Investigation of the early response to rat forepaw stimulation

Magn Reson Med. 1999 Feb;41(2):247-52. doi: 10.1002/(sici)1522-2594(199902)41:2<247::aid-mrm6>;2-u.


The role of relative cerebral blood volume (rCBV) in the early response of blood oxygenation level-dependent (BOLD) signal following sensory stimulation was assessed. Magnetic resonance imaging (MRI) measurements of rCBV and BOLD signal as a function of time (t) were compared with relative cerebral blood flow (rCBF) obtained by laser doppler flowmetry during a repeated epoch of rat forepaw stimulation in which 6 sec of electrical stimulation followed 54 sec of rest. rCBF(t) exceeded rCBV(t) in somatosensory cortex at all time points and reached a maximal increase (60%) during a 6 sec stimulation that was much higher than maximal rCBV (10%). An initial dip was not observed in BOLD signal, which showed a delay with respect to rCBF that was roughly consistent with the cerebral blood transit time.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blood Volume*
  • Cerebrovascular Circulation*
  • Electric Stimulation*
  • Evoked Potentials, Somatosensory*
  • Forelimb
  • Laser-Doppler Flowmetry
  • Magnetic Resonance Imaging*
  • Male
  • Oxygen / blood*
  • Rats
  • Rats, Sprague-Dawley
  • Somatosensory Cortex / blood supply
  • Somatosensory Cortex / physiology*


  • Oxygen