Theory and practice of transcranial extracellular impedance control (tEIC)

As the working hypothesis in the present study, neural coupling (NC) is the sum of synaptic coupling (SC) and volume current coupling (VcC), and VcC influences cognitive and behavioral functions. VcC is a remote direct electrical coupling, or electrical crosstalk, across extracellular space between electroencephalogram (EEG) generators, which are spatiotemporally synchronously activated pyramidal neural populations. VcCs can occur everywhere in the brain along volume current (Vc) propagation paths. Transcranial extracellular impedance control (tEIC) can modulate the ongoing Vc distribution; therefore, tEIC can modulate VcCs and affect cognition and behavior that involve VcCs. Here, I•provide the mathematical formulations of VcC and tEIC effects•explain practical settings involved in tEIC.