Engels M M A, Yu M, Stam C J, Gouw A A, van der Flier W M, Scheltens Ph, van Straaten E C W, Hillebrand A
Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
Department of Clinical Neurophysiology and MEG Center, VU University Medical Center, Amsterdam, The Netherlands.
Neuroimage Clin. 2017 Jun 17;15:673-681. doi: 10.1016/j.nicl.2017.06.025. eCollection 2017.
In a recent magnetoencephalography (MEG) study, we found posterior-to-anterior information flow over the cortex in higher frequency bands in healthy subjects, with a reversed pattern in the theta band. A disruption of information flow may underlie clinical symptoms in Alzheimer's disease (AD). In AD, highly connected regions (hubs) in posterior areas are mostly disrupted. We therefore hypothesized that in AD the information flow from these hub regions would be disturbed. We used resting-state MEG recordings from 27 early-onset AD patients and 26 healthy controls. Using beamformer-based virtual electrodes, we estimated neuronal oscillatory activity for 78 cortical regions of interest (ROIs) and 12 subcortical ROIs of the AAL atlas, and calculated the directed phase transfer entropy (dPTE) as a measure of information flow between these ROIs. Group differences were evaluated using permutation tests and, for the AD group, associations between dPTE and general cognition or CSF biomarkers were determined using Spearman correlation coefficients. We confirmed the previously reported posterior-to-anterior information flow in the higher frequency bands in the healthy controls, and found it to be disturbed in the beta band in AD. Most prominently, the information flow from the precuneus and the visual cortex, towards frontal and subcortical structures, was decreased in AD. These disruptions did not correlate with cognitive impairment or CSF biomarkers. We conclude that AD pathology may affect the flow of information between brain regions, particularly from posterior hub regions, and that changes in the information flow in the beta band indicate an aspect of the pathophysiological process in AD.
在最近一项脑磁图（MEG）研究中，我们发现健康受试者在高频波段时，大脑皮层存在从后向前的信息流，而在θ波段则呈现相反模式。信息流的中断可能是阿尔茨海默病（AD）临床症状的基础。在AD中，后部区域的高度连接区域（枢纽）大多受到破坏。因此，我们推测在AD中，来自这些枢纽区域的信息流会受到干扰。我们使用了27名早发性AD患者和26名健康对照者的静息态MEG记录。利用基于波束形成器的虚拟电极，我们估计了AAL图谱中78个皮质感兴趣区域（ROI）和12个皮质下ROI的神经元振荡活动，并计算了定向相位转移熵（dPTE），作为这些ROI之间信息流的度量。使用置换检验评估组间差异，对于AD组，使用斯皮尔曼相关系数确定dPTE与一般认知或脑脊液生物标志物之间的关联。我们证实了先前报道的健康对照者在高频波段从后向前的信息流，并发现AD患者在β波段的这种信息流受到干扰。最显著的是，在AD中，从楔前叶和视觉皮层向额叶和皮质下结构的信息流减少。这些中断与认知障碍或脑脊液生物标志物无关。我们得出结论，AD病理可能会影响脑区之间的信息流，特别是来自后部枢纽区域的信息流，并且β波段信息流的变化表明了AD病理生理过程的一个方面。
