Stam C J, de Haan W, Daffertshofer A, Jones B F, Manshanden I, van Cappellen van Walsum A M, Montez T, Verbunt J P A, de Munck J C, van Dijk B W, Berendse H W, Scheltens P
Department of Clinical Neurophysiology and MEG, Amsterdam, The Netherlands.
Brain. 2009 Jan;132(Pt 1):213-24. doi: 10.1093/brain/awn262. Epub 2008 Oct 24.
In this study we examined changes in the large-scale structure of resting-state brain networks in patients with Alzheimer's disease compared with non-demented controls, using concepts from graph theory. Magneto-encephalograms (MEG) were recorded in 18 Alzheimer's disease patients and 18 non-demented control subjects in a no-task, eyes-closed condition. For the main frequency bands, synchronization between all pairs of MEG channels was assessed using a phase lag index (PLI, a synchronization measure insensitive to volume conduction). PLI-weighted connectivity networks were calculated, and characterized by a mean clustering coefficient and path length. Alzheimer's disease patients showed a decrease of mean PLI in the lower alpha and beta band. In the lower alpha band, the clustering coefficient and path length were both decreased in Alzheimer's disease patients. Network changes in the lower alpha band were better explained by a 'Targeted Attack' model than by a 'Random Failure' model. Thus, Alzheimer's disease patients display a loss of resting-state functional connectivity in lower alpha and beta bands even when a measure insensitive to volume conduction effects is used. Moreover, the large-scale structure of lower alpha band functional networks in Alzheimer's disease is more random. The modelling results suggest that highly connected neural network 'hubs' may be especially at risk in Alzheimer's disease.
在本研究中，我们运用图论概念，对比了阿尔茨海默病患者与非痴呆对照者静息态脑网络的大规模结构变化。在无任务、闭眼状态下，对18名阿尔茨海默病患者和18名非痴呆对照者进行了脑磁图（MEG）记录。对于主要频段，使用相位滞后指数（PLI，一种对容积传导不敏感的同步测量方法）评估所有MEG通道对之间的同步性。计算了PLI加权连接网络，并以平均聚类系数和路径长度进行表征。阿尔茨海默病患者在较低的α和β频段显示平均PLI降低。在较低的α频段，阿尔茨海默病患者的聚类系数和路径长度均降低。与“随机故障”模型相比，“靶向攻击”模型能更好地解释较低α频段的网络变化。因此，即使使用对容积传导效应不敏感的测量方法，阿尔茨海默病患者在较低的α和β频段仍表现出静息态功能连接丧失。此外，阿尔茨海默病中较低α频段功能网络的大规模结构更随机。建模结果表明，高度连接的神经网络“枢纽”在阿尔茨海默病中可能尤其处于风险之中。
