Neural Basis of Saccade Target Selection

This article reviews what is currently known about how the brain selects targets for saccadic eye movements. Saccade target selection is needed because primates can look at just one thing at a time. Target selection ought to be judicious because it is important to look at the right thing in a potentially dangerous and ever changing environment. Usually, conspicuous visual features attract gaze. While much is known about the low level mechanisms responsible for generating saccadic gaze shifts, very little is presently known about how the brain selects the targets for eye movements. Saccade target selection may not be that difficult a problem; there is not yet much neurophysiological data. Current data indicate that when confronted with multiple possible targets, comparisons, possibly through lateral inhibition, are made across the visual field by neurons encoding stimulus features within topographic maps. Through topographic mapping, the outcome of this visual spatial comparison ultimately activates neurons in maps of saccade direction and amplitude that generate a shift of gaze to the desired target and attenuates the activity of cells that would generate inappropriate saccades. Through investigating saccade target selection more can be learned about the roles of structures throughout the visual system as well as elucidating how processes such as attention and memory influence visual processing.