脑电的非线性动力学研究中的问题和进展

本文对近年来国外在脑电的非线性动力学研究中提出的问题进行了综述 ,内容涉及了脑电的非线性的证明 ,脑电不是低维的混沌 ,以及传统的脑电混沌参数估算中的主要弊病等。文中也介绍了针对以上问题的最新研究进展。     

脑电的非线性动力学高维持性及研究现状与展望

８０年代以来,脑电（ＥＥＧ）一直被视为低维混沌信号,关于脑电混沌性的检验及对其低飨混沌性的质疑,是近年来国际学术界的研究热点。目前的研究基础上论证了ＥＥＧ的非线性和混沌性,却否定了它是源于低维的混沌系统。因此,用经曲的低维混沌算法云分析研究高维ＥＥＧ的适用性和适用条件,必须进行探讨和论证。本文简要介绍了近年来的研究现状,其中着重介绍了ＥＥＧ低维简化模型法,最后展望了研究的发展前景。     

脑电非线性动力学快速分析与癫痫脑电分析

通过分析比较非线性时间序列动力学分析过程中使用的各种算法,选择出适合脑电分析的算法。这些算法时空复杂度较高,计算耗时。我们对这些算法进行了串行优化和改进,使其时间复杂度有不同程度的降低,并提高了其准确度;再对其进行并行化,进一步提升了算法效率。最后整个计算过程运行时间缩短为优化前运行时间的1/50。在此基础上,我们提出了脑电非线性动力学快速分析系统的设计,并使用该系统分析了癫痫脑电数据,取得了良好的结果。     

电刺足三里穴脑电信号的非线性动力学方法初探

为探讨电刺足三里穴位引起的大脑活动的变化，本文以脑电为手段，用非线性动力学方法对电刺前后的两种脑电的非线性特征进行分析。实验结果显示，非线性特征指数，如关联维数、Lyapunov指数和测度熵，在电刺前后均能很好的区分（P〈0．05）。结果表明，电刺后大脑的随机性和无序度降低，大脑相应脑区的活动更趋于有序，且这种有序性将随着电刺次数的增加而渐趋于稳定。     

脑电的非线性动力学研究中的问题和进展

本文对近年来国外在脑电的非线性动力学研究中提出的问题进行了综述,内容涉及了脑电的非线性的证明,脑电不是低维的混沌,以及传统的脑电混沌参数估算中的主要弊病等。文中也介绍了针对以上问题的最新研究进展。     

精神分裂症脑电分析技术研究的进展

讨论了精神分裂症脑电分析技术,包括脑电图,脑诱发电位和脑电地形图在人的几种主要技术的研究进展和应用现状,并对其应用前景做了展望。     

大鼠癫痫模型脑电信息的非线性分析

为了探索应用非线性动力学理论进行癫痫疾病预报的新方法，采用非线性动力学指标：近似熵和相关维对大鼠癫痫发作过程的整个脑电信号进行分析研究。结果显示癫痫发作时，脑电信号的近似熵和相关维明显低于发作前和发作后，这表明了癫痫发作过程脑电信号复杂度的变化规律；而癫痫发作前又是一特殊的阶段，其脑电信号的复杂度已开始降低，但发作症状尚未出现。因此运用非线性动力学方法对癫痫发作至少在短期内可预报。     

新生儿睡眠期的脑电非线性分析方法

目的脑电（electroencephalogram,EEG）是新生儿脑功能监护中重要的生理信号,近年研究发现基于非线性动力学的复杂度分析能够客观反映大脑成熟度、睡眠周期和惊厥状态等。方法本文针对神经系统发育正常的早产新生儿组和足月新生儿组,采用近似熵（approximate entropy,ApEn）和样本熵（sample entropy,SampEn）两种非线性参数,对新生儿在安静睡眠期（quiet sleep,QS）和活动睡眠期（active sleep,AS）的脑电信号进行分析。结果神经系统发育正常的新生儿中,AS期的ApEn和SampEn均高于QS期,且具有显著性差异;随着受孕后年龄（postmenstrual age,PMA）的增大,新生儿QS期的ApEn和SampEn的值均随之增加,且波动逐渐减弱,而AS期的ApEn和SampEn的值并无显著变化;绝大多数新生儿在AS期与QS期的SampEn之差高于ApEn之差。结论AS期新生儿EEG的复杂度大于QS期的复杂度;随着PMA的增大,新生儿EEG的复杂度提高,脑功能发育趋于成熟;ApEn与SampEn在表现新生儿脑电信号复杂度上趋势一致,但SampEn在区分AS与QS方面更具优势。     

精神分裂症脑电基于维数计算的时空复杂度测量

文章用非线性动力学理论，分别从两个角度对精神分裂症脑电进行了维数估计。当使用时延嵌入维数法时我们得到了明显高于对照组的相关维数，尤其在F7和FP1，这种增加更为明显，我们认为在精神分裂症患者的某些脑区复杂度要高于正常人。而当使用空间嵌入维数法时，却得到了不同的结果。这表明在精神分裂症患者的整个脑区可能存在大面积的慢波活动，使得整体的复杂度下降。最后，文章从三个不同但相关的角度，即临床症状学、神经心理学和功率谱估计，讨论了基于维数计算的复杂度测量以及他们之间的关系。认为非线性动力学理论可以成为精神分裂症临床诊断的有力辅助工具。     

