Neural trajectories do not follow the tapping kinematics.

A. Diagram of the rotational trajectory of the SCT neural activity during three inter-tap intervals: one 450-ms interval (green) and two 1,000-ms intervals (red). Each tap is numbered and projected in the trajectory as a white circle. A blue triangle marks the beginning, whereas a yellow triangle marks the end of the movement time. The monkeys produced phasic stereotypic movements whilst timing the dwell between taps during SCT [37]. B. Euclidean distance (dt, see inset) between an anchor point (red) and the position of each tap (green, mean ± SD, slope = 0.00007, R2 = 0.0633, p = 0.225), or half of the inter-tap interval position on the neural trajectories (blue, mean ± SD, slope = −0.001, R2 = 0.801, p p p p p C. Speed of the tapping movement (orange trace) from the second to the sixth tap of ST, and the PC1 projected neural information (cyan) for 26 simultaneously recorded neurons during a trial with a target interval of 550 ms. Taps were represented as yellow squares and stimuli as red circles. Movement and dwell times are depicted in green and magenta, respectively. D. Similar to (C) during an 850-ms target interval (PC1 projected neural information as a yellow trace). E. Mean ± SD of the duration of the movement (green) and the dwell between movements (magenta) across target intervals, computed from the speed profile of the tapping movements. A two-way ANOVA showed significant main effects on kinematic state (movement/dwell duration, F(1, 228) = 1,850.61, p p p p F. Mean ± SD of the peak speed during the tapping movement as a function of the target interval during ST (ANOVA main effect interval, F(5, 114) = 5.13, p p https://doid.gin.g-node.org/d315b3db0cee15869b3d9ed164f88cfa/. a.u., arbitrary unit; dh, Euclidean distance of the anchor point to the half inter-tap position; dt, Euclidean distance from the anchor point to the tap position; HSD, honestly significant difference; PC, principal component; SCT, synchronization-continuation task; ST, synchronization task.