Department of Neuroscience, Columbia University, New York, NY, USA.
Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
Nature. 2022 Jan;601(7892):240-244. doi: 10.1038/s41586-021-04118-6. Epub 2021 Dec 8.
Associative memories guide behavioural adaptation by binding together outcome-predictive sensory stimuli. However, in a feature-rich environment, only a subset of stimuli may predict a desired outcome. How neural circuits enable behavioural adaptation by selectively and durably representing subsets of sensory stimuli that are pertinent to a specific outcome is not known. We investigated this feature selection process in the hippocampus during memory acquisition and subsequent consolidation. Two-photon calcium imaging of CA3 axonal projections to CA1 combined with simultaneous local field potential recordings revealed that CA3 projections that encode behaviourally informative sensory stimuli were selectively recruited during the memory replay events that underlie hippocampal memory consolidation. These axonal projections formed sequential assemblies that conjunctively link sensory features to spatial location and thus reward proximity. By contrast, axons encoding uninformative, peripatetic sensory cues were notably suppressed during memory replay. Thus, while the hippocampus comprehensively encodes the real-time sensory environment, it implements a flexible filtering mechanism to maximize the utility of memories destined for long-term storage. We propose that utility-dependent recruitment of sensory experience during memory consolidation is a general coding principle for associative learning.
关联记忆通过将具有预测作用的感觉刺激结合在一起，引导行为适应。然而，在一个富含特征的环境中，只有一小部分刺激可能预测到理想的结果。神经回路如何通过选择性地和持久地表示与特定结果相关的感觉刺激的子集来实现行为适应，目前尚不清楚。我们在记忆获取和随后的巩固过程中研究了海马体中的这个特征选择过程。CA3 对 CA1 的轴突投射的双光子钙成像与同时的局部场电位记录相结合，揭示了编码行为相关感觉刺激的 CA3 投射在记忆巩固的记忆重放事件中被选择性地招募。这些轴突投射形成了连续的集合，将感觉特征与空间位置以及奖励接近度联系起来。相比之下，编码无信息、游走感觉线索的轴突在记忆重放过程中明显受到抑制。因此，虽然海马体全面编码实时感觉环境，但它实施了一种灵活的过滤机制，以最大化用于长期存储的记忆的效用。我们提出，在记忆巩固过程中，根据使用情况招募感觉经验是联想学习的一般编码原则。
