GABA concentration in posterior cingulate cortex predicts putamen response during resting state fMRI

Area of Science:

• Neuroscience
• Neuroimaging
• Biochemistry

Background:

• Resting state networks (RSNs) are crucial for brain function.
• Neurotransmitters, particularly gamma-aminobutyric acid (GABA) and glutamate, regulate the excitation-inhibition balance.
• Magnetic resonance spectroscopy (MRS) enables in vivo measurement of these neurotransmitters.

Purpose of the Study:

• To investigate the relationship between GABA concentration in the posterior cingulate cortex (PCC) and resting-state functional connectivity.
• To explore the role of GABA in the segregation of motor input within RSNs.

Main Methods:

• Single-voxel MRS (PRESS sequence) was used to measure GABA levels in the PCC of 20 healthy males at 3 T.
• Resting-state functional magnetic resonance imaging (fMRI) was acquired.
• Dual regression analysis was employed, incorporating the GABA/Creatine+Phosphocreatine ratio (GABA ratio) into the general linear model.

Main Results:

• A negative linear relationship was observed between the GABA ratio in the PCC and the connection strength of the putamen to the default-mode network (DMN).
• Individual GABA levels influenced specific resting-state network metrics.

Conclusions:

• GABA in the PCC plays a significant role in modulating resting-state functional connectivity, specifically impacting the segregation of motor input.
• These findings underscore the importance of the GABAergic system in maintaining brain network organization during rest.