Control of saccades in Parkinson's disease.

Parkinson's patients (PD) made pro- and antisaccades: In the no-delay condition, the target appeared concurrent with the GO signal. In the delay condition, the target appeared before the signal for movement. Second, we probed spatial working memory in PD. Subjects looked to the remembered locations of sequential targets. In the no-delay prosaccade condition, PD had faster reaction times, made more express saccades, and exhibited hypometria. In the no-delay antisaccade condition, PD had longer reaction times and made more direction errors. In the delay tasks, PD made more direction errors and had more difficulty withholding a movement. PD made more sequencing errors in the spatial working memory task. These findings are consistent with a basal ganglia pathophysiology influencing eye movement processing in the frontal cortex.