Abstract
Both saccade reaction times and orienting choices are sensitive to the value of rewards associated with visual targets. Similarly, increasing the reward value of orienting to a visual target enhances neuronal responses in several visual-oculomotor brain areas. One question these observations raise is to what extent reward modulation of neuronal activity in such areas reflects nonspecific changes in motivation or arousal rather than the relative value of a particular target or eye movement. Here we show that increasing the size of fluid rewards in blocks reduced saccade reaction times and improved visual detection performance in monkeys performing a peripherally-cued saccade task, suggesting enhanced motivation. Area LIP neurons responded to visual cues spatially segregated from the saccade target, and these responses were enhanced by increasing reward. Moreover, neuronal responses closely tracked local changes in reinforcement rate associated with task performance rather than the specific value of each cue. These data demonstrate that dynamic changes in motivational state contribute to neuronal activity in LIP.