Adaptive biasing of action-selective build-up activity in M1.
A. Time course of action-selective beta power (12-36 Hz) lateralization in the M1 hand area, contralateral vs. ipsilateral to upcoming button press, collapsed across trials (black line). Red line, bilinear fit. Gray box, time window (0.58 s to 0.8475 s from evidence onset) used to quantify the (rate of) build-up of power lateralization in panels B-E (vertical dashed lines in B and D). The window was defined to start 250 ms after the intersection point of bilinear fit and end 50 ms before the minimum of power lateralization, chosen so as to cover the interval containing ramping activity in the majority of trials. B. Same as A, but now split by sensory environment (Repetitive vs. Alternating) and by consistency of the upcoming behavioral choice with the stimulus category from previous trial. Dark colors, choice on current trial = stimulus category on previous trial; bright colors, choice on current trial = − stimulus category on previous trial. C. Difference in slopes between consistent and inconsistent conditions from B in time window of interest (see A), separately for Repetitive and Alternating environments. D. Component of action-selective lateralization governed by single-trial bias, irrespective of upcoming behavioral choice and pooled across sensory environments (see main text for details). E. Slope estimates for neural bias measures from panel D. Left, time window from panel A. Right, early time window derived from single-trial regression in panel F. F. Time-variant impact of single-trial history bias on amplitude (black) and slope (gray) of M1 beta lateralization (relative to up-coding hand). G. Same as F but for impact of signed stimulus strength. Shaded areas, SEM. Bars, p < 0.05 (two-tailed cluster-based permutation test) across participants. * p < 0.05 (one-tailed paired permutation test).