EDITORIAL ADVISORY COMMITTEE

Verne S. Caviness

Bernice Grafstein

Charles G. Gross

Theodore Melnechuk

Dale Purves

Gordon M. Shepherd

Larry W. Swanson (Chairperson)

The History of Neuroscience in Autobiography

VOLUME 2

Edited by Larry R. Squire

ACADEMIC PRESS

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Copyright © 1998 by The Society for Neuroscience

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98   99   00   01   02   03   EB   9   8   7   6   5   4   3   2   1

Contents

Lloyd M. Beidler

Arvid Carlsson

Donald R. Griffin

Roger Guillemin

Ray Guillery

Masao Ito

Martin G. Larrabee

Jerome Lettvin

Paul D. MacLean

Brenda Milner

Karl H. Pribram

Eugene Roberts

Gunther Stent

Lloyd M. Beidler

BORN:

Allentown, Pennsylvania

January 17, 1922

EDUCATION:

Muhlenburg College, B.S. (1943)

Johns Hopkins University, M.S. (1944)

Johns Hopkins University, Ph.D. (1951)

APPOINTMENTS:

Florida State University (1950)

Professor Emeritus, Florida State University (1992)

HONORS AND AWARDS:

National Academy of Sciences U.S.A. (1974)

American Academy of Arts and Sciences (1975)

Lloyd Beidler carried out pioneering physiological studies of chemoreception working with a variety of species and sensory systems. He carried out psychophysical studies with sensory nerves, and he demonstrated turnover in sensory cells. He is an authority on the sensory physiology of taste.

Lloyd M. Beidler

My Early Life

My interest in science as a possible career started when I was a senior in college. Most of the attitudes, skills, and philosophy utilized in my scientific career, however, were developed long before. The effects of growing up with family stability, in a semirural environment, and with great personal freedom were reflected throughout my life.

My father’s family were Mennonites whose origin can be traced to 1736 in Pennsylvania. My mother’s family emigrated from Germany more recently. My father left school after eighth grade and became a railroad clerk in Bethlehem, where my mother also worked after she graduated from high school.

I was born in 1922 in Allentown, Pennsylvania. My two sisters Rose and Doris were born a few years earlier. When I was about 6 months old, my father purchased half of a two-home dwelling in a newly formed rural development north of Allentown. The house was 20 feet wide and two and half stories high. We were on the edge of the development and faced a large farm. About 300 feet from our house was a large abandoned iron ore pit which was used as a trash dump by the city. The church was our only social center. It contained a large worship area, a small, one-room library on the first floor, and a basement where the Boy Scouts and other social groups met. The village had only one store, located in the large front room of a house. We children had no playground or any other gathering place. As a result, my chief entertainment as a boy was at home and at the trash pit, which became the source of parts for any toy I desired, including my first and only bicycle. Later the pit became the source of parts for electrical devices and components for radios. Thus the pit contributed greatly to my interest in the physical sciences.

My father worked hard and followed a rigorous schedule from the time I was born until after I graduated from college. He assigned jobs of cutting the grass, weeding the garden, and taking the coal ashes outside, and they had to be accomplished on time. Serious offenses were followed by spankings but I soon learned to avoid them. When my chores were finished I had almost complete freedom but I had to be home when my father returned from work. Home rules were strict and clear, but because my sisters and I obeyed them, we had an unusual amount of independence. My father was an avid reader and we three children again followed his example.

The depression greatly impacted my life as it did most people of the time. We collected rainwater from the roof of the house and stored it in an underground cistern. A hand pump in the kitchen brought the water up from the tank. My mother heated water on a wood stove for our baths every Saturday night. Our toilet was an outhouse about 20 feet from our dwelling. We converted the house to indoor plumbing when I was in high school. Today this type of living seems primitive but then it was the norm and most families were considered neither poor nor wealthy. My life, and those of my friends, was greatly influenced by the immense social and economic upheaval produced by the great depression and World War II. Simultaneously, though, the rewards of science were noticeable. Electrification was spreading rapidly to rural areas. Electric-powered delivery trucks were being replaced by noisier but faster gasoline-powered trucks and roads were being constructed. As a boy, I ran outside if I heard a small plane. Radio was introduced and television came later. The practice of medicine was still primitive and we waited until shortly before the war before antibiotics were available. These were tough but exciting times for a future scientist.

My formal education started in a two-room, six-grade schoolhouse. Mrs. Kistler, a motherly teacher with 2 years of normal school education, taught the first three grades. I then moved across the hall to Mr. Kistler’s class for the next three grades. I still remember doing my arithmetic assignment in Mrs. Kistler’s class while others were either singing or reading in the same room. In winter the classes would be interrupted by students who had to get dressed to go to the outhouse. The mental discipline needed to study at school was also useful at home because neither of my parents could help with homework. My father, however, carefully scrutinized our monthly school grades.

Middle school and high school were quite different. We were bussed several miles to the middle school, but walked only about a mile to the high school. The buildings were modern and the teachers quite accomplished and well educated. The high school curriculum was broad and included arts, music, and industrial training every year. My experience in wood working and metal lathe operation was helpful years later when I had to make much of my own research equipment. The most interesting courses for me were chemistry and physics. I obtained permission to do experiments in both laboratories instead of attending a study period. My experiment in the physics lab was to build a Tesla spark producer. Another student and I used a high-voltage transformer from an old neon sign. We fed the high voltage into a coil made from ¼-inch-diameter copper tubing which served as the primary winding of the Tesla device. The secondary winding consisted of No. 22 wire wound on a 6-inch-diameter and 30-inch-high cardboard cylinder that we obtained in a dress shop. Our Tesla device produced a very high-voltage but low-current spark about 10 inches long. Our teacher never came into that part of the laboratory while we were experimenting! We demonstrated the coil to the class with dramatic results. During my senior year I did a series of chemistry experiments on making dyes and applying them to different types of cloth. The principal often came into the lab and showed his interest by asking questions.

My father and I never discussed future plans and I had little idea of what I might do after graduation. However, when I was a senior, my high school principal took me to see the dean of a local liberal arts college, Muhlenberg College. The meeting resulted in a scholarship and a change in my life.

Muhlenberg College in Allentown

The depression was still being felt when I entered college in 1939. Fortunately the cost of a college education was not high. I bicycled to college and carried a packed lunch. I dusted library books 10 hours a week and was paid 40 cents an hour. That federal program helped the college and allowed me to graduate without owing a debt to the government. I also worked in a grocery store every Saturday and as a laborer in the Bethlehem steel plant during the summers. Thus, my father had only to contribute 100 dollars for each year of my undergraduate experience. This seemingly small amount, however, was approximately what my mother was given to feed the family for 5 months.

As a boy I built a radio with a triode vacuum tube, a variable capacitor, a resistor, and a self-wound inductance, all from components found at the trash pit. To this day I still remember the thrill of hearing my first successful radio receptions. Such experiences influenced my decision to major in physics in college.

The chairman of the physics department, Dr. Ira Zartman, received his doctorate from the University of California and was one of the first researchers to measure molecular velocities. He left Muhlenberg when I was a sophomore and went to Johns Hopkins University to organize a research and development group for the Navy. This left a rather young faculty to teach physics to about six physics majors as well as general physics to the science majors. We physics majors had a close relationship with the professors; one of them took us on a hiking trip through the mountains of Vermont during our junior year. The attack on Pearl Harbor was announced on radio while I was a junior studying for an exam in atomic physics. The government responded quickly by organizing new research groups to design and build weapons. Our physics curriculum at Muhlenberg changed rapidly as a result. We physics majors wanted to respond to the need of the military for scientists in electronics and for physicists both to work in the new government laboratories and to help train newly inducted men.

Johns Hopkins in Baltimore

A few months before I graduated from Muhlenberg College in December 1942, I received a phone call from Dr. Zartman. He had learned that I had received offers to join a research group in Oak Ridge, Tennessee, and to teach at a University in New York. He asked me to consider the physics department at Johns Hopkins University in Baltimore. Two months later I accepted a junior instructorship as a graduate student in physics at Johns Hopkins.

I received an M.S. in physics after a year of graduate work and I was again approached by Dr. Zartman. He was desperately searching for more researchers for the naval laboratory located just one floor beneath the physics department! The mission of this group was to develop proximity fuses that could not be jammed. The antiaircraft shells had small radio transmitters which were energized when the shells were shot toward a flying aircraft and the transmitted beam was reflected by the aircraft back to the shell. When the signal was large enough, the shell exploded. These new antiaircraft shells were very effective; more than 90% of the Japanese attack planes were being destroyed in the Pacific in a single encounter. However, the shells could be harmlessly exploded on the way to their target if a radio transmitter at the same frequency as the shell was operating in the vicinity of the planes. The new research mission was to design electronic fuses that would not respond to the enemy’s attempt at jamming. I joined this group and developed new electronic designs. The fuses were then tested for their radiation patterns by four women in the laboratory. One of these women, Mary Lou, became my wife. She had recently graduated from Goucher College in Baltimore, majoring in physics. Her interest in science had led her to join the Civilian Pilot Training program, which was supported by the government to form a group of women that might be called on later to learn to fly larger planes that could be shuttled to England. It was in this program that she obtained her pilot license.

Johnson Foundation for Medical Physics, University of Pennsylvania

I believed that most biological processes could be explained by a series of physical and chemical events and that someone with my training could contribute to advances in biology and medicine. I discussed my interests with Dr. Samuel Talbot of the Wilmer Institute of Ophthalmology and this led to the opportunity to work in his laboratories in the evenings and hear his views of the future of biophysics. He encouraged me to enter the new field of biophysics when the war was over in 1945 and I applied to the Johnson Foundation for Medical Biophysics at the University Pennsylvania. The director, Professor Detlev Bronk, had performed the first recording from a single nerve fiber in Lord Adrian’s laboratory in Cambridge, England, while he was a postdoctoral fellow. (This research led to the establishment of the famous sensory law relating the frequency of nerve firing and the number of nerve fibers responding to the intensity of sensory response, an important contribution to the total research for which Adrian received the Nobel Prize.) The Johnson Foundation had previously trained many postdoctoral fellows but few predoctoral students.

The faculty included Drs. Frank Brink, Martin Larrabee, and Phil Davies in neurophysiology, Keffer Hartline in vision, and Tom Anderson in electron microscopy. There was no defined curriculum except that everyone had to take human physiology in the medical school. I also studied general physiology with Lewis V. Heilbrunn, chemical embryology with Jean Brachet, and x-ray diffraction with A. L. Patterson. We were required to take three of the five exams required of the doctoral students in the department of physics and show competence in German and French. The program was more like a research apprenticeship. All of the students were very close to the faculty.

We arrived in the laboratory at about 9:00 AM, ate lunch together in the library room, and left the laboratory at about 10:00 P.M. Each student was assigned to a professor and worked in his office–laboratory. I worked with Frank Brink but he never assigned me a research project. Thus, I made my own decision and chose to study frog embryonic development. After my first year at the Johnson Foundation I married Mary Lou who then became a graduate student and assistant in physics at Bryn Mawr College. Her major professor was A. L. Patterson, who had developed a mathematical method for analyzing x-ray diffraction patterns of crystals and determining their three-dimensional atomic structure. This he did while also serving as a lecturer for several years at the Johnson Foundation where he was attempting to determine the atomic structure of proteins. My marriage caused a stir among the graduate students because, unknown to me, Dr. Bronk had an unwritten rule that Johnson Foundation students should not marry until after they had obtained their Ph.D.

Professor Bronk was very active in the National Research Council of the National Academy of Sciences as well as many other scientific organizations, and seldom was in his office in the daytime. However, he was often at the Foundation in the evening. One evening he asked me about my dissertation plans. As a graduate student I had been independent and had chosen my own dissertation topic without first talking with Dr. Bronk. I had taken graduate courses in quantum mechanics, theory of molecular structure, valence theory of organic chemistry, and statistical mechanics, and thought I would study the interaction of ions and molecules in a biological system; specifically the interactions of ions and molecules with taste and olfactory receptors. Dr. Bronk was not pleased with my choice of research and suggested instead that I study under Adrian in Cambridge, England, who already had written several papers on olfaction. This suggestion came as a shock to me because Mary Lou, who was now working in x-ray diffraction at the Franklin Institute, and I had no resources to move to England.

Within a few weeks my problem was unexpectedly solved. Dr. Hartline announced that Dr. Bronk was to become president of Johns Hopkins University and that he was to become chairman of a new department of biophysics that was to be located next to a building that housed the departments of biology and psychology. He said that he would like to form good relationships with both departments and that I could help him if I would consider selecting a dissertation in the field of either taste or olfaction because both Vincent Dethier of biology and Elliot Stellar of psychology were interested in the chemical senses! I was ecstatic. Both Mary Lou and I loved Johns Hopkins and we still had friends there. It became apparent to me later that Keffer Hartline knew of my previous conversation with Dr. Bronk about my interest in the chemical senses, but neither Keffer Hartline nor I knew that I would form a lifetime relationship with both Vince Dethier and Elliot Stellar and that Curt Richter would later ask me to do research in his laboratory after I received my Ph.D.

Back to Johns Hopkins

Several months later, all the students and the neuroscience component of the faculty moved to Johns Hopkins. I started my research with the blowfly by investigating the neural response of the peripheral nerve to chemical stimulation of the leg. After several months of failures I switched to studying the taste responses of the rat by recording from the chorda tympani nerve. The magnitudes of the responses were disappointing and after several months of failures, Hartline suggested I contact Professor Carl Pfaffmann at Brown University. Pfaffmann was most helpful and suggested I visit his laboratory. Several weeks later Mary Lou and I journeyed by bus to Providence, Rhode Island. This proved to be an excellent and helpful trip. I soon learned that Carl had been a postdoctoral fellow with Bronk at the Johnson Foundation for a year after Carl received his Ph.D. in physiology with Adrian in Cambridge! Thus, we had many common friends. Carl spent an entire day showing me the tricks of taste nerve recording. Not only did we become lifetime friends, but he taught me the importance of behavioral science in the study of the senses. Although I was a student and he a professor, he always treated me as an equal. At no time did this relationship ever change. In later years he sent me many of his newly granted Ph.D. students for additional postdoctoral experience.

After returning from Dr. Pfaffmann’s laboratory, I used his methods to record from the chorda tympani of the rat. My first recording equipment was primitive. I pushed a 6-foot-long table against another one and suspended a black cloth from the ceiling to separate the two. Alongside my table was a Cambridge camera which contained a string galvanometer, a carbon arc, and a container for photographic paper 6 inches wide and many meters in length. The electrical activity fed into an electronic amplifier that was connected to the string galvanometer. The spark of the carbon arc was focused on the mirror of the galvanometer and the image reflected on to the photosensitive paper in the box. When the experiments were complete, I took the box into the dark room and developed the paper.

One evening I applied a high concentration of sodium chloride to the surface of the rat tongue and turned the amplifier to high. A tremendous volume reverberated throughout the room! Unfortunately, it was late at night and no one else heard the response. Because I had spent such a long time in taste research with no response as a reward, I wanted to share that night’s experience with some of the other students. I measured the voltages across the speaker coils and then plotted them as a function of time as I placed various concentrations of stimuli over the surface of the rat tongue. The results were magnificent.

The next morning the first student in the lab was Ted MacNichol, a graduate student of Hartline’s who was very experienced in electronics. He appeared impressed with the results and suggested I use a method to plot the results electronically rather than use the tedious method of manual plotting. I gave this some thought and decided to average electronically by using an RC network and a half-wave rectifier vacuum tube much as was used in AC power supplies. Thus, I had a running average of the magnitude of the neural activity in response to taste stimulation. This worked well, but the laboratory’s electrical engineer, John Hervey, later designed a much improved instrument. I thought of using this method of measuring taste response to determine appropriate concentrations of taste stimuli to use when recording from single taste nerve fibers. This method was so well received by others who studied taste that it was quickly and widely adopted. It was particularly useful to researchers who studied the taste behavior of animals.

I researched many taste substances and accumulated many data, and now I needed to find a job. Dr. Hartline offered to help and I discussed my predicament with Mary Lou, who was now working in color vision at Wilmer Institute of Ophthalmology at Johns Hopkins Medical School. I remembered a short ad by Bernice Larson in Science magazine indicating that she was in the business of matching employer with employee. I answered her ad which resulted in a phone call from the dean of Arts and Sciences at Florida State University. Two weeks later, Mary Lou and I visited the university, toured Tallahassee, met other researchers who were recruited the year before, accepted an offer to begin September 1, 1950, and returned to Baltimore.

Planning for the Future

Shortly before we left for Tallahassee, Mary Lou and I had to plan for our future. What kind of a life did we want and how should we proceed? I already knew I wanted to teach and initiate a research program. What did Mary Lou envision? Her father was a very energetic engineer who had designed automobiles at a time when there were dozens of small companies competing for dominance in the industry. After the auto industry matured and only a few companies remained, he entered aeronautical engineering and designed the first variable pitch propeller for small planes. Thus, Mary Lou was raised in a family where the father was consumed by his profession.

Mary Lou chose physics as a career opportunity and obtained her M.S. from Johns Hopkins. She had experience as a scientist in a research institute, a university, and two industries before we arrived in Tallahassee. Now she was expecting a child within a few months. She decided that she would like to have several children and raise a family rather than continue a professional career in science. An integrated family was envisioned where the father as well as the mother undertook home chores and raised the children together. Mary Lou also wanted to continue to have some social contacts with scientists and share much of my travel to meetings. We agreed that we would take our children with us when traveling, either in the United States or abroad. This was accomplished even though by the time we first visited Europe and attended meetings in Stockholm, six young children accompanied us, the youngest being four years of age. Fortunately, all of her views of a family unit were similar to mine, but now we had to plan ahead or else we would never reach our goals.

First, we needed to live in Tallahassee within 10–15 minutes of the university so that I could eat lunch with the family every day and also return to the lab in the evening if needed. Furthermore, it would be very helpful if our home could be in a rural setting, with plenty of space and with construction codes that allowed me complete freedom to build whatever structures I needed.

Adjusting to Florida State University

We decided to move to Tallahassee by car. This presented a problem because my father had never owned a car, and none of my high school or college friends drove one. I had been in a car only a few times before graduate school! I knew little about how a car worked and nothing of how to drive one. I decided to employ a driving instructor for a week but first I needed a car. I soon purchased a used Kaiser sedan for $400. At the end of the week my trainer said I was ready for the exam but it would help if I gave the examiner 15 dollars for an incentive! That turned out to be good advice and the following morning, license in hand, we left for Tallahassee, not going over 40 miles per hour for the first 2 days.

Florida State University was completing its transition from a women’s college to a coeducational university with a graduate program. I was assigned to the department of physiology, which consisted of five faculty, a large undergraduate program, and a new graduate program with about seven students. I was assigned to a 10 by 12-foot room which was to serve as an office and laboratory. A long hallway connected the office with the main corridor and I immediately moved my office door to the end of the twenty-foot hallway in order to gain more laboratory space. The Dean gave me $750 in research money which I used to buy a drill press, a table saw, an oscilloscope, and an audio amplifier kit that could be assembled easily. This left about $500 for animals and supplies for the remainder of the year. I wrote a letter to the director of the Bell Telephone Labs in New Jersey and requested any surplus electronic equipment that they might be able to send to me. Several weeks later I received a large wooden box full of such helpful items.

My first research grant was from the U.S. Army Quartermaster Laboratory and the following year I was also funded by the Office of Naval Research (ONR). The latter was important because ONR supported a large number of scientists who studied the senses. Within a few months, but before equipment arrived for the grant research, I received a letter stating that I would have to submit quarterly research reports. I was disturbed and phoned Dr. Hartline for suggestions. In his rather amusing manner he suggested that I should by no means send reports to Washington, saying there would be no one there who would understand them, someone would be obligated to file them, and I would be making work for many people. I sent no reports for 5 years but then one day received a letter of apology. ONR had lost all my reports! Would I please send a one-page report of my research findings that would cover the past 5 years! I never forgot this lesson and it saved me huge amounts of time in later years.

Teaching–Research Interactions

During my early years at Florida State I had to concentrate on teaching several courses, including one on human physiology for undergraduate nonscience majors and another on sensory physiology for graduate students. I soon learned that the graduate students had no knowledge of electronics and little of shop practice so I devised a course that included both. I purchased kits of parts for audio amplifiers, oscilloscopes, audio generators, and electronic voltmeters, which the students then assembled. All the equipment used vacuum tubes.

The sensory physiology laboratory included experiments in all the sensory areas. Each student had to learn to record cat cochlear microphonics, Limulus single optic nerve fiber activity, rat taste nerve integrated responses, frog skin tactile responses, cat Pacinian corpuscle responses to tactile stimulation, and several others from a selection of another six that included the infrared receptors of the rattlesnake! Each student had to collect all his own animals except the rat. Often a student attempted to do two of the laboratory experiments on the same animal to save both time and an animal. One of the students recorded the cat cochlear microphonics and then recorded the taste response from the chorda tympani nerve on the same animal. As a result, a whole new avenue of taste research was born! We soon learned that the cat responded to taste stimuli quite differently than a rat or rabbit. This was one of the most exciting discoveries for our laboratory in 1954, since it was commonly assumed that most animals were similar in their responses to simple taste stimuli.

Irving Fishman, Clarence Hardiman, Mohessen Nejad, and Henry Tamar (students who indicated an interest in working in the sensory area), and I decided to study the taste responses of other animals such as the guinea pig, hamster, cow, pig, sheep, raccoon, and dog. All the rodents responded to sodium more than to potassium, whereas the reverse was true for the carnivores.

I was excited with our findings and immediately phoned my friend Carl Pfaffmann. I was astonished to learn that he also was studying species differences in taste, so we agreed to publish at the same time and cross reference each other.

A Colleague’s Offhand Comment Spurs Me On

The biochemistry and physiology faculty held joint seminars. In 1953 I was asked to present a seminar and decided to talk about a mathematical expression of the magnitude of taste response as a function of stimulus concentration based on the law of mass action. This mathematical expression allows one to calculate the magnitude of taste response as a function of concentration, magnitude of maximum response, and equilibrium constant of the reaction. The equation fitted the experimental data well. With some assumptions the binding energy could be calculated to be just a few kcal/mol, a very weak bond. I had never expected to publish this but one of the biochemists, Earl Frieden, thought the story was both interesting and important and urged me to publish. I reconsidered, obtained more data, and published my theory in 1954. This stimulated others to consider weak van der Waal forces instead of covalent chemical bonding in the stimulus-receptor interaction.

The Japanese Relationship

The majority of my early graduate students were World War II veterans who were receiving benefits under the GI bill. Some, such as Don Tucker, served in the marines and fought the Japanese on many Pacific islands. It was with some trepidation that I accepted my first Japanese post doc, Katsumi Kimura. He and his wife arrived in 1955. Not only did he come to the country of his former enemy, but he was introduced to our separate but equal process as soon as he stepped off the train in Tallahassee. There were two entrance doors to the station. One said ‘colored’ and the other ‘white’. Which should he chose? Was he considered white or colored? Similar differences in culture confronted the Japanese daily but they never mentioned them to me until many years later.

Dr. Kimura used microelectrodes to record from single cells of the taste buds of the rat and hamster in response to stimuli representing the four basic taste qualities; salty, sour, sweet, and bitter. Their concentrationresponse curves were similar to those obtained from neural recordings.

Our excellent experience with Dr. Kimura led me to accept another dozen Japanese scientists to come to our laboratory at FSU during the next decade. Almost half of these researched the olfactory system with the late Don Tucker. About eight are now professors in Japanese universities.

Pensacola Meetings

The Office of Naval Research held the first of a number of symposia in 1955 at the Naval Air Station in Pensacola where much of their in-house research on naval aviation medicine was conducted. All the scientists (about 40) supported by ONR in the field of sensory systems were invited to attend by Captain Ashton Graybiel, of the U.S. Naval School of Aviation Medicine. These included many of the leaders of sensory areas such as Keffer Hartline, George Wald, Clarence Graham, Georg von Bekesy, Hallowell Davis, Glen Wever, Frank Geldard, Paul Nafe, Smitty Stevens, Carl Pfaffmann, and about 25 others, including juniors in the field such as Howard Baker, Dan Kenshalo, and me from Florida State University. We gave a short summary of our research and there was plenty of time for interaction. The lectures, figures, and discussion were all published by ONR. Three of this group would later receive the Nobel Prize! Those meetings were excellent for those of us who were still in the infancy of our careers. We were exposed to the newest in all the sensory fields and became personal friends with a number of leaders. They became acquainted with us and could judge the merits of our research. Tallahassee is not far from Pensacola, and we often invited individuals to visit us and talk to our students. Many years later I gave a lecture to the psychology department at the Massachusetts Institute of Technology and met a graduate student named Ann Graybiel. I was surprised and pleased to learn she was Capt. Graybiel’s daughter. Dr. Ann Graybiel is now professor of Brain and Cognitive Sciences at MIT.

Dr. von Bekesy visited Florida State after the Pensacola meetings on several occasions. We often talked about research in taste and olfaction. He mentioned that he thought research in olfaction was not quantitative enough and also pointed out similarities between the tongue, the skin, and the basilar membrane. I was surprised to learn that he was working on a problem involving taste; he later sent me a paper where there was confusing terminology on stimulating a single papilla versus a single taste bud. He had read many of my papers and had examined pictures of single fungiform papillae from the rat, which contain only one taste bud. Human fungiform papillae, however, contain several taste buds. He thanked me for “extensive remarks on my paper on electrical taste,” and then wrote:

You may be interested in the history of this confusion. When I first described activities in the inner ear, I used the term “stimulation of the basilar membrane.” I was told that the term was wrong, since the basilar membrane is a ligament, and one cannot stimulate that. It was this experience that made me reluctant to use the term “stimulation of the papilla,” since the papilla again is supporting tissue mainly. Therefore I used the term “stimulation of the taste buds in the papilla.” The experiments submitted for publication have already been going on for a year, so I got tired of this long term, and my subjects and I used the word bud.

Don Tucker’s Unexpected Entry into Olfactory Research

One of the faculty at Florida State worked on thermal control processes in animals and used the opossum as his research animal. He was going to discard one of them and asked if I wanted to use it. I accepted the animal and asked a graduate student to look at the olfactory epithelium in the nose. The graduate student spent several days on the project and each day Don Tucker, an electrical engineer by training who was employed to build and repair our electronic equipment, made negative remarks about the student’s skill. I found Tucker’s remarks distasteful and thought I would teach Tucker a well deserved lesson. I told him to take over the project I had given to the student. Contrary to what I expected, Don did an excellent job and proved to be an outstanding researcher. I terminated his work as a technician and placed him in a research position to study the opossum olfactory tissue.

The sheet of olfactory tissue that Tucker first removed from the opossum was rich in fine olfactory and trigeminal nerve fibers. Odors from cloves, cajeput, eucalyptus, oranges, coffee, etc., excited the recorded single fibers but no two fibers responded in the same way. Were they olfactory or trigeminal responses? The action potential size and type of odor stimulus could not define the nerve source and we had to devise another preparation.

We decided to leave the olfactory tissue intact. (Opossums are plentiful in the Tallahassee vicinity, are easily handled, and have a large area of olfactory epithelium in the snout.) We used small strands of both olfactory and trigeminal nerve bundles for recording. The olfactory system responded sooner and the neural firing was more regular than that of the trigeminal.

We found that autonomic activity greatly affected the magnitudes of olfactory and trigeminal neural activity. Usually, increased sympathetic stimulation resulted in increased olfactory and trigeminal activity, whereas parasympathetic responses were more complex. Because many events can affect these responses, it was interesting to see the olfactory response increase when the experimenter clapped his hands or when he touched the naris with his forceps. The reverse is also true: the response to an odor can affect respiratory and cardiac activities. The results of these chemosensory experiments emphasized how integrated are the body’s functions and demonstrated the importance of requiring the study of mammalian physiology for all of our students.

The possibility of recording olfactory action potentials was questioned, particularly in Europe. The olfactory nerve diameter is about 0.2 µm. When I had difficulty recording from chemosensory nerves of insects when I was a student, I was often told that the message was perhaps transmitted by the spread of small local potentials rather than by action potentials. In addition, it was known that the olfactory epithelium in vertebrates is usually near the olfactory bulb. However, we knew that in many fish the two tissues were separated by a large distance, sometimes more than 10 inches, and that local potentials could not spread over such large distances.

One day I received a phone call from Lord Adrian who was visiting Rockefeller University. He asked if I would come to New York and talk with him and with Professor Herbert Gasser who had studied the anatomical and electrical properties of the olfactory nerve. I was delighted and went to New York to spend an afternoon talking about the olfactory system. I believe they became convinced that one can, indeed, record electrical activity from olfactory nerve strands that contain but one active fiber.

Recording from Human Taste Nerves

As a student I had read about the discovery by Galvani (1737–1798) that the human chorda tympani nerve passes through the middle ear on its travel from the tongue to the higher nervous system. Some time later others demonstrated that if the human ear canal were filled with salt water and electrically stimulated, the subject perceived a taste. Quite accidentally in 1954 I also came across a paper by Dr. Samuel Rosen, an otolaryngologist who showed that he could cure certain deafness (otosclerosis) by mobilizing the footplate of the stapes in the middle ear while the patient was under local anaesthesia. During this operation he often cut the chorda tympani nerve to get a better view of the foot of the stapes. Because much of the chorda tympani nerve is not embedded in tissue as it traverses through the middle ear, I wondered why not try to record the neural activity while the tongue is chemically stimulated? When I returned to Tallahassee I wrote to Dr. Rosen and suggested we try recording from his patients. In August he replied, noting that he would be willing to cooperate. I was excited because the patients might also tell us something about their taste sensation while we record from their taste nerve.

Clarence Hardiman, an FSU graduate student, and I spent several weeks with Dr. Rosen at two different hospitals in New York City trying to record suitable neural activity without success. We realized finally that we had two major obstacles. First, the injection of a local anesthetic often impaired the function of the chorda tympani taste nerve from which we were trying to record the electrical activity. Second, Dr. Rosen, as surgeon, was the only person allowed to manipulate the nerve before recording. Both Clarence and I had much experience with chorda tympani nerve recording, but it was difficult to explain our knowledge to Dr. Rosen without actually touching the patient. We spent about 3 weeks in the operating room without success.

The success of Dr. Rosen’s new method of stapes mobilization spread quickly throughout the world. Two or 3 years after our unsuccessful attempts at taste nerve recording, Professor Yngve Zotterman and Dr. Herman Diamant tried the same experiments in Umeå, Sweden with some success. In 1959, they published beautiful recordings of human neural responses to various tastants. I later visited Umeå where Zotterman and Diamant showed me recordings in the operating rooms. The reasons for their great achievement—the use of general anesthetics and careful handling of the chorda tymani.

Building Our Home

My monthly salary in 1950–1951 was $400. Although the economy was much improved by the end of World War II, my concern for the future remained. In the meantime our family size was increasing. Somehow I had to protect my family from any downturn in the economy. We therefore purchased 10 acres of farm land about 6 minutes from the university and I started to lay a house foundation in January 1955. In Tallahassee, almost every day can be an outside workday, so building progressed well. By May of the same year I had finished the roof. The house was about 35 feet wide by 50 feet long.

When a problem occurred that I did not know how to solve, I visited other houses being constructed to learn the answer. I finished the electricity and plumbing by the end of 1956 and we moved in July 1957. I had not yet finished the inside walls but each month we lived in the house was a month for which I paid no rent. As the family grew to six children (five boys and one girl), we added another room. As my boys grew, their participation in home affairs also increased. To each we assigned daily chores of planting the garden or feeding the chickens, turkeys, cows, pigs, and a horse.

Life Span of Sensory Cells

The library is a good place to broaden ones approach to science. Since the library at Florida State did not have much of the older science literature, I decided in 1959 to use the excellent library at Woods Hole. I obtained a key to the library and the use of a desk for two weeks. Among the articles I read were several on cell life span and cell replacement in epithelial tissue. I also learned that in 1914 M. Heidenhain, the great histologist, thought taste cells may have a short life as do skin cells. Other histologists did not agree because few mitotic figures were found in taste buds when compared with basal cells in the tongue epithelium. However, I often wondered how taste cells can be surrounded by hundreds of different chemicals at various concentrations and not be injured. Perhaps Heidenhain was right, and new methods would prove or disprove the concept. Many students of skin replacement used the mitotic inhibitor, colchicine, to study cell replacement. Our initial studies with colchicine indicated that cells surrounding the taste bud underwent division and that the daughter cells could enter the taste buds. However, a chance engagement with Dr. H. Quastler of the Brookhaven Labs resulted in an offer to visit his laboratories and learn how to study cell turnover more quantitatively with tritiated thymidine.

A graduate student, Ron Smallman, and I accepted his offer to learn quantitative methods for measuring cell turnover and replacement. We then learned, as a result of quantitative techniques, that rat taste cells are indeed replaced and that half of them are replaced within 9–10 days. Because the tagged population declines exponentially, one-quarter of the labeled population is still present after 18–20 days and one-eighth after 36–40 days.

Since all the rat cells that undergo cell division within the period of our taste cell labeling are also labeled, several other tissues were also studied in our laboratory by various students, visiting scientists, and fellow faculty members.

We also labeled other animals, such as fish, that possess electroreceptors. They appeared to be replaced much as taste cells are. Another student, Janet Wise, studied the turnover of the cells at the center of the rat eardrum and their migration to the periphery of the eardrum.

We thought that there were similarities between auditory receptors and taste receptors, but we studied rat auditory receptors without success. When Hallowell Davis visited our lab, he made it known that this was not a very good idea. He said that histologists had never seen mitotic figures in auditory cells. I replied that perhaps the auditory cells were replaced only after auditory damage; however, we had little experience in cutting and preparing bone-embedded tissue, and did not proceed with the project.

We examined many tissues after rats were injected with tritiated thymidine for our taste studies. One of them was the olfactory epithelium that contains many millions of olfactory receptors. Unlike taste cells which have an epithelial origin, olfactory cells are of neural origin. We observed cells in the olfactory epithelium that were radioactive. Closer scrutiny indicated that these may be olfactory receptors.

Pasquali Graziadei, who later joined our Psychobiology group, was a professional neuroanatomist with very broad experience. Our previous experience with the study of auditory cells suggested to me that someone much more familiar with anatomical studies should study the olfactory system. Time determined that this was a wise decision. Furthermore, Dr. Graziadei published a number of excellent papers on the olfactory epithelium as well as on the olfactory bulb. These studies should be of interest not only to those studying sensory systems but also to those interested in spinal cord and brain repair processes.

Expanding the Research Opportunities

One Thursday afternoon in 1958, I received a phone call from someone at the National Institutes of Health (NIH). The caller wanted to know if I would be interested in applying for a training grant to expand my research. I replied no, saying that I already had enough work to do. The caller persisted and asked if he could visit me the following Monday.

After my visitor left, I reconsidered my initial reaction and outlined a plan and budget. The next month a five-man committee came to see me. My tentative budget included salaries for a secretary, histologist, electronic technician, a half-time machinist, and five postdoctoral stipends. One member of the committee, in particular, did not think I needed so much support staff. My reply was that Florida State was just forming a graduate program and that the facilities were not adequate. If I trained postdoctoral fellows, I would need the same facilities as my competitors at the major research universities up north. To my surprise the committee was convinced and NIH funded the grant which later was extended several times until its termination in 1980.

International Symposium on Olfaction and Taste

Graduate students flooded the universities in the 1950s due to the GI bill. By the end of the decade chemical senses were no longer being studied by only a small group of physiologists and psychologists. In 1959, Walter Rosenblith sponsored a symposium on sensory communication at MIT. Carl Pfaffmann asked Yngve Zotterman from Stockholm and me to visit his laboratory at Brown University and meet his students during late afternoon. This we did, and the three of us then talked about taste as we sat around a small table. I said that it would be nice if my students and Carl’s could get together every few years as they had much in common. Yngve thought this would be good and wondered if there was some way that his students could also meet our students. I jokingly replied that my students certainly would like to visit Sweden! Immediately, Yngve said that his position as Secretary of the Wenner-Gren foundation in Stockholm might allow him to invite all of us. Carl and I laughed and did not take Yngve seriously; however, Yngve did organize an excellent meeting in Stockholm and this in 1962 became the first of a series entitled International Symposium on Olfaction and Taste (ISOT), held every 3 years since then.

ISOT was a jewel for many of us. However, all the speakers were invited, and the cost of international travel limited the number of students who could attend. Furthermore, whereas most of our research monies were coming from the medical and industrial communities, we decided that a new society (ACHEMS) should be formed with annual meetings in the United States with adequate attention given to industrial and health needs. The group meets in Sarasota, Florida once a year, but this meeting focuses on basic research with little attention to medical or industrial needs.

Seattle World’s Fair

After the Soviets launched Sputnik to orbit in 1957, President Kennedy and the American military became concerned about the adequacy of science and technology in the United States. Their concern included how science and mathematics were taught in the schools and how well the public was informed about science. An international World’s Fair was soon to be held in Seattle in 1962, and the President’s science advisors (including Detlev Bronk, Harry Harlow, and Paul Weiss) suggested that the U.S. exhibition should center on science and technology. A budget of about $10 million was allocated to the Department of Commerce for this purpose. Five modern buildings were designed and constructed. Professional science writers were contracted to develop scripts that could be used by industrial designers for posterboard exhibits on various science themes. It soon became apparent that a professional scientist was needed to oversee the design process, develop new exhibits that used material other than posterboards, expand the exhibits on biology and animal behavior, and coordinate the many small but important interfaces with the scientific community. For these objectives, Athelstan Spilhaus, Dean of Technology at the University of Minnesota, was appointed Commissioner. Spilhaus was a trained oceanographer, a writer of popular books on science, and author of a syndicated comic strip on science. I was appointed Science Coordinator of the U.S. Science Exhibits in Spring 1961.

After working in Washington, DC for several months, it became apparent that I needed to be in closer daily contact with the exhibit designers. I moved my office to Madison Avenue in New York to one of the offices of the industrial design firm, Teague Associates. I felt strongly that the exhibits must contain more than posterboards. We designed a real laboratory and made it ready for operation, so that the public would get a better idea of what science was all about. It contained much of the equipment found in a typical university laboratory. In addition, each morning one of the demonstrators would dissect the optic nerve of Limulus (horseshoe crab), and record the electrical neural activity in response to light stimulation, and display it on a large overhead oscilloscope and play it on an audio amplifier. The demonstration was impressive and the audience asked questions about both the animal itself and the electrical activity within their own bodies.

My previous experience with animal behaviorists also became very useful in planning the exhibits. For example, I had read an article by B. F. Skinner at Harvard University about pigeons playing ping pong. I thought that experiment could be a center attraction for our exhibits on animal behavior. I phoned Professor Skinner but he informed me that such an exhibit would be too difficult to put together. He suggested that I visit one of his former students, Dr. Donald Blough at Brown University and our visit culminated in the best exhibit of the Fair! We had a continuous show of working pigeons displaying color discrimination. Similar personal contacts with Professor Eckard Hess at the University of Chicago, Professor Harry Harlow at the University of Wisconsin, Professor Paul Fields at the University of Washington, and many others resulted in an excellent series of animal exhibits.

It soon became obvious that we needed someone to be available to the public to answer questions about the exhibits. I suggested that we employ 40 college women. We had more than 120 applicants, and I interviewed each one. Most had no college science courses, and we therefore had to employ someone as a trainer and an overall coordinator. I needed someone I knew and could trust to get the job done and who would interact well with the young students. We employed Ron Smallman, a former graduate student of mine, who did an excellent job.

My family and I moved to Seattle in Fall 1961, although I kept my office in New York for several months more and visited Seattle every weekend. The fair opened officially in Spring 1962. Because Dr. Spilhaus had many other commitments, I was assigned the additional task of being on hand when honored dignitaries arrived or when television appearances were needed. As a result, I met many interesting visitors such as Jonas Salk, Walter Cronkite, and the Shah of Iran and his wife, and appeared on many TV programs, including a 15-minute talk about cell turnover on a morning show. The latter produced an embarrassing incident when the host asked what the relation was between cell turnover and reincarnation!

We returned home to Tallahassee in Fall 1962. When I first visited Florida State for an interview, the dean had made it very clear to me that each faculty member had three duties, namely, teaching, research, and service. I now felt that I had amply fulfilled my service commitment and needed to concentrate on my graduate students whom I had left behind. While working on the exhibits I visited my laboratory only four days a month but several postdoctoral fellows, including David Moulton, had been available to help the graduate students. I also needed time at a good library.

Formalizing Our Psychobiology Program

In 1964 the National Science Foundation initiated its Centers of Excellence throughout the nation. The Florida State University vice president appointed a seven-member committee, including Dan Kenshalo and me to represent psychobiology. The committee concluded that Dan and I should present a budget of about one million dollars. The psychobiology budget included many technical positions and 14 new faculty to be shared by the departments of psychology and biological sciences. The State of Florida was obligated to keep the faculty intact after the grant period expired five years later. The Center was awarded, the State of Florida kept its word, and as this chapter is being written the number of faculty and staff positions remains the same as it was after the grant was awarded.

Nature’s Taste Modifiers

Can one modify a taste? Can one change a sour taste to a sweet taste? Can a sweet taste be completely inhibited? Can bitterness be completely suppressed? The highest authority says yes. According to the Bible:

When they came to Marah, they could not drink the water of Marah because it was bitter; therefore it was named Marah. And the people murmured against Moses, saying, “What shall we drink?” And he cried to the Lord; and the Lord showed him a tree, and he threw it into the water, and the water became sweet. (Exodus 15:22)

In 1964 I decided to search for possible taste modifiers. I learned about a red fruit about the size of an olive that grew in West Africa. It was supposed to produce sweetness when eaten before eating sour food. I located some specimens, called miracle fruit, in a nursery in south Florida. I purchased several small plants and planted them in the greenhouse at Florida State. When I had about two dozen mature plants with berries, I tasted them. They were excellent in taste and when eaten before sour lemons, the lemons then tasted very sweet. The sweet taste was natural in character, unlike that of saccharin.

Upon producing a good crop after three years of propagation, I decided to determine the chemical nature of miracle fruit. I followed the usual procedures of organic chemistry by trying to extract the active principle with chloroform, acetone, benzene, and other reagents, but without success. Either it did not have the properties of an organic substance, or else we were degrading it. After many months of extractions, I wondered if there was something in saliva that was important that I was overlooking. We tried extraction with saliva and we were successful! We made an artificial saliva without the organic constituents and hit the jackpot! We knew how to extract the ingredient with only inorganic substances.

In 1967 Dr. Kenzo Kurihara, a protein chemist, joined our laboratory and I turned the problem over to him. This was serendipity because the active ingredient in the berry was a protein! No one expected this because all known tastants at that time were small molecules. When Kenzo determined the molecular weight to be about 44,000, I felt uncomfortable and hesitated to consider publishing the results. After more experiments he convinced me that the ingredient was indeed a protein and we sent a paper to Science. We waited for almost 5 months before it was published in 1968. In recent years Dr. Yoshie Kurihara in Japan has determined the amino acid composition and sequence, but we still do not have a complete understanding of how this protein stimulates the taste cell to modify its response.

Protein Synthesis and Transport in Olfactory Nerve

As a student at Hopkins I had learned of the possibility that the polio virus could travel from the nose to the brain by using the olfactory pathway. I also knew that taste buds disappear if the nerve connection is cut and that taste buds regenerate when the taste nerve again innervates the buds. Thus, I was interested in chemical transport by the nerve axons. Paul Weiss told me that he used the frog olfactory nerve to study axonal flow. This nerve has a large and homogeneous population of C fibers. In 1970 my colleague at Florida State, Dr. Dexter Easton, informed me that the garfish, which is plentiful near Tallahassee, has an accessible olfactory nerve bundle more than 10 inches long. Furthermore, the bundle contains a homogeneous population of millions of small C fibers. This encouraged me to use a row boat at a local lake and fish for gar at least 3 feet in length.

I used this preparation to study colchicine blocks of the olfactory nerve. Guenter Gross, then a new graduate student trained in engineering, became interested in this preparation for a dissertation. He did a series of excellent studies of axonal flow in C fibers and determined a velocity of 222 mm/day in olfactory fibers with a 0.244-mm diameter. These highly quantitative methods are excellent for the study of transport of proteins with radioactive labels. The labeled amino acid is placed into the nostril where the olfactory epithelium is both visible and easily accessible. Dr. Cancalon, a postdoct in my laboratory, studied the various subcellular fractions of molecules that are synthesized in the olfactory nerve cell bodies and rapidly transported in the olfactory nerve as well as those slowly transported.

Because there is a direct route from the nose to the brain, one wonders whether other substances placed into the nose, such as medicines or pollutants, can enter the olfactory nerve bundle and also pass directly to the brain.

Gustatory Nerve Synthesis and Transport

I decided to use axoplasmic flow to determine what fraction of the cells of the taste bud are innervated. The nodose ganglia of the rat which contain the cell bodies of the nerves that innervate the taste buds of the epiglottis, were injected with labeled amino acids. If the nerve innervates a taste cell, I thought, labeled molecules may pass from the nerve ending into the innervated cell. Six hours after nodose injection of labeled amino acids, cells of the taste buds were heavily labeled. Thus, there appeared to be an axonal route for molecules that are synthesized and labeled in the axon’s cell body to cells of the taste bud. (These experiments also demonstrated a method whereby the neural pathways can be labeled.)

Determinants of Taste Cell Characteristics

One of the most important questions in the area of chemoreception is, what determines the response characteristics of taste cells? Is it the nerve that innervates them or properties at the location of the taste buds? We know in humans that we taste sweet things better in the front of the tongue and bitter tastes are more pronounced in the back. However, not all animals exhibit this same taste pattern. Irving Fishman showed that the taste buds on the front of the tongue of the fox are sensitive to bitter substances, and this finding was recently verified in my laboratory.

In 1987, Mohssen Nejad, a postdoc in my laboratory, cross-regenerated the greater superficial petrosal nerve of the rat, which normally innervates the palatal taste buds, with the chorda tympani nerve, which normally innervates the anterior two-thirds of the tongue. The taste response characteristics followed the area in which the taste buds were located—not the innervating nerve. These findings were similar to those of Dr. Bruce Oakley’s laboratory. The effects of bilateral sectioning of both of these nerves on the sweet taste in the rat were studied by Krimm and others in 1987.

Looking Back

Many years ago I was having dinner with a group of food industralists in England. During our conversation the elderly man next to me asked what was my profession. I replied that I was a professor. He said he was president of one of the largest food companies in England and would trade his job for mine any day. He was so busy he had no time to travel, to visit other people, or to interact with the youth of the day! I traveled all over the world and interacted with many different kinds of people without any cost to me. Usually my wife traveled with me and we took the children with us when they were young. Later, only one or two of them accompanied me: Steve and Allan to Japan; David to Iran, Turkey, England, and Spain; John to the mountains of Venezuela to hunt special sweet plants; Dianne to Russia.

I remember the comment of Vernon Mountcastle a number of years ago. He said, “Lloyd, we were born at the right time. We started our research careers when research money was becoming plentiful. As research money becomes scarce, we look forward to retirement.” The change that affects me most, however, is not only money but the fact that now there is less freedom to get up in the morning with an interesting research idea and go into the lab and pursue it without first getting approvals from everyone concerned followed by making a report to someone in Washington who files it where it forever remains, unread. However, the race was worth running.

Selected Bibliography

Bargoot F, Williams TP, Beidler, LM. The localization of radioactive amino acid taken up into the outer segments of frog (rana pipiens) rods. Vision Res 1969;9: 352–369.

Beidler LM. Properties of chemoreceptors of tongue of rat. J Neurophysiol 1953;16: 595–607.

Beidler LM. A theory of taste stimulation. J Gen Physiol 1954;38:113–139.

Beidler LM, Tucker D. Response of nasal epithelium to odor stimulation. Science 1955;122:76.

Beidler LM, Fishman IY, Hardiman C. Species differences in taste responses. Am J Physiol 1955;181:235–239.

Beidler LM, Tateda H. Taste receptor potentials of the taste cell of the rat. J Gen Physiol 1964;47:479–486.

Beidler LM, Smallman R. Renewal of cells within taste buds. J Cell Biol 1965;27: 263–272.

Beidler LM. Comparison of gustatory receptors, olfactory receptors and free nerve endings. Cold Spring Harbor Symp Quant Biol 1965;30:191–200.

Beidler LM, Moulton DG. Structure and function in the peripheral olfactory system. Physiol Rev 1967;47:1–25.

Beidler LM, Kurihara K. Taste-modifying protein from miracle fruit. Science 1968; 161:1241–1243.

Beidler LM. Cell recognition and neural coding of taste. Proc Int Union Physiol. Sci 1971;8:21–22.

Beidler LM. The use of the scanning electron microscope for biological material. In: Proceedings of the Engis Stereoscan Colloqium, Vol. II. Morton Grove: Engis Equipt Corp., 1969;109–122.

Cancalon P, Beidler LM. Distribution along the axon and into various subcellular fractions of molecules labeled with 3H leucine and rapidly transported in the garfish olfactory nerve. Brain Res 1975;89:225–244.

Cancalon P, Elam JS, Beidler LM. SDS gel electrophoresis of rapidly transported proteins in garfish olfactory nerve. J Neurochem 1976;27:687–693.

Cancalon P, Beidler LM. Differences in the composition of the polypeptides deposited in the axon and nerve terminals by fast axonal transport in the garfish nerve. Brain Res 1977;121:215–227.

Gross G, Beidler LM. Fast axoplasmic transport in C-fibers of the garfish olfactory nerve. J Neurobiol 1973;4:413–428.

Gross G, Beidler LM. A quantitative analysis of isotope concentration profiles and rapid transport velocities in the C-fibers of the garfish olfactory nerve. J Neurobiol 1975;6:213–232.

Kimura K, Beidler LM. Microelectrode study of taste receptors of the rat. Am J Physiol 1956;187:610.

Krimm R, Nejad MS, Smith JC, Miller IJ, Beidler LM. The effect of bilateral sectioning of the chorda tympani and the greater superficial petrosal nerves on the sweet taste in the rat. Physiol Behau 1987;41:495–501.

Kurihara K, Beidler LM. Mechanism of the action of taste-modifying protein. Nature 1969;22:1176–1179.

Kurihara K, Kurihara Y, Beidler LM. Isolation and mechanism of taste modifiers: Taste modifying protein and gymnemic acids. In: Pfaffman C, ed. Olfaction and taste. New York: Pergamon Press, 1969;450–469.

Nejad M, Beidler LM. Taste responses of the cross-regenerated greater superficial petrosal and chorda tympani nerves of the rat. Ann NY Acad Sci 1987;510: 523–526.

Rosen S. Simple method for restoring hearing in otosclerosis mobilization of stapes. Acta Oto-Laryngologica 1954;44:78–88.

Sato T, Beidler LM. Relation between receptor potential and resistance change in the frog taste cells. Brain Res 1973;53:455–457.

Sato T, Beidler LM. Membrane resistance change of the frog taste cells in response to water and NaCl J Gen Physiol 1975;66:735–763.

Shingai T, Beidler LM. Response characteristics of three taste nerves in mice. Brain Res 1985;335:245–249.

Shingai T, Beidler LM. Interstrain differences in bitter taste responses in mice. Chem Senses 1985;10:51–55.

Arvid Carlsson

BORN:

Uppsala, Sweden

January 25, 1923

EDUCATION:

University of Lund, M.D. (1951)

University of Lund, Ph.D. (1951)

APPOINTMENTS:

University of Gothenburg (1951)

Professor Emeritus, University of Gothenburg (1989)

HONORS AND AWARDS:

Royal Swedish Academy of Science (1975)

Wolf Prize in Medicine, Israel (1979)

Japan Prize (1994)

Foreign Associate, Institute of Medicine, National Academy of Sciences, U.S.A.

Arvid Carlsson made fundamental discoveries about the role of biogenic amines as neurotransmitters in the brain. He and his colleagues presented the first convincing evidence for dopamine as a central neurotransmitter and suggested that it plays an important role in the reward system. He also discovered dopamine autoreceptors and selective serotonin reuptake inhibitors, and he clarified the action of certain antipsychotic drugs in terms of their action on central biogenic armine systems.

Arvid Carlsson

I was born in Uppala, Sweden, on January 25, 1923. I grew up in an academic, middle-class family. When I was 3 years old, my father was appointed professor of history at the University of Lund, and moved my family there, from Uppsala. My father had earned his Ph.D. at the University of Uppsala and my mother had passed the master-of-arts examination. My mother kept a keen interest in research throughout her life but gave priority to raising her children and to assisting her husband in his research. However, when my father died at the age of 76 she, then 71 years old, devoted herself entirely to her favorite area of research, the legal status of Swedish women in the Middle Ages. She published a couple of books and a number of articles on this subject in Swedish, which earned her an honorary Ph.D. degree at the University of Uppsala, several years later.

We were four children in the family, and we all took academic degrees at different levels. We had a strong orientation toward the humanities. My elder brother and sister chose to study the humanities, but I chose medicine, as did my younger brother, who was 7 years younger than I. The reason for my deviating behavior was partly youthful opposition, partly some vague idea of science being more “useful” than the arts.

My childhood and youth were happy. I grew up in a stable environment with loving and supportive parents. I was probably average in my disobedience and escapades. School was endurable; I made very good marks without too much effort.

At age 16, in June 1939, I took a hitch-hiking trip to Germany for 2 weeks with a boy of the same age. This was to be my only trip outside the Nordic countries until I was 32. It occurred only two and a half months before the outbreak of World War II. We had the opportunity to talk to many Germans of varying social standing; most of them felt convinced that a war would begin as soon as the harvest was done, and they seemed to accept it, albeit reluctantly. In Berlin, I spent one night in a hostel which was run by an evangelic foundation and inhabitated by very poor people. I especially remember several Jews with long beards and sad faces, mumbling while they read a heavy book that could have been the Talmud, apparently searching for an answer and a solution in a desperate situation. Otherwise, I was not aware of the terrible actions against Jews that were probably going on around me.

My medical studies started in 1941 and went smoothly, apart from several interruptions for a couple of years of military service. Lund was, and still is, a small university town, somewhat reminiscent of Oxford. The quality of research and teaching, including that of the medical school, was good. Among the professors of the school are a couple of prominent names: Torsten Thunberg, professor of physiology, who had discovered “tissue respiration;” the dehydrogenases, and had developed a method to measure their activity. His work was simultaneous but independent of Warburg’s research on the same subject, in Berlin. Warburg, but not Thunberg, was awarded the Nobel prize. Ernest Overton, professor of pharmacology, was famous for his revolutionary theories on the structure and lipid properties of the cell membrane and on the mechanism underlying narcosis. Overton had died before I started my medical studies, and Thunberg was already emeritus by then. Sadly, Overton became mentally ill in his later life; he was said to propose himself repeatedly for the Nobel prize, which he, like Thunberg, certainly deserved, but did not get. Among the most innovative of my contemporaries at the medical school was Nils Alwall, although his seminal contributions had not been generally recognized at that time. Alwall is one of the pioneers in the development of the artificial kidney. He successfully ran a department of kidney dialysis in the medical university’s clinic. The internationally renowned Gambro Company was founded on the basis of this work. It is still quite successful in kidney dialysis and other biomedical technology. Another major innovation from the university was ultrasonar cardiography, which was developed by Helmuth Hertz and Inge Edler. Jörgen Lehmann was one of the most prominent among Thunberg’s students. In the 1940s, in Göteborg, he discovered paraaminosalicylic acid (PAS) which, together with streptomycin, discovered by Selman Waksman, provided the first effective drug treatment for tuberculosis. Waksman, but not Lehmann, was awarded the Nobel prize for his discovery.

During the first 5 years of my medical studies, World War II was going on, rendering Sweden almost entirely isolated. During my first year, however, five Danish medical students were allowed to leave Denmark, which was then occupied by Germany, to do their anatomy studies with us, in Lund. I became especially friendly with one of them: Ib Munkvad. Among other things, we played chess together. Munkvad later became a psychiatrist with an orientation to biological psychiatry. He was instrumental in developing biological psychiatry in Denmark and is also known for formulating the hypothesis that the dyskinesias induced by dopaminergic agonists could make a model of psychosis.

Another remarkable contact with the war occurred during a few nights in October 1943, when thousands of Jews managed to escape in small fishing boats across the sound between Denmark and Sweden. This happened when one of the top members of the German occupation informed Danish authorities that a major deportation of Jews from Denmark to Germany was forthcoming. Among the Jews who came to Sweden were a number of prominent medical researchers. They were immediately enrolled in our medical school and became important teachers and researchers.

An even sadder contact with the war occurred in the spring of 1944, when I was in my first year of clinical training. Count Folke Bernadotte, a member of the Swedish royal family, had managed to persuade German authorities to allow him to enter Germany with white buses and to pick up prisoners at concentration camps. Through Bernadotte’s efforts, 30,000 prisoners, among them 11,000 Jews, escaped. Some of the prisoners were taken to Lund, where a big tent was erected in a park to house them. I was given the task of examining several of the prisoners. Many were children who suffered from malnutrition. Tuberculosis was not uncommon. However, most shocking was their mental status. They behaved like wild animals, obviously suffering from severe anguish and suspicion and they trusted nobody.

Starting in Pharmacology

At the outset of my medical studies I had decided to become a researcher, and in 1944, I was offered a modest position as amanuens (initially without salary), in the University of Lund’s department of pharmacology, after I had passed a successful examination in that discipline. The head of that department, and at that time the only professor, was Gunnar Ahlgren. He had been Thunberg’s favorite student and apparently had been an asset in the group around Thunberg. However, when he was on his own, he was not scientifically productive, but he managed to attract a number of talented students, who were to make successful careers in various medical disciplines. One of these people was Nils Alwall.

Ahlgren gave me and another student, Georg Theander, a topic to investigate: measuring the duration of action of pentylenetetrazol (Cardiazol), a convulsant that was then used frequently as an analeptic to wake up people who had taken an overdose of a hypnotic or sedative, and which was also used as a forerunner of electroconvulsive therapy. Nowadays this drug has a modest use as a diagnostic and experimental tool. To measure the action of pentylenetetrazol, Ahlgren proposed employing its awakening action against central depressants. At first we tried nitrous oxide, but to our surprise the drug was unable to antagonize its anesthetic action. We then added a subhypnotic dose of barbital and found that the combined action of barbital and nitrous axide could be antagonized, and the increase in partial pressure of nitrous oxide that was needed to inhibit the righting reflex could be used as a measure of pentylenetetrazol action. The result of this study was that the duration of action of pentyleneterazol was much longer than expected from observations on its effect in animals that were not treated with central depressants. We published our results (Carlsson and Theander, 1946), and this first publication of ours was awarded a modest prize, intended for young medical scientists at the University of Lund. One might wonder why Ahlgren was interested in the duration of action of this drug. He never explained that to me, but when I told him about our results, he was obviously pleased, but not surprised. A plausible reason for this was that he had actually tried it on himself to antagonize a sedative and thus discovered its long duration of action.

Together with another pharmacologist, Folke Serin, I studied the action of another analeptic, nikethamide, and discovered a circadian rhythm in its lethal action. The publication of these findings (Carlsson and Serin, 1950) appears to have been the first to describe a circadian rhythm of a drug’s action, according to a review article on chronobiology, which was published much later when this subject became fashionable in connection with space research.

Work on Calcium Metabolism

In 1948, Gunnar Ahlgren persuaded me to go into an entirely different area of research, calcium metabolism. At that time, radioactive tracers, among them ⁴⁵Ca, had become commercially available, and a Swedish drug company wanted us to test a number of calcium salts for their oral availability. I agreed to do this research. The testing of different calcium salts did not disclose anything of interest, but I used this opportunity to investigate the absorption of calcium as well as its metabolism in the skeleton by means of the new technique. That work resulted in my M.D. thesis (corresponding to the American Ph.D.) and in several subsequent papers, including the doctoral theses of two students of mine, Bertil Lindquist and Göran Bauer, who later became professors of pediatrics and orthopedic surgery, respectively. Briefly, what we found was that it is possible, contrary to the opinion at that time, to use tracer techniques to differentially measure the uptake (or “accretion”) and the resorption of the bone mineral (for a review, see Bauer et al., 1961). Among other things, we discovered that vitamin D in physiological doses can stimulate not only the intestinal absorption and “accretion” but also the resorption of bone minerals. Our findings aroused some international interest and resulted in an invitation to a Gordon Conference in the summer of 1955.

Getting into Neuropsychopharmacology: Sabbatical in Bernard B. Brodie’s Lab

In 1952, when I had an appointment as assistant professor and had applied for an associate professorship in the department of pharmacology, the expert committee instead appointed my competitor, Folke Serin, who later became a prominent specialist and academic teacher in internal medicine and still remains one of my oldest friends. At the same time, the committee let me know that, in their opinion, my present research field, calcium metabolism, did not occupy a central position in pharmacology. I now felt that I had to make a choice, to either leave pharmacology and go into internal medicine (I had completed my medical education in 1951) or switch into a new research field. I decided to apply for a position as physician in the department of internal medicine of the university hospital. I worked for the whole of 1954 in that department. I found the clinical work interesting and I learned a lot during that year which, I believe, was useful in my subsequent career. However, I still found basic research too attractive to abandon. I thus contacted the professor of medical chemistry, Sune Bergström, who had proven to be helpful on previous occasions when I needed advice and support, and asked him if he could explore the possibility of my working in an American laboratory, studying chemical pharmacology. Bergström kindly wrote to one of his many friends in the United States, Bernard Witkop, a prominent organic chemist who worked at the National Institutes of Health. Witkop forwarded the letter to Sidney Udenfriend, who in turn forwarded it to his chief, Bernard Brodie. Brodie replied that I was welcome to work in his laboratory, the Laboratory of Chemical Pharmacology at the National Heart Institute, as a visiting scientist.

In late August 1955, after attending the Gordon Conference on Mineral Metabolism, I began work in Dr. Brodie’s laboratory. The first day I had lunch in the cafeteria of Building 10 with Drs. Brodie and Udenfriend. I got the impression that Brodie had not yet made up his mind whether he would take me on or let me work with Dr. Udenfriend. He told me that he wanted me to work with him and Parkhurst A. Shore on the action of reserpine on the storage of serotonin in blood platelets in vitro. I started immediately on this project. Adequate equipment had already been acquired.

The following month I was frustrated because the results were entirely negative. Moreover, I was shocked to find that in this new environment, my competence as a scientist was by no means taken for granted. This was of course understandable but still shocking in view of the way I had been treated in my home laboratory. After a month of completely negative results the in vitro system suddenly started to work beautifully. The reason for this dramatic change was never fully clarified, but it coincided with the introduction of a new batch of reserpine. Thus, we could demonstrate a clear-cut and specific blockade by very low concentrations of reserpine on the storage of serotonin in platelets. This was the first demonstration of a direct action of reserpine on the storage of serotonin (Carlsson et al., 1957a).

I can hardly overemphasize how lucky I was to get that opportunity to work in Dr. Brodie’s laboratory during a very dramatic period, when drug research was undergoing a revolution and psychopharmacology was in statu nascendi. This was only 3 years after the discovery of the antipsychotic action of chlorpromazine and 1 or 2 years after the rediscovery of the antipsychotic action of reserpine (reported by psychiatrists in India, three decades earlier). At this point I was introduced by Drs. Brodie and Shore to the most modern methods of biochemical pharmacology as well as to the hottest area of psychopharmacology at that time.

What kind of person was Bernard B. Brodie, the man who has played the most important role in my scientific career? It is difficult to answer this question in a few words. He was obviously richly gifted and had a lot of charisma. His background was in organic chemistry, but he had specialized in drug metabolism, which he had pioneered by developing a multitude of methods for measuring the levels of drugs and their metabolites in tissues and body fluids. At the time of my visit, the prototype of a new instrument, a spectrophotofluorimeter, had been constructed in Brodie’s laboratory by Robert Bowman in collaboration with Udenfriend. This instrument was to revolutionize the measurement not only of drugs but also of several endogenous compounds of great physiological interest. It combined high sensitivity with specificity. For several decades this instrument played a dominant role in biochemical pharmacology. It has now been surpassed by even more powerful equipment.

Brodie had remarkable intuition. When he sensed that a research area was “hot” he did not hesitate to go into it, even if his knowledge of the area was limited. Thus, when he learned about the antipsychotic actions of chlorpromazine and reserpine and the finding that lysergic acid diethylamide (LSD) seemed to possess affinity for 5-hydroxytryptamine (5HT) receptors, he started to do experiments with these drugs in order to find out more about their relation to serotonin. Although some of these experiments were primitive and inconclusive, they culminated in experiments in which reserpine was found to have a dramatic effect on the storage of serotonin in tissues. This seminal discovery was made only a few months before I joined Brodie’s group.

Back to Sweden: Work on Reserpine, Dopa, and Dopamine

After spending 5 fruitful months in Brodie’s lab I returned to Lund, having been recently appointed as associate professor of pharmacology. Before my return I had contacted Nils-Åke Hillarp, who was working as associate professor of histology at the University of Lund. Hillarp was an ingenious scientist. At that time he had already made a number of remarkable contributions to neuroscience as well as to endocrinology. Hillarp and I worked together until his untimely death in 1965. In the mid-1950s Hillarp’s interest focused on the adrenal medulla, where he had discovered that cell organelles store the adrenal medullary hormones and discovered the role of adenasine triphosphate (ATP) as a counter-ion in the storage complex. With Hillarp I discovered that reserpine caused depletion of the adrenal medullary hormones (Carlsson and Hillarp, 1956), and soon afterward I discovered, together with my students Åke Bertler and Evald Rosengren, that similar depletion took place in other tissues, including brain (Bertler et al., 1956; Carlsson et al., 1957b). These findings offered a possible explanation of the hypotensive action of reserpine. This was confirmed by experiments where stimulation of sympathetic nerves no longer caused release of the neurotransmitter noradrenaline following reserpine treatment (for a review and references, see Carlsson, 1987).

These discoveries excited us, but at the same time, they placed me in an awkward position with my highly esteemed mentors, Drs. Brodie and Shore. Our results challenged their interpretations in two respects. First, our data indicated that the action of reserpine should not necessarily be interpreted as due solely to its effect on serotonin; second, our results argued against their proposal that continuous release of the putative neurotransmitter serotonin onto its receptors is responsible for the action of the drug. Rather, our results suggested that at least the hypotensive action was due to an effect on catecholamines and that this effect was caused by depletion rather than release. Unfortunately, this divergence of opinion was to place my mentors and me in different camps for many years to come and led to a many sometimes intense debates, in writing as well as at various meetings. This was especially unfortunate, because despite these divergences, we were on much more common ground than a great number of other workers in this field.

To resolve the issue of the mode of action of reserpine my colleagues and I administered 3,4-dihydroxyphenylalanine (dopa) to reserpine-treated rabbits and mice and discovered the central stimulant action of this amino acid as well as its ability to reverse the akinetic and sedative action of reserpine. Because the serotonin precursor 5-hydroxytryptophan was not capable of reversing the action of reserpine we suggested that depletion of catecholamines, rather than serotonin, was responsible for some important behavioral effects of reserpine (Carlsson et al., 1957c). However, when we analyzed the brains of the animals treated with reserpine and dopa, we found them still fully depleted of noradrenaline. Further analysis revealed that the behavioral action of dopa was closely correlated to the accumulation of dopamine in the brain. Moreover, our studies disclosed that dopamine is a normal brain constituent and is released by reserpine, as are noradrenaline and serotonin. The data suggested to us that dopamine is not just a precursor to noradrenaline, as was generally believed at that time, but is an endogenous agonist in its own right (Carlsson et al., 1958). This received further support when Bertler and Rosengren (1959) shortly afterward discovered the marked difference in regional distribution between dopamine and noradrenaline, the former being largely accumulated in the basal ganglia. We could thus suggest that the Parkinsonism induced by reserpine is due to dopamine depletion, which can be restored by L-dopa, and that dopamine is involved in the control of extrapyramidal motor functions. This was further supported by the finding that the motor disturbances in Huntington’s chorea can be alleviated by reserpine and similar drugs (Carlsson, 1959).

Encountering Disbelief from the British Pioneers

Thus, for the first time, evidence was forthcoming for a role for endogenous agonists, present in brain tissue, in animal behavior. At first serotonin had come into focus, but the subsequent experiments pointed to a role for the catecholamines, and especially dopamine, for the sedative and akinetic actions of reserpine, and the reversal of these actions by L-dopa. We were excited by these findings but were disappointed to meet with considerable resistance to our views by some prominent investigators, especially at a Ciba Symposium on adrenergic mechanisms, held in London in the spring of 1960 (Vane et al., 1960), which was a rather strange experience. At this meeting practically all prominent workers and pioneers in the catecholamine field were present. It was much dominated by the strong group of British pharmacologists, headed by Sir Henry Dale. I was impressed to see how the British pharmacologists, as well as many other former Dale associates, behaved toward Sir Henry, like school children to their teacher, although some of them had indeed reached a mature age. It was also remarkable to find how little disagreement there was among these people, who behaved more or less like a football team. At this meeting I reported on some of our data indicating a role for the catecholamines in motor function and alertness. No doubts were expressed about our observations as such. In fact, Drs. Blaschko and Chrusciel presented observations that confirmed our findings on some essential points.

I have reread the discussions recorded in the Symposium volume, and I am still puzzled by them. To start with, in Sir John Gaddum’s summary of the session on central adrenergic mechanisms, he concluded: “The meeting was in a critical mood, and no-one ventured to speculate on the relation between catecholamines and the function of the brain” (Vane et al., 1960, p. 584). My paper, which was titled “On the biochemistry and possible functions of dopamine and noradrenaline in brain,” as well as a considerable number of remarks that I made during the discussion sessions, dealt precisely with this issue. Obviously, in Gaddum’s mind, I was nobody! Why did he and the other British pharmacologists so completely ignore the evidence that we presented? At first there was some concern about L-dopa being a “poison.” This appeared to be based mainly on the observation by WeilMalherbe that large doses of L-dopa, given together with a monoamine oxidase inhibitor, could be lethal. This discussion ended with a concluding remark by Sir Henry Dale (page 551) that L-dopa is, in fact, a poison, which he found remarkable for an amino acid. Then Paton referred to unpublished data by Edith Bülbring, suggesting the presence of catecholamines in glia rather than in nerve cells. Responding to a question by Dale, Marthe Vogt concluded (p. 551) that there was absolutely no evidence that the catecholamines in the brain act as synaptic transmitters or serve a general hormonal function. Proposals by me and others that this may be the case were said to depend on the particular pharmacological agents used. A critical survey of all the available evidence led, according to Marthe Vogt, to the conclusion that anyof the theories on a relation between catecholamines or serotonin and behavior is “a construction which some day will be amended” (p. 579).

In order to understand the reluctance of some of the most prominent pioneers in chemical transmission to accept that monoamines have a role in brain function it may help to recall that at that time, brain research was dominated by electrophysiology. A vivid debate had been ongoing between Dale and J. C. Eccles about the role of electrical versus chemical transmission in general, and it is possible that Dale had been impressed by the arguments in favor of electrical transmission, at least concerning the brain. From a classical neurophysiological point of view it must have seemed hard to accept, for example, that a loss of nerve function could be alleviated by administering a chemical such as dopamine (given as its precursor, L-dopa). With such a perspective, the alternative interpretation that L-dopa effects were caused by some strange kind of amino acid toxicity may seem less far-fetched.

Visualizing the Monoamines in the Fluorescence Microscope

In any event, this meeting taught me that a scientist’s life can sometimes be tough. I suppose that this experience gave me some immunity to criticism and resistance, which I, and presumably most other scientists, have often met with in our professional lives. At this meeting, Hillarp and I decided to further increase our efforts to convince people of our ideas. I had just been appointed professor and chairman of the department of pharmacology at the University of Göteborg. We agreed that Hillarp should join me to work on catecholamines in the new department, provided that he could be freed from his associate professorship in histology in Lund. We applied for the necessary funds from the Swedish Medical Research Council, and our grant was approved. We decided to focus on two problems: to investigate a possible active amine-uptake mechanism by the adrenal medullary granules and its inhibition by reserpine, and to try to develop a histochemical fluorescence method to visualize the catecholamines in tissues. Both projects turned out to be successful. Because detailed accounts of this work have been given elsewhere (Carlsson, 1987; Dahlström and Carlsson, 1986; Carlsson et al., 1962a, 1964; Andén et al., 1964b), they will not be repeated here. Both discoveries had a considerable impact on the scientific community’s acceptance of the concept of chemical transmission in the central nervous system (CNS) and on the development of monoaminergic synaptology.

A Paradigm Shift: Chemical Transmission in the Brain and Emerging Synaptology

During the early part of the 1960s, a large number of observations were made in Sweden by Hillarp, me, and our respective collaborators, based on the combination of histochemical, biochemical, and functional studies, and by using a number of pharmacological tools. These observations doubtless contributed greatly to convincing the scientific community of the role of biogenic amines as neurotransmitters and, in more general terms, on chemical transmission as an important physiological principle in the brain. That we can speak of a true paradigm shift during the early 1960s is evident from a comparison between the proceedings of the Ciba meeting on adrenogic mechanisms in London, and an international symposium held in Stockholm, in February 1965, titled “Mechanisms of Release of Biogenic Amines” (von Euler et al., 1966). In his introductory remarks to this symposium, Uvnäs stated that, “these amines play an important role as chemical mediators in the peripheral and central system.” None of the distinguished participants in this symposium expressed any doubts on this point.

While the skepticism about the role of chemical transmission in the brain had thus faded, it was followed by an intense debate on the function of various synaptic structures and mechanisms. A major issue dealt with the role of synaptic vesicles in the transmission mechanism. In the mid-1960s opinions still differed on the subcellular distribution of the monoaminergic transmitters. In the fluorescence microscope the accumulation of monoamines in the so-called varicosities of nerve terminals was obvious. This corresponded to the distribution of synaptic vesicles, as observed with the electron microscope. In fact, Hökfelt in 1968 was able to demonstrate the localization of central as well as peripheral monoamines to synaptic vesicles using the electron microscope. However, there was controversy about the nature and size of the extravesicular (or extragranular) neurotransmitter pool. This is evident from the recorded discussions from the Stockholm symposium on biogenic amines. For example, on p. 471, Drs. Julius Axelrod and Ulf von Euler maintained that a considerable part of the transmitter was located outside the granules, mainly in a bound form. This fraction was proposed to be more important than the granular fraction, because it was believed to be more readily available for release. Indeed, the granules were facetiously referred to as garbage cans. Our group had arrived at a different model of the synapse, based on combined biochemical, histochemical, and pharmacological data (Carlsson, 1966). We were convinced that the granules were essential in transmission, and that the transmitter had to be taken up by them in order to become available for release by the nerve impulse. In favor of this contention was our finding that reserpine’s site of action is the amine uptake mechanism of the granules. The failure of adrenergic transmission as well as the behavioral actions of reserpine were correlated with the blockade of granular uptake induced by the drug, rather than to the size of the transmitter stores (Lundborg, 1963). Moreover, extragranular noradrenaline (accumulated in adrenergic nerves by pretreatment with reserpine, followed by an inhibitor of monoamine oxidase (MAO) and systemically administered noradrenaline) was unavailable for release by the nerve impulse, as observed histochemically (Malmfors, 1965). We proposed that, under normal conditions, the extragranular fraction of monoaminergic transmitters was very small, owing to the presence of MAO intracellularly, and that the evidence presented to the contrary was an artefact. Subsequent work in numerous laboratories has lent support to these views. At the Stockholm symposium, William Douglas presented evidence suggesting a calcium-triggered fusion between the granule and the cell membrane, which preceded the release. The release is now generally assumed to take place as exocytosis, even though a fractional, rather than complete, extrusion of the granule content seems to be the most likely alternative. For a discussion of this issue, see a recent paper by Folkow and Nilsson (1997), presented as a tribute to the late Jan Häggendal.

An important issue in the early debate on synaptic structures and mechanisms dealt with the site of action of major psychotropic drugs. In their first studies on reserpine, Brodie and his colleagues had proposed that the agent was capable of releasing serotonin onto receptors, which would suggest the cell membrane to be its site of action. However, our observations demonstrated that reserpine acted on the storage mechanism of the synaptic vesicles. As to the tricyclic antidepressants, Brodie et al. suggested that their site of action was the synaptic vesicles. In their original studies, reported in 1960, Axelrod et al. (see Axelrod, 1964) observed that the uptake of circulating catecholamines by adrenergic nerves could be blocked by a variety of drugs, such as reserpine, chlorpromazine, cocaine, and imipramine. These studies obviously did not distinguish between a number of different pharmacological mechanisms. In our own combined biochemical (Carlsson et al., 1962b, see also the independent, simultaneous work of Kirshner, 1962) and histochemical studies (Malmfors, 1965), two different amine-uptake mechanisms could be distinguished: uptake at the level of the cell membrane, sensitive to cocaine and imipramine, for example, and uptake by the storage granules or synaptic vesicles, sensitive to reserpine, for example. These two mechanisms must be distinguished from each other because of the different, functional consequences of their inhibition—enhancement and inhibition, respectively—of monoaminergic neurotransmission.

Disclosure of the Mode of Action of the Major Antipsychotic Agents

In the early 1960s we were puzzled that the major antipsychotic agents, such as chlorpromazine and haloperidol, had a reserpine-like pharmacological and clinical profile, yet lacked the monoamine-depleting properties of the latter drug. We found that chlorpromazine and haloperidol accelerated the formation of the dopamine metabolite 3-methoxytyramine and the noradrenaline metabolite normetanephrine, while leaving the neurotransmitter levels unchanged. In support of the specificity, neither promethazine, a sedative phenothiazine lacking antipsychotic and neuroleptic properties, nor the adrenergic blocker phenoxybenzamine caused any change in the turnover of the catecholamines (Carlsson and Lindqvist, 1963). To us it did not seem farfetched, then, to propose that rather than reducing the availability of monoamines, as does reserpine, the major antipsychotic drugs block the receptors that are involved in dopamine and noradrenaline neurotransmission. This would explain their reserpine-like pharmacological profile. To account for the enhanced catecholamine turnover we proposed that neurons can increase their physiological activity in response to a receptor blockade. This, I believe, was the first time that a receptor-mediated feedback control for neuronal activity was proposed. These findings and interpretations have been amply confirmed and extended by numerous workers, using a variety of techniques. In the following year our research group discovered the neuroleptic-induced increase in the concentrations of deaminated dopamine metabolites (Andén et al., 1964a). Later papers by Andén et al. (1970a) from our own laboratory and by Nybäck and Sedvall (1970) emphasized the effect of neuroleptics on dopamine, and the work of Aghajanian and Bunney (1974) described the effect of dopaminergic agonists and antagonists on the firing of dopaminergic neurons. Other important, subsequent discoveries were the dopamine-sensitive adenylate cyclase by Greengard and his colleagues (Kebabian and Greengard, 1971) and the binding of dopamine to specific cell-membrane sites, from which it could be displaced by neuroleptics (Seeman et al., 1976; Creese et al., 1976).

These observations formed the basis for the “dopamine hypothesis of schizophrenia.” It should be noted, however, that the paper by Lindqvist and me did not particularly emphasize dopamine, even though the adrenergic blocker was inactive and the effect of haloperidol was more striking on dopamine than on noradrenaline turnover. In fact, we did not exclude the possibility that serotonin receptors could also be involved in the antipsychotic action. Even though our subsequent research favored an important role for the dopamine-receptor blockade in the antipsychotic action, the data could hardly exclude a contributory role of other monoaminergic receptors. Such a possibility has gained increased interest more recently, thanks to research on clozapine and other atypical antipsychotic agents.

Dopamine, the Reward System, and Drug Dependence

That dopamine plays a crucial role in the reward system and in drug dependence is now generally recognized. Our research group became interested in this problem in the mid-1960s, when we and others found that amphetamine releases dopamine and that its stimulating action can be blocked by an inhibitor of catecholamine synthesis, α-methyltyrosine. Somewhat later, Gunne also found that the stimulant and euphoriant action of amphetamine in humans could be prevented by treatment with α-methyltyrosine. Our further pursuit of this line of research led to the concept that dopamine is also involved in the psychostimulant and dependence-producing action of some other major drugs of abuse, such as the opiates and ethanol. Thus, in ethanol, we found that its stimulating action in animals is accompanied by an increase in dopamine synthesis (Carlsson and Lindqvist, 1973) and can be prevented by α-methyltyrosine, which can also prevent the stimulating and euphoriant action of ethanol in humans (for a review, see Engel and Carlsson, 1977).

Our studies on the role of dopamine and other neurotransmitters in drug dependence were later pursued and extended by Jörgen Engel and his colleagues. Engel is my successor as professor of pharmacology in our department.

The fundamental role of dopamine in the reward system also has important implications for the treatment of various maladies with neuroleptic drugs. Since they are all dopamine-receptor blocking agents, they are likely to impair the reward system, resulting in dysphoria and anhedonia. Such side effects may be at least as serious as the extrapyramidal side effects. In fact, because the site of action of the reward system is probably in the ventral striatum, which appears to be more sensitive to dopamine-receptor blockade than the dorsal striatum, an impairment of the reward system is likely to show up in lower doses of neuroleptics than the extrapyramidal side effects, which mainly reside in the dorsal striatum.

The Discovery of Doparninergic Autoreceptors and Their Potential Role as Targets for Drugs

We were investigating autoreceptors in 1963, even though we did not understand it at that time. The nature of the feedback mechanism that we had proposed was obscure, apart from its mediation via receptors that respond to the neurotransmitter in question. Some have said that we proposed a feedback loop, but this is not true. It was not until the early 1970s that we were able to examine the problem further. In the meantime, Farnebo and Hamberger, in 1971, had proposed the existence of presynaptic receptors as one possible explanation for their observation that the release of catecholamines from brain slices after field stimulation could be influenced by receptor agonists and antagonists. After we had developed a method to measure the first, rate-limiting step in the synthesis of catecholamines in vivo we discovered that the synthesis of dopamine could be inhibited by a dopamine-receptor agonist and stimulated by an antagonist, even after exclusion of a feedback loop by means of axotomy (Kehr et al., 1972). Thus, we felt convinced that the receptors involved were presynaptic. In order to avoid confusion over the nature of these receptors, which appeared to be located on various parts of the neuron and possessed a special functional significance among the presynaptic receptors, I proposed to call them “autoreceptors” (Carlsson, 1975), a word that later became generally accepted. I also proposed that agents with selective action on autoreceptors may prove useful not only as research tools but also as therapeutic agents. We already knew that low doses of a dopaminergic receptor agonist could have a preferential action on autoreceptors and thus cause a paradoxical behavioral inhibition.

Four years later, our collaboration with skillful organic chemists led to the discovery of 3-PPP. In our original studies this agent appeared to be highly selective for dopaminergic autoreceptors, but a few years later, when we had the opportunity to study the pure enantiomers of 3-PPP, we discovered that they had different pharmacological profiles. The + form turned out to be an agonist rather similar to apomorphine, though with somewhat lower intrinsic activity, whereas the – form was found to have agonistic properties on the dopaminergic autoreceptors, but with moderate intrinsic activity. On postsynaptic dopamine (D₂) receptors the – form behaved essentially as an antagonist, although it seemed devoid of cataleptogenic properties (for a review, see Clark et al., 1985).

Subsequent work revealed that the profile of (–)-3-PPP, now also called preclamol, is shared by many other dopaminergic agents, which all appear to have in common the property of being partial receptor agonists. Several such agents, with varying intrinsic activities and specificity, have been or are now being tested in vivo, mainly as antipsychotic agents. In fact, these agents may test two different, though somewhat related, hypotheses: First, that a preferentially or selectively acting dopaminergic autoreceptor agonist may have antipsychotic properties, though with fewer side effects than the classical neuroleptics, and second, that a partial dopamine receptor agonist may possess a suitable intrinsic activity to avoid extrapyramidal side effects, including tardive dyskinesias, and yet be sufficiently antagonistic on postsynaptic receptors to allow for an antipsychotic action.

In 1986, I received a letter from Carol Tamminga of the Maryland Psychiatric Research Center, in which she enquired about the possibility of trying (–)-3-PPP in patients with schizophrenia. She had been informed by her chief, William Carpenter, about a presentation of mine at a meeting in Heidelberg, in which I had reported preclinical data on this agent, indicating antipsychotic properties and lack of extrapyramidal side effects. Dr. Tamminga had a long-standing interest in the possible usefulness of dopaminergic agonists in the treatment of schizophrenia, starting from her discovery that apomorphine, given in single doses, can alleviate psychotic symptoms in patients with schizophrenia (Tamminga et al., 1978). I replied that I would be delighted to supply her with the drug and the documents she would need to conduct a new-drug investigation and to assist her as much as possible in carrying out such a study. With her letter a most stimulating and fruitful collaboration began, and is still ongoing.

It took some time to obtain the Investigational New Drug application from the Food and Drug Administration. In 1989, the first series of patients started to receive single, escalating intramuscular doses of (–)-3-PPP or of placebo, in a double-blind study. The results were encouraging. Psychotic symptoms tended to be reduced, and the drug appeared to be well tolerated (Tamminga et al., 1992). We subsequently gave patients with schizophrenia escalating, single oral doses of the drug in an effort to obtain the same plasma levels as we had achieved in the parenteral study. Again, the results were promising. The next step was to give repeated doses of the drug or placebo in a double-blind crossover design. We found that 1 week of treatment with (–)-3-PPP caused a significant antipsychotic response, but that a therapeutic effect did not remain after 2 or 3 weeks. Apparently, some kind of tolerance had developed (Lahti et al., 1997). As expected on the basis of the preclinical data, extrapyramidal effects were not detectable. In fact, (–)-3-PPP is anticataleptic in rats and has been shown to possess mild antiParkinson action in clinical studies (Pirtosek et al., 1993). In these studies, the partial dopamine receptor agonism became apparent, in that the drug was able to antagonize dopamine-receptor agonists, while at the same time having anti-Parkinson properties.

Further studies are underway to investigate the possibility of developing (–)-3-PPP to a therapeutically useful antipsychotic agent. If these efforts are successful, they will no doubt represent a breakthrough by being antipsychotic without manifesting the serious side effects induced by toosevere dopamine-receptor blockade. These effects are not limited to motor functions but extend to the endocrine system and to severe dysphoria, probably related to interference with the well-established function of dopamine in the reward system.

Another line of autoreceptor research deals with the preferential dopamine autoreceptor antagonists, which have likewise been developed by our research group (see Svensson et al., 1986). A prototype for these agents is ( + )-UH 232 (N,N-dipropyl-cis-( + )-(1S,2R)-5-methoxy-1-methyl-2-aminotetralin). In animal experiments this agent presents a fascinating mixture of behaviorally stimulating and depressant properties. In lower dosages it tends to be predominantly stimulating, apparently the result of a preferential antagonistic action on dopaminergic autoreceptors, whereas higher doses tend to be predominantly depressant, especially if the animal’s behavioral baseline level is high. This latter action is apparently caused by an antagonistic action on dopaminergic postsynaptic receptors. In rats, selfadministered cocaine ( + )-UH232 and related agents have been found to reduce the motivation for this drug-seeking behavior (Roberts and Ranaldi, 1995). So far, ( + )-UH232 has only been given in single, oral doses to human volunteers and patients with schizophrenia (unpublished data). In my laboratory a number of compounds with possibly more favorable properties, such as OSU 6162, have been prepared and are now being further evaluated. Preliminary observations suggest that they represent a somewhat heterogeneous group of agents, for reasons such as their effects on D3 receptors and other receptor subtypes that are only partly understood.

After working on the concept of autoreceptors for about 25 years, with the development of preferentially acting dopaminergic agonists and antagonists, my colleagues and I are pleased to note that this area of research is now active. However, another 5 to 10 years will presumably be needed to obtain a reasonably clear evaluation of the autoreceptor approach in psychopharmacology.

Discovery of Selective Serotonin Reuptake Inhibitors

Whereas dopamine, like Cinderella, had to dwell in obscurity for a long time until it came into glory, serotonin took another path. Very soon after the discovery was made that serotonin is a normal brain constituent, it started to attract a great deal of interest. Moreover, a link between serotonin and LSD was discovered and brain serotonin was proposed to play a role in keeping us sane (see Gaddum, 1953). This culminated with the discovery of reserpine’s serotonin-depleting action. However, when subsequent work disclosed the catecholamine-depleting action of reserpine, noradrenaline and later dopamine came into focus, and serotonin lost its dominant place. But serotonin has made a splendid comeback in a number of different contexts.

The tricyclic antidepressants were first shown to block the reuptake of noradrenaline, and thus this neurotransmitter was proposed to play a major role in the control of mood and drive. Later we discovered, however, that the tricyclic antidepressants also have powerful actions on the reuptake of serotonin and that this applied particularly to some of the most widely used antidepressants (Carlsson et al., 1968; also see Carlsson, 1976, 1982, 1986). Together with the late Dr. Hans Corrodi, a highly talented Swiss chemist, we then developed the first selective 5-HT uptake inhibitor, zimelidine (Berntsson et al., 1972), which turned out to be an active antidepressant agent, as demonstrated in several well-controlled clinical studies (see Carlsson et al., 1981) but was withdrawn because of rare but serious side effects. Subsequently, a number of other selective serotonin uptake inhibitors were developed and were likewise found to be efficacious antidepressants. This, in conjunction with the previous discovery of an antidepressant action of L-tryptophan (Coppen, 1963) and of reduced concentrations of 5-hydroxyindoleacetic acid in the cerebrospinal fluid of patients with depression and those who were suicidal (Träskman et al., 1981), led to a marked increase in the visibility of serotonin, which is now generally recognized as an important neurotransmitter in the control of mood.

More recently, serotonin also started to attract a great deal of attention in the control of anxiety. Panic disorders appear to respond especially well to serotonin uptake inhibitors. Most remarkably, obsessive-compulsive conditions appear to respond specifically to serotonergic drugs (see Eriksson and Humble, 1990). The ability of these agents to influence personality aberrations, also within the range of normal variation, has attracted considerable interest, as evident from the book Listening to Prozac (Kramer, 1993). The introduction of the selective serotonin reuptake inhibitors (SSRIs) obviously represents a major therapeutic advance in psychiatry as well as a milestone in rational drug development.

Controversial Priority Issues

Because the aim of scientific research is to gain new knowledge, the novelty aspect is of paramount importance. An excellent report of data or proposal of a theory is of limited scientific value if the same thing has been put forward before. In order to get real credit for one’s work a scientist has to be first. What may be at stake in this context may, of course, be of decisive importance for a scientist’s entire career.

This reminds me of an anecdote stemming from Jean Delay’s teacher, Nageotte (Deniker, 1983): “If something new appears in medicine one starts by saying: it is not true. Once the fact has been proven one says it is true, but unimportant. Finally, when a fact has been proven and proven important one says in medicine: it is not he who discovered it.” In fact, these few sentences point to some most important, highly legitimate questions that have to be raised about a new discovery. Sadly, however, it is not always in the interest of truth that attempts are made to challenge scientific discoveries.

One case deals with the discovery of dopamine in the brain. It should be clear that this discovery has to be credited entirely to our research group, as we disclosed in our paper in Science (Carlsson et al., 1958). However, some authors have challenged this, referring to two papers published in Nature the year before (Montagu, 1957; Weil-Malherbe and Bone, 1957). It is curious that, to my knowledge, none of these authors have themselves challenged our claims of having discovered dopamine in the brain. To anybody with an elementary knowledge in techniques of biochemical analysis, who has taken the trouble to read these papers carefully, it will be clear that they have not presented any acceptable evidence for the occurrence of dopamine in the brain, nor proposed any particular function for it. Unfortunately, however, even a few specialists in this field have overlooked the obvious shortcomings of these papers. This is the reason why I feel that I have to comment on them.

Both papers used the same highly unspecific and inadequate method, introduced by Dr. Weil-Malherbe, and the results clearly indicate that the method does not measure dopamine. Thus, in Weil-Malherbe’s paper with A. D. Bone, dopamine is found in the brainstem in very large amounts, actually higher than the noradrenaline values. As is well known, the dopamine levels in the brainstem are low, lower than the levels of noradrenaline. Similar inadvertancies can be found in Montagu’s paper. Those values of dopamine were obtained by subtracting the fluorescence values that were derived from a highly unspecific ethylene diamine condensation method, from those obtained by a conventional fluorimetric method for measuring adrenaline and noradrenaline. Documentation that this subtraction method measures dopamine is entirely lacking and, in contrast to our own specific method, which became a citation classic, it was never widely used and was soon abandoned, even by Weil-Malherbe himself.

Montagu wisely did not claim that she had identified or measured dopamine, but rather a compound “X.” She claimed that compound X (which is likely to be a mixture of several compounds) had the same Rf value as dopamine, but she did not give an RF value for either dopamine or compound X, nor did she specify the paper-chromatographic system she used, nor did she explain how the spots had been developed. No chromatogram was shown. Such poor documentation, or rather absence of documentation, which was not amended in any subsequent publication, is of course entirely unacceptable. Moreover, even if one generously accepts that Montagu has observed dopamine as a spot on paper chromatography, such a merely qualitative demonstration of dopamine in the brain was not surprising, because dopamine was then already generally believed to serve as a precursor of noradrenaline and adrenaline. It is thus only natural that there was no indication in Montagu’s paper that she considered the possible presence of dopamine in the brain to be in any way remarkable.

In contrast, in our Science paper in 1958 we identified dopamine in the brain beyond doubt and provided correct figures for its levels. Moreover, we provided pharmacological data demonstrating a relationship between variations in dopamine and brain function. Thus we proposed for the first time, and on the basis of good documentation, that dopamine is not merely a precursor of noradrenaline but an agonist in its own right.

Another issue deals with the discovery of the regional distribution of dopamine in the brain. Credit for this discovery is sometimes given entirely to Bertler and Rosengren (1959). It is fair to mention that Bertler and Rosengren were my graduate students and were preparing for their theses under my direction. We had agreed that the study of the distribution of dopamine in the brain should be part of their thesis work. Thus, according to publication policies in Sweden then, it would have been appropriate not to have my name on the first publication on this issue. To restore the balance, however, I made the first announcement of dopamine’s abundance in the basal ganglia at the First International Catecholamine Symposium, in November 1958 (published in Pharmacological Reviews, Carlsson, 1959). Here I also summarized, for the first time, the arguments of a role for dopamine in extrapyramidal functions and disorders.

The most bizarre priority issue that I have personally been involved in deals with the development of the first SSRI. The first SSRI to be developed, both at the preclinical and clinical stage, was zimelidine. Much to my amazement, however, I came across a mini-review in Life Sciences in August 1995, titled “Prozac (Fluoxetine, Lilly 110140), the First Selective Serotonin Uptake Inhibitor and an Antidepressant Drug Twenty Years Since Its First Publication” (Wong et al., 1995). I wrote to Dr. Wong at Lilly and reminded him that the disclosure of the SSRI properties of zimelidine came more than 2 years before that of fluoxetine. In terms of clinical development and demonstration of antidepressant properties, zimelidine was even more ahead of fluoxetine. In the widely read book Listening to Prozac, in which the Lilly Corporation scientists are interviewed, these scientists likewise appear to give themselves the entire credit for the discovery of the SSRIs.

I managed to convince the Lilly scientists that a correction of their mini-review would be appropriate. Such a correction has now appeared in Life Sciences. This note clearly states that the first SSRI was zimelidine (Carlsson and Wong, 1997).

Recent and Ongoing Research

To include recent or ongoing research in an autobiography seems somehow inappropriate, because it lacks historical perspective. Still, at least in my case, it sheds some light on my previous research. I will focus on three research projects that are partly interrelated. Some of it has recently been reviewed (Carlsson et al., 1997).

A Working Hypothesis on a Thalamic Filter and Its Feedback Regulation via the Striatal Complexes

About 10 years ago we tried to design a model to explain the paradox that antipsychotic agents, such as dopamine D₂ receptors which without doubt exert powerful actions on the cerebral cortex, act mainly on targets that are sparse in the human cerebral cortex. Based on available pharmacological and neuroanatomical evidence, we postulated that the striatal complexes, comprising the dorsal and ventral striatum and the corresponding dorsal and ventral pallidum, exert a predominantly inhibitory function on the thalamus, leading to a reduced transmission of sensory information to the cerebral cortex as well as a concomitant reduction of arousal. As is generally recognized, arousal is controlled by the ascending reticular formation, which operates in close linkage with the sensory input. We assumed that dopamine is predominantly inhibitory on striatal neurons, and thus an increased dopaminergic tone should counteract the inhibitory effect of the striatal complexes on the thalamus and, consequently, enhance the relay of sensory information to the cortex and raise the level of arousal. If the transmission through the thalamus becomes excessive, the integrative capacity of the cortex may break down, and confusion or psychosis will ensue. In the striatum, dopamine is counterbalanced by a powerful corticostriatal glutamatergic system, which is derived from all parts of the cerebral cortex (Carlsson, 1988a).

A simple way to test the predictive value of this model would be to induce hypodopaminergia, leading to immobility (catalepsy), and then to inhibit the corticostriatal glutamatergic function. If the model is valid, mobility should then be restored, despite the absence of dopamine. Maria Carlsson and I did this experiment in 1989, and it came out as we predicted. In this experiment we depleted mice of dopamine through the use of reserpine in combination with α-methyltyrosine. The immobility thus induced was dramatically reversed by treatment with an NMDA-receptor antagonist either systemically or locally in the nucleus accumbens (Carlsson and Carlsson, 1989; Svensson and Carlsson, 1992).

We later discovered powerful interactions indicating that not only was dopamine counterbalanced by glutamate in the striatum but so also were noradrenaline and serotonin, whereas acetylcholine operated in concert with glutamate. Apparently the cerebral cortex exerts a powerful control of the subcortical monoaminergic systems via glutamatergic pathways projecting to the striatum (Carlsson and Carlsson, 1989a-c, 1990). Likewise, corticofugal glutamatergic pathways appear to exert a powerful control over the monoaminergic systems by projecting to the monoaminergic cell bodies in the lower brain stem. This control seems to consist of both an accelerator—a glutamatergic pathway projecting directly to the monoaminergic cells—and a brake, consisting of a glutamatergic pathway, followed by a gabaergic interneuron. A similar accelerator/brake system appears to exist in the striatum, that is, postsynaptically in relation to the monoaminergic systems.

One example illustrating the powerful role of glutamate for controlling the responsiveness of monoaminergic systems is provided by some recent observations we made in our laboratory with 5-HT2 receptors. The stimulant action of the 5-HT2 agonist LSD is strongly potentiated by the NMDA antagonist MK-801 in monoamine-depleted mice, and this effect can be blocked by the potent and selective 5-HT2A-receptor antagonist MDL 100,907. In mice with an intact monoaminergic system, the psychostimulant action of MK-801 can be antagonized by MDL 100,907 already in quite low doses that are but slightly inhibitory on normal behavior. Originally, the scientists at Marion Merrell Dow Pharmaceuticals had discovered that MDL 100,907 can antagonize amphetamine-induced stimulation, while leaving baseline activity essentially unchanged. From the standpoint of psychotogenesis, these observations are interesting, given that all these neurotransmitters have been shown not only to influence psychomotor activity in animals and in man, but also to play a role in psychosis. In fact, the dopamine hypothesis of schizophrenia now appears to yield to a multifactorial concept of a dysfunction induced by a complex imbalance between several neurotransmitter systems.

The animal model psychosis induced by an NMDA antagonist can be tentatively used for testing the ability of antipsychotic drugs to restore the biochemical pattern in the brain, as revealed by multivariate analysis. Thus, the abnormal biochemical pattern of MK-801-treated rats can be partially restored by haloperidol and clozapine, though in different ways. The improvement by haloperidol occurs exclusively along an axis, steered by an influence on dopaminergic indices, whereas clozapine acts along a perpendicular axis, where serotonergic indices are influential. The effect of MDL 100,907 is similar to that of clozapine, suggesting that the latter drug acts largely via inhibition of 5-HT2A antagonism in this model.

Postmortem Studies

In collaboration with C.-G. Gottfries and others we performed two postmortem studies on brains from patients with schizophrenia. Several brain regions were analyzed for monoaminergic indices, that is, the levels of dopamine, noradrenaline, and serotonin, as well as some of their precursors and metabolites. Using conventional univariate statistics we were unable to detect any striking differences between controls and schizophrenics, when the latter, like the former, were treated as a single group. However, when we applied multivariate statistics, the patients with schizophrenia showed an almost complete separation from the controls. The data further indicated that the patients with schizophrenia did not constitute a homogenous group; both the type of schizophrenic disturbance (paranoid vs nonparanoid) and gender influenced the pattern of monoaminergic indices. Some of the deviating patterns showed similarities to those seen in experimental animals treated with NMDA-receptor antagonists.

In our pattern-recognition studies, using multivariate analyses of postmortem as well as animal experimental data, two members of our research group, Lars O. Hansson and Nicholas Waters, made especially important contributions. Both types of studies emphasize the intimate interactions between a variety of neurotransmitter systems, and the experimental data clearly indicate that a primary disturbance in one system may lead to complex changes in the biochemical pattern involving several neurotransmitters. Clearly, we are far from being able to identify any single factor that could account for the multiple biochemical changes occurring in the schizophrenic brain. Most probably schizophrenia, like so many other major disorders, is heterogeneous and not due to one single cause.

Oxidation of Catechols to Quinones

For a long time the so-called autoxidation of catechols, which may after all, according to recently published studies, be catalyzed by enzymes and thus should not be called autoxidation, has been assumed to occur in the brain. One piece of evidence supporting this contention is the occurrence of neuromelanin in catecholaminergic nerve cells. The possible physiological and pathophysiological role of this metabolic pathway is still obscure. To measure the formation of quinones in vivo is difficult, because they are highly reactive (and thus cytotoxic) and will remain in free form for but a very short time after their formation. In order to get a handle on this mechanism we have developed techniques for analyzing the major metabolites of these catechols, that is their 5-S-cysteinyl adducts. We have thus been able to demonstrate the occurrence of the 5-S-cysteinyl adducts of dopamine, dopac, and dopa in the brain. We have found that 5-S-cysteinyldopamine is more elevated than dopamine in the brain of patients with Parkinson’s disease, analyzed postmortem, which may be an indication of oxidative stress, possibly leading to degeneration of dopaminergic nerve cells (Fornstedt et al., 1989). Surprisingly, we have also found an elevation of 5-Scysteinyldopamine in the brains of people with schizophrenia (see Carlsson et al., 1997). Multivariate analysis has also proven most helpful in these studies.

These studies were initiated in collaboration with my former student, Evald Rosengren (now professor emeritus of pharmacology at the University of Lund; Rosengren et al. 1985), who played an important role in our early catecholamine studies in the 1950s and who more recently had studied catechol oxidation mechanisms in peripheral tissues. In the further elaboration of these studies, which required considerable analytical skill, Bodil Fornstedt made a most important contribution.

Collaboration with the Pharmaceutical Industry

I have had the opportunity to collaborate with the pharmaceutical industry for about 40 years. My doctoral thesis work evolved from collaboration with a drug company. I have been engaged in research projects jointly with five different drug companies from 1960 onward. This collaboration has had a considerable impact on my research. It has given me and my research team significantly more financial resources than we otherwise would have had. More important, it has increased our awareness that basic biomedical research should ultimately aim at clinically relevant advances.

Of special importance at an initial stage was the collaboration with Hässle, a subsidiary of the Astra Company, of Sweden. Very soon after my move from Lund to become the chairman of pharmacology at the University of Göteborg I was approached by the head of research at Hässle, Mr. Ivan Östholm. Östholm and the management of Hässle had a generous and sympathetic attitude toward collaboration with academic researchers. According to their philosophy, a collaboration should be based on a genuine mutual research interest. Thus, Hässle showed considerable flexibility in formulating their research projects so as to foster close collaboration with university groups.

At Hässle, the decision had been made to develop a drug for the treatment of heart arrhythmia by reducing the sympathetic tone. This decision was based on advice from a number of university researchers. When I learned about this project in 1961 I suggested that Hässle focus their efforts on developing a beta-adrenergic blocking agent. At that time the work at Eli Lilly Company on dichloroisoproterenol (DSI) was already known. I had learned about it at the First International Catecholamine Symposium in Bethesda, Maryland, in 1958 and in subsequent work, further illustrating the role ofbeta-adrenergic receptors on heart function. I proposed that Hässle start out from the structure of DCI to develop a clinically useful betaadrenergic blocking agent.

At that time, a skillful Swiss organic chemist, Dr. Hans Corrodi, had just been employed by Hässle. Corrodi and I started a fruitful and stimulating collaboration, which continued until his untimely death in 1973. Corrodi started synthetic work around the DCI molecule, and one such agent was taken to the clinical testing stage but was found to possess too-high intrinsic activity. Finally, the Hässle chemists made alprenolol, which turned out to be a clinical useful beta-adrenergic blocking agent and was placed on the market.

At the outset we did not know that ICI had started a similar research project and that they were somewhat ahead of us (for details, see Shanks, 1984). But in any event, alprenolol was one of the first beta-blocking agents to be placed on the market and became a milestone in the development and growth of the then very small drug company, Hässle. Later, Hässle developed the beta-1-selective antagonist metoprolol, which became an even greater success on the market. For a long time the beta-blockers belonged to the most important drugs marketed by the Astra group, as a whole. Moreover, a spinoff project on beta-adrenergic agonists, which was started at Hässle but which they could not pursue because of their limited resources, was transferred to the Astra subsidiary, Draco, where it resulted in successful drugs for the treatment of asthma. Thus, the company was able to build up the financial strength they needed to subsequently develop several other very successful drugs, such as omeprazol.

From a scientific point of view, the most important outcome of my collaboration with Hässle and Astra was the development of the first SSRI, zimelidine. In 1995, Dr. Östholm published an account of the successful and dramatic development that took place during his time as head of research at Hässle.

Medicinal Chemistry

Another important result of my collaboration with Hässle was that we were able to work directly with medicinal chemists, some of whom actually became members of our research group in the department of pharmacology, whereas others were located at the School of Pharmacy of the University of Uppsala. The latter group was initially headed by Dr. L.J.G. Nilsson, who managed to recruit a large group of graduate students, several of whom were later able to defend their Ph.D. theses within the framework of our collaboration.

In my opinion, a close collaboration between pharmacologists and medicinal chemists in an academic setting leads to a most fruitful crossfertilization and should thus be more widely implemented.

The collaboration with Astra during the 1970s and 1980s was a scientific success. For example, during that time the first dopamine autoreceptorpreferring agonists and antagonists, as well as the first selective 5HT1A receptor agonist 8-hydroxy-DPAT, still a gold standard, were developed. However, the spirit of the early collaboration, when Dr. Östholm was head of research at Hässle, had faded. The successful growth of Astra had led to the recruitment of a competent scientific staff, which, of course, was an important and useful development. But at the same time, the “NIH syndrome” (NIH = Not Invented Here) became prominent. Thus, the ideas generated from our collaboration with Astra were not given high priority, and Astra decided not to invest into further development of any agents synthesized within the scope of our collaboration.

In 1987, we started a fruitful collaboration with the Upjohn Company, and the collaboration with Astra/Hässle was then terminated. Thanks to Upjohn’s generous financial support we were able to increase both the pharmacological and chemical moieties of our staff. This collaboration lasted for 7 years and was a scientific success. For example, it was during this time that we were able to develop our concept of the thalamic filter mechanism and the interaction between neurotransmitters in neural circuitries. From the point of view of drug development it is still too early to have a final judgment, in view of some still-ongoing projects generated by our collaboration. In my opinion, however, the collaboration suffered clearly from the NIH syndrome.

After the termination of our collaboration with Upjohn in 1994 we were no longer able to keep our medicinal chemistry and pharmacology groups together in one and the same project. However, both groups are still actively involved in research, thanks to joint projects with three other drug companies. Among these, the one with Hoechst Marion Roussell (formerly Marion Merrell Dow) has been ongoing for the longest time. Our most stimulating collaboration was to increase our understanding of the involvement of serotonin, and especially the 5-HT2A receptors, in our circuitry models. This collaboration has been most successful. Among other things, it has disclosed an intimate relationship between the serotonergic and glutamatergic systems.

Collaborators

During the past half-century of active research I have had the privilege to work with hundreds of collaborators. The two most critical phases in my professional life were the sabbatical in Brodie’s lab and the first 3 years following my return to Lund. I have already pointed out how much I owe to Steve Brodie and his colleague, Park Shore, who generously introduced me to modern techniques in biochemical pharmacology and to the fascinating field of neuropsychopharmacology. Sadly, Steve is no longer with us, but I still enjoy a longstanding friendship with Park, and his wife, Helen.

Following my return to Sweden I faced the challenge of setting up a modern lab of biochemical pharmacology. I realized that I needed a lot of help to be able to do this. When I was still in Brodie’s lab I wrote to NilsAke Hillarp with a proposal to collaborate with him. Fortunately, he agreed. The first thing I did after returning to Sweden in January 1956 was to order an Aminco-Bowman spectrophotofluorimeter. I had no money for this expensive equipment, but I considered it absolutely essential to get it as quickly as possible. I applied to the Swedish Medical Research Council for the necessary funds. My application was referred to Professor Ulf von Euler. He did not consider this instrument necessary for measuring catecholamines. He had himself published a method to determine adrenaline and noradrenaline, using a filter fluorimeter, which, in his opinion, was adequate. Fortunately, I had mentioned in my application that I also intended to measure serotonin. Because serotonin could not be measured in his instrument, he supported my application, and I received the grant.

