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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). In this study, 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 min of 1 mA 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.

Original publication

DOI

10.7554/eLife.08789

Type

Journal article

Journal

Elife

Publication Date

18/09/2015

Volume

4

Keywords

GABA, brain stimulation, functional connectivity, human, neuroscience, plasticity, resting state networks, tDCS, Adult, Female, Healthy Volunteers, Humans, Magnetic Resonance Imaging, Male, Motor Cortex, Transcranial Direct Current Stimulation, Young Adult, gamma-Aminobutyric Acid