脑电信息处理

脑电信息处理是脑功能研究重要组成部分。本文介绍了脑电信息处理的前沿领域,包括诱发电位、事件相关电位（ＥＲＰ）、正弦调制光（声）诱发脑电、４０ＨｚＥＲＰ和脑电非线笥动力学研究,并论及了认知活动与分形维数的关系。     

短时记忆容量与40Hz脑电事件相关电位分维特性的相关性研究

我们采用不同组块数的汉字词组作为刺激事件,研究了在短时记忆过程中４０Ｈｚ脑电事件相关电位（４０Ｈｚ ＥＲＰｓ）的分维特性。通过短时记忆容量与４０Ｈｚ ＥＲＰｓ分维特性的相关分析,发现在测试组块数在７附近时,４０Ｈｚ ＥＲＰｓ分维数分形维数特性发生了突变,表现为左右半球分维数值相对大小的反转和同一半球内分维数的突降。这与心理学分析得到的汉字短时记忆容量在６、７个组块数附近的结合相吻合。     

基于大脑皮层信息传输的脑电信息图示方法

提出一种基于大脑皮层信息传输的脑电地形图示方法—脑电信息图（Ｂｒａｉｎ ＩｎｆｏｒｍａｔｉｏｎＭａｐｐｉｎｇ － ＢＩＭ） 。其原理是从不同导联电极上采集脑电信号经相空间重建构成头皮电位信息传输矩阵, 将各导联信息传输时间序列的信息传输量和复杂度数据绘制成头皮拓扑分布图, 以直观地反映脑电信息传输分布模式在不同时相中的变化进程。该方法不仅是从新的角度观察大脑功能变化, 而且可克服传统的脑电频谱分段地形图不能表达长程脑电模式变化的不足。对局限性癫痫病患者的试用表明,脑电信息图能较好地反映癫痫发作前后的信息传输动向和复杂度（Ｋｃ 、Ｃ１ 、Ｃ２） 的变化趋势。结果提示,脑电信息图（ＢＩＭ） 有可能成为一种新的观察大脑功能活动的图示诊断方法,值得进一步深入研究。     

一种新型的脑电位分布处理仪

我们研制的BKC-1型脑电处理仪,也称为脑电地形图仪。它是一种新颖的脑电信息处理仪器,采用高档微机(有高精度A/D转换接口)、精密的AR参数模型和快速傅立叶变换(FFT)相结合的脑电波处理软件。可直接与现有的国内外各种类型的脑电仪连接,能对多种脑电信号进行数据采集和处理。脑电位分布处理仪原理框图如图1所示。它用电子计算机对脑电图(EEG)信号进行处理,将脑电图的曲线波形转化成二维的彩色图象。同普通脑电图信号相比,它     

基于分类的单实验事件相关电位估计方法

本文提出了一个基于机器学习的新方法,用以从单实验脑电信号中估计事件相关电位.为估计事件相关电位,首先构建了一个运用分类方法的基本框架和以此框架为基础的优化模型.在此基础上,引入logistic回归来实例化这个优化模型,并推导出SingleTrialEM算法.只要在使用之前训练得到一个logistic模型,SingleTrialEM算法就能够从单实验脑电信号中估计事件相关电位.模拟测试表明,本文的方法是正确稳定的,明显优于Woody过滤器方法.认知测试的结果与认知科学的各项结论一致.     

应用小波变换提取ERP的P3波

本文首次以平均ＥＲＰ和单次ＥＲＰ小波变换系数相关性为基础,设计了小波时频滤波器,可以将单次事件关联电位的Ｐ３波从眼动、自发脑电等干扰中提取出来     

有限元法计算各向异性介质球头模型电位分布

在脑电正问题研究中,脑神经元所产生的电活动可用电流偶极子来模拟.本文提出把大脑看作各向异性介质球,即同时考虑电容效应、电导效应对脑内电流偶极子产生的电位的影响,并用有限元法推导出偶极子在各向异性介质球模型中的电位分布计算公式.结果表明介质的电容效应对电位分布是有影响的,反映了大脑活组织电特性,对外来不同频率的信号刺激有不同的响应.同时有限元法对大脑内某一区域内电位分布求解表明,测量较深层组织的电特性变化敏感的特点,可获得更多的测量信息.     

脑电事件相关去同步化和同步化的神经元群模型

利用基于丘脑-皮层网络的神经元群模型,研究被试者在某种认知状态下脑功能区的连接状态。模型包括三个模块,分别对应脑电头皮电极C3、Cz、C4记录的三个皮质区。模型外部输入包括用高斯白噪声表示的上行传入感受器信号、用直流偏移表示的皮质对丘脑的兴奋性输入、用指数衰减表示的来自脑千和前脑基底神经元的调制信号。模型输出的兴奋性神经元群的平均膜电位反映脑电记录的局部电位。改变模型输入,进行多次仿真试验并进行线性和非线性分析。研究结果显示：仿真输出信号的alpha频带功率谱有与实际脑机接口实验一致的事件相关去同步化和同步化现象;模型中功能相近的区域间有更强的耦合,随着耦合强度的增加,输出信号间的相关性和同步性均增加。     

再版《脑物理学》

再版《脑物理学》内容增加近一倍。新增内容主要有超导磁强计的设计思想、认知电位、计算机与大脑、大脑功能检测等。介绍了如何利用事件相关脑电位（ＥＲＰ）、事件相关脑磁场（ＥＲＦ）、偏侧准备电位（ＬＲＰ）,以及正确比（或出错率）、反应时间（ＲＴ）等,检测选择注意、短时记忆、语言活动、认知处理等心理工作。科学家们把人大脑看作一个信息处理系统,由彼此可区分的多个子系统组成。最简单的分法就是分成感觉中枢子系统和运动中枢子系统。目前已检测出这两个子系统之间的信息传输、运动准备、策略作用等功能。最后介绍了利用电磁…     

基于关联维数和Lyapunov指数高频脑电非线性动力学研究

目的:探讨利用非线性动力学理论特征值来区分老年人和青年人脑电的差异。方法:采用非线性动力学的关联维数和lyapunov指数对老年组和青年组的安静闭眼、安静睁眼和N-back字母记忆事件等的高频脑电进行特征提取,对特征值进行统计分析,分析两组特征值之间的差别。结果:安静闭眼和安静睁眼事件下,老年组多数导联的关联维数和lyapunov指数的特征值与青年组的特征值存在显著差异(P均0.05);N-back字母记忆事件下,老人多数导联的关联维数特征值大于青年的特征值,但老年组只有14导联的lyapunov指数特征值大于青年组的特征值(P均0.05)。不管有无思维活动,人脑在矢状线上的五个导联Fz、FCz、Cz、CPz、Pz的关联维数和lyapunov指数的特征值都处在峰值处。结论:老年人相比青年人脑功能弱、能量发放少;在思维活动情况下,老年需要更多地发放能量来完成相同的思维活动。安静闭眼和睁眼以及N-back字母记忆事件等三个事件的关联维数和lyapunov指数特征值可用来区分老年组和青年组脑电的差异。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.