve impulse must regenerate NO. Neuronal depolarization leads to calcium influx which can activate calmodulin and NOS.

In short order David purified NOS to homogeneity and then cloned the relevant gene (Bredt et al., 1991). It turned out that there are three forms of NOS. The first that we cloned is the neuronal form, nNOS, whereas the blood vessels have a distinct form, endothelial NOS (eNOS), and all tissues, especially those involved in inflammation, possess an inducible form, inducible NOS (iNOS). Charlie Lowenstein, a cardiologist working in our lab, collaborated with David to clone iNOS (Lowenstein, Glatt, Bredt, Snyder, 1992), while other labs, using our nNOS sequence as a template, also cloned iNOS and identified eNOS.

With the purified enzyme protein, David raised antibodies and demonstrated strikingly selective neuronal localizations throughout the brain and the peripheral nervous system (Bredt et al., 1990). The autonomic nervous system proved far more useful than the brain for establishing neurotransmitter function. Thus, David found nNOS highly localized to the innervation of the penis. We collaborated with Arthur (Bud) Burnett in the Hopkins Urology Department showing that penile erection elicited by nerve stimulation was abolished by NOS inhibitors (Burnett et al., 1992). These findings established that NO is the neurotransmitter of penile erection. Utilizing similar techniques, several laboratories established that NO is a transmitter of nonadrenergic, noncholinergic transmission in the gut.

Years later we learned that our work on NO and penile erection affected the development of an important clinical drug. At the press conference launching Viagra (sildenafil), the research director of Pfizer explained that sildenafil is an inhibitor of phosphodiesterase-5, which elevates levels of cyclic GMP that then relaxes smooth muscle. Pfizer sought a drug to relax coronary arteries for use in angina but the drug failed in clinical trials. Moreover, it elicited a peculiar side effect, unwanted penile erections. Sildenafil was thus buried until Pfizer scientists read our 1992 Science paper on NO and penile erection and decided to conduct clinical trials in erectile dysfunction. Although Johns Hopkins had filed for patent protection covering NO and penile erection, the patents didn’t extend to cyclic GMP—so it goes.

Abundant literature indicates that vascular stroke damage stems in large part from a massive release of glutamate from stressed glia with the glutamate overactivating NMDA receptors to cause neuronal damage. NMDA neurotoxicity is readily demonstrable in brain cultures. Moreover, NMDA antagonists markedly reduce stroke damage. We wondered whether NO might mediate the neurotoxic actions of NMDA receptor activation. Ted and Valina Dawson, together with David, showed that NMDA neurotoxicity is greatly reduced by NOS inhibitors (Dawson et al., 1991). Others showed that such drugs prevent stroke damage.

To seek additional functions of neural NO, we collaborated with Paul Huang and Mark Fishman at Massachusetts General Hospital in generating nNOS knock-out mice (Huang et al., 1993). Initially, we were distressed at the absence of any obvious phenotype. Then, Ted noticed that in the cages housing male nNOS knock-outs and wild-type littermates, he often found dead mice, invariably the wild-type animals, who displayed all manner of scars and torn hair. To investigate further, we collaborated with Randy Nelson in the Psychology Department. Randy demonstrated an incredible increase in aggressive behavior in the nNOS deleted mice (Nelson et al., 1995). Within seconds of placement together of a male nNOS knock-out and a wild-type animal, the knock-out would attack and often kill his cage partner. Increased aggressive behavior in some gene knock-out mice had been previously described, but nothing remotely approaching this level of violent behavior had ever been seen previously in mice, at least to our knowledge.

Randy discovered another notable behavior. When male mice are together with females, the male will initially mount the female. If she is not in estrus, she emits a clue and the male retreats. Not so with the male nNOS knock-outs. They would mount the females repeatedly despite loud squeals, “Rape! rape!” of the females. Such dramatic sexual aggression appears to be unprecedented in mice.

Prior to these behavioral forays, the only obvious phenotype of the knock-outs was an enlarged stomach. nNOS neurons innervating the pyloric sphincter provide relaxation so that the knock-outs were displaying pyloric stenosis with associated gastric dilation. Chris Ferris, who had completed his M.D./Ph.D. training and residency in medicine, was pursuing a gastroenterology fellowship and had returned to our lab. He noted a similarity of the nNOS knock-out stomachs to what happens in diabetic gastroparesis, a common complication of diabetes. Crystal Watkins, an M.D./Ph.D. student, collaborated with Chris to show that diabetic rodents display enlarged stomachs with slowed gastric emptying much like the nNOS knock-outs (Watkins et al., 2000). They also evinced a virtual abolition of nNOS neuronal staining in the pyloric area. We first assumed we were witnessing an extension to the stomach of diabetic neuropathy with the thin, unmyelinated nNOS neurons degenerating like so many others in diabetics. However, other staining techniques showed that the neurons were still there but simply lacked nNOS. Moreover, treatment with insulin restored the staining. The NO signaling in the stomach that regulates gastric propulsion involves cyclic GMP, as treating diabetic rodents with sildenafil alleviated diabetic gastroparesis.

NO does not signal only through cyclic GMP. At Duke, Jonathan Stamler showed that NO, being chemically reactive, can nitrosylate cysteines in various proteins (Hess et al., 2005). Because nitrosylation is rapidly reversible, it was difficult to ascertain whether nitrosylation was a normal event occurring under basal conditions with physiologic levels of NO that are far less than those resulting from addition of large concentrations of conventional NO donors. Samie Jaffrey, an M.D./Ph.D. student, developed a novel chemical technique, the biotin-switch assay, that detects nitrosylation of individual protein bands (Jaffrey et al., 2001). He showed that many prominent proteins are nitrosylated in the brain under basal conditions. Moreover, such nitrosylation vanishes in nNOS knock-out mice, establishing that this modification derives from physiologically formed and released neuronal NO.

Neurotransmitters come in chemical classes such as biogenic amines, amino acids and peptides. Might NO not be the only gaseous neurotransmitter? My M.D./Ph.D. student Ajay Verma asked whether carbon monoxide (CO) might function like NO. He noted that CO was already known to be formed in mammalian tissues, something of which I had been unaware. Heme oxygenase (HO), which degrades the heme released from hemoglobin in aging red blood cells, cleaves the ring to form biliverdin and at the same time releases a one carbon fragment as CO. The best characterized subtype of HO is an inducible form, highly concentrated in the spleen where aging red blood cells reside, and is designated H01. In the process of purifying H01, Mahin Maines at the University of Rochester found another form of the enzyme which she designated H02. H02 didn’t seem to be physiologically relevant, at least to the known roles of heme in degrading hemoglobin, as it was concentrated only in the brain and testes. Ajay showed that H02 is localized to discrete neuronal populations in the brain closely resembling the localizations of guanylyl cyclase which it activates similarly to NO (Verma et al., 1993). Moreover, he showed that CO physiologically regulates cyclic GMP in the retina. Randa Zakhary, an M.D./Ph.D. student, then established a neurotransmitter role for CO (Zakhary et al., 1997). She showed that NANC neurotransmission, which underlines normal intestinal peristalsis, is reduced by about 50% in nNOS knock-out mice and by the same proportion in H02 knock-out mice. Moreover, H02 and nNOS are localized in the same populations of neurons in the myenteric plexus of the gut suggesting that they may function as co-neurotransmitters. In analogy with NO, we asked, “How might CO be regenerated with each new nerve impulse to support neurotransmission?” Darren Boehning showed that, like nNOS, H02 is physiologically stimulated by calcium-calmodulin (Boehning et al., 2004) as well as being regulated by casein kinase-2 (CK2) phosphorylation (Boehning et al., 2003a). Masao Takahashi, a postdoctoral fellow, found that H02 also binds APP, the precursor of the Aβ42 peptide that occurs in Alzheimer’s plaques and mediates neurotoxicity (Takahashi et al., 2000). A-beta peptide precursor protein (APP) regulates H02 activity with Alzheimer mutant APP markedly diminishing H02 activity.

What about the other product of HO, biliverdin? Biliverdin readily accumulates in mammalian tissues that all contain an abundance of biliverdin reductase, that rapidly reduces biliverdin to bilirubin. This yellow pigment is generally regarded as the end product of heme metabolism, as it is conjugated to glucuronide and excreted. But this didn’t make any sense, because biliverdin is more readily excreted. Why would nature create two extra enzymes and, in the process, create bilirubin that in high concentrations deposits in the brain to cause kernicteric damage? An answer to these questions came in the studies of my postdoctoral fellow Sylvain Doré (Doré et al., 1999). He discovered that brain cultures from H02 knock-out mice are much more sensitive to all forms of neurotoxic insult than wild-type specimens and that the H02 mutants display substantially greater stroke damage. He wondered whether the loss of any product of H02 accounted for the neurotoxicity. Adding CO did not reverse the toxicity in brain cultures but low nanomolar concentrations of bilirubin were markedly neuroprotective. This was puzzling, because Sylvain was eliciting neural damage by adding to the cultures 100 μM concentrations of the oxidant hydrogen peroxide. It was well known that bilirubin is antioxidant. But how could minute concentrations of this antioxidant protect against 10,000 times higher concentrations of an oxidant? We thought of a possible explanation. Whenever a molecule of bilirubin acts as an antioxidant, it is itself oxidized to biliverdin. Perhaps the abundant tissue concentrations of biliverdin reductase regenerate bilirubin. Such an enzymatic amplification could readily enable bilirubin to cope with 10,000 times higher concentrations of hydrogen peroxide. A M.D./ Ph.D. student David Baranano proved that this hypothesis is correct (Baranano et al., 2002). He showed that depletion by ribonucleic acid (RNA) interference of biliverdin reductase prevents the neuroprotective actions of bilirubin and also worsens the neurotoxic effects of various agents.

All of these findings suggested that bilirubin serves as an endogenous antioxidant cytoprotectant. Biliverdin reductase would provide an elegant means for nature to make use of bilirubin but maintain low endogenous concentrations, as higher levels of bilirubin are toxic to the brain and other tissues. Clinical data support this notion. Gilbert’s syndrome is a condition in which individuals have a defect in the bilirubin glucuronidation process and so display modestly elevated serum levels of bilirubin. The prevalence of ischemic heart disease in these individuals is about a sixth of control levels. Multiple studies in “normal” populations show less atherosclerosis in individuals with elevated bilirubin.

Glutathione is a well-known antioxidant that is an endogenous cytoprotectant. Why do we need bilirubin? One possibility lies in the markedly different chemical properties of the two molecules. Glutathione is a water soluble tripeptide, whereas bilirubin is an extremely lipophilic molecule. Perhaps glutathione primarily protects water soluble proteins, whereas bilirubin would prevent peroxidation of membrane lipids. To test this concept, Tom Sedlak, a psychiatrist in our lab, monitored soluble protein oxidation as well as oxidation of lipids (Sedlak and Snyder, 2006). He showed that bilirubin selectively protects lipids, whereas glutathione protects the proteins. He depleted glutathione with an agent that inhibits its biosynthesis and depleted bilirubin reductase by RNA interference. Loss of glutathione led to a greater increase in protein oxidation than lipid oxidation and the reverse transpired with the loss of bilirubin.

The heme oxygenase-biliverdin reductase story provides yet one more example of the beauty with which nature sculpts the body. As Julie Axelrod always emphasized, “When nature finds a good molecule, he/she uses it again and again in different contexts.”

D-Serine

The history of neuroransmitters is filled with “laws” that are repeatedly overturned. Acetylcholine was the first neurotransmitter and formed the paradigm for “proper” transmitters. One rule was that a “neurotransmitter must be inactivated by a specific synaptic enzyme.” Julie’s work with norepinephrine reuptake inactivation overturned that notion. Peptides are not inactivated by enzymes or uptake and to this day don’t display any unique inactivating system—they probably just diffuse away from synapses. To ensure specificity, it was assumed that nature created molecules that were highly specialized to be neurotransmitters. Amino acids such as glutamate and glycine dispensed with that concept. Far more radical were the gases. They were not stored in synaptic vesicles nor released by exocytosis, nor did they act upon receptors on adjacent neuronal membranes. D-amino acids, especially D-serine, are even more bizarre.

I had been intrigued by a little-noticed paper from the laboratory of Professor Toru Nishikawa who was developing a prodrug of D-serine as a nonmetabolized glycine analogue for administration to schizophrenics. He was testing the “NMDA hypothesis of schizophrenia” based on the similarity to schizophrenia of the psychosis elicited by phencyclidine, which blocks NMDA receptors so that stimulating the “glycine site” of the NMDA receptor should be therapeutic. To assess whether the prodrug delivered D-serine to the brain, his postdoctoral fellow Atsushi Hashimoto developed a high performance liquid chromatography (HPLC) system to separate the isomers. Remarkably, in placebo-treated rodents the brain contained D-serine at levels about a third those of L-serine, while there were no other D-amino acids detectable except for some D-aspartate. My graduate student Michael Schell tried different means of assaying D-serine with little success till our faculty colleague Mark Molliver suggested generating an antibody. This succeeded magnificently and was followed soon by an antibody to citrulline, the coproduct of NOS action, which was used to monitor NOS activity in the brain by immunohistochemistry (Eliasson et al., 1997).

The D-serine antibody revealed notable surprises (Schell et al., 1995). D-serine was highly localized to areas of the brain enriched in NMDA receptors. This was tantalizing, because D-serine was known to be substantially more potent than glycine at the so-called glycine site of the NMDA receptor. The classic work of Phillipe Ascher had established that NMDA receptor activation requires another agonist and that glycine satisfied this requirement. It was assumed that the NMDA receptor was unique in requiring two agonists, because its overstimulation could be neurotoxic. Because glutamate is a dietary amino acid, eating a steak dinner might cause a stroke. The requirement for a second neurotransmitter would provide a fail-safe mechanism—two keys required to open the lock. However, this didn’t make sense, as glycine was also an abundant dietary amino acid. We felt that D-serine, a rare molecule formed only in the vicinity of NMDA synapses might make better sense. Jean-Pierre Mothet, a postdoctoral fellow, carried out the critical experiment to test this possibility (Mothet et al., 2000). In 1935 the great Hans Krebs had discovered a novel enzyme, D-amino acid oxidase, which surprisingly degraded only D-amino acids. We showed that at physiologic pH the enzyme is rather selective for D-serine and, when added to brain extracts, it can totally degrade D-serine without influencing levels of any other amino acid, especially glycine. Adding D-amino acid oxidase to brain slices or cultures greatly reduced NMDA neurotransmission despite completely normal levels of glycine. Hence, it appeared likely that D-serine is the predominant coagonist with glutamate at NMDA receptors. Very recently, in collaboration with my former student Joe Coyle, we have found alterations of NMDA transmission as well as long-term potentiation (LTP) in mice with knock-out of serine racemase.

The next surprise came with localizations. Herman Wolosker, a postdoctoral fellow, undertook the task of seeking an enzyme that physiologically generates D-serine. After some heroic biochemistry, he successfully purified and then cloned serine racemase, which converts L- to D-serine (Wolosker et al., 1999). The immunohistochemical localizations of serine racemase and D-serine were the same, both in the vicinity of NMDA synapses. However, both were highly concentrated in astrocytic glia that ensheath the synapse. Hence, D-serine appeared to overturn an unspoken but clearly fundamental rule of neurotransmission—a neurotransmitter should be in neurons. Subsequently, following his move to a faculty position at the Technion in Israel, Herman has shown that serine racemase and D-serine also occur in neurons but a variety of evidence indicates that glial D-serine mediates neurotransmission.

GAPDH and Cell Death

In recent years our laboratory has addressed signaling systems that are cytotoxic or cytoprotective. These include the IP3 receptor-cytochrome C interaction, NO mediating glutamate neurotoxicity, IP6 kinase-II killing cells, the neuroprotective actions of drugs influencing immunophilins, and bilirubin serving as a cytoprotectant.

One of the most striking of these signaling cascades involves glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH is a well known glycolytic enzyme whose generation of ATP is critical for cells in various contexts. I became interested in GAPDH upon reading a paper by De Maw Chaung utilizing antisense technology to identify potentially neurotoxic proteins (Ishitani and Chuang, 1996). He found that antisense to GAPDH blocked neurotoxicity elicited by an anticancer drug in cerebellar cultures. Akira Sawa, an M.D./Ph.D. psychiatrist doing postdoctoral work in our lab, attempted to confirm and extend this finding. Akira showed that antisense to GAPDH protects against toxicity elicited by multiple stimuli in a wide range of cell cultures (Sawa et al., 1997). He then noticed that with all these apoptotic stimuli about 4% of cellular GAPDH translocated to the nucleus. Although antisense treatment had little effect on total cellular levels of GAPDH, it depleted the nuclear pool, which presumably turned over more rapidly.

We wondered how GAPDH, which lacks a nuclear localization signal, enters the nucleus. Akira utilized yeast two-hybrid technology to look for binding partners with nuclear localization signals and detected Siah, a ubiquitin3-ligase. By a selective mutational analysis Akira established that Siah is responsible for the translocation of GAPDH to the nucleus following apoptotic stimuli. But how would such stimuli cause GAPDH to bind to Siah? A graduate student Makoto Hara established the following signaling cascade (Hara et al., 2005). Following any cell stressor iNOS is induced. The generated NO nitrosylates GAPDH at cysteine-150, which is critical to catalytic activity. Although abolishing catalytic activity, nitrosylation confers upon GAPDH the ability to bind to Siah. In the brain neurotoxic stimuli elicit glutamate release which, via NMDA receptors, generates NO to nitrosylate GAPDH.

Once in the nucleus, how does GAPDH kill the cell? Makoto and Nilkantha Sen, a postdoctoral fellow, obtained insight by showing that nitrosylated GAPDH in the nucleus binds to the protein acetylase p300/CBP which then acetylates GAPDH enabling it to activate p300/CBP by augmenting its autoacetylation. p300/CBP then acetylates and activates p53, the well-known tumor suppressor whose ability to kill cells is well established.

Extracurricular Activities

Music has long been a passion. I began piano lessons when I was just 5 years old and, before I was 6, I performed on a local radio talent show “Uncle Bud’s Amateur Hour”—a reflection of my Mom’s “stage mother” proclivities. When I was 8 years old, our piano was sold—possibly because of a clash about practicing. As detailed above, I ended up playing the classic guitar and continue to practice more or less regularly as time permits. I try to help the guitar community in my capacity as a board member of the Peabody Conservatory where I have adopted the Guitar Department as my special focus. For instance, we sponsor the top guitar student each year or two in a Carnegie Hall recital. I also serve as a trustee of the Shriver Hall Chamber Music Concert Series, one of the most prominent in the country, and have successfully lobbied for guitar recitals.

My most extensive civic commitment in the music world involves the Baltimore Symphony Orchestra (BSO). As one of the principal cultural organizations of the city, which derives half its $30 million budget from philanthropy, the board has typically been dominated by local business leaders whose corporations are a mainstay of support. An apocryphal but true story deals with the CEO of Baltimore’s premier bank. When asked to join the BSO board, he responded, “Okay, just so long as I never have to go to a concert.” Hence, when a friend of mine on the nominating committee advocated for my membership, she argued, “Shouldn’t we have at least one person on the board who cares about music?” Soon after joining the board in 1992 I became chair of the Music Committee, a position that I maintain and cherish today. Why should a symphony orchestra need a music committee composed of trustees? What have they to offer the music director? One of my passions is the commissioning of new symphonic works. I argue to the board that in the laboratory we don’t constantly repeat the experiments of Pasteur—hence, let’s encourage new symphonic works.

To raise commissioning funds, I have sought links to events that appeal to appropriate donors. One of my first activities was to commission a new concerto for the guitar that I funded by soliciting contributions from former students of my teacher Sophocles Papas. I uncovered a zionistically motivated donor to support a commission in honor of the 50th anniversary of the state of Israel. Baltimore’s was the only major symphony orchestra sponsoring such a commission. The biggest challenge was a concerto that our music director David Zinman had conceptualized for two left-handed pianists, Leon Fleisher and Gary Graffman, both of whom suffered from focal dystonia that incapacitated their right hand. For a rather large fee, the U.S. composer William Bolcom accepted the challenge. He realized that it would be rare to have two left-handed pianists in the same concert hall on the same day. Hence, he elaborated two separate concertos for the left hand that could also be played together, hence three distinct concertos. A fund-raising breakthrough arrived when we realized that a distinguished Baltimore hand surgeon, recently deceased, had treated Fleisher and Graffman, and his hospital was fund-raising for a new hand surgery building. The world premiere of the concerto was a sold-out fund-raiser for the hospital, raising ample funds for the commission and for the new building.

Participating in our synagogue has been rewarding. My religious roots go back to when I was five years old. Although our family was reform, I was sent to a newly founded modern orthodox Hebrew day school, largely because there was bus service and a hot lunch. I remained at the Hebrew Academy of Washington till high school but thereafter was little involved with religion. When our older daughter Judy was school age, we joined a liberal, unaffiliated synagogue populated in large measure by academics, lawyers, and physicians. I accidentally attended a board meeting and soon was on the board and a few years later was president. I accepted the position after being assured that, “the synagogue runs itself. You’ll have little to do between the monthly board meetings.” Within the first two months of my tenure our custodian fell from a ladder in the lobby, bumped his head, and died. Then our beloved cantor underwent surgery for a presumed herniated lumbar disc and emerged paraplegic. A new rabbi arrived. We were a bare-bones congregation with no secretary, just an administrator who couldn’t type.

Despite all the chaos, my tenure was much fun. As Hopkins is the leading hospital in Baltimore, where many of our ill congregants were treated, I took to making regular hospital visits, complementing the pastoral activities of the rabbi, an enterprise that was personally enriching. Of course, the president ought to attend synagogue every Saturday. To make this a meaningful experience, I encouraged our tradition of a full Shabbat lunch for all the congregants. Besides being a time when I could transact most synagogue business, interpersonal interactions at synagogue were rewarding. Rather than finding weekly attendance a chore, it became an addiction and to this day I attend synagogue regularly on Saturday mornings.

I never thought of myself as a scientist but rather a physician/psychiatrist who happens to do some research. I wanted to be a psychiatrist long before I had any interest in science. I still devote a good bit of time to helping people in distress find appropriate referrals. Although I have maintained a faculty appointment in the psychiatry department at Johns Hopkins and for years continued to supervise residents in psychotherapy, I was never involved in departmental administration. To get a feel for the big picture of psychiatry, I agreed to serve on the board of the Sheppard Pratt Hospital, the largest private psychiatric hospital in Maryland. Learning the economics of a large hospital’s administration, its delicate interplay with governmental politics and bureaucracy, and somehow keeping the hospital out of bankruptcy are remarkable challenges. Somehow they concatenate in a bizarre mixture which has worked well—at least for our hospital. One of my pet efforts on the board has been to help launch a museum of art with mental health themes. In the new hospital building, with inviting public spaces, the art attracts the local community. Thus, the edifice is not regarded as an “insane asylum” but as an important communal gathering place.

Scientific Public Life

The life of a biomedical researcher can be great fun—especially if the work is going well and is well funded. I recall Julie giving a public address soon after winning the Nobel Prize and saying, “I never cease wondering at my good fortune to be in a job that is so much fun that I would be doing it even if there were no pay.” Research can be an all-consuming 24/7 enterprise. If so, who minds the store? Someone needs to chair departments, serve as Dean, edit journals, and organize scientific societies. I have always been relatively well organized and so have been drafted into various civic endeavors.

My first encounter in the civic life of the scientific community involved efforts to honor Julie. It started with a scientific meeting where Leslie Iversen, Jacques Glowinski, Lincoln Potter, Hans Thoenen, and other former students of Julie were assembled. We talked about “doing something” for Julie. Somehow I ended up responsible for organizing “something” for what I thought would be Julie’s 60th birthday in 1971—it turned out to be his 59th. In August 1970 I asked the powers of the American Pharmacology Society, ASPET, to allow us a slot during the ASPET banquet to be held in April 1971 at the Federation of American Societies for Experimental Biology (FASEB) gathering in Chicago. I was told, “So many of our colleagues have birthdays that we can’t single out any single individual for special treatment.” Irv Kopin, who was serving as president of the Catecholamine Club, which held dinner meetings at FASEB, agreed to a program of Julie’s former students. Raising money from drug companies to subsidize travel expenses seemed hopeless. Then, in October 1970 Julie’s receipt of the Nobel Prize was announced. Money from drug companies flowed in. I received a phone call from the ASPET president eager to include us on his program—I declined. The Catecholamine Club event was much fun and emotionally moving. Oxford University Press put out an elegant volume incorporating chapters from all the speakers.

Another challenge came in the early 1970s. Every 6 years since the late 1950s catecholamine researchers had gathered for a major meeting. I was drafted to chair the Catecholamine Conference to be held in Strasbourg in 1972. I was soon initiated into the world of fund-raising. Although just a 32-year-old twirp, I was obliged to toady up to major drug company VPs seeking donations. Somehow, we raised enough money to support the travel of the 120 invited speakers and to provide amenities for the 500 to 600 participants.

One of the principal sources for funding was Robert Maxwell, the notorious, now-deceased founder of Pergamon Press. Normally scientific publishers do not fund meetings or publications, merely providing modest royalties on sales of the volume. At that time Maxwell had just returned to leadership of Pergamon after a hiatus during which the British government found him “not fit to run a public company.” He was eager to resurrect the scientific image of Pergamon and appeared willing to pay for the privilege of publishing our volume. I recall vividly meeting with him more than a year before the meeting when he invited me to his enormous suite in the San Francisco Hilton Hotel at the time of the International Pharmacology Congress. Of the six rooms in his “presidential” suite, one was a cocktail lounge where he exerted his famous charismatic charm. I was rather flummoxed, me a nobody, being wooed by this famous man. However, I knew what I wanted, a large advance on royalties, something that was in those days unprecedented for scientific books, especially for proceedings of scientific meetings. I sold him on the “massive” interest by the biomedical community in catecholamines and walked away with a handsome advance. Although I subsequently obtained gifts from the major drug companies, Maxwell’s was the largest contribution.

Another unique feature of the Strasbourg meeting was its “opening to China.” The conference took place in June 1973 soon after Richard Nixon’s trip to China. We had sent pro forma letters of invitation to officials of the Chinese Academy of Sciences expecting nothing in return. Remarkably, we received a delegation of top Chinese biomedical researchers. They were warm and friendly individuals, most of whom had only recently been resurrected from their exile to the countryside during the Cultural Revolution.When I returned to Baltimore I had visits from the FBI and the CIA asking about my sojourn in Strasbourg. The agents revealed that Chinese attendance at a catecholamine meeting was no accident but a calculated effort to learn new research that might benefit Mao Tse-tung’s Parkinson’s disease.

I was elected president of the Society for Neuroscience for the 1980 year, highlighted by some interesting challenges. The Society had been launched in 1970 with a few hundred members and had grown to about 7,000 when I took office. People were complaining that the annual meeting was so crowded that “one couldn’t be with one’s own friends.” There was an incipient movement to fracture the always tentative union between the molecular oriented “wets” and the neurophysiologic “drys.” I argued that the raison d’etre of the Society was to bring together these two streams of neuroscience. Moreover, I noted that membership size was plateauing—a false prediction for a society which now numbers about 37,000 members. The union held.

In a single year as president, one can’t accomplish too much. I felt it important to select a special focus. Ours was then, and still is, the largest biomedical research society, yet was alone in not publishing a society sponsored journal. Members of Council resisted, “There are already too many journals.” However, I thought there were not enough journals of distinction in the neurosciences. If we could make subscription to the society journal a component of member dues, we would launch the journal with 7,000 subscribers, substantially more than almost any other basic biomedical journal. With such a proposition, we could probably obtain far more favorable terms from a publisher than the usual 50/50 split of the “profits,” which too often evaporated with accounting legerdemain. As successful journals generally run a 40% operating profit, I proposed that the publisher pay us 20% of gross revenue, which ought to correspond to half the profits, and editorial office expenses. Max Cowan agreed to be the first Editor-in-Chief. We interviewed a series of publishers and set up an auction that attracted impressive bids from about five companies. Williams and Wilkins, the respected publisher of the Journal of Biological Chemistry, the Journal of Pharmacology, and Experimental Therapeutics and others, provided the best offer. Thus was the Journal of Neuroscience born.

Years later I returned to service on behalf of the Journal of Neuroscience. In the mid-1990s the Internet was beginning to affect scientific publishing, with a few journals developing online editions while others resisted the expense and chaos of this “passing fad.” I was asked to chair the Committee on Publications. It became evident to me that online publishing was the future and that laggards would be losers. Following some struggle with Council, we collaborated with Stanford University’s HiWire operation to launch an online version of our journal. Ours was the second major basic biomedical online publication following the Journal of Biological Chemistry, a pioneer from which we gleaned precious wisdom. Today a favorite cocktail party competition is guessing the date when hard copies of biomedical journals will vanish.

That year, 1980, was a busy one. Joshua Lederberg had assumed the presidency of Rockefeller University and had a single “professorship” open. He had long had a fascination with the brain and psychiatry—his wife is a psychiatrist. Josh courted me aggressively, indicating that I could bring with me two other faculty, my colleagues Joe Coyle and Mike Kuhar. Rockefeller provided munificent support for faculty, so much that one almost didn’t need to apply to the NIH for research grants. Fully intending to leave Johns Hopkins, I visited Dean Richard Ross. He said that large amounts of “hard” money for a professor were out of the question. However, many people had advocated that Hopkins develop a department focused on the brain. He proposed designating Joe, Mike, and myself as the Department of Neuroscience. He would provide us more money than Rockefeller offered with no more responsibilities than directing the medical student freshman course in neuroscience. The law of inertia prevailed, I remained in Baltimore, and the Neuroscience Department was launched as a tiny group of three faculty charged with coordinating activities for neuroscientists throughout the medical school.

Our group didn’t remain tiny for long. Howard Hughes chose to “get into” the neuroscience game at University of California/San Francisco (UCSF), Mass General, Columbia, and Hopkins. Hughes funding permitted us to recruit four new faculty. Then Vernon Mountcastle and all the other neurophysiologists in the Physiology Department elected to move into our department as did Mark Molliver and other neuroanatomists in the Anatomy Department. The construction of a new basic science building about this time enabled all of us to congregate in contiguous space. Before long we were the largest basic science department at Hopkins. My faculty have all been civic minded so that chairing the department was never onerous and rarely occupied more than 20% of my time. I found that recruiting new faculty and nurturing their development was much akin to developing the careers of young postdoctoral fellows and of parenting children. If you make your children, students, and faculty your number one priority, they’ll rapidly wean, become independent successes, and bring you joy.

In 2006, after some 26 years directing the Department, I stepped down and Rick Huganir assumed leadership. In 1987 Rick was one of our first Howard Hughes recruits into neuroscience, till then a senior associate of Paul Greengard’s at Yale. It has been particularly gratifying to witness his growth over two decades to a world-class neuroscientist and respected administrator.

Industry

Ever since taking the pharmacology course in medical school, I have been fascinated by drugs. It was fortuitous that my research training was with Julie Axelrod, likely the greatest pharmacologist of his era. Much of the early work in my laboratory at Hopkins involved drugs such as amphetamines and psychedelic drugs. However, my interactions with the drug industry had been limited to begging for financial support for scientific meetings. Receptor research changed all of that. Until the advent of ligand binding for neurotransmitter receptors, drug development in the pharmaceutical industry required screening agents in intact animals, demanding chemical engineering feats to deliver many grams of drug to the pharmacologist. If one chemical was more potent than another, there was no way of determining whether it had greater affinity for the putative receptor, was metabolized less, or penetrated more readily to the target organ. Thus, intelligent structure-activity analysis was impossible. Receptor binding changed all of this. Even with the relatively primitive binding apparatus in our laboratory, we could screen thousands of chemicals a day.

Soon I was a consultant to a substantial number of leading pharmaceutical companies including Sandoz (now Novartis), Burroughs-Wellcome, Warner-Lambert, Dupont, and others. One of the first and most productive relationships was with Sandoz. A little more than a year after publication of the opiate receptor paper, I was visited by Stephan Guttmann, head of chemistry at Sandoz. He grasped the potential importance of receptor binding for drug development and also saw it as an opportunity to incorporate biology into the chemistry division to mitigate his dependence on the Sandoz pharmacologists. I became a consultant to the company, visiting Basle four to six times a year and hosting chemists from Sandoz in our laboratory where they learned receptor technology.

Visiting the laboratories at Sandoz and other companies was illuminating, teaching me much about the psychology of industry scientists. Chemists were typically horrified when I advocated screening their large libraries of chemicals at random to seek “hits” that could then be further refined to secure greater potency. They took umbrage that I would be treating chemists as automotons doing blind screening “like monkeys.” After much effort, I convinced most that high-throughput screening would provide greater intellectual stimulation for the chemists. They might uncover totally unexpected structures that were uniquely active at particular receptors. My classic argument utilized the opiate receptor as a paradigm. What if enkephalin were a known neurotransmitter and one wished to find a drug to mimic it? Molecular modeling with the most advanced computers would never lead to morphine, whereas a simple screen of plant extracts would hit pay dirt rapidly. Enkephalin is a useful example, as finding small molecules to activate or block receptors for peptides is a particularly major challenge that, over recent decades has been successfully addressed.

Receptor screening has been particularly useful in sculpting drugs to avoid side effects. Muscarinic cholinergic actions have bedeviled many psychotropic drugs including most neuroleptics and antidepressants. Although Prozac was heralded for introducing the class of serotonin-specific uptake inhibitors (SSRIs), its principal clinical benefit has been the absence of anticholinergic side effects based on screening candidates for effects on [³H]QNB binding to muscarinic sites.

In 1980 Genentech went public, and the biotech boom emerged. In late 1982 I was approached by two young brothers David and Isaac Blech. Utilizing their meager savings from Bar Mitzvah gifts and borrowings from friends, they had launched Hybritech, the first biotech company to focus upon making monoclonal antibodies. Within a year they had founded several biotech companies. The dozens of biotech companies then extant largely did very similar things, cloning genes for proteins such as insulin or making monoclonal antibodies. The Blechs asked their advisors whether there existed any other biomedical technology that would be relevant to the pharmaceutical industry. They spoke to my former M.D./Ph.D. student Gavril Pasternak at Cornell, who pointed out the obvious relevance of receptors and sent them to me. The brothers journeyed to Baltimore, we had lunch at Danny’s, a fancy restaurant near the train station, agreed that a receptorbased company made good sense, shook hands, and within a few months launched Nova Pharmaceutical Corporation.

There is a formula for developing new companies, especially in high tech areas. One begins with seed funding to hire a handful of people and get some sort of “proof of principle.” Then comes venture capital funding at substantially greater levels and finally, many years later, a public offering, affording financial liquidity. Nova overturned all these rules. In the summer of 1983 Nova had no labs and no products. The only employee was Don Stark, former president of the American division of Sandoz and an expert in marketing drugs, but no knowledge of science. I recruited David U’Prichard, my former postdoctoral fellow and then a faculty member at Northwestern University, as our Research VP. David had no industrial experience. Biotech was extremely hot that summer. The Blechs wanted to catch the frenzied market optimism before it dissipated. Hence, with nothing but a dream, Nova went public. The stock offering was highly successful, with the share price increasing almost 50% in a day.

One of my first challenges was ensuring that my activities with Nova didn’t interfere with my obligations to Johns Hopkins. Nova never funded any of my Johns Hopkins research. In terms of time commitments, I strived to honor the University guidelines that faculty shouldn’t devote more than 20% of their effort to outside activities. Accordingly, I declined the great majority of invitations to give talks at other universities and participate in scientific meetings, except for those that provided unique intellectual rewards. I set up regular monthly meetings with the head of research and with laboratory researchers and, of course, was available for phone calls.

