Numerical model of electrical potential within the human head

A realistic subject‐specific human head model was constructed based on structural magnetic resonance imaging (sMRI) data. Electrical conductivities were assigned inhomogeneously according to tissue type and variability within each head segment. A three‐dimensional (3D) finite‐difference method (FDM) was used to compute the evolution of the electrical potential from a single electrical dipole within the brain. The Douglas–Rachford FDM and three versions of iterative FDM were tested on a three‐layer concentric sphere model. The successive over‐relaxation (SOR) iterative method showed the best convergence properties and hence was used to compute the electrical potential within a realistic head model. The effect of using inhomogeneous rather than homogeneous conductivities within head segments of this model was shown to be important.