GIGA-Research, Cyclotron Research Centre/In Vivo Imaging Unit, University of Liège, Liège, Belgium; Walloon Excellence in Life Sciences and Biotechnology (WELBIO, Belgium), Belgium.
GIGA-Research, Cyclotron Research Centre/In Vivo Imaging Unit, University of Liège, Liège, Belgium; Walloon Excellence in Life Sciences and Biotechnology (WELBIO, Belgium), Belgium; Department of Neurology, CHU de Liège, Liège, Belgium.
Neuroimage. 2018 Jul 15;175:354-364. doi: 10.1016/j.neuroimage.2018.03.055. Epub 2018 Mar 28.
Lack of sleep has a considerable impact on vigilance: we perform worse, we make more errors, particularly at night, when we should be sleeping. Measures of brain functional connectivity suggest that decrease in vigilance during sleep loss is associated with an impaired cross-talk within the fronto-parietal cortex. However, fronto-parietal effective connectivity, which is more closely related to the causal cross-talk between brain regions, remains unexplored during prolonged wakefulness. In addition, no study has simultaneously investigated brain effective connectivity and wake-related changes in vigilance, preventing the concurrent incorporation of the two aspects. Here, we used electroencephalography (EEG) to record responses evoked by Transcranial Magnetic Stimulation (TMS) applied over the frontal lobe in 23 healthy young men (18-30 yr.), while they simultaneously performed a vigilance task, during 8 sessions spread over 29 h of sustained wakefulness. We assessed Response Scattering (ReSc), an estimate of effective connectivity, as the propagation of TMS-evoked EEG responses over the fronto-parietal cortex. Results disclose a significant change in fronto-parietal ReSc with time spent awake. When focusing on the night-time period, when one should be sleeping, participants with lower fronto-parietal ReSc performed worse on the vigilance task. Conversely, no association was detected during the well-rested, daytime period. Night-time fronto-parietal ReSc also correlated with objective EEG measures of sleepiness and alertness. These changes were not accompanied by variations in fronto-parietal response complexity. These results suggest that decreased brain response propagation within the fronto-parietal cortex is associated to increased vigilance failure during night-time prolonged wakefulness. This study reveals a novel facet of the detrimental effect on brain function of extended night-time waking hours, which is increasingly common in our societies.
我们的表现更差，犯的错误更多，尤其是在晚上，我们本该睡觉的时候。大脑功能连接的测量表明，睡眠不足期间警觉性的下降与额顶叶皮层内部的交叉对话受损有关。然而，在长时间清醒期间，与大脑区域之间因果交叉对话更密切相关的额顶叶有效连接仍未得到探索。此外，没有研究同时调查大脑有效连接和与清醒相关的警觉性变化，从而无法同时纳入这两个方面。在这里，我们使用脑电图（EEG）记录了 23 名健康年轻男性（18-30 岁）在额叶上接受经颅磁刺激（TMS）刺激时的反应，同时他们在 29 小时的持续清醒过程中进行了警觉性任务。我们评估了响应散射（ReSc），这是有效连接的估计，作为 TMS 诱发的 EEG 反应在额顶叶皮层上的传播。结果显示，随着清醒时间的增加，额顶叶 ReSc 发生了显著变化。当关注应该睡觉的夜间时段时，额顶叶 ReSc 较低的参与者在警觉性任务上的表现更差。相反，在休息良好的白天时段则没有检测到相关性。夜间额顶叶 ReSc 还与 EEG 测量的困倦和警觉性客观指标相关。这些变化伴随着额顶叶反应复杂性的变化。这些结果表明，额顶叶皮层内大脑反应传播的减少与夜间长时间清醒时警觉性失败的增加有关。这项研究揭示了延长夜间清醒时间对大脑功能的有害影响的一个新方面，这种影响在我们的社会中越来越普遍。
