1995 年 19 巻 3 号 p. 734-739
To determine the possibility of discriminating multisources in the brain by using a 3-D magnetoencephalogram (MEG), measurements were made of magnetic fields produced by two and three current dipoles implanted in a spherical head model and a human cranium model. The 3-D MEG measurement was made by using a 3-D second-order gradiometer connected to three rf-SQUIDs, which can detect magnetic field components perpendicular to and tangential to the scalp. The MEG distribution perpendicular to the scalp was not helpful for estimating the location and number of sources, owing to the lack of a dipole pattern. By referring to the MEG distribution tangential to the scalp, however, two and three current sources could be clearly discriminated in both a spherical head model and a cranium model. It was found that this MEG measurement tangential to the scalp could provide information on new constrained conditions for calculation of the inverse problems with multi-sources.