Direct source reconstruction of MEG inverse problem using cerebral cortex shapes

Direct reconstruction method (DRM) for MEG inverse problem is the method which can estimate unknown current source parameters without initial parameter guesses and iterative computing of forward solution. However this reconstruction algorithm requires the magnetic field information on the whole sphere which encloses the head. It is impossible to measure the magnetic field on the lower hemisphere in actual MEG measurement, because neck and jaw prevent us from locating sensors. In this paper, we consider the estimation error occurred by deficiency of the magnetic field information and propose a new method improving DRM using cerebral cortex shapes, which makes it possible to reconstruct unknown source parameters accurately only from the magnetic field information on the upper hemisphere. We prove effectiveness of the proposed method by numerical simulations and real SEF-MEG source localization experiments.