Neuroscience 2004 Abstract
| Presentation Number: | 977.4 |
|---|---|
| Abstract Title: | The bold response in rat somatic sensory cortex peaks with multiple whisker stimulation at low whisk rates: A functional magnetic resonance imaging study without anesthesia. |
| Authors: |
Melzer, P.*1
; Ebner, F. F.1
1Dept Psychol, Vanderbilt Univ, Nashville, TN |
| Primary Theme and Topics |
Sensory Systems - Tactile/Somatosensory -- Barrels |
| Secondary Theme and Topics | Sensory Systems<br />- Tactile/Somatosensory<br />-- Cortex imaging |
| Session: |
977. Barrels II Poster |
| Presentation Time: | Wednesday, October 27, 2004 4:00 PM-5:00 PM |
| Location: | San Diego Convention Center - Hall A-H, Board # Y5 |
| Keywords: | vibrissa, barrel, fmri, cerebral blood flow |
Rats explore their environment with their whiskers whisking at rates up to 25 whisks/s. ~7 whisks/s dominate. Additional, less prominent, spectral peaks can be observed at lower and higher rates. We examined the effect of frequency of whisker deflection on the blood oxygenation level-dependent (BOLD) signal in rat somatic sensory cortex with functional magnetic resonance imaging at 4.7 T using a FLASH sequence in a block design [Sachdev et al., NeuroImage 19:742]. Five adult Long-Evans rats were trained to tolerate immobilization with restraint. Stress effects were suppressed with diazepam sedation (Valium, 12 mg/kg b.w., i.p.). The rats were imaged twice. Two 4-minute epochs of rest were alternated with two equivalent epochs of whisker stimulation. Nine caudal mystacial whiskers on the right side were deflected simultaneously with 1, 3 or 9 air puffs/s. Whisker stimulation at the three frequencies increased the BOLD signal in primary and secondary somatic sensory cortex on both sides statistically significantly (P < 0.05). The response was stronger contralateral to stimulation and greatest at 3 air puffs/s. In separate studies with electrophysiological recordings of single-unit responses to the same stimuli [Champney et al., Soc Neurosci Abstr 27:51.11], we observed that the population of responsive neurons decreases and the adaptation of their responsiveness increases non-linearly with linearly increasing frequency of whisker stimulation. Indeed, the interaction between the number of stimuli presented, the number of neurons activated and their degree of adaptation to repetitive stimulation predicts a peak in cerebral activation at frequencies of whisker stimulation between 3 and 6 air puffs/s. Possible mechanisms for the reduced cortical excitation at stimulus frequencies > 6/s are: i) suppression of thalamocortical afferent activity, and ii) inhibition by GABAergic interneurons.
Supported by NS 25907
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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