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On the transition from reconsolidation to extinction of contextual fear memories.
Learn Mem. 2017 09; 24(9):392-399.LM

Abstract

Retrieval of an associative memory can lead to different phenomena. Brief reexposure sessions tend to trigger reconsolidation, whereas more extended ones trigger extinction. In appetitive and fear cued Pavlovian memories, an intermediate "null point" period has been observed where neither process seems to be engaged. Here we investigated whether this phenomenon extends to contextual fear memory. Adult rats were subjected to a contextual fear conditioning paradigm, reexposed to the context 2 d later for 3, 5, 10, 20, or 30 min, with immediate injections of MK-801 or saline following reexposure, and tested on the following day. We observed a significant effect of MK-801 with the 3- and 30-min sessions, impairing reconsolidation and extinction, respectively. However, it did not have significant effects with 5-, 10-, or 20-min sessions, even though freezing decreased from reexposure to test. Further analyses indicated that this is not likely to be due to a variable transition point at the population level. In conclusion, the results show that in contextual fear memories there is a genuine "null point" between the parameters that induce reconsolidation and extinction, as defined by the effects of MK-801, although NMDA receptor-independent decreases in freezing can still occur in these conditions.

Authors+Show Affiliations

School of Psychology, University of Birmingham, Birmingham, B15 2TT, United Kingdom.School of Psychology, University of Birmingham, Birmingham, B15 2TT, United Kingdom.Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, 21941-902, Brazil.School of Psychology, University of Birmingham, Birmingham, B15 2TT, United Kingdom.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28814464

Citation

Cassini, Lindsey F., et al. "On the Transition From Reconsolidation to Extinction of Contextual Fear Memories." Learning & Memory (Cold Spring Harbor, N.Y.), vol. 24, no. 9, 2017, pp. 392-399.
Cassini LF, Flavell CR, Amaral OB, et al. On the transition from reconsolidation to extinction of contextual fear memories. Learn Mem. 2017;24(9):392-399.
Cassini, L. F., Flavell, C. R., Amaral, O. B., & Lee, J. L. C. (2017). On the transition from reconsolidation to extinction of contextual fear memories. Learning & Memory (Cold Spring Harbor, N.Y.), 24(9), 392-399. https://doi.org/10.1101/lm.045724.117
Cassini LF, et al. On the Transition From Reconsolidation to Extinction of Contextual Fear Memories. Learn Mem. 2017;24(9):392-399. PubMed PMID: 28814464.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - On the transition from reconsolidation to extinction of contextual fear memories. AU - Cassini,Lindsey F, AU - Flavell,Charlotte R, AU - Amaral,Olavo B, AU - Lee,Jonathan L C, Y1 - 2017/08/16/ PY - 2017/04/12/received PY - 2017/06/29/accepted PY - 2017/8/18/entrez PY - 2017/8/18/pubmed PY - 2018/5/3/medline SP - 392 EP - 399 JF - Learning & memory (Cold Spring Harbor, N.Y.) JO - Learn Mem VL - 24 IS - 9 N2 - Retrieval of an associative memory can lead to different phenomena. Brief reexposure sessions tend to trigger reconsolidation, whereas more extended ones trigger extinction. In appetitive and fear cued Pavlovian memories, an intermediate "null point" period has been observed where neither process seems to be engaged. Here we investigated whether this phenomenon extends to contextual fear memory. Adult rats were subjected to a contextual fear conditioning paradigm, reexposed to the context 2 d later for 3, 5, 10, 20, or 30 min, with immediate injections of MK-801 or saline following reexposure, and tested on the following day. We observed a significant effect of MK-801 with the 3- and 30-min sessions, impairing reconsolidation and extinction, respectively. However, it did not have significant effects with 5-, 10-, or 20-min sessions, even though freezing decreased from reexposure to test. Further analyses indicated that this is not likely to be due to a variable transition point at the population level. In conclusion, the results show that in contextual fear memories there is a genuine "null point" between the parameters that induce reconsolidation and extinction, as defined by the effects of MK-801, although NMDA receptor-independent decreases in freezing can still occur in these conditions. SN - 1549-5485 UR - https://www.unboundmedicine.com/medline/citation/28814464/On_the_transition_from_reconsolidation_to_extinction_of_contextual_fear_memories_ L2 - http://learnmem.cshlp.org/lookup/pmidlookup?view=long&pmid=28814464 DB - PRIME DP - Unbound Medicine ER -