The responses of pericruciate cortical neurones to distal forepaw electrical stimulation in the unanaesthetized, unrestrained cat.

Experiments were performed to examine the responses of cortical neurons in the pericruciate cortex to cutaneous afferent input from the distal forepaw. Ninety-nine cortical neurons responding to electrical stimulation of the forepaw were recorded from four cats. Their response latencies ranged from 6 to 23 ms. The units had cutaneous receptive fields which ranged in size from those restricted to one digit to those extending over the whole forelimb. They were recorded from area 4 and area 3. Intracortical microstimulation at the recording sites activated either the distal or proximal musculature of the forelimb. When the characteristics obtained from each recording site were examined as a group of features, a uniform population emerged which was significantly different from the rest of the sample. These units had the shortest latency responses to distal forepaw electrical stimulation, the shortest duration of evoked discharge, the smallest distal cutaneous receptive fields. Such units were recorded at the border between areas 3 and 4, at sites which on microstimulation resulted in movements of the distal forepaw musculature.