Resting-state functional connectivity and quantitation of glutamate and GABA of the PCC/precuneus by magnetic resonance spectroscopy at 7T in healthy individuals

PLoS One. 2020 Dec 29;15(12):e0244491. doi: 10.1371/journal.pone.0244491. eCollection 2020.

Abstract

The default mode network (DMN) is the main large-scale network of the resting brain and the PCC/precuneus is a major hub of this network. Glutamate and GABA (γ-amino butyric acid) are the main excitatory and inhibitory neurotransmitters in the CNS, respectively. We studied glutamate and GABA concentrations in the PCC/precuneus via magnetic resonance spectroscopy (MRS) at 7T in relation to age and correlated them with functional connectivity between this region and other DMN nodes in ten healthy right-handed volunteers ranging in age between 23-68 years. Mean functional connectivity of the PCC/precuneus to the other DMN nodes and the glutamate/GABA ratio significantly correlated with age (r = 0.802, p = 0.005 and r = 0.793, p = 0.006, respectively) but not with each other. Glutamate and GABA alone did not significantly correlate with age nor with functional connectivity within the DMN. The glutamate/GABA ratio and functional connectivity of the PCC/precuneus are, therefore, independent age-related biomarkers of the DMN and may be combined in a multimodal pipeline to study DMN alterations in various disease states.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Brain Mapping / methods
  • Female
  • Glutamic Acid / analysis*
  • Glutamic Acid / metabolism
  • Healthy Volunteers
  • Humans
  • Magnetic Resonance Spectroscopy / methods
  • Male
  • Middle Aged
  • Multiparametric Magnetic Resonance Imaging / methods
  • Nerve Net / diagnostic imaging
  • Nerve Net / physiology*
  • Parietal Lobe / diagnostic imaging
  • Parietal Lobe / metabolism*
  • Rest / physiology*
  • Young Adult
  • gamma-Aminobutyric Acid / analysis*
  • gamma-Aminobutyric Acid / metabolism

Substances

  • Glutamic Acid
  • gamma-Aminobutyric Acid

Grants and funding

The authors acknowledge the facilities, scientific and technical assistance, and salary support of BAM from the National Imaging Facility, a National Collaborative Research Infrastructure Strategy (NCRIS) capability, at the Melbourne Brain Center Imaging Unit, The University of Melbourne. OGM was supported by the Melbourne Research Scholarship (MRS), The University of Melbourne and The Neuroscience Foundation, The Royal Melbourne Hospital.