Enhanced resting-state connectivity of amygdala in the immediate aftermath of acute psychological stress

Recent neuroimaging studies investigating responses to stressful stimuli may importantly further our understanding of psychological trauma etiology. However, theory posits that sustained activation of these stress circuits after the stressful event may play an equally important role in the development of stress-related psychopathology. Importantly, such post-stress network changes remain poorly characterized. The amygdala with its connections is crucially positioned in the central stress circuitry that mediates the initial stress response. Hence, we investigated post-stress amygdala-centered connectivity patterns in order to characterize the aftermath of acute, experimentally-induced stress in healthy humans. We recorded resting-state functional MRI in 26 female participants following a period of moderate psychological stress induced by means of aversive (vs. emotionally neutral) movie watching with a self-referencing instruction. Next, we implemented a seedregion analysis calculating the voxel-wise correlation with the anatomically extracted time-series of the amygdala. Various stress measures confirmed successful stress induction. Moreover, we demonstrated enhanced functional coupling of the amygdala with dorsal anterior cingulate cortex, anterior insula, and a dorso-rostral pontine region, which appears to overlap with the anatomical location of the locus coeruleus (LC), when contrasting the stress with the control group. Thus, we show that the aftermath of acute stress is qualified by prolonged activation in an amygdala-connectivity network. This pattern of co-activation may indicate an extended state of hypervigilance that promotes sustained salience and mnemonic processing after stress. Characterization of the post-stress brain state may provide initial insight into the early phases of psychological trauma formation.