Dissociated roles of dorsal and ventral hippocampus in recall and extinction of conditioned fear in male and female juvenile rats.

Dissociated roles of dorsal and ventral hippocampus in recall and extinction of conditioned fear in male and female juvenile rats. Exp Neurol. 2020 Apr 10;:113306 Authors: Park CHJ, Ganella DE, Perry CJ, Kim JH Abstract Reduction of conditioned fear expression by extinction underlies cue exposure therapies that treat anxiety disorders. Extinction is context-specific. Renewal, for example, is the relapse of extinguished fear when subjects are tested in a different context to extinction. This context-specificity is developmentally regulated and sex-dependent, with renewal being observed in postnatal day (P) 18 female, but not in male, rats. Given the hippocampus (HPC) is critical for context-specific extinction in adult rodents, we investigated dorsal or ventral hippocampus (dHPC or vHPC) involvement in context-specific extinction in P18 male and female rats. We microinfused muscimol (GABAA agonist) to inactivate either structure before extinction, then tested rats for renewal the next day. Regardless of sex, dHPC inactivation accelerated extinction acquisition, while vHPC inactivation reduced fear expression during extinction and impaired extinction recall. Consistent with previous findings, renewal was observed in females but not in males. Surprisingly, inactivation of dHPC or vHPC had no effects on renewal in either sex, indicating that the hippocampus does not play a critical role in context-dependent extinction learning in juvenil...
Source: Experimental Neurology - Category: Neurology Authors: Tags: Exp Neurol Source Type: research