A Shift from Value- to Saliency- Neural Encoding of Subjective Value in Combat Veterans with PTSD during Decision Making under Uncertainty

Combat soldiers are vulnerable to Post-traumatic Stress Disorder (PTSD), following traumatic experiences in the battlefield. Studies have often used fear-related design to unravel the underlying neural deficits of learning and emotion regulation in PTSD patients. However, the role of individual uncertainty attitudes in the development of trauma-related psychopathology has hardly been examined, especially that uncertainty is highly related to the traumatic experiences from the battlefield. Through a monetary gambling paradigm inspired by behavioral economics, we explore the neural markers of PTSD symptoms of combat veterans in the realm of decision making, focusing on the subjective valuation of uncertain monetary gains and losses. We identify increased behavioral aversion to risky monetary gains and ambiguous monetary losses related to higher PTSD symptom severity. We find the key role of the emotional numbing cluster of PTSD symptoms in influencing the general activities of ventromedial prefrontal cortex (vmPFC) during valuation. We further suggest that a shift from value- to saliency- encoding pattern of subjective values across rewards and punishments in the valuation neural system, especially in ventral striatum, exist in combat veterans with PTSD, compared with trauma-exposed controls. Our results elucidate the increased neural sensitivity to highly salient rewards and punishments related to PTSD symptoms, and at the same time, point to the fundamental differences in brain regions involved in reward- and punishment- processing. We also identify potential resiliency neural mechanisms that could protect trauma-exposed individuals against developing PTSD symptoms.