The subjects were seated in a comfortable, reclining chair located in a dimly lit sound-attenuated RF-shielded room (IAC, Industrial Acoustics, The Bronx, NY). EEG activity was recorded on Neuroscan systems (Versions 4.1, 4.2, and 4.3; (Neurosoft, Inc., El Paso, TX)) using a 61-channel electrode cap (Electro-cap International, Inc., Eaton, OH), which included 19 channels of the 10–20 International System and 42 additional electrode sites (Electrode Position Nomenclature, Society, 1991; Figure 2). The electrodes were nose-referenced and subjects were grounded using an electrode placed on the forehead (frontal midline, 2 cm above the nasion). Eye movements were monitored with two electrodes placed on supraorbital regions of the left eye for vertical and two electrodes placed on external canthi of both eyes for horizontal movements. Electrode impedance was maintained below 5 kΩ throughout the recording. The continuous EEG signals were recorded at sampling rates of 256, 500, and 512 Hz depending on the amplifier version, with a band pass filter set at .02 to 100 Hz and were amplified 10,000 times using a set of amplifiers (SynAmps2, Neuroscan, TX).
