Forward problem solution of ESI using FEM and BEM with quadratic isoparametric elements

The representations of the intracellular electric current of active cell populations in the brain based on recorded scalp potentials are called electric source images (ESIs). For accurate interpretation of the measured data it is necessary to develop numerical models that incorporate the correct geometry and electrical properties of the head. This paper presents the solutions of the two numerical models that employ quadratic isoparametric elements: the Finite Element Method (FEM) and the Boundary Element Method (BEM). The solutions are obtained for a tangential dipole source located at different depths in a concentric spherical shell model of the head. The Relative Difference Measures (RDMs) are calculated for each method using approximately same number of surface nodes. It is observed that for deep sources the RDMs for FEM solutions are smaller than the corresponding values obtained for BEM solution. However, for shallow sources RDMs for BEM model are superior compared to the RDMs of the FEM solutions.