Nova thrived. I enjoyed the availability of an outlet whereby new findings in our lab with potential therapeutic benefit could be exploited. For instance, bradykinin was well recognized as an important peptide mediator of pain and inflammation. Hence, our identification of bradykinin receptors (Innis et al., 1981) might have therapeutic relevance if it were only possible to make bradykinin antagonists. Our collaborator, John Stewart at the University of Colorado, had made modifications in the bradykinin peptide structure that conveyed antagonist properties. Patents from the University of Colorado were licensed to Nova whose peptide chemists soon came up with potent and selective bradykinin antagonists. In a collaborative scientific investigation between Nova and ourselves, we showed that the bradykinin antagonists had analgesic properties in rodents leading to a drug development enterprise at Nova (Steranka et al., 1988). As there was a literature on a role for bradykinin in mediating the symptoms of the common cold, Hans Mueller, Nova’s CEO, conducted an informal clinical trial on his own nose and decided that the bradykinin antagonists “obliterated all my symptoms.” More extensive clinical studies were less promising. Other companies subsequently came up with even more potent bradykinin antagonists, some of which are still being explored for anti-asthmatic actions.

The biotech industry has long endured an exhilarating/panicky seesaw existence on Wall Street with 1991 a time of exuberance. All public biotech companies were able to raise substantial amounts of cash, and mergers became popular. Nova merged with Scios, a California-based company about the same size as Nova. I remained on the Scios board and followed closely the up-down meanderings of the company culminating in its highly successful sale in 2004 to Johnson and Johnson.

As Scios focused on cardiovascular products, neuroscience didn’t make much business sense. I convinced the CEO Rich Casey to spin off the neuroscience efforts into a new company which we dubbed Guilford Pharmaceuticals. The name was my wife Elaine’s brainchild, reflecting the section of Baltimore in which we reside.

Guilford afforded new potentials for drug development. Henry Brem, then a young neurosurgeon at Hopkins, had worked with the eminent chemical engineer Robert Langer in developing a novel treatment for primary brain tumors. The classic anticancer drug carmustine was incorporated into a biodegradable polymer and implanted in the brains of patients at the site where the surgeon had removed their tumor. As carmustine is an alkylating agent, it would not diffuse away from the site of implantation so that patients could receive, at the site of tumor regrowth, concentrations of the drug more than 1,000 times what would be possible by conventional routes of administration. The resultant product Gliadel had been under development by Nova since 1985, but the medical chief of Scios thought it was “silly” and declined to carry the product forward even though Phase III clinical trials had already been completed. I successfully inveigled Rich Casey, the Scios CEO, to gift the project to Guilford—we sealed it with a handshake in the men’s room at a Scios retreat.

Besides Gliadel, Guilford developed potential neuroprotective drugs based on the immunophilin research in our lab. Phase II trials of the lead agent GPI1485 showed promise in slowing the progression of Parkinson’s disease. Particularly striking was our use of radiolabeled ligands of dopamine neuronal transporters to image dopamine neurons and directly demonstrate a retardation of their loss following drug treatment. Technical problems regarding the drug’s bioavailability have hampered progress.

What have I learned from my experiences with industry? Some argue that academics should confine themselves to basic research and let drug companies learn about their findings from publications. I think differently. The NIH doesn’t fund biomedical research because science is beautiful. Rather, every dollar of our grant support is intended to find causes and, more importantly, treatments for disease. The increasing sophistication of molecular approaches to biomedical science brings new basic findings far closer to therapeutic application than in past years. Yet there remains a gulf between the two. Drug development in large pharmaceutical organizations is driven in substantial part by the marketing divisions which too often advocate “metoo” approaches to capture 10% to 20% of market share of some other company’s multibillion dollar blockbuster. If a university scientist approaches a large company with an idea based on his or her newly discovered receptor/ enzyme, the retort will be, “We have long lists of great ‘inhouse’ ideas already which we don’t have time to pursue. Moreover, we have no guarantee that a drug acting on your new receptor/enzyme will be effective, as there is not yet already a drug acting at this target.” Small companies founded by university scientists, the mainstay of the biotech industry, can bridge this chasm.

Family

Elaine and I were married a week after I graduated medical school. Our honeymoon comprised hoisting our worldly goods into my Volkswagen and driving from Washington, D.C., to San Francisco where I interned at the Kaiser Hospital. Most internships are grueling affairs that, in the 1960s on the East Coast of the United States, involved working every other night all night. By contrast, medical life was much less stark in San Francisco with the on-call schedule at Kaiser generally being every fourth or fifth night. Coupled with the lack of need to study for exams, internship was the most relaxed period of my life since beginning college. Elaine and I made many close friends, some of whom we have retained throughout the years. My first foray into songwriting occurred when a former intern lured me into collaborating on a musical show satirizing medicine. Elaine and I developed an interest in art collecting, making purchases of some original prints, which we couldn’t afford as each of us was earning about $250 a month. Such an idyllic year formed a fruitful beginning to a marriage that has happily endured till the present.

Our first-born daughter Judith, like typical first borns, was always well behaved and grew up to realize her parents’ aspirations. From the time she was 5 years old she knew, more or less, that she would be a physician. However, to avoid becoming a “grind” Judy majored in art history at Princeton even helping Elaine and I in our collecting activities.

Judy loved every specialty in medical school, especially pediatrics. She knew that she would never wish to “compete with dad” and so eschewed even considering psychiatry. However, she fell in love with the discipline as soon as she began her psychiatry clerkship and now is in private practice of psychiatry in Philadelphia.

Judy married Stephen Kastenberg while she was still a medical student. During her psychiatry residency she gave birth to Abigail, 2 years later to Emily, and 5 years later to Leo. The grandchildren have become a most important part of our life. As Philadelphia is only 1 to 2 hours by car from Baltimore, we see the kids every 2 to 3 weeks.

All grandparents repeat the same mantra, “Nothing is so wonderful. It’s positively spiritual.” For me, the grandchildren released a new burst of creative fervor, especially in music. As soon as Abigail was born, I wrote a song, “Abigail I Love You.” Now original songs with lyrics and chords emerge at the birthdays of all the kids as well as on numerous other occasions, such as the departure of guys and girls from the lab, the birth of their children, special birthdays of friends, and numerous other occasions. Grandchildren are a fitting capstone to anyone’s life.

Deborah emerged 4 years after Judy, very different in temperament. She always marched to her own drummer and was remarkably creative from the outset. By the time she was 7 years old, Debbie was involved in school theatre. In high school she joined a American-Russian musical troupe whose production “Peace Child” toured the Soviet Union, Japan, and other countries on multiple occasions. Besides becoming fluent in Russian, the Peace Child experience fostered Debbie’s pre disposition for the theatre. Thus, in college she majored in theatre and participated in every aspect, writing, directing, and performing. Her playwriting gift soon became apparent so she is now a New York—Los Angeles playwright—screenwriter. Courtesy of the California Supreme Court’s ruling legalizing gay marriage, Debby and her partner Sonora Chase, a talented actress, were wed in August 2008.

Bottom Line

What is it all about? What I’ve tried to convey in this essay is that, for me, life works best if one incorporates a diversity of interests. Participation in the arts enhances fecundity in scientific discovery. Parenting children involves the same practices as mentoring students, faculty, and other professional colleagues. Doing “deals” in the business world augments one’s acumen for meandering the jungle of modern science. Most of all, all of these activities should be fun. If not, why bother?

Selected Bibliography

sBanerjee SP, Cuatrecasas P, Snyder SH. Solubilization of nerve growth factor receptors of rabbit superior cervical ganglia. J Biol Chem 1976;251:5680–5685.

Banerjee SP, Snyder SH, Cuatrecasas P, Greene LA. Binding of nerve growth factor receptor in sympathetic ganglia. Proc Natl Acad Sci USA 1973;70:2519–2523.

Baranano DE, Rao M, Ferris CD, Snyder SH. Biliverdin reductase: a major physiologic cytoprotectant. Proc Natl Acad Sci USA 2002;99:16093–16098.

Bennett JP Jr., Logan WJ, Snyder SH. Amino acid neurotransmitter candidates: sodium-dependent high-affinity uptake by unique synaptosomal fractions. Science 1972;178:997–999.

Bennett JP Jr., Snyder SH. Angiotensin II binding to mammalian brain membranes. J Biol Chem 1976a;251:7423–7430.

Bennett JP Jr., Snyder SH. Serotonin and lysergic acid diethylamide binding in rat brain membranes: relationship to postsynaptic serotonin receptors. Mol Pharmacol 1976b;12:373–389.

Bhandari R, Saiardi A, Ahmadibeni Y, Snowman AM, Resnick AC, Kristiansen TZ, Molina H, Pandey A, Werner JK Jr., Juluri KR, Xu Y, Prestwich GD, Parang K, Snyder SH. Protein pyrophosphorylation by inositol pyrophosphates is a post-translational event. Proc Natl Acad Sci USA 2007;104:15305–15310.

Boehning D, Moon C, Sharma S, Hurt KJ, Hester LD, Ronnett GV, Shugar D, Snyder SH. Carbon monoxide neurotransmission activated by CK2 phosphorylation of heme oxygenase-2. Neuron 2003a;40:129–137.

Boehning D, Patterson RL, Sedaghat L, Glebova NO, Kurosaki T, Snyder SH. Cytochrome c binds to inositol (1,4,5) trisphosphate receptors, amplifying calciumdependent apoptosis. Nat Cell Biol 2003b;5:1051–1061.

Boehning D, Sedaghat L, Sedlak TW, Snyder SH. Heme oxygenase-2 is activated by calcium-calmodulin. J Biol Chem 2004;279:30927–30930.

Borjigin J, Wang MM, Snyder SH. Diurnal variation in mRNA encoding serotonin N-acetyltransferase in pineal gland. Nature 1995;378:783–785.

Braas KM, Newby AC, Wilson VS, Snyder SH. Adenosine-containing neurons in the brain localized by immunocytochemistry. J Neurosci 1986;6:1952–1961.

Bredt DS, Hwang PM, Glatt CE, Lowenstein C, Reed RR, Snyder SH. Cloned and expressed nitric oxide synthase structurally resembles cytochrome P-450 reductase. Nature 1991;351:714–718.

Bredt DS, Hwang PM, Snyder SH. Localization of nitric oxide synthase indicating a neural role for nitric oxide. Nature 1990;347:768–770.

Bredt DS, Snyder SH. Nitric oxide mediates glutamate-linked enhancement of cGMP levels in the cerebellum. Proc Natl Acad Sci USA 1989;86:9030–9033.

Bredt DS, Snyder SH. Isolation of nitric oxide synthetase, a calmodulin-requiring enzyme. Proc Natl Acad Sci USA 1990;87:682–685.

Bruns RF, Daly JW, Snyder SH. Adenosine receptors in brain membranes: binding of N6-cyclohexyl[³H]adenosine and 1,3-diethyl-8-[³H]phenylxanthine. Proc Natl Acad Sci USA 1980;77:5547–5551.

Bruns RF, Daly JW, Snyder SH. Adenosine receptor binding: structure-activity analysis generates extremely potent xanthine antagonists. Proc Natl Acad Sci USA 1983;80:2077–2080.

Burnett AL, Lowenstein CJ, Bredt DS, Chang TS, Snyder SH. Nitric oxide: a physiologic mediator of penile erection. Science 1992;257:401–403.

Burt DR, Creese I, Snyder SH. Antischizophrenic drugs: chronic treatment elevates dopamine receptor binding in brain. Science 1977;196:326–328.

Burt DR, Enna SJ, Creese I, Snyder SH. Dopamine receptor binding in the corpus striatum of mammalian brain. Proc Natl Acad Sci USA 1975;72:4655–4659.

Burt DR, Snyder SH. Thyrotropin releasing hormone (TRH): apparent receptor binding in rat brain membranes. Brain Res 1975;93:309–328.

Cameron AM, Steiner JP, Sabatini DM, Kaplin AI, Walensky LD, Snyder SH. Immunophilin FK506 binding protein associated with inositol 1,4,5-trisphosphate receptor modulates calcium flux. Proc Natl Acad Sci USA 1995;92:1784–1788.

Chakraborty A, Koldobskiy MA, Sixt KM, Juluri KR, Mustafa AK, Snowman AM, van Rossum DB, Patterson RL, Snyder SH. HSP90 regulates cell survival via inositol hexakisphosphate kinase-2. Proc Natl Acad Sci USA 2008;104:11341139.

Coon SL, Roseboom PH, Baler R, Weller JL, Namboodiri MA, Koonin EV, Klein DC. Pineal serotonin N-acetyltransferase: expression cloning and molecular analysis. Science 1995;270:1681–1683.

Coyle JT, Snyder SH. Antiparkinsonian drugs: inhibition of dopamine uptake in the corpus striatum as a possible mechanism of action. Science 1969a;166: 899–901.

Coyle JT, Snyder SH. Catecholamine uptake by synaptosomes in homogenates of rat brain: stereospecificity in different areas. J Pharmacol Exp Ther 1969b;170: 221–231.

Creese I, Burt DR, Snyder SH. Dopamine receptor binding: differentiation of agonist and antagonist states with 3H-dopamine and 3H-haloperidol. Life Sci 1975; 17:933–1001.

Creese I, Burt DR, Snyder SH. Dopamine receptor binding predicts clinical and pharmacological potencies of antischizophrenic drugs. Science 1976;192: 481–483.

Creese I, Burt DR, Snyder SH. Dopamine receptor binding enhancement accompanies lesion-induced behavioral supersensitivity. Science 1977;197:596–598.

D’Amato RJ, Alexander GM, Schwartzman RJ, Kitt CA, Price DL, Snyder SH. Evidence for neuromelanin involvement in MPTP-induced neurotoxicity. Nature 1987;327:324–326.

Dawson VL, Dawson TM, London ED, Bredt DS, Snyder SH. Nitric oxide mediates glutamate neurotoxicity in primary cortical cultures. Proc Natl Acad Sci USA 1991;88:6368–6371.

Doré S, Takahashi M, Ferris CD, Zakhary R, Hester LD, Guastella D, Snyder SH. Bilirubin, formed by activation of heme oxygenase-2, protects neurons against oxidative stress injury. Proc Natl Acad Sci USA 1999;96:2445–2450.

Eliasson MJ, Blackshaw S, Schell MJ, Snyder SH. Neuronal nitric oxide synthase alternatively spliced forms: prominent functional localizations in the brain. Proc Natl Acad Sci USA 1997;94:3396–3401.

Ferris CD, Cameron AM, Bredt DS, Huganir RL, Snyder SH. Autophosphorylation of inositol 1,4,5-trisphosphate receptors. J Biol Chem 1992;267:7036–7041.

Ferris CD, Huganir RL, Snyder SH. Calcium flux mediated by purified inositol 1,4, 5-trisphosphate receptor in reconstituted lipid vesicles is allosterically regulated by adenine nucleotides. Proc Natl Acad Sci USA 1990;87:2147–2151.

Ferris CD, Huganir RL, Supattapone S, Snyder SH. Purified inositol 1,4,5-trisphosphate receptor mediates calcium flux in reconstituted lipid vesicles. Nature 1989;342:87–89.

Fischer JE, Snyder SH. Histamine synthesis and gastric secretion after portacaval shunt. Science 1965;150:1034–1035.

Furuichi T, Yoshikawa S, Miyawaki A, Wada K, Maeda N, Mikoshiba K. Primary structure and functional expression of the inositol 1,4,5-trisphosphate-binding protein P400. Nature 1989;342:32–38.

Garthwaite J, Garthwaite G, Palmer RM, Moncada S. NMDA receptor activation induces nitric oxide synthesis from arginine in rat brain slices. Eur J Pharmacol 1989;172:413–416.

Glowinski J, Snyder SH, Axelrod J. Subcellular localization of H3-norepinephrine in the rat brain and the effect of drugs. J Pharmacol Exp Ther 1966;152:282–292.

Gould RJ, Murphy KM, Snyder SH. [³H]nitrendipine-labeled calcium channels discriminate inorganic calcium agonists and antagonists. Proc Natl Acad Sci USA 1982;79:3656–3660.

Hara MR, Agrawal N, Kim SF, Cascio MB, Fujimuro M, Ozeki Y, Takahashi M, Cheah JH, Tankou SK, Hester LD, Ferris CD, Hayward SD, Snyder SH, Sawa A. S-nitrosylated GAPDH initiates apoptotic cell death by nuclear translocation following Siah1 binding. Nat Cell Biol 2005;7:665–674.

Hess DT, Matsumoto A, Kim SO, Marshall HE, Stamler JS. Protein S-nitrosylation: purview and parameters. Nat Rev Mol Cell Biol 2005;6:150–166.

Huang PL, Dawson TM, Bredt DS, Snyder SH, Fishman MC. Targeted disruption of the neuronal nitric oxide synthase gene. Cell 1993;75:1273–1286.

Hughes J. Isolation of an endogenous compound from the brain with pharmacological properties similar to morphine. Brain Res 1975;88:295–308.

Hughes J, Smith TW, Kosterlitz HW, Fothergill LA, Morgan BA, Morris HR. Identification of two related pentapeptides from the brain with potent opiate agonist activity. Nature 1975;258:577–580.

Innis RB, Correa FM, Uhl GR, Schneider B, Snyder SH. Cholecystokinin octapeptidelike immunoreactivity: histochemical localization in rat brain. Proc Natl Acad Sci USA 1979;76:521–525.

Innis RB, Manning DC, Stewart JM, Snyder SH. [³H]Bradykinin receptor binding in mammalian tissue membranes. Proc Natl Acad Sci USA 1981;78:2630–2634.

Innis RB, Snyder SH. Distinct cholecystokinin receptors in brain and pancreas. Proc Natl Acad Sci USA 1980;77:6917–6921.

Ishitani R, Chuang DM. Glyceraldehyde-3-phosphate dehydrogenase antisense oligodeoxynucleotides protect against cytosine arabinonucleoside-induced apoptosis in cultured cerebellar neurons. Proc Natl Acad Sci USA 1996;93:9937–9941.

Jaffrey SR, Erdjument-Bromage H, Ferris CD, Tempst P, Snyder SH. Protein S-nitrosylation: a physiological signal for neuronal nitric oxide. Nat Cell Biol 2001;3:193–197.

Javitch JA, D’Amato RJ, Strittmatter SM, Snyder SH. Parkinsonism-inducing neurotoxin, N-methyl-4-phenyl-1,2,3,6 -tetrahydropyridine: uptake of the metabolite N-methyl-4-phenylpyridine by dopamine neurons explains selective toxicity. Proc Natl Acad Sci USA 1985;82:2173–2177.

Javitch JA, Uhl GR, Snyder SH. Parkinsonism-inducing neurotoxin, N-methyl-4phenyl-1,2,3,6 -tetrahydropyridine: characterization and localization of receptor binding sites in rat and human brain. Proc Natl Acad Sci USA 1984;81:4591– 4595.

Kim SF, Huang AS, Snowman AM, Teuscher C, Snyder SH. From the cover: Antipsychotic drug-induced weight gain mediated by histamine H1 receptor-linked activation of hypothalamic AMP-kinase. Proc Natl Acad Sci USA 2007;104:3456–3459.

Kuhar MJ, Pert CB, Snyder SH. Regional distribution of opiate receptor binding in monkey and human brain. Nature 1973;245:447–450.

Lee CM, Snyder SH. Norepinephrine neuronal uptake binding sites in rat brain membranes labeled with [³H]desipramine. Proc Natl Acad Sci USA 1981;78: 5250–5254.

Logan WJ, Snyder SH. Unique high affinity uptake systems for glycine, glutamic and aspartic acids in central nervous tissue of the rat. Nature 1971;234:297–299.

Lowenstein CJ, Glatt CS, Bredt DS, Snyder SH. Cloned and expressed macrophage nitric oxide synthase contrasts with the brain enzyme. Proc Natl Acad Sci USA 1992;89:6711–6715.

Lyons WE, George EB, Dawson TM, Steiner JP, Snyder SH. Immunosuppressant FK506 promotes neurite outgrowth in cultures of PC12 cells and sensory ganglia. Proc Natl Acad Sci USA 1994;91:3191–3195.

Morrison BH, Bauer JA, Kalvakolanu DV, Lindner DJ. Inositol hexakisphosphate kinase 2 mediates growth suppressive and apoptotic effects of interferon-beta in ovarian carcinoma cells. J Biol Chem 2001;276:24965–24970.

Mothet JP, Parent AT, Wolosker H, Brady RO Jr., Linden DJ, Ferris CD, Rogawski MA, Snyder SH. D-serine is an endogenous ligand for the glycine site of the N-methyl-D-aspartate receptor. Proc Natl Acad Sci USA 2000;97:4926–4931.

Nagata E, Luo HR, Saiardi A, Bae BI, Suzuki N, Snyder SH. Inositol hexakisphosphate kinase-2, a physiologic mediator of cell death. J Biol Chem 2005;280:1634– 1640.

Nelson RJ, Demas GE, Huang PL, Fishman MC, Dawson VL, Dawson TM, Snyder SH. Behavioural abnormalities in male mice lacking neuronal nitric oxide synthase. Nature 1995;378:383–386.

Pasternak GW, Goodman R, Snyder SH. An endogenous morphine-like factor in mammalian brain. Life Sci 1975;16:1765–1769.

Patterson RL, van Rossum DB, Barrow RK, Snyder SH. RACK1 binds to inositol 1,4,5-trisphosphate receptors and mediates Ca²⁺ release. Proc Natl Acad Sci USA 2004;101:2328–2332.

Peroutka SJ, Lebovitz RM, Snyder SH. Two distinct central serotonin receptors with different physiological functions. Science 1981;212:827–829.

Peroutka SJ, Greenberg DA, U’Prichard DC, Snyder SH. Regional variations in alpha adrenergic receptor interactions of [³H]-dihydroergokryptine in calf brain: implications for a two-site model of alpha receptor function. Mol Pharmacol 1978;14:403–412.

Pert CB, Kuhar MJ, Snyder SH. Opiate receptor: autoradiographic localization in rat brain. Proc Natl Acad Sci USA 1976;73:3729–3733.

Pert CB, Snyder SH. Opiate receptor: demonstration in nervous tissue. Science 1973;179:1011–1014.

Pevsner J, Hwang PM, Sklar PB, Venable JC, Snyder SH. Odorant-binding protein and its mRNA are localized to lateral nasal gland implying a carrier function. Proc Natl Acad Sci USA 1988a;85:2383–2387.

Pevsner J, Reed RR, Feinstein PG, Snyder SH. Molecular cloning of odorant-binding protein: member of a ligand carrier family. Science 1988b;241:336–339.

Pevsner J, Trifiletti RR, Strittmatter SM, Snyder SH. Isolation and characterization of an olfactory receptor protein for odorant pyrazines. Proc Natl Acad Sci USA 1985;82:3050–3054.

Resnick AC, Snowman AM, Kang BN, Hurt KJ, Snyder SH, Saiardi A. Inositol polyphosphate multikinase is a nuclear PI3-kinase with transcriptional regulatory activity. Proc Natl Acad Sci USA 2005;102:12783–12788.

Russell D, Snyder SH. Amine synthesis in rapidly growing tissues: ornithine decarboxylase activity in regenerating rat liver, chick embryo, and various tumors. Proc Natl Acad Sci USA 1968;60:1420–1427.

Russell DH, Snyder SH. Amine synthesis in regenerating rat liver: extremely rapid turnover of ornithine decarboxylase. Mol Pharmacol 1969;5:253–262.

Sabatini DM, Erdjument-Bromage H, Lui M, Tempst P, Snyder SH. RAFT1: a mammalian protein that binds to FKBP12 in a rapamycin-dependent fashion and is homologous to yeast TORs. Cell 1994;78:35–43.

Saiardi A, Bhandari R, Resnick AC, Snowman AM, Snyder SH. Phosphorylation of proteins by inositol pyrophosphates. Science 2004;306:2101–2105.

Saiardi A, Caffrey JJ, Snyder SH, Shears SB. Inositol polyphosphate multikinase (ArgRIII) determines nuclear mRNA export in Saccharomyces cerevisiae. FEBS Lett 2000;468:28–32.

Saiardi A, Erdjument-Bromage H, Snowman AM, Tempst P, Snyder SH. Synthesis of diphosphoinositol pentakisphosphate by a newly identified family of higher inositol polyphosphate kinases. Curr Biol 1999;9:1323–1326.

Saiardi A, Sciambi C, McCaffery JM, Wendland B, Snyder SH. Inositol pyrophosphates regulate endocytic trafficking. Proc Natl Acad Sci USA 2002;99:14206– 14211.

Sattin A, Rall TW. The effect of adenosine and adenine nucleotides on the cyclic adenosine 3,’ 5’-phosphate content of guinea pig cerebral cortex slices. Mol Pharmacol 1970;6:13–23.

Sawa A, Khan AA, Hester LD, Snyder SH. Glyceraldehyde-3-phosphate dehydrogenase: nuclear translocation participates in neuronal and nonneuronal cell death. Proc Natl Acad Sci USA 1997;94:11669–11674.

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;92:3948–3952.

Sedlak TW, Snyder SH. Messenger molecules and cell death: therapeutic implications. JAMA 2006;295:81–89.

Seeman P, Chau-Wong M, Tedesco J, Wong K. Brain receptors for antipsychotic drugs and dopamine: direct binding assays. Proc Natl Acad Sci USA 1975;72: 4376–4380.

Seeman P, Lee T, Chau-Wong M, Wong K. Antipsychotic drug doses and neuroleptic/dopamine receptors. Nature 1976;261:717–719.

Simantov R, Kuhar MJ, Uhl GR, Snyder SH. Opioid peptide enkephalin: immunohistochemical mapping in rat central nervous system. Proc Natl Acad Sci USA 1977;74:2167–2171.

Simantov R, Snyder SH. Morphine-like peptides in mammalian brain: isolation, structure elucidation, and interactions with the opiate receptor. Proc Natl Acad Sci USA 1976;73:2515–2519.

Simon EJ, Hiller JM, Edelman I. Stereospecific binding of the potent narcotic analgesic (3H) Etorphine to rat-brain homogenate. Proc Natl Acad Sci USA 1973;70:1947–1949.

Smellie FW, Davis CW, Daly JW, Wells JN. Alkylxanthines: inhibition of adenosineelicited accumulation of cyclic AMP in brain slices and of brain phosphodiesterase activity. Life Sci 1979;24:2475–2482.

Snyder SH. Perceptual closure in acute paranoid schizophrenics. Arch Gen Psychiatry 1961;5:406–410.

Snyder SH. Brain peptides as neurotransmitters. Science 1980;209:976–983.

Snyder SH. Brainstorming. Boston, MA: Harvard University Press, 1989.

Snyder SH, Axelrod J, Zweig M. A sensitive and specific fluorescence assay for tissue serotonin. Biochem Pharmacol 1965;14:831–835.

Snyder SH, Epps L. Regulation of histidine decarboxylase in rat stomach by gastrin: the effect of inhibitors of protein synthesis. Mol Pharmacol 1968;4:187–195.

Snyder SH, Faillace L, Hollister L. 2,5-dimethoxy-4-methyl-amphetamine (STP): a new hallucinogenic drug. Science 1967;158:669–670.

Snyder SH, Greenberg D, Yamamura HI. Antischizophrenic drugs and brain cholinergic receptors. Affinity for muscarinic sites predicts extrapyramidal effects. Arch Gen Psychiatry 1974;31:58–61.

Snyder SH, Katims JJ, Annau Z, Bruns RF, Daly JW. Adenosine receptors and behavioral actions of methylxanthines. Proc Natl Acad Sci USA 1981;78:3260–3264.

Snyder SH, Merril CR. A relationship between the hallucinogenic activity of drugs and their electronic configuration. Proc Natl Acad Sci USA 1965;54:258–266.

Snyder SH, Michaelson IA, Musacchio J. Purification of norepinephrine storage granules from rat heart. Life Sci 1964;3:965–970.

Snyder SH, Myron P, Kies MW, Berlow S. Metabolism of 2-C14 labeled L-histidine in histidinemia. J Clin Endocrinol Metab 1963;23:595–597.

Snyder SH, Reivich M. Regional localization of lysergic acid diethylamide in monkey brain. Nature 1966;209:1093–1095.

Snyder SH, Richelson E. Psychedelic drugs: steric factors that predict psychotropic activity. Proc Natl Acad Sci USA 1968;60:206–213.

Snyder SH, Rosenthal D, Taylor IA. Perceptual closure in schizophrenia. J Abnorm Soc Psychol 1961a;63:131–136.

Snyder SH, Silva OL, Kies MW. The mammalian metabolism of L-histidine. IV. Purification and properties of imidazolone propionic acid hydrolase. J Biol Chem 1961b;236:2996–2998.

Snyder SH, Zweig M, Axelrod J, Fischer JE. Control of the circadian rhythm in serotonin content of the rat pineal gland. Proc Natl Acad Sci USA 1965b;53:301–305.

Steiner JP, Connolly MA, Valentine HL, Hamilton GS, Dawson TM, Hester L, Snyder SH. Neurotrophic actions of nonimmunosuppressive analogues of immunosuppressive drugs FK506, rapamycin and cyclosporin A. Nat Med 1997;3:421–428.

Steiner JP, Dawson TM, Fotuhi M, Glatt CE, Snowman AM, Cohen N, Snyder SH. High brain densities of the immunophilin FKBP colocalized with calcineurin. Nature 1992;358:584–587.

Steranka LR, Manning DC, DeHaas CJ, Ferkany JW, Borosky SA, Connor JR, Vavrek RJ, Stewart JM, Snyder SH. Bradykinin as a pain mediator: receptors are localized to sensory neurons, and antagonists have analgesic actions. Proc Natl Acad Sci USA 1988;85:3245–3249.

Supattapone S, Worley PF, Baraban JM, Snyder SH. Solubilization, purification, and characterization of an inositol trisphosphate receptor. J Biol Chem 1988;263:1530–1534.

Takahashi M, Dore S, Ferris CD, Tomita T, Sawa A, Wolosker H, Borchelt DR, Iwatsubo T, Kim SH, Thinakaran G, Sisodia SS, Snyder SH. Amyloid precursor proteins inhibit heme oxygenase activity and augment neurotoxicity in Alzheimer’s disease. Neuron 2000;28:461–473.

Taylor IA, Rosenthal D, Snyder S. Variability in schizophrenia. Arch Gen Psychiatry 1963;8:163–168.

Terenius L. Stereospecific interaction between narcotic analgesics and a synaptic plasm a membrane fraction of rat cerebral cortex. Acta Pharmacol Toxicol (Copenh) 1973;32:317–320.

U’Prichard DC, Greenberg DA, Sheehan PP, Snyder SH. Tricyclic antidepressants: therapeutic properties and affinity for alpha-noradrenergic receptor binding sites in the brain. Science 1978;199:197–198.

U’Prichard DC, Snyder SH. Binding of 3H-catecholamines to alpha-noradrenergic receptor sites in calf brain. J Biol Chem 1977;252:6450–6463.

Uhl GR, Bennett JP Jr., Snyder SH. Neurotensin, a central nervous system peptide: apparent receptor binding in brain membranes. Brain Res 1977a;130:299–313.

Uhl GR, Kuhar MJ, Snyder SH. Neurotensin: immunohistochemical localization in rat central nervous system. Proc Natl Acad Sci USA 1977b;74:4059–4063.

van Rossum DB, Patterson RL, Cheung KH, Barrow RK, Syrovatkina V, Gessell GS, Burkholder SG, Watkins DN, Foskett JK, Snyder SH. DANGER, a novel regulatory protein of inositol 1,4,5-trisphosphate-receptor activity. J Biol Chem 2006;281:37111–37116.

Verma A, Hirsch DJ, Glatt CE, Ronnett GV, Snyder SH. Carbon monoxide: a putative neural messenger. Science 1993;259:381–384.

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Nobuo Suga

BORN:

Kobe City, Hyogo Prefecture, Japan

December 17, 1933

EDUCATION:

Tokyo Metropolitan University, B.S. (1958)

Tokyo Metropolitan University, Ph.D. (1963)

APPOINTMENTS:

Tokyo Medical and Dental University (1958)

Harvard University (1963)

University of California, Los Angeles (1965)

University of California, San Diego (1966)

Washington University (1969)

HONORS AND AWARDS (SELECTED):

American Academy of Arts and Sciences (1992)

National Academy of Sciences (1998)

Academy of Sciences in St. Louis, MO (2003)

Ralph W. Gerard Prize, The Society for Neuroscience (2004)

Nobuo Suga and his collaborators explored the neural mechanisms for parallel and hierarchical processing of biosonar information and the cortical maps representing different types of biosonar information. They also explored the role of the corticofugal (descending) auditory system in the improvement and adjustment of auditory signal processing and the neural circuit for plastic changes in the central auditory system elicited by auditory fear conditioning.

Nobuo Suga

Parents and Childhood

My father, Setsuzo Suga (1885–1966), and my mother, Sueno (Miyamoto) Suga (1897–1994), were born and grew up in northern Kyushu, the place of our ancestral home. My parents had four children: one daughter and three sons. Their daughter died at age 2 before I was born. I was the middle child of the three brothers. Just before I was born, my father’s friend told my father, “If your next child is a boy, his name should be Nobuo, because this name with three kanjis (morphograms) is the best combination with Suga.”

My father opened a printing house in Kobe City. I didn’t know the reason why my father chose the printing business. Was it a good business for a new epoch after the long-lasting feudal period? I had heard from my mother that he was from a Samurai family in northern Kyushu. So, I wonder how he could have generated the money to purchase all the machines for his printing house. What I remember is that three men and one woman worked in the printing house and that one of the men occasionally brought me small crabs because he knew I liked animals. Two large printing machines on the first floor of the printing house made a sound “Gara gara ga-chan, Gara gara ga-chan.” A large cutter used for cutting a pile of large sheets of paper was also on the first floor. Several racks of movable type were on the second floor.

Once, when my father sharply turned his car loaded with sheets of paper at the corner of a street, the big pile of paper shifted toward one side of the car and the car flipped over. His left upper arm was injured. In his daily life, however, he had no problem with his injury at all, but he could not use a rifle. This turned out to be lucky for him and his family because he was able to escape the draft of the Japanese Imperial Army. However, his luck ended on March 17, 1945, when U.S. bombers (B29s) dropped incendiary bombs to burn down Kobe City. Approximately 9,000 people were burned to death by this overnight bombing. My father lost everything, except fortunately his family members were spared. From early 1944 to August 1945, all schoolchildren were evacuated from the cities. So, I was living in a temple halfway up a mountain along with my classmates and a teacher. There, autumn was beautiful. Rice fields below us were like golden carpets. The winter was cold with a lot of snow, so we could enjoy sledding. During the night of March 17, 1945, our teacher told us “Kobe City is under attack by U.S. bombers, and the city is burning.” We all stood on the open verandah of the temple, exposed to the cold air. A long stretch of sky far beyond the black mountains in front of us was reddish. Five days after the bombing, my parents came to the temple to pick me up. We moved by train from Kobe City to northern Kyushu. On the train, my mother told me how close they came to being burned to death. They, along with neighbors, had escaped under an elevated railroad. However, soon houses on both sides of the railroad started burning, but those on the harbor side had burned down earlier, giving them time to escape from the flames to the harbor just before they were suffocated and burned.

When I was growing up in Kobe, my father frequently took me to the fields and mountains near Kobe to collect beetles, grasshoppers, cicadas, and so on. Because of these experiences in Kobe, my childhood was enjoyable, filled with fishing and catching insects. In late July 1945 when I was in a tree catching a large stag beetle, I fell out of the tree, landing on a dead tree branch that tore a large opening in the skin of my right armpit. While going to the doctor’s office with my father, a U.S. fighter plane suddenly approached us. We heard a loud noise and saw splashes in the creek right alongside us on the road. We quickly hid under some nearby bushes. This brief moment was my last experience of the war.

The war ended on August 15, 1945. In Kyushu, my father purchased land and a farmhouse that had been partially damaged by a bomb. He became a farmer. My parents worked especially hard. However, they were not successful at all as farmers because they had no experience doing this type of work. By the time I graduated from middle school, my father’s savings were depleted. Financial rescue came from my mother’s younger brother who was successful in Tokyo. Heeding his suggestion and with his monetary support, I temporarily went to a nearby high school, and my father prepared to move our family from Kyushu to Tokyo. In Tokyo, I worked at a watch shop during the daytime, repairing and selling clocks, and went to high school and then to college at night.

