PMC10014735_01
(A-D) Horizontal AC-electrooculogram (EOG) recordings. In each figure, the upper graph shows semi-eye position (time constant 3 s) and the lower graph shows eye speed (time constant 0.03 s). In each graph, the upper direction indicates rightward eye movement, and the lower direction indicates leftward. Chart speed is 5 mm/s in (A, C, D), and 25 mm/s in (B). (A, D) were continuously recorded. (A) Square wave jerks (SWJs) occurred in the following three conditions: first, in the daylight under the target-on state; second, under the target-off (arrow) state; and finally, light-off (arrow) in the dark. The amplitudes of SWJs were 4-5 deg under target-on, 5-6 deg under target-off, and 6-8 deg in the dark. The frequency of SWJs also gradually increased as follows: 1 Hz under target-on state, 1.5 Hz under target-off state, and 2 Hz in the dark. Ocular microflutters occurred among SWJs (arrowheads). (B) SWJs and ocular microflutter (arrowheads) occurred in the daylight under target-on state [recorded at 25 mm/s, i.e., as five times as in (A)]. (C) Macro SWJs (amplitude 5 deg) and a single or several saccadic ping-pong gaze (SPPG, arrowheads in the upper graph, amplitude 20-40 deg) occurred alternately in the dark with eyes open. (D) In the dark, macro SWJs (5-10 deg) occurred in a series with eyes open, and then with eyes closed, SPPG with high amplitude (70 deg) occurred continuously and macro SWJs disappeared. With eyes open again, macro SWJs reappeared continuously and SPPG disappeared.
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SWJs (around 5 deg in amplitude) occurred frequently (40-60/min) during fixation (Figures 1A, B, refer to Supplementary Video 1 by infrared CCD camera). SWJs are defined as "pairs of small horizontal saccades (typically <2 deg) that take the eye away from the primary position and then return it after 200-300 ms," and macro SWJs are defined as "large (>4 deg) SWJs." Along with SWJs, sometimes ocular microflutter of small amplitude (<2 deg) appeared with a saccade frequency of 8-10 Hz. This microflutter consisted of 5-10 back-to-back saccades with no intersaccadic interval (arrowheads in Figures 1A, B). SWJs occurred more frequently and largely under target-off state than under target-on (Figure 1A). In the dark, macro SWJs (5-10 deg) often occurred in a series (Figures 1A, C, D). In addition, with eyes open in the dark, there appeared either a single or several horizontal "saccadic ping-pong gaze" (SPPG) events with amplitude of 20-40 deg alternately with macro SWJs (arrowheads in Figure 1C, refer to Supplementary Video 2 by infrared CCD camera). SPPG with high amplitude (30-70 deg) appeared continuously and SWJs disappeared (Figure 1D). SPPG consisted of the following two components: (1) horizontal irregular pendular oscillations of the eyes (ping-pong gaze, PPG). MRI images (MR Parkinsonism Index 19.3) (Supplementary Figure 1). Mild striatal dopamine deficiency was found on dopamine transporter imaging (SBR Ave. 4.75, Z-score -2.60, Supplementary Figure 2).
(A, B) Horizontal AC-EOG recordings. In each figure, the upper graph shows semi-eye position (time constant 3 s) and the lower graph shows eye speed (time constant 0.03 s). In each graph, the upper direction indicates rightward eye movement, and the lower direction indicates leftward. The chart speed is 5 mm/s. This figure was recorded one and a half years after Figure 1. (A) In the daylight, macro SWJs (5 deg) occurred under the target-on state from the start, and then under the target-off state, a single or several SPPGs with small amplitude (15-20 deg) occurred (dashed lines, 15 deg) alternately with macro SWJs. Subsequently, the light was turned off [(A) continues to (B)]. (B) In the dark, macro SWJs soon disappeared. Alternatively, SPPG appeared continuously and got larger (to 50 deg) than in the daylight. And then, with eyes closed, giant SPPG emerged with an amplitude of 70 deg, reaching the full range.
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In addition, with eyes open in the dark, there appeared either a single or several horizontal "saccadic ping-pong gaze" (SPPG) events with amplitude of 20-40 deg alternately with macro SWJs (arrowheads in Figure 1C, refer to Supplementary Video 2 by infrared CCD camera). Even in the daylight, a single or several SPPG with small amplitude (15-20 deg) appeared under the target-off state (Figure 2A). In the dark with eyes open, SPPG at a period of 2-3 s emerged immediately and got larger, and then with eye closure, giant SPPG emerged with amplitude to 70 deg reaching the full range (Figure 2B, refer to Supplementary Video 2). MRI images (MR Parkinsonism Index 19.3) (Supplementary Figure 1). Mild striatal dopamine deficiency was found on dopamine transporter imaging (SBR Ave. 4.75, Z-score -2.60, Supplementary Figure 2).