Preservation of Eye Movements in Parkinson's Disease Is Stimulus- and Task-Specific

Flowchart of participant inclusion by participant group, task, and medication status.

Sequence of events and eye movements in the pro-saccade task. A, Each trial started with a drift correction followed by a fixation period. Participants had to saccade to the cued target square. B, 2D eye position in pro-saccade task for a representative PD patient (purple) and control participant (green). For illustration purposes, eye and target position data were flipped to always depict the saccade target on the right. C, Main sequence (saccade velocity vs amplitude) for 2 representative patients (purple circles) and 2 control participants (green circles). Each circle represents one trial. D, Saccade latency distributions (relative frequency of binned saccade latencies) for patients and controls. E, Mean saccade amplitude as a function of saccade latency. Each dot represents the mean saccade amplitude in a 50 ms time bin across all patients (purple) and controls (green). Vertical lines indicate SE. **p < 0.01; ***p < 0.001; ranked sum test.

Sequence of events and eye movements in the anti-saccade task. A, Each trial started with a drift correction followed by a fixation period. Participants had to saccade to the uncued target square. B, 2D eye position in pro-saccade task for a representative PD patient (purple) and control participant (green). For illustration purposes, eye and target position data were flipped to always depict the saccade target on the right. C, Saccade latency distributions (relative frequency of binned saccade latencies) for patients and controls. Blue bins represent changes of mind. Red bins represent direction errors. D, Task performance (percentage of saccades toward uncued location without any corrections) as a function of saccade latency. ***p < 0.001 (ranked sum test).

Comparison of pro- and anti-saccade task performance. A, Relationship between the frequency of express saccades during the pro-saccade task and the error rate (saccade toward the cued target) in the anti-saccade task. Each circle represents a patient (purple) and control participant (green). Significant regression results in patient group: ***p < 0.001. B, Saccade distributions of a control participant (C57; green) and patient (P35; purple) who had a similar rate of express saccades.

Sequence of events and eye movements in sinusoidal pursuit task. A, Each trial started with a drift correction followed by five cycles of sinusoidal target motion in either horizontal or vertical direction. B, 2D eye position for a horizontally moving target at a speed of 16 deg/s for a representative PD patient (purple) and control participant (green). Saturated segments represent saccades. Lighter segments represent smooth pursuit.

Sequence of events and eye movements in go/no-go track-intercept task. A, Each trial started with a fixation period. Participants viewed a moving, disappearing target and had to judge whether the target would miss or pass a strike box. B, 2D eye position in track-intercept task for a representative PD patient (purple) and control participant (green). C, First catch-up saccade latency distributions (relative frequency of binned saccade latencies) for patients and controls. Red bins indicate trials in which the go/no-go decision was incorrect. D, Go/no-go decision accuracy as a function of initial catch-up saccade latency for patients (purple) and controls (green). Circles represent group mean for given saccade interval. **p < 0.01 (ranked sum test).