Peripheral afferent inputs to the forelimb area of the monkey motor cortex: input-output relations.

Abstract

1. Peripheral inputs to cortical efferent zones projecting to distal forelimb muscles were examined in Cebus monkey by using one microelectrode both for low intensity intracortical stimulation and for recording cellular discharges. 2. Efferent zones within the motor cortex received afferent inputs from skin, joint and muscle receptors. 3. A given efferent zone received afferent inputs from receptors in muscles as well as joints involved in the movement produced by microstimulation within that zone. 4. Cells activated by tactile stimuli had receptive fields almost exclusively on the glabrous volar surface of the hand and lay within cortical efferent zones projecting to finger flexor muscles. 5. The region of low threshold efferent zones which projected to distal forelimb muscles was found to coincide with a region receiving short latency afferent input from group II cutaneous and deep afferents. Group I muscle afferents projected to an adjacent area of the cortex. 6. The organization of motor cortex in cat and monkey was compared with particular reference to input-output relations.