PDF(Pubmed)
Abstract：
Consolidation of initially encoded hippocampal representations in the neocortex through reactivation is crucial for long-term memory formation and is facilitated by the coordination of hippocampal sharp-wave ripples (SWRs) with cortical slow and spindle oscillations during non-REM sleep. Recent evidence suggests that high-frequency cortical ripples can also coordinate with hippocampal SWRs in support of consolidation; however, the contribution of cortical ripples to reactivation remains unclear. We used high-density, continuous recordings in the hippocampus (area CA1) and prefrontal cortex (PFC) over the course of spatial learning and show that independent PFC ripples dissociated from SWRs are prevalent in NREM sleep and predominantly suppress hippocampal activity. PFC ripples paradoxically mediate top-down suppression of hippocampal reactivation rather than coordination, and this suppression is stronger for assemblies that are reactivated during coordinated CA1-PFC ripples for consolidation of recent experiences. Further, we show non-canonical, serial coordination of independent cortical ripples with slow and spindle oscillations, which are known signatures of memory consolidation. These results establish a role for prefrontal cortical ripples in top-down regulation of behaviorally relevant hippocampal representations during consolidation.
摘要：
通过重新激活在新皮质中巩固最初编码的海马表征对于长期记忆形成至关重要，并且在非REM睡眠期间，海马锐波波纹（SWRs）与皮质缓慢和纺锤体振荡的协调也促进了这种整合。最近的证据表明，高频皮质波纹也可以与海马SWRs协调，以支持巩固;然而，皮质波纹对再激活的贡献尚不清楚.我们使用了高密度，在空间学习过程中，海马（CA1区）和前额叶皮层（PFC）的连续记录表明，与SWR分离的独立PFC波纹在NREM睡眠中普遍存在，并且主要抑制海马活动。PFC涟漪矛盾地介导了自顶向下抑制海马再激活，而不是协调，对于在协调的CA1-PFC涟漪期间重新激活的组件，这种抑制更强，以巩固最近的经验。Further,我们展示了非规范，具有缓慢和纺锤体振荡的独立皮质波纹的串行协调，这是已知的记忆巩固的标志。这些结果确立了前额叶皮质波纹在巩固过程中行为相关海马表征的自上而下调节中的作用。
