徐波を持つ異常脳磁場・異常脳波の電源モデルと二次元マップのシミュレーション

Abstract

A source model is proposed to simulate spatial distributions of abnormal MEG and EEG activities such as the delta activity associated with brain tumors. Brain tumor itself is electrically silent and the spherical shell around the tumor might generate abnormal neural activities. The sources of these neural activities are represented by combinations of multiple dipoles, and magnetic fields and electrical potentials over the surface of the head are calculated. The results show that, in a special case where the dipoles orient in the same direction or orient radially, the spatial MEG and EEG patterns are analogous to those generated by a single or two dipoles. The electrical conductivity of brain lesions varies with pathological situations such as edema and calcification. The effect of inhornogeneities of brain lesions on spatial MEG and EEG patterns is also studied. It is found that only the magnitude of the magnetic fields and potentials are influenced by the inhomogeneities, and the spatial patterns are not influenced.