When I returned to Sweden a number of highly qualified and enthusiastic people were waiting for me at my home department. They had been working with me on calcium metabolism and were quite willing to join me in the new research area. My first laboratory assistant was Margit Lindqvist. She introduced me to laboratory techniques, starting in 1944, with the subcutaneous injection of drugs into guinea pigs. She was an enormously talented laboratory assistant, who, during the many years of our collaboration acquired various skills, especially in biochemical analysis. Her competence soon reached a level clearly above that of a laboratory assistant and made her a highly valued research associate. With her I wrote numerous papers, including the citation classic about the mode of action of major neuroleptics (Carlsson and Lindqvist, 1963). Sadly, she died prematurely, in 1978.

Tor Magnusson, another collaborator, started to work with me in 1949. He is a chemical engineer, is unusually talented, and has broad knowledge, extending from biochemical analysis to surgical techniques and statistics. He became assistant professor in pharmacological techniques. Although he has formally retired, he still comes to our department almost every day and is still of great help. Like Margit Lindqvist, he has coauthored many seminal papers in my bibliography. For example, he is a coauthor of the two seminal papers on L-dopa and dopamine, published by Carlsson et al. in Nature, in 1957, and in Science, in 1958. Tor has volunteered in a number of self-experiments with drugs. In 1957 we gave him an intravenous infusion of L-dopa. We expected to see some dramatic mental actions, but the only effect we could see was emesis.

Bertil Waldeck is also a chemical engineer. He started to work with me in 1956. In 1958, he and I published a paper on the fluorimetric measurement of dopamine (Carlsson and Waldeck, 1958). This paper also became a citation classic. He also coauthored our paper on dopamine in Science, in 1958. Like Margit Lindqvist and Tor Magnusson, Bertil Waldeck joined me when I moved from Lund to Göteborg, in 1959. I have published numerous papers with Waldeck. He successfully defended his Ph.D. thesis in 1975. Somewhat later, he was offered and accepted a prestigious position at the Astra subsidiary, Draco.

When I returned to Sweden in 1956, two graduate students who had worked with me on calcium metabolism joined me: Evald Rosengren and Ake Bertler. They liked to work together and nicely supplemented each other. Rosengren had a restlessly searching mind, while Bertler was the systematic organizer. Both of them contributed greatly to our research in various ways. They were instrumental in working out our method for analysis of adrenaline and noradrenaline. This became another citation classic (Bertler, Carlsson, and Rosengren, 1958). They later became professors of pharmacology and clinical pharmacology, respectively.

In 1960 the department of pharmacology moved into a brand new building, and we had generous funds for equipment. Later in the same year, NilsAke Hillarp and his skillful research assistant, Georg Thieme, joined us. (For a discussion of some of Thieme’s most important contributions, see Dahlström and Carlsson, 1986.) We could thus set up our methods and resume our research in the new department without much delay. The early 1960s were characterized by lots of activity, through which we contributed to a paradigm shift in brain research. After Hillarp’s move to the Karolinska Institute in 1962 to take over the chair of histology, he recruited a large number of young, enthusiastic students, and a fruitful collaboration began between his new group and our equally enthusiastic group, which likewise expanded with many new students. At about the same time Hans Corrodi, a skillful medicinal chemist, started to collaborate, first with us and later with both groups. Corrodi’s contributions in several areas became quite important to our research.

Sadly, many of the people who were actively engaged in this important development have passed away, in most cases, prematurely: Nils-Åke Hillarp, Hans Corrodi, Margit Lindqvist, Bengt Werdinius, Nils-Erik Andén, Björn-Erik Roos, Jan Häggendal, and more recently, Georg Thieme. Unfortunately, Hillarp and Corrodi did not live long enough to witness the spectacular outcome of their research efforts.

I have had the pleasure of seeing about 40 of my graduate students defending their Ph.D. theses successfully, and of working with an equally large number of foreign postdoctoral fellows, who have also contributed much to our success. Among the latter was our first foreign fellow, Lewis S. Seiden, who is now professor of pharmacology at the University of Chicago. The most remarkable thing about Lew’s stay with us was that he was able to teach us just about as much as we could teach him. Lew had had very good training in animal behavior, and introduced, for example, the technique of conditioned avoidance. We were then able to demonstrate, for the first time, the ability of L-dopa to restore the conditioned avoidance response in reserpine-treated animals (Seiden and Carlsson, 1963). As a result of Lew’s contribution a number of people have since defended their Ph.D. theses based on behavioral experiments, including my successor as professor of pharmacology, Jörgen Engel (for review, see Engel and Carlsson, 1977).

Collaboration with scientists in other departments was also important for our group. They have belonged to many different disciplines. For example, in animal behavior, we had a stimulating collaboration with Knut Larsson and his colleagues. With them, we demonstrated the remarkable ability of 5-HTlA agonists, such as 8-hydroxy-DPAT, to stimulate sexual behavior in the male rat (Ahlenius et al., 1981). In psychiatry, we performed postmortem studies on brains from patients with schizophrenia and dementia with C.-G. Gottfries (see Carlsson, 1981), and drug trials with Jan Wålinder and others on α-methyltyrosine–neuroleptic interactions in patients with schizophrenia (Wålinder et al., 1976) and on tryptophan–clomipramine interactions in patients with depression. We also have a longstanding collaboration with C.A. Tamminga and her colleagues at the Maryland Psychiatric Research Center, in Baltimore, studying the action of (–)-3PPP in patients with schizophrenia (Tamminga et al., 1992; Lahti et al., 1997).

With neurologists A. Svanborg, G. Steg, and their colleagues, we performed the first clinical study in Sweden with L-dopa in patients with Parkinson’s disease (Andén et al., 1970b), and with G. Stern, at the Middlesex Hospital in London, we studied the action of (–)-3PPP in patients with Parkinson’s disease (Pirtosek et al., 1993).

The first of these two studies was initiated after I had attended a meeting in Canada, in 1967, where George Cotzias presented his first dramatic results with oral L-dopa in the treatment of Parkinson’s disease. This was the first time that I met George. We became friends and had many stimulating discussions. My colleague Tor Magnusson spent an exciting sabbatical with George’s group in the mid-1970s. George’s untimely death in 1977 was a great loss to his many friends, as well as to science. In this context I must also mention the late Walther Birkmayer, whose friendship I appreciated a lot. Both Walther and George had intensely searching minds, were highly creative, and contributed enormously to the advances of clinical neuroscience. I miss them both very much.

We also collaborated with the neuropathologist A. Brun, in postmortem studies of Parkinson’s disease (Fornstedt et al., 1989), and with C. Kjellstrom (Fornstedt et al., to be published).

Attending Scientific Meetings

Meetings of various kinds are, of course, an essential component of scientific activity. In my own experience they have turned out to be of utmost importance, not only because of the scheduled programs but also because they provide valuable opportunities for informal discussions with colleagues and to learn about the latest “scientific gossip.” Personal contacts can probably never be entirely replaced by even the most sophisticated advances in communication techniques. Many of our ideas as well as opportunities for fruitful collaboration have been generated at scientific meetings. The proceedings that are sometimes published after scientific meetings are often of great value because they provide convenient access to accounts on significant advances, and—especially if the discussions are recorded—they can be invaluable historical documents by displaying the state of the art at a given point in time. Finally, but not least, meetings are a source of immense pleasure because they provide the opportunity to maintain friendships with many colleagues.

There is a rather special series of meetings that I have enjoyed attending for about 20 years. They were initially sponsored by Mr. and Mrs. Denghausen, who provided annual donations to Nathan Kline to enable him to assemble up to a dozen clinical and preclinical neuroscientists to spend a week on a Caribbean island, together with their wives. The purpose of these meetings is to create a relaxed atmosphere where the researchers have the opportunity to discuss neuropsychiatric issues in depth. The format is that each scientist presents some data of his own in an informal way with access only to a blackboard. The emphasis is on a brainstorming interaction between all the participants, who represent a broad area of knowledge. Thus, the speaker is interrupted throughout his presentation with questions and comments. The scheduled meetings take place only in the morning. The rest of the day gives the opportunity for even more informal scientific discussions. For a long time, Nate Kline was the central figure at these meetings. Nate was one of the most important pioneers of biological psychiatry and psychopharmacology, as is amply documented by numerous interviews of prominent people in the field made by David Healy (1996) in The Psychopharmacologists. Nate is often described as a flamboyant person, but when I met him he was in a later stage of his life, still with a lot of charisma but rather like a wise King Solomon. After Nate passed away in 1983, his function as organizer of these meetings was taken over by Robert Cancro, who managed to keep a similar format and atmosphere as before. I have found these meetings most enjoyable, and I am convinced that they have affected all the participants, not least by the generation of new ideas and by initiating new lines of research.

Reflections on Some Current Trends in Drug Research

The last few decades have seen a dramatic evolution of techniques that are useful in drug research, extending from the molecular level all the way to the highest levels of integration. Unfortunately, the spectacular advances in molecular biology have led to an overoptimism on future possibilities in drug discovery. In the past, this discovery process has nearly always depended on observations at higher levels of integration, and in fact, not seldom, on unexpected clinical findings. Insofar as the molecular mechanism of action is concerned, it has generally become disclosed after the discovery of a new therapeutic principle. Actually, cases are known where the mode of action has remained obscure for decades and even still remain unknown, as is the case with lithium.

Today, the belief is often expressed that from now on, drug discovery will take a new path, starting out with the genome and the identification and cloning of proteins involved in pathogenetic mechanisms. However, the question of how to identify those proteins that are useful as drug targets, remains unanswered.

Managers of drug companies have become reluctant to develop drug candidates with interesting and promising new pharmacological profiles until the precise molecular mechanism has been disclosed. Such an attitude may not only lead to missed opportunities, but may also cause a longstanding loss of competence in their scientific staffs, owing to a too-heavy weight placed on molecular biology at the expense of expertise at higher levels of integration.

Paradoxically, the ever-increasing sensitivity of techniques leads to a new problem: as the sensitivity approaches the background noise of nature, there is a risk that the detection and identification of a new molecule will initiate resource-demanding work for years, which will finally lead to the conclusion that the molecule in question is just the result of a failure of the precision of biology. The aspect of redundancy or superfluousness calls for a lot more awareness than was previously the case, when detection techniques were rather insensitive and the risk of touching the background noise was minimal.

Thus, it can be argued, for example, that a number of the numerous, admittedly highly active neuropeptides that have been found in the brain are not necessarily functionally important. They may, for example, be redundant vestiges from a time before the evolution of neurons from round cells, in which they played an important role as hormones, but with the advent of long processes to make nerve cells they may have become less useful, given that they had to be elaborated around the cell nucleus before being transported to their site of function, the nerve terminal (for further discussion, see Carlsson, 1988b). Similar views have been expressed by Bowers (1990), who emphasized the marked species variation in the occurrence and distribution of neuropeptides in the brain should arouse the suspicion of superfluousness.

My Family

A successful career always depends at least to some extent on luck. I was fortunate to grow up in an academic environment and to be encouraged and supported in many ways by my parents.

My wife, Ulla-Lisa, and I have been married since 1945. We had attended the same school and thus had already known each other for many years. My wife is a physician but practiced medicine for only a short time. We have five children altogether; our first child was born in 1947. Like my mother, Ulla-Lisa has given priority to raising our children and keeping our home in good shape. However, as the children grew up and left our home she has spent an increasing amount of time assisting me in my research in many respects, for example, looking after my correspondence, keeping all my papers in good order and reading and criticizing my manuscripts. Needless to say, the priorities my wife chose have been favorable for my scientific career. Without her loyalty, assistance, and support, in numerous ways I would not have been able to accomplish by far as much as has now been possible.

I also owe a lot to our five children, not least to our two daughters. The older one, Lena, is a science writer, and together with her I have had the most stimulating experience of writing a book titled Messengers of the Brain. It was intended for educated laymen, students of psychology, and others. Unfortunately, the Swedish version, which appeared in 1988, is now out of print. A Japanese version has appeared, thanks to the initiative of my friend, Professor H. Narabayashi, who actually did the translation from English together with a colleague.

Our younger daughter, Maria, is assistant professor of pharmacology in our department. With her I have done a lot of stimulating and successful research on the interactions between different neurotransmitters in circuitries connecting the cerebral cortex with various subcortical structures. Some of this work has been mentioned in this autobiography.

My three sons have chosen different careers. Bo is an ophthalmologist, and works at the University Hospital. Hans is an economist who specializes in game theory. He is employed as assistant professor at the University of Lund, where I received my professional and scientific training. Magnus, the youngest of our children, has a Ph.D. in computer science.

Clearly, the assembled knowledge of our children is quite broad and has been very useful to the whole family. In addition, we have seven grandchildren. To be able to follow their growth and development has been, and still is, a great privilege and source of pleasure.

Concluding Reflections

Ideally, a scientific discovery may be thought of as an instantaneous, “eureka” kind of happening. There is no doubt that such events do occur. One example is the demonstration of humoral transmission in the frog heart by Otto Loewi. More frequently, however, a discovery is a process that evolves from a series of observations by different investigators over a varying length of time. A fascinating example is the discovery of the planets’ rotation around the sun. This may seem a far-fetched example in the present context, but I find it remarkably illuminating and instructive, not least owing to the clever and penetrating way in which this particular discovery process has been narrated and analyzed by Arthur Koestler (1959) in The Sleepwalkers. It started with Copernicus’ postulate in the 16th century (actually an iteration of Aristarchos’ contention, 1800 years before), and became well-established by Kepler in the beginning of the 17th century, thanks to his mathematical analysis of the extensive and careful astronomical observations by Tycho Brahe for two decades at the end of the 16th century. However, an understanding of the underlying mechanisms was not reached until the end of the 17th century through Newton’s further analysis of Kepler’s “laws,” which led to the concept of gravity. Even though the discovery process is generally more rapid today, this example may still be looked upon as a role model by demonstrating the complexly interweaved contributions of different personalities using different approaches and technologies.

A comprehensive and fully adequate account of the dramatic development in which my colleagues and I have had the opportunity of taking part will have to await an outstanding narrator like Arthur Koestler. A scientist who has been actively engaged in such a process can, at best, be expected to give a reasonably fair account of his own contributions and to bring them into the context of the work of others. If at all possible, he would probably prefer to bring his account in conformity with the eureka model of discovery. One hopes that he would be able to do this without omitting or deemphasizing contributions by others. It will have to be left to my readers’ judgment as to what degree I am successful in this respect in this autobiography, and then not least when I try to summarize below the most salient scientific contributions by me and my co-workers.

Not far from the eureka model of discovery would be our identification of dopamine as a normal brain constituent, coupled with the recognition that dopamine plays an important role as an agonist in its own right not only in normal brain function but also in the pathophysiology of mental and motor disorders and in the mode of action of some important drugs.

To the same category would also belong our development of the first SSRI, zimelidine.

In a broader context, we have played an active part in a paradigm shift in brain research, through the recognition that chemical, rather than electrical, transmission is a major mechanism by means of which nerve cells communicate with one another in the brain. This paradigm shift has, of course, had a strong impact on basic brain research, but as exemplified by our own work, it has also opened up possibilities to unravel new pathophysiological mechanisms and to discover novel targets for therapeutically useful drugs.

I am very grateful for the ample recognition that has been bestowed upon me in the form of prestigious prizes, honorary degrees, and memberships. However, what I find most gratifying is alleviating the suffering of millions of people who are afflicted by various mental and neurological disorders, which the pursuit of our research has led to.

Selected Bibliography

Ahlenius S, Larsson K, Svensson L, Hjorth S, Carlsson A, Lindberg P, Wikström H, Sanchez D, Arvidsson L-E, Hacksell U, Nilsson JLG. Effects of a new type of 5-HT receptor agonist on male rat sexual behavior. Pharmacol Biochem Behavior 1981;15:785–792.

Andén N-E, Roos B-E, Werdinius B. Effects of chlorpromazine, haloperidol and reserpine on the levels of phenolic acids in rabbit corpus striatum. Life Sci 1964a; 3:149–158.

Andén N-E, Carlsson A, Dahlström A, Fuxe K, Hillarp N-Å, Larsson K. Demonstration and mapping out of nigro-neostriatal dopamine neurons. Life Sci 1964b;3: 523–530.

Andén N-E, Butcher SG, Corrodi H, Fuxe K, Ungerstedt U. Receptor activity and turnover of dopamine and noradrenaline after neuroleptics. Eur J Pharmacol 1970a;ll:303–314.

Andén N-E, Carlsson A, Kerstell J, Magnusson T, Olsson R, Roos B-E, Steen B, Steg G, Svanborg A, Thieme G, Werdinius B. Oral L-DOPA treatment of Parkinsonism. Acta Med Scand 1970b;187:247–255.

Bauer CH, Carlsson A, Lindquist B. Metabolism and homeostatic function of bone. In: Comar CL, Bronner F, eds. Mineral metabolism. An advanced treatise. New York: Academic Press, 1961;609–676.

Berntsson PB, Carlsson PAE, Corrodi HR (1972) Belg. Pat. 781105 (72-4-14).

Bertler Å, Carlsson A, Rosengren E. Release by reserpine of catecholamines from rabbits’ hearts. Naturwissenschaften 1956;22:521.

Bertler Å, Carlsson A, Rosengren E. A method for the fluorimetric determination of adrenaline and noradrenaline in tissues. Acta Physiol Scand 1958;44:273–292.

Carlsson A. The occurrence, distribution and physiological role of catecholaminesin the nervous system. Pharmacol Rev 1959;11:490–493.

Carlsson A. Physiological and pharmacological release of monoamines in the central nervous system. In: von Euler US, Rosell S, Uvnäs B, eds. Mechanisms of release of biogenic amines. Oxford: Pergamon Press, 1966;331–346.

Carlsson A. Dopaminergic autoreceptors. In: Almgren O, Carlsson A, Engel J, eds. Chemical tools in catecholamine research, Vol. II Amsterdam: North-Holland, 1975;219–225.

Carlsson A. The contribution of drug research to investigating the nature of endogenous depression. Pharmakopsychiat 1976;9:2–10.

Carlsson A. Aging and brain neurotransmitters. In: Platt D ed. Funktionsstorungen des Gehirns im Alter. Stuttgart and New York: Schattauer, 1981;67–82.

Carlsson A. Recent observations on new potential and established antidepressant drugs. Pharmakopsychiat 1982;15:116–120.

Carlsson A. Current views on the mode of action of antidepressant drugs. Adu Pharmacother 1986;2:167–174.

Carlsson A. Perspectives on the discovery of central monoaminergic neurotransmission. Ann Rev Neurosci 1987;10:19–40.

Carlsson A. The current status of the dopamine hypothesis of schizophrenia. Neuropsychopharmacology 1988a;l:179–186.

Carlsson A. Peptide neurotransmitters—redundant vestiges? Pharmacol Toxicol 1988b;62:241–242.

Carlsson A, Hillarp N-A.Release of adrenaline from the adrenal medulla ofrabbits produced by reserpine. Kgl Fysiogr Sällsk Forhandl 1956;26, No. 8.

Carlsson A, Lindqvist M. Effect of chlorpromazine or haloperidol on the formation of 3-methoxytyramine and normetanephrine in mouse brain. Acta Pharmacol (Copenhagen) 1963;20:140–144.

Carlsson A, Lindqvist M. Effect of ethanol on the hydroxylation of tyrosine and tryptophan in rat brain in vivo. J Pharm Pharmacol 1973;25:437–440.

Carlsson A, Serin F. The toxicity of nikethamide at different times of the day. Acta Pharmacol 1950;6:187–193.

Carlsson A, Theander G. On the duration of action of pentamethylenetetrazol. Acta Pharmacol 1946;2:227–234.

Carlsson A, Waldeck B. A fluorimetric method for the determination of dopamine (3-hydroxytyramine).Acta Physiol Scand 1958;44:293–298.

Carlsson A, Wong DT. A note on the discovery of selective serotonin reuptake inhibitors. Life Sci 1997;61:1203–1203.

Carlsson A, Shore PA, Brodie BB. Release of serotonin from blood platelets by reserpine in vitro. J Pharmacol Exp Ther 1957a;120:334–339.

Carlsson A, Rosengren E, Bertler Å, Nilsson J. Effect of reserpine on the metabolism of catecholamines. In: Garattini S, Ghetti V, eds. Psychotropic drugs. Amsterdam: Elsevier, 1957b;363–372.

Carlsson A, Lindqvist M, Magnusson T. 3,4-Dihydroxyphenylalanine and 5-hydroxytryptophan as reserpine antagonists. Nature (London) 1957c;180:1200.

Carlsson A, Lindqvist M, Magnusson T, Waldeck B. On the presence of 3-hydroxytyramine in brain. Science 1958;127:471.

Carlsson A, Falck B, Hillarp N-A. Cellular localization of brain monoamines. Acta Physiol Scand 1962a;56(Suppl. 196):1–27.

Carlsson A, Hillarp N-Å, Waldeck B. A Mg+ +-ATP dependent storage mechanism in the amine granules of the adrenal medulla. Med Exp 1962b;6:47–53.

Carlsson A, Falck B, Fuxe K, Hillarp N-Å. Cellular localization of monoamines in the spinal cord. Acta Physiol Scand 1964;60:112–119.

Carlsson A, Fuxe K, Ungerstedt U. The effect of imipramine on central 5-hydroxytryptamine neurons. J Pharm Pharmacol 1968;20:150–151.

Carlsson A, Gottfries C-G, Holmberg G, Modigh K, Svensson TH, Ogren S-O, eds. Recent advances in the treatment of depression. Acta Physiol Scand 1981, Suppl. 290.

Carlsson A, Hansson LO, Waters N, Carlsson ML. Neurotransmitter aberrations in schizophrenia. Life Sci 1997;61:75–94.

Carlsson M, Carlsson A. The NMDA antagonist MK-801 causes marked locomotor stimulation in monoamine-depleted mice. J Neural Transm Basic Neurosci Neural Sect Psychiatry Sect 1989a;75:221–226.

Carlsson M, Carlsson A. Dramatic synergism between MK-801 and clonidine with respect to locomotor stimulatory effect in monoamine-depleted mice. J Neural Transm Basic Neurosci Neural Sect Psychiatry Sect 1989b;77:65–71.

Carlsson M, Carlsson A. Marked locomotor stimulation in monoamine-depleted mice following treatment with atropine in combination with clonidine. J Neural Transm Basic Neurosci Neural Sect Psychiatry Sect (P-D Section) 1989c;l: 317–322.

Carlsson M, Carlsson A. Interactions between glutamatergic and monoaminergic systems within the basal ganglia—implications for schizophrenia and Parkinson’s disease. Trends Neurosci 1990;13:272–276.

Clark D, Hjorth S, Carlsson A. Dopamine receptor agonists: Mechanisms underlying autoreceptor selectivity. II. Theoretical considerations. J Neural Transm Basic Neurosci Neural Sect Psychiatry Sect 1985;62:171–207.

Dahlström A, Carlsson A. Making visible the invisible. (Recollections of the first experiences with the histochemical fluorescence method for visualization of tissue monoamines). In: Parnham MJ, Bruinvels J, eds. Discoveries in pharmacology. Vol 3, Amsterdam: Elsevier, 1986;97–128.

Engel J., & Carlsson A. Catecholamines and behavior. Curr Dev Psychopharmacol 1977;4:l-32.

Fornstedt B, Brun A, Rosengren E, Carlsson A. The apparent autoxidation rate of catechols in dopamine-rich regions of human brain increases with the degree of depigmentation of substantia nigra. J Neural Transm Basic Neurosci Neural Sect Psychiatry Sect 1989;1:279–295.

Kehr W, Carlsson A, Lindqvist M, Magnusson T, Atack C. Evidence for a receptormediated feedback control of striatal tyrosine hydroxylase activity. J Pharm Pharmacol 1972;24:744–747.

Lahti AC, Weiler MA, Corey PK, Lahti RA, Carlsson A, Tamminga CA. Antipsychotic properties of the partial dopamine agonist (–)-3PPP in schizophrenia. Biol Psychiatry 1997. [in press]

Pirtosek Z, Merello M, Carlsson A, Stern G. Preclamol and Parkinsonian fluctuations. Clin Neuropharmacol 1993;16:550–554.

Rosengren E, Linder-Eliasson E, Carlsson A. Detection of 5-S-cysteinyldopaminein human brain. J Neural Transm Basic Neurosci Neural Sect Psychiatry Sect 1985;63:247–261.

Seiden LS, Carlsson A. Temporary and partial antagonism by L-DOPA of reserpineinduced suppression of a conditioned avoidance response. Psychopharmacologia 1963;4:418–423.

Svensson K, Hjorth S, Clark D, Carlsson A, Wikström H, Andersson B, Sanchez D, Johansson AM, Arvidsson L-E, Hacksell U, Nilsson JLG. (+)-UH 232 and ( + )UH 242: Novel stereoselective DA receptor antagonists with preferential action on autoreceptors. J Neural Transm Basic Neurosci Neural Sect Psychiatry Sect 1986;65:1–27.

Tamminga CA, Cascella NG, Lahti RA, Lindberg M, Carlsson A. Pharmacologic properties of (–)-3PPP (Preclamol) in man. J Neural Transm Basic Neurosci Neural Sect Psychiatry Sect 1992;88:165–175.

Wålinder J, Skott A, Carlsson A, Roos B-E. Potentiation by metyrosine of thioridazine effects in chronic schizophrenics.Arch Gen Psychiatry 1976;33:501–505.

Additional Publications

Aghajanian GK, Bunney BS. Pre- and post-synaptic feedback mechanisms in central dopaminergic neurons. In: Seeman P, Brown GM, eds. Frontiers of neurology and neuroscience research. Toronto: University of Toronto Press, 1974;4–11.

Andén N-E, Butcher SG, Corrodi H, Fuxe K, Ungerstedt U. Receptor activity and turnover of dopamine and noradrenaline after neuroleptics. Eur J Pharmacol 1970;11:303–314.

Axelrod J. The uptake and release of catecholamines and the effect of drugs. Prag Brain Res 1964;8:81–89.

Bertler Å, Rosengren E. Occurrence and distribution of dopamine in brain and other tissues. Experientia 1959;15:10.

Bowers CW. Superfluous neurotransmitters. Trends Neurosci 1994;17:315–320.

Carlsson M, Svensson A. Interfering with glutamatergic neurotransmission by means of MK-801 administration discloses the locomotor stimulatory potential of other transmitter systems in rats and mice. Pharmacol Biochem Behav 1990; 36:45–50.

Coppen A, Shaw D, Farrell JP. The potentiation of the antidepressant effects of a monoamine oxidase inhibitor by tryptophan. Lancet 1963;24ii:61–64.

Creese I, Burt DR, Snyder SH. Dopamine receptor binding predicts clinical and pharmacological potencies of antischizophrenic drugs. Science 1976;192:481–483.

Deniker P. Discovery of the clinical use of neuroleptics. In: Parnham MJ, Bruinvels J, eds. Discoveries in pharmacology, Vol 1. Amsterdam: Elsevier, 1983:163–180.

Eriksson E, Humble M. Serotonin in psychiatric patholphysiology. In: Pohl R, Gershon S, eds. The biological basis of psychiatric treatment, Vol. 3, Progress in Basic Clinical Pharmacology. Basel: Karger, 1990; 66–119.

von Euler US, Rosell S, Uvnäs B, eds. Mechanisms of release of biogenic amines. Oxford: Pergamon Press, 1966;331–346.

Farnebo L-O, Hamberger B. Drug-induced changes in the release of 3-H-monoamines from field stimulated rat brain slices. Acta Physiol Scand 1971; Suppl. 371: 35–44.

Folkow B, Nilsson H. Transmitter release at adrenergic nerve endings: total exocytosis or fractional release? News Physiol Sci 1997;12:32–36.

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Healy D. The psychopharmacologists. London: Chapman and Hall, 1996.

Hokfelt T. Thesis. Stockholm: I Haggstroms Tryckeri AB, 1968.

Kebabian JW, Greengard P. Dopamine-sensitive adenyl cyclase: possible role in synaptic transmission. Science 1971;174:1346–1349.

Kirshner N. Uptake of catecholamines by a particulate fraction of the adrenal medulla. J Biol Chem 1962;237:2311–2317.

Koestler A. The sleepwalkers. London: The Arkana Books, 1959. Kramer PD. Listening to prozac. New York: Penguin Books, 1993.

Lundborg P. Storage function and amine levels of the adrenal medullary granules at various intervals after reserpine treatment. Experientia 1963;19:479.

Malmfors T. Studies on adrenergic nerves. Acta Physiol Scand 1965;64, Suppl 248: 1–3.

Montagu KA. Catechol compounds in rat tissues and in brains of different animals. Nature (London) 1957;180:244–245.

Nybäck H, Sedvall G. Further studies on the accumulation and disappearance of catecholamines formed from tyrosine-14-C in mouse brain. Eur J Pharmacol 1970;10:193–205.

Östholm I. Drug discovery—A pharmacist’s story. Stockholm: Swedish Pharmaceutical Press, 1995.

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Donald R. Griffin

BORN:

Southampton, New York

August 3, 1915

EDUCATION:

Harvard University, B.S. (1938)

Harvard University, M.A. (1940)

Harvard University, Ph.D. (1942)

APPOINTMENTS:

Cornell University (1946)

Harvard University (1953)

Rockefeller University (1965)

President, Guggenheim Foundation (1979)

Harvard University, Associate of Zoology (1989)

HONORS AND AWARDS:

American Academy of Arts and Sciences (1952)

National Academy of Sciences, U.S.A. (1960)

Eliot Medal, National Academy of Sciences (1961)

Donald Griffin discovered, with Robert Galambos, the phenomenon of echolocation in bats. He carried out extensive studies of bat behavior, demonstrating conclusively that bats use echolocation to catch flying insects. He also conducted fundamental studies of homing in birds, bird navigation, and honeybee communication. He has written extensively on the topic of awareness in nonhuman animals.

Donald R. Griffin

Imight be called a “WASAG,” for white Anglo-Saxon agnostic, and I have been most fortunate in my relatives, friends, and general circumstances. My ancestors have been in the United States for at least three generations; some were part of the original Mayflower company, and one was a refugee from the slave revolts in Haiti. Two came from Ireland, including my great grandfather Thomas Francis Griffin (1820–1907). He must have led a full and fascinating life between his arrival at the age of 15, and his financial success in building up a prosperous foundry business that by the 1890s was selling carwheels to railroads literally around the world, from St. Petersburg through Europe and North America to Vladavostok. This emigrant boy was a distant cousin of the Irish playwright Gerald Griffin (1803–1840), but unfortunately he left no recollections, and we know only that he began by working on the new Mohawk and Hudson railroad as it was being expanded westward from Schenectady. To quote my father’s recollections, “In the 1830s the Mohawk and Hudson was a very small affair … with some 20 miles of track, two locomotives, .… half a dozen cars made out of stage coach bodies, and … a few horses to pull the cars when the locomotives broke down.” Curiously enough, my mother’s great grandfather, Asa Whitney, was superintendent of the Mohawk and Hudson. By the 1890s the thriving Griffin foundries produced such superior carwheels that the Whitney foundry in Philadelphia went bankrupt.

Mary Whitney Redfield Griffin (1885–1968) read to her only child so much that my father feared I would never learn to read myself. My favorites were Ernest Thompson Seton’s books and the National Geographic Mammals of North America with colored illustrations by Louis Aggassiz Fuertes. My father, Henry Farrand Griffin (1880–1954) had strong literary interests and was a scholarly amateur historian. A few years after he graduated from Yale in 1903 his father’s financial affairs collapsed in 1907 and he became a reporter for the New York Evening Sun, covering among other things Theodore Roosevelt’s Bull Moose Campaign and the sinking of the Titanic. After turning to advertising about the time I was born (August 3, 1915) he developed high blood pressure in his 40s and retired gradually to Barnstable, Massachusetts where he read widely, wrote numerous unpublishable essays, tried to improve on standard translations of selected Greek and Roman classics, and published two historical novels (H. F. Griffin, 1941, 1942).

My uncle, Alfred C. Redfield (1890–1983), encouraged my boyish interests in biology from time to time. A great grandson of William C. Redfield (1789–1857), who discovered the cyclonic nature of storms, he was an enthusiastic bird watcher in his youth, and by the 1920s he was a comparative physiologist at Harvard. His interests gradually shifted to ecology and he was one of the scientists who founded the Woods Hole Oceanographic Institution.

After fourth grade my schooling was highly irregular and at times consisted of tutoring at home by my father and a retired school teacher, as well as 2 years at Phillips Andover that were interrupted by illness; but it sufficed for admission to Harvard in 1934. My most vivid memory was the forbidding white-haired principal of the Barnstable grammar school delivering an impassioned sermon on the hideous doctrine of evolution, culminating with “Do any of you believe your grandmother was a monkey?” The occasion was the death of the famous plant breeder Luther Burbank who, we were assured, had been struck down by the Lord because of his blasphemous advocacy of biological evolution.

Wild mammals have fascinated me as long as I can remember—certainly since the age of 10. By the time I was about 12 my enchantment with trapping furbearers in the North Woods led to a few ill-fated efforts to trap local mammals; but even skinning roadkills was beyond me until a friend of my parents demonstrated the simple procedure of lifting the edge of the skin and cutting where it was still attached to the underlying muscle. Badly misaligned teeth required frequent trips to an orthodontist, and as a reward for putting up with this monthly tooth wiring I was taken to the Boston Museum of Natural History on Berkeley Street. After I had become familiar with the public exhibits I was encouraged to frequent the museum library, where a thoughtfully supportive librarian introduced me to scientific journals. In time I met curators Francis Harper and Clinton V. McCoy who encouraged a redirection of my enthusiasm for trapping furbearers to collecting small mammals and making them into study skins. Curiously enough McCoy was my laboratory teaching assistant in elementary zoology a few years later. At age 15, the age at which my great grandfather had emigrated from Ireland, I subscribed to the Journal of Mammalogy.

Collecting small mammals and reading about them at the museum library led me to hope I could describe a new subspecies of Peromyscus from Cape Cod based on variations in ratio of tail length to body length. This aspiration was based on the numerous papers by Outram Bangs describing new subspecies of small mammals from islands off the New England Coast, almost all of which have long since been relegated to synonomy. The books and papers I read told me that the red-backed vole Clethrionomys (then Evotomys) gapperi was found in damp mossy woodlands. But when I caught several on Sandy Neck, a very dry barrier beach with pine and oak woods, I came to realize that scientific papers were not always correct in every detail.

Trappers and deer hunters in Massachusetts were supposed to report to the Division of Fish and Game the number of various species they had taken. Doubtless encouraged by my father, I wrote to the appropriate authorities and obtained lists of the numbers of each species reported from each county. I wondered whether the populations of each species could be estimated from the numbers trapped. This required assumptions about how many could be taken without reducing the population and presumably causing a decline in numbers taken in subsequent years. All this was of course naive guesswork, and I remember Uncle Alfred diplomatically pointing out that the proportion of those killed and reported to those actually present must have been very different for deer and weasels.

Another redirection of my enthusiasm for trapping was to dream of becoming a fur farmer. I spent hours during school study hall planning and sketching the cages I would build. I bought by mail order live traps similar to the current “Have-a-heart” types and caught a few muskrats and skunks, for which I constructed substantial and roomy cages. But I was disappointed that my captives spent most of their time in the roomy nest boxes and very seldom showed themselves voluntarily in daylight. I also kept a few chinchilla rabbits, and my indulgent parents took me to meetings of the local rabbit breeders club. One piece of advice that I recall vividly when I asked about rabbit hutch construction was “Don’t try to build against rabbits.”

The first time I found a live skunk in one of my wire mesh traps I naturally approached it with great trepidation. But I had read that skunks don’t “shoot” unless seriously alarmed. So I decided that I could wrap the wire mesh trap and skunk in a piece of old rug, kindly donated by my mother, and carry it back to my waiting cage. The first time I tried this I nervously dropped the rug from a couple of feet above the cage. The rug protected me, but I had to ask for another piece for later captures. By the time I was driving a car at 16 I became confident enough to carry well wrapped traps in an automobile without mishap. This led to requests from family friends for humane removal of skunks living under their houses.

In 1932, when I was 17, I visited the Oliver Austin bird banding station at Eastham and was invited to spend a couple of weeks with the Austin family while collecting small mammals on the station grounds and learning about bird banding from the Oliver Austins, father and son, and Maurice Braun who is well known for his later work at Hawk Mountain, Pennsylvania. The Austin station was then one of the largest in North America in terms of numbers of birds banded per year. I learned how the Austins were catching small birds in cage traps, and helped them catch shorebirds with mist nets which were then quite new. They allowed me to band birds in Barnstable as a substation of the Austin enterprise.

My mammal collecting had only occasionally brought me into contact with bats; as I recall I had made a study skin of only one Eptesicus fuscus, but it was only natural to think of combining my interest in small mammals and banding birds. When I heard of a colony of bats in the attic of an abandoned frame house the Austins let me try a few of their bird bands on these bats. Recoveries the next year showed that the bats tolerated bird bands reasonably well (Griffin, 1934). From 1933 to 1938 I banded as many bats as I could catch at nursery colonies in buildings and in caves where they hibernated. I perfected what I have come to call the “Tom Sawyer fence whitewashing method” of recruiting college friends to participate in studies of animal behavior under natural conditions by letting them in on the secret that it is great fun.

Recoveries of banded little brown bats (Myotis lucifugus) showed that they migrated between caves in Vermont and nursery colonies as far away as Cape Cod (Griffin, 1940b, 1945; Gifford and Griffin, 1960; Davis and Hitchcock, 1965). Homing experiments yielded returns after displacement as far as 50 miles. But the real surprise from bat banding has been longevity records up to 20 years or more (Hall et al., 1957; Griffin and Hitchcock, 1965; Griffin, 1980; Roer 1971; Lehman et al., 1992; Sommers et al., 1993). I will never forget hearing Alan Grinnell, who accompanied me on a trip to Vermont caves in search of banded bats, exclaiming “He’s older than I am!” Lifespans of several years must be quite common, because I once recaptured 8% of a large group after 8 years, and some 10- to 12-year-old females were pregnant or lactating. Analyses of animal longevity are often confused by assuming that all marked animals not recaptured have died. But banded bats often move between colonies, so that many more must have survived than were recaptured.

At Harvard I concentrated heavily on biology and one quarter of my courses were in chemistry. Although I never used chemistry, faint memories have often helped me judge the plausibility of scientific ideas. I was only a B student, but John Welsh encouraged me to study activity rhythms of bats (Griffin and Welsh, 1937). The tutorial plan was still taken seriously at Harvard, and I was fortunate to have Jeffries Wyman as my tutor. He had me read elementary material on physical chemistry but also tolerantly supported my interests in migration of bats and birds. Physiology was the order of the day, and animal behavior was considered too vague for serious scientists. To satisfy a distribution requirement I took E. G. Boring’s half course in introductory psychology, but had to do so against the strong advice of a junior instructor who assured me it would be a waste of time.

I cannot recall just how my interests in bats turned to their orientation in the dark. Their agile flight in totally dark caves was most impressive, and I had read elementary accounts of Spallanzani’s experiments showing that blinded bats flew normally. Left to my own devices I might never have even heard of the physics professor George Washington Pierce, but Talbot Waterman and James Fisk told me I should ask whether his new apparatus for studying “supersonic” sounds might respond to bats. He was already studying the high-frequency sounds of grasshoppers, with a biology student, Vincent Dethier, to help him identify them.

Once I worked up the courage to knock on his door, I found Pierce a jolly fellow whose apparatus clicked and rattled delightfully whenever my bats were at all active. They were emitting definite sounds well above the range of human hearing, but we had difficulty detecting any of these sounds when they were flying around the room. We were therefore appropriately cautious about concluding that these sounds were used for orientation (Pierce and Griffin, 1938). As described elsewhere (Griffin, 1958, 1980) when I returned to studying bats with fellow student Robert Galambos we found that the initial difficulty had been that both the bats’ emission of sounds and the sensitivity of Pierce’s apparatus were quite directional, and that we had to aim the apparatus straight at an approaching bat to reliably detect these sounds.

During my senior year I decided it was time to branch out and take up something new as I started graduate work, looking forward hopefully to some sort of academic career. The navigation of birds struck me as a suitable thesis problem, but some of my elders and betters advised that if I really hoped to become a serious scientist I should put aside such childish interests in favor of some important subject such as physiology. I was saved from this dilemma when Karl Lashley came to Harvard as a member of both biology and psychology departments. I had read the classic paper by Watson and Lashley (1915) on the homing of terns, and persuaded him to accept me as a biology graduate student to study the homing of locally available species. Lashley stipulated that I take a couple of courses in psychology with Clifford Morgan and S. S. Stevens, and I even talked E. G. Boring into letting me audit his proseminar for first year graduate students.

The key question I hoped to answer was whether birds displaced into unfamiliar territory could determine the homeward direction and proceed directly back to their nests. In the summer of 1938 I selected Leach’s petrels as a suitable species, partly because a fellow graduate student, William Gross, had been studying them at the Bowdoin College field station on Kent Island at the mouth of the Bay of Fundy. These pelagic seabirds spend about 4 days with their eggs and young in burrows on islands free of ground predators while the mate spends the same time feeding at sea. Each homing experiment entailed catching 20 or 30 petrels and transporting them in covered cages to distant release points. For releases well out in the ocean the cages were taken by launch and auto to Halifax and left with the deck officer of a freighter who released them en route to the West Indies. Many homed from distances as great as 470 miles, but their speed of return was not especially impressive. Either they might have been well oriented but spent considerable time in feeding, or perhaps they flew in some sort of search pattern that brought them to a familiar coastline (Griffin, 1940a).

In 1939–1941 I therefore turned to herring gulls and common terns nesting on Penikese Island not far from Woods Hole, and both species returned reasonably well from release points several hundred miles along the coast or inland. The speed and percentage returns were slightly better from the southwest where the bird might have encountered landmarks that were familiar from their seasonal migrations. But as with the petrels, the results were consistent with a “nothing but” interpretation that in unfamiliar territory birds either flew off more or less randomly or searched in some systematic pattern until they found familiar landmarks. To distinguish between these two possibilities I obviously had to learn where they actually flew. As we cast about for possible methods to accomplish this, Lashley suggested feeding the birds poison capsules so that after a predetermined time they would drop from the sky and, he thought, be observed and their location reported. I diplomatically refrained from following that advice, but I did seriously consider radio tracking, only to find that the smallest available transmitter was much too heavy for a herring gull to carry (Griffin, 1963).

It was Alexander Forbes, the physiologist, yachtsman, pioneer aviator, and explorer of Laborador, who encouraged the alternative of following herring gulls from a light airplane. Although nothing could have been farther from any of my previous experience or aspirations, Forbes’ enthusiasm was irresistible. We first tried releasing a gull from the plane: “Wait ‘til I pull the plane up into a stall, then you open the door, Griffin, and throw the gull down as hard as you can, so it’ll miss the horizontal stabilizer.” A nice idea at the time, except that the open door acted as right rudder and put the plane into a spin. After that we asked someone at the airport to watch our plane and release a gull when it was rocked back and forth conspicuously. It proved feasible to keep a white gull in view while circling one or two thousand feet above it, and in 1941 I bought a 6-year-old plane and followed several gulls as they started home. Once more it seemed that when released inland in presumably unfamiliar territory herring gulls did not head directly toward home, even though most of them did eventually find their way back to their nests on Penikese Island (Griffin, 1943).

During the summer of 1939 I was lucky to be awarded a fellowship (probably on the recommendation of W. J. Hamilton) to work at the newly established E. N. Huyck Preserve in Rensselaerville, southwest of Albany. After homing experiments with gulls and terns in May and June I returned to banding bats and repeated and extended the obstacle avoidance experiments that Hahn had carried out at Indiana University more than 30 years earlier (Hahn, 1908). The agility with which bats dodged 1-mm wires even when blindfolded was most impressive; I experimented with various types of ear plugs and confirmed the disorientation of bats with impaired hearing. On returning to Harvard in the fall I found that Galambos had succeeded in recording cochlear microphonics from bats at frequencies up to 90 kHz. I have described elsewhere the development of our joint experiments (Griffin and Galambos, 1941; Griffin, 1958, 1980), and Galambos has also published his recollections of our experiments (Galambos, 1995, 1996; see also Grinnell, 1980). He was far more of a physiologist, and without his critical ideas I would very likely never have worked out such conclusive experiments showing that bats avoid obstacles by echolocation. On the other hand I was the one who knew bats, and our collaboration was intense and fruitful. We kept to our original plan that his Ph.D. thesis would be on the hearing of bats and mine on the homing of birds.

After Pearl Harbor I was fortunate to be employed in applied wartime research at Harvard in S. S. Stevens’ Psychoacoustic Laboratory where I found it exhilarating to plunge directly into practical efforts to improve voice communication systems used in noisy military tanks and aircraft. Orders conveyed by radio were often so garbled that a pilot could not tell where he should fly to return to his carrier. The equipment then in use had been developed 20 years earlier for dot–dash telegraphy with a sharp peak at about 1 kHz which became painfully loud or even damaging to the ears when the gain was turned up. After laborious tests in a variety of noise fields we proved to everyone’s satisfaction that one really could hear better in noise with a broad-band system. This now seems obvious, but in 1942 it appeared to be long-haired theorizing.

After several months at the Harvard Fatigue Laboratory testing equipment and developing improved gear for soldiers and airmen forced to live and fight under adverse climatic conditions, I was glad to join George Wald and Ruth Hubbard in a project sponsored by the U. S. Army Engineers. Still secret night vision devices converted infrared light into an image that allowed soldiers to see and shoot the enemy in total darkness. The only catch was that despite everything in the textbooks, the intended victims could see a dark red glow from the infrared searchlight. Working with filters that had to be locked away in a safe after each experiment, we measured the human threshold in the near infrared. At 1000 nm one could feel a slight warming of the skin at the visual threshold (Griffin et al., 1947).

When I participated in competitive efforts to sell one of the Armed Forces on our conclusions, or on the virtues of a device we were recommending, it was instructive to see how the formal structure of scientific tests could be manipulated to achieve any of a wide range of outcomes, according to the preference of the advocate. Yet in my firsthand experience the Armed Services eventually reached reasonable decisions, although they often needed a great deal of persuasion. Much of this applied wartime “research” consisted of gathering evidence that would convince officials of relative simple matters of scientific fact that were obvious very quickly once one studied the matter sensibly.

Six months resumption of my junior fellowship in the first half of 1946 provided a fine opportunity to apply to bats what I had learned about acoustics with S. S. Stevens and especially from Francis Wiener of L. L. Beranek’s Physical Acoustics Laboratory. He loaned me a 640AA condenser microphone, which at the time was by far the best available to record sounds above the frequency range of human hearing. The cathode ray oscilloscope showed at a glance that the sounds emitted by bats were even briefer in duration than Pierce’s apparatus had revealed; rather than being broadband noise bursts, they were frequency modulated chirps sweeping downward by an octave during 1 or 2 msec (Griffin, 1946, 1950, 1958).

Having been at Harvard for 12 years it was obvious that I should move out into the real (non-Harvard) world. I knew some of the biologists at Cornell, including William Wimsatt who was then teaching anatomy at the Harvard Medical School. I let Bill know that I would be delighted to become Cornell’s comparative physiologist. Howard Adelmann was building up a department of Zoology, and his screening included asking me to prepare outlines of three courses in vertebrate, invertebrate, and general physiology. Brought up to believe that physiology was one subject that was best not divided along phylogenetic lines, I managed to persuade him that I should give one full course in comparative physiology, and a seminar on cellular physiology.

I am deeply appreciative of Adelman’s vigorous support even when it was not at all what he had probably anticipated. He was a true scholar, and although I strongly disagreed with his political opinions, he was a tower of intellectual strength. His own work in experimental embryology had included two years with Spemann in Germany, but had shifted to intensive analyses of the history of embryology and anatomy that led to his monumental books on Vesalius and Malphigi. It seemed at times that I was the only colleague who was willing to listen patiently to endless monologues about the problems of truly accurate translation.

In the present period when talented scientists are so much more numerous than suitable positions, I am somewhat embarrassed to recall my extreme good fortune when, during the summer of 1947, the University of Rochester offered to make me a full professor and chairman of its biology department. I was, and still am, flabbergasted that a good university would offer me such a responsible position after only one year as an assistant professor. Nothing appealed to me less than academic administration, but with two small children I could not afford to turn down such an offer. Fortunately for me, and I think also for the University of Rochester, Adelmann was able to twist whatever dean’s arms were necessary and I was promoted to tenured associate professor. Although I did not realize it at the time, this episode reflected the beginning of an exponential growth phase in academic science.

I was delighted to find a Cornell graduate student, W. C. Curtis, son of a plant physiologist, ready to work with me. He began by measuring the ability of bats to avoid wires of various sizes, showing better than chance avoidance even with wires 0.26 mm in diameter. Although Galambos and I had at first thought that bats could scarcely use their vision at all since plugging the ears made them so helpless, Curtis confirmed and extended the published work of Eisentraut showing that they did indeed have at least rudimentary pattern vision. We also wondered whether owls might use echolocation, but Curtis found that although barn owls could avoid obstacles in very dim light, they were disoriented in total darkness.

During the war years I had worked out detailed plans for improved homing experiments that I hoped would clarify the sensory basis of bird navigation. The gannets nesting on Bonaventure Island in the Gulf of St. Lawrence seemed ideal because they are large and white and thus easily followed from the air. Furthermore they are strictly pelagic and normally do not fly far from the ocean, so that inland release points would certainly be unfamiliar territory. But research support adequate for rental of a suitable airplane was unheard of. Then suddenly I learned from Laurence Irving and Pete Scholander at Swarthmore College that, mirabile dictu, the federal government was still supporting research projects, even though the war had ended. There was now an agency called the Office of Naval Research ready to award research contracts at a biological research station at Point Barrow, Alaska. Even more astonishing was that they did not really care what one studied, provided it was in arctic Alaska. What I really wanted to do was follow homing gannets over New Brunswick and Maine, but of course there were interesting birds nesting on the north coast of Alaska, including large white species such as snow geese and swans. So my proposal to the ONR explained that in order to study the homing of snow geese and swans in Alaska I had first to develop and perfect the method of airplane following, which could be accomplished more effectively with gannets from Bonaventure Island in 1947, to be followed by similar studies in Alaska in 1948.

A Cornell graduate student, Ray Hock, and his wife, Ann, helped me catch gannets nesting at the top of cliffs on Bonaventure Island, and we transported them by local boat and Navy jeep to Caribou, Maine. With a three-place Piper Super Cruiser fitted with an extra fuel tank in place of the third passenger I managed to follow gannets for as long as 10 hours. Most of them did return to their nests, but their flight paths deviated greatly from a straight line between Caribou and Bonaventure Island (Griffin and Hock, 1949; Griffin, 1964).

These airplane observations, together with a thorough analysis of all the data then available, persuaded me that almost all bird homing could be accounted for without assuming that the birds could choose the correct homeward direction when released in unfamiliar territory (Griffin, 1944, 1952). This conclusion, which in retrospect seems so narrowly overconservative, was very much in keeping with the basic ideas on which I had been brought up at Harvard in the 1930s. Everything that animals did was to be explained in the simplest possible terms; Jacques Loeb or Frankel and Gunn (1961) were models to be emulated. For example, when I used to discuss the problems of bird navigation with my student friends one farfetched idea we played with was that the birds might conceivably use the sun or stars for directional guidance. But this was outrageous speculation, and a typical response was to ridicule the notion that a bird might carry around in its head a nautical almanac to determine the appropriate direction for migration or homing from the constantly changing azimuth of the sun or a star. The possibility that birds might distinguish Polaris from other stars was so outlandish that I don’t think anyone even dared to mention it.

The English physicist Wilkinson (1952) likened homing birds to gas molecules, and his equations could be made to fit reasonably well with the data then available on homing performance—including my airplane observations. Yet small nagging doubts remained, for some reports of homing pigeons, and especially Lack and Lockley’s experiments with Manx Shearwaters, were difficult to reconcile with this “nothing but” explanation that seemed most reasonable and appropriate.

Only a few years later Matthews (1968) in England and Kramer (1961) in Germany demonstrated that well-trained homing pigeons really do show much better than random homeward orientation within a few minutes after release in unfamiliar territory. In 1948 an even more startling development shook up my whole scientific viewpoint when I first heard of Karl von Frisch’s experiments on the waggle dances of honeybees. At first I was incredulous, even though his earlier work on color vision in bees and hearing of fishes was well known and highly regarded. Good God, if mere insects communicate abstract information about distance and direction, where does that leave Loebean tropisms? If bees do something like that, how can I be so sure that homing birds simply search for familiar landmarks?

I lost no time in setting up my own observation hive, with help from Cornell apiculturists, and saw for myself the striking correlation between the pattern of the waggle dances and the distance and direction to the food source. I even managed to work it into the laboratory of my comparative physiology course as an “unknown.” The students first estimated from the dances where the bees were informing their sisters that food was located, and then they checked to see where marked bees were gathering concentrated sucrose solution from artificial feeders. I was so fascinated by this revolutionary discovery that I helped arrange for von Frisch and his wife to visit the United States for a series of lectures. They flew from Graz in the Austrian province of Styria, passing through Vienna, which was still occupied by the Russians, and on to Frankfurt where they watched in amazement the almost continuous shuttle flights of American planes to blockaded West Berlin. In Ithaca they charmed everyone, and the only problem was that when they wanted to walk through the countryside almost every motorist stopped to help these elderly people with their walking sticks. It was a nuisance to explain to driver after driver that they really liked to walk.

One of the requirements of the lecture series at Cornell was that the Cornell University Press should have the option of publishing von Frisch’s lectures. He readily agreed, and within a few weeks I received a manuscript describing the same marvelous material he had presented in his lectures. But it was typed single-spaced on thin paper with strike-overs and a very few places where German word order prevailed over English usage. In my youthful innocence I did not realize that a university press would have its evaluation affected by such mechanical details. I became increasingly puzzled when several weeks went by without any response from the press, especially since I was fending off fervent pleas from other university presses to let them see the manuscript. Finally I was told that there was great doubt that the manuscript was publishable at all, but that one of their readers was revising it into acceptable form. Adelmann and I were outraged when we learned that an elderly professor of apiculture had indeed rewritten the first chapter to read like a Department of Agriculture bulletin, even inserting long paragraphs on his own experiments dealing with the amount of hay that should be piled around beehives to enable bees to survive the winter.

Seeking independent opinions I circulated samples of von Frisch’s original and the proposed revisions to colleagues in other departments. The philosopher Max Black supported me fully, and Mike Abrams, Professor of English, asked if he might please use my samples in his freshman English class—von Frisch’s passages as models, and the revisions as horrible examples of what to avoid. In the end Adelmann and I won our battle and Cornell University Press did publish Bees, Their Vision, Chemical Senses and Language (von Frisch, 1950) which was of course a great success, and is still in print. But I was so ashamed that I never told von Frisch about the whole affair.

By 1951 I had returned to further experiments on bat echolocation. It seemed appropriate to investigate whether they could discriminate between different objects. Thinking that a bat would do its best to avoid obstacles that blocked its escape path, an interested student and I built various types of boxes with an entrance hole in the middle of one wall, so that a bat released there would have a choice of escaping by flying right or left toward two identical openings leading out into a large flight chamber. We reasoned that if one of these two flight paths was obstructed the bat would of course choose the unencumbered passageway, and that having established this we could then go on to set up different obstacles at the two ends of the box and learn whether the bat could distinguish those offering the best escape route. But the bats (Myotis lucifugus) frustrated us at every turn. Either they developed position habits, always flying to the right or left regardless of the obstacles, or they flew toward the cluttered opening instead of the open one.

In late August, in what I thought of as a last ditch effort to salvage something from a summer’s work, I took my apparatus for the first time out of doors where bats were pursuing flying insects. I had no reason to think that this would lead to anything interesting, but having watched bats (Eptesicus fuscus) hunting over a small pond near the Cornell campus, I wondered whether their orientation sounds might be different from those I had been recording in the laboratory. At that time the best way I could record bat sounds was to photograph their waveforms displayed on a cathode ray oscilloscope, using an ancient 35-mm motion picture camera modified so that the film moved continuously. Because most of my apparatus required AC power I had to use a gasoline engine-driven generator to power the station wagon full of gear. The long, deep parabolic horn around the 640AA condenser microphone was the only piece of apparatus left over from Pierce’s supersonic detector of the 1930s. Because it was impossible to aim the parabola at a bat flying 50 feet above the pond and at the same time watch the oscilloscope, I threw together a crude audible detector by feeding the ultrasonic signal into the second detector stage of a portable radio.

The results were unexpectedly spectacular (Griffin, 1953a, 1958). Although Galambos and I had learned a decade earlier that bats increase the repetition rate of their orientation sounds when approaching obstacles, the increases in pulse rate during insect pursuit were very much greater. The “put-put-put” from the portable radio as a bat approached speeded up as it closed in on a moth or beetle to a buzz of up to 200 pulses per second. Neither I nor anyone else had previously suspected that bats might catch small flying insects by echolocation. We had always thought of echolocation as a collision warning system, and it seemed out of the question that small insects could return strong enough echoes to be audible to a rapidly moving bat. It is difficult now to realize how great a shift in viewpoint was necessitated by this evidence that bats use echolocation to locate and intercept small moving targets. Echolocation of stationary obstacles had seemed remarkable enough, but our scientific imaginations had simply failed to consider, even speculatively, this other possibility.

Yet my evidence from field observations was not entirely conclusive. For instance, one critic suggested that the increase in repetition rate was analogous to the faster yelps of his dog in hot pursuit of a rabbit. Final resolution of this question had to wait another decade when collaborative experiments with Frederic Webster in Cambridge showed that echolocation really was used at least by some insectivorous bats in their efficient capture of small flying insects in the dark (Griffin et al., 1960).

Having come to realize that bat echolocation was a highly versatile mode of perception, it was natural for a zoologist to wonder whether it might differ among the many groups of bats. It was difficult to convince some of my colleagues that this was a significant question. One expert in hearing, Nobel laureate Georg von Bekesy, told me it would be a waste of time to examine those queer-looking bats from the tropics: a bat is a bat, those sounds are simply noise bursts, and nothing more is likely to be learned from comparative studies of echolocation. But F. P. Moehres had already discovered that the horseshoe bats use a very different type of echolocation than the bats we had studied, and Harold Trapido at the Gorgas Laboratory in Panama persuaded me after rather extensive correspondence to dispatch 20 packing cases of apparatus by air freight to Panama; he showed me where to catch several species of bats with habits very different than those previously studied in North America and Europe.

The first of my two months in Panama was spent tracking the air freight shipment which had gone astray, but when it finally arrived I was able to learn very quickly that orientation sounds and echolocation differed greatly in bats that fed on insects, fruit, fish, or blood of large animals. The most striking result was that I could not detect any orientation sounds at all from most of the small neotropical fruit-eating bats such as the very common Carollia perspicillata, though they collided with obstacles when their ears were plugged; I was for a time back with Spallanzani and Jurine: hearing was necessary for obstacle avoidance but the bats seemed to fly silently. It turned out that the problem was microphone sensitivity and much lower emitted intensities. When Alvin Novick returned to Panama a year later with the newly developed plastic diaphram electrostatic microphones he could detect at least faint orientation sounds from all the neotropical bats. These initial studies in Panama in 1953 and 1954 opened up a whole new truly comparative vista of echolocation adapted to a variety of feeding habits (Griffin and Novick, 1955).

My first sortie to the tropics in 1953 was also enlivened by William and Katherine Phelps of Caracas who invited me to accompany them to the Cave of the Guacharos near Caripe where Humboldt had eloquently described how the oilbirds nest in totally dark caves. We were able to show by simple field experiments that they employ a crude form of echolocation using audible clicks (Griffin, 1953b).

In 1953 I was invited to return to the Harvard biology department, with the primary obligation of teaching introductory zoology. I approached this with considerable trepidation, and I am afraid did only moderately well at elementary teaching. But the stimulating environment and superior facilities available at Harvard did permit better research work than I would have been able to accomplish at Cornell. I also managed to avoid the bitter political problems that wracked the Cornell zoology group during the late 1950s.

I and several Harvard students continued to investigate bats’ use of echolocation for insect catching, taking better and better, and bulkier and bulkier, electronic equipment to field sites where bats were actually doing their insect hunting. No such equipment was then available with battery power, so that we either relied on portable generators or persuaded neighbors to let us plug in a long extension cord. Sixteen-millimeter sound movies showed the position of a flying bat and the sound track measured the timing of their ultrasonic orientation sounds “translated” into audible clicks by crude ancestors of modern bat detectors. The big brown bat, E. fuscus, was the species I usually studied, but once a rare opportunity arose when migratory red bats, Lasiurus borealis, were actively chasing beetles over a miniature golf course in Falmouth, Massachusetts. The owner was most reluctant to allow us to wander through his premises trailing a long cable leading from microphone and parabolic reflector back to a truck full of equipment powered via an extension cord connected to one of his power outlets. But it was a unique opportunity, and we finally persuaded him to allow us to record bats over his golf course, provided that we did not tell his clients what we were doing. This required considerable diplomacy, especially when a serviceman from Otis Air Force base loudly explained to all within earshot that we must be studying radio waves from the ionosphere, even though some skeptical listeners kept asking “But why do they always point that thing at those bats?”

Neurophysiology of brain mechanisms of bat echolocation began when Alan Grinnell first exposed the dorsal surface of the brain of an M. lucifugus under nembutal anaesthesia and placed a simple wire electrode of the surface of the inferior colliculus. The beautiful evoked potentials so easily recorded formed the basic of his extensive studies of the neurophysiology of bat echolocation (Grinnell, 1963). These studies were extended later by Nobuo Suga and several others, so that in many ways the neural bases of auditory discriminations in bat brains are better understood than those of any other nonhuman animal, as recently reviewed by Suga (1994) and in several chapters of the book edited by Popper and Fay (1995).

The idea that bats use echolocation to locate and capture small flying insects still seemed rather radical, but my efforts to test it experimentally were stymied for many years because I could not persuade captive bats to catch flying insects. This bottleneck was broken by an entomologist, Eric Tetens-Nielsen, who invited me to bring bats to his laboratory in Vero Beach, Florida where he had a flight chamber filled with hundreds of mosquitoes. So I flew to Florida with some freshly caught M. lucifugus in a modified briefcase and as soon as they were released in Tetens-Nielsen’s flight chamber some began to catch numerous mosquitoes with the same rapid increase in pulse repetition rate that had first indicated use of echolocation for prey capture.

The next step was to set up a similar flight chamber at Harvard where I could record the bats’ sounds much more accurately and take sound movies to show the spatial relations between bat and insect along with the temporal pattern of ultrasonic sounds. We quickly switched from mosquitoes to fruit flies reared in oversized versions of the standard bottles used by geneticists.

Frederic Webster began a fruitful collaboration which included conversion of a Quonset hut he had erected in his backyard to house a trampoline into a larger bat flight chamber than the low ceilings of the Biological Laboratories could provide. Here we could, at last, elicit active insect hunting by M. lucifugus under controlled conditions. Although vision seemed most unlikely to guide insect hunting bats, a first step was to study insect catching in total darkness. The orientation sounds were similar, but how could we tell whether the bats were really catching fruit flies in total darkness? Because there was no way bats could gain weight in our flight chamber except by catching fruit flies, weighing them before and after a short period of insect catching in darkness finally demonstrated, conservatively, that some bats caught a fruit fly every few seconds (Griffin et al., 1960).

Another alternative to echolocation was that bats located flying insects by passive listening to sounds of their wingbeats. These were very faint, audible only if the fruit fly was almost inside one’s ear canal, and the great increase in the bat’s own sounds seemed inconsistent with listening for faint wingbeat sounds from Drosophila. But it was a distinct possibility that required serious consideration. We therefore subjected our insectcatching bats to loud sounds of both audible and ultrasonic frequencies. In broad-band audio frequency noise that was enormously louder than the flight sounds of fruit flies the bats continued to gain weight as fast as under quiet conditions. But when we played ultrasonic noises they landed on the wall and refused to continue insect hunting.

Under some conditions large numbers of bats fly close to one another in caves, especially when emerging in the evening. Listening with a bat detector to the bedlam of ultrasonic sounds leads one to wonder why the innumerable pulses from dozens of bats within a few meters of each other do not interfere with their echolocation. Yet they do not collide with obstacles, or with each other (although they do not need to intercept flying insects). This led to experiments in which we tried to measure how resistant bats were to jamming. They dodged wires successfully in noises loud enough that we had difficulty detecting their emitted sounds, which were of course much more intense than echoes from 1-mm wires. Our first experiments were limited because we could not be sure that the available loudspeakers generated all frequencies, including harmonics, of the bats’ orientation sounds.

The possibility that bats had some way to overcome jamming intrigued colleagues at the MIT Lincoln Laboratory enough to justify their generous collaboration, which included developing transistorized bat detectors to replace my clumsy modified radio receiver. They also loaned us greatly superior electronic apparatus to improve our studies of bat “radar.” The principal collaborator was J. J. G. McCue who worked with us extensively on bat echolocation for several years.

Having constructed a much improved noise field with multiple loudspeakers radiating broad-band ultrasonic noise from both ends of our flight chamber, we turned to a long-eared bat. Corynorhinus townsendii from caves in West Virginia, because they emit lower-intensity orientation sounds that we could match more adequately with our battery of loudspeakers. We persuaded them to fly back and forth through four rows of vertical wires, facing one of the arrays of loudspeakers at each end of the flight space, while we recorded their orientation sounds and their flight paths. The loudest noise we could deliver barely prevented them from successfully avoiding the wires.

If one naively treated the air between the bat and the wire obstacle as a single communication channel, the bats appeared to exceed the theoretical limits for detection of signals in noise predicted by information theory. That sounded exciting, and helped elicit the magnificent cooperation from the Lincoln Laboratory. But bats have two ears, and close analysis of our data showed how they could appear to be defying information theory. When the noise was really difficult they changed their flight paths. Instead of flying straight from end to end of the flight chamber with minor deviations to dodge wires, they began ziz-zag flight that approached the wires obliquely. This meant that echoes from the wires reached their ears at considerably different directions from the jamming noise. Figuratively speaking, the bats were using two-point interferometry. Grinnell also showed that evoked potentials could be elicited from bat brains in our jamming noise if the noise and signals comparable to echoes from the wires arrived from different directions (Griffin et al., 1963). I have always found these experiments quite intriguing, but when I presented a paper on bats’ resistance to jamming at a meeting of the American Physiological Society, the audience turned out to number zero. Nor are these experiments mentioned in recent reviews of bat hearing and auditory discrimination.

Initially it had been a real surprise that bats used echoes from their ultrasonic sounds to avoid obstacles. Then, this sort of collision avoidance was extended by the recognition that they catch their insect prey by echolocation. But could they distinguish between different objects that returned echoes of their orinatation sounds? They chase inedible pebbles tossed into the air, suggesting that they can’t tell them from flying insects. Yet no one had reported bats chasing fallen leaves or raindrops, so that this was an open question. It seemed reasonable to infer that they must have some ability to detect differences in size of sonar target, but Webster was proud to display a flash photograph of a bat grasping a tennis ball between its wings. Perhaps bat sonar is an all-or-nothing affair and they simply turn toward and attack anything that returns echoes.

To study the possibility of discrimination between different sonar targets, we tossed mealworms into the air just in front of approaching bats, and several M. lucifugus learned to catch these unnatural but tasty “flying” insects. When a bat had become adept at catching tossed mealworms, we began tossing up pebbles, metal spheres, and other inedible objects of roughly the same size. At first the bats attacked almost anything from BB shot to tennis balls, but after a few days some individuals began to be more selective and turn away without touching the inedible junk while still catching most of the mealworms. We presented them with spheres of different diameters, and those closest in size to mealworms were more difficult, but in time even these were rejected while real mealworms continued to be captured. This indicated something more than simple discrimination based on amplitude of echoes.

We therefore turned to disks, and in our best experiments randomly interspersed two sizes of disk between mealworms, one estimated to generate lower, the other higher amplitude of echoes. But both mealworm and disk echoes vary 100- to 1000-fold in amplitude depending on the angle at which sound waves strike them, so that this disk versus mealworm discrimination seemed appropriately challenging for our bats. After several days of practice a few individual M. lucifugus did learn to make this discrimination quite well, catching 80 to 90% of the mealworms, and turning away from the majority of the disks. This was impressive because measuring amplitudes of the echoes of the disks and mealworms that returned from a variety of directions showed almost complete overlap in power spectrum levels. It seemed clear that bats could not achieve this discrimination simply by learning that one sort of echo power spectrum meant a tasty mealworm and others meant a hard chunk of plastic (Griffin et al., 1965). James Simmons and his colleagues have recently proposed that bats detect the temporal patterns of echo maxima over intervals of much less than 1 µsec (reviewed by Simmons, 1989).

In 1965 discussions with Fairfield Osborn, president of the New York Zoological Society, and Detlev Bronk, president of The Rockefeller University, led to the opportunity for me to organize a research program in ethology sponsored jointly by the two institutions. I am proud to have facilitated in this way the outstanding investigations of Peter Marler, Fernando Nottebohm, and many of our younger colleagues. In 1970 I nearly dropped the telephone from my ear on hearing Frank Stubbs, a trustee of the Mary Flagler Cary Charitable Trust of Millbrook, New York inquire whether we might like to establish a field station there, which we were of course delighted to do.

Once the collaborative arrangements at Rockefeller University and the New York Zoological Society had been established, I set up a wind tunnel large enough for small birds and bats to fly for long periods where we could observe their behavior. Among other experiments Jose Torre-Bueno found that some individual starlings could be induced to fly steadily for hours while their body temperature and heart rate was measured by trailing wires. He later continued these investigations in Vance Tucker’s laboratory at Duke where he built a closed-circuit wind tunnel that was sealed tightly enough to function as a respirometer. Previous measurements had indicated that flying birds, like fixed-wing aircraft, have a minimum energy expenditure at some “optimal” flight speed, with marked increases when flying faster or slower. But to every one’s surprise, when starlings flew at various speeds in this apparatus their metabolic rate did not vary appreciably (Torre-Bueno and Larochelle, 1978). Starlings, and probably other birds, change their wing and body shapes to maintain efficient flight over a wide range of speeds. Once again living organisms turned out to be more efficiently complex than we had believed possible.

The sensory basis of bird navigation continues to challenge scienific explanation. One aspect of the bird navigation problem is the question of whether birds can maintain an appropriate direction of migratory flight when “flying blind” in or between layers of opaque cloud that prevent them from seeing either the stars or the ground. Previous radar observation had suggested that migrants do this, but I wished to gather more definitive data that would show just how accurately migrating birds could maintain an appropriate course when one could be sure they were in fact flying blind. With the collaboration of Larry Eisenberg of the Rockefeller University Electronics Laboratory we adapted for radar bird watching a Korean War surplus fire control tracking radar. This massive assembly of vacuum tubes and elegant machinery could track individual birds, and even insects, at ranges of a few miles. After Ronald Larkin adapted a digital computer to analyze the continuous stream of data on a target’s azimuth, elevation, and range, we could plot in three dimensions the flight paths of individual birds with an accuracy of a meter or less, even when they were flying several hundred meters over our heads. When operating this apparatus I felt I was a bat.

On nights when ground observations and meteorological data on cloud heights were available our bird-watching radar sometimes showed a few migrants flying straight and level in seasonally appropriate directions even when they must have been flying blind (Griffin, 1973), but the density of migrants was much lower under these conditions. Apparently most birds avoid flying blind, but some at least are able to do so. How they manage to do this remains an unsolved scientific question. We also took our bird watching radar to sea, thanks to an invitation from John Teal of the Woods Hole Ocanographic Institution, and tracked numerous migrating birds and insects over the western North Atlantic. The resulting data, combined with radar tracking of free balloons to measure wind velocities where we tracked birds and insects, showed that birds must fly for at least two or three days to migrate from New England to the Caribbean, and some insects must have maintained powered flight for many days to reach the places where our radar tracked them (Larkin et al., 1979; Larkin, 1991).

One popular theory is that migrating birds are sufficiently sensitive to the earth’s magnetic field to orient their flight by some equivalent of a magnetic compass. The positive evidence consists almost entirely of weak statistical effects of earth strength fields on orientation of birds fluttering in small cages. All efforts to locate a sensory or neural mechanism that would allow such magnetic sensitivity, or to condition birds to earth strength magnetic stimuli, had then and have still led to negative results. TorreBueno and Larkin tested the possibility that previous negative results might be explained by assuming that birds would respond to earth strength fields only during actual flight. They tried to condition starlings to fly on one side or the other of the wind tunnel according to the direction of a magnetic field generated by appropriate coils. But once again the birds showed no sign of any magnetic sensitivity. This problem remains an exciting scientific challenge.

Another Rockefeller graduate student, James Gould, brought me back to the communicative dances of honeybees discovered by Karl von Frisch, which had so challenged my reductionist attitudes in the late 1940s. In the meantime Adrian Wenner and his colleagues had challenged von Frisch’s interpretation of the dances by claiming that other bees do not use the information about direction and distance, which everyone agreed was contained in the orientation and duration of the waggle dance, but simply search for odors of flowers brought back by the dancer (reviewed by Wenner and Wells, 1990). It is impracticable to follow the actual flight paths of bees over hundreds of meters, which would be one way to resolve this uncertainty. Instead Gould devised an ingenious experiment by which he could cause dancing bees to orient the dances in a direction that was very different from the direction the dancer had actually flown to reach a scented food source. The great majority of the recruits that followed these dances searched in the direction indicated by the experimentally shifted dances rather than flying to where the dancer had actually filled her stomach with concentrated sugar solution (Gould, 1976). Von Frisch’s interpretation has since been supported even more convincingly by Michelsen et al. (1992) who developed a model honeybee that caused recruits to fly in an experimentally determined direction without providing any goal-related odors.

Maturing scientists often experience what might be called the “philosopause” as they turn to more general questions than those that have occupied their attention for many years of detailed investigation. Mine has involved a growing dissatisfaction with the reductionistic viewpoints so prevalent in biology and psychology. In particular, I had begun to doubt the wisdom of totally ignoring the possibility that animals may experience conscious thoughts and subjective feelings. This led me to attempt to launch a subdiscipline of cognitive ethology (Griffin, 1976, 1984, 1992). I feel that only limited progress has yet been achieved by the small but growing group of ethologists who are trying to learn what nonhuman animals actually think and feel, but I am optimistic that in due course new blood, new approaches, and new ideas will open up this field of scientific investigation. I have often wondered why it took me so long to speak out on this subject, and I believe the chief reason has been the positivistic climate of opinion at Harvard and elsewhere in the 1930s which led me and many other scientists to believe that only reductionist explanations were worthy of critical scientific acceptance. Many surprising discoveries and much shaking up of prior assumptions were necessary before I was ready to think seriously about animal consciousness. Hindsight is always easy, and I may simply be swimming with a changing tide in the history of ideas. But it does seem that firsthand involvement in surprising discoveries is what prepared me to shift my thinking into new and I hope fruitful channels.

Reopening questions about the private, subjective experiences of animals has aroused considerable opposition from some psychologists and ethologists. One of my books (Griffin, 1984) has been called “The Satanic Verses of Animal Cognition.” Most psychologists have long since abandoned the strict behaviorism of Watson and Skinner in favor of a cognitive psychology, and there has even been a small movement in behavioral ecology and ethology to consider animal cognition. Yet almost all of the scientists who study animal cognition continue adamantly to avoid any serious consideration of what life may be like to the animals themselves. Thus animal cognition has become respectable, but animal consciousness remains forbidden territory, primarily because scientists see no way to gather objective, independently verifiable data about it. As Latto (1986) put it: “Sadly for those of us who agree that (studying conscious, subjective experiences of animals) would be a desirable goal, there is no evidence that it is anything but unattainable.”

Yet we are obviously conscious, and we make useful and significant, though incomplete and imperfect, inferences about the private thoughts and feelings of our human companions. We do this by observing their behavior, especially their communicative behavior, verbal and nonverbal. But we have been brought up to assume that we cannot do this with other species because they do not talk about their private experiences, if such exist. In 1974 it suddenly occurred to me that what ethologists have learned about animal communication opens up an important scientific opportunity. Many animals communicate extensively, and at least some of the messages they exchange may well be expressions of simple conscious thoughts. Insofar as this is the case, animal communication provides objective, verifiable data about what animals are thinking and feeling.

This suggestion that animal communication can provide scientists with a significant though imperfect “window” on animal thoughts and feelings has been a “lead balloon” as far as most of my colleagues are concerned. They feel that animals communicate unconsciously, or, more conservatively, that there is no way we can tell whether any of their communicative behavior conveys even the simplest conscious experiences. But it seems to me that our scientific aspirations in this area are still needlessly inhibited by vestiges of behaviorism that linger on as a sort of “mentophobia.” Furthermore, many other types of evidence suggest that animals are quite capable of simple perceptual consciousness. These include versatile adjustments of behavior to cope with newly arisen challenges, together with the growing evidence from neurophysiology that all central nervous systems operate on the same basic principles. The aversion to any recognition of animal consciousness has led many behavioral scientists to discredit all such suggestions by exaggerating them into allegations that animals engage in thoughts rivaling the human level of complexity.

It has been pleasantly stimulating to become involved in a heated scientific controversy. The term cognitive ethology continues to be used even by some who are most critical of my ideas, apparently in the hope that animal cognition can be studied fruitfully even though animal consciousness remains taboo. Recognizing as clearly as my critics that studying subjective experiences in other species will be difficult, I continue to believe it is possible. One problem is that scientists who reject any possibility of progress in this area seem to require absolutely perfect proof of any statement about animal consciousness before recognizing the possibility that it may be open to scientific investigation. Yet such premature perfectionism would have seriously impeded scientific progress in attacking other difficult problems; it is difficult to understand why is it so fervently demanded in this case.

After my retirement from Rockefeller University, Harvard has generously appointed me an Associate of Zoology and allowed me to work at the Concord Field Station of the Museum of Comparative Zoology. In 1996–1997 I was even able to offer a tutorial seminar in cognitive ethology for Harvard undergraduates. Because I just love trying to solve scientific problems, and in particular trying to understand animals, along with discussions of animal consciousness I try in a limited way to study the endlessly and significantly fascinating behavior of real animals under natural conditions. Specifically, I am analyzing the role of near-field acoustic signals in the dance communication of honeybees, and seeking to understand the apparently purposeful behavior of beaver.

Acknowledgments

For permission to include in this chapter modified forms of material previously published, I thank the editors and publishers of Animal Sonar Systems edited by René-Guy Busnel and James F. Fish (Plenum Publishing Corporation, 1980) and Leaders in the Study of Animal Behavior edited by Donald A. Dewsbury (Bucknell University Press, 1985, and under the title Studying Animal Behavior: Autobiographies of the Founders by the University of Chicago Press, 1989).

Selected Bibliography

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Gould JL. The dance-language controversy. Q Rev Biol 1976;51:211–244.

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Griffin DR, Webster FA, Michael CR. The echolocation of flying insects by bats. Anim Behav 1960;8:141–154.

Griffin DR, McCue JJG, Grinnell AD. The resistance of bats to jamming. J Exp Zool. 1963;152:229–250.

Griffin DR, Hitchcock HB. Probable 24-year longevity records for Myotis lucifugus. J Mammal 1965;46:332.

Griffin DR, Friend JH, Webster FA. Target discrimination by the echolocation of bats. J Exp Zool 1965;158:155–168.

Griffin HF. The white cockade. New York: Greystone Press, 1941.

Griffin HF. Paradise street. New York: Appleton-Century, 1943.

Grinnell AD. The neurophysiology of audition in bats. J Physiol 1963;167:38–113.

Grinnell AD. Dedication. In: R-G. Busnel and JF Fish eds. Animal sonar systems. New York: Plenum, 1980.

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Larkin RP, Griffin DR, Torre-Bueno JR, Teal J. Radar observations of bird migration over the Western North Atlantic. Behav Ecol Sociobiol 1979;4:225–264.

Larkin RP. Flight speeds observed by radar, a correction: Slow “birds” are insects. Behav Ecol Sociobiol 1991;29:221–224.

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Torre-Bueno JR, Larochelle J. The metabolic cost of flight in unrestrained birds. J Exp Biol 1978;75:223–229.

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Wenner AM, Wells PH. Anatomy of a controversy: The question of “language” among bees. New York: Columbia University Press, 1990.

Wilkinson DH. The random element in bird “navigation.” J Exp Biol 1952;29: 532–560.

Roger Guillemin

BORN:

Dijon, France

January 11, 1924

EDUCATION:

Lycée Carnot, Dijon, B.A. (1941)

Lycée Carnot, Dijon, B.Sc. (1942)

Faculté de Médecine, Lyon, M.D. (1949)

Université de Montreal, Ph.D. (1953)

APPOINTMENTS:

Baylor College of Medicine (1953)

Salk Institute for Biological Studies (1970)

Whittier Institute for Diabetes and Endocrinology (1989)

Distinguished Research Professor, Salk Institute for Biological Studies (1997)

HONORS AND AWARDS:

National Academy of Sciences, U.S.A. (1974)

American Academy of Arts and Sciences (1976)

National Medal of Science, U.S.A. (1976)

Nobel Prize for Physiology or Medicine (1977)

Académie des Sciences, Institut de France (1980)

Légion d’Honneur, France (1983)

Roger Guillemin and his collaborators clarified the neuroendocrine control of the anterior pituitary gland by identifying a series of novel peptide molecules of hypothalamic origin. The same molecules were later found to have other functions in many parts of the central and peripheral nervous system, in the gastrointestinal tract, and more recently in the immune system.

Roger Guillemin

Childhood and Youth

I was born in Dijon, France, on January 11, 1924. My brother was born on May 4, 1927. That is the earliest of my long-term memories, as I remember vividly the beautiful bushes of Persian lilac in full bloom in the garden that surrounded the house where we were both born, that morning, when riding back home on my small red tricycle from the nearby house of my paternal grandparents, I was told that I had acquired a brother. My parents, our parents, were simple people with only a modicum of education. My mother had a junior high school education. Her parents were small farmers in the northern part of Burgundy, and my grandfather on that side had been, at times, a wine merchant. My father had completed a trade school education as a metal tool maker. He had read the French classics on his own and owned a small library, which became my first contact with books. He worked as a lathe operator in the nearby industrial plant that my paternal grandfather owned and operated and in which they were then manufacturing several types of riveting machines for which my grandfather had obtained some early patents. Later, my father changed jobs but always remained in this field of fine toolmaking, a trade that my brother later acquired formally. My father had a good voice as a lower baritone and sang in a men’s choir that became famous as part of a traditional guild society created in the 1930s during the recession years and which aimed at promoting the sale of the wines of Burgundy throughout the world. The “Chevaliers du Tastevin” is still a flourishing association. He also wrote poetry, some dealing with the wine songs of the guild. As an expression of a different part of his personality he was a referee of boxing matches; as a younger man he had been involved, like his father, in French boxing, also known as savate, or foot boxing. I never was interested in that sort of thing. Dijon had been the capital of the Duchy of Burgundy when the Dukes of Burgundy were more powerful than the fledgling King of France, owned all of the Flanders, and maintained a rich court life. The superb collections of Flemish and early Burgundy masters at the Musée des Beaux Arts go back to those days. Those paintings and the sculptures of Claus Sluter marked my younger years.

As a child, I always was interested in things dealing with science; for instance, botany—I knew hundreds of wild plants, which I collected in a large herbarium, quite a few wild mushrooms, which I collected and ate, of course; biology—the usual dissection of frogs et alia; electronics—radio crystal sets, transmitters (early one vacuum tube), ham radio, blowing of fuses not only in the house but even at the nearby electric pole, the resetting of which by the power company took care of all my piggy bank, etc. I was educated in the public schools in Dijon all the way through the two baccalaureates: in letters, the solid classic curriculum, including French literature, Latin for 5 years, Greek for 4 years, German for 5 years (a foreign language I learned to speak fluently), and in elementary mathematics (algebra, analytical geometry, elementary calculus). By that time, I was 18, and it was 1942. France had incredibly lost the war to Hitler’s panzer divisions in May 1940, and Dijon was in that part of France which the German army occupied since that date. But I had heard the call (l’appel) that General de Gaulle had broadcast from London on June 18, 1940. It was by listening to the programs in French from the British Broadcasting Corporation, though strictly forbidden by the Germans, that we knew how the war progressed. Those years of youth were awfully bleak and sad. Being fluent in German helped me out of a couple of brushes with the occupation army having to do with involvement in the Résistance, the underground movement, and when I received my marching orders from the local Kommandantur to proceed to some munitions plant in Bavaria as part of the forced civilian labor, I tore them apart and disappeared into the underground. I somehow managed to reach the Jura mountains near the town of Besançon, where, with some local friends, until the liberation in the fall of 1944 by the 5th American Army coming from the south of France, I ran a passage point to nearby Switzerland for all sorts of people fleeing the German army, the Gestapo, and the French milice of Vichy. Our cover was a camp of about 100 children moved by the Red Cross from the industrial suburbs of Paris, which were often bombed by the Allies. There were some tense encounters with exploring German patrols. The day the American tanks came up, there was a short skirmish with the rear guard of the German garrison; I was wounded by a piece of shell that scraped my skull, but far worse, one of the children of the camp was killed. I was back on my feet within a few weeks, though for years, small boils would erupt from the scar left by the shrapnel on my skull and scalp and small pieces of steel would come out. I still have the scar.

Medical School and Early Training

After the baccalaureates, I had hesitated between a career as an engineer, as I loved practical things, doing things with my hands, and a career in medicine. I entered medical school in Dijon in 1943. Late in 1944, I returned from the Jura mountains to Dijon, to continue my second year at the local medical school. I received the M.D. degree from the Faculté de Médecine of Lyon in 1949. The two schools were then administratively connected, with the larger school of Lyon granting the degrees. All my medical studies and training were totally clinically oriented, with 3 years of what we could call rotating internship. There was no laboratory facility of any sort in Dijon, except for gross anatomy—in which I was prosecteur, a teaching assistant, for 2 years. During these 5 years of medical studies, I had become interested in endocrinology, probably because two of my best teachers of clinical medicine, P. Etienne-Martin and Jacques Charpy, were themselves interested in what were in those days the early concepts of endocrinology and the beginning logical therapy it appeared to offer. I always hoped that somehow I could one day work in a laboratory. In France, one terminated medical studies after 5 years of curriculum; one could then practice medicine––which I did for some time. To obtain the degree of Doctor in Medicine, one had to write and defend a dissertation, a thesis, which was usually pro forma. I decided, however, to write a dissertation for the M.D. degree that I would enjoy and, I hoped, on some work I could perform in a laboratory.

While I had always been interested in endocrinology as a medical student, my interest in neuroendocrinology undoubtedly started later with my collegial and friendly contacts with Claude Fortier when in 1948 I joined the group of young people attracted to the just-created Institute of Experimental Medicine and Surgery at the Université de Montréal.¹ Its young director, Hans Selye, then 43, was at the peak of his attractive powers over young(er) minds intrigued by his extraordinary experimental abilities, the novelty of his observations, and the far-reaching implications he derived from them. At the end of World War II, medical literature from the United States started to trickle into Europe. One day, in the small village where I was practicing medicine, I heard that Selye would be lecturing in Paris on “stress” and the “diseases of adaptation.” I decided to go to hear him. Selye lectured, in French, at la Pitié (a charity and teaching hospital built in the 17th century and where the cardiologist Paul Lian had for a number of years organized an annual teaching event with distinguished invited lecturers). The magnetism of the man was extraordinary. For me, just out of 5 years of medical school, 2 years of which had been in Nazi-occupied France, with teaching entirely directed toward medical care and no laboratory opportunities whatsoever, the lectures of Selye were from a different world. I went to talk to him after one of his lectures. After some sort of an interview in the office of Robert Courrier in the old building of Collége de France, Selye assured me of a modest fellowship of $120 per month from his own research funds to come to Montreal for one year, where I would complete a dissertation for the M.D.

A couple of months at that institute, in the midst of other young people from Canada, England, Holland, the United States, and Brazil, led me to conclude that I had grossly miscalculated my abilities. There was no way I could ever reach their ease at handling the knowledge, techniques, and concepts which I had never heard of in those dark years of my “medical studies” in Dijon. I was thus inclined to regard the year as a rather unique escapade and then go back to the practice of medicine in Burgundy, probably in that medieval little town where I had already established a modest reputation as a young and alert practitioner in part-time assignments during my last year of medical schooling.

Selye had asked me to set up a technique to keep rats alive long enough after bilateral nephrectomy to see whether large doses of desoxycorticosterone acetate would still produce the vascular lesions he had shown earlier to be regularly produced by the mineralocorticoid in unilaterally nephrectomized rats.

While he was a remarkably lucid and elevating lecturer, Selye was not a teacher of graduate students or postgraduate fellows in the sense that he would make specific efforts to spend any of his own time to teach one anything. The tools, the environment were there and available, but it was left to everyone to make the best of it. Personal contacts, discussions, collaboration among the younger people were of major importance. It was through these that I learned of Fortier’s interest in elucidating the mechanisms involved in the physiological control of ACTH secretion, one of the primordial events, as had been shown by Selye, in the response to stress. Besides my work with the bilaterally nephrectomized rats, I read the available literature and observed what Fortier was doing, at that time transplanting the anterior lobe of the pituitary in the anterior chamber of the eye. Geoffrey Harris, then at the Maudsley Hospital in London, came to Selye’s institute as a Claude Bernard Lecturer in 1949 and spent a week with us. Very different from Selye as a scientist, he convinced some of us that there were major problems in classical physiology to be answered in elucidating the physiological mechanisms involved in the hypothalamic control of adenohypophysial secretions. In his laboratory at the Maudsley, he had recently shown, with several younger collaborators such as Curt von Euler, Seymour Reichlin, Bernard Donovan, K. Brown-Grant, and Jack deGroot, that it was possible specifically to stimulate, acutely or chronically, the secretion of one anterior pituitary hormone or another [adrenocorticotropin-(ACTH), thyrotropin-(TSH), gonadotropin(s)-(FSH/LH)] by electrical stimulation of different loci in the ventral hypothalamus in studies with rabbits; conversely, high frequency or electrocoagulation of the same hypothalamic nuclei would inhibit or prevent secretion of the same adenohypophysial hormones. Similar conclusions had been reached quite independently by David Hume, Don Fredrickson, and W. F. (Fran) Ganong at the NIH in Bethesda and Samuel (Don) McCann and John Brobeck in Philadelphia. These studies had followed early reports by Charles (Tom) Sawyer, J. E. Markee, and W. H. Hollinshead in 1946 and by Jack Everett and C. H. Sawyer in later years.

At that time the prevalent concept was that the hypothalamus was somehow involved in controlling the secretions of the anterior lobe of the pituitary, most likely through some neurohumoral transmitter, reaching the adenohypophysial parenchyma through the exquisite network of capillary vessels first described by Popa and Fielding (J. Anat. Vol. 675, 88, 1930). The vascular pathway was the sole possible link, because it was by that time clearly established that no nerve fibers could be shown to exist between hypothalamus and adenohypophysis, in contradistinction to the well-recognized tract of nerve fibers joining the supraoptic and the paraventricular nuclei of the hypothalamus to the posterior lobe of the pituitary. The concept of neurosecretion had originated with morphologists such as Berta Scharrer, first in Germany and later in the United States, observing in invertebrates, neurons which contained granules stained by various dyes and which thus resembled cells of exocrine or endocrine glands—the thyroid, the pancreas, the pituitary, etc. Extended to vertebrates by Ernst Scharrer, and the school around Bargman in Germany, the concept was essentially based on morphological observations, again dealing with the hypothalamo–hypophysial system of fibers I mentioned above and relating to the neurohypophysis. As early as 1924, the chemist J. J. Abel, then at Johns Hopkins, had mentioned that aqueous extracts of the ventral hypothalamus of several mammalians had the same bioactivities as similar extracts of the posterior pituitary. Geoffrey Harris and Dora Jacobson had shown that secretion of adenohypophysial hormones (ACTH, TSH, FSH/LH) would cease following complete section of the pituitary stalk, only to resume if and when the capillary vessels between hypothalamus and adenohypophysis would rejoin and reirrigate the pituitary tissue. And the flow of blood had been shown by Harris in the rabbit, by Bernardo Houssay in Buenos Aires in the frog, by Jacques Benoit and Ivan Assenmacher in the duck to be from brain to pituitary.

What was the chemical nature of this single? multiple? message from hypothalamus to pituitary? Nobody knew. And Selye, in the daily rounds in the laboratory or at the weekly seminar, kept insisting that it was all important to know the chemical nature of that “first mediator” that would acutely activate the pituitary to secrete ACTH upon exposure to any kind of stress, thus leading to his “alarm reaction.” Somewhat after the visit of Harris in Montreal, the idea occurred to me to use what Selye had called “adaptation to nonspecific stress” in an effort to dissociate the nonspecific release of ACTH by drugs exerting other, very specific pharmacological actions, drugs such as antihistaminics. Why antihistaminics? Probably because we had had another set of Claude Bernard lecturers, Bernard Halpern and Jean Hamburger, who had lectured to us about the new phenothiazine derivatives that the French pharmaceutical industry had recently made available to them and that they had found to be powerful antihistaminics (before others were to recognize their neuroleptic activities). And there were reports from Kahlson’s laboratory in Lund indicating large amounts of histamine in hypothalamic extracts. My idea was to see whether one could reach a “stage of adaptation,” in Selye’s terminology, by repeated injections of Phenergan after it had lost its ability to induce (nonspecific) release of ACTH while still retaining its specific pharmacological activity as an antihistaminic. Thus we could ascertain whether the ultimate mechanism triggering the release of ACTH was histamine, or at least some endogenous substance specifically affected by Phenergan. I discussed this with Fortier and we started a few experiments along these lines. There was soon no doubt that repeated injections of Phenergan would each stimulate less and less ACTH release, as judged by the adrenal ascorbic acid test of Sayers, and that a time could be reached when injections of Phenergan were no longer followed by acute release of ACTH. In these animals the drug retained its normal, potent antihistaminic property and would completely prevent the acute release of ACTH normally induced by injection of enormous doses of histamine. I then observed that in such a preparation any other type of stress agent such as surgery, injection of formalin, or forced immobilization would still stimulate the normal release of ACTH. The “first mediator” of Selye’s stress syndrome likely was not histamine. This was reported in a short note with Claude Fortier (Trans. N.Y. Acad. Sci., Vol. 15, 138–140, 1953) and was my first contribution to the field of neuroendocrinology. I conducted similar studies somewhat later, with anticholinergic and adrenolytic drugs, with similar results. I also ascertained that the drugs were indeed acting within the central nervous system, demonstrating their ability to inhibit focal cortical seizures recorded by electrocorticography and induced by depositing, on the parietal cortex of the rat brain, small paper pledgets soaked with histamine, carbachol, or serotonin. The conclusion was thus reached that none of the classical neurotransmitters studied here (acetylcholine, epinephrine, serotonin, histamine) was the exclusive ultimate mediator, “the first mediator” of Selye, of the (stressinduced) release of ACTH. Some other (novel?) substance of hypothalamic origin had to be postulated as the ultimate mediator.

Leaving Montreal

Somehow, it was now 1952. I was still in Montreal, having enrolled in 1949 in an extraordinary series of courses in endocrinology (in which I met Murray Saffran as one of the undergraduate students) jointly offered by McGill and the Université de Montréal, and I was completing a dissertation for the Ph.D. degree in physiology (actually called experimental medicine and surgery). The experimental work for that degree dealt with the mechanisms involved in the production of hypertension and kidney lesions by desoxycorticosterone acetate—the topic Selye had assigned to me when I arrived in Montreal. Nothing earthshaking is to be found in that dissertation, but I had learned the fundamentals of experimental endocrinology, how to design an experimental protocol, and how to be critical of oneself (and of others). They had been 4 extraordinary years and I have always been grateful to Hans Selye for having given me the opportunity. While I knew that I enjoyed the life of an investigator, I was not too sure that I had what was necessary to be a meaningful one. I knew, though, that if there were to be a way of mine, it would be different from the ways of Selye. I had come to recognize that Selye’s style was absolutely unique and probably not to be emulated. He would always be dealing with a purely descriptive phenomenology, with more than a touch of the dramatic and a need to be read and/or presented as generating “unified” theories of medicine. Moreover, with the exception of a few early and elegant studies on the neuroendocrinology of the milk-letdown reflex, very classical in their approach, Selye’s descriptive phenomenology, as I called it above, was the result of experimental decisions of such extremes as to make one wonder about their relevance not only to physiology but also to the causes of diseases of man. I would probably best fit as a “traditional” physiologist.

Having completed the work for and received my Ph.D. degree, I decided to leave Selye’s laboratory. By that time I had married Lucienne Jeanne Billard, the nurse who had been in charge of my case when, a couple of years earlier, I had been diagnosed with TB-meningitis. Three of the young people in Selye’s lab came down with rather sudden infection with tuberculosis at about the same time. The source of infection was never fully elucidated. I was thus one of the early beneficiaries of Waksman’s recent discovery of streptomycin and intrathecal dihydrostreptomycin. I was also given very large doses of the even more recent cortisone for reasons difficult to understand today. But the result of it all was adequate enough so that I did not lose more than a summer in Notre Dame Hospital in Montreal. Our first daughter, Chantal, was born in October 1952.

After I visited C. N. H. Long at Yale, who had been an early proponent of an adrenergic mechanism for ACTH release, he offered me a job in his Department of Physiology, which I accepted. A few days later, through a peculiar set of circumstances connected with my having received one of the early scholarships of the John and Mary R. Markle Foundation the year before, I was asked to join the Department of Physiology at Baylor University College of Medicine in Houston, Texas, as an assistant professor to teach endocrinology. Hebbel Hoff had recently moved to Baylor from McGill as chairman of the department. I flew to Houston and met him and Michael deBakey, the cardiovascular surgeon who had just joined Baylor as chairman of surgery. At Baylor, there were space, money, an incredibly open future, and also azaleas and live oaks. Somehow, I sensed that all that meant more than the Ivy League. I never regretted that decision. I sent a cable of apologies and regrets to C. N. H. Long, who, always the gentleman, never held it against me, as I was to know later on many occasions. In September of 1953, I joined the faculty of Baylor and started to teach endocrinology. With my money from the Markle Foundation, I also immediately started a modest research project to complete the “adaptation” studies started in Montreal on the mechanisms of ACTH release.

Baylor College of Medicine, 1953–1970

I stayed at Baylor and worked and taught physiology in Hoff’s department for almost 20 years. Hoff was probably the most considerate and the most generous chairman I could ever have hoped for. He created an environment in that department where I could work with a minimum of encumbrances. His teaching load was immeasurably greater than mine for all those years. He accepted generously that I would prefer to spend much of my time and effort in my laboratory with a few graduate students and postdoctoral fellows rather than with the medical students. He shielded me from too much involvement in the internal problems of the school (thanks to him, I barely knew when there were problems at the school). Hoff also easily enrolled me in his scholarly interest in the history of medicine. All the work we published together on Claude Bernard’s manuscripts, on the early time recordings of natural phenomena, on the history of blood transfusion in man, in which I was rather deeply involved at some time—all that was seeded, started, and nurtured by the prodigious energy and the encyclopedic mind of this great scholar of modern American physiology. Hoff revolutionized the teaching of modern physiology to medical students by his early introduction, with Leslie Geddes, of simple and rugged electronic instrumentation in the early 1950s (the Physiograph), to replace Ludwig’s kymograph and the accompanying smoked drum that were still in use at that time. All of the current instrumentation is so obvious now that we forget it was not always like that. Hoff could have chosen to spend more of his time in his own laboratory to pursue his earlier work with John Eccles in Sherrington’s department on the electrophysiology of the pacemaker of the heart or later with John Fulton on the physiology of the respiratory center. He chose instead to let me, along with other younger people in the department, spend my time in my laboratory. My debt of gratitude to Hebbel Hoff is equaled only by my feelings of affection for him and my respect for his scholarly mind.

The man who had been in charge of the department before Hoff became chairman was A. D. Keller. Keller and Breckenridge had reported a series of experiments in which they had observed persistence of hypophysial functions after “extirpation” of the pituitary stalk and also after partial hypophysectomy. Breckenridge was still in the department, and I got to know him well. A gentle man who decided to get an M.D. degree (which he obtained when he was in his late 40s), Breckenridge was still interested in the physiology of the control of pituitary secretions. He showed me how to hypophysectomize dogs by an elegant transpalatinal approach that I showed later to one of my postgraduate fellows, Harry Lipscomb. Keller’s original results, totally at odds with what Geoffrey Harris had reported, were, and still are, best explained by uncontrolled regeneration of the hypothalamo–hypophysial portal vessels.

One day, from Houston, I went to Galveston to visit the tissue culture laboratory of Charles Pomerat and also to see some of his famous watercolors of churches in Mexico. Pomerat showed me around, showed me his extraordinary time-lapse movie photography of various cells, particularly of neurons, speaking either in English or in his slow, perfect French, with always the most exquisite and exacting choice of the mot juste. He introduced me to a young undergraduate, Barry Rosenberg, who had been culturing adenopituitary cells as his assignment for an M.Sc. degree. Then Pomerat said, ‘‘You know these pituitary cells which grow so well, for some reasons which we don’t understand, do not seem to secrete hormones.” I asked which hormones and he said, “Gonadotropins. We are testing the fluids by injecting them into mice prepared as for pregnancy tests.” I immediately told Pomerat, “I think I know why this is so: Your pituitary cells in vitro are lacking some substance of hypothalamic origin. Could one culture jointly pituitary and hypothalamus?” Pomerat was not particularly impressed. In a short discussion later that day, I described to him the rationale for my statement, but I did not convince him. I left, intrigued, and kept thinking about this strange observation and my proposal. A week or so later, I went back to see Pomerat and asked him whether I could set up some simple experiments in his laboratories to test the idea I had mentioned to him the previous week. I do not remember exactly what happened; Pomerat was no more enthusiastic than on the first occasion, but he suggested that perhaps Rosenberg could join me at Baylor in Houston (Rosenberg had applied to Baylor College of Medicine, as I seem to recall) to study that very problem. Barry Rosenberg came to Baylor a few weeks later and showed me how to do tissue cultures with the clot and coverslip method, originated by Alexis Carrel, 40 years earlier at the Rockefeller and still in use. Shortly thereafter, as I recall, Barry Rosenberg left to go to medical school in New York. A few months later, I knew that the pituitary cultures released ACTH in the culture medium, but only for the first few days following transplantation, and that they would release ACTH again if and when they were co-cultured with fragments of median eminence or ventral hypothalamus. I had set up the adrenal ascorbic acid bioassay for ACTH, Sayers’s assay, as I thought that it would be more sensitive than the assay for gonadotropins used earlier by Rosenberg in Pomerat’s department, and also probably because studies on the mechanisms of response to stress (the release of ACTH) were much in my mind after 4 years in Selye’s laboratory. I still remember going home the evening of the day on which I had seen for the first time the effect of adding a fragment of hypothalamus tissue to the pituitary cells in vitro and had observed the depletion of adrenal ascorbic acid in every animal of the bioassay, the sign of the presence of ACTH. I remember well telling my young wife, “I have made an observation today of such importance that you will never have to worry about our future in academic medicine.” I also remember, during the next few weeks, the extraordinary excitement of learning the methods of pharmacological assays for vasopressin, oxytocin, histamine, epinephrine, and norepinephrine, and getting them to work in the one-room laboratory; the elating sensation of learning so many new things, getting them to work for new goals—things which had never been done by others; the thrill of discovering, of realizing the pregnant future, known only by those who have really experienced it. I am happy to see that still happening to the younger people in the laboratory when they come up with a good new idea or make an unexpected observation, confirm it, and expand it. It is certainly a different feeling from what one feels when putting the final mark on the solution of a problem which has taken years to solve. The former is all action, movement, and expectation. The latter is a feeling of achievement, of having reached the goal, of finally breathing, and of”what next.”

That summer (1955) I spent a month in the Maudsley laboratories of Geoffrey W. Harris at the Institute of Psychiatry in London. I showed the early results of combined tissue cultures to Harris. He was rather skeptical. During that short stay at the Institute, I met Seymour Reichlin, Bernard Donovan, Keith Brown-Grant, and H. J. Campbell; Claude Fortier was there also. Later that fall, David Hume came to Houston for the meeting of the University Surgeons and he talked on kidney transplants, his new interest. I showed Hume the results of the combined tissue cultures with hypothalamus and pituitary. Hume was impressed and, I remember, encouraged me to go on with the in vitro method.

After a seminar I gave at Baylor, I was approached by Walter Hearn, another young fellow like me, from the Department of Biochemistry. He proposed that we work together to isolate the hypothalamic hypophysiotropic substances. I was delighted by the proposal. I had by that time pretty much decided that the most important contribution to understanding the mechanisms whereby the hypothalamus controlled the secretion of the pituitary was to establish the nature of the hypothalamic factors involved. Anything short of that would be beating around the bush. Once the hypothalamic hypophysiotropic neurohormones were isolated and characterized, all the real physiological as well as clinical studies could proceed with synthetic replicates of the neurohumors in unlimited amounts.

In one of our lectures at McGill, David Thompson had once generalized that all hormones secreted by cells of ectodermic origin were proteins or polypeptides, those secreted by cells of endodermic origin were proteins or small-size derivatives of amino acids (thyroxine), and those secreted by cells of mesodermic origin were steroids. Perhaps naively, I had formed the hypothesis that the postulated hypophysiotropic hypothalamic substances would be peptides, probably small, as were oxytocin and vasopressin. Since du Vigneaud had characterized and synthesized these two, the hypothetical others would be synthesized also. Of revolutionary significance was the work led by Vincent du Vigneaud (V du V) at Cornell with Charlotte Ressner, Darrell Ward, Panayotis Katsoyannis, which had led to the separation of oxytocin and vasopressin, the establishment of their primary structure as two closely related nonapeptides, and, in 1952, the total synthesis of oxytocin, the first complete synthesis of a large and complex polypeptide endowed with hormonal activity (J. Am. Chem. Soc., Vol. 75, 4879–4880, 1953). (Du Vigneaud would receive the Nobel Prize for Chemistry in 1957 for that achievement.)

Hearn and I worked for 2 years (until he left Baylor for another job at Ames, Iowa—where one of his technicians, later graduate student, would be Roger Burgus). Joined by several graduate students and postdoctoral fellows, William Cheek, Buford Nichols, Dwight (Gene) Householder, Sidney Levine, and later Harry Lipscomb, we purified extracts of hypothalamic tissues (a few fragments, maybe 10–50, collected locally from a sheep and steer kosher operation) and later of posterior pituitary tissues; both had ACTH-releasing activity. Through simple chromatographic separation, we convinced ourselves that the ACTH-releasing activity both in the hypothalamic tissues and in the pituitary extracts was due to some substance that appeared to be different from oxytocin and vasopressin, known since John Abel in 1924 (and as seen again in my bioassays) to be also in these hypothalamic extracts.² Why the work on extracts of the posterior pituitary? Early in 1955, a note by Don McCann and John Brobeck reported that injections of relatively large doses of Pitressin (a commercial clinical preparation of vasopressin) would release ACTH in rats having large lesions of the median eminence produced by electrocoagulation through electrodes located with a stereotaxic instrument. Such a lesion had been reported by McCann to inhibit or prevent the acute release of ACTH that takes place upon exposure to any sort of stressful situation. McCann in these early studies showed how such lesions could be produced routinely in the rat.

Sam McCann was born and reared in Houston; I had met him after my early studies with Fortier in Brobeck’s department during a short visit in Philadelphia and that same evening at Brobeck’s house. I had just received pure synthetic lysine–vasopressin from du Vigneaud and had observed that it would not stimulate release of ACTH from the pituitary tissue cultures. I confirmed McCann’s and Brobeck’s reports when I observed that Pitressin would release ACTH from the pituitary tissue cultures whereas the synthetic vasopressin (LVPl) from du Vigneaud would not. My conclusion was that some substance other than vasopressin in the relatively crude Pitressin was the responsible hypophysiotropic agent. That was the beginning of an extraordinary series of experiments and spirited exchanges between McCann and myself that would last for almost 5 years. There would be the “vasopressin school,” with McCann as its leader, followed by an everincreasing number of people, pharmacologists, physiologists of sorts, and clinicians, all satisfied that vasopressin could be and was the physiological mediator of the stress-induced release of ACTH. The evidence appeared overwhelming, but was circumstantial. Against all these would be the other school (the “CRF school,” as it would be named later), proposing that vasopressin could not be the physiological mediator of ACTH release (too-high doses of vasopressin were necessary), which instead was controlled by a corticotropin-releasing factor (CRF), possibly related chemically to vasopressin but different: Hearn and I had obtained by paper chromatography “fraction D” from hypothalamic extracts, which had no or little pressor or antidiuretic activity, which had a mobility different from that of pure synthetic lysine—vasopressin, and which released ACTH. Finally, both McCann and I agreed in 1959 that vasopressin was not the exclusive mediator of stress-induced release of ACTH after a series of experiments I reported with Buford Nichols showed that in nonanesthetized trained dogs one could totally dissociate release of ACTH, measured by plasma 17-hydroxycorticosteroid levels, from the release of vasopressin as shown by concomitant antidiuresis; also, in several hundred animals (rats) stereotaxically placed hypothalamic lesions would or would not inhibit stress-induced release of ACTH, as assessed by the new flurometric method I had devised with George Clayton to measure plasma corticosterone, with no correlation whatever with the presence or absence of diabetes insipidus.