High School

I liked biology and selected biology for extracurricular club activities. The club had just one microscope. After studying various sections of plants, there was nothing for the biology club members (only five to six people) to do, so we started going to the mountains whenever we had money and could take off work on Sundays. We mostly took a late-night train after our last class on Saturday and returned to Tokyo on a late-night train on Sunday. I remember very little from this period of my life, except the time spent in the mountains.

College

In Tokyo, there were several universities that had a night school. The professors and curriculum of these night schools were different from those of the regular schools, and the diploma stated that graduation was from the night school. However, Tokyo Metropolitan University was unique. The same professors taught day and night classes, and there was only one type of diploma. I took only night classes so it took 5 years instead of the usual 4 years for me to graduate. Without hesitation, I majored in biology. My parents did not say anything to me about it, but my relatives expressed their surprise because a biology major was least likely to earn money. I was first interested in genetics and joined the Chromosome Society and then the Genetics Society. I changed my mind, however, when I enrolled in an experimental embryology class taught by Professor Katsuma Dan. It was so fascinating that I decided to perform an experiment for a graduation thesis in experimental embryology instead of in genetics. Professor Dan gave me a project: “Change in the Toughness of the Chorion of Fish Eggs.” I studied the change in toughness of the chorion from just after fertilization through hatching. By the end of January 1958, I had written my thesis in Japanese. Professor Dan said, “This thesis is good enough to publish in English.” My thesis in English was apparently not good at all. So, Professor Dan eventually wrote it for me for publication (Suga, 1963).

The Bridge to Auditory Neurophysiology

I occasionally walked to Toritsu Daigaku railway station to ride the train to Shibuya station and to take another train on another line together with Professor Dan after my last class at night. It was perhaps late December 1957. While we were waiting for the train at Shibuya station, he asked me, “What is your plan after graduation?” (In Japan, a graduation ceremony is always in late March.) I replied, “I want to be a biologist and be involved in research.” Then, he said, “Well, our society has changed after the war. Like you, who has no money but wants to be a biologist.” (In 2006, I attended a biology class reunion in Tokyo and learned that Professor Dan had said the same thing to one of my classmates who also took all her classes at night and later became a professor at a university in Tokyo.) The train came in and Professor Dan got off at the second station, Harajuku. I rode further to Mejiro station and thought to myself, “Well, he is right. The emperor and his princes are involved in biology research.” It was not an option for me to go to graduate school because there was no graduate school at night. It was also not an option for me to work for a company just for money. I wanted to have a full-time job involved in research.

In January 1958, Professor Dan asked me to come to his office. He said, “You may be good in neurophysiology. Professor Yasuji Katsuki at Tokyo Medical and Dental University is one of my friends. He is a prominent auditory physiologist and has money to hire you. What do you think?” I knew neither neurophysiology nor auditory physiology. Professor Dan said, “Why don’t you try neurophysiology? If you do not like it, you may come back to me, and I will think of another job for you.” I replied, “I will try it. I’ll do my best.”That is the standard response in this situation. Professor Dan looked for one of his business cards in his desk drawers. He found only a well-worn card on which something was written. He cleaned it with an eraser and wrote “Professor Yasuji Katsuki. I introduce Mr. Nobuo Suga. Please kindly meet him.” And then he handed it to me, saying, “Please take this to Tokyo Medical and Dental University to see Professor Katsuki next Monday morning at 9 o’clock.”

That Monday, I went to Ochanomizu railway station. Tokyo Medical and Dental University was just across the bridge, Hijiribashi. I still remember; it was a cold, but pure, bright and beautiful morning when I crossed that bridge. I now know, it was the bridge for me to become an auditory neurophysiologist.

Professor Katsuki, who was wearing a white lab coat, was a warm, softspoken person. His office was divided by a black curtain, with his desk on the window side and electrical instruments in two relay racks on the door side. He only asked me a few questions and showed me his lab. He then asked me to meet “his” Assistant Professor Susumu Hagiwara (who later became a professor at the University of California), who also asked me a few questions. That was all. Professor Katsuki said, “Please work here, starting on April the first.” I got the job! There are no April Fool’s jokes in Japan.

Five Years in Katsuki’s Laboratory

In general, each department of a medical school consists of a full professor, an assistant professor, two assistants (who have a M.D. or M.D./Ph.D.), and a laboratory technician or laboratory assistant. A senior assistant can be a lecturer. I just had a bachelor’s degree in biology and knew nothing of neurophysiology, so I was first hired as a laboratory assistant. I then became an assistant in The Anatomy Department when there was an open position, although I had performed all my research in the Physiology Department. The research on hearing was so interesting to me that I put all my time and energy into it, from 8:30 AM to ∼ 11:00 PM. Professor Katsuki started to treat me as one of his collaborators by the midsummer of 1958, in spite of the fact that I was still busy learning auditory physiology through a review article written by Galambos (1954) and through my ongoing research on the cat’s auditory system in Katsuki’s laboratory. Professor Katsuki then gave me the research topic “The Neurophysiology of Hearing in Insects” for my Ph.D. dissertation. I immediately went to a department store on Ginza Street in Tokyo and purchased long-horned grasshoppers, “kirigirisu,” Gampsocleis buergeri (Tettigoniidae), and started to work on this species on Tuesdays, Thursdays, and Saturdays. On Mondays, Wednesdays, and Fridays, I worked on cats or monkeys with Professor Katsuki and Dr. Takeshi Watanabe or Kei-ichi Murata. A short paper by Katsuki and me on hearing in 12 species of insects was published in late 1958. It was my first published paper. When the reprints came in, I felt great satisfaction reading it on a late-night train to my home, although I found terrible misprints in Table 1 of the paper.

The research on insects (Suga and Katsuki, 1961), as well as on cats (Katsuki et al., 1959) and monkeys (Katsuki et al., 1960, 1962), went very well. Professor Katsuki briefly mentioned that the neurophysiology of vision might be an interesting topic for my future research, so I worked on the descending visual system of the kirigirisu in the summer of 1961 (Suga and Katsuki, 1962). However, the main focus of my research was on hearing in insects. There were periods of time during which I went to Katsuki’s home almost every Sunday afternoon to write papers. He used to wake up early in the morning, so I often found him asleep in the late afternoon in front of me when I was having a difficult time with my writing. I tried to wake him up by making noise, but it did not work. This signaled the end of the day’s activity. He and his wife often asked me to stay for dinner with them. After dinner, he used to make cocktails by referring to a booklet of recipes. He would pour half a cocktail into my glass and the other half into his. He used to make a few different cocktails during the course of the evening, so I felt very good on the train home. One particular evening, Professor Katsuki could not decide which cocktail to make next and handed the booklet to me to choose the next drink. I did not know anything about cocktails, so I pointed out “grasshopper” and said, “It might be interesting to try this.” He then looked at the booklet. A moment later, he said, “I am one bottle short to make this.” He suggested I choose something else, or else he would make the cocktail, saying, “This is a grasshopper, although one leg is missing.”

Professor Katsuki was a very sincere person. He did not tell jokes, or perhaps he did, but the jokes were not funny. By contrast, Dr. Hagiwara (Hagi-san) frequently joked or told stories in a very interesting way. We all ate lunch together. Professor Katsuki did not talk much, but Hagi-san talked frequently, evoking constant laughter. In late 1965, when my wife (Hiroko) and I stayed at Hagi-san’s house in La Jolla, California, for 3 days, he said, “The San Diego Zoo is wonderful. There are more than 100 giant tortoises from the Galapagos Islands.” So, the next morning, Hiroko and I went to the zoo. There was a much smaller number of tortoises than expected. So, we counted them. Later, at dinner, I mentioned to Hagi-san that there were only 31 giant tortoises. Hagi-san declared, “I amplify a story, but never lie.” Likewise, the job of a neurophysiologist, which I first learned in Katsuki’s laboratory, was to amplify small signals.

Professor Katsuki had a research grant from the National Institutes of Health (NIH) of the United States to develop a dip-prism microscope. Hagi-san and Mr. Toshio Nakatsubo (Olympus Optical Co., Tokyo) were his coworkers for this project. The potential for the application of this microscope for neurophysiological research was not promising. Hagi-san gradually disassociated himself from this project, and I gradually became involved with it. In response to a suggestion from the NIH, Professor Katsuki decided to demonstrate the microscope at the NIH in Bethesda, Maryland, and at the Congress of the International Union of Physiological Sciences held in Leiden, Holland. In the summer of 1962, we made a trip around the world. My schedule differed from Professor and Mrs. Katsuki’s. I joined them in Bethesda, New York, Boston, and Leiden. For me, it was an eye-opening first trip abroad, visiting the United States, England, Holland, Germany, Switzerland, and Italy. Unlike when I travel now, I met almost no Japanese people during my trip. The dip-prism microscope was not at all successful, but I was rewarded by the trip itself.

I spent 5 wonderful years in Katsuki’s laboratory, which was in its golden period at that time. I learned a great deal from Professor Katsuki, and I am proud to have written so many papers that were coauthored by Professor Katsuki. As I have previously stated, I had an opportunity to work on the hearing of several species of animals, including the cat and monkey as well as insects. Therefore, I still feel as though I can work on any animal, from a large macaque to a small cricket, if necessary, easily recognizing the merit of comparative auditory physiology. For me, the research on invertebrates and lower vertebrates is just as interesting and important as that on higher vertebrates such as primates because they all share the basic principles and mechanisms for hearing. Because my impression is that the speed of progress in neurophysiology is inversely related to the size of a species studied, I prefer to work on smaller animals rather than the larger ones.

In Katsuki’s lab, I was involved in research which might be historically interesting to describe here: (1) binaural neuron, (2) two-tone suppression,(3) cochleotopic (tonotopic) map in the primary auditory cortex, and (4) sharpening of frequency tuning by lateral inhibition.

Binaural Neuron, T-Large Fiber

Long-horned grasshoppers have the tympanic organ (ear) at the proximal end of the tibia. Many sensory (primary auditory) neurons attach to the tympanic membrane through the attachment cells. They send their axons (tympanic nerve fibers) to the first thoracic ganglion and excite second-order auditory neurons. One of the second-order neurons has a large-diameter axon. We named it the “T-large fiber” because it is excited by the tympanic nerve fibers. This large fiber in the central nerve cord sends auditory signals to the brain and the third thoracic ganglion from the first thoracic ganglion in the same discharge pattern.

The T-large fiber is excited by stimulation of the ipsilateral tympanic organ but is inhibited by stimulation of the contralateral tympanic organ. Because of this binaural interaction, the response of the T-large fiber to a sound is very directional. When a singing kirigirisu was placed 1 to 2 meters away from one side of a kirigirisu from which the action potentials of the T-large fibers on both sides were simultaneously recorded, the T-large fiber on one side showed action potentials well synchronized with individual stridulatory sounds of the song, whereas the T-large fiber on the other side did not (Suga and Katsuki 1961). Later, Solomon D. Erulukar, who wrote a review article on sound localization, told me that such a binaural neuron as the T-large fiber had not been previously found in any other animal, and that our finding fit into van Bergeijik’s model for sound localization in mammals. It was interesting to know that a certain neural mechanism is shared by insects and higher vertebrates.

Two-Tone Suppression

Inhibitory responses of auditory neurons to tone bursts were first found in the cochlear nucleus of a cat by Galambos and Davis (1944). In a noctuid moth, I found inhibition that was different from that described by them. In the tympanic organ of the noctuid moth, there are only two sensory neurons attached to the tympanic membrane through the attachment cells. There are no efferent nerve fibers to the organ. These two sensory neurons are tuned to an identical frequency but one was 20 to 30 decibels more sensitive than the other. The low threshold sensory neuron adapted much more slowly than the high threshold neuron. When a short tone burst was delivered during a long tone burst, the response of the low threshold neuron to the long tone was immediately stopped (inhibited) during the period of the overlap, although this short tone burst alone excited the neuron. This inhibition, which is now called “two-tone suppression,” was hardly explained at the time (Suga, 1961). Professor Katsuki then suggested examining whether the auditory nerve fibers of a monkey showed the same inhibition.

Because the frequency tuning of cats’ peripheral auditory neurons was much sharper than that of the basilar membrane studied by Békésy, sharpening of the neural frequency tuning by lateral inhibition was suspected by the early 1960s. In 1962–1963, inhibition of background discharges and/or twotone suppression of primary auditory neurons were reported in monkeys (Katsuki et al., 1962; Nomoto et al., 1964), cats (Rupert et al., 1963) and bullfrogs (Frishkopf and Goldstein, 1963). Nomoto et al. (1964) called twotone suppression “peripheral inhibition,” whereas Rupert et al. (1963) called it “direct or immediate inhibition.” Two-tone suppression was further studied by Sachs and Kiang (1968) who called it “two-tone inhibition.” The cochlear microphonic response showed two-tone suppression (Pfeiffer and Molnar, 1970) that was caused by cochlear nonlinearities (Pfeiffer, 1970). Two-tone inhibition is apparently not due to synaptic inhibition. Therefore, it has been called two-tone suppression.

The Cochleotopic (Tonotopic) Map or Representation in the Primary Auditory Cortex

When I learned of the cochleotopic map in the auditory cortices of anesthetized cats (Woolsey and Walzl, 1942) and dogs (Tunturi, 1944, 1960), I thought that the functional organization of the auditory cortex was fascinating. These studies were based on evoked potentials recorded from the auditory cortex. When I was in Katsuki’s lab, recording action potentials of single cortical auditory neurons of a cat with a glass micropipette electrode with a tip diameter of <0.3 μm was so difficult that only one frequency-tuning curve was measured on the average per each one-day experiment. This was presumably also the case in auditory physiology laboratories other than Katsuki’s lab. Therefore, single-neuron data for the cochleotopic map was accumulated with many cats and the locations of the studied neurons were superimposed referring to the anterior or posterior ectosylvian sulcus. It was then noticed that neurons with best (characteristic) frequencies quite different from each other were located at a given small area of the auditory cortex. Therefore, single-neuron data obtained in Katsuki’s lab and in a few other laboratories cast doubt on the presence of the strict cochleotopic map in the auditory cortex. Evans et al. (1965) recorded 105 cortical auditory neurons in unanesthetized cats and concluded that the distribution of best frequencies did not support the presence of the cochleotopic map in the auditory cortex. I understood that this conclusion was well accepted by most auditory physiologists. However, my single-neuron study on the auditory cortex of the little brown bat, Myotis lucifugus, showed the cochleotopic map (Suga 1965b). Therefore, I suspected that the auditory cortex of the bat might be different from that of the cat. Ten years later, the story of the cochleotopic map of the cat changed. That is, Merzenich et al. (1975) recorded single neurons or clusters of neurons from the auditory cortex of the anesthetized cat with glass-coated platinum-iridium electrodes and reestablished the presence of the cochleotopic map in the cat’s auditory cortex.

Sharpening of Frequency Tuning by Lateral Inhibition

The processing of constant frequency (CF) or quasi-CF sounds is directly related to a problem of whether the central auditory system has a mechanism for the sharpening of frequency tuning of neurons, because frequencytuning curves of peripheral neurons are very wide at high sound pressure levels. Katsuki et al. (1958, 1959) measured the frequency-tuning curves of single neurons at different levels of the ascending auditory system of the cat and found that the central auditory system of the cat has a neural mechanism for the sharpening of frequency tuning: the higher the level up to the medial geniculate body, the sharper the frequency tuning. Professor Katsuki believed that sharpening is accomplished by lateral inhibition. This was his major contribution to auditory neurophysiology at that time.

However, auditory physiologists had started to believe that there was no sign of neural sharpening and no sign of lateral inhibition in the central auditory system of the cat. This was based on findings made between the mid 1960s and early 1970s. (1) Frequency-tuning curves of cochlear nerve fibers tuned to frequencies higher that 3 kilohertz are very sharp without lateral inhibition (Kiang et al., 1965). (2) Frequency-tuning curves of neurons in the medial geniculate body are broader than those of peripheral neurons and show no sign of sharpening (Aitkin and Webster, 1972), and (3) Frequency-tuning curves of central auditory neurons are mostly similar to or broader than those of cochlear nerve fibers (an experience shared by most cat physiologists who worked on auditory nuclei). Later, this consensus was strengthened by Calford et al. (1983) who wrote: “No difference in sharpness of tuning was found between samples of units from nuclei in the lemniscal auditory pathway, although units from the anterior auditory field showed broader tuning than those in the lemniscal pathway” (p. 395). Professor Katsuki apparently was disappointed with this consensus against his findings and asked my opinion about it on a few occasions when I was a postdoctoral research associate in the United States.

Through my own research in 1964 and thereafter, it was clear to me that the frequency tuning of single neurons is sharpened by inhibition in the central auditory system of the little brown bat and the mustached bat. Unlike quasi-triangular tuning curves of peripheral neurons, pencil-shaped or spindle-shaped tuning curves have been found in the central auditory systems of many different species of animals over the last 40 years. Inhibitory tuning curves are commonly associated with a very sharp excitatory tuning curve. The best frequency (BF) for an inhibitory tuning curve is slightly lower or higher than the BF for an excitatory tuning curve. An application of a γ-aminobutyric acid (GABA-A) receptor antagonist to thalamic (Suga et al., 1997) or midbrain (Yang et al., 1992) auditory neurons eliminates the inhibitory tuning curves and broadens the excitatory tuning curves. It has been well demonstrated that the sharpening of frequency tuning curves is accomplished by lateral inhibition in a cascaded manner. I reached the conclusion that the contradiction on the sharpening of neural frequency tuning curves originated from differences in defining the sharpness of frequency-tuning curves of neurons (Suga 1995).

The sharpness of a tuning curve has been expressed by a Q-n dB value, which is the BF divided by a bandwidth at n dB above the minimum threshold (n dB width). If a tuning curve is exactly triangular in shape, its sharpness can be appropriately expressed by a single value, for example, a Q-10 dB value. If it is not, a Q-10 dB value related only to the tip portion of a tuning curve is simply inadequate to describe the overall sharpness of the tuning curve. Frequency-tuning curves of peripheral neurons commonly show a deflection point at about 40 dB above the minimum threshold where the slopes of the passive and active filters join (Evans, 1972). Therefore, Q-20 dB and Q-50 dB values may be used to determine whether the passive and/or active portions of a tuning curve are sharpened by inhibition in the central auditory system.

The choice of parameters characterizing tuning curves should be contingent on the problem being discussed. To discuss sharpening, a change in the skirt portion of a tuning curve (e.g., Q-50 dB) should be mainly considered, not the tip portion, because the tip portion is sharp at the periphery. On the other hand, to discuss broadening, the tip portion of a tuning curve (e.g., Q-20 dB) should be mainly considered, not the skirt portion, because the skirt portion is broad at the periphery (Suga and Tsuzuki, 1985). For me, it is quite appropriate to conclude that the cat’s central auditory system has a mechanism for the sharpening of frequency tuning, and that this mechanism drastically sharpens the skirt of a tuning curve.

Different from tuning curves at the periphery, the tuning curves of certain central auditory neurons have a narrow width even at high stimulus levels. Such a tuning curve is called a “level tolerant” sharp frequencytuning curve (Suga and Manabe, 1982). In the central auditory system, neurons with different response properties are clustered in different locations. Level-tolerant frequency tuning is common or concentrated in a particular region or regions along the cochleotopic axis (Casseday and Covey, 1992; Condon et al., 1994; Ehret and Moffat, 1985; Suga and Manabe, 1982; Suga and Tsuzuki, 1985) or along iso-BF lines (Schreiner and Mendelson, 1990; Schreiner and Sutter, 1992). The central auditory system also has a mechanism for the broadening of frequency tuning. Broadly tuned neurons are clustered separately from sharply tuned neurons. Therefore, the presence of broadly frequency-tuned neurons in the central auditory system cannot be used as evidence against the presence of sharply tuned neurons such as level-tolerant neurons.

Postdoctoral Research in the United States

In the summer of 1960, Professor V. B. Wigglesworth (an insect physiologist at the University of Cambridge in England) visited Katsuki’s laboratory. I demonstrated to him the responses of the binaural neurons (T-large fibers) of kirigirisu. He apparently liked the demonstration because just before he left the laboratory he invited me to work in his laboratory after finishing my Ph.D. dissertation. However, he had no setup for auditory neurophysiology as well as no salary for me. So, I started to prepare for an English test and an application for a British scholarship to get travel and living expenses to work in England.

At that time, Dr. Takeshi Watanabe (one of Professor Katsuki’s students) was at the Massachusetts Institute of Technology in Cambridge, Massachusetts, as a postdoctoral research associate. In 1961, he visited Professor Donald R. Griffin at the Biology Department of Harvard University. In Griffin’s lab, Alan D. Grinnell, a graduate student (presently a professor at UCLA), was finishing his Ph.D. dissertation on the neurophysiology of audition in bats and was planning to go to Bernard Katz’s lab at the University of London. So, Professor Griffin asked Watanabe whether Professor Katsuki knew of any young neurophysiologist who might want to come to his laboratory to work on the bat’s auditory system. My name was mentioned. Shortly afterwards, I received an invitation letter from Professor Griffin through Professor Katsuki. He apparently had a research grant to support me as well as the setup for auditory neurophysiology. Professor Katsuki suggested that I go to Griffin’s lab after finishing our presentation of the dip-prism microscope at the Congress of the International Union of Physiological Sciences held in Leiden, Holland, in the summer of 1962, and after receiving my Ph.D. I earned my Ph.D. in March 1963 by presenting my thesis “Neurophysiology of Hearing in Insects” and by giving a public lecture at Tokyo Metropolitan University. On April 1, 1963, I began working in Griffin’s lab as a postdoctoral research fellow. This was the beginning of my research on the bat’s auditory system. I first repeated Grinnell’s excellent pioneering work to become familiar with the auditory system of the little brown bat and then took advantage of a frequency modulated (FM) sound generator that was built by Dr. Jerry J. G. McCue in the MIT Lincoln laboratory. I found that the inferior colliculus consists of many different types of neurons in terms of excitatory and inhibitory frequency-tuning curves and responses to tone bursts, FM sounds, and noise bursts (Suga, 1969). Among them, FM-specialized neurons are particularly interesting, because they have no excitatory area, but instead an inhibitory area, and respond to a FM sound that sweeps across the inhibitory area. This “paradoxical” response is explained by a disinhibition or summation model. Many FM specialized neurons respond to downward-sweeping FM sounds, but not to upward-sweeping ones, and some respond to upward-sweeping FM sounds, but not to downward-sweeping ones, while some respond to downward and upward-sweeping FM sounds (Suga 1965a, 1965b). My research with the little brown bat went well. Professor Griffin promoted me to a lecturer in my 2nd year.

I had a wonderful time in Griffin’s lab. Hiroko Kurihara Suga (my wife, a middle-school teacher) came to Cambridge in the summer of 1963 to join me. Particularly vivid in my memory are the bat hunting trips I took to Cape Cod and Vermont with Hiroko and Ms. Judy H. Friend. In late 1964, Professor Griffin came back from the William Beebe Tropical Research Station in Trinidad, West Indies, and told me and his students that there were unknown animals producing ultrasonic sounds that could be detected only by a bat detector. I asked him to show me the waveform of the sounds on the cathoderay oscilloscope (CRO) screen in addition to playing back the tape-recorded sounds. By watching the waveform, I mentioned, “Those sounds must be produced by long-horned grasshoppers.” Then, Professor Griffin immediately said, “Why don’t you go to Trinidad to catch the insects?” So, Hiroko and I went to Trinidad in late January 1965. In the front yard of the research station, there were many “ultrasonic” insects singing in the afternoon, but I could not see any of them on the first day. In the late afternoon of the second day, I finally saw a faint green slender long-horned grasshopper (∼ 23 mm long) singing and reflecting sunlight at the tip of a drooping leaf of a Queen of India tree. When I moved my bat detector closer to the insect, its stridulatory sound became very loud. I was so excited that I missed catching it! However, once I knew what the insect looked like, it was not difficult to find and catch it. Eventually, I found three species of “ultrasonic insects”: Phlugis sp.1, Phlugis sp.2, and Drepanoxiphus modestus. Phlugises are daytime singers that produce stridulatory sounds that are 40 to 60 kilohertz noise bursts, whereas Drepanoxiphus is a night singer that produces sounds that are 22 to 24 kilohertz “pure tone” pulses. They were reported as mutes although they belonged to the long-horned grasshopper family. I caught several other long-horned grasshoppers, for example, Conocephalus saltator, which produces sounds that are 18 to 66 kilohertz noise bursts. I also studied their hearing and mechanism of sound production (Suga, 1966). We fully enjoyed the 2 months we spent in Trinidad, together with Roderick A. Suthers (presently a professor at Indiana University in Bloomington) who was working on the fish-catching bat, and Hubert Markl (presently retired from numerous highly prestigious posts in Germany) who was researching the leaf-cutting ant and other insects.

I spent two highly productive years in Griffin’s lab, working on the little brown bat at Harvard Biology and on ultrasonic grasshoppers in Trinidad. I wanted to publish papers coauthored by Professor Griffin. However, he said, “Everyone knows that I don’t do neurophysiology. I can’t be a coauthor.” So, all seven papers of mine did not bear his name. Because of this, I felt something was missing, but I thought that this was the U.S. way of publishing. Toward the end of the first year in Griffin’s lab, Professor Theodore H. Bullock (Zoology Department, UCLA) visited Griffin’s lab and offered me a job as a research scientist. So, in May 1965, Hiroko and I moved to UCLA and I began working in Bullock’s lab.

In Bullock’s lab, all postdoctoral research associates worked independently of each other, choosing their own research topics and species. Bullock’s lab had no setup for auditory neurophysiology. Therefore, after my arrival at UCLA, I ordered instruments for auditory neurophysiology as well as a soundproof chamber. While I waited for the instruments to arrive, I studied electric fish because a few species of electric fishes were kept in Bullock’s lab and were easily available for research. A departmental machinist, who was said to be very difficult to deal with, was somehow very cooperative with me and quickly made me a Lucite trough and mouthpieces for my experiments on the fish, according to my design. So, I was able to start my research on the electric fish within 1 month after my arrival at UCLA. This electric fish experiment lasted approximately 5 months (Suga, 1967). This was a relatively relaxed period in my life. Hiroko and I lived in West Los Angeles and often walked along the rows of tall palm trees on Santa Monica Beach, looking at the Pacific Ocean. My first child, Ibuki, was born in November 1965.

In late 1965, Professor Bullock moved to the medical school of the University of California, San Diego (UCSD). So, I moved to UCSD from UCLA in early 1966 and restarted my work on bats at Scripps Institute of Oceanography, La Jolla, because the medical school at UCSD was under construction. Bat hunting trips around Lake Henshow with Hiroko and Ms. Grace G. Kennedy (the lab assistant) were quite enjoyable. Professor Bullock provided me with unique experiences through his research collaborating with Katsuki’s group on hearing in porpoises in Japan and also through the research conducted on the research vessel, Alpha Helix, which traveled to the Amazon in Brazil. On Alpha Helix, I worked on hearing in mole crickets that flew on the ship at night or silky anteaters and sloths that were brought to the ship by natives.

In Katsuki’s lab, I studied the responses of the T-large fiber of the longhorned grasshopper to the species-specific call and had an opportunity to see its sound spectrogram. Therefore, it was not totally new for me to see sound spectrograms. In 1966, however, Visible Speech written by Potter et al. (1966) and several papers on the perception of speech sounds in humans (e.g., Cooper et al., 1952; Liberman et al., 1956, 1959) opened my eyes, because no neurophysiology textbook had ever described the acoustic patterns (sound spectrograms) of human speech and animal sounds that are processed by the auditory system. (All recent neurophysiology textbooks still have this tradition.) I examined the sound spectrograms of calls produced by many species of animals and found that calls of higher vertebrates contain three types of information bearing elements (IBEs): constant frequency (CF) tones, frequency modulated (FM) sounds, and noise bursts (NB) which respectively are comparable to formants, transitions, and fills in human speech sounds. Therefore, I first studied how central auditory neurons selectively responded to each of the three types of IBEs and how inhibition was contributing to the creation of the selectivity. I found that inhibition created various types of neurons: asymmetrical neurons, CF-specialized neurons, FM-specialized neurons, NB-specialized neurons, and so on (Suga, 1968, 1969, 1973). I then studied how central auditory neurons responded to combinations of IBEs. The stimuli designed for this experiment were not related to the sounds behaviorally relevant to the bat, and the progress in the research was mediocre. I had to wait 10 years to have success in this line of research.

I was quite comfortable as a research scientist in Bullock’s lab, but in early 1968, Professor Susuma Hagiwara (UCSD) suggested that I become an independent scientist. The University of Hawaii in Honolulu, Indiana University in Bloomington, and Washington University in St. Louis, Missouri, offered me an assistant professor’s job. I was not in a hurry at all to accept a faculty position and didn’t respond to any of these offers. Later, Washington University offered me an associate professor’s job instead of an assistant professor’s job. At Hagiwara’s suggestion, I took the job as an associate professor in the Department of Biology at Washington University.

My First Year at Washington University in St. Louis

I moved to St. Louis on the 4th of January in 1969. Having my own laboratory was the start of an exciting and wonderful phase of my research career. The first year at Washington University, I was particularly busy with writing papers on my research performed in California, lecture notes, and a laboratory manual for teaching as well as a proposal to get a research grant from the National Science Foundation (NSF). I also performed research on the cat’s auditory system in the Medical School at Washington University. My second child, Yuko, was born in May 1969. Hiroko and I were both very busy during this time. In retrospect, I wonder how I managed to do all these things at once.

My First Research Grant

I had no experience in writing a research proposal, and many young scientists had a difficult time in getting a research grant because of the Vietnam War (1959–1975). Regardless, I submitted my research proposal “Studies in Comparative Auditory Neurophysiology” to the NSF instead of the NIH, because my research on the bat’s auditory system was not directly related to human health. At that time, almost all auditory neurophysiologists had been working on cats, and the atmosphere was such that if you were not working on cats, you were not considered an auditory neurophysiologist. So, it appeared to be a disadvantage to keep working on bats. I could work on either cats or monkeys because I worked on cats and monkeys in Japan. I knew that the squirrel monkey, Saimiri sciureus, is not large and emits many different types of calls. Therefore, I chose the squirrel monkey for my next research project. In my proposal, I wrote something like “I will complete my research on bats in two years and then will start to work on the squirrel monkey.” My proposal was assigned to the program for Regulatory Biology. One day, Dr. David B. Tyler, the NSF Program Director, called me from Washington, D.C., and mentioned that he wanted to see me in my office during his visit to St. Louis. While visiting me, he told me that my proposal was for a project that would easily last 10 years or more. He suggested that I write a well-focused proposal for the next funding period and promised to fund my research project because of my high productivity and the many interesting research papers that I had written. That was a good ol’ days. The NSF supported my research from 1969 to 1981. I had a 2-month summer salary from the NSF. I had heard that the NIH allowed scientists to get a 3-month summer salary. So, in 1980, I submitted my research proposal, “Neural Basis of Complex-Sound Processing,” to the NIH as well as the NSF. My approved NIH research grant was larger than my approved NSF grant, so I chose the NIH grant. Since then, my research has been supported by the NIH.

Animals for Auditory Neurophysiology in My Lab

Because the auditory system has evolved for detecting and processing behaviorally relevant sounds (species-specific sounds and sounds produced by prey and predators), the selection of the species of an animal for auditory neurophysiology is an important issue. Orientation sounds (biosonar pulses or, simply, pulses) are indispensable sounds for survival of insectivorous bats and are extensively used everyday by bats. The acoustic parameters characterizing the pair of the pulse and its echo are known to bear different types of biosonar information. Therefore, a neural basis of complex-sound processing can be explored by researching how biosonar information is processed in the bat’s auditory system. However, the biosonar pulses of the little brown bat are simple FM sounds and are not particularly suited for discovering the basic mechanisms or principles for the neural processing of complex sounds. I was aware of the advantages and disadvantages of working on bats. However, I decided to work on bats for awhile because they were much smaller than the squirrel monkey and could easily be handled by myself without anyone else’s help.

In 1973, Dr. James A. Simmons, an assistant professor in the Department of Psychology at Washington University in St. Louis (presently a professor at Brown University), suggested that we work together on the Panamanian mustached bat, Pteronotus parnellii rubiginosus. That was the beginning of my research on the mustached bat. Jim was a brilliant person from whom I learned a great deal. Since 1970, the number of auditory neurophysiologists working on bats gradually increased. The mustached bat was recognized as an excellent species for auditory research, although its auditory system is specialized for echolocation. In the early 1980s, collecting Panamanian mustached bats became difficult. Dr. William E. O’Neill, one of my former postdoctoral research associates (presently a professor at the University of Rochester) helped me collect mustached bats in Jamaica, graciously sharing with me the caves where he also collected bats for his research. Because several groups of scientists had been collecting bats from the same caves annually since the early 1980s, by the mid-1990s the bat colonies had become small, and the bats were hard to collect. In addition, getting an animal collection permit became more difficult. In the late 1990s, the collection of mustached bats in Jamaica became impossible. Professor Jeffrey J. Wenstrup (at Northeastern Ohio University College of Medicine) kindly helped me with the importing of Trinidadian mustached bats.

To work on bats from foreign countries, we have to spend extra time and effort on animal collection, exportation and importation permits, interacting with local village people, shipping the bats by air freight, clearing them through customs at the airport, and hand-feeding the bats until they start to eat by themselves from a dish. In the long run, ideally the bats should be bred in the animal facility of the research university. The mustached bat is arguably one of the best species for auditory research. However, collecting them became a problem. So, I decided to work on the big brown bat, Eptesicus fuscus, (a common species in Missouri and Illinois) and the Mongolian gerbil, Meriones unguiculatus, in addition to the mustached bat. The comparative studies of different species of mammals turned out to be very interesting and important for the understanding of the neural specialization of the auditory system.

Setting up the Suga Lab (Transitional Period)

I had to wait approximately 10 months to set up my laboratory. Professor Russell Pfeiffer (Dept. of Electrical Engineering) offered me his auditory physiology setup to use that was designed for cats and located on the Medical School campus across Forest Park. I chose a topic familiar to me for our joint project with the cat: properties of two-tone suppression. One of Pfeiffer’s postdoctoral fellows, Randolph Martin Arthur (presently a professor at Washington University in St. Louis) joined this project and became its driving force (Arthur et al., 1971). When the minimum essential instruments to deliver single-tone bursts and record action potentials arrived at my lab and a soundproof chamber was installed, I wanted to start my research on bats, although our cat project was not completed. I didn’t know a place where I could collect bats in Missouri. At the end of one of my lectures at our medical school, Professor Louis S. D’Agrosa of St. Louis University Medical School introduced himself to me, saying that he had been working on the microcirculation of the bat’s wing. Soon after, we started collecting little brown bats in Missouri caves together.

In the first experiment in my lab, I found that some collicular neurons showed a constant response latency regardless of the stimulus intensities and rise times. To very weak tone bursts or tone bursts with slowly rising amplitudes, these constant latency neurons did not shift their response latencies at all. They were suited for coding echo delays (Suga, 1971).

My first postdoctoral research associate was Peter Schlegel, who was followed by Tateo Shimozawa. Together, we performed enjoyable experiments. We found that in five different species of bats, vocalization of speciesspecific biosonar pulses were elicited by electrical stimulation of the central gray matter or reticular formation of the midbrain (Suga et al., 1973), and that the auditory neural response evoked by a self-vocalized sound was attenuated by ∼25 dB in the midbrain by the efferent copy from the vocalization system (Suga and Schlegel, 1972; Suga and Shimozawa, 1974). Phillip H. S. Jen was my first graduate student. He stayed with me as a postdoctoral research associate for one year after graduation. To extend the findings of the neural attenuation of vocal self-stimulation, we worked on the muscular attenuation of vocal self-stimulation. We found that the middle ear muscles contracted synchronously with sound emission and attenuated vocal selfstimulation by 15 ∼ 30 dB: the lower the frequency of the emitted sound, the larger the attenuation. We also found that the tetanus fusion frequency of the stapedius muscle was as high as 320/s (Suga and Jen, 1975). We were quite satisfied with these experiments that we performed on the little brown bat.

