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Sperry, Roger
Saturday, December 15 2012, 11:23 AM
Roger Sperry (1913-1994)
Citation:
Todman, D. (2008) History of Neuroscience: Roger Sperry (1913-1994), IBRO History of
Neuroscience
[http://www.ibro.info/Pub/Pub_Main_Display.asp?LC_Docs_ID=3473]
Accessed: date
Don Todman
Roger Sperry was an iconic figure in neuroscience who shared the Nobel Prize in Physiology or
Medicine with David Hubel (b.1926) and Torsten Wiesel (b.1924) in 1981 (Figure 1). His long period
of research questioned established dogmas and led to important discoveries in the fields of neural
development and hemispheric specialization with his work on the human split-brain. His
achievements established him as one of the foremost neuroscientists of the twentieth century.
Roger Wolcott Sperry was born in Hartford, Connecticut in 1913. His father died when Roger was
11 and his mother raised two sons by securing a position as assistant to the principal at a local
high school. At the Hall High School in West Hartford, Sperry was an accomplished athlete who
captained the basketball team and achieved a state record in javelin throw. He studied at Oberlin
College in Ohio on an academic scholarship, completing his bachelor's degree in English in 1935
(Voneida, 1994). He continued at Oberlin and received a masters degree in experimental
psychology in 1937 under Dr RH Stetson (1872-1950), an authority on the physiology of speech.
Subsequently he was accepted as a doctoral student at the University of Chicago under Dr Paul
Weiss (1898-1989), a leading zoologist and researcher on the developing nervous system.
Neural development and the chemoaffinity theory
In the 1940s the prevailing state of knowledge was that the wiring of the nervous system largely
came about through experience. His supervisor Weiss was a prominent advocate of this functional
principle, which suggested that neurons had the capacity to adjust to the characteristics of
associated muscles and/or organs. The concept was summarized in the saying, "function precedes
form". Paul Weiss had developed a reputation for research on the developing nervous system
through his work, which involved the transplants of limb buds in amphibians. Sperry's research
utilized the laboratory rat where he developed skilled neurosurgical techniques.
Sperry's initial experiments involved switching of flexor and extensor muscles in rat's hind limbs
whilst further work involved crossing the nerves to the same muscles (Sperry, 1940, 1942).
According to the functional theory, the laboratory animals would adjust to this change. His studies
showed that in all cases the rats displayed the same awkward limb movements with no adaptation.
These findings conclusively demonstrated that the motor system of the rat was predetermined and
could not be modified by the transplants or with training or time. The significance of this work was
soon apparent as it established that the central nervous system circuitry was indeed hard-wired
for specific functions (Finger, 1999).
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Sperry received his PhD in 1941 and then continued post-doctoral studies with Karl Lashley (18901958) at Harvard University. Lashley was a leading psychobiologist who also shared the
functionalist views of Weiss. In 1942, Sperry and Lashley worked at the Yerkes laboratory of
primate biology in Florida where Sperry pursued his work on neuronal specificity. It was here that
he performed his studies involving the rotation of eyes in amphibians.
Previous work had found that sectioning of the optic nerves in newts could result in nerve
regeneration when the eye was returned into its socket. Sperry designed a series of experiments
in which the optic nerves were cut and the eyes rotated 180°. The question to be tested was
whether their vision would return to normality after a period of adaptation or would the animals
view the world as upside down. In all cases the results were unequivocal. The newts continued to
act as if the world was upside down. When food was presented in the upper field, they looked
down and vice versa. The responses remained the same even after a period of training (Sperry,
1945) (Figure 2). When Sperry traced the regenerated optic nerves into the brain; he found that
the original pattern from eye to brain was maintained, suggesting that the nerves were guided in
some way to their original places of termination (Sperry, 1948). The work was amplified by further
studies in amphibia and on nerve-muscle and retino-tectal regeneration in fish.
Figure 2: When the eye is rotated 1800, the frog's prey catching behavior is inverted (after
Sperry, 1945).
Sperry's experimental results led him to theorize on the nature of this nerve guidance in the
developing or regenerating nervous system. The original concept of a chemical attractant
secreted by target cells and guiding developing neurons was suggested by Santiago Ramón y Cajal
(Cajal, 1909). Cajal's theory of neurotropism in embryonic nerve cell development was based on
hypothetical grounds. Sperry cautiously developed a chemical theory for nerve guidance that
culminated in his chemoaffinity theory (Berlucchi, 2006). He proposed the theory in a series of
publications culminating in his paper in 1963 for the National Academy of Sciences (Sperry, 1963).
