SOME PROPERTIES OF PYRAMIDAL NEURONES IN MOTOR CORTEX WITH PARTICULAR REFERENCE TO SENSORY STIMULATION

Abstract

The effect of sensory afferent volleys on the responses of cortical pyramidal neurones with descending axons in the medullary pyramid was studied by stimulation of a skin nerve and medullary pyramid and recording with 1 or 2 microelectrodes from the cat''s pericruciate cortex. Sensory stimulation was found to be capable of evoking responses of neurones in the pericruciate cortex including the pyramidal neurones with descending axons and, at times, either facilitating or supressing the cortical neuronal responses to pyramidal volleys. The conduction velocity of 72% of the pyramidal fibers studied was about 8 m/sec. The conduction velocity of 42% and of 10% of the pyramidal fibers was faster than 23 m/sec and 95 m/sec, respectively. The refractory periods of pyramidal responses varied between 1.5 and 2.5 msec.