Research on the Mustached Bat

The biosonar pulse of the little brown bat and the big brown bat is FM. It sweeps downward about one octave within a range between 100 and 15 kilohertz. The properties of FM pulses vary depending on echolocation situations. In target-directed flight, the FM pulse becomes lower in frequency, shorter in duration, and higher in emission rate. Echoes that elicit behavioral responses of the bat usually do not overlap with the emitted pulse. On the other hand, the biosonar pulse of the mustached bat always consists of a long CF component followed by a short FM component. Because each biosonar pulse contains four harmonics (H1–4), there are eight major components (CF1–4, FM1–4). The second harmonic (H2) is always predominant, with CF₂ at ∼ 61 kilohertz and FM₂ sweeping from 61 kilohertz to ∼49 kilohertz. The CF₂ frequency slightly differs among individual mustached bats and is sexually dimorphic: the males’ CF₂ is ∼ 1.04 kilohertz lower than the females’ on the average. In target-directed flight, the CF–FM pulse becomes shorter in duration and higher in emission rate, but its spectrum changes little. Echoes that elicit behavioral responses in the mustached bat usually overlap with the emitted pulse, so that biosonar information is extracted from a complex sound potentially containing up to 16 components. The long CF and short FM sounds are most suited for bearing velocity and distance information, respectively. Specifically, the difference in frequency between the CF components in the emitted pulse and its echo (Doppler shift) carries information about the relative velocity of a target, whereas the time delay of the echo from the emitted pulse carries information about target distance. Therefore, the auditory system of the mustached bat is particularly suited for exploration of the neural mechanisms for processing complex sounds by combination-sensitive neurons. I considered that the CF and FM components were comparable to the formants and transitions in human speech sounds and that the neural mechanisms found in the mustached bat would significantly contribute to understanding the basic neural mechanisms for processing the formants, transitions, and combinations of these (Suga, 1972). However, as expected, this view has not necessarily been well accepted because some think that the auditory system of the bat specialized for echolocation is very different from that of nonecholocating mammals, although the bat uses a variety of communication calls as do nonhuman primates (Kanwal et al., 1994).

Auditory Periphery

I began the research on the mustached bat in my lab, first with Simmons and then Jen. Later, many postdoctoral research associates came to my lab from Japan. The cochlea of the mustached bat is extremely sharply tuned to the frequency of ∼61 kilohertz. So, we first studied the auditory periphery (Suga and Jen, 1977). I was quite satisfied with the data on the auditory periphery of the mustached bat, which showed the dramatic specialization for analyzing the CF₂ of the species-specific biosonar pulse. Professor Gerhart Neuweiler (Goethe University of Frankfurt, Germany) invited me to work on the horseshoe bat, Rhinolophus ferrumequinum, the so-called 83-kilohertz CF-FM bat in the Old World. I first considered not going to Germany because the experiments in my lab had been going very well. However, I changed my mind because Jen could continue our experiments on the mustached bat without me and because I thought it would be interesting to work on the CF–FM bat in the Old World in comparison to the mustached bat that is the 61-kilohertz CF–FM bat in the New World. The 5 months in Frankfurt were successful (Suga et al., 1976). The data obtained from the auditory peripheries of the mustached, horseshoe, and little brown bats are the best demonstration of the specialization that the sharpness of the frequency tuning of peripheral neurons varies according to the amplitude spectrum of behaviorally important species-specific sounds (Suga and Jen, 1977).

Auditory Cortex

My experimental philosophy was first to find cortical auditory neurons that were quite different from peripheral ones in their response properties and then explore how the differences were created by neural interaction in the central auditory system, using the top-down approach. Because the auditory periphery was successfully studied, I began working on the auditory cortex with Jen. We first examined the columnar organization in terms of the BF and then the cochleotopic (tonotopic) map in the auditory cortex. That is, we first performed the most basic study. The cochleotopic map of the auditory cortex of the mustached bat was unique, because the frequency of CF₂ at ∼ 61 kilohertz was overrepresented and the iso-BF contour lines were concentric (Suga and Jen, 1976). Such a cochleotopic map had not been found in any other animal at that time. This large area representing CF₂ was apparently related to the processing of Doppler shifted (DS) CF signals. So, we named it the DSCF processin area.

Amplitopic Representation

Different from other cortical auditory areas, the DSCF area represents identical frequencies at ∼61 kilohertz with a larger number of neurons. So, an obvious question was what was different among neurons tuned to identical frequencies. I particularly remember the summer months of 1976 when I did not have a research associate because an expected research associate was not able to come to my lab in time. So, I alone continued the acute cortical mapping experiments, working from morning until midnight, because it was essential to have the data, as much as possible, from one auditory cortex within one day. Hiroko came to the lab in the evening with our two children, bringing dinner, so that we all could eat and spend time together. This 3-month summer research produced very interesting data: (1) each DSCF neuron was tuned to a specific combination of frequency and amplitude of a sound,(2) each cortical column represented a specific combination of frequency and amplitude, and (3) the DSCF area had the frequency-versus-amplitude coordinates (Suga, 1977; Suga and Manabe, 1982). This was the first neurophysiological map beyond the cochleotopic map. We also found that the DSCF area consisted of two subdivisions in terms of the distribution of two types of binaural neurons (Manabe et al., 1978), and one type of binaural neuron was callosally connected, but the other type was not (Liu and Suga, 1997). Knudsen and Konishi (1978) found the auditory space map in the midbrain of the barn owl. So, the auditory physiology of noncat species became very interesting. The number of auditory physiologists working on noncat species gradually increased, and they became a nonminority in the field of auditory physiology.

Combination-Sensitive Neurons

Toshiki Manabe and I further studied the frequency and amplitude tuning of DSCF neurons and started to examine other cortical areas that were interesting enough for further exploration. The area dorsoanterior to the DSCF area showed very poor responses to single tone bursts, so we initially did not pay attention to this area. However, we occasionally found combination-sensitive neurons in this area. A “combination-sensitive” neuron means that the response of the neuron to a combination of two or more sounds is larger than the algebraic sum of the responses to the individual sounds combined. At that time, Mudry et al. (1977) found a combination-sensitive area in the frog’s auditory thalamus, and Feng et al. (1978) found combination-sensitive neurons tuned to echo delays in the midbrain of the big brown bat. One year after Manabe’s arrival, William E. O’Neill and then Kazuro Kujirai came to my lab as postdoctoral research associates. We found many types of combination-sensitive neurons. Among these, CF/CF neurons tuned to Doppler shifts for processing velocity information and FM–FM neurons tuned to echo delays for processing target ranges were easily recorded. These two types of neurons are separately clustered at the dorsoanterior areas of the auditory cortex and form the velocity (Suga et al., 1983) or distance (Suga and O’Neill, 1979) axis or map, respectively. We published a dozen papers on combination-sensitive neurons. Among them, the longest original article was 53 pages long and became one of my favorite papers (Suga et al., 1983). Thereafter, several postdoctoral research associates came to my lab: Kohichi Tsuzuki, Junsei Horikawa, Dan Margoliash, Masashi Kawasaki, Robert F. Burkard, Hideo Edamatsu, Doug Fitzpatrick, Hayato Misawa, and Atsushi Tanahashi. They particularly contributed to extending our research on combination-sensitive neurons in the auditory cortex. The number of combination-sensitive areas in the auditory cortex increased (Suga, 1990). Two graduate students, John F. Olsen (Olsen and Suga, 1991) and John A. Butman, worked on combination-sensitive neurons in the auditory thalamus and significantly contributed to furthering our understanding of the processing of complex sounds. It became clear that different types of auditory information are processed in a parallel and hierarchical way in the central auditory system.

In addition to combination-sensitive neurons, non-combination-sensitive neurons in the auditory cortex and the inferior colliculus of the mustached bat were studied by several of my collaborators: Isao Saitoh, Taku Hattori, Atsushi Asanuma, and so on. Among their works, I particularly remember these two findings—that the inferior colliculus has the frequencyversus-latency coordinates (Hattori and Suga, 1997) and that long latencies (delay lines) of collicular neurons are created by inhibition (Saitoh and Suga, 1995).

All the research on combination-sensitive neurons and the functional map of the auditory cortex were obtained through neurophysiological studies performed delivering a synthesized biosonar pulse and echo in a soundproof room. Therefore, we had to demonstrate that combination-sensitive neurons responded to echoes when the bat emitted biosonar pulses. Kawasaki and Margoliash placed the mustached bat outside of our 2nd-floor lab window facing a large parking lot. When the bat emitted biosonar pulses, they delivered synthesized echoes to the bat that were variously delayed from the vocalized biosonar pulses and proved that “delay-tuned” FM–FM neurons studied with the synthesized biosonar pulse and echo were indeed tuned to the pair consisting of the vocalized biosonar pulse and the synthesized echo, as predicted (Kawasaki et al., 1988).

Assistant Professor Stephen J. Gaioni (Dept. of Psychology) and I had a research grant from the Air Force Office of Scientific Research to study echolocation behavior in relation to the cortical auditory map. That is, I had extra money and an open position for an extra postdoctoral research associate. Hiroshi Riquimaroux, who had a Ph.D. in psychology applied for this position. So, Gaioni and Riquimaroux conditioned the mustached bat for either fine frequency or time interval discriminations and then inactivated either the cortical DSCF area which systematically represents the frequency of sound with very sharply frequency-tuned DSCF neurons or the cortical FM–FM area which systematically represents a time interval (i.e., echo delay) between two sounds with FM–FM combination-sensitive neurons. As expected, inactivation of the DSCF area disrupted the frequency but not the delay discriminations, whereas inactivation of the FM–FM area disrupted the delay but not the frequency discriminations (Riquimaroux et al., 1991). Through this experiment, we learned (1) acoustic stimuli for behavioral experiments should be designed according to behaviorally relevant sounds, (2) inactivation experiments of each cortical auditory area to examine its auditory function should be designed in relation to its functional organization electrophysiologically explored, and (3) the auditory cortex which is cochleotopically (tonotopically) organized plays a role in fine frequency discrimination, not in course frequency discrimination.

By 1993, the response properties of cortical auditory neurons and the neurophysiological map of the auditory cortex of the mustached bat had been extensively studied with acoustic stimuli designed on species-specific biosonar pulses and their echoes. Although further important data were still coming out at the time, I thought that it was time to study how species-specific communication sounds are processed in the auditory cortex that is highly specialized for processing biosonar information. Are there cortical areas specialized for processing communication sounds? Are the areas specialized for processing biosonar information also involved in processing communication sounds? When Jagmet S. Kanwal, Sumiko Matsumura, and Kevin K. Ohlemiller joined my lab, it was indeed the time to study the responses of cortical auditory neurons and the cortical map in terms of the processing of species-specific communication sounds. As the first step, the communication sounds of the adult mustached bat were classified. We were surprised with the complexity of the communication sounds: there were at least 33 discrete types of syllables that could be further classified as 19 single syllables, 14 composites and three subsyllables (Kanwal et al., 1994). Acoustic stimuli were synthesized by utilizing these communication sounds (Ohlemiller et al., 1994) and used for neurophysiological studies, as suggested by Suga (1992). It then became clear that cortical neurons specialized for processing biosonar information are also involved in processing communication sounds that have acoustic properties similar to, but not the same as, those of biosonar pulses, and that neurons change their tuning according to a difference in the amplitude spectrum between the biosonar pulses and communication sounds (Ohlemiller et al., 1996).

When the project on the processing of communication sounds was progressing, I considered that the corticofugal (descending) auditory system had not been appropriately studied and that we could perform innovative research on it. So, we started to study the function of the corticofugal auditory system. Thus, my lab had three projects going at that time: #1: further studies on the cortical representation of biosonar information conducted by Heibin Teng; #2: cortical processing of communication sounds conducted by Kanwal and others; and #3: corticofugal modulation of collicular neurons conducted by Jun Yan and others. The research project on the cortical processing of communication sounds was taken on by Kanwal for his research as an assistant professor at Georgetown University. I compared projects #2 and #3 and decided to stop project #2 in my lab and concentrate on project #3 because project #2 had been in my mind for many years and was not fresh for me, whereas I was strongly motivated to perform innovating research on the function of the corticofugal system.

Functions of the Corticofugal Auditory System

It had been considered that auditory signal processing is performed through divergent and convergent projections of neurons in the ascending auditory system (Covey and Casseday, 1999; Suga, 1990), although the auditory cortex sends out descending nerve fibers much more than the thalamocortical ascending nerve fibers. The corticofugal auditory system forms multiple feedback loops, so the exploration of its function is quite challenging. By the middle of the 1990s, progress in the neurophysiology of the corticofugal system was very limited and neurophysiological data of corticofugal effects on thalamic and midbrain auditory neurons had been controversial: (1) only or predominantly inhibitory, (2) only or predominantly excitatory, or (3) equally excitatory or inhibitory. These data, regardless of the excitatory or inhibitory effect, indicate that one of the corticofugal functions can be nonspecific gain control. However, I strongly felt that the corticofugal system should have much more elegant functions than simple gain control because there is a much larger number of corticofugal fibers than thalamocortical fibers.

I had noticed a significant problem in all the neurophysiological research on the corticofugal system, that is, cortical activation by electric stimulation and cortical inactivation by a drug or cooling were too widely spread to explore corticofugal function, even in the experiments that performed so-called focal activation or inactivation. To study the function of the corticofugal system, I considered (1) the tuning of stimulated cortical and recorded subcortical neurons should be first measured because the cortical and subcortical neurons both are tuned to particular values of acoustic parameters, (2) electric stimulation or a drug application for activation or inactivation should be highly focal except for the initial phase of corticofugal research, and (3) corticofugal effects on subcortical neurons should be evaluated with regard to the relationship in tuning between the stimulated or inactivated cortical neurons and the recorded subcortical neurons. Therefore, our research performed since 1995 has been designed on this philosophy.

The rapid progress in our research on the function of the corticofugal system depended on excellent collaborators of mine. Jun Yan (Yan and Suga, 1996), Yungfeng Zhang (Zhang et al., 1997), and Wei Yan (Yan and Suga, 1998) made several important discoveries in the initial phase of this project. Then, Syed A. Chowdhury, Xiaofeng Ma, Masashi Sakai, Zhongju Xiao, Yongkui Zhang, and Jie Tang extended the research on this project. We first found that repetitive stimulation of the auditory cortex with 0.2 ms, 100 nA electric pulses evoked changes in the response properties of subcortical auditory neurons. Then, we found that the stimulation also evoked changes in the response properties of cortical auditory neurons (Suga et al., 2000, 2002) and even changes in the cochlear hair cells when the rate of the stimulation was high (Xiao and Suga, 2002a), and that all the subcortical changes originate from the cortical changes as reviewed by Suga and Ma (2003). The most basic findings of ours are described below.

Focal electric stimulation of cortical auditory neurons facilitates the response and sharpens the tuning of cortical and subcortical auditory neurons whose tuning matches that of the stimulated cortical neurons, whereas it slightly suppresses the response and shifts the tuning of cortical and subcortical neurons whose tuning does not match the stimulated cortical ones. We named this corticofugal function “egocentric selection,” which is the improvement of cortical and subcortical auditory signal processing and the adjustment of a neural representation (representational map) of an acoustic parameter in the cortex and subcortical auditory nuclei. In other words, egocentric selection occurring in the subcortical nuclei improves and adjusts the cortical input for signal processing and representation in the cortex (Suga et al., 2000, 2002). Focal inactivation of cortical auditory neurons shifts the tuning of subcortical neurons in the opposite direction to the shift evoked by the focal electric stimulation. However, nonfocal or uniform inactivation of cortical auditory neurons, including cortical neurons matched and unmatched to recorded subcortical neurons, reduces the auditory responses of the subcortical neurons but does not shift their tuning (Yan and Suga, 1999; Zhang and Suga, 1997).

There are two types of tuning shifts of the subcortical neurons: shifts toward and away from the tuning of the stimulated cortical neurons, which are, respectively, named “centripetal” and “centrifugal” shifts. The centripetal and centrifugal shifts of the tuning of subcortical neurons, respectively, result in the expanded and compressed reorganizations of the subcortical auditory map. An antagonist of GABA-A receptors applied to the auditory cortex changes the compressed reorganization into the expanded reorganization. Strong inhibition relative to excitation in the auditory cortex apparently evokes the compressed reorganization. The expanded reorganization has been found in the auditory system as well as in the visual and somatosensory systems of several species of mammals, whereas the compressed reorganization has thus far been found in the subsystems of the auditory system of the mustached bat which are highly specialized for processing certain types of biosonar information. Our results, however, indicate that the mustached bat and nonbat species basically share identical corticofugal neural mechanisms, and that the specialization in the mustached bat is partly created by strengthening inhibition in the auditory cortex (Xiao and Suga, 2002b).

Electric stimulation of the nervous system to explore the function of its particular portion is an old technique, but it is still a valuable technique. For example, focal electric stimulation of the inferior colliculus evokes the BF shifts of the collicular neurons surrounding the stimulated collicular neurons, just like those elicited by cortical electric stimulation. Inactivation of the auditory cortex blocks the development of these BF shifts (Zhang and Suga 2005). Electric stimulation of the ventral division of the medial geniculate body of the house mouse evokes the collicular BF shift, and this collicular BF shift is blocked by inactivation of the auditory cortex (Wu and Yan, 2007). Therefore, it becomes clear in the big brown bat and house mouse that the plastic changes in the auditory cortex elicited by focal electric stimulation of the subcortical auditory nuclei are transmitted back to the subcortical auditory nuclei.

Corticofugal Feedback and Tone-Specific Plasticity Elicited by Auditory Fear Conditioning

Because the effects of the cortical electric stimulation lasted up to 3.5 hours, I thought that corticofugal modulation was involved in plastic changes in the central auditory system caused by learning. So, we started doing research to explore the relationship between plastic changes evoked by the corticofugal system and auditory fear conditioning, although no one speculated that corticofugal feedback would be involved in the plasticity elicited by auditory fear conditioning. In our first experiment (Gao and Suga, 1998), we immediately noticed that the neural circuit model proposed by Weinberger (1998) to explain the cortical tone-specific changes elicited by the conditioning was most likely incorrect or incomplete. Enquan Gao (Gao and Suga, 1998, 2000), Weiqing Ji (Ji et al., 2001, 2005; Ji and Suga, 2003) and Xiaofeng Ma (Ma and Suga, 2001, 2003) established that corticofugal feedback and the somatosensory cortex, which were neglected by the Weinberger model, play an important role in plastic changes in the central auditory system evoked by the conditioning. Gao and Suga (1998) proposed the neural circuit for the tone-specific changes, represented by BF shifts elicited by auditory fear conditioning. The Gao-Suga model, elaborated upon by Suga and his collaborators (2000), states that small or subthreshold short-term cortical and collicular BF shifts specific to a conditioning tonal stimulus (CS) are evoked by the neural circuit within the auditory cortex and corticofugal feedback loops activated by the CS alone, and that this cortical BF shift is augmented and changed into the long-term BF shift by acetylcholine released into the auditory cortex from the cholinergic basal forebrain. In this model, the cholinergic basal forebrain is activated by the auditory and somatosensory cortices via the association cortex and the amygdala where the CS is associated with an unconditioned leg-stimulus (US). In addition, CS–US association may also occur in the association cortex. The collicular BF shift is increased by the augmented cortical BF shift through corticofugal feedback and contributes to the development of the large long-term cortical BF shift (Suga and Ma, 2003). This model is fundamentally different from the Weinberger model (1998). The Gao-Suga model proposes that the small short-lasting cortical BF shift is evoked by the neural net intrinsic to the central auditory system without CS–US association, whereas the Weinberger model proposes that it is evoked by the multisensory thalamic nuclei, only after CS–US association occurs in these nuclei.

Retirement

I retired from “teaching” at the age of 70½ years (June 2004). However, I have three soundproof chambers with many instruments, rooms for my research associates, and a room for my lab technician, in addition to my office. So, my research situation hasn’t changed at all. The only change due to my retirement is that I have no teaching duties. What a wonderful situation I am in! I am fortunate to have three research associates and three ongoing projects to explore further: (1) the neural circuit for tone-specific plasticity elicited by fear conditioning and nonspecific plasticity elicited by pseudoconditioning, (2) interaction between different auditory cortical areas, and (3) plasticity of the lemniscal and nonlemniscal auditory systems.

What Is Interesting in the Neurophysiology of the Central Auditory System

In physiology and neurophysiology textbooks, the number of pages devoted to vision has dramatically increased relative to that of hearing over the last 40 ∼ 50 years. Professor Vernon B. Mountcastle edited Medical Physiology (C.D. Mosby Co., 1968), and he himself wrote Chapter 65 “Central Neural Mechanisms in Hearing” for this book. He once told me, “Nothing is interesting in the neurophysiology of hearing.” In the early 1980s, when we had published several papers on combination-sensitive neurons, nonauditory physiologists on different occasions said to me, “It is hard to teach auditory neurophysiology. What are interesting topics in the central auditory system to teach to students?” At that time, I had been teaching an undergraduate course, “Sensory Physiology,” and had felt the same way. In book chapters on hearing, the story about cochlear anatomy and physiology had been well written and was interesting enough to excite readers, whereas the story about the central auditory system had been much less interesting, although the tonotopic representation in the auditory system and the neural basis of sound localization had been described.

This is still true, even in recent neuroscience textbooks. They contain an interesting chapter on cochlear anatomy and physiology and, at most, a mediocre chapter on the central auditory system. For hearing, the responses of central auditory neurons to tone bursts have been well studied by changing the values in the frequency, amplitude or time domain, or by changing the values of binaural cues. However, it has apparently been questionable what topics are really interesting, except for the processing of binaural cues. A few hundred papers on hearing have been published every year, and the authors of these papers, including me, have thought that their papers are interesting and important to further the understanding of auditory mechanisms. However, these papers are apparently not particularly interesting to nonauditory neurophysiologists. This may be the reason why textbook chapters on the central auditory system have been mediocre.

The most fundamental neural mechanism for processing sound is creating neural tuning in the frequency, amplitude, time, and spatial domains and sharpening it by inhibition. Sound is the changes in atmospheric pressure in time, so the story of the fundamental neural mechanism should include the processing of sound in the frequency-time and amplitude-time domains. A book chapter on the central auditory system must describe these basic stories and then must introduce the story of the processing of behaviorally relevant sounds after describing the acoustic properties of these behaviorally relevant sounds.

Epilogue

I began my career in auditory neurophysiology according to Professor Dan’s suggestion and learned under Professor Katsuki’s guidance. I think that I entered a field that was just right for me. Since 1970, I have had many postdoctoral research associates. All of them, except four, came to my lab without any experience in working on the central auditory system. These research associates learned how to perform auditory neurophysiology within 3 ∼ 4 months in my lab and then performed excellent goal-oriented research for 1 to 3 years. The progress of my (our) research has depended on their talent and devotion to the research. My wife, Hiroko Suga, has been a consistent source of support to me since 1963, without which my activity in research might not have been so smooth and enjoyable. I sincerely acknowledge the contributions of all these individuals.

I like mountains, climbing up beyond the timberline to see a vast open space. When I went to The Nature Place in Colorado Springs, I found a small, inspirational plaque in the computer-telephone room that said, “History is not closed. The future remains open and depends on our imagination and bold initiatives.”

(My photograph used for this autobiography was taken sometime in the early 1980s when I was most actively engaged in research.)

Selected Bibliography

Aitkin LM, Webster WR. Medial geniculate body of the cat: organization and responses to tonal stimuli of neurons in ventral division. J Neurophysiol 1972; 35:365–380.

Arthur RM, Pfeiffer RR, Suga N. Properties of “two-tone inhibition” in primary auditory neurones. J Physiol 1971;212:593–609.

Calford MB, Webster WR, Semple MM. Measurement of frequency selectivity of single neurons in the central auditory pathway. Hear Res 1983;11:395–401.

Casseday JH, Covey E. Frequency tuning properties of neurons in the inferior colliculus of an FM bat. J Comp Neurol 1992;319:34–50.

Condon CJ, White KR, Feng AS. Processing of amplitude-modulated signals that mimic echoes from fluttering targets in the inferior colliculus of the little brown bat, Myotis lucifugus. J Neurophysiol 1994;71:768–784.

Cooper FS, Delattre PC, Liberman AM, Borst JM, Gerstman LJ. Some experiments on the Perception of Synthetic Speech Sounds. J Acoust Soc Amer 1952;22: 597–606.

Covey E, Casseday JH. Timing in the auditory system of the bat. Annu Rev Physiol 1999;61:457–476.

Ehret G, Moffat AJM. Inferior colliculus of the house mouse II. Single unit responses to tones, noise and tone-noise combinations as a function of sound intensity. J Comp Physiol 1985;156:619–635.

Evans EF. The frequency response and other properties of single fibres in the guineapig cochlear nerve. J Physiol 1972;226:263–287.

Evans EF, Ross HF, Whitfield IC. The spatial distribution of unit characteristic frequency in the primary auditory cortex of the cat. J Physiol 1965;179:238–247.

Feng AS, Simmons JA, Kick SA. Echo detection and target-ranging neurons in the auditory system of the bat Eptesicus fuscus. Science 1978;202:645–648.

Frishkopf LS, Goldstein MH Jr. Responses to acoustic stimuli from single units in the eighth nerve of the bullfrog. J Acoust Soc Amer 1963;35:1219–1228.

Galambos R. Neural mechanisms of audition. Physiol Rev 1954;34:497–528.

Galambos R, Davis H. Inhibition of activity in single auditory nerve fibers by acoustic stimulation. J Neurophysiol 1944;7:39–57.

Gao E, Suga N. Experience-dependent corticofugal adjustment of midbrain frequency map in bat auditory system. Proc Natl Acad Sci USA 1998;95:12663–12670.

Gao E, Suga N. Experience-dependent plasticity in the auditory cortex and the inferior colliculus of bats: role of the corticofugal system. Proc Natl Acad Sci USA 2000;97:8081–8086.

Hattori T, Suga N. The inferior colliculus of the mustached bat has the frequencyvs.-latency coordinates. J Comp Physiol–A 1997;180:271–284.

Ji W, Gao E, Suga N. Effects of acetylcholine and atropine on plasticity of central auditory neurons caused by conditioning in bats. J Neurophysiol 2001;86: 211–225.

Ji W, Suga N. Development of reorganization of the auditory cortex caused by fear conditioning: effect of atropine. J Neurophysiol 2003;90:1904–1909.

Ji W, Suga N, Gao E. Effects of agonists and antagonists of NMDA and ACh receptors on plasticity of bat auditory system elicited by fear conditioning. J Neurophysiol 2005;94:1199–1211.

Kanwal JS, Matsumura S, Ohlemiller KK, Suga N. Analysis of acoustic elements and syntax in communication sounds emitted by the mustached bat. J Acoust Soc Amer 1994;96:1229–1254.

Katsuki Y, Murata K, Suga N, Takenaka T. Single unit activity in the auditory cortex of an unanesthetized monkey. Proc Jap Acad 1960;36:435–438.

Katsuki Y, Suga N, Kanno Y. Neural mechanism of the peripheral and central auditory system in monkeys. J Acoust Soc Amer 1962;34:1396–1410.

Katsuki Y, Sumi T, Uchiyama H, Watanabe T. Electric responses of auditory neurons in cat to sound stimulation. J Neurophysiol 1958;21:569–588.

Katsuki Y, Watanabe T, Suga N. Interaction of auditory neurons in response to two sound stimuli in cat. J Neurophysiol 1959;22:603–623.

Kawasaki M, Margoliash D, Suga N. Delay-tuned combination-sensitive neurons in the auditory cortex of the vocalizing mustached bat. J Neurophysiol 1988;59: 623–635.

Kiang NYS, Watanabe T, Thomas EC, Clark LF. Discharge patterns of single fibers in the cat’s auditory nerve. MIT Research Monograph 1965;35:1–154.

Knudsen EI, Konishi M. A neural map of auditory space in the owl. Science 1978;200:795–797.

Liberman AM, Delattre PC, Gerstman LJ, Cooper FS. Tempo of frequency change as a cue for distinguishing classes of speech sounds. J Exp Psychol 1956;52: 127–137.

Liberman AM, Ingemann F, Lisker L, Delattre P, Cooper FS. Minimal rules for synthesizing speech. J Acoust Soc Amer 1959;31:1490–1499.

Liu W, Suga N. Binaural and commissural organization of the primary auditory cortex of the mustached bat. J Comp Physiol-A 1997;181:599–605.

Ma X, Suga N. Plasticity of bat’s central auditory system evoked by focal electric stimulation of auditory and/or somatosensory cortices. J Neurophysiol 2001;85: 1078–1087.

Ma X, Suga N. Augmentation of plasticity of the central auditory system by the basal forebrain and/or somatosensory cortex. J Neurophysiol 2003;89:90–103.

Manabe T, Suga N, Ostwald J. Aural representation in the doppler-shifted-CF processing area of the primary auditory cortex of the mustache bat. Science 1978;200:339–342.

Merzenich MM, Knight PL, Roth GL. Representation of cochlea within primary auditory cortex in the cat. J Neurophysiol 1975;38:231–249.

Mudry KM, Constantin-Paton M, Capranica RR. Auditory sensitivity of the diencephalon of the leopard frog Rana p. pipiens. J Comp Physiol 1977;114:1–13.

Nomoto M, Suga N, Katsuki Y. Discharge pattern and inhibition of primary auditory nerve fibers in the monkey. J Neurophysiol 1964;27:768–787.

Ohlemiller KK, Kanwal JS, Butman JA, Suga N. Stimulus design for auditory neuroethology: synthesis and manipulation of complex communication sounds. Aud Neurosci 1994;1:19–37.

Ohlemiller KK, Kanwal JS, Suga N. Facilitative responses to species-specific calls in cortical FM-FM neurons of the mustached bat. Neuroreport 1996;7:1749–1755.

Olsen JF, Suga N. Combination-sensitive neurons in the medial geniculate body of the mustached bat: encoding of target range information. J Neurophysiol 1991;65:1275–1296.

Pfeiffer RR. A model for two-tone inhibition of single cochlear-nerve fibers. J Acoust Soc Amer 1970;48(Suppl 2):1373.

Pfeiffer RR, Molnar CE. Cochlear nerve fiber discharge patterns: relationship to the cochlear microphonic. Science 1970;167:1614–1616.

Potter RK, Kopp GA, Kopp HG. Visible speech. New York: Dover, 1966.

Riquimaroux H, Gaioni SJ, Suga N. Cortical computational maps control auditory perception. Science 1991;251:565–568.

Rupert A, Moushegian G, Galambos R. Unit responses to sound from auditory nerve of the cat. J Neurophysiol 1963;26:449–465.

Sachs MB, Kiang NY. Two-tone inhibition in auditory-nerve fibers. J Acoust Soc Amer 1968;43:1120–1128.

Saitoh I, Suga N. Long delay lines for ranging are created by inhibition in the inferior colliculus of the mustached bat. J Neurophysiol 1995;74:1–11.

Schreiner CE, Mendelson JR. Functional topography of cat primary auditory cortex: distribution of integrated excitation. J Neurophysiol 1990;64:1442–1459.

Schrenier CE, Sutter ML. Topography of excitatory bandwidth in cat primary auditory cortex: single-neuron versus multiple-neuron recordings. J Neurophysiol 1992;68:1487–1502.

Suga N. Functional organization of two tympanic neurons in noctoid moths. Jap J Physiol 1961;11:666–677.

Suga N. Change in the toughness of the chorion of fish eggs. Embryologia 1963;8: 63–74.

Suga N. Analysis of frequency modulated sounds by auditory neurones of echolocating bats. J Physiol 1965a;179:25–53.

Suga N. Functional properties of auditory neurones in the cortex of echo-locating bats. J Physiol 1965b;181:671–700.

Suga N. Ultrasonic production and its reception on some neotropical tettigoniidae. J Insect Physiol 1966;12:1039–1050.

Suga N. Electro-sensitivity of specialized and ordinary lateral line organs of electric fish, Gymnotus carapo. In Cahn P, ed. Lateral line detectors. Bloomington: Indiana University Press, 1967;395–409.

Suga N. Analysis of frequency-modulated and complex sounds by single auditory neurons of bats. J Physiol 1968;198:51–80.

Suga N. Classification of inferior collicular neurones of bats in terms of responses to pure tones, FM sounds, and noise bursts. J Physiol 1969;200:555–574.

Suga N. Responses of inferior collicular neurones of bats to tone bursts with different rise times. J Physiol 1971;217:159–177.

Suga N. Analysis of information-bearing elements in complex sounds by auditory neurons of bats. Audiol 1972;11:58–72.

Suga N. Feature extraction in the auditory system of bats. In Moller AR, ed. Basic mechanisms in hearing. New York, NY: Academic Press, 1973;675–742.

Suga N. Amplitude-spectrum representation in the Doppler-shifted-CF processing area of the auditory cortex of the mustache bat. Science 1977;196:64–67.

Suga N. Cortical computational maps for auditory imaging. Neural Networks 1990;3:3–21.

Suga N. Philosophy and stimulus design for neuroethology of complex-sound processing. Phil Trans Roy Soc Lond 1992;B336:423–428.

Suga N. Sharpening of frequency tuning by inhibition in the central auditory system: tribute to Yasuji Katsuki. Neurosci Res 1995;21:287–299.

Suga N, Gao E, Zhang Y, Ma X, Olsen JF. The corticofugal system for hearing: recent progress. Proc Natl Acad Sci USA 2000;97:11807–11814.

Suga N, Jen PH. Peripheral control of acoustic signals in the auditory system of echolocating bats. J Exp Biol 1975;62:277–311.

Suga N, Jen PH-S. Disproportionate tonotopic representation for processing speciesspecific CF-FM sonar signals in the mustache bat auditory cortex. Science 1976;194:542–544.

Suga N, Jen PH-S. Further studies on the peripheral auditory system of “CF-FM” bats specialized for fine frequency analysis of Doppler-shifted echoes. J Exp Biol 1977;69:207–232

Suga N, Katsuki Y. Central mechanism of hearing in insects. J Exp Biol 1961;38: 545–558.

Suga N, Katsuki Y. Vision in insects in terms of the electrical activities of the descending nerve fibres. Nature 1962;194:658–660.

Suga N, Ma X. Multiparametric corticofugal modulation and plasticity in the auditory system. Nat Rev Neurosci 2003;4:783–794.

Suga N, Manabe T. Neural basis of amplitude-spectrum representation in auditory cortex of the mustached bat. J Neurophysiol 1982;47:225–255.

Suga N, Neuweiler G, Moller J. Peripheral auditory tuning for fine frequency analysis by the CF-FM bat, Rhinolophus ferrumequinum: III cochlear microphonic and auditory nerve responses. J Comp Physiol 1976;106:111–125.

Suga N, O’Neill WE. Neural axis representing target range in the auditory cortex of the mustached bat. Science 1979;206:351–353.

Suga N, O’Neill WE, Kujirai K, Manabe T. Specificity of combination-sensitive neurons for processing of complex biosonar signals in the auditory cortex of the mustached bat. J Neurophysiol 1983;49:1573–1626.

Suga N, Schlegel P. Neural attenuation of responses to emitted sounds of echolocating bats. Science 1972;177:82–84.

Suga N, Schlegel P, Shimozawa T, Simmons JA. Orientation sounds evoked from echolocating bats by electrical stimulation of the brain. J Acoust Soc Amer 1973;54:793–797.

Suga N, Shimozawa T. Site of neural attenuation of responses to self-vocalized sounds in echolocating bats. Science 1974;183:1211–1213.

Suga N, Tsuzuki K. Inhibition and level-tolerant frequency-tuning curves in the auditory cortex of the mustached bat. J Neurophysiol 1985;53:1109–1145.

Suga N, Xiao Z, Ma X, Ji W. Plasticity and corticofugal modulation for hearing in adult animals. Neuron 2002;36:9–18.

Suga N, Zhang Y, Yan J. Sharpening of frequency tuning by inhibition in the thalamic auditory nucleus of the mustached bat. J Neurophysiol 1997;77:2098–2114.

Tunturi AR. Audio frequency localization in the acoustic cortex of the dog. Am J Physiol 1944;141:397–403.

Tunturi AR. Components of the evoked potential in the MES auditory cortex. Am J Physiol 1960;199:529–534.

