GABAergic effect on resting-state functional connectivity: Dynamics under pharmacological antagonism
Fatima A Nasrallah1, Kavita Kaur D/O Ranjit Singh2, Ling Yun Yeow2
1Magnetic Resonance Imaging Group, Singapore Bioimaging Consortium, Agency for Science Technology and Research, Singapore; Clinical Imaging Research Centre, National University of Singapore, Singapore; Queensland Brain Institute, University of Queensland, Brisbane, QLD, Australia.
Neuroimage
|January 26, 2017
Summary
Modulating the GABAergic system with bicuculline increased brain excitability and resting-state functional connectivity (BOLD signals). This suggests the GABAergic system plays a key role in neural and hemodynamic oscillations.
Area of Science:
- Neuroscience
- Neuroimaging
- Systems Neuroscience
Background:
- Resting-state functional connectivity MRI (fcMRI) reveals synchronous brain activity, but underlying mechanisms are unclear.
- Gamma-aminobutyric acid (GABA) levels are reportedly linked to functional connectivity.
- GABAergic system's role in modulating brain network dynamics needs further elucidation.
Purpose of the Study:
- To investigate if altering GABAergic transmission affects resting-state functional connectivity.
- To explore the relationship between GABAergic activity, neural oscillations, and BOLD signals.
Main Methods:
- Modulated GABAergic activity using bicuculline, a GABAA receptor antagonist, in anesthetized rats.
- Measured resting and evoked electrophysiology and BOLD signals.
- Analyzed EEG coherence and cerebral blood flow.
Main Results:
- Bicuculline administration increased somatosensory BOLD activation and evoked potentials, indicating heightened brain excitability.
- Resting BOLD correlations increased within and between cortical areas and between cortex and striatum.
- EEG coherence changes mirrored BOLD correlation shifts, suggesting a link between neural and hemodynamic connectivity.
Conclusions:
- The GABAergic system significantly influences neural and hemodynamic oscillations.
- Findings support the neuronal basis of fcMRI and its correlation with neurotransmission.
- Long-range projections via GABAergic interneurons may mediate observed functional connectivity changes.
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