Effects of Prediction Error and Acute Stress on the Retrieval-Extinction of Fear Memories of Different Strength

Subjects: Psychology >> Medical Psychology submitted time 2021-02-05

李俊娇 陈伟 胡琰健 曹杨婧文 郑希付

Abstract： Under the framework of Reconsolidation Interference of conditioned fear memory, Prediction Error (PE) is demonstrated as a necessary condition of memory destabilization. However, the role of PE in destabilizing fear memories of different strength is unclear. The degree of PE that is needed to effectively reactivate fear memory may be changeable according to the strength of memory. It is unknown whether the PE used to reactivate weak memories is still valid in retrieving enhanced memories. Besides, explorations of possible solutions are rare if strong memories are resistant to undergoing reconsolidation. Among factors that are possible to help to overcome the boundary condition, the effects of stress hormone are worth exploring. However, the manipulation of fear strength in human studies in the laboratory has not been well developed. Thus, the present study has three main aims: (1) based on previous results in animal studies, we tested the effect of fear memory strength manipulation in the laboratory settings in humans; (2) to examine the effect of PE during reactivation on destabilizing different strength memories and (3) to test the possible influence of post-reactivation exogenous stress to the retrieval-extinction of fear memories. The three days retrieval-extinction paradigm was adopted in the present study. We manipulated the memory strength through two kinds of acquisition procedures on the first day, which varied the predictability of the unconditioned stimulus (US) occurrence after the conditioned stimulus (CS). 24 hours later, a reminder contained a single PE was used to reactivate memories, then followed by a stress task (Social Evaluate Cold Pressor test, SECPT) or not before extinction. After 24 hours, a test of spontaneous recovery and reinstatement was utilized to measure the return of fear in each condition. All participants were divided into three conditions: CS-Predictable US_no Stress Group, CS-Unpredictable US_no Stress Group and the CS-Unpredictable US_Stress Group. The skin conductance response (SCR) and fear-potentiated startle response (FPS) were used as measurements of conditioned fear. The results showed that there was a relatively higher increase in fear response (SCR) from Day 1 to Day 2 in the CS-Unpredictable US condition than the CS-Predictable US condition, which may suggest the difference of memory strength among conditions. And for the weak fear memory (CS-predictable US), the reactivation that contained single PE and followed by extinction training can prevent the spontaneous recovery, especially on the SCR measurement. While in the enhanced memory condition (CS-unpredictable US), the extinguished memory had a distinct relapse in the memory test on the third day, which suggests the failure of memory destabilization. Furthermore, under this condition, if the acute stress task was adopted after reactivation, the return of fear would further increase, comparing with the no stress manipulation conditions. These results indicate that PE used to reactivate weak memories is insufficient to destabilize strong memories; and the post-reactivate acute stress cannot compensate this deficit caused by boundary conditions (e.g., strength). We further discussed possible interpretations of these results and the implications for the translation of retrieval-extinction to clinical practice and the cure of post-traumatic stress disorders (PTSD).

Peer Review Status:Awaiting Review

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