title: Third-order harmonic expansion of the magnetoencephalography forward and inverse problems in an ellipsoidal brain model.
abstract: We present a forward modeling solution in the form of an array response kernel for magnetoencephalography. We consider the case when the brain's anatomy is approximated by an ellipsoid and an equivalent current dipole model is used to approximate brain sources. The proposed solution includes the contributions up to the third-order ellipsoidal harmonic terms; hence, we compare this new approximation against the previously available one that only considered up to second-order harmonics. We evaluated the proposed solution when used in the inverse problem of estimating physiologically feasible visual evoked responses from magnetoencephalography data. Our results showed that the contribution of the third-order harmonic terms provides a more realistic representation of the magnetic fields (closer to those generated with a numerical approximation based on the boundary element method) and, subsecuently, the estimated equivalent current dipoles are a better fit to those observed in practice (e.g., in visual evoked potentials). Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Centro de Investigación y de Estudios Avanzados (Cinvestav), Unidad Monterrey, Mexico.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Alcocer-Sosa
authors.affiliation: Centro de Investigación y de Estudios Avanzados (Cinvestav), Unidad Monterrey, Mexico.
authors.forename: David
authors.identifier: 0000-0003-0424-3053
authors.initials: D
authors.lastname: Gutiérrez
mesh_terms: D001921:Brain / Q000502:physiology*; D005074:Evoked Potentials, Visual; D006801:Humans; D015225:Magnetoencephalography; D008959:Models, Neurological
keywords: brain modeling; ellipsoidal harmonics; equivalent current dipole; inverse problems; magnetoencephalography