Institut Pasteur, Université Paris Cité, Neural Circuits for Spatial Navigation and Memory, Department of Neuroscience, F-75015, Paris, France.
Sorbonne Université, Collège Doctoral, F-75005, Paris, France.
Nat Commun. 2022 Jul 15;13(1):4122. doi: 10.1038/s41467-022-31775-6.
Episodic memory formation and recall are complementary processes that rely on opposing neuronal computations in the hippocampus. How this conflict is resolved in hippocampal circuits is unclear. To address this question, we obtained in vivo whole-cell patch-clamp recordings from dentate gyrus granule cells in head-fixed mice trained to explore and distinguish between familiar and novel virtual environments. We find that granule cells consistently show a small transient depolarisation upon transition to a novel environment. This synaptic novelty signal is sensitive to local application of atropine, indicating that it depends on metabotropic acetylcholine receptors. A computational model suggests that the synaptic response to novelty may bias granule cell population activity, which can drive downstream attractor networks to a new state, favouring the switch from recall to new memory formation when faced with novelty. Such a novelty-driven switch may enable flexible encoding of new memories while preserving stable retrieval of familiar ones.
情景记忆的形成和回忆是互补的过程，它们依赖于海马体中相反的神经元计算。海马回路中如何解决这种冲突尚不清楚。为了解决这个问题，我们在经过训练以探索和区分熟悉和新颖虚拟环境的头部固定小鼠的齿状回颗粒细胞中获得了体内全细胞膜片钳记录。我们发现，颗粒细胞在转换到新环境时会一致地表现出短暂的微小去极化。这种突触新颖性信号对阿托品的局部应用敏感，表明它依赖于代谢型乙酰胆碱受体。计算模型表明，对新颖性的突触反应可能会使颗粒细胞群体活动产生偏差，这可以使下游吸引子网络进入新状态，当面对新颖性时，有利于从回忆切换到新的记忆形成。这种新颖性驱动的切换可以实现新记忆的灵活编码，同时保持对熟悉记忆的稳定检索。