Weinberger NM. Physiological memory in primary auditory cortex: characteristics and mechanisms. Neurobiol Learn Mem 1998;70:226–251.

Woolsey CN. Auditory areas I, II, and Ep: cochlear representation, afferent paths and interconnections. Bull Johns Hopkins Hosp 1960;106:127–142.

Woolsey CN, Walzl EM. Topical projection of nerve fibers from local regions of the cochlea to the cerebral cortex of the cat. Bull Johns Hopkins Hosp 1942; 71:315–344.

Wu Y, Yan J. Modulation of the receptive fields of midbrain neurons elicited by thalamic electrical stimulation through corticofugal feedback. J Neurosci 2007;27:10651–10658.

Xiao Z, Suga N. Modulation of cochlear hair cells by the auditory cortex in the mustached bat. Nature Neurosci 2002a;5:57–63.

Xiao Z, Suga N. Reorganization of the cochleotopic map in the bat’s auditory system by inhibition. Proc Natl Acad Sci USA 2002b;99:15743–15748.

Yan J, Suga N. Corticofugal modulation of time-domain processing of biosonar information in bats. Science 1996;273:1100–1103.

Yan W, Suga N. Corticofugal modulation of midbrain frequency map in bat auditory system. Nature Neurosci 1998;1:54–58.

Yan J, Suga N. Corticofugal amplification of facilitative auditory responses of subcortical combination-sensitive neurons in the mustached bat. J Neurophysiol 1999;81:817–824.

Yang L, Pollak GD, Resler C. GABAergic circuits sharpen tuning curves and modify response properties in the mustache bat inferior colliculus. J Neurophysiol 1992;68:1760–1774.

Zhang Y, Suga N. Corticofugal amplification of subcortical responses to single tone stimuli in the mustached bat. J Neurophysiol 1997;78:3489–3492.

Zhang Y, Suga N. Corticofugal feedback for collicular plasticity evoked by electric stimulation of the inferior colliculus. J Neurophysiol 2005;94:2676–2682.

Zhang Y, Suga N, Yan J. Corticofugal modulation of frequency processing in bat auditory system. Nature 1997;387:900–903.

Hans Thoenen

BORN:

Zweisimmen, Switzerland

May 5, 1928

EDUCATION:

University of Bern and Innsbruck, Certificate of Medicine (1953)

University of Bern, Doctorate in Medicine (1957)

University of Basel, “Habilitation” in Experimental Pharmacology (1969)

APPOINTMENTS:

Staff Scientist, Department of Experimental Medicine, Hoffman-LaRoche, Basel (1961)

Visiting Scientist National Institute of Mental Health (1968–1969)

Research Group Leader Neurobiology, Biocenter, University of Basel (1971)

Director Max Planck Institute of Neurobiology, Munich (1977)

Director Emeritus Max Planck Institute of Neurobiology (1996)

HONORS AND AWARDS (SELECTED):

Member Deutsche Akademie der Naturforscher, Leopoldina (1979)

Feldberg Prize (1980)

Cloetta Prize (University of Zurich, 1985)

Wakeman Award (Duke University, 1988)

Honorary Doctorate, University of Zurich (1992)

Ipsen Prize (1994)

Charles A. Dana Award (1994)

Ralph W. Gerard Prize (Society for Neuroscience, 1995)

Foreign Associate National Academy of Sciences, United States (1996)

Bristol-Myers Squibb Award (1999)

Honorary Doctorate, University of Würzburg (1997)

Corresponding Member, Swiss Academy of Medical Sciences (2003)

Hans Thoenen elucidated the mechanism of action of 6-hydroxydopamine that led to the serendipitous detection of trans-synaptic enzyme induction. Subsequently his laboratory made crucial contributions to the field of neurotrophic factors, including the cloning of brain derived neurotrophic and ciliary neurotrophic factor and the analysis of their physiological functions.

Hans Thoenen

When I was invited to contribute an autobiographical chapter to the History of Neuroscience in Autobiography I was very hesitant about it. My scientific career, at least at the beginning, was tortuous and certainly anything but a model career. Ideally, the description of such a career should set an example to young scientists how to organize their scientific life to become successful. However, in this respect I can barely provide a positive example, more likely how not to do it.

My main motivation for doing research evolved from a combination of profound curiosity and a taste for adventure, to embark to new territories with all its excitements and risks.

A Boy from the Swiss Mountains

In the biographies of many successful scientists, the wish to become a scientist was already apparent in their early childhood. Barely out of their diapers, they had their own laboratory and were reading the biographies of their scientific idols. My laboratory was the natural environment of a mountain valley in the Swiss Alps. We observed plants and animals in all seasons, and our imagination was stimulated, for example, by finding the remains of a hare together with the tracks of a fox in the snow. Our taste for adventure was satisfied by exploring rock caves with self-made carbide lamps that not too seldom failed. And when not outdoors, I became acquainted with many different occupations such as carpenters, plumbers, coopers, ski and sledge makers, and many more. When I visited their workshops they were more amused than annoyed as I pestered them with questions why they were doing what in which way.

Before I went to school my reading and mathematical abilities were very limited. When I participated in my first ski race I had a high number that was beyond the limits of my numerical knowledge so the amused starter had to say, “Come on Hansi, it’s your turn now.” I did not shine in this first race. Later on I did much better and won many races in different age categories.

Very soon I also made my first attempts to climb the rocky bastions surrounding my home valley, partly under the supervision of experienced mountaineers but to an increasing extent independently. For quite a while I envisaged the possibility to earn my living as a ski instructor and mountain guide. However, I then decided, with the encouragement of my parents, to invest some time in preparation for entering high school in Burgdorf, a small town at the entrance to the Emmental. The preparation was minimal. It consisted largely of a crash course in Latin, given by the local reverend, and some extra lessons in geometry and algebra.

Ancestors and Family Background

A school teacher traced our family back to the thirteenth century, when my paternal ancestors moved from the neighboring Valais to the Simmental. The Simmental, like virtually all the valleys of the Swiss Alps, became overpopulated. The young people were forced to leave, especially those who did not fit into the society, did not go to church, or otherwise did not behave in an orderly way. For a long time virtually the only option was to become a mercenary. Many returned from their exploits as cripples, if at all; only very few came back with a modest fortune.

After mercenaries were no longer in demand, young men still had to leave their home valley, had to emigrate when still teenagers. They were often sent with a one-way ticket to the United States, preferably Wisconsin. Not too seldom these ne’er do wells returned as “the rich uncles from America” and were then courted by their respectable relatives at home. More recently a small proportion of the younger generation had the privilege of going to high school and university. My paternal ancestors enjoyed this privilege. My grandfather was a judge at the castle of Wimmis at the entrance to the Simmental. My father was an M.D. who, initially, had envisaged an academic career. The prerequisite for this was a substantial fortune. The economic crisis after World War I forced him to change to practical medicine. Here, it should be recalled that at the beginning of the twentieth century Switzerland was strongly oriented toward Germany. The main commander of the Swiss Army was related to the Bismarck family and, because my father had invested his money in German stocks and bonds, he lost everything.

However, the strong orientation toward Germany had also its limits. My grandfather, as the representative of the Bernese government, had to welcome the German Emperor immediately before World War I, when Wilhelm II came to the Simmental to shoot chamois. My grandfather was not only supposed to welcome him but the rigid protocol demanded him also to bow low. My grandfather strictly refused to do so, considering this to be an unbearable humiliation. Maybe my limited belief in authority has some genetic roots.

High School Education in a Small Town

I entered the high school in Burgdorf with minimal preparation, as I mentioned earlier. The entry criteria for boys—seldom girls—from the mountains were very generous. We were given a year to catch up to the required level. It was well known that the children from the mountains were not lacking in motivation. For the majority of their parents this was a heavy financial burden. Often they and their relatives had to pool their resources to send just one student to high school and university.

At the age of 14 I was in Burgdorf completely on my own. I had my own room, and nobody checked my coming home or supervised my homework. This promoted my independence and sense of responsibility.

The time in Burgdorf was an enjoyable and very fruitful one. We were taught in small classes and had outstanding teachers, highly motivated to give us the best possible education. Some of them were university professors, but their salaries were so miserable that they had to work as high school teachers to make ends meet.

University Education

After obtaining my Maturitätszeugnis (school-leaving certificate) in 1947, I went to the University of Bern to study medicine. I originally wanted to study biochemistry and medicine in parallel. Unfortunately this was not possible at that time. The first year at medical school perfectly met my gusto. We had very small classes and received our basic training, including practical courses, together with physicists and chemists. The rest of the education at the medical school corresponded to the general contemporary standard. It was common practice to study for part of the time at another university. My choice of Innsbruck was governed more by the prospect of mountaineering in the Austrian Alps than by specific aspects of medical training that were offered there and not in Bern. The time in Innsbruck was, nevertheless, very instructive. Most of the students were much older than I was. They had been drafted at an early age, before they had finished high school. A large number had been awarded their school-leaving certificate for destroying tanks or shooting down planes. At the end of the war many of them spent years in Russian prisoner camps in Siberia. An Austrian fellow-student who introduced me to the climbs around Innsbruck was one of the only five survivors of a Gebirgsjäger (mountain troop) regiment. His reaction to the war experiences was rather exceptional. He remained an enthusiastic rock climber and loved strenuous outdoor activities. The attitude of the majority of the students with similar war experiences was completely different, along the lines of “For years we have been freezing, starving, and lying in the mud; enough is enough.”

From Clinical to Experimental Research

During my medical studies it became clear that practical medicine was not my professional goal. I was interested in basic physiological functions including pathogenic mechanisms. I was not ready to blindly accept the “rigid therapeutic recipes” that were not infrequently controversial and the subject of “religious wars” between different “clinical schools.”

After a period of military service and a year of training in general pathology at the University of Bern, I was accepted as an assistant in the Department of Internal Medicine led by Hans Staub in Basel. He was originally a pharmacologist and in spite of not being a full-blown clinician became head of the Department of Internal Medicine. This was a very unusual setup, to some extent way ahead of its time, particularly for the rather conservative University of Basel. Although there were therapeutic schemes for given clinical situations, Staub expected a rational justification for the treatment of every individual patient.

By the time I joined his department he had already suffered a serious heart attack. Although he encouraged his assistants to pursue clinical research projects, he no longer had the strength to supervise them adequately and to ensure they had sufficient time to work in the lab besides their heavy caseload of 25 patients each. It became clear to me that the quality of research I could accomplish under these circumstances did not meet my expectations. Moreover, even under optimal conditions, I would very soon encounter the ethical and technical barriers that are familiar to those carrying out clinical research with humans. A problem could become really interesting, but it was not possible to take it as far as I would have wanted. Although I would have had the opportunity to pursue a promising clinical career, I decided to change from clinical to pure experimental research.

My first position in experimental research was mediated by Alfred Pletscher, the medical research director of Hoffman La Roche in Basel, who, as a former assistant, still had contacts with the Department of Internal Medicine. I approached him for advice and with the best of intentions he recommended me for a position in a small, newly founded research center, mainly supported by Hoffmann La Roche. My experience was so disappointing and even embarrassing that I refrain from giving the details of the research projects I was supposed to pursue. This first position ended one Christmas morning when I was fired for reasons of “scientific incapability and insubordination.” The label of “incapability” was based on the fact that I did not find what my boss expected. The label of “insubordination” resulted from my rather undiplomatic way of explaining to him why I could not satisfy his expectations. Although it was a lost year, I learned a very important lesson for my whole life, namely how not to treat my collaborators.

To be Married to the Right Wife

When I informed my wife what had happened on this memorable Christmas morning, she just burst out laughing and told me that she had been expecting such a dramatic end for a long time. Not a word of reproach with respect to my responsibility for my family. Also in the preexperimental period she supported me in every possible manner and encouraged me to participate in a mountaineering expedition to the Himalaya (Everest-Lhotse) when she was pregnant. Because of serious health problems of my father I had to cancel my participation in this expedition. Again, at the end of my clinical time, when I was selected for an expedition of the Swiss Alpine Club to the Peruvian Andes, my wife supported me in every possible way, even though by then we had our two little boys.

The importance of my wife was not confined to the beginning of my scientific career. Later on she had a central function in my research group, first at the Biocenter in Basel and then at the Max Planck Institute in Munich. She was looking after our foreign scientists and their families, helping them to find accommodation, to overcome difficulties with awkward officials at the immigration office, and to cope with everyday problems. For instance, she had to convince desperate Midwest girls that it is perfectly possible to survive without the brand of cornflakes available in the United States from Alaska to Key West and that cheese does not have, at any price, to match the geometry of “Wonder Bread.” In fact my wife became the mother of my department, comforting collaborators when they had personal problems, listening to them and giving advice only when asked. Today young scientists may have difficulties to imagine the existence of such a function. However, at that time, a scientific career was a family enterprise and the function of the wife was clearly understood to be as important as that of the husband.

Basic Research in a Drug Company

In spite of my “scientific incapability and insubordination” label I was offered a position in the Department of Experimental Medicine at Hoffmann La Roche. This position gave me the opportunity to do basic research under much more favorable conditions than would have been possible at the University of Basel. There, the quality of research in the areas I was interested in was rather mediocre.

In the early 1960s Roche started to harvest the fruits of their blockbuster drugs Librium and Valium, and it was the policy of the firm to invest the money, as far as possible, in (basic) research. At the end of the decade this led to the foundation of the Roche Institute of Molecular Biology in Nutley (New Jersey) and the Basel Institute of Immunology. Before these large institutes were founded, a few small basic research groups were created within existing research units. These small groups were expected to do qualified (basic) research without being directly involved in the routine screening. Again, this was initiated by Alfred Pletscher and his “right hand” Alfred Studer. I joined a small research group consisting initially of Albert Hürlimann (with a background in experimental cardiovascular pharmacology) and Willy Haefely (with a background in bacteriology). Before starting my active research in Basel, Roche gave me the opportunity to spend short periods in different laboratories, including the Heymann Institute in Ghent, Belgium, under the directorship of I. Leusen, and the laboratories of H. Blaschko, E. Bülbring, and W. Feldberg in England.

The general topic of our research was the analysis of the physiological function of the sympathetic nervous system as a basis for rational pharmacological modifications. On my return to Basel I began to develop a preparation of the isolated perfused cat spleen. This preparation enabled me to compare the mechanical response of the spleen (perfusion pressure and volume change) to electrical stimulation of the splenic nerves with changes in the norepinephrine output in the perfusion fluid. We found that compounds with antidepressive properties, like Imipramine and Desimipramine, enhanced the volume changes and the perfusion pressure of the spleen in response to the electrical stimulation of the sympathetic splenic nerves. At the same time these compounds increased the concentration of norepinephrine in the perfusion fluid of the spleen. Other drugs, in particular phenoxybenzamine, reduced the mechanical response but nevertheless enhanced the norepinephrine output. Here, I missed an essential mechanism by which phenoxybenzamine enhances the norephinephrine output. I thought that phenoxybenzamine enhanced the norepinephrine output exclusively through an inhibition of reuptake. However, under physiological conditions phenoxybenzamine enhances the norepinephine output also through a negative feedback mechanism that is mediated by norepinephrine and affects a subpopulation of alpha-adrenergic receptors on the sympathetic nerve terminals.

False Adrenergic Transmitters

After these initial experiments on the importance of the reuptake of endogenously secreted norepinephrine, I shifted my attention to the analysis of false adrenergic transmitters. It is important to recall what the state of knowledge was at that time. Immediately before World War II, Hermann Blaschko had already proposed how catecholamine synthesis might proceed from phenylalanine to norepinephrine. When I started my investigations there was only fragmentary information on the individual enzymes and the corresponding cofactors. The enzymes were neither purified nor were antibodies against them available.

When I began my experiments, E. Muscholl and coworkers in Mainz had just demonstrated that alpha-methyldopa, in clinical use as an antihypertensive drug, is metabolized to alpha-methyl-norepinephrine and that this metabolite is released by electrical stimulation of sympathetic nerves. I wanted to investigate the concept of false adrenergic transmitters in more general terms, and Hoffmann La Roche was the ideal place to pursue such a project. A number of young, talented chemists were enthusiastic to synthesize compounds for a rational concept rather than for the purpose of broad general screening, with a “lucky shot” as the only attractive prospect. The sympathetic neurons can be “cheated” by means of false transmitters because the enzymes involved in the synthesis of the adrenergic transmitter are not absolutely specific. The same is true for the amine transporters of the plasma membrane and the storage vesicles. The effects of the proposed false transmitters or corresponding precursors were first analyzed by their depleting action on norepinephrine in sympathetically innervated organs. We analyzed the functional consequences in the isolated perfused spleen, the nictitating membrane of the cat, and the changes in blood pressure of unanesthetized rats. Based on this information we decided whether it was worth initiating a more detailed analysis. If this was the case, the corresponding precursor molecules or the false transmitter itself were labeled with tritium. This enabled their metabolism to be analyzed. I identified these various metabolites by paper chromatography with solvent systems established with the help of our chemists, in particular Albert Langemann. The rate of separation by these solvent systems was very much dependent on temperature. It is amusing to recalling that I spent many (hot) summer nights on an air mattress in my lab—no air conditioning was available—to catch the optimal time point in the separation process.

An important change in the direction of my research took place when Jean-Pierre Tranzer joined Hoffman La Roche. He was an outstanding electron microscopist and decided to leave academia in France to provide to his wife and his five children an appropriate standard of living. He took the opportunity of joining Roche with particular pleasure in view of the prospect of doing, nevertheless, predominantly basic research. Jean-Pierre and I joined forces immediately. We felt that advanced methods of electron microscopy (EM) could help us to arrive at a better, comprehensive understanding of the replacement of the physiological transmitter norepinephrine with false transmitters than biochemical analysis alone.

Only a few years before Jean-Pierre started his work on false adrenergic transmitters, De Robertis in Argentina had identified synaptic vesicles as probable transmitter storage organelles. In the few EM studies of sympathetic nerve terminals the presence of a “dense core” was very variable, depending on the fixation procedure used. Jean-Pierre first improved the fixation and contrasting methods for norepinephrine at the EM level. By contrast with previous findings, he demonstrated that virtually all synaptic vesicles had a dense core and that the intensity of the labeling could be increased by preincubation in medium containing norepinephrine. For false transmitters we could predict whether they could be visualized at the EM level by mimicking the fixation and contrasting procedure in the test tube. In this way we identified 5-hydroxydopamine (5-HODA) as a very useful marker for adrenergic neurons. All synaptic vesicles were densely labeled and the picture was particularly impressive when adrenergic and cholinergic nerve terminals were located in close proximity to each other (Figure 1).

The experiments with 5-HODA also revealed other interesting aspects that it was difficult to interpret correctly at the time. “Reticulum-like” structures were labeled in addition to the synaptic vesicles, although less intensively. We thought that besides the synaptic vesicles there might be an “additional storage compartment” for the adrenergic transmitters. Most likely we identified the precursor compartment of the (small) synaptic vesicles. In contrast to the large dense core vesicles, which are produced in the perikaryon, the small synaptic vesicles are produced as tubulo-reticular precursors. Mature vesicles are formed in the nerve terminals. Such a precursor compartment was recently identified by Wieland Huttner and coworkers. In this precursor compartment the amine transporters are most likely “diluted,” and after one or possibly several cycles of exo/endocytosis the mature synaptic vesicles are formed. This concentration process is linked with the sorting of other specific constituents of the (small) synaptic vesicles. The details of these sorting mechanisms are still not completely understood, for example, how the amine transporters of the plasma membrane and the synaptic vesicles are separated from each other.

Fig. 14.1    Comparison between the replacement of the physiological transmitter norepinephrine by 5-HODA and 6-HODA. After treatment with 5-HODA all the synaptic vesicles (small and large) are filled with electron dense material (A). Immediately adjacent cholinergic nerve terminals (c) remain empty. After treatment with 6-HODA (B) the cholinergic nerve terminals (c) remain intact, do not contain electron dense material, whereas the adrenergic nerve terminals (a) are in different stages of degeneration. (C) Oxidation products of 6-HODA and covalent binding to nucleophilic groups of macromolecules (proteins, nucleic acids).

Detection of The mechanism of Action of 6-Hydroxydopamine (6-HODA)

In parallel to the analysis of 5-HODA, we also investigated its isomer 6-HODA. It also fulfilled the requirements of a false transmitter to be visualized at the EM level in the storage vesicles. From previous experiments by Marthe Vogt in Babraham/Cambridge (U.K.) and the Merck Laboratories in the United States it was known that 6-HODA produced a long-lasting depletion of norepinephrine. We evaluated a broad spectrum of dosage schedules leading to a maximum long-term depletion of norepinephrine in different species, in particular rats and cats (see Thoenen and Tranzer, 1968; Tranzer and Thoenen, 1968). Because we knew that 6-HODA is easily oxidized, we saturated the solutions to be injected intravenously with Argon. We expected that after such treatment the storage vesicles of the adrenergic nerve terminals would be filled with electron-dense material and that this material would remain there for a much longer time than after treatment with 5-HODA.

I will never forget the moment when Jean-Pierre rushed into my lab and said in his beautiful Alsatian dialect “Du müesch sofort cho lüege die si alli futü” (“Come and look quickly, they are all gone”). We rushed to the EM and spent a very long time at the screen. The degenerating adrenergic nerve terminals were located next to intact cholinergic nerve terminals (Figure 1). We repeated the experiments several times and also established the time course of the degeneration. We thought that all this information would be sufficiently interesting for publication in Nature. We were wrong: The paper was rejected out of hand and qualified as a “fixation artifact.” We also received fatherly advice how to fix tissues for EM analysis. Although we had emphasized the selectivity of the effects, the reviewer ignored our statement and our clear experimental evidence for the selectivity of the destructive effect. We were disappointed and angry. Indeed, nobody was qualified to teach Jean-Pierre Tranzer how to prepare tissues for EM examination. Jean-Pierre absolutely refused to contest this decision and to embark on a “discussion with idiots.” We sent the paper to Experientia, a journal that, at that time, had a reputation not very far behind that of Nature and Science. This paper, together with a more extensive paper in Naunyn Schmiedeberg’s Archives, became citation classics and the “fixation artifact” of 6-HODA has been confirmed many thousand times by hundreds of laboratories all over the world.

After having established that the reason for the long-lasting depletion of norepinephrine by 6-HODA was the selective destruction of adrenergic nerve terminals rather than a long-term storage of 6-HODA, the question arose what was the molecular mechanism responsible for this destructive effect. Albert Langemann, who was in charge of the large-scale synthesis of 6-HODA, was continuously confronted with its extreme susceptibility to oxidation. He suggested the formation of a para-quinone derivative and its possible further transformation into a trihydroxyindole (Figure 1). Both of these oxidation products can easily form covalent binding with a variety of nucleophilic groups such as SH, NH2, and phenolic HO-groups. This assumption was first supported by preliminary observations made by Fritz Bigler, who found that after administration of H3–6-HODA a substantial proportion of the radioactivity was covalently bound in sympathetically innervated tissues, whereas 99% of the radioactivity could be extracted after injection of labeled norepinephrine. Thus, the specificity of the destructive effect of 6-HODA seemed to result from its efficient accumulation in adrenergic nerve terminals. As such the destructive effect of 6-HODA is nonspecific as impressively demonstrated when 6-HODA was accidentally injected subcutaneously and produced a local necrosis.

In experiments performed after my return from the laboratory of Julius Axelrod (see below), Alfons Saner and I directly identified by spectroscopy the metabolites of 6-HODA suggested by Albert Langemann.

The extreme reactivity of the oxidation products of 6-HODA had, most probably, disastrous consequences for those scientists who were dealing with large quantities of these oxidation products. It is otherwise hard to understand why all the scientists who were involved in such experiments died a few years later. Albert Langemann died of thyroid cancer, Jean-Pierre Tranzer from acute bleeding into a brain tumor, and Fritz Bigler died of leukemia. I probably escaped the fate of my colleagues because, in experiments I performed with my own hands, I took every possible precaution to prevent 6-HODA from oxidation before I injected it intravenously.

Detection of the Trans-Synaptic Induction of Tyrosine Hydroxylase, a Further Consequence of the “Magic Brown Powder”

Just after the detection of the mechanism of action of 6-HODA, I joined the laboratory of Julius Axelrod at National Institutes of Health in Bethesda, Maryland. I arrived with my family in June 1968 at a time of unrest with violent riots in Washington, D.C., and it took some extra time to get settled.

During this period, when I was not yet working full-time in the lab, I noticed with great interest that Bob Mueller, a young postdoc, had just established an assay for tyrosine hydroxylase (TH). Because I had to give a survey lecture on the occasion of the International Congress of Physiology I thought it would be attractive to document biochemically the effect of 6-HODA not only by a depletion of norepinephrine but also by a drastic reduction of the rate-limiting enzyme of its synthesis. The TH assay was sensitive enough for the high TH concentrations in the adrenal medulla. However, when determining TH activity in sympathetically innervated organs we were sometimes working at the sensitivity limit of the assay. Bob Mueller and I managed to determine TH activity in the highly concentrated homogenates of rat hearts. The supernatants had to be passed over a molecular sizing column to eliminate “low molecular inhibitor(s).” These inhibitors, most likely, reflected the high concentrations of endogenous tyrosine that simply diluted the relatively low specific activity of H3-labeled tyrosine used for the assay. When the first 6-HODA treated rats were ready to be analyzed, Bob left for a short vacation. I was pleased to see that the TH activity in the heart homogenates was drastically reduced. I used the adrenals as controls for the (tricky) assay in the heart. To my great surprise there was a more than 2-fold increase in TH activity. In this context it is important to remember that 6-HODA neither destroys adrenal medullary cells nor the cell bodies of adult adrenergic neurons. The destructive effect is restricted to the sympathetic nerve terminals. I repeated the experiments several times and confirmed the initial observation. Julius Axelrod, who went by the name of Julie, was as keen as we were to pursue this unusual finding. Bob and I joined forces and left our original projects. We assumed that the increase in TH resulted from general stress and activation of the pituitary-adrenocortical axis. Here, we were strongly influenced by the discovery made not long before by Dick Wurtmann and Julie that phenylethanolamine-N-methyltransferase (PMNT) was regulated by glucocorticoids. In fact, besides the marked increase in TH activity there was also a small (about 15%) increase in PMNT activity. To evaluate the importance of the pituitary-adrenocortical axis more specifically as the cause of the 6-HODAmediated TH induction, we repeated our experiments with hypophysectomized animals. However, the TH induction remained unchanged. We then denervated the adrenals unilaterally and demonstrated that we were dealing with a neuronally mediated effect. On the denervated side there was no increase in TH. The enzyme kinetic analysis supported the assumption of an increase in enzyme protein rather than the activation of a given quantity of TH. This view was further supported by the fact that cycloheximide treatment impaired the increase in 6-HODA-mediated TH induction.

In subsequent experiments we found that other drugs like reserpine and phenoxybenzamine, which interfere with the postganglionic sympathetic transmission, had an effect similar to that of 6-HODA. However, the increase in TH was not restricted to the adrenal medulla but also occurred in sympathetic ganglia, and the TH induction was prevented by transsection of the preganglionic sympathetic nerves. Moreover, the very small increase in PMNT activity in the adrenal medulla was shown to be mediated by neuronal activity, that is, it could be blocked by denervation of the adrenals.

Our results were published in Science, Nature, and other prestigious journals and attracted the interest of the scientific community. Other laboratories, which had been working for years on the hydroxylation of phenylalanine and tyrosine, were somewhat annoyed that outsiders were the first to demonstrate the selective induction of a macromolecule through neuronal activity. It was indeed a fortuitous observation that deserves the label of “serendipity.” We can, however, claim the merit of not discarding this “odd observation,” just being satisfied with the drastic reduction of TH in the rat heart by 6-HODA treatment. Trans-synaptic enzyme induction was not the result of an investigation designed to establish it, it resulted from an observation made in a small side project that simply served the purpose of satisfying my pride to present some new unpublished data in a survey lecture.

The period I spent working in Julie’s lab was a very important and productive one. I concentrated almost exclusively on the experiments and hardly ever went to the library. I followed Julie’s advice: “Don’t let yourself be distracted by the literature, read when you’ve done the experiments.” However, if experiments permitted, I attended evening seminars on subjects that included the regulation of enzymes in bacteria. I was impressed to learn that the enzymes involved in a given metabolic pathway were often regulated as functional units, forming so-called operons. I was attracted by this idea and wondered whether such a mechanism might also come into play in mammals for the regulation of the enzymes involved in norepinephrine synthesis.

After my return to Switzerland I took my investigations further and demonstrated that physiological stimuli such as exposure to cold and the stress of swimming also resulted in an induction of TH in adrenal medulla and sympathetic ganglia. After establishing the assays for the other enzymes involved in the synthesis of the adrenergic transmitters (norepinephrine and epinephrine) I was delighted to see that all the experimental conditions that led to an induction of TH also produced an increase in dopamine-β-hydroxylase (DBH). I was not too much disturbed that dopa-decarboxylase (DDC) was not specifically increased because it was already known that this enzyme is also expressed in nonneuronal tissues.

First Experiments with Nerve Growth Factor (NGF)

By the time I was working on trans-synaptic enzyme induction I was aware of the existence of nerve growth factor (NGF). I knew the story of its fortuitous detection, the rich source of the male mouse salivary gland, and the spectacular effects on sensory and sympathetic neurons in vitro and in vivo. I was also aware of the production of an anti-NGF antiserum that provided the first direct evidence that NGF had a physiological function.

I first became more directly interested in NGF through a seminar given by Pietro Angeletti, a senior collaborator of Rita Levi-Montalcini. I wondered whether the dramatic increase in the size of sympathetic ganglia was also reflected by a corresponding increase in TH and DBH as in transsynaptic enzyme induction. So far, the analysis of the biological effects of NGF had virtually exclusively been confined to the morphological analysis. Pietro Angeletti was as keen as I was to work on this. He sent me large quantities of 2.5 S NGF that enabled newborn rats to be treated with 10 mg/kg of NGF a day for 10 days. Pietro carried out the morphological analysis, that is, he determined the total volume of the superior cervical ganglion, and the number of neuronal cell bodies and their diameter. I carried out the biochemical analysis, that is, determined the enzyme levels involved in norepinephrine synthesis. I was thrilled to see that the pattern of NGF-mediated enzyme induction was very similar to that seen in trans-synaptic enzyme induction, including the enzyme kinetic data providing evidence for an increase in the quantity of TH and DBH protein rather than an activation of these enzymes. I imagined two signal transduction pathways funneling into a common end point at the transcriptional level. It is no wonder that, given the scarcity of information available on signal transduction in general, this (naïve) hypothesis proved to be wrong. However, this kind of day-dreaming is an essential part of the day-to-day fun in research.

From Industry Back to University

During my time at NIH, Julie Axelrod told me on several occasions that my future should be in academia. I suspect that he himself took active steps in this direction. Indeed, after my return to Basel I received attractive offers from U.S. universities and research institutes. Although tempted to return to the United States, I had serious concerns due to the ongoing Vietnam War. My teenage boys would have risked being drafted within the next few years. On the other hand, on my return from NIH the atmosphere at Roche had changed. There was increasing pressure on me from intermediate hierarchical levels to become more directly involved in general screening and administration. This would have meant a considerable increase in my salary. Even my wife was approached, but her answer was straightforward: “Do you expect me to choose more money in return for an unhappy husband?” It became clear that I had to make a decision while I was still receiving attractive offers. The productive activities in the Axelrod lab proved to be important when a new multidisciplinary institute, called Biocenter, was founded at the University of Basel. The Biocenter, which represented a bold leap forward, was expected to become a first-class international research institute. I was offered a position as head of a neurobiology research group, first as associate and 2 years later as full professor, accommodated in the Department of Pharmacology. However, my teaching duties in pharmacology were confined to a few lectures in neuropharmacology.

A new curriculum had to be designed to provide the students with an appropriate training. In the first 2 years the main focus was on mathematics, physics, biophysics, and chemistry. This was interspersed with survey lectures in cell biology and neurobiology at the level of Scientific American to encourage students, who were predominantly interested in biology, to accept the initial mathematically oriented training as a prerequisite for the high standard of biological research they were aiming at. These 2 years of basic training were followed by so-called block courses in which the students became acquainted with contemporary methods in genetics, biophysics, biochemistry, cell biology, and neurobiology. The classes were small, about 30 students per year. This permitted a very intensive and individual training, also serving the purpose of showing the students that even the most sophisticated and specialized methods are “doable.”

In 1971–1972 not all the research groups of the Biocenter had been set up. The newly founded Friedrich Miescher Institute of Ciba-Geigy was therefore accommodated in those parts of the Biocenter that were not yet occupied, until the Friedrich Miescher Institute had its own facilities. The Miescher Institute was led by Hubert Bloch, an eminent science leader with a visionary capability to identify gifted young scientists. He encouraged his staff members to participate in the neurobiology block course, and very soon fruitful scientific collaborations developed with Irwin Levitan, Ron Lindsay, Denis Monard, and Frank Salomon. An additional benefit of the contacts with the Friedrich Miescher Institute was the large number of male mice that became available to my research group. They originated from toxicological control groups of Ciba-Geigy. This enabled us to purify our own NGF in large quantities and to expand the spectrum of our research, in particular to the autoradiographic localization of labeled NGF at the light and EM level and a more detailed analysis of the mechanism of action of NGF.

NGF Research at the Biocenter

Detection of the Specific Retrograde Axonal Transport of NGF

After having established the similarity between the selective induction of TH and DBH by NGF and enhanced preganglionic activity, I became interested in the physiological functions of NGF in general. I started to read the original publications of Victor Hamburger and Rita Levi-Montalcini and also became interested in the cocultivation experiments of Geoffrey Burnstock. He had demonstrated that there was a correlation between the density of innervation of the target tissues of sympathetic neurons and the extent of fiber outgrowth these tissues elicited from sympathetic ganglia when cocultivated. This fiber outgrowth could be abolished by the administration of anti-NGF antibodies.

Just after my move to the Biocenter I met a young Australian Ph.D. student, Ian Hendry, who was attending the annual winter school in Zuoz in the Canton Grisons. He expressed interest in working in my lab after finishing his Ph.D. with Les Iversen, Cambridge, U.K. It became never clear to me whether he was more interested in my research or in my skills as a potential ski instructor in the Swiss Alps.

After finishing his Ph.D. Ian came to Basel and put forward the hypothesis that NGF could replace sympathetic target organs. If this hypothesis was correct, NGF had to be transported retrogradely to the cell bodies because the regulation of TH by NGF occurred at the transcriptional level. We therefore injected J125 NGF into the anterior eye chamber and determined the rate of accumulation of radioactivity in the superior cervical ganglion of the injected and contralateral side. There was in fact a greater accumulation of labeled NGF on the injected side and a much lower accumulation on the contralateral side resulting from J125 NGF escaping into the general circulation. This interpretation was supported by autoradiographic experiments showing a weak diffuse labeling of the superior cervical ganglion on the contralateral side. By contrast, on the injected side, the radioactivity was concentrated in a relatively small number of neuronal cell bodies corresponding to the neurons innervating the iris. This interpretation was further supported by the fact that this accumulation could be blocked by transsection of the postganglionic axons or by interference with the axonal transport through local administration of colchicine.

After the departure of Ian Hendry, a young Ph.D. student, Martin Schwab, approached me to ask whether he could perform birth-dating experiments with H3-thymidine in my lab. Martin pursued his thesis in an institute outside the Biocenter where he could not perform these experiments. He finished his thesis very rapidly and became more and more interested in the ongoing projects of my research group. With his basic training in developmental neuroanatomy he was well qualified to take over the analysis of the retrograde axonal transport at the EM level and to include in this analysis also methods of morphometry. In a very short time Martin had acquired all the necessary skills for conventional EM, audoradiography at the EM level, and determination of the size of the different cell compartments of neurons by stereological methods.

Specificity of the Retrograde Axonal Transport of NGF in Sensory Neurons

We now expanded the analysis of the retrograde axonal transport to the sensory neurons by injecting labeled NGF unilaterally into the forepaws. We then analyzed the rate and specificity of the retrograde transport to the corresponding dorsal root ganglia C6–C7. As with injection into the anterior eye chamber, there was a highly selective accumulation of radioactivity in the ganglia of the injected side. The accumulation of J125 NGF was again confined to a relatively small number of heavily labeled neurons. As controls for the specificity of the retrograde axonal transport of J125 NGF we injected labeled proteins with differing physico-chemical properties. Of particular interest was cytochrome C, which has a high isoelectric point like NGF and virtually the same molecular weight. No evidence for a specific retrograde transport of cytochrome C could be demonstrated.

