[Modeling the effect of the layer thickness and tissue conductivities of the head and the brain on the EEG potentials...

The influence of the thickness and specific resistance of the brain tissues and its surrounding coverings, brain sulci and anisotropy of white matter electric conductivity on the EEG potentials were modeled. The finite element method was used for simulation, which is realized in the Femlab module. During the comparison of two models with different thickness of the layers was shown the change of potentials by 40% for scull, which thickness varied by 9 mm, and for the gray matter and spinal fluid the change of potentials amounted to 15% by 3 mm variable thickness. The change of conductivity by 25% resulted in the difference of potentials amounted to 15% for the white matter and 1.5% for the cortex of the brain. During the assignment of the anisotropy in the model, by the whole volume of the white matter, sixfold difference of the potentials in comparison with application of isotropic parameters was discovered. The difference of the potentials for single heterogeneity, simulated the sulci of the brain, amounted to 10% in the heterogeneity projection point and increased during the drawing near to the "referent electrode". The model complex of the "sulci of cerebrum" gave significant contribution to the difference of the potentials and depended on the depth of dipole occurrence and nearness of the sulci complex. Significant influence of brain sulci on the EEG-potentials distribution, which can give rise to great artifacts, was discovered.