EEG signals in the eye-closed resting state were continuously recorded for approximately 120 s using a Neuroscan SYNAMPS recording system (Neuroscan Inc., El Paso, TX) from 29 Ag/AgCl electrodes (Falk-Minow Services, Munich, Germany) with a nose reference based on the International 10–20 system (29 channels = Fp1, Fp2, AFz, Fz, F4, F8, F3, F7, FCz, FC4, FT8, FC3, FT7, Cz, C4, T8, C3, P7, CPz, CP4, CP3, Pz, P4, P8, P3, P7, Oz, O2, and O1). In addition, the vertical and horizontal electro-oculograms (EOGs) were recorded to monitor the eye movements and blinks. Sampling frequency was 1000-Hz with a bandpass of 0.1–200-Hz, and the electrode impedances were less than 10 kΩ. Participants were instructed to keep their eyes closed while resting EEG was recorded for 120-sec. Ocular artifacts recorded by vertical and horizontal EOGs were corrected in the acquired EEG data by the method of Gratton et al. (1983). The EEG was segmented into 2-sec epochs and the epochs with voltage exceeding ± 150 μV were excluded to reduce artifacts. Frequency bands of interest were classified by delta (1–4 Hz),
