Neuroscience 2004 Abstract
| Presentation Number: | 431.2 |
|---|---|
| Abstract Title: | Functional magnetic resonance imaging: Effect of blood pressure increases and decreases. |
| Authors: |
Wang, R.*1,2
; Qiao, M.2
; Foniok, T.2
; Kirk, D.3
; Vivanco, R.4
; Tuor, U.1,2
1Neurosci. Res. Group, Univ. of Calgary, calgary, Canada 2Inst. for Biodiagnostics (West), NRC, Univ. of Calgary, calgary, Canada 3Exptl. Imaging Ctr., Univ. of Calgary, calgary, Canada 4MB, B153 3330 hospital DR NW, T2N4N1, |
| Primary Theme and Topics |
Homeostatic and Neuroendocrine Systems - Cerebral Blood Flow and Homeostasis -- fMRI, PET, SPECT |
| Session: |
431. Functional Imaging Poster |
| Presentation Time: | Monday, October 25, 2004 9:00 AM-10:00 AM |
| Location: | San Diego Convention Center - Hall A-H, Board # II27 |
| Keywords: | IMAGING, BLOOD FLOW |
Introduction:Functional magnetic resonance imaging (fMRI) provides an indirect measure of cerebral activation via changes in blood-oxygen-level-dependent (BOLD) signal,which assumes a coupling between neural activity and tissue oxygenation changes.We sought to determine whether blood pressure(BP) changes contribute to functional activation detected by fMRI.Methods:Images were acquired in rats using a 9.4T MR system prior to and following a BP increase or decrease with and without electrical stimulation of the forepaw.Four BP ranges were investigated (1-30,31-45,46-60 and >60 mmHg).Transient BP increases were produced with norepinephrine (e.g.0.15-1.2ug/kg,I.V.)and decreases with arfonad (e.g.0.5-3.25mg/kg,I.V.).Fuzzy clustering (EvIdent) and cross-correlation analysis were used to identify voxels of apparent activation in response to stimulation or the BP time course measured arterially.Results: Electrical stimulation of the forepaw produced activation in the sensory-motor cortex.This activation increased as BP increased with changes being marked when BP increased by 46-60mmHg.Similarly,hypotension induced a decrease in activation, with the most significant change occurring when BP decreased by >60mmHg.With either hypertension or hypotension,the greater the change in BP,the greater was the apparent activation response to the BP change.This indicates that hypertension augments the activation produced by electrical stimulation of the forepaw whereas hypotension has an opposite effect.Conclusions: BP changes affect the cerebral activation measured using fMRI,with hypertension leading to an overestimate,and hypotension,an underestimate of the response.BP changes should be considered during the interpretation of fMRI studies.
Supported by Canadian Institutes for Health Research
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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