Deibel Scott H, Rota Ryan, Steenland Hendrik W, Ali Karim, McNaughton Bruce L, Tatsuno Masami, McDonald Robert J
Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
NeuroTek Innovative Technology Inc., Toronto, ON, Canada.
Front Neurosci. 2020 Oct 6;14:551843. doi: 10.3389/fnins.2020.551843. eCollection 2020.
Circadian rhythm misalignment has a deleterious impact on the brain and the body. In rats, exposure to a 21-hour day length impairs hippocampal dependent memory. Sleep, and particularly K-complexes and sleep spindles in the cortex, have been hypothesized to be involved in memory consolidation. Altered K-complexes, sleep spindles, or interaction between the cortex and hippocampus could be a mechanism for the memory consolidation failure but has yet to be assessed in any circadian misalignment paradigm. In the current study, continuous local field potential recordings from five rats were used to assess the changes in aspects of behavior and sleep, including wheel running activity, quiet wakefulness, motionless sleep, slow wave sleep, REM sleep, K-complexes and sleep spindles, in rats exposed to six consecutive days of a T21 light-dark cycle (L9:D12). Except for a temporal redistribution of sleep and activity during the T21, there were no changes in period, or total amount for any aspect of sleep or activity. These data suggest that the memory impairment elicited from 6 days of T21 exposure is likely not due to changes in sleep architecture. It remains possible that hippocampal plasticity is affected by experiencing light when subjective circadian phase is calling for dark. However, if there is a reduction in hippocampal plasticity, changes in sleep appear not to be driving this effect.
昼夜节律失调会对大脑和身体产生有害影响。在大鼠中，暴露于21小时的日长会损害海马体依赖性记忆。睡眠，尤其是皮层中的K复合波和睡眠纺锤波，被认为与记忆巩固有关。K复合波、睡眠纺锤波的改变，或者皮层与海马体之间的相互作用可能是记忆巩固失败的一种机制，但尚未在任何昼夜节律失调范式中得到评估。在本研究中，对五只大鼠进行连续的局部场电位记录，以评估暴露于连续六天的T21明暗周期（L9:D12）的大鼠在行为和睡眠方面的变化，包括轮转活动、安静觉醒、静止睡眠、慢波睡眠、快速眼动睡眠、K复合波和睡眠纺锤波。除了在T21期间睡眠和活动的时间重新分配外，睡眠或活动的任何方面的周期或总量均无变化。这些数据表明，暴露于T21六天引起的记忆损害可能不是由于睡眠结构的变化。当主观昼夜节律阶段需要黑暗时经历光照，海马体可塑性仍有可能受到影响。然而，如果海马体可塑性降低，睡眠变化似乎并不是这种影响的驱动因素。
