A comparison of different numerical methods for solving the forward problem in EEG and MEG

In view of the complexity of the conductivity and the geometry of the human head, a numerical method would appear to be necessary for the adequate calculation of the electric potential and the magnetic induction generated by electric sources within the brain. Four numerical methods that could be used for solving this problem are the finite-difference method, the finite-element method, the boundary-element method, and the finite-volume method. These methods could be used to calculate the electric potential and the magnetic induction directly. Alternatively, they could be applied to the electric potential or the electric field and the magnetic induction could then be determined by numerical integration of the Biot-Savart law. In this paper the four numerical methods are briefly reviewed. Thereafter the relative merits of the methods and the various options for using them to solve the EEG and MEG problem are evaluated.