Source analysis and functional connectivity
An EEG cortical source analysis was performed using exact low-resolution
electromagnetic tomography (eLORETA) software (Pascual-Marqui et al.,
2011; Vecchio et al., 2021) (publicly available athttp://www.uzh.ch/keyinst/NewLORETA/LORETA01.
htm). This is a linear source imaging method used in resting-state EEG
studies to estimate the current source densities of EEG rhythms in
different frequency bands. Regions of interest (ROIs) were defined
according to the Brodmann areas: 41 ROIs (1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
11, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 34, 35,
36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48), for each
hemisphere. A lagged linear coherence between all pairs of the 82 ROIs
was extracted by “all nearest voxels” for seven frequency bands: delta
(1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (12–30 Hz), gamma 1
(30–50 Hz), gamma 2 (50–70 Hz), and gamma 3 (70–90 Hz).