The lateral intraparietal area codes the location of saccade targets and not the dimension of the saccades that will be made to acquire them

Abstract

Activity in the lateral intraparietal area (LIP) represents a priority map that can be used to direct attention and guide eye movements. However, it is not known whether this activity represents the location of saccade targets or the actual eye movement made to acquire them. We recorded single neurons from rhesus macaques (Macaca mulatta) while they performed memory-guided delayed saccades to characterize the response profiles of LIP cells. We then separated the saccade target from the saccade end point by saccadic adaptation, a method that induces a change in the gain of the oculomotor system. We plotted LIP activity for all three epochs of the memory-guided delayed-response task (visual, delay period, and presaccadic responses) as a function of target location and saccade end point. We found that under saccadic adaptation the response profile for all three epochs was unchanged as a function of target location. We conclude that neurons in LIP reliably represent the locations of saccade targets, not the amplitude of the saccade required to acquire those targets. Although LIP transmits target information to the motor system, that information represents the location of the target and not the amplitude of the saccade that the monkey will make.