Context controls the ability of unconditional stimulus deflation to mitigate fear relapse

Our lab, and others, have recently demonstrated that fear behavior can be weakened following fear acquisition with a footshock unconditional stimulus by presenting a weaker version of that footshock, a phenomenon termed 'unconditional stimulus deflation' or US deflation. Unlike extinction, US deflation putatively functions by modifying the original fear memory, potentially making it a more effective candidate for reducing fear and preventing relapse effects often observed following extinction. Here, we adapted our contextual fear US deflation procedure to a delay conditioning paradigm in order to examine common relapse phenomena: renewal and reinstatement. We found that while ABA renewal and reinstatement were unaffected by US deflation, AAB renewal was reduced by US deflation. Our results support similar work in suggesting that prevention of relapse is at least partially dependent on deflation occurring in the same context as training when using a delay fear conditioning procedure.