What was the origin of that name “corticotropin-releasing factor,” or CRF? In 1955 I had organized with Charles Carton, a young assistant professor in neurosurgery, and William Fields, a professor of neurology at Baylor, the Third Annual Meeting of the Houston Neurological Society, to be devoted to recent studies on the hypothalamus. The only previous meeting on that subject had been the imposing meeting of the Association for Research in Nervous and Mental Diseases (ARNMD), which had taken place in New York in December 1939. The lean volume that came from the Houston meeting (compared to the 1000-or-so-page The Hypothalamus published by the ARNMD in 1940), titled Hypothalamic Hypophysial Interrelationships, was edited by the three of us and was the first volume ever devoted to the neuroendocrinology of the hypothalamus. To my surprise, I learned at that meeting from Geoffrey Harris, who came with John Green, whom he had been visiting at UCLA, that somebody else had been doing in vitro work with pituitary and hypothalamus. Harris had visited Saffran at McGill a few weeks earlier, who had shown him results of short-term incubation (a few hours vs the days and weeks of my tissue cultures) of rat pituitary. Saffran had been incubating rat adenohypophyses with fragments of hypothalamus, brain cortex, or posterior pituitary. It was the first I had heard of Saffran’s work on the control of ACTH secretion. Harris also said that Saffran, too, had concluded that vasopressin was not the releaser of ACTH—rather, it was another peptide that he called “corticotropinreleasing factor,” in short CRF. Harris added that Saffran had almost isolated the corticotropin-releasing factor, which was present (probably stored) more in the posterior pituitary than in the hypothalamus. All of that was in remarkable agreement with what I had independently concluded.

When I got in touch with Saffran and exchanged information and results with him, it became obvious to me that Saffran’s methodology was much more quantitative than mine, with his use of rat hemipituitaries (rather than my coverslip tissue cultures) and with a well-characterized incubation medium (rather than the tissue culture fluid with chick embryo extract and calf serum). There were also some peculiar discrepancies in results. The most potent extracts Hearn and I had made to stimulate release of ACTH were of hypothalamic origin. Saffran’s co-incubations with extracts of the hypothalamus were inactive in releasing ACTH or were replaceable by brain cortex and required the presence of a catecholamine; his best results (the most potent additive to stimulate release of ACTH) were obtained with rat posterior pituitary. Saffran’s results (reported with Bruno Benfey and Andrew Schally) on the pituitary incubation and extracts, together with the whole thrust of the in vivo experimental results from McCann and my own in vitro observations of ACTH release with Pitressin but not with synthetic vasopressin, led to intense work on extracts of the posterior pituitary. On the appeal of the quantitative aspect, I shifted rapidly to the short-term hemipituitary incubation. Following discussions with Claude Fortier, who had just joined the staff of the Department of Physiology at Baylor, we so modified its design and calculation to make it even more amenable to sound statistical calculation—simple but powerful modifications that I was happy to learn from Saffran shortly thereafter he and Schally immediately incorporated in their subsequent studies. Hearn, Householder, and I observed corticotropin-releasing activity in fractions from posterior pituitary extracts with mobilities identical to those of the hypothalamic materials in several systems; all were different from the vasopressins or oxytocin. In studies of tissues other than hypothalamus and posterior pituitaries, I was surprised to observe occasional release of ACTH by fractions of brain cortex extracts as well as by fractions of relatively crude substance P of brain or gut origin. In all cases, the active fractions (releasing ACTH) behaved on two or three chromatographic systems identically to the ACTH-releasing fraction of hypothalamus or posterior pituitary origin. The most purified materials (fraction D) active in vitro at 1 µg/ml were obtained in minute amounts (less than 100 µg); they were not homogeneous. When we tried to obtain them in greater purity by paper electrophoresis, we would regularly lose activity and peptide.

Hearn left Baylor for Iowa State at Ames. I immediately contacted some of the younger biochemists in the Medical Center in Houston to pursue the isolation of CRF. I was not a biochemist. Obviously, the isolation of CRF required knowledge of chemistry that I lacked, and the isolation of CRF was the most important thing to pursue and complete. One day, I received a letter from Andrew Schally, writing from Saffran’s laboratory and inquiring about the possibility of joining me at Baylor. My first meeting with Schally was at the following Federation Meeting in Atlantic City. Schally had written that he would be getting his Ph.D. degree the next summer or fall and that he would like to come work in my laboratory without delay after that to complete the isolation and characterization of CRF and, he hoped, move on later to other suspected hypothalamic factors. The Atlantic City meeting confirmed these goals and Schally’s interest. In that first conversation, I found Schally to be an intense younger man who, to me, the physiologist, appeared to be a qualified biochemist already with knowledge and technical know-how on peptides and, more particularly, on CRF from his training with Saffran. Working together appeared to be a sure bet to finish the isolation of CRF which I had started with Hearn. The same conclusion had obviously been reached by Schally on the basis of his work with Saffran and of what he had read of my papers. Somewhat surprised that he would not do all he could to keep him, I wrote Saffran to tell him of the letter and conversation with Schally. Saffran was affable as always, gave Schally a good though guarded recommendation, and told me that he (Saffran) was leaving on a sabbatical to work on projects unrelated to CRF.

Schally joined me in Houston in 1957. We worked together very well, very hard, with never an unpleasant word, on the isolation of CRF, which we saw within reach in another few months—repeatedly every 6 months for the next 4 years. There is no doubt in my mind that Selye’s studies on stress and his remarkable observations of the involvement of the pituitary–adrenal axis in response to stress were powerful and persuasive incentives for the early studies by Geoffrey Harris in London; David Hume, Don Nelson, and Fran Ganong at Harvard; Claude Fortier in Montreal; Evelyn Anderson, Gordon Farrell, and Sam McCann then at NIH; and later myself. To characterize the first mediator of the whole endocrine response to stress was quite a challenge in which many were interested. Selye’s concepts made it of physiological interest, with possible clinical significance, when J. S. L. Browne and Eleanor Venning started to show in the early 1950s that the endocrine response to stress in man also involved the pituitary–adrenal cortex system. Selye, through his stress concept, had thus a major stimulating role in orienting the early efforts in neuroendocrinology toward the study of the hypothalamus–pituitary ACTH–adrenal cortex functional relationships. Strangely enough, and unwittingly on Selye’s part, this is probably about the worst thing that happened to nascent neuroendocrinology. The search for CRF was to prove so complex and baffling that it was not completed until 1981 through the elegant work led by Wylie Vale, one of my former students and collaborators, as we shall see later.

The lack of an answer (isolation of CRF) after the first 3–4 years of early work—in fact, the lack of clear-cut progress toward isolation of CRF, multiple statements to the contrary—raised in the minds of many biologists, aware of the success of others in isolating biologically active substances (such as the ever-productive groups of Viktor Mutt in Stockholm or Vittorio Erspamer in Rome), grave doubts about the validity of these early concepts of neuroendocrinology; the same doubts were also directed, with concern, at the few people involved in these unsuccessful attempts at characterizing CRF. One can reasonably and musingly post-pose that, had we started to work on the hypothalamic control of thyrotropin secretion, or even of gonadotropin secretion, this most likely would not have happened. While the isolation of TRF (the thyrotropin-releasing factor) and the characterization of its molecular structure took from 1962 to 1969, the sequence of events involved was always logical and constructive and the reasons for slow progression were reasonably well understood.

In June 1960 I assumed the post of associate director of the Laboratory for Experimental Endocrinology, of which Robert Courrier was chairman, at the Collége de France, in Paris. The family—we then had six children, ages 8 years to 1 month—moved to France. We lived in the Chateau de Prunay, a beautiful place with 40 acres of park that belonged (and still does) to the Institut de France. On the insistence of Hebbel Hoff, I maintained my laboratory at Baylor operative, funded, and active with Harry Lipscomb and Andrew Schally. I literally commuted between Paris and Houston. Three years later, I decided to return to Houston; local circumstances in Paris had been such that I could not reconcile them with my goals or my ethics in science. My wife and all the children found the return to Texas somewhat difficult. It was in Paris, during those 3 extraordinary years, that Edouard Sakiz and I obtained our first solid evidence for the presence of a luteinizing hormone-releasing factor (LRF) in hypothalamic extracts and reported its early purification by gel filtration and ion-exchange chromatography (C.R. Acad. Sci. Paris, Vol. 256,504, 1973). The very same methodology was to be used 10 years later in the final isolation of LRF by my laboratory as well as that of Schally. Sam McCann and Geoffrey Harris also had reported evidence for the existence of LRF at about the same time. I have given in some detail a historical account of the search for LRF, its purification, and the involvement of both my laboratory and Schally’s in its isolation and synthesis (see Am. J. Obstet. Gynecol., Vol. 129, 214–218, 1977). The most important achievement of those 3 years in Paris was the report with Edouard Sakiz, Eichi Yamazaki, and Marian Jutisz of the first incontrovertible evidence of a thyrotropin-releasing factor in hypothalamic extract (C.R. Acad. Sci. Paris, Vol. 255, 1018–1020, 1962), its first purification and, with Don Gard, the early evidence of the mode of action of TRF in competition with thyroid hormones at the pituitary level (Endocrinology, Vol. 73, 564–572, 1963). Large-scale collection of sheep hypothalamic fragments also was started in Paris. When I returned to Houston in 1963, I carried with me half a million fragments of sheep hypothalamus, dissected, trimmed, and lyophilized, ready for work. By 1962, I had definitely concluded that enormous quantities of hypothalamic tissues would be necessary to complete the work involved in the chemistry of isolating and characterizing the hypothalamic hypophysiotropic factors. Of their existence, there was no doubt in my mind.

Back in Houston, I went to about every one of the largest slaughterhouses in the Midwest and Southwest, spending 1 or 2 days working on the floor with the local people to make clear what I wanted. Over 3 years, I collected 5 million fragments of sheep hypothalamus. There were some colorful episodes; my French accent was of little help in Paris, Texas. The summer after Wylie Vale became a graduate student at Baylor, his assignment was to work full time on the killing floor of one of the slaughterhouses in San Antonio which had agreed to donate the tissues if we could furnish the labor. That was hard labor for him, for that summer. Eventually, every one of the fragments was redissected in the laboratory to ascertain anatomical correctness of the section involved and to trim away peripheral tissues (du Vigneaud, who came to visit in Houston had once told me that, in the isolation of oxytocin, the most efficient purification step had been that of separating the pituitary from the cow). More than 50 tons of fresh frozen tissues was handled, processed, lyophilized, and extracted in the laboratory from 1964 to 1967.

When in November 1963 I returned from Paris to Houston, Schally was no longer in my laboratories at Baylor. Deeply disturbed at our inability to solve the problem of the nature of CRF in the 4 years of collaborative efforts, I had told him during one of my many commuting visits from Paris to Houston that perhaps some reappraisal of our collaborative arrangement would be necessary in the future. Late in 1962 or early 1963 Schally went to New Orleans to set up a unit of research on polypeptides at the Veterans Administration Hospital, where he pursued his own efforts on the characterization of hypothalamic peptides controlling pituitary functions.

In our working together, Schally and I had learned much about the strategy of an isolation program that would be of use to both of us in future endeavors. As I said above, it is perhaps unfortunate for neuroendocrinology that we did not first look for a TRF or a LRF in hypothalamic tissues. The hard work that Schally and I had devoted unremittingly to the characterization of CRF had little immediate reward. But this is the usual case with hindsight. Edouard Sakiz and Eichi Yamazaki had both decided to come with me to the United States from Paris. At the last minute, Yamazaki told me that he wished to abandon science for the spreading of true Buddhism; he became (and still is) a high-ranking member of Sokagakai, a very large religious and political party in Japan. Sakiz went to Houston ahead of me by a few months to get things going at our usual pace. From Paris to Houston, Sakiz and I worked together for almost 7 years, with a bond of friendship and of intellectual commensality that I never encountered with anybody else. That warm friendship is still very much alive. Sakiz became the director of research and later the president of Roussel-UCLAF, one of the largest and most successful pharmaceutical companies in France.

Upon return to Houston, we worked hard at purifying both LRF and TRF, in consultation with Darrell Ward, who had come from du Vigneaud’s laboratory to M.D. Anderson Hospital across the street, where he became chairman of biochemistry. I organized the handling and cutting of the hypothalamic fragments and their lyophilization in industrial-size desiccators. I also performed the first solvent extraction and stockpiled the products of the first steps of purification of the extract, chromatography on gigantic gel-filtration columns of 15 cm x 2 m, in batches of 100,000 fragments, followed by ion-exchange chromatography on columns also of respectable size (all methodology that we had ascertained early on small scale). Meanwhile, Sakiz was running the bioassays; he was also writing more and more sophisticated computer software for our statistical analyses in experimental endocrinology. In spite of all that hard work, efficiency, and enthusiasm, there is no doubt in my mind that the move from Paris back to Houston, with the accompanying physical and emotional strain, was a terrible drawback for our work in the laboratory.

In my historical account (mentioned above) of the isolation of LRF, I explained how the vagaries of the bioassay had led me early in 1965 to shelve the isolation of LRF until a better assay became available (that was not to arrive until 1969 from our work with Max Amoss, when Max reduced to practice a solid-phase radioimmunoassay for rat LH of exquisite sensitivity and great specificity). Because the bioassay for TRF I had designed in Paris in 1962 was so reliable, we could devote our full-time effort to characterizing TRF. With Edouard Sakiz and Pierre and Simone Ducommun, who had joined us after 3 years in Fortier’s department in Quebec, and young Wylie Vale, we also conducted in vitro and in vivo physiological studies on the mechanisms of simultaneous secretion of ACTH and TSH and on the mechanisms of secretion of TSH as modified by thyroid hormones and using (sparingly) relatively crude preparations of TRF. With Wylie Vale, we showed the effects of elevated K⁺ on TSH secretion, the role of Ca²⁺, the antagonism by thyroid hormones, and the rapid degradation in plasma of purified (though not homogeneous) TRF. From these times came the elegant study that was part of Wylie’s dissertation showing the dissociated effects as a function of time of cycloheximide vs actinomycin D on thyroxine inhibition of TRF-induced release of TSH.

Soon after my return from Paris I had begun inquiring for a chemist to join our group, as Darrell Ward could not devote much of his time and efforts to this project and I knew I did not have the competence to bring to completion the isolation of TRF and its structural characterization, particularly in view of the submilligram quantities that were expected to constitute the final yield. In September 1965, Roger Burgus joined us at Baylor. While he had been working on the chemistry of cobalamines in the preceding few years, he had trained with Hearn at Ames, Iowa, and had been involved in Ream’s own efforts, after he had left Baylor, in preparing CRF from posterior pituitary powders. The arrival of Burgus was taking place at a propitious and also critical time: propitious because I had accumulated large amounts of the hypothalamic extract and Sephadex fraction containing TRF for a meaningful attack on its final isolation; critical because Sakiz, Ward, and I had recently started to wonder whether TRF was a polypeptide or at least a homomeric peptide since we could not destroy the biological activity of our preparations of TRF by incubating them with trypsin, Pronase, carboxypeptidases A and B, or leucine amino peptidase. A short note stating that question (C. R. Acad. Sci. Paris, Vol. 262, 2278–2281, 1966) was prepared some months after Burgus’s arrival. Burgus had carefully insisted that the text clearly read that, while the results recently obtained were compatible with such a proposal, they did not exclude the possibility that TRF could be a peptide, although a somewhat unusual one (by our thinking at the time).

Then followed the series of experiments that led in 1968 to the isolation of TRF in the laboratory at Baylor. The decisions as to the chemical steps, the handling of the minute amounts of pure material generated, and the final approach with mass spectrometry of the synthetic pGlu-His-Pro-NH₂ and finally of the native ovine TRF were those of Roger Burgus, while the performance and appraisal of the bioassays and the surrounding biology were my decisions, together with the participation of Wylie Vale, who was to receive his Ph.D. in physiology in the summer of 1968. I have given, with Burgus and Vale, a careful historical account of these 4 years, of how we purified, isolated, and characterized the structure of TRF, in an extensive and critical review (Vit. Horm., Vol. 29, 1–39, 1971). To this day, we have nothing to add to, remove from, or qualify in that review. It goes with great technical detail into the approach that we set and followed in what was to be a classic of the strategy used in the isolation and characterization of a natural product of complicated biological assay that is present in minute amounts (for the technology of that time, i.e., before the appearance of molecular biology) in an unusual starting material. References to the various pertinent technical papers are extensive and exhaustive, not only to the publications of my own laboratory but also to the few other groups working on the isolation of TRF, particularly Schally’s group. Of particular significance was the fact that we obtained the primary sequence of ovine TRF through low- and high-resolution mass spectrometry, a method leading to incontrovertible direct evidence. The identity of Rfs (ratio of mobility to the front of solvent) in multiple chromatographic systems, as proposed later by Schally’s group, is never of concluding weight.

I will recount here only a few details in a lighter vein. With Roger Burgus, Thomas Dunn, and Wylie Vale, I submitted to Science, in February 1969, a manuscript describing the TRF biological activity of the protected (treatment with acetic anhydride) synthetic tripeptide (R)Glu-His-Pro-OH and showed, in the same note, the absence of TRF biological activity of all the other protected isomer tripeptides. This was without any possible argument the first evidence of a known peptide (H-Glu-His-Pro-OH) with no TRF activity in itself but showing the generation of TRF activity solely upon protection of its N-terminus as we knew native TRF to be protected. Moreover, synthesis of the series of all tripeptides composed of His, Pro, Glu, produced in record time at my request by Rolf Studer and his collaborators at Hoffman-LaRoche in Basel, had been triggered by our recently acquired knowledge that the whole of the molecule of TRF could be accounted for by the three amino acids His, Pro, Glu as we had just publicly reported—Schally and Folkers in the audience—in January 1969 at a meeting in Tucson, organized by the NIH (see J. Meites, ed., Hypothalamic Hypophysiotropic Hormones,³ Williams & Wilkins, Baltimore, 1970, pp. 21–35). That manuscript was rejected by Science on the comments of one referee who said “the posterior pituitary peptides [oxytocin and vasopressin] are active [in stimulating release of TSH] in the nanogram range. I mention the claims of LaBella (Franck LaBella, a Canadian pharmacologist) not to advocate the posterior pituitary peptides as physiological TRFs but to compare the relatively high doses of the synthetic material with the low doses of substances known to occur in the vicinity of the hypothalamus.” Having anticipated that this might well be the fate of this revolutionary manuscript, I had sent a month later, in early March 1969, a short note to the French Academy of Sciences (which was to appear in C.R. Acad. Sci. Paris, Vol. 268, 2116–2118, 1969). I returned the manuscript to Science with what I thought was a clear and careful rebuff of such ridiculous comments, but also with new data, only to have it returned a month later with a new comment by the same referee, I suppose, that he had just read the note in French describing the same results; Science did not deal in repetitions. That fateful referee’s knowledge of French had to be about as profound as his knowledge of and, I would guess, his contribution to the field as shown by his earlier comments: the new version sent to Science had now the evidence of the pyro-Glu N-terminus and other additional new data leading to conclusions proposed but not proven in the earlier note in French. There is no doubt in my mind that had Science published that note when we sent it, the unpleasant exchanges that were to follow later in the year with Folkers and Schally about the priority of our characterizing the primary structure of TRF would never have occurred (or who knows!).

I have said and written on several occasions that I consider the isolation and characterization of TRF the major event in the establishment of modern neuroendocrinology, the inflection point that separated confusion and a great deal of doubt from real knowledge. Contemporary neuroendocrinology was born of that event. Isolations of LRF, somatostatin, the endorphins, others later, were all extensions of that major event––the isolation of TRF, a novel molecule in hypothalamic extracts, with hypophysiotropic activity, the first so characterized. I am happy that Geoffrey Harris was still alive when that happened. I have a letter from him in which he expressed in friendly terms his satisfaction with that happening. The event was the vindication of 14 years of hard work within the paradigm of a hypothalamic neurohumoral control of adenohypophysial secretions. From observation of what has happened in neuroendocrinology since 1969, the isolation of TRF was also the vindication of my early decision, as a physiologist, that the most heuristic event in neuroendocrinology would be the isolation and characterization of the first one (any one) of the then-hypothetical hypothalamic hypophysiotropic factors.⁴

After TRF, pioneering in neuroendocrinology ceased and became the harvesting of a new and expanding science. And expand, it did, in ways and concepts that were expected, so to speak in the normal science (in the sense of Thomas Kuhn) that followed but far more interestingly in the revolutionary (again in the sense of Thomas Kuhn) observations that were to follow. With the discovery of TRF several offers for chairmanship of a department of physiology came my way. One of the most intriguing was from the new campus that the University of California was creating at Irvine. While we were perfectly happy in Texas and at Baylor, I thought that one should not limit one’s vision to the acquainted surroundings. Sometime in January 1969, my wife and I went to the Irvine campus as guests of the search committee for a new chair of a combined department of physiology and pharmacology. That evening, the chairman of the search committee took us for dinner to a very nice restaurant called Victor Hugo, by the ocean. For the first time, we saw pods of gray whales blowing their spouts in the annual migration from Alaska to the lagoons in the south of Baja California in Mexico, where they have their calves, before returning north in March April. While we were having dinner, our host was called briefly to the phone. Upon his return, he said to me, “Jonas wishes to speak with you.” I asked whether that had anything to do with the whales we were watching and he answered, “No, no, the real Jonas, Jonas Salk, is trying to reach you.” A couple of days later, after I had for all practical purposes declined the offer from UC Irvine-the structure of the combined department as suggested was more than I felt comfortable handling and leading—we drove to La Jolla and saw the Salk Institute for the first time. We met Jonas Salk, the resident fellows, and the nonresident fellows of the institute gathered for their annual January meeting. The group of people was impressive. In addition to Jonas Salk, we met resident fellows Jacob Bronowski, Ed Lennox, Mel Cohn, Leslie Orgel, and Robert Holley, who had just received the Nobel Prize for his work on the structure of transfer-RNA and who had just joined the Institute. The nonresident fellows were Francis Crick, Jacques Monod, Salvador Luria, Warren Weaver, Steve Kuffler, and Daniel Lehrman. The president of the Salk Institute at that time was Joe Slater, who had come from the Ford Foundation. That group was the senior faculty of the institute, resident and nonresident fellows having each and all the same voting capacity in decisions involving the current and future academic programs of the institute.

I soon found out that they were interested in starting two new programs at the institute, one dealing with neurobiology and another dealing with or looking at fundamental research involved in the biology of birth control, to be expanded into means and problems of population control. In the couple of days of conversation that followed, it became apparent that the group I was dealing with was well aware of the latest literature on the purification of hypothalamic peptides, their significance in the physiological control of endocrine functions, and their potential clinical use. The discussions were friendly, fast paced, and with as much vision as technical subtleties.

But even more impressive than that impressive group was the structure, the building of the Salk Institute. Designed by Louis Kahn, in close spiritual and practical collaboration with Jonas Salk, it was positioned at the edge of a cliff opening westerly to the Pacific Ocean. The two identical buildings were separated by the plainest of travertine patios designed by Luis Barragan. Their monastic lines created in me a shock, a spiritual experience which I had never expected there or ever felt except perhaps when I first saw the Cathedral of Köln at the end of the second World War, all black and how gothic and intact, in the middle of such devastation. I was mesmerized by the extraordinary beauty of that Salk Institute and right then, decided that I could not pass the opportunity to work and live in such a unique place. To this day, 28 years later, I still have the same emotion each time I see that building.

In June 1970, the whole group moved from Baylor College of Medicine in Houston to the newly created Laboratories for Neuroendocrinology at the Salk Institute; 10,000 square feet of totally open space that I designed in close consultation with the architects in charge of outfitting it into a highly efficient, multipurpose laboratory, one half physiology, one half chemistry, and between the two halves an island with a conference room and 10 small offices for the staff and an administrative entrance for three secretaries. All central walls were of glass so that one could see through the whole space from any one location: nobody could, or should, think they were working alone in that laboratory. There were ceiling to floor length curtains, though, in the staff offices that could be closed should one wish. The curtains were rarely drawn. I worked in that laboratory for 20 years and never had to modify that original design, except in minor details. To the “TRF group” from Houston, we added Jean Rivier, who had been a postdoctoral fellow at Rice University in Houston, where he studied NMR spectroscopy with Richard Turner; Jean would be in charge of a 100-MHz NMR to be installed in the lab; Catherine, his wife, was completing her dissertation for the Ph.D. in physiology in my Baylor lab; Nicholas Ling, who came from Stanford with the most elogious recommendation from his mentor, Carl Djerassi, and who was to be in charge of a mass spectrometry unit; Michael Monahan from UCSD, who would be in charge of a unit of solid-phase peptide synthesis; and Anne Pitzer, who came with us from Houston as our inhouse computer expert. We had developed in Houston a sophisticated unit of computerized statistical analyses, modeling, etc. Nothing of that was then commercially available; we distributed free of charge, of course, hundreds of copies of the software, EXBIOL, the principles of which go back to the early days with Edouard Sakiz. When the laboratory was fully functional we were about 50 people. The move from Houston to San Diego (La Jolla) was so well organized that within 30 days of arriving at Salk, we were already generating data.

In the last year or so of the characterization of TRF, when it became obvious that that problem would soon be solved, I had decided to reopen the earlier project of the isolation of the hypothalamic factor, LRF, controlling the secretion of the gonadotropin LH (luteinizing hormone). A new graduate student, Max Amoss, had reduced to practice a solid-phase radioimmunoassay for rat LH. While still in Houston, we had brought into routine use the elegant method of short-term monolayer tissue culture of pituitary cells as originally conceived by Wylie Vale. I decided that it would be the method of choice, coupled with the radioimmunoassay for LH, for our work with LRF in the side fractions of our extracts of ovine hypothalamic tissues remaining from the TRF isolation program. By the end of the year we had isolated a few hundred micrograms of homogeneous LRF, which, based on quantitative HCl hydrolysis, yielded 9 amino acid residues. We also established that the C-terminal was amidated, as in TRF, and that the N-terminal was pyroGlu, again as in TRF. The complete and correct sequence of porcine LRF as that of a decapeptide, the 9 residues we had seen earlier plus a residue of tryptophan, with the C- and N-termini as we had seen and reported for the ovine peptide, was actually first proposed in June 1971 by the group of Schally; Schally completed the isolation process, the elegant chemistry for sequencing and early synthesis to be credited to the distinguished chemists Hisayuki Matsuo and Yoshihiko Baba, both visiting scientists in the laboratory in New Orleans. Three months later, Roger Burgus in our new lab at Salk completed the sequencing of ovine LRF by classic Edman degradation, and later Nicholas Ling confirmed the sequencing using mass spectrometry with our newly activated Varian Mat CH-5. The molecule of ovine origin had the same sequence as that of the decapeptide of porcine origin reported earlier by Schally’s group. The peptide of human origin, which we characterized a few years later with immunochemistry and microsequencing, is identical to that decapeptide. The sequence is well conserved throughout the vertebrates with only minor variations and the mammalian decapeptide has biological activity in all species of vertebrates studied.

That latest statement took me to China. When President Nixon and Henry Kissinger reopened relations with China 10 years later, one of the first practical results was some form of a cultural exchange program in which the United States gave China the names of 15 Chinese scholars—mostly mathematicians and physicists, as I seem to remember, whom we wished to invite here to lecture, and reciprocally, the Chinese gave the names of 15 American scientists whom they similarly wished to lecture in various centers in China. To my surprise, my name was on that list, my formal host being the Institute of Zoology from Academia Sinica. My wife and I went to China for about a month, a few months after the death of Mao as I remember it, and I lectured in quite a few places. On the opening day of my formal reception by my host agency I was given the explanation for this unexpected invitation: Chinese biologists, following a note by the group of Maurice Fontaine in Paris—which I had read, but with no further thought—had recognized that synthetic mammalian LRF would produce spawning and egg laying when injected into the coelomic cavity of the carps which the Chinese had traditionally grown in ponds as a major source of food protein. The carps never reproduced in captivity; thus, from time immemorial, farmers trekked each spring to the main rivers, sometimes hundreds of miles away, to collect smallfry, which they brought back to their ponds. The Chinese had built two large-scale synthesis facilities, one in the north and one in the south of China, in which they were producing kilograms of an analog (D-Trp⁶-desGly¹⁰-LRF) of the decapeptide originally reported by our lab as more potent than the native molecule and which they were distributing to these fish farmers. The carps could now be induced to reproduce in captivity; no more trekking to the Yang Tse or any other faraway river. Several of the Chinese biologists and chemists who had been involved in that episode came to my lab at the Salk Institute, subsequent to my visit to China. The Institute of Biochemistry, Academia Sinica, in Shanghai where I lectured for several days was indeed home to a group of remarkable chemists (who, by the way, had been the first to synthesize insulin in 1958–1959, before Katsoyannis in New York or Zahn in Austria). They had organized the large-scale industrial synthesis of the LRF peptide, at a time when we were only able to make milligrams by solid phase! The old director, Wang Yin Li, was still there and told me some extraordinary stories about their survival through the Cultural Revolution following his meeting with Mao Tse-tung and Mao’s wife when she understood that they were “synthesizing life” (insulin is indeed life-saving!), a unique feat of Chinese science that she decided must be left to proceed to show the world!

So, two novel polypeptides in the hypothalamus, unquestionably controlling secretion of pituitary hormones, had now been characterized. There was enough evidence that the decapeptide stimulated concomitant secretion of both gonadotropins LH and FSH, though with strange stimulus/ response times that would not be elucidated until 10 years later by the elegant studies of Ernst Knobil on the frequency of the pulsatile release of LRF by the hypothalamus as controlled by the suprachiasmatic nucleus. Cyril Bowers in New Orleans made the unsuspected observation that TRF would stimulate the secretion not only of TSH but also of prolactin, though there was a great deal of species variation (not very active in the rat, very active in humans, even more so in bovidae). There were two more pituitary hormones in search of their hypothalamic-releasing factor: ACTH and growth hormone (GH). As soon as the nature of LRF was ascertained, we synthesized large quantities of the peptide and started doing physiological studies in vitro and in vivo with the synthetic replicate. I decided that concomitantly we should start looking for the hypothetical growth hormonereleasing factor (GRF). Seymour Reichlin had shown in 1959 that lesions of the ventromedial hypothalamus in the rat would lead to animals that were obese but shorter than their age-controls. Their long bones were shorter and their tibial plate cartilage was 30–50% thinner than that of their agecontrols. Using the pituitary tissue culture method now fine-tuned by Wylie Vale and a radioimmunoassay for rat GH that a new Canadian post doc, Paul Brazeau, had reduced to practice, we started looking for evidence of a GH-releasing substance in extracts of fresh ovine hypothalamic tissues. To our surprise, the extracts would acutely inhibit the in vitro secretion of GH rather than stimulate it. After repeated and careful checking of everything in the experimental design and performance of the experiments, we had to conclude that the results were correct and could be interpreted only as evidence of some substance in the hypothalamic extract that would inhibit the secretion of growth hormone. There was nothing in the literature that would comfort this observation except for a short note by Lad Krulich and Don McCann that they had observed inhibition of GH secretion in the extract of some localized sampling-punches from the hypothalamus next to others that would stimulate secretion of growth hormone. In about a month we had isolated a peptide that accounted for all the inhibitory activity of the original extract. It had 14 amino acid residues, including 2 Cys. Its potency was on the order of what we had seen for TRF or LRF (i.e., in the low nanomolar range, with an exquisite linear log-dose/response relationship). In a couple of weeks Roger Burgus had sequenced it by manual Edman degradation, one residue a day, and simultaneously Jean Rivier was proceeding with the synthesis by the Merrifield solid-phase method. Both the linear and the oxidized form of the synthetic peptide had full biological activity at ≥1 nM. Both the native and the synthetic peptides inhibited the secretion of only growth hormone in the in vitro assay, not LH or TSH, and had similar activity in an in vivo model in which we were taking advantage of an old, though not well understood, observation that intraperitoneal injection of pentobarbital in rats elevated their plasma levels of immunoreactive GH. I then proposed the name somatostatin for this novel peptide (Science, Vol. 179, 77–79, 5 January 1973). We had, of course, realized the possible clinical significance of somatostatin, or one of its sure-to-come analogs, in the treatment of acromegaly and other pituitary adenomas and in diabetes, should the molecule be active in humans. It was active in humans, as rapidly demonstrated by Sam Yen at UCSD in lowering GH plasma levels in acromegalics; by Jack Gerich, Peter Forsham, et al., in San Francisco; and by Rolf Luft and Suad Efendic at the Karolinska in Stockholm, in dramatically sparing insulin in juvenile diabetics, in complementary multiple mechanisms that became obvious somewhat later.

We then started distributing aliquots of synthetic somatostatin to whomever asked for it, with, of course, no strings attached, except that we be kept informed of whatever results were obtained. One day, Wylie Vale got a phone call from Charlie Gale, a colleague physiologist at the University of Washington in Seattle who had early requested somatostatin to use in studies on growth hormone secretion in the baboon. Charlie Gale said that their animals had responded as expected in terms of plasma GH level but that all showed signs of profound hypoglycemia during the infusion of the peptide. A few days later, Gale called again and said that they now had evidence that infusion of somatostatin in their baboons dramatically lowered levels of plasma insulin and glucagon. That was all unexpected. We had never seen anything like that in the rat. I asked Sam Yen to check the plasma levels of insulin and glucagon in the blood samples of the acromegalics in whom we had injected somatostatin. All showed decreased levels of the two pancreatic hormones during infusion with somatostatin.

By that time we had generated in rabbits several batches of polyclonal antisera against somatostatin. The antibodies were of relatively low binding affinity. They would not lead to satisfactory radioimmunoassays but would probably be good enough for immunohistology. Puzzled by the observations of Charlie Gale, I started wondering whether somatostatin or a related peptide could be made by neurons in the vagus or other nerves with terminals in the pancreas. Simple calculations based on the known short half-life of somatostatin and circulation time and distribution volume made it unlikely that any peripheral (pancreatic) effect of somatostatin could be due to circulating levels of the peptides of hypothalamic origin. I sent some of these antisera to Maurice Dubois, at INRA (Institut National de Recherche Agronomique) in Nouzilly, France, asking him to see whether he could demonstrate somatostatin immunoreactivity in such peripheral nerve structures. A few weeks later, he called me on the telephone and in great excitement told me that the somatostatin immunoreactivity was, in fact, present not in nerve terminals but in every one of the so-called δ-cells of the islets, well known to morphologists, but for which no function or secretion had ever been attributed, in contradistinction to the β-cells (insulin) and α-cells (glucagon). This was independently observed and confirmed by Rolf Luft and Thomas Hökfelt in Stockholm. And there was soon no doubt that somatostatin could inhibit directly at the pancreas level, in in vitro preparations, secretion of insulin and glucagon. That was the first evidence for a peptide originally characterized in the brain, a neuropeptide, to be found in tissues other than the nervous system and showing biological activity there in relation to that peripheral source. Some years later we actually isolated and sequenced somatostatin of pancreatic origin and found it to be identical to the molecule from the hypothalamic origin. Soon thereafter, immunoreactive somatostatin was located by several groups (Besser and Hall in England) in specialized epithelial cells in the fundus of the stomach, the duodenum, the ileum, and at each and all of these locations, somatostatin could be shown to be biologically active in inhibiting whatever the local peptide or protein secretion would be. It also inhibited release of acetylcholine by the myenteric plexus, thus leading to inhibition of peristalsis. Immunoreactive somatostatin was also demonstrated in parts of the brain other than the hypothalamus, in particular, the brain cortex, as well as parts of the hippocampus. These observations led to the abandonment of the concept of neuropeptides, i.e., peptides specifically and exclusively of central nervous system origin. And it was soon recognized, primarily from the immunohistology work of Thomas Hökfelt in Stockholm, that every single biologically active peptide isolated earlier in the gut or the pancreas could be located in some immunoreactive form in the central nervous system-ubiquitous, yes, but not random. Each of these peptides has well-recognized mapping, recently confirmed by demonstration of their mRNAs by the new methods of molecular biology. Many neurons, particularly in the hypothalamus (paraventricular nucleus, supraoptic nucleus), have been clearly demonstrated to synthesize and release several biologically active peptides, along with a particular neurotransmitter such as noradrenaline, acetylcholine, or dopamine. To my knowledge, as per the writing of these pages in Spring 1997, the significance of this co-localization of peptides and neurotransmitter is still unclear, particularly as it relates to the presence of specific peptides in specific neurons (cortex, hippocampus, amacrine cells of the retina, etc). What has also emerged from these early observations is the multiplicity of receptors, in the central nervous system as well as in peripheral tissues, for these peptide ligands. It is thus difficult not to think that these peptides must have some role in the function(s) of the neurons they come from or have receptors for. I am confident that these roles will be elucidated in the future through the combination of the reductionism of molecular biology and good physiology. In fact, we know today that practically any biologically active peptide originally identified in the gut, the lungs, the heart, the skin can also be found in the CNS with highly specific mapping and distribution. And there are high-affinity receptors, on neurons, for these many peptides. I cannot believe that these peptides, for which, as I said above, we still do not know of a clear function in the CNS, are no more than phylogenic relics, as some have proposed.

Hundreds of thousands of analogs of these hypothalamic native peptides have been synthesized by now, both in academia and in industry. “Superagonist” analogs of the decapeptide LRF 1000 times more active than the native molecule and with longer half life, thus leading to rapid downregulation of their receptors, are now the treatment of choice for precocious puberty, a part of the treatment for uterine fibroids, endometriosis, some types of pituitary adenomas, and prostate tumors, in this case with analogs of somatostatin. The market for these molecules is currently several billion dollars world wide annually. Specific antagonists are being designed for these peptides, of experimental as well as clinical interest.

The isolation and characterization of the endorphins was an easy exercise, when compared to the previous years of anxiety. In the spring of 1975 I was invited to lecture on the current status of the hypothalamic peptides at the annual meeting of the Canadian Association for the Advancement of Sciences, in Winnipeg. After the lecture, my host, Henry Friesen, asked me what I thought of the recent report by that group in Scotland about a small peptide in the brain that had morphine-like activities. I had not heard of it. But I immediately perked up because: (1) we still did not know what the growth hormone-releasing factor was and (2) I knew that injection of morphine in humans as in laboratory animals was a powerful stimulant of acute GH secretion. Back at the Salk Institute, I searched the literature. There was essentially the still ongoing work of Sol Snyder and his group, Lars Terenius in Stockholm, Avram Goldstein at Stanford, and Eric Simon in New York, all dealing with their localization of opiates receptors in the brain; a statement from Goldstein’s group that they had actually been looking for an endogenous ligand to these opiate receptors but with no clear-cut results; and the papers from Kosterlitz’ group in Scotland who, indeed, reported purification of one or more small peptides (6 or 7 amino acid residues) which had opiate-like bioactivity in a couple of bioassays which I had never heard of (myenteric plexus of the guinea pig, contraction of the rat vas deferens). That endogenous ligand of the opiate receptor may, indeed, be our still-elusive growth hormone-releasing factor. I immediately decided to search for such a molecule in our inexhaustible supplies of side fractions from the TRF, LRF, and somatostatin isolations. I called Avram Goldstein at Stanford, told him of my intentions, and asked him whether he would agree to teach me the bioassay with the myenteric plexus of the guinea pig ileum which I knew he was using, along with his receptor-binding assay. Even though he knew I would become a competitor in the characterization of the endogenous ligand which he had attempted himself, as I said above, Avram immediately said with elegance and generosity, of course, to come anytime. A few days later, I had set up the bioassay in my lab at the Salk Institute, and within a month I had located several side fractions from extracts of hypothalamic tissues and of pituitary powders that, indeed, had powerful activity in the opiate bioassay, reversible by Naloxone. I soon realized that there were several zones of biological activity as the purification progressed using the novel methods of high-pressure liquid chromatography that Roger Burgus and Jean Rivier had just introduced in the lab, following the more classic ion exchangers and molecular sieves columns. It also became rapidly evident that the molecular sizes of the peptides I was isolating were much larger than what Hans Kosterlitz and John Hughes in Scotland were writing about, under the name of enkephalins. I decided to use the name endorphins for these larger peptides, a name which had been proposed earlier by Eric Simon for the still-unknown endogenous ligand that the studies on the opiate receptors were postulating. On December 31, 1975, Roger Burgus completed the sequence of the smallest of the three peptides I had isolated in homogeneous form by HPLC,⁵ a 16-residue peptide which I called α-endorphin because it was the first of three to be fully characterized. A week before, the day before Christmas, I had received the issue of Nature in which Hughes, Kosterlitz, Fothergill, Morgan, and Morris reported their identification of Leu⁵-enkephalin and Met⁵-enkephalin. They had noticed the similarity of their Met⁵-enkephalin to the sequence 61–65 of the molecule called β-LPH, a 91-amino-acid residues isolated from pituitary extracts years before by C.H. Li at Berkeley and which had always remained some sort of a mystery because it had no well-characterized biological activity except for a minor lipotrophic effect, hence its name. Amazingly, the sequence of α-endorphin contained Met⁵-enkephalin as its N-terminal and the extension 6–16 was identical to the sequence 66–76 of β-LPH.

I presented these latest results at the Harvey Lecture I delivered on January 8, 1976. The other two endorphins I had isolated were a 17-residue peptide, which turned out to have the same sequence of α-endorphin plus one Leu residue at the C-terminal, which I called γ-endorphin; and a 31-residue peptide, which turned out to have the exact sequence of 61–91 of β-LPH and which I called !3-endorphin upon some (friendly) forcing by C. H. Li, who wanted to be sure that that molecule would clearly be identified with (his) β-LPH of old. That whole field of opioid peptides exploded in the ensuing months and years with the recognition of the multiple opiate receptors δ, κ, μ; the identification of several other opioid peptides, some related to the endorphins (Matsuo’s neo-endorphins), the others unrelated, such as the dynorphins recognized and identified by Avram Goldstein and his group; and more recently several other molecular species, including the strange der-morphins with a D-amino acid as recognized by Erspamer and his collaborators. The nature of the precursor molecules of these opioid peptides is now totally clarified thanks to the powerful methodology of molecular biology. There was a flurry of excitement when Floyd Bloom and I injected β-endorphin in the cisterna of rat and produced dramatic catatonia, reminiscent, of course, of the clinical picture of hebephrenic schizophrenia. Early reports claimed disappearing of auditory hallucination of schizophrenics given Naloxone. Nothing of these clinical claims was confirmed. β-Endorphin, however, is undoubtedly a powerful analgesic agent in man when injected intrathecally or even by epidural location.

As soon as we had enough synthetic replicates of α-, β-, and γ-endorphins, I immediately tested whether they would stimulate the release of growth hormone, since that had been my early incentive for all that work. Indeed, they stimulated secretion of growth hormone in vivo, in the rat, as does morphine, but they were totally inactive in vitro in the pituitary monolayer cell culture assay. Endorphins were not the growth hormone-releasing factor still expected to be found in the hypothalamus.

The nature of the hypothalamic-releasing factor for growth hormone was not to be established until 1982 and in a totally unexpected way. Sometime in 1978 I decided that it was time to look again for that elusive GRF. By that time we knew about the several forms of somatostatin present in the hypothalamus, the 14-residue peptide we had first characterized, an N-terminal extended 16-residue peptide, and the 28-residue peptide first identified by Viktor Mutt in Stockholm in porcine intestinal extracts. We also had excellent radioimmunoassays for these somatostatin-related molecules so that they could easily be located in any extraction scheme of hypothalamic tissues. We also had good knowledge and practice of the bioassay, which would be the monolayer tissue culture of rat pituitary cells, combined with radioimmunoassay measurement of the growth hormone secreted in the incubation fluid. The residues/side fraction from the earlier extraction programs were now almost 20 years old; though always kept at ca. –20°C they were showing signs of proteolytic degradation. I then decided to obtain some fresh hypothalamus tissues and I signed a contract with a large supplier of laboratory rats to obtain 250,000 rat brains shipped frozen on dry ice to the lab. We purified GRF, well separated from several zones of somatostatin-related peptides, but we had major technical problems of instability of the GRF fractions which we could not reduce to homogeneity. In the fall of 1980 I gave a plenary lecture on the physiological regulation of somatic growth at the annual meeting of the French Society of Endocrinology in Paris, in the same room of the old Ecole de Médecine where in 1885 Pierre Marie had described acromegaly. I mentioned those rare cases of acromegaly in which no pituitary adenoma can be found but in which some peripheral tumor may function as an ectopic source either of growth hormone or of a growth hormone-releasing substance. Such a case had just been reported by Michael Thorner from the University of Virginia in which removal of a small pancreatic tumor had led to a decrease to normal of the blood levels of GH in an acromegalic patient with no pituitary tumor. Bioassay of the pancreatic tumor had shown it did not contain growth hormone. I told my audience in Paris that should they recognize such a case of acromegaly with a normal pituitary and observe a peripheral tumor (carcinoid, islet cell, lung tumor, etc.), that I would be interested in obtaining that tumor as a possible source of GRF. A few months later, Geneviève Sassolas, then a young assistant professor in the Medical School in Lyon, wrote me about such a patient. Fusun Zeytin from the laboratory at Salk went to Lyon, organized the collection of the tumor in the operating room, and was back in San Diego 2 days later with a large, grossly heterogeneous tumor removed from the pancreas of that patient. Assays showed that some regions were rich in somatostatin bioactivity, and others extremely active to stimulate release of growth hormone. In a few weeks, with Peter Bohlen, Paul Brazeau, Fred Esch, and Nicholas Ling, we had isolated, sequenced, and synthesized human GRF as a 44-residue, C-terminal amidated linear peptide along with two C-terminal truncated fragments, 1–37 and 1–40, with lower specific activity. Later that year we identified GRF from human brains and showed it to be identical to GRF 1–44(NH₂) isolated from the pancreas tumor. The synthetic molecule is highly active in man to stimulate secretion of growth hormone. Immunocytochemistry by Bernard Bloch located GRF neurons in a discrete region of the ventral hypothalamus (arcuate nucleus, ventromedial and lateral nuclei of the tuber) with rich axonal projections to the portal vessels in the median eminence. An extensive series of experiments ensued, leading to a clear understanding of the mechanism of action of GRF, its noncompetitive inhibition by somatostatin, its pulsatile secretion by the hypothalamus, cloning of its message and precursor, etc. That rare tumor as an ectopic source of GRF had led to solving in a couple of months what had been in limbo since the first observations of Reichlin in the 1950s and our early, repeated failures.

A couple of years earlier, the group led by my former student, then associate, then colleague, Wylie Vale, had solved a similarly frustrating quest for one of these hypothalamic peptides by isolating and characterizing CRF, the corticotropin-releasing factor from ovine hypothalamus. First shown to exist in 1955 by my laboratory in Houston and that of Saffran in Montreal, it was not until 1981 that CRF was identified as a 41-amino-acid residue linear peptide by Wylie Vale, Joachim Spiess, and Jean and Catherine Rivier from some of the fractions of our previous TRF, LRF, and somatostatin isolation programs. It is also to the credit of Wylie Vale’s group to have subsequently done the mapping of CRF neurons and CRF receptors throughout the brain and to have shown its profound effects, all triggered by exposure to stress, on the endocrine, immune, and autonomic systems, in a series of superb physiological experiments.

But I should soon close that accounting. I must however, mention the work that went on in the laboratory at the Salk Institute that led to our first identification, sequencing, and cloning of acidic and basic FGFs (fibroblast growth factors); the first isolation and characterization through molecular biology in collaboration with Genentech of inhibins, molecules which had eluded everybody for 50 years; the recognition that differential recombination of the α- and β-chains of that heteromeric molecule produces structures with opposite biological activities and which I called activins; and the recognition and final identification of the molecules called folliculostatins by Nicholas Ling, Shao Ying, and Shunichi Shimasaki. The two FGFs are now recognized to be major growth factors for neurons, certainly during embryonic life; they are actually synthesized and utilized through autocrine pathways by some neurons and in highly specific locations. For instance, in the hippocampus only neurons of the CA2 show by in situ hybridization mRNA for FGF and FGF receptors. The biological significance of these growth factors in the development, differentiation, repair, and aging processes of neurons throughout the CNS and the peripheral nervous system is now a major chapter in the neurosciences. Similarly, inhibins, activins, and follistatins originally recognized in gonadal tissues or fluids have now been located in specific mappings of the brain, along with highaffinity receptors. I am now quite incapable of following all that literature.

Sometime in 1977, about a month before the traditional December date, I received instructions on how to prepare the one-hour Nobel lecture I would have to deliver; about a week before the lecture I got a note informing me that the lecture would be 45 minutes; the day before the talk, when in Stockholm, of course, I was told that since Rosalyn Yalow, Andrew Schally, and I would lecture the same day, that each talk would be no more than 30 minutes. That was undoubtedly the most stressful talk I ever gave—I still remember the dry mouth—without notes, in 30 minutes. But I had kept the title: “Peptides in the Brain: The New Endocrinology of the Neuron” (see Science, Vol. 202, 390–402, 1978). And a few years later when I delivered the Walter B. Cannon Memorial Lecture (see The Physiologist, Vol. 28, 391–396, 1985), I titled it “The Language of Polypeptides and the Wisdom of the Body.” If things had changed and expanded from 1978 to 1988, today’s exponentially moving knowledge is giving us both insight and control, all the way to the genome, to realize that nervous systems, endocrine systems, and immune systems have ontogenic as well as phylogenic commonalities, to explain and lead to the integrated physiology we now recognize. Besides the wonderment as to how all that happened, how elegant so much of it is, is the additional rejoicing that so much of all this knowledge is now put to use rationally to cure diseases, to alleviate pain, and again to make us wonder at the brain—our brain.

Selected Publications

Baird A, Schubert D, Ling N, Guillemin R. Receptor- and heparin-binding domains of basic fibroblast growth factor. Proc Natl Acad Sci USA 1988;85:2324–2328.

Bloch B, Brazeau P, Ling N, Böhlen P, Esch F, Wehrenberg WP, Benoit R, Bloom F, Guillemin R. Immunohistochemical detection of growth hormone-releasingfactor in brain. Nature 1983;301:607–608.

Bloom F, Battenberg E, Rossier J, Ling N, Guillemin R. Neurons containing β-endorphin in rat brain exist separately from those containing enkephalin: Immunocytochemical studies. Proc Natl Acad Sci USA 1978;75:1591–1595.

Bloom F, Segal D, Ling N, Guillemin R. Endorphins: Profound behavioral effects in rats suggest new etiological factors in mental illness. Science 1976;194: 630–632.

Böhlen P, Brazeau P, Bloch B, Ling N, Gaillard R, Guillemin R. Human hypothalamic growth hormone releasing factor (GRF): Evidence for two forms identical to tumor derived GRF-44-NH₂ and GRF-40. Biochem Biophys Res Commun 1983;114:930–936.

Brazeau P, Vale W, Burgus R, Ling N, Butcher M, Rivier J, Guillemin R. Hypothalamic polypeptide that inhibits the secretion of immunoreactive pituitary growth hormone. Science 1973;179:77–79.

Burgus R, Butcher M, Amoss M, Ling N, Monahan M, Rivier J, Fellows R, Blackwell R, Vale W, Guillemin R. Primary structure of the ovine hypothalamic luteinizing hormone-releasing factor (LRF). Proc Natl Acad Sci USA 1972;69:278–282.

Burgus R, Dunn T, Desiderio D, Guillemin R. Structure moléculaire du facteur hypothalamique hypophysiotrope TRF d’origine ovine: Mise en evidence par spectrométrie de masse de la sequence PCA-His-Pro-NH2. CR Acad Sci Paris 1969; 269:1870–1873.

Burgus R, Dunn T, Desiderio D, Ward D, Vale W, Guillemin R. Characterization of ovine hypothalamic hypophysiotropic TSH-releasing factor (TRF). Nature 1970; 226:321–325.

Clayton G, Bell W, Guillemin R. Stimulation of ACTH-release in humans by nonpressor fraction from commercial extracts of posterior pituitary. Proc Soc Exp Biol Med 1957;96:777–779.

Courrier R, Guillemin R, Jutisz M, Sakiz E, Aschheim P. Présence dans un extrait de l’hypothalamus d’une substance qui stimule la sécrétion de I’hormone antéhypophysaire de lutéinisation. CR Acad Sci Paris 1961;253:922–927.

Cuevas P, Baird A, Guillemin R. Stimulation of neovascularization and regeneration of the rat sciatic nerve by basic fibroblast growth factor. J Cell Biochem Suppl 1987;11A:50, 194.

Cuevas P, Carceller F, Esteban A, Baird A, Guillemin R. Basic fibroblast growth factor (BFGF) enhances retinal ganglion cells survival and promotes axonal growth of rat transected optic nerve. Third Joint Meeting on Neurochemical Approaches to Understanding Cerebral Disorders, European Society for Neurochemistry, June 9–12, 1988, Copenhagen. [Abstract]

Emoto N, Gonzalez AM, Walicke P, Wada E, Simmons D, Shimasaki S, Baird A. Basic fibroblast growth factor (FGF) in the central nervous system: Identification of specific loci of basic FGF expression in the rat brain. Growth Factors 1989;2:21–29.

Esch F, Ueno N, Baird A, Hill F, Denoroy L, Ling N, Gospodarowicz D, Guillemin R. Primary structure of bovine brain acidic fibroblast growth factor (FGF). Biochem Biophys Res Commun 1985;133:554–562.

Gerich J, Lorenzi M, Schneider V, Kwan C, Karam J, Guillemin R, Forsham P. Inhibition of pancreatic glucagon responses to arginine by somatostatin in normal man and in insulin-dependent diabetics. Diabetes 1974;23:876–880.

Gospodarowicz D, Cheng J, Lui G-M, Baird A, Böhlen P. Isolation of brain fibroblast growth factor by heparin-Sepharose affinity chromatography: Identity with pituitary fibroblast growth factor. Proc Natl Acad Sci USA 1984;81:6963–6967.

Guillemin R. A re-evaluation of acetylcholine, adrenaline, nor-adrenaline and histamine as possible mediators of the pituitary adrenocorticotrophic activation by stress. Endocrinology 1955;56:248–255.

Guillemin R. The brain as an endocrine organ. Neurosci Res Prog Bull Suppl 1978; 16:25.

Guillemin R. Peptides in the brain: The new endocrinology of the neuron. Science 1978;202:370–402.

Guillemin R, Brazeau P, Böhlen P, Esch F, Ling N, Wehrenberg WB. Growth hormone-releasing factor from a human pancreatic tumor that caused acromegaly. Science 1982;218:585–587.

Guillemin R, Hearn WR. ACTH release by in vitro pituitary. Effect of pitressin and purified arginine-vasopressin.Proc Soc Exp Biol Med 1955;89, 365–367.

Guillemin R, Ling N, Burgus R. Endorphines, peptides, d’origine hypothalamiqueet neurohypophysaire à activité morphinomimétique. Isolement et structure moleculaire de l’a-endorphine. CR Acad Sci Paris Ser D, 1976;282:783–785.

Guillemin R, Rosenberg B. Humoral hypothalamic control of anterior pituitary: A study with combined tissue cultures. Endocrinology 1955;57:599–607.

Guillemin R, Vargo T, Rossier J, Minick S, Ling N, Rivier C, Vale W, Bloom F. β-Endorphin and adrenocorticotropin are secreted concomitantly by the pituitary gland. Science 1977a;197:1367–1369.

Guillemin R, Yamazaki E, Jutisz M, Sakiz E. Présence dans un extrait de tissus hypothalamiques d’une substance stimulant la sécrétion de I’hormone hypophysaire thyréotrope (TSH). Première purification par filtration sur gel Sephadex. C RAcad Sci Paris, 1962;255:1018–1020.

Henriksen S, Bloom F, McCoy F, Ling N, Guillemin R. β-Endorphin induces nonconvulsive limbic seizures. Proc Natl Acad Sci USA 1978;75:5221–5225.

Ling N, Burgus R, Rivier J, Vale W, Brazeau P. The use of mass spectrometry in deducing the sequence of somatostatin—A hypothalamic polypeptide that inhibits the secretion of growth hormone. Biochem Biophys Res Commun 1973; 50:127–133.

Ling N, Ying S-Y, Ueno N, Shimasaki S, Esch F, Hotta M, Guillemin R. Pituitary FSH is released by a heterodimer of the β-subunits from the two forms of inhibin. Nature 1986;321:779–782.

Mason A, Hayflick J, Ling N, Esch F, Ueno N, Ying S, Guillemin R, Niall H, Seeburg P. Complementary DNA sequences of ovarian follicular fluid inhibin show precursor structure and homology with transforming growth factor-β. Nature 1985; 318:659–663.

Monahan M, Amoss M, Anderson H, Vale W. Synthetic analogs of the hypothalamic luteinizing hormone releasing factor with increased agonist or antagonist properties. Biochemistry 1973;12:4616–4620.

Morrison JH, Benoit R, Magistretti PJ, Ling N, Bloom FE. Immunohistochemical distribution of pro-somatostatin-related peptides in the hippocampus. Neurosci Lett 1982;34:137–142.

Nicoll R, Siggins G, Ling N, Bloom F, Guillemin R. Neuronal actions of endorphins and enkephalins among brain regions: A comparative microiontophoretic study. Proc Natl Acad Sci USA 1977;74:2584–2588.

Oyama T, Jin T, Yamaya R, Ling N, Guillemin R. Profound analgesic effects of β-endorphin in man. Lancet 1980:i;122–124.

Parker DC, Rossman LG, Siler T, Rivier J, Yen S, Guillemin R. Inhibition of the sleep-related peak in physiologic human growth hormone release by somatostatin. J Clin Endocrinol and Metab 1974;38:496–499.

Shimasaki S, Koga M, Esch F, Cooksey K, Mercado M, Koba A, Ueno N, Ying S-Y, Ling N, Guillemin R. Primary structure of the human follistatin precursor and its genomic organization. Proc Natl Acad Sci USA 1988;85:4218–4222.

Vale W, Burgus R, Guillemin R. On the mechanism of action of TRF: Effects of cycloheximide and actinomycin on the release of TSH stimulated in vitro by TRF and its inhibition by thyroxine. Neuroendocrinology 1968;3:34–46.

Vale W, Grant G, Rivier J, Monahan M, Amoss M, Blackwell R, Burgus R, Guillemin R. Synthetic polypeptide antagonists of the hypothalamic luteinizing hormone releasing factor. Science 1972;176:933–934.

Walicke PA, Baird A. Trophic effects of fibroblast growth factor on neural tissue. Prag Brain Res 1988;78:333–338.

Walicke P, Cowan WM, Ueno N, Baird A, Guillemin R. Fibroblast growth factor promotes the survival of dissociated hippocampal neurons and enhances neurite extension. Proc Natl Acad Sci USA 1986;83:3012–3016.

Yen S, Rebar R, VandenBerg G, Naftolin F, Ehara Y, Engblom S, Ryan K, Benirschke K, Rivier J, Amoss M, Guillemin R. Synthetic luteinizing hormone releasing factor: A potent stimulator of gonadotropin release in man. J Clin Endocrinol Metab 1972;34:1108–1111.

Ying SY, Ling N, Guillemin R. lnhibins and activins. Structures and radioimmunoassays. Ann NY Acad Sci 1988;541:143–152.

¹The following 30-odd pages, with minor changes, are from a chapter entitled Pioneering in Neuroendocrinology 1952–1969, published in Pioneers in Neuroendocrinology, Vol. 2, Plenum Press, 1978; with permission from the publisher.

²There were already, at that time, good reasons to suspect that the hypothalamus should have neurohumoral control of all adenohypophysial secretions, not just of ACTH. Sid Levine and I tried for more than a year to observe whether the co-cultures with rat hypothalamus would lead to increased secretion of gonadotropins and/or thyrotropin as assessed by our simple bioassays. While there was always a trend of the numbers in that direction, no experiment ever yielded a statistically significant set of results. I have come back many times to these protocols and the experimental results. Nothing statistically defensible could have been interpreted in these results; nothing was ever published. The “trends” were absolutely correct, though it would take years to comfort them into facts and corresponding chemical structures.

³The published proceedings of that Tucson meeting make interesting reading for the historian of neuroendocrinology. One finds in it the extensive description by Schally and Arimura of their isolation of”GHRH” and its biological activity (pp. 208–226); the claims of FRF free of LRF activity (p. 248), both being proposed as polyamines (pp. 248–252): the claims of the isolation of MIF and MRF (rather, MSH-RIH and MSHRH) (pp. 171–183)—all from the laboratories of Schally. All turned out to be artefacts. There also is the paper with Burgus showing the isolation of ovine TRF (pp. 227–241) and the original figures showing its composition: 81.6% of the weight was accounted for in terms of the three amino acids His, Glu, and Pro; theoretical ponderal contribution of the amino acids for a tripeptide isolated as a monoacetate is 86%. Three months after our first note on the TRF activity of protected Glu-His-Pro-OH appeared, Schally was still concluding in 1969 that TRF was not a homomeric peptide and that the nonpeptidic moiety of the molecule of TRF (66% of its weight) was responsible for the biological activity of TRF: the ultimate proof of that conclusion, so said Schally et al. in J. Biol. Chem., Vol. 244, 4077, 1969, was that, indeed, all tripeptides composed of Glu, His, Pro had no biological activity. Schally had had such peptides prepared by the group of Merck as early as 1966. In fact, when Burgus and I became interested in the very same compounds, I wrote to my friends at Merck asking for these, only to be told that none was left because the whole lot had been given to Schally. I then wrote Schally asking for some small aliquots of these peptides, pointing out that this request and a cooperative response on his part would be not only in good scientific spirit but also for the best use of our taxpayers’ grant moneys. Schally did not see fit to go along with my request, with the excuse that “the FDA did not allow such transfers across state lines” (sic). The data on the homogeneity of our latest batch of ovine TRF reported by Burgus at the Tucson meeting, showing it to be a peptide composed exclusively of the three amino acids, had been obtained and definitely ascertained only a few days before the meeting. In view of the results published by Schally’s group, our new observation was obviously a turning point, of which Burgus and I fully realized the implications. We never considered not to reveal it at the Tucson meeting. But Burgus and I knew that time would be short for us, as soon as we had given it away. It was from Tucson that I made by phone my first request to the group at Hoffmann-LaRoche for the synthetic tripeptides since we had no knowledge at that time of how to synthesize rapidly enough even a simple tripeptide. The conclusion is inescapable that Schally and his collaborators never isolated TRF as a single entity, either in 1966 or later. I have previously said so in C. R. Acad. Sci. Paris, Vol. 269, 1870–1873, 1969; also in Vit. Horm., Vol. 29, 1–39, 1977. I do not doubt that their porcine TRF was probably obtained as a peptide practically free of other peptides; it was, however, so contaminated with other nonapeptidic side products that Schally was led to believe that the peptide in their TRF was not the principal component. These nonpeptidic components turned out to be classical contaminants, cellulose, dextran, myrystoleic acid, leached from the equipment used in the last stages of purification as finally recognized by Schally on p. 1103 of Biochemistry, Vol. 9, 1970, in a footnote acknowledging that their preparation of TRF was never better than 65% pure.

⁴What about the cost? Over the years (from 1953 to 1969) the funding ofmy laboratory at Baylor College of Medicine was almost exclusively by the National Institutes of Health (NIH), more specifically the National Institute for Arthritis, Metabolic and Digestive Diseases (NIAMDD), with a few tactically important contributions from the Ford Foundation, the Population Council, and the Markle Foundation. Making rather simple assumptions based on the budget ofmy own laboratory and what I was reading in newspapers in Houston, where Mission Control for the moon landing Apollo program was located (assuming that all work and expenses from 1953 to 1969 were necessary for, involved in, and responsible for the isolation of the first 1 mg of ovine TRF), I once calculated that that 1 mg of native, pure, ovine TRF made 1 kg of pure, native TRF, 2.5 times more expensive than a kilogram of moon rock brought back from the Apollo XI mission. Today the cost of synthetic TRF is a few cents per milligram.

⁵α-Endorphin was, to my knowledge, the first native peptide isolated by HPLC in its native, i.e., nonderivatized, form. That methodology, as we reported it, rapidly became routine everywhere for separating native oligopeptides and other molecules.

Ray Guillery

BORN:

Greifswald, Germany

August 28, 1929

EDUCATION:

University College, London, B.Sc. (1951)

University College, London, Ph.D. (1954)

APPOINTMENTS:

University College, London (1953)

University of Wisconsin School of Medicine (1964)

University of Chicago (1977)

Oxford University (1984)

Visiting Professor, University of Wisconsin School of Medicine (1996)

HONORS AND AWARDS:

Fellow of the Royal Society (1984)

Fellow of University College, London (1987)

Ray Guillery is best known for his detailed characterization of the structural organization of the mammalian visual system. This work has focused on the lateral geniculate nucleus, and on mechanisms underlying the development of structural peculiarities in the visual system of albino animals.

Ray Guillery

Yet, when all has been said, you never talk about yourself without loss: condemn yourself and you are always believed: praise yourself and you never are.

—M. de Montaigne, On the Art of Conversation, translated by M. A. Screech.

I think success is if you can walk up to a mirror, look at yourself, and say: Hey, I like you. (Laughs.) I don’t know, I don’t know, I don’t know. I really don’t know whether I like myself.

—Ben Green talking to Studs Terkel in American Dreams.

My Family

There is a strong line of biomedical research in my family. My father was a pathologist who had his first university appointment at Greifswald in Pommerania, where I was born in 1929, and where he had ambitions, never successfully fulfilled, to be a research scientist. He had trained as a pathologist at the Charité Hospital in Berlin, where, before their marriage, my mother had been a technician in the same department. In Greifswald during the 1920s he undertook some studies of cultured tissues. His father was an ophthalmologist who was trained as a physician in the German army and combined an active practice in Cologne with a serious research interest. He wrote on visual acuity; Gerald Westheimer and Heinz Wässle both knew of my grandfather’s work and asked how I was related when we first met. Heinz, many years ago, gave me a bound copy of my grandfather’s 1931 review on visual acuity. I like to imagine that it was written while we were visiting my grandparents in Cologne just before my parents’ divorce in that year. I was photographed sitting on grandfather’s lap; neither of us looks comfortable. The picture suggests that I was not yet house-trained. He was a formal man from a Rhineland Catholic family who may well have disapproved when his son married into a Russian Jewish family, and who must have been shocked by the divorce. My mother recalls him as distant, keeping the family at bay while he worked in his study.

Grandfather Guillery had married Maria Deiters, daughter of Hermann Deiters, music critic and biographer of Mozart, Beethoven, and Brahms. Hermann’s brother, Otto Deiters, had taught at the University in Bonn and worked in Bonn as a physician. He had trained with Virchow in Berlin, and in Bonn, influenced by Max Schultze, he undertook a series of studies of the nervous system and inner ear. His studies of the nervous system, published posthumously in a fine book in 1865, mark him out as an early, eminent neuroscientist, even though he was only 29 when he died. His greatest achievement was the first accurate description of nerve cells, complete with the axon and all of the dendrites (which were briefly called Deiters’ processes) carefully microdissected and accurately drawn. He also included detailed illustrations of astrocytes in the book, as well as a complete atlas of the brain stem.

On my mother’s side there was a medically qualified great aunt, my grandmother’s sister, who worked as a general practitioner in Berlin and looked after our minor ailments. My maternal grandfather had been a successful apothecary in St. Petersburg before 1917, but by the time I knew him in Berlin, Nazi policies had put him out of work, and he used to take us for long walks in the Tiergarten. I remember him on a few occasions, when we were in the country, taking us to look for mushrooms. He taught me that until you know what you are looking for, you cannot see it; a basic principle of microscopy and mushrooming.

After my parents’ divorce I lived with my mother and sister in Berlin and had no contact with my father and his second family. As a result, I did not learn much about my father’s side of the family until after I had started medical school in London. There I learned that the lateral vestibular nucleus was called Deiters’ nucleus (it still was!). My grandmother’s younger stepsister, Lisbeth Deiters, was a psychiatrist in Düsseldorf and one of the few of my German relatives who had still kept in touch with us after the war. So I asked her about Otto Deiters, and she wrote to me at length, sending me a copy of his book and a rare miniature photograph of him. Some years later (1965), shortly before she died, we wrote a brief note for Experimental Neurology about Otto Deiters.

I did not learn about my grandfather’s research until I was an undergraduate anatomy degree student and saw his name in Polyak’s book on the retina. I know I was intrigued to learn about these two relatives at the time, but no amount of introspection provides any hint that this knowledge seriously affected my career and served to turn me into a neuroanatomist with a strong interest in vision.

School Years

Before I started as a medical student at University College London in 1948 I had been to six different schools: one in Berlin, one in Switzerland, one in Holland, and three in England. Two of these schools gave me a solid basis for an independence of mind that was invaluable at the time, and that has served me well ever since. The first was in Berlin, where from 1935 to 1938, I attended the Rudolf Steiner school. This was about the only nonfascist school available to us, and it was being closed down by the Nazis. After my class was admitted there were no further admissions and ours was permanently the youngest class. My sister recently reminded me that toward the end of our time there, we were required to conform to Nazi salutations and sing Nazi songs, much against the inclinations of our teachers. Not only did the school stand out as firmly as it could against the evils of the time, but it also had profound views on education which must have influenced me significantly during those three years in ways I was then too young to appreciate.

Later, from 1940 to 1946, I went to a Quaker school in Oxfordshire. Here, again, I was being educated by people who were swimming against the stream: pacifists in the midst of World War II. The Quaker belief in the “inner light,” the individual’s own source for moral judgements, played an important part in our education at that time. It is difficult to evaluate now how this influenced me, and (of course) I kept no notes, but I have a clear sense that I owe to these two highly moralistic schools a sense of independence and purpose that allowed me to grow up from 1938 onward with only sporadic and limited parental guidance. During the war we were Germans in England, officially labeled “enemy aliens” and required to register as such. We grew up during a period of intense enmity, yet when the war ended, I was an adolescent who was able to think of himself, proudly, as English; I experienced more anti-German sentiments from my Swiss school mates in 1938 than I did during the whole of the war in English schools. I suspect that this period of my life produced in me a curious mixture: of being very serious about anything that I could learn, but ignoring almost all of it. I have never been able to relate very productively to accepted dogma or fashionable and exciting advances until (often too late) I had been able to work them into my own slow and personal view of what is important. All too often, as many of my students and colleagues will confirm, the baby in what I saw as dull bathwater never stood a chance.

Given that my mother, who was one of a very small group of German Quakers, was classified as Jewish by the Nazis, we left Germany very late. In the fall of 1938 my mother was warned that the police were planning to take away our passports, and within 24 hours our family left Berlin, each with a passport. Mine had a big J stamped on it, which had been crossed out by an equally large X because my father had been able to prove that his forebears, who had moved from France through Belgium in the previous four or five generations, had all been “Aryan.”

I know nothing about the preparations that my mother and grandmother must have made earlier. I can remember coming home from school one day to find everything had been packed. My sister had earlier been sent to a Quaker boarding school in Holland; my mother traveled to London, where she had a good friend (my godmother), who helped to get her a job as a housekeeper/nanny in North London, the only employment that was open to her; I was sent to Switzerland to be looked after by another friend of my mother’s. My grandfather had died earlier; my grandmother, who in 1917 had fled from St. Petersburg, now traveled to Paris to join her oldest daughter. Both were later to flee from Paris, and after the war settle in New York. My grandmother’s three sisters remained in Germany and all died there, two in a concentration camp in Poland.

I spent some months in Switzerland, amazed by the scenery after my urban upbringing in a Berlin block of flats. I lived in a large, square, vinecovered house next to Lake Zürich, went to school half-way up a steep hill behind the village, and at the weekends we would occasionally hike in the mountains. My first view of clouds from above still preserves its initial magic, even now that flight has made it almost banal. I rapidly, but temporarily, acquired the Swiss version of the German language. I had few friends in the school and was exposed to some bullying because the Swiss disliked the Germans. I was lonely, but not unhappy. The mountains, a beautifully hand-crafted model steam engine I was given for Christmas, and a chocolate factory in the next village along the shores of Lake Zürich, where a school friend’s mother worked, represent the highlights that I can readily recall of this brief period of my ninth year.

Soon after Christmas, early in 1939, it was possible for me to join my sister in the school in Holland. Classes were in English and German, and we gleaned a small knowledge of Dutch. The school was in an impressive “castle,” or manor, complete with moat. I was one of the youngest in the school; I had a sense that interesting things were happening around me, in the school and internationally, but never really found out what they were. I was confused and was not there long enough to form any clear impressions. At the end of the summer term we traveled to England to stay with my godmother in North London, meet my mother, and then briefly to join my mother, my grandmother, my aunt, and her young daughter in a vacation on the north coast of France in August. We returned to England a few days before the outbreak of World War II.

On September 3, 1939, the day the war started, my sister and I were scheduled to go back to Holland from England. Civilian shipping was canceled and we were left “stranded” in England. The family that employed my mother evacuated their children to Oxford where their uncle (Professor Carter) was professor of Botany. We stayed in their house briefly and I can recall large numbers of children playing complicated games in their seemingly large garden. When 45 years later we were looking for a house in Oxford, this same house was on the market, and the garden seemed a lot smaller. Certainly the house was too small for all of us in 1939 and my sister and I were sent to live with a family in North Oxford: an academic widow with two children slightly older than us. Here we learned about the English language and English ways of behaving. We did not then realize that we had entered a rare subculture: an Oxford academic family. The children’s playroom was called the JCR (junior common room). When we had eaten enough we were taught to say: “Thank you, I have had an elegant sufficiency,” and we were only allowed second helpings at meal times if we had made a significant contribution to the conversation. For me this was a great stimulus to help me learn to speak the new language. In the evenings we listened to the radio or were read Dickens and other classics. My introduction to the English language was a curious mixture of Christopher Robin, Alice, Swallows and Amazons, Dickens, a radio comedy program called ITMA, and Lear nonsense verses. I enjoyed learning the new language, was young enough to learn it fast and old enough to enjoy the new sounds and meanings. Colin Roberts, my godmother’s brother-inlaw, a classicist and fellow of St John’s College, took a gentle and kindly interest in my linguistic development, feeding me stories and rhymes when we met, including many limericks from among which “the young lady from Twickenham whose boots were too tight to walk quick in’ em” stood out for me. The waywardness of the rhymes and spellings had a great appeal after the formalities of the Germanic languages. My mother and sister never seemed to share my joy in these aspects of our new language.

We stayed with this family for a year. I went to a rather shabby preparatory school in North Oxford, where the pupils knew very little and where our teacher was convinced that Hitler would shortly win the war. He was very kind to me and another German-Jewish refugee, spoiling us in the belief (we thought) that if he was nice to the Germans, the Germans would later be nice to him. I spent a year in that school learning the language and little else. Then, thanks to the Oxford Quakers, I was able to go to a Quaker boarding school in Oxfordshire (Sibford School).

My sister stayed in Oxford for two years more and moved to a new home. This was the home of Professor W. E. and Mrs. Le Gros Clark, who had at the beginning of the war sent their two daughters to Canada for safety. He was the Dr. Lee’s Professor of Anatomy, she worked as a volunteer for the Oxford Refugee Committee, and they had a large house in North Oxford. As a result, I spent much of my school holidays in the Le Gros Clark home, although I had my suppers and slept in a nearby boys’ home that was entirely unappealing. However, I watched the rather silent and distant professor grumble his way through some parts of many days, and at the weekends there were occasions when I got to know him better.

He and I went off cycling in the country, and on one occasion we went farther afield by train to visit a model village, Beaconscott, halfway to London. The professor really enjoyed this. He took lots of photographs of the tiny houses and streets and let me watch later while he did the developing and printing in the department. He showed me his lab, including his animal house and some monkeys. These may just have been the monkeys he used to explore the possibility that each of the three pairs of layers in the primate lateral geniculate nucleus is concerned with passing messages about a different primary color on to the cerebral cortex (although I was probably just a little too late for them). The theory was wrong and was fiercely attacked in 1951 by Gordon Walls who used the opportunity to write a clear and beautifully concise summary of geniculate organization. Le Gros Clark told me in the 1950s that he was deeply hurt by this attack, but when later in the 1960s I became interested in the lateral geniculate nucleus I found that Walls’ book provided an extremely valuable and entertaining introduction to the problems of geniculate organization.

At the end of this period, during which I spent term time at school and the holidays between the Le Gros Clark’s home and a boys’ home, my mother, whose employment had so far been legally limited to domestic work, was able to find work again as a pathology technician. This was thanks to Ernst Chain who had known my godmother’s family in Berlin. Chain had a younger colleague (Edward Duthie) who was given the job of organizing the pathology department at the Northampton General Hospital. Most of the eligible technicians were in the armed forces by then, and Chain knew that my mother’s training in Berlin (under Lubarsch) must have been thorough. She went back to work as a technician in Northampton, and lived in a small flat where we could join her during the school holidays. Northampton is not very far from Oxford, and Edward Duthie not only ran the routines of the hospital lab, but also maintained an interest in some ongoing research projects. My mother was very impressed, and at second hand, so was I. I have no idea what the research involved, and I don’t think my mother knew much more. I believe it was after the work on hyaluronidase, and before Duthie’s involvement in the early days of penicillin research. I was able to visit the lab, see all the specimens in bottles, watch my mother sharpening microtome knives by hand, and see her cutting beautiful, even, long ribbons of paraffin sections. It was some years before I learned to appreciate how good she was at this.

At this time I was given a small microscope for Christmas, and to go with it, my mother prepared serial sections through a guinea pig embryo, stained with hematoxylin and eosin. Although I spent a lot of time looking at these very attractive sections, I had no real clue about identifying the parts. My education had not prepared me to look for knowledge beyond what was in a set school course. I suspect that time spent looking at these essentially mysterious sections helped to prepare me for my later career.

Sibford was not a scholarly school. It was set in beautiful Cotswold country. We learned to enjoy the countryside, and I learned much from a local farmer’s family where I stayed for one school holiday and where I visited during term time. They let me make butter, harness the horse (badly), and watch the pig-killing. The school did not expect its pupils to go to university and trained us accordingly. We all left at 16. Each subject was strictly limited. It was only in art, woodwork, and metalwork that one could strive for a perfection that was identifiable but beyond one’s reach. As a result, I had a serious ambition to make and design furniture. However, my mother was keen to see me go to university, preferably medical school. I made a poor effort to seek admission to an art school, but in the end, moved from Sibford to a grammar school, where I had two years to prepare for university.

I had been poorly prepared for the intensive two years of study in science I needed before taking the Higher School Certificate required for university entrance. This may have been a great benefit for me, because during those two years I had to learn to work hard and systematically, to catch up with the rest of the class in mathematics, physics, and chemistry. The biology was easier for me. It was taught by Malcolm Scott, who later taught in the Royal Veterinary College in Camden Town. He was informal, lively, and enthusiastic. Although he could be scathing when we did anything stupid, he tended to treat us as equals in a refreshing way. I was intrigued to meet him again quite recently when his wife, Patricia Scott, was given an award by the Research Defence Society during my spell as the honorary secretary of this organization.

University

In 1948 I borrowed £3 from my mother in order to pay the entrance fee for the London Intercollegiate Scholarship exam. As a result I won a scholarship to study medicine at University College London (UCL). My time as a medical student opened many new doors for me, but it took me a long time to realize just how lucky I had been to enter this particular academic environment. The first year, when I was commuting from Kew where my mother had a small flat, was intensive and hard work. At first I traveled by underground train and there had to read anatomy from an unillustrated text (Johnson’s Synopsis); anatomical illustrations would have shocked other travelers. Later, I cycled to save money, and then moved closer to central London. It was a joy to learn that so much new knowledge was spread out for me. It was not only the shiny pages of new textbooks such as the beautifully illustrated Maximow and Bloom histology text, it was also having the free run of the shelves of the Thane library. I took to browsing and reading rather indiscriminately, fascinated by the way in which different authors, most since forgotten by me, dealt with difficult problems of physiology and anatomy.

I was still surprisingly naive. Although we had a fine course oflectures and some outstanding teachers, my inclination was to rely on books, rather than people. J. Z. Young’s introductory lectures were a brilliant and original approach to the study of the human body, but I did not realize just how original until much later. Lovatt-Evans gave almost all of the lectures in the physiology course. He was lively and vastly entertaining. Bernard Katz gave the lectures on vision. He was erudite, very serious, and less easy to follow. He taught in some of the practical physiology classes and, on one occasion, admonished a student who was not doing the set experiment, but had Maximow and Bloom open at the section on striated muscle. The student was told to put the book away, and as an aside was advised not to take the histologists too seriously when they described the complex arrangement of striations they thought they could see with their light microscopes.

Keith Richardson taught the histology classes during the first terms of the medical course. He was tightly organized throughout. Not only did he start and finish each lecture precisely on time, but every sentence was a complete and elegant structure. During this introductory course and for many years at UCL thereafter I learned from him a respect for order and precision. It was through the histology course that I was particularly stimulated to take an interest in anatomy. Looking back now this is perhaps surprising. The lectures were not as exciting as many others, nor as original, but they opened doors for a completely ignorant student who had not yet been taught the importance of recognizing originality, or creativity. I think Keith understood his audience.

The neuroanatomy was very badly taught and most of us had difficulty understanding the basics or discovering that the subject might be interesting. I spent a significant part of my first summer vacation, when I was not holidaying in France or making some extra money as a temporary ward orderly in a small West London hospital, working through Ranson and Clark. That did stimulate my interest.

Visiting scientists during my early years at UCL included Sperry, Broom, Marie Stopes, Bargmann, and many others. The medical students were expected to attend. This filled the lecture theatre and gave a good impression, but occasionally left some puzzlement. At one time, Lorente de Nó spoke about the vestibular nuclei, showing slide after slide of (to the students) uninterpretable Golgi preparations, each much like the other. One slide went up and Lorente said “uppa-side-down.” The laughter that followed visibly annoyed the speaker. Heinrich Kluver spoke about temporal lobe lesions and showed movies of monkeys masturbating, something that the rather prim, though openly dirty-minded medical class was not ready for. By the end of my first year I knew that I wanted a career as a research scientist. My brief spell as a ward orderly had convinced me that I did not want to practice medicine. The way forward was to do well in the exams (the “2nd MB”) that covered the basic science subjects, and hope to gain another scholarship to support me for an extra, intercalated B.Sc. course in anatomy or physiology. I worked hard and did well and then had two interesting interviews, one with John Young and the other with Bernard Katz, suggesting that I work for a B.Sc. I chose to work for the anatomy degree (was Le Gros Clark’s early influence involved?).

The anatomy degree was an almost new course. Two years earlier, P. K. Thomas had taken this degree as a solo enterprise; now I was one of four medical students taking time out (four terms) of the routine medical course to learn about anatomy as a science. I think we, and our teachers, made the course up as we went along. It was difficult to see much planning but there was serious commitment and a developing sense of excitement about what we were learning.

The most important part of the course was a regular (once every week or 10 days) tutorial, with J. Z. Young. He would give each of us a couple of references and a subject (such as the pyramidal tract, the evolution of the hippocampal commissure, head segmentation, or Piltdown man), and then we would retreat to the library, read a great deal more, and produce an essay that could be read to the great man in about 15 minutes. And we did regard him as a great man and were suitably in awe of him. He would scrawl notes while we were reading, occasionally taking time out to answer an important telephone call, and then he would take the essay apart, often quite brutally. He would explain the biological and logical underpinnings of the subject and could do this even with subjects that were quite far from his own interests and background. I discovered later that compared to many anatomists, he did not know a great deal about the mammalian brain, but what he could do quite brilliantly was to show us how to think about it. It was this positive part of the tutorial, in which he convinced us that we had the capacity to generate some original thoughts and perhaps define some new problems, that almost always left a great feeling of achievement at the end of the tutorial, even though one knew well that one had written a pretty stupid essay.

We had “intercollegiate” lectures from professors in other London schools. Goldby on comparative neuroanatomy was serious, dull, and informative. Hamilton would lecture to a very small group of students on very early development, always after lunch. He would fix one with a fierce gaze, and the others would slowly drop off to sleep. Boyd was enthusiastic and highly specialized with a memorable collection of slides of early neural development. Cave was unscholarly with a well-honed collection of dirty stories, for which he had made a name for himself among London medical students. Amoroso taught us how to artificially inseminate a rabbit on one day and on the next collect the fertilized ova. He taught a small group of students of whom just one was a woman. He addressed almost all of his instruction to her, to her great delight. His charm compensated for Cave’s crudities.

The best lectures and seminars were those held in UCL. Hans Gruneberg gave us a set of lectures on genetics and Michael Abercrombie organized a course of almost embarrassingly informal seminars on development. At first we were rather lost as to what was expected of us or what exactly the seminars were about, but as the series proceeded we realized that Abercrombie was thinking through the topics during the course of each seminar and we began to be able to share his thoughtful approach.

Keith Richardson taught a very sophisticated, practical histology class, where perfection was always expected and could never be attained. Donald Sholl acted as a sort of avuncular figure who looked after us, supervised the practical aspects of our lab, taught us statistics, and even invited us to his home to meet his wife and three young children in a suburb in the far north of London. I remember being horrified at the feeding habits of a two-year-old.

The four terms passed quickly and served to convince me that I wanted a research career. I knew I had to work hard to win a scholarship that would support a postgraduate training. I enjoyed the course, hated the exams, which were surprisingly small-minded, but did well enough to win a scholarship and start on real research.

Starting a Research Career

At my first meeting with J. Z. Young at the start of my Ph.D. training, in 1951, he suggested that I do a study of bird cortex. I had already made up my mind to study the hypothalamus. It was attracting a fair amount of attention, it was clearly crucial in the control of the autonomic nervous system, W.R. Hess had won a Nobel Prize stimulating the hypothalamus and producing “affective” behavior, Stephen Ranson had investigated it physiologically and anatomically, and Le Gros Clark had written a book on it. Perhaps my bicycle rides with Le Gros did influence my career.

We discussed the options briefly, came to no clear decision, and I went off and started work on the hypothalamus. About six to eight weeks later I met J. Z. in the corridor and he suggested that it was time we discussed my progress. I went to speak with him and he suggested, as though he had just thought of it, that it might be a good idea if I were to work on the hypothalamus. We agreed, discussed strategy briefly, and then I was left largely to myself until I had the first draft of a thesis. At that stage he gave us enormous independence, for which I was grateful. He was willing to argue and discuss when we had something interesting, but the process of finding a suitable area of research was an important part of our research training. The view, widely held today, that good research should be addressing a “soluble” problem owes much to K. Popper and more to P. B. Medawar. The more realistic view, that some of the most important research one can do is to look in a challenging area, such as the brain, and there work to define a soluble problem, is a less fashionable view I learned from J. Z. Young. Solving the soluble problems is often far easier than finding them.

I had just two years for my Ph.D. I worked in a part of D. A. Sholl’s lab for most of the time, but on my own projects. He treated me paternalistically in a rather narrow way, but he encouraged me to attend seminars that A. J. Ayer held regularly. They were open to all, and outsiders like me could listen without having to expose their ignorance. The fast interchanges of incisive arguments were fascinating and in marked contrast to another exercise in logic I undertook at that time. I met regularly with Professor Woodger, Professor of Theoretical Biology at the Middlesex Hospital. Woodger would explain to me on a one-to-one basis his system of logic as applied to biology. I recall that he proved to me, conclusively, that if several species evolved from a common ancestor, then there must be intermediate forms. This did not seem a very enlightening conclusion to me, but I did not doubt then, nor do I now, that his careful, pedantic approach did help me to think clearly about biological problems.

During my first year I studied the structure of the nerve cells in the hypothalamus, using a variety of reduced silver and Golgi stains. I thought I had an interesting thesis topic when I found that histograms plotting the lengths of dendritic segments between branch points always showed marked, regularly spaced peaks, suggesting that there was a “unit length” for hypothalamic dendritic segments. Sholl, a trained statistician, made me plot more and more segments until the peaks disappeared. I have occasionally thought about returning to this project! Adding more animals, nonuniform in size, must inevitably have made the peaks disappear.

I was also starting to take an interest, then fashionable, in the extent to which one could establish quantitative relations between the number of cells in a relay, their input fibers, and their output fibers. This made more sense when the nerve cell was still considered as the unit of neural function than it does today. Now it would be difficult to define the units whose quantitative relationships might throw some light upon functional relationships.

The mamillary bodies, a part of the hypothalamus, were ideal for my quantitative study; the cell group is well defined, the inputs come in the fornix, and the output goes largely in the mamillothalamic tract, both welldelineated fiber tracts. So I started to count nerve cells and nerve fibers. This could have ended as a very dull piece of numerology, but I was lucky. I soon found that some of my sections of the fornix gave counts of 100,000 fibers, whereas others gave 200,000. Both came from the postcommissural fornix; the difference was disconcerting and could not be ignored. I worried at it for a while and then noticed that the lower numbers were nearer the termination of the bundle in the mamillary bodies, as though the fornix were losing half of its fibers on the way. This loss was present in rabbit, cat, and rat (later I found it in the monkey, too), and so, together with a very detailed review of much of the older German literature, I was able to put together a thesis before my two years had passed. I was offered an assistant lectureship in 1953 as my scholarship ended.

I was lucky to get that far. In 1952, when I was just starting on the counts of the fornix, I almost stopped that line of research. My sister persuaded me, now that I was a student of anatomy, that I should once more contact the Le Gros Clarks. I was hesitant, but wrote and was invited for tea. When I arrived, the professor, who had just returned from a trip to Australia, was still out in the Parks with two of his young research fellows, learning how to throw a boomerang. When they came in, I was introduced to Drs. Daitz and Powell, and we settled down to tea and talk about neuroanatomy. Daitz was studying the fornix and, among other things, was counting the fibers. This did not increase my self-confidence. Having chosen to work on the hypothalamus I should have expected some competition from Le Gros Clark’s team, but this was closer than I could reasonably have expected. I went away feeling low and doubtful about my thesis research. But I was committed, did not have much time left, and had to proceed with the planned research.

Not long after this, Daitz rather suddenly and, very sadly, died. I learned that he had been counting the subcommissural fornix, so my counts of the postcommissural fornix were complementary to his. Tom Powell took over this research and, very generously, suggested that we do the research jointly. This started a long and stimulating interaction with Tom Powell and before long with Max Cowan, who came to Oxford at about that time to do his thesis research. They would come to London or I would go to Oxford several times each year and our discussions of research projects proved extremely stimulating for me. At UCL at that time there was no one who had a truly expert knowledge of the mammalian brain. I could speak with Tom and Max, and very occasionally with Le Gros Clark, about almost any problem of method, or neuroanatomy, and learn something new. Often, at the end of our meetings I would feel very insecure. I was working alone, and slowly feeling my way into the subject. They had a head start, and Le Gros Clark’s broad knowledge and experience. Their production of papers in the mid- and late-1950s was impressive and, for me, intimidating. Many years later, Tom once told me that he found our meetings stressful, too. He was concerned because I had learned from John Young to ask interesting questions about the brain; that was something he envied and felt he had not gained from his association with Le Gros Clark.

At the end of my Ph.D. training I no longer had the exemption from military service provided by my student status. My upbringing as a Quaker had taught me pacifism and I had registered as a conscientious objector, and so at the end of my training, I had to attend a tribunal. To my surprise, John Young came to support me in this. He also played an important role in helping me to make the decision not to finish my medical training. I received a great deal of advice to stay in medical school from almost all of my colleagues (and even from my father, a distant figure who wrote me stilted, formal German letters, and had earlier advised me that I could not get into medical school because I had no Latin). I was told that I could not expect to have a successful career without a medical qualification. John Young’s support of my career at that point was crucial. He pointed out that if I wanted to study the brain, the three to four years needed to become medically qualified would probably help me very little. He said (I was 24 at the time) that the next three or four years were likely to be my most productive and I should be careful not to waste them. I took his advice, have never regretted it, and am still grateful for it. I don’t think I gave any consideration to the very short professional life of great-granduncle Deiters, but perhaps I should have.

Assistant Lecturer and Lecturer at UCL, 1953–1960

Once I had an appointment on the staff of the Anatomy Department I felt a sense of freedom I had never known before. Although I still had to work for tenure, I thought I stood a reasonable chance and was not overly worried about finding some other employment if I should fail. I had essentially complete freedom in my choice of research, funding was no problem because all I needed in the way of glassware, chemicals, animals, and other material was provided without question, by the department. I was given a small lab where I could do more or less as I liked. Also, for the first time in my life I was no longer constrained in my personal finances. I was making an income of £450 per annum. I moved into a small flat in Old Compton Street in Soho.

Previously, I had lived in a single room in a large house in Gloucester Terrace overlooking the goods yard of Paddington Station. There was noise and soot from the steam trains, but the rent was only £1 a week and there were four other medical students in the house who provided agreeable company. Three were from St. Mary’s Hospital, which was close by. After I moved I kept up with my friends from St. Mary’s and through them, met another St. Mary’s medical student, Margot Pepper. She agreed to become my wife in December 1954, and joined me in the Soho flat for the first stage of 30 years of a very happy marriage. She was completing her medical degree while I was getting a start on my research.

My first project grew out of my thesis. I had to find out about the fibers that left the fornix on the way to the mamillary bodies. The fornix fibers are extremely thin and the techniques available then did not allow me to trace any of them. Fortunately, at that time Walle Nauta had developed a stain that would reveal very fine degenerating, unmyelinated fibers. The method was published in 1954, but earlier than that, Bill Hayhow, who was visiting from Australia and studying the lateral geniculate nucleus, had got hold of a cyclostyled copy (photocopying was not yet available) of the method. With this new method I was able to trace the fibers from the fornix to the anterior thalamic nuclei. I started to write the paper, and as I was close to finishing, Walle Nauta himself visited the department. I showed him my results and he very quietly and very charmingly told me that he had found the same thing and had already submitted the paper to the Journal of Comparative Neurology. That was not good news, but good science bears repeating. I finished writing and then submitted my paper to the Journal of Anatomy, where we published then. The Journal of Comparative Neurology had a publication delay of nearly two years and the Journal of Anatomy took about a year; so both our papers appeared in 1956, and Nauta never claimed priority.

Nauta had developed the method primarily because he had been interested in studying the fiber pathways of the hypothalamus. It was important to define how the hypothalamus is connected to the rest of the brain, and the new method provided a fine opportunity for exploring this. It never occurred to me that my next project, a study of the fiber pathways of the hypothalamus, would be likely once again to coincide with Nauta’s research plans and that he was likely to be way ahead of me; or perhaps it did occur to me, but I was too brash to worry.

I started to make small lesions in the hypothalamus in rats and cats, often using a difficult ventral approach in order not to damage other parts of the brain, and traced the degenerating fibers that connect this small part of the brain to the rest of the central nervous system. I had to teach myself the surgical approach from books and practice dissections. There was no help to be got from colleagues in the department. Once, when I was working on the approach through the soft palate in a cat, Lodvick Evans, a more senior colleague, stopped by and watched me struggling for a while. He asked what I was doing. I told him; there was a long silence, and then he said, in his strongest Welsh accent, “If I were you I’d go through the rectum,” and left.

I learned quite a lot about the pathways that go through the hypothalamus, especially the medial forebrain bundle, which links the hypothalamus to the mid-brain and the septum, but also about the fornix and the mamillary bodies. I was able to publish the results in the Journal of Anatomy again, and one paper, which appeared in 1957, later became a citation classic. I had been lucky to have been able to exploit an entirely new method on a part of the brain that was of interest to a great many people. I had spent a lot of time earlier trying to stain the fine fibers of the hypothalamus with various old silver methods. They all produced interesting results but none revealed fibers so that one could trace them reliably through the very dense fiber meshwork of the hypothalamus. The Nauta method was a very significant advance and for the next 10 to 15 years it provided a new way of studying the pathways in all parts of the brain. At national meetings in the United Kingdom and the United States papers based on the method tended to dominate, until the electron microscope took over, and I can remember colleagues complaining in private about the “Nauta bandwagon.” The method became available to me just when I needed it and when it was still very new. Because I had tried so many other methods, I was ready to exploit it as soon as I heard about it.

My entry into electron microscopy was more delayed. University College London had one of the earliest and finest electron microscopy labs in the country. This was thanks to John Young’s foresight. He brought Dave Robertson over from the United States and set him up in what seemed to us at the time a very extravagant lab. It was to last a long time and served to train many successful electron microscopists. One of the first of these was George Gray, whose classification of cortical synapses and description of the dendritic spines as postsynaptic specializations will long stand as major achievements.

I knew George well at this time (in the late 1950s). We lived near each other north of London, and his oldest son was much the same age as ours, so at weekends we would take the children for country walks and George and I would talk shop. He tried hard to persuade me to take up electron microscopy, telling me of all the great things there were to be discovered. My reaction was rather negative because I had a program of study which, at that stage, simply was not asking any fine structural questions. I did not want to make up new questions just so that I could use an exciting technique that was rapidly becoming fashionable. However, it wasn’t long before a question presented itself.

Brian Boycott and I were studying lizards and found that our neurofibrillar silver stains showed up some curious structures in the brains that were present when the animals were kept in the cold but not when they were kept warm. The electron microscope was the ideal tool for looking more closely at these structures. Some of the structures we were seeing were like the classical ring-like, neurofibrillar terminal boutons that Santiago Ramón y Cajal and others had described as characteristic of some, but by no means all, synaptic junctions. Oddly, such ring-like structures are not seen in cerebral cortex and other regions that are densely populated with synapses. We found that the neurofibrillar structure was formed within the synaptic terminals by bundles of neurofilaments. The classical neurofibrillar methods showed this cytoskeletal element of the synapses; they did not show the whole of the terminal. These conclusions raised some historically imporant points about early views of synaptic structure and also proved critical for the interpretation of fiber degeneration at synaptic terminals. However, they were very difficult for many colleagues to understand and accept, and did not lead to general acceptance. The issues became unimportant as better methods for tracing fibers and studying synaptic relationships became available. For me, these observations served as a useful introduction to electron microscopy of synaptic structures and of degenerating fibers.

A Sabbatical Break, 1960–1961

By 1959 I had spent six years on the staff of University College. I had been heavily involved in the teaching of the B.Sc. students and in all parts of the medical anatomy course; my research on the fiber pathways in the hypothalamus and thalamus and my new interest in electron microscopy all seemed to be going well. I started to think about taking a sabbatical break, preferably in the United States. Tom Powell had just come back from a very successful period at Johns Hopkins University, where he had worked closely and productively with Vernon Mountcastle. He had been particularly impressed by Jerzy Rose, and strongly advised me to go and work with Jerzy, who had just moved to the University of Wisconsin at Madison, to join Clinton Woolsey. We now had two young sons and a third on the way. Finding funds that would suffice to support the whole family was not easy.

I applied for a Rockefeller Travelling Fellowship, and was interviewed at the Medical Research Council by a panel that included Dale and Hodgkin. They were unreasonably kind to me. Hodgkin congratulated me on my publications even though the list must have looked extremely thin to him, and they awarded me the Fellowship. When Jerzy found out how much money the fellowship paid he immediately arranged to add a significant sum to it. Jerzy was very considerate of such things. Unfortunately, the Rockefeller people would not allow that, threatened me with horrible tax problems, and I had to give the money back.

The plan in my Rockefeller application was to look at a thalamocortical relationship that Rose and Woolsey had just described and labelled as “sustaining projections.” Whereas the classical description of the thalamus, based on the studies of Le Gros Clark, Earl Walker, and Rose and Woolsey had each major thalamic nucleus going to one area of the cerebral cortex, Rose and Woolsey now proposed that a single thalamic nucleus might project to more than one cortical area. This was (and still is) an extremely important change of view, and it seemed to me that the Nauta method might be suitable for demonstrating some of the these postulated dual projections. So I went to Madison to undertake a Nauta study; but it was not to be.

Jerzy Rose was moving away from anatomical problems to physiological problems concerned with hearing; Woolsey had a very old nine-channel oscilloscope that had never been properly exploited that he wanted to use, so I was encouraged to join them in a project that would look at thalamocortical pathways by stimulating thalamic cells and recording evoked potentials in the cortex with nine surface electrodes at once. I did argue in favor of the (to me) much more promising Nauta method and Woolsey agreed to let me try the method. However, he was at that time in the middle of a project (he was usually in the middle of several projects) on pathways linking separate lobules of the cerebellum, and we agreed to give the method an initial trial on the cerebellum. Anyone who has tried mounting frozen sections of the cerebellum will know that I had a difficult problem. Each separate lobule gets twisted in processing and has to be teased out as the section is mounted on a glass slide.

My chief problem, however, was that almost every available surface in the histology lab was devoted to cutting and staining the Nissl sections that the lab depended on at that time. There was no space for my silver staining. Woolsey found a surface where I could work but it was a long way from running water and a sink; these have to do heavy duty for the Nauta stain. I had to carry my staining dishes back and forth across the corridor. I got the sections stained, mounted them, and was rather pleased with the result. However, when I came in the next morning, I found Clinton Woolsey on his hands and knees trying to clean some small(ish) silver nitrate stains I had made on the floor between the labs. The stains didn’t come out; silver nitrate stains don’t. We said no more about the cerebellum or the Nauta method, and I rather wasted the rest of my year stimulating the thalamus and recording the evoked potentials nine times faster than anyone before; at least during the relatively brief periods when all nine channels of the oscilloscope were working.

Although the experimental work I did during that year was almost worthless, in the long run the year was not wasted. I learned how other people thought about the nervous system, not only in Madison but in several labs which I was able to visit briefly, including Palay’s, Bullock’s, Mountcastle’s and Poggio’s, Nauta’s, Pinckney Harman’s, and F. O. Schmitt’s. In Madison, Jerzy Rose was always willing to argue, sometimes perversely just to have an argument, but often instructively, and during the year I learned much from him. He was unusually stubborn. The first time I met him he took me into his office and showed me some really very poor silver stains. He was new to silver staining at that time. I looked at them, listened to his arguments, and then commented that I thought the staining was too incomplete for his conclusions. This was tactless and stupid, even though I had by then spent nine years with silver stains of various sorts. Rose’s reaction was controlled incandescence, and it was more than two hours before I got out of his office. Jay Goldberg, who was waiting to see Jerzy about another matter, was surprised that my first visit should have taken so long. He laughed when later I told him what had happened. In spite of this start, Jerzy always treated me with great generosity and patience.

Jerzy taught us to be extremely critical and circumspect. He had thought deeply about neuroanatomy and was able to pass his wisdom readily to others. He wrote discussions that carefully circumnavigated every possible objection or problem. It was hard to catch him out, but he had extraordinary blind spots. He refused to believe that the corticospinal tract of rodents travels in the posterior columns, and needed a lot of persuading that red blood cells of birds have nuclei; he insisted that all the cells he was seeing in sections of a pigeon’s brain were white cells indicative of infection. He was completely unconvinced when we once tried to persuade him that dandelion did not rhyme with perihelion.

Back to London (1961–1964)

When we returned to London I was keen to get back to electron microscopy. George Gray and I continued our studies of neurofibrils by looking at nerve cells of the leech which were known to have unusually coarse fibrils, and by looking at degenerating nerve fibers in several species in situations where the neurofibrils were known to increase. Peter Ralston came to University College with previous experience of peripheral nerve stains. He and I studied the Nauta stain with the electron microscope to show that the method did stain synaptic terminals, a point denied by many at the time, possibly due to the poor quality of their preparations, but perhaps just a misinterpretation of the sections. Marc Colonnier was then studying the visual cortex with the electron microscope and he and I initiated a study that was to change my career and give it a sense of direction it had previously lacked. In the cortex, many of the incoming fibers form synapses on slender dendritic spines. When Marc cut the incoming fibers and studied their degeneration he found that some of the spines were shed, but that the postsynaptic nerve cell itself seemed unaffected. This was in marked contrast to what was then thought about the monkey’s lateral geniculate nucleus, where Glees and Le Gros Clark had earlier described incoming retinal axons making rather large, one-to-one synapses directly on the cell bodies of lateral geniculate cells. When the retinal axons are cut, the geniculate cells show quite marked degenerative “transneuronal” changes and, in addition, the retinal axons show a dramatic neurofibrillar increase, which the cortical axons never show. We thought we would use the electron microscope to compare the two situations and learn more about the details of the degenerative changes, hoping especially to understand the basis of the transneuronal changes at the simple geniculate synapse and possibly relate it to the neurofibrillar changes.

At that time we were still fixing tissues in osmium tetroxide, and it was not until we started to use aldehyde fixation that we began to get acceptable preparations of the geniculate. We were amazed by the synaptic complexity of the nucleus. The simple one-to-one synapse was not to be found. We published an account of our results, showing the complex relationships of retinal axons with other synaptic structures. Our paper appeared shortly after J. Szentágothai had published a detailed account of geniculate structure. He wrote me and commented on the fine quality of our pictures but pointed out that we had made a mistake about the polarity of some of the synapses formed by the retinal fibers. These fibers had to be postsynaptic to other axons in the nucleus so that experimentally observed depolarization of retinal fibers could be explained. This had been observed by several groups after repetitive firing of optic nerve fibers, and interpreted as “presynaptic inhibition” in accordance with J. C. Eccles’ observations in other parts of the brain. Our preparations showed the retinal fibers as presynaptic, and so they have subsequently proved to be. It is always a mistake to make the anatomy fit the physiology. If it does fit, that is encouraging. If not, then there is a problem to be solved, and it was my interest in this problem that later led me into a detailed study of the lateral geniculate nucleus. The problem is not really resolved yet. Probably the depolarization of the retinal axons is due to the accumulation of extracellular potassium. The retinal axons end in unusual synaptic complexes called glomeruli, within which astrocytic processes are rare. In most parts of the brain astrocytes are next to synapses and serve to mop up extracellular potassium. The structure of the glomeruli (not the synaptic polarity) may well be responsible for the depolarization seen in the optic nerve fibers, but the possible functional significance of these relationships remains unexplored.

I enjoyed my time back in London. In 1961 Le Gros Clark had offered me a position in Oxford but because this would have meant a salary drop I stayed at University College. In 1963 I was promoted to a Readership, which made my career look secure. However, it also made me look critically at the future. There were no significant challenges ahead, except for possibly heading an anatomy department somewhere, which I was then not inclined to do. I was receiving job offers from the United States and started to look at those seriously. D. Bodian invited me to Johns Hopkins, and Al Berman, who had moved from Woolsey’s group to the Anatomy Department at the University of Wisconsin, was urging me to join that department. Margot was working part-time as a general practitioner and our daughter, Jane, was born in 1963. Career opportunities for both of us looked more promising in the United States and after long consideration, preparing lists of pros and cons, and finding the pro list much the longer, we decided to move back to Madison. I tried to finish my major research projects, wrote a long review with George Gray on synaptic structure, closed the chapter on the leech, taught the last group of B.Sc. Anatomy students, 12 of them, and stayed just long enough to see the exam list, headed by Semir Zeki.

Madison, 1964–1977

The time I spent in Madison was perhaps the most productive part of my career. We lived a short walk from the lab and the schools, and the children grew up to think of Madison as home. Margot worked part-time in the nearby University Health Clinic and when the children were older she started a residency in dermatology. Over the years I was joined by a series of stimulating neuroanatomical colleagues. Max Cowan joined the department in 1966 and when he left Semir Zeki came for a year, followed by Peter Ralston. I had superb technical staff, Grayson Scott taking charge of the electron microscopy and Elaine Langer of all of the light microscopy and photography. I participated in the teaching of neuroanatomy to medical students and developed a course for graduate students, early on working on this with Max, and later with Semir, and then Peter. I enjoyed this teaching, and spent the whole of my 20 years in the United States without teaching any of the other subjects that I had been trained to teach at University College: no gross anatomy, no histology, no embryology. To some extent I missed this, but there were too many other things to do at the time for me to have serious regret.

When I came to Madison I wanted to look at the problem that Szentágothai had raised about presynaptic inhibition. This had been demonstrated in the spinal cord, in the posterior column nuclei, and in the lateral geniculate nucleus. I wrote a grant application proposing to look in the geniculate and posterior columns, to compare the two situations. The grant was funded but the geniculate part of the work proved so complex and rewarding that I never properly explored the posterior columns.

It was clear to me that the knowledge we had of the lateral geniculate nucleus was surprisingly incomplete and, in places, either muddled or wrong. I tried hard to arrive at a more “complete” view of the nucleus, including its laminar structure, the structure and origin of its afferents, and the fine structural details of synaptic arrangements in the nucleus. Peter Ralston was looking at the ventrobasal thalamic nucleus at the same time and the similarities between his results and mine gave strong support for the view that there is a “general pattern” of organization that characterizes the thalamus, a view that also came out of the work being done concurrently at Oxford by Tom Powell and Ted Jones.

At this time I was primarily a descriptive anatomist, a term that is often, especially in grant reviews, linked with “merely,” as though the work were easy or unnecessary. The important roots of neuroscience in accurate descriptive accounts are often overlooked, and the joy of arriving at a reasonably accurate and lasting description of a structural relationship is not as widely appreciated as perhaps it should be. It was a chance observation made in 1968 that was before long to take my research in a new, and quite unexpected, more interpretative and experimental direction.

