Abstract
Differences in γ-aminobutyric acid (GABA) levels measured with Magnetic Resonance Spectroscopy have been shown to correlate with behavioral performance over a number of tasks and cortical regions. These correlations appear to be regionally and functionally specific. In this study, we test the hypothesis that GABA levels will be correlated within individuals for functionally related regions—the left and right sensorimotor cortex. In addition, we investigate whether this is driven by bulk tissue composition. GABA measurements using edited MRS data were acquired from the left and right sensorimotor cortex in 24 participants. T1-weighted MR images were also acquired and segmented to determine the tissue composition of the voxel. GABA level is shown to correlate significantly between the left and right regions (r = 0.64, p < 0.03). Tissue composition is highly correlated between sides, but does not explain significant variance in the bilateral correlation. In conclusion, individual differences in GABA level, which have previously been described as functionally and regionally specific, are correlated between homologous sensorimotor regions. This correlation is not driven by bulk differences in voxel tissue composition.
Highlights
Magnetic resonance spectroscopy (MRS) measurements can detect individual differences in the levels of γ-aminobutyric acid (GABA), which are correlated with behavioral paradigms thought to rely on the efficacy of the GABAergic system
GABA is more highly concentrated in grey matter (GM) than white matter (WM) [25], so we explored whether individual differences in GABA level are driven by differences in voxel
We found a significant inter-region intra-individual correlation in GABA levels between homologous brain regions
Summary
Magnetic resonance spectroscopy (MRS) measurements can detect individual differences in the levels of γ-aminobutyric acid (GABA), which are correlated with behavioral paradigms thought to rely on the efficacy of the GABAergic system. MRI experiments (an indirect measure of neuronal activity) [1,2,3,4,5]; functional responses to stimuli as recorded by magnetoencephalography [1,6]; psychophysical task performance [4,7,8,9,10]; quantitative measures of personality traits [11,12] and age [13] These correlational relationships have been shown in various regions of the brain, including primary sensory and motor regions [4,8,9,14], prefrontal motor regions [7,10] and areas of the frontal lobe [11,13,15] and suggest that individual differences in GABA levels have functional and behavioral correlates. Two separate studies [11,16], studying a large number of voxels, have found no significant inter-regional correlations between five regions of interest
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