The EEG recordings were low-pass filtered at 100 Hz and collected
continuously at 516 Hz by an Active-two Biosemi system at seventytwo
recording sites: sixty-six channels in an electrode-cap under the
10/20 system-extended and three pairs of additional electrodes. Two
pairs of electrodes, situated on the outer canthi and infra-orbital ridges,
monitored horizontal and vertical eye movements; one recording pair
was situated over the mastoids. A Common Mode Sense (CMS) activeelectrode
and a Driven Right Leg (DRL) passive-electrode acted as a
ground during recording. The electrodes were average-referenced
offline.