Individual differences in GABA content are reliable but are not uniform across the human cortex.
1H magnetic resonance spectroscopy (MRS) provides a powerful tool to measure gamma-aminobutyric acid (GABA), the principle inhibitory neurotransmitter in the human brain. We asked whether individual differences in MRS estimates of GABA are uniform across the cortex or vary between regions. In two sessions, resting GABA concentrations in the lateral prefrontal, sensorimotor, dorsal premotor, and occipital cortices were measured in twenty-eight healthy individuals. GABA estimates within each region were stable across weeks, with low coefficients of variation. Despite this stability, the GABA estimates were not correlated between regions. In contrast, the percentage of brain tissue per volume, a control measure, was correlated between the three anterior regions. These results provide an interesting dissociation between an anatomical measure of individual differences and a neurochemical measure. The different patterns of anatomy and GABA concentrations have implications for understanding regional variation in the molecular topography of the brain in health and disease.
University of California, Berkeley, Berkeley, CA, United States. Electronic address: igreenhouse@berkeley.edu.
Ian
I
Greenhouse
University of California, Berkeley, Berkeley, CA, United States.
Sean
S
Noah
University of California, Davis, Davis, CA, United States.
Richard J
RJ
Maddock
University of California, Berkeley, Berkeley, CA, United States.
Richard B
RB
Ivry
D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000378:metabolism*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D057054:Molecular Imaging / Q000379:methods*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018377:Neurotransmitter Agents; D005680:gamma-Aminobutyric Acid
Cortex; GABA; Individual differences; Inhibition; Magnetic resonance spectroscopy; Molecular topography