Net station 4

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.

EEG was recorded for the entire duration of the two experimental sessions. Data were collected at a sampling rate of 1000 Hz using the high impedance amplifier Net Amp 300 and Net Station 4.3 (Electrical Geodesics Inc.). Impedances were kept below 50 kΩ. From the original 256 electrodes, 73 located on the cheeks and on the neck were removed and the recordings from the remaining 183 electrodes were used for analysis. During the recording, EEG signal was referenced to Cz electrode. For analysis, data were down-sampled to 250 Hz and re-referenced to the average across the 183 electrodes.

EEG was recorded for the entire duration of the experimental session, both during the task performance and in the resting state periods. Data were collected at a sampling rate of 1000 Hz using the high impedance amplifier Net Amp 300 and Net Station 4.3 (Electrical Geodesics Inc.). Impedances were kept below 50 kΩ. From the original 256 electrodes, we removed 73 channels located on the cheeks and on the neck. The remaining 183 electrodes were used for further analysis. During the recording, the EEG signal was referenced to the Cz electrode. For analysis, data were down‐sampled to 250 Hz and rereferenced to the average across the 183 electrodes.