Ges 300 amplifier

As the EEG cap could be fitted very rapidly (about 15 min), there was only a very short interval between the learning phase and the TNT task. EEG activity was continuously recorded by a GES 300 amplifier (Electrical Geodesics, Inc.), using a HydroCel Geodesic Sensor Net (HGSN-128; Electrical Geodesics, Inc., Eugene, OR, United States) with a dense array of 128 Ag/AgCl sensors^{73 (link)}. Impedances were kept under 100 k $\mathrm{\Omega }$ ^{74 (link)}, and the EEG channel was referenced to a vertex reference Cz, and the ground to CPPZ (fixed by the EGI system). The signal was sampled at a 20-kHz frequency with a 24-bit A/D and was online (hardware) amplified and low-pass filtered at 4 kHz. The signal was then filtered by a Butterworth low-pass finite impulse response (FIR) filter at 500 Hz and subsampled at 1 kHz. Electro-oculograms were recorded using four electrodes placed vertically and horizontally around the eyes. EEG data were processed offline using Netstation 4.4.2 (Electrical Geodesics Inc., Eugene, OR, USA). The signal was filtered using a 1-Hz Kaiser FIR first-order high-pass filter (which ensures a linear phase and no distortion in the bandwidth), in order to discard DC and very slow waves.

EEG activity was continuously recorded by a GES 300 amplifier (Electrical Geodesics, Inc. Eugene, OR, USA) using an EGI Hydrocel Geodesic Sensor Net (HGSN-128) with a dense array of 128 Ag/AgCl sensors. Impedances were kept under 100 kΩ, and EEG channels were referenced to a vertex reference Cz and ground to CPPZ (fixed by the EGI system). The signal was sampled at 20 kHz frequency with a 24-bit A/D and was online (hardware) amplified and low-pass filtered at 4 kHz. The signal was filtered by a Butterworth low-pass finite impulse response (FIR) filter at 500 Hz and subsampled at 1 kHz. An electro-oculogram was performed using four electrodes placed vertically and horizontally around the eyes. EEG data were processed offline using Netstation 4.4.2 (Electrical Geodesics Inc., Eugene, OR, USA). The signal was filtered using a 1 Hz Kaiser FIR first-order high-pass filter (which ensures a linear phase and no distortion in the bandwidth) to discard DC and very slow waves.