When he was awarded the Gerard Prize of the Society for Neuroscience in 1979, the citation
stated: "The chemoaffinity theory soon found wide recognition and is one of the few important
general unifying principles in today's developmental neuro-biology despite the fact that its
molecular basis is unknown" (Voneida, 1994).
Sperry's work had an impact on the practice of neurosurgery during World War II. During the war,
he worked with the Office of Scientific Research and Development (OSRD) in the Nerve Injury
Project. His discoveries led to a change in the surgical management of servicemen with nerve
injuries. Previously it had been common for surgeons to transplant nerves into antagonistic muscle
groups and to submit the patient to retraining in an attempt to restore normal functioning. In
clinical practice the results were unsatisfactory and Sperry's studies led to substantial changes in
these treatment protocols.
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The corpus callosum and split-brain experiments
Sperry returned to the University of Chicago in 1946 where he worked first in the department of
anatomy. In 1949 he married Norma Deupree in Wichita, Kansas. Shortly afterwards he developed
tuberculosis from a laboratory monkey which he had used for nerve transplants. He was appointed
an associate professor of psychology at the University of Chicago in 1952 but moved to the
warmer climates of California in 1954 as the Hixon Professor of psychobiology at the California
Institute of Technology (Caltech).
Sperry's interest in the corpus callosum began as a graduate student. The function of this
structure, also known as the great cerebral commissure connecting the two cerebral hemispheres,
had remained largely unknown. In the early 1930s, Walter Dandy, neurosurgeon at Johns Hopkins
University, split the corpus callosum to gain access to third ventricle tumors (Dandy, 1936). His
observations suggested that patients had no observable ill-effects or mental changes from this
procedure. In the early 1940s, surgical section of the corpus callosum for resistant epilepsy was
performed by William Van Wagenen at University of Rochester medical school. Andrew Akelaitis
performed behavioral and psychological tests on these patients after surgery and reported largely
negative findings with no demonstrable or permanent deficits on cognitive tests (Akelaitis, 1941).
To other investigators these findings were perplexing as it was known that the corpus callosum
consisted of over 200 million nerve fibres connecting the cerebral hemispheres. This lack of known
function led Karl Lashley to remark that the function of a corpus callosum "must be mechanical, to
keep the hemispheres from sagging" (Voneida, 1994).
In the early 1960s, Sperry had the opportunity to examine patients who had callosalectomies by
Drs Philip Vogel and Joseph Bogen in Los Angeles. With his graduate students, Colwyn Trevarthen
and Michael Gazzaniga, he devised a series of tests to examine patients after surgery. The
experiments carefully examined language function as well as a range of cognitive and behavioral
studies. Their work led to dramatic discoveries demonstrating differences between the
hemispheres which had been previously unrecognized. The left-brain was superior in the fields of
analytical and linguistic processing, whilst the right hemisphere was superior in visuospatial abilities
(Gazzaniga, 1965, 1967). The clinical studies were augmented by laboratory experiments which
involved sectioning the corpus callosum of cat's brain. Sperry and his graduate student Ronald
Myers demonstrated that behavioral changes learned in one hemisphere were not transferred to
the other (Myers, 1953). From this work Sperry remarked in a 1964 paper published in Scientific
American: "It was as though each hemisphere were a separate mental domain operating with
complete disregard, indeed, with a complete lack of awareness, of what went on in the other. The
split-brain animal behaved in the test situation as if it had two entirely separate brains" (Sperry,
1964).
The work was published in two seminal papers in Brain in 1965 and 1967 (Gazzaniga, 1965, 1967).
Their observations showed that the right hemisphere also had language capabilities and in one
sense, a person could literally have two consciousnesses. The general public became fascinated
with these split-brain studies although some of the ideas became distorted in the media and
elsewhere. The notion that the right hemisphere was for emotion and art and the left hemisphere
for reasoning and intellectual pursuits was an over-simplification of Sperry's studies and papers
(Figure 3). Nonetheless, these studies on functional specialization in the cerebral hemispheres
brought him to wide public attention and secured his share of the 1981 Nobel Prize in Physiology or
Medicine.
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Figure 3: A schematic representation of certain specialized hemispheric functions (after Zaidel and
Iacaboni, 2002).
