Sperry, Roger Wolcott
Sperry, Roger Wolcott
(b. 20 August 1913 in Hartford, Connecticut; d. 17 April 1994 in Pasadena, California), neuroscientist and Nobel Prize winner whose split-brain studies dramatically altered views of how the mind works.
Sperry, the elder of the two sons of Francis Bushnell Sperry, a banker, and Florence Kraemer, an assistant to the principal of a local high school, spent his childhood on a farm near Hartford, Connecticut, where he developed a lifelong passion for nature and the outdoors. Neither parent had much formal education. When Sperry was eleven years of age his father died, and the family moved to West Hartford, where Sperry attended William Hall High School, graduating in 1931. An all-star athlete and straight-A student, Sperry won a four-year scholarship to Oberlin College in Ohio, where he worked in the dining halls to cover his board. He graduated in 1935 with a bachelor’s degree in English literature.
Sperry became interested in the subject of memory while he was studying at Oberlin. His decision to remain there for a master’s degree in psychology, which he received in 1937, was heavily influenced by the Oberlin psychology department’s highly experimental and physiologically brain-oriented approach and the quality of its faculty, including Lawrence Cole, Louis Hartson, Homer Weaver, and Raymond H. Stetson, his adviser. A seminar talk by another graduate student on the work of Paul A. Weiss, one of the most influential biologists of his day, led Sperry to spend an extra year at Oberlin as a student-at-large, taking courses in the life sciences in preparation for Ph.D. work under Weiss at the University of Chicago.
At Chicago, Sperry mastered highly skilled neurological techniques, and he disproved a widely held theory about how the brain works that had been put forward by his doctoral adviser, Weiss. According to Weiss’s theory, the huge neural network linking the sense organs and muscles to the brain begins as a bunch of casually connected nerve fibers, which are undifferentiated and unspecified, and becomes, after factoring in experience and learning, the highly coordinated, purposeful system seen in animals. The key ideas underlying this theory, based on meticulous experiments by Weiss that were misinterpreted, had to do with plasticity and interchangeability of function.
In a series of seminal papers published between 1941 and 1946, however, Sperry demonstrated unequivocally that what actually happens during an animal’s development is just the opposite of that postulated by Weiss. Rather than being formed of interchangeable bits and pieces, the brain’s circuits are largely hardwired, meaning that each nerve cell acquires its own chemical identity starting in early embryonic development. From then on the function of the cell is fixed and cannot be altered. Sperry’s experiments involved surgical procedures, starting with rats. The results of his experiments showed that rearranging an animal’s nerve connections produced inappropriate responses that could not be retrained.
Upon completing his doctorate in zoology in 1941 Sperry went to Harvard on a one-year National Research Fellowship and worked with Karl S. Lashley in psychology. In addition to continuing his experiments on the effects of surgical procedures involving peripheral nerves in rats and later in monkeys, Sperry started a new line of research on the selectivity of nerve growth in the visual system, using regeneration of the optic nerve in salamanders. When he surgically rotated the eyes 180 degrees before regeneration, the recovered vision of the animal was also rotated, and the animals saw the world upside down and reversed right to left. As Sperry later said, the animal responded “as if everything seen through one eye were being viewed through the opposite eye.” Moreover, with their eyes inverted, no amount of retraining could restore correct vision to the animal. The experiments showed clearly that the nerves had grown selectively back to their original connections and offered compelling evidence, in Sperry’s words, that nerves grow to specific connections “by intricate chemical codes under genetic control” and predetermination.
