Application of Equivalent Multipole Moment Method with Polar Translations to Forward Calculation of Neuromagnetic Fields

Abstract

This paper describes an application of the equivalent multipole moment method (EMMM) with polar translations to calculation of magnetic fields induced by a current dipole placed in a human head model. Although the EMMM is a conventional Laplacian field solver based on spherical harmonic functions, the polar translations enable it to treat eccentric and exclusive spheres in arbitrary arrangements. The head model is composed of seven spheres corresponding to skin, two eyeballs, skull, cerebral spinal fluid, grey matter, and white matter. The validity of the calculated magnetic fields and the magnetic flux linkages with a loop coil locating nearby the model is successfully confirmed by the reciprocity theorem derived by Eaton.