Neuromagnetic investigation of somatotopy of human hand somatosensory cortex

SummaryIn order to investigate functional topography of human hand somatosensory cortex we recorded somatosensory evoked fields (SEFs) on MEG during the first 40 ms after stimulation of median nerve, ulnar nerve, and the 5 digits. We applied dipole modeling to determine the three-dimensional cortial representations of different peripheral receptive fields. Median nerve and ulnar nerve SEFs exhibited the previously described N20 and P30 components with a magnetic field pattern emerging from the head superior and re-entering the head inferior for the N20 component; the magnetic field pattern of the P30 component was of reversed orientation. Reversals of field direction were oriented along the anterior-posterior axis. SEFs during digit stimulation showed analogous N22 and P32 components and similar magnetic field patterns. Reversals of field direction showed a shift from lateral inferior to medial superior for thumb to little finger. Dipole modeling yielded good fits at these peak latencies accounting for an average of 83% of the data variance. The cortical digit representations were arranged in an orderly somatotopic way from lateral inferior to medial superior in the sequence thumb, index finger, middle finger, ring finger, and little finger. Median nerve cortical representation was lateral inferior to that of ulnar nerve. Isofield maps and dipole locations for these components are consistent with neuronal activity in the posterior bank of central fissure corresponding to area 3b. We conclude that SEFs recorded on MEG in conjunction with source localization techniques are useful to investigate functional topography of human hand somatosensory cortex non-invasively.

[1]  Samuel J. Williamson,et al.  Magnetic Fields of the Cerebral Cortex , 1980 .

[2]  L. Kaufman,et al.  On the relation between somatic evoked potentials and fields. , 1981, The International journal of neuroscience.

[3]  C. C. Wood,et al.  Human cortical potentials evoked by stimulation of the median nerve. I. Cytoarchitectonic areas generating short-latency activity. , 1989, Journal of neurophysiology.

[4]  William Sutherling,et al.  Current source-density and neuromagnetic analysis of the direct cortical response in rat cortex , 1988, Brain Research.

[5]  G. Klem,et al.  Extraoperative Cortical Functional Localization in Patients with Epilepsy , 1987, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[6]  D. H. McLain,et al.  Drawing Contours from Arbitrary Data Points , 1974, Comput. J..

[7]  M. Raichle,et al.  Mapping human somatosensory cortex with positron emission tomography. , 1987, Journal of neurosurgery.

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

[9]  B. Roth,et al.  Magnetic determination of the spatial extent of a single cortical current source: a theoretical analysis. , 1988, Electroencephalography and clinical neurophysiology.

[10]  W W Sutherling,et al.  Functional anatomy of human hand sensorimotor cortex from spatiotemporal analysis of electrocorticography. , 1991, Electroencephalography and clinical neurophysiology.

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

[12]  J. Sarvas,et al.  Mixed and sensory nerve stimulations activate different cytoarchitectonic areas in the human primary somatosensory cortex SI , 1986, Experimental Brain Research.

[13]  P Gloor,et al.  Neuronal Generators and the Problem of Localization in Electroencephalography: Application of Volume Conductor Theory to Electroencephalography , 1985, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[14]  S. Goldring,et al.  Localization of function in the excision of lesions from the sensorimotor region. , 1984, Journal of neurosurgery.

[15]  William H. Press,et al.  Numerical recipes , 1990 .

[16]  J. Fermaglich.  Electric Fields of the Brain: The Neurophysics of EEG , 1982 .

[17]  G L Romani,et al.  Neuromagnetic characterization of the cortical response to median nerve stimulation in the steady state paradigm. , 1987, The International journal of neuroscience.

[18]  M Hämäläinen,et al.  Early deflections of cerebral magnetic responses to median nerve stimulation. , 1989, Electroencephalography and clinical neurophysiology.

[19]  V. Mountcastle.  Modality and topographic properties of single neurons of cat's somatic sensory cortex. , 1957, Journal of neurophysiology.

[20]  William Sutherling,et al.  Intracellular currents of interictal penicillin spikes: Evidence from neuromagnetic mapping , 1986, Brain Research.

