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Posteromedial cortex glutamate and GABA predict intrinsic functional connectivity of the default mode network

Dimitrios Kapogiannis, David A. Reiter, Auriel A. Willette, Mark P. Mattson

Neuroimage September 18, 2012 DOI: 10.1016/j.neuroimage.2012.09.029 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Observational cohort Peer reviewed
Sample size 20
Population Healthy men
Topics Default mode network
Keywords Glutamate receptor Glutamatergic Gabaergic Excitatory postsynaptic potential Neurotransmitter Gamma-aminobutyric acid Inhibitory postsynaptic potential Functional connectivity Central nervous system
Citations 212
Key findings Glutamate and GABA concentrations in the posteromedial cortex explain about half of the variance in default mode network intrinsic functional connectivity, with glutamate positively and GABA negatively correlated.

Abstract

The balance between excitatory glutamatergic projection neurons and inhibitory GABAergic interneurons determines the function of cortical microcircuits. How these neurotransmitters relate to the functional status of an entire macro-scale network remains unknown. The posteromedial cortex (PMC) is the default mode network (DMN) node with the greatest functional connectivity; therefore, we hypothesized that PMC glutamate and GABA predict intrinsic functional connectivity (iFC) across the entire DMN. In 20 healthy men, we combined J-resolved magnetic resonance spectroscopy to measure glutamate and GABA in the PMC and resting fMRI followed by group Independent Components Analysis to extract the entire DMN. We showed that, controlling for age and partial GM volume in the MRS voxel, PMC glutamate and GABA explained about half of the variance of DMN iFC (represented by the network's beta coefficient for rest). Glutamate correlated positively and GABA correlated negatively with DMN iFC; in an alternative statistical model which included the glutamate/GABA ratio, the ratio correlated positively with DMN iFC. Age had no independent association with DMN iFC. No other network was associated with PMC glutamate or GABA. We conclude that regional neurotransmitter concentrations in a network node strongly predict network but not global brain iFC.

Comparable studies

Other observational and cohort studies on default mode network, most cited first.

Study Year Design Participants
A default mode of brain function Normal adult human brain 2001 Observational study
Resting-State Functional Connectivity Reflects Structural Connectivity in the Default Mode Network Healthy subjects 2008 Observational cohort
Meditation experience is associated with increased cortical thickness Participants with extensive Insight meditation experience and matched controls 2005 Observational cohort n = 20
Meditation experience is associated with differences in default mode network activity and connectivity Experienced meditators and matched meditation-naive controls 2011 Observational cohort
The precuneus/posterior cingulate cortex plays a pivotal role in the default mode network: Evidence from a partial correlation network analysis Healthy subjects 2008 Observational study

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