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Neurocircuitry of fear extinction in adult and juvenile rats

journal contribution
posted on 2018-10-01, 00:00 authored by D E Ganella, L D Nguyen, L Lee-Kardashyan, L E Kim, A G Paolini, Jee Hyun KimJee Hyun Kim
In contrast to adult rodents, juvenile rodents fail to show relapse following extinction of conditioned fear. Using different retrograde tracers injected into the infralimbic cortex (IL) and the ventral hippocampus (vHPC) in conjunction with c-Fos and parvalbumin (PV) immunochemistry, we investigated the neurocircuitry of extinction in juvenile and adult rats. Regardless of fear extinction or retrieval, juvenile rats had more c-Fos+ neurons in the basolateral amygdala (BLA) compared to adults, and showed a higher proportion of c-Fos+ IL-projecting neurons. Adult rats had more activated vHPC-projecting BLA neurons following extinction compared to retrieval, a difference not observed in juvenile rats. The number of activated vHPC- or IL-projecting BLA neurons was significantly correlated with freezing levels in adult, but not juvenile, rats. We also identified activated neurons in the BLA that simultaneously project to the IL and vHPC in the retrieval groups at both ages. This study provides novel insight into the neural process underlying extinction, especially in the juvenile period.

History

Journal

Behavioural Brain Research

Volume

351

Pagination

161 - 167

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

0166-4328

eISSN

1872-7549

Language

eng

Publication classification

C1 Refereed article in a scholarly journal