Shortly after Pearl Harbor was bombed by Japan in late 1941 Sperry moved to Orange Park, Florida, to continue his postdoctoral work with Lashley, who had left Harvard to become the director of the Yerkes Laboratories of Primate Biology. From 1942 to 1946 Sperry was a biology research fellow at Yerkes, where he continued his nerve-cross experiments on a variety of animals, including rats, fish, and monkeys. On rats Sperry showed that, if the nerve connections in the animal’s hind feet were reversed, an electric shock to the right foot caused a reaction in the left foot and it could not be unlearned. He also continued his work on optic nerves and nerve growth using frogs and salamanders collected locally. From 1942 to 1945 Sperry’s military service consisted of participation in the Nerve Injury Project, a medical research project organized by Weiss under the auspices of the Office of Scientific Research and Development. The project dealt with the surgical repair of peripheral nerve injuries. Sperry’s demonstrations that nerve fibers are not interchangeable and that the design of the brain’s machinery is set early in embryonic development had important consequences for human neurosurgery. Treatment protocols for nerve-damaged soldiers changed substantially after Sperry advised neurosurgeons of the group’s findings in 1945.
In 1946 Sperry returned to the University of Chicago as an assistant professor in the department of anatomy. On 28 December 1949 he married Norma Gay Deupree, a biologist who was one of his many collaborators. They had two children. Soon after his marriage Sperry was diagnosed with tuberculosis, forcing him to spend part of 1950 in the Adirondack Mountains in upstate New York recovering from the disease. During this period he wrote a seminal essay, “Neurology and the Mind-Brain Problem,” published in 1952 in the American Scientist. The article reflected his growing interest in the relationship between the brain and conscious experience. Returning to Chicago, Sperry taught human anatomy to medical students and worked on small tropical fish at Bimini in the Caribbean in the winter months. He started a scientific collaboration with Ronald Myers, a joint M.D. and Ph.D. student, on the corpus callosum, the fiber bridge between the two cerebral hemispheres, whose functions were a mystery to neurobiologists. In 1953 they reported that, when this brain structure was cut, the visual learning was divided in two by the surgery and the transfer of visual information between the two hemispheres ended. Split-brain research became one of Sperry’s primary interests over the next decade.
In 1952 Sperry became section chief of neurological diseases and blindness at the National Institutes of Health and an associate professor of psychology at the University of Chicago. In 1954 he accepted an appointment at the California Institute of Technology (Caltech) as the Hixon Professor of Psychobiology. At Caltech, Sperry developed and extended the split-brain experiments with animals with the help of a long line of graduate students and postdoctoral students. In the early 1960s Sperry began studying the effects of brain splitting on perception, speech, and motor control in human beings whose hemispheres had been cut to control intractable epilepsy. With these patients Sperry discovered that the right hemisphere, like the left hemisphere where the speech center of the brain is located, had its own world of perception, memory, and consciousness. Sperry, who was of average height with a wiry build and piercing eyes that concealed a very shy personality, shared the 1981 Nobel Prize in medicine for his discoveries concerning the specialization of the cerebral hemispheres.
Beginning in 1965 Sperry published a great number of philosophical papers dealing with his own theory of mind and consciousness. He died in Pasadena, California, from a heart attack following a degenerative neuromuscular disease. He was cremated and his ashes were scattered in an undisclosed location.
A small amount of personal biographical material on Sperry is in the Oberlin College archives. Colwyn Trevarthen, ed., Brain Circuits and Functions of the Mind (1990), a collection of essays by Sperry’s colleagues and former students, touches on many phases of his career and his personality and includes a complete bibliography of his writings. “Sperry on Consciousness,” Caltech News (1988), is the closest thing to an autobiographical account of why he changed his thinking about scientific thought and human behavior in the mid-1960s. Personal glimpses of the man, his work habits, and his rich family life are scattered throughout “Paths in the Brain, Action of the Mind,” Neuropsychologia 36 (Oct. 1998): 953—1096, a special issue devoted to Sperry and the main areas of his research by twelve colleagues who knew him professionally over a long time. See also “Roger Wolcott Sperry,” in National Academy of Sciences, Biographical Memoirs, vol. 71 (1997). Obituaries are in the New York Times (20 Apr. 1994), Trends in Neurosciences 17 (1994): 402-404, and American Psychologist 50 (1995): 940-941.
Judith R. Goodstein