Variation of functional MRI signal in response to frequency of somatosensory stimulation in alpha-chloralose anesthetized rats

Magn Reson Med. 1996 Jul;36(1):13-5. doi: 10.1002/mrm.1910360104.


The dependence of functional MRI contrast on the repetition rate (1.5-9 Hz) of a sensory stimulus was investigated with a T2*-weighted gradient echo method during forepaw stimulation of alpha-chloralose anesthetized rats (n = 5). An activation area was observed in the left or right somatosensory cortex dependent on the stimulation of the right or left forepaw, respectively. The activation intensity decreased for stimulation frequencies above 3 Hz, and was negligible at 9 Hz. The interpretation is that at low stimulation rates the neurons can respond to each stimulus, but at higher rates there is insufficient recovery time so that the response is progressively occluded.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anesthesia, Intravenous
  • Anesthetics, Intravenous / administration & dosage*
  • Animals
  • Cerebrovascular Circulation
  • Chloralose / administration & dosage*
  • Electric Stimulation*
  • Forelimb / innervation
  • Glucose / metabolism
  • Image Enhancement
  • Magnetic Resonance Imaging*
  • Magnetic Resonance Spectroscopy
  • Male
  • Neural Pathways / physiopathology
  • Neurons / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Refractory Period, Electrophysiological / physiology
  • Somatosensory Cortex / metabolism
  • Somatosensory Cortex / physiopathology*
  • Subtraction Technique


  • Anesthetics, Intravenous
  • Chloralose
  • Glucose