Some Effects of Deafferentation on Neurons of the Cat Spinal Cord

THE firing characteristics of individual neurons of the mammalian nervous system have been studied in varying structures with a wide range of stimuli, anesthetics, and surgical procedures, while attention has not been focused upon comparing spontaneous activity in normal and abnormal states. Previous studies of activity in the cortical epileptic focus by Ward et al1-4have elucidated two attributes of "epileptic" neurons: autonomous high-frequency bursts and loss of synaptic drive which has been attributed to the absence of dendritic spines.5On the basis of these investigations, it has been postulated that the "epileptic" cell is in a state of partial functional deafferentation and that the abnormal firing pattern is a consequence of this deafferentation. Studies utilizing cortical neurons cannot divorce afferent from efferent activity because of the complex geometry of the cortical feltwork but the anatomy of the spinal cord permits deafferentation without manipulation of efferent systems.