Montgomery Sean M, Sirota Anton, Buzsáki György
Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, New Jersey 07102, USA.
J Neurosci. 2008 Jun 25;28(26):6731-41. doi: 10.1523/JNEUROSCI.1227-08.2008.
Rapid eye movement (REM) sleep has been considered a paradoxical state because, despite the high behavioral threshold to arousing perturbations, gross physiological patterns in the forebrain resemble those of waking states. To understand how intrahippocampal networks interact during REM sleep, we used 96 site silicon probes to record from different hippocampal subregions and compared the patterns of activity during waking exploration and REM sleep. Dentate/CA3 theta and gamma synchrony was significantly higher during REM sleep compared with active waking. In contrast, gamma power in CA1 and CA3-CA1 gamma coherence showed significant decreases in REM sleep. Changes in unit firing rhythmicity and unit-field coherence specified the local generation of these patterns. Although these patterns of hippocampal network coordination characterized the more common tonic periods of REM sleep (approximately 95% of total REM), we also detected large phasic bursts of local field potential power in the dentate molecular layer that were accompanied by transient increases in the firing of dentate and CA1 neurons. In contrast to tonic REM periods, phasic REM epochs were characterized by higher theta and gamma synchrony among the dentate, CA3, and CA1 regions. These data suggest enhanced dentate processing, but limited CA3-CA1 coordination during tonic REM sleep. In contrast, phasic bursts of activity during REM sleep may provide windows of opportunity to synchronize the hippocampal trisynaptic loop and increase output to cortical targets. We hypothesize that tonic REM sleep may support off-line mnemonic processing, whereas phasic bursts of activity during REM may promote memory consolidation.
快速眼动(REM)睡眠一直被认为是一种矛盾的状态,因为尽管对唤醒干扰的行为阈值很高,但前脑的总体生理模式却类似于清醒状态。为了了解海马体内网络在REM睡眠期间如何相互作用,我们使用96通道硅探针从海马体的不同亚区域进行记录,并比较了清醒探索和REM睡眠期间的活动模式。与活跃清醒状态相比,REM睡眠期间齿状回/CA3区的θ波和γ波同步性显著更高。相比之下,CA1区的γ波功率以及CA3-CA1区的γ波相干性在REM睡眠中显著降低。单位发放节律性和单位-场相干性的变化确定了这些模式的局部产生。尽管这些海马体网络协调模式表征了REM睡眠中更常见的紧张期(约占总REM的95%),但我们还在齿状回分子层检测到了局部场电位功率的大幅相位爆发,同时齿状回和CA1神经元的发放出现短暂增加。与紧张性REM期不同,相位性REM时段的特征是齿状回、CA3区和CA1区之间的θ波和γ波同步性更高。这些数据表明,在紧张性REM睡眠期间,齿状回的处理增强,但CA3-CA1区的协调有限。相比之下,REM睡眠期间的相位性活动爆发可能为海马体三突触回路的同步以及增加向皮质靶点的输出提供机会窗口。我们假设,紧张性REM睡眠可能支持离线记忆处理,而REM期间的相位性活动爆发可能促进记忆巩固。