Cortical representation of dermatomes: MEG-derived maps after tactile stimulation

Mechanical stimulation of skin receptors is known to evoke cortical responses arising from the somatosensory cortex. Here we present a magnetoencephalographic (MEG) study where dermatomal somatosensory-evoked fields (DSSEFs) were recorded after mechanical stimulation of sacral (S1), lumbar (L3), thoracic (Th7), and cervical (C4) dermatomes in three healthy volunteers. All MEG measurements were repeated in order to test the replicability of the results. DSSEFs were successfully measured and modeled in all three participants. The topography and temporal dynamics of cortical responses derived after stimulation of each dermatome are described. We found that cortical-evoked responses can be reliably recorded using MEG after mechanical stimulation of dermatomes when a sufficiently large skin region within the dermatome is stimulated. Primary sensory cortex response (SI) to each of the four dermatomes was replicable and showed stability over time. The MEG-derived individual maps of activation confirm the somatotopic representation of dermatomes in primary sensory cortex and the utility of MEG recordings in disentangling the interactions between primary and secondary sensory cortex during somatic perception.

[1]  R. Kakigi,et al.  Dermatome versus homunculus; detailed topography of the primary somatosensory cortex following trunk stimulation , 2000, Clinical Neurophysiology.

[2]  A. Papanicolaou,et al.  Brain Plasticity for Sensory and Linguistic Functions: A Functional Imaging Study Using Magnetoencephalography With Children and Young Adults , 2001, Journal of child neurology.

[3]  Christoph Stippich,et al.  Interaction of Tactile Input in the Human Primary and Secondary Somatosensory Cortex—A Magnetoencephalographic Study , 2001, NeuroImage.

[4]  R. Dykes,et al.  Organization of primary somatosensory cortex in the cat. , 1980, Journal of neurophysiology.

[5]  D. S. Barth,et al.  Neuromagnetic investigation of somatotopy of human hand somatosensory cortex , 2004, Experimental Brain Research.

[6]  A. Rodriquez,et al.  Somatosensory evoked potentials from dermatomal stimulation as an indicator of L5 and S1 radiculopathy. , 1987, Archives of physical medicine and rehabilitation.

[7]  R. Hari,et al.  Magnetoencephalography in the study of human somatosensory cortical processing. , 1999, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[8]  A. Papanicolaou,et al.  Selective attention effects on somatosensory evoked potentials. , 1989, The International journal of neuroscience.

[9]  C. Manelfe,et al.  [Presurgical evaluation of cerebral tumors with functional MRI]. , 1998, Neuro-Chirurgie.

[10]  Ryusuke Kakigi,et al.  The somatosensory evoked magnetic fields , 2000, Progress in Neurobiology.

[11]  M. Kliot,et al.  Mapping dermatomes during selective dorsal rhizotomy: case report and review of the literature. , 2003, Surgical neurology.

[12]  Andrew C. Papanicolaou,et al.  Fundamentals of Functional Brain Imaging — A Guide to the Methods and their Applications to Psychology and Behavioral Neuroscience. A.C. Papanicolaou, Swets and Zeitlinger, Lisse, 1998, ISBN 90-265-1518-6 , 2000, Biological Psychology.

[13]  G. Kraft,et al.  The clinical use of dermatomal somatosensory evoked potentials in lumbosacral spinal stenosis. , 2004, Physical medicine and rehabilitation clinics of North America.

[14]  R. Hari,et al.  Separate finger representations at the human second somatosensory cortex , 1990, Neuroscience.

[15]  H. Aronen,et al.  Significance of the second somatosensory cortex in sensorimotor integration: enhancement of sensory responses during finger movements , 1996, Neuroreport.

[16]  W. Penfield,et al.  SOMATIC MOTOR AND SENSORY REPRESENTATION IN THE CEREBRAL CORTEX OF MAN AS STUDIED BY ELECTRICAL STIMULATION , 1937 .

[17]  R Hari,et al.  Cerebral magnetic fields to lingual stimulation. , 1991, Electroencephalography and clinical neurophysiology.

[18]  Timothy P L Roberts,et al.  Ipsilateral representation of oral structures in human anterior parietal somatosensory cortex and integration of inputs across the midline , 2003, The Journal of comparative neurology.

[19]  R.N.Dej.,et al.  The Cerebral Cortex of Man , 1951, Neurology.

