Continuously recorded EEG (61 sensors, 10/20 placement) data were digitized at 1024 Hz with a passband of DC to 205 Hz using the BioSemi ActiveTwo recording system (BioSemi, Amsterdam, Netherlands). Two additional reference electrodes were placed on either earlobe. Vertical and horizontal ocular movements were monitored by two electrodes placed superior and inferior to the right eye and two electrodes placed on left and right temple, respectively.
