The biophysical foundations of the localisation of encephalogram generators in the brain. The application of a distribution-type model to the localisation of epileptic foci

The brain electrical activity measured as the EEG signal is a powerful tool for the understanding of normal and pathological brain function. The EEG presents a high temporal resolution but a low spatial resolution. The latter can be improved solving the so-called inverse problem, if some a priori physiological and anatomical information is included. The present review presents the biophysical bases that allows brain source localization in realistic head models, as well as the two basic source models used: dipolar models and distributed source models. Finally, an example of practical application for the localization of epileptic focus using the distributed solution EPIFOCUS will be presented.