Routine Control Procedure Opens up a New Field of Research

To evaluate the possibility of a specific retrograde axonal transport of NGF in motoneurons, we injected J125 NGF unilaterally into the deltoid muscle of the rat foreleg. However, this did not result in an accumulation of radioactivity in the corresponding motoneurons (C6–C8). To decide whether this was due to insufficient penetration of J125 NGF to the nerve terminals in the motoneuron end plate, we injected J125-labeled tetanus toxin, which was known to propagate from the periphery via the axons to the motoneuron cell bodies. There was clearly a greater accumulation of J125 tetanus toxin in the motoneurons of the injected side. In subsequent experiments at the EM level, Martin Schwab demonstrated that tetanus toxin was not only transported to the motoneuron cell bodies but also transferred trans-synaptically to (inhibitory) interneurons. The time period of this trans-synaptic transfer coincided with the appearance of tetanic rigidity. These investigations also ended a dispute as to whether tetanus toxin was transported within or along the axons. To our astonishment, tetanus toxin was also transported retrogradely in sensory and sympathetic neurons. We then expanded our analysis to the central nervous system (CNS) and demonstrated that labeled tetanus toxin, when injected into a projection field, was transported retrogradely to the corresponding cell bodies. Tetanus toxin thus became a very useful tool for analyzing the projection fields of all peripheral and central neurons. In view of the already known high affinity of tetanus toxin to the trisialoganglioside TGT1, we investigated whether the simultaneous administration of TGT1 or treatment with neuraminidase, an enzyme that degrades gangliosides, interfered with the retrograde transport of tetanus toxin. This was indeed the case. By contrast, the retrograde transport of NGF was not affected. We then also included cholera toxin in our studies, which was known to have a high affinity to the monosialoganglioside GM1, and wheat germ agglutinin, a lectin with a high affinity to glycoproteins with N-acetyl glucosamine residues. All these molecules were transported retrogradely in all the populations of neurons investigated in the peripheral and central nervous system.

More Detailed Analysis of the Retrograde Axonal Transport

The EM studies with J125 NGF provided evidence for the association of the radioactivity with tubulo-vesicular compartments within the axons, which are indistinguishable from smooth endoplasmic reticulum. This cautious formulation reflects the level of knowledge in the late 1970s, when neither luminal nor specific membrane markers for smooth endoplasmic reticulum were known. After injecting J125 NGF into the anterior eye chamber or the submandibular gland (another target organ of the adrenergic neurons of the superior cervical ganglion), about 20% of the radioactivity was localized in secondary lysosomes (dense and multivesicular bodies), but the majority of the radioactivity was again localized in smooth endoplasmic reticulum-like compartments. There was no radioactivity (above background level) in the nucleus, mitochondria, and the Golgi cysternae. In view of the limited resolution of EM autoradiography we sought to produce a coupling product between NGF and horseradish peroxidase to achieve direct cytochemical localization. The coupling procedure not only had to preserve horseradish peroxidase activity but, most important, also had to preserve the biological activity of the coupled NGF. Kitaru Suda, a very gifted Japanese chemical engineer, managed to create such a coupling product by oxidation of the carbohydrate moiety of horseradish peroxidase to aldehyde groups that then were reacted with the free amino groups of NGF. The direct cytochemical localization of the reaction product of horseradish peroxidase confirmed the subcellular localization suspected in axons and the perikaryon from autoradiographic studies. In previous experiments, retrograde axonal transport of horseradish peroxidase alone had been demonstrated by injection into the anterior eye chamber of cats and hamsters. However, the concentrations of horseradish peroxidase used were several hundred times higher than those present in our coupling product. When used in these (lower) concentrations no retrograde axonal transport was detectable.

Coupling products of horseradish peroxidase were also used for the more direct localization of the retrograde transport of tetanus toxin, cholera toxin, wheat germ agglutinin, phytohaemagglutinin, and ricin. All these molecules showed the same subcellular localization as NGF. The only exception was tetanus toxin, which, as in motoneurons, was also transferred trans-synaptically to the presynaptic cholinergic nerve terminals of the superior cervical ganglion. There, it was localized in a vesicular compartment of 600 to 1000 Ångstroms diameter.

Attempts to Elucidate the Mechanism of Trans-Synaptic and NGF-Mediated Enzyme Induction

Our efforts to obtain more detailed information on the mechanism of transsynaptic and NGF-mediated enzyme induction led to a clear identification of the unresolved questions, but we were hampered by the fact that the necessary tools were simply not (yet) available. Nevertheless, I think it might be informative to briefly summarize our way of thinking and to present the steps we took to get at least some information. As already mentioned, neither the amino acid and complementary deoxyribonucleic acid (cDNA) sequences of TH and DBH were known nor their genomic organization. Even for cyclic adenosine monophosphate (cAMP), the details of its signal transduction were only rudimentary.

To determine the duration of enhanced preganglionic neuronal activity necessary to initiate TH and DBH, we exposed rats to short repetitive bouts of swimming stress. We then determined the period of time during which the induction of TH and DBH could be blocked by the administration of actinomycin D and cycloheximide, inhibitors of transcription and translation respectively. Because the treatment of rats with maximally effective doses of cycloheximide could not be extended beyond 10 hours, we investigated whether trans-synaptic induction initiated in vivo could be extended in organ culture. This was indeed the case, provided glucocorticoids were added to the culture medium. The development of organ cultures also proved to be important for the analysis of the incorporation of radioactive amino acids into DBH as soon as polyclonal antibodies against DBH became available (see below).

The evaluation of the importance of cAMP in trans-synaptic enzyme induction was the subject of heated debate between the laboratory of Erminio Costa and my group. We agreed that the administration of reserpine initiated a marked increase in cAMP in the adrenal medulla. However, the point of controversy was whether the brief marked increase in cAMP was the crucial mechanism responsible for the trans-synaptic induction of TH. Bob Mueller, who spent a sabbatical with me at the Biocenter in Basel, demonstrated together with Uwe Otten that the TH induction could be prevented by unilateral transsection of the branches of the splanchnic nerves (supplying the adrenals), even if the transsection was performed after cAMP had returned to control levels. Conversely, a steady, marked increase in cAMP over a long period of time resulting from the administration of phosphodiesterase inhibitors did not result in TH induction. These data did not support a direct involvement of cAMP in trans-synaptic TH induction.

Purification of Dopamine-ß-Hydroxylase (DBH) and Production of Anti-DBH Antibodies

Claude Gagnon, a Canadian Ph.D., joined my laboratory with the goal of purifying DBH and producing antibodies against it. Claude isolated chromaffin granules from bovine adrenal medulla. After lysis of the chromaffin granules and several subsequent column steps, all the DBH activity was located in one band of approximately 75,000 in a one-dimensional sodium dodecyl sulfate (SDS) gel. The antibodies were produced in rabbits using standard procedures. The antiserum produced a single precipitation band against crude and purified DBH. To label DBH with radioactive amino acids, we injected rats with large quantities of H3 leucine. However, the incorporation into DBH was barely detectable. We therefore applied our knowledge of the time course of trans-synaptic and NGF-initiated DBH induction in vivo and the continuation in organ cultures in vitro. We compared the rate of DBH induction in the adrenal medulla and the superior cervical ganglion. In the adrenal medulla the maximum rate of synthesis, reflected by the incorporation of H3 leucin, was already attained when the organ culture was started one hour after the intravenous injection of NGF. In the superior cervical ganglion there was a relatively small initial increase that was followed after 4 hours by a further continuous increase, so that the whole process lasted 24 hours. This time course of DBH induction in the superior cervical ganglion is reminiscent of the J125 NGF accumulation after intravenous injection. After a very rapid, relatively small accumulation within the first 15 min a much larger accumulation followed after 4 hours, reaching a maximum after 8 hours. The rapid initial increase reflects the direct supply of J125 NGF to the neuronal cell bodies. The delayed, protracted accumulation reflects the retrograde transport of NGF from the periphery.

Differences in the Susceptibility of Sympathetic Neurons in Newborn and Adult Animals

The affinity purification of very large quantities of polyclonal anti-NGF antibodies after the immunization of sheep and goats enabled us to carry out experiments in which we compared equivalent quantities of anti-NGF antibodies in newborn and adult animals. The injection of a single dose of antibodies in newborn animals virtually completely destroyed the whole peripheral sympathetic nervous system. The TH levels in the superior cervical ganglia were reduced to less than 10% of those in the controls and remained at this reduced level until adulthood. If a corresponding quantity of antibodies was injected into adult animals, this resulted in only a transient reduction of TH and DBH. The reduction of DBH was much larger than that of TH, reflecting the higher turnover of DBH. At intermediate ages the reduction of both enzymes was larger than in adult animals, and the return to control levels was much slower than in adults. These experiments clearly demonstrated that the sympathetic neurons of newborn animals are much more sensitive to NGF deprivation than those of adult animals. They also provided a plausible explanation for the complete destruction of sympathetic neurons by 6-HODA in newborn animals. In fact, in complementary experiments in collaboration with Rita Levi-Montalcini we demonstrated that in newborn animals treated with an optimal destructive dose of 6-HODA, the cell bodies of sympathetic ganglia could be protected by the simultaneous administration of NGF. In contrast the sympathetic nerve terminals could not be protected.

First Steps Toward a Reliable Immuno-Assay for NGF

My group at the Biocenter was already well established when a young scientist from Geneva, Yves-Alain Barde, visited me. He was seeking advice about how to optimally denervate the brown fat pad of rats with 6-OHDA. We discussed in detail the procedure I had worked out with Jean-Pierre Tranzer and the main purpose of the visit was rapidly settled. We talked mainly about ongoing research projects, and I felt that Yves-Alain was becoming increasingly interested. After a few additional meetings he expressed his intention to accomplish the Swiss Certificate of Molecular Biology. This certificate involved completion of a specific range of courses and experimental work corresponding to a master’s thesis. The 3rd-year block courses in the curriculum of the Biocenter met these course requirements in an optimal manner. Out of all the possible topics for the experimental work Yves-Alain chose a very demanding one, namely the determination of the levels of NGF in sympathetic target tissues in relation to the density of their adrenergic innervation.

After a few exploratory attempts to study the incorporation of radioactive amino acids into endogenous NGF in the rat iris, we came to the conclusion that the development of a sensitive immuno-assay would be a more suitable way of approaching this question. First, working together with Kitaru Suda, Yves-Alain evaluated the suitability of the NGF competition assay. For this assay, a limited quantity of anti-NGF antibodies was adsorbed to the wall of a polystyrene tube and a quantity of J125 NGF, sufficient to saturate these antibodies, was incubated together with the serum or tissue homogenate to be assayed. The more NGF there was present in the sample, the less J125 NGF should be bound to the adsorbed antibody. Yves-Alain and Kitaru detected that in the serum samples the results were falsified by the presence of a macromolecule, later shown to be predominantly macroglobulin II. This molecule, present in large quantities, bound the labeled NGF and prevented its association with the anti-NGF antibodies adsorbed to the tube. This was the explanation for the excessively high levels of NGF determined by this assay. Nor could these excessively high levels of NGF be confirmed by the classical neurite outgrowth assay developed by Rita Levi-Montalcini in the early 1950s. This biological assay has its own pitfalls and is in any case not sensitive enough to detect the very small quantities of NGF present in sympathetic target tissues. Yves-Alain and Kitaru therefore developed a twosite assay. In contrast with the competition assay a large quantity of antiNGF antibodies was adsorbed to the bottom of a polystyrene tube in which the samples were incubated. After thorough washing, J125-labeled anti-NGF antibodies were added to the tube as “detector molecules.” This assay was sufficiently sensitive to demonstrate unambiguously that the values determined by the competition assay were artifacts. However, to obtain a sufficiently high sensitivity for the determination of NGF levels in small tissue samples, the antibodies had to be more strongly linked to the incubation vessel to withstand the washing steps with detergents necessary to reduce the background. Moreover, with respect to the general reproducibility of the assay, monoclonal antibodies would have been preferable. This approach became realistic as Milstein and Köhler had just published the procedure for their production. However, its implementation had to wait until our move to Munich (see below).

Dark Clouds Over My Activity at the Biocenter in Basel

My time at the Biocenter was characterized by a very good and friendly relationship with my colleagues. Unfortunately, this was not the case with the officials of the government of Basel, who had a very direct influence on our research activities. Each individual appointment of a staff member—technical, administrative, or academic—had to be approved by the government. The government could also cancel the agreements that formed the basis of our appointments. Because I expected a considerable increase in animal experiments in the future, I had negotiated a position for a veterinarian. As I did not fill this position immediately it was axed because “such a position was apparently not really necessary.” Another particularly painful regulation concerned the quota of working permits for foreign scientists. At that time only a limited number of foreign scientists were allowed to work in Switzerland. From the financial point of view it was understandable why the government of Basel wanted to reserve the quota, as far as possible, for the pharmaceutical industry. This policy kept the taxes flowing into the notoriously empty cash box, whereas staff positions granted to us meant spending tax money. In this situation I could not make any reliable longterm plans with my staff positions because the contracts for foreign scientists were only approved a few weeks before the persons concerned were expected to arrive in Switzerland. When I handed in an application earlier I received, in answer, a list of unemployed Swiss biochemists or biologists who were simply not qualified for such positions (returning hippies or recently released inmates of psychiatric clinics).

The tension with the government came to a head when Karl Bucher, Professor of Pharmacology, was approaching retirement. The government was not willing to guarantee his replacement by the time of his retirement. I was now in danger of having to take over all the teaching of medical and pharmaceutical students, including all written and oral examinations. This would have ruined my research. In addition, a planned cellular EM group, to be led later on by Martin Schwab after his return from a postdoctoral training at Harvard Medical School, was not guaranteed either. In this situation I started to look with different eyes at offers from outside. I had already received several offers from England, the United States, and Germany. The offer from the Max Planck Society was by far the most attractive. It included the reorganization of an institute and also involved the construction of a new research building. The offer was very generous, and there were absolutely no restrictions to the employment of foreign scientists. The only restrictions applied to technical and administrative positions.

It was an extremely difficult decision to leave the Biocenter as I had to leave excellent colleagues and good friends. They made every effort, together with leading scientists from other Swiss universities, to convince the government of Basel to fulfill my requirements. They did not succeed. My departure from Basel also had grotesque consequences. Just at the time I decided to accept the Max Planck Society’s offer I learned that I had been selected for the Marcel Benoit Prize, the most prestigious Swiss award for achievements in the area of biology. However, this award was cancelled by the Swiss Minister of Education and Research to demonstrate his “loyalty” to the government of Basel. I was more amused than bitter about this small-minded provincial reaction.

The Move to Munich

My decision to move to Munich was a difficult and painful one. However, I never regretted it. The contrast with the conditions imposed by the government in Basel was striking. The administrators of the headquarters of the Max Planck Society, in particular Edmund Marsch, gave me the reassuring feeling that their exclusive goal was to support our institute and to promote the research in the best possible way.

After my formal appointment in spring 1977, I had to organize my move to Munich. I designed the new department of neurochemistry to include three Nachwuchsgruppen (independent junior research group) corresponding to assistant professors with their own budget. I did not intend to have a large group of my own, but to complement my own spectrum of research with that of these groups.

By contrast with the appointment of the academic staff, I had to take over the technicians already in employment. They were generally well qualified and also motivated to learn the methods necessary to work in my research group. The Max Planck Society gave me the opportunity to train them for their new tasks in Basel.

I was also very pleased when all the scientists who were essential for pursuing ongoing or planned new projects agreed to move with me to Munich. These collaborators were Yves-Alain Barde, David Edgar, Greg Harper, and two graduate students, Felix Eckenstein and Theo Schäfer. Martin Schwab was joining us a few months later after the end of his postdoctoral period at Harvard Medical School. Until the new research building was ready to move into, we were accommodated in free lab space of the Max Planck Institute of Biochemistry in Martinsried.

Initially the new building was supposed to be located at the Kraepelinstrasse, in downtown Munich. However, it very soon became clear that this would be extremely difficult due to the strict German building regulations stipulating that the maximum size of a new building had to be in proportion to the “green area.” The decision of the Administrative Board of the Max Planck Society to put up the new building in Martinsried next to the Max Planck Institute of Biochemistry was very fortunate for me but hard to accept for the colleagues already appointed. They all had strong emotional ties to the “Kraepelin Institute,” not only linked to the name of Kraepelin, but also other famous scientists like Alzheimer, Numa, Page, Spielmeyer, and many more. For me the decision of the Administrative Board was a big relief because the scientific contacts with the Max Planck Institute of Biochemistry became increasingly important. Moreover, it was also much easier to supervise the construction of the new building I was in charge of. This new building had to match the general design of the Max Planck Institute of Biochemistry and, accordingly, we could incorporate improvements into the planning of our new institute. I was also very fortunate to have a qualified administrative help with the practical realization of the construction of the new building: Gisbert Nowozcek. He was an organic chemist and strongly technically minded, and he supervised the day-to-day progress of the construction work in a competent manner. He took care that the architects did not deviate too much from the original plans interfering with the requirements of experimental research. This policy paid off very well, and finally also my colleagues Herz, Kreutzberg, and Lux with their strong emotional links to the Kraepelin Institute were very happy to work in the new research facilities in Martinsried.

New Institute, Major Decisions

The move to Munich coincided with a period when important new techniques became available, in particular the production of monoclonal antibodies and the synthesis of oligonucleotides. The latter opened up the possibility of progressing from a partial amino acid sequence of a protein to the determination of the corresponding cDNA sequence and establishment of the genomic organization. In the following I outline those individual projects that, at least retrospectively, are the most important ones. Many of the projects described separately influenced each other conceptually and methodologically. I paid particular attention to those aspects that were not mentioned in our original publications but were nevertheless of utmost importance for success or failure.

Purification of Brain Derived Neurotrophic Factor (BDNF)

In initial experiments, still performed in Basel, we observed that C6 gliomaconditioned medium contained survival activity detectable in dissociated embryonic (E10–12) chick sensory neurons. It was different from NGF because it could not be blocked by an excess of affinity-purified anti-NGF antibodies.

With the move to Munich, we took advantage of the opportunity to pursue long-term (high-risk) projects without the continuous pressure to publish. Nevertheless, we put ourselves under pressure insofar as the selected approaches had to have a rational basis for success. We very soon abandoned the idea of purifying a factor from glia-conditioned medium. Assuming that the biological activity of this new factor would have properties similar to NGF, 5–10,000 liters of conditioned medium would have been necessary to purify one nanomol. At that time this was the minimum quantity necessary for the determination of a partial amino acid sequence of a protein. We reasoned that the factor produced by glial cells might also be present in brain tissue. Indeed, in brain homogenates of different species there was a comparable survival activity. The decision to use pig brains was determined by the very short interval between killing and removal of the brains and the virtually unlimited quantities that could be collected in the slaughter house within a short time. The brains were frozen at –70°C until use. All the following steps were performed at 4°C, that is, in a refrigerated centrifuge or in a cold room. After two ammonium-sulfate precipitation steps and carboxymethyl cellulose chromatography, the final purification was accomplished by two-dimensional gel electrophoresis. The whole activity was localized in one single spot. The apparent molecular weight was about 13,000 as compared with marker molecules. After publishing the first purification procedure in 1982, we were urged to coin a name for this factor. Because we knew that the names initially given to newly detected molecules were often wrong or even misleading, we chose the most noncommittal name we could think of: brain derived neurotrophic factor (BDNF).

Although the quantities of BDNF isolated by the first purification procedure were very small, we nevertheless thought that they would be sufficient to determine at least a partial amino acid sequence. Unfortunately the N-terminus was blocked and the quantities of BDNF were too small to permit the production of proteolytic fragments. After this disappointing outcome, Yves-Alain Barde redesigned the whole purification procedure with great dedication and imagination. He replaced the two-dimensional electrophoresis by two hydrophobic separation steps on octyl and phenyl sepharose columns and a final C8 microbore reversed phased column. In this way sufficient quantities of BDNF became available for the production of proteolytic fragments and the determination of their amino acid sequence.

The quantities of pure BDNF also enabled us to analyze its survival effect on a broad spectrum of placodeand neural crest-derived sensory neurons, such as the neurons of the nodose, vestibular, petrosal, geniculate, and trigeminal ganglion. These experiments were partly carried out in collaboration with Alun Davies and Ron Lindsay. The effect of BDNF in vivo was also evaluated by Yves-Alain and his graduate student Magdalena Hofer. For these investigations they chose quails, which are interchangeable with chicks but much smaller, so that less BDNF was necessary to perform these experiments in vivo. Finally Jim Johnson demonstrated that BDNF also had a survival effect on isolated rat retina ganglionic cells in culture.

At this stage efforts had already been made to immunize mice with the aim of producing monoclonal antibodies against BDNF. It became apparent that, by contrast with NGF, BDNF was a very poor antigen. The production of monoclonal antibodies against BDNF had to wait for many years until large quantities of recombinant BDNF were available and fish BDNF was cloned and produced in recombinant form.

Cloning of BDNF

The new purification procedure enabled the production of proteolytic fragments and the determination of their amino acid sequences by the gas phase procedure, a method that had, in the meantime, been established by Friedrich Lottspeich. In this way about one third of the amino acid sequence of mature BDNF could be determined and compared with that of NGF. The homology between BDNF and NGF was about 50%, suggesting that they were members of a common gene family. With the availability of the partial amino acid sequence and the rapid progress made with the automatic synthesis of oligonucleotides, we thought that the cloning of BDNF could be accomplished in no time. This, however, was not the case, and difficulties that could scarcely have been foreseen arose from the different genomic and cDNA libraries used. The genomic libraries contained at least three equivalents of genomic DNA and, accordingly, at least three positive clones were to be expected. However, no positive clones were detected in any of the genomic and cDNA libraries, although we made use of all the oligonucleotide technology available at that time for the screening of libraries. On rescreening after BDNF cloning, we confirmed the negative results. Some mysterious forces seemed to be out to thwart us. Unfortunately we did not use the polymerase chain reaction (PCR) method at the earliest possible time. We had been discouraged to do so by a scientist at our institute who was reputed to be the expert in genomic analysis. He was a specialist in the forensic exploitation of single nucleotide polymorphism and declared PCR to be a useless, artifact-ridden method. After all the disappointing negative results with the screening of our libraries, we finally decided, nevertheless, to try the PCR method. Because we had good reasons to believe that the genomic organization of NGF and BDNF, as members of a common gene family, would be very similar, we concluded that it should be relatively easy to obtain PCR products coding for BDNF from genomic DNA. At that time the first contacts with Regeneron had already been initiated and Eric Shooter, a main promoter of this start-up firm (see below) had a young Polish postdoc, Piotr Masiakowski, who was very familiar with the PCR method. With his help, including the selection of the appropriate equipment, we had the first genomic PCR product coding for BDNF in a very short time. These genomically determined sequences then formed the basis for the cloning of the full length sequence of BDNF cDNA and the identification of other members of this gene family.

I consider the cloning of BDNF to be the most important contribution of my laboratory to the field of neurotrophic factors. The credit goes to Yves-Alain Barde who succeeded in this monumental task, never being discouraged by any setbacks, however serious they were.

The cloning of BDNF represented a turning point in the field of neurotrophic factors. In fact, the field exploded, and a great number of laboratories moved into it. It promised to become a gold mine with respect to new attractive directions of research and new therapeutic perspectives.

First Contacts with Biotech Firms

In the late 1980s, when the cloning of BDNF was within our grasp, we were flooded with offers from established and start-up biotech firms in the United States. In contrast, companies in Germany showed absolutely no interest. It has to be remembered that this was a time when molecular genetics was demonized. To bring a plasmid to Germany was as criminal as smuggling heroin. At best the German firms “encouraged” us with taunting remarks such as “when you have something that works orally, let us know, then we will consider the possibility of your working for us on a contract basis.”

Although I had worked in a pharmaceutical firm, I had no experience with patents and even less with commercial negotiations. I was also not willing to spend too much time on this kind of thing. We were more than happy to hand over all these tasks to Garching GmbH, the institution created by the Max Planck Society for commercially exploiting the results of basic research. Although commercial exploitation was encouraged, the interests of the scientists had absolute priority. Accordingly, we had an essential influence on the selection of the firm to cooperate with. Out of the large number of firms and individuals approaching us during this period I chose the start-up firm Regeneron. This decision was based on my longstanding friendship with Eric Shooter, in whom I had unlimited confidence and who, together with Len Schleifer, was the driving force behind this new biotech firm. The relationship with Regeneron did not develop as expected. It became clear that the main goal of Regeneron was to become a leading power in basic research on neurotrophic factors and, thus, they became our competitors. This precluded an open exchange of information and endangered the careers of our postdocs and graduate students. Moreover, it proved to be impossible to delineate in a reliable manner the projects to be followed in Tarrytown and Munich. After some disappointing experiences Yves and I resigned from the advisory board of Regeneron, and the relationship with this firm remained almost exclusively in the hands of Garching GmbH.

On the Search for Neurotrophic Factors Supporting Motoneurons

At the same time as Yves-Alain Barde was working on the cloning of BDNF and other members of the neurotrophin family, David Edgar, together with Ulrike Dormann, embarked on the purification of neurotrophic factors present in embryonic skeletal muscle extract, which were thought to regulate the survival of motoneurons during embryonic development. In contrast to the well-established culture systems for autonomic and sensory neurons, no corresponding method for motoneurons was available. Although survival effects on motoneurons in mixed cultures of spinal neurons had already been reported, it could not be decided whether the survival effect resulted from a direct action on motoneurons or an indirect one via other spinal neurons or nonneuronal cells. David and Ulrike developed a culture system for chick spinal motoneurons. It was based on the following main steps: dissection of the ventral lumbar and brachial spinal cord, digestion by trypsin, trituration, filtration, and a final metrizamide gradient step. The motoneurons, retrogradely labeled by previously injected rhodamine-isothiocyanate, were localized in one fraction of uniformly large neurons. The time when this motoneuron purification could be carried out proved to be very limited, that is, restricted to E-6. Before this stage the differentiation was not sufficiently advanced and later on the isolation of motoneurons became more difficult, necessitating higher trypsin concentrations and more vigorous trituration. This unavoidably damaged the motoneurons. In an initial paper it was demonstrated that extracts from chick embryonic muscle had a survival effect, present in the 25% to 70% ammonium sulfate fractions. The work on the purification of this survival activity was not continued, since Ulrike Dormann left our laboratory for personal reasons to move to London.

This original preparation of motoneurons was then substantially improved by Yoshi Arakawa, a visiting scientist from the Japanese drug company Esay. He wanted to purify a new factor he suspected in muscle and skin. He thought that he could immediately start with the purification. However, Michael Sendtner and I convinced him that the prerequisite for a successful purification was a reliable, optimal assay and that it was clear that our assay had not yet reached this level. He accepted this with some reluctance but was then very successful in improving the motoneuron assay. He did not change the original concept but made many modifications, such as reducing the dissection time, reducing the trypsin concentration, and using a simpler metrizamide gradient. With this improved purification procedure for motoneurons, Yoshi Arakawa analyzed the survival effect of neurotrophic factors that were already available. To our great surprise, none of the already purified and cloned neurotrophins (NGF, BDNF, and NT-3) had a survival effect on this preparation of motoneurons. The same was true for a great variety of mitogens and cytokines and various interleukines. However, ciliary neurotrophic factor (CNTF) and basic fibroblast growth factor had a very strong survival effect. They both kept motoneurons surviving for more than a week, and their effects were cumulative, in combination virtually 100% (see Arakawa et al., 1990).

The results obtained with the improved preparation of chick motoneurons were nevertheless in many respects misleading because they only related to a small time span. This became apparent as soon as Michael Sendtner and Tony Hughes introduced the cultivation of rat motoneurons based on the binding of motoneurons to solid phase anti-p75NTR antibodies, a system developed by Chris Henderson in Marseille. In this culture system more than 50% of motoneurons survived at low concentrations of BDNF. NT-3 and NT-4/5 also showed substantial survival activity. The survival effect of IGF-1 was also much stronger because we used a serum-free medium, avoiding the high concentrations of IGF-1-binding proteins that are present in the horse serum used for the cultivation of chick motoneurons. The neurotrophic support of motoneurons by a great variety of molecules from different gene families suggested multifactorial support. The prevalence of the supportive function of these factors changed during the various developmental stages. It might also be possible to exploit this multifactorial support for therapeutic purposes to reduce the possible side effects of individual trophic factors. At least in vitro, the combination of border-line effective doses of individual molecules resulted in a virtually 100% survival. The potential exploitation of this concept for therapeutic purposes has been extensively discussed by Michael Sendtner and myself in a review of Nature Neuroscience (see Thoenen and Sendtner, 2002).

Purification and Cloning of Ciliary Neurotrophic Factor (CNTF)

The purification, cloning, and evaluation of the physiological functions of CNTF are closely connected with the name of Michael Sendtner. Michael joined my laboratory with the goal to be trained for 2 to 3 years in contemporary methods of cellular and molecular neurobiology to pursue experimental clinical research in the Department of Neurology of the Technical University of Munich.

When Michael joined my laboratory he had virtually no experimental experience. However, from the very beginning it was apparent that he had an exceptional talent for experimental research. He adopted very soon all the necessary methods and designed his experiments like a scientist with many years of experimental experience. In his very first experiments, Michael resolved a controversial question as to whether the initial step of NGF-mediated signal transduction was the activation of Na⁺K⁺-ATPase, as reported by the laboratory of Silvio Varon. Michael demonstrated that this was the case only when chick sensory neurons used for this assay were severely damaged and consistently died within 24 hours. The activation of Na⁺K⁺-adenosine tri-phosphate (ATP)ase was not observed in more carefully treated neurons, which survived in the presence of NGF. This conclusion was further supported when no Na⁺K⁺-ATPase activation was initiated by NGF in chick sympathetic neurons and calf adrenal medullary cells.

Michael Sendtner’s dedication to neurobiological research was coupled with many other talents worthy of a “Renaissance man.” At high school he also studied music and obtained a diploma in classical lute, winning prestigious prizes at an early age opening up a promising career in music. Occasionally he was unsure whether music or neurobiology should have priority. Finally it was possible to convince him—my wife played an essential part—that he could continue music as a hobby while pursuing a scientific career, but the reverse was simply not possible. The initially planned 2 years became around 10 years, and he then moved to the University of Würzburg where he became head of an independent clinical research group. He made essential contributions to the elucidation of the pathogenetic mechanisms of amyotrophic lateral sclerosis (ALS) and corresponding animal models and signal transduction mechanisms essential for the survival effects of neurotrophic factors. He also contributed crucially to the molecular understanding of the pathogenetic mechanisms of spinal muscle atrophy.

After the departure of Ulrike Dormann, Michael Sendtner took over the identification and purification of motoneuron survival factors. His approach was much broader in that he did not confine his analysis to embryonic muscle extract but also included other tissues. In this way he found a strong survival activity in extracts of chick eyes, where the Varon group had identified a potent survival factor for parasympathetic neurons of chick ciliary ganglia. A similar activity, in particularly high concentrations, had been identified in the rat sciatic nerve and partially purified by G. M. Barbin, a French postdoc in the Varon lab. In addition to the survival effect on chick ciliary neurons, they had also demonstrated a survival effect on sensory and sympathetic neurons. However, they did not include the analysis of motoneurons. Although we assumed that the Varon laboratory would work intensively on the further purification and cloning of CNTF, we decided to do this ourselves to remain independent in every respect in the future.

Michael Sendtner managed to purify CNTF to homogeneity in a very short time. He modified the preparative gel electrophoresis procedure described by Barbin and used additional chromatographic steps, in particular hydrophobic columns. The rapidity of purification took also advantage of the experience of Yves-Alain Barde to purify BDNF. The partial amino acid sequence of CNTF was determined from fragments obtained by cyanogen bromide cleavage and tryptic digestion using the gas phase microsequencing procedure. The nucleotide sequence of full-length cDNA was determined by PCR from messenger ribonucleic acid (mRNA) isolated from cultures of rat astrocytes shown to produce substantial quantities of CNTF. At the same time Patrick Caroll identified a genomic clone of CNTF that confirmed the cDNA sequence.

Contrary to our expectations, the Varon lab had not continued with the purification and cloning of CNTF. However, a biotech firm, Synergen, cloned CNTF from rabbit sciatic nerve. The two papers were published almost simultaneously in Science and Nature in 1989.

Our further investigations demonstrated that CNTF was certainly not involved in the regulation of motoneuron survival during embryonic development. The expression of CNTF (mRNA and protein) was not detectable during embryonic development, neither in the periphery nor in the central nervous system. By contrast, the CNTF receptor cloned by George Yankopoulos was already expressed during embryonic development, indicating that CNTF was not the only activating ligand of this receptor, and a series of other ligands have in fact been identified, which belong to other gene families.

In motoneurons, the embryonic period of target-dependent regulation of neuronal survival is followed by a period of increased sensitivity to axonal injury. This sensitivity decreases with increasing postnatal age and, remarkably, is inversely related to the increase in the levels of CNTF in the axonensheathing Schwann cells. This led us to speculate that CNTF, as a nonsecretory molecule, might act as a “lesion factor.” In fact, after transsection of the facial nerve in newborn animals it was possible to prevent the degeneration of motoneurons in the facial nucleus by local administration of CNTF. The function of CNTF as a lesion factor was also compatible with the subcellular localization in the sciatic nerve in adult animals after nerve lesion. In intact sciatic nerves CNTF is equally distributed in the cytoplasm of the ensheathing Schwann cells. However, after lesion, besides the downregulation of the CNTF mRNA distal to the lesion site, CNTF protein was localized with patchy distribution in the extracellular space. The reappearance of CNTF mRNA and protein in Schwann cells distal to the lesion site occurs parallel to the outgrowth of regenerating axons. After the production of CNTF KO-mice (see below), additional evidence for the function of CNTF as a lesion factor was provided in the mouse mutant pmn (progressive motoneuronopathy). In this autosomal recessive mutant, the first symptoms of paralysis occur in the hind legs by postnatal week 3 and then progress rapidly to the anterior parts of the body. Between week 7 and 8 all the animals die. By the 6th postnatal week about 40% of the motoneurons of the facial nucleus have degenerated. However, when the facial nerve is transsected at the 4th postnatal week there is a dramatic reduction of the degenerating neurons. This rescue effect is absent when pmn mice are crossed with CNTF KO mice.

Production of CNTF KO Mice

The gene targeting method, which had just become available, seemed to be just what we needed to help us understand the physiological functions of our newly detected neurotrophic molecules. Because it proved to be impossible to obtain embryonic stem (ES) cell lines from the very few laboratories that had already reported on the production of KO animals, I decided to go the autodidactic way. This was possible because Rolf Kemmler provided us with an ES line (D3) he had developed for other purposes, that is, not for gene targeting experiments. As absolute beginners in this field we had to focus all our efforts. The physiological function of CNTF was less predictable than that of all the other neurotrophic molecules we had cloned. CNTF was not a secretory molecule and, additionally, had a rather mysterious pattern of expression, as described above.

Together with a technician I established the cultivation of the D3 cells and their transduction by electroporation with the target constructs that were produced by a very gifted Japanese molecular biologist, Yasuo Masu. The positive clones were handed over to Eckhard Wolf, a Ph.D. student in the laboratory of Gottfried Brehm. Eckhard had already extensive experience with the production of conventional transgenic mice through pronucleus injection. The injection of ES cells into blastocysts was thus rapidly implemented. Very soon we had the first chimeras, and the germ line transfer also worked reasonably well. The homozygous CNTF KO mice were fertile and did not show any behavioral peculiarities. We nevertheless decided to subject their motoneurons to a more detailed analysis, particularly in view of the expression of CNTF postnatally and in adulthood suggesting an involvement in maintenance functions. In spinal and facial motoneurons there was in fact a small but statistically significant reduction in the number of cell bodies. The residual neurons showed differing signs of atrophy and degeneration, and there were reactive astrocytes and an augmented number of microglial cells in their vicinity. These morphological changes were reflected by a slight but statistically significant reduction in muscle strength.

