3-DIMENSIONAL LOCALIZATION OF DIPOLES FOR POTENTIALS-EVOKED BY POSTERIOR TIBIAL NERVE-STIMULATION IN THE MONKEY

Somatosensory evoked potentials (SEPs) elicited by right posterior tib ial nerve stimulation were simultaneously recorded from 21-27 epidural electrodes in three monkeys. N23-P40 was recorded anterior to the lef t central sulcus, and P23-N40 was recorded on the parietal midline and the middle portion of the right hemisphere, These potentials were tho ught to be the primary cortical responses elicited by posterior tibial nerve stimulation in the monkey, since a topographical map made of th em corresponded to the paradoxical lateralization of the primary corti cal components in human posterior tibial nerve SEPs. Current source ge nerators (dipoles) of these potentials were 3-dimensionally identified dipoles located in the left side of the mesial wall of the anterior p arietal cortex, and oriented obliquely toward the right hemisphere by a dipole tracing (DT) method in which the 3-dimensional localization o f dipoles in the brain were estimated and superimposed on magnetic res onance imaging (MRI) images. (C) 1997 Elsevier Science B.V.