Table 1.
Patient demographics and clinical measures.
Table 2.
MoCA and MMSE score differences between older and PD cohorts.
Fig 1.
Experimental sequence and timings of the cognitive tasks.
(A) Interleaved pro/anti-saccade task. In pro-saccade trials (left panel), the cue is green and indicates to participants to make a saccade towards the target. In the anti-saccade condition (right panel), the cue is red, and participants are asked to inhibit a saccade towards the target and to make a saccade 180° away from it instead. The cue remained on the screen for 3000 ms and target appeared for 1000 ms. For both trial types, correct saccades according to cue are illustrated by an arrow while dotted lines represent possible cue locations. There was an inter-trial interval (ITI) was of 2500 ms. (B) Decision making task. Participants had to detect the direction, either left or right, of coherently moving dots among randomly moving ones. Each trial began with participants fixating a fixation cross in the center of the screen for 700 ms. Moving dots appeared in a circular window of 10°, illustrated by dotted lines, with a coherence of 10, 20 or 30% among moving dots. The movement of the dots is indicated by arrows in the figure. Following the moving dot screen, a blank screen remained until button-press response and the next trial began. (C) Spatial visual memory task. Participants’ instructions were to determine the direction of the shift of one of the targets. Each trial began with a fixation cross for 700 ms in the center of the screen. Next, one, three of five targets appeared for 200 ms. This was followed by a blank screen for 1000 ms, after which one of the targets reappeared for 250 ms but shifted to the right or the left as illustrated by an arrow in the figure. Thereafter the screen remained blank until participant’s button-press response. The ITI lasted 1000 ms. (D) Pop-out visual search task. Participants searched for a lollipop shaped target among circles (feature-present) and were asked to report as quickly as possible whether the target was present or absent in the search array. (E) Serial visual search task. Targets and distractors were reversed, and participants searched for a circle among lollipops (feature-absent). Trials began with a square fixation window of 4.4° in the center of the screen (illustrated by dotted lines in the figure) surrounding a black fixation dot. When participants’ gaze was detected within this window, the search array appeared and remain until their button-press response. The next trial began after an inter-trial interval (ITI) of 300 ms.
Fig 2.
Performance across groups in the saccade and cognitive tasks.
Younger adults’ performance is shown in blue, older adults’ in purple and PD patients’ in red. (A) Mean error rates in percentages for pro-saccades and anti-saccades. Pro, pro-saccade trials; Anti, anti-saccade trials. (B) Mean saccade reaction times in ms for each group. (C) Decision times for correct decisions in the decision-making task. (D) Performance in the spatial visual memory task in percentage correct. (E) Search times both the pop-out and serial visual search tasks. We compared group performance in each panel with one-way ANOVAs and corrected t-tests, * = p<0.05, *** = <0.001. Bars represent standard error of the mean across subjects for each group.
Fig 3.
Heat maps of correlations among all tasks for each group.
Pearson’ correlations between the performance measures for the different tasks for younger adults in (A), older adults in (B), and PD patients in (C). Weak correlations, near 0, are in white while those nearing 1 are in red, portraying strong correlations. Pearson’s correlations are in absolute values.
Table 3.
Standard multiple linear regression of anti-saccade measures on cognitive task performance for older populations.