I was looking at the laminar structure of the cat’s lateral geniculate nucleus, puzzled by the reports that the cat has three geniculate layers, two innervated from one eye and only one from the other. I was pleased to find a small extra layer of fine fiber degeneration, making the score two-all. It became clear that earlier accounts of three layers of fiber degeneration, called A, A1, and B, had been based on inadequate Nauta stains and a confusion about what exactly was to be called layer B. In order to cut through the muddle I described the layers as A, A1, C, and C1 (A and C receiving from the contralateral eye, A1 and C1 from the ipsilateral eye), dropping B into limbo. This upset many people, and still leaves newcomers wondering about what happened to B. It pleased me to have two layers connected to each eye, even though they weren’t matched in size or in structure. But the pleasure was not to last. It wasn’t long before Terry Hickey, with the more sensitive autoradiographic method found yet another layer, C2, making the score 3–2. We still don’t have a clear idea about exactly what the lateral geniculate nucleus is doing for one eye that it doesn’t do for the other.

During the course of these studies, one cat showed an unusual laminar structure. I was puzzled by this until I saw in my notes that it had been a Siamese cat and recalled that Siamese cats are commonly cross-eyed. A second Siamese cat showed the same abnormality. It did not take long to find that all Siamese cats are abnormal: many of the fibers that would normally take an uncrossed course from the eye to the lateral geniculate nucleus, instead take a crossed course. The complex implications of this relatively simple abnormality are intriguing. We can ask about the developmental mechanisms producing such an abnormality at the optic chiasm (the site of the partial crossing). The answer is not yet clear. We can also ask about the visual capacities of an animal that receives part of its visual input as a mirror reversal of the normal; and we can make some instructive comparisons between normal and Siamese cats in their reactions to visual deprivation. Jon Kaas and I looked at many of the electrophysiological problems, and Vivien Casagrande and I studied some of the visual behavior of normal and visually deprived Siamese cats. The implications of these studies are not easily summarized. They showed that nerve fibers, even when they take a wrong route, can still make the topographically correct connections on the other side of the brain. More surprisingly, they showed that in some cats, the abnormal messages from the lateral geniculate nucleus are suppressed in the cerebral cortex, whereas in other cats, the pathway going from the lateral geniculate nucleus corrects the aberrant mirror reversal. This took some working out because David Hubel and Torsten Wiesel had reported the second sort of cat (correcting), and all our cats were of the first sort (suppressing). Because each result implied different anatomical connections, we undertook the anatomical studies and were lucky that after studying 10 cats that all matched the suppression, we found one that matched the correction. We named them “Boston” and “Midwestern” pathways, respectively, and the terms were so apt that they stuck.

These observations opened many new doors. Siamese cats represent a form of albinism and it became evident quite early that all mammalian albinos have the same sort of chiasmatic abnormality. The results started my interest in the visual pathways of albinos, in the development of the optic chiasm, and also in the development of the thalamocortical pathways which had demonstrated their remarkable capacity to adapt to the abnormal inputs by correcting the pattern of the pathway that goes to the cerebral cortex.

One interesting outcome arose from my (private) speculation that the Siamese cat might provide a useful model for studying binocular competition. In a normal mammal each hemisphere receives inputs from two eyes, and these inputs are arranged so that they match retinotopically, allowing single cortical cells to receive from a single point in visual space through the left and the right eye. Wiesel and Hubel had been studying the effects of early visual deprivation in one eye, which produces blindness in the deprived eye and corresponding cell shrinkage in the parts of the lateral geniculate nucleus innervated by that eye. They had good but indirect evidence that the deprivation acts by upsetting a competitive balance that characterizes normal development and normally allows both eyes to develop equal access to the appropriate part of the cortex, each eye connecting to cortex through one of two competing geniculocortical pathways. Because most of the representation of vision in one cerebral hemisphere of a Siamese cat comes from one eye only, it seemed to me that one could test the competition hypothesis, since there should be no competition in the large monocular part of the Siamese visual pathway.

I needed to raise some Siamese kittens with a monocular lid suture in order to make this test. I got three young Siamese cats, two female and one male, and waited for them to mature and breed. They took forever. At the end of about a year or more I suddenly realized that I had been stupid. And it was sudden, and rather exciting. A normal cat has a part of the visual pathway that is monocular. We all do. If you shut one eye, the part of the visual field that you lose is monocular, and this monocular part of the visual field has its own representation in a well-defined part of the lateral geniculate nucleus and cortex. There could be no competition in this part of the system. The situation had been well summarized by Gordon Walls in the book he had written about the lateral geniculate nucleus and Le Gros Clark’s color experiments. So now I realized that if a monocular suture acted by upsetting the competitive balance in the geniculocortical pathway, in a normal cat the monocular segment of the pathway should be spared. Why hadn’t Wiesel and Hubel seen this in the lateral geniculate cells of their cats? And why hadn’t I thought about it earlier? When I looked at the Wiesel and Hubel paper the result was obvious in their illustrations: the monocular segment was spared!

Deciding on the next step was not easy. A theoretical paper based on the published photographs would probably be ignored even though the logic was compelling. One needed some measurements to make a convincing case. Dennis Stelzner and I raised three kittens with monocular lid suture, then prepared the sections and measured the cells. It was months before we had the results, and naturally I was sure that an idea as obvious as this one could not be ours alone. But it was. We published the result and convinced many people. I was able to exclude other explanations later by further experiments, and with Murray Sherman, was able to show that in any monocular part of the visual field (naturally occurring or experimentally created) there is sparing, not only of the geniculate cells but also of visual capacity, which is lost after monocular deprivation for the main, binocular part of the visual field. Writing the first paper on the competition was surprisingly difficult. New thoughts, even when they are clear in one’s head, are difficult. I wrote most of the paper while on vacation with the family in Door County, Wisconsin. During the day we enjoyed the scenery and Lake Michigan. In the quiet evenings I worked to get my thoughts organized.

The Move to Chicago, 1977–1984

The work that I did in the early and middle 1970s led to several interesting job offers and made me think seriously about our future in Madison. The children were growing up, Margot had started her residency but was not sure that there was a slot for her in the Madison dermatology program to complete her third year, and I saw my future in neuroscience at Wisconsin as limited. When I spoke to the dean of the medical school, who at that time was a surgeon, about the importance of graduate training in neuroscience, which was receiving no financial support, he asked whether I wasn’t just wanting to have fun. The answer—of course—was yes. I regarded teaching and introducing others to neuroscience as fun; no one could possibly have wanted to do it for the money. I was invited to look at the Anatomy Department at the University of Chicago, where on my first visit it was made clear to me that an outsider would not be welcome. The university was also planning to build a neuroscience program and had an interesting and lively group of neuroscientists. When the dean, Dan Tosteson, rang me after my visit to ask whether I would be interested in a position in Anatomy I said that I was not; I wanted to have my cake and eat it too. I wanted the environment of the expanding neuroscience program that the university was planning but I did not want the administrative responsibilities that would go with the Anatomy appointment. Dan Tosteson said he would arrange for me to have my cake and eat it too, and he did. I was given an appointment as chairman of a new Committee on Neurobiology and as a member of the Department of Pharmacological and Physiological Science, and Margot was able to complete the third year of her residency at the University of Chicago, later moving into a staff position in Dermatology.

Al Heller was the head of my new department, and our shared views about the academic goals of the new neurobiology program made my seven years in Chicago run smoothly. Al did the heavy duty administration, involving me occasionally, and I was able to focus on the developing graduate program and on the research in my lab. Later, after I had moved to Oxford, I realized that I had also had some necessary lessons in administration. Al never actually provided tutorials, but I learned a lot by just watching and listening.

My research shifted gradually during my time in Chicago. I had moved the core of my Siamese cat colony in 1977, but was to lose it to disease within a few years. I continued to work out the basic structure of the lateral geniculate nucleus in cat and rabbit, and started to look more closely at the developmental problems raised by the albino abnormality. We started to define the stages in the development of the visual pathways in normally pigmented and albino ferrets. Ferrets were attractive for this because they have a visual system very similar to the cat’s, but they have larger litters and the young are born at a very much earlier developmental stage, so that one can undertake experiments in postnatal ferrets that would have to be prenatal in cats.

In the late 1970s I was surprised to receive an invitation to a conference at Leeds Castle in England on the optic chiasm. I was to give the introductory talk. Although the optic chiasm, which is the region where some of the fibers going from the eye to the brain cross, and where an abnormal contingent crosses in albinos, had been of obvious interest to me in relation to the albino abnormality, I knew very little about it. Leeds Castle is a beautiful and luxurious building in a fine setting, the conference sounded interesting, I still had a mother to visit in England, and I accepted. Then I had to start reading about the chiasm. The literature was confusing, I gave a rather bad introduction, enjoyed the lavish hospitality of Leeds Castle, and sat through fierce arguments, illustrated by gruesome movies, about the best approach to a tumor near the chiasm: through the nose, the frontal lobes, or the temporal lobes. I came away guilty about my inadequate knowledge and determined to find out more about the optic chiasm. Working out exactly how the fibers that go from the retina to the brain relate to each other took up much of my time in Chicago, and later in Oxford. The pathway is intricate and complex, and early attempts to understand the development of the chiasm were necessarily flawed in the absence of clear information about the structure that was actually developing. The pathway consists of functionally distinct fiber groups, which Chris Walsh was able to show develop at different times, and which have distinct crossing patterns in the chiasm. That is, there is not one simple rule for all of the fibers.

In Chicago I also started to do some difficult intrauterine experiments in order to look at the developmental mechanisms that could produce the Boston pattern of geniculocortical connections in some animals and the Midwestern pattern in others. We were able to show that in the development of the geniculocortical pathway there is a mechanism that is independent of retinal inputs and another that depends on these inputs. In a normal cat both would tend to produce the same result, but in a Siamese cat, where the retinal input to the lateral geniculate nucleus is reversed relative to normal, they would produce opposite results, and so exactly which type of circuit is developed depends upon which mechanism happens to be dominant. These experiments also produced some unexpected and very puzzling results about the development of the optic chiasm. Removal of one eye, very early in development, before any of the fibers had reached the chiasm, produced an abnormality in the pathway formed later from the other eye, an observation that had previously been reported for mice by Pierre Godement. The surviving pathway behaved rather like one coming from an albino eye, in growing few, if any, uncrossed fibers. Hector Chan showed later, in Oxford, that this pathway was not like the albino pathway in its detailed anatomy. Rather, it seems that in normal development the uncrossed fibers need the crossed fibers from the other eye to accompany them on their journey beyond the chiasm. Carol Mason and Pierre Godement were able to show that when the crossed fibers from one eye are lost, the uncrossed fibers from the other eye stall at the chiasm.

I enjoyed my time in Chicago. I had stimulating colleagues with high scholarly standards. We had keen students and the neuroscientists formed a productively interactive group. I had no idea of leaving until Tom Powell, who was still in the Oxford Anatomy Department, suggested that I consider moving to Oxford to head that department when Charles Phillips retired in 1983. Tom had been passed over as the head of that department some years earlier. He knew now that he would never be made head, and encouraged me to think of myself as a candidate for the post. Margot and I had both spent some of our childhood in Oxford, we had a notion that eventually we might want to retire in England, and a move well before retirement seemed sensible. Our children’s education was almost completed and we felt that we could afford the major drop in salary that the move would entail. When Colin Blakemore, who was an elector for the anatomy post came through Chicago and asked if I was interested, I was ready to say yes. The job was offered to Gordon Shepherd first who, fortunately, decided against the move. Then we went through a long and complicated negotiation that included a promise of a job for Margot from the dermatologists and, for me, a complex correspondence containing many subordinate clauses and attempts to explain an administrative structure that I later learned was not understood by anyone.

The Department of Human Anatomy at Oxford, 1984–1996

In Oxford I had to take greater administrative responsibilities than I had had in Chicago. The department had a history of poor industrial relations with its technicians. The administrator wanted to be in charge of the department, did not trust the staff and was, in turn, not trusted by them. There were existing antagonisms that made some of our meetings difficult and tense. The first few years were not easy, but there was enthusiasm about research and teaching in the department that made the job enjoyable for me in spite of the difficulties. After three years the department was able to hire a new administrator, David Dongworth, who, unlike his predecessor, had had postdoctoral research experience, and had also worked for the Medical Research Council before moving to Oxford. He understood what was needed for the creation of a good research environment. Gradually he took over more and more of the running of the department and ran it smoothly and well. There were no more industrial hearings for me to attend and I knew that our financial affairs were in capable hands. I could concentrate on other things. He was everything that a good administrator should be and helped to build a strong, friendly, and enthusiastic department, which I was very sorry to leave when I reached retirement age in 1996.

Early during my time in Oxford I was approached by a committee representing the European Neuroscience Association (ENA) to ask whether I would take on the editorship of a journal they were planning to start. Michel Cuénod, Per Andersen, Anders BjØSrklund and Wolf Singer represented the ENA and were visiting several English publishing houses to explore possibilities. When they were asked who would edit the new journal they decided that they had best come to an early decision on this. The evening before their meeting with Oxford University Press they were dining in Oxford. I had moved to Oxford recently, so they rang and asked me to join them for their dessert to discuss my possible candidacy. We had moved house that day, it had been one of our coldest January days, and I was dirty, cold, and tired; but I realized that this editorship might give me an opportunity to get to know European neuroscientists in a way that is not generally easy for someone who has recently moved from one continent to another. So we met, and I later agreed to become the first editor of the new journal. It was hard work to set up new procedures and policies, but it was rewarding. I did get to know many of the active neuroscientists in Europe, and found that working with them was a delight. We got the journal started, and later on some of the same colleagues helped to set up a much needed European body (The European Biomedical Research Association) to address issues related to animal experimentation. More and more new legislation was coming from the European Union in Brussels, and there was a need for a body that could address these issues from a European, rather than a national, perspective. Thanks to Mark Matfield, the very energetic executive director of the new body, it got off to an excellent start.

The research of my lab in Oxford focused on two separate issues. One was to learn more about the optic chiasm and its development. I was able to summarize much of our current knowledge on this in a review written with Jeremy Taylor and Carol Mason shortly before my retirement. The other was a study of the thalamic reticular nucleus and a group of transient cells, closely related to the reticular nucleus.

Work on the reticular nucleus had started for me in a single study done in Madison with Vicente Montero and Clinton Woolsey. We had been able to show that small injections of two different radioactive tracers into visual cortex produced two clearly distinct loci of anterogradely transported label not only in the lateral geniculate nucleus (this was expected), but also in the thalamic reticular nucleus. Because the reticular nucleus at that time was considered to be a diffusely connected cell group, this result was a surprise and stood out as rather an exception to knowledge of the reticular nucleus.

I did not follow this clue any further until after I had moved to Oxford more than seven years later. Then I encouraged John Crabtree to look more closely at this issue. Herb Killackey, who was visiting Oxford at the time, expressed one of the problems succinctly when he asked how single points in the visual field are represented in the thalamic reticular nucleus. We knew that in the lateral geniculate nucleus they are represented by the “lines of projection” that Gordon Walls had described clearly in his book and P. O. Bishop has discussed in his autobiographical chapter (The History of Neuroscience in Autobiography, Vol. 1). John and Herb published a very beautiful paper in the first issues of the European Journal for Neuroscience, defining a then rather surprising mapping of visual cortex and retina onto the reticular nucleus. We now know that for each major sensory pathway (vision, hearing, touch), which relates to its own sector of the reticular nucleus, the relevant sensory surfaces are accurately mapped via connections coming from cortex and from thalamus. Many of the details of the mapping established by different pathways coming from thalamus or cortex still remain to be defined. These are likely to prove important in the proposed role of the reticular nucleus in attentional mechanisms, and I hope that in the next few years it will be possible for colleagues in Madison, where I am now working in a “post-retirement” capacity, to define the major features of these pathways.

When I was first looking at the radioactively labeled fibers that pass from visual cortex to thalamus I was struck by a change in the appearance of the pathway that occurs some distance before it reaches the thalamic reticular nucleus. It looked as though the fibers might be establishing contacts or a change in direction in this region. Careful inspection showed very few scattered cells in this region, which Annemarie Clemence and John Mitrofanis then demonstrated clearly and labeled the perireticular nucleus. John went on to show that these cells were the surviving remnants of a transient cell group, rather like the cortical subplate. The cells are there early in development just as the corticothalamic and thalamocortical fibers are growing past, and once these fibers have entered their appropriate course, the cells disappear as though they play a role in the development of the fiber pathway. The further study of this still quite mysterious cell group took up much of the other research efforts in the Oxford lab with Gary Baker, Eion Ramcharan, and Niels Adams during the next few years.

My time in Oxford was rewarding and enjoyable from the point of view of my research and my administrative duties, but not for my teaching or my personal life. The instruction of undergraduate students at Oxford is dominated by the tutorial system, which can provide excellent opportunities to students and teachers, but by tradition excludes professors from instruction other than the giving of formal lectures. Graduate students receive virtually no formal instruction, so that my contacts with students were limited for much of my time. Students automatically tended to turn to their tutors or their research supervisors. The curious tradition ofrelieving staff from most teaching duties when they were elevated to professorial rank tended to exclude many of Oxford’s most senior staff from the mainstream of the university’s educational enterprise, which in Oxford is focused on the colleges.

On the personal side, we found when we got to Oxford that the promise of a job for Margot was not going to be kept. Moving two careers is never easy and perhaps we were unwise to trust the reassurances we were both given. Margot was left in limbo for a considerable time, with no honest recognition of the promises that had been made, and she never found a really suitable professional opportunity in England. It was a bad experience. We separated toward the end of our time in Oxford and she is now once again practicing as a dermatologist in Madison.

Retirement 1996–

In 1996 I reached the mandatory retirement age at Oxford, and as this time approached I began to wonder about what I would do with my time. When an opportunity arose for me to return to Madison, to undertake some studies of thalamic anatomy with John Harting and other colleagues, I welcomed it enthusiastically. John had originally come to Madison in the 1970s to spend time as postdoctoral fellow in my lab. He is now head of the Anatomy Department and, working with Sherry Feig and Dave Van Lieshout, had been doing some beautiful light and electron microscopical studies of thalamic and tectal fiber pathways. They had all of the techniques I needed to attack some of the problems that still intrigued me about the thalamus. I had been corresponding for some years with Murray Sherman about the thalamus. He had earlier spent a sabbatical year in Oxford as the NewtonAbraham Visiting Professor and we had formed a habit of fruitful argument, which in recent years we continued by e-mail. This led to the development of a number of ideas about thalamic structure, many of which were included in a review we wrote just before I retired. Now I have an opportunity to look into some of these ideas in my semiretirement. John Harting has given me generous lab space and I am once more starting to do experimental work. The main thrust of our current research derives from an observation that was published in 1972 from the Madison Anatomy Department by Larry Mathers, a student of Peter Ralston’s. This had long puzzled me but never seemed to fit into a general scheme. Larry found that nerve fibers that innervate the pulvinar nucleus of the thalamus from the cerebral cortex have large terminals that look just like fibers from ascending sensory pathways (visual, auditory) in other thalamic nuclei. This is in contrast to the cortical fibers that innervate primary relay nuclei for vission, audition, and other senses, which are much smaller and clearly distinguishable. Evidence currently available suggests that the small endings modulate transmission through the thalamic relay, whereas the large endings provide the primary source of the information that is transferred. More recently, similar large cortical afferents have been found in other thalamic nuclei that receive few or no ascending afferents, so-called “association” nuclei, such as the mediodorsal nucleus or the posterior group. It now looks as though there are two distinct sorts of corticothalamic fiber, one with large and the other with small endings, and that these take origin from different groups of cortical cells. Nuclei that receive the large endings from cortex can be regarded as having their primary function in the relay of messages from one cortical area to another, in contrast to the classical relay nuclei, such as the lateral geniculate nucleus, which relays ascending visual information from the retina to the cortex and is subject to modulatory influences from the cortex via the smaller endings. Working out the details of this dual corticothalamic connectivity, and perhaps looking more closely at the thalamic reticular nucleus, promises to provide me with an interesting retirement.

Overview

It is not easy to summarize my life. Certainly the invitation to write about it has served as a stimulus for thinking about it and for that I am grateful. I had not fully realized before writing how lucky I have been in the forces that have shaped my career. Inheritance and environment seem to have combined smoothly to turn me into a neuroscientist; it almost looks as though I had no choice at all. I have always enjoyed the teaching but have felt more comfortable with a small group than in a formal lecture. The administrative duties were the most difficult and took me longest to learn. I should have built up the Oxford department more and left it in a stronger position, but I was never able to put my heart into the necessary “empire building.” I ended my career thinking of the department, in an admittedly parochial way, as the best small anatomy department in the world. It was the research that I enjoyed most and have focused on in this account. I have had many excellent students and coworkers and in the space available here have only mentioned a few of them in relation to particular high points of the research. They have provided essential stimulation in daily interactions, in arguments about details of particular research problems, and in our regular weekly lab meetings. For the descriptive work and for the experimental, interpretative studies, the day to day focus on each problem as it developed and took shape has been the most demanding and the most rewarding part of my career. It is very difficult to understand or to describe what it was that I was doing. How does one shape facts and ideas into coherent (publishable) advances in knowledge?

When you have carried some stuff round with you a very long time and mulled over it, and scraped together everything about it that might be useful—then it works, then something may come of it. You get an idea, it sticks in your head, or in your feelings; it is like a lump of clay in your hands, you try to work everything into it that you see, you think and dream of nothing but this one thing. That is the way you get it done.

This quotation, from H. T. Lowe-Porter’s 1939 translation of Thomas Mann’s Lotte in Weimar (published by Secker and Warburg), is about the creation of great poetry. Although I have been concerned with a very different product, the process of creating something new seems remarkably similar, no matter what the level. Perhaps the quote appeals to me because I share Goethe’s birthday. The amount of work and mulling over that is required for the production of a new description or a new idea, even a quite simple one, is always surprising. The reward comes rarely, but just often enough to keep you at it.

Acknowledgments

I thank my sister, Mrs. Evamaria Hawkins, and Drs. A. O. W. Stretton and D. Dongworth for reading an earlier version of the manuscript and making helpful comments. The photograph of me leaving the Department of Human Anatomy at Oxford was taken by Mr. Brian Archer. Written in Binham, Norfolk, United Kingdom and Madison, Wisconsin, United States, 1996.

Selected Bibliography

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Clemence AE, Mitrofanis J. Cytoarchitectonic heterogeneities in the thalamic reticular nucleus of cats and ferrets. J Comp Neurol 1992;322:161–181.

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Crabtree JW, Killackey HP. The topographic organization and axis of projection within the visual sector of the rabbit’s thalamic reticular nucleus. Eur J Neurosci 1989;1:94–109.

Daitz HM, Powell TPS. Studies of the connections of the fornix system. J Neural Psychiat 1954;7:5–82.

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Garey LJ, Powell TPS. The projection of the retina in the cat. J Anat Land 1968;102: 189–222.

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Mathers LH. The synaptic organization of the cortical projection to the pulvinar in the squirrel monkey. J Comp Neurol 1972;146:43–60.

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Ralston HJ III. The fine structure of neurons and synapses in the ventrobasal thalamus of the cat. Brain Res 1969;14:77–107.

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Wiesel TN, Hubel DH. Single cell responses in striate cortex of kittens deprived of vision in one eye. J Neurophysiol 1963; 26:1003–1017.

Additional Publications

Boycott BB, Gray EG, Guillery RW. Synaptic structure and its alteration with environmental temperature: A study by light and electron microscopy of the central nervous system of lizards. Proc R Soc B 1961;154:151–172.

Chan SO, Guillery RW. Developmental changes produced in the retinofugal pathways of rats and ferrets by early monocular enucleations: The effects of age and the differences between normal and albino animals. J Neuroscience 1993;13: 5277–5293.

Colonnier M, Guillery RW. Synaptic organization in the lateral geniculate nucleus of the monkey. Z Zellforsch 1964;62:333–334. [Database]

Cucchiaro J, Guillery RW. The development of the retinogeniculate pathways in normal and albino ferrets. Proc R Soc Lond B 1984; 223:141–164.

Deiters E, Guillery RW. Otto Deiters, 1834–1863. Exp Neurol 1963;9:iii–vi.

Gray EG, Guillery RW. An electron microscopical study of the ventral nerve cord of the leech. Z Zellforsch 1963;60:826–849. [Database]

Gray EG, Guillery RW. Synaptic morphology in the normal and degenerating nervous system. Int Rev Cytol 1966;19:111–182.

Guillery RW. A quantitative study of the mamillary bodies and their connexions. J Anat Lond 1955;89:19–32.

Guillery RW. Degeneration in the post-commissural fornix and the mamillary peduncle of the rat. J Anat Lond 1956;90:350–370.

Guillery RW. Degeneration in the hypothalamic connexions of the albino rat. J Anat Land 1957;91:91–115.

Guillery RW, Ralston HJ. Nerve fibers and terminals: Electron microscopy after Nauta staining. Science 1964:143:1331–1332.

Guillery RW, Adrian HW, Woolsey CN, Rose JE. Activation of somatosensory areas I and II of cat’s cerebral cortex by focal stimulation of the ventrobasal complex. In: Purpura and Yahr eds. The Thalamus. New York: Columbia University Press, 1966;197–207.

Guillery RW. An abnormal retinogeniculate projection in Siamese cats. Brain Res 1969;14:739–741.

Guillery RW. The organization of synaptic interconnections in the laminae of the dorsal lateral geniculate nucleus of the cat. Z Zellforsch 1969;96:1–38.

Guillery RW. The laminar distribution of retinal fibers in the dorsal lateral geniculate nucleus of the cat: A new interpretation. J Comp Neurol 1970;138:339–368.

Guillery RW, Stelzner DJ. The differential effects of unilateral lid closure upon the monocular and binocular segments of the dorsal lateral geniculate nucleus in the cat. J Comp Neurol 1970;139:413–422.

Guillery RW. Binocular competition in the control of geniculate cell growth. J Comp Neurol 1972;144:117–130.

Guillery RW, Kaas JH. Genetic abnormality of the visual pathways in a “white” tiger. Science 1973;180:1287–1289.

Guillery RW, Casagrande VA, Oberdorfer MD. Congenitally abnormal vision in Siamese cats. Nature 1974;252:195–199.

Guillery RW, Okoro AM, Witkop CJ. Abnormal visual pathways in the brain of a human albino. Brain Res 1975;96:373–377.

Guillery RW, Casagrande VA. Studies of the modifiability of the visual pathways in Midwestern Siamese cats. J Comp Neurol 1977;174:15–46.

Guillery RW, Oberdorfer MD, Murphy EH. Abnormal retino-geniculate and geniculocortical pathways in several genetically distinct color phases of the mink (Mustela vision). J Comp Neurol 1979;185:623–656.

Guillery RW, Polley EH, Torrealba F. The arrangement of axons according to fiber diameter in the optic tract of the cat. J Neurosci 1982;2:714–721.

Guillery RW. The optic chiasm of the vertebrate brain. In: WD Neff, ed. Contributions to sensory physiology, vol. 7, New York: Academic Press, 1982;39–73.

Guillery RW, Hickey TL, Kaas JH, Felleman DJ, Debruyn EJ, Sparks DL. Abnormal central visual pathways in the brain of an albino green monkey (Cercopithecus aethiops). J Comp Neurol 1984;226:165–183.

Guillery RW, Ombrellaro M, LaMantia AL. The organization of the lateral geniculate nucleus and of the geniculocortical pathway that develops without retinal afferents. Dev Brain Res 1985;20:221–233.

Guillery RW, Walsh C. Changing glial organization relates to changing fiber order in the developing optic nerve of ferrets. J Comp Neurol 1987;265:203–217.

Guillery RW, Jeffery G, Cattanach BM. Abnormally high variability in the uncrossed retinofugal pathways of mice with albino mosaicism. Development 1987;101:857–867.

Guillery RW. Early monocular enucleations in fetal ferrets produce a decrease of uncrossed and an increase of crossed retinofugal components: A possible model for the albino abnormality. J Anat 1989;164:73–84.

Guillery RW, Mason CA, Taylor JSH. Developmental determinants at the mammalian optic chiasm. J Neurosci 1995;15:4727–4737.

Guillery RW. Anatomical evidence concerning the role of the thalamus in corticocortical communication. A brief review. J Anat 1995;187:583–592.

Hickey TL, Guillery RW. An autoradiographic study of retino-geniculate pathways in the cat and the fox. J Comp Neurol 1974;156:239–254.

Hickey TL, Guillery RW. Variability of laminar patterns in the human lateral geniculate nucleus. J Comp Neurol 1979;183:221–246.

Kaas JH, Guillery RW. The transfer of abnormal visual field representations from the dorsal lateral geniculate nucleus to the visual cortex in Siamese cats. Brain Res 1973:59:61–95.

Montero VM, Guillery RW, Woolsey CN. Retinotopic organization within the thalamic reticular nucleus demonstrated by the double label autoradiographic technique. Brain Res 1977;138:407–421.

Sherman MS, Guillery RW, Kaas JH, Sanderson KJ. Behavioral electrophysiological, and morphological studies of binocular competition in the development of the geniculo-cortical pathways of cats. J Comp Neurol 1974;158:1–18.

Mitrofanis J, Guillery RW. New views of the thalamic reticular nucleus in the adult and the developing brain. TINS 1993;16:240–245.

Sherman MS, Guillery RW. Behavioral studies of binocular competition in cats. Vision Res 1976;16:1479–1481.

Sherman SM, Guillery RW. Functional organization of thalamocortical relays. J Neurophysiol 1996;76:1367–1395.

Taylor JSH, Guillery RW. Effect of a very early monocular enucleation upon the development of the uncrossed retinofugal pathway in ferrets. J Comp Neurol 1995;357:331–340.

Walsh C, Polley EH, Hickey TL, Guillery RW. Generation of cat ganglion cells in relation to central pathways. Nature 1983;302:611–614.

Masao lto

BORN:

Nagoya, Japan

December 4, 1928

EDUCATION:

University of Tokyo, M.D. (1953)

University of Tokyo, D.Ms. (1959)

APPOINTMENTS:

Kumamoto Medical School (1954)

University of Tokyo (1958)

Australian National University (1959)

University of Tokyo (1963)

Dean, Faculty of Medicine, University of Tokyo (1986)

Director General, Frontier Research Program, RIKEN (1992)

HONORS AND AWARDS (SELECTED):

Fujiwara Prize (Japan, 1981)

Academy Prize, Imperial Prize (Japan, 1986)

Japan Academy (1989)

Foreign Member, Royal Swedish Academy of Sciences (1989)

Foreign Member, Armenian Academy of Sciences (1990)

Foreign Member, Royal Society of London (1992)

Robert Dow Award in Neuroscience (U.S.A., 1993)

Lui Vuitton Moet Hennesy Science for Art Award (France, (1993)

Person of Cultural Merit (Japan, 1994)

Foreign Member, Russian Academy of Sciences (1994)

Japan Prize (1996)

Order of Culture (Japan, 1996)

Masao Ito discovered long-term depression in the cerebellum and carried out fundamental studies of the physiology and function of the cerebellum. In his later career, he became a highly visible scientific leader in Japan and an effective spokesperson for international cooperation in science.

Masao lto

I am not sure if my personal history will be of interest to the reader, but since whenever I face a difficulty I think of what my predecessors would have done, I would like to write here about major events and related anecdotes in my life so far, in the hope that they may contain some useful information for succeeding generations of neuroscientists.

My Parents

I was born in 1928 in Nagoya, Japan. My father, Mutuo, was the proprietor of a small enterprise that produced soft drinks. He died in 1935. I remember little about him, but my mother, Chiyo, frequently commented that he was capable of fast mental arithmetic. When doing calculations, he moved the fingers of his right hand on his knee as if he were using a Japanese abacus. Because he left the enterprise to my mother, she was able to maintain a comfortable standard of living for her family, including her mother, her sister, my two sisters, and me. My mother was one of the early graduates of Nara Women’s Higher Education School which, early in the 20th century, was one of only two colleges in Japan that were dedicated to training women to be qualified school teachers. Before marriage, she taught at the girls’ middle school, which her uncle had founded in Nagoya. My relatives told me that she was a popular teacher. To me, she was a calm and modest lady with a hidden, high intellect.

Middle School and High School Days

In 1941, the year I entered middle school, the Pacific war began. It ended in 1945, the year I graduated from that school. Middle school students were mobilized to help construct a military airport, and my final year there was spent in labor service at a military arms factory. In February 1945, I entered the preparatory course of the military school, and until the end of August, I stayed in a camp which was first located near Tokyo and then moved to a mountainous area west of Tokyo. I have only a few pleasant memories from this wartime period, for example, a number of capable teachers in the middle school and the lessons and practice on car engines at the camp.

In October 1945, I entered the 8th High School, one of the eight prestigious high schools at that time. I was fortunate in that the 8th High school had excellent teachers of mathematics, physics, chemistry, biology, English, and German, and that an emphasis on general culture had been a core of the high school traditions since prewar time. Along with many of my contemporaries, I am saddened that these traditions were lost when the entire Japanese school system was reformed shortly after the War.

One notable event from my high school days was that I spent 7 months in 1946 in a sanatorium near Nagoya recuperating from tuberculosis. At that time, the mortality rate for the disease was high and, in fact, during the rainy season in June, many patients died every day in the sanatorium. A young medical doctor who was a patient in the next room used to tell me how interesting medicine was to him, and how exciting his experiences at a university clinic were. His enthusiasm and stories opened my eyes to the existence of the immense fields of medical science. The director of the sanatorium, Rokuro Katsunuma, a tuberculosis expert with an enthusiastic mind for research, often tried to convince me that research is the only way to solve difficult medical problems, such as how to cure cancer and mental diseases. He also emphasized that any talented scientist can find his or her own comfortable niche somewhere in the vast fields of medical science. Thanks to the guidance I received from these people, I decided to study medicine.

University Days

In 1949 I entered the University of Tokyo Medical School. The initial months were full of new impressions, and I was particularly moved when I saw the brains of eminent politicians, scholars, and novelists kept in a storage room for anatomical reference material. However, I soon became bored with too many lectures that were purely descriptive in nature. I became nostalgic for physics, and audited a course in nuclear physics taught by San-íchiro Mizushima of the Faculty of Science. I did not formally register for this course, but no one minded that I attended the classes. Meanwhile, I found Shimane Sakamoto’s physiology lectures on classic theories of membrane excitation and conduction very interesting. I then met a young physiologist, Masayasu Sato, and used to spend most of my time in his laboratory, just watching him experiment on single nerve fibers excised from toads using a Helmholtz pendulum for stimulation, and discussing saltatory conduction in myelinated nerve fibers, which was the most advanced theory before the epoch-making Hodgkin–Huxley theory was published in 1952. Baldwin’s monograph on biochemistry also greatly affected me. I organized a series of seminars to read this book with a group of students and young researchers, including Masanori Otsuka, Seturo Ebashi, Masayasu Sato, and Sinji Ishikawa. Later, I had also a chance to engage in histological studies at the Brain Research Institute of the medical school. I was amazed by the numerous beautiful neurons I observed under a microscope, and enjoyed thinking about what these neurons do.

After graduating from medical school in 1953, I interned for 1 year at the Tokyo University Hospital where I completed rotations through a number of clinical sections. I was most interested in neurosurgery, psychiatry, and ophthalmology but, in the end, decided to pursue a career in physiology. During this internship, I had a chance to escape from the hospital from time to time to study in Takefusa Sakamoto’s electroengineering laboratory in the Faculty of Engineering. Here I constructed direct current-coupled amplifiers and stabilized power supplies, which were frontier technology at that time; it was a good time which allowed me such an option at my own risk. In 1954, Masayasu Sato returned from University College London where he had been on a British Council Fellowship for 2 years, and was appointed as professor at Kumamoto University Medical School. I moved to Kumamoto to work as assistant professor in his new department.

Thesis Work in Kumamoto

Around 1950, Bernard Katz’s discovery of quantal release of neurotransmitters and John Eccles’ discovery of inhibitory synaptic transmission were two major breakthroughs which, together with the Hodgkin–Huxley theory, opened a new era of neurophysiology. The epoch-making new technology used for these discoveries was glass microelectrodes connected to electronic instruments. In Japan, Takuzo Otani and Yasuji Katsuki were pioneers who applied this technology to the study of toad spinal motoneurons and mammalian central auditory systems, respectively. For my work in Kumamoto, I chose toad dorsal root ganglion cells which, having only one axon and no dendrites and forming no synapses, provided a very simple model of nerve cells. After 1 year of struggle in a laboratory set up in a barracks with all hand-made electronic instruments, I made the first ever intracellular recording with a microelectrode from dorsal root ganglion cells, and studied the electrical properties of their membrane. I found a peculiar rectification of the membrane which, according to present knowledge, is apparently due to H currents.

When my first physiology paper on electrical properties of dorsal root ganglion cells was published in the Japanese Journal of Physiology (Ito, 1957), I received requests for reprints from abroad; it was a joy for me to find among these, letters from two great scholars. One was Harry Gundfest who recommended the term “transmembrane stimulation” as a replacement for direct stimulation of the membrane which I had used, and the other was from John Eccles, who invited me to join his laboratory. John Eccles’ monographs The Neurophysiological Basis of Mind (1953) and Physiology of Nerve Cells (1957) were almost like bibles for young researchers, and I considered it a blessing to receive such an invitation from the author of these books.

After staying in Kumamoto for 3 years, I returned to Tokyo in 1957 and was employed as a lecturer at Nippon Dental College and, shortly after, as assistant professor in the Second Department of Physiology, of the University of Tokyo, chaired by the late Isao Wakabayashi. While I continued to work on dorsal root ganglion cells, I planned a trip to Canberra. I had been married to my wife Midori since 1956, and in February 1959, we left Yokohama Harbor on a 3000-ton ship on which we traveled for 1 month to Hong Kong, Borneo, Cairns, Brisbane, and finally Sydney, from where we flew to Canberra.

Three Years in Canberra

Canberra was like paradise. We lived in a comfortably furnished flat four km from the John Curtin School of Medical Research of the Australian National University; it took no more than ten minutes to drive. John Eccles’ department occupied the western half of the third floor of a long brick building. At one end of the corridor was a professor’s study and laboratory. At the other end was a room for technicians and a storeroom. In between were small booths for individual researchers on one side of the corridor, while on the other side were three laboratories used by David Curtis, John Hubbard, and graduate students, respectively. The four laboratories were air-conditioned, and fully equipped with instruments designed by Jack Coombs. If any problem occurred, several technicians rushed to fix it. In the morning, technicians distributed anesthetized animals to each laboratory, and developed films that had been exposed the day before. Data were continuously collected in these four laboratories, and numerous papers were sent out for publication. At the John Curtin School library, current and past issues of almost all journals published at that time were available. These conditions are not extraordinary today, but it seems like a miracle to me that they existed forty years ago in a university department.

John Eccles’ department attracted about seventy researchers from abroad. Its alumni association list includes the names of numerous eminent individuals presently considered leaders in the world of neuroscience. Among these, Per Andersen, Tatsunosuke Araki, Platon Kostyuk, Olov Oscarsson, Tomokazu Oshima, John Phillis, Tom Sears, Rod Westerman, and Bill Willis were my contemporaries. It seems to me to have been one of those rare occasions in which a single scholar attracts a large number of young talents who then became the leaders of the next generation.

During the first year of my stay I had a precious opportunity to work as part of a team with John Eccles and his daughter, Rose. We studied the ionic permeability of cat spinal motoneuron membranes by injecting two ion species in combination through double-barrelled microelectrodes, each barrel filled with a different solution. I learned the energetic and organized ways to conduct cat experiments. In addition, during the English-style tea time—often held at midnight during a break from an experiment—John Eccles often talked about his days in Oxford, and especially about Charles Sherrington. Apparently, John Eccles was taking Sherrington as his role model. Eccles, born in 1903, used to ask how he could stop working when Sherrington had started to fully work only after the age of sixty.

During the second year of my stay, I continued ionic permeability studies using electrophoretic injection techniques (Araki et al., 1961; Ito et al., 1962). We tested 34 different anion species and found a sharp distinction between permeant and nonpermeant ions through inhibitory subsynaptic membranes, proof of the sieve-membrane hypothesis. During the third year, I recognized a peculiar multiple exponential behavior of motoneuron membrane for current steps, and devoted a considerable amount of time to analyzing it (Ito and Oshima, 1965). The 3 years passed quickly and fruitfully and, in 1962, I decided to return home. We took with us our two children who had been born in Canberra, and a great respect for John Eccles and his department. One year later, John Eccles was awarded the 1963 Nobel Prize for Medicine and Physiology.

Return to Tokyo

By the time I returned to the University of Tokyo, Koji Uchizono had succeeded to the chair of the Second Department of Physiology. I was appointed associate professor, and organized a research group with Nakaakira Tsukahara, Keisuke Toyama, Mituo Yoshida, and later also with Kunihiko Obata, Masanori Hongo, Yasuhiro Okada, Rikuo Ochi, and Masao Udo. Research funds were scarce, and we had to start by building a shielded room with wood and wire netting as well as building all our electronic instruments. Mr. Eichi Narishige made a cat frame, a micromanipulator, and a microelectrode puller for us according to blueprints given to me by John Eccles. We had no technicians working directly for us, and we took care of the animals and cleaned our laboratory ourselves. This situation, however, was not an obstacle, because we were all young and in high spirits.

Initially, I wished to continue my work on spinal motoneurons in order to solve one particular problem that was left unsolved in John Eccles’ 1963 monograph, The Physiology of Synapses. It was clear that chloride ions contributed to the generation of inhibitory postsynaptic potentials (IPSPs); the belief at that time that potassium ions also contribute was based merely on the size of hydrated potassium ions being similar to that of hydrated chloride ions, and that permeation of potassium ions through a membrane was expected to generate a membrane hyperpolarization similar to IPSPs. I wanted to test the potassium contribution hypothesis, but to do this, it was necessary to deprive motoneurons of chloride ions. If IPSPs occurred in the absence of chloride ions, they must be generated, at least partly, I thought, by potassium ion flux. We perfused cat spinal cords in vivo with a chloride-free solution and exchanged the circulating blood with chloridefree artificial blood. We reduced the chloride content of the spinal cord by one-half, but this caused the heart to stop beating. After a number of unsuccessful experiments, we gave up. We were ahead of our time in these experiments; today chloride deprivation can be achieved easily in in vitro experiments on brain slices, and it has been proven that IPSPs are caused solely by increases in chloride flux.

Inhibitory Action of Purkinje Cells

I had to choose the next theme for my group of researchers who were impatient. Recalling the impressive anatomy lectures in my medical student days by Teizo Ogawa on giant neurons in the nucleus of Deiters and the red nucleus, I took up the study of these two types of neurons in cat brain stems. We formed two teams, one on Deiters neurons and the other on red nucleus neurons, and used the single laboratory on alternate days. In the morning, the off-duty team would arrive and the other team, which had been working since the preceding morning, would have to stop even if they were in the middle of an experiment. It took some months before we successfully penetrated these neurons with glass microelectrodes in cat brain stem.

In November 1963, Yoshida and I made the surprising observation that large IPSPs were generated in a Deiters neuron upon stimulation of the cerebellum. The latency of the IPSPs was short enough to indicate that they were induced monosynaptically (Ito and Yoshida, 1966). We stimulated Purkinje cells both directly and indirectly via afferent pathways, and confirmed that IPSPs always accompanied Purkinje cell excitation (Ito et al., 1966). We also confirmed that the IPSPs were evoked only from the ipsilateral vermis from which Purkinje cells project to the nucleus of Deiters (Ito et al., 1968a). We made similar observations on neurons in cerebellar nuclei, which receive Purkinje cell projections from respective areas of the cerebellum (Ito et al., 1970). I was convinced that Purkinje cells establish direct inhibitory connections with Deiters neurons and that Purkinje cells are inhibitory in nature.

This discovery provoked objections. Because all previously identified inhibitory neurons were small Golgi type-II neurons with relatively short axons, such as Renshaw cells in the spinal cord and basket cells in the hippocampus, John Eccles was not immediately convinced by my proposal that large Purkinje cells with long axons are inhibitory neurons. In fact, stimulation of the cerebellum was known to produce dual effects on muscle tone––excitation under some conditions and inhibition under others. We actually detected excitatory responses in Deiters and cerebellar nuclear neurons after cerebellar stimulation, but we were able to explain these responses as being due to stimulation of cerebellar afferents which supply excitatory synapses through their collaterals to Deiters and cerebellar nuclear neurons (Ito et al., 1969), or to disinhibition, (i.e., removal of inhibitory influences of Purkinje cells via the inhibitory action of basket and stellate cells in the cerebellar cortex) (Ito et al., 1968b).

At that time, γ-aminobutyric acid (GABA) had been proposed to be an inhibitory neurotransmitter, but electrophoretic application of GABA to motoneurons had not induced IPSP-like membrane hyperpolarization. Our experiment on Deiters neurons (Obata et al., 1967) revealed that GABA induces membrane hyperpolarization, suggesting it is an inhibitory neurotransmitter of Purkinje cells. Later, GABA was found by neurochemical and immunohistochemical techniques to be richly contained in all Purkinje cells. This observation supports the hypothesis that Purkinje cells are exclusively inhibitory. A decade later, however, some Purkinje cells were found to contain a peptide-like motilin, which excites smooth muscle cells. A subsequent test, however, revealed that electrophoretically applied motilin inhibits the activity of Deiters neurons (Chan-Palay et al., 1982); the possibility that Purkinje cells containing the motilin-like peptide are excitatory was thereby excluded.

When I started to work on Deiters neurons in Tokyo, I was not aware that John Eccles had moved his focus to the cerebellum after I had left Canberra. He came to Tokyo in 1965, on the occasion of the 26th IUPS (International Union of Physiological Sciences) Congress, and we organized an IBRO (International Brain Research Organization)-sponsored symposium on the neuronal mechanism of the cerebellum. It was a fantastic meeting, attended by internationally renowned authorities on neuroscience such as Ragnar Granit, John Szentágothai, Robert Dow, Charles Phillips, Francis Schmitt, John Brookhart, Vernon Brooks, and a number of young researchers, including Kris Krnjevic, Per Andersen, Jan Jansen, and Rodolfo Llinás. Our studies in Tokyo were well received, and no one doubted that Purkinje cells are inhibitory.

Round-the-World Trip

The 1965 meeting on the cerebellum brought me two big rewards. One was that John Eccles asked me to write a monograph on the cerebellum with him and John Szentágothai, which was published by Springer Verlag in 1967 as The Cerebellum as a Neuronal Machine. The other reward was invitations to participate in three meetings in 1966: a 1-week workshop on the cerebellum held in January in a suburb of Boston as part of the Neuroscience Research Program (NRP), a second 4-week NRP workshop held that summer in Boulder, Colorado (both organized by Francis Schmitt), and the Nobel symposium on structure and function of inhibitory neuronal mechanisms organized by Curt von Euler, in Stockholm. To attend these meetings and visit many laboratories around the world, I left home for six months.

John Eccles brought to Boston a number of chapters which he had written for the monograph. As we discussed the structure of the book, I saw his inspiration emerge and grow. These discussions were some of the most vivid scenes in which I recall this fabulous hero of neuroscience, who passed away in May 1997 at the age of 94. In 2 months while staying at the NRP center after the workshop, I wrote three chapters for my part of the monograph. I missed my laboratory, but it was a great joy to stay with three colleagues, Michael Arbib, Curt Bell, and Ray Kado. We chattered all day, discussing future perspectives of neuroscience. And, because I lived in the Vanderbilt dormitory of the Harvard Medical School—by courtesy of Stephen Kuffler—I also got a taste of American university life.

Network Models of the Cerebellum

By around 1965 our major understanding was that neurons in the brain are interconnected through excitatory and inhibitory synapses, forming intricate networks, as typically dissected in the cerebellum. However, when we tried to explain a brain function such as learning or motor control on the basis of the brain’s neuronal network structures, we found it impossible to do so. At the symposium on information processing in the cerebellum held in 1967 at Salishan Lodge on the Oregon coast, mathematicians, computer scientists, and bioengineers were invited to look into every detail of the cerebellum in order to interpret its functional meaning. The meeting was exciting because of discussions on the wide range of topics unfamiliar to traditional neurophysiologists. I particularly enjoyed Don McKay’s insightful analysis of the roles of inhibitory neurons in the brain. Even though the meeting ended without any tangible results, it symbolized the beginning of a new era of informational neuroscience. Indeed, David Marr’s (1969) epochal theory of the cerebellum and J.S. Albus’ (1971) simple perceptron model of the cerebellum were presented a short time later.

These are monumental issues in neuroscience. Neuronal network theories began with McCulloch and Pitt’s (1943) model of the brain according to which neuronal networks are capable of logical calculus. I was amazed to see that inhibitory synapses were postulated in this model which was proposed a decade before John Eccles’ discovery of IPSPs. Synaptic plasticity, which is an activity-dependent persistent change in synaptic transmission efficacy, was adopted in Hebb’s (1949) cell assembly model as a counterpart of the learning and memory capabilities of the brain. Rosenblatt (1962) further demonstrated that his simple perceptron model, composed of three neuron layers, one of which incorporates synaptic plasticity, is capable of actual learning. Both Marr’s (1969) and Albus’ (1971) theories are based on the assumption that the cerebellar neuronal network is composed of excitatory and inhibitory synaptic connections, and contains another important element: synaptic plasticity. Albus (1971), in fact, adopted a close analogy to that of simple perceptron in his neuronal network theory of the cerebellum.

Hebb’s (1949) cell assembly model assumes that coactivation of presynaptic and postsynaptic membranes leads to a persistent increase in the efficacy of synaptic transmission. Each Purkinje cell receives two distinct excitatory inputs: one, arising from a number of parallel fibers, exerts a weak effect, while the other, arising from a single climbing fiber, exerts a strong effect by which the target Purkinje cell is invariably excited. Hence, coactivation of parallel fibers and climbing fibers leads to the Hebbian synapse situation. G.S. Brindley (1964) was the first to suggest that coactivation of parallel fibers and a climbing fiber induces a Hebbian type of strengthening of parallel fiber-to-Purkinje cell synapses, and this suggestion was incorporated into Marr’s (1969) theory of the cerebellar cortex. However, Albus (1971) assumed for several reasons that such coactivation leads to sustained depression of parallel fiber-to-Purkinje cell transmission. These theories suggested that the elaborate cerebellar neuronal network acquires computational capability due to the synaptic plasticity of Purkinje cells. Different versions of the cerebellar neuronal networks capable of learning, proposed by Grossberg (1969), Gilbert (1974), and Fujita (1982), are also based on synaptic plasticity assumptions.

Around 1970, I anticipated that the postulated synaptic plasticity would be uncovered shortly, but unfortunately, experimental tests conducted in a number of laboratories failed to reveal such synaptic plasticity. While synaptic plasticity phenomena in the form of long-term potentiation and sensitization had been detected in the mammalian hippocampus and molluscan ganglia, respectively, in the early 1970s, the synaptic plasticity in the cerebellum assumption began to fall into disfavor. In spite of the beautiful theoretical prediction made around 1970, its verification had to wait a decade.

Vestibular Reflexes and Cerebellum

One of the important strategies which I learned in Canberra was to investigate microscopic neuronal events in spinal neurons in correlation with macroscopic phenomena at a reflex level. John Eccles’ finding of spinal inhibitory neurons was guided by observations of the inhibitory interaction between afferent signals in inducing monosynaptic reflexes. In 1968, when we finished a series of experiments on Deiters neurons and Purkinje cells, I turned to examine vestibular reflexes with colleagues Tadashi Akaike, Victor Fanardjan, Jun Fukuda, Steve Highstein, Kyoji Maekawa, Hiroshi Nakajima, Tadao Ohno, Jerry Simpson, N. Sato, and T. Tsuchiya. We found that Purkinje cells in the flocculus, a hemispheric part of the so-called vestibulocerebellum receiving vestibular afferents, directly inhibit vestibular nuclear neurons from relaying the vestibulo-ocular reflex (VOR), whereas the vestibulospinal reflex (VSR) does not receive Purkinje cell inhibition from the vestibulocerebellum even though these two reflexes are mediated by three-neuron pathways of similar structure.

Student riots from 1968–1970 culminated in the closure of our laboratory for six months. During these days, I spent time reading many books, including some on modern control theories. I noticed that the distinction between the VOR and VSR in their relationship with the vestibulocerebellum corresponds to their difference as control systems. Whereas the VSR is a classic feedback control system in which any change in the output (i.e., head position and movement) should be reflected in vestibular inputs, the VOR is a feedforward system, the output of which (i.e., eye position and movement) does not influence vestibular input.

It is a logical conclusion that the VOR requires the flocculus as a device which replaces the feedback loop and so secures its precision. I formulated this idea when I was invited to the symposium on the role of the vestibular organs in space exploration, held in Pensacola, Florida, in 1968. I elaborated on it further for the Fulton Society meeting in New York in 1969, but because I was hospitalized for abdominal pain, I was unable to attend the meeting. The proceedings of the meeting, in which my article was included, were published in an issue of the International Journal of Neurology (Ito, 1970). This article presents my initial idea about the control system structure of the cerebellum, and I regretted that it appeared in a journal almost unnoticed by colleagues in my field. However, I was told very recently by one of the participants at the New York meeting that my article was circulated among the cerebellum experts who attended. In the article, I predicted the presence of a teaching line in which the flocculus is informed of adequate performance of ocular movements. Kyoji Maekawa and Jerry Simpson (1973) subsequently found that retinal signals are, indeed, conveyed to the flocculus via climbing fibers. Thus, I completed the neuronal diagram including the VOR arc, flocculus, and retina on which I based my flocculus hypothesis of VOR control, according to which the flow of vestibular signals through the flocculus as a sidepath to the VOR arc is modified by retinal error signals conveyed by climbing fibers, so that the VOR dynamics undergo continuous adaptive correction toward minimization of retinal errors (Ito, 1974). This error-driven adaptive mechanism should enable the VOR to maintain precision even in the absence of feedback.

Flocculus Hypothesis of VOR Control

In 1970, I was promoted to chair the First Department of Physiology after Kojiro Matsuda. My major concern at that time was how to test the flocculus hypothesis. I presented the flocculus hypothesis at the 1971 IUPS Congress in Munich and G. Melvill-Jones described his amazing observation on human subjects that the VOR was extensively modified during vision reversal induced by Dove prism goggles (Gonshor and Melvill-Jones, 1974). It seemed obvious to me that this VOR modification was due to the adaptive mechanism of the flocculus that I was proposing. At that meeting I met Dr. David Robinson, who subsequently experimented on cats and demonstrated that lesions of the flocculus abolish the prism adaptation of the VOR (Robinson, 1976).

Through the 1970s, with colleagues Cesira Batini, Michel Dufossé, Brunello Ghelarducci, Pawel Jastreboff, Ray Kado, Yasushi Miyashita, Naoko Nisimaru, Igor Orlov, Takashi Shiida, lchiro Shimoyama, Nobuya Yagi, Miyuki Yamamoto, and later also Carey Balaban, Soichi Nagao, Katuei Shibuki, Akira Ueki, and Eiji Watanabe, we constructed detailed neuronal circuit diagrams for VOR control, paying special attention to the microzonal structure of the flocculus; using Amanomori’s method of combined rotations of a turntable for vestibular stimulation and a screen for optokinetic stimulation, we examined VOR adaptation in rabbits and monkeys. In-phase rotations of the turntable and the screen gradually inhibit the VOR, whereas out-of-phase rotations gradually enhance the VOR. After a long period of struggles against many obstacles (see Ito, 1992), it turned out that lesions of the flocculus abolish these VOR adaptations, and that Purkinje cells in the flocculus undergo changes in their responsiveness to head rotation in parallel with the VOR adaptation.

The data we collected are consistent with the flocculus hypothesis (summarized in Ito, 1982, 1984), but the hypothesis has been challenged a number of times. The most serious challenge was the report that discharge patterns in monkey Purkinje cells were inconsistent with the flocculus hypothesis (Miles and Lisberger, 1981). However, this conflict can be explained by two points (Ito 1994). One is that the part of the monkey cerebellum traditionally defined as the flocculus covers not only the genuine flocculus but also the ventral paraflocculus in its connections with brain stem structures (Gerrits and Voogd, 1989). Purkinje cells taken selectively from the genuine flocculus of monkeys respond to vestibular and optokinetic signals in a manner consistent with the flocculus hypothesis (Nagao, 1992). The second point is that Miles and Lisberger (1981) measured vestibular signals of Purkinje cells during visual suppression of the VOR, assuming that eye-velocity signals, which normally contaminate vestibular signals, are simply nullified during the VOR. However, in suppression of the VOR, a smooth pursuit mechanism is likely to drive the eye movement to counteract the VOR and hence, during the visual suppression, flocculus Purkinje cells could receive extra signals generated by the smooth pursuit mechanism, which would obscure vestibular signals. It now seems to be generally accepted that the flocculus plays a key role in induction of VOR adaptation, but whether or not maintenance of the VOR adaptation also involves plasticity in vestibular nuclei remains an unanswered question (Raymond et al., 1996). Evidence for such plasticity in vestibular nuclei or cerebellar deep nuclei is meager, and confirmation is required.

Long-Term Depression

Because the flocculus hypothesis of VOR control is consistent with the synaptic plasticity assumption, I became firmly convinced of the presence of the postulated synaptic plasticity in Purkinje cells. Observations of Purkinje cell responses during hand movement adaptation against a suddenly altered load were also consistent with Albus’ assumption (Gilbert and Thach, 1977).

In 1979, we found that lesions of the inferior olive—the sole source of climbing fibers—rapidly depress the inhibitory action of Purkinje cells on Deiters neurons (Ito et al., 1979). This phenomenon apparently represents trophic interactions among neurons required for developing and maintaining their proper connections, and is not related to Marr’s (1969) or Albus’ (1971) synaptic plasticity assumption. When I visited David Hubel and Stephen Kuffler at Harvard medical school in October 1979, David Marr attended my seminar on the trophic type of plasticity. This was my first and last meeting with him, and his words that he had been looking forward to seeing me for 10 years were deeply engraved in my mind. He also mentioned that because he was invited to Japan to receive an award, he would visit me if his health allowed him. He never showed up in Japan, and I still regret that at the time of our meeting I had no data to support his admirable cerebellar theory.

Immediately after I returned from Boston, I decided to test directly the hypothesis of synaptic plasticity in Purkinje cells with Masaki Sakurai and Pavich Tongroach. In order to monitor the parallel fiber-to-Purkinje cell transmission, we examined the probability of occurrence of spike responses in Purkinje cells to parallel fiber inputs. For the first step, we stimulated a vestibular nerve to excite a mossy fiber-granule cell-parallel fiber pathway to the flocculus. In December 1979, we clearly observed that, after conjunctive stimulation of the vestibular nerve and climbing fibers at the inferior olive, the probability of Purkinje cell responses to the vestibular nerve stimulation was reduced for a time period of 1 hour. By exploring with microelectrodes in and out of the flocculus, we examined the possibility that the vestibular nerve signals are reduced in the course of conduction to flocculus Purkinje cells, and we concluded that long-term depression (LTD) occurs at the parallel fiber-to-Purkinje cell synapses (Ito et al., 1982). Using stimulation of parallel fibers on the surface of the cerebellum, we obtained further evidence of sustained depression of parallel fiber-to-Purkinje cell transmission (Ito and Kano, 1982; Ekerot and Kano, 1985). Sakurai, in 1987, reproduced the LTD in an intracellular recording from Purkinje cells in rat cerebellar slices in vitro.

Despite my confidence about our observation on LTD, my presentations were unpopular at all four of the meetings held in 1980: The Cerebellum—New Vistas at NIH, Brain Mechanisms of Perceptual Awareness and Purposeful Behavior in Pisa, the 28th IUPS Congress in Budapest, and Neural Communication and Control in Debrecen, the first one in May and the latter three in July. Many colleagues in the field seemed to be of the opinion that no such plasticity exists, or that if it does, it is potentiation and not depression. Nevertheless, I was warmly encouraged by Ragnar Granit who, one day during the Pisa symposium, invited me to a restaurant together with G. Moruzzi and quoted Danton’s famous words on audacity. After the Debrecen meeting, B. Juresz, as he told me later, wrote to David Marr, who was seriously ill in bed at that time, that the synaptic plasticity hypothesis had received experimental support.

What we found was LTD, as predicted by Albus (1971), and not potentiation as assumed by Brindley (1964) or Marr (1969), but I don’t think that this detracts from Brindley’s or Marr’s theoretical formulation. Learning in the simple perceptron is based on a combination of two types of plasticity: potentiation occurs when a machine’s answer is correct, and depression occurs when it is erroneous, but the simple perceptron still learns, though with a reduced efficacy, with only one type of synaptic plasticity which can be either potentiation or depression. Because it would be difficult to equip a real synapse with both types of plasticity, nature appears to have chosen depression for several practical reasons, as pointed out by Albus (1971), but not for a theoretically logical reason.

After these meetings, I suffered from gallstones and was hospitalized. My further distress was that our short report on LTD was turned down by Nature, apparently reflecting the skepticism about the synaptic plasticity assumption prevailing among cerebellar physiologists at that time. I was relieved when our full report was later accepted for publication in the Journal of Physiology (London) (Ito et al., 1982).

Cerebellar Corticonuclear Microcomplex

Since 1976, I had been invited by Raven Press to write a monograph on the cerebellum, but I hesitated to start writing because of the uncertainty about the synaptic plasticity. When I obtained the first evidence of LTD in 1979, I immediately began to write the monograph, which was published in 1984 as The Cerebellum and Neural Control. With all Saturdays and Sundays devoted to it, it took about 1 month to complete each chapter, and more than 3 years to complete the entire monograph. In December 1983, I proofread the final draft in a hotel in downtown New York in 3 days, during which I slept for a total of only 3 hours. The book appeared in 1984 with my own simple cover design of Purkinje cells, and was dedicated to my mother, who had died in January of 1984 at the age of 92.

What I attempted in this book was integration of the three lines of information available on the cerebellum at that time: morphological, physiological, and chemical data of cerebellar cells and their networks, leading to formation of neuronal network models; morphological and electrophysiological data of neuronal connections in and out of the cerebellum, leading to a conception of control system models of the cerebellum; and functional and behavioral data suggesting the functional roles of cerebellar activity. The core concept proposed in the book is that the cerebellum consists of numerous functional units, called cerebellar corticonuclear microcomplexes (referred to below as microcomplexes). A microcomplex consists of four components: (1) a microzone of the cerebellar cortex as defined by the late Olov Oscarsson (1976), (2) a small group of neurons in vestibular or cerebellar nuclei receiving Purkinje cell inhibition from the microzone, (3) bundles of cerebellar afferent fibers arising from small groups of precerebellar structures and supplying excitatory synapses to the nuclear neurons and mossy fiber terminals to the microzone, and (4) a bundle of fibers originating from a small group of inferior olive neurons and supplying climbing fibers to the microzone and excitatory synapses to the nuclear neurons. While a mossy fiber input is converted to a nuclear output through a microcomplex, the input-output relationship is modifiable due to LTD induced in the microzone by error signals conveyed by the climbing fibers. A microcomplex is an adaptive unit of the cerebellum; like a computer chip, it is attached to a bodily control system, affording it with adaptiveness.

With a microcomplex attached, a reflex or a compound movement system, such as is used for locomotion and saccadic eye movements, would be converted from a classic control system to an adaptive one. In addition to the flocculus control of the VOR, eye-blink conditioning (cf. Thompson, 1987) may be considered to be a case of reflex adaptation. Adaptive adjustment of perturbed locomotion has been shown to be a function of the cerebellar vermis (Yanagihara and Kondo, 1996). For voluntary movements, however, a microcomplex appears to be used in a different way, that is, for forming a functional model of the motor plant including muscles, bones, and associated spinal cord mechanisms, as I proposed earlier (Ito, 1970). When command signals for a voluntary movement are sent from the cerebral motor cortex to the motor plant, the emerging movement effect would be fed back through sensory systems to the motor cortex; a voluntary movement would be performed based on the external feedback through sensory systems. If the motor cortex sends the same command signals to the cerebellar model, which projects back to the motor cortex through the cerebrocerebellar communication loop, the voluntary movement can be performed without use of the external feedback, by using the internal feedback through the cerebellum.

A microcomplex is expected to form a model by the following mechanism: suppose that a microcomplex is connected in parallel to an original system to be modeled. While both the microcomplex and the original system are fed by common input signals, any difference between their output is fed back to the microcomplex as error signals through climbing fibers. While this is repeated, the dynamics of the microcomplex will become equivalent to that of the original system. The model formation is a consequence of the adaptive mechanism, and nature seems to have found this new use of the cerebellum when the cerebral cortex emerged during evolution.

Unified Theory of Cerebellar Control

Since 1984 there have been two lines of development in our knowledge of the roles and mechanisms of the cerebellum. Kawato et al. (1987) described a model of voluntary cerebellar control, in which a microcomplex is placed parallel to the cerebral motor cortex. The motor cortex acts as a feedback controller, while the microcomplex serves as a feedforward controller, and both receive the same instruction signals and act to control a common motor plant. This parallel combination of a feedback and a feedforward system constitutes a so-called 2 degrees of freedom control mechanism. If the microcomplex, as a feedforward controller, acquires through learning dynamics equal to the reciprocal of the arm’s dynamics (i.e., an inverse dynamics), the trajectory represented by instruction signals fed to the microcomplex will be converted to the actual arm trajectory with fidelity. Kawato et al. (1987) demonstrated that a robot equipped with a 2 degrees of freedom control mechanism acquires a skillful arm movement after practice in a humanlike manner. Further, Shidara et al. (1995) found that Purkinje cell discharge in the ventral paraflocculus during eye movements represents an inverse dynamics of eyeballs.

The control system model proposed in 1970 matches the anatomically demonstrated cerebrocerebellar loop through the motor cortex and the intermediate part of the cerebellum, and explains how practice enables us to perform voluntary movements without feedback: for example, hitting a golf ball with your eyes closed. The Kawato et al. (1987) inverse dynamics model matches the parallel connections between the cerebral association cortex and the cerebellar hemisphere, and explains how practice enables us to perform voluntary movements without conscious attention. Currently, I think that these two control system models represent two different modes of learning in voluntary movements: one eliminates the need for external feedback and the other eliminates the need for conscious efforts to conduct movements. The former would involve the intermediate part of the cerebellum associated with the interpositus nucleus, and the latter, the cerebellar hemisphere associated with the dentate nucleus.

Another remarkable development concerning involvement of the cerebellum in mental activity was proposed by Leiner et al. (1986) based on the idea that the evolution of the human cerebellum parallels the enlargement of the cerebral association cortex. I turned to this problem when I was elected to serve as dean of the Faculty of Medicine of the University of Tokyo and so was completely deprived of opportunities to engage in laboratory work during the 2 years from 1986 to 1988. I paid attention to the close similarity between movement and thought from the viewpoint of their control mechanisms. To move, we operate parts of our body such as arms and legs, and to think, we manipulate ideas, concepts, and images encoded in our brain, presumably in the temporal-parietal association cortex. The targets of control are entirely different in these two types of control activity, but the mechanisms of control could be equivalent for them. I presented this view at the Principles of Design and Operation of the Brain symposium held in 1988 in the Pontifical Academy at the Vatican (Ito, 1990).

From a functional point of view, the brain evolved in five steps, with the cerebellum involved in all five: The brain stem and spinal cord developed three categories of function: reflexes, compound movements, and innate behaviors, the latter including food intake, drinking, and mating. Involvement of the cerebellum in reflexes and compound movement is now established, but cerebellar involvement in innate behavior is much less evident and needs further investigation; nevertheless, it is suggested by the existence of neural connections between the hypothalamus and the cerebellum. The fourth function of the brain is the sensorimotor cortical function, found in lower mammals. The above-mentioned control system models of voluntary movements should apply to this fourth brain function. The fifth brain function—thought—emerges from the association cortex as typically developed in primates, including humans. The inverse-dynamics control system model would apply to it. In this way, one could explain the diverse roles of the cerebellum systematically at all five of the hierarchical levels of brain function on the common ground of the microcomplex concept.

When my university career ended in March 1989, I gave my last physiology lecture to medical students and colleagues at the University of Tokyo. I explained how a normal person can touch the nose with his or her index finger accurately even with eyes closed, whereas cerebellar patients fail to perform this finger-to-nose test. This movement is apparently performed by using a model of the motor plant for fingers in the cerebellum, and cerebellar patients, lacking the model, are unable to touch the nose accurately unless the finger movement is controlled visually. At the end of my talk, I referred to the saying that while an unwise person only tries to adapt to his or her environment, a wise person thinks about how to change his or her environment. The cerebellum is an adaptive organ which may seem like an unwise person, but it enables the cerebrum to display its creativity. We must be aware of the important roles which the cerebellum plays behind the scenes. This is the answer to my long-standing question of what the cerebellum really does.

I presented this unified theory of cerebellar control in the first Ragnar Granit Lecture in Neuroscience in Stockholm in April 1991, but it was a most regrettable event that Ragnar Granit had passed away just a week before my lecture. I also had chances to present my theory in the symposium on Brain Mechanisms of Perception and Memory, held in Toyama, Japan, in 1991 (Ito, 1993a), and a Charcot lecture to neurologists in Paris, in June 1992 (Ito, 1993b). I wrote an article for a special issue of Trends in Neuroscience devoted to the debate on mental functions of the cerebellum, together with Robert Dow (Ito, 1993c), and was given a Robert Dow Award in Neuroscience in August 1993 directly from this great authority of cerebellar pathology. Since those days, supportive evidence for the involvement of the cerebellum in thought has accumulated in brain imaging experiments, as recently compiled in a monograph edited by J.D. Schmahmann (1997).

Signal Transduction in LTD

In my last lecture at the University of Tokyo, I had little to say about signal transduction processes underlying LTD, except that Ca²⁺ entry into a Purkinje cell caused by climbing fiber signals is required for induction of LTD, and that LTD is basically due to sustained reduction of glutamate sensitivity of Purkinje cells. Based on the little information available in the literature, I speculated that cyclic guanosine 5’-monophosphate (GMP) plays a role in induction of LTD (Ito, 1989). In April 1989, I moved to the Institute of Physical and Chemical Research which was founded in 1917 and is commonly known by its nickname, Riken (based on its name in Japanese). My task was to establish a new neuroscience group in the frontier research program, which was launched in 1987 at Riken to cover emerging new research fields such as biotechnology, nanotechnology, glycobiology, and neuroscience. In the neuroscience group, I set up a laboratory to investigate cellular and molecular processes underlying LTD with a number of colleagues including, initially, Katsuei Shibuki, Daisuke Okada, Laddawan Karachot, Ray Kado, Tetuso Yamamori, Kazutosi Nakazawa, and Ayako Ajima, and later Nick Hartell, Mariko Miyata, Dai Yanagihara, Hiroshi Kojima, Hirokazu Hirai, and researchers in other frontier research program laboratories.

Since around 1990, LTD and related phenomena had been taken up in the laboratories of Francis Crepel, David Linden, Arthur Konnerth, Tomoo Hirano, Susumu Tonegawa, Roger Tsien, and others, and studies of LTD had become a popular theme in neuroscience. During the past 10 years, we collected data suggesting the roles of nitric oxide, cyclic GMP, protein kinases C and G, metabotropic glutamate receptors, protein phosphatases, corticotropin-releasing hormone, and immediate early genes in LTD induction. At the final step of the complex signal transduction processes involving these receptors and messengers, α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors mediating parallel fiber-to-Purkinje cell synaptic transmission are likely to be phosphorylated, and my particular interest has been in visualizing those synapses undergoing LTD by using antibodies raised against phosphorylated AMPA receptors (Nakazawa et al., 1995). These new lines of knowledge provide new means to either facilitate or block LTD and to visualize its occurrence, which will be useful in identifying roles of LTD in cerebellar functions.

Question for the Future

In the fall of 1996, I was invited to deliver a Warner-Lambert lecture at the annual meeting of the Society for Neuroscience held in Washington, DC. After describing the development in cerebellar studies during the past 3 to 4 decades, I proceeded to speculate about future directions for neuroscience. It is evident that neuroscience has come of age and that, in the coming century, it will develop fully. Explosive expansion of our knowledge at cellular and molecular levels will eventually enable us to find ways to prevent or cure brain aging and neurological and psychiatric diseases. However, the path that will lead us toward an understanding of the brain mechanisms underlying our mind and behavior is still unclear. Around 1970, I anticipated two lines of development that might follow the great strides made in cerebellar studies. One is our understanding of the mechanisms and roles of synaptic plasticity in cerebellar networks, which, even though much slower than I expected, has advanced much during the past 3 decades. The other is the proliferation of network and system models, which could be applied to other parts of the brain such as the basal ganglia, hippocampus, thalamus, hypothalamus, and the cerebral cortex. Even though marked progress has been made by the discovery of multilayered perceptrons, socalled neurocomputers, these advances have not yet met my expectations. Some information about the brain essential for such modeling seems to be still missing. What we need to find in the brain in order to proceed beyond the framework of neuroscience so far set by cerebellar studies, is the profound question now before us.

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Martin G. Larrabee

BORN:

Boston, Massachusetts

January 25, 1910

EDUCATION:

Harvard College, B.A. (1932)

University of Pennsylvania, Ph.D. (1937)

APPOINTMENTS:

University of Pennsylvania (1934)

Cornell Medical College (1940)

University of Pennsylvania (1941)

Johns Hopkins University (1949)

HONORS AND AWARDS:

National Academy of Sciences, U.S.A. (1969)

Martin Larrabee did pioneering work on the electrophysiology and metabolism of sympathetic ganglia throughout his career. As part of his thesis work on the cat stellate ganglion with Detlev Bronk, he discovered the phenomenon of ‘‘prolonged facilitation,” which David Lloyd later demonstrated in monosynaptic spinal reflexes and called ‘‘post-tetanic potentiation.”

Martin G. Larrabee

After being imposed on the world in Boston, Massachusetts, on January 25, 1910, by parents of old New England stock, I grew up in a five-story, brick, row house that my grandfather had built in that city.

My father was a physician whose recreational activities were mostly photography, hiking, and exploring and trail building in the White Mountains of New Hampshire. He participated in some of the earliest winter climbing around Mount Washington and edited the Appalachian Mountain Club’s White Mountain Guide for nearly 20 years. In a unique activity, for many years up to his death in 1935, he joined a group of professional men on Sundays year-round at the Appalachian Mountain Club’s “Woodlot” on a private estate in Dover, just outside of Boston. Among other activities, they felled trees, cut, split, and corded the logs, built a shack with a fireplace and stove, and constructed bridges, all for the sheer joy of physical effort and agreeable company. I frequently accompanied him there during my teenage years. My pleasant contacts with this group of older men, every one of whom I liked and respected, no doubt strengthened my ideals and affected my general attitude toward life. There and through innumerable enjoyable hikes with my father, I developed a lifelong love of woods and mountains, to which I have always escaped for vacations, either in the United States or in Europe. By extraordinary good fortune, at breakfast in a mountain hut in New Hampshire in 1936, I first met Barbara Belcher, who later become my wife of 53 happy years. In the 1970s I led the development of 30 miles of hiking trails in a state park and along a large reservoir near Baltimore.

In childhood I played with some excellent educational toys. One was Meccanno, a British construction set that included a great variety of gears among its many ingenious parts. For example, I built a differential gear system so that I could understand what was in that bulge in the rear axle of the auto ahead. I also had a Canadian electrical set, from which I wound a motor that actually ran and could be reversed or have its speed controlled by switches and rheostats that were made in such a way that one could see exactly how they worked. And I had a small shop next to my bedroom, where I took lessons in woodworking and built many radios. Perhaps this was a precursor to my later tendency to construct many of my own research gadgets and modify them as they developed under my own hands, rather than submitting complete designs to the laboratory shop.

I prepared for college at Newton Country Day School, to which I commuted by trolley for 8 years. There I was drawn to mathematics and physics. I found they were subjects one could get hold of—there was a clear distinction between right and wrong—so that you usually knew where you stood when you had finished a problem. Also, at nearby Massachusetts Institute of Technology, there were fascinating Saturday morning physics lectures directed at high-school students, with lots of exciting demonstrations.

Harvard College

I graduated from Harvard College with a B.A. in physics in 1932, after once considering changing to engineering. While in college I spent one summer at the physiological optics lab at Dartmouth College, assisting ongoing studies of the effects of size differences between the retinal images in the two eyes and designing lenses to correct this disparity. Then, during my junior year, I saw on a bulletin board an announcement of a then bounteous scholarship of $300 in biophysics at the Johnson Foundation at the University of Pennsylvania. Almost simultaneously my father showed me a report of the foundation’s program in the Journal of the American Medical Association. So I wrote to the director, Detlev Bronk, who suggested that I spend the following summer, 1931, at the Marine Biological Laboratory in Woods Hole, Massachusetts, working with Keffer Hartline. That was the very summer in which Hartline first recorded from single fibers from the eye of the horseshoe crab (Hartline and Graham, 1932) and thus began the work that eventually earned him a trip to Stockholm, a dance with the Queen of Sweden, and other matters.

At Woods Hole that summer or the next I also worked with Baldwin Lucke, a pathologist from the University of Pennsylvania, studying the osmotic properties of Arbacia eggs by measuring the time course of volume changes after transfer to various solutions. The procedure involved microscopic measurements of the diameter of individual eggs, repeated until statistically respectable data were accumulated. This seemed rather tedious, so I made my first contribution to science by suggesting a diffraction method that would measure the average diameter of hundreds or thousands of eggs at a time. The following summer I assisted Lucké in using this method, and it resulted in my first coauthorship (Lucké et al., 1935).

Through these experiences I decided that science was fascinating, rewarding, and fun, and that its practitioners were friendly, stimulating, and thoroughly honest.

University of Pennsylvania, the Johnson Foundation

In the fall of 1932 I arrived at the Johnson Foundation, which was also the Biophysics Department in the graduate school at the University of Pennsylvania. I spent lab rotations on frog muscle physiology with Emil Bozler, on effects of X-radiation on the metabolism of fern spores with Raymond Zirkle, and on blood pressure responses to pulsatile perfusion of the carotid sinus of the cat with Bronk.

Transmission through Sympathetic Ganglia

After this, Bronk adopted me as his personal research assistant and set me studying transmission through the stellate sympathetic ganglion of the cat. The procedures allowed either maintenance of normal circulation under artificial respiration or an artificial perfusion system which I later developed using an idea that came to me while sitting on a boulder in the middle of a New Hampshire stream. My doctoral thesis on these preparations established the groundwork for several papers, publication of which was long delayed while the manuscripts travelled afar in Det Bronk’s briefcase during World War II. Although my degree was awarded in 1937, two of the three resulting papers were not published until some 10 years later!

A major finding in my thesis research was a phase of increase in the number of ganglion cells responding to a volley of presynaptic impulses, which lasted many seconds or minutes after a series of conditioning volleys over the same presynaptic axons. This increase did not occur after conditioning volleys over axons other than those used for testing and was not produced by volleys sent into the ganglion antidromically over the postsynaptic fibers. Therefore we concluded that activity caused long-lasting changes in the presynaptic endings, such that they delivered a stronger stimulus to the postsynaptic cells (Larrabee and Bronk, 1938, 1947). We termed the phenomenon “prolonged facilitation.” After our reports, David Lloyd at the Rockefeller Institute demonstrated the same phenomenon in monosynaptic reflex arcs in the spinal cord and resoundingly renamed it “post-tetanic potentiation” (Lloyd, 1949). This is rather a misnomer, for the phenomenon can be demonstrated after a single stimulus under suitable conditions, although Lloyd was unable do so in his preparations. These findings changed the thinking of some leading reflex physiologists, who had hypothesized that enduring after-effects on reflex responses resulted from the late arrival of impulses from closed chains of neurons, around which impulses had been set reverberating by the conditioning activity. There ensued an extensive literature applying the new name to superficially similar phenomena elsewhere in the nervous system, sometimes uncritically without demonstrating its presynaptic localization.

A second finding on the stellate ganglion dispelled another contemporary notion, that synaptic transmission was always significantly more sensitive to ischemia than was simple conduction along axons, so that this characteristic could be used to distinguish synaptic from nonsynaptic pathways. The stellate ganglion that we were studying contained not only a transynaptic route to the inferior cardiac nerve, but also many axons that passed through uninterruptedly to form the cervical sympathetic trunk. Thus these two kinds of pathways could readily be submitted to identical conditions of ischemia. The result was that conduction over many axons failed before the last of the synaptic pathways were blocked (Bronk et al., 1948).

Thus the relatively simple anatomy of sympathetic ganglia and their ready access for well-controlled experiments began to establish them as useful tools for understanding basic cellular physiology in more complex situations, such as those in the central nervous system. At the same time W. Feldberg and his associates, in studying the pharmacological properties of these ganglia, were initiating the whole field of chemical transmission at neuron-neuron synapses.

Some of my observations on ganglionic transmission at that time were made on responses in single fibers dissected from the inferior cardiac postganglionic nerve. These dissections were very difficult because the postganglionic fibers in this nerve are unmyelinated and thus belong to the smallest and most delicate class of nerve fibers. For some reason I added glucose to the dissecting medium; this was fortunate, because years later it was found that these small nerve fibers are especially sensitive to lack of this substance (Larrabee and Bronk, 1952). However, when I attempted to resume such recording after it was interrupted by work related to World War II, I could not again accomplish it.

During my graduate student days I contributed to the general techniques of electrophysiology by discovering serious distortions caused by hysteresis in the varying magnetic field of the then-popular Matthews Mirror Oscillograph. This resulted in its replacement by constant-field mirror oscillographs until cathode ray devices became generally available. I also revealed a treacherous tendency of stimulating current to spread to unintended nerves, caused by badly arranged systems, which led to the practice of placing an isolating transformer close to the preparation. I clearly remember the day that Ian Gaylor (from Scotland) and I discovered this flaw, for it had caused a serious error in my doctoral dissertation, which happened to be in the hands of the referees at that very moment.

With a distinct feeling of discomfort I recall that in those days we made our dissections in a small electrically shielded enclosure that was heated to body temperature and humidified to saturation. We dashed in and out of this enclosure to take recordings via amplifiers that were located outside. The recordings were made on seemingly endless strips of photographic paper, which sometimes reminded me of Laocoon and the serpents when I was hassling them through the dark-room developing tanks.

Being Det Bronk’s research assistant, my laboratory experiences were broadened by requests for collaboration from other departments, especially pharmacology. There were experiments on the cerebral cortex of cats with mescaline, also some with picrotoxin (a convulsant that produced large, intermittent discharges over the sympathetic nervous system), and recording of convulsant activity in the cerebral cortex caused by cortical stimulation. I also assisted Robert Pitts, a fellow of the Rockefeller Foundation, who came equipped with a Horsely-Clark stereotaxic instrument, in recording the responses of the sympathetic nervous system to stimulation of the hypothalamus (Bronk et al., 1940; Pitts et al., 1941).

Cornell Medical School

In 1940 Det Bronk accepted the chairmanship of the Department of Physiology and Biophysics at the Cornell Medical School in New York City and took along his close associates, including Keffer Hartline, Arthur Rawson (mechanical engineer), John Hervey (electrical engineer), Frank Brink, Philip Davies, Glen Millikan, and me. During the first semester we taught neurophysiology to a class that had already studied other aspects of physiology. In the second semester we conveniently reversed the order of topics and started the new class with neurophysiology. After that we went back to Penn, thus avoiding topics we didn’t know much about.

Respiratory Reflexes

That year at Cornell I had the pleasure of working with Clint Knowlton, a Commonwealth Fund postdoctoral fellow. We recorded the responses to inflation of the lungs of cats in single afferent fibers ascending the vagus nerve and in single efferent fibers descending to the diaphragm in the phrenic nerve. In addition to the well-known, slowly adapting receptors in the lungs and their reflex inhibition of inspiration, we discovered a second set of pulmonary afferents that were activated only on deeper-than-normal inspiration and rapidly adapted when the inspiration was maintained. Their reflex action promoted, rather than inhibited, inspiration. We concluded that this reflex would augment any deep inspiration, as in preparing for a sneeze or cough, and dubbed it the “autogenous pulmonary reflex” (Larrabee and Knowlton, 1946; Knowlton and Larrabee, 1946).¹

Back to the Johnson Foundation at Penn—the War Years

Det Bronk led us all back to the Johnson Foundation at Penn in the summer of 1941, and soon the lab became deeply involved in research related to World War II. The following are some activities of which I was aware at the time.

Det, as Special Consultant to the Secretary of War, served as Coordinator of Research in the Office of the Air Surgeon General and was away much of the time in Washington and other parts of the world. Among other things, he was involved in organizing and recruiting for the Aviation Physiologists program, which instructed air crews in the physiological problems of high altitudes. He was also a member or chairman of numerous committees concerned with research in the war effort (Brink, 1979).

Frank Brink was Civilian Consultant to the Secretary of War assigned to the Air Surgeon General’s Office and spent much of his time writing reports in that office at the Pentagon.

Hartline worked on vision problems, helping to persuade the U.S. Navy to change ship deck lighting from blue to adaptation-preserving red, developing head-worn infrared binoculars for landing aircraft and driving vehicles in the dark, studying the visual distortion caused by thick plastic enclosures over cockpits in fighter planes, determining the optimum degree of magnification for hand-held binoculars, and various other advisory and experimental projects for the armed services. These efforts were assisted by Lorus Milne and Irving Wagner.

Glen Millikan, in cooperation with the Coleman Instrument Co., developed the oximeter to determine the oxygen saturation of the blood in highaltitude flyers by measuring the color of blood with light transmitted through the ear. A modification of this device that fits over a finger is now widely used in medicine, especially in operating rooms.

John Pappenheimer, who joined the Johnson Foundation for the war years, measured accumulation of dangerous concentrations of carbon monoxide in military tanks during maneuvers and firing. He also investigated possible use of the “oxygen candle,” a disagreeable looking solid chemical that, when ignited, liberated more oxygen than it consumed. This is apparently the same material that caused a brief fire on the Russian space station in early 1997.

John Lilly developed the electrical capacitance manometer, with displacements so small that tracings of pulsatile blood pressure could be obtained through intraarterial needles. He also helped in many other projects.

Many tests of psychomotor performance and susceptibility to the bends were conducted in altitude chambers at the Medical School, first in a twoman chamber improvised out of a commercial candy-cooker by our mechanical engineer, Arthur Rawson, and later in a standard Air Force multiperson refrigerated chamber. I arrived at the altitude lab one day to find three physiology professors inside the big chamber screaming over the intercom, “Its going up! Its going up!” Meanwhile a high school student at the controls outside was staring at the rate-of-climb indicator and replying, “No it isn’t! No it isn’t!” The indicator was indeed reading zero, but only because the rate of climb was so fast that the needle had completed a 360° turn! Moreover, the altitude was getting dangerous. So I pushed the operator aside and halted the ascent, thus making a significant contribution to physiology.

In the altitude chambers, Robert Hodes and I tested the effects of ingestion of various chemicals on tolerance to anoxia, including ammonium chloride, nicotinic acid and its amide (suggested by Royal Calder, a physician of Houston, Texas), and methylene blue (suggested by Matilda Brooks).

Julius Comroe of the Pharmacology Department, John Lilly, Robert Hodes, and I undertook a major project, involving many medical student volunteers, to help validate a procedure proposed by the U.S. Air Force to select crews resistant to the “bends.” The latter are severe pains caused by gas bubbles in the tissues that were incapacitating some high-altitude flyers.

In collaboration with the Princeton Branch of the Fire Control Division of the Frankford Arsenal, I converted my office into a shooting gallery (no shots were fired), to compare various methods of determining the angle of lead necessary to hit a moving tank. I projected a picture of a beautiful California valley onto a long-paper kymograph, across which brown-paper tanks would travel at any desired speed. The subjects used binoculars with reticles of various design to estimate the angle traversed by the target tank between timer clicks that were separated by intervals equal to the time-offlight of a projectile.

Toward the end of the war, in an operating room at the army hospital in Framingham, Massachusetts, Hodes and I attempted to measure regeneration across nerve sutures by standard eletrophysiogical techniques. This was rather unsuccessful because of severe problems caused by the stimulation artifact when recording from nerves in continuity. Hodes and I also collaborated with William German, a neurologist at the Philadelphia Naval Hospital in evaluating peripheral nerve injuries by percutaneously stimulating the nerves above the injury and recording the action potentials thus evoked in muscles below the injury. We extended this method to all the major nerves in the extremities and obtained some elegant recovery curves by reexamining war victims over a period of several months. We also determined conduction velocities, in both injured and uninjured nerves, by measuring the difference in latency when stimulating at two different distances above the muscle. We were surprised to find that the normal velocities were considerably slower in nerves to the intrinsic muscles of the hand and foot than in those to the more proximal muscles that moved these same extremities. This was the first application of the method of nerve-evoked electromyograms to such a wide variety of nerves, and it resulted in my only substantial scientific paper from the war work (Hodes et al., 1948). From these experiences I developed a deep respect for the diagnostic skills of a neurologist in evaluating a cooperative patient without the aid of gadgetry. However, we could help in cases of suspected malingering or hysterical paralysis by definitively demonstrating the integrity of the peripheral nerve–muscle system.

In concluding this admittedly incomplete description of the Johnson Foundation’s contributions to the war effort, I must recognize the essential contributions of our engineers, Arthur Rawson and John Hervey, who were involved in almost every project and without whose support we could never have achieved as much. I should also cite the staff of our excellent machine shop under Rawson, especially Victor Legallais.

After the War

Mostly Effects of Anesthetics on Sympathetic Ganglia

As life returned to normal after the war, and the prewar work was written up and published, I again ventured briefly into respiratory reflexes, this time with Hodes (Larrabee and Hodes, 1948). Then I resumed the study of sympathetic ganglia, which I found suitable for a great variety of investigations and became my prime object of study for the rest of my career. Many sympathetic ganglia can be studied in situ, and some problems can even be investigated in waking, unanesthetized animals (e.g., Larrabee, 1968). Alternatively, some ganglia can be perfused or excised with relatively little damage and bathed with artificial solutions, thus exposing them to wellcontrolled environmental conditions. Moreover, the ganglion cells are at rest unless stimulated, and activity can be induced by naturally conducted nerve impulses initiated by electrical stimulation of the preganglionic nerve some distance away. This permits observation of effects of activity on metabolic processes without concern about abnormal applications of current or of electrode products to the cells under study, which occur in some preparations of excised brain tissue.

And now began the pleasure of associating with postdoctoral fellows from other countries. The first was Jean Posternak from Geneva. He and his wife, Yvonne, became good friends, and my wife, Barbara, and I later visited them many times in Switzerland.

Jean and I briefly studied the effects of a natural release from the adrenal glands, after brief clamping of the aorta, that could completely block transmission through sympathetic ganglia (Posternak and Larrabee, 1950). We then initiated an investigation of the effects of many anesthetics on synaptic transmission through the ganglia and on conduction along associated nerve trunks. We quantitatively defined the degree of selective action of an anesthetic on synaptic transmission as the ratio of (a) the concentration required to reduce the maximal compound action potential of the preganglionic nerve trunk by 50% to (b) the concentration required for similar action on the postsynaptic response. Both the blocking potency, as measured by the molecular concentration needed, and the degree of selective action tended to increase systematically with molecular weight, reaching a 10-fold selectivity with pentobarbital, which was the heaviest agent we tested (Larrabee and Posternak, 1952).

About this time I began to measure the oxygen uptake of sympathetic ganglia, exploiting the oxygen electrode that Philip Davies had developed for rapidly measuring tissue oxygen concentration (Davies and Brink, 1942; Davies, 1962). Phil also devised ingenious procedures to prevent the electrode from becoming obstructed by nonreactive substances, such as proteins attracted by the electric field, and from movement of the solution to which it was exposed. He applied it to the cerebral cortex of cats, measuring oxygen concentration and metabolism with impressive spatial resolution (Remond et al., 1946).

Jean Pasternak and I thrust a sharpened version of the oxygen electrode into the stellate ganglion of the cat and estimated the rate of oxygen consumption from the rate of fall of concentration when the blood flow or an artificial perfusion was suddenly stopped. We demonstrated increases in oxygen consumption during activity induced by stimulating either the preganglionic or postganglionic nerves, and were even able to detect an acceleration after as few as two volleys of impulses (Larrabee and Bronk, 1952).

Leaving the Johnson Foundation

Here we come to the end of the Johnson Foundation years, and I cannot leave them without reflecting on what a wonderful experience it was. Det Bronk took care of the finances before the days of federal largess, frugally spending the income from the endowment. The latter was in memory of Eldridge Reeves Johnson, who is credited with building the first talking machine when it was invented by Thomas Edison. Det also obtained grants from various sources, including the Supreme Council of the Scottish Rites Masons, the National Foundation for Infantile Paralysis, and the American Philosophical Society. We were a close-knit, highly cooperative group, with few responsibilities other than the conduct of the best research of which we were capable. We lunched together in the department library, where we were joined by several research-oriented physicians from the medical school and hospital, in which we were located. Lunch conversations ranged from serious discussions of each other’s research problems and triumphs to trivial pursuits, such as calculating the time required for a nerve impulse to reach the moon. Electrophysiological experiments were not started until after lunch, due to electrical disturbances in the morning from diathermy machines on the floor below, but frequently continued far into the night after a nucleus had supper together at a nearby restaurant. Again, the engineering support by Arthur Rawson and John Hervey was most important to our work. Art’s policy of keeping the excellent machine shop always open to our tinkering was most helpful, even though someone occasionally strained his kindly Quaker disposition almost to the breaking point. Many of the world’s best known neurophysiologists were Bronk’s friends and visited the laboratory, sometimes followed by an evening at the Bronks’ home for further discussions. Among those that I recall were Herbert Gasser, head of the Rockefeller Institute, Ralph Gerard from Chicago, E.D. (later Lord) Adrian from Cambridge, England, and J.C. (later Sir John) Eccles from Australia. In an informal way, a number of us would frequently drift out to the Bronks’ country home on Sunday afternoons. Helen Bronk, a saint-on-earth in many ways, would cheerfully feed supper to all who wanted to stay, without previous knowledge of the number, without kitchen help except for any wives who happened to be present, and before the days of microwaves and deep-freezers. In the stimulating and friendly environment of the Johnson Foundation, we were a harmonious, secure group that laughed a lot. I wish I had memory and space for more of the humor.

Johns Hopkins University and the New Department of Biophysics

On January 1, 1949, Bronk became president of Johns Hopkins University. There he had found an endowment for a biophysics department that had not yet been formed, so he led his team southward to fill the gap. Included were all participants in the earlier migrations to Cornell Medical School and back, except for Arthur Rawson, who had already taken a position at the Army’s Camp Detrick laboratories in Frederick, Maryland. Also included were graduate students Francis Carlson, Ted MacNichol, Lloyd Beidler, Clarence Connelly, and Paul Hurlbut; all except Beidler stayed as departmental members after receiving their degrees. Keffer Hartline was appointed chairman of the new Thomas C. Jenkins Department of Biophysics. Until our new building was completed a year or two later, most of the group was lodged in rooms loaned by the Biology Department in the Faculty of Arts and Sciences on Hopkins’ Homewood Campus. However, I was provided generous laboratory space by Abner McGehee Harvey in the Department of Medicine at the Medical School and Hospital complex in East Baltimore. There I was in frequent contact with Vernon Mountcastle in Physiology, Stephen Kuffler in Ophthalmology, and John Magladery in Neurology. Also, I was especially helped in getting oriented by Joseph Lillienthal and Kenneth Zierler in the Department of Medicine.

More on Anesthetics in Sympathetic Ganglia

At this time the leading theory of anesthetic action was that these agents primarily depressed oxidative metabolism and that the suppression offunction was a secondary effect of the metabolic disturbance. This theory was supported by some observations on oxygen consumption by excised brain tissue, but it seemed to me that the concentrations employed might be excessive and that better controlled experiments could be made on sympathetic ganglia, where we had by then developed techniques for measuring oxygen uptake and synaptic transmission simultaneously. Moreover, Duncan Holaday and I had shown in naturally circulated cat ganglia that transmission was affected at surgical levels of anesthesia with ether and chloroform, so that the sensitivities of sympathetic synapses to at least some anesthetics were similar to those in the central nervous system (Larrabee and Holaday, 1952). Joined by Juan Garcia Ramos from Mexico City and later by Edith Bulbring from Oxford, England, we found on superior cervical ganglia excised from rabbits that seven different anesthetics all suppressed the transynaptic response by as much as 50% at concentrations that had no detectable effect on oxygen consumption. In contrast, two typical metabolic poisons, cyanide and azide, both affected oxygen metabolism at least as much as they did synaptic transmission (Larrabee et al., 1952). Thus the hypothesis of a primary effect of anesthetics on metabolism was not supported.²

The Superior Cervical Ganglion of the Rat

Searching for a laboratory animal more convenient than cats and rabbits, I tried various smaller species and found that superior cervical ganglia excised from rats survived well in a typical oxygenated, bicarbonate-buffered, physiological solution. Therefore I adopted this preparation for many subsequent investigations.

Effects of Lack of Oxygen and Lack of Glucose

Ramos, in a second and very thorough series of experiments, compared the survival of transmission through excised rat ganglia under various conditions of anoxia and aglycemia, separately and combined. He first showed that transmission survived about as long when both substances were supplied to an excised preparation as when the ganglia were left in situ with the natural blood supply after cutting the preganglionic nerve. Failure in the absence of glucose was accelerated by repetitive stimulation and delayed by preexposure to an elevated glucose concentration. The failure was also delayed by reducing the temperature of preparations stimulated infrequently, but was essentially independent of temperature when stimulated at frequencies above 1 per second. These and other results were reported in detail at a Cold Spring Harbor Symposium (Larrabee and Bronk, 1952).

Later we found that oxygen uptake was not greatly affected at the time of transmission failure caused by withdrawal of glucose, so energy metabolism must have shifted smoothly to endogenous substrates (Larrabee et al., 1957). William Stekiel, in his doctoral dissertation, subsequently showed that ammonia output was increased more than six-fold in the absence of glucose, indicating utilization of amino acids and/or proteins (Larrabee et al., 1957). F.J. Brinley, as part of his doctoral dissertation, found that glucose-free metabolism not only maintained the normal high internal potassium of the ganglion cells almost as well as did metabolism in the presence of glucose (Brinley, 1967), but also restored it after considerable potassium had been lost during temporary withdrawal of oxygen (Larrabee and Klingman, 1962). Thus the oxidation of endogenous substrates sufficed for some but not all functions. We speculated that protein used in the absence of glucose might be essential for conduction or transmission; in that case the eventual physiological failure would result from an active, rather than a passive, process.

Charles Edwards, who was the first graduate student to do his thesis research in my laboratory, adapted the glucose oxidase method to measure glucose depletion in 25-µl batches of solution that had bathed a rat ganglion. Anesthetics, surprisingly, increased glucose uptake considerably, accompanied by an increase in lactate output that accounted for most of the extra glucose (1955).

Pseudorabies Virus and a Puzzling Discharge of Impulses

In the early 1950s I was joined by John Dempsher, fresh out of medical school with fellowships from the U.S. Public Health Service and the National Foundation for Infantile Paralysis. He first tried the effects of various bacterial toxins on the rat ganglion, without interesting results. Then, at the First International Poliomyelitis Congress in New York City, I happened to sit at a banquet next to Albert Sabin, of polio vaccine fame. He told me that in attempting to infect the central nervous system with pseudorabies virus inoculated into the eyes of mice, he had sectioned the whole head and noticed typical lesions in the superior cervical ganglion. He suggested we investigate the effects of this virus in our rat preparations. Frederick Bang in Hopkins’ Department of Epidemiology offered to grow the virus for us, and David Bodian in Anatomy offered to do the histology. We found, about 2 days after inoculating the virus into the vitreous humor of one eye of a rat, that virus had appeared in the ipsilateral superior cervical ganglion, that many or all ganglionic neurons were histologically abnormal, and that remarkable spontaneous discharges of nerve impulses appeared in both the preganglionic and postganglionic nerves. These discharges involved many cells, lasted about 1 second, and were separated by silent periods of 1 or more seconds. At the earliest stage of infection spontaneous activity appeared only in the postganglionic nerve, at the latest stages only in the preganglionic nerve. The spontaneous discharges continued in the same patterns after the ganglia were excised. They never occurred in the ganglion contralateral to the infection and never in uninoculated animals. Since many different cells obviously fired in each burst, there was evidently some kind of communication from cell to cell. However, the mechanism remains a mystery because there are no known synaptic connections to accomplish this (Dempsher et al., 1955).

The Move to Homewood

In 1953 Bronk left Hopkins to become president of the Rockefeller Institute in New York City, taking along Hartline, Hervey, Brink, Connelly, and Hurlbut. I was invited to join them, but chose to remain at Hopkins. I moved my laboratory from the medical area to commodious space that then became available in the Biophysics Department at Hopkins’ Homewood Campus. I also obtained a research grant from the National Institutes of Health that became effective September 1, 1954, for studies on “Metabolism and Function in Sympathetic Neurons.” This was funded continuously for some 43 years, at least through November 30, 1997, and is the only funding outside of Hopkins that I ever sought.

Metabolism at Rest and in Activity

I now began a study of the changes in ganglionic metabolism that accompany the shift from the resting to the active state, which in our experiments was caused by naturally conducted nerve impulses that were initiated by stimulating the preganglionic nerve at some distance from the ganglion.

I built a respirometer for oxygen uptake, after the design of Carlson et al. (1950), in which sterile bathing fluid continuously flowed slowly past the ganglion while the concentration of the remaining oxygen was measured downstream with an oxygen electrode. According to suggestions of Philip Davies, the electrode tip was coated with collodion, which stabilized it in the bicarbonate buffer system being used and rendered it insensitive to movement of the solution. To enable ready sterilization, the respirometer chamber was made of glass, which gave me the fun of learning glassblowing on a rather small scale. The preganglionic nerve was pulled into a side arm with its own flow of solution, which permitted stimulation without danger of electrode products affecting the measured oxygen uptake. The postganglionic nerve was drawn into a channel in the plug that closed the top of the respirometer, in order to record the postganglionic response. With this I measured the resting rate of oxygen uptake and its increase during stimulation. The activity increment was readily measured during stimulation as infrequently as once per second, increased with frequency, and reached an upper limit about 40% above the resting level at 15 per second (Larrabee, 1958).

Paul Horowicz, then a graduate student, and Michel Dolivo from Lausanne, Switzerland, measured glucose uptake and lactate output by chemical methods (Horowicz and Larrabee, 1958; Dolivo and Larrabee, 1958). In ganglia at rest, the difference between these two rates provided enough substrate to account for about 92% of the oxygen taken up. Another 3% was accounted for by ammonia production, measured by William Stekiel, under the assumption that the ammonia was liberated on conversion of glutamine to glutamate and that the latter was all oxidized to CO₂. These results were in reasonable agreement with the contemporary understanding that glucose is the major substrate for energy production in neural tissues, although Stekiel’s ammonia measurements suggested a small contribution from amino acids or proteins.

By 1957 the Tracerlab CE-14 low-background system for beta counting had become available, with anticoincidence circuitry for reducing cosmic ray counts. The background counting rate was only about 1 count every 2 minutes, enabling us to measure ¹⁴CO₂ output from our small tissue samples, which had fresh weights of only about 1 mg. For this I built a system in which slowly flowing, humidified 5% CO₂–95% O₂ picked up the ¹⁴CO₂ from the incubation medium and, after dehumidification, carried it through a chamber sealed to a Geiger counter. Thus ¹⁴CO₂ output was measured continuously. (Twenty years later this apparatus was still in use in my laboratory.) Using glucose labeled with 14C, we could now measure incorporation of glucose carbon into CO₂ and, using paper chromatography, into various products in the tissue and in the bathing medium, without confusion from products of other, unlabeled substrates that would be included in chemical measurements.

The results on resting ganglia were that 64% of the glucose carbon went to CO₂ and 24% to lactate in the bathing fluid, while 12% was incorporated into tissue constituents, thus accounting for all of the carbon in the glucose.

However, the ¹⁴CO₂ output was only 86% of the oxygen uptake, raising a possibility of some oxidation of other substrates, which would have to be endogenous because no substrates other than glucose were provided in the bathing solution (Larrabee and Klingman, 1962). Moreover, there were greater problems concerning the extra metabolism that was associated with activity. When the preganglionic nerve was stimulated about five times per second, glucose uptake by the ganglion rose about 55% above the resting rate, but the chemically measured lactate output rose enough to account for much of the extra glucose. Only about 24% of the extra glucose remained after allowing for the extra lactate produced, and this could account for only about one-quarter of the extra oxygen consumed during the activity (Larrabee and Klingman, 1962). In contrast, experiments with [¹⁴C]glucose soon showed that much more than the 24%, in fact about half of the carbon in the extra glucose, was actually converted to CO₂ (Horowicz and Larrabee, 1962a,b). I believe this was the first unequivocal evidence for increased oxidation of glucose in neural tissue during activity. However, the increase in CO₂ output from glucose was only about 67% of the increase in oxygen uptake. A reasonable interpretation of all these findings is that extra glucose is indeed metabolized to CO₂ for energy production during activity, but that some endogenous substrate or substrates, possibly including glycogen, are also used, both for production of lactate and for oxidation to CO₂. Stekiel had found no increase in ammonia production during activity, so proteins or amino acids seem unlikely candidates (Larrabee et al., 1957).

Similar questions concerning the extra substrates used during activity have arisen in recent studies of human brain by noninvasive PET and MRI techniques (Barinaga, 1997). However, I confess difficulty in comprehending how reliable metabolic rates can be deduced from such measurements of the concentrations of naturally present substances in a tissue with an intact and variable circulation of blood.

Phospholipids

My next foray was into phospholipids, stimulated by reports that acetylcholine in the presence of eserine increased the labeling of phosphatidyl inositol (PI) and phosphatidic acid in a variety of tissues (Hokin et al., 1960). However, the concentrations of acetylcholine used were even higher than those that I had earlier observed to depress rather than stimulate sympathetic ganglion cells. So I attempted to reproduce their results under more normal conditions in our ganglion preparations, where activity could be initiated by naturally conducted nerve impulses. In 1955 I was joined by Jack Klingman, who patiently bolstered my weak biochemistry, and by William Leicht, whose skillful hands conducted most of the experiments. We found that activity, generated by stimulating the preganglionic nerve, indeed increased the ³²Pi labeling of PI, but we were never able to confirm Hokin’s finding of an effect on phosphatidic acid. The labeling of PI with ¹⁴C from [U-¹⁴C]glucose was also increased. There were no significant changes in labeling of phosphatidyl choline or phosphatidyl ethanolamine, or of any phospholipids in nerve trunks or in the nonsynaptic sensory ganglion of the vagus nerve. The effect on PI was prevented by blocking synaptic transmission with tubocurarine, and it could not be produced by sending impulses antidromically into the ganglion by stimulation of the postganglionic nerve. Therefore, we concluded that it was an effect of the synaptic transmitter acting on the ganglion cells and not simply a result of the discharge of impulses by these cells (Larrabee et al., 1963; Larrabee and Leicht, 1965).

I later extended the effect on PI to still more natural conditions by stimulating the preganglionic nerves of ganglia remaining in situ in anesthetized rats. I even showed that it was produced by normal sympathetic activity in the unanesthetized animal, where a control ganglion at rest was provided by preliminary cutting of the preganglionic nerve on one side (Larrabee, 1968). These were the first demonstrations of the effect on ³²Pi labeling of PI under physiological conditions. But nobody seemed to pay much attention, perhaps because the reductionist philosophy of the time was satisfied with findings under simplified but highly artificial circumstances. David Burt later showed that the PI effect was greatest in subcellular fractions containing synaptosomes and mitochondria (Burt and Larrabee, 1973). He also found that the labeling of PI with [³H]inositol was increased during activity even more than that with ³²Pi, and that there was a small but significant effect on labeling with [¹⁴C]glycerol, but none with [¹⁴C]acetate (Burt and Larrabee, 1976). Thus the increased turnover of the PI molecule during activity must involve most but possibly not all of its parts.

The Giant Axon of the Squid

Due to the interest in the giant axon of the squid that was generated by the ionic transfer experiments of Hodgkin and Huxley, F.J. Brinley and I investigated the labeling of lipids in this preparation. He incubated the axons with ³²Pi at the Physiology Department of the Medical School and brought them to me for analysis. In intact axons there was the expected labeling of phosphatidyl inositol, phosphatidyl ethanolamine, and phosphatidic acid. Most surprisingly, phosphatidyl choline, although apparently present in abundance, received no detectable ³²P label. Another finding, possible only with the giant axon, was that extruded axoplasm, when mixed with ³²Pi, labeled the same lipids as did the intact axon (Larrabee and Brinley, 1968).

The Higher Inositides

Godfrey White from J.N.Hawthorn’s laboratory in Birmingham, England, brought more biochemical knowledge, including reverse-phase paper chromatography for resolving the di- and tri-phosphatidyl inositides. Activity in the rat ganglia had no effect on ³²Pi labeling of either of these. We also examined the effects of two analogs of inositol, δ- and ‘γ-hexachlorocyclohexane. The latter is also known as “lindane,” a highly toxic insecticide. The δ-hexane blocked axonal conduction and the transynaptic response at similar low concentrations, without reducing the ³²Pi labeling of any of the inositides. On the other hand, the γ-hexane had a striking selective action on synaptic transmission at a concentration of 0.07 mM, without effect on axonal conduction or on incorporation of ³²Pi into inositides. The results on transmission suggest that synaptic blockage may be an important component of the toxicity of the latter insecticide, for which the LD₅₀ for rats is only 0.3 mmol/kg body weight (White and Larrabee, 1973).

