Anhedonia, the diminished drive to seek, value, and learn about rewards, is a core feature of major depressive disorder^1,2,3. The neural underpinnings of anhedonia and how this emotional state drives behaviour remain unclear. Here we investigated the neural code of anhedonia by taking advantage of the fact that when mice are exposed to traumatic social stress, susceptible animals become socially withdrawn and anhedonic, whereas others remain resilient. By performing high-density electrophysiology to record neural activity patterns in the basolateral amygdala (BLA) and ventral CA1 (vCA1), we identified neural signatures of susceptibility and resilience. When mice actively sought rewards, BLA activity in resilient mice showed robust discrimination between reward choices. By contrast, susceptible mice exhibited a rumination-like signature, in which BLA neurons encoded the intention to switch or stay on a previously chosen reward. Manipulation of vCA1 inputs to the BLA in susceptible mice rescued dysfunctional neural dynamics, amplified dynamics associated with resilience, and reversed anhedonic behaviour. Finally, when animals were at rest, the spontaneous BLA activity of susceptible mice showed a greater number of distinct neural population states. This spontaneous activity allowed us to decode group identity and to infer whether a mouse had a history of stress better than behavioural outcomes alone. This work reveals population-level neural dynamics that explain individual differences in responses to traumatic stress, and suggests that modulating vCA1–BLA inputs can enhance resilience by regulating these dynamics.

快感缺乏，即寻求、重视和学习奖励的动力减弱，是重度抑郁症的核心特征^1,2,3。快感缺乏的神经基础以及这种情绪状态如何驱动行为尚不清楚。在这里，我们利用以下事实研究了快感缺乏的神经密码：当小鼠暴露于创伤性社交压力时，易感动物会变得社交退缩和快感缺乏，而其他动物则保持弹性。通过进行高密度电生理学来记录基底外侧杏仁核 （BLA） 和腹侧 CA1 （vCA1） 的神经活动模式，我们确定了易感性和弹性的神经特征。当小鼠积极寻求奖励时，弹性小鼠的 BLA 活性在奖励选择之间表现出强大的区分力。相比之下，易感小鼠表现出类似反刍的特征，其中 BLA 神经元编码了转换或留在先前选择的奖励的意图。在易感小鼠中操纵 vCA1 对 BLA 的输入挽救了功能失调的神经动力学，放大了与恢复力相关的动力学，并逆转了快感缺乏行为。最后，当动物休息时，易感小鼠的自发 BLA 活动表现出更多不同的神经种群状态。这种自发的活动使我们能够解码群体身份，并推断小鼠是否比单独的行为结果更有压力史。这项工作揭示了群体水平的神经动力学，解释了对创伤应激反应的个体差异，并表明调节 vCA1-BLA 输入可以通过调节这些动力学来增强弹性。