Sherrington, C. S.
Sherrington, C. S.
Sir Charles Scott Sherrington (1857-1952) made an overwhelming contribution to the foundations of modern neurophysiology through his experiments and theories on the functioning of the spinal reflexes. Sherrington’s importance to the behavioral scientist lies in the fact that he used mainly the methods of behavioral science to pursue his investigations. He studied the behavior of animals after the influence of higher neural centers had been removed surgically by spinal transection. From such behavior he formulated hypotheses about the nature of the nervous system, which he tested by further experiment.
Sherrington was born in London, the son of a country doctor. Although his curriculum at school did not include science, he later enrolled as a medical student at St. Thomas’s Hospital in London. Before he completed his clinical studies there in 1885 he worked in the physiology school at Cambridge University and he also spent almost a year with Friedrich Goltz and Carl Anton Ewald in Strasbourg. It was in Goltz’s laboratory that he saw the reactions of a dog with a high spinal transection. The investigation of such phenomena was to form his major scientific interest until 1935, the date of his retirement from the Waynflete professorship of physiology at Oxford. Although something was known of reflex action in a general way, Sherrington’s thorough investigations transformed the study of reflex action into a tool for the understanding of nervous activity.
His book The Integrative Action of the Nervous System (1906) summarizes his most important contributions. The problem that Sherrington posed himself was how the truncated nervous system of the spinal animal produces motor reactions that are coordinated both in space and in time when stimuli are applied. He saw that stimulation of motor pathways alone leads to contortions rather than to actions and that the properties possessed by nerve trunks alone are not sufficient to endow the nervous system with the means of achieving the behavior that he observed. To account for the difference in reaction to different stimuli Sherrington had recourse to the notion of an adequate stimulus, or the idea that the function of a receptor is to make available a particular reflex only to specific physical stimuli. Furthermore, Sherrington was struck by the presence of an after-discharge (the tendency for a reaction to persist after the stimulus has been withdrawn), by differences in latency of reaction when stimuli of differing strength are applied, and by the irreversibility of conduction in the reflex arc. To explain these and other discrepancies between the action of nerve trunks and the nature of the connection between stimulus and response, Sherrington postulated the functions of the synapse, the name of which he coined. This synaptic hypothesis, based almost entirely on behavioral observations, has now been strikingly verified by advances in experimental technique. On the synaptic hypothesis, messages travel from one nerve cell to another across a small gap between the two cells. Thus there is a functional connection between the two cells as distinct from a physical fusion of their membranes. Transmission across this gap is different in kind from transmission along the processes of the nerve cell itself. (It is now known that in the vertebrate nervous system such transmission across the synapse generally occurs by means of diffusion across the gap between the nerve cells—the synaptic cleft—of small amounts of chemical substances, such as acetylcholine.) He used this hypothesis further to account for interactions between reflexes, and he also introduced the notion of the final common path, thus narrowing down the locus at which one reflex inhibits another. He provided a detailed physiological basis for the mechanism of chain reflex, a notion propounded both by Exner and by Jacques Loeb, which is of great importance to behaviorism.
It should be stressed that Sherrington, in his more than three hundred publications, made contributions to many fields other than neurophysiology, among them the physiology of blood, the psychology of contrast and flicker, and the functional localization of the motor cortex. He was also one of the early scientists to work on the neural basis of the emotions. His discussion of the James-Lange theory in the seventh chapter of The Integrative Action of the Nervous System is still one of the best in the literature. The excellence of his work won wide recognition, and in 1932 he was awarded the Nobel prize for medicine.
Although Sherrington probably contributed more than anyone else to the purely mechanistic understanding of reflexes, he also found it useful to consider them in terms of their purpose, or biological utility. And he was not averse to devoting thought to the more philosophical aspects of the functioning of the nervous system. In his extensive writings on the subject he argued for a Cartesian dualism of body and mind, a position in which Sir John Carew Eccles, another distinguished neurophysiologist, has followed his teacher.
In spite of their profound influence on physiology, the details of Sherrington’s observations and thoughts have little affected the mainstream of behavioral science. However, the general impact of his work, whether rightly or wrongly, contributed to the vogue for analysis in terms of the reflex or of stimulus-response psychology.
J. A. Deutsch
(1906) 1948 The Integrative Action of the Nervous System. 2d ed. New Haven: Yale Univ. Press.
(1925) 1940 The Assaying of Brabantius and Other Verse. 2d ed. Oxford Univ. Press.
1932 CREED, R. S.; Denny-Brown, D.; Eccles, J. C.; Liddell, E. G. T.; and Sherrington, C. S. Reflex Activity of the Spinal Cord. Oxford: Clarendon.
(1940) 1951 Man on His Nature. 2d ed. Cambridge Univ. Press. → A paperback edition was published in 1953 by Doubleday.
1946 The Endeavour of Jean Fernel. Cambridge Univ. Press.
Cohen, Henry 1958 Sherrington: Physiologist, Philosopher and Poet. Springfield, 111.: Thomas; Liverpool Univ. Press.
Liddell, Edward G. T. 1960 The Discovery of Reflexes. Oxford: Clarendon. → See especially pages 98-143, “Sherrington and His Times.”