Neuroscience Program, Department of Psychology, and Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02453, USA.
Neuroscience Program, Department of Psychology, and Volen National Center for Complex Systems, Brandeis University, 415 South Street, Waltham, MA 02453, USA.
Curr Biol. 2024 Jul 8;34(13):2801-2811.e9. doi: 10.1016/j.cub.2024.05.018. Epub 2024 Jun 3.
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.
通过重新激活来巩固最初编码的海马体记忆在新皮层中的表现对于长期记忆的形成至关重要，并且在非快速眼动睡眠期间，海马体的尖波涟漪（SWR）与皮层慢波和纺锤波的协调有助于巩固。最近的证据表明，高频皮层涟漪也可以与海马体 SWR 协调以支持巩固；然而，皮层涟漪对再激活的贡献尚不清楚。我们在空间学习过程中使用高密度、连续的海马体（CA1 区）和前额叶皮层（PFC）记录，结果表明，与 SWR 分离的独立 PFC 涟漪在非快速眼动睡眠中很常见，主要抑制海马体活动。PFC 涟漪矛盾地介导了自上而下的海马体再激活抑制，而不是协调，并且对于在协调的 CA1-PFC 涟漪期间被重新激活以巩固最近经验的集合，这种抑制更强。此外，我们还展示了独立皮层涟漪与慢波和纺锤波的非典型序列协调，这是记忆巩固的已知特征。这些结果确立了前额叶皮层涟漪在巩固过程中对行为相关海马体表现的自上而下调节中的作用。
