EEG recordings
Continuous EEG was recorded at a 250 Hz sampling rate from 128 electrodes (HydroCel Geodesic Sensor Net) referenced online to the vertex electrode (Cz). We used a Net Amps 200 amplifier and Net Station Acquisition software version 4.2.1 (EGI, Inc.) to monitor signal acquisition. The sensor net was soaked in a potassium chloride solution prior to the recording session. Electrode impedance was assessed at or under 40 kΩ before recording. Data were online filtered with a 0.01 Hz high-pass filter and a 100 Hz low-pass filter.