We report several studies on the effects of removing the medial premotor cortex (supplementary motor area) in monkeys. The removal of this area alone does not cause either paralysis or akinesia. However, the animals were poor at performing a simple learned task in which they had to carry out an arbitrary action: they were taught to raise their arm in order to obtain food in a foodwell below. They were impaired whether they worked in the light or the dark. They were impaired when they had to p...