EEG examination and data preprocessing
Resting-state EEG data without excessive noise, muscle artifacts, or epileptiform discharges were extracted and preprocessed using EEGLAB (R13_6_5b) in MATLAB R2017b. An independent component analysis was used for further artifact removal, particularly for muscle artifacts. EEG data were resampled at 500 Hz and recomputed against the average reference. A 50 Hz notch filter was applied to attenuate the contamination from the alternating current. The bandpass filter was set to 0.1–100 Hz. The EEG data were split into non-overlapping epochs of two seconds. Each participant underwent 60–120 epochs.