Exploring the boundaries of post-retrieval extinction in healthy and anxious individuals
Acunzo, Maria Alexandra Kredlow
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Human and non-human animal studies indicate that the reconsolidation of conditioned fear memories can be interrupted, and return of fear attenuated, using a paradigm of memory retrieval coupled with extinction called post-retrieval extinction (PRE). This series of studies examined the efficacy of PRE for attenuating the return of fear in healthy and anxious individuals in order to inform translation of PRE to the clinic. Study 1 was a meta-analysis of 16 comparisons of PRE versus extinction in healthy human participants. My hypothesis that PRE would be more efficacious than extinction in attenuating the return of fear was supported (effect size g = 0.40). This effect was moderated by factors potentially related to memory strength. Accordingly, in Study 2, I tested a strategy to strengthen fear memories using a compound unconditioned stimulus for use in a subsequent study of PRE (Study 3). I hypothesized that the use of a compound unconditioned stimulus would improve rates of acquisition and differential conditioning levels in healthy participants (N=143, M(SD) age=23.0 (9.8), 59% female). My results confirmed that the use of a compound unconditioned stimulus enhanced rates of acquisition, but contrary to my hypothesis, did not enhance differential conditioning levels among those meeting threshold values for conditioning. In Study 3, I tested the relative efficacy of PRE in 49 healthy and 43 anxious participants (M(SD) age=23.0 (8.0), 71% female) who received either one day of acquisition followed by PRE or extinction, or three days of acquisition followed by PRE. I hypothesized that PRE would be more efficacious than extinction in attenuating the reinstatement of fear for memories conditioned over one day, but not for stronger fear memories conditioned over three days. Contrary to my hypothesis, no effect of PRE was observed on reinstatement of fear for participants who received one day of acquisition. Furthermore, PRE was not more beneficial for anxious participants who received one day versus three days of acquisition. In sum, the PRE effect size from this study was near zero and at the 11th percentile of those observed by meta-analysis; future research should continue to examine moderators of PRE effects.