The present report has developed intracranial and surface Laplacian CSD methods as distinct, but compatible, applications of Poisson’s source equation aimed at identifying the generators of volume-conducted activity arising from the injection of current into, or removal from, the extracellular medium across the neuronal membrane. For an appropriately recorded intracranial field potential profile, these sources and sinks may be directly matched to the corresponding cyto- and fiberarchitecture of the region recorded, while for scalp-recorded EEG, the surface Laplacian identifies the resultant currents that enter and leave the skull and scalp from the subjacent dura.
