Scalp EEG was recorded from 13 lateral, homologous pairs of electrode sites (FP1/2, F3/4, F7/8, FC5/6, FT9/10, C3/4, T7/8, CP5/6, TP9/10, P3/4, P7/8, P9/10, O1/2) and from four midline electrode sites (Fz, Cz, Pz, and Oz) using extended 10–20-system placements with an electrode cap (Electro Cap International, Inc.) and a nose reference. Electrodes at supra- and infra-orbital sites surrounding the right eye recorded blinks and vertical eye movements (bipolar), while electrodes at right and left outer canthi recorded horizontal eye movements (bipolar). All electrodes were tin, with impedances below 5 kΩ. EEG was recorded using a Grass Neurodata system at a gain of 10 k (5 k and 2.5 k for horizontal and vertical eye channels, respectively), with a bandpass of 0.1–30 Hz using a NeuroScan recording system (200 samples/s). Recordings were screened for electrolyte bridges between electrodes (Tenke and Kayser, 2001) and activity at bridged electrodes was replaced by spherical spline interpolation from unaffected sites. Only one control subject showed bridging at any of the sites reported here (only O1 to Oz), and exclusion of this subject's data did
