Evaluation of boundary element methods for the EEG forward problem: effect of linear interpolation.

We implement the approach for solving the boundary integral equation for the electroencephalography (EEG) forward problem proposed by de Munck [1], in which the electric potential varies linearly across each plane triangle of the mesh. Previous solutions have assumed the potential is constant across an element. We calculate the electric potential and systematically investigate the effect of different mesh choices and dipole locations by using a three concentric sphere head model for which there is an analytic solution. Implementing the linear interpolation approximation results in errors that are approximately half those of the same mesh when the potential is assumed to be constant, and provides a reliable method for solving the problem.