Localization of dipole by boundary element method in three dimensional reconstructed monkey brain.

The boundary element method was applied to 3-dimensionally reconstructed monkey brain to localize a current source generator (dipole) of somatosensory evoked potentials (SEPs) recorded from epidural electrodes under assumption that a brain is electrically homogeneous and is bounded by a high resistant substance (skull). Absolute mean deviation of estimated dipoles from actual dipoles artificially generated by electrical stimulation at known coordinates in the brain were within 1-3 mm. The estimated dipole computed from SEPs by right median nerve stimulation at latency of P10-N10 waves was located in area 3b of the somatosensory hand area in monkey. Our data suggest that this technique of locating dipoles by the boundary element method applied to a reconstructed brain allows accurate determination of the 3-dimensional coordinates of a dipole.