A 19‐channel Nicolet system (Cephalon, Denmark) was used for the EEG recording. EEG data were collected at a sampling rate of 512 Hz, with analog bandpass filtering between 0.1 and 100 Hz. Nineteen Ag/AgCl electrodes were placed according to the international 10‐20 system. Reference electrodes were placed on A1 and A2, and the ground electrode was attached to the forehead. The impedance of each electrode was maintained at below 10 kΩ. The eyes‐closed resting‐state EEG was recorded for 10 min in a shielded and sound‐attenuated room in the morning. Participants were instructed to relax without thinking about anything during the EEG recording but without falling asleep.
