A MEG Multiresolution Model Selection Procedure Reveals the Cortical Somatotopy of Hand-Fingers

We introduce a new model selection procedure (MiMS) to the MEG source estimation problem, based on a multireso-lution approach. The technique uses an explicit piecewise image model of cortical currents that is iteratively updated through increasing spatial resolution according to the generalized cross-validation (GCV) error principle. The method is illustrated on MEG data testing for the somatotopic organization of early brain responses following stimulation of hand fingers. In addition to the canonical somatotopic organization of brain responses along the post-central gyrus, these data suggest that the MiMS approach could help revealing the spatial extent of mass-neural responses as a pertinent parameter of brain activation, in complement to measures of amplitude variations of cortical currents.