Interoception in Fear Learning and Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a psychiatric condition characterized by sustained symptoms, including reexperiencing, hyperarousal, avoidance, and mood alterations, following exposure to a traumatic event. Although symptom presentations in PTSD are heterogeneous and incompletely understood, they likely involve interactions between neural circuits involved in memory and fear learning and multiple body systems involved in threat processing. PTSD differs from other psychiatric conditions in that it is a temporally specific disorder, triggered by a traumatic event that elicits heightened physiological arousal, and fear. Fear conditioning and fear extinction learning have been studied extensively in relation to PTSD, because of their central role in the development and maintenance of threat-related associations. Interoception, the process by which organisms sense, interpret, and integrate their internal body signals, may contribute to disrupted fear learning and to the varied symptom presentations of PTSD in humans. In this review, the authors discuss how interoceptive signals may serve as unconditioned responses to trauma that subsequently serve as conditioned stimuli, trigger avoidance and higher-order conditioning of other stimuli associated with these interoceptive signals, and constitute an important aspect of the fear learning context, thus influencing the specificity versus generalization of fear acquisition, consolidation, and extinction. The authors conclude by identifying avenues for future research to enhance understanding of PTSD and the role of interoceptive signals in fear learning and in the development, maintenance, and treatment of PTSD.