Studies on the flexor reflex. VI.—Inhibition

Abstract

Since it was first described (Sherrington, 1907 ; 1909; Sherrington and Sowton, 1911), inhibition of the flexor reflex by stimulation of contralateral afferent nerves has not been so systematically studied as inhibition of extensor reflexes. This comparative neglect is possibly due to its frequent absence when sought for against the background of a tetanic flexor reflex (Graham Brown, 1914). Sherrington and Sowton (1915), however, showed that a series of flexor reflexes evoked by single break-shocks could be regularly inhibited from contralateral nerves, and by using this technique it was possible to demonstrate the slow passing off of inhibitory after-effect subsequent to the stimulation of a contralateral nerve. An important contribution to the study of inhibition was published by Samojloff and Kisseleff (1927), who employed single flexor reflexes or slow series of single flexor reflexes as backgrounds for the investigation of the inhibition arising from the stimulation of contralateral nerves. Their most important finding was that the flexor reflex evoked by a single excitatory volley suffered inhibition from a single inhibitory volley (contralateral) which preceded the excitatory volley by intervals between 10 σ and 300 σ. The present investi­gation is an attempt to study the nature of this long-lasting inhibition.