Hippocampal CA3 is central to memory formation and retrieval. Although various network mechanisms have been proposed, direct evidence is lacking. Using intracellular V_m recordings and optogenetic manipulations in behaving mice, we found that CA3 place-field activity is produced by a symmetric form of behavioral timescale synaptic plasticity (BTSP) at recurrent synapses among CA3 pyramidal neurons but not at synapses from the dentate gyrus (DG). Additional manipulations revealed that excitatory input from the entorhinal cortex (EC) but not the DG was required to update place cell activity based on the animal’s movement. These data were captured by a computational model that used BTSP and an external updating input to produce attractor dynamics under online learning conditions. Theoretical analyses further highlight the superior memory storage capacity of such networks, especially when dealing with correlated input patterns. This evidence elucidates the cellular and circuit mechanisms of learning and memory formation in the hippocampus.

中文翻译：

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海马区 CA3 支持记忆的神经元动力学机制


海马 CA3 是记忆形成和检索的核心。尽管已经提出了各种网络机制，但缺乏直接证据。在行为小鼠中使用细胞内 V_m 记录和光遗传学操作，我们发现 CA3 位置场活动是由对称形式的行为时间尺度突触可塑性 （BTSP） 在 CA3 锥体神经元的重复突触处产生，而不是在齿状回 （DG） 的突触处产生。其他操作表明，需要来自内嗅皮层 （EC） 而不是 DG 的兴奋性输入来根据动物的运动更新位置细胞活动。这些数据由一个计算模型捕获，该模型使用 BTSP 和外部更新输入在在线学习条件下产生吸引子动力学。理论分析进一步强调了此类网络的卓越内存存储容量，尤其是在处理相关输入模式时。该证据阐明了海马体中学习和记忆形成的细胞和回路机制。