Center for Experimental Neurology, Department of Neurology, Inselspital University Hospital, University of Bern, Bern, Switzerland.
Department for BioMedical Research, University of Bern, Bern, Switzerland.
Sleep. 2019 Dec 24;42(12). doi: 10.1093/sleep/zsz182.
Theta phase modulates gamma amplitude in hippocampal networks during spatial navigation and rapid eye movement (REM) sleep. This cross-frequency coupling has been linked to working memory and spatial memory consolidation; however, its spatial and temporal dynamics remains unclear. Here, we first investigate the dynamics of theta-gamma interactions using multiple frequency and temporal scales in simultaneous recordings from hippocampal CA3, CA1, subiculum, and parietal cortex in freely moving mice. We found that theta phase dynamically modulates distinct gamma bands during REM sleep. Interestingly, we further show that theta-gamma coupling switches between recorded brain structures during REM sleep and progressively increases over a single REM sleep episode. Finally, we show that optogenetic silencing of septohippocampal GABAergic projections significantly impedes both theta-gamma coupling and theta phase coherence. Collectively, our study shows that phase-space (i.e. cross-frequency coupling) coding of information during REM sleep is orchestrated across time and space consistent with region-specific processing of information during REM sleep including learning and memory.
在空间导航和快速眼动（REM）睡眠期间，theta 相位调节海马网络中的 gamma 振幅。这种跨频耦合与工作记忆和空间记忆巩固有关；然而，其空间和时间动态仍不清楚。在这里，我们首先使用来自自由移动小鼠的海马 CA3、CA1、下托和顶叶皮层的同时记录中的多个频率和时间尺度来研究 theta-gamma 相互作用的动力学。我们发现 theta 相位在 REM 睡眠期间动态调节不同的 gamma 频段。有趣的是，我们进一步表明，在 REM 睡眠期间，theta-gamma 耦合在记录的大脑结构之间切换，并在单个 REM 睡眠期间逐渐增加。最后，我们表明，隔海马 GABA 能投射的光遗传沉默显著阻碍了 theta-gamma 耦合和 theta 相位相干性。总的来说，我们的研究表明，在 REM 睡眠期间，信息的相位空间（即跨频耦合）编码是跨时间和空间协调的，与 REM 睡眠期间包括学习和记忆在内的信息的特定区域处理一致。
