ABSTRACT

The primary somatosensory cortex (SI), comprising cytoarchitectonie areas 3a, 3b, 1 and 2 of the cerebral cortex, plays a critical role in primates in the processing of somatosensory information generated by passive stimulation of peripheral tissues or elicited by active movements. The thermode provided an experimental means by which the effects of reversible cold block-induced inactivation of SI could be tested on orofacial motor behaviour and on motor cortex neuronal activity in the awake monkey. During bilateral cooling of face SI in two monkeys tested, there was a statistically significant reduction in the success rates for the performance of the tongue protrusion task in comparison with the control series of trials. Other properties of the face SI neurones indicated the involvement of face SI also in motor control. The original neuronal data indicate an important role for face SI in operantly conditioned orofacial movements.