registration of 8 minutes of EEG

The subjects were instrumented with 19 bridge silver and silver chloride electrodes fitted on a plastic prewired head cap and placed on the scalp according to the 10-20 system (namely: Fp1, Fp2, F3, F4, F7, F8, Fz, C3, C4, Cz, P3, P4, Pz, T3, T4, T5, T6, O1, and O2), with an electroconductive paste applied between the electrodes and the skin to guarantee optimal connection The signals were recorded with a 512 Hz sampling frequency and filtered by an offline first order zero-phase Butterworth band-pass filter, with cutoff frequencies set, respectively, at 1.6 and 70 Hz to remove frequencies outside the range of interest. After this pre-processing, the main EEG rhythms and dominant frequencies were extracted by spectral and connectivity analyses. Delta (1.6-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz), gamma1 (30-50 Hz), and gamma2 (50-70 Hz) frequency bands were considered.