Neural circuitry involved in conditioned inhibition via safety signal learning is sensitive to trauma exposure

Abstract

Exposure to trauma throughout the lifespan is prevalent and increases the likelihood for the development of mental health conditions such as anxiety and post-traumatic stress disorder (PTSD). Safety signal learning (SSL)––a form of conditioned inhibition that involves reducing fear via conditioned safety––has been shown to effectively attenuate fear responses among individuals with trauma exposure, but the association between trauma exposure and the neural mechanisms of SSL remains unknown. Adults with varied prior exposure to trauma completed a conditioned inhibition task during functional MRI scanning and collection of skin conductance response (SCR). Conditioned safety signals reduced psychophysiological reactivity (i.e., SCR) in the overall sample. Although exposure to a higher number of traumatic events was associated with elevated SCR across all task conditions, SCR did not differ between threat in the presence of conditioned safety (i.e., SSL) relative to threat alone in a trauma-related manner. At the neural level, however, higher levels of trauma exposure were associated with lower hippocampal, amygdala, and dorsolateral prefrontal cortical activation during SSL. These findings suggest that while conditioned safety signals can reduce fear in the presence of threat even among individuals exposed to higher degrees of trauma, the neural circuitry involved in SSL is in fact sensitive to trauma exposure. Future research investigating neural processes during SSL among individuals with PTSD or anxiety can further elucidate the ways in which SSL and its neural correlates may reduce fear and link trauma exposure with later mental health conditions.

Keywords

• Threat and safety learning
• Trauma
• fMRI
• Amygdala
• Hippocampus