Nerve Growth Factor and Its Antiserum

In 1965 Giovanni Toschi came to the lab from Rome, bearing a generous gift of nerve growth factor (NGF) from its discoverer, Rita Levi-Montalcini. He also taught us to dissect the lumbar sympathetic chains from chicken embryos. Unfortunately we obtained no publishable results during Giovanni’s relatively short stay, though his visit was educational for us and later led to many findings.

As our techniques with the nerve growth factor improved, Lester Partlow, for his doctoral dissertation, studied the effects the factor on sympathetic ganglia excised from chicken embryos. He demonstrated that the excessive growth of axons, which was caused by addition of the factor to the medium, was unaffected by profound inhibition of RNA synthesis by actinomycin-D or of protein synthesis by cycloheximide (Partlow and Larrabee, 1971). These findings dispelled a contemporary hypothesis that the growth effects were mediated by synthesis of a novel RNA and thence of a novel protein.

Partlow also found, in the absence of the inhibitors, that the rates of incorporation of labeled precursors into RNA and protein, which otherwise tended to decline 5-10 hours after excision, were better sustained if the nerve growth factor were added to the medium (Partlow and Larrabee, 1971). And Ted Brown, a talented undergraduate, found similar effects on ¹⁴CO₂ production from [1-¹⁴C]glucose (Larrabee, 1969, 1972). These findings suggested a supportive, rather than a stimulative, action of the growth factor.

Brown, under Partlow’s direction, also found that the growth of fibers induced by the growth factor around excised sympathetic ganglia was greatest at 14 days of embryonic age and that significant outgrowth could still be obtained until at least 19 days of age, whereas the growth response from dorsal root ganglia ceased abruptly after 15 days (Larrabee, 1972). He also found an axial gradient along the lumbar sympathetic chains in the development of the responsiveness, with the outgrowth becoming elicitable first in the more cephalad ganglia (unpublished).

David Halstead, another doctoral candidate, followed the time course of various depressant effects of an antiserum to the nerve growth factor in the superior cervical ganglia of young mice. This antiserum had been produced in a horse and was given to us by the Wellcome Research Laboratories, courtesy of D. Caird Edwards. With a background in electrical engineering, Halstead exhibited unusual ingenuity and skill in developing procedures, such as routinely recording transmission through ganglia from mice 3 days of age and younger with body weights of 1.5 to 3 g. The transynaptic response was the most rapidly affected of all the attributes measured, falling to 79% of its control height in ganglia excised 12 hours after an injection of antiserum at 7 to 10 days of age, and to less than 5% after 2 days. By the second day, glucose metabolism to CO₂ had fallen to about 20% of the control, incorporation of labeled precursors into RNA and protein were down to about 40%, and the dry weights of the ganglia were about 50% of the control. Thus the antiserum affected the ganglia in several ways, raising a question about what was the primary event in their degeneration (Halstead and Larrabee, 1972).

Semiretirement

My tenure at Hopkins expired in 1975 because I had reached the age of 65, and no more graduate students came my way. Perhaps they feared I would not last to the completion of their thesis research. But I continued in the laboratory for more than 20 additional years, publishing another 15 research papers. Smaller but very adequate space was generously provided by the Biophysics Department and I volunteered most of my time, recompensed only very modestly from my shrinking but continuing NIH grant.

Carbohydrate Metabolism in Sympathetic Ganglia of Chicken Embryos

In the course of the experiments with the nerve growth factor, I became impressed with the sympathetic chain of chicken embryos as an admirable preparation for certain kinds of research. The eggs are relatively inexpensive, they come with their own built-in food supply, and can be delivered by the supplier at any desired age of development. Thus the laboratory incubator can contain a fine collection for age studies or provide eggs of a given age on any day between deliveries. So I abandoned the rat ganglia in favor of the chicken embryo.

I set out to describe the progressive changes in carbohydrate metabolism that occur during development, as the embryologists had done for morphological events. I used the lumbar sympathetic chains of the chicken, which can be excised as early as 6 days after laying, the day on which they have completed migration into their final position. At 8 days, the earliest age that I studied extensively, the carbon from labeled glucose was mostly released as lactate, with very little appearing in CO₂, so energy production was mostly glycolytic. It seemed probable that this was related to the poor blood supply, which was just beginning to develop in the ganglia and is not completed until the 12th day. By the 12th day the production of labeled lactate had declined by 80% and the output of ¹⁴CO₂ from [1-¹⁴C]glucose had risen to a maximum. At this time the output from [6-¹⁴C]glucose was only 20% of that from [1-¹⁴C]glucose, indicating that much of the glucose was utilized via the pentose pathway.³ As development continued, the C-1 output declined progressively to the level of the C-6 output, indicating subsidence of metabolism via the pentose pathway. Thus glucose metabolism, like morphological development, passed through several stages: the first was characterized by glycolysis to lactate, the second, by pentose pathway activity, and finally a conventional adult pattern of oxidation arose, presumably restricted mostly to the Embden–Myerhof pathway and the tricarboxylic acid cycle (Larrabee, 1972).

Later I repeated these experiments in more detail (Larrabee, 1985), and compared the results with some on dorsal root ganglia (Larrabee, 1987b). I showed, among other things, that the developmental rise and fall of activity in the pentose pathway was paralleled by a surge in lipid synthesis. Thus there must be an intensified formation of these products at this stage of development, peaking at about 11 days of embryonic age and supported by the pentose path’s synthesis of NADPH, which is needed for chain elongation in the building of fatty acids (Larrabee, 1987a).

Evaluation of the Pentose Pathway

The foregoing experiments drew my attention to the pentose pathway, and I sought a way to determine how the metabolism of glucose was partitioned between this route and the more familiar Embden–Meyerhof glycolytic pathway. The then popular equations of Wood, Katz, and Landau (1963) were not applicable to our preparations because they depended on a frequently ignored assumption that the tissue was in an isotopic steady state, whereas our embryonic ganglia sometimes took as long as 15 hours for ¹⁴CO₂ output to rise to a steady value during exposure to [6-¹⁴C]glucose and it seemed undesirable to work with the tissue so long after excision. On the other hand, our preparations showed a great difference between the time courses of ¹⁴CO₂ production from [1-¹⁴C]glucose and [6-¹⁴C]glucose from the very beginning of incubation, and it occurred to me that this difference contained information that had not been available to other investigators. For example, when the output of ¹⁴CO₂ from [6-¹⁴C]glucose rose more slowly than that from [1-¹⁴C]glucose, it was evidence for activity in the pentose pathway, even if the final values were identical and investigators waiting for the steady state might conclude otherwise.

Accordingly, I laboriously derived equations describing the time course of ¹⁴CO₂ output from [1-¹⁴CJ]-, [2-¹⁴CJ]- and [6-¹⁴C]glucose by the cyclic systems represented by the pentose pathway and the citric acid cycle, in terms of the time constants of pools that delayed the output of ¹⁴CO₂ and certain other parameters. These expressions could be fitted to the data on ¹⁴CO₂ output by adjusting the parameters, using a computer-driven, nonlinear, least-squares program. Thus, at the age of 65, I was finally introduced to the world of computers by someone else’s graduate student, and trudged back and forth from my lab to the University’s central computer, lugging a 10-inch stack of key-punched cards that had to be reloaded into the computer each time.

I applied this procedure to data from sensory ganglia of chicken embryos, obtained very satisfactory fits to time courses of the ¹⁴CO₂ outputs from variously labeled glucoses, and published the equations in a lengthy and difficult paper (Larrabee, 1978). (I have not the least evidence that anybody except the referee ever read it, and I have some reason to believe that even he never finished it!) I soon found, however, that I had been incorrect in assuming that the pool of intermediates which delayed carbon-6 of glucose on its way to CO₂ was located somewhere in the pentose pathway: when I tried to identify this pool, the evidence indicated that no pool big enough existed in that path. Instead, paper chromatography of the ganglion tissue showed that the major differential incorporation of carbon-6 was into lipids, and in addition about half as much as this went into chromatographically immobile substances, possibly including proteins, lipoproteins, and nucleic acids (Larrabee, 1980).

Therefore, I adapted the time-course equations to a different model. In this model I abandoned the pool in the pentose path and assumed that the ganglia contained two different kinds of cells, one with all glucose entering the pentose system and the other completely lacking this pathway. This permitted an even better fit to the data and indicated that about 23% of the absorbed glucose entered the pentose pathway (Larrabee, 1980). Some support for the assumed difference between kinds of cells was later obtained, for the pentose path was less active in cultures containing only neuronal cells than in nonneuronal cultures (Larrabee, 1982). At least the new model showed that the time-course equations published in 1978 might have a usefulness beyond the particular faulty model for which they were originally developed.

Later I realized that rigorous upper and lower limits to the flux from glucose to the pentose pathway could be set from the rates of ¹⁴CO₂ output from [1-¹⁴C]glucose and [6-¹⁴C]glucose. Moreover, the range of uncertainty between these limits could be greatly narrowed by using time-course data, all without application of a specific model (Larrabee, 1989). The flux thus calculated for dorsal root ganglia in 10 µl of medium ranged from 12 to 36% of the glucose taken up, thus embracing the value of 23% that had been obtained in my 1980 paper with the more elaborate but assumption-laden equations. Moreover, the latter equations remained plausible, whereas they would have been invalidated if their result had fallen outside the new rigorously derived range.

I also published a critique of the classical Katz and Wood equations for evaluating pentose pathway activity (Wood et al., 1963), explicitly stating their implicit assumptions and rederiving their equations. By considering a tissue containing two kinds of cells, it was apparent that very misleading results could be obtained on nonhomogeneous tissues, even if each constituent obeyed all of Katz and Wood’s assumptions (Larrabee, 1990).

Fluxes through Extracellular Pools of Lactate and Alanine

In the course of experiments on lactate production from [¹⁴C]glucose, my attention was attracted to an unidentified radioactive peak on chromatograms of media recovered at the end of an experiment. Its magnitude was sometimes comparable to that of lactate, and I was unaware of the release of any such sizeable product from glucose other than lactate and CO₂. This was finally identified as alanine (Larrabee, 1984).

The outputs and uptakes of both lactate and alanine were measured by tracer methods as functions of their concentrations in the bathing solution. This revealed a marked increase of output of each to the medium as its concentration was raised. The reason for the increase was apparently that much of the released material was normally reabsorbed via an uptake system that was saturable, so that uptake of the added material interfered with reuptake of that which was produced by the cells. The situation was greatly clarified by computer modeling, assuming that uptake varied with the extracellular concentration according to familiar Michaelis-Menton kinetics for both alanine and lactate, and that their outputs were affected in specific ways that were somewhat different from one another. Calculations for the model were made by numerical integration over the time course of incubation, thus allowing for progressive changes in concentrations and for reuptake of some of the released material. To enable these calculations, exchange rates between the extracellular space within the ganglion and the surrounding medium were shown to be directly proportional to the concentration differences, and the transfer coefficients for this exchange, as well as the volume of the extracellular space, were measured by wash-out experiments.

First, the model was used to predict the exchanges between the whole ganglion and the surrounding medium, and the best values for the various constants in the cellular exchange equations were found by least-squares fitting of the predictions to the observations. Some ingenuity was involved in this, because it was necessary to devise a way of fitting both the uptake and output data for several concentrations of a given substrate in a single computer run, and this involved telling the computer a little white lie due to the structure of the available program.

Once the best values of the constants had been chosen, it was possible to calculate the exchanges between the cells and the extracellular fluid, which cannot be measured directly, and thus determine the fluxes of lactate and alanine through their extracellular pools. It was estimated that as much as 45% of the glucose taken up was released to the extracellular fluid as lactate and alanine, but that over 65% of these released materials were reabsorbed before they could diffuse out of the tissue into the bathing solution (Larrabee, 1992). Thus the extracellular pools can be important routes for glucose metabolism and should be included as intermediates of carbohydrate metabolism. Whether the released materials were reabsorbed by the same cells that produced them or by different cells is unknown for our ganglion preparations. However, evidence for partial digestion of glucose by one type of cell for subsequent utilization by other types has been reported for retina (Poitry-Yamate et al., 1995; Tsacopoulos and Magistretti, 1996).

Lactate Metabolism in Relation to Glucose Metabolism

My final investigations in this area asked how the source of CO₂, and hence of energy production, was partitioned between glucose and lactate when both were present. To this end, the two substrates were provided in various combinations of concentrations, with first one and then the other uniformly labeled with ¹⁴C. Addition of each substrate was found to reduce the output of CO₂ from the other, but the sum of the outputs nevertheless always exceeded that from either alone, so energy production was always increased by combining the two (Larrabee, 1995).

Moreover, in a sense, lactate was a substrate preferred over glucose. For example, when both were present in the medium at a concentration of 5 mM, about 5 times as much CO₂ came from lactate as from glucose, and an excess from lactate persisted until its concentration was reduced below 2 mM (Larrabee, 1996).

By computer modeling, many details of the concentrations and flux rates of both exogenous and endogenous lactate were calculated for the sympathetic ganglia under study. This was done using the previously published equations for cellular lactate uptake and release as functions of the extracellular concentration and for the exchange rate between the extracellular fluid and the bathing solution.

Finally, a model for brain was constructed by replacing the function that had been used for transfer between the extracellular fluid and the bathing medium in the ganglion calculations by the transport properties of the blood-brain barrier of the adult rat (Cremer et al., 1979). This model predicted rates for consumption of blood lactate that agreed well with those reported by other investigators for dog brains in situ in the presence of a wide range of lactate concentrations, thus encouraging further calculations. Accordingly, it was estimated that, with a normal level of blood glucose (5 mM) and a typical resting value of blood lactate (1 mM), 6% of the CO₂ produced by the brain would be derived from blood lactate. If the lactate were raised to 5 mM, it would supply about 20% of the CO₂, and at 20 mM, a level commonly reached during intense exercise, it would supply more than half of the CO₂, about 60% (Larrabee, 1996), even in the presence of 5 mM glucose. This suggests that lactate may be a significant fuel for brain, especially during muscular activity, and deserves more experimental investigation at elevated concentrations than it has yet received.

In closing, it should be emphasized that these questions about use of lactate by the brain cannot be settled by chemical measurements of lactate in the arterial and venous blood of the brain under normal resting conditions. This is because, under these conditions, the lactate concentrations may then be about 1 mM in both blood and brain, so that outflux of lactate formed in the brain may equal the influx from the blood and thus conceal the metabolism of blood lactate.

Epilogue

This account was written with the aid of my new personal computer during the spring of 1997 in my comfortable study in a congenial retirement community located in a beautiful valley outside of Baltimore. Barbara and I moved there three years earlier as her health was beginning to fail, before she died in 1996. I have made many friends in the community. Our son, David, lives nearby, and we enjoy a meal together weekly. My older son, Benjamin, born to my first wife, Sylvia, is also nearby in southern Pennsylvania.

In retrospect, I have had a happy and relatively easy life. I was well reared by my parents, sustained by Det Bronk’s paternalism early in my career, and subsequently supported abundantly by a single research grant that enabled all the experiments I wanted to do. And, for more than 20 years after my tenure expired, I was generously provided with lab and office space by my University and its Biophysics Department.

I feel fortunate to have been invited to the 2nd International Neurochemical Symposium in Aarhus, Denmark, in 1958. This opened my provincial New England eyes to other parts of the world and led to numerous vacations in Europe, especially in the beautiful mountains of Switzerland. Later, Barbara and I also enjoyed many other trips to scientific meetings in far away places, including Brussels, Budapest, Milan, Strasbourg, Vienna, Hawaii, Japan, and Venezuela.

In writing this account I was interested to see the flow of research from project to project, as questions or opportunities that were revealed in one project led to the next. The flow was sort of an evolutionary process, punctuated by occasional events such as the development of the oxygen electrode by Philip Davies, suggestions received at a chance dinner with Albert Sabin, and the gift of nerve growth factor by Rita Levi-Montalcini. I enjoyed it all, never seemed to lack an exciting horizon, and find little that I would like to change.

Selected Bibliography

Bronk DW, Pitts RF, Larrabee MG. Role of hypothalamus in cardiovascular regulation. Res Publ Assn Res Nerv Ment Dis 1940;20:323–340.

Bronk DW, Larrabee MG, Gaylor JB. The effects of circulatory arrest and oxygen lack on synaptic transmission in a sympathetic ganglion. J Cell Comp Physiol 1948;31:193–212.

Burt DR, Larrabee MG. Subcellular site of the phosphatidylinosital effect. Distribution on density gradients of labelled lipids from resting and active sympathetic ganglia of the rat. J Neurochem 1973;21:255–272.

Burt DR, Larrabee MG. Phosphatidylinositol and other lipids in a mammalian sympathetic ganglion: Effects of neuronal activity on incorporation of labelled inositol, phosphate, glycerol and acetate. J Neurochem 1976;27:753–763.

Dempsher J, Larrabee MG, Bang FB, Bodian D. Physiological changes in sympathetic ganglia infected with pseudorabies virus. Am J Physiol 1955;182:203–216.

Dolivo M, Larrabee MG. Metabolism of glucose and oxygen in a mammalian sympathetic ganglion at reduced temperature and varied pH. J Neurochem 1958;3:72–88.

Edwards C, Larrabee MG. Effects of anesthetics on metabolism and on transmission in sympathetic ganglia of rats: Measurement of glucose in microgram quantities using glucose oxidase. J Physiol 1955;130:456–466.

Halstead DC, Larrabee MG. Early effects of antiserum to the nerve growth factor on metabolism and transmission in superior cervical ganglia of mice. In: G Steiner, E Schönbaum, eds. Immunosympathectomy, Chapter XIV. Amsterdam: Elsevier, 1972;221–236.

Hodes R, Larrabee MG, German W. The human electromyogram in response to nerve stimulation and the conduction velocity of motor axons. Studies on normal and on injured peripheral nerves. Arch Neural Psych 1948;60:340–365.

Horowicz P, Larrabee MG. Glucose consumption and lactate production in a mammalian sympathetic ganglion at rest and in activity. J Neurochem 1958;2: 102–118.

Horowicz P, Larrabee MG. Oxidation of glucose in a mammalian sympathetic ganglion at rest and in activity. J Neurochem 1962a;9:1–21.

Horowicz P, Larrabee MG. Metabolic partitioning of carbon from glucose by a mammalian sympathetic ganglion. J Neurochem 1962b;9:407–420.

Knowlton GC, Larrabee MG. A unitary analysis of pulmonary volume receptors. Am J Physiol 1946;147:100–114.

Larrabee MG, Bronk DW. Long-lasting effects of activity on ganglionic transmission. Am J Physiol 1938;123:126. [Abstract]

Larrabee MG, Knowlton GC. Excitation and inhibition of phrenic motoneurons by inflation of the lungs. Am J Physiol 1946;147:90–99.

Larrabee MG, Bronk DW. Prolonged facilitation of synaptic excitation in sympathetic ganglia. J Neurophysiol 1947;10:139–154.

Larrabee MG, Hodes R. Cyclic changes in the respiratory centers, revealed by the effects of afferent impulses. Am J Physiol 1948;155:147–164.

Larrabee MG, Bronk DW. Metabolic requirements of sympathetic neurons. Cold Spring Harbor Symp Quant Biol 1952;17:245–266.

Larrabee MG, Holaday DA. Depression of transmission through sympathetic ganglia during general anesthesia. J Pharmacol Exp Ther 1952;105:400–408.

Larrabee MG, Posternak JM. Selective action of anesthetics on synapses and axons in mammalian sympathetic ganglia. J Neurophysiol 1952;15:9l–114.

Larrabee MG, Ramos JG, Bulbring E. Effects of anesthetics on oxygen consumption and on synaptic transmission in sympathetic ganglia. J Cell Comp Physiol 1952;40:461–494.

Larrabee MG, Horowicz P, Stekiel W, Dolivo M. Metabolism in relation to function in mammalian sympathetic ganglia. In: D Richter, ed. The metabolism of the nervous system, Proceedings of the second international neurochemical symposium. London: Pergamon Press, 1957;208–220.

Larrabee MG. Oxygen consumption of excised sympathetic ganglia at rest and in activity. J Neurochem 1958;2:81–101.

Larrabee MG, and Klingman JD. Metabolism of glucose and oxygen in mammalian sympathetic ganglia at rest and in action. In: KAC Elliott, IH Page, JH Quastel, eds. Neurochemistry, 2nd edition. Springfield: Thomas, IL, 1962;150–176.

Larrabee MG, Klingman JD, Leicht WS. Effects of temperature, calcium and activity on phospholipid metabolism in a sympathetic ganglion. J Neurochem 1963; 10:549–570.

Larrabee MG, Leicht WS. Metabolism of phosphatidyl inositol and other lipids in active neurones of sympathetic ganglia and other peripheral nervous tissues. The site of the inositide effect. J Neurochem 1965;12:1–13.

Larrabee MG. Transynaptic stimulation of phosphatidylinositol metabolism in sympathetic neurons in situ. J Neurochem 1968;15:803–808.

Larrabee MG, Brinley FJ, Jr. Incorporation of labelled phosphate into phospholipids in squid giant axons. J Neurochem 1968;15:533–545.

Larrabee MG. Metabolic effects of nerve impulses and nerve-growth factor in sympathetic ganglia. Prog Brain Res 1969;31:95–110.

Larrabee MG.Metabolism during development in sympathetic ganglia of chickens: Effects of age, nerve growth factor and metabolic inhibitors. In: E Zaimis, J Night, eds. Nerve growth factor and its antiserum. London: The Athlone Press, 1972.

Larrabee MG. A new mathematical approach to the metabolism of[¹⁴C]glucose, with applications to sensory ganglia of chicken embryos. J Neurochem 1978;31: 461–491. [Typographical errata: J Neurochem 1979;32:283. Also note that equations for the citric acid cycle in Table 6 can be improved by substituting (l-R1R2/2)⁻¹-(1+R1R2/2) for the sum from n = 2 to infinity of(R1R2/2)n.)

Larrabee MG. Metabolic disposition of glucose carbon by sensory ganglia of 15-day-old chicken embryos, with new dynamic models of carbohydrate metabolism. J Neurochem 1980;35:210–231.

Larrabee MG. [¹⁴C]Glucose metabolism in sympathetic ganglia of chicken embryos and in primary cultures of neurons and of other cells from these ganglia. J Neurochem 1982;38:215–232.

Larrabee MG. Lactate uptake and release in the presence of glucose by sympathetic ganglia of chicken embryos and by neuronal and non-neuronal cultures prepared from these ganglia. J Neurochem 1983;40:1237–1250.

Larrabee MG. Alanine uptake and release by sympathetic ganglia of chicken embryos. J Neurochem 1984;43:816–829.

Larrabee MG. Ontogeny of glucose metabolism in sympathetic ganglia of chickens. Changes in carbon fluxes to CO₂, lactate and tissue constituents from 8 to 19 days of embryonic age. J Neurochem 1985;45:1193–1200.

Larrabee MG. Ontogeny of glucose metabolism in sympathetic ganglia of chickens. Concurrence of maximum rates in the hexosemonophosphate shunt and in synthesis oflipids but not of ribonucleic acid. J Neurochem 1987a;48:417–424.

Larrabee MG. Ontogeny of glucose and lipid metabolism in dorsal root ganglia of chickens. Similarities and contrasts with sympathetic ganglia. J Neurochem 1987b;49:393–398.

Larrabee MG. The pentose cycle (hexose monophosphate shunt). Rigorous evaluation of limits to the flux from glucose using ¹⁴CO₂ data, with applications to peripheral ganglia of chicken embryos. J Biol Chem 1989;264:15875–15879.

Larrabee MG. Evaluation of the pentose phosphate pathway from ¹⁴CO₂ data. Fallibility of a classic equation when applied to non-homogeneous tissues. Biochem J 1990;272:127–132.

Larrabee MG. Extracellular intermediates of glucose metabolism: Fluxes of endogenous lactate and alanine through extracellular pools in embryonic sympathetic ganglia. J Neurochem 1992;59:1041–1052.

Larrabee MG. Lactate metabolism and its effects on glucose metabolism in an excised neural tissue. J Neurochem 1995;64:1734–1741.

Larrabee MG. Partitioning of CO₂ production between glucose and lactate in excised sympathetic ganglia, with implications for brain. J Neurochem 1996;67: 1726–1734.

Lucké B, Larrabee MG, Hartline HK. Studies on osmotic equilibrium and on the kinetics of osmosis in living cells by a diffraction method. J Gen Physiol 1935; 19:1–17.

Partlow LM, Larrabee MG. Effects of a nerve-growth factor, embryo age, and metabolic inhibitors on growth of fibres and on synthesis of ribonucleic acid and protein in embryonic sympathetic ganglia. J Neurochem 1971;18:2101–2118.

Pitts RF, Larrabee MG, Bronk DW. An analysis of hypothalamic cardiovascular control. Am J Physiol 1941;134:359–383.

Posternak JM, Larrabee MG. Depression of synaptic transmission through sympathetic ganglia following temporary occlusion of the aorta: An effect of endogenous adrenalin. Bull Johns Hopkins Hosp 1950;87:144–155.

White GL, Larrabee MG. Phophoinositides and other phospholipids in sympathetic ganglia and nerve trunks of rats. Effects of neuronal activity and inositol analogs (delta and gamma-hexachlorocyclohexane (lindane) on [³²P]-labelling, synaptic transmission and axonal conduction. J Neurochem 1973;20:783–798.

Additional Publications

Barinaga M. What makes brain neurons run? Science 1997;276:196–198.

Brink F, Jr. Detlev Wulf Bronk. In: Biographical memoirs. Washington, DC: The National Academy of Sciences of the United States, 1979;50:2–87.

Brinley FJ, Jr. Potassium accumulation and transport in the rat sympathetic ganglion. J Neurophysiol 1967;30:1531–1560.

Carlson FD, Brink F, Bronk DW. A continuous flow respirometer utilizing the oxygen cathode. Rev Sci Inst 1950;21:923–932.

Cremer JE, Cunningham VJ, Pardridge WM, Braun LD, Oldendorf WH. Kinetics of blood-brain barrier transport of pyruvate, lactate and glucose in suckling, weaning and adult rats. J Neurochem 1979;33:439–445.

Davies PW, Brink F. Microelectrodes for measuring local oxygen tension in animal tissues. Rev Sci Inst 1942;13:524–533.

Davies PW. The oxygen cathode. In: WL Nastuk, ed. Physical techniques in biological research. New York: Academic Press, 1962;137–179.

Hartline HK, Graham CH. Nerve impulses from single receptors in the eye. J Cell Comp Physiol 1932;1:277–295.

Hokin MR, Hokin LE, Shelp WD. Effects of acetyl choline on turnover of phosphatidic acid and phosphoinositide in sympathetic ganglia and in various parts of the nervous system in vitro. J Gen Physiol 1960;44:217–226.

Katz J, Wood HG. The use of ¹⁴CO₂ yields from glucose-1- and -6-¹⁴C for the evaluation of the pathways of glucose metabolism. J Biol Chem 1963;238:517–523.

Lloyd DPC. Post-tetanic potentiation of response in monosynaptic reflex pathways of the spinal cord. J Gen Physiol 1949;33:147.

Poitry-Yamate CL, Poitry S, Tsacopoulos M. Lactate released by Muller glial cells is metabolized by photoreceptors from mammalian retina. J Neurosci 1995;15: 5179–5191.

Rémand A, Davies PW, Bronk DW. Influence of the vascular bed on the pattern of oxygen tension in the cerebral cortex. Fed Proc 1946;5:86.

Tsacopoulos M, Magistretti PJ. Metabolic coupling between glia and neurons. J Neurosci 1996;16:877–885.

Wood HG, Katz J, Landau BR. Estimation of pathways of glucose metabolism. Biochem Zeit 1963;338:809–847.

¹An incident with a ridiculous aftermath occurred when Knowlton purchased a toy printing press at Macy’s department store in order to run off form cards to help sort our data from 99 single afferent fibers. Several years later his promotion in the Air Force was delayed when a security check revealed that he had owned a printing press while living in New York City in 1941!

²Edith Bulbring somewhat facetiously explained that there are, in ascending order, physiological concentrations, pharmacological concentrations, biochemical concentrations, and biophysical concentrations. In other words, each discipline except the first tends to raise the concentration until something interesting happens, with little concern about the relevant level in the intact organism. I have always tried to avoid that pitfall.

³For those unfamiliar with the pentose pathway, it may be characterized for present purposes as an alternative route for glucose metabolism that parallels the first few steps of the Embden–Meyerhoff glycolytic path. It is needed to form ribose for RNA synthesis and NADPH for fatty acid synthesis. At entry to this route, all carbon-I of glucose is released to CO₂. It is frequently called the “pentose cycle” because some of its products are recycled into its entry.

Jerome Lettvin

BORN:

Chicago, Illinois

February 23, 1920

EDUCATION:

University of Illinois, B.S. (1943)

University of Illinois, M.D. (1943)

APPOINTMENTS:

University of Rochester (1947)

Manteno State Hospital, Illinois (1948)

Massachusetts Institute of Technology (1951)

Rutgers University (1988)

Jerome Lettvin was trained in psychiatry and then carried out neurophysiological studies in the spinal cord, made the first demonstration of feature detectors in the visual system, and studied information processing in the terminal branches of single axons. He is remembered for his original and charismatic classroom teaching, especially on the subject of perception.

Jerome Lettvin

Beginnings

My parents immigrated, each from the Ukraine, in the decade before World War I. They met in Chicago. Mother was a piano teacher, father was a Kropotkin-type anarchist turned lawyer. In 1915, father, who had come to America only fours years earlier, graduated Tuley High School in Chicago, winning the prize for oratory. He then embarked on social reform, speaking at street corners and in the hobo’s park (next to the Newberry Library), supporting labor unionization and a variety of other causes. Mother, a handsome woman, was much sought after by dentists, doctors, and other such elevated types. But she saw in father the fire she wanted to impart to her children. So she arranged that he be given tickets to concerts, plays, and other events, and always by accident happened to be seated next to him. In a short while, of course, he fell in love, but when he proposed, she made it clear that she would accept him only if he went to law school. So he did, supporting himself by selling papers and doing odd jobs. Immediately on graduating he collapsed, but she nursed him back to health, married him, and I was born February 23, 1920. Thereafter there were two more sons and a daughter.

My brothers and sister agree with me that we never got to know father at all well. Father at home was gently taciturn and unassuming. Mother ruled the house and had a driving ambition for all of us. I played my first piano concert at the age of eight then quit. After all, my sister and youngest brothers were already prodigies at the piano. They appeared a few years later individually and together as soloists with the Chicago Symphony Orchestra. I stubbornly wanted to write poetry, so mother finally drove me that way.

We lived in an enchanted ghetto, Humboldt Park. Rosalind Tureck was next door. Saul Bellow, Isaac Rosenfeld, Sam Wanamaker, and Sidney Harris were all at Tuley High School with me. There are a great many less well-known literati, musicians, artists, and actors who attended that school from 1932 to 1936. The surroundings were materially poor but culturally rich; it was impossible not to resonate.

I went from high school to Lewis Institute, a working-man’s college ($15 a course), now part of Illinois Institute of Technology. It closed because stones began falling from the parapets, endangering the already run-down Madison Avenue environment. I spent my third year of college (1938) at the University of Chicago because my mother had decided I was to be a doctor. Her decision was irrevocable.

Friends

My education began at the University of Chicago where I met my two lifelong friends: Walter Pitts (the mathematician), and Hyman Minsky (the economist). Both are now dead. Indeed, I owe whatever learning I have to Walter. I was 18 at the time, and he was 15. It was my last year as pre-med. My mother, who had a whim of iron, had laid out my career. Walter had run away from home in Detroit the previous year and become a nonstudent at the University of Chicago. The school was well aware of him and turned a blind eye to his presence in classes. Before we met, he had wandered into the office of Carnap, the logician, with a marked and annotated copy of Carnap’s recently published book on logic. Without introducing himself he went into a careful analysis of weaknesses and even outright errors in the text, and after a long colloquy, he left without ever giving his name. Carnap spent half a year searching for “that newsboy who understood logic,” and when he found Walter, arranged to get him a job (for Walter was penniless). In any case, nobody threw him out of the graduate school classes he attended.

He was an autodidact who had taught himself Latin, Greek, and Sanskrit along with German and French. He began his interest in logic and mathematics at the age of 12 when some bullies chased him into the Detroit public library. He hid out in a section where Russell and Whitehead’s Principia Mathematica was shelved. He spent the next two weeks reading it, and sent a letter to Russell about some questions raised by the first volume. Russell replied affably in the fashion of addressing a fellow.

I really don’t remember how we met, but only that, for some reason, we became fast friends. I knew no science and less mathematics but was much taken up with poetry; this was our initial common bond. Going to medical school dismayed me for I wanted to be a writer, but my mother’s hold on me was unyielding. During the year at University of Chicago, Walter, knowing my innocence of formal reasoning and philosophy, proceeded gently, ever so gently, to give me some notion of the underlying ideas. It is very hard to explain what is meant by the delusion of a glimmering of what you don’t understand, but somehow that is what he evoked in me, and very skillfully indeed. However, much of our time was spent in experimenting with literary forms. We collaborated in trying to write a play.

There was a wonderfully comely young woman there at the time, Josephine, now a psychologist, to whose room Walter and I generally gravitated. She was warm, witty, and knowledgeable, and visiting her was like attending a salon of the sort we had only read about in accounts of past centuries. It goes without saying that Walter and I fell in love with her, yet always from a respectful and admiring distance.

Hy Minsky was the leader of the young socialists on campus. He and Walter and I would get together every few weeks to discuss politics. I remember how horrified he was when he heard that I was ghost-writing pamphlets for a member of the YCL, the Young Communist League. I pleaded that it gave me a certain kind of practice in putting forth vehemently what I don’t believe, but he and Walter persuaded me to stop.

The only department at University of Chicago that Walter called home was Rashevsky’s group in mathematical biophysics. I had another friend there, Bob Williamson, and was always welcome for coffee from the large, ever-hot urn. Sitting through seminar after seminar, I understood little of any lecture until Walter explained it to me later. Rashevsky tolerated me as a well-meaning visitor.

Medical School

In the fall of 1939 I entered the University of Illinois School of Medicine. The requirements for entrance were nominal as compared to today. The elementary premed courses in physics, chemistry, and mathematics could be easily passed simply by knowing the rules but without much understanding. Everything to be learned in medical school then was entirely empirical; there was little explanation of why things were as they were and how they worked or functioned. The studies were arduous but not difficult—all that was required was a good memory.

As far back as I recall I was always an overweight slob, disheveled and careless of appearance. After I entered the school I was “rushed” for the Jewish medical fraternity, and a week later was the only student ever depledged, to my relief. My father was an anarchist and I inherited his fear of organized in-groups.

The one faculty member I followed was Gerhardt von Bonin, the neuroanatomist. He was the only one to whom I showed my poetry. Liking it, he tried to persuade me that poetry was more interesting and challenging than medicine, and that despite my parents I should drop out and follow the higher calling. At our final practical examination at the end of the course, he came up to our table, on which lay the cadaver that my partner and I had dissected. Looking fixedly at me he said, “I will pick up an organ. If you name it you will pass and go on to be a leech. If you fail to name it you will fail and become a poet.” Without looking aside he reached into the lower abdomen with forceps and held up something. I was torn, but finally muttered “the cerebellum,” leaving the choice to him. He dropped the tissue back without looking at it, and said with contempt. ‘‘You named it, you pass. And god have mercy on your soul.” This anecdote may sound apocryphal, but Tom Kemper, the eminent neuropathologist, had much the same experience with Gerhardt.

In my third year, Warren McCulloch came to the school as Professor of Psychiatry. His function was to set up a laboratory of neurophysiology in the basement of the Illinois Neuropsychiatric Institute. Gerhardt and Percival Bailey knew him well and were looking forward to collaboration. Gerhardt took me along to meet Warren. When I was in high school, I had read Buckle’s history of the Scotch mind in the 17th century. It gave me nightmares for weeks afterward. Warren would be the first Scotchman I ever knew and, truly, I had a frisson going to see him. This was not lessened when I met him. He sported no beard then, but certainly had the most piercing eyes I ever encountered. However, in very little time, he, acting most friendly, dispelled my nervousness.

During the first two years of medical school, Walter and I met often and far into the night. Walter would visit a medical class, I would take time off to go to one of Rashevsky’s seminars. I brought Walter to visit Warren. Whoever has read Warren’s essays knows his abiding interest in philosophy. There was no question at all but what Walter instantly became part of Warren’s coterie.

Adoption by the McCullochs

Walter was impoverished, as I said earlier. I was increasingly chafing at my mother. I loved her, but home had become intolerable. She had taken a strong dislike to Walter and to Bob Williamson because, as friends, they might divert me away from the goal she envisioned for me, a career as an eminent doctor, impeccably dressed, who in courtly manner would give wonderful speeches while accepting award after award for his skill. Warren and his admirable wife, Rook, adopted Walter and me as family and we went to live at their home.

It was there, late in that year (1942), that Warren and Walter conceived and wrote their famous paper, “On the Logical Calculus Immanent in Nervous Activity,” and its sequel, “How We Perceive Universals.” These papers are at the root of what later became AI, artificial intelligence. They were published in Rashevsky’s Bulletin of Mathematical Biophysics. It is hard to describe the ferment in those long evenings, but for the first time I began to perceive what was at issue in the study of the brain.

Walter stayed on but I moved a few months later in 1942. Residents and nurses had been leaving for the army and the Illinois Neuropsychiatric Institute, a research hospital, became understaffed. I was in my last year of medical school and already strongly driven to neurology, having devoured all the books on the subject in the medical library. When I volunteered to Francis Gerty, the head of psychiatry, as a fill-in for nurse, intern, or resident as needed on a 24-hour call, he quickly accepted and gave me a resident’s room so as to have me instantly accessible. I was already familiar with psychiatry from my reading and had impressed the rest of his staff when I attended ward rounds and conferences on patients.

Low Key Vengeance

One virtue of writing an autobiography is that you can do your own deconstruction like a Tinguely sculpture. So I will dispose of one canard promptly. I am not now nor have ever been a true scientist. My credentials for incompetence are unflawed, and testimony of colleagues will bear me out. Yet the first paper I ever signed as co-author was with Walter, “A Mathematical Theory of the Affective Psychoses, Part I.” It was meant as a joke, but now, as I read it again, I find it even more well-done than I remember and would bet it could be passed by some referees today. The spirit behind the paper was simply revenge.

I was working on the wards fairly steadily and Walter would come over often enough to keep me company. He would stay over in my room because Warren’s house was in a suburb and public transport was awful at night. Next door to my resident’s room lived a Hungarian fellow aspiring to certification. This schmuck complained to Gerty that he suspected Walter and me of being homosexuals. Gerty, who well knew otherwise from the nursing staff, called me in to warn me of the fellow’s charges. Walter was as incensed as I was at the imputation. We plotted revenge. It is hard to explain our processes of thought. Both of us felt somewhat like literary characters out of some imaginary novel that Edmund Wilson might admire. The graceless Hungarian was a poseur. Standing with one foot advanced, head bowed, hand on chin, he would nod understanding at well-timed intervals. This characteristic allowed him to pass muster wordlessly not only with patients but with colleagues. The greatest revenge would be to stimulate him to that pose by a lecture which he couldn’t understand while at the same time he would know that we knew he didn’t understand. The thinking was convoluted, but literary. It was more satisfying than outright battery to shame someone publicly while he alone would know he was being shamed. After all, we were young and loved complexity for its own sake.

So the next evening we sat over a bottle of potent wine and plotted. Our target’s preferred interest was in depression. Well and good. But how to use the notion? At that time an odd discipline was emerging that even I could smell as contrived, topological psychology. Walter had a lifelong aversion to psychiatry. But I laid out what were the current doctrines and suggested we reduce them to diagrams so unfamiliar as to carry instant conviction. Walter was most interested in Leibniz, whose dictum on logical machines was the root of the paper with Warren. Half drunk, we cooked up a broth, he processing the formal expressions, I providing the ideas to be so expressed. We wrote the paper that night, using Leibniz’s words—“affection” for being acted on, and “conation” for striving to act.

Next day we showed it to Warren, who was amused but interested. We did not tell him our motives. He advised that we show it to Gerty, which we did. Gerty, who wanted some rapport between psychiatry and science, glanced at it and proposed a public seminar. That is what we aimed at. Walter coached me on how to present the mathematical part which I didn’t understand (but no one would ask about) and I coached him in the current catch-words and concepts in psychiatry with cases in point. When the day came we walked into a surprisingly crowded lecture room. Rashevsky was there; so also were Franz Alexander, the head of the Psychoanalytic Institute, and several other dignitaries. In the audience and standing in a side aisle as if to be ready for a medical emergency was our target. Undaunted we went through our routine, expecting at any moment an embarrassing question from Rashevsky’s group or Alexander’s circle. But nothing happened except general acclaim. And there was our victim in the exact pose we wanted. Our triumph was complete.

But it backfired. Rashevsky wanted to publish the paper directly in his journal. It is insulting to tell such a figure that he fell for a hoax. Later Alexander invited both of us to lunch and proposed (I swear this is true) that we be hired to put psychoanalysis on a firm theoretical basis. We demurred on obvious grounds. I was already in the Army and Walter had a difficult job to finish. A decade later we were further embarrassed when offered a grant to write Part II This is the whole story and I trust to have saved my reputation as a nonscientist.

Internship

While working at the INI and finishing medical school I wrote an essay on the physiological explanation for the Argyll–Robertson pupil. It differed considerably from that advanced by Merritt and Moore, and was carefully argued. I submitted it along with my application to the Harvard Nerve Service at Boston City Hospital. It persuaded Merritt to accept me into the service as an intern. Our class graduated 3 months early because of the war.

Denny-Brown had just taken over Harvard Nerve Service when I arrived. Norm Geschwind and I have always claimed not only that Denny had a well-developed sense of humor, something our colleagues think preposterous, but also that he was the best teacher of neurology around. Going on rounds with him became a game. He would often make outrageous or wrong-headed diagnoses, forcing the residents and interns to argue with him on physiological and anatomical grounds. We learned much more from debating those diagnoses than from simply filing and classifying them.

Denny was a physiologist, trained by Sherrington. One of his masterpieces, the work on the Brown–Sequard syndrome, is a cautionary essay on spinal cord physiology even today, especially today.

For some reason he allowed me to clown. One night I taught a wall of patients in the women’s ward to practice the positive Babinski reflex in the right foot only. The next day some visiting dignitaries in neurology were to be shown around. It was only at the third successive right positive Babinski during rounds that Denny turned and glared at me. The reflex did not figure in the rest of the rounds, but Denny never took me to task for it nor mentioned it thereafter.

During this period a cointern in medicine, Raisbeck, persuaded me to go with him on a visit to his uncle at MIT, Norbert Wiener. Wiener had just lost his valued postdoctoral fellow to a fatal ski accident. I described Walter to Wiener in glowing terms that he disbelieved. So Warren financed a ticket for Walter on the train to Boston. Walter and I walked in on Wiener who after a gruff”hello” said to Walter, “Let me show you my proof of the ergodic theorem.” They went next door to the blackboards, and by the time the second board was covered, after frequent acute questions and comments by Walter, it was clear that he was in. Walter moved to Boston. Many years later I found a soothing letter from Denny to my father who worried about the dread influence of Walter’s diverting me to science instead of medicine, and asked Denny to dissuade me from such fell interests.

I went off to the army in January 1944 after serving a 9-month internship which was truncated because of the war. But before going overseas I spent three months training at Bellevue neuropsychiatry in New York. Walter had been coopted by the Kellex Corporation, a branch of the A-bomb project in the Woolworth building. So we took an apartment together. Wiener visited us several times.

Kellex was losing young men to the draft, for there was no provision for sparing scientists in the law. I later accused Sam Wortis, the head ofneuropsychiatry at Bellevue, of engineering the appointment of A.A. Brill as chief psychiatrist at the 42nd Street station. He never affirmed it but refused to deny it. Brill not only had issued a poor translation of Freud into English but held to an unshakable belief that dealing in symbols was the mark of schizophrenia. Hence all users of mathematics were, by definition, nuts. In full seriousness he labeled every drafted physicist and mathematician prepsychotic. Just such uncelebrated accidents save important effort in critical times. Walter was enraged by the diagnosis as were his colleagues. Some of them used to meet occasionally in our apartment because they were not permitted by General Groves to talk to each other at work. If the army had known this I would never have been allowed to go overseas.

After I returned from my work as chief of psychiatry in the 237th General Hospital at France, Denny was very cold to me. It was hard to persuade him until much later that I had not turned into a psychiatrist but had been dragooned into shrinkship by the army. Note that at the time one could move into psychiatry from any field of medicine, but not back. Nobody trusted a psychiatrist to do real medicine. Nevertheless, I had been offered good openings but I really wanted to do research on the nervous system.

Educational Interlude

Then a new option was offered. Walter and Wiener felt it was time I learned some science. So Wiener arranged for me to be admitted as a special student on the condition that I would take an overload of courses for a year. At the same time, the Veteran’s Administration gave me a paying post as an outpatient psychiatrist in downtown Boston. I accepted and Hy Minsky (then at Harvard), Walter, Oliver Selfridge, and I took a single large room on Beacon Street. There wasn’t much money between us; mostly it was my salary from the VA. We kept it in $20 bills between the leaves of Spengler’s Decline of the West as the last place any thief would look.

That year gave me a freshman introduction to science. I remember most vividly Dirk Struik, who is still alive at almost 103, for his engaging course on differential geometry. But before the end of the academic year I fled to Chicago. Walter had lost a manuscript that Wiener was working on and I decided to take the blow. It was about a month before the end of the term. I was exhausted from the load of five courses along with doing my stint as clinician, and it was obvious to me that I would never be a true scientist. So no sacrifice was involved.

In Chicago, Warren gave me the run of the laboratory and I cadged from my parents for a few months by staying at home. Then Warren suggested that if I wanted to go into research I should apply for a post as physiologist and see what happened. After all, as an M.D. I had credentials. During this time I had been learning methods of physiology at Warren’s lab so I could proclaim myself a physiologist. The department of psychology at the University of Rochester hired me to work at inducing motion sickness as an abortifacient for cats. This was because one of the popular methods for inducing abortion at the time was to take a sequence of high rides at amusement parks or a boat cruise in bad weather. It was a silly project, foolishly set up, but there were some good physiologists in other departments who were doing single unit recordings in the auditory nerve and studies on other parts of the nervous system. I learned electronics from John Kanwisher and something about axonology from Bob Taylor, and set up to study vestibular fibers in carp and cat.

Just before I left Chicago for Rochester, I met my wife, Maggie, and two days later proposed. She accepted, over the violent protests of our parents, and we married in Rochester. This was in 1947 and we have been happily in love ever since. She claims to have few if any regrets. I can only bless my luck, for she is certainly the most comely and sympathetic and wise woman imaginable.

I left Rochester after a year, having worked with Wendt’s elevator that could bounce cats up and down by sine waves, trapezoid waves, triangular waves, and square waves. It was silly work but I had contracted to do it. In my spare time, however, I had made some then-novel discoveries on the vestibular fibers in cats. But Wendt forbade me to publish them from his department because he positively hated electrical records. So I left to go to Utah where I had been offered a position to do neuropharmacology. But the Utah funds fell through just as I started out by car. We stopped in Chicago where our first son, David Warren, was born within a few days, and now I had to make serious plans.

At Manteno State Hospital, 50 miles south of Chicago, there was a shortage of physicians but a most admirable administrator, Dr. Paul Bay. I made a deal with him that I would serve as neurologist and night physician if he would give me space for a laboratory. He agreed. Warren persuaded Von Neumann to persuade ONR to give me a start-up fund of $5000 to outfit the lab. I built my own amplifiers, stimulators, and animal holders. The only commercial device was an oscilloscope that I modified to give me a linear sweep, and an old Bell and Howell 35-mm movie camera that I fixed to give me single frame records.

Within the year I was joined occasionally by Pat Wall, then an assistant professor of anatomy at the University of Chicago, Paul Dell from the University of Marseilles, and Tony Remond from the Saltpetriere in Paris. Dr. Bay was kind enough to allow them visiting quarters when there were some; otherwise they stayed overnight in our cottage. We worked on spinal cord physiology with particular interest in the effects of the bulbo-reticular inhibitory system. On looking back I regret that we did not publish the work. Incomplete as it was, there were some solid, interesting findings that have not yet been reported by others.

After a while graduate medical students began showing up in search of postdoctorate projects and there were times when the lab was crowded. Walter visited often from Boston and so did Warren from Chicago. Pat Wall and I wanted to go on to study spinal cord physiology with microelectrodes, but such a project would cut severely into my clinical time. I had gone for close to a year on four hours sleep a night. Furthermore, I had neglected Maggie dreadfully.

Incidentally, over the few years I was at Manteno I became a shrink that some members of the Mafia trusted. In return, they did favors for me. Chief among them was an old Cadillac limousine which I could use to round up feral cats that the farmers wanted to see taken away. So I never ordered experimental animals. I had no budget for acquiring or housing them. All experiments were acute.

Clinically I made two innovations. In 1950–1951 I was first to use apomorphine in treating Parkinsonism. In 1950 I was first to use oral myanesin as a human tranquilizer after Elwood Henneman showed its calming effect in oral form on Warren’s dog, Puck, who was frightened by thunderstorms. I tried it first on myself in moderately high dose and sat in high good humor for about two hours, giggling. In lesser doses it worked wonderfully on patients. But adaptation to it was rapid and I recommended it be used only once every other day. Becker, meanwhile, had made a version of much lower solubility so that it could not be used in overdose. This issued as Miltown, and, if you remember, was overused for a time as a popular fad. Then it was dropped from the NNR precisely because of the marked adaptation at only two doses per day.

In the meanwhile Maggie languished as a housewife, bore our daughter, Ruth Anna Livia, on April Fool’s Day, 1950, and then went into the unenviable suspended animation of a doctor’s wife in a madhouse, having nobody to talk with but the ambulatory patients. The other doctors’ wives were unapproachable; they didn’t even commingle among themselves. By this time she had become seriously deaf from otosclerosis. In retrospect I can only regret how she must have suffered, but there was no treatment for her condition at that time and she retreated into plain servitude. She wanted more children, but every pregnancy worsens the affliction. Meanwhile she took an interest in patients and, with very good judgment, she liberated more women through her back door than would be freed by the clinical board. The hospital had 8000 patients and only eight doctors, two of whom were fairly incapacitated. Of the remaining six, three were refugee German Jewish psychiatrists who had not the simplest knowledge of ordinary people. I mentioned they were Jewish because I remember being taken aback when they refused to release a Polish inmate who gave his profession as “Shabbas goy.” They would not believe me that there was such a calling, and I had to bring a sociologist from the University of Chicago to verify it.

Although one member of the board was a woman, they were chary of releasing women inmates who had been immured on almost no grounds except the malice of a relative or some other triviality. That is where Maggie rightly stepped in. Dr. Bay knew what she was doing and tacitly approved.

Translation to MIT

Late in 1950, Wiener had persuaded the Research Lab of Electronics (RLE) at MIT to import nervous physiology. Warren, Pat, and I were invited to come as research personnel, not faculty. Warren and Pat resigned their academic posts and the three of us metastasized to MIT in 1951 to be joined there by Walter. A separate group was set up by Rosenblith, who came from Harvard. Jerry Wiesner, above all, was our protector and guide.

By 1955 we produced our first major work in the physiology of the spinal cord, a set of momentary maps of sources and sinks of current at various times after a dorsal root volley. The task was arduous experimentally but yet more arduous computationally. It took several people close to a year to process the data. Today we could have had the results in less than an hour. The study showed that a volley in one root had a profound and protracted effect on the results of a volley delivered in an adjacent root some 10 ms later. The effect of the first volley on one root was to block for many milliseconds the invasion of a second volley onto collaterals of an adjacent root. This interaction occurred far presynaptically. Later Eccles discovered the same effect by other methods.

Bob Gesteland had come over from General Radio as our first doctorate student at Walter’s suggestion and addressed the problem of recording from single units in the frog’s olfactory epithelium. It took some time to work out a clean air delivery system that carried sharply limited olfactant pulses, but his admirable work gave the first records of single unit activity in this system. He has since become a notable authority on the sensory processes in smell.

At about this time Brad Howland appeared. I have thought of putting him into the Guinness Book of Records as the only graduate student who stayed as such for 31 years. He was a brilliant inventor and engineer whose specialty was optics. Self-supporting, he saw no reason to engage with timewasting society and he proposed to remain in the comfortable Teflon tower of MIT as long as he could. He had his own laboratory down the hall. There is no space here to describe his clever work.

Familial Interlude

I break off to tell of my family. In 1952 Maggie had a fenestration on her left ear that made her hearing better than mine. She flowered marvelously thereafter. In 1954 our third child was born, Jonathan Democritus. I was spending so much time in the lab that Maggie had the full burden of raising our kids. Then something occurred that foreshadowed her future role.

One of my best friends at MIT was Giorgio de Santillana, the historian of ideas. He was a most learned and kindly man with a mordant wit. Walter, Wiener, and I often hung out at his office. Giorgio was a past-master at fortune-telling with the Tarot. Wiener loved having his fortune told. Giorgio vainly tried to persuade him that the Tarot should be a rare and sometime thing to be used only in crisis, but Wiener would have none of such excuses. For example, Walter and I used it when we started a new experimental venture. There’s nothing mystical about it—it brings up, by chance, associations that you do not ordinarily consider and in that way serves to break the constraints that hemmed your thinking. It is a charming way of introducing overlooked contingencies. So every month or so, Giorgio would give in to Wiener and come up with a fortune together with a complex character analysis. At the end of the reading, Wiener would exclaim “But that’s not me, that’s X (or Y or Z)” where X, Y, or Z were fellow mathematicians. Giorgio would shrug and say ‘‘You may have been thinking of them when you picked the card.”

Anyway, one evening in the mid-1950s, when Maggie and I visited him, he offered to tell her fortune for he liked her. He read it to show that by age 40 she would become famous, author several books, and be popularly admired for her wisdom. I think he was as startled by this as was she. Giorgio never flattered anyone—but there it was in the cards. She never forgot that evening after the predictions all came true. But by that time Giorgio was dying and she could not tell him how right he was.

Walter’s Tragedy (Expurgated)

Returning to the conditions at MIT Walter, as I said, fled his home in his early times because of his father. Warren and I were his close friends but Wiener became the father he never had. One day, in 1952, Wiener sent from Mexico City a registered letter to Jerry Wiesner severing forever all relations with Warren, Walter, and me. Years later, Arturo Rosenblith, at whose house the Wieners had stayed at the time, gave an account of what happened. It is a shameful story; Wiener himself was as much a victim as we. The tale is not worth telling here. But the anathema destroyed Walter. He gradually and politely bowed out of being, lost interest in pretty much everything, and became inaccessible. After the few years that Warren and Rook, then Maggie and I, took him in, he did what he could to disappear in a small rented room where he died after years of unrelieved despair. He had burnt everything he ever wrote.

I have often wondered whether I could have done anything. After all, as psychiatrist I could have a found a colleague to take him on. But the problem was that Walter would not go, and in any case was dead of despair long before he died. Wiener was unapproachable on the matter by any of our many mutual friends.

The Frog’s Eye

After 1955, I was drawn to study frog vision by a young visitor from Scotland, Alex Andrew, who thought physiological work on cats barbaric. Part way into the study he extended his proscription to frogs, mainly because his future wife was a firm anti-vivisectionist. However, we had begun to have some interesting results and I was reluctant to abandon the work. By that time I had met Humberto Maturana, whose doctorate thesis at Harvard on the electron microscopy of the frog optic nerve showed that only 3% of the half-million fibers were myelinated. I invited him to join the laboratory and within a year we had worked out the method of recording from single unmyelinated optic nerve fibers of diameter 0.1–0.5µ mi. Umberto had a delicacy in surgery that I could not achieve, a broad learning, and a keen mind. I thought we worked well together but afterward his wife told Maggie that he would arrive home in a fury, unable to sleep for cursing at me. In retrospect, I don’t blame him. Nevertheless, the work got done by 1957. Warren and Walter pointed out questions we had to answer by designing new tests and classifying our results. Oliver Selfridge helped write the paper.

One aspect of our now well-known paper, “What the Frog’s Eye Tells the Frog’s Brain,” (for which title I am much indebted to John Moore) is that nobody to my knowledge has ever repeated the recording of the unmyelinated fibers in optic nerve. As Arthur Grant and I showed in 1991, the easily recorded signals in tectal neuropil are the responses from active glomeruli, the dendritic appendages of tectal cells. Their activity represents the correlated activity of many neighboring retinal ganglion cells of the same type. The pulse trains of glomeruli are readily distinguished from those of single optic nerve fibers in pattern and duration.

Some Details of Work on the Frog’s Eye

One of the deficits in previous papers on the frog optic nerve was that the accounts of Hartline and Barlow were obviously on the easily recorded myelinated fibers. The receptive fields were large, and though Barlow made a good attempt at dredging visual resolution from possible higher order processing of the combinations of field operations, it was not persuasive. Until we could record from the unmyelinated fibers which were 30-fold greater in number, there was no way of qualifying the retinal output. We did not want to poke electrodes through the vitreous or through the retina to record from the small ganglion cells (whose axons are unmyelinated) because the presence of such an electrode itself distorts the images in the neighborhood.

A good deal of research consists of endless floundering until a lucky accident happens. It was well over a half year before we recorded our first unmyelinated fiber by accident. At that time the conventional way of telling whether you were recording an optic fiber was switching light on and off and seeing if a signal occurred. After all, the retina is photosensitive. If there was no signal the electrode was thrust further. As Umberto moved his hand to advance the micromanipulator there was a mutter of activity on the loudspeaker. He stopped. Again there was no response to turning the light on and off, but again, moving his hand as if to touch the manipulator evoked the mutter. It did not take long, with minute excursions of the tip, to maximize transients well above the noise level. With various small targets, moved about in jerks, we could estimate the size of the center receptive field at 3–5°, much smaller than the fields previously recorded.

Pastiche of the Decades

Most of my own work has not been submitted for publication except as students or colleagues were involved. Since this is an autobiography rather than an official history, I can dally on some of those peripheral efforts and tell of two projects. The first arose from Steve Raymond’s doctorate thesis in which he showed by an elegant new “threshold hunting” method the course of threshold change in a single axon after an impulse. The aftereffects of an impulse can be tracked for a long time, but, for practical purposes, Steve limited his observation to a few seconds. The aftereffects of a short train can endure for half an hour.

These aftereffects of a pulse on threshold of a nerve fiber are of two sorts after the refractory period: a short saturating period of hyperexcitability, and a long, nonsaturating period of depression. The first does not build up with repeated stimuli, the second does; the decay time of the latter increases markedly with the magnitude attained.

The existence of these two phases suggested a new approach to the decoding of information encoded in pulse-interval patterns. It had long been known that the impulse down an axon usually invades only a fraction of terminal synapses. This can be shown by collision experiments where an orthodromic pulse invading the tree allows an antidromic impulse to pass back into the axon from stimulation at the synaptic region. In axons that have been post-tetanically potentiated, at the peak of the potentiation the whole tree must be invaded since none of the anti-dromic impulses get through. The normal partial invasion of the whole tree under ordinary conditions sets the problem: what determines if a branch is invaded? At a bifurcation, there is a general principle that seems to hold for all branching systems, that the two twigs into which a branch divides are asymmetric in diameter. At the same time, the safety factor of impulse transmission drops markedly at bifurcation.

Since the time courses of the same membrane processes change with the surface/volume relations of a tube, it occurred to us that bifurcation of an axon along with the low safety factor makes a two-bit switch which depends on the time since the last invasion of the tree. In that case, the axonal tree becomes a decoder of pulse-interval codes, giving a historydependent sequence of the partial invasions of the terminal synaptic field. Steve Raymond and Paul Pangaro did a nice movie of the threshold aftereffects and their role in temporal coding.

The first time I proposed this, a talented young mathematician, Rusty Bobrow, chose to do a doctorate thesis on the model. He was already getting some interesting results with a simple tree of eight terminals when the math department disallowed the project for not being certain enough of a result. It was not a well-defined problem. So Rusty quit and went on to make a name for himself at Bolt, Beranek, & Newman, a prestigious company in systems analysis and design.

The second time, two decades later, the same problem in another form won a doctorate for Gill Pratt from the department of electrical engineering and computer science where he is now assistant professor. But then it was too late for me to set up a physiological study to show its application, even though Gill and Arthur Grant and I showed the systematic spectral coding of light by a single fiber from the frog’s eye, the type that goes to the thalamic nucleus.

The second project that I look back on joyfully and regretfully has to do with stentors and involved Eric Newman, now full professor at the University of Minnesota. Using Vance Tartar’s method we fused pairs of stentors every which way. Stentors are single-celled trumpet-shaped protozoa which are wonderful to watch. They do many distinct acts: elongate or contract, make a hold-fast at the narrow end or retract it, move their membranelles clockwise or anticlockwise in changing the vortex that brings food or rejects unpalatable particles, change the program of beating in the cilia along their bodies, ingest or “spit away” the particles brought to the gullet by the membranelles’ vortex, reverse swimming direction when bright light plays on the “eye-spot” in the field (the head end), etc. Their behavior has several such distinct patterns. What was astonishing to observe was that in a fused pair of stentors a master-slave relation developed. Whatever the master stentor did, the slave stentor did, although it had received no stimulus. If the master changed membranelle motion, so did the slave; if it twisted itself in one direction so did the slave; if it swallowed a bit of food, so did the slave swallow; if it put out or retracted a hold-fast, so did the slave; and so on. The correlation of behavior, while never complete, was so well above chance as to be unmistakable.

There is no nervous system in stentor, and the pair was connected at only one point anywhere along the bodies of the two. How are the different kinds of act communicated until the stentors finally separate themselves as they do (when not paired side-by-side to make a single stable doublet that propagates itself by fission)? Eric wisely saw this as an endless venture and switched to the analysis of current generation of the frog retinogram for his doctorate. But it was a wonderful problem, this communication of many distinct patterns of behavior between conjoined stentors.

I have remained haunted by this memory, delighted to have made the observations, regretful at not having pursued the matter further.

There are about a dozen such strange projects that occupied some of the time, were clearly worth taking to some presentable form, but could not be carried out to publishable state in a guaranteed way. At its peak the laboratory had about six or seven graduate students and postdocs working on clearly defined problems and there was room for much diversion (although I regarded it all as serious play).

Around the mid-1960s we lacked money for new apparatus. Brad Howland (my permanent graduate student) and I decided to remedy the deficit by making some ready cash. Miller and Licklider had published two papers. In one they showed that the highest intelligibility of chopped speech (sound alternating with silence) lay around a chopping rate of 100 Hz. In the other paper, they showed that speech versus noise gave highest unintelligibility at that same chopping rate.

We instantly cooked up an anti-wire-tapping device for the telephones of bookies. Their problem was to receive track information in a timely fashion, but since that was illegal, to avoid identification by a wire-tap. Since the speaker at the track does not have to listen to what he says, the receiver can chop with silence what he hears, and in the silent phases insert noise on the line.

The most excellent confusion was had by using as noise yesterday’s race results recorded by the same speaker and an irregular chopping rate driven by thermal noise in the 90-110 Hz band. We tried it out and it worked well. For evidentiary purposes in court, the wiretap was useless (These were the days before computers were widely available).

I called a Mafia friend and asked him to find out if the bookies in New York would pay $10,000 for the gadget. After he confirmed this, Brad and I went to Henry Zimmerman, then head of RLE, to get his permission. This was Tuesday and the delivery of the device had been set for Saturday. Henry was amused and consented. But on Friday we were recalled to his office. There were two colonels. They asked to see the document that went with the gadget. We showed it to them. Then one pulled a stamp from his pocket, marked the paper TOP SECRET, and forbade us from the sale. Brad and I had to call my contact to tell him that the device didn’t work. Louie knew me well, so he called that evening and asked if Maggie and I would go to the movies, leaving the device and paper in my desk at home. There would be a burglary and a nice surprise left behind. I called Brad to see how he felt about it. He advised that we chicken out. So we did.

Several historians of cryptology have tried to get access to our paper, but Henry told us that somehow it has disappeared. Oh well.

Later on the Chicago Mafia offered to give the lab $30,000, no strings attached. Jerry Wiesner was president then, and I told him of the offer. He said “absolutely not” in no uncertain a tone. But then, as I was leaving, he said thoughtfully, “Now, if it were 300k. .. “ We both laughed.

I cannot forbear mentioning one success that got quashed. I had gone to lecture in Hawaii and while I was snorkeling one day with my son Jonathan, he called my attention to a flounder that was slithering along the bottom. I didn’t know the species. When the flounder crossed a rock larger than it, it seemed transparent, as if the rock were somehow visible through it. After I reported this to the students back at the lab they accused me of finding a new way of smoking pot under water.

Bill Saidel, however, decided to investigate the coloring of northern flounders. In 1914 someone had photographed a flounder against four checkered bottoms of markedly different periodicities. It seemed evident from looking at the flounder against the bottom that it carried the periodicity of the bottom across its back. Now the eyes of the flounder are atop the flat head. It is hard to imagine how the flounder, resting on the bottom, can match the bottom periodicity by its vision, just as the flounder I saw crossing the rock seemed to complete the rock across its back.

Saidel took as his doctorate topic the physiology of the pigment movement in the pigmented cells of the flounder skin. This satisfied his thesis committee in the biology department. He bent to it with a will. But meanwhile, he made a startling discovery. When the old pictures were reproduced carefully (they weren’t that good to begin with) and the flounder in each picture was nicely cut out from the background, all of the four flounder images were practically identical. There was no sign of any checkering period. They differed slightly in contrast as if the photos were differently developed, but that was all.

What seemed the case is that the apparent periodicity across the back of the flounder is filled in by the observer. The transparent long fins on either side of the flatfish are flecked by the same spots of varied size as over the body so that the background checkering is blended with the overlaid spots. In this smooth transition to the opaque body of the flounder, the surrounding periodicity is subjectively imposed by the observer on the spotted texture of the body.

There are several well-known optical “illusions” that have this character. For example, if you set a TV set to an empty channel, the screen is cluttered with random visual noise. When you intrude your finger over the screen from one edge and slowly wiggle it up and down, it is as if a ghost of the finger protracts itself ray-like well across the screen, a form construed from the noise.

The art of speckling over the northern flounder’s back is not that it portrays periodicities that the flounder can ill see, but rather that it leads you to protract into it periodicities that you can well see. That is great art indeed, and we were all enchanted by Saidel’s wit and demonstration.

He completed his thesis on the mechanism of pigment migration in the skin cells of the flounder to the satisfaction of the biology department. But they struck from the thesis the whole appendix that carried the story of the induction of form into texture by the observer. To the department it was a wild speculation in psychology which had no place in biology. That deletion from his thesis was a bad blow to Bill. He published it two decades later in an obscure German zoological journal, but so tersely and cautiously written that one could barely grasp the point. He never fully recovered from the departmental snub.

Enough of these stories. Over three decades (1956-1986) of flourishing and florid ventures, more flowers for the imagination than food for thought, the more serious funded research work of the laboratory went on. We were kept going by funds from NIH, the Air Force, and, blessedly, Bell Laboratories which seemed to get more of a kick from our strange work than from our official missions. The bibliography of the laboratory is as variegated as it could be, and a source of the great pride I have in my students and postdocs. I say bluntly and sincerely that I served more as a catalyst to their ideas than as a source. They were a highly talented lot. The Research Laboratory of Electronics at MIT was a garden for ideas, with the richest intellectual soil that could be imagined, and a great many of the developments that MIT boasts were first nurtured there. But that would take a separate set of volumes.

Maggie

True to Giorgio’s tarot reading, Maggie did become a famous figure by accident. Unable to move her arms for several months after a severe whiplash when she was back-ended at a traffic stop, she refused surgery. Instead, she studied my anatomy books and worked out her own therapy on mechanical grounds. The word spread and in a short time she helped so many students and staff at MIT with their back problems that they persuaded her in the 1960s to start a self-fitness class at MIT. By the end of the year there were 200 people a day taking her classes. Then Channel 4 picked her up, then Channel 2 (PBS), and her set of daily shows attracted a huge following. They were repeated for 17 years on TV. She wrote four books, of which one, Maggie’s Back Book, is still in print a quarter-century later. When it first appeared, the great neurologist, Denny-Brown, ordinarily undemonstrative, embraced her at a party saying she had finally rid Boston of needless back surgery. Everyone was astonished and she loved it.

She is now finishing an expert system for the web, devoted to showing how to rid yourself of back pain.

Our three children have successful careers in fields they chose carefully to be those I know nothing about. Of our grandchildren, one is at Microsoft, one is an animator, one is writing for TV and films, one is a boxer (she also studies philosophy), and two have yet to graduate high school.

Bexley

In the late 1960s and early 1970s, Maggie and I spent six years as “houseparents” at the most intractable dormitory at MIT, Bexley Hall. One of these days Maggie will write her memoirs of that time under the title “Any Sport in a Dorm.”

I can talk about two odd episodes here. Bexley had wire taps on the Cambridge Police lines, on an FBI office, and on a CIA observing office at 545 Main Street. Everyone assures us this must be false—such offices are not permitted on U.S. soil. But 545 Main Street was the home of advanced work in cryptography, artificial intelligence, and all those strange computer arts that spawned the modern age. The CIA would have been remiss if it had no presence in the shadows.

At any rate, a premed student on the 4th floor of Bexley was secretly financing his future career by manufacturing LSD which he incorporated into sugar cubes or thin gelatin sheets. One of his shipments to New York broke open at the post office. The damn fool put his return address on it, but not his name. Our students got wind of a federal raid on Bexley from their tap on the police line. In the morning, when the forces showed up, a large hand had been mounted in the courtyard pointing the feds to the proper entrance, and all along the staircase there were careful directions to the room they were to raid. Of course, everything had been cleaned up. But the next week was out of a Keystone comedy. Agents with binoculars lurked behind the windows in the ship museum across the street. Students, mounted on our roof, used ridiculously large binoculars to watch the agents. Various jokers, clad suspiciously, slouched in guilty wariness along the street. In the end, everyone gave up the nonsense. Meanwhile the premed student stopped cold when threatened by us with putting the episode on record.

As I say, this is one of the less involved incidents that over the next six years both enlivened and exhausted us. The images of our stay there are among the most vivid in our memories.

I had known Tim Leary (the LSD guru) for awhile. He once visited the lab to describe his allowed pot sessions at Concord Reformatory (officials deny it now). He had accumulated evidence that those who smoked pot in the jail had the lowest recidivism, and argued “post hoc, propter hoc.” I don’t know the details because he never published them. Before we went to Bexley, Tim was brought at some expense by the student lecture committee to give his argument for “Turn off, tune in, drop out,” the incentive to drug use. There were no funds left over to bring in a contrarily minded notable so at the last minute, I was asked to fill in.

It was a memorable evening. At the end Tim muttered to me “that’s the last time I debate a Jew.” We both laughed. But the debate got instant attention by the press. The Boston Globe extolled me in an editorial, and Variety reported it as the first time “bull shit” was ever uttered unbleeped on TV. It was nice to be a hero for a few days. High schools throughout the country used the replay in the war against drugs.

Current Work

Gadi Geiger joined the laboratory 15 years ago. He and I began a study of “lateral masking” in human vision. A remarkable set of findings gave us a new non-reading visual test for dyslexia. The test, in turn, suggested a treatment which was eminently successful in all of the few adult dyslexics on whom we tried it. The treatment cost practically nothing and involved no supervision.

We saw dyslexia as a learned perceptual strategy and showed how it could be unlearned. This is heresy in an era of neurocalvinism, the determination of a disability by a defect in the brain. But then we made controlled experiments on grammar school children and got admirable and convincing results. Nevertheless, although our results have appeared in highly esteemed refereed journals, we are still regarded with suspicion.

The essence of our thesis is that there is a strategy in perception determined by the task to be performed under perceptual guidance. That is to say, the processing of visual information is determined by what use is to be made of it, and changes with that use. This is not a foreign concept in psychology. The works of Richard Held, Ivo Kohler, and many others show different applications of this idea. That there are physiological correlates, and physiological mechanisms involved, goes without saying. But the application of physiological psychology to what are classified as neurological disorders is now beginning to take hold. A fair amount of evidence on the “plasticity” of the continually reconnecting brain has finally become convincing and is changing the face of neurology.

I am glad to have been involved all my life in what interested me because I was given the freedom to pursue what I chose. What luck!

Paul D. MacLean

BORN:

Phelps, New York

May 1, 1913

EDUCATION:

Yale College, B.A. (1935)

Yale University School of Medicine, M.D. (1940)

APPOINTMENTS:

Yale University School of Medicine (1949–1957)

National Institute of Mental Health (1957–)

Laboratory of Neurophysiology (1957–1971)

Chief, Laboratory of Brain Evolution and Behavior (1971–1985)

HONORS AND AWARDS:

Distinguished Research Award, Association for Research in Nervous and Mental Disease (1964)

Karl Spencer Lashley Award, American Philosophical Society (1972)

Anokhin Medal, P. K. Anokhin Institute of Normal Physiology, Academy of Medical Sciences, U.S.S.R. (1986)

Paul MacLean is best known for his formulation and elaboration of the concept of the limbic system, which is based on relationships between the “visceral brain” and psychosomatic disease.

Paul D. MacLean

Introduction

This autobiographical sketch will be limited to tracing the experiences and ideas that led me into brain research and the kinds of experiments I did thereafter. After all, without a history of the products of our subjective experience, there is little to link the formulation and evolution of ideas from generation to generation. The mention of subjective experience requires that I state right at the start what I mean by that expression.

Neurologically speaking, subjective experience boils down to psychological forms of information and, as Norbert Wiener (who coined the word cybernetics) cogently expressed it, “Information is information, not matter or energy” (Wiener, 1948, p. 155). Regarding the immateriality of his definition, an argument by Neils Bohr about the existence of the particle and wave of quantum mechanics offers a kind of parallel: “A particle in reality has neither a position nor momentum. It has only the potential to manifest these complementary properties....” (Bernstein, 1991, p. 48). In thinking of Wiener’s definition of information in light of Bohr’s comment, it must be emphasized at the same time that there can be no communication of information without an expenditure of energy. This might be regarded as a law of communication. The word potential calls to mind Aristotle’s “potential,” applying in his philosophy to different forms of nothingness, which would compare to the use of our word information. The so-called law of communication would seem to be incompatible with Cartesian dualism, which proposes that brain matter and the operations of the mind are independent of one another.

Although it can be argued that there is no certainty of knowledge, it does not deny our subjective feelings of certainty that none of us would be engaged in human endeavors without the diversity of our subjective experience. Certainly without it, there could hardly exist the commonly expressed questions such as, “Why are we here?”; “Where are we going?”; and “What is the meaning of life?” And the same reasoning could be applied to such everyday things as colors and other qualia which, except for their subjective generation in our brain, do not exist in the entire universe.

Since there are indications that the brain provides the algorithms capable of leading to solutions for everything we do (Vandervert, 1988), there could hardly be any more important investigation than the discovery of the neuroanatomical and chemoarchitectonic connectivity of the brain which allows it to create its particular species of algorithms (MacLean, 1997). In one of his informal writings, Santiago Ramón y Cajal (1966) stated, in effect, that everything that goes on in our perceived universe is but a reflection of the structure of the brain.¹

Epistemology deals with the origin, nature, limits, and validity of knowledge. It represents a collective public approach that attempts to find what can be publicly agreed upon on the basis of what is observable, that is, “facts.” In a word, epistemology seems to disregard the realization that everything “selected for study, every observation, and every interpretation, require subjective processing by an introspective observer” [The Triune Brain in Evolution (TBE); MacLean, 1990, p. 5). The irony of the purely objective approach is that there is no logical way of circumventing the realization “that the cold, hard facts of science, like the firm pavement underfoot, are informational transformations by the software of the brain, the physical properties of which are defined as ‘viscoelastic’” (MacLean, 1990, p. 5). As a complementary term for that branch of epistemology that deals with the body of knowledge and the collective disciplines concerned with clarifying the nature and limitations of the subjective brain, I have used the expression “epistemics” (MacLean, 1975, 1990, p. 4). Later, I shall have occasion to mention some of the limitations that may be expected even if we were able to discover the detailed connectivity that accounts for the brain’s particular species of algorithms.

Childhood Influences

The background for my growth and development was that of a Presbyterian minister’s family. I was born on May 1, 1913, in Phelps, New York, which is in the Finger Lakes region near the head of Lake Seneca. My parents, along with my two older brothers, had moved to Phelps the previous year from the town of Naples, where my father had begun his ministry in 1904. The youngest of a large family living at Lake Ainslie, Nova Scotia, my father was influenced by his oldest sister, Euphemia, the widow of a minister, to pursue the same profession. After obtaining his education locally and in the nearby city of Sydney, he completed his education for the ministry at Auburn Seminary in Auburn, New York, near the head of Lake Owasco. While at the seminary, he helped to support himself by substituting for ministers on summer vacation. Preaching in Delhi, New York, on one of these occasions, he fell in love at first sight with a beautiful young woman in the choir, Eliza Dreyfus, who was to become his wife and mother of four sons.

The manse where I was born was on the north side of a red brick, paved main street, located a few houses east of the red brick Presbyterian church with a lovely, towering steeple. The manse itself was also brick, but painted yellow and faced with a low, white porch. The fields, gentle hills, woods, and streams surrounding Phelps were a veritable wellspring for a child’s imagination. Indeed, one had only to go down to the foot of East Main Street to follow a stream that led to pussy willows in spring, or a stunning nest of speckled pheasant’s eggs in the leaves at the edge of the woods. In the fall, there was raking of leaves, running and jumping into the piles, then the smell of burning leaves with chestnuts exploding from deep within. In winter, there was plenty of snow with hillside sledding, horses with jingle bells pulling sleighs, or bobsleds filled with hay.

I’ll mention just a few childhood incidents that might have influenced my career. Because my father was in the pulpit on Sundays and my mother and two older brothers sang in the choir, it seemed quite natural that I was encouraged to attend Sunday School as early as possible. Sometime between the age of three and four, we were learning the Ten Commandments when someone indicated that you might be struck dead if you took the Lord’s name in vain. This led to what might be described as my first experiment. The assertion continued to bother me because I had heard the Lord’s name taken in vain and had never seen anyone struck dead. So, one day, when the manse was empty, I went into a closet, closed the door, and shouted at the top of my lungs, “JESUS CHRIST!” I waited for lightning to strike, and nothing happened. I was to learn later that this experiment was counterproductive. Whoever had said that one might be struck dead if you took the Lord’s name in vain had not qualified whether it would occur immediately or sometime in the future. Hence, I have been waiting ever since.

The next incident occurred sometime after I was considered old enough to go to church. Again, because my father was in the pulpit, and my mother and brothers were in the choir, I had to fend for myself and was advised to sit in the back of the church where my presence would be less conspicuous. One warm spring Sunday I rode my tricycle to church and parked it in a safe place far from the door. I walked up the steps, and once inside, chose an empty pew just to the right of the central aisle. My father was not far into the sermon when a little girl a few pews ahead of me began to giggle uncontrollably while alternately looking up at the ceiling and covering her mouth to suppress her giggles. Finally, I could not resist my curiosity to see what was amusing her. To do this, I had to climb over the partition between the pews. At the instant I stood up to make this move, I heard a voice from the pulpit shout, “PAUL!” I spent the rest of the sermon figuring out what I should do. I decided to run away from home and, right after the Benediction, slipped out quietly and rode my tricycle down the next street toward the flour mill by the Canadaigua outlet. I was seeking refuge in the house of Anna Kent, the dressmaker, whom I had gotten to know and love when she came to our house to sew for my mother. She had the soothing, deep voice of a quietly playing organ.

When I failed to return home after the service, my two older brothers were sent out to search for me, and it was not long before I was brought home, expecting a thrashing. But there was not even a scolding. If there was, it had come from just the sound of my name, Paul, shouted from the pulpit. But ever after that, I kept wondering to myself, “Why do people who know better do things that they also know may get them in trouble?” In retrospect it would seem I was perseverating on the question raised by Spinoza’s statement to the effect that all people are driven by their emotions. The persistence of that question seems to have been instrumental in steering the direction of my interests when I engaged in brain research 30 years later at the Massachusetts General Hospital (MGH).

World War I

After the church incident, there was a concatenation of world events triggered by the assassination of the Archduke of Austria and his wife at Sarajevo, Bosnia, on June 28, 1914, and Austria’s declaration of war on Serbia. The Germans, who sided with the Austrians, declared war on Russia and soon opened a second front in Belgium, where, to everyone’s horror, they were depicted as cutting off the breasts of Belgian women. Eventually, the reticence of the United States to engage in worldwide conflict was overcome. We were to learn via telegraph and newspaper that our government had declared war on Germany on April 15, 1917. Thereafter, I found my 4-year-old mind swimming in a sea of war-related events—my father’s donning a uniform to serve as chaplain at Camp Merritt, New Jersey (and eventually returning with uniforms to fit me and my three brothers); my watching the burning embers of the logs in the fireplace and imagining the back and forth lighting-up of sparks as soldiers fighting in the trenches of France; the hanging of an effigy of the Kaiser, followed by its burning in the town park on a mountain-high pile of potato crates; a movie at the town theater showing fighting against the Germans and an officer with a spiked helmet flying 40 feet into the air after being hit by a single bullet. Then there was the surprise false armistice, when we as children were awakened at four in the morning and given hot cocoa. And finally, on November 11, 1918, the daytime telegraphing of the real armistice, with all except my youngest brother, Burton, going our separate ways with neighbors in open cars to spread the word of victory to the outlying farmers. That was an unbelievably warm and sunny day!

During the war, I had my first introduction to a medical condition. I first heard the word “germ” in Phelps when I contracted German Measles. When I asked why I was sick, it was explained to me that germs had gotten into my system. I mistook the term “system” for the word “cistern” which, in those days, were located in the cellars of houses to collect a supply of rainwater from the roof. My room was on the second floor of the manse and on a balmy spring day during the height of the war, I had the window wide open so I could look out onto the street. A good friend of the family walked by and called up, asking why I was in bed. I was reported as saying, “I have too many Germans in my cistern!”

Not long after the war my father received a “call” from the Presbyterian church in the small city of Hornell, New York, some 60 miles southwest of Phelps in the foothills of the Allegheny Mountains. As a six-year-old, there were many reasons for my disliking Hornell. Apart from its atmosphere of manufacturing, the location of the manse was just around the corner from the business district, and there were no nearby inviting streams to play in. Most disturbing to me was the closed-in feeling produced by the surrounding hills and my inability to see the horizon from any spot. The absence of a horizon as a reference point was particularly disrupting to my current preoccupation with trying to discover how Columbus concluded that the earth was round. I was partially reconciled when, one day while sitting on the steps of the gray stone Presbyterian church where I had a sweeping view of the sky, it suddenly occurred to me that the heavens were rounded like a tremendous dome.

But these dislikes were nothing compared with the anxiety generated by the renowned flu epidemic that later crept into Hornell and, in our own house, threatened my mother’s life. The dread that she might die brought back one of my earliest memories from Phelps. One morning at get-up time, I had scampered across the bed and asked her, “How long will you live, Mother?” She did not answer, and when I asked again, she pretended to swat me so as to get me to move along. I was to wait a long time before my brain research gave me some evolutionary insight into why separation—or even the threat of separation—is such a painful condition for mammals.

I think we were all happy when, three years later, my parents decided to accept an attractive call to the Presbyterian church in Batavia, New York. The gray stone church with the bell tower topped by four pinnacles was at the corner of Main and Liberty Streets. Our large brick manse with high ceilings was next door on Liberty Street.

In some respects, Batavia was a larger edition of Phelps. The towering elms of East Main Street gave such a lovely, cathedral-like appearance that Thomas Moore described them in a poem when he visited there in the early 19th century. Like Phelps, the city was edged by surrounding farms that could be reached by bicycle and where one could hear the sounds of crows and chickens, delight in the familiar smells of horses and cows, and inhale the fragrance of new-mown hay.

With experiences like these, my childhood years in Batavia, punctuated by two-month-long summer vacations at the Thousand Islands, were hardly more notable than a long, quiet, organ prelude. One of my most enduring childhood influences was a cultivation of a love of painting, triggered by the gift of a box of oil paints and brushes from my oldest brother. I found that once I started a picture on a Saturday, I could not leave it all day. Another enduring influence occurred in eighth grade. A lovely older teacher once said to me, “noblesse oblige.” I did not know what it meant at the time, but along with the golden rule, I have been thinking about it ever since.

The approach of high school brought with it a real fracture in my way of life. My oldest brother, Charles, had attended Hamilton College for a year and then transferred to Yale College. In his letters to the family, he successfully conveyed his impression that students who went to Yale were far better off if they had attended a preparatory school. That was enough to get me looking, and I turned up one in the Adirondacks that sounded like a real resort where one rode horses, played tennis, and so on. But the hammer came down quickly on that notion, and I was advised to apply for a school that prepared particularly for a college like Yale. I was fortunate to learn of the Taft school, where I applied and, probably thanks to my being a minister’s son, was awarded a full scholarship of $1600 a year for four years.

Steps toward Medical School

Perhaps one disadvantage of a preparatory school is that it overprepares you for what to expect in the first year or two of college, when one is presumed to be getting steamed up for selecting a major. I attended Yale as an undergraduate but, without the exhilaration of novelty, I found the first two years rather humdrum. All of that changed in the third year when, along with honors work in English, I discovered F.S.C. Northrop’s course called Philosophy of Science. At our home the emphasis had been on English literature. Hence, at Yale, I took a minimum of courses required in science and chose biology and geology to satisfy science requirements. At that time, Northrop had the reputation of being one of the few people who could understand Einstein’s theories of relativity. The subject captured my imagination, and after taking his courses in my junior and senior years, I decided to pursue a career in philosophy. My friend and classmate, Steve Crary, who was going to study divinity at New College, Edinburgh, suggested that I go along with him to satisfy my ambition to study philosophy under the Plato scholar, A.E. Taylor.

But no sooner had I purchased a steamship ticket than I began to have second thoughts. How, by reading and rereading what philosophers had already said, could I derive any substantial new ideas about the “why” of life? In September 1935, not long before my scheduled departure for Scotland, an alarming incident occurred at home that was to change the whole course of my career. My mother was suddenly taken ill with what was presumed to be a heart attack. But when the number-one doctor of Genesee County was called in, he dismissed it as a probable passage of a stone in the duct of the gall bladder. It was a tremendous relief to everyone, and after he departed, I thought how wonderful it must be to belong to a profession where one could relieve such anxiety. I decided almost immediately that by going into medicine I could satisfy two aspirations—to help people, and to learn about the psychological functions of the brain. I would still go to Edinburgh, but with the alternate purpose of obtaining the accreditation in physics and chemistry required for entrance to a medical school.

When I arrived in Edinburgh I found that I had not taken into account the accreditation I would need to take courses in physics and chemistry at the university. Most students, I discovered, already had eight years of experience in both subjects. Professor Charles Barkla, who had won the Nobel prize for his work on X ray, gave the first part of the physics course beginning in October. He was an imposing, stout person and wore a swallowtailed coat and striped trousers. When I was ushered in to ask if I could take his course, the first thing he did was ask for my credentials. Upon telling him, he leaned back in his swivel chair, and holding his hands on his round belly, began to guffaw like Santa Claus. Finally, when he was able to control himself, he asked me if I had had trigonometry. When I replied with a slow, side-to-side “no” with my head, he let out such a loud whoop that one might have thought he was going to have a convulsion. When it seemed he would never stop laughing, I went up to him and, patting him softly on his shoulder as though to soothe him said, “Here, here, this is really serious. I don’t have enough money to return to the States.” With that he suddenly stopped laughing, turned toward me and, looking me straight in the eye said, “There’s a week before classes start. Here, take this little book on trigonometry and if you read it, you can take my course.” My accreditation for medical school was completed the following summer when I sailed through organic chemistry at Cornell University in Ithaca, New York.

My first choice for medical school was Yale, where Dean Milton Winternitz had introduced many interesting innovations. After my admission, he winkingly showed me the recommendation that he said had been the deciding factor. It was from Chauncey Brewster Tinker, who had a legendary reputation as professor of English at Yale. He had been sent a questionnaire about me. On it he had written, “I never fill out questionnaires. MacLean is a good man, and you had better take him without more ado.”

All four years during medical school I earned a bedroom and small study in the Dana House at 24 Hillhouse Avenue, which was owned by a gracious, elderly lady, Amy Dwight Dana, the daughter of James Dwight Dana, the geologist, and the granddaughter of Benjamin Silliman, who had introduced the teaching of science at Yale. The house was on a large corner lot, and I earned my living quarters by sweeping a wide macadam sidewalk and its connecting walks. Winternitz gave an early morning course of introductory lectures, and sometimes my broom sweeping and long walk to the school were not always conducive to my arriving on time. He lectured while walking back and forth and twirling a gold watch at the end of a long gold chain. I sensed that it broke the tension when I would walk in late and he would stop, draw himself up to his full height and say, “Good morning, MacLean!” Everyone seemed to enjoy this.

The Yale system had many built-in freedoms, and as every citizen learns, freedom has many constraints. There was the freedom to take periodic examinations which were purported to be for the student’s benefit and which were presumably never graded. A wonderful feature of the system was the opportunity to delve into a subject as deeply as you wanted. There was the challenge, too, of writing a thesis. I started off particularly enjoying the study of the nervous system, but the more we read and were lectured to, the more it seemed that its functions were mainly to regulate reflexes, posture, and all kinds of motor performance. It was a period when people joked that, as far as psychological functions were concerned, the skull might as well be filled with cotton wadding. At any rate, my disappointment was such that I decided I might as well settle down to being a real physician specializing in cardiovascular disease. My thesis was concerned with an attempt to produce cardiovascular disease with antisera.

When it was time to apply for internships, I discovered that there existed a kind of Ivy League competition among eastern medical schools. I was leaning toward an internship in medicine in one school where my good friend (and, later, best man), David Crocker, had wanted to go. But when I returned from an interview there, I was called in by Dr. Francis G. Blake, the dean and professor of medicine at Yale, who was well known for his research on pneumonia. He told me that he had received a letter from Professor Warfield Longcope, the head of medicine at Johns Hopkins University, who wished to meet me and could do so during one of his periodic visits to the Rockefeller Institute in New York. I told Dr. Blake of my leaning for the place I had just visited. “No,” he said, “you’ve got to go to New York for an interview with Professor Longcope.” He stated this in his usual clipped speech, and it was clearly an order. I was fortunate to be accepted into the program, and I learned later that at that time, Johns Hopkins provided a position for only one outsider, and Yale had never had a candidate accepted. Medically speaking, it was one of the most rewarding experiences I’ve ever had. One was expected to be on call 7 days a week, and the day you were assigned to the Accident Room, you could expect to be up all night. Being on call around the clock acquainted one with all phases of a disease requiring hospital treatment.

World War II

I had fully intended to keep a diary my first year at Johns Hopkins, but the only entry I made was when I was hospitalized for a brief respiratory illness. The entry read, “I expect that we’ll be at war with Japan by the end of the year.” At the end of my internship, I returned to Yale as an assistant resident on Dr. Blake’s service, and on December 7th, when Pearl Harbor was bombed, I was in Batavia visiting my parents. I had received an appointment as assistant resident in medicine at the Peter Bent Brigham Hospital for the following year. After the declaration of war, I wanted to join the war effort and decided to sign up with the Yale Unit, which was to become the 39th General Hospital. While waiting for activation, I continued in my position as assistant resident, and also held a research position with Winternitz’s group, which was concerned with treating the effects of exposure to war gas.

It so happened that one day, while tearing up the steps to the wards, I tripped on the steps upon seeing a beautiful girl waiting with classmates to get into the amphitheater for a lecture. Her name, I learned later, was Alison Stokes. She was a Quaker, graduate of Bryn Mawr College, and was studying for a degree in nursing. After our first social occasion, I decided that she was the one person in this world I wanted to marry. We became engaged, and on July 16, 1942, we were married at Camp Edwards on Cape Cod, shortly after hearing the rumor that the Yale Unit would be departing for Europe in three days.

Just as abruptly, the word circulated that our mailing address would be APO San Francisco, and we were issued mosquito netting and snow boots and told to purchase winter overcoats. Where else but Alaska? We did not entrain until the middle of September, and after a mysterious, roundabout, transcontinental crossing, arrived at Pittsburg, California. Here we had orientation classes which included instructions to shoot ourselves if we were ever taken captive, and there were almost daily 20-mile hikes in dry, 90 to 100° heat. The ship on which we were to sail arrived in San Francisco so heavily covered with barnacles that the hull had to be scraped and painted, and it was another six weeks before we set sail with some of the shipmates sarcastically cheering “Golden Gate in ‘48” as we went under the famous bridge.

I include more of this history because of subsequent experiences that got me back on track to my original aspirations to learn about psychological functions of the brain. Despite our presumed preparation for an Alaskan assignment, our unescorted vessel kept sailing in a southwesterly direction, and after three weeks, we docked at Auckland, New Zealand, where we learned that a 1000-bed hospital was being built for soldiers evacuated from the Solomon Islands. At that time, a large number of our troops were on Guadalcanal undergoing a six-week bombardment by Japanese ships firing 16-inch shells. The food supplies of our troops were so reduced that the soldiers were living on rice and maggots.

I could not believe it, but I discovered that I was the only person in the unit who had experience in bacteriology. Consequently, I was assigned to work with Averill Liebow, a pathologist and one of my teachers at Yale, who had responsibility for the laboratory. Together, Liebow and I showed that the diphtheria bacillus caused tropical ulcers that were disabling our troops. This discovery led to effective treatment and prophylaxis.²

Our 1000-bed hospital filled up and emptied about once a week. About a third of the casualties were surgical, a third malaria, and a third psychiatric. For whatever reasons, two of our three psychiatrists chose to accept positions of advancement in the office of the hospital commander. This left Merrill Moore, a psychiatrist from Boston (and also a poet who had published a book of a thousand sonnets titled “M”), in an intolerable situation. When the searchlight circled for replacements it found my friend, David Crocker, and me. This was because when our hospital personnel were bivouacked 30 miles south of Auckland, we became restive in our bucolic surroundings and volunteered to help out at the naval station, whose temporary buildings were on the Auckland cricket field. There, every patient from Guadalcanal, in addition to having malaria and an enlarged liver, suffered from a psychoneurosis.³ So, overnight, because of that experience and a short tutelage by a Navy psychiatrist, I was taken by the scruff of the neck, lifted out of bacteriology, and put in charge of the psychotic ward. At the far end of the ward was a padded cell with a refrigerator-thick door, and a small, thick-glassed window for looking in on the patient. One of my first patients was a six-foot, four-inch Marine who, when not grimacing and playing with his toes, became alternately self-destructive or attacked others. Major Moore advised me to strip him of his clothes and place him in the padded cell. After three days he became so quiet and seemingly affable that, on rounds, I suggested to the nurse and the two corpsmen that I go in alone and talk with him. Everything seemed to be going well when suddenly I felt a tightening sensation around my neck and my head beginning to burst. The patient had taken each end of my tie and was choking me. Luckily, one of the corpsmen had stayed nearby, saw what was going on, and rushed in to save me. These experiences with patients suffering from psychiatric illness got me thinking again that the mind must be in the head, that it was just not an epiphenomenon.

Postwar Interim

The just-mentioned impression was clinched during a short period of the practice of medicine after the war. I was separated from the Army on New Year’s Day, 1946, at the Brooke General Hospital, San Antonio, Texas. Eyeing the future, I suggested to my wife, Alison, that we head for Seattle, which a friend at Yale had described as a “brave new world.” So as to avoid expensive rented office space, I initiated practice in the lower half of our house and also attended in the hospital outpatient clinic of the new medical school where my former teacher, Theodore Ruch, had been appointed head of the department of physiology. Owing to that connection, I was recruited to give the lectures on electrocardiography to the students comprising the first class at the school.

In my private practice I often found that after taking a complete history and doing a complete physical examination in the classical manner, I was unable to uncover anything except psychological symptoms and found it unconscionable to send such patients away with nothing but a sedative. At the same time, it was frustrating not to have any idea where in the brain these symptoms were generated. Consequently, I wrote Dr. Stanley Cobb at MGH in Boston, whose writing on psychosomatic illness had appealed to me, and inquired about the possibility of a fellowship for studying with him. It turned out that a U.S. Public Health Service fellowship would be available in September and I was invited to Boston for an interview. It was the most impressive and wisest interview I ever had. I did not know then that he had a notorious stammer and would not have guessed it until toward the end of the interview when there was every indication I could have the job. Dr. Cobb went on to say, “MacLean, I want you to know that if you come here, you can have the freedom to just sit on your . . . ah . . . ah . . . ah . . . ah.” He couldn’t get the word out. He leaned back in his chair, and continued to go on with his mouth wide open, saying, “ah . . . ah . . . ah . . . ah . . . ah” for what seemed an eternity. I knew of course what he wanted to say but did not help him. Finally, his head came forward and he explosively let out the one syllable word—adding, “and think.” Subsequently I learned from a friend that he hated to be helped and that my not doing so was probably a good thing.

The following August found us leaving Seattle and driving east to Boston with our young sons, Paul and David, and their baby brother, Alexander. On the way, we spent a reviving vacation in a rented cottage near my family’s summer place on Murray Isle in the Thousand Islands. Through a college friend, my wife had already found us an early 19th century house on Monument Street in Concord, Massachusetts, about a half mile beyond Old North Bridge where the first shot of the Revolutionary War was “heard ‘round the world.” Living in Concord made it an easy commute to North Station in Boston, where I would walk along a back street with markets to the MGH, often enjoying the company of the neuropathologist, Dr. Charles Kubik, who boarded the train at Lincoln.

At the MGH, 1947–1949

For my research I wanted to record the bioelectrical activity of structures at the base of the brain that possibly fed into the hypothalamus, which was known to be important for the expression of emotion. I therefore devised improved nasopharyngeal electrodes that could be slipped easily through each side of the nose and lie comfortably in the posterolateral part of the nasopharynx on each side. X rays showed the tips to be about 2 cm from the medial surface of the temporal lobe toward the rostral end of the hippocampus.

As I will explain, this proved to be a timely endeavor because of increased interest in a form of epilepsy that Gibbs and colleagues in 1938 called “psychomotor epilepsy.” This type of epilepsy commonly occurs without convulsions. During the aura at the beginning of an epileptic storm, the patient’s mind may light up with one or more of a wide range of emotions. Of great epistemological significance is that some patients experience an altered sense of self, or an exaggerated, free-floating feeling of what is real, true, and important. Afterwards, they engage in various forms of behavior for which they have absolutely no memory. In 1948, Gibbs and colleagues published a report indicating that, in most cases, the epileptic focus was in the anterior temporal region.

These landmark studies, combined with the localizing neurosurgical findings of Penfield and Jasper (1954) (see MacLean, 1990, pp. 419–420) led to the best evidence and, indeed, the only subjective evidence, that structures seemingly in the temporal lobe were involved in the elaboration and expression of emotional feelings.

The electroencephalography laboratory where I worked was headed by the well-known neurologist, Robert Schwab. It was close to Cobb’s department in the Ether Dome Building. There I was joined by A. Arellano, a research fellow from Lima, Peru. The opportunity arose to examine 12 patients with symptoms of psychomotor epilepsy, whose standard EEGs had shown neither a general nor localized disturbance. For this study Arellano devised an extra basal electrode that had a felt tip which, when wetted in saline, could be placed next to the tympanic membrane, about a half centimeter below the fusiform gyrus of the temporal lobe. Leads from the ear lobes served as two extra monitors of activity in the basal EEG. With simultaneous recording of the standard and basal EEGs, and using the sleep-activated method described by Gibbs and colleagues in 1948, we found in a majority of cases that spiking activity appeared and that the negative component reached greatest amplitude at the site of the left or right nasopharyngeal electrodes—the electrodes nearest the hippocampal formation, a supposedly rhinencephalic structure (MacLean and Arellano, 1950).

How would such an epileptogenic focus account for the emotional symptomatology of such patients, and more incomprehensible still, the symptoms involving the visual, auditory, or somatic sensory systems? In searching for an answer at the Boston Medical Library, I stumbled upon a paper by James W. Papez titled “A Proposed Mechanism of Emotion” in the 1937 volume of Archives of Neurology and Psychiatry and was immediately struck by its relevance to our findings. Taking into account what was then known about the role of the hypothalamus in emotional expression, Papez pointed out that the so-called rhinencephalon was the only part of the hemisphere known to be strongly connected with the hypothalamus. In citing case material to support his argument he summed up his view of the underlying mechanism as follows (Papez, 1937, p. 728):

The central emotive process of cortical origin may then be conceived as being built up in the hippocampal formation and as being transferred to the mammillary body and thence through the anterior thalamic nuclei to the cortex of the gyrus cinguli. The cortex of the cingular gyrus may be looked on as the receptive region for the experiencing of emotion as the result of impulses coming from the hypothalamic region, in the same way as the area striata is considered the receptive cortex for photic excitations coming from the retina.

The serially connected structures just mentioned have since become known as “the Papez circuit.”

But if the emotive process was originally built up in the hippocampal formation, it still left open the question of how emotions generated by exterosensory information got into these particular structures. When I went to Dr. Cobb with this question, he suggested I go to Cornell, where Papez taught, to ask the Odyssean navigator of the brain. A nice letter from Papez suggested that I come during the spring break of 1948, during which I was treated to a concentrated three-day course in comparative neuroanatomy. Papez seemed so dedicated and saintlike that I still have the feeling of remembering everything he said. In answer to my question about visual, auditory, and somatic inputs into the hippocampal formation, he showed me in a fixed human brain possible association pathways from the respective sensory areas.

Following my visit I began working on a paper titled, “Psychosomatic Disease and the ‘Visceral Brain.’ Recent Developments Bearing on the Papez Theory of Emotion.” I used the term “visceral brain” instead of rhinencephalon as a means of reducing the previous accent on olfactory functions. In its original 16th century meaning, visceral applied to strong inward feelings and implicitly to accompanying visceral manifestations.

The visceral brain paper was perhaps significant in introducing a few new ideas. First of all, it suggested that a phylogenetically old part of the brain occurring as a common denominator in all mammals might receive information from all the sensory systems. With respect to the hippocampus itself, this would indicate that “it was not an autonomous little factory of its own, manufacturing the raw materials of emotion out of thin air” (MacLean, 1990, p. 266). Figure 3 of that paper schematized the overlapping of interoceptive and exteroceptive systems in the hippocampal formation which, because of the analyzing mechanism of the evolutionarily primitive cortex, might account for the seemingly paradoxical overlapping of affective experience whereby primitive peoples and those with psychoneurotic and so-called psychosomatic conditions, appear to experience outside conditions as though they were happening inside.⁴ In terms of Freudian psychology, I suggested that the visceral brain is not at all “unconscious (perhaps not even in certain stages of sleep) but rather eludes the grasp of the intellect because its animalistic and primitive structure makes it impossible to communicate in verbal terms” (MacLean, 1949). In conclusion, I made the suggestion that, although our intellectual functions are mediated in the newest and most highly developed part of the brain, “our affective behaviour continues to be dominated by a relatively crude and primitive system. This situation provides a clue to understanding the difference between what we ‘feel’ and what we ‘know’” (MacLean, 1949, p. 351).

I presented my paper on the visceral brain at a staff meeting on January 11, 1949, and it was published in late 1949. In the meantime, my curiosity had developed a mounting interest in a whole series of anatomical and neurobehavioral questions raised in the paper that could only be answered in an experimental laboratory. The opportunity came when I received an invitation from my friend, John Fulton, professor and head of the department of physiology at Yale Medical School, with whom I had become wellacquainted while there as a student. I held a combined research–teaching appointment in physiology and psychiatry, starting at the rank of assistant professor in 1949 and then became associate professor in physiology in 1957.

Research at Yale, 1949–1956, and Development of the Limbic System Concept

Curiously enough, Papez in his 1937 paper does not even refer to Broca’s famous paper of 1878. It had become, so to speak, part of the public domain, and everyone was assumed to know about it. But it can hardly be overemphasized that from the standpoint of the evolution of mammals and their culmination thus far in human beings, it represents a historic milestone. Giving recognition to earlier descriptions of the same structure by Gerdy (1838) and Foville (1844), Broca drew attention to a large, cerebral convolution which he called the great limbic lobe because it surrounded the brainstem. It was Broca’s special contribution to identify the limbic lobe in a large variety of mammals and infer on that basis that it was a part of the brain common to all mammals. For function, Broca’s comparative findings led him to infer that the limbic lobe operated at an animalistic level (cerveau brutal), whereas the rest of the cortex subserved intelligence (cerveau intellectuel). Being impressed by the robust connections of the olfactory bulb with the forward part of the limbic lobe, Broca speculated that the entire limbic convolution was involved in olfactory functions. This notion gained wide appeal, and textbooks appeared in the 1890s referring to the entire limbic lobe as the rhinencephalon (MacLean, 1990, p. 263). Because olfaction was regarded as an unimportant sense in human beings, “the rhinencephalon was treated like an unwanted child” in the teaching of brain anatomy (MacLean, 1990, p. 263). As one author of a book on human evolution wrote, “[the rhinencephalon] probably has not contributed greatly to the evolution of the human brain and will, therefore, not be considered further” (MacLean, 1990, p. 263).

Although not known at the time of Broca’s paper, cytoarchitectural studies have since shown that the limbic lobe is enveloped by two concentric rings of cortex—the inner ring, usually referred to as archicortex and the outer ring, as mesocortex of M. Rose. As Rose points out, the mesocortex appears for the first time in mammals and is transitional in type between the archicortex and the outer evolving neocortex (MacLean, 1990, pp. 252–256).

When I joined the department of physiology at Yale in 1949, I became aware that the term visceral brain seemed to create misunderstanding because, in physiological parlance, the word visceral applies only to the glands and hollow organs, including the blood vessels. As a way around this, I found myself referring to the limbic cortex and its primary brainstem connections as the limbic system. Broca originally chose the word limbic because it is purely descriptive and implies no theory about function. At any rate, that is how the term limbic system was introduced into the literature in 1952 (MacLean, 1952, 1990, p. 267).

It is the expression “primary brainstem connections” that gives the cutting edge to Occam’s razor for defining the limbic system in a modular sense. Another reinforcement of the term is the interconnectivity within the limbic lobe itself. In addition, there are other illustrative reasons for the designation. First, nothing serves so well to illustrate that the limbic cortex and its primary brainstem connections constitute an anatomically and functionally integrated system than to map the propagation of neuronal after discharges induced in limbic structures by electrical stimulation (MacLean, 1990, Chapter 19). Time after time, one finds that the propagating nerve impulses stay within the confines of limbic circuitry. Parallel observations have been made during therapeutic neurosurgical procedures. Second, of biochemical distinctions, I found it of particular interest that our autoradiographic study on rats showed that, following the parenteral injection of ³⁵S-labeled L-methionine, there was a high uptake of the agent in both the archicortex and the mesocortex that distinguished the limbic cortex from the neocortex (MacLean, 1990, pp. 361–362). Third, as will be summarized later, both experimental and clinical findings provide evidence that the three main subdivisions of the limbic system derive information in terms of affective feelings that guide behavior required for self-preservation and preservation of the species.

The limbic system concept leads to the often overlooked recognition that the history of the evolution of the limbic system represents the history of the evolution of mammals and their distinctive family way of life.

Experimental Work

The first experiment on my agenda at Yale was a strychnine neuronographic study with Karl Pribram to learn whether or not there were association pathways from visual, auditory, and somatic cortical areas to the hippocampal gyrus, as Papez had suggested. The findings in cats and rhesus monkeys did provide evidence of such stepwise connections.

For neurobehavioral studies, I developed an electrode that could be chronically fixed for recording electrical activity while performing either electrical or chemical stimulation in freely moving cats. A long, semicircular viewing box with a clear plastic front allowed the behavioral responses to be recorded by motion picture while the subject was always in focus of a camera rotating on a central post. The leads to and from the subject traveled along a track above it, and moving panels along the back provided immediate access to the subject. The stage also permitted observations of the effects of brain stimulation on conditioned avoidance behavior. For chemical stimulation, we employed primarily cholinergic agents because, ostensibly, they avoid complication of excitation of fibers of passage (MacLean, 1990, p. 64). With different collaborators (MacLean, 1990, Chapter 19), I explored the amygdala and related cortex, the hippocampus, the cingulate gyrus, the hypothalamus, and other structures. I will summarize the main findings later when, after citing the work done at the National Institute of Mental Health (NIMH), I will consider the functions of the three main subdivisions of the limbic system.

A Sabbatical Followed by a National Institutes of Health Appointment

In 1956, in addition to my promotion to associate professor of physiology, I was given a year’s leave of absence for study in Europe made possible by the award of a National Science Foundation Senior Postdoctoral Fellowship. During that time I was affiliated with the Institute of Physiology at the University of Zurich. We rented a house in Thalwil, on the west bank of Lake Zurich, 11 miles south of the city. If I were to dwell on the wealth of experiences both I and my family enjoyed that year, there would be space here for little else.

