Dealing with white matter anisotropy in the Boundary Element Method

Incorporating white matter anisotropy into the MEG/EEG forward problem is usually done via Finite Element Modeling. Indeed, the FEM can handle a different anisotropic conductivity tensor per voxel, contrarily to Boundary Element Methods, which consider homogeneous conductivity within each compartment (corresponding to various tissues). Laura Serron’s internship (1st year Master’s degree) studied the opportunity of incorporating local anisotropy (along fibers) to Boundary Element Models. This study builds upon ideas exposed in Emmanuel Olivi’s PhD thesis (Université Nice Sophia Antipolis, 2011). We express the presence of the fiber as a perturbation to a homogeneous conductivity. The goal is then to compute the effect of this perturbation on the fields (electric potential for EEG, magnetic potential for MEG). In Laura Serron’s internship, we studied near-field and far-field approximations which are classically used in Inverse Problems of inclusion identification.

Méthode de perturbations en E.D.P. pour modéliser les inhomogénéités de conductivité électrique, L. Serron, stage de Master première année, Université de Nice Sophia Antipolis.