抄録
This paper presents the results of computer modeling studies of the effects of a volume current with multi-sources on 3-D magnetoencephalogram (MEG) measurement. An inner-surface model (homogeneous medium: 0.5 Sm-1) of the skull consisting of 1979 triangular elements was used. In calculation of 3-D magnetic field components (Br, Bθ, Bφ) in a spherical coordinate system, multi-sources were set to the pariental, temporal, and occipital lobes of the brain. A 3-D second-order gradiometer developed by the authors, with an orthogonally wound Ni-Ti wire on a rectangular 3×3×6 cm solid, was also used. The base line of the detection coil for B<r was 2.8 cm and those of the coils for Bθ and Bφ were 1.4 cm. The effects of the volume current on the tangential components (Bθ, Bφ) were not observed in the pariental, occipital, and upper parts of the temporal lobe. However, in the lower parts of the temporal lobe to the boundary, the directions of the multi-sources had some effects.
