title: Local GABA concentration is related to network-level resting functional connectivity.
abstract: Anatomically plausible networks of functionally inter-connected regions have been reliably demonstrated at rest, although the neurochemical basis of these 'resting state networks' is not well understood. In this study, we combined magnetic resonance spectroscopy (MRS) and resting state fMRI and demonstrated an inverse relationship between levels of the inhibitory neurotransmitter GABA within the primary motor cortex (M1) and the strength of functional connectivity across the resting motor network. This relationship was both neurochemically and anatomically specific. We then went on to show that anodal transcranial direct current stimulation (tDCS), an intervention previously shown to decrease GABA levels within M1, increased resting motor network connectivity. We therefore suggest that network-level functional connectivity within the motor system is related to the degree of inhibition in M1, a major node within the motor network, a finding in line with converging evidence from both simulation and empirical studies. DOI: http://dx.doi.org/10.7554/eLife.01465.001.
authors.affiliation: Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Charlotte J
authors.initials: CJ
authors.lastname: Stagg
authors.forename: Velicia
authors.initials: V
authors.lastname: Bachtiar
authors.forename: Ugwechi
authors.initials: U
authors.lastname: Amadi
authors.forename: Christel A
authors.initials: CA
authors.lastname: Gudberg
authors.forename: Andrei S
authors.initials: AS
authors.lastname: Ilie
authors.forename: Cassandra
authors.initials: C
authors.lastname: Sampaio-Baptista
authors.forename: Jacinta
authors.initials: J
authors.lastname: O'Shea
authors.forename: Mark
authors.initials: M
authors.lastname: Woolrich
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Smith
authors.forename: Nicola
authors.initials: N
authors.lastname: Filippini
authors.forename: Jamie
authors.initials: J
authors.lastname: Near
authors.forename: Heidi
authors.initials: H
authors.lastname: Johansen-Berg
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods; D015536:Down-Regulation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000166:cytology / Q000378:metabolism*; D009415:Nerve Net / Q000166:cytology / Q000378:metabolism*; D009433:Neural Inhibition; D009474:Neurons / Q000378:metabolism*; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid
keywords: GABA; magnetic resonance spectroscopy; resting state fMRI