【摘要】 麻醉诱导的无意识在宏观尺度表现为大脑区域之间功能连接的中断.然而,在介观尺度,麻醉的脑意识消失作用机制仍不明确.本研究分析了9名接受丙泊酚全身麻醉的癫痫患者(年龄18～54岁)的皮层脑电(electrocorticogram,ECoG)数据,采用了相位模式复杂度(phase-pattern complexity,PPC)的同步估计方法,并基于图论度量了皮层尺度麻醉前后的聚类系数、平均特征路径长度、全局效率、局部效率和中介中心性等几种网络特征参数.结果表明,delta-theta(1～8Hz)频段和gamma2(48～60Hz)频段在意识消失后的PPC值显著降低(分别为P<0.01,P<0.05).皮层尺度脑网络则由节点间的强连接转变为以少数节点为枢纽节点,并成散射状连接其他节点的网络拓扑结构.研究表明,麻醉导致的意识消失与皮层尺度神经活动的相位模式复杂度的降低及对应的拓扑网络的简单化有关.更多还原

【Abstract】 The neurophysiological mechanisms of anesthetic-induced loss of unconsciousness(LOC) have been extensively investigated at the macro scale. When it comes to the cortical scale, however, it still remains unclear how the cortical network and the information integration mode change during propofol anesthesia. In this study, we employed the phase-pattern complexity(PPC) measure, a synchronization measure of the diversity of temporal patterns in the phase relationships between two time series, to analyze the electrocorticogram(ECoG) changes during propofol anesthesia. Nine epileptic patients who were undergoing intracranial monitoring for surgical treatment were investigated. Network characteristic parameters such as clustering coefficient, average characteristic path length, global efficiency, component efficiency, and betweenness centrality were measured based on the graph theory. Below is a brief summary of our findings. Firstly, the phase-pattern complexity after LOC reduces significantly in the delta-theta(1-8 Hz) and gamma2(48-60 Hz) frequency bands(with a P-value of <0.01 and <0.05, respectively). Secondly, after LOC, the cortical network changes from a strongly connected network of nodes to one where some of the nodes work as hub nodes and are scattered to connect with other nodes. Thirdly, the following conclusions are drawn from the network measure:(1) During propofol anesthesia, the clustering coefficient value increases in the delta-theta and gamma2 frequency bands, which indicates strong aggregation between nodes in the cortical network.(2) The average characteristic path length increases after LOC, which means that the action of propofol impairs the brain’s ability of functional integration.(3) The increase in betweenness centrality indicates that propofol simplifies the cortical network. This leads to an increased number of cortical regions that stop communicating with each other, which in turn results in more paths for information transmission and lower transmission efficiency.(4) The decrease in global efficiency and component efficiency reflects that propofol partially interrupts long-distance connections between cortical regions. To sum up, our research indicates that the propofol induced LOC is related to the reduction of the neural activities’ phase-pattern complexity in cortical scale and the simplification of the corresponding topological networks. The propofol induced LOC is also underlying correlated with the disruption of direct connection between cortical regions and the increasement of the role of hub nodes in information integration.更多还原