Stimulus versus eye movements: comparison of neural activity in the striate and prelunate visual cortex (A17 and A19) of trained rhesus monkey.

Visual responses were recorded from single cells in the parafoveal striate (A17) and prelunate (A19) cortex of awake rhesus monkeys while they were fixating a stationary or moving spot of light in the presence of a moving or stationary stimulus. Retinotopy and stimulus requirements were found to be less strict in A19 as compared to A17. Striate cells preferred slow stimulus movements and displayed a large amount of binocular interaction. Many prelunate cells responded well to fast stimulus movements, all were binocular but only a few showed binocular interaction. In both areas an overall deficit of visual responses during saccadic eye movements was observed which was mostly due to the cells' inability to respond to stimuli moving at saccadic velocities. Only in A19 were there cells which seemed to receive non-sensory signals reducing visual responses during rapid eye movements. We concluded that the prelunate cortex has access to input which does not use the geniculate-striate pathway. The additional observation of presaccadic activation of some cells supports the idea that activity in the prelunate cortex may be associated with events related to visually guided changes of the direction of gaze and/or attention.