Abstract
Several recent studies have reported an inter-individual correlation between regional GABA concentration, as measured by MRS, and the amplitude of the functional blood oxygenation level dependent (BOLD) response in the same region. In this study, we set out to investigate whether this coupling generalizes across cortex. In 18 healthy participants, we performed edited MRS measurements of GABA and BOLD-fMRI experiments using regionally related activation paradigms. Regions and tasks were the: occipital cortex with a visual grating stimulus; auditory cortex with a white noise stimulus; sensorimotor cortex with a finger-tapping task; frontal eye field with a saccade task; and dorsolateral prefrontal cortex with a working memory task. In contrast to the prior literature, no correlation between GABA concentration and BOLD activation was detected in any region. The origin of this discrepancy is not clear. Subtle differences in study design or insufficient power may cause differing results; these and other potential reasons for the discrepant results are discussed. This negative result, although it should be interpreted with caution, has a larger sample size than prior positive results, and suggests that the relationship between GABA and the BOLD response may be more complex than previously thought.
Highlights
blood oxygenation level dependent (BOLD) fMRI is widely used to study brain activity either with or without explicit stimuli
One sensorimotor dataset for the finger tapping task and one dataset for the visual task did not produce subject-level significant activation and were excluded from the secondary analyses that quantified the BOLD using the region of significant activation
The previously observed relationship between GABA levels and BOLD activation in both the occipital cortex and other regions of the brain was not replicated in the current study
Summary
BOLD fMRI is widely used to study brain activity either with or without explicit stimuli. The BOLD signal results from a combination of physiological factors, including cerebral hemodynamics, metabolic responses and oxygenation that provide a surrogate measure of the underlying neural activation [1,2]. In traditional task-based BOLD-fMRI studies, a stimulus is presented to increase brain activity. In response to this stimulus, there is an increase in regional. GABA and BOLD Correlations across Multiple Brain Regions
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