The role of anticipation and prediction in smooth pursuit in Parkinson's disease

Patients with Parkinson's disease (PD) have difficulties in self-guided (internally driven) movements. The basal ganglia provide a non-specific internal cue for the development of a preparatory activity for a given movement in the sequence of repetitive movements. Controversy surrounds the questions whether PD patients are capable of (a) anticipating their own movements before an external trigger appears (anticipation) and (b) predicting movement velocity once the moving target shortly disappears from the visual scene (prediction). In previous studies PD patients performed visually (externally) driven movements…