Mathematical dipoles are adequate to describe realistic generators of human brain activity

It is investigated whether a mathematical dipole description is adequate for the localization of brain activity on the basis of visually evoked potentials (VEPs). Extended sources (dipole disks and dipole annuli) are stimulated and fitted with a mathematical dipole. It is found that the deviation between the positions of the disks and annuli and the equivalent dipole is very small. Also, the differences in the direction and amplitude may be neglected. The position of the extended source with respect to the electrode grid does not much influence these conclusions.