When we sailed for Europe in 1956 the outlook at Yale was such that I thought I would be there the rest of my life. But in the spring of 1957, while in Zürich, I had an inviting letter from Robert B. Livingston, who had succeeded Seymour Kety after his highly successful launching of the intramural research program at the NIMH and the National Neurological Institute. With Wade Marshall, chief of the laboratory of neurophysiology, I had been invited to establish a new section in the Marshall Laboratory. The new section would be named The Section on Limbic Integration and Behavior.

I had shied away from previous opportunities to go to the National Institutes of Health because during World War II, I had grown wary of government-operated institutions. But the record of the NIH in the meantime had melted away all such concerns, and I would like to express my profound gratitude for the opportunity to do full-time research with such marvelous support.

The Marshall Laboratory was on the third floor of the Clinical Center in Bethesda, Maryland. Except for rabbits, animals larger than rats and mice had to be transported back and forth to a neighboring animal building. Since a main purpose of my research was to investigate how vision influenced limbic functions, I decided that I would no longer use cats, but rather employ a primate, such as the small South American squirrel monkey (Saimiri sciureus), with which I had had experience at Yale. Moreover, for obtaining a complete description of their behavior (a so-called ethogram), I hoped to recruit an ethologist.⁵ Also for that purpose, I wanted the animals to be housed across the hall from my office where records of observation could be made around the clock.⁶6 There was no administrative precedent for this and, moreover, fear was expressed that a monkey might escape and get on a patient corridor. But after devising a monkey escape control system, I was granted permission.

One of the main purposes of our section was to obtain electrophysiological and anatomical information about the connections of the limbic cortex with the various sensory systems. I was aware from experience that macroelectrodes would be unsatisfactory for this work because volume-conducted potentials generated in visual structures were manifest in the hippocampus. Moreover, anaesthesia was known to block nerve conduction in certain pathways. I therefore modified the system that I had used at Yale, whereby a light plastic stereotaxic platform could be permanently fixed above the scalp and provide a closed system for exploring the brain with metal or glass microelectrodes. The same device also provided exploration of the brain with stimulating electrodes in experiments where that was required (MacLean, 1990, pp. 333-336).⁷ For the microelectrode recording, it was a special advantage that the Marshall Laboratory possessed as much expertise and apparatus for recording bioelectrical activity as could be found anywhere.

One module of our section was set aside for purely anatomical work and the staining of serial sections of brains of experimental and control animals. John Gergen (a research associate) and I prepared a stereotaxic brain atlas based on serial sections of the brains of 30 squirrel monkeys (Gergen and MacLean, 1962).

The most complete review of the microelectrode findings on more than 14,000 units recorded while in the Marshall Laboratory and later at the Poolesville facility is to be found in Chapter 26 of The Triune Brain in Evolution (MacLean, 1990). In a word, we found that stimulation of all the exteroreceptive systems evoked unit responses in respective limbic areas of the fronto-insulo-temporal cortex and in the occipital, parasplenial, and posterior cingulate cortex. Surprisingly, the unit responses were modalityspecific. A finding of special interest was that photic stimulation evoked both phasic and sustained unit responses in the posterior hippocampal gyrus as well as unit spike potentials in the adjoining parasplenial limbic cortex and neocortical fusiform cortex. An anatomical study showed that when lesions were placed in the lateral geniculate body, degeneration could be traced in Meyer’s temporal loop into the posterior cortex of the hippocampal gyrus. The posterior parahippocampal cortex caudal to the rhinal fissure is a major source of hippocampal afferents. Phasic spike discharges were elicited in the hippocampus only by vagal and olfactory stimulation. These observations may be relevant to mechanisms involved in conditioning and memory.

Another major undertaking in our section was the investigation of brain structures and pathways involved in primal sexual functions. It is curious that little knowledge had existed about the representation of such pivotal functions above the level of the hypothalamus. The major findings and associated collaborators in these studies are summarized in Chapter 20 of The Triune Brain in Evolution (MacLean, 1990).

A Triune Concept of the Brain and Behavior

In February 1969, I gave the Clarence Hincks Memorial Lectures at Queens University, Kingston, Ontario. In keeping with the overall theme of the three lectures—The Brain and Behavior—I explained that the human forebrain evolved to its great size while retaining features of three basic formations that reflect an ancestral relationship to reptiles, early mammals, and recent mammals. The three neural assemblies, I pointed out, are radically different in structure and chemistry, and in an evolutionary sense, countless generations apart. Based on these features alone, I said, it might be surmised that psychological and behavioral functions depend on the interplay of three quite different mentalities. The three evolutionary formations might be popularly regarded as three interconnected biological computers, each having its own special intelligence, its own subjectivity, its own sense of time and space, and its own memory, motor, and other functions.

What I did not realize until afterward was that if you speak publicly in Canada, the communication ties within the British Commonwealth are such that there may be a period when the sun will never set on what you say. The underlying theme of my lectures—the three-brain concept—gained rather wide circulation, but in the abbreviated reports, one got the impression that we behaved as though under the direction of three separate brains. I realized that what I needed was a word so definably tight that there could be no possible confusion on that score. Despite its other connotations, I liked the word “triune” because its letter-by-letter spelling was so close to the Greek term meaning, literally, three-in-one. If the three main evolutionary assemblies were pictured as intermeshing and functioning together as a triune brain, they could hardly be completely autonomous, but would be able to operate somewhat independently. Moreover, the word triune also implies that the whole is greater than the sum of its parts because, with the exchange of information among the three main assemblies, each derives a greater amount of information than if it were acting alone. Consequently, I explained in the published version why I changed the title to “A Triune Concept of the Brain and Behavior.”

The Laboratory of Brain Evolution and Behavior

Bob Livingston, director of the Intramural Research Program, and I had frequently discussed the advantages of having a satellite field laboratory for conducting certain neurobehavioral studies. The reasons for having such a facility were many, but the main thrust of the argument may be found in the writings of C. Judson Herrick, who said in effect, that there is no experiment that Nature has not done for us.⁸ In my entry titled “Triune Brain” in the Encyclopedia of Neuroscience (1987), I cited some of the advantages of the comparative, evolutionary approach at both the molecular and macroscopic levels.

In 1959, Livingston learned of the NIH plan to obtain a 1000-acre farm to support the clinical and research needs of the Clinical Center. Mindful of our foregoing discussions, he applied for and obtained a sector of 30 acres for a field laboratory. Economic considerations required the purchase of a farm 30 miles from the Clinical Center, near the Potomac River, 7 miles south of Poolesville, Maryland. Because our facility was part of the overall plan for the farm, including the architecture, the laboratory was not ready for occupancy until May 1971. In the meantime, John E. Eberhart, who had succeeded Livingston as director of the NIMH Intramural Research Program, and who shared a like enthusiasm for the facility, thoughtfully asked me to be with him every time there was a meeting with the architects.

Goals and Outcome of Research at Poolesville

The Poolesville facility was built to serve as another means of broadening the evolutionary approach in finding the roots of human subjective experience and behavior. Evidence continues to accumulate that in all animals there are molecular commonalities that apply to genetic coding and enzymatic reactions that carry over to complex cellular assemblies. “Nowhere is the uniformity of complex cellular assemblies more striking than in the cerebral evolution of vertebrates both as it applies to similarities within classes and to certain commonalities across classes” (MacLean, 1987, p. 1235).

We intended to focus on the anatomy and functions of cerebral commonalities of animals belonging to the three classes of terrestrial vertebrates: reptiles, birds, and mammals. All land vertebrates derive from the stem reptiles. Continuing fossil discoveries are adding to the evidence that birds evolved from dinosaurs. The fossil record, on the contrary, provides numerous examples linking the lineage of human beings and other mammals to the mammal-like reptiles (therapsids) that lived in Permian times, some 250 million years ago when there was but one giant continent known as Pangaea. Providing a remarkable illustration of directional evolution, several lines of the therapsids were approaching the mammalian condition so that finally the most reliable distinction was the retention in the jaw joint of two small bones which, in mammals, migrate and become the malleus and incus of the middle ear.

There are no living reptiles directly in line with mammals, but one of the primitive therapsids had an auditory apparatus and skeleton so similar to lizards that paleontologists gave it the name Varanosaurus, after the Varanus (monitor) lizard, of which the Komodo dragon is an example. Therefore, I decided to use lizards in our comparative neurobehavioral studies. If one does a behavioral analysis (ethogram) of the three classes of land vertebrates, one finds about 25 forms of behavior common to all three (MacLean, 1990, p. 100). In one category are behaviors that comprise their daily master routine and subroutines. In the other category are displays used in social communication. In all three classes, the displays can be grouped into four main types—greeting displays, aggressive displays, courtship displays, and submissive displays.

Given the list of the basic forms of behavior in the three classes of land vertebrates, what brain structures might account for the shared similarities? Classical experiments had shown that the neural chassis in the lower brainstem and spinal cord was somewhat comparable to a vehicle without a driver (MacLean, 1990, Chapter 3). This would indicate that structures responsible for directive behavior must be looked for in the forebrain. Given the small representation and archicortical resemblance of the cortex in reptiles and birds, the most likely place to look for the driver was those parts of the basal ganglia having both an anatomical and chemical resemblance to those in mammals. These comprise the so-called striatal complex and include the olfactostriatum (olfactory tubercle and nucleus accumbens), corpus striatum (caudate nucleus and putamen), globus pallidus, and satellite collection of gray matter (MacLean, 1990, pp. 37–43). In a comparative context, I refer to them as the R-complex. Clinically, they have been regarded as part of the motor apparatus under the control of the motor neocortex, having, so to speak, no mind of their own.

Years before in Boston, on one of our walks from North Station to the MGH, I asked Charles Kubik, “Charlie, what do the basal ganglia do?” Because he had seen so many cases with large cavities in the corpus striatum without a history of motor symptoms, he jokingly replied, “Hunh, they don’t do nuttin’: They just hold up the rest of the brain.”

Experimental Findings on Display Behavior

Squirrel Monkeys. In 1964 I described two varieties of squirrel monkeys, one of which would consistently display to its reflection in a mirror, whereas the other showed little or no interest in its reflection. I referred to the mirror-displaying monkey as the gothic type because the ocular patch formed a peak over the eye like a gothic arch, while the other variety was called roman because the arch was rounded like a roman arch (see MacLean, 1990, pp. 172–173, for facial, vocal, and karyotypic differences). The main features of the gothic-type mirror display comprise vocalization, spreading of the thigh, and full penile erection. In year-round testing of 105 monkeys, these manifestations were shown to occur 82% of the time in sets of 30 trials. Systematic observations of the effects of brain lesions of various neocortical, limbic, and striatal structures were made on more than 115 monkeys (MacLean, 1990, Chapters 13 and 14).

The main outcome of the study showed that the rostromedial part of the globus pallidus (MacLean, 1978) is a site of convergence of neural systems involved in the species-typical expression of the mirror display. Since the same features of the display occur in both aggression and courtship, the findings would imply that the same cerebral structures are also implicated in these displays.

Lizards. With Neil Greenberg, we studied the effects of forebrain lesions on the challenge display of the green Anolis lizard (MacLean, 1990, p. 153). In this kind of an experiment, it is essential not to interfere with thermoregulation. Since the optic nerves of the lizard are almost completely crossed, it is possible to place a lesion in only one side of the brain and then test the lizard’s behavior with either of its eyes covered when it looks at a rival male lizard living side-by-side in a like vivarium with a removable screen in between. Serial brain sections showed that only the lizards with lesions of the R-complex failed to display when looking with the eye projecting to the injured hemisphere. Lesions elsewhere, including the dorsal ventricular ridge, were ineffective.

Routines. There seems to be a tendency not to think about the complicated kind of neural apparatus required to maintain a daily master routine, and at the same time brook the interruptions of emergencies and other factors that precipitate a variety of subroutines. The master routine of lizards is quite similar for various species, including (1) cautious morning emergence; (2) basking; (3) defecation; (4) drinking; (5) morning hunting within territory; (6) period of inactivity; (7) afternoon hunting farther afield; (8) late afternoon basking near shelter; and (9) retirement to roost.

We never completed a neurobehavioral study on how different cerebral lesions affected the daily master routine in mammals. However, with Michael Murphy, a research associate, we found that neonatal hamsters that were completely deprived of neocortex but with an intact limbic system and striatal complex developed normally and manifested all forms of hamster-typical behavior along with the usual daily master routine.

In my study of the effects of pallidal lesions on the mirror display of squirrel monkeys, I reported that each monkey had a subroutine for approaching a mirror during the control preoperative period. Although not displaying after surgery, the former preoperative manner of looking into the mirror was altered.

Perhaps the most telling observations on the probable role of the basal ganglia in affecting the daily master routine and subroutines derived from clinical case reports. Caine and colleagues (MacLean, 1990, p. 220) observed a group of 18 patients at the NIH Clinical Center with a diagnosis of Huntington’s disease, which primarily affects the corpus striatum. Although the authors do not mention the word routine, what they actually described as one of the earliest symptoms of the illness was an inability to initiate and carry out a daily master routine. In some cases, long-accustomed subroutines were also affected. A dentist, for example, was no longer able to perform the familiar step-by-step sequence of filling a tooth.

Patients with Sydenham’s chorea, often attributed to an irritative condition of the corpus striatum, may spend their days, as reported so vividly by Osler (MacLean, 1990, p. 221), engaged in repeated performance of bizarre subroutines that allowed them little time for an orderly, daily master routine.

In summary, there are indications that the R-complex orchestrates the performance of displays used in social communication. Moreover, one obtains pieces of evidence from experimental and clinical findings that the R-complex provides an intelligence for linking together the requisite behavior of the daily master routine, as well as those of subroutines.

The Limbic System: Summary of Earlier and Continuing Research

It cannot be overemphasized that “psychomotor epilepsy” provides the best evidence (and the only self-descriptive, subjective evidence) that limbic structures are basically involved in the generation and expression of emotional feelings. I will therefore introduce this summary with a brief classification of emotional feelings referred to as affects, as opposed to their outward expression for which Descartes’ word emotion is appropriate. At Yale, just as at the MGH, I continued to see patients with psychomotor epilepsy or who were candidates for electro-encephalographic diagnosis. This background, together with my reading of numerous case histories, led me to develop a workable classification of the affects, described in four chapters on the phenomenology of psychomotor epilepsy in The Triune Brain in Evolution (MacLean, 1990, Chapters 22–25).

It is the element of subjective awareness that distinguishes psychological from other functions of the brain, the most common of which are sensations, perceptions, drives, emotional feelings, and thoughts. Under usual conditions, sensations and perceptions depend on the immediate excitation of receptors. Through different processes of mentation, however, drives, emotional feelings, and thoughts may recur and persist after the inciting incidents. Subjectively, the affects may be characterized as either agreeable or disagreeable. By definition, there are no neutral affects. The affects can be divided into three kinds—basic, specific, and general. The so-called basic affects are associated with basic bodily needs such as thirst for water, hunger for food, the need to expel, and so on. The specific affects are feelings associated with specific sensory systems and thereby also include the cultural affects. The general affects correspond to what we usually describe as emotional feelings, and are so named because they may be activated by things, situations, or individuals. There are six main kinds of general affects characterized, respectively, by feelings of desire, anger, fear, dejection, joy, and affection. During the aura at the beginning of a limbic epileptic storm, a patient’s mind may light up with typical feelings that, in one case or another, cover the entire range of basic, specific, and general affects.

Functions of the Three Main Limbic Subdivisions. Based on a review of experimental and clinical findings, including the growing amount of information from anatomical, electrophysiological, and neurochemical studies, I had suggested that the limbic system could, operationally speaking, be divided into three main subdivisions, all of which derived information in terms of affective feelings that guide behavior required for self-preservation and the preservation of the species. Phylogenetically, the two oldest divisions include limbic cortical areas reciprocally connected with two telencephalic nuclei, the amygdala and the septal nuclei, which are closely associated with the olfactory apparatus. Experimental and clinical findings have revealed that cortical and subcortical structures most closely associated with the amygdala are involved in experience and behavior, and are primarily concerned with self-preservation as it relates to feeding, the search for food, and the fighting and defense that may be required in obtaining food. The septal division, on the contrary, appears to promote survival of the species as evidenced by its involvement in primal sexual functions and manifestations conducive to sociability, courtship, and reproduction.

The newest subdivision, of which there is no clear counterpart in the reptilian brain, and which culminates in the human brain, is referred to as the thalamocingulate division because of the preponderance of its cingulate cortical connections with the anterior and midline thalamic nuclei. In contrast to the two just-mentioned divisions, some workers would argue that it has nothing to do with emotional behavior. Recent experimental findings point to the unlikelihood of such a negative statement. In the evolutionary transition from therapsids to mammals, three forms of behavior appear to have developed that most clearly distinguish mammals from other vertebrates. This cardinal family related triad comprises: (1) nursing, conjoined with maternal care; (2) audiovocal communication for maintaining mother–offspring contact; and (3) play behavior.

Nursing and Maternal Care. The important role of the cingulate cortex in maternal behavior, including nest-building, nursing, and pup retrieval, has been known since the important publication on this subject by Stamm in 1954. His findings in rats were subsequently confirmed and extended by Slotnick, who also showed the importance of cingulate function in paternal behavior (MacLean, 1990, pp. 388–395). With Michael Murphy, who had developed an extensive ethogram on feral hamsters, we observed similar maternal deficits in another type of experiment involving cingulate ablations in neonatal hamsters which had grown to maturity.

Audiovocal Communication. In my studies of the functions ofpallidotegmental pathways, I noted that squirrel monkeys with certain lesions developed abnormal kinds of vocalization and, occasionally, did not vocalize at all. I discussed this with John Newman, of the Child Health Laboratory of Comparative Ethology, who was particularly interested in the vocalization of primates, and the separation cry in particular. The separation cry possibly ranks as the most basic mammalian vocalization. A preliminary analysis of the spectrograms of monkeys that had been operated on showed harmonic evidence of the infantile nature of the cry or other abnormalities. We then undertook a study to attempt to narrow down the tegmental structures involved in such changes (MacLean, 1990, pp. 402–403). After that, the next step was to test the effects of ablating parts of the medial frontal cortex containing the anterior cingulate cortex because of the long-known importance of the latter in primate vocalization. We found that ablation of a strip of pregenual cingulate cortex with its continuation in the subcallosal cingulate cortex resulted in an enduring elimination of the spontaneous production of the separation cry (MacLean, 1990, pp. 403–410).

Play Behavior. Our observations on the developmental behavior of neonatal hamsters deprived of the entire neocortex revealed that they matured normally and acquired all forms of hamster-typical behavior. What was surprising and of great interest was that, if in addition the cingulate cortex had been destroyed in either males or females, they failed to develop playful behavior expected around the 13th day, or at any time thereafter.

Significance of the Family-Related Behavioral Triad

Here it is enough to say that there are numerous situations that, for both people and mammals generally, make separation painful. In this respect it is of interest that the part of the cingulate cortex involved in the production of the separation cry receives some of its innervation from thalamic nuclei involved in the perception of pain (MacLean, 1990, p. 541). Of further relevance is the high content of opioid receptors in the cingulate cortex, and that morphine, in all varieties of mammals to which it has been given, eliminates the separation cry. I have suggested that the origin of the cry is perhaps evolutionarily traceable to the times of beginning nursing and the fatal consequences that would ensue if the young were separated from a nursing mother.

In speaking of play, I have noted that few people, even experts in animal behavior, seem to be aware that mammals are the only vertebrates that engage in indisputable play. In this regard, I have suggested that play may have originated as a means of promoting harmony in the nest and, later, sociability and muscle-building for the strategies of survival. There is no need here to elaborate on all the ways that play enters into the imaginative and creative aspects of the arts, literature, and science.

These considerations of separation and crying also bring up the question of the neural substrate of laughing and crying which have long remained a mystery. The results of the foregoing studies suggest that it would be worthwhile to review cases of psychomotor epilepsy in which there were manifestations of either or both laughing and crying. The findings are too extensive to be reviewed here, as are the many implications. In one sentence, the location of irritable foci involve nuclei and cortical structures along the course of Papez’s circuit that suggest opportunity for reciprocal innervation of laughing and crying.

An interesting question arises here about the specific nature of tearing in human beings. It is said that all mammals are subject to tearing when exposed to irritating conditions such as smoke. However, it is claimed that human beings are the only creatures in which tearing is induced by emotional feelings. Human beings are also the only creatures to discover the use of fire for a variety of purposes such as cooking food, making tools, and the like. Evidence of the hominid use of fire can be found as early as 1.4 million years ago. Briefly, I have suggested that the tearing associated with grief may have been conditioned by the irritation of smoke when burning the remains of loved ones (MacLean, 1990, pp. 556–558). The tears of laughter, on the contrary, might have been conditioned by amusing forms of communication occurring during cooking or relaxation around a fire or in a cave (MacLean, 1990, p. 558).

The Meaning of Life in Regard to the Limits of Knowledge

Sense of Being (Ontology) and Memory

On the basis of introspection alone, one might infer that sense of self and reality depends on an integration of internally and externally derived experience. Whereas the neocortex receives most of its information from the outside world via the visual, auditory, and somatic pathways, the limbic system not only is closely tuned to the internal environment, but also, as previously emphasized in our experimental studies, receives information from all the exteroceptive senses. Hence, it could be argued that a sense of self depends on an integration of limbic and neocortical systems.

Such a concept would seem to be borne out by manifestations of psychomotor epilepsy. Following the aura, patients may engage in automatisms that range in individual cases from simple to very complex forms of behavior for which they have absolutely no memory. The complex automatisms can involve skilled, cognitive functions, as illustrated by a physician who correctly diagnosed and treated a patient, and an obstetrician who performed a breech delivery. At autopsy, a former physician (Hughlings Jackson’s famous Case Z) was found to have a small cyst involving the region of junction of the amygdala and hippocampus (MacLean, 1990, pp. 563-564). As noted earlier, limbic seizures tend to spread within and be confined to structures of the limbic system. Evidence exists that the onset of the automatism coincides with a bilateral spread to limbic structures necessary for a sense of self-identity. Without a sense of self, there is, so to speak, no place to deposit a memory of ongoing experience (anterograde amnesia). The same argument could be made in cases of anterograde amnesia associated with destructive lesions of the hippocampus and certain other limbic structures.

The Matter of Belief

Finally, it is of profound epistemic significance in regard to human belief that the symptomatology of psychomotor epilepsy suggests that the limbic cortex generates free-floating, affective feelings conveying a sense of what is real, true, and important. The same applies to feelings of discoveries (eureka-type feelings) that would compare to the nonepileptic, “this is it” revelation, such as what Kepler experienced upon his wrongful conception of “the five perfectly fitting solids” (MacLean, 1990, p. 578).

There is evidence that limbic cortical structures by themselves are incapable of verbal communication. On the other hand, evidence just reviewed suggests that without a cofunctioning limbic system, the neocortex lacks not only the requisite neural substrate for a sense of self, of reality, and the memory of ongoing experience, but also a feeling of conviction as to what is true or false. It would therefore seem that we are left in an intellectually shaky position. It is one thing to have an illiterate brain for judging the authenticity of food or a mate, but where do we stand if we must depend on this same mind for belief in our ideas, concepts, and theories? (MacLean, 1990, p. 453).

Even with a normally functioning brain, the neocortex is incapable of dealing with one problem that brings us right up to the limits of knowledge. This is because the logical functions that we attribute to the neocortex are such that no logical system of any complexity can be cleared of contradiction. This situation, as proved arithmetically by Godel, is owing to the axiomatic need of self-reference. As Bronowski commented, self-reference “creates an endless regress, an infinite hall of mirrors of self-reflection” (MacLean, 1990, p. 571). To this might be added that, because the subjective brain is solely reliant on the derivation of immaterial information, it could never establish an immutable yardstick of its own; it must forever deal with a nondimensional space and a nondimensional time for which it establishes its own arbitrary standards of measurement.

One might hope that further developments in quantum mechanics clarifying the interplay of the wave and quantum might lead to some further surety of knowledge. But here again the viscoelastic properties of the brain make its calculations so incommensurably slow and crude as to make many of the questions of quantum physics incomprehensible. Nevertheless, it adds intellectual interest to deal with such questions. For example, in a recent paper of mine dealing with the brain and the derivation of subjective experience, it gave appetite to my thinking by raising the question of the role of certain proteins and their being affected by resonance at the molecular, submolecular, and atomic levels (MacLean, 1997).

The Meaning of Life

The Four Horsemen of the Apocalypse (conquest, war, famine, and death) have always been with us, but since the onrush of worldwide communication, they have never seemed to be riding in so many places at once. Psychic anguish, starvation, horrendous kinds of killing, and war keep appearing everywhere. To this must be added the untold suffering of countless animals as, for example, the tons of fish dragged up on deck every day to die a slow, suffocating death. These are thoughts to temper anyone’s attempt to understand the meaning of life. And I must admit, in the last few years it has tempered my once lively curiosity about the meaning of life. In discussion now with people about this question, my phrasing has acquired a negative slant. Why, I ask, with all the suffering in this world-human suffering, animal suffering—would anyone want to create life, and perpetuate life, here or elsewhere in the Universe?

When, as usual, there are no persuasive answers, I call attention to what has been for me a comforting observation. The development of the prefrontal cortex in human beings has been shown to be involved in anticipation and planning, as well as with empathic and altruistic feelings. The prefrontal cortex is closely tied in with the limbic cingulate cortex which, as noted above, has been found in animals to be involved in parental behavior, the separation cry, and play. As I have suggested elsewhere, the evolution of prefrontal connections with the limbic “parental” cortex would make it possible for a concern for the future welfare of the immediate family to generalize to other members of the species, a psychological development that amounts to an evolution from a sense of responsibility to what we call conscience. What does it tell us about the meaning of life when we can now say that for the first time in the known history of biology, we are witnessing the evolution of human beings with a concern not only for the suffering and dying of their own kind, but also for the suffering and dying of all living things?

Acknowledgments

In 1993, I decided to satisfy my desire to return primarily to the study of the human brain. Most needed, I thought, was a three-dimensional picture of the cortical and subcortical neural circuitry with which the viscoelastic brain derives its own species of algorithms (i.e., solutions) accounting for everything we do. Such reasoning led me to ask to be assigned to the NIMH Neuroscience Center at St. Elizabeths, where I hoped a start could be made for a multipurpose national brain facility for perfecting the methods by which we study the anatomical and chemical connectivity of the brain. Unfortunately, the introduction of the marvelous technique of brain imaging has led to the wrongful impression that it will replace classical methods. However, if we rely mainly on imaging techniques, we shall be a little like those in Plato’s cave trying to obtain information from changing light and shadows. At the proposed facility on the beautiful St. Elizabeths campus overlooking nearby Washington, one could foresee the formation of a museum-quality collection of brains with excellent histories that would be representative of diverse human diseases and of different genetic stock.

I am most grateful to our NIHM and NIH administrations for expediting approval of my request. I owe special thanks to Chief Daniel R. Weinberger, M.D., and Deputy Chief Joel Kleinman, M.D., for their friendly welcome into the Clinical Brain Disorders Branch.

Relevant to our research on mammal-like reptiles (therapsids) and lizards at the Poolesville Lab, I want to thank colleagues at the Smithsonian Institution for their cooperation in organizing two public conferences (see Hotton et al., 1986 and Greenberg and MacLean, 1978). For the present manuscript, I had the good luck to enlist Ioline D. Henter, M.A., for both typing and editorial discussion.

Selected Bibliography

Bernstein J. Quantum profiles. Princeton, NJ: Princeton University Press, 1991.

Broca P. Anatomie comparée des circonvolutions cérébrales. Le grand lobe limbique et la scissure limbique dans la série des mammifères. Rev Anthropol 1878;1:385–498.

Gergen JA, MacLean PD. A stereotaxic atlas of the squirrel monkey’s brain (Saimiri sciureus). Washington, DC: U.S. Government Printing Office, 1962. [PHS Publication 933]

Greenberg N, MacLean PD, eds. The behavior and neurology of lizards. Washington, DC: U.S. Government Printing Office, 1978. [DHEW Publication (ADM) 77–491]

Hotton III N, MacLean PD, Roth JJ, Roth EC, eds. The ecology and biology of mammal-like reptiles. Washington, DC: Smithsonian Institution Press, 1986.

MacLean PD. Psychosomatic disease and the “visceral brain.” Recent developments bearing on the Papez theory of emotion. Psychosom Med 1949;11:338–353.

MacLean PD. Some psychiatric implications of physiological studies on the frontotemporal portion oflimbic system (visceral brain). Electroencephalogr Clin Neurophysiol 1952;4:407–418.

MacLean PD. The triune brain, emotion, and scientific bias. In: FO Schmitt, ed. The neurosciences: Second study program. New York: The Rockefeller University Press, 1970;336–349.

MacLean PD. A triune concept of the brain and behavior. Lecture I: Man’s Reptilian and Limbic Inheritance; Lecture II: Man’s limbic brain and the psychoses; Lecture III: New trends in man’s evolution. In: Boag T, Campbell D, eds. The hincks memorial lectures. Toronto: University of Toronto Press, 1973;6–66.

MacLean PD. On the evolution of three mentalities. Man Envir Sys 1975;5:213–224.

MacLean PD. Effects of lesions of globus pallidus on species-typical display behavior of squirrel monkeys. Brain Res 1978;149:175–196.

MacLean PD.Triune brain. In: Adelman G, ed. Encyclopedia of neuroscience. Cambridge, MA: Birkhauser Boston, 1987;1235–1237.

MacLean PD, ed. The triune brain in evolution: Role in paleocerebral functions. New York: Plenum, 1990.

MacLean PD. Neofrontocerebellar evolution in regard to computation and prediction: Some fractal aspects of microgenesis. In: Hanlon RE, ed. Cognitive microgenesis: A neuropsychological perspective. New York: Springer-Verlag, 1991;3–31.

MacLean PD. Limbic system. In: Beaumont JG, Kenealy PA, Rogers JC, eds. The Blackwell dictionary of neuropsychology. Oxford: Basil Blackwell, 1996.

MacLean PD. Women: A more balanced brain? Zygon J Religion Sci 1996;31: 421–439.

MacLean PD. The brain and subjective experience: Question of multilevel role of resonance. In: Vandervert L, ed. Nonlinear dynamics (including chaos) and quantum theory (perspectives on consciousness) in psychology. J Mind Behav 1997;18:247–268.

MacLean PD, Arellano AP. Basal lead studies in epileptic automatisms. Electroencephalogr Clin Neurophysiol 1950;2:l–16.

Papez JW. A proposed mechanism of emotion. Arch Neurol Psychiat 1937;38: 725–743.

Ramón y Cajal S. Charlas de Café, ninth edition. Madrid, Spain: Espasa-Calpe, SA, 1966.

Vandervert LR. Systems thinking and a proposal for a neurological positivism. Sys Res 1988;5:313–321.

Wiener N. Cybernetics, or control and communication in the animal and the machine. New York: Wiley, 1948.

¹I am grateful to Miguel Marin-Padilla for this difficult-to-obtain reference.

²I had read that garage mechanics did not get infections on their hands because of the antibacterial effect of pyocyanase from the bacillus Pseudomonas aeruginosa living in a tarry environment. Hence, I grew this organism in an appropriate broth until it acquired the typical bluish color of the bacteria’s secretions. The broth was filtered, concentrated, and mixed into a salve. Amazingly, when applied to tropical ulcers, they healed rapidly. Not long after a Grand Rounds reporting its effectiveness, I was put out of business by the availability of penicillin.

³Every time a little airplane would fly over, a whole ward of patients would “hit the deck” and crawl under the bed. When I got down on my hands and knees to reassure one of them, I discovered fruit jars containing things such as cut off ears and gold teeth under the head of almost every bed.

⁴For example, I examined a patient in the Hopkins accident room who came in complaining of cats and dogs fighting in his stomach. When I placed my stethoscope on his abdomen during the examination, he said, “Can you hear them, Doc?”

⁵In the 1950s the European enthusiasm for ethology had hardly reached our shores. Through Richard Jung, the well-known German electrophysiologist, I was introduced to Detlev Ploog, who had spent a year in Jung’s laboratory and, in addition, had a special interest in ethology. Arrangements were made for him to join our section as a visiting scientist. During the 2-year period (1958–1960) that he was with us, he collaborated with me in electrophysiological studies, and together we also obtained a well-defined ethological picture of the behavior of squirrel monkeys as the behavior occurs in captivity.

⁶In running the animal quarters opposite from my office, it was kept foremost in mind that in neurobehavioral studies the health, care, and surroundings of the animals are of utmost importance. Most important, it was necessary to have a full-time animal caretaker with a kindly disposition that the animals learned almost immediately to recognize. We made rounds at scheduled times and in following the health of the monkeys, weighed them weekly, and inspected them closely. Special cages were made to satisfy their needs for exercising and for viewing everything that was going on. An extra large, two-story cage with four accessible compartments was constructed for observation of four or five monkeys living together.

⁷See these pages also in regard to humane experimental conditions.

⁸In correspondence about this matter, Herrick could cite no particular aphoristic statement to this effect.

Brenda Milner

BORN:

Manchester, England

July 15, 1918

EDUCATION:

University of Cambridge, B.A. (1939)

University of Cambridge, M.A. (1949)

McGill University, Ph.D. (1952)

University of Cambridge, Sc.D. (1972)

APPOINTMENTS:

Université de Montréal (1944)

McGill University (1952)

HONORS AND AWARDS: (SELECTED):

Distinguished Scientific Contribution Award, American Psychological Association (1973)

Fellow, Royal Society of Canada (1976)

Foreign Associate, National Academy of Sciences U.S.A. (1976)

Fellow, Royal Society of London (1979)

Karl Spencer Lashley Award, American Philosophical Society (1979)

Ralph W. Gerard Prize, Society for Neuroscience (1987)

Fellow, Society of Experimental Psychologists, U.S.A. (1988)

William James Fellow, American Psychological Society (1989)

Canadian Medical Hall of Fame (1997)

Brenda Milner first described patient H.M., thereby discovering the memory functions of the medial temporal lobe. She has carried out pioneering neuropsychological work on the topics of memory, hemispheric specialization, and the functions of the frontal lobes.

Brenda Milner

Background (1918–1939)

There was nothing in my background to predict a career in the sciences. I was born in Manchester, England in July, 1918, the only child of Samuel Langford, musical critic on the Manchester Guardian, and

Leslie Doig. My father came from a family of market gardeners, but it has been said that he had a romantic rather than a business interest in gardening. I grew up in an old house surrounded by a large, overgrown garden, where my father grew delphiniums for the sake of their color rather than their market value.

As a young man, my father had played the organ in the local parish church, and it was there that his musical talent was spotted; a scholarship fund was raised to send him to study music under Carl Reinecke in Leipzig, where he stayed for 4 years, returning to England in 1900 to earn his living as a professional journalist, music teacher, and occasional concert pianist. Apart from his musical training, he was largely self-educated and expressed distrust of formal education as inhibiting the creative spirit. His wide-ranging library of prose and poetry made me a precocious reader but contained no scientific writing.

My mother, who was 23 years younger than my father, came from a broken home; as a result she had had to leave her high school in Birmingham at the age of 14 and as a young woman take a clerical job in Manchester, where she stayed with family friends. While in Manchester, she took singing lessons from my father, and subsequently married him, much to the surprise of his family who had thought of him as a confirmed bachelor.

Their life together was dominated by music, and it was a bitter disappointment to them to discover that I had absolutely no musical aptitude, and, in fact that I was practically tone deaf. Once this had been accepted, my childhood became much happier. Since my father was at home during the day, he took charge of my early education, which included arithmetic, a great deal of Shakespeare, and even a little German. At the age of seven, I began to attend a small private primary school, where we had to speak French on all social occasions (a foretaste of things to come), and where I struggled to improve my handwriting, which, like other motor skills, lagged far behind my reading ability.

When I was 8 years old, my father died of tuberculosis, after a relatively short illness, and my whole life changed. My mother secured a place for me at Withington Girls’ School, where I remained for the next 10 years, and we moved to a more modern house nearby.

One incident stands out from my early years at Withington. Thanks to my father’s teaching, I found myself far in advance of my class in several core subjects, so that my mother asked if I could skip a class. The school agreed but warned her that I would be behind in French as a result. My mother took this as a challenge and taught me French grammar solidly all summer, so that when I returned to school in the fall I found that I knew enough French for the next 3 years. This excellent groundwork led me to develop a great love of French language and literature, which was to stand me in good stead when I came to live and work in Montreal, many years later.

The British school system then (and probably even now) requires specialization quite early, so that by the age of 15 I had to choose between science and the humanities. It was a difficult choice, but with my love of Latin I would have opted for classics (and a totally different life), had my school offered Greek. Since it did not, I chose to study mathematics and physics, on the science side. This was partly because I greatly enjoyed my high school mathematics, but also because I believed (and still do) that it is possible to develop one’s knowledge and enjoyment of foreign languages and literature on one’s own, but that once you give up science you abandon it forever. My headmistress was angered by my choice because she thought, quite rightly, that this would make it more difficult for me to get a scholarship to Oxford or Cambridge (but my mother, to her everlasting credit, supported me, although she herself would have preferred me to opt for the humanities). I had certainly gambled on my future, but thanks to an excellent physics teacher, I managed to get into Newnham College, Cambridge in 1936 and supported myself there on a Manchester City Scholarship, supplemented by a small grant from my college.

I had not been long at Cambridge before I realized that I would never distinguish myself in mathematics. Therefore, at the end of my first year, I decided to change fields. I was, however, still attracted by the elegance of mathematical reasoning and toyed with the idea of switching to logic and philosophy, in the Moral Sciences Tripos. But I was soon dissuaded from such a plan, as senior members of my college pointed out to me that nobody could earn their living in philosophy, and hence that it was a subject strictly for people of independent means. Instead, they suggested that I might consider psychology, which in those days was still classed as a moral science. F. C. Bartlett, already famous for his research in memory, was the professor, and his wife was Director of Studies in psychology at Newnham. She proved quite welcoming and gave me Murcheson’s encyclopedic Handbook of Experimental Psychology for summer reading to prepare myself for this new field.

As I had feared, my mother was extremely disappointed by my news. Although she had originally hoped that I would have a career in the humanities, she had a great respect for mathematics and therefore had reconciled herself to my choice. Psychology was another matter, for outside the universities this discipline was still relatively unknown in England.

For me, however, experimental psychology proved a fortunate choice, providing a friendly laboratory environment and the tools with which to satisfy my growing curiosity about the behavior of organisms. Under Bartlett’s leadership, the Cambridge department had acquired a strongly biological orientation, stemming from the tradition of Sir Henry Head. We also shared a building with Professor E. C. Adrian’s Physiological Laboratory, where I had the privilege of hearing Carl Pfaffmann present his early work on taste in one of our joint seminars. For my future career, however, the most important influence was that of Oliver Zangwill, who was my supervisor from 1937 to my graduation in 1939. It was he who first taught me the value of studying the behavioral effects of brain lesions, because he believed that through an analysis of disordered function one could gain insights into the functioning of the normal brain.

The War Years (1939–1944)

On the basis of my examination results, I was awarded the Sarah Smithson studentship by Newnham College, which would enable me to pursue postgraduate research in experimental psychology at Cambridge. My project was to explore how subjects behave in situations of sensory conflict, for example, in situations in which visual information was in apparent disagreement with information derived from proprioception. With the outbreak of World War II in September 1939, this project was redirected to the war effort. I became part of a team developing and administering selection tests for air crew with a focus on the supposedly different qualities required to be a fighter or a bomber pilot. Although the whole laboratory was on a war footing, Bartlett was very skilled in keeping his scientists out of uniform, which meant that we could give our opinions to Air Marshals without running into problems of rank.

When my studentship ran out, I had to leave Cambridge and I was recruited by C. P. Snow to work as an experimental officer for the Ministry of Supply at the Radar Research and Development Establishment situated in Christchurch, near Bournemouth, on the south coast. At that time I was one of only three women officers in this large establishment, the other two being librarians. My job was to evaluate different methods of display and control for radar operators. This is where I met Peter Milner, an electrical engineer from Leeds University, who had been designing a trainer for radar operators which allowed one to compare the tracking accuracy of direct laying, aided laying, and velocity laying, as well as different forms of display. I was billeted in the home of a factory worker and had little or no social contact with the mathematicians and physicists who made up the bulk of the scientific staff. I was, however, allowed frequent visits to Cambridge “to consult the Professor” and took full advantage of these short respites from my rather dreary existence in Christchurch.

The return train journey from London to Christchurch at night also had its own interesting possibilities, since most of the names of the stations had been removed, and in the country all the signposts were pointing the wrong way, to confuse invading Germans. At this time, in the spring of 1942, there was fear of possible parachute raids to carry off “brains” and it became evident that the establishment ought to be moved to a safer place. On one of my trips to Cambridge, I received an urgent telephone call from one of my friends, telling me to return to Christchurch immediately, with no further explanation. I did so, only to discover that within a few days the whole establishment was to be moved to Malvern, a small country town in the West Midlands, in the heart of the fruit-growing district.

The radar research establishment at Malvern soon took on the atmosphere of a college campus and the next 2 years were happy ones. Yet from a work point of view, this was for me a discouraging period of simply marking time, since the problems I was working on had no general theoretical interest. But by the late summer of 1944, it was apparent that the war in Europe would soon be over and it was time to think about one’s peace-time career. I was therefore delighted to be invited to return to Cambridge to work with Kenneth Craik once the war had ended.

At this point something totally unexpected occurred that was to change the course of my life. Peter Milner was invited to join a small group of physicists, under the leadership of Sir John Cockcroft, who were due to leave for Montreal to initiate atomic energy research in Canada. The project was to last 1 year. On the spur of the moment, Peter and I decided to get married and about 2 weeks later we set sail from Glasgow on the Queen Elizabeth, which had been converted into a troopship for the duration of the war. We were accompanied by a large group of British war brides who had married American soldiers stationed in Britain and were now on their way to the United States, and on the first night out we (i.e., all the women) were addressed by the ship’s captain and told not to harass the men. We had expected to land in New York, but in fact landed in Boston, to the delight of a young Bostonian anxious to rejoin her family for Thanksgiving. All the way across the Atlantic, we zig-zagged to avoid submarines, and all the time in complete black-out (as we had been in England for the previous 5 years). In Boston, the war brides received a warm welcome from the Red Cross, and we were included in that welcome and driven to the Copley Plaza Hotel for planked steak, ice-cream, and a good night’s rest. But what I remember after the darkness of wartime England, and the even deeper darkness of the North Atlantic, was the brilliantly lit streets of Boston. Peter and I found this light quite intoxicating, only to be told that this was the American black-out! Next day, after a brief tour of MIT physics labs, we took the train to Montreal, little knowing how long we would stay in Canada.

Montreal (1944–1952)

In Montreal, the first academic opportunity that presented itself to me was in the francophone Université de Montréal, where the head of the newly formed Institut de Psychologie, Father Noël Mailloux, was a Dominican priest whose somewhat unconventional approach to psychology combined the teachings of St. Thomas Aquinas with those of Freud. He began by asking me to give 20 lectures on Bartlett’s theory of memory, and he subsequently employed me to teach laboratory courses in experimental and comparative psychology. I found these assignments initially very challenging, since I had had little opportunity to speak French since my high-school days, although fortunately I had read a great deal. The challenge had to be met, however, and I found it a most stimulating experience. Moreover, I was only a few years older than my students and I formed some friendships that have lasted to this day. Nevertheless, as I became used to teaching in French, I realized that there were other difficulties in the way of communication. Most of the students had completed the classical baccalaureate degree and were interested in studying clinical psychology. They also had a Cartesian approach, expecting to know in advance what an experiment would demonstrate. My more empirical approach left them dissatisfied. I began to feel that it was time to make a change.

When we first arrived in Canada, the Psychology Department at McGill University was in a run-down state, having been reduced by the war to an absentee chairman and one half-time lecturer. In 1946, Robert MacLeod was appointed to the Chair, with a mandate to get the department back on its feet. MacLeod had carried out important research on the perceptual constancies in Germany before World War II and was strongly influenced by Gestalt psychology and phenomenology. This material was familiar to me from my undergraduate days at Cambridge, and I began to participate in his seminars, as an interesting change from my regular work at the Université de Montréal.

True to his mandate, MacLeod quickly recruited two senior faculty members, George Ferguson from Edinburgh in statistics, and Donald Hebb from Orange Park in what was then called physiological psychology. Hebb arrived with his book, The Organization of Behavior, still in manuscript; during his first seminar, we discussed this book chapter by chapter and did the relevant background reading, which covered Lorente de Nò, Marshall and Talbot, Hilgard, Lashley, and Sperry. The graduate students in this seminar included Mortimer Mishkin, Lila Ghent (Braine), Herb Lansdell, and Woodburn Heron, and discussion after the seminars often continued late into the night. It was an exciting time and hastened my decision to do a Ph.D. at McGill. By this time, the Atomic Energy project had moved from Montreal to Chalk River, Ontario. I wrote to Peter enthusiastically about the Hebb seminar, with the result that he decided on a career change.

In 1948, MacLeod left McGill for Cornell University and Hebb reluctantly took over the Chairmanship, a position that I think he soon came to enjoy. In 1949, I persuaded him to accept me as a graduate student, and I set about designing experiments to explore tactual concept formation in the congenitally blind.

One of the attractions for Hebb in returning to McGill was the interdisciplinary aspect, with colleagues such as Hank Mackintosh in physiology, and Wilder Penfield and Herbert Jasper at the Montreal Neurological Institute (MNI). Shortly after his arrival, Hebb had extracted a promise from Penfield that he could send one graduate student to the MNI to study the patients undergoing brain surgery for the relief of epilepsy. Under this arrangement, Donald Forgays had just completed a short project showing that patients were usually less impaired right after surgery than a few days later, when postoperative edema had set in, a finding that complemented his main research, which was with rats. Hebb then asked me if I would like to do my thesis research at the MNI, investigating the effects of temporal lobe lesions, since I was supposed to be inteested in the thought processes. Fascinated as I had become by my work with the blind, this could not compete with the attraction of Penfield’s patients. In June, 1950, I began to carry out research at the MNI, and knew immediately that this was the kind of work I wished to pursue, whatever the practical difficulties. Meantime, the only advice Hebb gave me was to make myself as useful as I could and not to get in anyone’s way. He also bequeathed me a few tests. The rest was up to me.

During those first months at the MNI, I was impressed, as no one could fail to be, by the experience of being present in the gallery of the operating room while Penfield stimulated the exposed cortex in awake patients who had reported complex hallucinatory experiences as part of their epileptic seizures. In a small number of such cases, Penfield was able to elicit reports of complex experiential phenomena that sometimes, but not invariably, resembled those occurring during their habitual seizures.

On the basis of such meticulously documented clinical observations, Penfield had become convinced that with his stimulating electrode he had managed to excite part of the neural substrate of past experience. Frequently, the experience he evoked by cortical stimulation could in fact be linked to some well-documented event, or at least to some recurrent feature of the patient’s everyday life. Hence came his postulate that somewhere in the brain of each of us, there is a continuous, ongoing record of the stream of consciousness (that is, of everythig we attend to, not of things we are not attending to) extending from birth to death.

To me, as an experimental psychologist, and a student of Bartlett, this tape-recorder notion of memory seemed highly implausible since I had been trained to think of remembering as a reconstructive rather than a reproductive process. Later I often talked to Penfield about the difficulties I had with this view. He used to say “Of course this is not memory as you psychologists understand the term, when you refer to the variability of memory, with its abstractions, generalizations, and distortions. In ordinary remembering, we do not have direct access to the record of past experience in the brain.”

Despite Penfield’s evident interest in memory processes, I had no intention at this stage of working on memory myself, but rather chose to focus on complex perceptual tasks. Apart from an early report by Hebb in 1939 on a single case of right temporal lobectomy, and a few auditory studies, little was known at the time about the behavioral effects of temporal lobectomy in humans. My hypotheses were therefore largely based on what was known in the monkey. In particular, the dramatic demonstration by Kluver and Bucy in 1937 of a state they termed “psychic blindness” followed bilateral temporal lobectomy in the monkey led me to expect to find visual impairments in patients with temporal-lobe lesions, although the fact that the removals in the patients were unilateral made it less likely that any striking changes would be seen. Using the small battery of tasks that Hebb had left me from his days at the MNI, I planned to test preoperatively, and again 2 weeks postoperatively, all patients undergoing unilateral cortical excisions as a treatment for focal epilepsy. With such a project, it was a particular disadvantage not to be at the MNI during the day, but I still had my full-time teaching job at the Université de Montréal, on the other side of town, and therefore had to limit myself to the weekends and evenings for testing patients. It was therefore important to know ahead of time on which patient Penfield was about to operate. For this I relied on the residents, but even they could never be sure, because Penfield would often decide only at the last minute to operate on Patient A rather than Patient B. Another obstacle was the pneumoencephalogram (PEG), which David Hubel described in his memoir, and which was mandatory for all presurgical patients. This procedure (over the timing of which I had of course no control) involved removing cerebrospinal fluid and replacing it with air. Afterwards the patients felt all right as long as they were lying down, but as soon as they sat up (as they had to do for my tests), they quickly developed headache and nausea, so that testing had to be abandoned. Despite these various frustrations, I managed to accumulate enough data for a thesis by the spring of 1952; I demonstrated mild deficits on certain pictorial tasks in my temporal-lobe groups, deficits that were detectable preoperatively and accentuated after removal of the epileptogenic area. Interestingly, these deficits were seen more reliably after right temporal-lobe lesions than after left.

I saw a parallel between the deficits I was observing in patients with right temporal-lobe lesions and the selective impairment of visual discrimination learning that was being described by Mishkin and Pribram after bilateral removal of the inferotemporal cortex in the monkey. Similarly, some years later, I was to uncover an impairment on simple melodic discrimination tasks after right anterior temporal lobectomy (but not after left) that resembled the auditory discrimination deficits seen after bilateral lesions of the superior temporal cortex in the monkey.

As I was writing my thesis, I became aware of several further avenues I wished to pursue. First, I needed to see more patients if I was to demonstrate the special contributions of the right temporal lobe. It was still hard to convince people that the results were not due to the surgeon making larger removals from the right than the left hemisphere, or that the right temporal deficit was not simply a consequence of an upper-quadrant visual field defect (although this could hardly account for the preoperative findings).

Secondly, I had been listening to the patients’ complaints and realizing that those with left temporal-lobe lesions complained of poor memory, but that when I questioned them further, the examples they gave were always from the domain of verbal memory. They forgot what they heard and what they read. It seemed that, whether I liked it or not, I ought to begin investigating memory. This conclusion was further reinforced by my first encounter with a case of postoperative global amnesia.

Hebb had assumed that upon completing my thesis in the summer of 1952 I would return to full-time academic work at the Université de Montréal. When I told him that I was planning to give up a tenured position there in order to pursue my research with Penfield’s patients, he attempted to dissuade me, assuring me that “no psychologist could survive for long at the MNI.” However, when he saw that my mind was made up, he offered to support me for a year as a postdoctoral fellow based in the McGill Psychology Department. To my astonishment, before the year was out, Penfield had told me that he needed me at the MNI and he had provided me with an office with easy access to patients and a small stipend (but no research funds). This gesture ensured the future of neuropsychology at the MNI and was, I think, brought about by the fact that in fairly rapid succession we had seen two cases of severe memory loss following unilateral anterior temporal lobectomy.

Memory Loss after Bilateral Medial Temporal-Lobe Lesions

In the early days of temporal-lobe surgery, Penfield had usually confined his removal to the anterior neocortex, but this limited resection was rarely effective in controlling the patient’s seizures; by the time I arrived on the scene, most temporal-lobe removals included the anterior hippocampus and parahippocampal gyrus, together with the amygdala, with no striking behavior change resulting from what by then had become a routine procedure. During this period, several patients with unilateral neocortical removals returned with continuing seizures, requiring completion of the temporal lobectomy.

In one such case, that of a civil engineer (P.B.), this second operation, which involved only the medial structures of the left temporal lobe, was followed by a severe, persistent, and generalized impairment of recent memory unaccompanied by other cognitive deficits. The impairment was manifest clinically as a profound anterograde amnesia, such that the experiences of daily life were forgotten as soon as the patient’s attention shifted to a new topic. In addition, there was a retrograde amnesia covering the salient events of the previous few months. P.B.’s unexpected memory loss was a troubling outcome of elective surgery; he remained a single puzzling case until November, 1952, when another patient (F.C.), a 28-year-old glove cutter, exhibited a similar amnesic syndrome after a one-stage left temporal lobectomy that included the amygdala, uncus, and anterior hippocampus and parahippocampal gyrus. In his case, the retrograde amnesia extended back 4 years.

To account for these two instances of memory loss after a unilateral temporal-lobe removal, we hypothesized that in each case there had been a preexistent, but preoperatively undetected, atrophic lesion in the medial temporal area of the opposite hemisphere, so that when Penfield removed a large part of the hippocampus and parahippocampal gyrus in the left hemisphere he effictively deprived the patients of hippocampal function bilaterally. The reason we emphasized the hippocampal region was that P.B. had had his temporal lobectomy in two stages, and it was only after the medial temporal-lobe removal that the memory loss was seen. In this case, our hypothesis was to be confirmed 9 years later, when P.B. died of a pulmonary embolism and the autopsy findings revealed the presence of a long-standing right hippocampal atrophy. In contrast, on the operated (left) side, the 22 mm of hippocampus that remained appeared to be normal.

We reported these two cases at the 1955 meeting of the American Neurological Association, in Chicago, and Dr. William Scoville, a neurosurgeon from Hartford, Connecticut, read our abstract. He immediately called Penfield and said that he had seen a similar memory disturbance in a patient of his (H.M.), in whom he had carried out a bilateral medial temporal-lobe resection, also in an attempt to control epileptic seizures. As a result, I was invited to go down to Hartford to study H.M. and other patients of Scoville with similar removals.

Scoville had designed the operation of bilateral medial temporal-lobe resection as an alternative to frontal lobotomy in the treatment of seriously ill schizophrenic patients. Because of the known connections between the medial temporal region and the orbital frontal cortex, he had hoped that this procedure would prove psychiatrically beneficial, while avoiding the undesirable side effects of a frontal lobotomy. As it turned out, the operation did little to alleviate the psychosis, and any memory changes went undetected until much later, when I had the opportunity to examine eight of these patients. Although some were difficult to test, I did manage to establish the presence of anterograde amnesia in all cases where the removal had encroached upon the hippocampus and parahippocampal gyrus, but not where the removal was limited to the uncus and amygdala.

Scoville had first become aware of the risk to memory in his operation in 1953, when he carried out a radical bilateral medial temporal-lobe resection in a 27-year-old epileptic patient (H.M.), whose frequent major and minor seizures had failed to respond to near toxic doses of anticonvulsant medication. This frankly experimental procedure had been proposed because H.M., an assembly-line worker by trade, had become unable to work or lead a normal life. The operation did in fact control the epilepsy, but at far too high a price. Already within the first few postoperative days, it was clear that H.M. had a serious impairment of recent memory. He could not remember what he had had for breakfast, and he could no longer find his way around the hospital or recognize members of the hospital staff (apart from Scoville, whom he had known for many years). He also showed a patchy retrograde amnesia for the events of the past 3 years, but his earlier memories appeared to be intact, his speech was normal, and his social behavior entirely appropriate.

On my first encounter with H.M. in April 1955, it was apparent that his memory disorder was of the same kind as that shown by Penfield’s two patients, but even more severe. Again, there had been no intellectual loss; in fact, H.M.’s IQ had risen postoperatively, from 104 to 117, presumably because he was now having far fewer seizures and was on considerably reduced medication.

As with P.B., H.M.’s capacity for sustained attention was also remarkable. For example, I found that he could retain the number 584 for at least 15 minutes by continuous rehearsal, combining and recombining the digits according to an elaborate mnemonic scheme. Yet the moment his attention was diverted by a new topic, the whole event was forgotten. This pattern seemed to suggest that he might be able to retain a simple memorandum indefinitely, provided that no other activity claimed his attention. What I failed to realize at the time was the key role played by verbal rehearsal in this holding process. My graduate student, Lilli Prisko, was later to show, using a delayed paired-comparison task, that simple nonverbal stimuli were forgotten by H.M. in less than a minute, a finding subsequently confirmed by Murray Sidman and his colleagues in an elegant delayed-matching paradigm. These and other related studies have concurred in showing that H.M. can register perceptual information normally, but that the information ceases to be available to him within 30-40 seconds. Such results appear to support the distinction between a primary memory process with a rapid decay and an overlapping secondary process (impaired in H.M.) by which the long-term storage of information is achieved.

H.M.’s inability to retain even verbal information after a single exposure, if he was distracted in the interval, did not necessarily mean that he would be unable to master a new task with extensive practice. Accordingly, before my next trip to Hartford, I picked up two different learning tasks from the McGill experimental psychology laboratory and then spent 3 days administering them to H.M. One of these tasks, a 28 choice-point stylus maze, proved to be impossibly difficult for him to learn, since by the time he reached the end of the maze he had completely forgotten the beginning, saying each time “I am having a little argument with myself: should it be this way or should it be that?” In contrast, and much to my surprise, H.M. had no trouble at all in learning the other task, mirror-drawing, which involved the acquisition of a new visuo-motor skill. In this case, H.M. was presented with a five-pointed star, with a double contour, and was instructed to trace a path around it, keeping within the narrow border created by the contour lines. What made the task difficult was that he only saw the star, and his own hand, as reflected in a mirror. Under these conditions, we all tend to move the hand in the wrong direction when we reach the points of the star, but we gradually improve with practice over many trials. I took H.M. through 30 trials, spread over the 3 days of my visit, and he showed a typical learning curve. Yet at the end of the last trial, he had absolutely no idea that he had ever done the task before. This was learning without any sense of familiarity. Nowadays we are well aware that such dissociations are possible following a discrete brain lesion, but for me at the time it was quite astonishing. It was also early evidence of the existence of more than one memory system in the brain.

H.M.’s success on the mirror-drawing task led me to speculate that other kinds of motor skill might also be acquired independently of the medial temporal-lobe system. By this I had in mind such activities as learning to dance or swim or to pronounce a foreign language correctly. Such skills are built up gradually without our being able to describe just what we are learning, and the attempt to introspect is likely to impair performance. It seemed reasonable to suppose that such kinds of learning (later termed “procedural” by Cohen and Squire) would not require the participation of a conscious, cognitive memory system.

This generalization has held up whenever it has been tested, although the skills sampled so far have been few and of limited complexity. But it soon became clear that motor skills were only a part of a large collection of learning and memory abilities that are spared in H.M. and other amnesic patients with similar lesions. Thus, in 1968, Warrington and Weiskrantz found that amnesic patients could learn to identify fragmented drawings of objects and animals with progressively fewer cues, even though they did not remember having seen the drawings before, a finding that I was subsequently able to replicate in H.M. This long-term effect of a prior visual experience, which I called “perceptual learning,” is an instance of what is now known as priming, a kind of learning distinct from motor skill, and which, in this case, is probably mediated at the level of the visual cortex.

Interest in human memory processes and their neural substrates has grown steadily over the past 30 years, and the early pioneering work with H.M. certainly provided some of the impetus for this growth. Nevertheless, the findings had a somewhat mixed reception at the time, largely because of difficulty in establishing a suitable animal model for human amnesia. For years we were perplexed by the seeming lack of confirmation from work with monkeys, where, for example, animals with bilateral medial temporal-lobe resections similar to what had been described in H.M. showed normal performance on visual discrimination-learning tasks, even when concurrent trials on a different task were interpolated as potential distractors. This led many investigators to question the human findings, or even the validity of cross-species comparisons. What we had not considered at the time was that ostensibly similar tasks may be solved in different ways by humans and monkeys, and that a visual discrimination task learned by the monkey over many trials was an example of procedural learning and therefore not a good test for amnesia. It was not until much later that the concept of multiple memory systems became widely accepted and hence that it became clearer which memory tasks were appropriate to give to experimental animals. An important breakthrough came in 1978, when Mishkin demonstrated a severe deficit in monkeys with bilateral medial temporal-lobe lesions on a one-trial task of object recognition memory (delayed nonmatching to sample). This is of course what we should have predicted from H. M.’s failure on single-trial, nonverbal delayed matching tasks, and represents a convergence of findings from monkey to man.

Taken as a whole, the behavioral studies provide compelling evidence that the cognitive (declarative) memory system is critically dependent upon the medial temporal region. Yet we still have much to discover about the relative importance of specific structures within that region and their mode of interaction with other brain areas. Despite the use of the word “hippocampal” in the titles of my papers with Scoville and Penfield, I have never claimed that the memory loss was solely attributable to the hippocampal lesions. Recent magnetic resonance imaging (MRI) studies in H.M. by Corkin et al. (1997) have shown that the bilateral medial temporal-lobe resection was essentially as described by Scoville, except less extensive (thus conforming to Percival Bailey’s dictum that surgeons typically overestimate the extent of tissue excised). The lesion was bilaterally symmetrical and included the bulk of the amygdala, the perirhinal and entorhinal cortices, and about 5 cm of the hippocampal formation. The parahippocampal cortex was largely intact, as was the lateral neocortex and temporal stem. It seems likely, as Corkin et al. suggest, that the severity of H.M.’s memory impairment compared with that of other amnesic patients with selective hippocampal lesions may be related to the inclusion of perirhinal, entorhinal, and some parahippocampal cortex in the removal. Much current research in various centers is directed to exploring this issue.

The Growth of Neuropsychology at the MNI

In the aftermath of my work on amnesia, neuropsychology flourished at the MNI. In 1957, I was joined by two young colleagues. Laughlin Taylor, a graduate student in the McGill Psychology Department, came to help with the clinical testing of neurosurgical patients and has stayed on to head our neuropsychological services. Doreen Kimura came the next year as my first Ph.D. student, supported first by Hebb and later as a postdoctoral fellow on my own N.I.H. grant. In her thesis, Doreen demonstrated a clear impairment after right temporal lobectomy, but not after left, in recognition memory for abstract visual patterns, as well as providing evidence for subtle perceptual changes associated with epileptogenic lesions of that lobe. Meantime I myself had found a robust deficit in memory for new faces after right temporal lobectomy but not after left. The argument for a greater contribution from the right temporal lobe than the left to memory for visual patterns was thus considerably strengthened.

Doreen was the first person to use the Broadbent dichotic-listening technique to demonstrate a complementary specialization of the two hemispheres in audition. In Broadbent’s version, different strings of digits were presented in pairs to the two ears, and the subject merely had to report as many digits as possible, in any order. Broadbent had found that normal subjects tended first to report all the digits for one ear, and then those for the other, rather than as a sequence of pairs. What Doreen discovered was that patients tested preoperatively, as well as normal control subjects, obtained higher scores for the right ear than for the left, a finding that she attributed to left-hemisphere dominance for speech and to the predominance of the crossed auditory pathway, from right ear to left temporal lobe, over the ipsilateral one. Evidence in support of this view came from patients with proven right-hemisphere speech lateralization, the majority of whom showed a left-ear superiority on this verbal dichotic-listening task. Doreen then went on to demonstrate, in a group of normal right-handed subjects, a right-ear superiority for digits combined with a left-ear superiority for the recognition of dichotically presented melodies, thus highlighting a dual functional asymmetry of the auditory system.

After Doreen left, Donald Shankweiler carried her auditory research further before joining Al Liberman’s group at the Haskins laboratories in New York. Don had been a student of Arthur Benton and one day he received a letter from Benton telling him that a new journal, Cortex, was about to be launched in Milan by De Renzi’s group. Only a short while earlier I had learned from Henry Hécaen of the first publication of Neuropsychologia, and Don and I wondered how two neuropsychology journals could survive. We would never have predicted then that both would be alive and thriving in the 1990s, together with a proliferation of other journals devoted to brain and behavior.

With Don’s departure, our work on audition was interrupted for several years, although ever since my own early strong findings of impairments in tonal memory and timbre-discrimination after right anterior temporal lobectomy I had been convinced of the need for further work on music. However, I was clearly not the right person to undertake it, given my musical incompetence. Fortunately, in 1981, I was able to recruit Robert Zatorre from Brown University on an N.I.H. postdoctoral fellowship. Robert held degrees in both music and experimental psychology, and thus seemed an ideal person to conduct research on music and the brain. Robert has stayed on to become a permanent member of our group and, together with his students, is making a major contribution to our understanding of how the brain processes musical input.

In 1961, the arrival of Suzanne Hammond (now Suzanne Corkin) as a graduate student from Smith College inaugurated our program of research in somesthesis, a topic in which she expressed a surprisingly passionate interest from the beginning. Initially Sue modelled her work on that of Josephine Semmes and Hans-Lukas Teuber who had carried out meticulous sensory testing on the hands of Korean war veterans with penetrating missile wounds of the brain, but at the same time she designed tactual learning tasks analogous to visual ones developed by Doreen. Since we still had virtually no money and no technical help, Sue showed considerable initiative in driving around to various local merchants and persuading them to make up material to her specifications “for the sake of McGill.”

By this time Theodore Rasmussen had succeeded Penfield as Director of the MNI; he proved to be an enthusiastic collaborator in several of our research projects. Despite an early report by Penfield and Evans of contralateral sensory defects after posterior parietal cortical excisions, Rasmussen was convinced, on the basis of his own surgical experience, that there was no lasting sensory loss after removals that spared the postcentral gyrus, unless the blood supply to that gyrus had been compromised. Sue’s careful quantitative testing of sensory discriminaton on the hand combined with Rasmussen’s systematic sensory mapping of the postcentral gyrus by cortical stimulation in awake patients yielded a striking confirmation of this hypothesis.

When Sue completed her Ph.D. thesis, she took up a position in Hans-Lukas Teuber’s newly formed department at M.I.T., and after Lukas’s untimely death in 1977, she took over the direction of the M.I.T. neuropsychology lab. Prior to Lukas’s death, he and I had collaborated in further follow-up studies of H.M., both in Hartford and at M.I.T.; Sue has continued to monitor H.M.’s progress to the present day, as well as carrying out new investigations of his memory disorder.

By the mid-1960s, our lab at the MNI had acquired some financial stability for the first time. In 1964, I received a Career Investigatorship award and an operating grant from the Medical Research Council of Canada; I have had continuous salary and research support from the Council ever since, without which most of our work could not have been done. Shortly afterward, Laughlin Taylor accepted a position as a clinical neuropsychologist on the Quebec Hospital Service, and our neuropsychology unit became more firmly established in both the hospital and the institute.

In 1960, I met Roger Sperry at a memory conference in New York, and when he heard of my special interest in the right hemisphere he invited me to go out to Pasadena and study the group of patients with cerebral commissurotomy. As a result, Laughlin Taylor and I made several visits to Caltech during the next 10 years, always with some specific experimental question in mind. For me, our most important finding was not only that the patients tested after cerebral commissurotomy were better at delayed matching of tactile patterns with the left hand than with the right, but also that they could bridge longer delays than H.M., whose commissures were intact. The fact that the mute, surgically isolated, right hemisphere could match tactile patterns correctly after a 2-minute delay seemed to me to constitute an effective rebuttal of the claim, by Sidman and others, that H.M.’s failure on such tasks after 30 seconds was due to a failure to generate the appropriate verbal labels.

My visits to Pasadena were enriching in other ways and led to lasting friendships with Roger and Norma Sperry, and with Joe and Glenda Bogen, as well as with many of the students in Sperry’s lab. I was therefore delighted when, in 1972, during a sabbatical year in Cambridge, I was able to welcome Roger and Norma there, on the occasion of Roger’s honorary degree from that university.

It was on a visit to Caltech that I first met Giovanni Berlucchi and Giacomo Rizzolatti, at a party held in their honor at the end of a year they had spent in Sperry’s lab; I was later to visit them both in Italy, first in Moruzzi’s lab in Pisa, and later in Parma and Verona on many occasions. During this same period, I also established strong links with Ennio De Renzi’s group in Milan; it was there that he and Luigi Vignolo persuaded me to give my lectures in my somewhat halting Italian, which henceforth added another dimension to my visits to colleagues in Italy. These Italian connections have also been strengthened by visits to Dario Grossi’s group in Naples, and by Valeria Cavazzuti’s prolonged stay in Montreal as a visiting scientist from Bologna, as well as by Antonio Incisa della Rocchetta from Rome, who did his Ph.D. with me and who has become a firm friend of all members of our group.

The Introduction of Intracarotid Sodium Amobarbital Speech Tests

It is impressive how often the introduction of a new technique can give us new insights into brain function. We owe the introduction of intracarotid amobarbital testing to Juhn Wada, a postdoctoral fellow in neurology from Japan. I remember the occasion when he first told us of the possibility of determining the side of speech representation by injecting a barbiturate, sodium amobarbital, into the common carotid artery of one side. It was during a preoperative EEG conference on a left-handed patient whose seizures arose from the left posterior temporal region, but who showed no postictal speech difficulty. Penfield had just remarked how wonderful it would be if only we had a means of determining ahead of time if the lesion was in the dominant hemisphere for speech, in which case he would not operate. Wada, sitting at the back of the room, suddenly spoke up, asserting that there was indeed such a way. Penfield removed his glasses (a sure sign of annoyance) and said that this was ridiculous. But Wada was quietly persistent, and soon he and Rasmussen embarked on rigorous testing of monkeys to establish the safety of the procedure. Then, from 1959 onward, all left-handed or ambidextrous patients who were candidates for a brain operation underwent preoperative intracarotid amobarbital tests to determine the lateralization of speech, as did any right-handers for whom there was reason to suspect atypical speech representation.

What these tests brought that was new was the possibility of comparing the functions of the two hemispheres of the same individual, although testing had to be simple and the time available was short. The language tests were similar to those used in conjunction with cortical stimulation in the operating room; they included both the naming of common objects and the recitation of well-known sequences, such as the days of the week forward and backward and counting forward and backward.

In a long series of amobarbital tests carried out in collaboration with Rasmussen and Charles Branch in neurosurgery, Laughlin Taylor and I confirmed the existence of bilateral speech representation in about 15 to 20% of non-right-handed patients, as well as demonstrating interesting qualitative differences between the pattern of speech disturbance from left and right-sided injections in about 40% of such cases.

The results of amobarbital speech tests also alerted us to the importance of locus of lesion in determining whether or not an early injury to the left cerebral hemisphere resulted in the right hemisphere becoming dominant for speech. Rasmussen and I were initially surprised to find that severe early trauma to the left frontal polar region or to the left occipital lobe was compatible with left-hemisphere dominance for speech. We later realized, from a scrutiny of the distribution of lesions in the group of patients with early damage to the left hemisphere, that damage to Broca’s area or to the posterior parieto-temporal speech zone in infancy was likely to bring about a functional reorganization of the brain in which the right hemisphere became dominant for language or in which there was bilateral representation, but that, in contrast, left-hemisphere lesions that spared these critical regions rarely affected the lateralization of speech.

The Initiation of Amobarbital Memory Tests

Once it had become apparent that the operation of anterior temporal lobectomy carried some risk to memory in patients with preexisting damage to the hippocampal region of the opposite hemisphere, for the next few years all seizure patients with bilateral independent electrographic abnormality, or with radiological or clinical evidence of such bilateral damage, were refused operation. Yet we realized that this policy would exclude many people whose seizures might have been controlled, or substantially reduced, by removal of the more epileptogenic area. For this reason, in the late 1960s, Rasmussen suggested that we try to adapt the intracarotid amobarbital procedure to the study of memory, thereby enabling us to screen out those patients for whom the proposed temporal lobectomy was likely to provoke an amnesic syndrome. The underlying hypothesis was that no memory deficit (as defined by our tests) should be seen after unilateral amobarbital injection, unless there was already extensive damage in the hippocampal zone of the opposite hemisphere. If there were such contralateral damage, then the temporary inactivation of the ipsilateral hemisphere by the action of the drug should produce transiently the amnesic state seen in patients, such as H.M., with known bilateral medial temporal-lobe lesions.

Attractive as this suggestion sounded, it was not at all clear to me at the time that such an extension of the amobarbital procedure from speech to memory would prove either feasible or valid. Whereas we could be confident that the carotid injection would affect the cortical speech areas, provided we obtained the expected contralateral hemiparesis, it was far less certain that the hippocampal region would be inactivated in those cases (and they would be the majority) in which the posterior cerebral artery was not filled. This question was particularly troubling because we were then still making our injections into the common carotid artery, and without angiographic control. We were thus unaware of the precise distribution of the drug in any given case. A second cause for concern was the fact that the effects of the amobarbital injection wear off in a matter of minutes, yet a short time lapse between stimulus presentation and stimulus retrieval was essential if we were to have a meaningful memory test.

In designing our original memory protocol in 1959, I was looking for a task that H.M. would fail but that an aphasic patient would be able to pass. The essential features were, first, the use of dually encodable material (line drawings of common objects) and, second, the interpolation of an effective distractor task (mental arithmetic) before memory was tested. An interesting early finding was that most patients showed very poor free recall of material presented when one hemisphere had been inactivated by the drug, even if the injection was ipsilateral to the patient’s brain lesion. For this reason, and because amnesic patients fail recognition as well as recall tests, we decided to take recognition of the test items from a multiple-choice series as our criterion of successful retention. The results for our first 123 patients were encouraging for several reasons. First, we obtained a clear dissociation between aphasia and amnesia, in that patients frequently recognized later objects that they had been unable to name when presented shortly after the injection, and, conversely, patients might fail to recognize later objects that they had named correctly. Second, our main goal was achieved in that we did see a transient anterograde amnesia after 22% of the injections contralateral to a temporal-lobe epileptogenic lesion, and never (in the first series) after ipsilateral injections. This anterograde amnesia was usually accompanied by retrograde amnesia for material presented before the injection. However, once the drug had worn off, patients were again able to identify the items from the preinjection period, whereas they could still neither recall nor recognize the new material that had been presented while the drug was active. Thus the retrograde amnesia could be attributed to a retrieval block but the anterograde amnesia appeared to represent a true failure to consolidate the new experience into an enduring memory trace. I later used this as an argument against Larry Weiskrantz’s interpretation of amnesia as primarily a retrieval deficit.

The Challenge of the Frontal Lobes

Although by the time I went to work at the MNI, by far the most frequent brain operations were for the treatment of temporal-lobe epilepsy, this had not always been the case. Before embarking on temporal-lobe surgery, Penfield had carried out a number of operations on the frontal lobes in cases of posttraumatic epilepsy or indolent brain tumor. It was during this period, in the late 1930s, that Hebb spent 2 years as a research fellow at the MNI, where he studied Penfield’s patients before and after surgery. At the time, Hebb’s main interest lay in exploring the effects of these removals on intelligence, as measured by the standard tests of the day. To his great surprise, the patients he saw showed little or no intellectual change following the frontal-lobe operation, and tended to have average or above-average intelligence before the operation.

The fact that in some cases an extensive removal of epileptogenic brain tissue actually resulted in improved intellectual status (provided that the patient’s seizures had been controlled) led Hebb and Penfield to formulate the notion of “nociferous cortex.” This is the idea that an area of damaged and malfunctioning brain can interfere with the activity of neighboring healthy tissue, so that when the damaged area is excised, the overall level of intellectual efficiency may rise. A particularly striking example of this was provided by their famous patient K.M. who in 1928, at the age of 16, had sustained a severe, penetrating injury to both frontal lobes. He subsequently developed recurrent major epileptic seizures and exhibited a marked deterioration in behavior. On April 14, 1938, in an attempt to alleviate the seizures, Penfield carried out a bilateral brain operation, removing an extensive area of scar tissue involving approximately the anterior one third of both frontal lobes. This operation not only controlled K. M.’s epilepsy, but also led to a remarkable improvement in his day-to-day behavior and to a reliable increase in his IQ, which was in the average range. Such results led Hebb to argue that in the adult brain the frontal lobes contribute less to intellectual function than had hitherto been supposed.

At first my own experience with frontal-lobe patients at the MNI seemed to add further support for Hebb’s view. Patients undergoing left or right frontal cortical excisions for epilepsy constituted well-matched brain operated control groups in my temporal-lobe studies. Not only were these patients unimpaired postoperatively on the Wechsler Bellevue Intelligence Scale, they also achieved normal scores on most of the perceptual and mnemonic tasks that proved difficult for patients with temporal-lobe lesions. Nor had they any difficulty performing the Weigl color-form sorting task, or other simple pass-fail tasks on which performance had been claimed to be selectively sensitive to frontal-lobe injury.

It seemed clear that I was missing something; once again I took my cue from studies in the monkey, where Harlow and Dagnon had demonstrated an impairment in discrimination reversal learning after large bilateral frontal cortical excisions. Their animals showed normal learning of the initial discrimination problem but had great difficulty in overcoming their established response pattern, once the reward values of the discriminanda were reversed so that the previously correct choice became incorrect. With this result in mind, I decided to administer the Wisconsin Card Sorting Test to all my patients before and after operation. In this task, which was modelled by Grant and Berg on work with monkeys, the subject is required to sort a stack of response cards with reference to four key cards and to verbal feedback provided by the examiner as to the correctness of each response. After a particular mode of sorting has been established (say, to color), a new sorting principle (form or number) is imposed without warning. Whereas normal control subjects and patients with temporal-lobe lesions usually adapt quickly to the new principle, I found that patients with dorsolateral frontal lobe-lesions did not, the deficit being more consistently seen and more long-lasting after left frontal lesions than after right. These results on a quantitatively scored test provided strong support for the view that the ability to shift from one mode of solution to another is more impaired by frontal than by posterior cerebral injury and constituted my first evidence of cognitive impairment in our frontal-lobe groups.

It so happened that in 1962 I had the opportunity to carry out a follow up study on Hebb and Penfield’s patient K.M., who had sustained damage to both frontal lobes; I was able to replicate Hebb’s findings for the intelligence tests that had been given 23 years earlier. K.M. had remained seizure free, his behavior had been socially appropriate, and his Wechsler IQ was with in the average range. Yet on the Wisconsin Card Sorting Test he exhibited to an unusual degree the perseverative behavior that I had come to expect from patients with lesions to the dorsolateral frontal cortex. This case study emphasized for me that fact that the failure to find deficits after a brain lesion may merely mean that the range of tasks sampled has been too narrow, rather than that the damaged area was serving no important cognitive function.

Divergent Thinking and the Frontal Cortex

Many of my ideas for studying patients have come from having my curiosity piqued by peculiarities of behavior that I then set out to measure with carefully chosen tasks. In this sense my research has been data-driven rather than theory-driven. A salient example of this is my discovery of a word fluency deficit in patients with excisions from the left frontal lobe. These removals all spared Broca’s area; the patients showed no loss on verbal intelligence tests, but I was impressed by the remarkable paucity of their spontaneous speech, even though they were typically cooperative and good-humored throughout the lengthy testing sessions, had a normal vocabulary, and were certainly not aphasic. There was thus a striking contrast between their word knowledge and their word use. I set out to test this further using the Thurstone Word Fluency Test, which requires subjects to write down as many words as possible beginning with a particular letter within a prescribed time limit. Patients with left frontal-lobe excisions were in fact impaired on this task, having a lower output than my other groups, including the patients with left temporal-lobe lesions and deficient verbal memory. My student, Marilyn Jones-Gotman, then went on to demonstrate a corresponding deficit in patients with right frontal-lobe lesions on a nonverbal fluency task, in which subjects were instructed to draw as many different unnameable designs as they could invent in a given time.

Fluency tasks are considered to be tests of divergent thinking, in that they emphasize the number and variety of responses that can be generated to a single question, unlike traditional intelligence tests, where there is usually just one answer to the question or problem set. Such tasks are held to be better predictors of creative achievement than are standard intelligence tests, and it is therefore interesting that performance on them should be impaired by frontal-lobe lesions.

Frontal Lobes and the Temporal Organization of Memory

In 1964, I was invited by Larry Weiskrantz to take part in a summer workshop at Churchill College, Cambridge to examine the various experimental methods used to measure behavioral change consequent to surgical, pharmaceutical, and other treatments. My assigned topic was that of memory disorder. As a result, I found myself trying to understand better why patients with frontal cortical excisions failed certain memory tasks, while performing normally on others that involved the same kind of memoranda. It seemed as though the way that memory was tested was critical in determining whether or not a deficit would be found after frontal lobectomy, whereas in the case of left or right temporal-lobe removals, the nature of the stimulus material was the predominant factor.

The natural starting-point for thinking about frontal lobes and memory is the classical experiment of Jacobsen in 1935, followed by that of Jacobsen and Nissen in 1937, showing impairment of delayed response and delayed alternation in monkeys with bilateral frontal-lobe removals, the critical zone being subsequently narrowed down by Nelson Butters to the middle third of sulcus principalis. This did not, however, seem to me to be the best way to test memory in patients, because even quite long time intervals can be bridged by verbal mediation. Instead, my student, Lilli Prisko, had in 1963 adapted the Konorski delayed paired-comparison technique to bring out deficits after frontal lobectomy; the task embodied an intratrial delay as an essential feature. In her procedure, two easily discriminable stimuli in the same sense modality are presented in succession and the subject has to say whether the second stimulus was the same as, or different from, the first one, presented 60 seconds earlier. Patients with frontal-lobe lesions were impaired on those tasks on which a few stimuli recurred in different pairings throughout the test, but not on the one task in which new stimuli were used on each trial. This contrast indicated that patients with frontallobe lesions had a heightened susceptibility to interference from the effects of preceding trials, rather than an inability to retain new information over a short time interval.

Reflecting on these findings during the Cambridge workshop, I suggested that frontal lobectomy might interfere with the ability to structure and segregate events in memory, and hence that in a situation lacking strong contextual cues, patients with such lesions would be less able than control subjects to distinguish a stimulus presented 60 seconds ago from one appearing earlier in the same series of trials. It seemed to me that if items in memory normally carry time tags that permit the discrimination of the more from the less recent (as Yntema and Trask had proposed), then this time-marking process might be disturbed by frontal-lobe injury, so that serial-order judgements were impaired.

Some years later, in the early 1970s, another student of mine, Philip Corsi, provided a direct test of the hypothesis by constructing three formally similar recency-discrimination tasks, embodying different kinds of stimulus material (concrete words, representational drawings, and abstract paintings) and administering these tasks to patients with unilateral removals from the frontal or the temporal lobe and to normal control subjects. The results obtained confirmed the notion that frontal-lobe lesions impair the temporal ordering of recent events, as well as indicating some specialization offunction related to the side of the lesion and the stimulus material.

Unlike the temporal-lobe groups, neither frontal-lobe group was impaired in simple item recognition, as measured by the ability to distinguish a stimulus that had appeared before from one that was new. These findings pointed to some separability of the processes mediating item memory and those mediating memory for temporal order.

It was not possible, on the basis of Corsi’s original data, to identify a specific area within the frontal cortex that is implicated in recency discrimination, but when later, in collaboration with my former graduate student, Gabriel Leonard, I tested more patients, we found some limited support (in the case of the left frontal lobe and verbal tasks) for a critical area in the mid-dorsolateral frontal cortex, as I had hypothesized on the basis of animal studies.

By this time there was ample evidence of cognitive deficits associated with lesions of the frontal cortex, and also of a reawakened and growing interest in this part of the brain. Whereas, for me, the 1950s had been the decade of the temporal lobes, in the early 1960s the major emphasis in our work shifted to studies of frontal-lobe function, despite the relatively small number of these cases coming our way. This trend was evident also in the interests of new recruits to our unit. In 1973, Morris Moscovitch spent a year with me as an MRC postdoctoral fellow on leave from the University of Toronto; during this period he looked for proactive-interference effects on verbal memory tasks in patients with frontal-lobe lesions. He was followed by Bryan Kolb, also an MRC postdoctoral fellow, with a strong interest in the role of the frontal lobes in social communication.

In 1977, Michael Petrides came as a postdoctoral fellow from Sue Iversen’s laboratory in Cambridge. Michael had a strong background in neuroanatomy but had carried out behavioral work on the frontal and parietal cortex of the monkey for his Ph.D. thesis. Michael had chosen to do his postdoctoral research with me in Montreal, because he wished to adapt some of the tasks that he had used with monkeys to the study of patients with frontal- or temporal-lobe lesions. But on arrival in Montreal, Michael also established an animal laboratory and devised simplified versions of some of the tasks that I had used with patients (including those requiring temporal-order judgments) in order to look for more precise localization of function than was possible in our work with patients. Subsequently, Michael embarked on systematic neuroanatomical studies of the primate frontal cortex with Deepak Pandya in Boston, and this work has now provided us with a valuable, detailed picture of the anatomical homologies between monkey and human frontal cortex.

New Developments and the Advent of Neuroimaging

The last few years have brought many changes. In 1990, Michael Petrides succeeded me as Director of Neuropsychology/Cognitive Neuroscience Unit at the MNI, while I continue to carry out research as the Dorothy J. Killam Professor of Psychology, funded by the Medical Research Council of Canada. Michael’s appointment means that the Institute has now committed itself to a full-time salaried professorial position in neuropsychology, and hence that the research unit that I built up will continue to flourish.

I have had many new graduate students since the early 1980s, including Dennis Rains, Donald Read, Mary Lou Smith, Laurie Miller, Julien Doyon, Virginia Frisk, Susan Pigott, Ingrid Johnsrude, and Joelle Crane. This period has seen a consolidation of my earlier work with patients, with further evidence of the complementary specializations of the two temporal lobes in memory processes, and of the important role played by the hippocampal region. In addition, with the introduction by Dr. André Olivier of the procedure of selective unilateral amygdalo-hippocampectomy as an alternative to anterior temporal lobectomy in cases of medial temporal-lobe epilepsy, it has become possible to delineate better the specific role of the medial temporal region in the performance of our memory tasks.

At this point, a whole new research prospect opened up with the establishment of the McConnell Brain Imaging Centre at the MNI, first under the directorship of Albert Gjedde, and more recently of Alan Evans. This meant that we were now able to use neuroimaging techniques of positron emission tomography (PET), combined with MRI, to measure regional cerebral blood-flow changes in normal volunteer subjects, and in individual patients during the performance of our various cognitive tasks.

The opportunity came at the right time for us, because in 1989 Michael and I were jointly awarded a McDonnell-Pew grant to establish a center for cognitive neuroscience at the MNI. This substantial financial support has facilitated a close interaction between the neuropsychology unit and that of brain imaging. It has also enabled us to attract some gifted young scientists to join our group, including Tomáš Paus, a neurophysiologist from Prague, and Denise Klein, a psycholinguist and cognitive psychologist from South Africa.

Neuroimaging work with normal subjects complements rather than replaces the analysis of the behavioral effects of brain lesions, and the underlying logic is different in the two cases. In the typical lesion study, if a lasting impairment in the performance of a given task follows damage to a particular brain region, it is assumed that the damaged area plays a critical role in normal performance of that task. In contrast, in the typical PET experiment, the regions showing significantly increased blood-flow compared with a baseline condition are assumed to have been jointly activated by the cognitive demands of the task, without performance necessarily being dependent upon the integrity of all the activated regions. The great attraction of imaging studies is that they show us the normal brain in action, and that they allow us to break our complex behavioral measures down into their component processes (as, for example, in comparing the encoding and retrieving phases of a memory task).

During the past few years, Denise Klein and I have been using PET and MRI to investigate whether performance in a second language (L2) involves the same neural substrates as that of a first language (Ll) in normal bilingual subjects, who acquired L2 after the age of 5 years. To do this, we first capitalized on the bilingual (French–English) situation in Quebec, but later extended our study to two languages (Mandarin and English) that were linguistically more distinct. Still more recently, in collaboration with Andre Olivier, we have embarked on a series of individual studies of presurgical patients whose brain lesions bordered on critical speech cortex. Our goal has been to map not only primary speech areas, but also areas involved in higher order linguistic processing, such as synonym generation. By using tasks in the operating room similar to those used with PET, we have attempted to correlate regions of cerebral activation identified via PET with those identified by electrical stimulation of the exposed cerebral cortex in patients under local anesthesia. Our clinical aim is to reduce the risk to language in such operations.

Postscript

As I look back over the past 50 years, it seems to me that I have had a lot of luck in being in the right place at the right time, but also enough tenacity of purpose not to be discouraged when the going got rough, as it frequently did in the early days at the MNI. I am also grateful for my sense of curiosity, which led me to wish to delve deeper into phenomena that caught my eye, and which keeps me going to this day. Of course none of this work would have been possible without the active collaboration of my colleagues in neurosurgery, in particular Theodore Rasmussen and Andre Olivier, or without the enthusiastic support of generations of graduate students and postdoctoral fellows who contributed so much. At this stage, my own greatest satisfaction comes from seeing behavioral neuroscience so firmly established in what Hebb, some 40 years ago, considered to be unpromising soil.

Selected Bibliography

Branch C, Milner B, Rasmussen T. Intracarotid sodium amytal for the lateralization of cerebral speech dominance. J. Neurosurg 1964;21:399–405.

Corkin S, Milner B, Rasmussen T. Somatosensory thresholds—Contrasting effects of postcentral-gyrus and posterior parietal-lobe excisions. Arch Neurol 1970;22: 41–58.

Frisk V, Milner B. The role of the left hippocampal region in the acquisition and retention of story content. Neuropsychologia 1990;28:349–359.

Incisa della Rochaetta A, Milner B. Strategic search and retrieval inhibition: The role of the frontal lobes. Neuropsychologia 1993;31:503–524.

Jones-Gotman M, Milner B. Design fluency: The invention of nonsense drawings after focal cortical lesions. Neuropsychologia 1977;16:61–71.

Klein D, Milner B, Zatorre RJ, Meyer E, Evans AC. The neural substrates underlying word-generation: A bilingual functional imaging study. Proc Natl Acad Sci USA 1995;92:2899–2903.

Klein D, Olivier A, Milner B, Zatorre RJ, Johnsrude IS, Meyer E, Evans AC. Obligatory role of LIFG in synonym generation: Evidence from PET and cortical stimulation. NeuroReport 1997;8:3275–3279.

Klein D, Zatorre RJ, Milner B, Meyer E, Evans AC. Left putaminal activation when speaking a second language: Evidence from PET. NeuroReport 1994;5: 2295–2297.

Kolb B, Milner B. Performance of complex arm and facial movements after focal brain lesions. Neuropsychologia 1981;19:491–503.

Leonard G, Milner B. Contribution of the right frontal lobe to the encoding and recall of kinesthetic distance information. Neuropsychologia 1991;29:47–58.

Leonard G, Milner B. Recall of the end-position of examiner-defined arm movements by patients with frontal- or temporal-lobe lesions. Neuropsychologia 1991;29: 629–640.

Milner B. Intellectual function of the temporal lobes. Psycho Bull1954;51:42-62.

Milner B.Psychological defects produced by temporal lobe excision. Res Publ Assoc Res Nerv Ment Dis 1958;36:244–257.

Milner B. Laterality effects in audition. In: Mountcastle VB, ed. Interhemispheric relations and cerebral dominance. Baltimore: Johns Hopkins Press, 1962a; 177–195.

Milner B. Les troubles de la mémoire accompagnant les lésions hippocampiques bilatérales. In: Physiologie de l’hippocampe Colloques lnternationaux No. 107. Paris: C.N.R.S., 1962b;257–272. [English translation in: Milner PM, Glickman S, eds. Cognitive processes and the brain. Princeton: Van Nostrand, 1965; 97–111]

Milner B. Effects of different brain lesions on card sorting. Arch Neurol 1963;9: 90–100.

Milner B. Some effects of frontal lobectomy in man. In: Warren JM, Akert K, eds. The frontal granular cortex and behavior. New York: McGraw–Hill, 1964; 313–334.

Milner B. Visual recognition and recall after right temporal-lobe excision in man. Neuropsychologia 1968;6:191–209.

Milner B. Memory and the medial temporal regions of the brain. In: Pribram KH, Broadbent DE, eds. Biology of memory. New York: Academic Press, 1970;29–50.

Milner B. Hemispheric specialization: Scope and limits. In: Schmidtt FO, Worden FG, eds. The neurosciences: Third study program. Boston: M.I.T Press, 1974; 75–89.

Milner B. Memory and the human brain. In: Shafto M, ed. How we know, Nobel conference XX. New York: Harper & Row, 1985;31–59.

Milner B. Aspects of human frontal-lobe function. In: Epilepsy and the functional anatomy of the frontal lobe. New York: Raven Press, 1995;66:67–84.

Milner B. Amobarbital memory testing: Some personal reflections. Brain Cognition 1997;33:14–17.

Milner B, Branch C, Rasmussen T. Evidence for bilateral speech representation in some non-right-handers. Trans Am Neural Assoc 1966;91:306–308.

Milner B, Corkin S, Tueber H-L. Further analysis of the hippocampal amnesic syndrome: 14-year follow up of H.M. Neuropsychologia 1968;6:215–234.

Milner B, Corsi P, Leonard G. Frontal-lobe contribution to recency judgements. Neuropsychologia 1991a;29:601–618.

Milner B, Jonsrude I, Crane J. Right medial temporal-lobe contribution to objectlocation memory. Phil Trans R Soc Lond B 1997;352:1469–1474.

Milner B, McAndrews MP, Leonard G. Frontal lobes and memory for temporal order of recent events. In Watson JD, Kandel E, Stevens C, Senjowski T, organizers. The brain, Cold Spring Harbor Symposium on Quantitative Biology. New York: Cold Spring Harbor Laboratory Press, 1991b;55:987–994.

Milner B, Penfield W. The effect of hippocampal lesions on recent memory. Trans Am Neurol Assoc 1955;30:42–48.

Milner B, Petrides M. Behavioural effects of frontal-lobe lesions in man. Trends Neurosci 1984;7:403–407.

Milner B, Taylor L. Right-hemisphere superiority in tactile pattern recognition after cerebral commissurotomy: Evidence for nonverbal memory. Neuropsychologia 1972;10:1–15.

Milner B, Taylor L, Jones-Gotman M. Lessons from cerebral commissurotomy: Auditory attention, haptic memory, and visual images in verbal associative learning. In: Trevarthen C, ed. Brain circuits and functions of the mind. New York: Cambridge University Press, 1990;293–303.

Milner B, Teuber H-L. Alteration of perception and memory in man: Reflections on methods. In: Weiskrantz L, ed. Analysis of behavioural change. New York: Harper & Row, 1968;268–375.

Owen AM, Milner B, Petrides M, Evans AC., & A specific role for the right parahippocampal gyrus in the retrieval of object-location: A positron emission tomography study. J Cog Neurosci 1996;8:588–602.

Penfield W, Milner B. Memory deficit produced by bilateral lesions in the hippocampal zone. AMA Arch Neurol Psychiat 1958;79:475–497.

Petrides M, Milner B. Deficits on subject-ordered tasks after frontal and temporal lobe lesions in man. Neuropsychologia 1982;20:249–262.

Pigott S, Milner B. Memory for different aspects of complex visual scenes after unilateral-temporal or frontal-lobe resection. Neuropsychologia 1993;13:l–15.

Rasmussen T, Milner B. The role of early left-brain injury in determining lateralization of cerebral speech functions. Ann NY Acad Sci 1977;299:355–369.

Scoville WB, Milner B. Loss of recent memory after bilateral hippocampal lesions J Neurol Neurosurg Psychiat 1957;20:11–26. [Database]

Smith M-L, Milner B. Differential effects of frontal-lobe lesions on cognitive estimation and spatial memory. Neuropsychologia 1984;22:697–704.

Smith M-L, Milner B. Right hippocampal impairment in the recall of spatial location: Encoding deficit or rapid forgetting? Neuropsychologia 1989;27:71–81.

Additional Publications

Cohen NJ, Squire LR. Preserved learning and retention of pattern analyzing skill in amnesia: Dissociation of knowing how and knowing that. Science 1980;210: 207–209.

Corkin S, Amaral DG, González RG, Johnson, KA, Hyman, BT. H. M.’s medial temporal lobe lesion: Findings from magnetic resonance imaging. J Neurosci 1997; 17:3964–3979.

Grant DA, Berg EA. A behavioral analysis of degree of reinforcement and ease of shifting to new responses in a Weigl-type card-sorting problem. J Gen Psychol 1948;38:404–411.

Harlow HF, Dagnon J. Problem solution by monkeys following bilateral removal of the prefrontal areas. I. The discrimination and discrimination-reversal problems. J Exp Psychol 1942;32:351–356.

Hebb DO. Intelligence in man after large removals of cerebral tissue: Deficits following right temporal lobectomy. J Gen Psychol 1939;211:437–446.

Hebb DO, Penfield W. Human behavior after extensive bilateral removals from the frontal lobes. Arch Neurol Psychiat 1940;44:421–436.

Jacobsen CF. Functions of the frontal association area in primates. Arch Neurol Psychiat 1935;33:558–569.

Jacobsen CF, Nissen HW. Studies of cerebral function in primates: IV. The effects of frontal-lobe lesions on the delayed alternation habit in monkeys. J. Comp Physiol Psychol 1937;23:101–112.

Kimura D. Cerebral dominance and the perception of verbal stimuli. Can J Psychol 1961;15:166–171.

Kluver H, Bucy PC. “Psychic blindness” and other symptoms following bilateral temporal lobectomy in rhesus monkeys. Am J Physiol 1937;119:352–353.

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© 1997 Nicholas DeSclose

Karl H. Pribram

BORN:

Vienna, Austria

February 25, 1919

EDUCATION:

University of Chicago, B.S. (1938)

University of Chicago, M.D. (1941)

APPOINTMENTS:

Yerkes Laboratories of Primate Biology (1946)

Yale University (1948)

Center for Advanced Studies, Stanford University (1958)

Stanford University (1959)

Professor Emeritus, Stanford University (1989)

Distinguished Professor, Radford University (1989)

HONORS AND AWARDS (SELECTED):

NIH Lifetime Research Career Award (1962)

International Neuropsychological Society (President, 1967)

American Psychological Association

Division of Physiological and Comparative Psychology (President, 1967–1968)

Division of Theological and Philosophical Psychology (President, 1979–1980)

Menfred Sakel Award, Society for Biological Psychiatry (1976)

Realia Honor, Institute for Advanced Philosophic Research (1986)

Outstanding Contributions Award, American Board of Medical Psychotherapists (1990)

Honorary Ph.D. in Psychology, University of Montreal, Canada (1992)

Neural Network Leadership Award, International Neural Network Society (1994)

Honorary Ph.D. in Neuroscience, University of Bremen, Germany (1996)

Karl Pribram was trained as a neurosurgeon and then devoted his career to elucidating the structure and function of the cerebral cortex, relating human clinical experience to his neurophysiological and neurobehavioral studies on nonhuman primates. He discovered the visual functions of the temporal lobe and the relationship of the anterior frontal cortex to the limbic system. His theoretical writings include the topics of perception, emotion, memory, and planning.

Karl H. Pribram

Preamble

Summer 1918. The head of the bacterological services of the Austrian Army and a Dutch Red Cross nurse were swimming nude in the Danube somewhere between Vienna and Budapest. Some pigs pulled their clothes from the bushes; retrieval entailed a considerable chase. The child conceived on that occasion was often accused of “pigging out,” and his manners were attributed to that chase by the Danube.

February 25, 1919. I was born in Vienna, Austria at 8:00 PM encased in the amniotic sac—taken by my mother to be a most propitious beginning.

Autumn 1923. I set off to a Kinderheim in Gstaadt, Switzerland to protect me and my mother from a stormy relationship.

Summer 1924. Ernest August Pribram, my father, went to America to save me from growing up in a Europe whose future he saw as torn with political turmoil.

Autumn 1926. I joined my mother in Vienna and finished second grade in Catholic school.

Summer 1927. I went to a farm in Geneva, and learned French.

Autumn 1927. I and my mother arrived in the United States and my reunited family settled in Chicago.

The Scientist as a Young Man

It was Labor Day, 1932, when my father put me on a train in Chicago to head for Culver Military Academy near Fort Wayne, Indiana. I had set my sights on going to Culver once I had heard about it from my dentist, a gentle, wonderful man who saved my adolescent cavitous molars which, over the next 70 years, I have had to protect from the more rapacious of the dental profession. Tonsils I still also own, despite the medical fad that no one should reach adulthood with such natural protective devices in place. In each case battles with established practice had to be engaged and each time I won: good training for a career in research.

My attraction to Culver was simple: horses. My father could not afford the additional fees to allow me to become a member of the famed Black Horse Troop which was sent to Washington for each presidential inauguration. But the field artillery was still horse-drawn in that long-ago time when the caissons and French 75’s went rolling along.

Before going to Culver, I had a dismal 6-year record in Chicago’s public schools, being repeatedly expelled for fighting with bullies who picked on everyone, or from Catholic schools for asking the nuns simple questions such as how God could be both all good and all just. What I saw around me during the depression of the 1930s didn’t fit the picture of God that those good women tried to convey. When told to have faith, I lost all faith in what the hooded ladies had to say, and expressed my opinion in no uncertain terms. Over and over. My father had Jesuit friends who tried to reason with me, but as I would not accept their premises, they taught me only that reason can be totally reasonable and that what one needs to ascertain truth or falsity is to search for the premises, the axioms, from which the reasoning takes off.

The public school teachers were being paid with script, so during the last year in elementary school, I took over when teachers were absent—which was often. I figured that each of the students had fathers and that the fathers worked and could tell their children what they did. So, each pupil came to class prepared to tell us about his father’s occupation, and what it entailed both intellectually and in practice. We were all fascinated and much preferred our system to the substitute teachers that were foisted upon us. The administration was not altogether pleased.

My father believed that a military environment was just what his son needed. As we said good-bye I hugged him (he didn’t like hugging much) and I said that I was proud to be admitted to such an excellent school. My father replied, “Be sure to conduct yourself in such a manner that Culver will be proud of you when you leave.” Those parting words stayed with me for the rest of my life.

During my senior year science was to be taught for the first time in the history of the Academy, one course in physics and another in chemistry. I immediately registered for both. Although the two courses were not to be taken simultaneously, I pleaded that as a senior, I had been prevented from having an adequate science education. I took the courses and received honors in both, as well as in history and in English literature. Each required a special project that went beyond what had been covered in class. Only one student was to receive honors in a particular subject and each student was eligible to receive honors in only one subject. Fortunately, only the competitive “one subject, one student” part had been made explicit and my projects were completed at graduation when the “one student, only one honor” became elevated to everyone’s consciousness, as we would say today. I graduated with all four honors.

The decision as to which university to attend was a difficult one. I had been accepted at Oxford, Harvard, and the University of Chicago, but two related factors favored Chicago: (1) I had decided to study biology and medicine, and my father, an eminent biologist (bacteriologist, pathologist, and immunologist) with whom I hardly ever had interacted, was there; and (2) though a decision for Harvard or Oxford would have carried more prestige, in 1936, Chicago under Maynard Hutchins was more intellectually alive and innovative. So Chicago it was.

My father and I met every Sunday. He portrayed the facts and ideas important to physiology and immunology to me in unforgettable fashion. Just recently I joined in writing two papers that deal with the possibility of superconductivity in dendrite membranes because the formulations are consonant with these early tuitions.

Five years later, in 1941, I received my M.D. According to Hutchins, it was not really considered a doctorate, rather simply a permit to practice a trade. The Chicago colors were withheld from the gowns worn to the graduation ceremonies by the incipient medics.

I had done well at university. I loved my undergraduate courses in history and economics, physics and chemistry, and biological discovery, made straight Ns, and took comprehensive exams in stride, often without having attended classes (an O.K. under Hutchins). I took copious notes. The endocrines and the brain were especially intriguing because they served as integrators of the functions of the body. Viewing myself as a potential explorer (I had steeped myself in Amundsen and Admiral Byrd while in my preteens and in Paul DeKruif’s The Microbe Hunters somewhat later) I saw endocrinology and biochemistry at one extreme—where too much research had already been done to consider them virgin fields—and brain physiology at the other extreme, where too few techniques seemed to be available for fruitful exploration.

All this changed once I engaged the medical clinical curriculum. Seeing patients was wonderfully satisfying from the human and diagnostic standpoint, but the lectures and laboratory sessions were incredibly dull. When I asked questions of “how” or “how come,” I was summarily informed that the answer was, “because I say so.” I was challenging authority and that was a no-no. Catholic school all over again. This in Hutchins’s Chicago? Obviously, Hutchins was correct in his evaluation: medical school was a trade school.

In one class we were to type pneumonias. Thirty-six types were known and during the course of the class, two more were discovered. Sulfanomides had also just been discovered and were on the market. Was it really necessary to learn the typing procedure? The class decided: No. The professor declared: Yes. The class walked out and got away with it. Some of Hutchins’s influence permeated even into the depths of the medical establishment. Over the years medical education has, to some extent, remedied this intolerable teaching situation, but one still reads articles by students, interns, and residents who tell a story that is not too different from the one I experienced.

The only way to make the study of medicine outside of the clinic interesting was to attach oneself to one or another of the professors and aid them in their research. One got to know them, the puzzles they were trying to solve, and the broader biological perspective within which medical care operates. I decided to apprentice in the department of physiology. “Ajax” Carlson was its head. He insisted that every student in the department repeat the historically important experiments that led to current views of how the human body functioned. This dictum had an enormous influence on my research career. Over the years, many experiments done in my laboratories were initiated to see for ourselves the details of currently important findings that can only come from first-hand experience in generating data. Thus, when confronted in a discussion of ideas, I would always be able to call up Carlson’s other dictum: “Wass iss die effidence?” And, to the extent possible, I would have that evidence first-hand.

I was privy to exploring with my professors the deterioration of the activity of vitamin C in orange juice with storage; the effects in dogs of denervation of the kidneys, and a project I devised and performed myself: How much blood flow does the liver need before deficiencies in function would show up on laboratory tests? I constricted the flow of blood to the liver by placing adjustable clamps on the hepatic artery and the vena cava. The clamps had been devised by Goldblatt to do just this sort of study on the kidneys. Goldblatt found that impairing kidney blood flow produced persistently elevated blood pressure. The liver experiments had no such dramatic effects. Turning the screws on the Goldblatt clamps had no effect whatsoever on the then-available tests of liver function—until the last one-eighth turn of either screw (in the clamp on the vena cava or the one on the hepatic artery). With this last turn, the animal, which had to all intents been perfectly normal for weeks, died. Any small aggregate of surviving liver cells could function in lieu of the entire liver, up to a point.

It was a lesson I remembered when, much later, I learned that memory storage in the brain shows considerable resistance to degradation when large extents of that organ are damaged.

Most exciting of these forays into research, however, was an exposure to the work being done in Ralph Gerard’s laboratory. On one occasion, an electrical record from a brain site energized a loudspeaker. Whenever a loud clap was produced near the cat from which the record was being taken, the loudspeaker would give out a distinct sound. A tap to the cat’s paw also produced a sharp sound on the loudspeaker. Brain electrical activity reflected the sensory input! A discussion ensued: why couldn’t these results be shown outside the laboratory? Electrocardiograms were being made daily, why not electroencephalograms (EEGs)? The answer was that the electrical changes produced by the brain were several magnitudes smaller than those produced by the heart.

That evening, across the table from me sat Frank Offner, a student engineer who became intrigued by the problem when I told him what I had seen. He stated that the current lack of sufficient amplification of the signal with respect to the noise of the system should not be insurmountable. I introduced Offner to Gerard. Frank Offner spent his life making and marketing EEG machines, the hard-copy electroencephalograms we sought that evening at dinner. It was the first time I realized how many contributions to neurobehavioral science could be made in informal settings far removed from the laboratory. There were to be many, many more.

Ralph Gerard was to play a most significant part in my education. Gerard was an incisive thinker and a brilliant teacher. Whenever sloppy reasoning went on in the classroom he propelled a piece of chalk at the perpetrator. On one such occasion, I was the target: my thinking had been teleological, a process forbidden in Gerard’s neurophysiology. Many years later, neurophysiologists became aware of the ubiquitous presence of feedback and feedforward processes in the nervous system. I laughed privately at my former master and always cocksure friend. “Ha ha, how wrong you were in your certainty,” I exclaimed as I was composing Languages of the Brain.

I have spent many hours in the classroom pointing out how our ideas of the functions of the brain have evolved, and that even what I have written and taught has become obsolete. I am not sure that my way of teaching is better than Gerard’s. Perhaps uncertainty is too unsettling to a student. Let students be misled and find out for themselves, allowing them to experience the glee of having the “professor” shown to be wrong.

Of course I didn’t always wait until later to challenge my professor. On one occasion Gerard was providing the class with the criteria for classifying mammals. Among these was hair. I stroked my long dense locks and asked: “Really, do all mammals have hair?” The class roared. Gerard was as bald as Yul Brynner in “The King and I.”

For me, the high point of Gerard’s classes came at the time of a final exam in an advanced course on neurophysiology. Gerard asked only one question: Discuss the organization of the nervous system. Fortunately for me, John Fulton’s classic Physiology of the Nervous System had just arrived at the university bookstore the weekend before the exam. In preparation, I had purchased a copy. The book was so fascinating that I could not put it down and spent the entire weekend reading, letting go the rest of my studies and preparation for finals. On Gerard’s exam I filled eight blue books, writing as fast as writing could be accomplished. Gerard stated it was the very best he had ever received; how had I achieved such comprehensive knowledge and superb organization? I told Gerard of Fulton’s book. Fortunately, Gerard had not as yet seen it; the posing of his exam question was not related to the publication.

The first half of Fulton’s Physiology of the Nervous System was devoted to sensory receptors, motor units, peripheral nerves, spinal cord, and brainstern. Microanatomy was presented with appropriate pictures. The second half of the book did the same for the brain’s cortex and the fiber system coursing to and from it and detailed the discovery of the functions of the occipital (rear) lobes of the brain’s hemispheres. In a similar fashion, Fulton reviewed the discovery of the connections of the parietal lobe to somatic sensation and the temporal lobe to hearing. Nothing as yet was known of the functions of the inferior part of this lobe. This was to be my contribution during the first years of work with Fulton.

