The resting-state human electroencephalography (EEG) represents the ongoing oscillations of spontaneous and continuous brain electrical activity, typically recorded while the participant is in a relaxed state (Niedermeyer, 1999). EEG is traditionally decomposed into the following frequency bands: delta (0–3 Hz), theta (4–7 Hz), alpha (8–12 Hz), beta (13–28 Hz), and gamma (>29 Hz), with each band reflecting different topography and brain activity (Niedermeyer, 1999). For example, alpha rhythm reflects a relaxed state and has a posterior occipital topography, while beta rhythm reflects an active brain state and is present all over the scalp but predominantly at fronto-central loci (Rangaswamy and Porjesz, 2014). Dynamic coordination of lower frequencies (theta or alpha rhythms from subcortical region) and higher frequencies (beta or gamma rhythms from cortical sites) through a mechanism of phase-amplitude coupling modulates thalamo-cortical and cortico-cortical activity (Canolty and Knight, 2010; Malekmohammadi et al., 2015). Further, coherence at the beta frequency may serve to establish transient physiological connections among neurons in the hippocampus and related brain structures (Leung, 1992a; Vecchio et al., 2016a). While local excitatory-inhibitory interactions underlying sensory, motor and perceptual
