The depressive‐like state was accompanied by resistant extinction learning, which carried on for the first 2 weeks of extinction training. In particular, SDPS‐prone rats showed delayed discontinuation of responding, as compared both with controls and their resilient counterparts. This delayed incorporation of contextual updates corresponds well to overgeneralization of conditioned stimuli, as it is hypothesized in depression.31 In favor of this notion, mice exposed to repeated social defeat stress display delayed fear extinction and exhibit generalization of fear.32 Alternatively, delayed extinction performance could reflect SDPS‐induced deficits in cognitive flexibility, as observed in depressed patients.33 Impaired reversal learning, especially when it requires the inhibition of behavioral patterns driven by affective information, has been observed in the clinic.34 At the preclinical level, exposure to social defeat during adolescence is associated with deficits in reversal learning during adulthood.35 Importantly, these deficits depend on social context, as they were reversed following social housing but maintained in adults that, similar to our paradigm, remained in social isolation.35
