Fig. 3: Evolution of power modulation over the 5 training days and relation with BCI-performance dynamics.

a Topographies, one for each frequency band of interest, display the changes in EEG power across the 5 days of training. All frequency bands show a global linear power increase (positive t values). Electrodes showing significant linear trends are highlighted with black dots (permutation test, cluster corrected, p < 0.05, n = 15). b Power (averaged over participants) for each day, plotted for each significant channel, shows a clear increase over the 5 training days. c Topographies display the statistical result of the interaction term between EEG power and the effect of training (modeled with a planned contrast) on BCI-performance. Several statistically significant clusters display positive t-values, indicating that EEG power in specific regions and frequency bands became stronger with training. Among these, the most prominent were found over frontal and central regions in the theta band and the left temporal area in the low-gamma band. Significant electrodes are highlighted with black dots (permutation test, cluster corrected, p < 0.05, n = 15).