斯坦福大学医学院Lisa M. Giocomo小组在研究中取得进展。他们研制了一个灵活的海马体群体编码相对于奖励的经验。该研究于2025年6月11日发表于国际一流学术期刊《自然—神经科学》杂志上。

为了测试这种可能性，课题组人员对小鼠在虚拟环境中导航时的海马CA1进行了双光子成像，这些虚拟环境具有变化的隐藏奖励位置。研究团队发现，当奖励移动时，神经元亚群将它们的放电场更新到与奖励相同的相对位置，构建跨越整个任务的行为时间尺度序列。在学习过程中，随着额外的神经元被招募，这种奖励相关表征变得更加机器人化，奖励相关放电的变化通常先于奖励重新定位后的行为适应。同时，空间环境代码是通过一个并行的、动态的亚种群而不是通过专门的细胞类来维持的。这些发现揭示了海马体在放大行为相关信息的同时如何灵活地编码经验的多个方面。

据介绍，为了强化奖励行为，奖励前和奖励后的事件必须被记住。海马体位置细胞活动跨越空间和非空间事件，但海马体活动是否编码与奖励相关的整个事件序列尚不清楚。

附：英文原文

Title: A flexible hippocampal population code for experience relative to reward

Author: Sosa, Marielena, Plitt, Mark H., Giocomo, Lisa M.

Issue&Volume: 2025-06-11

Abstract: To reinforce rewarding behaviors, events leading up to and following rewards must be remembered. Hippocampal place cell activity spans spatial and non-spatial episodes, but whether hippocampal activity encodes entire sequences of events relative to reward is unknown. Here, to test this possibility, we performed two-photon imaging of hippocampal CA1 as mice navigated virtual environments with changing hidden reward locations. We found that when the reward moved, a subpopulation of neurons updated their firing fields to the same relative position with respect to reward, constructing behavioral timescale sequences spanning the entire task. Over learning, this reward-relative representation became more robust as additional neurons were recruited, and changes in reward-relative firing often preceded behavioral adaptations following reward relocation. Concurrently, the spatial environment code was maintained through a parallel, dynamic subpopulation rather than through dedicated cell classes. These findings reveal how hippocampal ensembles flexibly encode multiple aspects of experience while amplifying behaviorally relevant information.

DOI: 10.1038/s41593-025-01985-4

Source: https://www.nature.com/articles/s41593-025-01985-4