The Efffcts Of The Retrieval-Reextinction On Fear Relapse

Fear memories about traumatic experiences are important pathological basis for mental disorders.There are two main types of current treatments for pathological fear memories: one is exposure therapy based on fear extinction;the other uses the principle of memory reconsolidation to alter adverse memories through pharmacological and behavioral interventions.Fear extinction is the formation of a new safe memory competing with the original fear memory and is prone to fear relapse in a variety of situations.Memory reconsolidation refers to the use of cues to retrieve consolidated memories,which can become unstable and need to go through the process of new protein synthesis to become stable again.Memories can be erased,modified,or updated by drugs or behavioral methods when they are unstable.There are many animal and human studies that demonstrate that the standard retrieval-extinction paradigm,in which fear memories are first retrieved with cues,followed by extinction learning after a short interval,can prevent fear relapse.In principle,this is an intervention reconsolidation method that provides an idea for eliminating bad memories.However,the retrieval-extinction effect is limited by some boundary conditions,such as memory strength and prediction error at the time of retrieval.Because reconsolidation resistance occurs with excessively strong fear memories,this poses difficulties and challenges in translating the retrieval-extinction paradigm to the clinic.Because two competing memories will weaken each other,Experiment 1 conducted fear extinction training before standard retrieval-extinction,i.e.,extinction-retrieval-reextinction to explore whether fear relapse can be prevented by first performing extinction training to weaken strong fear memories so that they are easily disrupted by subsequent retrieval-reextinction manipulations.Seventy-two college students from Henan University were recruited and randomly divided into standard extinction group,retrieval-extinction group and retrieval-reextinction group.The experiment used a conditioned fear procedure with geometric figures as the conditioned stimulus(CS)and laboratory electric shock as the unconditioned stimulus(US)to investigate the effect of retrieval-reextinction on fear relapse with US expectancy rating,arousal,valence and skin conductance response as fear response indicators.The results revealed that only the retrieval-reextinction group was resistant to fear relapse compared to the other two groups,and that the retrieval-reextinction group had significantly lower memory strength during the retrieval phase than the retrieval-extinction group.The results of Experiment 1 showed two points: first,the retrieval-reextinction can prevent fear relapse;second,strong memories no longer resist reconsolidation after extinction.The ability to extinction learning varies between individuals,resulting in different degrees of weakened fear memory,as well as expectations for the retrieval phase.In contrast,memories of different strengths require different degrees of prediction error(i.e.,a mismatch between expected and actual outcomes)to trigger the reconsolidation process.Therefore,in experiment 2,according to the US expectancy value during memory retrieval,we divided them into two groups: retrieval US > 5 and retrieval US≤5,the former being considered to have produced an prediction error during the retrieval phase,while the latter did not.Forty-six college students from Henan University were selected,and the procedure was the same as that of the retrieval-extinction group in Experiment 1.The results revealed that state anxiety was higher in the retrieval US > 5 group,and the US expectancy value in the retrieval phase was not different from that before the first extinction,indicating that extinction learning was impaired in this group,and the first extinction training could not weaken the fear memory,so the subsequent retrieval-reextinction could not prevent fear relapse;while the retrieval US ≤ 5 group had lower state anxiety,successful extinction,and no fear relapse.The results of Experiment 2 illustrate three points:(1)anxiety level affects the effect of extinction training;(2)a prerequisite for the retrieval-reextinction effect is that the fear memory can be weakened by the previous extinction training;and(3)prediction error may be neither a sufficient nor a necessary condition for triggering memory reconsolidation.Extinction training is a learning process,and learning strategies affect the strength and persistence of extinction memories.retrieval practice enhances memory performance,avoids memory interference,and resists the damaging effects of stress on memory recall.Therefore,Experiment 3 useed the retrieval practice strategy in extinction training to enhance extinction memory and examined whether this learning strategy could help the retrieval-reextinction to inhibit fear relapse in individuals with impaired extinction.Fifty-three college students from Henan University were selected,the procedure and group were the same as in Experiment 2,except that retrieval practice were performed in the extinction training.The results found that the group with retrieval US > 5 still experienced fear relapse,while the group with retrieval US ≤ 5did not,and there was no difference in anxiety levels between the two groups.The results of Experiment 3 illustrate two points: first,retrieval practice in extinction learning does not enhance extinction memory;second,extinction effects are also affected by innate extinction learning ability.