Abstract/Summary

The ability to discriminate and update the threat or safety value of stimuli in the environment has clear health benefits. A common hallmark of many anxiety disorders is pervasive and sustained responding to stimuli that no longer signal threat, suggesting impaired fear regulation. Unfortunately, some populations, such as adolescents and those with anxious dispositions are particularly vulnerable to anxiety disorders. This body of work examines how individual differences in development and anxious disposition impact fear extinction, the key fear regulatory processes studied in this thesis. In a series of fear conditioning experiments adapted for developmental samples, we demonstrated individual differences in development and anxious disposition to predict substantial variability in fear extinction ability, as measured with psychophysiological and neural correlates. In a developmental sample, we found that younger age and age-related structural changes in the ventromedial prefrontal cortex (vmPFC) are important predictors of continued responding in the amygdala to learned threat vs. safety cues during fear extinction. In adult samples, however, we found intolerance of uncertainty to specifically predict elevated responses to both learned threat and safety cues in psychophysiological correlates and the amygdala during fear extinction, over and above other general measures of anxious disposition. More broadly, these findings highlight the potential of developmental and intolerance of uncertainty-based mechanisms to help understand pathological fear in anxiety disorders and inform future treatment targets.