From Dipoles to Multipoles : Parametric Solutions to the Inverse Problem in MEG

In order to reconcile the advantages of the classical dipole model and minimum norm imaging techniques, higherorder parametric source models based on multipolar expansions of the source have been suggested. We evaluate the ability of dipolar and multipolar MEG source estimation frameworks to localize spatially extended patches of cortical activity. The results show the performance of the different models with respect to the area of active cortex and to variable noise conditions and demonstrate the utility of the multipole model.