The hippocampus is thought to mediate episodic memory through the instantiation and reinstatement of context-specific cognitive maps. However, recent longitudinal experiments have challenged this view, reporting that most hippocampal cells change their tuning properties over days even in the same environment. Often referred to as representational drift, these dynamics raise multiple questions about the representational capacity and content of the hippocampal code. One such question is whether and how these dynamics impact the contextual code. To address this, here we imaged large CA1 populations over more than a month of daily experience as freely behaving mice participated in an extended geometric morph paradigm. We find that long-timescale changes in population activity occurred orthogonally to the representation of context in network space, allowing for consistent readout of contextual information across weeks. Together, these results demonstrate that long-timescale changes to the CA1 spatial code preserve the relative structure of contextual representation.

中文翻译：

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CA1 空间代码的长期动态保留了上下文表示的相对结构

海马体被认为通过情境特定认知地图的实例化和恢复来调节情景记忆。然而，最近的纵向实验对这一观点提出了挑战，报告称即使在相同的环境中，大多数海马细胞也会在几天内改变其调谐特性。通常称为代表性漂移，这些动态引发了关于海马代码的表示能力和内容的多个问题。其中一个问题是这些动态是否以及如何影响上下文代码。为了解决这个问题，我们在一个多月的日常经验中对大型 CA1 种群进行了成像，因为自由行为的小鼠参与了扩展的几何变形范式。我们发现，人口活动的长期变化与网络空间中的上下文表示正交，允许在几周内一致地读取上下文信息。总之，这些结果表明 CA1 空间代码的长期变化保留了上下文表示的相对结构。