Ipsilateral head and centring eye movements evoked from monkey premotor cortex

Recent studies in monkeys have identified a 'polysensory, defensive zone', in the ventral premotor cortex, stimulation of which results in coordinated multisegmental movements reminiscent of those normally produced by animals that react to head-directed threatening stimuli. Here, we describe gaze movements evoked in the head-fixed and head-unrestrained monkey by electrical stimulation of the polysensory zone. Centring eye movements were elicited at all sites and under both conditions. With the head free to move, ipsilateral head movements always accompanied evoked eye movements and carried gaze into a final steady-state position in ipsilateral body space. Our results support the hypothesis that stimulation of the polysensory zone generates avoidance behaviours in which gaze is moved away from a head-directed threatening stimulus.