Motor and sensory cortex in humans: Topography studied with chronic subdural stimulation

Sumio Uematsu, Ronald Lesser, Robert S. Fisher, Barry Gordon, Kunitada Hara, Gregory L. Krauss, Eileen P. Vining, Robert W. Webber

Research output: Contribution to journalArticlepeer-review

159 Scopus citations


CLASSIC NEUROSURGICAL TEACHING holds that once the Rolandic fissure (Rf) has been located, there are distinct differentiated primary motor and sensory functional units confined within a narrow cortical strip: Brodmann's Areas 4 and 6 for primary motor units in front of the Rf and 3, 1, and 2 for sensory units behind the Rf. To test this assumption, we examined in detail the records of cortical mapping done by electrical stimulation of the cerebral cortex via implanted subdural electrode grids in 35 patients with seizure disorders. Of 1381 stimulations of the electrode sites, 346 (25.1%) produced primary motor or motor-arrest and sensory responses in contralateral body parts: 56.8% were primary motor responses; 16.2% were motor-arrest; 22.5% were sensory; and the remaining 4.5% were mixed motor and sensory responses. Two-thirds (65.9%) of the primary motor responses were located within 10 mm of the Rf, and the remaining one-third (34.1%) were more than 10 mm anterior to the Rf or were posterior to the Rf. Furthermore, in the patient group with brain lesions, fewer than one-third (28.1%) of the responses were within the 10-mm narrow anterior strip. Our study reconfirmed that a significant number—at least one-third—of motor responses are distributed outside the classic narrow cortical strip. In patients with brain lesions, the motor representation is further displaced outside the narrow strip. This finding indicates that primary motor cortex may extend beyond the gyrus immediately anterior to the Rf.

Original languageEnglish (US)
Pages (from-to)59-72
Number of pages14
Issue number1
StatePublished - Jul 1992


  • Brain mapping
  • Cortical stimulation
  • Epilepsy
  • Motor cortex
  • Rolandic fissure
  • Sensory cortex
  • Subdural electrode

ASJC Scopus subject areas

  • Clinical Neurology
  • Surgery


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