Digital 19-channel scalp EEG (Neuroscan Medical Systems, Neurosoft Inc. Sterling, VA, USA) was recorded during awake-resting condition, with the electrodes fixed in an elastic cap (ECI-Electro cap, Eaton, Ohio, USA), and positioned according to the International 10–20 system (i.e., Fp1, Fp2, F7, F3, Fz, F4, F8, T7, C3, Cz, C4, T8, P7, P3, Pz, P4, P8, O1, O2). The EEG activity was acquired using a linked ears reference, sampled at 250 Hz, and filtered offline between 1 and 30 Hz. Electrode impedance was kept below 5 kΩ. Vigilance-controlled EEG recordings lasted about 5 to 6 minutes, including eyes closed and eyes open states, as well as photic stimulation in all subjects. Analyses were circumscribed to the 3 min of awake, eyes-closed condition. For each subject, 40 s of artifact-free EEG data, fragmented into epochs of 2 s, were randomly selected. Artifact rejection was performed manually based on visual inspection by an experimenter blind to the participants' condition and genetic data. Segments containing blinking artifacts, muscle or cardiac contamination, or drowsiness signs were carefully excluded, so that reliable estimates of brain