The most fascinating and important story for me, though I didn’t realize it at the time, was composed by the results of damage to the frontal lobes of the brain. Fulton’s work had led to the procedure of frontal leukotomy, or lobotomy, as it was commonly known. Severing the fibers connecting the frontal lobes from structures in the brain stem was shown, on occasion, to produce marked changes in personality. What caused these changes was not known. After I had completed my training in neurosurgery (with Paul Bucy, Eric Oddberg, Percival Bailey and Warren McCullock in Chicago, Illinois; Eustace Simmes in Memphis, Tennessee; and Lyerly in Jacksonville, Florida), Fulton asked me to join him in finding out just what they might be. But I am ahead of the story.

Another aspect of neurophysiology that I learned from Gerard and from Fulton’s book was that receptor-initiated signals course to the spinal cord via nerves that reach it through a “root” that is separate from the one leaving the cord to reach muscles. Experiments by Charles Bell in England and François Magendie in France had shown that sectioning of the entering root left the animal without sensation while its movements remained intact. The reverse was true of the other, the outgoing root. Until these experiments were completed, no one knew which root provided the input and which the output. The results of the experiment were heralded as a “law” and were the basis for conceiving the basic unit of nervous activity as a reflex arc.

Reflex arcs are segregated in segments which represent the fact that the composition of our bodies is much like that of earthworms. Each segment of the spinal cord is encapsulated by a vertebra. The vertebrae are held together by sheaths which contain disc-shaped cartilaginous cushions. When the sheaths rupture the cartilage oozes out to press on the nerve roots, causing pain. When the compressed nerve roots carry signals from the back of the leg, the patient experiences sciatica. Much of the ordinary practice of neurosurgery is made up of removing such ruptured discs.

Many years later, just before joining Fulton in his laboratory at Yale University in 1948, one of the last major human surgical operations I performed was the removal of such a disc. I had recently read of an innovative technique, by which the operation was done with the patient lying on his side, eliminating pressure on his abdominal blood vessels and thus minimizing bleeding at the operative site. I was able to remove the disc before the operating room nurse had fully completed setting up all the gear we usually needed, and performed the entire procedure in less than 20 minutes. The patient was eating steak a few hours later and had no recurrence of his problem.

However, in all his discussion of reflexes, Fulton did not mention a major component of the output root of the reflex: one-third of the nerves composing this root end in the receptors of muscles. Thus muscle receptor activity is regulated not only by the stretching of the muscle but by signals coming to the receptor from the spinal cord. The spinal cord signals are in turn controlled by signals coming from the brain. Although known to exist previously, the importance of these receptor regulating nerves came into focus in the 1950s through the work of John Eccles and Stephen Kuffler. They investigated the effects of stimulating the nerves going to the receptors after having removed the functions that make muscles contract.

The “law of Bell and Magendie” was, after all, not a law. The reflex arc is not an arc but a mechanism akin to a thermostat that can be set to a particular value which determines the operation (the on’s and the off’s) of the system. Soon other receptors were found to be regulated in a similar fashion. Years later, Spinelli and I would devote a decade to showing that retinal processes were subject to such central control. In 1960 George Miller, Eugene Galanter, and I wrote a book (Plans and the Structure of Behavior) in which we detailed the import of the new neurology and moved psychology from stimulus-response, reflex-arc behaviorism to a cognitive science which paid heed to the brain’s control over its own input from the senses.

In 1949 John Fulton presented me with the third edition of his book inscribed, “In warm appreciation. . . .”My main contribution to this edition was to rewrite the chapter on the brain’s control over the autonomic nervous system. The autonomic system is called this because it regulates the functions of the viscera which, for the most part, take care of their own process and function automatically without our awareness or conscious intervention. However, I had by then established that the brain’s cortex had an input to the hypothalamus of the brainstem which, in Fulton’s earlier editions, was called the head ganglion of the autonomic system. Fulton himself had obtained, with Margaret Kennard, results that indicated the possible operation of such cortical control and in fact gave me my appointment at Yale, in part, because of my findings. But I am again getting way ahead of the story as it has unfolded over the years.

Gerard’s lectures and laboratory courses with the climactic final exam had me hooked. The brain was to be the continent I was to explore. Many years later, Paul MacLean inscribed a translation (for which he was responsible) of a book written by Ramon y Cajal: “To Karl, Magellan of the Brain.” I was delighted with his insight as to my motivation in choosing a research career.

Over these years, Gerard became a close friend, referred to as Poppa Ralph, because when my father was killed driving an auto in which my bride and I were passengers, Gerard telegraphed his readiness to fetch us from Montana where the accident had occurred. The Chicago experience was thus a warm and personal one as well as an intellectual feast.

World War II came as expected and the necessities demanded graduation, internship, and residencies. I passed up the opportunity to receive a Ph.D. in physiology although I had passed all the necessary examinations. This was no time to pursue the basic research necessary to finish a thesis. My life as an enthusiastic, unorthodox, and brash young man had to give way to life among medical men, those arch conservatives who threw Semmelweiss out of their profession for showing that they were infecting mothers in the hospital during childbirth and put Pasteur temporarily into a jail for administering lockjaw vaccine to a boy who had been bitten by a rabid dog.

What sustained me during those years (1941–1948) of the practice of medicine and surgery were the rewarding experiences with patients which made up the practice and the consuming interest in finding out how the brain works which was fuelled by the signs and symptoms portrayed by these patients. During my externships and internship I was fortunate to have as a colleague, my complement, Joseph Ranzahoff: he abhorred neurology and brain surgery but loved the smelly nether regions of abdominal surgery. Trades of patients were the order of the day: chaque un a son gout. Ironically, during his military stint Ranzahoff was assigned to neurosurgery and after the war, he became an eminently successful, though somewhat gruff, practitioner of the art in New York city (see Shainberg, 1979).

In addition to Gerard, the University of Chicago was rich in other neuroscientists. Stephen Polyak was working on the anatomy of the retina and visual system. I was intrigued by the work of Roaf (1927, 1930) on color afterimages and saw in Polyak’s detailing of three sorts of retinal bipolar cells a mechanism for analyzing and further separating the Helmholtzian receptor process, accounting for the effects of color afterimages. I wrote up these suggestions with Polyak’s help and submitted the result as an unpublished medical student thesis.

Paul Weiss was training Roger Sperry to transplant limbs of Amblystoma. I became well acquainted with both of them when Weiss appeared on my medical service during my internship. The friendships lasted a lifetime and centered on the problem of resonance: How could it be that a limb induces in the developing nervous system a code that allows the system to recognize the limb irrespective of its innervation? Sperry’s answer to this question invoked specific chemical codes; mine, suggested in Languages of the Brain, devolves on the finding by J.Z. Young of the induction of specific nerve fiber size spectra by each muscle. Most likely the specific chemistry induces specific fiber size spectra.

A. Earl Walker became chief of neurological surgery when Paul Bucy left; I learned the details of thalamic anatomy from Walker before joining Bucy. Over the years to come, together with Kao Liang Chow and with the help of Jerzy Rose at Johns Hopkins University, I extended Walker’s anatomical research to complete a classification of thalamocortical connectivity. Also during this period, Ward Halstead introduced me to what we now call neuropsychological procedures, which are used to study the effects of brain injury in humans.

But most important to my future were Heinrich Klüver and Paul Bucy, pioneers in investigations of the functions of the temporal lobe of the brain. In 1942, I became Bucy’s first resident when he moved to the nearby Chicago Memorial Hospital and wrote up our first 100 brain operations in order to have the residency accredited. Bucy was editing a volume on the precentral motor cortex at the time and I became privy to the controversies and details of explorations of this research, as well as learning the techniques of surgery from a master.

My time with Bucy was exciting and fabulously enriching. Bucy would tell stories as we made rounds. He had started in general practice and had found that his patients were in fact patient and loyal even when he made mistakes or had to bumble through because of his limited experience. What counted, he found, was that he was really trying and that he was totally honest with his patients and their families. On another occasion he recounted that, while in general practice, he had visited a mental hospital only to find that almost all the patients were sedated with bromides. He ordered the patients to be taken off the drug. Within a fortnight more than half of them were well enough to be considered for discharge. (We don’t use bromides today, but how will our current drugging practices be evaluated by another generation?)

Most of all, Bucy taught me how to localize brain tumors and, in the course of this, to learn about the localization of brain functions. I read avidly during the few quiet moments while on emergency duty, including the book Bucy had published with Buchanan on intracranial tumors in infancy and childhood, and the section on brain tumors he wrote for Roy Grinker’s textbook on neurology. In the section on treatment (p. 621), I saw once again (as I had been taught in obstetrics) the admonition “we must follow the ageold rule of surgery, primum non nocere, and curb our enthusiasm to the point where optimum results in length of life, comfort, and happiness are attained.”

It was also the time I became acquainted with Percival Bailey’s treatise on intracranial tumors. After carefully and beautifully reviewing the evidence, he unequivocally states (p. 69): “I merely wanted to impress upon you that in the human brain the parts are not equipotential and that even the defect of intelligence does not, as is sometimes stated (261), depend only upon the quantity of cerebral tissue removed or destroyed.” Reference (261) is to Karl Lashley’s 1929 monograph Brain Mechanisms and Intelligence, which I managed to purchase at a second-hand book store for a dime. Lashley later became a major influence in my life and the tension between his views and those I inherited from Bailey and Bucy formed the thrust of my research career.

Bailey could make his summary statement despite that in the text (p. 67) leading up to it he had to remark that:

The anatomical correlates of such relatively simple functions as sensation and voluntary motion are somewhat familiar to us. We know also that the central mechanism of the more complicated function of language is usually clustered closely around the left lateral fissure, but when we attempt to discuss a higher mental function such as intelligence, we are greatly hampered by lack of consistent data. Yet certain areas of the brain are known, injury to which is peculiarly liable to disturb intelligence. One of these is the left supramarginal gyrus. Another is the anterior part of the frontal lobe, although in this case the disturbance of character is predominant and I should be less willing to indicate the exact area involved. It is significant that these parts are just the ones in the human brain which are most developed beyond those present in the higher apes.

Later, after I had been given techniques to study such general concepts as intelligence and character by Karl Lashley, I made it my research business to pin down more precisely the localization of the brain/behavior relations entailed. Only much later did I begin to understand what Lashley meant by his dicta regarding equipotentiality and mass action in the storage and retrieval of memories and in the processing of equivalence in perceptions and actions.

In 1943, Bucy was editing a volume on the motor systems of the brain. I was privy to that editing, chapter by chapter, as Bucy explained to me his views and criticisms of what had been submitted. I found out that Wilder Penfield, Warren McCulloch, and Dusser de Barenne all thought of the cerebral motor cortex more as a sensory cortex for movement than as the final common path for all cortical activity, a view that Bucy shared. I learned of how much scholarly activity goes into the writing and editing of such a volume, the great care to provide the best currently available access to knowledge.

My turn to become scholarly came when we admitted a 54-year-old Greek woman who complained of bouts of twitching accompanied by localized sweating over the left side of the face. While in the hospital she actually experienced a grand mal epileptic seizure accompanied by sweating and by flushing. When during surgery we found a small oligodendroglioma in the precentral motor cortex, a tumor which was readily removed with the result of a complete cure for the patient, I suggested that we had come upon a most important finding. Everyone in neurology knew that control over the autonomic nervous system was exercised by no higher station than the hypothalamus. Cortical control would mean that the system was not as autonomous, or automatic, as we had been taught to believe. But here was a patient whose cortical tumor had produced epilepsy accompanied by localized sweating and flushing, definitely due to excitation of the autonomic nervous system. I asked Bucy if this observation was worth publishing and he agreed that, indeed, it was. I was eager to get something into print. I was already 24 years old and most of my forebears had published in their early 20’s. I was about to become the laggard in the family.

The paper was accepted for publication in the Archives of Neurology & Psychiatry (Bucy and Pribram, 1943) and Bucy received a letter from Earl Walker that the Chicago Medical Society wished to have it presented at their next meeting. Bucy showed me the letter and said “you do it.” I did. The other speaker that evening was Warren McCulloch, head of the research team at the Neuropsychiatric Institute of the University of Illinois. I did not understand a word of what he was trying to tell us and neither did anyone else. It took me another 40 years of listening to McCulloch (who was at Massachusetts Institute of Technology (MIT) when I was at Yale) and discussion before I was able to grasp the “cybernetic” ideas that were to transform our understanding of the way the nervous system operated. Two decades later, I was offered the headship of the research team at the University of Illinois. It was a most gratifying offer but, by then, I was ensconced in a most productive laboratory at Stanford and could not see myself free to move.

A second research endeavor stemmed from the results of the surgery performed on this interesting woman: I noted that careful removals of cortical tissue that minimally invaded white matter left the patient with no perceptible aftereffects. During the 1950s, when Lawrence Weiskrantz was a graduate student in my laboratory, discussing this insight led to his lifelong pursuit of careful removals of visual cortex and the devising of infinitely sophisticated testing procedures to determine the extent of residual vision; these experiments resulted in his discovery of blind-sight, the ability to perform visual tasks without conscious awareness of the visual stimuli involved.

Within a few months of joining Bucy, I was so completely caught up in neurosurgery (while still attending to all the other services in the small hospital) that I made a decision to pursue the study of the nervous system, as a neurologist, a psychiatrist, or a neurosurgeon. I had never been good with my hands so I asked Bucy to tell me, after some months, whether I could make it as a surgeon. His answer came in typical Bucy fashion. One day he said, “Next month I am going on vacation and turning my practice over to you.” I asked if that meant that he wanted me to do the surgery. “Of course,” he said. That was all. I had set up a woodworking shop in my home and had practiced using my hands with the aid of machine shop workers who were my neighbors. All my patients and I survived the month. That was it; I became a neurosurgeon. Bucy arranged for me to have a residency with Eric Oldberg at the neighboring St. Luke’s hospital if I wanted it. Oldberg was head of the University of Illinois Neuropsychiatric Institute where Percival Bailey, Gerhardt von Bonin, and Warren McCulloch were pursuing their own research. I was to be part of this team.

Thus, after my year with Bucy, I became Oldberg’s resident (and also took on the residencies in neurology and psychiatry for extended periods when necessary because of the war) with privileged access to this group. Bailey took on another resident, John Green, and Bailey sat with us over a six-month period detailing the history of his tutelage with Hortega del Rio, whose methods and neuroembryological approach led to Bailey’s pioneering work on the classification of brain tumors. Each story was illustrated with microscopic material sectioned from brain tumors which we examined together in great detail.

I occasionally participated in the then-ongoing strychninization experiments of chimpanzee cortex and listened attentively to Bailey, von Bonin, and McCulloch discuss the results. Some years later, at Yale University, I was able to put to good use my surgical skills and the knowledge I had acquired from these discussions to complete the chemical stimulation experiments on cat and monkey by explorations of the medial and basal surfaces of the brain, which had remained inaccessible to the earlier research.

A most exciting part of the research going on at this time was the exploration of the lateral surface of the human brain for suppression of motor activity. Although the results obtained were highly controversial, the process of cortical stimulation in which Bucy also participated, the examination of the patient (sometimes left to me) while this stimulation was in progress, and the discussions which ensued were fascinating. I remember well the occasion during one of these procedures when a telegram arrived from Paul Glees at Oxford University stating that he had just found nerve fibers connecting the precentral cortex to the caudate nucleus, using his newly developed silver staining technique. McCulloch suggested that the term negative feedback be applied to explain the suppression of motor activity and that Glees had found the anatomical basis for such feedback. Knowledge of these feedback circuits, in conjunction with those operating on the spinal reflex, were to produce the Test–Operate–Test sequence as a fundamental procedure operating in the formation of Plans in Plans and the Structure of Behavior (Miller et al., 1960).

The Universities of Chicago and Illinois were not the only centers for neuroscience research in Chicago at the time. Horace Magoun and Donald Lindsley and their collaborators were beginning their research on the mesencephalic reticular formation at Northwestern University. I was to participate in this work in collaboration with Percival Bailey, having received a fellowship to do so, but Bailey changed his plans and went overseas for a year. The proposed collaboration never took place, but my interest in the project had been piqued so that I kept abreast of developments as they occurred.

Exciting as all of these Chicago experiences were, they did not furnish me with some of the basic tools I needed to accomplish my goals, which were to explore the relationship between brain function and mental processes such as emotion, cognition, and conation (the intention to act). In my search for a hay fever-free location where I might earn my living as a neurosurgeon and at the same time pursue these goals, I heard of the Yerkes Laboratories of Primate Biology near Jacksonville, Florida, where Karl Lashley was director. Fortunately, there was a position open in Jacksonville with J.G. Lyerly. Lyerly, as well as Poppen in Boston, had devised a superior incision for frontal lobotomy which was safer than the classical (lateral) Freeman–Watts procedure and left fewer unwanted side effects. The lateral incision was shown by Fred Mettler and L. P. Rowland to invade Broca’s speech area. Although no language disturbances followed the lateral incision, fibers from the medial and orbital cortex were more apt to be saved when Lyerly’s superior incision was used. Because of his innovative bent, I felt that Lyerly would be sympathetic to my desire to work at Yerkes. In 1946, I took my Florida State Board examinations and began private practice.

Lyerly agreed to my working two half-days per week, plus any free time, at my research at Yerkes. I called Lashley and he responded favorably, stating that he had been looking for a neurosurgeon to assist him in his primate research. Thus began a collaboration which was to prove most influential in shaping my subsequent research program.

Lashley taught me the techniques of experimental psychology, a field of inquiry which I did not know existed. Paradoxically, although Lashley was almost solipsistic, destructive in his research procedures and interpretations of any finding that would relate brain function to behavior, he provided many of the questions that needed to be answered and that led to the discoveries which make up the substance of my career. Some of the discoveries I made while he was still alive, such as the unique relationship between the frontal cortex and the limbic forebrain, and the sensory specificity of various sectors of the posterior “association” cortex. He ignored or played down these results, as they were contrary to his belief that the mechanisms involved in organizing complex psychological processes were distributed in the brain. But always, his critical wit sharpened my interpretations and provided the basis for further observation and experiment.

The opportunity to work full time in research came in 1948 when I was asked by John Fulton to join him the department of physiology at Yale University. My association with Yale lasted for a decade (1948-1958), during which time I also directed the research laboratories of the Institute of Living, a mental hospital in nearby Hartford, Connecticut. The facilities at Yale and in Hartford provided ample space for a group of young investigators dedicated to exploring the power of combining the techniques of experimental psychology with those of neurophysiology and experimental neurosurgery. Doctoral students from Yale (Muriel Bagshaw, Martha Helson Wilson), Harvard (Lawrence Weiskrantz), McGill (Mortimer Mishkin), University of California at Berkeley (William Wilson), and Stanford (Jerome Schwartzbaum) formed the nucleus of a most productive team, all of whom received their degrees while working on the program.

During this period I spent one month a year at the Yerkes Laboratory, and Kao Liang Chow, an early student and collaborator, spent a month with me in the north, reestablishing at least in part Yerkes’ original vision, a Yale University-related primate research laboratory. This continuing collaboration led to an invitation to succeed Lashley as director of the laboratories, and I filled this post until the president of Yale University sold the laboratories to Emory University in Atlanta in 1956.

Also during this period, I began an intimate association with psychologists at Harvard University. I taught summer school there one year, built operant equipment in the Harvard shops, and learned a great deal from S.S. Stevens, Gary Boring, and Georg von Bekesy. Once a month, Bert Rosner and I drove up to Harvard (and later MIT) to perform experiments with Walter Rosenblith on monkeys in which we evoked electrical potentials in the cortex by auditory stimulation. Somewhat later, these sessions were extended to explore, with Wolfgang Kohler, the evocation of direct current shifts under similar conditions.

My interactions with B.F. Skinner at Harvard were especially memorable and led to a decade of primate operant conditioning experiments, which developed into subsequent research in cognitive neuropsychology. Shortly, I was able to automate and extend the operant equipment to record (including reaction time) the results of individual choices among a dozen possible panel presses. Later, over my three decades at Stanford (1959–1989), these responses were recorded in a large variety of problem-solving situations. The computer-controlled testing apparatus was dubbed Discrimination Apparatus for Discrete Trial Analysis (DADTA).

At one point in our interaction, Skinner and I came to an impasse over the possible mechanism involved in the chaining of responses. Chaining was disrupted by resections of the far frontal cortex. Skinner suggested that proprioceptive feedback might have been disrupted, but this hypothesis was not supported by my experiments. Furthermore, as I indicated to Skinner, he, as a Ph.D. in biology, could propose such an hypothesis, but I, as a loyal Skinnerian, had to search elsewhere than within the “black box” for an answer to our question. George Miller overheard some of our discussions and pointed out to me that he had available a procedure that made chaining of responses easy: a computer program. Miller explained to me the principles of list programming which he had just learned from Herbert Simon and Alan Newell. The culmination of the collaboration begun by these encounters in the halls of Harvard was Plans and the Structure of Behavior, a book influenced also by our interactions with Jerome Bruner, who had organized a conference on thinking at Cambridge University in 1956 to which we had been invited. The book was written in 1958-1959 at the Center for Advanced Studies in the Behavioral Sciences, adjacent to the campus of Stanford University.

Thanks to Jack Hilgard and Robert Sears of the psychology department, and to Tom Gonda (the son of a neurologist who had been a friend of my family in Vienna) in psychiatry, I was given an appointment at Stanford (supported, initially, by a grant from the Markel Foundation for Social Research) in 1959. Soon afterward, in 1962, I received a lifetime research career award from the U.S. National Institutes of Health which, in addition to substantial grants to pursue research interests, sustained me for the next three decades.

At Stanford, another group of doctoral and postdoctoral associates joined these endeavors. (Altogether, some fifty doctoral and fifty postdoctoral fellows were trained in the neuropsychological laboratories at Yale and Stanford under my direction.) At Stanford, Robert Anderson, Muriel Bagshaw, Bruce Bridgeman, James Dewson, Robert Douglas, Daniel Kimball, Abraham Spevack, and Leslie Ungerleider were among those who made major contributions. Nico Spinelli became an integral and almost indispensable collaborator.

When I became emeritus at Stanford at age 70, I was offered the opportunity to continue work at Radford University in Virginia. Radford, sister university to Virginia Tech, built a laboratory for me, and I organized a Center for Brain Research and Informational Sciences (B.R.A.I.N.S.) with the help of Alastair Harris, who chairs the psychology department. The appointment is supported by the eminent scholars fund of the Commonwealth of Virginia and an endowment from the James P. and Anna King Foundation. I developed a close and effective collaboration with Joseph King, who obtained his Ph.D. at neighboring Virginia Tech under the direction of Abe Spevack, who had spent several years with me at Stanford as a postdoctoral fellow.

Research Themes

The results of the research completed over the years at the Yerkes laboratories, at Yale, at Stanford, and currently in Virginia, can be organized according to overlapping themes, each theme representing a problem area and the application of techniques appropriate to that problem area. A description of the themes follows.

Theme I: Establishing a Correlation between Brain Systems and Specific Behavioral Indicators

By the time my research program began, large areas of the primate cortex remained unexplored by experimental investigation. In humans, damage to these areas resulted in agnosia, aphasia, and changes in character, and thus in interpersonal emotional interactions. But it was not known whether these changes in competence and behavior were the result of damage additional to that inflicted on primary sensory-motor systems, or whether the changes could occur without such damage. Furthermore, it was not known whether the changes were specific to one or another location within the silent (known as the “association”) cortex.

By using a battery of behavioral tests and resecting large parts of the then-silent cortex of monkeys without invading the primary sensory-motor systems, I found answers to these questions relatively rapidly. A method was devised which used superimpositions of reconstructions of resected cortex. The number of the resections that produced a particular behavioral deficit were summed. The sum of the resections which produced no deficit were also summed and the result was subtracted from the sum of lesions that produced a deficit. This “intercept of sums” technique was the origin of the “double dissociation” technique now used so extensively in clinical neuropsychology and allowed me to make multiple double dissociations among the various deficits produced by the resections and to localize the brain system involved in the behavior represented by each task (reviewed by Pribram, 1975).

The results I obtained at Yale in the early 1950s were unequivocal. One type of deficit was produced when the anterior frontal, the cingulate and hippocampal cortex, and the amygdala and anterior temporal cortex were resected. Another type of deficit followed resections of the posterior cortical convexity and could be further subdivided into sensory-specific components, each of which was related to its own portion of the convexal cortex. In no instance did invasion of the adjacent primary sensory-motor systems produce the deficit or even enhance it. These findings were published in the Journal of Comparative Neurology and Journal of Comparative and Physiological Psychology in the early 1950s, reviewed in 1954 in Current Trends in Psychology (Pribram, 1954), and reprinted in Behavioral Sciences (see Pribram, 1969, Vol. I).

Theme II: Determining the Behavioral Categories Denoted by the Indicators

Having identified specific behavioral indicators for the functions of specific areas of the cortex, the next problem was to discover what the indicators meant. Much as a Babinsky sign serves as an indicator of improper functioning of the spinal pyramidal motor system, signs of malfunction of brain cognitive systems were now available to us.

In order to define the meaning of the behavioral indicators we had to explore the effects of each brain resection with a wide range of behavioral tasks related in one way or another to the indicator. Limits were established by showing which tasks could be performed without any deficit. For example, the visual deficit produced by resections of the inferotemporal cortex was observed during discriminations of color, brightness, size, and two- and three-dimensional shapes, but not when the animal was tracking even minute objects. Further, limits to the deficit on the brightness or size discrimination were obtained when the difference between the brightness or size of the cues was either very large or very small. (In the latter case, normal controls had as much difficulty discriminating size or brightness as did the monkeys with brain damage.) I used response operator characteristic curves (ROC) to check whether the deficiency in discrimination was a function of changes in detection threshold or in response bias.

Interpretation was seldom straightforward, despite the wealth of data accumulated. This was in large part due to the lack of agreement about the constructs used in experimental psychology. Just how does one compare the results obtained in a fixed interval operant conditioning study with a result obtained in an ROC decisional experiment? How does one compare either of these with results obtained in a delayed alternation situation tested in a Yerkes box or with the DADTA apparatus? Interpretation had to be made after much cross validation of techniques, often using the same subjects and, of course, comparable resections. Nonetheless, some 80 publications in Brain, Journal of Neurophysiology, Journal of Comparative Neurology, Journal of Comparative and Physiological Psychology, and Neuropsychologia presented the results of these investigations, each in the technical language appropriate to the behavioral methods used. But in most cases some conceptual leaps were necessary in making the interpretations; these leaps were guided on one hand by findings on human neuropsychological patients and on the other by knowledge obtained about the anatomy and physiology of the neural systems being investigated.

Theme III: Determining the Physiological Processes Mediated by the Systems

Another line of research, which was made possible by the initial findings of Theme I, was an analysis of the anatomy and physiological processes of the neural systems of which the critical cortical areas were a part. Chemical and electrical stimulations in anesthetized or problem-solving monkeys were performed. The effects of such stimulations on electrical recordings of event-related, local field potentials were assessed while monkeys performed in the DADTA. Also, such effects on the microstructure ofreceptive fields of single units in the visual somatosensory, somatosensory, and motor systems were assayed.

Once again the results of these experiments yielded a good deal of data (some 40 papers), published in the Journal of Neurophysiology, Brain Research, Experimental Brain Research, Electroencephalography, and Clinical Neurophysiology and Experimental Neurology, which are interesting in their own right. However, as in Theme II, interpretation (and in some instances controversial interpretation) became necessary. One major controversy centers on whether the sensory specificity of the “association” cortex of the parietal, occipital, and temporal lobes is due to its transcortical input via connections from the related primary sensory cortex, or whether the specificity is to be ascribed to an output which operates downstream on the primary sensory systems. I was able to make massive disconnections, some of which appeared to be complete, between the primary sensory systems and the inferotemporal cortex involved in visual discriminations. None of these disconnections produced lasting deficits in sensory discriminations and this led me to propose the output hypothesis. Controversy hinged on whether the disconnections were in fact total: even a small remnant of connectivity could possibly be sufficient to mediate an input. The facts are reviewed in the paper “The Role of Cortico-cortical Connections” (Pribram, 1986a).

Theme IV: Relevance of the Research Results to Humans

The research program began with the aim to clarify the brain mechanisms involved in cognitive, emotional, and conative (involving the intention to act) processes in humans. The final research phase of the program therefore had to address the relevance of the results of the nonhuman primate research, in which some 1500 monkeys were used, to human neuropsychological findings. Since my early days in the neurosurgical clinic, electrical recordings of event-related scalp potentials, computerized tomography, and nuclear magnetic resonance imaging (MRI) techniques have been developed to aid in the localization of brain pathological conditions. A major task ahead is to compare the results obtained with these techniques with those obtained in monkeys.

Due to the prodigious advances in information processing technology, recordings of the running electrical brain activity show great promise, as well. Differences in patterns can reflect individual differences in character traits and differences in conscious states. To the end of exploiting these possibilities, my laboratory was recently fitted with a 128-electrode recording capability. In addition, my colleagues and I have devised several new methods for quantifying the spatiotemporal dynamics of EEG. Development of these methods was motivated by watching computer-generated animations of EEG voltage recordings. These animations contain a wealth of information about the rapidity (about 100 per second) of change in the patterns of voltages observed across the surface of the scalp. We quantified these spatio-temporal dynamics as scalars, vectors, and cluster analytic plots of EEG activity and have obtained initial findings suggesting that the techniques will prove useful (Pribram et al., 1996).

Theme V: Theoretical Interpretations of the Research Results

The laboratory research has yielded many unexpected results. These results have dramatically changed my views from time to time and posed, as critical to further research, problems which I had thought I could ignore. Much of the theoretical work which has engaged me has stemmed from these surprises.

Discoveries

Karl Popper claims that science is based on conjecture and refutation, and Karl Lashley was always comfortable when he operated in this mode. My own research has proceeded in a more haphazard fashion (see Pribram, 1982). Despite the planning represented by the themes described earlier, my actual research has been a search which stemmed from problems and paradoxes (such as unexpectedly finding relatively direct sensory inputs to the motor cortex) rather than from well-formulated conjectures or hypotheses.

Theses there were, but only rarely did I derive single, testable hypotheses with experiments designed to confirm or disconfirm. Rather, I followed the rule that several more or less clearly defined alternatives presented themselves when the thesis, that is, the reasons for performing the research, became clear. I designed experiments to find out which of the alternatives fit the data I had obtained. Sometimes the data fit none of the alternatives, the thesis itself was found wanting, and new directions had to be taken. Often these new directions stemmed from attempts to systematize the data already obtained and to develop an appropriate frame for sorting and classifying them.

Whatever the merits or deficiencies of this approach, it is shared by many biologists. Claude Bernard, when asked how he proceeded in the laboratory, answered that he simply asked nature some questions. By adopting this perspective, the yield of my research has been substantial and I made many discoveries which might not have been uncovered by a more rigid approach. Some of these discoveries are detailed below.

The Functions of the Frontolimbic Forebrain

The Limbic Forebrain. Early research results led me to redefine the boundaries of the limbic forebrain (also called the olfactory brain) which had hitherto included only the hippocampal and cingulate gyri by establishing the relationship between limbic cortex and visceroautonomic activity (see Pribram & Kruger, 1954).

Based on the earlier work of Warren McCulloch, Percival Bailey, and Gerhardt von Bonin, I established by strychnine neuronography and by electrical stimulation and histological examination, the interrelationship between the amygdaloid complex and the surrounding orbitofrontal, anterior insular, and temporal polar cortex and the direct connections of all of these to the hypothalamus (see Pribram et al., 1950; MacLean and Pribram, 1953; Pribram and MacLean, 1953).

The work of Arthur Ward and Robert Livingston had shown that visceroautonomic responses were obtained from electrical stimulation of the cingulate gyrus and orbitofrontal cortex. With B. R. Kaada and J. A. Epstein (see Kaada et al., 1949) I extended these results to the anterior insula, temporal pole, and amygdala. Initially, this finding was resisted as being due to artifact—a Nobel laureate indicated to John Fulton that he thought our results were due to inadvertent stimulation of the dura—after all, we knew that the hypothalamus was the “head ganglion” of that system. Fulton stuck by me and published our findings. Within 2 years, most of the graduate students in physiology at Yale were doing their theses on limbic related topics.

Thus, the amygdala and its surrounding cortex were shown to be part of the limbic forebrain, which, as noted above, had previously included only the hippocampal and cingulate systems. Further, an entire extent of mediobasal motor cortex—which included the periamygdaloid cortex, the temporal and the adjacent anterior insular, the orbitofrontal, medial frontal and anterior cingulate cortex—was discovered whose primary function is to regulate visceroautonomic functions (Pribram, 1961).

The Anterior Frontal Cortex and Limbic Forebrain.Next I established the fact that the far frontal cortex is the “association” cortex for the limbic forebrain. This accounted for the psychosurgical effects of frontal lobotomy. Using the delayed response and delayed alternation techniques I extended the work of Carlyle Jacobsen and Henry Nissen, who had shown that resections of far frontal cortex disrupted performance on these tasks. I found that resections of the various structures composing the limbic forebrain (hippocampus, amygdala, cingulate cortex) also disrupted performance of delayed alternation (Pribram et al., 1962). By contrast, resections of the cortex of the posterior cerebral convexity failed to disrupt performance on these tasks; if anything, monkeys with such resections tended to perform better than their unoperated control subjects (Pribram and Miskin, unpublished results).

These findings, and results of anatomical experiments which showed that the organization of the projections from the dorsal thalamus to the anterior frontal, peri-rhinal, and cingulate cortex differed substantially from the organization of the projections to cortex of the posterior cerebral convexity (Pribram, 1958a, b), indicated that the anterior frontal cortex can be considered to be intimately related in both structure and function to the limbic forebrain. This relationship between the anterior frontal cortex and the limbic forebrain was quickly recognized to account for many of the changes in “character” produced by frontal lobotomy in humans.

Neurobehavioral and Psychophysiological Analyses of the Functions of the Frontolimbic Forebrain. In addition to the effects on the performance of delayed alternation, my students and I showed that amygdalectomy affected a set of behaviors I labeled the four F’s: Fighting, Fleeing, Feeding, and Sex. Aggression—fighting—was assayed in a dominance hierarchy and shown to be dependent on the immediate (48 hour) interaction between the amygdalectomized monkey and his next dominant neighbor (Rosvold et al., 1954). It is as if the familiarization process during which relative dominance becomes established had to be repeated anew with every encounter.

Fleeing was examined in a conditioned avoidance procedure. Not only amygdalectomy but all limbic and anterior frontal resections markedly altered avoidances, although the escape (pain) threshold was unaffected (Bagshaw and Pribram, 1968; Pribram and Weiskrantz, 1957). It is the memory of the familiarity with pain, perceived as fear, that is affected, not sensitivity.

A large number of animal experiments were done to measure the effect of food deprivation on the amount eaten, the effect of the amount of food used as reinforcer (size and number of food pellets) in determining the rate of lever pressing, and the amount of food ingested when the animal had unlimited access. Amygdalectomized animals (monkeys, dogs, rats) ate more than their controls but deprivation had very little effect on the amount eaten, nor did changes in the quantity of reinforcer (Schwartzbaum, 1960, 1961). The increase in the amount eaten proved to be the result of eating long after control subjects were satiated (Fuller et al., 1957). Satiation proved to be akin to familiarization in that memory of what had just been eaten influenced further eating.

I did not perform any formal experiments on the effects of amygdalectomy on sexual behavior. But informal observation and a careful review and personal observation of the work of the Baltimore, Washington, and UCLA groups led to the conclusion that the degree of familiarization with the situation in which sexual behavior takes place (as well as between the sexual partners) is a potent variable in determining the change in sexual behavior that results from amygdalectomy (Pribram, 1960).

It took a quarter of a century of experimental analysis to reach the conclusion that familiarization is the common denominator in disturbances produced by amygdalectomy. Early on, it became apparent to me that the four F’s were related to each other in some special way. In lay terms, fight, flight, food, and sex were instincts. But the term instinct had become suspect in experimental psychology because of the lack of an agreed upon definition as demonstrated by Frank Beach’s presidential address, titled the “De-scent oflnstinct,” presented to Division 3 of the American Psychological Association. Instead, ethologists had substituted “species specific behaviors.” But this concept somehow failed to capture the spirit of what is meant by instinct. Human language is species specific and has recently been labeled an instinct, but that label departs considerably from earlier ones.

What makes the four F’s so interesting to us—whether they are exhibited by birds, bees, or nonhuman mammals—is not only that we all “do it” but that we all do it in a somewhat similar fashion. Rather than being species specific, instincts such as the four F’s are species-shared behaviors. The question therefore arose, “just what is the property that is disturbed by amygdalectomy and shared by the four F’s?” In order to answer this question experimentally, I decided to take a long chance and first ask another: What might it be that is not shared, that is, what are the limits of the impairment produced by amygdalectomy? As almost always, nature answered the question that I posed in a surprising fashion.

I chose to examine monkeys’ responses on a set of stimulus equivalence problems in which the monkeys were trained to choose the lighter of two greys and tested on trials in which the absolute values of the greys were changed (Schwartzbaum and Pribram, 1960). Behaviors exhibited in such situations could not be labeled as instinctive, yet equivalences characterize the reinforcing properties of various food and sex objects. In a similar vein, equivalences characterize the deterrent properties of various agonists to be aggressed against or avoided.

Over a decade, with different collaborators [Jerome Schwartzbaum (see Schwartzbaum and Pribram, 1960), Eliot Hearst (see Hearst and Pribram, 1964a, b), Muriel Bagshaw (Bagshaw and Pribram, 1965) and Robert Douglas (Douglas et al., 1969; Douglas and Pribram, 1969; Pribram et al., 1969)], I undertook a series of experiments on amygdalectomized monkeys. The results of these experiments demonstrated first that, indeed, equivalence was disrupted by amygdalectomy, whereas stimulus generalization remained intact (generalization is disrupted by resections of the posterior cortical convexity). Second, disruption of equivalence occurs because amygdalectomized monkeys treat an episode in their experience as novel whereas control monkeys respond to the same experience as familiar.

Equivalence thus depends on treating an episode—a situation—as familiar. The results of the experimental analysis were consonant with observations made in the clinic where patients with epileptogenic lesions of the amygdala experience déjà vu and jamais vue phenomena. Further analysis of these experimental results indicated that familiarity resides in the context within which the episode is experienced (Pribram, 1991, pp. 217,233, and Appendix C).

The changes in dominance and in avoidance produced by amygdalectomy can be understood as deficiencies in familiarization: the monkey’s position in the dominance hierarchy is no longer familiar after the resection, and reestablishing a position is impaired by failures in the familiarization process. The effects of deprivation and of changes in the amounts of food used as reinforcer depend on previous experience, that is, being familiar with the sensations produced by deprivation and “recalling” the ordinary, familiar amount of food used as a baseline reinforcer. And the effects of amygdalectomy on sex in the UCLA study turned out to be dependent on territoriality: sexual behavior, which is ordinarily restricted to certain familiar places and times, is now displayed over a much larger range of situations (Pribram, 1960).

At first glance these results regarding familiarization appear to be too cognitive, too devoid of the gut feeling which is imparted by the concept instinct. But while I was engaged in the series of experiments on equivalence, I was fortunate to be introduced to Eugene Sokolov by Alexander Romanovich Luria. In 1960, Sokolov and Luria came to my newly established laboratory at Stanford and stayed for two weeks. Sokolov had demonstrated that an orienting reaction would occur when a stimulus was omitted from a regular series and even when the intensity of a repetitive stimulus was suddenly reduced. This demonstrated that a representation, or a neuronal model of the series, had been constructed against which the change was perceived as novel.

Aside from the importance of demonstrating that neural representations of stimulus events exist, to me, the intriguing aspect of Sokolov’s experiments was that he used visceroautonomic indicators in his experiments. What we needed to do was to replicate his experiments both with humans and with amygdalectomized and control monkeys.

Muriel Bagshaw, who as a medical student worked with me at Yale and was at this point on the pediatric faculty at Stanford, helped implement the execution of such experiments. On the basis of my earlier experiments, which showed the amygdala to be the focus of a forebrain system controlling visceroautonomic responses, we predicted a change to occur in the rate of habituation of visceroautonomic responses in the Sokolov paradigm. Much to our surprise, we found that visceroautonomic responses were almost totally wiped out and habituation of the behavioral aspects of the orienting reaction failed to occur (Kimble et al., 1965; Bagshaw et al., 1965; Bagshaw and Benzies, 1969; Bagshaw and Coppock, 1968). Together, these results indicated that the familiarization process underlying behavioral habituation is dependent on the occurrence of visceroautonomic responses to the stimulus. I concluded that the visceroautonomic components of orienting were important in rapidly familiarizing novel events. Without these visceroautonomic responses, rapid familiarization did not occur (Pribram et al., 1974). I concluded, therefore, that William James’ theory of emotion—that feelings were constituted of a “report” to the brain of a body (especially visceral) response to a situation—had to be modified to take into account the matching of such a report to a representation, a neuronal model in Sokolov’s terms, of previous reports in similar situations. It is a mismatch that leads to the experienced emotion, not the report, per se.

The experiments using visceroautonomic indicators to track the habituation of the orienting reaction were extended, with Luria, to human patients with far frontal lesions with results essentially the same as those obtained with amygdalectomized animals. We also extended the inquiry to the effect of frontolimbic resections on classical conditioning to show its dependence on this occurrence of visceroautonomic responses (Bagshaw and Coppock, 1968). Similar results were obtained by James McGaugh in a long series of conditional avoidance experiments. His aim was to identify the variables critical to consolidation of the memory trace.

The Hedonic, Protocritic Aspects of Sensation and the Frontolimbic Forebrain. Having demonstrated frontolimbic regulation ofvisceroautonomic activity and its importance to the familiarization process, I wondered whether regulation was limited to the interoceptive “world within.” After all, it is exteroceptive stimuli that, in our experiments, induced habituation. I therefore set up a new series of experiments to answering the question: Which class of exteroceptive stimuli, what sorts of sensory input, are processed by the systems of the frontolimbic forebrain?

Muriel Bagshaw and I, while still at Yale, had examined taste threshold discrimination (using bitters) because of its relation to food intake and showed it to be disrupted by resections localized to the anterior portion of the planum temporalis just forward of the primary auditory input area (Bagshaw and Pribram, 1953). After resections of the temporal pole, monkeys would repeatedly eat meat (hot dogs), something control monkeys do not do (Pribram and Bagshaw, 1953). Thus, the anterior portion of the planum temporalis was shown to serve as the primary receiving cortex for taste while the temporal polar cortex, so close to the olfactory input, serves a higher level of gustatory processing. The older concept of the limbic system as an olfactory brain was shown, therefore, not to be totally discarded.

In the spinal cord, tracts conveying exteroceptive pain and temperature run together. It seemed reasonable to ask, therefore, whether these strange bedfellows continue to travel together in the forebrain. With my daughter Joan, Bagshaw and I showed that pain threshold was unaffected (Bagshaw and Pribram, 1968), but in experiments with Lawrence Weiskrantz, avoidance conditioning was shown to be disrupted by all resections that invaded the far frontal or limbic formations, including amygdala, hippocampus, and cingulate cortex (Pribram, 1954b; Pribram and Weiskrantz, 1957).

Next, experiments were undertaken to investigate whether the structures found to be critical in the maintenance of pain-related avoidance behavior were also critically involved in temperature discrimination. Tests were performed and found to be disrupted by resections and electrical stimulations of the orbitofrontal cortex and the amygdala. No such disruption was seen after resections or electrical stimulations of parietal cortex (Chin et al., 1976).

I summarized these findings with a proposal that is derived from a distinction made by Henry Head for peripheral nerves: epicritic sensations display local sign (i.e., can be accurately localized in time and space); when local sign is absent, the sensations are described as protopathic (original+ pathos). For central processing, the terms hedonic or protocritic are more appropriate. The proposal states that the frontolimbic forebrain processes the hedonic, protocritic aspects of sensation, whereas the systems of the cortical convexity process the epicritic aspects (Pribram and McGuinness, 1975; Pribram, 1977).

The Functions of the Posterior Cortical Convexity

Sensory Specificity in Cognition and the Posterior Cortical Convexity. In another part of the research program, I was able to show that the cognitive aspects of epicritic processes were dependent on the sensory specificity of restricted regions within the posterior association cortex of the cortical convexity. The cortical terminations of epicritic sensory input were well known when this program of research was initiated. However, at that time it was thought that the expanse of cortex lying between the primary sensory receiving areas served a purely “associative” function. Thus the sensory specificity of agnosias found in human patients was thought to result from lesions of the association cortex which invaded the adjacent primary sensory cortex as well.

The experiments undertaken with Josephine Semmes and Kao Liang Chow, using the multiple dissociation technique, demonstrated that, in the monkey, no such invasion of primary sensory cortex was necessary to produce the sensory deficits. In addition to the cortical systems involved in taste already described, a nonprimary area specific to the tactile sense, another specific to hearing, and a third specific to vision, were identified (Blum et al., 1950).

An extensive series of experiments, which engaged the interest and participation of Mortimer Mishkin, centered on the functions of the inferotemporal cortex, the area shown to be specific to vision (Mishkin and Pribram, 1954; Pribram and Mishkin, 1955; Mishkin, 1954; Mishkin and Hall, 1955). Until this discovery, the temporal lobes were thought to be totally devoted to hearing; visual defects following temporal lobe lesions were thought to be due to involvement of the optic tracts or radiations. It took more than two decades of demonstration and publication before the role of the inferotemporal cortex in vision was accepted as it is now. The results of this series showed that visual sensory functions such as threshold and detection remained essentially intact; resections produced marked deficits whenever selections among visual inputs were demanded.

Electrical recording of local field potentials led to similar conclusions. Recordings made from the primary visual cortex were sensitive to changes in number and kinds of features that characterized the input. Recordings made from the inferotemporal cortex were sensitive to variables that influenced selection or choice, especially when choice had to be made among ones that share features (Rothblatt and Pribram, 1972; Nuwer and Pribram, 1979; Bolster and Pribram, 1993).

Selection was interpreted to be the rudiment of the cognitive process underlying comprehension. [The experimental results that formed the steps leading to this interpretation are detailed in Lecture 7 of Brain and Perception; Pribram (1991).] When comprehension is disturbed by a brain lesion in humans, the identification of objects is impaired, which results in an agnosia.

Efferent Control over Sensory Input. One of the main motivations of the research undertaken at Stanford was the overriding need for demonstration of top-down processing in the brain and nervous system. In psychology, computer science, and linguistics, as in cognitive science in general, top-down processing is assumed and essential. In the brain sciences, however, bottom-up processing was (and is) generally acknowledged as sufficient for constructing theories of function. However, Hagbarth and Kerr (1954) had shown efferent control over tactile receptors and efferent control over muscle spindles had also been shown during the 1950s. Thus, in a series of experiments, D. N. Spinelli, J. H. Dewson, and I (Spinelli et al., 1965; Spinelli and Pribram, 1966; Pribram et al., 1966; Spinelli and Pribram, 1967; Reitz and Pribram, 1969; Gerbrandt et al., 1970; Spinelli and Weingarten, 1966; Dewson, 1968) demonstrated a ubiquitous top-down corticofugal control from sensory specific “association” cortex over sensory input, control that extended as far down as the retinal and auditory receptors.

Perceptual Constancy. Experimental evidence was provided to show that, in vision, size constancy is a function of the perisensory system which immediately surrounds the sensory receiving cortex. In an initial experiment, together with Robert Anderson, I showed that object constancy was not related to the functions of the frontolimbic forebrain (Anderson et al., 1976; Pribram et al., 1977). In the complementary study, carried out by Ungerleider and me size constancy was shown to be disrupted by a combined lesion of the pulvinar of the thalamus and the pre- and peristriate cortex (Ungerleider et al., 1977). Following such lesions monkeys responded to the size of the retinal image and did not take distance cues into account.

The results of these experiments indicate that at least one form of constancy is dependent on the perisensory visual system. Electrical stimulation of this system produces eye movements. Object constancy is likely, therefore, to depend on eye movements which produce a series of related sensory images. Processing these related images results in constancy. Based on these and other results, a theory of object perception was modelled in terms of symmetry groups (Pribram and Carlton, 1987) and amplified in Brain and Perception (Pribram, 1991). I am, at present, extending this model to account for the variety of reference frames, attained by transformations of coordinates, that account for the variety of perspectives with which we encounter our conscious experience.

Reciprocity between the Functions of the Frontolimbic Systems and Those of the Cortical Convexity. Mortimer Mishkin and I (in unpublished studies) demonstrated that reciprocity exists between the functions of the frontolimbic formations and those of the cortex of cortical convexity. Resections of the frontolimbic cortex actually speed the learning of sensory discriminations, while making the learning of delayed alternation well nigh impossible. Resections of the cortex of the posterior convexity actually speed the learning of delayed alternation, making the learning of difficult sensory discriminations well nigh impossible.

This reciprocity was also demonstrated with electrophysiological techniques. Recovery cycles in the visual system were shortened by electrical stimulations of the inferior temporal cortex and the putamen and lengthened by electrical stimulations of the frontolimbic forebrain and the caudate nucleus (Spinelli and Pribram, 1966). The inhibitory surrounds and flanks of receptive fields of neurons in the lateral geniculate nucleus and in the primary visual cortex were made larger by electrical stimulations of the systems of the posterior convexity and made to disappear by stimulations of frontolimibic systems (Spinelli and Pribram, 1967; Lassonde et al., 1981).

Feature Encoding by Neurons in the Visual Cortex. Having utilized plots of receptive fields in the studies on reciprocity, I became interested in classifying the properties of visual receptive fields. Initially with Nico Spinelli and Bruce Bridgeman (Spinelli et al., 1970), and later with M. Ptito and M. Lassonde (Pribram et al., 1981), I attempted to classify “cells” in the visual cortex. This proved to be impossible because each cortical cell responded to several features of the input such as orientation, velocity, and the spatial and temporal frequency of drifted gratings. Furthermore, cells and cell groups displayed different conjunctions of selectivities which included: (1) tuning to auditory frequency, (2) whether a stimulus property had been reinforced, and (3) whether a particular response had been made on a prior occasion. Furthermore, such properties as simple and hypercomplex could occur in the same recording from single cells. I concluded that cells were not detectors, that their receptive field properties could be specified, but that the cells were multidimensional in their characteristics (see Pribram, 1991, Lectures 1 and 2).

Thus, the pattern generated by an ensemble of neurons is required to encode any specific feature, as indicated also by Vernon Mountcastle’s work on the parietal cortex and Georgopoulos’ data on the motor cortex. The assumption that single neurons serve as feature detectors or channels therefore, has to be abandoned. Classification of receptive field (network) properties rather than of cells is more appropriate.

When a spike train becomes stationary, without a temporal change in the probability density of the occurrence of spikes, an analysis based on a random walk with drift is potentially relevant. An early study by G. L. Gerstein and Benoit Mandelbrot (1964) indicated that a model based on a random walk with positive drift yields an excellent fit to experimental data of interspike intervals recorded from spontaneous neural activity. There are, therefore, theoretical and experimental reasons to believe that a model based on the first-passage time of a random walk with positive drift realistically describes the process that generates spike-train statistics. We investigated whether, according to the model, different stimulus features would differentially influence the initiation of a spike.

The model implies that one factor is a boundary condition or “barrier height” that reflects the amount of depolarization necessary for the spike to occur; the second is “drift rate” which reflects the rate at which repolarization proceeds. We found that the orientation of a visual stimulus affects the boundary condition; its spatial frequency affects the drift rate (Berger et al., 1990; Berger and Pribram, 1992; reviewed in Berger and Pribram, 1993).

The Functions of the Peri-Rolandic Central Cortex

Gabor Functions in the Somatic-Sensory Cortex. At Radford University, I have available only rats and humans. Surprisingly, we quickly obtained fabulous spike trains from the somatosensory cortex of the rats and immediately set to work to extend findings from visual neurophysiology. Joseph King and I, with two graduate students in engineering, investigated receptive fields in the somatosensory “barrel cortex” of the rat obtained by stimulation of their vibrissae. We rotated grooved cylinders to stimulate the rats’ whiskers. The spatial separation between the grooves were different on different cylinders and the cylinders could be rotated at different speeds. Our results were plotted as surface distributions of excitation in dendritic receptive fields and as neuronal population vectors (King et al., 1994; SantaMaria et al., 1995). A computer simulation of our results showed that, according to the principles of signal processing, the somatosensory surface distributions recorded in these circumstances were readily described by Gabor-like functions much as in the visual system, unambiguously indicating that processing can occur in a space time constrained spectral domain.

The Sensory Nature of Motor Control. The finding of a mediobasal motor cortex and the involvement of motor control in the production of object constancy inspired me to look more closely at some aspects of the functions of the classical motor systems.

While at Yale in 1952, quite by accident I discovered direct cutaneous and proprioceptive inputs to the precentral motor cortex. With a postdoctoral student and neurosurgical colleague, Leonard Malis, I had developed and perfected an apparatus to study the brain electrical potentials evoked by sensory stimulation. Together with a graduate student, Lawrence Kruger, Malis placed electrodes on the cortex of a monkey. I had earlier opened the skull to expose the central Rolandic area of the cortex, but had left to test a group of monkeys with the delayed alternation procedure. Returning, I found Malis’ oscilloscope displaying crisp, large electrical responses every time the sciatic nerve was stimulated. We were ecstatic. For almost 2 years we had waited for the oscilloscope, a DuMont, the first to be built for use in neurophysiology and designed by Harry Grundfest of Columbia University. Grundfest received the initial production model; we received the second. Finally we were able to do the experiment we had planned.

Our joy was short-lived. I asked where the electrodes had been placed. Malis and Kruger replied in unison, “on the brain, you dummy.” I asked, “but where on the brain?” When I looked, the electrode site was squarely in the upper-middle part of the precentral gyrus. “Artifact,” I exclaimed.

It took a thesis by Kruger and consultations with Clinton Woolsey and Wade Marshall before we all were convinced that indeed the “motor” cortex received afferents directly from the periphery—not via the cerebellum or the postcentral gyrus. I resected these structures in various experiments without producing any change in the evoked response. Only the incitement of spreading depression diminished the response, attesting to the fact that it was not, after all, artifact (Malis et al., 1963; Kruger, 1956).

With Malis and another postdoctoral student and neurosurgical colleague, Joseph Berman, I explored the effects on behavior of extensive resections of the precentral cortex using latch boxes and cinematographic recordings of the behavior of monkeys in a variety of situations. The results of these investigations showed that all movements, defined as sequences of muscle contractions, remained intact. The skill of opening latch boxes was, however, impaired: transition times between movements were markedly increased. This increase in transition time was specific to the latch box situation; it was not present in more ordinary circumstances such as climbing the sides of cages, grabbing food, and other movements (Pribram et al., 1955–56).

On the basis of these experiments and the importance of the gamma motor system, I concluded that the precentral cortex exerted its effect by changing the setpoints of the muscle spindles involved. Behavioral acts were defined in terms of patterns of these set points which thus resulted from particular consequences of movement. Control over acts had to encode in some way and represent the input resulting from movements rather than control specific muscles or even muscle sequences per se. When this representation was impaired, transition times became prolonged. I was tempted to suggest that the time constant of processing the representation had been extended, a suggestion consonant with a proposal made by Lashley in 1924, who decided that the motor cortex was facilitatory only in its function.

Frequency Encoding of Load in the Motor System. The nature of the encoding process remained opaque to me for almost a decade after completing the initial experiments. Then, a series of events occurred which allowed me to continue the explorations. First, data obtained by Edward Evarts showed that the activity of neurons in the precentral motor cortex was proportional to the load placed on a lever manipulated by a monkey and not the metric extension or contraction of the muscles used in the manipulation. Second, the results obtained in the 1930s by N. Bernstein in the Soviet Union were translated into English. Bernstein had shown that he could predict the course of a more-or-less repetitive series of actions by performing a Fourier analysis of the wave forms produced by spots placed over the joints involved in the action.

These data and analyses fed into the thesis I had by then developed, that certain aspects of cortical function could best be understood by carrying out harmonic analyses. Orthogonal transformations of sensory inputs, such as the Fourier method, were hypothesized to be one “code” used for cortical processing. Together with an engineering student, Amand Sharafat (Pribram et al., 1984), I performed an experiment in which we investigated whether neurons in the cat motor cortex were tuned to certain bandwidths of frequencies of passive movements of their forelimbs. Here, for once, we were testing a specific hypothesis, and the hypothesis was supported by our results. Certain cells in the motor cortex are responsive to the frequency of the movement of a limb. Some of these cells are also selective of phase. The ensemble of cells are therefore performing a spectral analysis of changes produced by the movement. A set of values is computed which, when inversely transformed, represents the load imposed by the situation (the apparatus moving the limb) on the movement. It is this load, not the metric contractions of the muscles nor the sequences involved in movement per se, to which the cells are responding.

Theory

In 1984, on the back page of the front section of the New York Times, a fullpage advertisement had been placed, ostensibly by Omni magazine. In part, the ad read as follows:

In a recent issue, Omni magazine discussed the problems of perception and memory with Dr. Karl Pribram, the Austrian born neuropsychologist who developed the first holographic model of the brain. According to Pribram, the brain encodes information on a three dimensional energy field that enfolds time and space, yet allows us to recall or reconstruct specific images from the countless millions stored in a space slightly smaller than a melon. The Pribram interview is a rich, provocative example of the journalism that has made Omni the world’s leading science magazine.

Provocative, it certainly is. I puzzled as to what it might have been that I had said that would make someone—anyone—even the current “media hype”—attribute to me such a view of “the” brain. Ah, yes. The fields are the receptive dendritic fields of neurons recorded as surface distributions of excitation. And true, a three-dimensional orthogonal (spectral) transformation will enfold a four-dimensional space/time image. Storage capacity in the spectral domain is indeed prodigious. This domain is, of course, only one of several “languages of the brain,” but on the whole, someone had read me better than I had initially read them.

The Omni interview and other similar experiences have made me wonder how it is that my theoretical work has engaged so much popular interest, while discoveries made in the laboratory have often become part of the received wisdom in the neurosciences without acknowledgment even within psychology or neuroscience. The laboratory research has taken up by far the greatest amount of my time and effort, and I therefore welcome this opportunity to show how this research led to theory. For me, theory is data-based and, according to Ajax Carlson’s maxim, I have, whenever possible, obtained in my own laboratory at first-hand the data critical to theory.

What led to this notoriety was the publication of Plans and the Structure of Behavior in 1960, which had a major impact on moving psychology from a strictly behavioristic stimulus–response or response–reward science to a more cognitive science. In that publication, George Miller, Eugene Galanter, and I called ourselves subjective behaviorists. I have already noted how I became involved with Miller after Skinner and I reached an impasse on the problem of the chaining of responses. Clinical considerations, set forth in my contribution to Sigmund Koch’s Psychology as a Science, were instrumental in taking more seriously the verbal reports of introspection than was the custom in mid-century. Thus came about a major divergence from Skinner, who abhorred the use of subjective terminology because of the difficulty of extracting the exact meaning of a verbal communication. This topic was explored at great length at the Center for Advanced Study in the Behavioral Sciences with Ormond van Quine who was writing Word and Object while we were engaged in writing Plans.

The thrust of Plans was that computer programs can serve as powerful metaphors for understanding cognitive processes and the brain processes involved in them. That thrust has been realized—in the neuroscience community as well as in psychology—in conceptualizations such as “information processing” and “motor programs,” which abound.

However, it has also become clear that brain processes are considerably different, even in the fundamentals of their operation, from current serial processing computers. Brain processing proceeds, to a large extent, in parallel, and addressing occurs by content rather than by location. Our mails are representative of location-addressable systems. Content-addressable systems are akin to those in which a broadcast is receivable by a properly tuned instrument, irrespective of location within the broadcast range.

These differences were highlighted in Languages of the Brain (Pribram, 1971), published a decade after Plans. Languages continued to explore the power of hierarchically arranged information processing mechanisms but added the mechanisms of image processing which, although they had been integral to the conceptions proposed in Plans, were not explored because no appropriate metaphor was available at that time. Such a metaphor became available in the early 1960s in the form of optical holograms. Image processing depends on parallel processing and thus is better fitted to some aspects of brain anatomy and function than is serial programming.

One of the consequences of considering parallel as well as serial processing was the introduction of a model for feedforward operations. In Plans, we had made much of hierarchically organized feedback loops. As Roger Brown pointed out in his review of our volume, this left the mental apparatus almost as much at the mercy of input as did the earlier stimulus–response psychologies. In Languages, this deficiency was remedied by showing that coactivation of two or more feedback loops by a parallel input would produce the kind of feedforward organization basic to voluntary control. This proposal was in consonance with similar suggestions put forward by Herman von Helmholtz, Ross Ashby, Roger Sperry, and Hans-Lukas Teuber, but was more specific in its design features than were the other suggestions.

Of the many languages described in Languages of the Brain, the language of the hologram has engendered the greatest lay interest and professional controversy. This controversy has resulted because the optical hologram displays vividly the operations of image processing. Image processing relies on orthogonal transformations such as the Fourier which, because of their linearity, are readily invertible. This means that image and transform are reciprocals, that is, duals of one another, and that transformation in either direction is readily achieved.

The transform domain has properties which make it ideal for storage and for computation. Gigabytes of retrievable information can be encoded in a cubic centimeter of holographic memory. IBM uses such storage devices in the barcode machines that identify grocery store items. Correlations are computed by simply convolving (multiplying) one input with the next. The ease with which such correlations can be computed in this fashion accounts for the value of the fast Fourier transform (FFT) in statistics.

There are other properties of the transform domain which are not so obviously useful but which have had a tremendous theoretical impact. Information becomes distributed in the transform domain so that essentially equivalent images can be reconstructed from any portion of the stored representation. Computer simulations of such parallel distributed processes (PDP) have become commonplace. Such simulations can “learn language” by going through stages similar to those developed during language learning in human infants. The relations between such simulations and neurophysiological and neuropsychological data are reviewed in my book Brain and Perception: Holonomy and Structure in Figural Processing (Pribram, 1991).

Holography was a mathematical invention designed by Dennis Gabor to enhance the resolution of electron microscopy. Optical realizations of the mathematics came more than a decade later. It is important to emphasize that other realizations of the mathematics such as those made by computer (as in the IBM example above) are also holographic. Certain aspects of brain function realize Gabor’s mathematics, to that extent they too can be thought of as holographic.

During the 1970s considerable evidence accumulated that one of the properties of receptive fields of cells in the primary visual cortex can be expressed in terms of Gabor elementary functions. In a 1946 paper, before his invention of holography, Gabor became interested in determining the maximum compression of a telephone message which could be transmitted across the Atlantic cable that would still leave that message comprehensible. To accomplish this, he developed a phase space for psychophysics which had as its coordinates not only space and time but the spectral properties of the process (later to be embodied in holography). Because he used Hilbert’s mathematics as had Heisenberg in developing the formulation of quantum physics, Gabor recognized the elementary functions populating the phase space as quanta of information. Brain and Perception further develops the implications for brain function of Gabor’s quanta of information, and their relation to Shannon’s measure on the amount of information, to PDP theory, and to the data obtained in my investigations.

Recently, together with Mari Jibu and Kunio Yasue (who collaborated on the mathematical appendices to Brain and Perception), I provided some speculations indicating how, at the synaptodendritic level, quantum mechanical processes can operate. Something like superconductivity can occur by virtue of boson condensation over short ranges when the water molecules adjacent to the internal and external hydrophilic layers of the dendritic membrane become aligned by the passive conduction of postsynaptic excitatory and inhibitory potential changes initiated at synapses (Jibu et al., 1996).

The characteristics of the spectral and phase space domains are very different from the familiar space–time dimensions which characterize the image domain. Consider, for example, the dimensions of a spectral representation of an electroencephalographic record: its dimensions are frequency and power. Time is not represented as such; it has become enfolded into the representation of frequency.

I have put together a narrative that describes the importance of these theoretical and laboratory results to understanding the brain/mind relation. The story runs as follows: Take computer programming as a metaphor. At some point in programming, there is a direct correspondence between the programming language and the operations of the hardware being addressed. In ordinary sequential processing configurations, machine language embodies this correspondence. Higher-order languages encode the information necessary to make the hardware run. When the word processing program allows this essay to be written in English, there is no longer any similarity between the user’s language and the binary (on/off) procedures of the computer hardware. This, therefore, expresses a dualism between mental language and material hardware operations.

Transposed from metaphor to the actual mind–brain connection, the language describing the operations of the neural wetware, the connection web, made up of dendrites and synapses and the electrochemical operations occurring therein seem far removed from the language used by behavioral scientists to describe psychological processes. But the distance which separates these languages is no greater than that which distinguishes word processing from machine language.

However, the mind–brain connection is different from that which characterizes the program–computer relationship. The mind–brain connection is composed of intimate, reciprocal, self-organizing procedures at every level of neural organization. High-level psychological processes such as those involved in cognition are therefore the result of cascades of biological bootstrapping operations.

If we take seriously the possibility that at the level of the connection web something is occurring which is akin to a computer being programmed in machine language, the Gabor, or some similar function, fulfills the requirements. This function was devised not only to operate on the material level of the Atlantic cable but also to determine comprehensible telephone communication, the aim of which is mutual minding.

Therefore, at the level of processing in the connection web, a formal correspondence (such as the correspondence between machine language based on a binary code and the operations of computer hardware based on on/off switches) is an accurate and productive philosophical approach that describes this process. Correspondence occurs as a result of algebraic rather than geometric homomorphisms. But the actual procedures are instantiations not only as programming and natural languages but in a variety of media. In music, these instantiations may be a performance, a compact disc, a cassette tape or a radio or television broadcast. The procedures involved thus bind together the various scales of operation by way of reciprocal processes that lead to self-organizing embodiments. At the same time, their mathematical structure defines the process and thus avoids the pitfalls of a promissory materialism and those of an evanescent unspecifiable mentalistic process.

A convenient label for this resolution of the mind–brain issue is isonomy. Isonomy is defined as obeying a set of laws that are related to one another by a change in coordinates. Isonomy, by taking into account levels of instantiation, encompasses epistemological dualisms and pluralisms and avoids the category error of an ontological identity position.

There is thus good evidence that a class of orders lies behind the classical level of organization we ordinarily perceive and which can be described in Euclidean and Newtonian terms and mapped in Cartesian space–time coordinates (see also C.J.S. Clarke, 1995). This other class of orders constitutes distributed organizations described as potential because of their impalpability until radical changes in appearance are realized in the transformational process. When a potential is realized, information (the form within) becomes unfolded into its ordinary space–time appearance; in the other direction, the transformation enfolds and distributes the information, as this is done by the holographic process. Because work is involved in transforming, descriptions in terms of energy are suitable, and as the form of information is what is transformed, descriptions in terms of entropy (and negentropy) are also suitable. Thus, on the one hand, there are enfolded potential orders; on the other, there are unfolded orders manifested in space–time.

Dualism of mental versus material holds only for the ordinary manifest world of appearances—the world described in Euclidean geometry and Newtonian mechanics. I gave an explanation of dualism (Pribram, 1965) in terms of procedural difference in approaching the hierarchy of sciences that can be discerned in this world of appearances. This explanation was developed into a constructional realism. But it was also stated that certain questions raised by a more classical dualistic and identity position were left unanswered.

Two issues can be discerned: (1) What is it that remains identifiable across algebraic transformations? (2) Is the correspondence between machine language (program or musical notation) and the machine or instrument’s operation an identity or a duality? I believe the answer to both questions hinges on whether one concentrates on the order (form, organization) or the embodiments (the media) in which these orders become instantiated (Pribram, 1986b).

Instantiations depend on transformations among orders. What remains invariant across all instantiations is in-formation, a form within. The measure of information (in terms of negentropy, the amount of organization of energy) in Gabor’s terms applies both to the organization of the material wetware of the brain and cable hardware in telecommunication, and to the organization of the mindful communication itself. Thus the in-formation is neutral to the material/mental dichotomy. Surprisingly, according to this analysis, it is a Platonism that motivates the information revolution (e.g., “information processing” approaches in cognitive and neurosciences) and distinguishes it from the materialism of the industrial revolution. Further, according to my perspective, as in-formation is neither material nor mental, a scientific pragmatism akin to that practiced by Pythagoreans, will displace mentalism and dualism as well as materialism as the central philosophical concern (Pribram, 1997).

Thus, by temperament, I need to be grounded in the nitty gritty of experimental and observational results as much as I am moved by the beauty of theoretical formulations expressed mathematically. Therefore, in my opinion, in the 21st century the tension between idealism and realism which characterized the dialogue between Plato and Aristotle and which has been elaborated by Bertrand Russell, will replace that between mentalism and materialism, a new tension that, at its most productive, will lead to new directions in experimentation, observation, and mathematical theory construction in the spirit of a Pythagorean pragmaticism: that is, a tension between an appearance and the potential process that generates it.

These considerations suggest that these new directions in experimentation will change the venue of science. Currently our emphasis is on what Aristotle called efficient causes, the “this causes that.” According to the proposals presented in this essay, 21st century science will supplement searches guided by efficient causation with research guided by Aristotle’s final causes. Searches guided by formal and final causation ask how things and events are put together to be what they are and what they tend to become. This type of research, which is by no means new (especially in thermodynamics and psychophysics), emphasizes transfer functions, transformations that occur as we search for ways to understand relations among patterns at different scales of observation.

Pythagoras examined by experiment and mathematical (thoughtful) description orders at all scales of observations available to him. These scales ranged from universal (spiritual) to those composing musical tones produced by vibrating material objects. There is every evidence, from what has occurred in the second half of the 20th century, that in the coming millennium, a similar range of experience will be the grist of our explorations. At the very center of such endeavors is humankind’s understanding of its relation to the universe—and at the center of this understanding lies the relation between the orders invented or discovered by the operations of that three-pound universe, the brain, and those orders in which it is embedded.

As of now, these are speculative but historically well-grounded proposals that are set forth to provoke 21st century dialogue, research, and theorizing. For my part, in order to give body to the speculations, I need to continue to incorporate current research findings with the earlier ones obtained by me and my students into a systematic theoretical framework sensitive to the ever-changing landscape of data. In order to do this properly, I must, as heretofore, heed Ajax Carlson’s two dicta: (1) Wass iss die effidence? (2) Try to access that evidence first hand. This should keep the explorer in me occupied for a good long while.

Selected Bibliography

Anderson RM, Hunt SC, Vander Stoep A, Pribram KH. Object permanency and delayed response as spatial context in monkeys with frontal lesions. Neuropsychologia 1976;14:481–490.

Bagshaw MH, Benzies S. Multiple measures of the orienting reaction and their dissociation after amygdalectomy in monkeys. Exp Neurol 1968;2:175–187.

Bagshaw MH, Coppock HW. Galvanic skin response conditioning deficit in amygdalectomized monkeys. Exp Neurol 1968;20:188–196.

Bagshaw MH, Kimble KP, Pribram KH. The GSR of monkeys during orienting and habituation after ablation of the amygdala, hippocampus and inferotemporal cortex. Neuropsychologia 1965;11:111–119.

Bagshaw MH, Pribram KH. Cortical organization in gustation (Macaca mulatta). J Neurophysiol 1953;16:399–508.

Bagshaw MH, Pribram KH. Effect of amygdalectomy on transfer of training in monkeys. J Comp Physiol Psychol 1965;59:118–121.

Bagshaw MH, Pribram JD. Effect of amygdalectomy in stimulus threshold of the monkey. Exp Neurol 1968;20:197–202.

Bailey P. Intracranial Tumors. Springfield, IL: Charles C. Thomas, 1993.

Bailey P, Buchanan DN, Bucy PC.Intracranial tumors of infancy and childhood.Chicago: University of Chicago Press, 1939.

Berger DH, Pribram KH. The relationship between the Gabor elementary function and a stochastic model of the inter-spike interval distribution in the responses of visual cortex neurons. Biol Cybernet 1992;67:191–194.

Berger D, Pribram KH.From stochastic resonance to Gabor functions. In: Pribram K, ed. Rethinking neural networks: Quantum fields and biological data. 1993; 47–66.

Berger D, Pribram KH, Wild H, Bridges C. An analysis of neural spike-train distributions: Determinantes of the response of visual cortex neurons to changes in orientation and spatial frequency. Exp Brain Res 1990;80(1):129–134.

Blum JS, Chow KL, Pribram KH. A behavioral analysis of the organization of the parieto-temporo-preoccipital cortex. J Comp Neurol 1950;93:53–100.

Bolster B, Pribram KH. Cortical involvement in visual scan in the monkey. Perception psychophysics, 1993;53(5):505–518.

Bucy PC. The precentral motor cortex. Urbana, IL: University of Illinois Press, 1944.

Bucy PC, Pribram KH. Localized sweating as part of a localized convulsive seizure. Arch Neurol Psychiat 1943;50:456–461.

Chin J, Pribram KH, Drake KH, Green J. Disruption of temperature discrimination during limbic forebrain stimulation in monkeys. Neuropsychologia 1976;14: 293–310.

Clarke CJS. The nonlocality of the mind. J Consciousness Studies 1995;2(3): 231–240.

Dewson JH, III. Efferent olivocochlear bundle: Some relationships to stimulus discrimination in noise. J Neurophysiol 1968;31:122–130.

Douglas RJ, Barrett TW, Pribram KH, Cerny MC. Limbic lesions and error reduction J Comp Physiol Psychol 1969;68:437–441.

Douglas RJ, Pribram KH. Distraction and habituation in monkeys with limbic lesions. J Comp Physiol Psychol 1969;69:473–480.

Fuller JL, Rosvold HE, Pribram KH. The effect on affective and cognitive behavior in the dog of lesions of the pyriform-amygdala-hippocampal complex. J Comp Physiol Psychol 1957;50:89–96.

Fulton JF.Physiology of the nervous system. New York: Oxford University Press, 1949.

Gerbrandt LK, Spinelli DN, Pribram KH. The interaction of visual attention and temporal cortex stimulation on electrical recording in the striate cortex. Electroenceph Clin Neurophysiol 1970;29:146–155.

Gerstein GL, Mandelbrot B. Random walk models for the spike activity of a single neuron. Biophys J 1964;4:41–68.

Grinker RR.Neurology, 3rd ed. Springfield, IL: Charles C. Thomas, 1943.

Hagbarth KE, Kerr DIB. Central influences on spinal afferent conduction. J Neurophysiol 1954;17:295–307.

Hearst E, Pribram KH. Facilitation of avoidance behavior in unavoidable shocks in normal and amygdalectomized monkeys. Psych Rep 1964a;14:39–42.

Hearst E, Pribram KH. Appetitive and aversive generalization gradients in normal and amygdalectomized monkeys. Comp Physiol Psychol 1964b;58:296–298.

Jibu M, Pribram KH, Yasue K. From conscious experience to memory storage and retrieval: The role of quantum brain dynamics and boson condensation of evanescent photons. Int J Modern Phys B 1996;10(13 & 14):1735–1754.

Kaada BR, Pribram KH, Epstein JA. Respiratory and vascular responses in monkeys from temporal pole, insula, orbital surface and congulate gyrus. J Neurophysiol 1949;12:347–356.

Kimble DP, Bagshaw MH, Pribram KH. The GSR of monkeys during orienting and habituation after selective partial ablations of cingulate and frontal cortex. Neuropsychologia 1965;3:121–128.

King J, Xie M, Zheng B, Pribram KH. Spectral Density Maps of Receptive Fields in the Rat’s Somatosensory Cortex. In: Origins: Brain & self organization. Hillsdale, NJ: Erlbaum, 1994:556–571.

Kruger L. Characteristics of the somatic afferent projection to the precentral cortex in the monkey. Am J Physiol 1956;186:475–482.

Lashley KS. Brain mechanisms and intelligence. Chicago: University of Chicago Press, 1929.

Lassonde M, Ptito M, Pribram KH. Intracerebral influences on the microstructure of receptive fields of cat visual cortex. Exp Brain Res 1981;43:131–144.

MacLean PD, Pribram KH. Neuronographic analysis of medial and basal cerebral cortex. I. Cat. J Neurophysiol 1953;16:312–323.

Malis LI, Pribram KH, Kruger L. Action potential in “motor” cortex evoked by peripheral nerve stimulation. J Neurophysiol 1953;16:161–167.

Miller GA, Galanter E, Pribram KH. Plans and the structure of behavior. New York: Henry Holt, 1960. [Also in Japanese, German, Spanish, Italian, and Russian]

Mishkin M. Visual discrimination performance following partial ablations of the temporal lobe: II. Ventral surface vs. hippocampus. J Comp Physiol Psychol1954;47:187–193.

Mishkin M, Hall M. Discrimination along a size continuum following ablation of the inferior temporal convexity in monkeys. J Comp Physiol Psychol 1955;48: 97–101.

Mishkin M, Pribram KH. Visual discrimination performance following partial ablations of the temporal lobe. I. Ventral vs. lateral. J Comp Physiol Psychol 1954; 47:14–20.

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Pribram KH. The cognitive revolution and mind/brain issues. Am Psychol 1986b; 41(5):507–520.

Pribram KH. Brain and perception: Holonomy and structure in figural processing. Hillsdale, NJ: Erlbaum, 1991.

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Pribram KH, Bagshaw M. Further analysis of the temporal lobe syndrome utilizing front-temporal ablations. J Comp Neurol 1953;99:347–375.

Pribram KH, Blehert SR, Spinelli DN. Effects on visual discrimination of crosshatching and undercutting the inferotemporal cortex of monkeys. J Comp Physiol Psychol 1966;62:358–364.

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Pribram KH, Douglas R, Pribram BJ. The nature of non-limbic learning. J Comp Physiol Psychol 1969;69:765–772.

Pribram KH, King JS, Pierce TW, Warren A. Some methods for dynamic analysis of the scalp recorded EEG. Brain Topography 1996;8(4):367–377.

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Pribram KH, Lennox MA, Dunsmore RH. Some connections of the orbito-frontotemporal limbic and hippocampal areas of Macaca mulatta. J Neurophysiol 1950;13:127–135.

Pribram KH, MacLean PD. Neuronographic analysis of medial and basal cerebral cortex. II. Monkey. J Neurophysiol 1953;16:324–340.

Pribram KH, McGuinness D. Arousal, activation, and effort in the control of attention. Psychol Rev 1975;82:116–149.

Pribram KH, Mishkin M. Simultaneous and successive visual discrimination by monkeys with inferotemporal lesions. J Comp Physiol Psychol 1955;48: 198–202.

Pribram KH, Plotkin HC, Anderson RM, Leong D. Information sources in the delayed alternation task for normal and “frontal” monkeys. Neuropsychologia 1977;15:329–340.

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Schwartzbaum JS, Pribram KH. The effects of amygdalectomy in monkeys on transposition along a brightness continuum. J Comp Physiol Psychol 1960;53: 396–399.

Shainberg, Lawrence. Brain surgeon: An intimate view of his world. New York: Lippincott, 1979.

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Spinelli DN, Pribram KH. Changes in visual recovery functions and unit activity produced by frontal and temporal cortex stimulation. Electroenceph Clin Neurophysiol 1967;22:143–149.

Spinelli DN, Pribram KH, Bridgeman B. Visual receptive field organization of single units in the visual cortex of monkey. Int J Neurosci 1970;1:67–74.

Spinelli DN, Pribram KH, Weingarten M. Centrifugal optic nerve response evoked by auditory and somatic stimulation. Exp Neurol 1965;12:303–319.

Spinelli DN, Weingarten M. Afferent and efferent activity in single units of the cat’s optic nerve. Exp Neurol 1966;15:347–362.

Ungerleider L, Ganz L, Pribram KH. Size constancy in Rheusus monkeys: Effects of pulvinar, prestriate, and inferotemporal lesions. Exp Brain Res 1977;27:251–269.

Eugene Roberts

BORN:

Krasnodar, Russia

January 19, 1920

EDUCATION:

Wayne University, B.S. (1940)

University of Michigan, M.S. (1941)

University of Michigan, Ph.D. (1943)

APPOINTMENTS:

Washington University School of Medicine (1946)

City of Hope Research Institute (1954)

HONORS AND AWARDS:

National Academy of Sciences, U.S.A. (1988)

American Academy of Arts and Sciences (1995)

Eugene Roberts reported the discovery of γ-aminobutyric acid (GABA) in the brain in 1950, and then pioneered the immunohistochemical localization of neurotransmitter-specific neural systems at the light and electronmicroscopic levels using antisera to the synthetic enzyme glutamic acid decarboxylase. His work was instrumental in establishing GABA as the major inhibitory neurotransmitter in the vertebrate central nervous system.

Eugene Roberts

Almost immediately after sitting down to write this piece, I felt myself drowning in a Proustian whirlpool of a lifetime of multisensory recollections running back in time in zig-zag fashion. This was not amenable to encapsulation for transmission to a reader. I believe as Picasso did: “There are so many realities that in trying to encompass them all one ends in darkness. That is why, when one paints a portrait, one must stop somewhere, in a sort of caricature. Otherwise there would be nothing left at the end,” (Picasso, cited by Ashton, 1988).

Therefore, at the outset, I undertake a broad brush-stroke, impressionistic approach, presenting a few vignettes from my life that relate to important formative influences. Perhaps one or another of them, in holographic fashion, may reveal me almost in toto.

Escape from Lenin’s Tomb

At the age of 2 years and 9 months, in November 1922, I was brought by my parents from Russia to the United States. My parents were natives of Kerch, a Black Sea port in the Crimea. They were on the move after the Russian revolution and were living in Krasnodar in the Caucasus, where I was born in 1920. In 1921 they moved to Leningrad (now, once again, St. Petersburg), whence they came to the United States, leaving by boat from Lebau, Latvia. The intricate and expensive travel arrangements had been made by my father’s brother, a wealthy real estate developer in Detroit, Michigan. We were met upon docking in New York City by his agent and taken immediately to a train departing for Detroit. In this manner, I was deprived of the classical immigrant experience of passing through Ellis Island, which I saw only recently at a distance from the deck of a ship that my wife and I were taking to England.

In Russia, my father had been a successful merchant with international connections. In the period between the Russian revolution in 1917 and the time we left Russia in 1922, merchants like my father were encouraged by the communist government to import from abroad and to sell on the flourishing black market items such as food, clothing, and soap to help keep the Russian population from starving or freezing to death or dying from inordinate spread of infections. Deciding in February of 1923 that the emergency was over, Lenin’s government arrested and summarily executed all of the merchants like my father and either killed members of their families or sent them into exile in Siberia. By the slim margin of 3 months, our little family had survived and made it to America!

I was an only child and received much love, attention, and encouragement from my parents. I spoke only Russian with them at home and in public as long as they lived, although eventually they spoke English well. This contrasted with friends who were older than I was when they came from Russia, many of whom repressed their knowledge of Russian, hoping to escape the “greenhorn” label so scornfully applied to immigrants in those days. Knowledge of Russian proved to be very useful during three separate month-long visits to the Soviet Union between 1962 and 1975, twice as a member of cultural exchange groups sent by the U.S. Department of State and once as a guest of the Soviet Academy of Sciences.

Dr. Lakoff’s Magic

Shaken by chills and only half conscious, lying on a narrow bed in a dimly lit room in Detroit Receiving Hospital after having suffered a ruptured appendix, on a pre-sulfa drug, pre-antibiotic day in April 1936, I heard my death sentence pronounced to my father, just outside the door: “Mr. Rabinowitch, your son has less than 1 chance in 100 of living. Perhaps we should do a laparotomy.” A blanket of sadness descended upon me and a tableau of things never to be experienced flowed through my mind as though on a receding tide—high school graduation, college, Microbe Hunterian and Arrowsmithian ecstatic commitment to science, a true love of my own. . . . To this day I marvel that I felt no panic or fear. Now in my 78th year, having experienced the thrills and rewards of the scientific chase and deep, reciprocated love, I wonder how it will be when death and I make our final rendezvous.

I remember a kind, roundish face looking down at me while saying to my parents standing alongside, “We must get this boy out of here and into my hospital. He’ll die here. He may die in the ambulance, but we must take that chance.” Twelve weeks later, 1 week after leaving the hospital, having regained 40 pounds and having lost the horrible mirror-repelling jaundiced yellow color I had acquired, I strode jauntily into the office of Dr. Charles Lakoff, arguably the best abdominal surgeon in Detroit, for my only posttreatment visit. Upon seeing me, he turned pale and sat down. I became alarmed and asked him whether or not he was ill. He said, “Eugene, I never thought I would see you walking again.” I replied, “It’s a good thing you didn’t let me know.” As I was leaving the office, the secretary handed me a bill for $50 to be paid “at my convenience.” She told me that Dr. Lakoff thought I should be charged this amount so that my self-respect and dignity would be preserved. They were.

Among the things I learned from this experience was never again to scoff at artistic representations of halos. I saw a halo three times daily for the last 9 of the 11 weeks I lay in the hospital, where Dr. Lakoff was chief of staff. My heart would begin to pound when I heard the sounds signaling the approach of Dr. Lakoff and his entourage. A golden glow enveloped him as he crossed the threshold to my room. Amazed and completely unbelieving, I checked this out daily. It always was there.

In 1960, I made a special trip to Detroit to present to Dr. Lakoff an inscribed volume of Inhibition in the Nervous System and γ-Aminobutyric Acid (Roberts et al., 1960) containing the proceedings of a neuroscience conference which I had organized together with colleagues from UCLA and Cal Tech at the City of Hope the previous year. I asked Dr. Lakoff, then already retired from surgery, how he had known what to do to save my life. He had touched me only to check the drain in my abdomen and to pat me on the head. He had never allowed even a single aspirin to be given me. His only reply was to quote his wife as having said, “Charlie, why do you run around so much? They’ll die anyway.” Then, smiling broadly he said, “You know, more than half of them lived.”

Raphael’s Mantle

My uncle, Raphael Dorfman, husband of my father’s sister, Hannah, lived in the flat next door, the back door of which opened onto the same breezeway as did ours. In Russia he had been a teacher in a gymnasium, a secondary school that differed from our high schools in that the curriculum included material at the level usually covered in the first 2 years of our colleges and universities. Because of restrictions of immigration quotas, he resided in Latvia for several years after his wife and son had come to the United States. He arrived in the depth of the depression and eventually found work as a house painter. He had poor rapport with a son who was absolutely refractory to any kind of intellectual stimulation. However, Raphael found fertile soil in me. He had taught Latin and mathematics in Russia. When I began Latin and algebra in the eighth grade, he took over supervision of my homework and other aspects of my intellectual development.

A trim, athletic man with a full head of wavy luxurious brown hair and a heavy, attractively kept mustache, a cigarette hanging from the right side of his mouth, wearing his beautiful silk shirt with brightly embroidered collar, he would say in Russian, “Well, Eugene, what have we tonight?” By that time I would have done my math problems and Latin assignment. He would give me additional problems to do and various puzzles to solve. He helped me achieve elegance in Latin translation while informing me about life in ancient Rome and life, in general. He also taught me some Yiddish, which was not spoken in my home because my mother came from a Russifled environment in which Yiddish was disdained. I learned to read the Jewish Daily Forward, to which my father subscribed, but I never learned to speak Yiddish.

Raphael’s liberal views made sense to me during the dark days of the Depression. I followed with great interest and approval the inhibitory controls that the New Deal was applying to the unfettered practices of free enterprise capitalism that had led to the depression. To this day, my social and economic views are colored by Raphael’s tutelage. It probably is one of the reasons that I felt comfortable when I came to the City of Hope Medical Center in 1954, which at that time was in transition from being a tuberculosis sanatorium to becoming a cancer hospital and basic research center. At its inception in 1912, the institution had been called the Jewish Consumptive Relief Association and was largely supported by Yiddish-speaking Jews with a socialistic orientation and labor union loyalties. However, only kosher food was served in order to accommodate orthodox Jewish patients who might require it. At that time, many in the San Gabriel Valley called it the “Jew hospital.” By the terms of the original charter of the City of Hope, free care of the highest possible quality would be given to patients without consideration of race, creed, or color. Upon arrival to the hospital, patients were given a brochure addressed “to a VIP” so that they would not feel themselves to be recipients of charity. Money to cover the costs was raised through a system of auxilaries throughout the country and from labor unions. Compulsory free care now has been discontinued because of fiscal exigencies and changes in health care delivery practices. It was beautiful while it lasted and was as empowering to staff as it was to patients.

Raphael must have noticed how much I admired his beautiful shirt with the embroidered collar. Upon my graduation from junior high school he made me a gift of it. I had put on Raphael’s mantle, so to speak. I wore it nightly until it wore out completely. Psychologically, I still am wearing it. When I went to see him in 1943, after having received my doctorate in biochemistry from the University of Michigan, the look on his face said it all. I had achieved his great ambition. My gratitude to him knows no bounds. He had made it possible for me to make a life for myself. He was my archangel Raphael.

Miss André’s Biology Class

Throughout my school years, from grade school through graduate school, I was fortunate in having well-educated, perceptive, and sometimes inspiring teachers. One stood out above all the rest. Miss Elonia André was a biology teacher to whose class I was assigned during my first semester in high school. She was a little, gray-haired lady with metal-rimmed glasses, a kind face that could turn stern, and two little bags, one underneath each side of her chin, that jiggled asynchronously when she said the words, “beetles and bugs.”

Noticing my apparently insatiable curiosity, she invited me to use the well-stocked and well-equipped laboratory to do whatever I wished when classes were over, during which time she sat in her office reading, correcting papers, and occasionally coming into the laboratory to observe my activities or just to chat. I became fascinated with the unicellular creatures found in her hay infusions, particularly with the antics of slipper-like paramecia as they went through their endless, apparently random swims. Wondering how I might perturb their activities, I decided to put a salt crystal at the edge of a drop in which a paramecium was moving about. Not only did it avoid touching the crystal, but the region it avoided increased progressively with time. Although I correctly deduced that the spreading invisible barrier was attributable to the diffusion of dissolved salt away from the crystal, I had no idea as to why the increased salt concentration affected the behavior of the paramecium. I observed dozens of paramecia in this manner and summarized my results in a short paper which I submitted to Miss Andre. She approved it enthusiastically. I loved Miss Andre, I loved biology, and I was “hooked” on science. She had stayed late after school solely on my account. She could have gone home promptly at four o’clock like the other teachers.

Miss André retired at the same time that my class graduated from high school in 1936 and, as one of the editors of the high school annual, the Centralite, I arranged to dedicate it to her. I am writing this, 61 years later, while looking at the wonderful, full-page picture of Miss André on the frontispiece and the dedication to her that I had written: “This Centralite is dedicated to Miss Elonia André, teacher and friend, who since 1896 has communicated the language and love of Nature to students of Central and won a permanent place in their hearts.”

One cold winter day, after completing courses in zoology and comparative anatomy at Wayne State University, I visited Miss André and her sister, both living in retirement in their home in Detroit, Michigan. I remember with great pleasure the cup of hot mulled grape juice and the attractive plate of cookies that they served while they queried me about my life at the university.

I never saw Miss André again. Something of her always will remain with me.

The Most Difficult Letter I Ever Have Had to Write

Dr. Seymour S. Kety

National Institute of Mental Health

National Institutes of health

Bethesda 14, Maryland

Dear Seymour:

I hope this letter isn’t as hard for you to read as it is for me to write. Some time after I had spoken to you and had sent the letter to Bierman refusing his job, he called me and asked me why I had not taken the position which he had offered me. I frankly told him a number of the objections that I had. He gave me assurance that these objections would be overcome and agreed to make his promises concrete by placing them in contract form. In the interim my wife and I had become increasingly apprehensive about working for the government at the present time, and it became apparent that it would be psychologically difficult for us to operate successfully and happily in the present environment, as we imagine it to be. I have, therefore, decided to take my chances in California, fully realizing what a superior scientific opportunity and environment I will be giving up. I am mortified to think of the concern and work that my vacillation will have caused you and only hope that you find it in your heart to forgive me....

I wrote the letter in April 1954. I had been offered and had accepted the job I had wanted above all others. After my discovery of brain-y-aminobutyric acid (GABA) in 1949 and the subsequent realization of its potential importance in brain function, I dearly wanted to spend full time working on it. At that time I was a research associate in the Division of Cancer Research at Washington University in St. Louis and my major obligation was to pursue cancer research. Although the director, the eminent

E.V. Cowdry, had most generously permitted me to work on GABA, I felt guilty at pulling less than my full weight on work of interest to him. As soon as I had learned from friends at the National Institutes of Health (NIH) in 1951 that a Mental Health Institute was being formed in Bethesda, with Seymour Kety as research director, I knew that was where I most wanted to be. With enthusiastic recommendations by scientists on the staff of the NIH and in academe, I was given an excellent civil service appointment by Kety with more than adequate support in terms of personnel, space, and equipment. In 1953 and early 1954 I was making relatively frequent trips to Bethesda to oversee construction of laboratories and installation of equipment.

A dark cloud had descended over Washington and was spreading over the rest of the country, as well. The witch hunts of the Cold War were gaining momentum. On successive visits I could sense progressive tightening of the vise. People were removing books from their shelves at home or turning them upside down. There was a palpable hesitation of individuals to join small groups talking in the halls of the Clinical Center at the NIH, where previously, friendly gregariousness had been the norm. My friends in other branches of government spoke on the phone with me only reluctantly, often suggesting that we talk only when we met face to face. Because I had been cleared by the FBI a number of times during my years on the Manhattan Project and because I could not recall having said or done anything that could be interpreted as subversive, I felt invulnerable to personal attack. Little did I realize that the situation had become a serious test of personal courage and conscience even for the “untainted” ones, somewhat akin to that faced by those who had to decide whether or not to hide or defend Jews during the Nazi years in Germany.

On my next visit to Bethesda, I dropped in to visit the biochemical group at the National Cancer Institute. Among others, I usually visited with an old friend, Vernon Riley. This time he was nowhere to be found. No one, including the head of the biochemistry group, Jesse Greenstein, whom I admired greatly for his scientific ability and personal courage, would tell me the whereabouts of Riley. On inquiry, Greenstein shrugged his powerful wrestler’s shoulders and said, “I don’t know what these guys do. I work 18 hours a day on my research and don’t keep track of them.” Finally, after persistent questioning around the laboratories, I learned that Riley had been summarily ordered off the grounds by a letter signed by Oveta Culp Hobby, Secretary of the Department of Health, Education and Welfare, with no reason being given. In a state of utter disbelief, I went directly to

G. Borroughs (Bo) Mider, director of the National Cancer Institute, whom I had known well at the University of Rochester during Manhattan Project days. His reply to my query as to whether he would demand an explanation for Riley’s dismissal was, “Can we risk the jobs of 3300 scientists for the sake of one?” I said forlornly as I left his office, ’’You’re all in danger if you don’t.” Things went no better at the Mental Health Institute.

I could not quietly allow human beings to be destroyed in this fashion. In spite of this dilemma, with trepidation I still planned to go to Bethesda and turned down an offer at the City of Hope Medical Center in Duarte, California, in a note I sent the Friday of the week during which the preceding incidents had taken place. The following Monday morning I joined others in the medical students’ lounge at Washington University Medical School to watch on television the first day of the Army–McCarthy hearings. There appeared on the screen the hateful, sneering countenance of Senator Joseph McCarthy, going through his act of shuffling papers with supposed lists of subversives while muttering irresponsible accusations of communism and disloyalty. My spirits had fallen to ground zero when the departmental secretary came in and told me that she was holding a long distance call for me from California. Returning to the departmental office, I lifted the receiver to hear from Howard Bierman, “Eugene, why did you turn down my job?” My instantaneous reply was, “I didn’t. I have just accepted it.”

I now have spent more than 43 productive years at the City of Hope and have never regretted the decision I so hastily arrived at. Seymour Kety and I have been good friends ever since. McCarthy was destroyed by the hearings and subsequently drank himself to death. Riley got a job at Memorial-Sloan Kettering Institute and thereafter continued doing good work until his death. Eventually, I was told that the unsubstantiated accusation in Riley’s file leading to his dismissal was that as a student at the University of Chicago, years before, someone had said that he had been seen contributing a few coins for the benefit of Americans who had fought as members of the Abraham Lincoln Brigade of the Spanish Republican Army against Francisco Franco, subsequently the long-time fascist dictator of Spain and Hitler’s ally. Come to think of it, so had I!

Just as I was completing this article, the following item appeared in the Los Angeles Times on April 28, 1997:

Spain

Germany Admits Guilt over Guernica

Germany’s president expressed remorse for the 1937 bombing of Guernica, making his country’s first atonement for what he called “the most terrible atrocities.” Roman Herzog sent a message to survivors of the German bombing raid—immortalized in a painting by Pablo Picasso—one day after the 60th anniversary of the first air attack on an undefended town in history. German warplanes dropped 100,000 pounds of bombs on the civilians of the Spanish town, killing between 1000 and 1650 people.

(Times Wire Reports)

Imagine the letter Pablo Picasso might have gotten from Oveta Culp Hobby had he been working at the NIH in 1954!

A Brief Career Sketch

I received my early education in excellent public schools near my home. I won a scholarship to Wayne State University in Detroit, where I majored in chemistry and minored in biology, and from which I received a B.S. degree, magna cum laude, in 1940. I had become fascinated by organic chemistry and originally had planned to work toward a doctorate in this field at the University of Michigan.

When I first became acquainted with the subject of biochemistry in 1939, the course was not popular with those who wished to make a career in science. It appeared to be a static discipline, concerned in the laboratory largely with medically related analyses of constituents of blood and urine and based on theories that viewed living organisms as combustion engines and on Folin’s hypothesis of the existence of independent exogenous and endogenous types of metabolism. But by 1940, the time at which I had to make a graduate career choice, the situation had been changed completely. Using compounds labeled with the newly discovered stable isotopes deuterium and 15N, Rudolf Schoenheimer and his associates, through brilliantly designed experiments, showed a dynamic state of body constituents to exist: “The simile of the combustion engine pictured the steady flow of fuel into a fixed system, and the conversion of this fuel into waste products. The new results imply that not only the fuel but the structural materials are in a steady state of flux. The classical picture must thus be replaced by one which takes account of the dynamic state of body structure.” This swept me and a number of others with both chemical and biological interests into the suddenly overwhelmingly exciting activities of metabolic biochemistry. This important watershed and the events surrounding it seem largely to have been forgotten. Not one of my last five postdoctoral associates, trained in leading centers in the United States, Japan, and Switzerland and all well versed in techniques of modern biochemistry and molecular biology, recognized Schoenheimer’s name when I brought it up in our first interviews. It is maladaptive and even tragic that such historical disconnectedness should exist. May I recommend for reading, or rereading, a small and beautifully written, posthumously published book by Schoenheimer, The Dynamic State of Body Constituents (Schoenheimer, 1942), and an excellent summary of earlier as well as of some more recent relevant studies by one of his original associates, Sarah Ratner (Ratner, 1979).

During an interview prior to my admission to graduate school, Professor H. B. Lewis, Chairman of Biochemistry at Michigan, told me discouragingly that jobs for biochemists generally were very scarce, but virtually impossible to obtain for “Jewish boys,” unless it was in some “choice” location such as southern Alabama. Noting the look of disappointment on my face, he said, “Well, young man, if you feel that way, come along, anyway.” I did.

During my first year at Ann Arbor, I learned from a variety of unsolicited sources with supporting data that the name Rabinowitch on an application would virtually assure that I would not even be granted an interview for a job, either in industry or in academe. I changed my name to Roberts with that in view, while maintaining my Jewish identity in all other respects. My parents did not take it lightly, but agreed with my decision.

The practicality of this move was borne out in 1946 when I applied for a position at Washington University. At the interview with Prof. Cowdry, there was instant rapport between us and he offered me the job, forthwith, even though early in our conversation I had informed him of my Jewishness. Shortly after I came to work in St. Louis, the senior scientist of our group told me that it was a good thing that it was not evident from my application that I was Jewish. Learning of the opening, the dean of the medical school was heard to have said to Dr. Cowdry, ’’Vincent, please don’t start a synagogue.” Although times have changed, it is important to remember both the scientific and social past so that we may transcend previous limitations and errors.

At the University of Michigan, a scholarship from the McGregor Foundation and a University Fellowship aided me in earning my M.S. degree in 1941 and Ph.D. in 1943. I was fortunate in that my doctoral thesis director, the eminent lipid biochemist, Prof. H.C. Eckstein, left the thesis work entirely to my own devisal and execution, all of which was accomplished in a 9-month period. Titled Factors Influencing the Deposition of “Fat” in the Liver, it focused on problems of biological methylation. My master’s and doctoral theses resulted in three publications in the Journal of Biological Chemistry, a matter of great pride in those days.

Immediately upon completion of my thesis, just as I was about to be drafted into the army, I was commandeered as a civilian to the Manhattan Project at the University of Rochester in Rochester, New York, to work on the toxicology of uranium dusts. Starting from scratch, with little precedent to draw upon, our group quickly developed the technologies necessary for the preparation, dispersal, sampling, and analysis of uranium dusts and studied in eight species of animals the effects of chronic inhalation exposure to different concentrations of dusts of various uranium salts used in industrial processes related to subsequent production of nuclear weapons. Sensitive techniques were devised for monitoring and evaluating the toxicities of these substances. Safe limits for human exposure were established and assiduously enforced so that health records in the plants involved in this work were superior to those in many diverse industries at that time. After multiple experimental repetitions over the years, our original values were declared to be the best available and were voted into law by Congress. In the course of this demanding 80-hour-a-week effort, I found the time to conduct and complete a study on mechanisms of drug-stimulated vitamin C synthesis in the rat. This “extra” work was carried out late at night, usually between 10 PM and 3 AM. It also was published in the Journal of Biological Chemistry.

I left the Manhattan Project in 1946 and joined the Division of Cancer Research at Washington University in St. Louis, spending three months each summer between 1947 and 1954 at the Jackson Memorial Laboratory in Bar Harbor, Maine. I developed a comprehensive program of study of nitrogen metabolism in carcinogenesis in an attempt to localize and characterize the differences between normal and neoplastic tissues that result in the greater growth potential of the latter. Even though it may seem naive by today’s standards, in those prehistoric days when the structure and function of DNA were unknown and its genetic role unsuspected, this work was highly regarded and well funded.

In 1954, I left Washington University to join the staff of the City of Hope Medical Center at the inception of its research endeavor. There I became Chairman of Biochemistry and Associate Director of Research. I assembled a staff of eight independent scientists in the biochemistry department and assisted in recruiting members for other departments. In addition, I organized and staffed electronic and machine shops and a chemical stock room and solicited journals, books, and funds to create and staff a library. Originally housed within the confines of my department, these activities eventually were taken over and enlarged by the central administration to serve the needs of the institution as a whole. After helping set the pattern for the research effort, which consisted of hiring talented and committed young scientists and leaving them alone to seek their own unique destinies while furnishing them with moral and material support, and after having convinced administrators and the board of directors of the validity of this approach to management of basic science research activities, I resigned as Associate Director of Research and the position was not reactivated.

When I came to the City of Hope, I was committed to do research on cancer and the nervous system. In 1949 I had discovered the unique presence of large quantities of GABA in the brain, now known to be the major inhibitory neurotransmitter in the nervous system. Its potential importance in brain function became apparent by 1957, at which time my attention began to turn more toward nervous system function and away from cancer research. In 1968 I was asked separately by two major universities to organize an interdisciplinary division of neurosciences, and planned to leave to accept one of these offers. However, I was persuaded by the Board of Directors of the City of Hope to stay on and organize such a division there. At its peak, the Division of Neurosciences had 13 senior independent scientists, all in different areas of endeavor, and a total staff of more than 70 employees.

In 1983 I requested to be relieved of all administrative duties so that I could devote myself entirely to my own research. I was made Distinguished Scientist and Director of Neurobiochemistry, essentially a one-man department. At the same time, I resigned from all committees and editorial boards, and as advisor to foundations.

My attention currently is focused largely on identifying major inhibitory command-control mechanisms and their nesting at levels of membrane, metabolism, genome, brain, and society.

I also am continuing some work on GABA, particularly on GABA transport, and have expanded my interests to include the effects of steroids and of amyloid on nervous system function. In the latter areas, the work on memory, attenuation of progression of degeneration after spinal cord injury, aging, and Alzheimer disease has aroused considerable interest. When time allows, I work on a book to be entitled The Inhibited Brain.

I have trained a number of American postdoctoral students as well as those from many other countries. Of my awards, I prize most highly election to membership in the National Academy of Sciences and the American Academy of Arts and Sciences and an honorary degree from the University of Florence.

Beyond Measurement: The Pattern Is the Thing

As in everyday life, so in science, ultimately we search for patterns. We are pattern-recognizing creatures. What usually begins as a single-minded devotion to the in-depth analysis of one or a small number of variables leads to questions of how the results might relate to the whole living unit, whether it be cell, tissue, organism, or society. Under primitive circumstances, the survival of individuals and species may have depended on the recognition of similarities of patterns and on the discernment of small differences among similar patterns. We know intuitively what pattern recognition is and recognize it by the relief of anxiety or joy when we experience its occurrence. We also can recognize superior pattern-recognizing abilities in others, whatever the nature of their activities. In the latter context, I am reminded of an incident many years ago when a newly trained pediatrician whom I knew became utterly distressed on failing to diagnose his own child’s illness, which was characterized by a sore throat, a high fever, and general malaise. Upon seeing the child, his mother, whose medical education consisted of raising six children, laughed and said immediately, “Well, of course, the child has measles.” The next morning her diagnosis was confirmed when the tell-tale rash appeared. We have internalized models, often difficult or even impossible to express verbally, to which we constantly are matching environmental patterns that arise from our sensory perceptions.

As I look back over my work of the last 50 years, it becomes clear to me that it can be epitomized as a search for patterns. Among my several biochemical endeavors, the discovery of GABA in brain and the consequent studies of its role in inhibitory processes afforded the best opportunity to begin to seek fundamental patterns in nature. To date, the major conclusion of my pattern search is the following: Progressive disinhibition of tonically inhibited living systems is coupled to increased variability generation in such a manner that the probability of making an optimally adaptive choice of behavior from among those available remains approximately constant over a wide range of increasing force parameters. Healthy living systems operate under conditions of freedom without license (Roberts, 1991).

All living systems are pattern-recognizing or generalizing entities, from single cells to complex human organizations. When a living system, unicellular or international, is presented with a new information pattern in its environment (external and internal), it is activated in a unique fashion. The types of impinging influences and their sequences, intensities, and rates of change result in an activation pattern that is likely to be different from any experienced previously. Even in well-controlled experiments in which single variables are manipulated, it is the change in the pattern of the environment which is the stimulus (stress, pressure, forcing function) for the system. Progress has been made toward establishing a universal law of generalization or pattern recognition that may be helpful in estimating the probability of whether or not an organism will react to a novel stimulus pattern in accordance with consequences associated with previously experienced stimulus patterns (Shepard, 1987; Ennis, 1988).

At all levels of observation, from genomic expression to freeway driving, progressive disinhibition is coupled to increased variability generation in healthy organisms (Roberts and Matthysse, 1970; Roberts, 1976a, 1986c, 1991; Hikosaka and Wurtz, 1983). A released system, like a wound spring, has the tactical advantage over a driven one in that it does not have to overcome the inertia of start-up when it switches from an inactive or minimally active to a fully active state. Metaphorically, metabolically generated energy is used to wind the biological springs. Ever-present, tonically active inhibitory influences, together with phasically active ones, maintain barriers to physicochemical perturbations, so that the interactions within the system in yin-yang fashion produce asymmetric, graded local changes. Transient signals are transduced by a variety of devices at hand to release processes that govern amounts and turnovers of substances, their locations, and their relations to each other.

Coupling exists between the driving force (pressure) and the generation of variability (information-processing capacity) among the subunits that participate in the nest of relations comprising the particular system being considered, i.e., healthy living systems have an expansible capacity for processing information in relation to demand. Paradoxical as it may seem initially, facile traverse of the adaptive functional range largely is made possible by diverse activities of inhibitory (attenuating and/or time-delaying) influences. In the central nervous system (CNS) inhibitory projection and local circuit neurons play crucial roles in information processing (Roberts, 1986a–c, 1991).

I surmise that increases in activities with increases in forcing function occur according to principles of nonlinear dynamics. It would be expected according to the latter concept that with progressively increasing force parameter, each living system considered would show three characteristic behaviors: smooth, periodic (oscillatory), and turbulent (chaotic). With full participation of inhibition and with tight coupling between degrees of disinhibition and variability generation, the region of smooth flow (efficiently adaptive behavior) would extend over a much greater range of force parameters than in their absence (Lorenz, 1963; Rössler, 1976; Mandell, 1983).

When healthy living systems are effectively stimulated, processes are released to operate at rates and for durations that enable them to react adaptively in a manner compatible with their individual behavioral repertoires. Cascades of processes are generated by actions of environmental factors that reduce transmembrane potential and/or interact with specific membrane receptors. Cascades of other processes are released by expression of genetic potential (Ames et al., 1986; Morgan et al., 1987; Saffen et al., 1988). When environmental pressures are increased, the number of such countercurrent cascades and their extents are increased in such a way that the probability of their meshing to give system-typical adaptive patterns tends to remain approximately constant. The relative constancies of structural, compositional, and functional features of cells, tissues, and organs in mature animals under various environmental conditions are indicative of the existence of remarkable biochemical and biophysical servomechanisms which coordinate a variety of complex biosynthetic and degradative pathways and which continuously adjust the rates of flow of substances between the organism and its environment, between extracellular and intracellular compartments of tissues, between cytosol and organelles, and among cytosolic aggregates (molecular ensembles) of individual cells (Schoenheimer, 1942; Roberts and Simonsen, 1962; Ratner, 1979; Goldberg et al., 1983; Goldberg and Walseth, 1985; Wheatley and Inglis, 1986).

