A Study of Origins of the Time Dependencies of Scalp EEG: I - Theoretical Basis

A relationship between cortical current density and resulting scalp potential is first obtained by means of arguments about volume conduction through brain, skull, and scalp. Next, a theoretical model of neural interaction at the macroscopic level of brain hierarchy is developed in order to predict cortical current density and the resulting spatial-temporal properties of scalp EEG. EEG frequencies in the 6 to 24 cycle/s range are predicted when a threshold parameter is small. When the threshold parameter approaches a critical value, there is an abrupt decrease in EEG frequency and increase in amplitude in a manner suggestive of the transition from the awake to sleeping state.