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Functional Magnetic Resonance Spectroscopy at 7 T in the Rat Barrel Cortex During Whisker Activation
Published on: February 8, 2019
Functional MRI impulse response for BOLD and CBV contrast in rat somatosensory cortex
Afonso C Silva1, Alan P Koretsky, Jeff H Duyn
1Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1065, USA. silvaa@ninds.nih.gov
Magnetic Resonance in Medicine
|May 31, 2007
Summary
Cerebral blood volume (CBV) responses peak faster and are narrower than blood oxygen level-dependent (BOLD) responses in fMRI. This suggests faster neurovascular mechanisms and impacts fMRI temporal resolution.
Area of Science:
- Neuroimaging
- Physiology
Background:
- Functional MRI (fMRI) temporal resolution is limited by vascular processes.
- Understanding the hemodynamic response (HDR) is crucial for fMRI accuracy.
Purpose of the Study:
- To measure and compare the impulse response (IR) of BOLD and CBV signals in a rat model.
- To determine the temporal resolution of the hemodynamic response (HDR) using fMRI.
Main Methods:
- Utilized an 11.7T scanner for high-field fMRI.
- Employed a binary m-sequence probe method for sensitive single-pixel IR estimation.
- Measured BOLD and iron-oxide-derived CBV IRs during somatosensory activation in rats.
Main Results:
- CBV IR was significantly narrower (FWHM 1.37s) and peaked earlier (TTP 1.65s) than BOLD IR (FWHM 1.92s, TTP 2.18s).
- Neurovascular control mechanisms demonstrated temporal resolution better than 1.5s FWHM.
- Findings suggest significant contribution of hemoglobin transit to BOLD signal dispersion.
Conclusions:
- CBV offers a more temporally resolved view of brain activation compared to BOLD.
- The temporal resolution of fMRI is influenced by vascular transit dynamics.
- These insights have implications for optimizing fMRI temporal resolution in research and clinical applications.
