Neural mechanisms of bottom-up selection during visual search

Models of attention and saccade target selection propose that within the brain there is a topographic map of visual salience that selects, through a winner-take-all mechanism, locations for further processing. The results of a series of recent experiments in monkeys performing pop-out visual search tasks suggest that the frontal eye field (FEF) functions as a map of visual salience. FEF is located at the interface of sensory and motor processing and participates in the transformation of visual information into a command to move the eyes. Visually responsive neurons in FEF identify conspicuous objects in a search array regardless of the feature that renders conspicuousness. Furthermore, selection occurs at a constant interval following search array presentation and is dissociated from saccade production. The finding of a visual salience map in FEF validates models of visual selection and can serve to guide future empirical and theoretical investigations.