Memory, Interrupted: A Retrieval Model of Intrusive Memories, Recovery Trajectories, and Neurobiological Effects in Post-Traumatic Stress Disorder

Abstract

Post-traumatic stress disorder (PTSD) is a psychiatric disorder often characterized by the unwanted re-experiencing of a traumatic event through nightmares, flashbacks, and/or intrusive memories. This paper presents a neurocomputational model using the ACT-R cognitive architecture that simulates intrusive memory retrieval following a potentially traumatic event (PTE) and derives predictions about an individual’s recovery trajectory, behavioral symptoms, and neurological effects. Memory intrusions were captured in the ACT-R framework by weighting the prior probability of re-encoding a memory by an emotional intensity term I, which captures the degree to which an event was perceived as dangerous or traumatic. A series of simulations were run in which a model performed memory retrievals under naturalistic conditions for up to two months after experiencing a simulated PTE. It was found that I had a significant effect on the probability of experiencing traumatic memory intrusions following a PTE, and that, under different conditions, the model experienced different probabilities of undergoing different recovery trajectories.