Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47907, USA.
Department of Human Development and Family Science, College of Health and Human Sciences, Purdue University, West Lafayette, IN, 47907, USA.
Sleep Med. 2023 Oct;110:44-53. doi: 10.1016/j.sleep.2023.07.021. Epub 2023 Jul 27.
In clinical populations, the movement of cerebrospinal fluid (CSF) during sleep is a growing area of research with potential mechanistic connections in both neurodegenerative (e.g., Alzheimer's Disease) and neurodevelopmental disorders. However, we know relatively little about the processes that influence CSF movement. To inform clinical intervention targets this study assesses the coupling between (a) real-time CSF movement, (b) neuronal-driven movement, and (c) non-neuronal systemic physiology driven movement.
This study included eight young, healthy volunteers, with concurrently acquired neurofluid dynamics using functional Magnetic Resonance Imaging (MRI), neural activity using Electroencephalography (EEG), and non-neuronal systemic physiology with peripheral functional Near-Infrared Spectroscopy (fNIRS). Neuronal and non-neuronal drivers were assessed temporally; wherein, EEG measured slow wave activity that preceded CSF movement was considered neuronally driven. Similarly, slow wave oscillations (assessed via fNIRS) that coupled with CSF movement were considered non-neuronal systemic physiology driven.
Our results document neural contributions to CSF movement were only present during light NREM sleep but low-frequency non-neuronal oscillations were strongly coupled with CSF movement in all assessed states - awake, NREM-1, NREM-2. The clinical/research implications of these findings are two-fold. First, neuronal-driven oscillations contribute to CSF movement outside of deep sleep (NREM-3); therefore, interventions aimed at increasing CSF movement may yield meaningful increases with the promotion of NREM sleep more generally - a focus on NREM S3 may not be needed. Second, non-neuronal systemic oscillations contribute across wake and sleep stages; therefore, interventions may increase CSF movement by manipulating systemic physiology.
在临床人群中，脑脊液（CSF）在睡眠期间的流动是一个研究领域，它与神经退行性疾病（如阿尔茨海默病）和神经发育障碍都有潜在的机制联系。然而，我们对影响 CSF 流动的过程知之甚少。为了为临床干预提供目标，本研究评估了（a）实时 CSF 流动、（b）神经元驱动的运动和（c）非神经元系统性生理驱动的运动之间的耦合。
本研究包括 8 名年轻、健康的志愿者，同时使用功能磁共振成像（fMRI）进行神经流体动力学测量、脑电图（EEG）进行神经活动测量以及外周功能近红外光谱（fNIRS）进行非神经元系统性生理测量。对神经元和非神经元的驱动因素进行了时间评估；其中，EEG 测量的在 CSF 运动之前出现的慢波活动被认为是神经元驱动的。同样，与 CSF 运动耦合的慢波振荡（通过 fNIRS 评估）被认为是非神经元系统性生理驱动的。
我们的结果表明，只有在轻度非快速眼动睡眠期间才存在神经对 CSF 运动的贡献，但低频非神经元振荡在所有评估状态（清醒、NREM-1、NREM-2）中都与 CSF 运动强烈耦合。这些发现的临床/研究意义有两个方面。首先，神经元驱动的振荡在非快速眼动睡眠（NREM-3）之外也有助于 CSF 运动；因此，旨在增加 CSF 运动的干预措施可能会随着更普遍地促进非快速眼动睡眠而产生有意义的增加——可能不需要特别关注 NREM S3。其次，非神经元系统性振荡在清醒和睡眠阶段都有贡献；因此，通过调节系统性生理学，干预措施可能会增加 CSF 运动。
