Inverse and forward modeling of interictal spikes in the EEG, MEG and ECoG

We tested the validity of EEG and MEG source characterization of interictal spikes in epilepsy patients for which subdural grid registrations of the ECoG and accurate geometrical information from MRI and CT were available. A boundary element volume conduction model was used while for the inverse problem dipolar and distributed source models and epicortical potentials were tested. Results show that for a good qualitative correspondence between sources computed from EEG and ECoG signals distributed source models are to be preferred. For combined EEG-MEG the dipole model performs slightly better. For a good quantitative correspondence, proper modeling of the conductivity values and geometry is essential.