Motor hand area GABA could be a physiological switch between motor network and default mode network connectivity

Motivation: The functional role of Inhibitory tone in the motor cortex is not completely understood. Previous work has been limited by the coarse spatial resolution in single-voxel spectroscopy. Goal(s): We applied a novel high spatial resolution MR spectroscopic imaging technique to test the relationship between inhibitory tone and motor network (MN) connectivity. Approach: We performed voxel-wise analysis of neurochemical data to correlate measures of inhibitory and excitatory tone with age as a confounder, MN and default mode network (DMN). Results: In the motor hand areas, we demonstrated a reciprocal correlation of inhibitory tone with MN and DMN connectivity. Inhibitory tone could “switch” node connectivity. Impact: The connectivity of key motor network nodes could be influenced by their inhibitory tone and the excitation–inhibition difference. This finding advances the understanding of motor network function and could be a target for modulation in clinical settings.