Because several response options may be available even to the simplest cell in a particular instance, because the particular choices made among the options often are unpredictable, and because the exercise of options results in functional and structural changes of varying extents and durations, it may be said that creativity and memory exist in every living unit (Tam et al., 1986). Although increasing in levels of complexity, the operations of multicellular organisms in their environments are not different in basic principle from those of single cells.

The Saga of GABA

Patterns of Free Amino Acids in Normal and Neoplastic Tissue

For a number of years, beginning with my joining the staff at Washington University in St. Louis in 1946, I was interested in the study of amino acid metabolism in both normal and neoplastic tissues in experimental animals. Early on, it appeared desirable to determine the composition of pools of nonprotein amino acids and related substances. I anticipated that the patterns of steady-state concentrations of these constituents would reflect characteristics of the tissues in a way that might reveal key metabolic differences among them. However, as in almost every biochemical field at that time, progress was slow and curiosity limited until methods became available that enabled a large number of determinations to be made in a reasonably short period of time. The development of simple and rapidly performed two-dimensional paper chromatographic procedures allowed the detection of microgram quantities of substances for which other adequate microanalytical procedures were not available and made it feasible to survey rapidly the distribution of free or loosely bound amino acids and other ninhydrin-reactive substances in biological fluids. I hastened to apply these techniques for the first time to animal tissues (Roberts and Tishkoff, 1949).

The paper chromatographic procedures furnished tools that were ideally suited for giving simultaneous information rapidly about the maximal number of constituents and, although often employed in a semiquantitative fashion, could give valuable hints about the presence of new materials and indicate which substances should be studied further in particular biological situations. Column chromatographic methods already were being applied extensively, but the procedures, although quantitative, were more timeconsuming and allowed far fewer samples to be examined. In addition, unknown substances were much easier to detect and identify by the paper chromatographic procedures.

As the work developed, it became apparent that the perceptions of the patterns of the spots of the different constituents on the chromatograms as well as their relative sizes and color values were more meaningful than the same data given in printouts of names of the constituents followed by numbers designating the amounts, in bar graphs, or in other forms of data presentation. Most human computers seem to be able to store and retrieve the patterned pictorial information more effectively and to relate it to metabolic events more rapidly than they can deal with the numerical representation of the same information. In general, it appears that the transmittal of some types of numerical information about multivariant situations from nonhuman computers to human recipients would be more effective if the information were transformed into quantitative, pictorial patterns resembling those seen on two-dimensional paper chromatograms! Indeed, recently the visual display of quantitative information has become an object of concerted scientific inquiry.

One of the great advantages of the paper chromatographic procedures, long since discarded in most laboratories, was the easy detection of new substances. For example, employing these methods we detected and identified aminoethylphosphonic acid, the first compound with a carbon–phosphorus bond found in animal tissues (Kittredge and Roberts, 1969). In this instance, the finding of a new spot on a chromatogram led to a new field of phosphorus biochemistry. Surveys of ninhydrin-reactive substances found in members of the major invertebrate phyla have revealed the presence of many unknown substances (Kittredge et al., 1962). Young scientists who may not wish to take part in the frenetic competition that exists in some areas of modern biochemistry and molecular biology may find many years of satisfying and exciting work in studies of such substances.

The earliest observations with the paper chromatographic method showed that, in a given species at a particular state of development, each normal tissue has a distribution of easily extractable amino acids and related substances that is characteristic for that tissue and is remarkably stable to external perturbations (Roberts and Simonsen, 1962). On the other hand, quite similar patterns are found in many different types of transplanted and spontaneous tumors (Roberts and Frankel, 1949; Fig. 1). The latter findings agreed with Greenstein’s generalization (1954) based on enzyme assays: “No matter how or from which tissues tumors arise, they more nearly resemble each other chemically than they do normal tissues or than normal tissues resemble each other.”

Figure 1. Comparison of the free amino acid patterns of mouse liver (1) and epidermis (2) with those found in a transplantable hepatoma (3) and squamouscell carcinoma (4). Extracts obtained from 75 mg of fresh weight of tissue were employed for descending two-dimensional paper chromatography (phenol, right to left; lutidine, bottom to top). Constituents on chromatograms: tyrosine, 1; phenylalanine, 2; leucine and isoleucine, 3; valine, 4; taurine, 5; proline, 6; hydroxyproline, 7; alanine, 8; threonine, 9; serine, 10; histidine, 11; glycerylphosphorylethanolamine and/or [β-alanine, 12; glutamine, 13; glycine, 14; arginine, 15; lysine, 16; glutamic acid, 17; aspartic acid, 18; ethanolamine phosphate, 19; cystine (cysteic acid), 20; glutathione, 21. Reprinted from Cancer Res 1949;9: 645–648, with permission of American Association for Cancer Research.

Employing new techniques of molecular biology, explanations for these findings now are being sought in interplay of expression of genetic potential with transmembrane potential and with second-messenger-initiated cascades.

Discovery of GABA in Brain

Working during the summer of 1949 at the Roscoe B. Jackson Memorial Laboratory in Bar Harbor, Maine, where an unusually good selection of transplantable mouse tumors carried in a number of inbred mouse strains were available for study, I analyzed the free amino acid content of the C1300 transplantable neuroblastoma. I chromatographed several mouse brain extracts for comparison with the neuroblastoma. Much to my surprise, relatively large quantities of an unidentified and previously unobserved ninhydrin-reactive material appeared on the chromatograms. At most, only traces of this material had appeared in a large number of extracts of many other normal and neoplastic tissues previously examined, or in samples of urine and blood. This immediately excited my curiosity.

Upon returning to my laboratories at Washington University in St. Louis, I isolated the unknown material from suitably prepared paper chromatograms. A study of the properties of the substance revealed it to be GABA. I submitted an abstract (Roberts and Frankel, 1950a) reporting the presence of GABA in brain. An abstract reporting the presence of an “unidentified amino acid in brain only” appeared from the Houston laboratory of Jorge Awapara (Awapara, 1950) in the proceedings of the same meeting. Because of a room shortage at the meetings where these findings were reported, I was assigned to share a room with Awapara who knew by that time that the unknown material he had found in brain was GABA. In addition to GABA, work in both of our laboratories had revealed the presence of large amounts of taurine in extracts of many rodent tissues. Awapara and I agreed that my laboratory would continue to work on GABA since I already was deeply engaged in relevant enzymatic studies, while he would put future emphasis on the study of metabolism of taurine. The first complete papers from our laboratories dealing with the occurrence of GABA in brain appeared in the same issue of the Journal of Biological Chemistry.

My identification of GABA in brain extracts was expedited by a report in 1949 that GABA was prominent among the soluble nitrogenous components detectable by two-dimensional paper chromatography in the potato tuber (Steward et al., 1949). This caused me to write semifacetiously in my notebook, “This proves that the brain is like a potato!” Unfortunately, little has happened to the state of the world since that time to change my mind. GABA had been found in nature long before. In 1910, D. Ackermann (Ackermann, 1910; Ackermann and Kutschler, 1910) found it to be produced in putrefying mixtures by the action of bacteria. Subsequently, many reports had been made about the occurrence of GABA and/or its formation in bacteria, fungi, and plants. I was thrilled to receive a letter from Ackermann with congratulations on my first report of the presence of GABA in brain.

The Emergence of a Physiological Role for GABA

For several years, the unique presence of relatively large amounts of GABA in the tissue of the central nervous system (CNS) of various species remained a puzzle. The great neurochemist Heinrich Waelsch once discouragingly remarked that GABA probably was a metabolic wastebasket. My continuing efforts to convince some of the eminent neurophysiologists working at Washington University at that time to apply GABA to various nerve preparations at the end of their planned experiments met with complete failure, even though I brought solutions of GABA personally to their laboratories in the hopes of persuading them to test it.

In the first review on the subject in 1956, written after I had moved to my present position, I concluded in desperation, “Perhaps the most difficult question to answer would be whether the presence in the gray matter of the CNS of uniquely high concentrations of γ-aminobutyric acid and the enzyme which forms it from glutamic acid has a direct or indirect connection to conduction of the nerve impulse in this tissue” (Roberts, 1956). However, later that year, the first suggestion that GABA might have an inhibitory function in the vertebrate nervous system came from studies by T. Hayashi’s group in Tokyo. They found that topically applied solutions of GABA exerted inhibitory effects on electrical activity in the brain. In 1957, from pharmacological studies with convulsant hydrazides, the suggestion was made by K. Killam and associates that GABA might have an inhibitory function in the CNS. Also in 1957, evidence was adduced for an inhibitory function for GABA in studies by E. Florey and co-workers that showed GABA to be the major factor responsible for the inhibitory action of brain extracts on the crayfish stretch receptor neuron. Within a brief period, interest in GABA increased greatly. Research then being carried out ranged from the study of the effects of GABA on ionic movements in single neurons to clinical evaluation of the role of the GABA system in, for example, epilepsy, schizophrenia, and various types of mental retardation. This warranted the convocation of a memorable interdisciplinary conference in 1959 at the City of Hope Research Institute (now the Beckman Research Institute of the City of Hope). It was attended by most of the individuals who had a role in opening up this exciting field and who presented summaries of their work at the meeting.

This first GABA conference was the greatest learning experience of my life. Having spent most of my scientific career in the narrow confines of organic chemistry, classical biochemistry, and the bare beginnings of molecular biology, I was thrust into the world of membranes, electrodes, voltage clamps, neuroanatomy, EEG and seizures, neuroembryology, and animal behavior. I had the privilege of meeting a number of the world’s leading neuroscientists among the participants, a few of whom still are active scientifically and have remained close personal friends. What a mind-boggling intellectual feast! The meeting itself was overwhelming to me. The excitement was pervasive because all of the participants sensed that a new era was beginning. The subject of neural inhibition finally had returned to front stage and center. It was obvious that much of the future progress in the field would depend on interdisciplinary efforts and that we all would have to begin to learn each other’s languages and ways of thinking. At times the proceedings resembled what one imagines might have taken place at the Tower of Babel. However, we all shared the optimistic feeling that we could help each other learn enough so that effective communication soon would take place. For some of us this turned out to be true, and many students in the laboratories of the participants reaped the benefit of the “new enlightenment.” It was a particularly heartening social occasion because approximately 80 individuals from Australia, Canada, England, France, Hungary, Japan, the Soviet Union, and the United States met in enthusiastic amity and forged long-lasting scientific and personal links. As a result of this meeting, I was given the opportunity to organize the first interdisciplinary division of neurosciences anywhere, with a generous allotment of 13 senior positions!

GABA as Inhibitory Neurotransmitter—A Rocky Road

Perhaps the subject of inhibition had languished in the wings for so many years because there was no material basis for it. Inhibitory neurons had not been identified, an inhibitory neurotransmitter had not been isolated and characterized, and postsynaptic sites for neural inhibition had not been shown. It is well to remember that it was not until 1952, 2 years after the discovery of GABA in brain, that the controversy as to whether synaptic transmission in the CNS is largely electrical or chemical in nature was settled in favor of the latter (Eccles, 1982).

It made no difference to me initially whether or not GABA were a neurotransmitter. My goal was the elucidation of its function in the nervous system, whatever it might be. However, I did sense that the “transmitter question” seemed to agitate a number of physiologists. Much skepticism arose with regard to the possible transmitter function of GABA because of the large quantities of GABA present in brain, three to four orders of magnitude higher than those of acetylcholine, the only proven neurotransmitter at that time. It would have been much more acceptable to some if the first identified inhibitory neurotransmitter would have had a more exotic chemical structure than that of GABA. At a later date, the situation was even worse for glycine, the simplest amino acid, which was identified as a putative inhibitory neurotransmitter in the spinal cord. Some time after the legitimization of GABA as an inhibitory neurotransmitter, I received an SOS signal from the discoverers of the glycine phenomenon, M. Aprison and R. Werman, whose findings were being met with much skepticism and even abuse. After visiting their laboratories and becoming thoroughly acquainted with their data, for several years I made it a point in my lectures on GABA to mention the glycine work and to indicate my support for the convincing findings of these excellent scientists. I vividly remember sitting at a symposium in Stockholm near a leading neurophysiologist who kept shaking his head and muttering angrily to himself during Werman’s presentation of the data documenting the inhibitory role of glycine in spinal cord.

The resistance to acceptance of GABA as a naturally occurring neurotransmitter was supported by negative experiments and interpretations, many of which, in retrospect, were technically flawed. At the 1959 GABA symposium (Roberts et al., 1960), statements were made that seemed to rule out a neurotransmitter role for GABA. It finally was remarked by someone that GABA entered the conference as a proud transmitter candidate and left it as a poor metabolite. For example, E. Florey, whose brilliant work had pioneered in the identification of GABA as a factor in brain extracts that exerted inhibitory effects on invertebrate preparations, stated, “Although one likes to ascribe to neurogenic compounds an action on postsynaptic membranes, there is every possibility that they affect intraneuronal processes which in turn control the state of the membrane. At present, it is not possible to decide whether GABA normally occurs outside of nerve cells as a product of secretion (modulator substance). All available evidence speaks, however, against it playing a role as inhibitory transmitter in vertebrates.” Florey made this statement, at least in part, because at that time GABA had not yet been shown to possess most of the “classical” requirements for neurotransmitter, chief among which are proof of identity of postsynaptic action with that of the natural transmitter, presence in inhibitory nerves, releasibility from terminals of identified nerves, and the presence of a rapid inactivating mechanism at synapses. The most critical among these is the first. As aptly stated by P. Fatt, “The characterization of the postjunctional response must logically precede any attempt to identify the transmitter, since the criterion for the identification is its ability to duplicate the effect of prejunctional nerve stimulation.”

Also damaging to GABA’s transmitter candidacy was Florey’s failure to detect GABA in the crustacean nervous system and his report of the discovery of an incredibly more potent inhibitory substance, Factor I. The latter findings unquestionably resulted from a concatenation of technical errors, because enormous concentrations of GABA later were found in inhibitory axons of crustacea and the existence of a Factor I independent of GABA has never been established. Faulty chemical work by H. McLennan led to conclusions similar to Florey’s. Also in the 1959 conference, W. Van der Kloot, discoverer of the blocking effect of picrotoxin on peripheral inhibition in invertebrates, noted, ’’Yet there is a compelling reason to deny that GABA itself is the transmitter. The inhibitory effects always persisted without diminution after GABA was perfused into claws. If there is an enzymatic breakdown of GABA, the disappearance of the molecule is inconspicuous.” The latter statement was based on the mistaken notion that the removal of all neurotransmitters would have to take place by a mechanism strictly analogous to the extremely rapid enzymatic destruction of acetylcholine by acetylcholinesterase at the vertebrate neuromuscular junction. Actually, the case of acetylcholine appears to be an exception. GABA and a variety of other neurotransmitters now are known to be removed rapidly from synaptically active sites by carrier-mediated transport into pre- and postsynaptic neuronal sites as well as into glial cells. Although usually operating effectively as a GABA “vacuum cleaner” in a physiologically coordinated manner with the natural release mechanisms, the GABA transport systems can be more easily overwhelmed with an exogenous flood of GABA than can the cholinergic system with acetylcholine, because acetylcholinesterase is an enzyme with a very high turnover number. Van der Kloot’s notion was derived from an incorrect assumption followed by an inappropriate experiment. D.R. Curtis and colleagues (Curtis et al., 1959) concluded that GABA was “not a specialized inhibitory substance.” This was based on their failure to observe in neurons onto which GABA was applied iontophoretically the hyperpolarization that is known to occur during natural inhibition in cat spinal motoneurons. They stated, “The possible specific inhibitory character of these acids (β-alanine and GABA) is excluded by their failure to produce a hyperpolarization of motoneuronal membranes.” It seems probable that the failure to observe hyperpolarization by the latter workers was attributable to the fact that, in the ingeniously devised coaxial microelectrodes used in their studies, there was sufficient electrical coupling between the barrels so as to preclude detection of the small potentials required to show hyperpolarization. Although glycine probably is the major inhibitory neurotransmitter in ventral regions of the spinal cord, numerous GABAergic synapses have been found immunocytochemically on the somata of spinal motoneurons and throughout the spinal cord, in general.

C.A.G. Wiersma, who had laid the groundwork for the use of crustacean sensory and neuromuscular synapses in quantitative physiological studies, also stated in the 1959 symposium, “At one time it looked as if GABA would meet the requirements of an inhibitory transmitter substance for many places, but in the last year or so it has become more doubtful that this is the case.” This was based on a paper published by G. Hoyle and Wiersma in 1958 in which is found the following statement: “We have applied this substance (GABA) in concentrations of 10–9–10–3 M to several preparations of crayfish and crab opener muscles. It did not produce mechanical inhibition in any of them, nor did it raise the resting potential in muscle fibers in which inhibitory action had this effect.” Although never acknowledged publicly, this result later was found to be attributable to a mislabeling of the bottle from which Hoyle took the substance to be tested. They probably had applied α-aminobutyric acid and not GABA. I personally made this discovery when looking over the chemicals on a shelf in Wiersma’s laboratory in his presence after Hoyle had left Cal Tech to go to the University of Oregon.

In the summary to the whole conference, although conceding the probable existence of true inhibition on ventral horn neurons in the spinal cord and on the crustacean sensory cell, George Bishop, the great collaborator of J. Erlanger and H. Gasser, remarked, “In spite of considerable experimentation and even more extensive interpretation, the position is still tenable that little or no such inhibition, that accompanying a positively oriented impulse and a decrease of resistance of the synaptic membrane, occurs in the cortex of the mammal. Postimpulsive depression resembling refractoriness is on the contrary of very prevalent occurrence there.” The curtain appeared to have been brought down on the candidacy of GABA as inhibitory neurotransmitter!

At a meeting of the Federated Societies held in the spring of 1959, I was approached by Stephen Kuffler and asked by him whether or not I thought there was still a chance that GABA might be a neurotransmitter and whether or not it would be worthwhile to hire a biochemist to work with him and other physiologists on the action of GABA in the crustacean nervous system as part of a team he was going to constitute upon his move from Johns Hopkins to Harvard. My affirmative answer encouraged him to hire E. Kravitz as biochemist for his group. The most convincing evidence for the role of GABA as an inhibitory neurotransmitter eventually was obtained by the Harvard group and by A. and N. Takeuchi in Japan from studies at crustacean neuromuscular junctions. The postsynaptic action of applied GABA mimics exactly that found on stimulating inhibitory nerves. Inhibitory axons contain enormous concentrations of GABA, while less than 1% of these levels can be detected in excitatory nerves. GABA is released from lobster inhibitory nerves in amounts proportional to the number and frequency of stimuli applied to the nerve and is not released by stimulation of excitatory nerves. The enzyme that forms GABA from L-glutamate, glutamic acid decarboxylase (GAD), is preferentially distributed in inhibitory nerves. Synaptically released GABA probably is inactivated by an uptake mechanism that is capable of acting against large concentration gradients. Picrotoxin, a convulsant agent, blocks the inhibitory action of GABA and the natural inhibitory transmitter similarly. Thus, in the crustacean peripheral nervous system GABA possesses impeccable credentials as an inhibitory transmitter, perhaps more convincingly documented than in the case of any other known transmitter at any site of action. Over the years, strong evidence had been adduced from many physiological and pharmacological studies for an inhibitory neurotransmitter role for GABA in the vertebrate CNS. However, the necessary definitive chemical correlative work and release experiments are much more difficult to achieve in the tightly packed vertebrate CNS than in the crustacean peripheral nervous system. Even using the latter, the definitive experiments on release of GABA were formidable, M. Otsuka losing approximately 14 kg in body weight while performing the arduous work required to achieve valid results.

GABA is liberated from presynaptic terminals of inhibitory nerves on dendrites, usually close to the cell body, on initial axon segments, on cell bodies, or on terminals of neurons employing other transmitters. It increases the permeability of membranes to specific ions in such a way as to cause the membranes to resist depolarization. For example, by acting on a particular class of receptors (GABAA), GABA produces an increase in permeability to c1⁻ ions that is measured as an increase in membrane conductance. GABA also produces increases in K⁺ conductance by action on another distinct class of receptors (GABAB) that are not colocalized with GABAA receptors (Bowery et al., 1983). In general, GABA accelerates the rate of return of the resting potential of all depolarized membrane segments which it contacts and stabilizes undepolarized membrane segments by decreasing their sensitivity to stimulation. Thus, at many sites in the nervous system, GABA exercises inhibitory command-control of membrane potential.

Remarkably, GABA alone of the amino acids commonly found in proteins and/or in tissues and body fluids in the free or easily extractable form is electroneutral, bearing no net charge at the physiological pH of 7.3 (Roberts and Sherman, 1993, and Appendix I). The obvious advantage of this property for a neural informational molecule is that it confers the highest probability of successfully traversing the densely packed extracellular synaptic domain between presynaptic release sites and postsynaptic receptor sites (100–200 nM) without becoming coulombically attracted or repelled by charged entities en route. The electroneutrality of the GABA molecule also is resistant to fluctuations of pH in the physiological pH ranges, since the pK₁ (COOH) and pK₂ (NH⁺₃) values are 4.031 and 10.556, respectively. Thus, the number of transmitter molecules released from a nerve terminal as a result of nerve activity in a variety of circumstances would reliably and quantitatively transmit messages from presynaptic nerves to the postsynaptic sites upon which they impinge. With the exception of GABA, all known major neurotransmitters are charged at physiological pH. Glutamic and aspartic acids and glycine are anionic, and acetylcholine, serotonin, norepinephrine, and dopamine are cationic. Numerous structure–activity studies in GABA-responsive systems show that no α-,β-, or ω-amino acid known to occur in any abundance in animal tissues approaches GABA in molar efficacy at the GABAA receptor. Therefore, the noise level created by nonspecific effects at the GABAA receptor would be minimal, ensuring fidelity and specificity of the neural messages delivered by GABA.

Coordinate enhancement occurs in GABAergic inhibitory function with progressive acidification because GABA formation and its anion channel opening efficacy are increased while its metabolic destruction by transamination and removal by transport are decreased (Roberts and Sherman, 1993). Diminution occurs upon alkalinization. Contrawise, acidification decreases postsynaptic efficacy of glutamate, the major excitatory neurotransmitter. In the above manner the delicate balance between excitation and inhibition in the brain is maintained within the adaptive range in response to local or global activity that acidifies the environment in which it occurs. Accelerated metabolism following nerve activity results in accelerated formation of CO₂ and lactic acid, the accompanying acidification applying physiological “brakes,” so to speak, slowing down neural activity while recovery takes place. This keeps the system from “overheating,” thereby helping prevent structural and functional damage from taking place. When GABAergic-glutamatergic relations are unbalanced by glutamatergic overactivity, seizures may occur. For example, the excitement experienced at an athletic event with the attendant hyperventilation not infrequently causes seizures to occur in susceptible individuals. Overbalancing in favor of the GABA system can lead to maladaptive decrement in neural activity and even to coma.

The properties of the simple GABA molecule and of the machinery built to support its function make it eminently suitable to guide the brain to function in a “civilized” manner. The yin–yang between the glutamatergic excitatory and GABAergic inhibitory systems is played out on the tight rope of a delicate balance, prolonged imbalances in relations between them leading to serious disorders.

The “charm” of GABA lies in nature’s choice of this simple molecule, made from the common metabolic soil of glutamic acid, for the all-important role as major controller of the infinitely complex machinery of the brain, allowing it to operate in the manner best described as freedom without license. Try as one might, one cannot come up with a better choice for the job.

Immunocytochemistry of GABA Neurons

For a number of years I felt that my laboratory, largely biochemical, was wandering in the wilderness of the complexities of the metabolism of the vertebrate CNS (Appendix II) without definitively coming to terms with problems related to GABAergic transmitter functions and the roles of GABA neurons in information processing. The history of chemical work on GABA goes back more than 47 years and it recapitulates most of the modern history of neurochemical endeavor. At the time that GABA was discovered in brain and the first experiments were being performed on its biochemistry and pharmacology, an accepted approach to neurochemistry was to study the whole brain or some grossly defined regions. Acetone powders, homogenates, slices, and other types of preparations were made from whole rodent brain and the projected studies were performed on such preparations. In due course it became possible to analyze for the components of the GABA system in different brain regions, and laminar analyses were performed on such suitably layered structures as the cerebellum, hippocampus, retina, and superior colliculus. Although the functions of most brain regions in terms of physiology, morphology, and behavior still were not well understood, a certain degree of definition was attained relevant to quantitative aspects of the amounts of GABA and the enzymes most importantly involved in its formation and degradation, GAD and GABA transaminase. The localization of GABA neurons was inferred by correlating microchemical, electrophysiological, pharmacological, and iontophoretic studies with what was known of the cytoarchitecture of specific regions of brain and spinal cord. Analyses of GABA contents and GAD activities were performed in almost all identifiable brain structures and spinal cord. Some studies combined biochemical analyses with various types of lesioning procedures in an attempt to correlate specific neural degenerations with losses of GAD and GABA.

The distributions of the components of the GABA system also were studied extensively by subcellular fractionation techniques in preparations from whole brain or selected regions. Interpretation of results from the above types of analyses always suffered from lack of definition, attributable to the presence of millions of cells of different types in any dissected region, and definitive conclusions were not possible about specific synaptic connections. Even when individual cell bodies of large neurons (e.g., cerebellar Purkinje cells) were dissected out and subjected to microanalytical examination, presynaptic endings from the axons of other neurons adhered to the neuronal somata, and it was impossible to estimate the proportions of a particular measured variable contributed by somata or presynaptic endings. Exquisite dissection techniques made possible the determination of GABA contents in membrane-containing and membrane-free portions of individual Deiters’ neurons. However, none of these approaches clarified the manner in which GABA neurons might participate in information processing in different parts of the vertebrate CNS.

A critical examination of our own work and that of others led me to the inevitable conclusion that direct visualization of components of the GABA system, particularly GABA neurons and their terminals, was necessary to obtain unequivocal proof of the existence of components of the GABA system at specific synaptic sites in neural tissues. The most likely approaches to achieve this goal appeared to be those that might lead to visualization of the pertinent proteins (GAD, GABA transaminase, and the GABA transport and receptor proteins) at the light and electron microscopic levels. This had never been done before for any neurotransmitter, and the technical difficulties to be overcome were formidable, to say the least.

Early in 1968 I decided with great trepidation to “go for broke,” so to speak, and to begin with GAD, the rate-limiting enzyme in GABA formation, a portion of which I knew to be present in an easily solubilized form and in high concentration in synaptosomes prepared from mouse brain. Many attempts had been made by us to develop chemical procedures for the visualization of GAD, but all failed because of the difficulties in demonstrating histochemically the products of the enzymatic reaction, GABA and CO2. The difficult alternative approach was to locate GABA neurons by immunocytochemical procedures. This required the preparation of pure GAD from brain, development of antibodies to the enzyme, and then visualization of the antibodies by a suitable labeling technique specifically at those cellular and subcellular sites where GAD, the antigen, is located. It is to this task that I and a group of talented young colleagues dedicated ourselves for several years, the work finally resulting in the first immunocytochemical visualization ever of a neurotransmitter synthesizing enzyme at various sites in the central nervous system at both light and electron microscopic levels (see Figs. 2–4 for examples and Appendix III for steps along the way). Much subsequent work from our own laboratories and that of others on GAD as well as on many other proteins has appeared over the years using variations of the techniques we developed. A useful atlas has been made of the distribution of GABAergic neurons and terminals in the rat central nervous system (Mugnaini and Oertel, 1985).

The development of the immunocytochemical techniques ended what I consider to be the “romantic” era of the GABA saga. We now are in the period of molecular biology in which aspects of all components ofthe GABA system are being explored at structural and genetic levels. My long association with the simple GABA molecule has been like peeling an onion, one problem inevitably leading to another in endless succession. The “peeling” continues at a greatly accelerated rate in laboratories throughout the world.

Inhibitory Command-Control by the Extended Brain: Instinctual Needs, Social Inhibition, and Release of Human Behavior

The brain, its function enhanced by invention and uses of language, tools, and social devices, has assumed a dominant position among the nested command-control systems that have evolved on the way from primordial single cell to conscious human being. The neuroendocrine system, the control of which is centered in the brain, regulates to a greater or lesser extent all aspects of structure and function throughout the body. The extended brain with its emergent properties increasingly is learning how to manipulate various aspects of the environment, terrestrial and even extraterrestrial.

Neural inhibition is not sufficient by itself to enable individuals to govern their activities in an adaptive manner in settled communities. For modern civilization to exist at all, it is necessary for there to be attenuation and time-delay of the gratification of instinctual needs or of their symbolic equivalents. For this purpose have been devised religions, taboos, and laws which, assiduously taught by word and example from early childhood on and reinforced by rewards and punishments, help to prepare individuals in their adulthood to walk the tightropes of the tensions arising from the interplay between instinctual demands and social inhibitions. These social inhibitions consist of the learned restrictions that have become part of the extended brain (conscience) and externally existing policing systems.

Figure 2. The inhibited nervous system. An unretouched photograph taken with Nomarski optics of a neuron in the rat nucleus interpositus studded with GAD-positive terminals, presumably Purkinje cell axonal terminals, is placed below a picture of Gulliver, showing him when he awoke to find himself pinioned to the ground. The latter picture is taken from the 1956 edition of Vol. 7 of The Book of Knowledge, The Grolier Society Inc., New York. (Figure prepared by Robert Barber).

Figure 3. GABA neurons and terminals in rat hippocampus and cortex. Left: a presumptive basket cell (B) in rat hippocampus that stains positively for L-glutamic acid decarboxylase (GAD) and is, therefore, a GABAergic neuron. It is studded with numerous GAD-positive terminals (arrows). Right: soma of a GAD-positive stellate cell (S) in layer V of the rat visual cortex that also is studded with GAD-positive terminals. In both micrographs, it is seen that somata of pyramidal neurons (P), which are not GAD-positive, are contacted by numerous GAD-positive terminals. The bar represents 10 µ.m. (Figure kindly furnished by C. E. Ribak and J. E. Vaughn.)

The essence of my argument is that the extents and variabilities of the cascades of multichannel informational flows, inward and outward, are coupled to demand at all times at all levels of observation in healthy organisms. Changes in activities with changes in forcing function occur everywhere in accord with principles of nonlinear dynamics. I posit that this would be as true for overt behavior of an individual in a complex social setting as for the activities within a membrane of an individual neuron. It now is of greatest importance to build bridges between neurobiology and physics so that we come to understand the physical principles that underlie our lives and how we live them.

The necessarily intimate coupling between brain and sensorium is easily seen from behavioral abnormalities that result from brain lesions or during sensory isolation. However, it is the dominant extended brain that ultimately abstracts and interprets environmental patterns and supervises the organization and release of adaptive behavior by enabling appropriate choices to be made from among the available options.

Figure 4. Electron micrographs of various types of synaptic junctions formed by presynaptic terminals that contain glutamate decarboxylase (GAD), the enzyme that synthesizes the neurotransmitter γ-aminobutyric acid (GABA). All specimens were obtained from rat CNS, and all were prepared according to immunoperoxidase procedures developed for the ultrastructural localization of GAD. (a) Axodendritic synapses in the substantia nigra. Two axon terminals (T1 and T2) filled with electron-opaque, GAD-positive reaction product are shown to synapse with a dendritic shaft (D) in the pars reticulata. One of the terminals (T1) forms an asymmetric synaptic junction (arrow); the other terminal (T2) forms a symmetric synapse (arrow) (original magnification × 44,000). (b) An axoaxonic synapse in the cerebral cortex. A GAD-positive axon terminals (T) is shown forming a symmetric synapse (arrow) with an axon initial segment identified by a dense undercoating of the axolemma (arrowheads) and a fasciculation of microtubules (e.g., asterisk) (original magnification × 20,000). (c) An axosomatic synapse in the dorsal horn of the spinal cord. A probable synaptic junction (arrow) is shown between a GAD-positive terminal (T) and neuron (N) in the substantia gelatinosa (original magnification × 26,000). (d) An axoaxonic synapse in the dorsal horn of the spinal cord. A synaptic junction (white arrow) is shown between the GAD-positive presynaptic terminal (T₁) and another synaptic terminal (T) that is not GAD-positive. In addition, T₂ is the presynaptic component of another synaptic junction (black arrow) with a dendrite (D) (original magnification × 38,000). (e) Dendrodendritic synapse in the glomerular layer of the olfactory bulb. Two GAD-positive gemmules (D₁, D₂) from dendrites of periglomerular neurons form synapses with a mitral/tufted dendritic shaft (D₃). One gemmule (D1) appears to form a reciprocal synapse, and the other gemmule (D₂) appears to be presynaptic only (original magnification × 54,000). Directions of synaptic transmission are indicated by arrows in a to e. Electron micrographs provided by RP Barber, BJ McLaughlin, CE Ribak, and JE Vaughn. Reprinted from Nerve Cells, Transmitters, and Behaviour, Levi-Montalcini R, ed. Vatican City, Italy: Pontifical Academy of Sciences, 163–213, with permission of the author.

To cite from an article written with Matthyssee in 1970: “We feel that social progress, and, indeed, the probability of survival, depend in large part on the range of behavioral options available to individuals and to nations. It may be that an integrated approach to the nervous system will reveal options yet undiscovered, for example by increasing the capacity for learning and for control of aggressive drives.”

We scientists must not despair at the relative lack of social progress in the intervening 28 years. “No, our science is no illusion. But an illusion it would be to suppose that what science cannot give us we can get elsewhere” (Freud, 1961).

A Final Note

My parents brought me from Russia to the United States when I was two years old. Unquestionably, the day of arrival was the luckiest one in my life. Nowhere else in the world would I have been given the opportunity to follow my inclinations so freely and with such good support and encouragement for so many years.

I was blessed with excellent teachers and humane and sensitive mentors. The young scientists who joined me at various times throughout my career have enlightened me and have contributed critically to whatever success the work may have attained.

I have had the freedom to travel and to meet colleagues from many countries. Whatever the state of the world, sitting in my study in the quiet of evening I have warm thoughts about those whose work I admire and whom I have been fortunate enough to know personally. What great scientists and fine human beings there are among them!

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Roberts E, Matthysse S. Neurobiochemistry: At the Crossroads of Neurobiology. Annv Rev Biochem 1970;39:777–820.

Roberts E, Sherman MA. GABA—The quintessential neurotransmitter: Electroneutrality, fidelity, specificity, and a model for the ligand binding site of GABAA receptors. Neurochem Res 1993;18:365–376.

Roberts E, Simonsen DG. Free amino acids in animal tissue. In: Holden JT, ed. Amino acid pools. Amsterdam: Elsevier, 1962;284–349.

Roberts E, Tishkoff GH. Distribution of free amino acids in mouse epidermis in various phases of growth as determined by paper partition chromatography. Science 1949;109:14–16.

Rössler OE. Chaotic behavior in simple reaction systems. Z Naturforsch A 1976;31: 259–264.

Saffen DW, Cole AJ, Worley PF, Christy BA, Ryder K, Baraban JM. Convulsantinduced increase in transcription factor messenger RNAs in rat brain. Proc Natl Acad Sci USA 1988;85:7795–7799.

Saito K. Immunochemical studies of GAD and GABA-T. In: Roberts E, Chase TN, Tower DB, eds. GABA in nervous system function. New York: Raven Press, 1976; 103–111.

Saito K, Barber R, Wu J-Y, Matsuda T, Roberts E, Vaughn, JE. Immunohistochemical localization of glutamate decarboxylase in rat cerebellum. Proc Natl Acad Sci USA 1974;71:269–273.

Saito K, Roberts E, Barber R. Immunocytochemical identification of GABAergic neurons. In: Kuriyama K, ed. Structure and function of synapses. Tokyo: Ishiyaku Shuppan, 1977;143–157.

Saito K., Schousboe A, Wu J-Y, Roberts E. Some immunochemical properties and species specificity of GABA-α-ketoglutarate transaminase from mouse brain. Brain Res 1974;65:287–296.

Saito K, Wu J-Y, Matsuda T, Roberts E. Immunochemical comparisons of vertebrate glutamic acid decarboxylase. Brain Res 1974;65:277–285.

Sano K, Roberts E. Binding of γ-aminobutyric acid by brain preparations. Biochem Biophys Res Commun 1961;4:358–361.

Sano K, Roberts E. Binding of γ-aminobutyric acid by mouse brain preparations. Biochem Pharmacol 1963;12:489–502.

Schoenheimer R. The dynamic state of body constituents. Cambridge: Harvard University Press, 1942.

Schousboe A, Wu J-Y, Roberts E. Purification and characterization of the 4-amino-butyrate-2-ketoglutarate transaminase from mouse brain. Biochemistry 1973; 12:2868–2873.

Schousboe A, Wu J-Y, Roberts E. Subunit structure and kinetic properties of 4-aminobutyrate-2-ketoglutarate transaminase purified from mouse brain. J Neurochem 1974;23:1189–1195.

Shepard RN. Toward a universal law of generalization for psychological science. Science 1987;237:1317–1323.

Steward FC, Thompson JF, Dent CE. γ-Aminobutyric acid. A constituent of the potato tuber? Science 1949;110:439–440.

Storm-Mathisen J, Leknes AK, Bore AT, Vaaland JL, Edminson P, Haug F-M S, Ottersen OP. First visualization of glutamate and GABA in neurones by immunocytochemistry. Nature 1983;301:517–520.

Takeuchi A. Studies of inhibitory effects of GABA in invertebrate nervous systems. In: Roberts E, Chase TN, Tower DB, eds. GABA in nervous system function. New York: Raven Press, 1976;255–267.

Takeuchi A, Takeuchi N. The effect on crayfish muscle of iontophoretically applied glutamate. J Physiol 1964;170:296–317.

Takeuchi A, Takeuchi N. Electrophysiological studies of the action of GABA on the synaptic membrane. Fed Proc 1967;26:1633–1638.

Takeuchi A, Takeuchi N. The structure-activity relationship for GABA and related compounds in the crayfish muscle. Neuropharmacology 1975;14:627–634.

Tam S-P, Hache RJG, Deeley RG. Estrogen memory effect in human hepatocytes during repeated cell division without hormone. Science 1986;234:1234–1237.

Thom R. Structural stability and morphogenesis. Reading, MA: Benjamin, 1975. [English edition].

Udenfriend S. Identification of γ-aminobutyric acid in brain by the isotope derivative method. J Biol Chem 1950;187:65–69.

Varon S, Weinstein H, Kakefuda T, Roberts E. Sodium-dependent binding of γ-aminobutyric acid by morphologically characterized subcellular brain particles. Biochem Pharmacol 1965;14:1213–1224.

Vaughn JE, Barber RP, Saito K, Roberts E, Famiglietti EV, Jr. Immunocytochemical identification of GABAergic neurons in rat retina. Anat Rec 1978;190:571–572.

von Bekesy G. Sensory inhibition. Princeton: Princeton University Press, 1967.

von Euler C, Skoglund S, Söderberg U. Structure and function of inhibitory neuronal mechanisms. Oxford: Pergamon Press, 1968.

Wang Y-J, Salvaterra P, Roberts E. Characterization of [3H]muscimol binding to mouse brain membranes. Biochem Pharmacol 1979;28:1123–1128.

Weinstein H, Varon S, Muhleman DR, Roberts E. A carrier-mediated transfer model for the accumulation of 14C-γ-aminobutyric acid by subcellular brain particles. Biochem Pharmacol 1965;14:273–288.

Wheatley DN, Inglis MS. Protein turnover during cell growth: A re-examination of the problem of linear incorporation kinetics of radioactively-labeled amino acids into protein and its relationship to growth characteristics. Cytobios 1986;47: 187–210.

Wiersma CAG, Furshpan E, Florey E. Physiological and pharmacological observations on muscle receptor organs of the crayfish, Cambarus clarkii girard. J Exp Biol 1953;30:136–150.

Wong E, Schousboe A, Saito K, Wu J-Y, Roberts E. Immunochemical studies of brain glutamate decarboxylase and GABA-transaminase of six inbred strains of mice. Brain Res 1974;68:133–142.

Wood JG, McLaughlin BJ, Vaughn JE. Immunocytochrmical localization of GAD in electron microscopic preparations of rodent CNS. In: Roberts E, Chase TN, Tower DB, eds. GABA in nervous system function. New York: Raven Press, 1976; 133–148.

Wu J-Y. Purification, characterization, and kinetic studies of GAD and GABA-T from mouse brain. In: Roberts E, Chase TN, Tower DB, eds. GABA in nervous system function. New York: Raven Press, 1976;7–55.

Wu J-Y, Matsuda T, Roberts E. Purification and characterization of glutamate decarboxylase from mouse brain. J Biol Chem 1973;248:3029–3034.

Wu J-Y, Roberts E. Properties of brain L-glutamate decarboxylase: Inhibition studies. J Neurochem 1974;23:759–767.

Yoneda Y, Roberts E, Dietz GW, Jr. A new synaptosomal biosynthetic pathway of glutamate and GABA from ornithine and its negative feedback inhibition by GABA. J Neurochem 1982;38:1686–1694.

Additional Publications

Steroid-Related

Roberts E, Bologa L, Flood JF, Smith GE. Effects of dehydroepiandrosterone and its sulfate on brain tissue in culture and on memory in mice. Brain Res 1987;406: 357–362.

Bologa L, Sharma J, Roberts E. Dehydroepiandrosterone and its sulfated derivative reduce neuronal death and enhance astrocytic differentiation in brain cell cultures. J Neurosci Res 1987;17:225–234.

Flood JF, Smith GE, Roberts E. Dehydroepiandrosterone and its sulfate enhance memory retention in mice. Brain Res 1988;447:269–278.

Flood JF, Roberts E. Dehydroepiandrosterone sulfate improves memory in aging mice. Brain Res 1988;448:178–181.

Roberts E. Dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) as neural facilitators: effects on brain tissue in culture and on memory in young and old mice. A cyclic GMP hypothesis of action of DHEA and DHEAS in nervous system and other tissues. In: Kalimi M, Regelson W, eds. The biological role of dehydroepiandrosterone (DHEA). New York: Walter de Gruyter & Co, 1990; 13–42.

Flood JF, Morley JE, Roberts E. Memory-enhancing effects in male mice of pregnenolone and steroids metabolically derived from it. Proc Natl Acad Sci USA 1992; 89:1567–1571.

Guth L, Zhang Z, Roberts E. Key role for pregnenolone in combination therapy that promotes recovery after spinal cord injury. Proc Natl Acad Sci USA 1994;91: 12308–12312.

Roberts E. Pregnenolone––From Selye to Alzheimer and a model of the pregnenolone sulfate binding site on the GABAA receptor. Biochem Pharmacol 1995;49: 1–16.

Flood JF, Morley JE, Roberts E. Pregnenolone sulfate enhances post-training memory processes when injected in very low doses into limbic system structures: The amygdala is by far the most sensitive. Proc Natl Acad Sci USA 1995;92: 10806–10810.

Alzheimer-Related

Flood JF, Morley JE, Roberts E. Amnestic effects in mice of four synthetic peptides homologous to amyloid β protein from patients with Alzheimer disease. Proc Natl Acad Sci USA 1991;88:3363–3366.

Flood JF, Roberts E, Sherman MA, Kaplan BE, Morley JE. Topography of a binding site for small amnestic peptides deduced from structure-activity studies: Relation to amnestic effect of amyloid β protein. Proc Natl Acad Sci USA 1994;91:

Flood JF, Morley JE, Roberts E. An amyloid β-protein fragment, Aβ [12-28], equipotently impairs post-training memory processing when injected into different limbic system structures. Brain Res 1994;663:271–276.

Appendix I

Appendix I. Isoelectric Points of Major Naturally Occurring Amino Acids and Peptides in Animal Tissuesa

Amino acid

pl

Aspartic acid

1.77

Glutamic acid

3.22

Cystine

5.03

Taurine

5.12

Asparagine

5.41

Phenyalanine

5.48

Homocystine

5.53

Threonine

5.64

Glutamine

5.65

Tyrosine

5.66

Serine

5.68

Methionine

5.74

Hydroxyproline

5.74

Tryptophan

5.89

Citrulline

5.92

Isoleucine

5.94

Valine

5.96

Glycine

5.97

Leucine

5.98

Alanine

6.00

Sarcosine

6.12

Proline

6.30

β-Alanine

6.90

Cysteine

6.94

Homocysteine

7.05

γ-Aminobutyric acid

7.30b

Histidine

7.47

δ-Amino-n-valeric acid

7.52

ϵ-Amino-n-caproic acid

7.60

1-Methylhistidine

7.67

Carnosine

8.17

Anserine

8.27

Lysine

9.59

Ornithine

9.70

Arginine

11.15  

aData taken from Greenstein and Winitz, 1961

bPhysiological pH is 7.30

Appendix II

Appendix II. Metabolic relationships potentially relevant to control of GABA formation and utilization. Many of these have been explored in studies in my laboratories and in those of others. Reprinted from Benzodiazepine / GABA receptors and chloride channels: Structural and functional properties. Olsen RW, Venter JC, eds. New York, NY: Liss, 1986; 1-39, with permission of the author.

Appendix III

Appendix III. Immunocytochemistry of GABA-Related Enzymes

Steps along the way

Date

Authors

1. Purification and properties

GAD

Purification and characterization of glutamate decarboxylase from mouse brain

1973

Wu, Matsuda, and Roberts

Electrophoresis of glutamic acid decarboxylase from mouse brain in sodium dodecyl sulfate polyacrylamide gels

1973

Matsuda, Wu, and Roberts

Properties of brain L-glutamate decarboxylase: inhibition studies

1974

Wu and Roberts

GABA-T

Purification and characterization of the 4-aminobutyrate-2-ketoglutarate transaminase from mouse brain

1973

Schousboe, Wu, and Roberts

Subunit structure and kinetic properties of 4-aminobutyrate-2-ketoglutarate transaminase purified from mouse brain

1974

Schousboe, Wu, and Roberts

Summary

Purification, characterization, and kinetic studies of GAD and GABA-T from mouse brain

1976

Wu

2. Immunological studies

GAD

lmmunochemical studies on glutamic decarboxylase from mouse brain

1973

Matsuda, Wu, and Roberts

Immunochemical comparisons of vertebrate glutamic acid decarboxylase

1974

Saito, Wu, Matsuda, and Roberts

Immunochemical studies of brain glutamate decarboxylase and GABA-transaminase of six inbred strains of mice

1974

Wong, Schousboe, Saito, Wu, and Roberts

GABA-T

Some immunochemical properties and species specificity of GABA-α-ketoglutarate transaminase

1974

Saito, Schousboe, Wu, and Roberts

Summary

Immunochemical studies of glutamate decarboxylase and GABA-α-ketoglutarate transaminase

1976

Saito

3. Immunocytochemical approaches

GAD

Immunohistochemical localization of glutamate decarboxylase in rat cerebellum

1974

Saito, Barber, Wu, Matsuda, Roberts, and Vaughn

The fine structural localization of glutamate decarboxylase in synaptic terminals of rodent cerebellum

1974

McLaughlin, Wood, Saito, Barber, Vaughn, Roberts, and Wu

The fine structural localization of glutamate decarboxylase in developing axonal processes and presynaptic terminals of rodent cerebellum

1975

McLaughlin, Wood, Saito, Roberts, and Wu

lmmunocytochemical localization of glutamate decarboxylase in rat spinalcord

1973

McLaughlin, Barber, Saito, Roberts, and Wu

Immunocytochemical localization of glutamate decarboxylase in the substantia nigra of the rat

1976

Ribak, Vaughn, Saito, and Barber

Immunocytochemical localization of glutamate decarboxylase in rat substantia nigra

1976

Ribak, Vaughn, Saito, Barber, and Roberts

Immunocytochemical localization of glutamate decarboxylase (GAD) in the olfactory bulb

1976

Ribak, Vaughn, and Saito

Glutamate decarboxylase (GAD) localization in neurons of the olfactory bulb

1977

Ribak, Vaughn, Saito, Barber, and Roberts

Immunocytochemical localization of GAD in somata and dendrites of GABAergic neurons following colchicine treatment

1976

Ribak and Vaughn

The immunocytochemical localization of GAD within stellate neurons of rat visual cortex

1977

Ribak

Immunocytochemical localization of glutamic acid decarboxylase in neuronal somata following colchicine inhibition of axonal transport

1978

Ribak, Vaughn, and Saito

GABAergic terminals are presynaptic to primary afferent terminals in the substantia gelatinosa of the rat spinalcord

1978

Barber, Vaughn, Saito, McLaughlin, and Roberts

Immunocytochemical localization of GAD in electron microscopic preparations of rodent CNS

1976

McLaughlin, and Vaughn

Aspinous and sparsely spinous stellate neurons contain glutamic acid decarboxylase in the visual cortex of rats

1978a

Ribak

Immunocytochemical identification of GABAergic neurons in rat retina

1978

Vaughn, Barber, Saito, Roberts, and Famiglietti

Immunocytochemical localization of glutamic acid decarboxylase (GAD) in the rat corpus striatum

1978

Ribak, Harris, Anderson, Vaughn, and Roberts

GABA-T

See Wood et al.

Summaries

Light microscopic visualization of GAD and GABA-Tin immunocytochemical preparations of rodent CNS

1976

Barber and Saito

Immunochemistry of the GABA system—a novel approach to an old transmitter

1976

Roberts

Immunocytochemical identification of GABAergic neurons

1977

Saito, Roberts, and Barber

Roles of GABA neurons in information processing in the vertebrate CNS

1978

Roberts

Gunther Stent

BORN:

Berlin, Germany

March 28, 1924

EDUCATION:

University of Illinois, B.S. (1945)

University of Illinois, Ph.D. (1948)

APPOINTMENTS:

California Institute of Technology (1948)

University of Copenhagen (1950)

Institut Pasteur, Paris (1951)

University of California, Berkeley (1952)

Wissenschaftskolleg zu Berlin (1985)

Professor Emeritus, University of California, Berkeley (1994)

HONORS AND AWARDS (SELECTED):

American Academy of Arts and Sciences (1968)

National Academy of Sciences, U.S.A. (1982)

American Philosophical Society (1984)

Akademie der Wissenschaften und der Literatur (Mainz) (1989)

European Academy of Arts and Sciences (1993)

Gunther Stent was trained in physical chemistry and initially studied DNA replication and expression. Moving in midcareer to neurobiology, he worked out the neural control of swimming and heartbeat in the leech. He also pioneered developmental studies of the leech, which resulted in a comprehensive description of cell lineage. He has written many philosophical essays on the epistemology and sociology of science.

Gunther Stent

Childhood

Few Jews lived in Treptow, the unfashionable suburb of Greater Berlin where I was born. Its anti-Semitic, petty-bourgeois milieu was light years distant from the avant-garde—the Albert Einsteins, the Max Reinhardts, the Marlene Dietrichs, the Bertolt Brechts—to whom the Berlin of the Weimar Republic owed its cultural glamour. My religious upbringing, insofar as I had any, took place in the context of anti-Zionist, self-hating Germano-Christianized Reform Judaism. There were no observances of Hebrew ritual in my home: no Sabbath candles, no Passover seder, no matzoth. Judaism only became a major factor in my life when I was 9, Hitler came to power, and I began to fear for my life as I watched Nazi storm troopers march through the Berlin streets bawling: “When Jew-blood spurts from our knives, we’ll all have twice-better lives.”

My father, Georg Stensch, a native of Berlin, owned one of the largest bronze statuary and light fixture factories in Germany. My mother, Elli, came from a family of well-to-do, assimilated Jews in the Silesian city of Breslau. In 1933, shortly after the Nazi takeover, she was confined in a psychiatric sanatarium, and my teen-age elder sister, Claire, took charge of my upbringing until, newly wed, she emigrated with her husband to Chicago in 1937. By then, my mother had died. A year later, my sister sent me the affidavit of support I needed to apply for my U.S. immigration visa. I was wildly enthusiastic about starting a new life in the glamorous New World, led by the great president to whom that Nazi monster, Joseph Goebbels, habitually referred as “Crypto-Jew Fraenkel Rosenfeld.” As I knew from poring over back issues of the National Geographic magazine I had come across in a resort hotel, America had the prettiest girls, the tallest buildings, and the most cars. I was crushed when the U.S. consulate in Berlin informed me that because of the sudden rush of German-Jewish visa applicants, it would be a few months until I could expect to get my papers. As it turned out, I had to cool my heels for 18 long months.

My father barely avoided being sent to Sachsenhausen concentration camp in the roundup of moneyed Jews during the Kristallnacht pogrom of November 10, 1938. Because he had connections with the Berlin police and a valid passport, he managed to escape to London, where my elder brother, Ronald, was living. Since neither my recently acquired stepmother nor I had a passport, we decided to join my father in London illegally. We had heard that the most promising route was across the “Green Frontier” between Germany and Holland or Belgium, which meant stealing over the border in open country, avoiding not only the German but also the Dutch or Belgian frontier patrols who were handing the Jewish refugees they intercepted back to the Germans. To cut down the risk, it was advisable to engage the expensive services of a guide. Our first guide was arrested by the police on his way to meeting us at Aachen station. Our second attempt, which involved traipsing through the snow-covered Ardennes forest on New Year’s eve, succeeded, but only after our second guide had led us directly to a German frontier police post. The post’s chief, who was probably cut in on the exorbitant tour fee, let us go after checking the Gestapo’s list of wanted persons and strip-searching us for contraband. We made it to Antwerp on New Year’s Day 1939, physically safe but destitute.

We had to wait four months in Antwerp for our British visa before my stepmother and I managed to reach London. After hanging around London for another 11 months, I finally received my U.S. immigration papers and, in March 1940, sailed alone for the States from Liverpool in the third-class bowels of an ancient Cunard steamer. By then, the Second World War had begun, and I was lucky that my ship was not torpedoed by a German U-boat before it docked in New York harbor.

I moved in with my sister. Chicago’s Hyde Park district had turned into one of the “Fourth Reich” settlements of German and Austrian Jewish refugees—like Washington Heights in Manhattan and Swiss Cottage in London—and she enrolled me at Hyde Park High School. Concealing my long absence from schooling, I struck the vice-principal as an upper-level junior, or maybe even as a senior (hadn’t I enjoyed the benefits of the world-renowned German secondary education?) until he gave me a few tests. I couldn’t do fractions, let alone geometry or science. Although I was almost 16, he made me start as a freshman, the graduating class of 1944.

Miss Rubovits, my English composition teacher at Hyde Park, demanded clarity as well as grammatical perfection. The weekly themes she assigned had to be written again and again, until her exacting literary standards were met. Imitating Miss Rubovits earned me much ill-will in my later professional life from scientific colleagues whose work, including feature articles I commissioned for the Journal of Neuroscience during the last few years of my career, I took the liberty of rewriting to Miss Rubovits’ standards.

To make up time, I signed on for extra courses, went to summer school, and obtained credit for knowing French (but not for knowing German, because it was my mother tongue). Accumulating credits at a furious rate, I made it through Hyde Park High in 21 months, still appallingly ignorant of most academic subjects. In the fall of 1942, I moved to Champaign, to enter the University of Illinois.

Synthetic Rubber

I had never heard of chemical engineering when I chose it as my major at Illinois. Its name suggested something brand new, something futuristic. “Gunther Stent, Chemical Engineer,” had a nice ring to it, and I figured it would set me apart from your run-of-the-mill college graduate. As it turned out, I didn’t care for chemistry in college any more than I had in high school until, in my junior year, I took my first course in physical chemistry. Professor Frederick T. Wall’s lectures were dynamic, lucid, and well prepared, and his presentation of chemical thermodynamics was captivating. In contrast to inchoate inorganic or organic chemistry,—not to speak of the boring engineering courses—physical chemistry appealed to me as a logically coherent discipline, whose theories are expressible as mathematical relations. I switched my major to physical chemistry.

Upon graduating from Illinois in January 1945, I applied to California Institute of Technology for a Ph.D. in physical chemistry under Linus Pauling, my scientific hero because his The Nature of the Chemical Bond was the first textbook that I actually enjoyed reading in all my 13 years of doing time in German and American schools. But Caltech turned me down and I resigned myself to staying at Illinois.

I accepted Prof. Wall’s offer to do a Ph.D. under his direction as a research assistant on the War Production Board’s (WPBs) synthetic rubber research program. The mission was to develop a process that would make synthetic rubber tires as good as, or even better than, tires made from natural rubber. Natural rubber consists of a homopolymer in which hundreds of isoprene monomers are linked end-to-end, whereas synthetic rubber (Buna-S) is a copolymer of equal proportions of butadiene and styrene monomers. One of the flaws of Buna-S that impaired its elastic properties was that, whereas natural isoprene homopolymer molecules are of uniform length, synthetic butadiene–styrene copolymer molecules are not. Wall assigned me to work out a method by which Buna–s could be resolved into a series of fractions, each of which would contain copolymer molecules of uniform length. I decided to try a modification of the thermal diffusion column invented by K. Clusius and G. Dickel in 1938 for resolving gaseous mixtures of atomic isotopes, such as 12CO2 and 13CO2.

I built a column, 2 m tall, of two concentric steel tubes separated by a narrow, 1-m gap which was filled with a toluene solution of the synthetic copolymer; the outer tube was cooled by cold water and the inner tube was heated by hot water. It worked as I had hoped. After letting the column run for 2 days, downward from the top, the gap contained Buna-S molecules of ever-greater chain length. Mathematical analysis of these data then gave me an entirely novel way of determining the molecular length distribution among the original synthetic copolymer molecules.

I was jubilant: It was my first success as an experimental scientist. I had finessed Mother Nature and made her do my bidding! Perhaps my device would become known as the “Stent column.” When people would congratulate me, I would feign modesty and point out that the idea was actually pretty obvious.

I proudly presented my findings at a national meeting of all WPB rubber research groups in the spring of 1946. There was no need for me to feign modesty. My talk aroused only mild interest; my colleagues thought that my method would never provide a practical way of producing Buna-S molecules of uniform chain length on an industrial scale. My results were never published, and my liquid-phase thermal diffusion method for resolving polymer molecules of different lengths vanished without trace from the corpus of science. This was a pity, because, unknown to me, biochemists studying proteins and nucleic acids in the 1940s were in great need of techniques for separating different size molecules in extracts from living cells. My thermal diffusion column could have served beautifully. In retrospect, I have no doubt that it would have made a stir among biochemists had I indeed adapted it for their purposes. But by the 1950s, when I finally became aware of the opportunity I had missed, much better molecular separation methods had been invented.

This proved to be only the first of several instances in my career when I hit on a good thing that could have gained me substantial fame—but didn’t. Many scientists try to sell sour grapes by claiming that one of their brilliant original ideas was stolen by someone who claimed credit. Such thefts do occur, but not often. The more banal cause for the failure to get due credit for one’s discovery is, as in my case, the lack of personal qualities needed to have it make an impact. Originality and inventiveness, though necessary, are not sufficient for making a mark in science: one also has to have intuition, stamina, and, above all, self-confidence to exploit one’s inventions and present them as a salable package.

What Is Life?

In my second year of graduate studies, my friend and mentor Martha Baylor, a postdoctoral research biologist in charge of the Illinois Chemistry Department’s electron microscope, suggested that I read What Is Life?, a recently published tract by the famous Austrian physicist Erwin Schrödinger. She thought that I would be interested in what the codiscoverer of quantum mechanics had to say about the connection between thermodynamics and biology. I had always found botany and zoology terminally boring, but I took her advice.

Schrödinger announced that a new era was dawning for the study of heredity, thanks to some novel ideas put forward by Max Delbrück, whom he identified as “a young German physicist.” How, Schrödinger asked, do genes manage to preserve their hereditary information over the generations? Following Delbrück’s then 10-year-old proposal that this stability derives from the atoms of the gene molecule staying put in “energy wells,” Schrödinger proposed that the gene-molecule is an aperiodic crystal, composed of a long sequence of a few different basic elements, repeated over and over. The exact sequence pattern of these elements would represent a “code” by means of which the hereditary information is encrypted. Thus, Schrödinger was the first to put forward the concept of the genetic code, one of the most important life sciences ideas of the 20th century. Schrödinger had no idea of the atomic nature of this code and thought that “from Delbriick’s general picture of the hereditary substance it emerges that living matter, while not eluding the laws of physics as established up to date, is likely to involve hitherto unknown ’other laws of physics,’ which, however, once they have been revealed will form just as integral a part of this science as the former” (Schrödinger, 1946).

In posing the question “What is life?” Schrödinger confronted physical scientists with a fundamental scientific problem worthy of their mettle, at a time when many of them were suffering from a professional malaise in the immediate postwar period. In stirring up the passions of its impressionable readers, What Is Life? became a kind of Uncle Tom’s Cabin of the revolution in biology that eventually left molecular biology as its legacy.

As a mere Ph.D. candidate of 22, I was too green to be suffering from anything as blasé as the professional malaise of my elder colleagues. Yet I was so captivated by the fabulous prospect that by studying genes I might turn up “other laws of physics” that I resolved to join the search for the aperiodic crystal of heredity. I thought that Delbrück, the young German physicist, had probably been drafted into the Wehrmacht and been killed during the war. But perhaps there were people in the States working along these lines.

Good news reached me in the summer of 1947. Delbrück was not only still alive, but he had just been appointed professor of biophysics at Caltech—my academic dream place, home of my hero, Linus Pauling. I wrote to Delbrück to ask if I could work under his direction in Pasadena. I was thinking of applying for a new type of National Research Council (NRC) postdoctoral fellowship sponsored by the Merck Chemical Company, whose purpose, according to an announcement in Science magazine, was “to provide special training and experience to young men and women trained in chemical or biological science who wish to broaden their fields of investigational activity.” What sort of biophysical problem could I be working on in his laboratory if I were awarded a Merck Fellowship? Delbrück replied that he was not in a position to state in any detail the type of problems he was going to work on next year, but he was thinking of doing some experiments on phototaxis in purple bacteria, which might be a good opening for the study of excitatory processes.

At least Delbrück’s response wasn’t an outright rejection. I didn’t know the meaning of phototaxis or excitatory processes, had never heard of purple bacteria, and was totally in the dark about what all this might have to do with genes and leading me to the discovery of “other laws of physics.” But I figured that there would be plenty of time to find out what Delbrück’s proposed project was all about, in the unlikely event that my fellowship request would be granted. In my application I declared that I hoped to apply my knowledge of physical chemistry to the study of biophysical problems, with special emphasis on the investigation of life processes from the point of view of thermodynamics and reaction kinetics. To that end, I intended to study the general nature of excitory [sic] processes under the direction of Prof. Max Delbrück at the California Institute of Technology. I had the good sense not to let on in my application that I had a hidden agenda, namely, looking for other laws of physics.

Many months later, I received a telegram asking me to come to New York—all expenses paid by the NRC—for an interview with the Merck Fellowship Board. My sky-high exultation over this marvelous news subsided as soon as I began to think about the interview. It wouldn’t take more than one or two incisive questions by the Board to reveal that I knew nothing about the “excitory” processes on which I was proposing to carry out advanced postdoctoral research by studying the phototaxis of purple bacteria and had no idea how all this was going to lead me to novel insights about life processes from the point of view of thermodynamics and reaction kinetics.

My fears were not unfounded. The Merck Fellowship Board comprised six formidably distinguished, awe-inspiring senior scientists: Chairman

A.N. Richards, President of the National Academy of Sciences and ex officio High Priest of American science; the geneticist and future Noble laureate, George W. Beadle, Chairman of the Caltech Biology Division; Detlev W. Bronk, professor of biophysics at the University of Pennsylvania and President of the NRC; Hans T. Clarke, professor and Chairman of Biological Chemistry at the College of Physicians and Surgeons of Columbia University; George O. Curme, Director of Research of the Carbide and Carbon Chemicals Corporation; and René Dubos, the famous bacteriologist at the Rockefeller Institute for Medical Research. I was in deep trouble as soon as Chairman Richards asked his first question.

“So you want to go into biology; what do you plan to do?”

“I want to study excitory processes to test whether the Second Law of Thermodynamics applies to living systems.”

“You mean ecitatory processes, don’t you?”

“Yes, Sir. I think so. Yes, I do.”

“How are you going to do it?”

“I’m going to study the phototaxis of purple bacteria.”

“How? And how’s this going to tell you something about the applicability of the Second Law?”

“I’m not exactly sure. Professor Delbrück suggested that this would be a good experimental material for my project.”

At this answer, the Board members frowned and shook their heads in disbelief After I proffered a few more obviously unsatisfactory responses to the questions of other Board members, René Dubos finally asked me sarcastically:

“Then, if I understood you correctly, your proposed postdoctoral studies in biology at Caltech would have to be at the—(pause and emphasis)—undergraduate level. Isn’t that so?”

“Yes, Sir. I guess so.”

After this response, I was dismissed summarily. As I shuffled out, totally humiliated, I noticed, to my astonishment, that Beadle winked at me. Three days after I got back to Champaign, a telegram came that said that they had given me the NRC Merck Fellowship, as one of only seven awardees among a total of 46 applicants. I could only conclude that the unsuccessful 39 were even more appalling phonies than I.

Delbrück asked me to meet him in Chicago in early May. He would be stopping in the City for a day on his way from Pasadena to Indiana University, where he was going to visit “Luria.” I had never heard that name before, but savvy friends at Illinois explained to me that Delbrück was referring to his collaborator, Salvador Luria, with whom he had published an important paper in 1943.

I was enchanted by Delbrück—lightening-quick on the uptake, funny, and amazingly well-informed on a wide range of subjects. He seemed to know everybody, especially the all-time greats of quantum physics, such as Max Planck, Niels Bohr, Werner Heisenberg, Wolfgang Pauli, and Paul Dirac. When the time finally came to discuss my future projects, Delbrück didn’t mention phototaxis of purple bacteria or sensory excitation at all.

“I take it that you want to work on phage?”

“Yes sir, that’s exactly what I want to work on. But could you refresh my memory as to what “phage” is actually all about?”

“No need for that now. You’ll find out what it’s all about soon enough at Cold Spring Harbor Laboratory. You’re going to spend the summer there and take the phage course. In early September, we’ll all head out west, to Pasadena.”

Contrary to the almost universally shared opinion that writing your thesis is a big pain in the butt—the worst part of getting a Ph.D.—I enjoyed writing mine. Thus, I became aware of my bizarre preference for writing about my scientific findings over making them in the first place. This gave me my first inkling that there seemed to be something odd about my motivation for doing science.

Scientists are supposed to be driven by a thirst for understanding the natural world. Their major reward for slaving away in the lab day and night is supposed to be a joy of discovery—the elation that attends reaching a novel insight into nature, as well as satisfying one’s innate curiosity. This can’t be the whole story, of course. Oddly enough, the satisfaction of a scientist’s curiosity about nature provided by a competitor’s discovery is cause, more often than not, for disappointment rather than joy. My curiosity about the workings of nature was not all that fervid, anyhow; what attracted me to science was the life style that came with it. I found it hugely satisfying to work in a lab, to make good conversation—scientific or otherwise—with intelligent colleagues, to travel all over the world, finding friends everywhere. Whenever I did manage to find something new—which didn’t happen often in my career—I too felt elated, of course. But my satisfaction came not from a joy of discovery, but from a joy of telling. What excited me most was the thought that, thanks to my discovery, I would have something to say next time I met a colleague or went to a conference.

That is why publishing papers was what I liked best about science. No sooner had I started a research project, than I was thinking about the paper that I would write about it. Long before I had found anything worth reporting, I was already composing the opening paragraph of the report. I thought of publishing as a way to start conversation. Compared to the joy of telling, the joy of discovery played such a minor role in my motivation that I don’t believe I would have done science if I had been Robinson Crusoe. Isolated, out of my colleagues’ earshot, I wouldn’t have made experiments, even if there happened to be a fully equipped lab on the island, with Man Friday available as a postdoc.

Phage

When I got to Cold Spring Harbor in June 1948, Max (which is what everybody there called Delbrück) introduced me to James Watson, a 20-year-old graduate student, who had also been fascinated by Schrödinger’s What Is Life?. Watson was working for his Ph.D. at Indiana University, doing research on the effects of X rays on phage with Luria, whom he had chosen as his mentor because Luria was a collaborator of Delbrück’s. Jim was my junior by 4 years and a mere graduate student. I didn’t like him at first because he treated me as an equal, as if his opinions were just as good as mine. But before long, I came to terms with the sobering fact that whenever we disagreed about some scientific proposition, his opinions were almost always right and mine almost always wrong. We became lifelong friends.

By the time the phage course was over, I felt I had become an expert phagologist. I had imbibed the conceit of Max’s Phage Group that there was no point in paying any attention to the work of our predecessors or of contemporaries external to the “Church,” as the French microbiologist, André Lwoff, referred to the coterie of Max’s disciples. Reading publications lacking the Church’s imprimatur was worse than a waste of time: The unsubstantiated claims based on poorly designed experiments presented by such confused heathen outsiders would just put wrong ideas in your head.

Besides the Phage Group votaries, other people with biological or biochemical interests were also summering at Cold Spring Harbor. Many presented seminars on their current work, most totally beyond my ken. But I was impressed by Rollin Hotchkiss from the Rockefeller Institute in Manhattan, who spoke on the DNA-mediated hereditary transformation of bacteria, by means of which Hotchkiss’ teacher, Oswald Avery, had shown in the early 1940s that DNA is the genetic material. There had been very little mention of DNA-mediated bacterial transformation in any of the other seminars, even though the physical and chemical nature of the gene was of capital interest not only to the members of the Phage Group, but also to most of the other people at Cold Spring Harbor.

Why had Avery’s discovery, though known to everyone at the lab, made so little impact on the very people interested in the nature of the gene in the summer of 1948? Because the view, then generally held, of DNA as a monotonous molecule that is always the same no matter what its biological source made it impossible to imagine how DNA could be the carrier of hereditary information. By 1952, however, it had been shown that the composition of DNA does vary according to its biological source. Now it could be readily imagined that genes are inscribed in DNA as a specific sequence of the four kinds of iterated building blocks, whose long string makes up the giant DNA molecule. In other words, DNA turned out to be Schrödinger’s “aperiodic crystal” composed of a succession of a small number of different elements, the exact nature of their succession representing a “hereditary code.”

Caltech lived up to my fantasy of a palm-tree studded academic nirvana: a double tier of adobe-colored California mission-style laboratory buildings facing a subtropically landscaped central mall, stretching for a half mile between two Pasadena streets, set off against the sunlit San Gabriel mountains peaked by 10,000-foot Mt. Baldy and peopled with brilliant minds, like Pauling, Beadle, and Max.

My research project was one of the few Max could have picked for which my training as a physical chemist happened to have eminently qualified me. One of the phage strains we studied in the Phage Group fails to attach to its bacterial host cell unless it has been previously “activated” by contact with the amino acid tryptophan. Max suspected (or maybe hoped) that the hitherto known facts about this activation process were not compatible with ordinary physicochemical principles. So maybe there was a paradox hidden here which might lead us to one of those “other laws of physics.”

Much as I was hoping to run into a biological system manifesting an “other law,” I feared that this was not one of them. I thought that I wouldn’t have much trouble coming up with an explanation of the seemingly bizarre tryptophan activation phenomenon within the framework of house-and-garden theories of physical chemistry. Max informed me that I would have a partner in my research project, Élie Wollman, a French bacteriologist from André Lwoff’s Department of Microbial Physiology at the Institut Pasteur in Paris. According to Max, Wollman and I were going to complement each other like liverwurst and rye bread. He had the bacteriology, of which I didn’t know from beans, and I had the math and physics, of which he was largely innocent. Together, we would make the perfect phageology sandwich.

By fall 1949, there were six research fellows working in Max’s lab—Elie Wollman, Jean Weigle, Wolfhard Weidel, Renato Dulbecco, Seymour Benzer, and me—a population explosion since I showed up as Max’s first Caltech postdoctoral fellow a year before. We formed a close-knit sib, with Max as our spiritus rector. Dulbecco would presently succeed in extending the method of plaque assay we used in phage work to animal viruses, which would set the stage for quantitative studies on animal viruses to fathom their intracellular reproductive cycle. He also opened the era of animal virus genetics by isolating virus mutants and developing techniques for mixed infection of single animal cells with two or more genetically different mutant viruses. For these contributions Dulbecco would be awarded the 1975 Nobel Prize in Physiology or Medicine.

Benzer, who had received his Ph.D. in solid state physics from Purdue University, was my classmate in the 1948 Cold Spring Harbor phage course. He, too, had been seduced by Schrödinger’s What Is Life? and hoped to get started on finding the aperiodic crystal of heredity in the Caltech lab of the protagonist of Schrödinger’s book. Within a few years, Benzer would convert the fuzzy concept of the Mendelian gene of classical genetics into its precisely defined, latter-day molecular-genetic version. I will always believe it a shame that Benzer was not included in the set of Nobel laureates honored for laying the foundations of molecular biology.

In Max’s research group, there was no clear separation between our professional and our private lives, because Max’s benevolent (or in New Age California-speak “caring”) interest in his disciples was all-inclusive. He not only guided our scientific work in the lab, but also supervised, not to say intruded in, what would normally be considered one’s private, after-hours activities, such as dating, partying, concerts, plays, movies, dinner, and camping. As our pater familias, Max considered it his business—if not actually his duty—to inform himself about all facets of our lives. The concept of privacy was not known to him.

Exchanging my anxiety-ridden sovereignty for an insouciant thralldom under which I could leave decisions about my professional and private activities in Max’s hands appealed to me. To give up all that freedom and personal responsibility for making choices with which I had been saddled was a relief. It was like being in the Army, where every soldier, downward from the Chairman of the Joint Chiefs of Staff, takes orders from a superior authority figure, who is held accountable for the commands one obeys.

It took Wollman and me most of our second year at Caltech to write three papers presenting the results of our experiments on the tryptophan activation and to hone our theory to account for them. I would never again devote as much effort and care to any of the couple hundred other papers and essays I eventually published, and I consider those three papers with Wollman as my best. Max predicted that one day they would be famous classics. Alas, only a few people read them when they came out—we did get one fan letter from an immunologist in Australia—and they have long since been forgotten.

As I had feared, there was no need to invoke “other laws of physics” to explain the seemingly bizarre dynamics of the tryptophan activation phenomenon. We managed to devise a model based on conventional physicochemical principles that accounted for all the data. It was a forerunner of the “cooperative” models of the complex interactions of small molecules with enzymes and other protein molecules put forward a few years after our papers, which have formed the basis for understanding the regulation of protein function ever since. As far as I know, no contributor to the vast literature of cooperative protein interactions ever cited our tryptophan activation model.

DNA Replication

My Merck Fellowship was to end in June 1950, and Max suggested that I go to Copenhagen to work in the lab of the Danish biochemist Herman Kalckar. He made the same proposal to Jim Watson, who was finishing his Ph.D. dissertation with Luria at Indiana University. Max told us that it might do us good to learn something about DNA chemistry from Kalckar. Max had begun to think that DNA did have something to do with genetic self-replication, although he had not yet cottoned to the idea that DNA was the genetic material of the phage—Schrödinger’s aperiodic crystal of heredity.

What he didn’t realize was that Kalckar knew very little about DNA.His specialty was adenosine triphosphate (ATP) and its provision of free energy for driving biochemical reactions. Maybe Max thought that DNA, being composed of ATP-like nucleotides, provided the free energy for driving self-replication of proteinaceous genes, in chromosomes as well as in phage. Within a couple of weeks after Jim and I showed up in Kalckar’s lab at the University of Copenhagen in September 1950, we realized that we weren’t going to learn anything about DNA from him, and so we moved over to Ole MaalØe’s lab at the Danish State Serum Institute. There we carried out radioactive tracer studies on the fate of the parental phage DNA and the synthesis of the progeny phage DNA in the infected bacterial host cell.

One of our labmates at the Serum Institute was Niels Jerne, who was studying the increase in antibody–antigen avidity during the immune response. We found his results only mildly interesting, not realizing that we were attending the gestation of his selective theory of antibody formation, which would revolutionize immunology in the late 1950s and bring Jerne the 1984 Nobel Prize in Physiology or Medicine. Our own results were not exactly world-shaking, but they helped to define the problem of DNA replication that had to be solved. At the end of our Copenhagen year, Jim Watson moved to Cambridge to learn how to do X-ray crystallography on DNA. There he met Francis Crick, to whom it had also occurred that knowing the three-dimensional structure of DNA would be likely to provide important insights into the nature of the gene. The result of their collaboration—the discovery of the DNA double helix—is history.

Meanwhile, I went to Paris to spend the last of my postdoctoral Wanderjahre in André Lwoff’s Department of Mircobial Physiology at the Institut Pasteur. I didn’t accomplish much in the way of research results there, but my intellectual development profited enormously from my close contacts with the brilliant crowd hanging out in the “Attic of Monsieur Lwoff” at Pasteur, such as Jacques Monod, Roger Stanier, and François Jacob, in addition to le grand patron himself and my old Caltech copains, Élie Wollman and Seymour Benzer.

My main accomplishment in Paris was getting married. I had met my future wife, Inga Loftsdottir, in Copenhagen at the boardinghouse where Jim Watson and I took our evening meals. She was Jim’s table partner, and he introduced her to me as the Herring Princess of Reykjavik. I was in thrall of the stupendous romance associated with Iceland under the Teutonic mystique of an Ultima Thule. Stark glaciers, volcanoes, and geysers; handsome, tall, invincible men and beautiful women with long, braided blond hair, in colorful medieval costumes. I was captivated by Inga’s good looks, quite apart from the built-in glamour that came with her being a Viking maiden. Moreover, I was enchanted by her professional-level piano playing on her huge grand, which took up almost all the space in her room at the boardinghouse. In the fall of 1951, we went to Paris together, where she studied piano with Reine Gianoli at the École Normale de Musique.

Just before leaving Copenhagen for Paris, I managed to line up a stateside job to which I could return with my bride in the fall of 1952. At a dinner that Niels Bohr gave for the galaxy of star-virologists who had come to Copenhagen to attend the International Poliomyelitis Congress (to which Bohr had invited me as his sole scientific grandson, via Max, in virus research.) I happened to be seated next to Nobel laureate Wendell Stanley. Having heard that he was recruiting people for his Virus Laboratory in Berkeley, I asked him whether there might be an opening; his offer of a research position in Berkeley equivalent to the rock-bottom academic rank of Instructor reached me a few weeks later in Paris. Eventually, I learned that although a Nobel laureate, Stanley never missed a chance to add yet another feather to his cap—however tiny a feather—and he fancied the idea of having on his staff someone he imagined was a young intimate of Niels Bohr’s.

I spent my entire academic career as a member of the Berkeley faculty, eventually becoming founding chairman of a mega-Department of Molecular and Cell Biology with a faculty of 90 professors and, as Stanley’s successor-twice-removed, the Director of the Virus Lab.

A few months before I left Paris, Alfred Hershey and his young assistant, Martha Chase, had shown that when the phage infects its bacterial host, only its DNA enters the cell while its protein stays behind at the gate, devoid of any further function in the reproductive drama about to ensue within. Thus the genes of the parent phage that are responsible for directing the synthesis of progeny phages reside in its DNA. Inspired by the Hershey-Chase results, on setting up shop in the Berkeley Virus Laboratory I resumed the studies on the replication of phage DNA I had begun in Copenhagen, but now using the “suicide” of ³²P-labeled phages recently discovered by Hershey, Martin Kamen, J.W. Kennedy, and Howard Gest. This suicide arises from the lethal cut of both polynucletide strands of the double helix by 1 out of 10 decays of a radioactive ³²P atom incorporated in the phage DNA. Nine out of 10 decays, however, cut only the single polynucleotide strand in which it occurs and leave intact the reproductive potential of the phage. The suicide method allowed us, i.e., my first graduate students and postdoctoral associates (among them Clarence Fuerst, Gordon Sato, Hisao Uchida, and Niels Jerne), to follow the fate of the DNA of the infecting phage after its entrance into the bacterial host cell. The results of our experiments indicated that in the course of its replication, the parental phage DNA is broken into several variously sized chunks, of which about a third reappear in the DNA of the progeny phage, and that this breakup is associated with genetic recombination. But contrary to my hope, we were not able to demonstrate by use of³²P decay suicide the semiconservative mode of the DNA replication process predicted by the Watson-Crick model.

It was after I bewailed our failure to Matthew Meselson on his visit to my laboratory that he devised his ingenious differential density labeling method by which he and Franklin Stahl managed to deliver their justly celebrated proof that had eluded me. A year after the Meselson–Stahl experiment, my postdoc, David Pratt, and I provided an independent, genetic proof of the semiconservative mode of phage DNA replication. We showed that most (base-analog-induced) phage mutants arise as heterozygotes, which carry the mutant allele in only the most recently replicated of the two strands of the double helix, while the strand that served as the template in the last replication round still carries the nonmutated allele. But by then it was too late; hardly anyone paid any attention to our frightfully clever paper.

DNA Expression

Eight years after the discovery of the DNA double helix, a new chapter began in the history of molecular biology. The formerly paramount problem of gene replication had been solved, at least in its broad outlines, and the focus of interest had shifted to the puzzle of how genes manage to express the hereditary information they encode in their DNA. This problem was solved, also at least in its broad outlines, by 1961, by the formulation of two great theories. One, the Central Dogma, in whose development and eventual validation Watson and Crick also played a leading role, asserted that gene expression is a two-stage process. In the first stage, the nucleotide sequence inscribed into DNA is transcribed onto RNA, and in the second stage the RNA transcipt is translated into its specifically encoded polypeptide chain by the cellular machinery for protein synthesis.

The other great theory, the operon model of regulation of gene expression developed by François Jacob and Jacques Monod, asserted that the Central Dogma’s DNA transcipt is an ephemeral, short-lived messenger RNA (mRNA) molecule, which is picked up by a ribosome on whose surface it is translated into the encoded polypetide chain. The operon model also asserted that the rate at which a given polypeptide chain is produced in the cell relative to all other genetically encoded polypeptide chains is determined by the rate at which its mRNA template is transcribed relative to all other mRNA species. The relative rate of mRNA transcription is, in turn, controlled by the interaction between an operator locus encoded in the DNA near the origin of mRNA transcription and a repressor molecule, whose affinity for the operator locus depends, in turn, on its own intraction with an inducer molecule.

So in the early 1960s, I switched my focus of interest from DNA replication to the exploration of the mechanism and control of DNA expression, guided in my thinking by the Central Dogma and the operon model. I began my new line of research during a sabbatical at the Cavendish Laboratory of the University of Cambridge, where Watson and Crick had discovered the DNA double helix. There, in collaboration with Sydney Brenner, I studied the regulation of transcription of ribosomal RNA (rRNA), which, being a stable part of the machinery of translation, is not itself translated into polypeptide chains and composes the bulk of cellular RNA. Brenner and I were able to identify a genetic locus, which we designated RC, that regulates the differential rate of rRNA transcription in accord with the availability of amino acids for protein synthesis. The mechanism by which this cell-physiologically critical gene implements its control turned out to be an enormously complex instantiation of the operon model which took about 10 years to work out and gave rise to a minor cottage industry.

On my return to Berkeley from Cambridge, I assembled a new crew of graduate students and postdoctoral associates for the study of DNA expression. Before long, two members of that crew, Hans Bremer and Michael Konrad, showed that in the DNA-RNA hybrid molecule which arises in the transcription process, only the most recently assembled RNA nucleotides are still in contact with their DNA template, while the older parts of the polynucleotide transcript have already dissociated from it. This finding suggested to me that in bacteria (if not in eukaryotes) mRNA transcription and translation are dynamically coupled processes. Thus I envisaged that a ribosome picks up a nascent mRNA molecule from its DNA template and starts translating it before transcription of the whole messenger molecule is even complete.

According to Karl Popper’s demand for “falsifiability” of scientific theories (which I don’t accept), my hypothesis of dynamic coupling of transcription and translation had the merit of being falsified if any one of three conditions failed to obtain. First, there should arise an in vivo complex of template DNA, nascent mRNA, and ribosomes. Second, the chemical direction in which mRNA is synthesized must be the same as the chemical direction in which it is translated. Third, because of the triplet nature of the genetic code in vivo, the rate of chain growth of mRNA (i.e., the number of nucleotides added per unit of time) must be three times the rate of polypeptide chain growth (i.e., the number of amino acid residues added per unit of time).

Being actual people rather than Popperian logical robots, we set out to verify rather than falsify these conditions. As for the first condition, Bremer and Konrad showed that it is met, by isolating the conceptually obligate DNA–mRNA–ribosome complex from phage-infected bacteria. The second condition was met as well. Bremer and Konrad showed that the synthesis ofmRNA proceeds from the 5’ phosphate end of the molecule toward its 3’ hydroxyl end, while a group working in the laboratory of Severo Ochoa studying the synthesis of oligopeptides directed by synthetic oligonucleotide templates showed that mRNA translation proceeds in the same direction, as did also George Streisinger’s analysis of the effects of frameshift mutants in phage DNA on amino acid sequence in phage proteins. Finally, the third condition is met too. One of my postdoctoral associates, Franrois Lacroute, found that at 37° C, the in vivo peptide chain growth rate of the bacterial enzyme, β-galactosidase is 15 amino acid residues per second, while another postdoc, Haim Manor, found that the average chain growth rate of bacterial mRNA under the same conditions is just about three times as great, namely 43 nucleotides per second.

I consider my validated hypothesis of dynamic coupling of transcription and translation as my most significant contribution to molecular biology.

A Prenatal Forecast of the Death of Molecular Biology

At one of our lab lunches at Caltech in fall 1949, when the birth of molecular biology fathered by the discovery of the DNA double helix still lay 4 years in the future, Max intimated to us that he was beginning to lose interest in the gene. He thought that phage research was bound to lead to an understanding of biological self-replication before long. But, he said, Mind you!—Once the self-replication riddle has been solved, there would still remain an even harder problem posed by living creatures—the function of the brain—for which reasonable, physical mechanisms couldn’t even be imagined. Max ventured that some “other laws of physics” were still needed to explain the function of this most mysterious ensemble of atoms in the universe and to explain how mind arose from matter.

To prepare us for our post-molecular–biological future in brain research, Max made us present a series of seminars on sensory neurophysiology. He drew up a list of publications, divided into chunks of three or four papers. Each of us had to pick one chunk for presentation, which, so Max promised us, would turn us all into brain experts by the next spring. Four of the chunks he selected comprised papers on vision, and they were quickly snapped up by the others. The fifth chunk was devoted to hearing, which my false friends left for poor, ignorant me. As I soon realized, my buddies already knew enough about sensory neurophysiology to stay away from hearing, compared to which vision, however complex its function may seem, is a breeze.

My chunk consisted of three papers published in the late 1920s in the Physikalische Zeitschrift under the title “Zur Theorie des Hörens” by the future (1961) Nobel laureate, Georg von Békésy, then at the Royal Hungarian Telegraph Research Laboratory in Budapest. My reading bogged down as soon as I got beyond the first sentence of Békésy’s first paper, which declared grandly that “the treatment of a series of problems in telephone technology is greatly impeded by the lack of a theory of hearing.” The papers were full of complex equations and circuit diagrams relating to hydrodynamics, resonance, and mechanical and electrical oscillators, while the text was couched in esoteric anatomical and physiological parlance, completely beyond my ken.

This, my first encounter with the literature of neurobiology, was counterproductive to Max’s missionary goal of arousing our interest in brain research. Maybe there were some “other laws” that could be revealed by studying hearing, but there was no way in which I could possibly find them. No Sir, I was going to stick with simple research on phage and bacteria. I was not alone among Max’s early disciples in refusing to switch to brain research at that time. Only Max himself stopped working on phage in the 1950s and took up sensory physiology, selecting as his experimental paradigm the growth response to light of the fungus Phycomyces.

It was not until the late 1960s that Seymour Benzer and I, and a few other romantics who had once been seduced by Schrödinger’s What Is Life?, realized the truth of Max’s prophecy that the brain would be the last exciting frontier of biological inquiry. By then, our kind of molecular biology—the avant garde discipline practiced by a closely knit coterie of aficionados of heredity and self-reproduction—no longer existed. Killed by success, romantic molecular biology had transformed into a mainstream academic and industrial mass movement in which there was no place for Max’s snobby little Phage Church.

The Hebb Synapse

Seymour told me that the best place for me to take my orders in brain research was Steven Kuffler’s Department of Neurobiology at Harvard Medical School, whose staff included his famous students, David Hubel and Torsten Wiesel, the Watson and Crick of neurobiology. Seymour recommended me to Kuffler, whom he had met at Woods Hole, as being serious in wanting to become a neurobiologist, rather than intending to do molecular biological schnapps experiments to decide whether memory resides in RNA, DNA, or protein molecules. In view of the dire shortage of electrophysiological setups in his department, it seemed to border on irresponsibility for Kuffler to waste any of them on a total ignoramus like me. But, in an uncharacteristically softheaded move, he agreed to take me on anyhow for my sabbatical year.

On my arrival in Boston in fall 1969, Kuffler’s very first piece of advice turned out to be the best counsel he ever gave me. He suggested that I, his eldest postdoc, work with his youngest faculty member, John Nicholls, who turned out to be a perfect teacher. Moreover, Nicholls also happened to be working on the leech, whose simplicity and experimental accessibility seemed like God’s gift to a hacker like me who lacked all surgical or electrophysiological skills. The central nervous system of this wonderful, unjustly maligned annelid worm consists of a chain of 32 iterated segmental ganglia linked by a longitudinal connective nerve. Each of these ganglia contains the somata of about 400 bilaterally paired and a few unpaired neurons, which project their axons to peripheral targets via segmental nerves, to targets in anterior or posterior segments via the connective nerve. By the time I joined him, Nicholls had already identified many leech neurons, with respect to their function and connectivity. It took me the whole year to acquire the bare minimum level of skills needed for neurophysiological experimentation, and I hadn’t contributed anything of value to my teacher’s research project when the time came for me to go home to Berkeley.

There was a tradition in the Kuffler department of a weekly lunch seminar at which the graduate students, postdocs, and faculty members reported their recent research results. When my turn came and I had no research results to report, I decided to present the results of my recent reading of a brilliant paper by the young English mathematician, David Marr, on the cerebellar cortex as a learning machine. The feature of Marr’s paper that interested me most was his idea that the cerebellum can learn to perform complex motor routines thanks to modifiable synapses that link parallel fibers and Purkinje cells. Marr proposed that these synapses have the property first put forward by Donald Hebb in 1949 to account for classical conditioning, namely that their activation or inactivation in a plastic neural network rises or falls with the synchronicity of the impulse activity of pre- and postsynaptic neurons.

I closed my seminar with a theory I had devised for a physiological mechanism by which the postulated property of the Hebb synapses could be instantiated at the subcellular level. I proposed that the receptors for the synaptic neurotransmitter are eliminated from the postsynaptic membrane by the transient reversals of membrane polarization that occur during action potentials in the postsynaptic cell. This would lead to inactivation of the synapse. But because the release of neurotransmitter by the presynaptic cell anchors the membrane potential of the subsynaptic region of the postsynaptic cell at a level about half-way between the negative-inside resting potential and the positive-inside action potential, the membrane patches surrounding the receptors of a synapse, whose activity has contributed to setting off the postsynaptic impulse, would be spared the full extent of the noxious polarity reversal. Thus only synchronous, but not asynchronous, activity of pre- and postsynaptic cells would preserve the existing strength of the synapse.

My seminar was not appreciated by my Harvard colleagues, who regarded neurobiological theorizing as snake oil selling. They didn’t conceal their exasperation over my wasting their time, especially when it came to my own proposal of a mechanism for the, in any case wholly fictive, Hebb synapse. Despite the disdain of my Harvard colleagues, I wrote a paper on my proposed Hebb synapse mechanism and asked a distinguished Berkeley physicist to communicate it to the Proceedings of the National Academy of Sciences, which did not then (as it does now) require an expert peer review, or my paper certainly would have flunked. Of the more than 100 neurobiological papers that I would eventually publish, this, my first, turned out to be the most successful; it was the only one of them anointed by the Institute of Scientific Information’s Citation Index as a “Citation Classic.”

Leech Swimming and Heartbeat

In making my mid-career switch to neurobiology, I had been strongly influenced by my friend Werner Reichardt, the founder–director of the Max Planck Institute for Biological Cybernetics in Tübingen. His studies of visually controlled locomotion of insects represented a close dialectic between elegant, nonlinear mathematical theories and brilliant quantitative experimental tests of their predictions at the behavioral, anatomical, and cellular level. During the 1950s, Reichardt solved the problem of how moving patterns are perceived by motion detectors of the insect visual system. In the 1960s, he showed how the neural circuitry he unraveled in the insect brain accounts also for perceptual tasks higher than simple motion detection, such as tracking an object in front of a textured background.

On my return to Berkeley in the fall of 1970, I decided to follow Reichardt’s lead and set out to study the visually controlled locomotory behavior of leeches. I thought that because of the simplicity and easy experimental accessibility of the leech nervous system I would soon have the advantage over my friend and beat him at his own game. Unfortunately, I didn’t know then that vision plays only a minor role, if any, in leech locomotion, and so I never posed any real threat to Werner’s primacy. But in the end I did find a few things about the neural control of rhythmic movements that Werner hadn’t worked out.

Of the two locomotory modes of leeches, swimming and inchworm crawling, I decided to study swimming. My predecessor in this investigation, Leonardo da Vinci, had shown in the quattrocento that leeches swim by undulating their flattened body in the dorso-ventral plane, forming a wave which travels from head to tail. The moving crests of the body wave are produced by progressively delayed contractile rhythms of the ventral body wall and the moving troughs by similar, but antiphasic, contractile rhythms of the dorsal body wall. The forces exerted against the water by these changes in body form provide the propulsion that drives the leech forward.

In getting started on this project, I had the luck to acquire an outstandingly competent young neurobiologist as a postdoctoral associate, William B. Kristan. He helped me set up my laboratory for this new line of work and develop a semi-intact leech preparation which carries out the swimming rhythm while permitting intracellular recordings from its central nervous system. We were soon joined by my first neurobiological graduate student, Carol Ort, and within about 3 years we had identified an ensemble of segmentally iterated motor neurons (some of which had been previously identified by Nicholls and Ann Stuart). The rhythmic impulse activity of these motor neurons—some excitatory and others inhibitory—drives the antiphasic local contraction and distension of the longitudinal muscles embedded in the segmental dorsal and ventral body walls. We found, moreover, that the rearward travel of the body wave is attributable to the impulse burst phase of each motor neuron leading that of its serial homolog in the next posterior ganglion by a phase angle of about 20°.

Kristan presently discovered that the motor neurons of a completely isolated leech nerve cord, deprived of all sensory input from the body wall, can exhibit sustained episodes of rhythmic activity. Hence, we could infer that the basic swimming rhythm is produced by a central rhythm generator, whose oscillatory activity pattern is generated independently of any proprioceptive feedback. In collaboration with my second, highly competent neurobiology postdoctoral associate, W. Otto Friesen, we then identified a network of bilaterally paired, rhythmically active interneurons as components of the central swimming rhythm generator. The interneurons of this generator owe their rhythmic impulse burst activity to their being linked into an intrinsically unstable oscillatory network, whose periodic activity pattern arises from the principle of recurrent cyclic inhibition, first proposed in 1967 by the Hungarian neuroanatomist G. Szekely. The central generator imposes the swimming rhythm on the motor neurons via a set of identified excitatory and inhibitory synaptic connections. Kristan and Friesen eventually established their own laboratories, where they continued the study of leech swimming with their students and brought its understanding to progressively higher levels.

When I acquired my second neurobiology graduate student, Wesley Thompson, I made him an uninspired research proposal, namely that he survey the leech ganglion in search of other rhythmically active neurons that might take part in swimming. Before long, Thompson identified two hitherto unknown pairs of oscillatory neurons. Their long cycle period indicated, however, that they had obviously nothing to do with swimming. On pursuing their function, Thompson discovered that they control the beat of the leech “heart,” which consists of two contractile lateral vessels, or heart tubes, that form part of a closed circulatory system. The walls of the heart tubes are ringed by heart muscles, whose periodic contraction and distension, or heartbeat, circulates the blood through this vascular system. Thompson found that the heartbeat pattern is not bilaterally symmetric. On the peristaltic body side, the segmental heart-tube sections constrict in a rear-to-front pattern, producing frontward peristalsis. On the synchronic body side, the sections constrict almost simultaneously. Peristaltic and synchronic heart beat modes are not permanent features of right and left sides, however. Every few minutes, the peristaltic side switches to the synchronic mode and the synchronic side switches to the peristaltic mode.

One of the rhythmically neuronal pairs discovered by Thompson, designated heart excitors, innervates the circular muscles of the ipsilateral segmental heart tube. The heart excitor activity cycles, in which impulse bursts alternate with bursts of inhibitory synaptic potentials, are phaselocked in a manner that corresponds to the segmental heart-tube constriction pattern. The other pair, designated as heart interneurons, is the source of the periodic bursts of inhibitory synaptic potentials in the heart excitors and part of a central heartbeat rhythm generator that does not require peripheral sensory input for its patterned output. Unlike the swim oscillator interneurons, however, the heart interneurons do possess an endogenous polarization rhythm, as indicated by their maintaining a periodic impulse burst activity while deprived of inhibitory synaptic input. Thompson’s pioneering work on the leech heartbeat system was continued by my later postdoctoral associate, Ronald Calabrese.

Cell Lineage in Leech Development

In the late 1970s, my research interests shifted from the functional organization of the adult leech nervous system to its genesis in embryonic development. Two veteran, card-carrying leech biologists, Roy Sawyer and Juan Fernandez, had joined my laboratory and drawn my attention to the stereotyped sequence of cell divisions which, onward from the fertilized leech egg, gives rise to an embryo with individually identifiable cells. As early as the 1870s, Charles Whitman, the American founder of experimental embryology, had ascertained by direct microscopic observation of the early leech embryo that a definite developmental fate could be assigned to each of its blastomeres and inferred that the differentiated properties that characterize a given cell in the mature animal are causally linked to its developmental line of descent. Despite these highly promising beginnings, the study of developmental cell lineage went into decline at the turn of the 20th century, until it was revived in the 1970s, when novel techniques capable of revealing cell lineage became available.

One of these novel techniques—intracellular lineage tracers—was developed in my laboratory by my postdoctoral associate, David Weisblat. It consists of microinjecting into an identified embryonic cell a tracer molecule that is passed on to all, and only to, the lineal descendants of the injected cell. These descendants can then be identified at a later developmental stage by observing the distribution pattern of the tracer within the embryonic or postembryonic tissues. The first tracer molecule used by Weisblat was the enzyme horseradish peroxidase, whose intracellular presence can be detected by treatment of the labeled tissues with a histochemical agent that causes formation of a black precipitate in any cell containing the enzyme. Later we developed lineage tracers consisting of an adduct of a fluorescent dye, such as fluorescein or rhodamine, and an inert carrier molecule, such as dextran. The cellular distribution of fluorescent tracers can be observed in living tissues under the fluorescence microscope, in contrast to horseradish peroxidase, which can be detected only in dead tissues killed by the reagent treatment.

By use of the cell lineage tracer technique, we managed to identify the ensemble of founder cells of each of the leech’s 32 body segments, trace the individual lines of descent of the identified components of its nervous system and musculature, clarify the process of neuroblast commitment to a particular developmental cell fate, and chart the pattern of postmitotic neuronal migration and axon outgrowth. The members of my laboratory engaged in this work at various times during the next decade included also Jochen Braun, Siegward Elsas, Lydia Glazer, Andrew Kramer, Martin Shankland, Duncan Stuart, Steven Torrence, and Saul Zackson. Eventually, Weisblat and Shankland each established his own highly productive laboratory and became an internationally renowned leader in the developmental biology of the leech.

Neurophilosophy

In my junior year at Illinois I had chosen philosophy as a secondary major because a fraternity brother had advised me that philosophy was a cinch. To get started, I signed up for a course with the seemingly weird title “Philosophy of Science,” taught by Max Black, the Russian-born, British-trained analytic philosopher. “What’s philosophy got to do with science?” I wondered. As I eventually found out, you don’t need to study philosophy to do good science. But, contrary to the opinion of many eminent scientists, you do need to study it if you want to participate in philosophical discourse without making a fool of yourself. Philosophy became my “secondary major” also in my professional career.

I made my debut as a philosopher when I published The Coming of the Golden Age: A View of the End of Progress, lectures I gave under my special appointment as Professor of Arts and Sciences for the 1967–1968 academic year, during the Free Speech Movement student revolt on the Berkeley campus. In these lectures, I tried to persuade my faculty colleagues and the few students who came to hear me that the Free Speech Movement was just one more omen of the end of the 10,000-year-long historical era of progress. Progress, which brought mankind ever-greater dominion over Nature, started with the neolithic agricultural–urban revolution and, so I declared, is ending in our time because its inherent self-limitations are now being reached. In successive lectures, I presented a set of diverse arguments in support of my thesis, drawn from epistemology, psychology, economics, and sociology, and applied them to the end of science and the arts which we are witnessing in the latter, postmodern half of the 20th century. Only a few thousand copies of my Golden Age book were sold and, except for a brief, favorable review in The New Yorker and a Marxist panning in the Moscow Literaturnaya Gazeta, it did not attract much critical notice. Nevertheless, my announcement of the end of science and the arts made me enough enemies to last a lifetime.

In later years I published philosophical essays on other topics, such as “Prematurity and Uniqueness in Scientific Discovery” (1972), “The Dilemma of Science and Morals” (1974), “Limits to the Scientific Understanding of Man” (1975), “The Poverty of Scientism” (1975), “Morality as a Scientific Phenomenon” (1978), and, in collaboration with Judith Martin, “A Philosophy of Etiquette” (1990).

My philosophical sensibilities were shocked when, in 1986, I read Patricia Churchland’s Neurophilosophy, which Science magazine had asked me to review. According to Churchland, the agenda of neurophilosophy is to produce, by means of an interaction among philosophy, psychology, and neuroscience, a uniform theory that explains what she calls the “the mind brain.” I too, like almost every other author who writes on the subject, have always advocated an interaction among these three disciplines to advance our understanding of mental processes. But, as I pointed out in my review, I doubt that what Churchland called her “cardinal hunch,” namely “that to discover our nature, we must see ourselves as organisms in Nature, to be understood by scientific methods and means,” can fathom the depth of the ancient mind-body problem. There are compelling metaphysical reasons why that problem has persisted ever since there have been philosophers and biologists, onward from Plato and Aristotle, and why dualist solutions that are contrary to “scientific methods and means” keep on being put forward by people who know all about the brain. The reason for the perennial persistence of dualism is simply that hardly anybody actually shares Churchland’s cardinal hunch and that, instead, nearly everybody is beholden, willy-nilly, to the ancient—possibly categorically innate—paradoxical theory of our being half beast, half divine, whose explicit Judeo–Christian version was first published in Genesis.

In my most recent philosophical essay I pointed out that a satisfactory solution to the mind-body problem has actually been available since the latter part of the 18th century, when Immanuel Kant put forward the idea that we live in two metaphysically distinct worlds, both constructed by our mind, whose architecture each of us shares with our fellow humans. One of these worlds is constructed by our faculty of theoretical reason whose natural objects are governed by the laws of causal determination that science tries to fathom. The other world is that constructed by our faculty of practical reason whose supernatural, rational human subjects are governed by laws of freedom that ethics tries to fathom. Thus, according to practical reason, the notion of free will—nonsensical from the viewpoint of theoretical reason—is a rationally necessary constituent of the metaphysical concept of personhood that governs interpersonal human relations. And that is why, to discover our nature, we must see ourselves as organisms in, as well as out of Nature, to be understood by scientific as well as metaphysical methods and means.

Selected Bibliography

Braun J, Stent GS. Axon outgrowth along segmental nerves in the leech. Dev Biol 1989;132:471–485, 486–501.

Bremer H, Konrad MW, Gaines K, Stent GS. Direction of chain growth in enzymic RNA synthesis. J Mol Biol 1965;13:540–553.

Delbrück M, Stent GS. On the mechanism of DNA replication. In: McElroy WD, Glass B, eds. The chemical basis of heredity. Baltimore: Johns Hopkins University Press, 1957;699–736.

Fernandez J, Stent GS. Embryonic development of the glossiphoniid leech Theromyzon rude: structure and development of the germinal bands. Dev Biol 1980; 78:407–434.

Friesen WO, Stent GS. Generation of a locomotory rhythm by a neural network with recurrent cyclic inhibition. Biol Cybernet 1977;28:27–40.

Gleizer L, Stent GS. Developmental origin of segmental identity in the leech mesoderm. Development 1993;117:177–189.

Keleher GP, Stent GS. Cell position and developmental fate in leech embryogenesis. Proc Natl Acad Sci USA 1990;87:8457–8461.

Kramer AP, Goldman JR, Stent GS. Developmental arborization of sensory neurons in the leech Haementeria ghilianii. J Neurosci 1985;5:759–767, 768–776.

Kretz JR, Stent GS, Kristan WB, Jr. Photosensory input pathways in the medicinal leech. J Comp Physiol 1976;106:l–37.

Kristan WB, Jr, Stent GS, Ort CA. Neuronal control of swimming in the medicinal leech. J Comp Physiol 1974;94:97–119, 121–154, 155–176.

Manor H, Goodman D, Stent GS. RNA chain growth rates in Escherichia coli. J Mol Biol 1969;39:l–29.

Martin J, Stent GS. I think; therefore I thank. A philosophy of etiquette. Am Scholar 1990;59;(2):237–254.

Pratt D, Stent GS. Mutational heterozygotes in bacteriophages. Proc Natl Acad Sci USA 1959;45:1507–1515.

Schrödinger E. What is life? Cambridge: Cambridge University Press, 1946;68–69. Stent GS, Maaloe O. Radioactive phosphorus tracer studies on the reproduction of

T4 bacteriophage. II Kinetics of phosphorus assimilation. Biochim Biophys Acta 1950;10:55–69.

Stent GS, Fuerst CR. Inactivation of bacteriophages by decay of incorporated radioactive phosphorus. J Gen Physiol 1955;38:441–458.

Stent GS. Decay of incorporated radioactive phosphorus during reproduction of bacteriophage T2. J Gen Physiol 1955;38:853–865.

Stent GS, Jerne NK. The distribution of parental phosphorus atoms among bacteriophage progeny. Proc Natl Acad Sci USA 1955;41:704–709.

Stent GS, Sato GH, Jerne NK. Dispersal of the parental nucleic acid of bacteriophage T4 among its progeny. J Mol Biol 1959;1:143–146.

Stent GS, Brenner S. A genetic locus for the regulation ofribonucleic acid synthesis. Proc NatlAcad Sci USA 1961;47:2005–2014.

Stent GS. Genetic transcription. Proc R Soc London B 1966;164:181–197.

Stent GS. The coming of the golden age: A view of the end of progress. New York: The Natural History Press. 1969. [Paperback edition, 1971; Castilian edition, Seix Barral, Barcelona, 1973; Japanese edition, Misuzu Shobo, Tokyo, 1972, French edition, Fayard, Paris, 1973].

Stent GS. Molecular genetics: An introductory narrative. San Francisco: W.H. Freeman, 1971. [Castilian edition, Ediciones Omega, Barcelona, 1973; Russian edition, Isdatelstvo “MIR”, Moskva, 1974; Italian edition, Zafirelli, Bologna, 1977; Chinese Edition, Academia Sinica, Beijing, 1978]

Stent GS. A physiological mechanism for Hebb’s postulate of learning. Proc Natl Acad Sci USA 1973;70:997–1001.

Stent GS. Limits to the scientific understanding of man. Science 1975;187:1052–1057.

Stent GS. Paradoxes of progress. San Francisco: W.H. Freeman, 1978a. [Spanish edition, Alhambra, Madrid, 1981]

Stent GS. Morality as a biological phenomenon. Berlin: Dahlem Konferenzen, 1978b. [Reprinted by University of California Press, 1981]

Stent GS. The role of cell lineage in development. Phil Transact R Soc London 1985; B312:3–19.

Stent GS. The poverty of neurophilosophy. J Med Philo1990;15(5):539–557.

Thompson WJ, Stent GS. Neuronal control of heartbeat in the medicinal leech. J Comp Physiol 1976;111:261–279, 281–307, 309–333.

Wall FT, Stent GS. A theory of vapor pressures of liquids based on van der Waals’ equation of state. II Binary mixtures. J Chem Phys 1949;17:1112–1116.

Weisblat DA, Sawyer RT, Stent GS. Cell lineage analysis by intracellular injection of a tracer enzyme. Science 1978;202:1295–1298.

Weisblat DA, Harper G, Stent GS, Sawyer RT. Embryonic cell lineage in the nervous system of the glossiphoniid leech Helobdella triserialis. Dev Biol 1980;76:58–78.

Weisblat DA, Kim SY, Stent GS. Embryonic origins of cells in the leech Helobdella triserialis. Dev Biol 1984;104:65–85.

Wollman EL, Stent GS. Studies on activation of T4 bacteriophage by cofactor. Biochim Biophys Acta 1950;6:292–306, 307–316, 374–383, 9:538–550.