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Forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit

Fear inhibition is markedly impaired in adolescent rodents and humans. The present experiments investigated whether this impairment is critically determined by the animal's age at the time of fear learning or their age at fear extinction. Male rats (n = 170) were tested for extinction retention...

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Autores principales: Baker, Kathryn D., Richardson, Rick
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Cold Spring Harbor Laboratory Press 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4749725/
https://www.ncbi.nlm.nih.gov/pubmed/26472643
http://dx.doi.org/10.1101/lm.039487.114
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author Baker, Kathryn D.
Richardson, Rick
author_facet Baker, Kathryn D.
Richardson, Rick
author_sort Baker, Kathryn D.
collection PubMed
description Fear inhibition is markedly impaired in adolescent rodents and humans. The present experiments investigated whether this impairment is critically determined by the animal's age at the time of fear learning or their age at fear extinction. Male rats (n = 170) were tested for extinction retention after conditioning and extinction at different ages. We examined neural correlates of impaired extinction retention by detection of phosphorylated mitogen-activated protein kinase immunoreactivity (pMAPK-IR) in several brain regions. Unexpectedly, adolescent rats exhibited good extinction retention if fear was acquired before adolescence. Further, fear acquired in adolescence could be successfully extinguished in adulthood but not within adolescence. Adolescent rats did not show extinction-induced increases in pMAPK-IR in the medial prefrontal cortex or the basolateral amygdala, or a pattern of reduced caudal central amygdala pMAPK-IR, as was observed in juveniles. This dampened prefrontal and basolateral amygdala MAPK activation following extinction in adolescence occurred even when there was no impairment in extinction retention. In contrast, only adolescent animals that exhibited impaired extinction retention showed elevated pMAPK-IR in the posterior paraventricular thalamus. These data suggest that neither the animal's age at the time of fear acquisition or extinction determines whether impaired extinction retention is exhibited. Rather, it appears that forming competing fear conditioning and extinction memories in adolescence renders this a vulnerable developmental period in which fear is difficult to inhibit. Furthermore, even under conditions that promote good extinction, the neural correlates of extinction in adolescence are different than those recruited in animals of other ages.
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spelling pubmed-47497252016-11-01 Forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit Baker, Kathryn D. Richardson, Rick Learn Mem Research Fear inhibition is markedly impaired in adolescent rodents and humans. The present experiments investigated whether this impairment is critically determined by the animal's age at the time of fear learning or their age at fear extinction. Male rats (n = 170) were tested for extinction retention after conditioning and extinction at different ages. We examined neural correlates of impaired extinction retention by detection of phosphorylated mitogen-activated protein kinase immunoreactivity (pMAPK-IR) in several brain regions. Unexpectedly, adolescent rats exhibited good extinction retention if fear was acquired before adolescence. Further, fear acquired in adolescence could be successfully extinguished in adulthood but not within adolescence. Adolescent rats did not show extinction-induced increases in pMAPK-IR in the medial prefrontal cortex or the basolateral amygdala, or a pattern of reduced caudal central amygdala pMAPK-IR, as was observed in juveniles. This dampened prefrontal and basolateral amygdala MAPK activation following extinction in adolescence occurred even when there was no impairment in extinction retention. In contrast, only adolescent animals that exhibited impaired extinction retention showed elevated pMAPK-IR in the posterior paraventricular thalamus. These data suggest that neither the animal's age at the time of fear acquisition or extinction determines whether impaired extinction retention is exhibited. Rather, it appears that forming competing fear conditioning and extinction memories in adolescence renders this a vulnerable developmental period in which fear is difficult to inhibit. Furthermore, even under conditions that promote good extinction, the neural correlates of extinction in adolescence are different than those recruited in animals of other ages. Cold Spring Harbor Laboratory Press 2015-11 /pmc/articles/PMC4749725/ /pubmed/26472643 http://dx.doi.org/10.1101/lm.039487.114 Text en © 2015 Baker and Richardson; Published by Cold Spring Harbor Laboratory Press http://creativecommons.org/licenses/by-nc/4.0/ This article is distributed exclusively by Cold Spring Harbor Laboratory Press for the first 12 months after the full-issue publication date (see http://learnmem.cshlp.org/site/misc/terms.xhtml). After 12 months, it is available under a Creative Commons License (Attribution-NonCommercial 4.0 International), as described at http://creativecommons.org/licenses/by-nc/4.0/.
spellingShingle Research
Baker, Kathryn D.
Richardson, Rick
Forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit
title Forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit
title_full Forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit
title_fullStr Forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit
title_full_unstemmed Forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit
title_short Forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit
title_sort forming competing fear learning and extinction memories in adolescence makes fear difficult to inhibit
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4749725/
https://www.ncbi.nlm.nih.gov/pubmed/26472643
http://dx.doi.org/10.1101/lm.039487.114
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