Figure 6 |. Coordination rates are unrelated to eye movements.

(a) Average traces of eye position relative to the fixation point, averaged across correct (n=75) and incorrect (n=25) trials in a sample session. The black bars represent the intervals when target and test stimuli are presented. (b) Trial distributions of eye velocity for correct (n=633) and incorrect (n=315) trials are not statistically different (p=0.54, 2-sided Wilcoxon Rank-sum test). (c) Single trial trace of eye velocity (left y-axis) and number of coordinated events (right y-axis) for a sample trial as a function of time since test onset (the time bin is 5 ms). (d) Distribution of Pearson’s correlation coefficients of eye velocity and coordination rates, regardless of order, across trials (n=948) for all sessions (p=0.3, 2-sided t-test). Only one trial in V1 and one trial in V4 showed significant (p<0.05) correlation coefficients. This analysis was performed by computing the cross-correlogram between the number of coordinated events and eye velocity (the two traces in panel c), averaged over trials across sessions (in V1 and V4). The cross-correlograms were corrected for the slow co-fluctuations of the two variables by using a 50-ms smoothing kernel and subtracting the cross-correlation of smoothed traces from the original one. Each cross-correlation was z-scored before averaging. (e) Trial by trial correlation of eye velocity and V1–V4 coordination, including 2^nd order and higher order events (calculated for the time lag of the peak V1–V4 coordination, as reported in the manuscript). Trials are pooled from 3 representative sessions (n=300). Both eye velocity and coordination rates were z-scored before calculating the Pearson’s correlation coefficient (r=0.06, p=0.3, 2-sided t-test). (f) Median p-values for the eye position and eye movement control analyses and their correlation with coordination rates, averaged across sessions (V1: n=22, V4: n=12; results reported for the 300-ms test stimulus presentation) – pos-perf: difference between eye position in correct and incorrect trials (p-value for 2-sided Wilcoxon Rank-sum test); vel-perf: difference between eye velocity in correct and incorrect trials (p-value for 2-sided Wilcoxon Rank-sum test); pos-SO coord: Pearson’s correlation between eye position and 2^nd order (SO) coordination rates (separately for V1 and V4); pos-HO coord: Pearson’s correlation between eye position and higher order (HO) coordination rates (separately for V1 and V4); vel-SO coord: Pearson’s correlation between eye velocity and 2^nd order (SO) coordination rates (separately for V1 and V4); vel-HO coord: Pearson’s correlation between eye velocity and higher order (HO) coordination rates (separately for V1 and V4). For all Pearson correlations, the p-value for the 2-sided t-test was used. For each box plot, the middle bar shows the median, the box shows the 25^th higher and lower percentiles, and the whiskers show the range of the data points.