The estimation of a realistic localization of dipole layers within the brain based on functional (EEG, MEG) and structural (MRI) data: A preliminary note

The main aim of this note is to indicate how it may be possible to improve the methodology of equivalent dipole (ED) localization by combining EEG and MEG measurements. Furthermore, we explore also in this paper the possiblility of using this information to locate within the cortex the active brain area responsible for a given evoked potential or magnetic field. In general the problem of localizing the brain sources of activity is difficult to solve because of several kinds of errors, namely the following: (1) the inaccuracy of EEG measurements that arises from uncertainities about the electrical properties (conductivities, (an)isotropy) of the conducting media and about the type and number of elementary sources (de Munck 1989); (2) the fact that MEG measurements although rather independent of the electrical properties of the media, only give information about the tangential components of sources; (3) the complexity of the form of the brain and surrounding tissues that implies that realistic models should be preferred to those based on spherical approximations (Meijs et al.

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