Divergent influences of anterior cingulate cortex GABA concentrations on the emotion circuitry

Abstract

Neuroimaging research has revealed that emotion processing recruits a widespread neural network including the dorsal anterior cingulate cortex (dACC), hippocampus, and amygdala. Recent studies have started to investigate the role of the primary inhibitory neurotransmitter γ-aminobutyric acid (GABA) on brain function, but little is known about the influences of GABA on this emotion circuitry. Using magnetic resonance spectroscopy, we investigated the role of GABA levels in the dACC on emotion processing by presenting emotional and neutral pictures to 68 healthy male participants during functional magnetic resonance imaging. Results revealed opposing associations of dACC GABA levels and neural activity. GABA levels were positively correlated with blood oxygen level dependent (BOLD) responses to emotional stimuli in the amygdala and to emotional and neutral stimuli in the hippocampus. In contrast, GABA levels were negatively correlated with BOLD responses for the comparison between positive and negative stimuli in the dACC. Our results suggest positive influences of dACC GABA on BOLD responses in the hippocampus and amygdala, and negative influences on BOLD responses in the dACC that are dependent on emotional valence.

Keywords: Amygdala; Emotion processing; GABA; Hippocampus; IAPS; MRS; dACC; fMRI.