Figure 1.

Experimental and data processing flow. The left column shows the experimental steps performed on each subject. First, 20‐s epochs were recorded during rest and the performance of the motor task. Afterwards, the stimulation electrodes were placed over the scalp—under the EEG cap—and tDCS was applied for 10 min. Immediately after the stimulation, the electrodes were removed and again 20‐s epochs were recorded during rest and the performance of the same motor task (strictly in the same order for all the subjects either for the real and sham tDCS sessions). The recorded epochs were processed offline. First, the epochs were band pass filtered, then the SL was calculated and subsequently a SL matrix was built. Finally, the SL matrices were thresholded and then undirected graphs were built.