Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Learn Mem. 2023 Sep 27;30(9):221-236. doi: 10.1101/lm.053834.123. Print 2023 Sep.
Episodic memories are thought to be stabilized through the coordination of cortico-hippocampal activity during sleep. However, the timing and mechanism of this coordination remain unknown. To investigate this, we studied the relationship between hippocampal reactivation and slow-wave sleep up and down states of the retrosplenial cortex (RTC) and prefrontal cortex (PFC). We found that hippocampal reactivations are strongly correlated with specific cortical states. Reactivation occurred during sustained cortical Up states or during the transition from up to down state. Interestingly, the most prevalent interaction with memory reactivation in the hippocampus occurred during sustained up states of the PFC and RTC, while hippocampal reactivation and cortical up-to-down state transition in the RTC showed the strongest coordination. Reactivation usually occurred within 150-200 msec of a cortical Up state onset, indicating that a buildup of excitation during cortical Up state activity influences the probability of memory reactivation in CA1. Conversely, CA1 reactivation occurred 30-50 msec before the onset of a cortical down state, suggesting that memory reactivation affects down state initiation in the RTC and PFC, but the effect in the RTC was more robust. Our findings provide evidence that supports and highlights the complexity of bidirectional communication between cortical regions and the hippocampus during sleep.
情景记忆被认为是通过睡眠期间皮质-海马体活动的协调来稳定的。然而，这种协调的时间和机制仍然未知。为了研究这一点，我们研究了海马体再激活与后扣带回皮层（RTC）和前额叶皮层（PFC）慢波睡眠上下状态之间的关系。我们发现海马体再激活与特定的皮质状态密切相关。再激活发生在皮质持续的 Up 状态或从 Up 状态到 Down 状态的转变期间。有趣的是，与海马体记忆再激活最常见的相互作用发生在 PFC 和 RTC 的持续 Up 状态期间，而海马体再激活和 RTC 的皮质 Up-to-Down 状态转变显示出最强的协调。再激活通常发生在皮质 Up 状态开始后 150-200 毫秒内，表明在皮质 Up 状态活动期间兴奋的积累会影响 CA1 中记忆再激活的概率。相反，CA1 的再激活发生在皮质 Down 状态开始前 30-50 毫秒，表明记忆再激活影响 RTC 和 PFC 中的 Down 状态起始，但在 RTC 中的影响更为显著。我们的发现提供了证据，支持并强调了睡眠期间皮质区域和海马体之间双向通信的复杂性。
