Stress impairs retrieval of extinguished and unextinguished associations in a predictive learning task.

Recovery effects which can frequently be observed after a seemingly successful extinction procedure indicate that extinction does not lead to an erasure of the memory trace. Investigating factors which modulate the retrieval of extinction memory is highly relevant for basic science and clinical applications alike. This study investigated the effect of stress on the retrieval of extinguished and unextinguished stimulus-outcome associations in a predictive learning task. In this task, participants had to imagine being the doctor of a patient who sometimes suffers from stomach trouble after meals in his favorite restaurants. They were presented with different food stimuli while having to predict the occurrence or non-occurrence of stomach trouble. As extinction memory is modulated by context, we manipulated contextual cues so that initial acquisition of critical associations occurred in context (restaurant frame) A on day one, whereas associations were reversed in context B (extinction, day two). On the third day, participants were either stressed (exposed to the socially evaluated cold pressor task (SECPT); n=21) or subjected to a control condition (n=21) shortly before extinction memory retrieval was tested (in contexts A and B). Salivary cortisol and blood pressure measures as well as subjective ratings indicated that stress induction was successful. When retrieval of extinguished associations was tested on day three, participants' predictions reflected a renewal effect, as indicated by stronger recovery of responding in the acquisition context compared to the extinction context. Compared to controls, stressed participants showed impaired retrieval of extinguished and unextinguished associations. Contextual cues abolished the stress-induced memory impairment for unextinguished but not for extinguished associations. These findings might help to explain why stress leads to the reoccurrence of symptoms in affective disorders.