Effects of recent exposure to a conditioned stimulus on extinction of Pavlovian fear conditioning

Abstract

In six experiments we studied the effects of a single re-exposure to a conditioned stimulus (CS; "retrieval trial") prior to extinction training (extinction-reconsolidation boundary) on the development of and recovery from fear extinction. A single retrieval trial prior to extinction training significantly augmented the renewal and reinstatement of extinguished responding. Augmentation of recovery was not observed if the retrieval and extinction training occurred in different contexts. These results contrast with those reported in earlier papers by Monfils and coworkers in rats and by Schiller and coworkers in humans. We suggest that these contrasting results could depend on the contrasting influences of either: (1) occasion-setting contextual associations vs. direct context-CS associations formed as a consequence of the retrieval trial or (2) discrimination vs. generalization between the circumstances of conditioning and extinction.

Figure 1.

Mean and SEM levels of freezing across the four stages of Experiment 1. Retrieval 90 min prior to extinction augmented ABA renewal of extinguished fear.

Figure 2.

Mean and SEM levels of freezing across the four stages of Experiment 2A (top panels) and Experiment 2B (bottom panels). Retrieval 90 min prior to extinction modestly reduced freezing on tests if retrieval occurred in the training context (Experiment 2A). Retrieval 90 min prior to extinction augmented ABA renewal if retrieval occurred in the extinction context (Experiment 2B).

Figure 3.

Mean and SEM levels of freezing across the four stages of Experiment 3. Retrieval 10 min prior to extinction increased freezing during extinction and tests in context B and context A.

Figure 4.

Mean and SEM levels of freezing across the four stages of Experiment 4A (top panels) and Experiment 4B (bottom panels). Retrieval 10 min prior to extinction had no significant effect on reinstatement in Experiment 4A (between-subjects reinstatement) but significantly increased reinstatement in Experiment 4B (within-subjects reinstatement).