These studies indicate that measures of phase shift duration and phase lock duration between groups of neurons measured at the scalp EEG must also be capable of being measured at the level of the 3-dimensional sources of the EEG using inverse methods. The initiation of in-phase to anti-phase dynamics of neurons is modeled by long distant excitatory inputs on dendrites where phase shift duration is dependent on the density of neurons in local loops and phase lock duration is determined by the reaction to the short duration excitatory inputs producing long duration inhibitory synaptic potentials (van Drongelen et al., 2004; Ko and Ermentrout, 2007; Tiesinga and Sejnowski, 2010; Li and Zhou, 2011). These studies suggest that phase shift duration is directly proportional to the temporal compactness or density of activated synapses, because, bursting of in-phase action potentials results in an average synaptic potential shift in the frequency of neurons and consequently phase shift duration is expected to be inversely related to neural density, that is, the higher the packing density then the shorter the phase shift duration. This is like local neighbors quickly communicating whereas long distance cousins take more time and effort to synchronize (i.e., long phase shift durations).
