Continuous EEG, stimulus onset, and response codes were recorded using a 72-channel, 24-bit Biosemi ActiveTwo system (256 samples/s; DC-128 Hz). A Lycra stretch electrode cap was used for a 66-channel, expanded 10–20 scalp montage (Pivik et al., 1993), with additional channels for nose (used as offline reference) and bipolar eye activity (left and right outer canthi; above and below the right eye) to monitor lateral eye movements and blinks. Cap placement was optimized by precise measurements of electrode locations with respect to landmarks of the 10–20 system (nasion, inion, auditory meatus, vertex). The scalp placements were prepared using a conventional water soluble electrolyte gel, and the electrode-scalp interface was verified by the acquisition software (ActiView; BioSemi, 2001). During acquisition, the active recording reference was composed of sites PO1 (common mode sense) and PO2 (driven right leg).
