Post-movement beta synchronisation after complex prosaccade task

Flowchart of the complex prosaccade task (left-directed). The test consisted of two saccades evoked by a moving white dot projected onto a black screen (top row). The subject focused on the dot (A) which after about 12s suddenly appeared on the right side of the screen (B) evoking the first saccade. Approximately 3s later the dot turned back to the centre (C) evoking the second saccade. Saccade latency (grey stripes) is calculated as the delay of eye movement after the appearance of the white dot in a new location (EOG, electro-oculography; R, right; L, left).

Average time–frequency–power map of 15 left-directed saccade-tasks recorded at FC1 (1.row) and FC2 (2.row) electrode positions (Subject Nr6). The flowchart shows the timing of ocular movements (EOG). The 1-s reference interval for EEG data analysis started 6s before the termination of the task. The intersaccadic interval was defined as a period between the termination of first saccade and the return of the white dot to the centre of the screen. The absolute power measured at FC1 and FC2 electrodes plotted against time shows the PMBS (black thick arrows) 1250 and 1375ms after the termination of the complex saccade task. Note that PMBS does not develop after the first saccade (MRBF, most reactive beta frequency; R, right; L, left).

PMBS curves. (A) Individual power % curves of 15 saccades directed to the right plotted against time at FC2 in Subject Nr3. The arrows show the highest power % values after termination of eye movement. The thick black line represents the average of the 15 curves. (B) Average power % curves of all subjects at FC1 and FC2 electrodes in the saccade task to the left. The arrows show the highest power % values after termination of eye movement (AVR, average; Nr, subject Nr).

Average PMBS power % of 15 right-directed tests of Subject Nr6 at the most reactive beta frequency plotted against time at different electrode positions. The most pronounced PMBS can be identified at FC electrode positions.

Average power % of the reference (ref) period, average intersaccadic (intersacc) peak power % and average peak PMBS values (15–15 tasks of 6 subjects) at FC1 and FC2 electrode positions in tasks directed to the right and left. The post-saccadic beta power increase (PMBS) was significant compared to the reference period in each direction at both the FC1 and FC2 electrodes, while the power increase in the intersaccadic interval was not. There was no significant difference in PMBS according to the direction of the ocular movement and the localisation of the electrodes. Statistical results are given using the mean power % value of the reference interval and the maximum power % values of the intersaccadic and post-saccadic periods (^∗comparison to mean power % value of reference period at the same electrode position in the same direction; ^†comparison to intersaccadic power % at the same position in the same direction; ^$comparison to PMBS values at the opposite position in the same direction; ^#comparison to PMBS value at the same position in the opposite direction) (box: means±SE; whiskers: SD).