The functional significance of certain duplicate motor patterns on the cerebral cortex in primates including man.

Rotation elicitable from direct irritation or implantation of the cortical irritant, penicillin, in both rostral and posterior parts of the temporal operculum and on the island cortex in the monkey (Macaca mulatta) has been described and illustrated in photographs. The pathways to and from these temporal and island areas have been considered and the results obtained have been compared with related reports in the literature on rotation in monkeys and man. The probable role of the precentral and postcentral insular areas and their related paths to the contraction of the muscles (sometimes called the agonists) on the side of an extremity in the direction of movement of that extremity and the commensurate relaxation of the muscles (sometimes called the antagonists) cooperating with them on the other side of the extremity is discussed.