Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania.
Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania.
Hippocampus. 2017 Nov;27(11):1125-1139. doi: 10.1002/hipo.22757. Epub 2017 Jul 12.
Behavioral and neurophysiological evidence suggests that the slow (≤1 Hz) oscillation (SO) during sleep plays a role in consolidating hippocampal (HIPP)-dependent memories. The effects of the SO on HIPP activity have been studied in rodents and cats both during natural sleep and during anesthetic administration titrated to mimic sleep-like slow rhythms. In this study, we sought to document these effects in primates. First, HIPP field potentials were recorded during ketamine-dexmedetomidine sedation and during natural sleep in three rhesus macaques. Sedation produced regionally-specific slow and gamma (∼40 Hz) oscillations with strong coupling between the SO phase and gamma amplitude. These same features were seen in slow-wave sleep (SWS), but the coupling was weaker and the coupled gamma oscillation had a higher frequency (∼70 Hz) during SWS. Second, electrical stimuli were delivered to HIPP afferents in the parahippocampal gyrus (PHG) during sedation to assess the effects of sleep-like SO on excitability. Gamma bursts after the peak of SO cycles corresponded to periods of increased gain of monosynaptic connections between the PHG and HIPP. However, the two PHG-HIPP connectivity gains during sedation were both substantially lower than when the animal was awake. We conclude that the SO is correlated with rhythmic excitation and inhibition of the PHG-HIPP network, modulating connectivity and gamma generators intrinsic to this network. Ketamine-dexmedetomidine sedation produces a similar effect, but with a decreased contribution of the PHG to HIPP activity and gamma generation.
行为和神经生理学证据表明，睡眠期间的慢波（≤1Hz）振荡（SO）在巩固海马（HIPP）依赖性记忆中发挥作用。已经在啮齿动物和猫中研究了 SO 对 HIPP 活动的影响，无论是在自然睡眠期间还是在麻醉滴定以模拟类似睡眠的慢节律期间。在这项研究中，我们试图在灵长类动物中记录这些影响。首先，在三只恒河猴的氯胺酮-右美托咪定镇静期间和自然睡眠期间记录 HIPP 场电位。镇静产生了具有 SO 相位和伽马振幅强耦合的区域特异性慢波和伽马（∼40Hz）振荡。这些相同的特征在慢波睡眠（SWS）中可见，但耦合较弱，并且在 SWS 期间耦合的伽马振荡具有更高的频率（∼70Hz）。其次，在镇静期间向旁海马回（PHG）的 HIPP 传入纤维发送电刺激，以评估类似睡眠的 SO 对兴奋性的影响。SO 周期峰值后的伽马爆发对应于 PHG 和 HIPP 之间单突触连接增益增加的时期。然而，在镇静期间，两个 PHG-HIPP 连接增益都远低于动物清醒时的增益。我们得出结论，SO 与 PHG-HIPP 网络的节律兴奋和抑制相关，调节了该网络的固有连接性和伽马发生器。氯胺酮-右美托咪定镇静产生类似的效果，但 PHG 对 HIPP 活动和伽马产生的贡献降低。
