title: V1 surface size predicts GABA concentration in medial occipital cortex.
abstract: A number of recent studies have established a link between behavior and the anatomy of the primary visual cortex (V1). However, one often-raised criticism has been that these studies provide little insight into the mechanisms of the observed relationships. As inhibitory neural interactions have been postulated as an important mechanism for those behaviors related to V1 anatomy, we measured the concentration of inhibitory gamma-amino butyric acid (GABA) in the medial occipital cortex where V1 is located using magnetic resonance spectroscopy (MRS) and estimated the surface area of V1 using fMRI retinotopic mapping. We found a significant positive relationship between GABA concentration and V1 surface area. This relationship was present irrespective of whether the MRS voxel had a fixed size across participants or was proportionally sized to each individual's V1 surface area. Hence, individuals with a larger V1 had a higher GABA concentration in the medial occipital cortex. By tying together V1 size and GABA concentration, our findings point towards individual differences in the level of neural inhibition that might partially mediate the relationships between behavior and V1 neuroanatomy. In addition, they illustrate how stable microscopic properties of neural activity and function are reflected in macro-measures of V1 structure.
authors.affiliation: School of Psychology, University of New South Wales, 2052 Sydney, Australia; Department of Neurophysiology, Max-Planck-Institute for Brain Research, Deutschordenstr. 46, 60528 Frankfurt am Main, Germany; Brain Imaging Center Frankfurt, Goethe-University Frankfurt, Schleusenweg 2-16, 60528 Frankfurt am Main, Germany. Electronic address: bergmann_johanna@yahoo.de.
authors.forename: Johanna
authors.initials: J
authors.lastname: Bergmann
authors.affiliation: Brain Imaging Center Frankfurt, Goethe-University Frankfurt, Schleusenweg 2-16, 60528 Frankfurt am Main, Germany; Institute of Neuroradiology, Goethe-University Frankfurt, Schleusenweg 2-16, 60528 Frankfurt am Main, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Pilatus
authors.affiliation: Department of Neurophysiology, Max-Planck-Institute for Brain Research, Deutschordenstr. 46, 60528 Frankfurt am Main, Germany; Brain Imaging Center Frankfurt, Goethe-University Frankfurt, Schleusenweg 2-16, 60528 Frankfurt am Main, Germany; Institute of Psychology, Department of Biopsychology, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Erhan
authors.initials: E
authors.lastname: Genç
authors.affiliation: Institute of Cognitive Science, University of Osnabrück, Albrechtstrasse 28, 49076 Osnabrück, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Kohler
authors.affiliation: Department of Neurophysiology, Max-Planck-Institute for Brain Research, Deutschordenstr. 46, 60528 Frankfurt am Main, Germany; Brain Imaging Center Frankfurt, Goethe-University Frankfurt, Schleusenweg 2-16, 60528 Frankfurt am Main, Germany; Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Str. 1, 60438 Frankfurt am Main, Germany; Ernst Strüngmann Institute in Cooperation with Max Planck Society, Deutschordenstr. 46, 60528 Frankfurt am Main, Germany.
authors.forename: Wolf
authors.initials: W
authors.lastname: Singer
authors.affiliation: School of Psychology, University of New South Wales, 2052 Sydney, Australia.
authors.forename: Joel
authors.initials: J
authors.lastname: Pearson
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009778:Occipital Lobe / Q000033:anatomy & histology* / Q000737:chemistry* / Q000502:physiology; D010775:Photic Stimulation; D014793:Visual Cortex / Q000033:anatomy & histology* / Q000737:chemistry* / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
chemical_list: D005680:gamma-Aminobutyric Acid
keywords: GABA concentration; Individual differences; Primary visual cortex surface area