EEG/MEG source reconstruction: new forward modeling and validation approaches

Haueisen, J.
Institute of Biomedical Engineering and Informatics, Technical University Ilmenau; Biomagnetic Center, Friedrich Schiller University Jena

In order to reconstruct the neuronal activity underlying measured EEG and MEG data both the forward problem (computing the electromagnetic field due to given sources) and the inverse problem (finding the best fitting sources to explain given data) have to be solved. The forward problem involves a model with the conductivities of the head, which can be as simple as a homogeneously conducting sphere or as complex as a finite element model consisting of millions of elements. The question is addressed how complex the employed forward model should be, and, more specifically, the influence of anisotropic volume conduction is evaluated. Since EEG/MEG source reconstruction is computationally complex and no unique solution exists, validation should be included for any new approach in data analysis. Consequently, new validation approaches are presented aiming at the comparison and the estimation of the procedural limits of the source localization accuracy under real world conditions.