Testing the Memory Reconsolidation Hypothesis in a Fear Extinction Paradigm: the Effects of Ecological and Arbitrary Stimuli

Abstract

Various studies demonstrated that extinction training taking place shortly after the activation of the acquired fear could weaken the conditioned fear. The procedure is called post-retrieval extinction (PRE). However, from the time it emerged, it has suffered from inconsistencies in the ability of researchers to replicate the seemingly established effects. Extant literature implies that conditioned fear might be differentially sensitive to the nature of conditioned stimuli (CS) used. The aim of the present study, therefore, is threefold. First, we aimed to replicate Schiller et al. (Nature, 463, 49-53.2010) procedure in which the PRE had produced positive results with arbitrary CSs only. Also, we examined the PRE as a function of CS type (ecological-fear-relevant (images of spider and snake) vs. arbitrary (images of yellow and blue circles)). Finally, we aimed to investigate the long-term effects of the PRE (i.e., 24 h, 15 d, and 3 mo). The study consisted of acquisition, re-activation and extinction, and re-extinction phases. Dependent measure was the recovery of fear responses as indexed by the skin conductance responses (SCRs) and arousal ratings of the participants at the last trial of the extinction and the first trial of the re-extinction. All groups showed significant acquisition and extinction patterns, compared to the other two groups (i.e., 6 h after the activating CS and without an activating stimulus) only the group that undertook extinction trials 10 min after the activating CS showed a sustained extinction. Thus, our findings provided further evidence for the robustness of the PRE paradigm in preventing the recovery of extinguished fears behaviorally, both with ecological and arbitrary stimuli.