The power spectral density of the artifact-free bipolar pair EEG data was calculated using the BVA fast Fourier transform (FFT) function. The 512-point FFT was calculated for artifact-free two-second epochs with a rectangular window, DC de-trending applied to each segment of data, and 0.5 Hz overlap at the limits of the band, yielding a frequency resolution of 0.5 Hz. Power was calculated in four frequency bands, corresponding to delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (12–20 Hz), for all nearest neighbor bipolar pairs of electrodes. For the purposes of these analyses, each pair of nearest neighbor electrodes represents a node of a brain network. The 66 nodes were mapped onto a Cartesian projection of the head in a two-dimensional plane, with each node located at the geometric midpoint (indicated by blue dots) between the two individual electrodes (indicated by red dots) in Figure 1B. This mapping allowed calculation of the relative physical distance between nodes in Cartesian coordinate space relative to the origin (in this case, the location of electrode Cz).
