Memories are thought to be stored in neuronal ensembles referred to as engrams. Studies have suggested that when two memories occur in quick succession, a proportion of their engrams overlap and the memories become linked (in a process known as prospective linking) while maintaining their individual identities. In this Review, we summarize the key principles of memory linking through engram overlap, as revealed by experimental and modelling studies. We describe evidence of the involvement of synaptic memory substrates, spine clustering and non-linear neuronal capacities in prospective linking, and suggest a dynamic somato-synaptic model, in which memories are shared between neurons yet remain separable through distinct dendritic and synaptic allocation patterns. We also bring into focus retrospective linking, in which memories become associated after encoding via offline reactivation, and discuss key temporal and mechanistic differences between prospective and retrospective linking, as well as the potential differences in their cognitive outcomes.

记忆被认为存储在称为印迹的神经元集合中。研究表明，当两个记忆快速连续出现时，它们的印迹的一部分会重叠，并且记忆会被链接起来（在称为前瞻性链接的过程中），同时保持各自的身份。在这篇综述中，我们总结了实验和建模研究揭示的通过印迹重叠进行记忆链接的关键原理。我们描述了突触记忆基质、棘簇和非线性神经元能力参与前瞻性连接的证据，并提出了一种动态体细胞突触模型，其中记忆在神经元之间共享，但通过不同的树突和突触分配模式保持可分离。我们还重点关注回顾性链接，其中记忆在通过离线重新激活编码后变得相关，并讨论了前瞻性链接和回顾性链接之间的关键时间和机制差异，以及它们认知结果的潜在差异。