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Memory reconsolidation mediates the updating of hippocampal memory content.

Lee JL - Front Behav Neurosci (2010)

Bottom Line: Moreover, memory reactivation is a necessary step in modifying memory content, as inhibition of hippocampal synaptic protein degradation also prevented the footshock-mediated memory modification.Finally, dorsal hippocampal knockdown of Zif268 impaired the reconsolidation of the pure contextual memory only under conditions of weak context memory training, as well as failing to disrupt contextual freezing when a strong contextual fear memory is reactivated by further conditioning.Therefore, an adaptive function of the reactivation and reconsolidation process is to enable the updating of memory content.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, University of Birmingham Birmingham, UK. j.l.c.lee@bham.ac.uk

ABSTRACT
The retrieval or reactivation of a memory places it into a labile state, requiring a process of reconsolidation to restabilize it. This retrieval-induced plasticity is a potential mechanism for the modification of the existing memory. Following previous data supportive of a functional role for memory reconsolidation in the modification of memory strength, here I show that hippocampal memory reconsolidation also supports the updating of contextual memory content. Using a procedure that separates the learning of pure context from footshock-motivated contextual fear learning, I demonstrate doubly dissociable hippocampal mechanisms of initial context learning and subsequent updating of the neutral contextual representation to incorporate the footshock. Contextual memory consolidation was dependent upon BDNF expression in the dorsal hippocampus, whereas the footshock modification of the contextual representation required the expression of Zif268. These mechanisms match those previously shown to be selectively involved in hippocampal memory consolidation and reconsolidation, respectively. Moreover, memory reactivation is a necessary step in modifying memory content, as inhibition of hippocampal synaptic protein degradation also prevented the footshock-mediated memory modification. Finally, dorsal hippocampal knockdown of Zif268 impaired the reconsolidation of the pure contextual memory only under conditions of weak context memory training, as well as failing to disrupt contextual freezing when a strong contextual fear memory is reactivated by further conditioning. Therefore, an adaptive function of the reactivation and reconsolidation process is to enable the updating of memory content.

No MeSH data available.


Acquisition of the contextual representation requires BDNF, but not Zif268. Knockdown of BDNF, but not Zif268, in the dorsal hippocampus during context pre-exposure impaired the subsequent ability of rats to retrieve the memory of the context in order to associate it with the footshock, and hence BDNF knockdown rats froze significantly less at the context fear memory test (n = 5–6 per group). Data presented as mean + S.E.M.
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Figure 3: Acquisition of the contextual representation requires BDNF, but not Zif268. Knockdown of BDNF, but not Zif268, in the dorsal hippocampus during context pre-exposure impaired the subsequent ability of rats to retrieve the memory of the context in order to associate it with the footshock, and hence BDNF knockdown rats froze significantly less at the context fear memory test (n = 5–6 per group). Data presented as mean + S.E.M.

Mentions: Rats were infused into the dorsal hippocampus with BDNF or Zif268 ASO/MSO prior to context pre-exposure (Figure 3). Impairing hippocampal memory consolidation by infusion of BDNF ASO significantly impaired subsequent contextual freezing (F(1,10) = 5.67, p = 0.039). In contrast, infusion of Zif268 ASO, which impairs hippocampal memory reconsolidation, had no effect relative to control missense infusions (F(1,8) = 0.271, p = 0.617). Therefore, the acquisition and consolidation of the contextual representation recruits selectively the same functional mechanism as for contextual fear memory consolidation.


Memory reconsolidation mediates the updating of hippocampal memory content.

Lee JL - Front Behav Neurosci (2010)

Acquisition of the contextual representation requires BDNF, but not Zif268. Knockdown of BDNF, but not Zif268, in the dorsal hippocampus during context pre-exposure impaired the subsequent ability of rats to retrieve the memory of the context in order to associate it with the footshock, and hence BDNF knockdown rats froze significantly less at the context fear memory test (n = 5–6 per group). Data presented as mean + S.E.M.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2991235&req=5

Figure 3: Acquisition of the contextual representation requires BDNF, but not Zif268. Knockdown of BDNF, but not Zif268, in the dorsal hippocampus during context pre-exposure impaired the subsequent ability of rats to retrieve the memory of the context in order to associate it with the footshock, and hence BDNF knockdown rats froze significantly less at the context fear memory test (n = 5–6 per group). Data presented as mean + S.E.M.
Mentions: Rats were infused into the dorsal hippocampus with BDNF or Zif268 ASO/MSO prior to context pre-exposure (Figure 3). Impairing hippocampal memory consolidation by infusion of BDNF ASO significantly impaired subsequent contextual freezing (F(1,10) = 5.67, p = 0.039). In contrast, infusion of Zif268 ASO, which impairs hippocampal memory reconsolidation, had no effect relative to control missense infusions (F(1,8) = 0.271, p = 0.617). Therefore, the acquisition and consolidation of the contextual representation recruits selectively the same functional mechanism as for contextual fear memory consolidation.

Bottom Line: Moreover, memory reactivation is a necessary step in modifying memory content, as inhibition of hippocampal synaptic protein degradation also prevented the footshock-mediated memory modification.Finally, dorsal hippocampal knockdown of Zif268 impaired the reconsolidation of the pure contextual memory only under conditions of weak context memory training, as well as failing to disrupt contextual freezing when a strong contextual fear memory is reactivated by further conditioning.Therefore, an adaptive function of the reactivation and reconsolidation process is to enable the updating of memory content.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, University of Birmingham Birmingham, UK. j.l.c.lee@bham.ac.uk

ABSTRACT
The retrieval or reactivation of a memory places it into a labile state, requiring a process of reconsolidation to restabilize it. This retrieval-induced plasticity is a potential mechanism for the modification of the existing memory. Following previous data supportive of a functional role for memory reconsolidation in the modification of memory strength, here I show that hippocampal memory reconsolidation also supports the updating of contextual memory content. Using a procedure that separates the learning of pure context from footshock-motivated contextual fear learning, I demonstrate doubly dissociable hippocampal mechanisms of initial context learning and subsequent updating of the neutral contextual representation to incorporate the footshock. Contextual memory consolidation was dependent upon BDNF expression in the dorsal hippocampus, whereas the footshock modification of the contextual representation required the expression of Zif268. These mechanisms match those previously shown to be selectively involved in hippocampal memory consolidation and reconsolidation, respectively. Moreover, memory reactivation is a necessary step in modifying memory content, as inhibition of hippocampal synaptic protein degradation also prevented the footshock-mediated memory modification. Finally, dorsal hippocampal knockdown of Zif268 impaired the reconsolidation of the pure contextual memory only under conditions of weak context memory training, as well as failing to disrupt contextual freezing when a strong contextual fear memory is reactivated by further conditioning. Therefore, an adaptive function of the reactivation and reconsolidation process is to enable the updating of memory content.

No MeSH data available.