Soon after the publication of the consequences of the CNTF gene targeting in mice, Takahashi and coworkers reported that a relatively high (2%) proportion of the Japanese population has a homozygous CNTF mutation leading to a complete inactivation of the biological activity of CNTF. Interestingly, Takahashi and coworkers did not observe any neurological defects in this population. However, meanwhile a similar proportion of total CNTF defects was detected in other ethnic groups and there, the absence of CNTF activity resulted in a much earlier beginning and more rapid progress of a specific form of a familial ALS resulting from a specific mutation in copper/ zinc superoxide dismutase 1 (SOD-1). This form of familial ALS results from a (toxic) gain of function rather than a reduced activity of superoxide radical scavenging activity. In a mouse model of this SOD-1 mutation the ALS manifestations were much more severe and occurred at an earlier age when the ALS mice were crossed with CNTF KO mice. Moreover, also in patients suffering from multiple sclerosis there is evidence for a modifier function of CNTF. Again, also here the manifestations of experimental multiple sclerosis in mice were more serious on a CNTF KO background.

All these observations that were reported in the last few years are in line with the evidence that the survival and the maintenance of specific functions of motoneurons is determined by a variety of different molecules. The question arose as to whether the absence of CNTF might not make motoneurons more sensitive to the absence of other trophic factors or the action of toxic molecules, which alone would not have any clearly detectable effects. Because leukemia inhibitory factor (LIF) is up-regulated in the peripheral nerves after axotomy and LIF also has a survival effect on motoneurons in vitro, we analyzed in collaboration with Philip Brûlet in Paris the consequences of the production of CNTF/LIF double KO mice. By contrast with CNTF KO mice, no morphological changes in motoneurons could be detected in LIF KO mice up to an age of 12 months. However, in CNTF/LIF double KO mice the signs of motoneuron degeneration occurred much earlier and were more extensive than in CNTF KO mice alone. Correspondingly, there was also a much stronger reduction in muscle strength at an earlier age than in CNTF KO mice.

Development of a More Sensitive Two-Site Enzyme Immuno-Assay for NGF

Just before the move to Munich, Yves-Alain Barde and Kitaru Suda had identified the artifacts inherent in the NGF competition assay. However, the reliable two-site assay they developed using J125-labeled affinity-purified polyclonal anti-NGF antibodies was not sufficiently sensitive to determine NGF levels in sympathetically innervated tissues and sympathetic ganglia. Yves was fully taken up with the purification of BDNF. Greg Harper, who moved with us to Munich, was still involved in NGF research (purification and cloning of bovine NGF) but could not be convinced that it would be possible to develop an assay more sensitive than the classical neurite outgrowth bioassay introduced by Rita Levi-Montalcini in the early 1950s. Sigrun Korshing, a graduate student with a good background in chemistry, then agreed to take over this demanding project. In the initial experiments the first antibody did not bind strongly enough to the polyethylene assay tubes to permit the necessary thorough washing with detergents, the prerequisite for reducing the background and increasing the sensitivity. Specially treated assay plates, binding the first antibody in a “pseudo-covalent manner,” were not yet available. Sigrun decided to covalently bind the first antibody to uniform, small (1 mm diameter) glass beads. After replacing the J125 labeling of the second (detector) antibody by coupling with β-galactosidase, it was possible to increase the sensitivity of the assay 500-fold.

The two-site immuno-assay developed in Basel was based on the antibodies from a sheep with a particularly high anti-NGF titer. However, it proved to be impossible to bring this animal from “dirty” Switzerland (not belonging to the European Union) to “clean” Germany. To overcome these difficulties I seriously considered the possibility of bringing the sheep across an unmanned part of the border from Switzerland to “clean” France and from there without any problems to “clean” Germany. I knew the open borders in the surroundings of Basel quite well, but I had mixed feelings about the possibility of being arrested as a newly appointed Max Planck director and bringing not only myself but also the Max Planck Society into trouble. We therefore decided to boost the sheep for a last time and to collect several liters of serum, a stock that lasted for a long time. However, we had decided from the very beginning that we would also produce monoclonal antibodies against mouse NGF. This method was still in its infancy after Milstein and Köhler had published the principles of this revolutionary method in the late 1970s. The available myeloma cell lines were not yet optimal (“partial producers”). After some initial difficulties we accomplished several successful fusions and obtained many positive clones. For the enzyme immuno-assay we selected a clone exclusively on the basis of its high affinity to NGF. It was sheer luck that it did not cross-react with any other neurotrophin. Amazingly, this clone (27/21) is still in use and is up to date in commercial kits offered for the immunological determination of NGF.

The sensitivity of this assay enabled NGF levels to be determined in target tissues of sympathetic neurons with not only dense but also sparse innervation. In general there was a positive correlation between the density of sympathetic innervation and NGF levels. For instance, the levels were high in the densely innervated iris and the heart atria but low in the more sparsely innervated heart ventricles. By far the highest concentrations of NGF were found in sympathetic ganglia (determined in superior cervical and stellate ganglia) that do not produce NGF themselves but accumulate it through retrograde axonal transport. This assay also provided the possibility to directly demonstrate the retrograde axonal transport of endogenous NGF. After crushing the sciatic nerve we observed a very rapid 10 to 15-fold increase in NGF distally to the location of the crush. Proximally to the crush site the NGF levels were reduced, very soon reaching the lower detection limit. It was important to restrict the duration of the analysis to a short time period, that is, fewer than 10 hours after the nerve was crushed to avoid interference with the local synthesis of NGF after nerve lesion (see below). In complementary experiments we investigated the consequences of the interference with the retrograde axonal transport of NGF by destroying the adrenergic nerve terminals with 6-HODA or blockade by colchicine. Within 12 to 15 hours the NGF levels in sympathetically innervated tissues increased twoto fourfold whereas the levels in sympathetic ganglia (superior cervical and stellate ganglion) decayed with a half-time of 4 to 5 hours to reach minimal levels of 4% to 5%. The increase in NGF levels in sympathetically innervated tissues after blockade of the retrograde axonal transport with 6-HODA is also determined by the NGF uptake by NGF-responsive sensory neurons that are not destroyed by 6-HODA. Under normal physiological conditions, these two populations of neurons compete for NGF. Accordingly, after administration of 6-HODA the levels of NGF increased in the corresponding sensory ganglia and the levels of their NGF-regulated neuronal peptides, such as substance P, increased after administration of 6-HODA.

Quantification and Cellular Localization of NGF mRNA

After having exploited the new sensitive NGF enzyme immuno-assay to resolve many open questions, we felt that it was essential to complement these results with a reliable method for NGF mRNA quantification. In the early 1980s it was virtually impossible to convince molecular geneticists to work on a neurobiological question. They were afraid of ruining their reputation by becoming involved in such “dirty systems.” The only way out was to acquire the necessary skills ourselves and to adapt the available methods to the requirements of neurobiology. In my lab Rolf Heumann took over this task. After joining my research group, Rolf had already made an important contribution by unambiguously demonstrating that the regulatory effects of NGF at the transcriptional level were mediated by second messenger mechanism(s) rather than by a direct transfer of NGF to the nucleus. This possibility was hotly disputed at the time because of the artifactual redistribution of J125 NGF after producing cell fractions of PC12 cells that had taken up J125 NGF.

First Rolf became acquainted with the still very laborious process of synthesizing oligonucleotides, which were necessary for the production of adequate probes to quantify NGF mRNA in Northern blots. He developed a very sensitive assay many years before the arrival of PCR that permitted the quantification of mRNA in small tissue samples. As was found when determining the NGF protein levels, the NGF mRNA was highest in those peripheral tissues with the densest sympathetic innervation. By contrast, in sympathetic ganglia, which had by far the highest NGF protein levels, NGF mRNA was at best at the detection limit. The sensitive assays for NGF protein and NGF mRNA also enabled us to expand our analysis to the central nervous system. This was of particular interest in the context of the support of cholinergic neurons by NGF and the relatively high levels of NGF mRNA in the projection fields of cholinergic neurons of the basal forebrain nuclei (see below).

The next logical step for a more refined analysis was the development of an in situ hybridization procedure that enabled us to determine the cellular localization of the really very rare NGF mRNA. Christine Bandtlow, a graduate student, established a procedure using S35 RNA probes. With the rapid progress in the automatic synthesis of oligonucleotide probes, she complemented her results with S35 labeled oligonucleotides. In densely innervated sympathetic tissues, the NGF mRNA was not only localized in smooth muscle and fibroblast cells, but at higher relative density in epithelial cells. In the iris, for instance, the densest labeling was in the cuboidal epithelial layer on the posterior side of the iris. In the skin, particularly in the whisker pad, the surface epithelium, and the epithelium of the hair follicles were much more densely labeled than the underlying stromal cells. These astonishing results were confirmed by Northern Blot hybridization in separated samples of epithelium and underlying stromal cells. Interestingly, in the whisker pad the rapid increase in NGF mRNA in the epithelium correlated with the in-growing sensory axons, suggesting the possibility of a causal relationship, that is, that the in-growing axons initiate the synthesis of NGF. However, this interpretation, at least as a general concept, was challenged by observations made in chick embryos. When the neural tube was removed at a very early developmental stage, a chick embryo was produced that had no innervation of the skin. Nevertheless, NGF mRNA developed in the skin independently of any innervation.

With these tools in hand we were also able to analyze in greater detail the regulatory mechanisms of NGF synthesis coming into play after nerve lesion. These experiments were predominantly performed in the rat sciatic nerve. In newborn animals intermediate levels of NGF mRNA are expressed by Schwann cells and cells of the epineurium. In adult rats virtually no NGF mRNA was detectable. However, after nerve lesion there was a very rapid increase in NGF mRNA, which was of short duration, followed by a slower more protracted increase. These changes were only visible in the segments distal to the lesion. Proximally these changes were restricted to the domain of the lesion site. Interestingly, if segments of the sciatic nerve were cultivated, the time course of the NGF mRNA changes differed distinctly. We observed only the initial rapid increase, whereas the more protracted changes were not detectable. We reasoned that the difference between organ culture and in vivo experiments might be due to the absence of immigrating macrophages in organ cultures. Indeed, we then added activated macrophages to the organ cultures and the in vivo situation could virtually completely be restored. At this stage of the experiments, Dan Lindholm, who had a background in rheumatology, joined my laboratory. Based on his knowledge we investigated which molecules, produced by activated macrophages, were responsible for the protracted increase in NGF mRNA. Tumor necrosis factor and platelet derive growth factor produced a very modest increase in NGF mRNA. However, interleukin-1b resulted in a dramatic 15-fold increase in NGF mRNA. Similar effects could also be achieved by medium conditioned by activated macrophages that could be blocked by anti-interleukin-1β antibodies. It is instructive to recall that at that time only antibodies against human interleukin-1b were available, which did not cross-react with rat interleukin. We thus had to use a “mixed system,” namely organ cultures of rat sciatic nerves and human-activated macrophages obtained from patients undergoing peritoneal dialysis.

A Memorable Evening with the Father of NGF

I had already worked in the field of NGF for several years before I met Viktor Hamburger personally. It was in the very early 1980s when I gave a seminar in St. Louis, Missouri. After the seminar Viktor took me out for dinner and immediately told me that he had deliberately not invited anybody else. The reason was that he wanted to speak German. I was baffled, because I knew his sad story. I would have expected him to avoid speaking German as far as possible, and there would have been more than reasons enough. In the course of our conversation it became clear that he had very strong emotional links to his home country, Germany. This did not make him any less grateful to the United States for providing him shelter after he was expelled from Germany and giving him the opportunity to pursue a successful scientific career. We shared memories of the Black Forest, in particular the Feldberg and the Notschrei, places that Viktor had visited in all seasons, including wintertime with old-fashioned skiing equipment. I had enjoyed the same places decades later, skiing in the winter on well-prepared cross-country tracks. His glowing eyes showed how much he loved this country. Later on I gradually discovered that he originated from a family with strong national feelings, German patriots, serving in the German army during World War I. To be expelled from your home country by foreign intruders is a bitter and damaging experience, but to be chased away like a scabby dog by the countrymen you identify yourself with is a tragedy of unimaginable proportions. In the following years I met Viktor more frequently, including on the occasion when I gave the Viktor Hamburger Lecture in St. Louis. I became aware of very personal predilections, for example, that it was a mistake to bring him Himbeergeist (raspberry brandy) as a souvenir from the Black Forest, as he definitely preferred Zwetschgenwasser (plum brandy). The memories of my contacts with Viktor Hamburger would be incomplete if I did not mention his sad exclusion from the Nobel Prize awarded to Rita Levi-Montalcini and Stanley Cohen. Viktor was bitter and depressed not so much for not being awarded the Nobel Prize but on account of unnecessary, offending remarks by one of the laureates.

Purification of Choline Acetyltransferase (ChAT); Production of Poly- and Monoclonal Antibodies

In our initial investigations on the possible functions of NGF in the CNS we injected NGF or anti-NGF antibodies into the immediate vicinity of the substantia nigra and the locus coeruleus. Against our expectation this did not result in any changes of TH activity. However, after injection of J125 NGF into the projection field of the locus coeruleus, we observed a retrograde labeling of neurons in the basal forebrain that we suspected to be cholinergic. Moreover, the injection of NGF into the lateral cerebral ventricles resulted in a marked increase in choline acetyltransferase (ChAT) activity in the basal forebrain. The precise identification of the sites of ChAT synthesis required the production of specific antibodies. This was accomplished by a graduate student, Felix Eckenstein, under the guidance of Yves-Alain Barde. As for the purification of BDNF we used pig brain also for the purification of ChAT. The ChAT activity was not particularly high, but it was compensated by the large quantities of pig brain we could obtain immediately after the animals were killed. The purification procedure included several precipitation steps, adsorption to hydrophobic columns, and a final HPLC column step that resulted in a more than 1 million-fold purification. After SDS gel electrophoresis all the ChAT activity was localized in a single band with an apparent molecular weight of 68,000. The production of monoclonal antibodies proved to be difficult and laborious. Our efforts resulted in one single useful positive clone that was not suitable for immunohistochemistry. However, it could be used for the affinity purification of ChAT from other species and to produce polyclonal antisera that made the immunohistochemical localization of ChAT possible.

The availability of reliable anti-ChAT antibodies had been awaited by the scientific community for a long time. In an initial set of experiments, partially in collaboration with Mike Sofroniew and Claudio Cuelleo (Oxford University, U.K.) we identified a series of cholinergic neurons in the forebrain, in particular in the nucleus tractus diagonalis (Broca), medial septum, medial forebrain bundle, caudate-putamen, and portions of the globus pallidus. Interestingly, in layer II–VI of the entire cerebral cortex there were predominantly bipolar spindle-shaped ChAT positive cells. The cell bodies and proximal dendrites could be visualized. However, the quality of the antibodies and our immunohistochemical techniques were not good enough to visualize the distal dendritic arborization and, above all, the axonal projections from basal forebrain cholinergic neurons to the hippocampus and the cerebral cortex. Their presence could be deduced from retrograde tracing and axonal transsection experiments. The latter led to a drastic reduction of ChAT in the projection fields. This was particularly illuminating for “undercut” experiments of the visual cortex which led to a strong reduction, but not to a complete disappearance of ChAT, providing the counterpart to the immunohistochemical localization of ChAT in the spindle-shaped interneurons of the cerebral cortex. Some basic important questions could be resolved in this way, but a lot of other questions were still waiting to be elucidated, particularly in the context of the pharmacological manipulation of central and peripheral cholinergic neurons. The various ChAT antibodies were in great demand, and Felix Eckenstein became a much-courted postdoc.

For us the anti-ChAT antibodies remained a useful tool for future experiments in which, in addition to NGF, we analyzed the response of ChAT levels to other neurotrophic molecules. The purification procedure for ChAT was also the basis for the determination of its partial amino acid sequence. This information was then handed over to the laboratory of Jacques Mallet in Paris who cloned ChAT and determined its genomic organization. My own lab could not pursue this project to this level. We had to set priorities and had more than enough to do elucidating the physiological functions of the members of the neurotrophin family and CNTF, including the production of corresponding KO animals.

Retrograde Trans-Synaptic Effects of NGF on Preganglionic Cholinergic Neurons

In previous experiments performed in Basel, we observed that treatment of newborn rats with NGF resulted in an increase in ChAT activity in the superior cervical ganglion. This increase did not result from a direct effect of NGF on the preganglionic cholinergic neurons. Neither J125-NGF nor NGF-HRP injected into the projection field of postganglionic adrenergic neurons was transferred to the preganglionic cholinergic nerve terminals. As a positive control we injected labeled tetanus toxin that was, as expected, transferred trans-synaptically.

Theo Schäfer, under the guidance of Martin Schwab, determined the morphometric changes occurring in the superior cervical ganglion of the rat and the corresponding preganglionic cervical trunk. Under physiological conditions the number of preganglionic cholinergic axons drops from 13,000 at birth to 7,000 at postnatal day 10, reflecting the physiological neuronal cell death in the superior cervical ganglion during this time period. NGF treatment did not only prevent this loss but even increased the number of axons to over 30,000 after 10 days of treatment with NGF. The retrograde labeling of the preganglionic cholinergic neurons in the spinal cord showed a similar distribution in controls and NGF-treated animals, that is, from C6 to T6. However, the number of neurons was 1.5 times higher in the NGF-treated animals, providing evidence for an augmented survival of the preganglionic cholinergic neurons.

Projects Not Discussed in Detail

At an early stage after our move to Munich, Motoharu Hayashi, under the guidance of David Edgar, investigated the rate of development of substance P, somatostatin, and vascular intestinal protein. They produced specific antisera against fragments of these peptides in rabbits, developed immunoassays, and then determined the rate of development of these peptides in the paravertebral sympathetic ganglia and spinal sensory neurons of chick embryos. These peptide changes occurred independently of each other. Similar, rather complex changes in the expression of these peptides occurred when large quantities of NGF were administered daily to the allantois of chick embryos.

In another set of experiments we compared the changes in NGF and p75NTR mRNA in the sciatic nerve during development and after lesion. These experiments were performed in cooperation with the laboratory of Eric Shooter.

In cooperation with Ruppert Timpl, David Edgar and I identified the heparin-binding domain of laminin as responsible for the potentiating effect of laminin on NGF-mediated neurite outgrowth and the potentiation of the survival effect of NGF on chick sympathetic neurons.

Although the “Campenot multi-chamber system” proved to be disappointing for the detailed analysis of the kinetics of the retrograde axonal transport, it led to initial experiments demonstrating that central myelin, produced by oligodendrocytes, inhibits the regeneration of axons after their lesion. In experiments subsequently carried out at the Brain Research Institute in Zürich, Martin Schwab purified one of the most essential inhibitory molecules, Nogo, and demonstrated in highly sophisticated experiments that monoclonal antibodies directed against specific domains of Nogo could at least partially restore the regeneration of transsected axons in the spinal cord.

Compulsory Retirement Determines Research Strategies

In the Max Planck Society the compulsory retirement of the directors at the age of 68 is an iron rule. It is expected that all the staff positions of scientists are available for a prospective successor. This policy ensures a high degree of flexibility in the selection of new, innovative directions of research.

For many years my research strategies were determined by my approaching retirement. On the one hand I wanted to finish as much as possible ongoing research projects requiring expertise in advanced neuroanatomy and immunohistochemistry in the context of the analysis of already produced KO mice. Postdocs fulfilling these qualifications expected to become acquainted with contemporary methods of molecular genetics, such as the overexpression of genes under the control of a tissue- or cell-specific promoter, or to learn all the necessary techniques to produce KO mice. In this way a relatively broad spectrum of projects was initiated, thought to provide the basis for future independent research groups outside our institute after my retirement. In this way we made the first interesting observations that, contrary to all expectations, calbindin-28 KO mice did not show increased sensitivity to the excitotoxic effects of glutamate. However, in view of the high concentrations of calbindin-28 in Purkinje cells the involvement of these neurons was thought to be responsible for the slight impairments of equilibrium and coordination. Indeed, later on Michael Meyer, Jaroslaw Barski, and Matti Airaksinen demonstrated by the selective targeting of the calbindin-28 gene in Purkinje cells that this was in fact the case.

In my own research I concentrated more and more on the modulatory role of neurotrophins, in particular BDNF, in activity-dependent neuronal plasticity. By contrast with the very generous support for an active Max Planck director, the level of support was very modest after retirement, and the topics to be pursued had to be selected very carefully, and the work, unavoidably, proceeded at a reduced pace.

Modulatory Role of BDNF in Activity-Dependent Neuronal Plasticity

Activity-dependent regulation of BDNF synthesis in the CNS was shown to occur very rapidly, that is, within minutes, suggesting its regulation as an immediate early gene. Under physiological conditions, BDNF in the CNS is exclusively expressed in neurons. The pattern of expression changed depending on the stimulation parameters used. The regulatory mechanisms also included physiological stimuli such as light input that elicited characteristic changes in BDNF expression in the neurons of the visual cortex. These observations led me to propose at an early stage of BNDF research that BDNF might be involved in activity-dependent neuronal plasticity. This hypothesis was strongly supported when Martin Korte demonstrated that in acute hippocampal slices of BDNF KO mice, long-term potentiation in the CA-3/CA-1 system was strongly reduced. Interestingly, this reduction was the same in homo- and heterozygous BDNF KO mice, demonstrating that this modulatory role of BDNF depends on a minimal critical level of BDNF. Very soon the relationship between BDNF and activity-dependent neuronal plasticity attracted the interest of many other laboratories, and it is impossible to give appropriate credit to all the contributions that were made in rapid sequence.

In view of my approaching retirement, with a drastic reduction of my experimental possibilities, I had to concentrate on specific details, such as the mechanism and site of secretion of neurotrophins at the light and EM level. Although fragmentary, these investigations led to surprising results: contrary to our expectations, the activity-dependent secretion of neurotrophins (initial experiments performed with NGF because suitable antibodies against BDNF were not yet available) did not depend on extracellular Ca⁺ + but exclusively on intact intracellular Ca⁺ + stores and the Ca⁺ + released therefrom. The levels of endogenous neurotrophins were so low that for the majority of the experiments a chemicalor virus-mediated transduction was necessary. The necessity for overexpression led us to question whether the results obtained were representative of the physiological situation in vivo. Not unexpectedly, given the different methods used, controversial results were reported and many questions are still unresolved, such as the site of the synthesis of BDNF; it is not known whether its synthesis is confined to the perikaryon or whether BDNF mRNA is selectively transported to distal parts of the neurons, in particular dendrites. Controversial observations were also reported on the nature of the compartment in which BDNF protein is transported and secreted from the different parts of the neuron. More recently the question arose as to whether neurotrophins, in particular NGF and BDNF, are secreted as precursors or mature proteins. This aspect became even more important when it was demonstrated that the precursor molecules were bound with higher affinity to p75NTR receptors and enhanced the evolving cascade of signal transduction.

Although the analysis of all the detailed functions of neurotrophins is justified in its own right, I feel that the increasing evidence for a modulatory role of BDNF in activity-dependent neuronal plasticity, long-term potentiation and long-term depression, opens up more general conceptional aspects. It is accepted that our memory is based on activity-dependent changes in synaptic strength. The mechanisms brought into play by the Hebbian activation pattern provide only limited possibilities for variability. The intensity of the activation of these rather ubiquitous mechanisms such as the activation of NMDA receptors, activation of CaM kinase II and IV, and calcium activated cAMP leaves little room for locally restricted modulations. If we put this limited armamentarium in context with the numberless engrams that are stored in the human brain (several languages, faces, names, broad spectrum of general knowledge, and the ever-increasing flood of new scientific data), it is comforting to know that mechanisms exist that can modulate these basic mechanisms with local restriction and variability. Neurotrophins, in particular BDNF, fulfill the requirements for such a function. I would like to emphasize that I do not consider this function to be unique. However, in spite of the numerous unresolved questions, knowledge on BDNF is relatively far advanced by comparison with that of other potential modulatory molecules. It is conceivable that many other molecules, including numerous neuropeptides, have similar functions. A direct link between the function of BDNF and memory has recently been reported. In the United States a regional cohort of predominantly European origin showed a relatively high percentage (2%) of a single nucleotide polymorphism that led to an exchange of the amino acid valine by methionine. This exchange was accompanied by subtle deficits in declarative memory and was also reflected in distinct changes in functional magnetic resonance imaging (fMRI). In animal experiments the same mutation in the precursor domain of BDNF led to changes in its sorting and a reduction of the activity-dependent secretion of BDNF. Moreover, there is increasing evidence for a possible relationship between the expression of BDNF and the therapeutic effect of antidepressants. When antidepressants were analyzed in animal models, there was a close correlation between the appearance of the antidepressive actions and the increase of BDNF levels in different regions of the CNS, in particular in the hippocampus and the amygdala. These antidepressants were introduced on account of their blocking action on the uptake of biogenic amines. Because this uptake blockade is an instantaneous effect, one would also expect a short-term therapeutic response. However, the therapeutic effect does not become apparent until several weeks after beginning of the administration of the antidepressant.

Although I am no longer actively contributing to the field of neurotrophic factors, it gives me great pleasure and satisfaction to see how this field developed in so many unexpected directions. When we embarked on these challenging, high-risk projects our goals were much more modest, namely to find neurotrophic factors for populations of neurons for which molecules of trophic support had not yet been identified.

Conclusion

When I was invited to write an autobiographical contribution I was very hesitant about doing so. Now, having come to the end I ask myself whether I have written it in an appropriate form. The simple description of valuable contributions made by my laboratory did not seem to be particularly interesting as such. Today the findings that were of high current interest at the time of their detection are considered self-evident, and at best they became textbook knowledge. As far as possible I have included aspects that have not been published in our original papers. They include fortunate combinations of circumstances but also the pitfalls we encountered, including barely explainable bad luck as for example, in the case of the screening of genomic libraries, when no clone coding for BDNF was present. I have also tried to shed light on the experimental situation—its possibilities and limitations—from a contemporary point of view. The biological problems were not infrequently clearly identified and the correct questions were asked. However, the experimental tools necessary to obtain a direct answer were simply not available. In this situation I felt it would be instructive to describe the approaches taken to obtain at least a partial answer.

Failures are just as much part of the everyday scientific life as the few moments of really exciting new insights. In between there are the long periods of hard work necessary to complete the many details of a project and to carry out all the necessary controls.

Sharing moments of success and overcoming difficulties with friends and motivated colleagues, based on absolute confidence, is one of the most positive aspects of doing research. However, it would be dishonest to exclude frictions and even painful personal experiences. They are part of our scientific life, even if our memory has the features to eliminate them and to present, retrospectively, a picture that is too rosy and does not correspond to the realities.

When I look back and try to evaluate what my coworkers and I contributed to science and what science meant to us, I realize that it is important to remember that the wheel is reinvented again and again. Although we contributed to the improvement of wheels or in rare cases even invented an initial primitive wheel ourselves, we cannot expect that these contributions will be acknowledged forever. Further progress is based on the very latest successful steps. What we think are earthshaking new insights now will become very soon textbook knowledge. I am happy that I had the opportunity to participate in a field of research that developed in such an extraordinary manner. Although for several years I have now been moving from the function of an active player to that of an interested spectator, I am still anxious to grasp as much as possible of the exciting new developments. However, at the same time I am also conscious that even the most important pillars of our science will disappear together with our planet. What remains is my gratitude that I have lived in a period of evolution brought about by a fortunate combination of numerous variables that made such interesting events possible including our own existence and that I was privileged to become a scientist.

Selected Bibliography

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Bandtlow CE, Heumann R, Schwab ME, Thoenen H. Cellular localization of nerve growth factor synthesis by in situ hybridization. EMBO J 1987;6:891–899.

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Barde YA, Edgar D, Thoenen H. Sensory neurons in culture: Changing requirements for survival factors during embryonic development. Proc Natl Acad Sci USA 1980;77:1199–1203.

Barde YA, Lindsay RM, Monard D, Thoenen H. New factor released by cultured glioma cells supporting survival and growth of sensory neurones. Nature 1978;274:818.

Barres BA, Burne JF, Holtmann B, Thoenen H, Sendtner M, Raff MC. Ciliary neurotrophic factor enhances the rate of oligodendrocyte generation. Mol Cell Neurosci 1996;8:146–156.

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Blöchl A, Thoenen H. Localization of cellular storage compartments and sites of constitutive and activity-dependent release of nerve growth factor (NGF) in primary cultures of hippocampal neurons. Mol Cell Neurosci 1996;7:173–190.

Bömmel H, Xie G, Rossoll W, Wiese S, Jablonka S, Boehm T, Sendtner M. Missense mutation in the tubulin-specific chaperone E (Tbce) gene in the mouse mutant progressive motor neuronopathy, a model of human motoneuron disease. J Cell Biol 2002;159:563–569.

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Canossa M, Gärtner A, Campana G, Inagaki N, Thoenen H. Regulated secretion of neurotrophins by metabotropic glutamate group I (mGluRI) and Trk receptor activation is mediated via phospholipase C signalling pathways. EMBO J 2001;20:1640–1650.

Canossa M, Griesbeck O, Berniger B, Campana G, Kolbeck R, Thoenen H. Neurotrophin release by neurotrophins: Implications for activity-dependent neuronal plasticity. Proc Natl Acad Sci USA 1997;94:13279–13286.

Carroll P, Lewin GR, Koltzenburg M, Toyka KV, Thoenen H. A role for BDNF in mechanosensation. Nat Neurosci 1998;1:42–46.

Carroll P, Sendtner M, Meyer M, Thoenen H. Rat ciliary neurotrophic factor (CNTF): Gene structure and regulation of mRNA levels in glial cell cultures. GLIA 1993;9:176–187.

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Castrén E, Zafra F, Thoenen H, Lindholm D. Light regulates expression of brainderived neurotrophic factor mRNA in rat visual cortex. Proc Natl Acad Sci USA 1992;89:9444–9448.

Cellerino A, Carroll P, Thoenen H, Barde YA. Reduced size of retinal ganglion cell axons and hypomyelation in mice lacking brain-derived neurotrophic factor. Mol Cell Neurosci 1997;9:397–408.

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Eckenstein F, Barde YA, Thoenen H. Production of specific antibodies to choline acetyltransferase purified from pig brain. Neuroscience 1981;6:993–1000.

Eckenstein F, Thoenen H. Production of specific antisera and monoclonal antibodies to choline acetyltransferase: Characterization and use for identification of cholinergic neurons. EMBO J 1982;1:363–368.

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Edgar D, Timpl R, Thoenen H. The heparin-binding domain of laminin is responsible for its effects on neurite outgrowth and neuronal survival. EMBO J 1984;3:1463–1468.

Edgar D, Timpl R, Thoenen H. Structural requirements for the stimulation of neurite outgrowth by two variants of laminin and their inhibition by antibodies. J Cell Biol 1988;106:1299–1306.

Egan M, Kojima M, Callicott JH, Goldberg TE, Kolachana BS, Bertolino A, Zaitsev E, Gold B, Goldman D, Dean M, Lu B, Weinberger DR. The BDNF val66met polymorphism affects activity-dependent secretion of BDNF and human memory and hippocampal function. Cell 2003;112:257–269.

Gagnon C, Otten U, Thoenen H. Increased synthesis of dopamine beta-hydroxylase in cultured rat adrenal medullae after in vivo administration of reserpine. J Neurochem 1976;27:259–265.

Gagnon C, Pfaller W, Fischer WM, Schwab M, Winkler H, Thoenen H. Increased specific activity of membrane-bound dopamine beta-hydroxylase in chromaffin granules after reserpine treatment. J Neurochem 1977;28:853–856.

Gagnon C, Schatz R, Otten U, Thoenen H. Synthesis, subcellular distribution and turnover of dopamine beta-hydroxylase in organ cultures of sympathetic ganglia and adrenal medullae. J Neurochem 1976;27:1083–1089.

Gärtner A, Shostak Y, Hackel N, Ethell IM, Thoenen H. Ultrastructural identification of storage compartments and localization of activity-dependent secretion of Neurotrophin 6 in hippocampal neurons. Mol Cell Neurosci 2000;15:215–234.

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Giess R, Maurer M, Linker R, Gold R, Warmuth-Metz M, Toyka KV, Sendtner M, Rieckmann P. Association of a null mutation in the CNTF gene with early onset of multiple sclerosis. Arch Neurol 2002;59:407–409.

Gnahn H, Hefti F, Heumann R, Schwab ME, Thoenen H. NGF-mediated increase of choline acetyltransferase (ChAT) in the neonatal rat forebrain: Evidence for a physiological role of NGF in the brain? Dev Brain Res 1983;9:45–52.

Goedert M, Otten U, Thoenen H. Biochemical effects of antibodies against nerve growth factor on developing and differentiated sympathetic ganglia. Brain Res 1978;148:264–268.

Gottschalk W, Pozzo-Miller LD, Figurov A, Lu B. Presynaptic modulation of synaptic transmission and plasticity by brain-derived neurotrophic factor in the developing hippocampus. J Neurosci 1998;18:6830–6839.

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Griesbeck O, Canossa M, Campana G, Gärtner A, Hoener MC, Nawa H, Kolbeck R, Thoenen H. Are there differences between the secretion characteristics of NGF and BDNF? Implications for the modulatory role of neurotrophins in activity-dependent neuronal plasticity. Microsc Res Tech 1999;45:262–275.

Griesbeck O, Korte M, Gravel C, Bonhoeffer T, Thoenen H. Rapid gene transfer into cultured hippocampal neurons and acute hippocampal slices using adenoviral vectors. Mol Brain Res 1997;44:171–177.

Griesbeck O, Parsadanian AS, Sendtner M, Thoenen H. Expression of neurotrophins in skeletal muscle: Quantitative comparison and significance for motoneuron survival and maintenance of function. J Neurosci Res 1995;42:21–33.

Guirland C, Suszuki S, Kojima M, Lu B, Zheng JQ. Lipid rafts mediate chemotropic guidance of nerve growth cones. Neuron 2004;42:51–62.

Harper GP, Glanville RW, Thoenen H. The purification of nerve growth factor from bovine seminal plasma. Biochemical characterization and partial amino acid sequence. J Biol Chem 1982;257:8541–8548.

Hartmann M, Brigadski T, Erdmann KS, Holtmann B, Sendtner M, Narz F, Lessmann B. Truncated TrkB receptro-induced outgrowth of dendritic filopodia involves the p75 neurotrophin receptor. J Cell Sci 2004;117:5803–5814.

Hayashi M, Edgar D, Thoenen H. The development of substance P, somatostatin and vasoactive intestinal polypeptide in sympathetic and spinal sensory ganglia of the chick embryo. Neuroscience 1983;10:31–39.

Hayashi M, Edgar D, Thoenen H. Nerve growth factor changes the relative levels of neuropeptides in developing sensory and sympathetic ganglia of the chick embryo. Dev Biol 1985;108:49–55.

Hendry IA, Stöckel K, Thoenen H, Iversen LL. The retrograde axonal transport of nerve growth factor. Brain Res 1974;68:103–121.

Heumann R, Korsching S, Bandtlow C, Thoenen H. Changes of nerve growth factor synthesis in nonneuronal cells in response to sciatic nerve transsection. J Cell Biol 1987;104:1623–1631.

Heumann R, Lindholm D, Bandtlow C, Meyer M, Radeke MJ, Misko TP, Shooter E, Thoenen H. Differential regulation of mRNA encoding nerve growth factor and its receptor in rat sciatic nerve during development, degeneration, and regeneration: Role of macrophages. Proc Natl Acad Sci USA 1987;84:8735–8739.

Heumann R, Schwab M, Thoenen H. A second messenger required for nerve growth factor biological activity? Nature 1981;292:838–840.

Heumann R, Thoenen H. Comparison between the time course of changes in nerve growth factor protein levels and those of its messenger RNA in the cultured rat iris. J Biol Chem 1986;261:9246–9249.

Hoener MC. Role played by sodium in activity-dependent secretion of neurotrophins-revisited. Eur J Neurosci 2000;12:3096–3106.

