Learning differentially shapes prefrontal and hippocampal activity

The ability to use sensory cues to inform goal directed actions is a critical component of behavior. To study how sounds guide anticipatory licking during classical conditioning, we employed high-density electrophysiological recordings from the hippocampal CA1 area and the prefrontal cortex (PFC) in mice. CA1 and PFC neurons undergo distinct learning dependent changes at the single cell level and maintain representations of cue identity at the population level. In addition, reactivation of task-related neuronal assemblies during hippocampal awake Sharp-Wave Ripples (aSWR) changed within individual sessions in CA1 and over the course of multiple sessions in PFC. Despite both areas being highly engaged and synchronized during the task, we found no evidence for coordinated single cell or assembly activity during conditioning trials or aSWR. Taken together, our findings support the notion that persistent firing and reactivation of task-related neural activity patterns in CA1 and PFC support learning during classical conditioning.

利用感觉线索指引目标导向行为的能力，是行为活动的关键组成部分。为探究声音如何在经典条件反射（classical conditioning）过程中引导预期舔舐行为，我们对小鼠的海马CA1区与前额叶皮层（prefrontal cortex, PFC）进行了高密度脑电生理记录。研究发现，CA1区与PFC神经元会在单细胞层面呈现出依赖于学习过程的特异性变化，并在群体层面保留对线索特征的表征信息。此外，在海马觉醒状态尖波涟漪（awake Sharp-Wave Ripples, aSWR）期间，任务相关神经元集群的再激活现象，在CA1区的单次实验会话内会发生动态变化，而在PFC中则会在多轮实验会话的进程中产生改变。尽管两个脑区在任务执行过程中均处于高度激活且同步的状态，但我们并未发现任何证据表明，在条件反射试次或aSWR期间存在单细胞或神经元集群的协同活动。综上，我们的研究结果支持这一观点：CA1区与PFC中任务相关神经活动模式的持续放电与再激活，能够为经典条件反射过程中的学习过程提供支撑。