invisible to the scalp recorded EEG. The present study is a further exploration of the scalp surface EEG studies of phase shift and phase lock duration by applying 4-dimensional neuroimaging (tEEG) of current sources using Low Resolution Electromagnetic Tomography (LORETA) using the time series of the center voxel of each of 88 Brodmann areas that comprise the DMN (Pascual-Marqui et al., 1994; Pascual-Marqui, 1999; Lehmann et al., 2006; Canuet et al., 2011; Langer et al., 2011). The present study is designed to explore the nature of sudden phase shifts followed by phase lock in small 3-dimensional volumes of EEG current density located in the center of Brodmann areas that constitute the DMN (Buckner et al., 2008). Because of the large number of possible network combinations and frequencies, we limited this study to the delta frequency band (1–4 Hz) and the DMN. Analyses of different frequency bands and locations show similar basic time domain measures with evidence of spatial-frequency “preferences.” These analyses will be published in the future.
