The measurement of magnetic fields over the head generated by electric currents in
the brain. As in any electrical conductor, electric fields in the brain are accompanied
by orthogonal magnetic fields. The measurement of these fields provides information
about the localization of brain activity which is complementary to that provided by
ELECTROENCEPHALOGRAPHY. Magnetoencephalography may be used alone or together with
electroencephalography, for measurement of spontaneous or evoked activity, and for
research or clinical purposes