Gyngell M L, Bock C, Schmitz B, Hoehn-Berlage M, Hossmann K A
Max-Planck-Institut für Neurologische Forschung, Abteilung für experimentelle Neurologie, Köln, Federal Republic of Germany.
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.
