Behavioral influences on cortical neuronal responses to optic flow.

Optic flow selectively activates neurons in medial superior temporal (MST) cortex. We find that many MST neurons yield larger and more selective responses when the optic flow guides a subsequent eye movement. Smaller, less selective responses are seen when optic flow is preceded by a flashed precue that guides eye movements. Selectivity can decrease by a third (32%) after a flashed precue is presented at a peripheral location as a small spot specifying the target location of the eye movement. Smaller decreases in selectivity (18%) occur when the precue is presented centrally with its shape specifying the target location. Shape precues presented centrally, but not linked to specific target locations, do not appear to alter optic flow selectivity. The effects of spatial precueing can be reversed so that the precue leads to larger and more selective optic flow responses: A flashed precue presented as a distracter before behaviorally relevant optic flow is associated with larger optic flow responses and a 45% increase in selectivity. Together, these findings show that spatial precues can decrease or increase the size and selectivity of optic flow responses depending on the associated behavioral contingencies.