[20]  R Steinmeier,et al.  Functional neuronavigation with magnetoencephalography: outcome in 50 patients with lesions around the motor cortex. , 1999, Neurosurgical focus.

[21]  P J Kelly,et al.  Integration of functional brain mapping in image-guided neurosurgery. , 1997, Acta neurochirurgica. Supplement.

[22]  D. Dumitru,et al.  SEGMENTAL V DERMATOMAL SOMATOSENSORYEVOKED POTENTIALS: Normal Intertrial Variation and Side-to-Side Comparison , 1993, American journal of physical medicine & rehabilitation.

[23]  R Salmelin,et al.  Comparison of somatosensory evoked fields to airpuff and electric stimuli. , 1994, Electroencephalography and clinical neurophysiology.

[24]  M. Reznik.  [Structure and functions of the cutaneous nervous system]. , 1996, Pathologie-biologie.

[25]  W. Trojaborg,et al.  Somatosensory evoked potentials from cervical and lumbosacral dermatomes , 1991, Acta neurologica Scandinavica.

[26]  G. Tassinari,et al.  Neurophysiologic and neuropsychological aspects of cutaneous perception. , 1984, Clinics in dermatology.

[27]  E. Sedgwick,et al.  Somatosensory evoked potentials from posterior tibial nerve and lumbosacral dermatomes , 1986 .

[28]  T. Morioka,et al.  Comparison of magnetoencephalography, functional MRI, and motor evoked potentials in the localization of the sensory-motor cortex. , 1995, Neurological research.

[29]  C. Woolsey,et al.  Localization in somatic sensory and motor areas of human cerebral cortex as determined by direct recording of evoked potentials and electrical stimulation. , 1979, Journal of neurosurgery.

[30]  Charles B. Wilson,et al.  Magnetic Source Imaging Demonstrates Altered Cortical Distribution of Function in Patients with Arteriovenous Malformations , 2002, Neurosurgery.

[31]  R. Kakigi,et al.  Representation of the Ear in Human Primary Somatosensory Cortex , 2001, NeuroImage.

[32]  H. Duffau,et al.  Usefulness of intraoperative electrical subcortical mapping during surgery for low-grade gliomas located within eloquent brain regions: functional results in a consecutive series of 103 patients. , 2003, Journal of neurosurgery.

[33]  V. Dietz,et al.  Traumatic cervical spinal cord injury: relation between somatosensory evoked potentials, neurological deficit, and hand function. , 1996, Archives of physical medicine and rehabilitation.

[34]  J. Slimp.  Dermatomal Somatosensory Evoked Potentials , 1994 .

[35]  M Hämäläinen,et al.  Somatosensory evoked cerebral magnetic fields from SI and SII in man. , 1984, Electroencephalography and clinical neurophysiology.

[36]  J. Slimp,et al.  Dermatomal somatosensory evoked potentials: cervical, thoracic, and lumbosacral levels. , 1992, Electroencephalography and clinical neurophysiology.

[37]  Allan H. Ropper,et al.  Evoked potentials in clinical medicine (second of two parts). , 1982 .

[38]  J. Sarvas.  Basic mathematical and electromagnetic concepts of the biomagnetic inverse problem. , 1987, Physics in medicine and biology.

[39]  Synek Vm.  Diagnostic importance of somatosensory evoked potentials in the diagnosis of thoracic outlet syndrome. , 1986 .

[40]  Joshua I. Breier,et al.  Integrating sensory and motor mapping in a comprehensive MEG protocol: Clinical validity and replicability , 2004, NeuroImage.

[41]  R. Hari,et al.  Functional Organization of the Human First and Second Somatosensory Cortices: a Neuromagnetic Study , 1993, The European journal of neuroscience.

[42]  K. Zilles,et al.  Areas 3a, 3b, and 1 of Human Primary Somatosensory Cortex 2. Spatial Normalization to Standard Anatomical Space , 2000, NeuroImage.

[43]  E. Gose,et al.  Dermatomal somatosensory evoked potential demonstration of nerve root decompression after VAX-D therapy , 2001, Neurological research.

[44]  A. Nakamura,et al.  Somatosensory Homunculus as Drawn by MEG , 1998, NeuroImage.

[45]  Alfons Schnitzler,et al.  Rapid mapping of finger representations in human primary somatosensory cortex applying neuromagnetic steady-state responses , 2002, Neuroreport.