An important distinction in research on the neural mechanisms of emotion regulation involves the relatively limited duration of emotional states versus emotional traits that are defined as the stable tendency to experience particular emotions in daily life. Neuroimaging investigations of the regulation of anger states point to the involvement of reciprocal changes in the prefrontal cortex and amygdala activity, but the neural substrate of trait anger has received less attention. We used resting-state functional MRI to determine whether the variation in the strength of functional connectivity between the amygdala and the orbitofrontal cortex is associated with trait anger. Sixteen healthy men completed the Spielberger State-Trait Anger Expression Inventory. Correlational analysis for resting-state functional connectivity (RSFC) was carried out with the left and the right amygdala as separate seed regions. Anger measures were correlated to RSFC involving the right and the left amygdala on a voxel-by-voxel basis across all individuals. We found that Trait Anger was inversely associated with the strength of RSFC between the amygdala and the contralateral middle orbitofrontal cortex. The association was stronger for the right amygdala-left orbitofrontal connection. Anger Control, the tendency to try to control expressions of anger, showed the opposite pattern of being positively correlated with amygdala-orbitofrontal connectivity. The present study provides evidence that RSFC in a corticolimbic circuit might subserve stable differences in anger regulation. Our findings also suggest that RSFC may prove valuable as a trait marker for disorders characterized by emotional dysregulation such as depression, anxiety, and personality disorders.
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