PDF(Pubmed)
Abstract：
Episodic memory is essential to navigate in a changing environment by recalling past events, creating new memories, and updating stored information from experience. Although the mechanisms for acquisition and consolidation have been profoundly studied, much less is known about memory retrieval. Hippocampal spatial representations are key for retrieval of contextually guided episodic memories. Indeed, hippocampal place cells exhibit stable location-specific activity which is thought to support contextual memory, but can also undergo remapping in response to environmental changes. It is unclear if remapping is directly related to the expression of different episodic memories. Here, using an incidental memory recognition task in rats, we showed that retrieval of a contextually guided memory is reflected by the levels of CA3 remapping, demonstrating a clear link between external cues, hippocampal remapping, and episodic memory retrieval that guides behavior. Furthermore, we describe NMDARs as key players in regulating the balance between retrieval and memory differentiation processes by controlling the reactivation of specific memory traces. While an increase in CA3 NMDAR activity boosts memory retrieval, dentate gyrus NMDAR activity enhances memory differentiation. Our results contribute to understanding how the hippocampal circuit sustains a flexible balance between memory formation and retrieval depending on the environmental cues and the internal representations of the individual. They also provide new insights into the molecular mechanisms underlying the contributions of hippocampal subregions to generate this balance.
摘要：
情景记忆对于通过回忆过去的事件在不断变化的环境中导航至关重要，创造新的回忆,并从经验中更新存储的信息。尽管收购和合并的机制已经得到了深刻的研究，对记忆检索的了解要少得多。海马空间表示是检索上下文指导的情景记忆的关键。的确,海马位置细胞表现出稳定的位置特异性活动，被认为支持上下文记忆，但也可以根据环境变化进行重新映射。目前尚不清楚重新映射是否与不同情景记忆的表达直接相关。这里,在大鼠中使用附带的记忆识别任务，我们发现，上下文引导记忆的检索是通过CA3重映射的水平来反映的，证明了外部线索之间的明确联系，海马重新定位,和引导行为的情景记忆检索。此外，我们将NMDAR描述为通过控制特定记忆痕迹的重新激活来调节检索和记忆区分过程之间平衡的关键角色。虽然CA3NMDAR活动的增加促进了记忆检索，齿状回NMDAR活性增强记忆分化。我们的结果有助于理解海马回路如何根据环境线索和个体的内部表征在记忆形成和检索之间保持灵活的平衡。它们还为海马亚区产生这种平衡的分子机制提供了新的见解。
