EEG/MEG Source Imaging: Methods, Challenges, and Open Issues

Table 1

A comparison of the four methods for solving Poisson's equation in a realistic head model is presented: boundary element method (BEM), finite element method (FEM), isotropic finite difference method (iFDM), and anisotropic finite difference method (aFDM).

	BEM	FEM	iFDM	aFDM
Position of computational points	Surface	Volume	Volume	Volume
Free choice of computational points	Yes	Yes	No	No
System matrix	Full	Sparse	Sparse	Sparse
Solvers	Direct/iterative	Iterative	Iterative	Iterative
Number of compartments	Small	Large	Large	Large
Requires tessellation	Yes	Yes	No	No
Handles anisotropy	No	Yes	No	Yes