Responses of precentral cells during cooling of post‐central cortex in conscious monkeys.

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Abstract
A cooling plate was implanted over the forelimb representation in area 2 of the post‐central region of cerebral cortex in two monkeys. Recordings were made of the discharges of thirty‐seven movement‐related neurones (thirty‐four precentral and three post‐central) in the forelimb motor representation of the cerebral cortex during active and passively imposed limb movements before, during and after cooling area 2 and local surrounding regions. Perfusion of the cooling plate with ice‐cooled water for 3‐5 min caused marked clumsiness of the conscious animal's forelimb movement and anaesthesia of the contralateral hand. Cooling of area 2 did not reduce the responses of area 4 cells to passive joint movements, nor did it alter the over‐all pattern of activity of these cells during self‐initiated lever pulling while that could still be performed. Cooling of area 2 did cause a significant increase in background cellular discharge in area 4 while the animal was at rest. Afferent impulses which are generated by passive joint movement and which have been shown to influence cells in area 4 of the conscious monkey at short latencies are probably not transmitted through cortico‐cortical connexions from area 2.