In humans and other mammals, memories of events are encoded by neuronal ensembles (or engrams) in the hippocampus. The mnemonic information stored in these engrams can then be used to guide future behavior, including prediction- and decision-making in dynamic environments. While some hippocampal engrams may be persistently stored, others are modified over time, suggesting that the represented memories may also be transformed. How might hippocampal engrams be modified through time? Adult hippocampal neurogenesis represents one process that continuously rewires hippocampal circuitry, presumably including stored hippocampal engrams. At intermediate stages, we propose that neurogenesis-mediated rewiring of hippocampal engram circuitry induces forgetting of specific stimulus attributes, and this less precise engram allows for generalization. At more advanced stages, we propose that neurogenesis-mediated rewiring of hippocampal engram circuitry leads to silencing of hippocampal engrams, rendering them no longer accessible by natural retrieval cues.

在人类和其他哺乳动物中，事件的记忆由海马体中的神经元集合（或印迹）编码。然后可以使用存储在这些记忆中的助记信息来指导未来的行为，包括动态环境中的预测和决策。虽然一些海马印迹可能会被永久存储，但其他一些会随着时间的推移而修改，这表明所代表的记忆也可能会被转化。海马印迹如何随着时间的推移而改变？成人海马神经发生代表了一个不断重新连接海马电路的过程，可能包括存储的海马印迹。在中间阶段，我们提出神经发生介导的海马印迹电路重新布线会导致忘记特定的刺激属性，而这种不太精确的印迹允许泛化。