Relationship between afferent input and motor outflow in cat motorsensory cortex.

Abstract

The motorsensory cortex apparently contains discrete localized regions in which microstimulation causes facilitation of monosynaptic reflexes in individual forelimb muscle nerves. The nature of inputs converging into such cortical efferent zones was examined by using a technique of intracortical microstimulation and extracellular unit recording through the same microelectrode. The effect of cortical stimulation was monitored by electromyograms recorded from individual muscles. It was found that efferent inputs to individual efferent zones are polymodal, consisting of inputs from receptors in skin, deep tissues and joints. For a given efferent colony, the peripheral localization of unit receptive fields is related to the muscle whose contraction is controlled by that efferent colony. The efferent zone which activates a particular muscle receives skin input predominantly from a skin region which lies in the pathway of limb movement produced by contraction of the muscle to which that zone projects. The efferent zone also receives joint input predominantly from the distal joint involved in the action of that muscle.