The supplementary motor area modulates perturbation-evoked discharges of neurones in the precentral motor cortex

Abstract

The hypothesis was tested that the supplementary motor cortex (SMA) may influence the responsiveness of area 4 neurones to kinesthetic stimuli. In the awake monkey, responses to arm displacements were recorded with and without conditioning intracortical stimulation of the SMA. In 14 of 26 tested area 4 neurones, there was an increase of the response latency and/or a decrease of the response magnitude when the peripheral stimulus was conditioned by SMA stimulation. Field potentials evoked by the displacements were reduced in 3 out of 7 recordings. These findings suggest that the SMA exerts subtle inhibitory effects on the motor cortex or its inputs.