Conclusion
Sperry continued at Caltech until his retirement in 1984. In his later life, much of his work was
focused on the theories of mind and consciousness and the mind-brain problem. His first paper,
which touched on the "central issue", was in 1965 in his chapter, New Views on the Nature of Man
(Sperry, 1965). He proposed a "mentalist position", by which he meant that the pattern of brain
dynamics directed and governed neuronal traffic. Thus, in Sperry's view, consciousness was
generated by neural activity but was nonetheless separate from it. In a sense, consciousness
emerged as an independent entity separate from the chemistry and biophysics of single nerve
cells. He proposed an analogy with quantum physics in which interactions of subatomic particles
result in emergent properties that do not resemble the particles from which they arose. Despite
these distinctions, he remained a monist and did not accept the concept of Cartesian dualism or
the "dualist interactionism" advocated by Popper and Eccles in 1977 (Popper, 1977).
Although Sperry's writings had a strong philosophical element, his discoveries in the split-brain
model showed that consciousness could be studied in the laboratory under controlled conditions.
His work has been the impetus for the "cognitive revolution" in which scientists have looked at
consciousness and mental processes in new ways.
By nature Sperry was a shy and somewhat aloof person, but he was also known for his warm
hospitality to his students and many international collaborators. In his latter years he suffered
from a form of progressive lateral sclerosis which affected his mobility and speech, though his
intellectual function was spared. His acceptance speech at the Nobel awards was read for him.
From his early academic studies in English literature he had a life-long interest in the arts and was
an accomplished sculptor and painter. His many scientific discoveries revolutionized foundational
concepts and overturned prevailing theories in neuroscience. In addition to the Nobel Prize, he
received numerous awards and honors including the Lasker award in 1979 and a National Medal of
Science. As Viktor Hamburger stated at the award of the Ralph Gerard prize of the Society for
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Neuroscience in 1979, "I know of nobody else who has disposed of cherished ideas of both his
doctoral and his post-doctoral sponsor, both at that time the acknowledged leaders in their fields"
(Voneida, 1994). Roger Sperry died in 1994 and was eulogized as an exceptional neuroscientist
and person of high ethical standards. Reflecting on his career that had encompassed new ideas in
neural development, split-brain syndrome and consciousness theory, David Hubel concluded: "His
contributions to neuro-biology were titanic" (Hubel, 1994).
Don Todman
Department of Neurology
School of Medicine
University of Queensland, Australia
drtodman@optusnet.com.au
Selected quotations
1. "With few exceptions, the bulk of the collected lesion evidence up through the 1950's into the
early 60's converged to support the picture of a leading, more highly evolved and intellectual left
hemisphere and a relatively retarded right hemisphere that by contrast, in the typical right hand of
brain, is not only mute and agraphic but also dyslexic, word deaf and apraxic, and lacking generally
in higher cognitive function" (Nobel lecture, 1981).
2. "Where there used to be a chasm and irreconcilable conflict between the scientific and the
traditional humanistic views of man and the world, we know perceive a continuum. A unifying new
interpretive framework emerges with far-reaching impact not only for science but for those
ultimate value-belief guidelines by which mankind has tried to live and find meaning" (Nobel
lecture, 1981).
3. "I have never been entirely satisfied with the materialistic or behaviouristic thesis that a
complete explanation of brain function is possible is purely objective terms with no reference
whatever to subjective experience: ie, that in scientific analysis we can confidently and
advantageously disregard the subjective properties of the brain process. I do not mean we should
abandon the objective approach or repeat the errors of the earlier introspective era. It is just that
I find it difficult to believe that the sensations and other subjective experiences per se serve no
function, have no operational value and no place in our working models of the brain" (Discussion in
the first conference on The Central Nervous System and Behavior, 1958).
Bibliography
Akelaitis AJ (1940) A study of gnosis, praxis and language following partial and complete section of
the corpus callosum. Transactions of the American Neurologic Association, 66: 182-185.
Berlucchi G (2006) Revisiting the 1981 Nobel Prize to Roger Sperry, David Hubel, and Torsten
Wiesel on the Occasion of the Centennial of the Prize to Golgi and Cajal. Journal History of
Neurosciences, 15, 4, 369-375.
Cajal SR (1909) Histologie du Système Nerveux de l'Homme et des vertébrés. Tome 1. Paris,
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Finger S (1999) Minds Behind the Brain: A History of the Pioneers and their Discoveries. New York,
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Gazzaniga M, Bogen JE, Sperry RW (1965) Observations on visual perception after disconnection of
the cerebral hemispheres in man. Brain, 88:221-236.
Gazzaniga M, Sperry RW (1967) Language after section of the cerebral commisures. Brain, 90:
131-148.
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