Journal: Frontiers in Behavioral Neuroscience

Article Title: Memory Reconsolidation Mediates the Updating of Hippocampal Memory Content

doi: 10.3389/fnbeh.2010.00168

Figure Lengend Snippet: Expression of BDNF (A) and Zif268 (B) proteins . Western blot analysis of dorsal hippocampal protein levels 2 h after final behavioral session in five groups. 1 – behaviorally naïve, 2 – context pre-exposure alone, 3 – immediate shock alone, 4 – context pre-exposure followed the next day by immediate shock, 5 – context pre-exposure followed the next day by re-exposure to the context alone. Learning the context representation selectively engages BDNF, whereas associating the retrieved memory of the context with the footshock upregulates Zif268 ( n = 4 per group). Data presented as mean + S.E.M. (* p < 0.05).

Article Snippet: The lack of contextual freezing in the Zif268 ASO group at the second test indicates that the previous treatment had not simply prevented the footshock updating of the contextual representation, but had disrupted the original representation itself.

Techniques: Expressing, Western Blot

Journal: Frontiers in Behavioral Neuroscience

Article Title: Memory Reconsolidation Mediates the Updating of Hippocampal Memory Content

doi: 10.3389/fnbeh.2010.00168

Figure Lengend Snippet: 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.

Article Snippet: The lack of contextual freezing in the Zif268 ASO group at the second test indicates that the previous treatment had not simply prevented the footshock updating of the contextual representation, but had disrupted the original representation itself.

Techniques: Knockdown

Journal: Frontiers in Behavioral Neuroscience

Article Title: Memory Reconsolidation Mediates the Updating of Hippocampal Memory Content

doi: 10.3389/fnbeh.2010.00168

Figure Lengend Snippet: Updating the contextual representation requires memory destabilization and reconsolidation . (A) Rats were pre-exposed to the context, and then infused into the dorsal hippocampus at the time of a subsequent immediate shock, with the updated memory assessed in a contextual fear test. Whereas knockdown of BDNF had no effect, knockdown of Zif268 and inhibition of synaptic protein degradation (β-lac) both significantly impaired contextual freezing. Zif268 knockdown no longer had an effect when delayed by 4 h after the immediate shock session ( n = 5–6 per group). (B) Retraining of the impaired rats. The groups showing an impairment were retrained the next week with further immediate shock and context fear test sessions to assess the integrity of the original contextual representation. The Zif268 knockdown group remained significantly impaired, whereas previous inhibition of synaptic protein degradation did not impair the ability of retraining to associate the immediate footshock with the intact retrieved context memory ( n = 5–6 per group). (C) Extent of context pre-exposure required to mitigate the immediate shock deficit. The normal pre-exposure used during training results in high levels of subsequent freezing compared to rats given no pre-exposure and only experiencing the immediate shock. A single 5-min short context pre-exposure failed to overcome the immediate shock deficit ( n = 4 per group). Data presented as mean + S.E.M.

Article Snippet: The lack of contextual freezing in the Zif268 ASO group at the second test indicates that the previous treatment had not simply prevented the footshock updating of the contextual representation, but had disrupted the original representation itself.

Techniques: Knockdown, Inhibition

Journal: Frontiers in Behavioral Neuroscience

Article Title: Memory Reconsolidation Mediates the Updating of Hippocampal Memory Content

doi: 10.3389/fnbeh.2010.00168

Figure Lengend Snippet: Reconsolidation is only engaged under conditions of memory updating . (A) Rats were pre-exposed to the context and then re-exposed to the context following knockdown of Zif268. No effect was observed in the subsequent context fear memory test ( n = 6 per group). (B) Rats were given a shorter initial exposure to the context, and then were re-exposed to the context. Knockdown of Zif268 impaired the subsequent ability of a footshock to be associated with the retrieved memory of the context ( n = 5–6 per group). (C) Rats were given a footshock at the end of each pre-exposure to the context, and then Zif268 was knocked down during a subsequent immediate shock session. No effect was observed in the subsequent context fear memory test ( n = 5–6 per group). Data presented as mean + S.E.M.

Article Snippet: The lack of contextual freezing in the Zif268 ASO group at the second test indicates that the previous treatment had not simply prevented the footshock updating of the contextual representation, but had disrupted the original representation itself.

Techniques: Knockdown