Reactivations of emotional memory in the hippocampus–amygdala system during sleep

The consolidation of context-dependent emotional memory requires communication between the hippocampus and the basolateral amygdala (BLA), but the mechanisms of this process are unknown. We recorded neuronal ensembles in the hippocampus and BLA while rats learned the location of an aversive air puff on a linear track, as well as during sleep before and after training. We found coordinated reactivations between the hippocampus and the BLA during non-REM sleep following training. These reactivations peaked during hippocampal sharp wave–ripples (SPW-Rs) and involved a subgroup of BLA cells positively modulated during hippocampal SPW-Rs. Notably, reactivation was stronger for the hippocampus–BLA correlation patterns representing the run direction that involved the air puff than for the 'safe' direction. These findings suggest that consolidation of contextual emotional memory occurs during ripple-reactivation of hippocampus–amygdala circuits.

情境依赖型情绪记忆的巩固依赖于海马体与基底外侧杏仁核（basolateral amygdala, BLA）之间的信号交流，但该过程的具体机制尚不明确。我们在大鼠于线性轨道上习得厌恶性气流刺激的定位任务过程中，以及训练前后的睡眠阶段内，同步记录了海马体与基底外侧杏仁核内的神经元集群活动。研究发现，训练后的非快速眼动睡眠阶段内，海马体与基底外侧杏仁核之间存在协同再激活现象。这类再激活在海马体尖波-涟漪（sharp wave-ripples, SPW-Rs）事件期间达到峰值，且涉及一类在海马体尖波-涟漪事件期间被正向调制的基底外侧杏仁核细胞亚群。值得注意的是，相较于代表“安全”奔跑方向的关联模式，代表存在气流刺激的奔跑方向的海马体-基底外侧杏仁核相关模式所对应的再激活强度更高。上述研究结果表明，情境依赖型情绪记忆的巩固过程，发生于海马体-杏仁核环路的涟漪再激活阶段。