ESTIMATING REGIONAL BRAIN ACTIVITY FROM EVOKED-POTENTIAL FIELDS ON THE SCALP

Potential fields on the surface of the brain were estimated from discr etely sampled scalp fields in human subjects. Relatively simple method s of linear algebra were combined with detailed anatomical information from magnetic resonance imaging. The method was verified using a tank model of the human head that encased a fully hydrated human skull in a polymer matrix of controlled resistivity matching that of human brai n and scalp. Brain surface fields evoked by checkerboard contrast reve rsal, spread less than their scalp field counterparts, and provided in formation helpful in localizing brain activity.