The measured electrical activity on the brain scalp is thought to be primarily generated from common dipole sources within brain. However, source characteristics for EEG activity cannot be identified solely on the basis of scalp recordings. To estimate the orientation and strength of the electrical dipole sources has been known as an ill-posed problem, i.e., there are a number of possible solutions which can explain the measured electrophysiological data. In this study, SL differences from resting EEG data were found in the subnetwork consisting of fronto-centro-parietal scalp regions (Fig. 4). Deeper sulcal sources in right central and precentral sulcal activity of this study could induce a broadly detectable signal despite being a relatively singular generator. So the hypothetical activities might be interpreted as two distinct synchronized cortical nodes rather than one strong deep oscillator. Nunez and colleagues have suggested utilization of surface Laplacian analysis (Nunez et al., 1997, 1999) to investigate radially oriented sources of neural activity in our EEG data and to find the superficial radial dipoles near the brain surface. However, this approach, and other source analysis approaches,
