Figure 1. Task description and movement traces.

Patients were asked to perform cued forearm pronation movements of three different sizes (A) after presentation of a baseline fixation cross that resulted in hand movements of three different amplitudes (B; small - yellow, medium - red, large - green) and movement velocities (C) aligned on movement onset. Shaded areas indicate the standard error of the mean. Black lines below the movement velocities indicate statistical significance (p<0.05, FDR corrected). Movement velocity shows a stepwise increase toward the large movement condition in the ON- and OFF- medication state (D). Patients in the dopaminergic OFF state (n = 7, sides averaged for each patient) performed the task significantly slower only in the large movement condition (E).