REFLEX INHIBITION BY DORSAL ROOT INTERACTION

Abstract

Dorsal roots L6 and L5 were stimulated in such a way that a volley in one inhibited the motor response to a volley in the other. With multiple microelectrode placements, the potential changes were measured, and the current distribution calculated for a cross section of the cord traversed by these dorsal root fibers. Thus it was possible to follow the intramedullary course of afferent impulses. It was shown that after stimulus of Lg, test volleys in L5 failed to invade collaterals of the primary axons. It was concluded that one type of inhibition involves blocking afferent nerve impulses before they have reached the region of cells.