Refining the sensory and motor ratunculus of the rat upper extremity using fMRI and direct nerve stimulation

Younghoon R. Cho, Christopher P. Pawela, Rupeng Li, Dennis Kao, Marie L. Schulte, Matthew L. Runquist, Ji Geng Yan, Hani S. Matloub, Safwan S. Jaradeh, Anthony G. Hudetz, James S. Hyde

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

It is well understood that the different regions of the body have cortical representations in proportion to the degree of innervation. Our current understanding of the rat upper extremity has been enhanced using functional MRI (fMRI), but these studies are often limited to the rat forepaw. The purpose of this study is to describe a new technique that allows us to refine the sensory and motor representations in the cerebral cortex by surgically implanting electrodes on the major nerves of the rat upper extremity and providing direct electrical nerve stimulation while acquiring fMRI images. This technique was used to stimulate the ulnar, median, radial, and musculocutaneous nerves in the rat upper extremity using four different stimulation sequences that varied in frequency (5 Hz vs. 10 Hz) and current (0.5 mA vs. 1.0 mA). A distinct pattern of cortical activation was found for each nerve. The higher stimulation current resulted in a dramatic increase in the level of cortical activation. The higher stimulation frequency resulted in both increases and attenuation of cortical activation in different regions of the brain, depending on which nerve was stimulated.

Original languageEnglish (US)
Pages (from-to)901-909
Number of pages9
JournalMagnetic resonance in medicine
Volume58
Issue number5
DOIs
StatePublished - Nov 2007

Keywords

  • Direct nerve stimulation
  • Rat motor sensory homunculus
  • Ratunculus
  • fMRI

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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