Baseline effects of transcranial direct current stimulation on glutamatergic neurotransmission and large-scale network connectivity

Michael A. Hunter, Brian A. Coffman, Charles Gasparovic, Vince D. Calhoun, Michael C. Trumbo, Vincent P. Clark

Research output: Contribution to journalArticle

Abstract

Transcranial direct current stimulation (tDCS) modulates glutamatergic neurotransmission and can be utilized as a novel treatment intervention for a multitude of populations. However, the exact mechanism by which tDCS modulates the brains neural architecture, from the micro to macro scales, have yet to be investigated. Using a within-subjects design, resting-state functional magnetic resonance imaging (rs-fMRI) and proton magnetic resonance spectroscopy (1H MRS) were performed immediately before and after the administration of anodal tDCS over right parietal cortex. Group independent component analysis (ICA) was used to decompose fMRI scans into 75 brain networks, from which 12 resting-state networks were identified that had significant voxel-wise functional connectivity to anatomical regions of interest. 1H MRS was used to obtain estimates of combined glutamate and glutamine (Glx) concentrations from bilateral intraparietal sulcus. Paired sample t-tests showed significantly increased Glx under the anodal electrode, but not in homologous regions of the contralateral hemisphere. Increases of within-network connectivity were observed within the superior parietal, inferior parietal, left frontal-parietal, salience and cerebellar intrinsic networks, and decreases in connectivity were observed in the anterior cingulate and the basal ganglia (p<0.05, FDR-corrected). Individual differences in Glx concentrations predicted network connectivity in most of these networks. The observed relationships between glutamatergic neurotransmission and network connectivity may be used to guide future tDCS protocols that aim to target and alter neuroplastic mechanisms in healthy individuals as well as those with psychiatric and neurologic disorders.

Original languageEnglish (US)
Pages (from-to)92-107
Number of pages16
JournalBrain research
Volume1594
DOIs
StatePublished - Jan 12 2015
Externally publishedYes

Keywords

  • Functional network connectivity (FNC)
  • Glutamine-glutamate (Glx)
  • Independent component analysis (ICA)
  • Magnetic resonance spectroscopy (MRS)
  • Parietal lobe
  • Resting-state functional magnetic resonance imaging (rs-fMRI)
  • Transcranial direct current stimulation (tDCS)

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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