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Acquisition of Resting-State Functional Magnetic Resonance Imaging Data in the Rat
Published on: August 28, 2021
Resting-state functional connectivity in animal models: modulations by exsanguination
Bharat B Biswal1, Sridhar S Kannurpatti
1Department of Radiology, UMDNJ-New Jersey Medical School, Newark, NJ, USA.
Methods in Molecular Biology (Clifton, N.J.)
|October 8, 2008
Summary
Resting-state functional MRI (fMRI) in rats revealed that reduced blood flow during exsanguination amplifies low-frequency blood oxygenation level dependent (BOLD) signal fluctuations. These brain BOLD signal changes show significant inter-hemispheric synchrony, similar to conscious humans.
Area of Science:
- Neuroimaging
- Systems Neuroscience
- Physiology
Background:
- Resting-state functional magnetic resonance imaging (fMRI) measures spontaneous brain activity.
- Blood oxygenation level dependent (BOLD) signal fluctuations reflect neural activity and cerebral blood flow (CBF).
- Low-frequency fluctuations (0.01–0.125 Hz) are characteristic of resting-state fMRI signals.
Purpose of the Study:
- To investigate the spatiotemporal characteristics of resting-state fMRI BOLD signal fluctuations in anesthetized rats.
- To examine how exsanguination, altering cerebral blood flow, impacts these BOLD signal fluctuations.
- To compare the spatial distribution and synchrony of BOLD fluctuations with cerebral blood flow dynamics.
Main Methods:
- High-field (9.4 Tesla) fMRI-BOLD measurements were acquired in isoflurane-anesthetized rats under normal and exsanguinated conditions.
- fMRI signal time series underwent low-pass filtering and spectral analysis.
- Cross-correlation analysis was used to assess the spatial distribution and inter-hemispheric synchrony of BOLD fluctuations.
Main Results:
- Under normal conditions, low-frequency BOLD fluctuations occurred in the cortex and thalamus.
- Exsanguination decreased mean arterial pressure and significantly increased the amplitude and power of low-frequency BOLD fluctuations.
- BOLD fluctuations exhibited substantial inter-hemispheric synchrony, particularly in the cortex and thalamus, with distinct patterns in the hippocampus.
Conclusions:
- The observed changes in resting-state BOLD signal fluctuations during exsanguination suggest a myogenic dependence, mirroring cerebral blood flow responses.
- High inter-hemispheric synchrony in BOLD fluctuations resembles patterns seen in the conscious human brain.
- Differential phase characteristics of low-frequency BOLD fluctuations highlight distinct functional network organizations within the rat brain.
