Modulation of GABA and resting state functional connectivity by transcranial direct current stimulation

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Abstract

We previously demonstrated that network-level functional connectivity in the human brain could be related to levels of inhibition in a major network node at baseline (Stagg et al., 2014). Here, we build upon this finding to directly investigate the effects of perturbing M1 GABA and resting state functional connectivity using transcranial direct current stimulation (tDCS), a neuromodulatory approach that has previously been demonstrated to modulate both metrics. FMRI data and GABA levels, as assessed by Magnetic Resonance Spectroscopy, were measured before and after 20 minutes of 1mA anodal or sham tDCS. In line with previous studies, baseline GABA levels were negatively correlated with the strength of functional connectivity within the resting motor network. However, although we confirm the previously reported findings that anodal tDCS reduces GABA concentration and increases functional connectivity in the stimulated motor cortex, these changes are not correlated, suggesting they may be driven by distinct underlying mechanisms.

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Velicia Bachtiar

Oxford Centre for Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom

Competing interests
No competing interests declared.
Jamie Near

Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Oxford, United Kingdom

Competing interests
No competing interests declared.
Heidi Johansen-Berg

Oxford Centre for Functional MRI of the Brain, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom

Competing interests
Heidi Johansen-Berg, Reviewing editor, eLife.
Charlotte J Stagg

Oxford Centre for Functional MRI of the Brain, University of Oxford, Oxford, United Kingdom

For correspondence
charlotte.stagg@ndcn.ox.ac.uk

Competing interests
No competing interests declared.

Ethics

Human subjects: Participants gave their informed consent to participate in this study in accordance with ethical approval from the East London Research Ethics Committee (Ref: 10/H0703/50).

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.