P2-23. GABA predicts resting-state functional connectivity in cingulate cortex

Abstract

Anterior cingulate cortex (ACC) is one of the key components of default mode network (DMN). Recent studies have shown that local concentrations of gamma-amino butyric acid (GABA), the major inhibitory neurotransmitter in central nervous system, modulate activities of specific neuronal networks at rest. But the relationship between GABA level of ACC and the functional connectivity within DMN is largely unknown. In this study, we performed magnetic resonance spectroscopy (MRS) using MEGA-PRESS sequence to measure the amount of GABA in ACC and resting-state functional magnetic resonance imaging to evaluate intrinsic neuronal activity at rest in twenty-five healthy subjects. This experiment demonstrates that GABA/ Creatine (Cr) ratio is not correlated with the functional connectivity between ACC and other DMN regions. On the other hand, GABA/Cr ratio in ACC is significantly correlated with the functional connectivity between ACC and posterior-mid cingulate cortex (pMCC). These results suggests that local GABA level in ACC is a predictor of synchronized activity within cingulate cortex, rather than within DMN.