Model studies of spreading electrical activities in the brain on MEG/EEG inverse problem

Using magnetoencephalogram (MEG) and electroencephalogram (EEG) the source estimation is performed in recent research. We simulated the MEG source estimation (inverse problem) for the purpose of finding the spread and the amplitude of neural activities. We proposed the hexagonal spreading dipole (HSD) model to briefly describe the source´s spread. Inverse simulation indicates that the source localization using the HSD model can be as accurate as the localization with a single dipole model. As the spread and the amplitude are associated with each other, it is effective to combine their information. However, it is significantly difficult to find the orientation of the HSD model, because the radial component of the neural source has few magnetic fields. The information of a cerebral cortex shape or EEG signal with a radial component should be applied to the source estimation algorithm