title: Individual variability in verbal fluency correlates with γ-aminobutyric acid concentration in the left inferior frontal gyrus.
abstract: A particular feature of the inferior frontal gyrus (IFG), which is considered a central region for language processing, is leftward functional/anatomical asymmetry. However, previous studies have not clearly shown lateralization of neurotransmitters in the cortical regions. Using proton magnetic resonance spectroscopy, we measured γ-aminobutyric acid (GABA) concentrations in the bilateral IFG. To evaluate individual variability in linguistic performance, we further used a verbal fluency test. Although GABA+/creatine (Cr) values were not different between the left and the right IFG, we found a significant correlation between category fluency scores and GABA+/Cr values in the left IFG. No correlation was found between letter fluency scores and GABA+/Cr values. We also confirmed that the result was independent of the references used (Cr and H2O). Our results show a new physiological basis of linguistic performance as well as leftward asymmetry of the IFG.
authors.affiliation: aDepartment of Life Sciences, Graduate School of Arts and Sciences bCenter for Evolutionary Cognitive Science, The University of Tokyo cJapan Society for the Promotion of Science, Tokyo dRiken Brain Science Institute, Wako, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nakai
authors.forename: Kazuo
authors.initials: K
authors.lastname: Okanoya
mesh_terms: D000293:Adolescent; D000328:Adult; D007839:Functional Laterality; D006801:Humans; D007802:Language; D008297:Male; D017397:Prefrontal Cortex / Q000378:metabolism*; D066244:Proton Magnetic Resonance Spectroscopy; D014705:Verbal Behavior; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid