Cellular and systems mechanisms of memory strength as a constraint on auditory fear reconsolidation (Nat Neurosci, 2009, 12:905-912)

報告日期: 2009/12/18
報告時間: 15:10/16:00
報告學生: 張智華
講評老師: 簡伯武
附件下載:

http://basicmed.med.ncku.edu.tw/admin/up_img/981218-1.pdf

Cellular and systems mechanisms of memory strength as a constraint on auditory fear reconsolidation

 

Szu-Han Wang, Lucas de Oliveira Alvares & Karim Nader

Nat Neurosci 12, 905 - 912 (2009).

 

Speaker: Chang, Chih-Hua (張智華)

Commentator: Gean, Po-Wu, Ph.D.(簡伯武 老師)

Time: 2009.12.18. 15:10 – 16:00

Place: Room 602

 

Abstract

New memories are stabilized after an initial learning experience by a process called consolidation. It is thought that once consolidated, memories remain in a fixed, stable state that is insensitive to further amnesic challenge. Moreover, the previous studies showed that retrieval of a memory trace can induce an additional labile phase that requires an active process to stabilize memory after retrieval. This process is called reconsolidation. However, reconsolidation theories are controversial. Conflicting findings on the existence of reconsolidation after retrieval have led to a discussion of the limiting factors. Such experimental conditions under which reconsolidation does not occur are defined as boundary conditions. A number of boundary conditions have been suggested, such as memory age, training strength and the length of reactivation. The rules, however, are not always simple, and boundary conditions also interact. For this reason, identifying the molecular mechanisms that change as a result of age, memory strength and the length of reactivation will allow for an objective determination of what underlies a boundary condition of memory reconsolidation. In this study, the authors found that strong auditory fear memories initially did not undergo reconsolidation but did over time, suggesting that the boundary condition induced by strong training is transient. Moreover, NR2B expression in the lateral and basal amygdale (LBA) was reduced under conditions when memories did not undergo reconsolidation and was normal when memories underwent reconsolidation. And pre-training dorsal hippocampus lesions cause strong fear memories to undergo reconsolidation in the LBA, suggesting dorsal hippocampus is necessary for the boundary conditions of the strong auditory fear memories in the LBA.

 

References 1-2

1.  Ben Mamou, C., Gamache, K. & Nader, K. NMDA receptors are critical for unleashing consolidated auditory fear memories. Nat Neurosci 9, 1237-1239 (2006).

2.  Tronson, N.C. & Taylor, J.R. Molecular mechanisms of memory reconsolidation. Nat Rev Neurosci 8, 262-275 (2007).