Abstract
The retrieval-extinction paradigm, which disrupts the reconsolidation of fear memories in humans, is a non-invasive technique that can be used to prevent the return of fear in humans. In the present study, unconditioned stimulus revaluation was applied in the retrieval-extinction paradigm to investigate its promotion of conditioned fear extinction in the memory reconsolidation window after participants acquired conditioned fear. This experiment comprised three stages (acquisition, unconditioned stimulus revaluation, retrieval-extinction) and three methods for indexing fear (unconditioned stimulus expectancy, skin conductance response, conditioned stimulus pleasure rating). After the acquisition phase, we decreased the intensity of the unconditioned stimulus in one group (devaluation) and maintained constant for the other group (control). The results indicated that both groups exhibited similar levels of unconditioned stimulus expectancy, but the devaluation group had significantly smaller skin conductance responses and exhibited a growth in conditioned stimulus + pleasure. Thus, our findings indicate unconditioned stimulus revaluation effectively promoted the extinction of conditioned fear within the memory reconsolidation window.
Highlights
The extinction of conditioned fear has been extensively examined because these negative emotions have the potential to influence normal life in both humans and animals
The mean CS+ pleasure rating significantly increased from post-acquisition to post-extinction between the two groups, which indicated the conditioned fear was successfully extinguished in both groups, but that US-devaluation leaded to a greater extinction effect
These results suggested US-revaluation activated the reconsolidation of the fear memory upon retrieval and leaded to a progressive deconsolidation of the memory followed by the assignment of a new valence to the CS during the extinction phase; this change in valence resulted in the dissociation between US-expectancy and skin conductance response (SCR) [21]
Summary
The extinction of conditioned fear has been extensively examined because these negative emotions have the potential to influence normal life in both humans and animals. In the Ret-Ext technique, using a retrieval trial activates a consolidated fear memory, and subsequently extinction training is presented during the reconsolidation time window; as a result, the extinction training might decrease the valence of the fear stimulus and rewrite or erase the conditioned fear memory. The post-acquisition presentation of a US of decreased intensity in a subsequent test session results in the weakening of CS fear response These finding suggest the crux of Pavlovian conditioning is the association between the CS and the presentation of the US, and that the current value of US presentation is an important determinant of whether a CR is elicited by CS. We hypothesized that the fear response of the devaluation group would be significantly lower than that of the control group during the Ret-Ext technique, and the CS+ pleasure of the devaluation group would be significantly greater than that of the control group if the US-revaluation changed the conditioned fear response
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