Abstract Negative and positive valence systems (NVS and PVS) pertain to processing of aversive and rewarding stimuli, respectively. Post-Traumatic Stress Disorder (PTSD) has been typically associated with hyper-responsivity of the NVS, and more recently, with deficient PVS functionality. The respective roles of these systems in early PTSD development have yet to be resolved. Here, we assessed neurobehavioral indicators of PVS and NVS longitudinally among 171 adult civilians at 1-, 6-, and 14-months following trauma exposure (TP1, TP2, and TP3). Using the ‘Safe or Risky Domino Choice’ (SRDC) game during fMRI, NVS and PVS functionality (i.e., activity and connectivity) were indicated by the amygdala and ventral striatum (VS) responses to punishments and rewards, respectively. The complementary functionality of these systems was behaviorally assessed as the percentage of risky choices taken during the game. Results revealed that increased amygdala functionality at TP1 was associated with greater PTSD severity at TP1 and TP3, specifically with hyperarousal and intrusion. Decreased VS functionality at TP1 was associated with greater PTSD severity at TP3, specifically with avoidance. Explainable machine learning revealed the primacy of PVS over NVS functionality at TP1 in predicting PTSD severity at TP3. Behaviorally, fewer risky choices were associated with more severe symptoms at TP1, especially with intrusion and avoidance. Overall, these results suggest a differential and potentially complementary involvement of NVS and PVS in PTSD development following trauma. Early therapeutics for PTSD in the immediate aftermath of trauma may thus target both negative and positive valence processing.

Differential Roles of Positive and Negative Valence Systems in the Development of Post-Traumatic Stress Psychopathology