Methods for the Localization of Electrical Sources in the Human Brain

Abstract

This chapter discusses the methods for the localization of electrical sources in the human brain. Although there has not been general agreement about the mechanism of evoked scalp potential generation, most investigators have proceeded from the belief that these potentials in some way directly or indirectly reflect the neuroelectric activity of the brain in the processing of sensory stimuli. As such, numerous authors have attempted to interpret evoked scalp potentials in terms of their neuroelectric sources in the brain. In strictly mathematical terms, this problem has long been known to be ill-posed and thus to possess no unique solution. Even with complete knowledge of the electrical and geometrical characteristics of the head itself, it is impossible to convert surface potential information alone into information concerning the actual distribution of sources in the brain. In spite of the limitations imposed by theoretical non-uniqueness, it is possible that useful information about the origin of evoked scalp potentials may be obtained by the solution of a less general problem that restricts the form of neural activity which might lead to scalp potentials.