Somatotopy of human hand somatosensory cortex revealed by dipole source analysis of early somatosensory evoked potentials and 3D-NMR tomography.
Somatosensory evoked potentials (SEPs) to median nerve and finger stimulation were analyzed by means of spatio-temporal dipole modelling combined with 3D-NMR tomography in 8 normal subjects. The early SEPs were modelled by 3 equivalent dipoles located in the region of the brain-stem (B) and in the region of the contralateral somatosensory cortex (T and R). Dipole B explained peaks P14 and N18 at the scalp. Dipole T was tangentially oriented and explained the N20-P20, dipole R was radially oriented and modelled the P22. The tangential dipole sources T were located within a distance of 6 mm on the average and all were less than 9 mm from the posterior bank of the central sulcus. In 6 subjects the tangential sources related to finger stimulation arranged along the central sulcus according to the known somatotopy. The radial sources did not show a consistent somatotopic alignment across subjects. We conclude that the combination of dipole source analysis and 3D-NMR tomography is a useful tool for functional localization within the human hand somatosensory cortex.
Buchner
H
H
Department of Neurology, Klinikum RWTH, Aachen, FRG.
Adams
L
L
Müller
A
A
Ludwig
I
I
Knepper
A
A
Thron
A
A
Niemann
K
K
Scherg
M
M
D000328:Adult; D001931:Brain Mapping; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000294:innervation*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000502:physiology*