to use a source model consisting of only a few discrete dipoles, namely the equivalent current dipole (ECD) model [59–62]. As opposed to the general applicability of the distributed source models, the ECD model assumes small extents of the neural responses, which may or may not be valid depending on the particular circumstances. Even if the assumptions are valid, the appropriate number of dipoles is often difficult to be determined a priori or solely from the EEG/MEG data [63].
