基于格兰杰因果关系的因效性脑网络研究

发布时间：2018-02-26 02:29

本文关键词： 格兰杰因果关系精神分裂症脑磁图 dDTF 因效性脑网络　出处：《南京邮电大学》2017年硕士论文　论文类型：学位论文

【摘要】：精神分裂症(schizophrenia)是一种严重的精神疾病,部分患者会出现主动性和认知功能丧失,最终导致脑功能衰退和精神残疾,也有的患者经过治疗后可以基本痊愈。本文在前人的工作基础上,基于格兰杰因果关系(Granger causality,GC)的因效性脑网络分析方法,深入研究了正常人、精神分裂症患者和无症状的患者亲属这三类人群的复杂脑网络差异,寻找客观的量化指标帮助医生及时发现病症。基于相关理论,本文主要完成了如下研究:第一,将直接定向传递函数(Direct Directed Transfer Function,dDTF)作为因果关系度量值,分别对三类人群的脑磁图(Magnetoencephalography,MEG)数据进行格兰杰因果关系分析,基于得出的因果关系邻接矩阵构建三类人群的因效性脑网络。实验结果发现,患者相比正常对照组在额叶区的因果作用要强,在颞叶区的因果作用要弱。这些异常的因果连接可能是导致患者的精神异常,甚至出现幻听、幻视等症状的原因。值得注意的是患者亲属左中央区的因果作用出现缺失,这可能是家族遗传过程中表现出来的一个隐性症状。第二,研究了三类人群复杂脑网络的网络拓扑熵、平均聚类系数、网络全局效率等全局拓扑特性,并且分析了不同大脑节律下因效性脑网络的特性差异。实验结果表明,三类人群脑网络的全局拓扑特性之间没有显著性差异,而在不同大脑节律下的dDTF均值存在显著差异。并且正常对照组和患者在不同节律下的网络全局特征相差不大。此外,患者亲属的各网络全局测度在频段普遍高于其他两类人,而在频段和频段普遍低于其他两类人。第三,研究了三类人群复杂脑网络的局部拓扑特性,即节点的度、介数、紧密度和核心数等网络“核心位置”测度。实验结果表明,正常对照组的脑网络分布最为稠密,有较多的核心节点和核心连接边,而患者亲属和患者的脑网络则相对稀疏。患者的脑网络在额叶区的因果作用较强,而在颞叶区较弱。根据实验结果推测,患者和患者亲属的某个节点与其余大部分节点丧失了相互作用。在中央额区三类人群均具有最高介数,是脑网络中的核心位置;患者和患者亲属在左中央区具有较高介数,且介数值均高于正常对照组。此外,患者亲属有较多节点的紧密度明显高于正常对照组和患者。第四,选取不同阈值,研究了三类人群的全频段分层因效性脑网络。通过分析发现,在高阈值和中等阈值下,三类人群的脑网络中同一脑区内的信息交流要大于不同脑区之间的信息交流,从一定程度上表明大脑更符合Hilgetag等人提出的全局稀疏的模块化分层结构。通过对网络拓扑熵的分析发现,三类人群的网络拓扑熵在中等阈值下最高,在高阈值下次之,在低阈值下最低。在中高阈值下,正常对照组的网络拓扑熵最高,患者次之,患者亲属最低。
[Abstract]:Schizophrenia is a severe mental illness, in which some patients suffer from loss of initiative and cognitive function, leading to brain dysfunction and mental disability. Some patients can be cured after treatment. Based on the previous work and Granger causality GCC-based brain network analysis method, this paper deeply studied the normal people. The complex brain network differences between schizophrenic patients and asymptomatic relatives of these three groups, looking for objective quantitative indicators to help doctors find the disease in time. Based on the relevant theory, this paper mainly completed the following research: first, Using direct Directed Transfer function dDTF as causality measure, Granger causality analysis was carried out on Magnetoencephalographic (Meg) data of three groups of people. Based on the resulting causality adjacency matrix, the causal brain network of three groups of people was constructed. The results showed that the causal effect of the patients was stronger than that of the normal control group in the frontal lobe area. The causal effect in temporal lobe area is weak. The causal connection of these abnormalities may be the cause of patients' mental disorders, even hallucinations, hallucinations and other symptoms. It is worth noting that the causal effect of the left central region of the relatives of the patient is missing. This may be a hidden symptom in the family genetic process. Secondly, the network topology entropy, average clustering coefficient, global network efficiency and other global topological properties of the complex brain network of three groups of people are studied. The experimental results show that there is no significant difference in the global topological properties of the brain networks among the three groups of people. However, there were significant differences in the mean value of dDTF in different brain rhythms, and there was no significant difference in the global characteristics of the network between the normal control group and the patient under different rhythms. In addition, the network global measures of the patients' relatives were generally higher than those of the other two groups in the frequency range. In the frequency band and frequency band, it is generally lower than the other two groups of people. Thirdly, the local topological characteristics of the complex brain network of three groups of people are studied, that is, the degree of node, the intermediate number, the density and the core number of the network "core position" measure. The experimental results show that, In the normal control group, the brain network is the most dense, with more core nodes and the core junction edge, while the brain network of the patient's relatives and patients is relatively sparse. The brain network of the patient has a strong causal effect in the frontal lobe area. According to the experimental results, one node of the patient and his relatives lost interaction with most of the other nodes. In the central frontal region, all three populations have the highest number of mediums, which is the core position in the brain network. Patients and relatives of patients had higher mediums in the left central region, and the dielectric values were higher than those in the normal control group. In addition, the tightness of more nodes in the relatives of the patients was significantly higher than that in the normal controls and patients. 4th, different thresholds were selected. In this paper, we studied the three groups of people's hierarchical response brain networks. Through the analysis, we found that the information exchange in the same brain area of the three groups of people was greater than that between different brain regions under the high threshold and the middle threshold. To some extent, it shows that the brain accords with the global sparse modularized layered structure proposed by Hilgetag et al. Through the analysis of the network topology entropy, it is found that the network topology entropy of the three groups of people is the highest at the middle threshold, and the next time at the high threshold. The network topology entropy of the normal control group is the highest, the patient is the second, and the relatives of the patient is the lowest.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R749.3;O157.5

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