Human hand and lip sensorimotor cortex as studied on electrocorticography

https://doi.org/10.1016/0168-5597(92)90016-5Get rights and content

Abstract

We investigated functional topography of human hand and lip sensorimotor cortex using somatosensory evoked potentials (SEPs) from chronically indwelling subdural grid electrodes (ECoG) in 3 epilepsy patients during stimulation of median nerve, ulnar nerve, and lower lip. We used dipole modeling to determine the cortical location of each peripheral sensory field. The cortical locations were in the postcentral gyrus and showed a clear somatotopic organization from medial superior to lateral inferior in the order: ulnar nerve, median nerve, and lip. The source localizations agreed with the results of cortical stimulations and anatomical features on intraoperative photographs. The cortical regions of median and ulnar nerve each could be modeled by sequential tangential and radial dipoles. The cortical region of lip was different and could be explained mostly by tangential dipoles. These findings suggest a difference in the cortical organization of human lip and hand sensory cortex and are consistent with a larger representation of lip in the posterior bank of central fissure in area 3b than on the gyral surface in area 1, similar to findings in macaque. Further studies in a larger population of patients with ECoG or normal subjects with scalp-EEG and MEG are warranted to test this hypothesis.

References (51)

  • S. Goldring et al.

    Comparative study of sensory input to motor cortex in animals and man

    Electroenceph. clin. Neurophysiol.

    (1970)
  • P.L. Nunez

    The brain's magnetic field: some effects of multiple sources on localization methods

    Electroenceph. clin. Neurophysiol.

    (1986)
  • J. Tiihonen et al.

    Early deflections of cerebral magnetic responses to median nerve stimulation

    Electroenceph. clin. Neurophysiol.

    (1989)
  • T. Allison et al.

    On the neural origin of early components of the human somatosensory evoked potential

  • T. Allison et al.

    Human cortical potentials evoked by stimulation of the median nerve. I. Cytoarchitectonic areas generating short-latency activity

    J. Neurophysiol.

    (1989)
  • C. Baumgartner et al.

    Spatiotemporal modeling of somatosensory evoked magnetic fields

  • R. Broughton et al.

    Scalp and direct cortical recordings of somatosensory evoked potentials in man (circa 1967)

    Can. J. Psychol.

    (1981)
  • U.W. Buettner et al.

    Diagnostic significance of cortical somatosensory evoked potentials following trigeminal nerve stimulation

  • G. Celesia

    Somatosensory evoked potentials recorded directly from human thalamus and Sm I cortical area

    Arch. Neurol.

    (1979)
  • K.H. Chiappa

    Evoked Potentials in Clinical Medicine

  • B.N. Cuffin

    Effects of fissures in the brain on electroencephalograms and magnetoencephalo-grams

    J. Appl. Phys.

    (1985)
  • J.C. De Munck et al.

    Mathematical dipoles are adequate to describe realistic generators of human brain activity

    IEEE Trans. Biomed. Eng.

    (1988)
  • J.E. Desmedt et al.

    Functional organization of far-field and cortical components of somatosensory evoked potentials in normal adults

  • J.E. Desmedt et al.

    Somatosensory evoked potentials in man: subcortical and cortical components and their neural basis

    Ann. NY Acad. Sci.

    (1982)
  • G. Findler et al.

    Sensory evoked response to electrical stimulation of the trigeminal nerve in humans

    J. Neurosurg.

    (1982)
  • Cited by (34)

    • MEG in the macaque monkey and human: Distinguishing cortical fields in space and time

      2010, Brain Research
      Citation Excerpt :

      In monkeys, previous work recording intracranial somatosensory evoked potentials (SEP's) using electrical stimulation applied to median nerve, lip, tongue and palate showed that, as in our study, latencies were slightly shorter for lip relative to hand responses (N9–P14 for lip and N10–P20 for hand; McCarthy and Allison, 1995). In humans, the evoked fields resulting from lip stimulation show a clear ∼ 20 ms peak as well as a later ∼ 35 ms peak (Table 2; Disbrow et al., 2003; Hoshiyama et al., 1996; Nakahara et al., 2004; Nakamura et al., 1998) with latencies for the lip response shorter than the digit response (Baumgartner et al., 1992). It is likely that the monkey ∼ 10 ms and ∼ 25 ms peaks observed here from lip stimulation correspond with the human ∼ 20 ms and ∼ 35 ms peaks respectively.

    • Cortical somatosensory evoked potential mapping

      2003, Handbook of Clinical Neurophysiology
      Citation Excerpt :

      Median nerve stimulation at the wrist and posterior tibial nerve stimulation at the ankle are the most popular stimulation sites, to obtain SSEPs of the cortical “hand” and “foot” areas, respectively. For face area SSEPs, stimulation can be applied directly on the lip (mandibular branch of the trigeminal nerve), cheek, or chin (Baumgartner et al., 1992; McCarthy et al., 1993). The polarity of the stimuli can be alternated to minimize stimulus artifact.

    View all citing articles on Scopus

    This research was supported by the Fonds zur Förderung der wissenschaftlichen Forschung Österreichs (Erwin Schrödinger Stipendium J246M and J334MED and Forschungsprojekt P7434) and by USPHS Grant 1-R01-NS20806.

    View full text