EEG localization accuracy improvements using realistically shaped head models.

A model of the head must be used in making estimates of the locations of electrical sources in the brain using electroencephalograms (EEG's) measured on the scalp. In part, the accuracy of these estimates is dependent on how accurately the model represents the actual head. In most work performed to date, spherical models of the head have been used. This paper presents results in which the estimates of source location are made in realistically shaped head models. Techniques for accurately and conveniently developing realistically shaped head models from CT's, MRI's, X rays, and/or physical measurements are also presented. Realistically shaped head models are developed for three subjects with electrical sources implanted at known locations in the brain. Localization accuracy is found to be significantly better in the realistically shaped head models than in spherical models if EEG's with good signal-to-noise ratio are used.