Neural Responsivity to Reward versus Punishment Shortly after Trauma Predicts Long-term Development of Post-Traumatic Stress Symptoms.

Abstract Background Processing negative and positive valenced stimuli involve multiple brain regions including the amygdala and ventral striatum (VS). Post-Traumatic Stress Disorder (PTSD) is often associated with hyper-responsivity to negatively valenced, yet recent evidence also points to deficient positive valence functioning. It is yet unclear what is the relative contribution of such opposing valence processing shortly after trauma to the development of chronic PTSD. Methods Neurobehavioral indicators of motivational positive vs. negative valence sensitivities were longitudinally assessed in 171 adults (87 females, age=34.19±11.47 years) at 1-, 6-, and 14-months following trauma exposure (TP1, TP2, TP3). Using a gambling fMRI paradigm, amygdala and VS functionality (activity and functional connectivity with the prefrontal cortex) in response to rewards vs. punishments were assessed with relation to PTSD severity at different time-points. The effect of valence processing was depicted behaviorally by the amount of risk taken to maximize reward. Results PTSD severity at TP1 was associated with greater neural functionality in the amygdala (but not the VS) towards punishments vs. rewards, and fewer risky choices. PTSD severity at TP3 was associated with decreased neural functionality in both the VS and amygdala towards rewards vs. punishments at TP1 (but not with risky behavior). Explainable machine learning revealed the primacy of VS biased processing, over the amygdala, in predicting PTSD severity at TP3. Conclusions These results highlight the importance of biased neural responsivity to positive relative to negative motivational outcomes in PTSD development. Novel therapeutic strategies early after trauma may thus target both valence fronts.