To investigate how brain metabolites, especially glutamate and glutamate to glutamine ratio of pgACC modulate the neural response within these areas and how this affects their function during emotion facial expression matching task.

Seventy healthy volunteers underwent magnetic resonance spectroscopy (MRS) and task functional magnetic resonance imaging (fMRI) in 7 Tesla scanner. PgACC MRS data were obtained using STEAM sequence and analyzed using LCModel.

Angry, fearful, and happy facial expressions were presented in an affect-matching block where one of the two facial expressions presented matched the target facial expression. The control condition was form matching. Data were preprocessed and analyzed in SPM 8.

Glutamate to Creatine ratio measured in pgACC positively correlated with BOLD response in the right DLPFC during negative emotional perception (FWE = 0.05) Glutamate to glutamine ratio indicating on-off mechanisms in pgACC positively correlated with BOLD responses in FFA extending to cerebellum cluster (FWE < 0.05).

This study indicate that pgACC, baseline metabolism predicts neural response to emotional processing. We conclude that individuals with higher glutamate ratios, an excitatory neurotransmitter, in pgACC during rest might have a better coping mechanism to potential danger indicated by perception of angry or afraid faces.

The higher glutamate to glutamine ratio in pgACC indicates a higher turnover of excitatory metabolite glutamate. This mechanism is associated with higher emotional response in fusiform area and cerebellum suggesting higher visual attention towards negative emotions.

The authors have not supplied their declaration of competing interest.