Influence of brain conductivity on magnetoencephalographic simulations in realistic head models

Abstract

The influence of brain tissue conductivity on magnetoencephalography (MEG) has been largely unknown. We compared the normal component of the magnetic field calculated at 61 detectors and the localization accuracy of 9 different realistic head finite element method (FEM) models containing various gray and white matter conductivities to the results obtained using a FEM realistic head model containing published baseline conductivity values. In the models containing altered conductivity values, the gray and white matter were varied, one at a time, between 10% and 200% of their baseline values and then varied simultaneously. Although changes in conductivity values for gray and for white matter individually altered the calculated magnetic fields and source localization accuracy only slightly, altering both gray and white matter conductivities simultaneously caused significant discrepancies in calculated results compared to the model with the baseline conductivity values. This study suggests that accurate gray and white matter conductivities may be important for MEG source localization in human brain.