Functional MRI of human primary somatosensory and motor cortex during median nerve stimulation

Clin Neurophysiol. 1999 Jan;110(1):47-52. doi: 10.1016/s0168-5597(98)00043-4.


Objectives: Somatosensory evoked potential (SEP) studies suggested that some early cortical SEP components may be generated in the primary motor cortex (M1) rather than the primary somatosensory cortex (S1).

Methods: We now used functional magnetic resonance imaging (fMRI) to study activation of S1 and M1 by electrical median nerve stimulation in healthy volunteers.

Results: The hand areas of both S1 and M1 showed significant activation (correlation coefficients >0.45) in 7 of 9 subjects (activated volume S1 > M1). For comparison, a sequential finger opposition task significantly activated S1 in 7 and M1 in all 9 subjects (activated volume M1 > S1).

Conclusions: These data show that the electrical stimuli used for SEP recording lead to a functional activation of S1 as well as M1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain Mapping
  • Electric Stimulation
  • Humans
  • Magnetic Resonance Imaging
  • Median Nerve / physiology*
  • Middle Aged
  • Motor Cortex / physiology*
  • Somatosensory Cortex / anatomy & histology
  • Somatosensory Cortex / physiology*