Figure 1.

Schematic of task design. 1) Black screen for duration of 1.0 to 1.1 seconds (s) during which patient is resting. 2) Fixation cross for duration of 1.0 to 1.1s indicates that cue to move is impending. 3) Onset of action selection cue indicates patient should move joystick. In the internally cued (IC) condition bidirectional arrows are displayed indicating that patient may move joystick left or right. In the externally cued condition (EC) uniform right or left pointing arrows are displayed, instructing action selection. Cue is displayed for 1.5s or until response is recorded. 4) Response is recorded for additional 0.5s during display of black screen. In total, response is recorded for 2s following action selection cue display. After the completion of a trial, a new trial begins.