Context Fear Learning And Renewal Of Extinguished Fear Are Dissociated In Juvenile Female Rats

Extinction is the decrease in emotion to a cue that was previously associated with an emotionally significant event. It involves repeated presentation of the cue without any consequences. In adult animals, extinguished fear to a cue can return if the cue is presented in a different environment/context to where extinction occurred, referred to as renewal. We have previously reported that developing female, but not male, rats show renewal. This study investigates whether the ability of developing female rats to show renewal is related to their ability in fear conditioning to the context. Additionally, facilitation of context conditioning by weaning previously shown in male rats was tested in developing female rats. In experiment 1, postnatal day 25 (P25) and P18 female rats showed renewal. P25 rats show more fear overall, suggesting a weaker extinction recall in this age. Experiment 2 tested context- and cue-elicited fear either immediately or 24 hr following conditioning. At the immediate test, P18 rats showed less context-fear compared with P25 rats. All rats showed low levels of context-fear at the 24 hr test. There were no age differences in cued fear. Weaning at P21 did not affect context or cue memory in P25 female rats. These findings suggest that the ability to form contextual fear memory is unrelated to the expression of renewal in juvenile female rats.