Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy/Center of Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Casanova, Barcelona, Spain.
Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy/Department of Neurology, San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy.
Mult Scler. 2019 May;25(6):801-810. doi: 10.1177/1352458518771838. Epub 2018 Apr 23.
We used graph theoretical analysis to quantify structural connectivity of the hippocampal-related episodic memory network and its association with memory performance in multiple sclerosis (MS) patients.
Brain diffusion and T1-weighted sequences were obtained from 71 MS patients and 50 healthy controls (HCs). A total of 30 gray matter regions (selected a priori) were used as seeds to perform probabilistic tractography and create connectivity matrices. Global, nodal, and edge graph theoretical properties were calculated. In patients, verbal and visuospatial memory was assessed.
MS patients showed decreased network strength, assortativity, transitivity, global efficiency, and increased average path length. Several nodes had decreased strength and communicability in patients, whereas insula and left temporo-occipital cortex increased communicability. Patients had widespread decreased streamline count (SC) and communicability of edges, although a few ones increased their connectivity. Worse memory performance was associated with reduced network efficiency, decreased right hippocampus strength, and reduced SC and communicability of edges related to medial temporal lobe, thalamus, insula, and occipital cortex.
Impaired structural connectivity occurs in the hippocampal-related memory network, decreasing the efficiency of information transmission. Network connectivity measures correlate with episodic memory, supporting the relevance of structural integrity in preserving memory processes in MS.
我们运用图论分析的方法来量化与海马体相关的情景记忆网络的结构连接，并将其与多发性硬化症（MS）患者的记忆表现相关联。
从 71 名 MS 患者和 50 名健康对照者（HCs）中获取大脑弥散张量成像和 T1 加权序列。共选取 30 个灰质区域（事先选定）作为种子点，进行概率追踪并创建连接矩阵。计算全局、节点和边缘的图论性质。在患者中，评估了言语和视空间记忆。
MS 患者的网络强度、聚类系数、介数、全局效率降低，平均路径长度增加。与患者相比，一些节点的强度和连通性降低，而岛叶和左侧颞枕叶的连通性增加。患者的线数（SC）和边缘连通性普遍减少，尽管一些边缘的连接性增加。记忆表现越差与网络效率降低、右侧海马体强度降低以及与内侧颞叶、丘脑、岛叶和枕叶相关的边缘的 SC 和连通性降低有关。
与海马体相关的记忆网络中存在结构连接受损，降低了信息传递的效率。网络连接的测量值与情景记忆相关，支持了结构完整性在 MS 中对记忆过程的重要性。
