Role of the inhibitory system in shaping the BOLD fMRI response

The shape of the blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal can vary considerably even across structures of the same sensory pathway. Here, we characterized the temporal behavior of the stimulus-evoked BOLD response in the primary cortical and subcor...

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Bibliographic Details
Published in:NeuroImage (Orlando, Fla.) Fla.), 2019-11, Vol.201, p.116034-116034, Article 116034
Main Authors: Aksenov, Daniil P., Li, Limin, Miller, Michael J., Wyrwicz, Alice M.
Format: Article
Language:English
Subjects:
Animals
BOLD
Brain mapping
Cerebral Cortex - diagnostic imaging
Cerebral Cortex - physiology
Cortex (barrel)
Cortex (somatosensory)
Cortex (temporal)
Experiments
Female
Firing rate
fMRI
Functional magnetic resonance imaging
Magnetic Resonance Imaging - methods
Muscimol
Neural Inhibition - physiology
Neuroimaging
Oxygen - blood
Rabbits
Somatosensory
Thalamic nuclei
Thalamus
Time course
Unit activity
Visual
Visual cortex
γ-Aminobutyric acid A receptors
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Summary:The shape of the blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal can vary considerably even across structures of the same sensory pathway. Here, we characterized the temporal behavior of the stimulus-evoked BOLD response in the primary cortical and subcortical regions of the visual and somatosensory whisker systems in awake rabbits. Despite similar BOLD responses in the thalamic nuclei, considerable differences in shape and duration emerged between the sensory cortices. Whereas the BOLD response in the whisker barrel cortex (WBC) was non-adaptive, BOLD in the visual cortex (V1) showed adaptation similar to simultaneously-recorded LFP and single unit activity. Analysis of baseline neuronal activity revealed significantly lower firing rates in V1 vs. WBC. We hypothesized that these changes point to region-dependent differences in the inhibitory systems which shape the hemodynamic response in each structure. To test the effect of neuronal baseline level inhibition on the BOLD signal shape, we locally injected the GABAA agonist muscimol in WBC. Adaptation emerged in the BOLD response after injection, along with an overall decrease in baseline firing rate. These findings point to the importance of region-specific inhibitory shaping in determining the temporal behavior of the BOLD response in different brain areas.
ISSN:1053-8119
1095-9572
DOI:10.1016/j.neuroimage.2019.116034