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

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

Ofer M Gonen  1   2   3 , Bradford A Moffat  2 , Patrick Kwan  1   2   3   4 , Terence J O'Brien  1   2   3   4 , Patricia M Desmond  2   5 , Elaine Lui  2   5
Affiliations
Observational Study

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

Ofer M Gonen et al. PLoS One. .

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.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. T1-weighted MRI with superimposed MRS 8 cm3 voxel.
(left–parasagittal; right–axial).
Fig 2
Fig 2. Regions of interest of cortical networks as used in the CONN.
(Red–PCC/Pr; Yellow–MPFC; Green–left IPL; Magenta–right IPL).
Fig 3
Fig 3. Example of LCModel output spectrum.
(Cr = creatine; PCr = phosphocreatine; GSH = glutathione; GABA = γ-amino butyric acid; NAA = N-acetylaspartic acid).
Fig 4
Fig 4. Glutamate/GABA concentration ratio in the PCC/precuneus vs age.
Fig 5
Fig 5. Mean functional connectivity of the PCC/precuneus vs age (seed-based).
(Calculated as mean connectivity to the other ROIs expressed as Fisher transformed Z values; SB_FC = seed-based functional connectivity).
Fig 6
Fig 6. Mean functional connectivity of the PCC/precuneus vs age (ICA-based).
(Calculated as mean connectivity to the other ROIs expressed as Fisher transformed Z values; ICA_FC = independent component analysis-based functional connectivity).
See this image and copyright information in PMC

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