【作者】 王超；

【导师】 于洪丽；

【作者基本信息】 河北工业大学 ， 工程硕士（专业学位）， 2021， 硕士

【摘要】 神经系统是人最复杂也是最重要的系统之一,其受损或功能异常会引发多种疾病和后遗症。作为一种非侵入式的神经调控技术,经颅电刺激可通过调节皮质神经元的兴奋性改善神经系统响应,但其刺激效应仍未明确阐明。本文通过仿真和实验的结合,图论分析结合电生理技术,从多个尺度研究不同强度电刺激对神经响应特性的分析,为辅助制定安全合理的t DCS刺激方案提供了参考。本文主要内容包括:1.通过仿真外加电刺激下的单个HH神经元模型、电耦合神经元模型和NW小世界神经网络,从不同尺度神经模型角度分析电刺激强度对神经放电响应的影响。一定强度的电刺激可促进神经元的兴奋性,使其放电频率增加,促进了神经网络放电的同步性,增强网络的激活程度,这种积极作用与电刺激强度呈正相关,但较大的电刺激会降低强电耦合强度网络的激活程度。2.对健康人施加1.0m A、1.25m A、1.5m A和1.75m A四种强度的t DCS,采集刺激前后的脑电信号,通过分析被试脑电的功率谱密度初步判断t DCS对脑电的影响,发现1.0m A和1.25m A的t DCS对alpha波段的功率谱密度几乎不存在影响,1.5m A和1.75m A的t DCS提升了alpha波段的功率谱密度,且1.75m A效果更明显。3.采用基于Wilcoxon符号秩和检验的相位滞后算法计算脑电信号同步性,并分别构建不同强度t DCS刺激前后的脑功能网络,计算和统计分析节点度、聚类系数、特征路径长度和网络效率(全局和局部效率)几个特征参数以及网络的小世界属性,以宏观脑电结合图论的方法分析不同强度电刺激对神经系统的作用效应。t DCS刺激后网络的节点度、聚类系数、网络效率(全局效率和局部效率)均有显著性增加,特征路径长度显著减少,变化幅度随刺激强度的增加而增加。t DCS刺激前和刺激后的脑网络均具有小世界属性,刺激后比刺激前小世界属性更强。t DCS加强了脑区之间的相位同步活动,提高了网络信息的传输效率。更多还原

【Abstract】 Nervous system is one of the most complex and important human systems,its damage or abnormal function will lead to a variety of diseases and sequelae.Transcranial direct current stimulation(t DCS),a non-invasive neuroregulation technique,can improve the response of the nervous system by modulating the excitability of cortical neurons,but its stimulation effects have not been clearly clarified.In this paper,based on the HH neuron model,the nerve response to external electrical stimulation was simulated and analyzed.By using t DCS as an intervention method,healthy EEG before and after t DCS with 1.0m A,1.25 m A,1.5m A and 1.75 m A were collected.Based on power spectral density analysis and brain functional network analysis,the effects of t DCS on neural response were explored.The main contents of this paper include:1.Through the analysis of the neural response of the single neuron model,electrical synapses coupling neuron model and NW small-world neural network to the external electrical stimulation,the results showed that a range intensity of electrical stimulation could promote the excitability of neurons.And the increase of the discharge frequency could promote the synchronicity of neural network and enhance network activation degree.This positive effect was positively related to the intensity of electrical stimulation.However,excessive electrical stimulation could reduce the activation degree of the network with strong electrical coupling strength.2.The average power spectral density of all channels and the power spectral density of C3 and C4 leads of the subjects were analyzed.The results showed that 1.0m A and1.25 m A t DCS had almost no effect on the power spectral density of alpha band.1.5m A and1.75 m A t DCS improved the power spectral density of alpha band,and 1.75 m A was more significantly.3.The phase lag based on Wilcoxon signed rank sum test(PLWT)was used to construct brain functional networks before and after t DCS with different current intensities.Five characteristic parameters of network: node degree,clustering coefficient,characteristic path length and network efficiency(global efficiency and local efficiency)were calculated and statistically analyzed,and the small-world property of the networks was estimated.The results showed that the node degree,clustering coefficient,network efficiency were significantly increased after t DCS,and the characteristic path length was significantly decreased.The variation range increased with the increase of the stimulus intensity.Both the brain networks before and after t DCS had small-world property.And the small-world property after t DCS was stronger than those before t DCS.It suggested that t DCS could enhance the phase synchronization between brain regions and improve the efficiency of network’s information transmission.更多还原