人类海马CA1的前向再激活支持重复学习，并在衰老大脑中保留
Forward reactivation in human hippocampal CA1 supports repetition learning and is preserved in the aging brain
重复是强化情景记忆的基本机制，然而再暴露过程中所参与的神经计算仍存争议。相互竞争的解释将重复相关的收益归因于对先前事件的回溯性重现，或归因于前瞻性地利用习得结构来预期后续内容。我们在一生队列（N = 418，年龄36–100岁）中使用高分辨率功能MRI和表征相似性分析，在参与者两次编码两个固定的人脸-姓名配对序列时追踪海马表征，并按方向、距离和序列解析再激活。在重复编码期间，CA1和CA2/3/DG表征自发地预期了紧邻的下一个状态，且并非由明确的任务要求所驱动。前向（而非后向）再激活预测了重复相关的收益，且未显示出可检测的年龄依赖性。在控制其他内侧颞叶区域的再激活后，只有CA1的前向再激活预测了记忆收益。因此，重复学习是一种主动的、时间上局部的前瞻性计算，具有独特的CA1贡献，且这种贡献似乎能保持到高龄。
把重复学习中的海马再激活按方向、距离和序列拆开，为前瞻性再激活与情景记忆增益的关系提供了大样本证据。
Repetition is a fundamental mechanism for strengthening episodic memory, yet the neural computations engaged during re-exposure remain disputed. Competing accounts attribute repetition-related gains either to retrospective reinstatement of prior events or to the prospective use of learned structure to anticipate what comes next. Using high-resolution functional MRI and representational similarity analysis in a lifespan cohort (N = 418, ages 36 -100), we tracked hippocampal representations as participants twice encoded two fixed sequences of face-name pairs, resolving reactivation by direction, distance and sequence. During repeated encoding, CA1 and CA2/3/DG representations spontaneously anticipated immediate next states, unprompted by explicit task demands. Forward, but not backward, reactivation predicted repetition-related gains, and showed no detectable age dependence. Only CA1 forward reactivation predicted memory gains after accounting for reactivation in other medial temporal lobe regions. Repetition learning is thus an active, temporally local prospective computation with a distinctive CA1 contribution that appears preserved well into old age.
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来源：bioRxiv · Neuroscience · biorxiv.org