[21]  Magnetic field associated with neural activities in an isolated cerebellum , 1987, Brain Research.

[22]  C. C. Wood,et al.  Localization of human sensorimotor cortex during surgery by cortical surface recording of somatosensory evoked potentials. , 1988, Journal of neurosurgery.

[23]  T. Rasmussen,et al.  Scalp and direct cortical recordings of somatosensory evoked potentials in man (circa 1967). , 1981, Canadian journal of psychology.

[24]  L. Deecke,et al.  Homuncular organization of human motor cortex as indicated by neuromagnetic recordings , 1991, Neuroscience Letters.

[25]  H. Spekreijse,et al.  Mathematical dipoles are adequate to describe realistic generators of human brain activity , 1988, IEEE Transactions on Biomedical Engineering.

[26]  L. Kaufman,et al.  Somatotopic organization of the human somatosensory cortex revealed by neuromagnetic measurements , 2004, Experimental Brain Research.

[27]  C Tomberg,et al.  Emulation of somatosensory evoked potential (SEP) components with the 3-shell head model and the problem of 'ghost potential fields' when using an average reference in brain mapping. , 1990, Electroencephalography and clinical neurophysiology.

[28]  P H Crandall,et al.  The magnetic and electric fields agree with intracranial localizations of somatosensory cortex , 1988, Neurology.

[29]  P. Hazemann,et al.  Handbook of Electroencephalography and Clinical Neurophysiology , 1975 .

[30]  T A Duff,et al.  Topography of scalp recorded potentials evoked by stimulation of the digits. , 1980, Electroencephalography and clinical neurophysiology.

[31]  L. Kaufman,et al.  Somatically Evoked Magnetic Fields of the Human Brain , 1978, Science.

[32]  Fernando Lopes da Silva,et al.  Biophysical Aspects of EEG and MEG , 2022 .

[33]  J E Desmedt,et al.  Color imaging of parietal and frontal somatosensory potential fields evoked by stimulation of median or posterior tibial nerve in man. , 1985, Electroencephalography and clinical neurophysiology.

[34]  D. Cohen,et al.  Demonstration of useful differences between magnetoencephalogram and electroencephalogram. , 1983, Electroencephalography and clinical neurophysiology.

[35]  C. Nicholson,et al.  MEG source models and physiology. , 1987, Physics in medicine and biology.

[36]  D. Barth,et al.  Spatiotemporal Modeling of Somatosensory Evoked Magnetic Fields , 1989 .

[37]  Neuromagnetic Localisation of Sensorimotor Cortex Sources Associated with Voluntary Movements in Humans , 1989 .

[38]  M. Hämäläinen,et al.  Realistic conductivity geometry model of the human head for interpretation of neuromagnetic data , 1989, IEEE Transactions on Biomedical Engineering.

[39]  J E Desmedt,et al.  Bit-mapped color imaging of human evoked potentials with reference to the N20, P22, P27 and N30 somatosensory responses. , 1987, Electroencephalography and clinical neurophysiology.

[40]  J. Kaas,et al.  Multiple representations of the body within the primary somatosensory cortex of primates. , 1979, Science.

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

[42]  C C Wood,et al.  Electrical sources in human somatosensory cortex: identification by combined magnetic and potential recordings. , 1985, Science.

[43]  B. Neil Cuffin,et al.  Effects of detector coil size and configuration on measurements of the magnetoencephalogram , 1983 .

[44]  L Leinonen,et al.  Cerebral magnetic responses to stimulation of ulnar and median nerves. , 1987, Electroencephalography and clinical neurophysiology.

[45]  W W Sutherling,et al.  Spatiotemporal modeling of cerebral evoked magnetic fields to median nerve stimulation. , 1991, Electroencephalography and clinical neurophysiology.

[46]  Woolsey,et al.  Cortical Sensory Organization , 1981, Cortical Sensory Organization.

[47]  G L Romani,et al.  Biomagnetic instrumentation. , 1982, The Review of scientific instruments.

[48]  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.