Holtmann B, Wiese S, Samsam M, Grohmann K, Pennica D, Martini R, Sendtner M. Triple knock-out of CNTF, LIF, and CT-1 defines cooperative and distinct roles of these neurotrophic factors for motoneuron maintenance and function. J Neurosci 2005;25:1778–1787.

Hughes RA, Sendtner M, Thoenen H. Members of several gene families influence survival of rat motoneurons in vitro and in vivo. J Neurosci Res 1993;36: 663–671.

Inagaki N, Chihara K, Arimura N, Ménager C, Kawano Y, Matsuo N, Nishimura T, Amano M, Kaibuchi K. CRMP-2 induces axons in cultured hippocampal neurons. Nat Neurosci 2001;4:781–782.

Inagaki N, Thoenen H, Lindholm D. TrkA tyrosine residues involved in NGF-induced neurite outgrowth of PC12 cells. Eur J Neurosci 1995;7:1125–1133.

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Kalcheim C, Barde YA, Thoenen H, Le Douarin NM. In vivo effect of brain-derived neurotrophic factor on the survival of developing dorsal root ganglion cells. EMBO J 1987;6:2871–2873.

Klapstein GJ, Vietla S, Lieberman DN, Gray PA, Airaksinen MS, Thoenen H, Meyer M, Mody I. Calbindin-D28k fails to protect hippocampal neurons against ischemia in spite of its cytoplasmic calcium buffering properties: Evidence from Calbindin-D28k knockout mice. Neuroscience 1998;85:361–373.

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Korsching S, Auburger G, Heumann R, Scott J, Thoenen H. Levels of nerve growth factor and its mRNA in the central nervous system of the rat correlate with cholinergic innervation. EMBO J 1985;4:1389–1393.

Korsching S, Heumann R, Thoenen H, Hefti F. Cholinergic denervation of the rat hippocampus by fimbrial transsection leads to a transient accumulation of nerve growth factor (NGF) without change in mRNA NGF content. Neurosci Lett 1986;66:175–180.

Korsching S, Thoenen H. Nerve growth factor in sympathetic ganglia and corresponding target organs of the rat: Correlation with density of sympathetic innervation. Proc Natl Acad Sci USA 1983;80:3513–3516.

Korsching S, Thoenen H. Quantitative demonstration of the retrograde axonal transport of endogenous nerve growth factor. Neurosci Lett 1983;39:1–4.

Korsching S, Thoenen H. Nerve growth factor supply for sensory neurons: Site of origin and competition with the sympathetic nervous system. Neurosci Lett 1985a;54:201–205.

Korsching S, Thoenen H. Treatment with 6-hydroxydopamine and colchicine decreases nerve growth factor levels in sympathetic ganglia and increases them in the corresponding target tissues. J Neurosci 1985b;5:1058–1061.

Korte M, Carroll P, Wolf E, Brem G, Thoenen H, Bonhoeffer T. Hippocampal long-term potentiation is impaired in mice lacking brain-derived neurotrophic factor. Proc Natl Acad Sci USA 1995;92:8856–8860.

Korte M, Griesbeck O, Gravel C, Carroll P, Staiger V, Thoenen H, Bonhoeffer T. Virus-mediated gene transfer into hippocampal CA1 region restores long-term potentiation in brain-derived neurotrophic factor mutant mice. Proc Natl Acad Sci USA 1996;93:12547–12552.

Korte M, Staiger V, Griesbeck O, Thoenen H, Bonhoeffer T. The involvement of brain-derived neurotrophic factor in hippocampal long-term potentiation revealed by gene targeting experiments. J Physiol Paris 1996;90:157–164.

Leibrock J, Lottspeich F, Hohn A, Hofer M, Hengerer B, Masiakowski P, Thoenen H, Barde YA. Molecular cloning and expression of brain-derived neurotrophic factor. Nature 1989;341:149–152.

Leingärtner A, Heisenberg CP, Kolbeck R, Thoenen H, Lindholm D. Brain-derived neurotrophic factor increases neurotrophin-3 expression in cerebellar granule neurons. J Biol Chem 1994;269:828–830.

Levi-Montalcini R, Aloe L, Mugnaini E, Oesch F, Thoenen H. Nerve growth factor induces volume increase and enhances tyrosine hydroxylase synthesis in chemically axotomized sympathetic ganglia of newborn rats. Proc Natl Acad Sci USA 1975;72:595–599.

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Lindholm D, Heumann R, Hengerer B, Thoenen H. Interleukin 1 increases stability and transcription of mRNA encoding nerve growth factor in cultured rat fibroblasts. J Biol Chem 1988;263:16348–16351.

Lindholm D, Heumann R, Meyer M, Thoenen H. Interleukin-1 regulates synthesis of nerve growth factor in non-neuronal cells of rat sciatic nerve. Nature 1987;330:658–659.

Lindsay RM, Thoenen H, Barde YA. Placode and neural crest-derived sensory neurons are responsive at early developmental stages to brain-derived neurotrophic factor. Dev Biol 1985;112:319–328.

Linker RA, Maurer M, Gaupp S, Martini R, Holtmann B, Giess R, Rieckmann P, Lassmann H, Toyka KV, Sendtner M, Gold R. CNTF is a major protective factor in demyelinating CNS disease: A neurotrophic cytokine as modulator in neuroinflammation. Nat Med 2002;8:620–624.

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Lu B, Pang PT, Woo NH. The yin and yang of neurotrophin action. Nat Rev Neurosci 2005;6:603–614.

Marty S, Berninger B, Carroll P, Thoenen H. GABAergic stimulation regulates the phenotype of hippocampal interneurons through the regulation of brain-derived neurotrophic factor. Neuron 1996;16:565–570.

Marty S, Carroll P, Cellerino A, Castrén E, Staiger V, Thoenen H, Lindholm D. Brain-derived neurotrophic factor promotes the differentiation of various hippocampal nonpyramidal neurons, including Cajal-Retzius cells, in organotypic slice cultures. J Neurosci 1996;16:675–687.

Masu Y, Wolf E, Holtmann B, Sendtner M, Brem G, Thoenen H. Disruption of the CNTF gene results in motor neuron degeneration. Nature 1993;365:27–32.

Mueller RA, Otten U, Thoenen H. The role of cyclic adenosine 3’,5’-monophosphate in reserpine-initiated adrenal medullary tyrosine hydroxylase induction. Mol Pharmacol 1974;10:855–860.

Mueller RA, Thoenen H, Axelrod J. Adrenal tyrosine hydroxylase: Compensatory increase in activity after chemical sympathectomy. Science 1969a;163:468–469.

Mueller RA, Thoenen H, Axelrod J. Increase in tyrosine hydroxylase activity after reserpine administration. J Pharmacol Exp Ther 1969b;169:74–79.

Mueller RA, Thoenen H, Axelrod J. Inhibition of trans-synaptically increased tyrosine hydroxylase activity by cycloheximide and actinomycin D. Mol Pharmacol 1969c;5:463–469.

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Otten U, Paravicini U, Oesch F, Thoenen H. Time requirement for the single steps of trans-synaptic induction of tyrosine hydroxylase in the peripheral sympathetic nervous system. Naunyn Schmiedebergs Arch Pharmacol 1973;280: 117–127.

Otten U, Schwab M, Gagnon C, Thoenen H. Selective induction of tyrosine hydroxylase and dopamine beta-hydroxylase by nerve growth factor: Comparison between adrenal medulla and sympathetic ganglia of adult and newborn rats. Brain Res 1977;133:291–303.

Otten U, Thoenen H. Effect of glucocorticoids on nerve growth factor-mediated enzyme induction in organ cultures of rat sympathetic ganglia: Enhanced response and reduced time requirement to initiate enzyme induction. J Neurochem 1977;29:69–75.

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Paravicini U, Stöckel K, Thoenen H. Biological importance of retrograde axonal transport of nerve growth factor in adrenergic neurons. Brain Res 1975;84:279–291.

Rohrer H, Heumann R, Thoenen H. The synthesis of nerve growth factor (NGF) in developing skin is independent of innervation. Dev Biol 1988;128:240–244.

Rohrer H, Schäfer T, Korsching S, Thoenen H. Internalization of nerve growth factor by pheochromocytoma PC12 cells: Absence of transfer to the nucleus. J Neurosci 1982;2:687–697.

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Saner A, Thoenen H. Model experiments on the molecular mechanism of action of 6-hydroxydopamine. Mol Pharmacol 1971;7:147–154.

Schäfer T, Schwab ME, Thoenen H. Increased formation of preganglionic synapses and axons due to a retrograde trans-synaptic action of nerve growth factor in the rat sympathetic nervous system. J Neurosci 1983;3:1501–1510.

Schwab M, Agid Y, Glowinski J, Thoenen H. Retrograde axonal transport of 125Itetanus toxin as a tool for tracing fiber connections in the central nervous system; connections of the rostral part of the rat neostriatum. Brain Res 1977; 126:211–224.

Schwab ME, Otten U, Agid Y, Thoenen H. Nerve growth factor (NGF) in the rat CNS: Absence of specific retrograde axonal transport and tyrosine hydroxylase induction in locus coeruleus and substantia nigra. Brain Res 1979;168:473–483.

Schwab ME, Suda K, Thoenen H. Selective retrograde transsynaptic transfer of a protein, tetanus toxin, subsequent to its retrograde axonal transport. J Cell Biol 1979;82:798–810.

Schwab M, Thoenen H. Selective trans-synaptic migration of tetanus toxin after retrograde axonal transport in peripheral sympathetic nerves: A comparison with nerve growth factor. Brain Res 1977;122:459–474.

Schwab ME, Thoenen H. Dissociated neurons regenerate into sciatic but not optic nerve explants in culture irrespective of neurotrophic factors. J Neurosci 1985;5:2415–2423.

Sendtner M. Neurotrophic factors: Effects in modulating properties of the neuromuscular endplate. Cytokine Growth Factor Rev 1998;9:1–7.

Sendtner M, Carroll P, Holtmann B, Hughes RA, Thoenen H. Ciliary neurotrophic factor. J Neurobiol 1994;25:1436–1453.

Sendtner M, Götz R, Holtmann B, Escary J-L, Masu Y, Carroll P, Wolf E, Brem G, Brûlet P, Thoenen H. Cryptic physiological trophic support of motoneurons by LIF revealed by double gene targeting of CNTF and LIF. Curr Biol 1996;6:686–694.

Sendtner M, Götz R, Holtmann B, Thoenen H. Endogenous ciliary neurotrophic factor is a lesion factor for axotomized motoneurons in adult mice. J Neurosci 1997;17:6999–7006.

Sendtner M, Gnahn H, Wakade A, Thoenen H. Is activation of the Na⁺K⁺ pump necessary for NGF-mediated neuronal survival? J Neurosci 1988;8:458–462.

Sendtner M, Holtmann B, Kolbeck R, Thoenen H, Barde YA. Brain-derived neurotrophic factor prevents the death of motoneurons in newborn rats after nerve section. Nature 1992;360:757–759.

Sendtner M, Kreutzberg GW, Thoenen H. Ciliary neurotrophic factor prevents the degeneration of motor neurons after axotomy. Nature 1990;345:440–441.

Sendtner M, Schmalbruch H, Stöckli KA, Carroll P, Kreutzberg GW, Thoenen H. Ciliary neurotrophic factor prevents degeneration of motor neurons in mouse mutant progressive motor neuronopathy. Nature 1992;358:502–504.

Sendtner M, Stöckli KA, Carroll P, Kreutzberg GW, Thoenen H, Schmalbruch H. More on motor neurons. Nature 1992;360:541–542.

Sendtner M, Stöckli KA, Thoenen H. Synthesis and localization of ciliary neurotrophic factor in the sciatic nerve of the adult rat after lesion and during regeneration. J Cell Biol 1992;118:139–148.

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Stöckel K, Guroff G, Schwab M, Thoenen H. The significance of retrograde axonal transport for the accumulation of systemically administered nerve growth factor (NGF) in the rat superior cervical ganglion. Brain Res 1976;109:271–284.

Stöckli KA, Lottspeich F, Sendtner M, Masiakowski P, Carroll P, Götz R, Lindholm D, Thoenen H. Molecular cloning, expression and regional distribution of rat ciliary neurotrophic factor. Nature 1989;342:920–923.

Stöckel K, Schwab M, Thoenen H. Comparison between the retrograde axonal transport of nerve growth factor and tetanus toxin in motor, sensory and adrenergic neurons. Brain Res 1975a;99:1–16.

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Stöckel K, Schwab M, Thoenen H. Role of gangliosides in the uptake and retrograde axonal transport of cholera and tetanus toxin as compared to nerve growth factor and wheat germ agglutinin. Brain Res 1977;132:273–285.

Stöckel K, Thoenen H. Retrograde axonal transport of nerve growth factor: Specificity and biological importance. Brain Res 1975;85:337–341.

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Thoenen H. Induction of tyrosine hydroxylase in peripheral and central adrenergic neurones by cold-exposure of rats. Nature 1970;228:861–862.

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Thoenen H, Hürlimann A, Haefely W. Dual site of action of phenoxybenzamine in the cat’s spleen; blockade of alpha-adrenergic receptors and inhibition of reuptake of neurally released norepinephrine. Experientia 1964;20:272–273.

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Index

Abbott, G. W., 397

Abe, T., 400

Acuna, C., 367

Adams, H., 247

Adelman, G., 179

Adelson, D., 303

Adhya, S., 388

Aghajanian, G., 441

Aitkin, L. M., 490

Albe-Fessard, D., 280, 282

Albright, T., 140, 142, 144

Alsop, J., 239

Altman, J., 118, 148

Amara, S., 395

Andersen, R., 367, 369

Anderson, P., 207, 208

Angeletti, P., 528

Aoki, K., 253, 255

Arai, H., 397

Arakawa, Y., 542–43

Aramori, I., 400

Armstrong, K., 145

Arsenal, E., 441

Atluri, P., 369

Axel, R., 396

Axelrod, J., 192, 194–98, 428–31, 458, 462–63, 466, 525, 526, 528

Azzopardi, P., 145

Balercia, G., 303

Banerjee, S., 437–38

Baraban, J., 448

Baranano, D., 457

Barchas, J., 431

Bard, P., 354–56, 359, 362, 371

Barde, Y.-A., 535, 537, 539–42, 547, 552

Barlow, H., 127

Barnard, E., 395–96

Barrett, C., 90–91

Bauer, J., 180

Bäumer, E., 237

Bekesy, G. von, 171–72

Bender, D., 124, 125, 128, 139, 143–44

Bennett, E., 74–77

Bennett, J., 436, 447

Bentivoglio, M., 303–4

Benzer, S., 19, 242

Berg, P., 392

Berger, F., 10

Berkowitz, E., 279, 286

Berman, A. J., 270, 271, 358

Berman, G., 149–50

Bhandari, R., 450

Bigler, F., 525

Birch, E., 181

Bird, T., 204

Bitterman, G., 16

Bizzi, E., 52, 58, 118, 182

Black, I., 199, 201

Blalock, A., 351–53, 355

Blasdel, G., 248

Blech, D., 467, 468

Blech, I., 467, 468

Bloch, H., 529

Bloom, F., 200, 204, 206, 221

Blumberg, J., 326–27

Boehning, D., 449, 456

Bolden, D., 304

Boname, J. R., 269

Bond, D., 431–32

Boring, E. G., 170–71

Borjigin, J., 429–30

Bornstein, M., 147

Bossom, J., 177

Braas, K., 445

Bradwejn, J., 214

Brady, R., 8, 9

Brandt, T., 181

Brecha, N., 298–99

Bredt, D., 453–55

Brennan, P., 404

Brodie, B., 196

Brookhart, J., 371

Brooks, D., 39

Brooks, G., 92

Brown, D., 425–26

Bruce, C., 139–40

Bruns, F., 445, 446

Buerger, A., 128–29

Bullock, T. H., 253, 285–87, 362, 493–94

Burgen, A., 193–94, 200

Burgess, D., 290, 291

Burkhalter, A., 428

Burnett, A. L., 454

Burt, D., 442, 444

Butter, C. M., 143

Calford, M. B., 490

Calvin, M., 18–20

Cameron, A., 453

Cameron, H. A., 148

Carey, F. M., 124

Carii, G., 361, 366

Carlsson, A., 443

Carraway, R., 334–36

Carter, N., 431–32

Carughi, A., 86

Casseday, J. H., 491, 503

Castiglioni, A. J., 295, 297

Caute, D., 99

Chagas, C., 144

Chakraborty, A., 451

Chang, M., 333

Chassis, H., 326

Chaung, D. M., 460

Chorover, S., 118, 119

Clark, W. M., 346

Clark, W. S., 230–31

Clement-Cormier, Y. C., 203

Cohen, I. B., 106

Cohen, S., 390, 391

Colombo, M., 142, 143

Conant, J., 73

Condon, C. J., 491

Coon, S. L., 430

Cooper, F. S., 494

Costa, M., 196–97

Counselman, M. H., 373

Covey, E., 491, 503

Covian, M., 356

Cowan, M., 141, 283, 368, 369, 464

Cowey, A., 115, 117, 124, 128, 145

Coyle, J., 433, 465

Creese, I., 442, 443

Crittenden, P., 325

Cuatrecasas, P., 437, 438

Cuello, C., 205

Cushman, D. W., 393

D’Amato, R. J., 448

Dan, K., 484–85, 507

Dandy, W., 353

Darian-Smith, I., 361

Dartnall, H. J. A., 279

Darwin, C., 146–47

Daumier, H., 17

d’Avella, A., 58

Davies, P., 358

Davis, H., 488

Davis, R., 16, 17

Dawson, T. M., 452, 455

Dawson, V. L., 452, 455

Deaver, Commander, 349

de Kruif, P., 5–6

Desimone, R., 139–42

Diamond, A., 71

Diamond, M. C., 75, 77–80, 82–84, 88

Dichgans, J., 181

Dickinson, D., 89

Dingman, W., 13

Dixon, R. A., 397

Doane, B., 365

Doré, S., 457

Dormann, U., 542

Doupe, A., 245

Dryja, T. P., 402

Durham, D., 295–96

Duvoisin, R. M., 400

Eckenstein, F., 552

Edgar, D., 542, 553, 554

Efstathiou, A., 180

Ehret, G., 491

Eichel, L. E., 131

Eipper, B. A., 390

Eliasson, M. J., 458

Elkes, J., 431, 432, 434

Emlen, J., 240

Epps, L., 433

Erspamer, V., 394

Evans, E. F., 489, 490

Evarts, E., 39, 41–43, 365–66

Falk, G., 401

Fallah, M., 145

Farb, D., 337

Feldman, 52

Feldman, S., 293, 294

Feldon, P., 290

Feldon, S., 290

Feng, A. S., 500

Ferris, C., 448–49, 455

Fessard, A., 281

Finke, R. A., 181

Fischer, J., 433

Fishman, M., 455

Flexner, J., 16

Flexner, L., 16

Fodor, I., 149

Fogassi, L., 146

Freedman, S. J., 177

Freeman, S. B., 209

Freeman, W., 133

Frishkopf, L. S., 488

Fulton, J., 112, 113, 268, 270, 371

Furstman, L., 294

Furuichi, T., 449

Gaddu, M., 205, 333–34

Gagnon, C., 533

Gaioni, S. J., 501

Galambos, R., 488

Gao, E., 505

Garthwaite, J., 453

Gates, T., 299

Gattass, R., 144

Gaufo, G., 83

Gaze, R. M., 21

Georgopoulos, A. P., 367, 368

Gerard, R. W., 12–13, 15, 18, 23

Geronomus, L., 337

Gerstein, G., 121

Glatt, C. S., 454

Glowinski, J., 195–97, 430–31, 463

Gochin, P., 141

Goldring, W., 326

Goldstein, A., 437

Goldstein, J., 217

Goldstein, M. H., Jr., 488

Goldstein, S. A., 397

Golovchinsky, V., 295

Goodglass, H., 118

Gottesman, M., 388

Gould, E., 115, 148

Gould, R., 447

Gould, S. J., 131, 146

Gralla, R. J., 216

Graybiel, A. M., 180

Graziano, M., 145, 146

Green, A., 433, 434, 437

Greenberg, D. A., 444

Griffin, D. R., 107, 137, 491–93

Grinnell, A. D., 491, 492

Gross, C. G., 107, 114, 116, 119–24, 126–29, 139, 140, 142, 143, 145–48, 150

Gurney, M., 244

Guttmann, S., 466

Gwiazda, J., 181–83

Hackett, F., 325

Hagiwara, S., 285–87, 485, 486, 494

Halata, Z., 306

Hall, Z., 198

Hamburg, D., 431

Hamburger, V., 551

Hammerschlag, R., 331–32

Hamori, J., 289

Hanfman, E., 175

Hara, M., 460

Hardt, M. E., 180

Harlow, H., 180

Harrison, C., 356

Hattori, T., 501

Hayaishi, O., 385, 386, 388

Hayashi, M., 553

Hayashi, Y., 400, 403

Hebb, D., 75

Heiligenberg, W., 250

Hein, A., 176–77, 180, 183

Heinemann, S., 398–99

Held, R., 168, 174, 176, 177, 180–81

Hendry, I., 201, 202, 530

Henneman, E., 355

Heric, T., 285

Herrnstein, R., 132–33

Hertting, G., 192, 195

Hess, D. T., 456

Hess, E., 10

Heumann, R., 549

Hikida, T., 410

Hirano, T., 405–6

Hirose, T., 392

Hogan, N., 53

Hökfelt, T., 200–201, 205

Hokin, L. E., 9

Hokin, M. R., 9

Hollmann, M., 399

Holloway, R. L., 79

Holmes, E., 143

Hopson, J., 75

Huang, P., 455

Hubel, D. H., 127

Hudson, L., 115

Huganir, R., 448–49, 466

Hughes, J., 205, 208, 439, 440

Huxley, A., 191, 192

Hwarinen, J., 365

Imura, H., 390

Innis, R. B., 447, 468

Ishii, T., 400

Ishitani, R., 460

Iversen, L. L., 193, 195, 199–202, 204, 206, 212

Iversen, S. D., 194, 197, 201, 208, 213, 218, 220, 221. See also Kibble, S.

Iwai, E., 128

Iwakabe, H., 402

Jackson, D. A., 389

Jacobson, S., 181

Jaffe, J., 437

Jaffrey, S., 456

Jahr, C. E., 401

Jarrott, B., 199

Jasper, H., 365

Javitch, J., 447–48

Jen, P. H.-S., 498, 499

Jessell, T., 206

Ji, W., 505

Jingami, H., 407

Johnson, R. E., 80

Johnston, G., 200

Julius, D., 396

Kaba, H., 404

Kadotani, H., 408

Kajisa, L., 80

Kakidani, H., 392

Kanazawa, I., 205

Kaneko, S., 409–10

Kanwal, J. S., 498, 502

Kaplan, J. K., 98

Karabel, J., 104, 125

Katsuki, Y., 484–89, 491–92, 507

Katz, B., 198

Katz, L., 243–44

Kawabata, S., 406

Kawasaki, M., 501

Kelly, J., 202

Kenton, B., 291–92

Kerr, F. W. L., 290

Kety, S. S., 8, 363, 425, 427, 431

Keverne, E. B., 404

Kiang, N. Y., 488, 490

Kibble, S., 191–92. See also Iversen, S. D.

Kies, M., 426

Kim, S., 444

Kimani, J., 86

Kirkpatrick, D. B., 291

Kitabatake, Y., 410

Kitamura, N., 393–94

Kitano, J., 406

Klee, J., 175

Klein, D. C., 430

Klinger, P., 15–16

Knight, R., 91–92

Knudsen, E. I., 248, 252, 500

Koehler, W., 166–71, 173, 174, 176, 239

Kornhuber, H. H., 361

Konishi, E., 500

Konorski, J., 126, 127

Koos, B., 307

Korshing, S., 547

Kosterlitz, H., 205, 440

Kotani, H., 394

Kozorovitskiy, G., 148

Kramer, M. S., 215

Kravitz, E., 197, 198

Krech, D., 74–76

Kruger, L., 269, 271–74, 278, 282–86, 288–95, 297–308

Kubo, T., 397

Kuffler, S., 197, 199

Kuhar, M. J., 438, 440, 465

Kumazawa, T., 297, 303

Kunishima, N., 407

Kuno, M., 396

Labos, E., 292

LaDu, B., 426

LaMotte, R. H., 361, 364, 366, 367

Landau, S., 297

Langemann, A., 525

Lederberg, J., 465

Lee, A., 305

Lee, C. M., 206, 447

Leehey, S. C., 181

Leeman, C., 330, 332, 335

Leeson, P. D., 212

Lefkowitz, R. J., 398

Lehman, S., 92

Leonardi, A., 304

Leonardo, A., 246

Leonardo da Vinci, 147

Leonbruno, F., 100

Leontovitch, T., 283

Lettvin, J., 127

Leuner, B., 148

Levi-Montalcini, R., 40, 528, 529, 534, 535, 547, 551

Lewicki, M., 245–46

Lewis, S., 5–6

Liberman, A. M., 233, 494

Liebeskind, J., 297

Lindner, D., 450–51

Liu, W., 500

Logan, W. J., 436

Lorente de Nó, R., 304–5

Lorenz, K. Z., 11, 239

Lowenstein, C., 454

Luo, H. R., 451

Lynch, J. C., 367

Lynen, F., 11

Lyons, W. E., 452

Ma, X., 503–5

Mackay, A., 201, 204

MacKinnon, D., 143

Magalhaes-Castro, H. H., 295

Magoun, H. W., 37, 278, 279, 283, 286

Mains, R. E., 390

Malis, L., 269–71, 276, 277, 289

Malkasian, D., 79

Manabe, T., 491, 500

Manning, D., 447

Manning, R., 128

Mantyh, C., 299, 301–3

Mantyh, P., 299

Marey, E.-J., 281

Margoliash, D., 245, 246, 501

Mark, R., 84

Marler, P., 233, 237, 238, 240, 241

Martin, J., 336

Maslow, A. H., 169, 174, 175, 177

Masu, M., 398, 399, 402

Masu, Y., 396

Masugi, M., 408

Matsumura, S., 502

Matthews, M., 288

Maxwell, D., 287–90

Maxwell, R., 463–64

McCasland, J., 245

McConnell, J., 14–15

McCullough, C., 174

McDonald, J., 305

Mckenzie, A., 81

McKhann, G., 370

McKnight, A. T., 215

Melnechuk, T., 179

Mendelson, J. R., 491

Menkin, V., 107

Merker, B., 181

Merril, C., 430

Merzenich, M. M., 489

Meyer, A., 347

Micevych, P. E., 297–98

Michaelson, A., 430

Michel, F., 284

Mihailivic, B., 114

Mikaelian, H., 177

Miller, A. H., 233, 235

Miller, C., 87

Miller, E., 141–42

Miller, G., 132

Miller, J. G., 12

Miller, R., 203, 290

Mishkin, M., 119, 120, 128, 139, 142–43, 180, 194

Mishler, P. C., 102

Mitchell, S. J., 405

Mitra, P. P., 250

Moffat, A. J. M., 491

Mohindra, I., 181, 182

Moiseff, A., 249

Molnar, C. E., 488

Moncada, S., 453

Montague, A., 106

Moore, T., 145, 146

Morant, R., 175, 176

Moriyoshi, K., 399

Morris, H., 205

Morrison, B. H., 451

Moruzzi, G., 37–39

Mosconi, T., 305

Mosso, J., 291

Mothet, J.-P., 459

Motter, B., 367

Mountcastle, V. B., 355, 356, 358, 359, 361, 364, 365, 367, 369, 371, 506

Movshon, J. A., 142

Mudry, K. M., 500

Mueller, B., 526

Muller, S., 369–70

Munson, P., 328–30

Murikawa, K., 407

Murphy, K., 447

Mussa-Ivaldi, F. A., 54, 55, 59

Naegele, J., 181

Nagata, E., 451

Nagata, T., 293

Nakahara, K., 406

Nakajima, Y., 402

Nakanishi, S., 388, 390, 391, 393, 394, 397–400, 402–5

Nakayama, K., 396

Nawa, H., 394, 395

Nawy, S., 401

Neal, M. J., 199, 201

Nelson, R., 455

Neubert, J. K., 305

Newman, E., 171

Newman, E. B., 132

Nishikawa, T., 458

Noble, E., 431

Noda, M., 392

Nomoto, M., 488

Nomura, A., 402

Nowozcek, G., 538

Numa, S., 386–89, 397

Ohfune, Y., 403

Ohishi, H., 405

Ohkubo, H., 393–94

Ohlemiller, K. K., 502

Okada, M., 406

Okamoto, N., 400

Okayama, H., 392

Olney, J., 211

Olsen, J. F., 501

Ondetti, M. A., 393

O’Neill, W. E., 500

Oppenheimer, J. R., 176

Oscar-Berman, M., 129

Otis, T. S., 308

Otsuka, M., 198

Ott, C., 80

Owen, R., 147

Pappenheimer, J., 336

Pastan, I., 388

Pasternak, G., 439–40, 467

Patterson, R., 449

Peierls, G., 149

Perl, E. R., 290–91, 295, 298, 356, 363

Peroutka, S., 444, 445

Perrett, D., 127, 140

Pert, C., 438, 440

Pettigrew, J., 247, 248, 250, 251

Pevsner, J., 446

Pfeiffer, R. R., 488, 497

Pinsk, M., 148

Pletscher, A., 519, 520

Poeppel, E., 180

Poggio, G. F., 359–61, 368

Pompeiano, O., 39, 40

Porter, P., 272

Potter, R. K., 494

Powell, T., 283, 359

Pribram, K., 269–71, 273

Protti, A. M., 80

Quarton, G., 20

Quiroga, R. Q., 128

Radin, N., 13

Rall, T., 445

Ravitch, D., 99

Ray, R. H., 295, 297

Reivich, M., 430

Rekosh, J., 177

Renoux, G., 83

Repp, A., 145

Resnick, A., 451

Ricci, G. F., 365

Rich, A., 347

Richelson, E., 434

Richmond, B. J., 127

Riquimaroux, H., 501

Rizzolatti, G., 146

Rocha-Miranda, C. E., 124–25, 139, 144

Rodin, B., 297, 298

Rodman, H., 141–43, 145

Rolls, E., 127

Romo, R., 365, 369

Rose, J., 273, 276, 277, 287, 288, 358, 359

Rosenberg, L., 426

Rosenblatt, R., 131

Rosenzweig, M., 14, 74–76

Ross, R., 368, 465

Rossor, M., 204

Rupert, A., 488

Russell, D. H., 435–36

Ryan, K., 336

Sabatini, D., 452

Sachs, M. B., 488

Saiardi, A., 450

Saitoh, I., 501

Sakagami, S., 232–33

Sakata, H., 365, 367

Sakurada, K., 400

Samuel, D., 20

Sandberg, B., 206

Sandell, J., 147

Saner, A., 525

Saporta, S., 293, 297

Sattin, A., 445

Sawa, A., 460

Schäfer, T., 553

Schapiro, M., 164–67, 174

Scheibel, A., 72, 85, 86, 88

Schell, M. J., 459

Schimke, R., 390, 391

Schlank, M., 177

Schlegel, P., 497

Schmitt, F. O., ix, 7, 18–20, 179, 252

Schneider, G. E., 119

Scholander, P., 286

Schon, F., 201

Schreiner, C. E., 491

Schwab, M., 530, 531, 536, 537, 553, 554

Schwartz, E., 141

Schwartzkopf, J., 235–36, 238

Schwartzkroin, P. A., 124

Schwassmann, H., 285

Seacord, L., 143

Sedlak, T., 457–58

Seeman, P., 203, 443

Sendtner, M., 542–44

Shadmehr, R., 55, 59

Shapiro, L., 98

Shattuck, S., 180

Shiells, R. A., 401

Shigemoto, R., 397, 405–6

Shimojo, S., 181

Shimozawa, T., 497

Shinozaki, H., 403

Sillevis-Smitt, P., 406

Silver, R. A., 405

Silverman, J., 300, 302, 303

Simantov, R., 440

Siminoff, R., 290, 291

Simmonds, M., 199

Simmons, J. A., 496

Simon, E., 438

Singer, M., 73–74

Singh, L., 212

Sinha, P., 183

Skinner, B. F., 105, 113, 132, 171

Smellie, F. W., 445

Snowman, A., 438, 439

Snyder, S. H., 196, 203, 205, 368, 426, 427, 429–30, 432–36, 438, 441, 442, 446–47, 449, 453–54, 458

Sousa, A. P. B., 144

Spencer, A., 38–39

Sperry, R., 77

Sporn, M. B., 13

Squire, L. R., 228

Stamler, J., 456

Stanley, A., 435

Staub, H., 519

Stebbins, L., 234

Stein, B., 292–93

Steiner, J., 452

Steinmetz, M. A., 365

Stephens, F., 73

Steranka, L., 447, 468

Sternini, C., 299

Stevens, S. S., 171, 173

Stoerig, P., 145

Stone, C., 207, 208

Suda, K., 535, 547

Suga, N., 484, 486, 488–93, 497–505

Sullivan, T., 249

Supattapone, S., 448–49

Sutter, M. L., 491

Swanson, L., 297, 299, 307

Symons, J., 73

Tachibana, M., 386, 387

Taii, S., 390

Takahashi, K., 407

Takahashi, M., 456

Takumi, T., 397

Talbot, W. H., 361, 365, 367

Tamashige, M., 231–32

Tanabe, Y., 400

Tanaka, K., 394, 397

Taylor, C., 146

Taylor, I. A., 427

Temkin, O., 278

Teuber, H.-L., 43, 118–22, 124, 178, 179, 271

Theophrastu, S., 106

Thoenen, H., 524, 543

Thorn, F., 182

Thudichum, J. L. W., 23

Tranzer, J.-P., 522, 524, 525, 535

Tresch, M. C., 57

Tricklebank, M. D., 213

Tsuzuki, K., 491

Tunturi, A. R., 488

Tyler, D. B., 495

Uhl, G., 447

Ungar, G., 15

Unger, R. K., 123

Ungerleider, L. G., 119

U’Prichard, D. C., 442, 444, 467

Uretsky, N., 201

Uylings, H. B. M., 79

Vaina, L., 140

van Rossum, D. B., 449

Vaughan, H., 121

Verma, A., 456

Voglmaier, S., 450

von Bekesy, G., 132

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Wada, N., 412

Walker, E., 363

Wallace, R. B., 392

Wallach, H., 166, 169

Walters, H., 446

Walzl, E. M., 488

Washburn, S., 234

Watanabe, D., 404, 408

Watanabe, T., 491

Watjen, F., 212, 213

Watkins, C., 455

Watson, J. B., 108, 171, 273

Webster, W. R., 490

Wehner, R., 254

Wei, J. Y., 302–3

Weinberger, N. M., 505–6

Weingarten, S., 296

Weiskrantz, L., 112, 114, 116–18, 180, 192, 194, 218

Werner, G., 292, 360, 361

Whitby, G., 192–94

White, B., 177

White, J., 90–91

Wiesel, T. N., 127

Wigglesworth, V. B., 491

Williams, B., 215

Wilson, D. M., 234, 237

Witkovsky, P., 284

Wolfe, J., 181, 182

Wolosker, H., 459

Wong, E., 210

Woodhall, B., 354

Woolsey, C. N., 488

Woolsey, T., 295, 296

Worley, P., 448

Wu, Y., 505

Wurtman, D., 428, 429, 526

Wurtz, R. H., 127

Xiao, Z., 504

Xide, X., 75

Xin-Tien Hu, 146

Yamamoto, M., 412

Yamamura, H., 438, 441

Yan, J., 503–5

Yan, W., 503

Yang, L., 490

Yeh, Y., 298

Yin, T. C. T., 367

Yokoi, M., 407

Yokota, F., 397–98

Yoshida, K., 410–11

Yoshida, Mr., 230, 231

Young, A. B., 440–41

Young, L., 181

Young, R., 294

Zakhary, R., 456

Zangwill, O. L., 111, 115

Zeigler, H. P., 123

Zhang, Y., 503, 505

Zitron, C. L., 99

Zukin, S., 442