Acquisition and inhibition of conditioned fear is modulated by individual stimulus fear-relevance.

Inhibitory learning is an important factor for decreasing fear expression. We investigated conditioned inhibition of learned fear responses using conditioned excitors and inhibitors differing in fear-relevance in a sample of 48 healthy female students. To study the effect of stimulus fear-relevance, we used the fear potentiated startle paradigm in an AX+/BX- discrimination learning task with fear-relevant (spider) vs. fear-irrelevant (butterfly) pictures as CS+ (A) and CS- (B), respectively. We found that, during acquisition, participants with elevated fear of spiders showed stronger fear potentiated startle to AX+ compared to BX- when the inhibitor (B) was fear-irrelevant (butterfly) using both median split as well as correlational analyses. In contrast, when the excitor (A) was fear-irrelevant (butterfly), fear potentiated startle to AX+ compared to BX- was reduced for participants with higher fear of spiders. Effects of conditioned inhibition were studied in a summation test, where excitor and inhibitor were presented in compound (AB) and compared to the last four excitor trials during prior acquisition. Conditioned inhibition was stronger for participants with a higher fear of spiders, when the butterfly acted as conditioned inhibitor (B). On the other hand, when the spider served as conditioned inhibitor, effects of conditioned inhibition were weaker for participants with higher fear of spiders. Hence, rather than to a general preparedness our data point to a specific impairment in safety learning for individually fear-relevant stimuli.

Transdiagnostic trauma severity in anxiety and mood disorders: Functional brain activity during emotional scene processing.

Exposure to traumatic events is not unique to post-traumatic stress disorder (PTSD) and is a significant factor in the development of physical and mental disease across the diagnostic spectrum. Using fMRI, this study assesses functional activation in the amygdala and visual cortex during emotional scene processing in a sample of anxiety and mood disorder patients (N = 162). Replicating previous studies with healthy young participants, a strong covariation was found between functional activity in the amygdala and ventral visual cortex, with blood-oxygen-level dependent (BOLD) activity overall significantly enhanced in both regions when viewing emotionally arousing, compared to neutral, scenes. BOLD changes during emotional processing predicted questionnaire reports of experienced trauma and PTSD-like symptoms (e.g., intrusive thoughts, bad dreams, re-experiencing) and associated functional impairment. Patients showing the smallest BOLD changes when viewing emotional (compared to neutral) scenes in the amygdala and ventral visual cortex reported the highest trauma scores, whereas those patients with the largest amygdala emotional reactivity differences reported the lowest trauma scores. Experiencing a life-threatening event (to self or other) that prompts high fear, distress, and functional impairment was associated with reduced functional limbic-visual activity, independent of a PTSD diagnosis. The findings suggest that experienced trauma may be a transdiagnostic vulnerability factor contributing significantly to psychopathology in many patients with anxiety and mood disorders.