抑郁症脑电特异性研究进展

抑郁症是以显著而持久的心境低落为主要症状的一组情感性精神障碍疾病, 发病率高并遍布各年龄组。随着世界经济的飞速发展、社会生活竞争的日益加剧, 全球抑郁症的发病率也快速提升, 且患病与自杀事件已呈低龄化趋势, 对抑郁症的预防诊治工作亟待重视与研究。以往抑郁诊治多依赖于主观量表评估和医生经验判定, 一致性差且误诊率、漏诊率高, 缺乏客观有效、方便快捷的定量诊断指标与方法。脑电(EEG)作为一种非侵入式探测大脑皮层神经电活动变化的研究手段, 时间分辨率高, 含有丰富的中枢神经认知生理活动信息, 是获取抑郁症大脑病理变化的客观有效方法, 且近年来抑郁症EEG特异性研究已取得部分成果。全面综述抑郁症EEG特征节律、非线性动力学参数、事件相关电位(ERP)响应, 以及脑神经网络特异性研究现状、存在问题及解决方案等进展情况, 并对未来愿景进行展望, 以期推进抑郁诊治方法研究, 助力开发更为有效的抑郁防治技术。     

MEG Characterization of Spontaneous Alpha Rhythm in the Human Brain

The present piece of research studied the spontaneous alpha rhythm of the human brain by combining the use of a whole-cortex neuromagnetometer and Magnetic Resonance Imaging. Single trials of spontaneous brain activity were recorded from ten human subjects asked to rest, with their eyes either closed or open, in relaxed wakefulness. MEG measurements were conducted over a period of one and a half years. The replicability of the results was confirmed for eight subjects out of ten. For three subjects, the alpha rhythm did not show any reductions due to the opening of the eyes. Both field map pattern and location of the estimated source were persistently stationary during each of the bursts of oscillations of the alpha rhythm. Dipoles were concentrated in clusters, indicating the existence of several spatially distributed sources. The calcarine fissure, the parieto-occipital sulcus and the surrounding occipital and parieto-occipital areas were identified as cortical sites of the brain where the alpha rhythm may originate. For four subjects, the majority of the sources were located near or in the calcarine fissure, while for five subjects, they were located near or in the parieto-occipital sulcus and for the remaining subject they were equally divided between the two generation sites.     

基于三维统计距离的异常心电节律检测方法

本文提出了一种异常心电节律的检测方法.首先重构出心电时间序列的二维相平面,并在此相平面上加入时间轴形成一个封闭的三维空间,通过比较时间序列的重构三维向量序列在此三维空间中的概率分布,得到两时间序列的差异,从而实现异常节律的检测.本方法不但能够检测出两心电信号在波形上存在的差异,并且可以检测出它们之间存在的各波(P、QRS和T波)位置的差异.本文对此方法和基于二维相平面的二维统计距离方法进行了异常节律检测的实验比较,结果表明此方法具有更好的检测效果.     

脑电中的混沌

本文简要回顾了脑电研究的历史和现状,重点评述了混沌理论在脑电研究中的意义,应用及进展,并对目前研究中存在的问题和进一步的发展方向进行了讨论。     

Alpha Enhancement and the Likelihood of an Alpha Experience

The following experiment was conducted as a preliminary investigation of the influence of the following four variables on the likelihood of having an “alpha experience” during brief alpha training: I) Subject Type (unpaid Volunteers versus Students required to participate in a psychology experiment), 2) suggestion (Alpha Experience Set or no set), 3) the degree of alpha enhancement achieved, and 4) Sex. Dependent measures were four different indexes of the degree of alpha enhancement based on an integrated amplitude measure of alpha strength, and the ratings of subjects' post-session subjective reports (SRs) on a 0 to 6 scale, where “6” is most like an alpha experience. Forty-eight (N=6) participants trained for 5 6-min enhancement periods alternated with 5 2-min rest periods, both with eyes open. None of the independent variables had significant effects on the SRs, with the exception of a three-way interaction, which was interpreted as due to the effects of an uncontrolled fifth variable: the degree of experienced success. Most important, although several persons did have alpha experiences, none of the four enhancement measures were significantly correlated with the SR ratings. In fact, all four of the correlations were negative. These results demonstrate that in our experimental situation the likelihood of an alpha experience is unrelated to the degree of alpha enhancement.     

Expectation Effects in Alpha Wave Control

In a study designed In investigate expectation artifact in EEG alpha training, Ss' actual direction of alpha change and expected direction of change were orthogonally manipulated in a 2x2 design. Twenty Ss actually enhanced alpha and 20 actually suppressed alpha (Task manipulation). Within each Tank group. 10 Ss were led to believe they enhanced alpha and 10 were told they suppressed alpha (Expectation manipulation) Five high and 5 low alpha baseline Ss were assigned to each of the 4 conditions. Ss participated in 4 alpha training sessions in a dark room, each composed or a 2-min eyes-closed baseline period followed by 20 2-min training period with a tone indicating S's EEG activity. Results, based on percent alpha change between the baseline period and the final alpha training period in each session, indicated that Ss who believed they enhanced alpha controlled alpha significantly better (more enhancement in the Task Enhancement condition and more suppression in the Task Suppression condition) than Ss who believed they suppressed alpha, Implications of expectation artifact for EEG biofeedback studies were discussed.     

Interactive Effects of Alpha Feedback and Instructional Set on Subjective State

The effects of EEG alpha feedback and instructional set were studied in 40 college students. Reported subjective experiences during feedback were examined experimentally in a factorial “drug-drug set” design. Alpha and no-alpha feedback were each paired with alpha and neutral instructions, in order to observe the individual and combined effects of alpha activity and instructional set. The results showed that for an “alpha experience” to occur, both alpha activity and alpha set are necessary; neither alone is sufficient. Theoretical considerations based on the Schachter and Singer (1962) drug model and some implications for alpha feedback research are discussed.     

Nonlinear Forecasting Measurements of the Human EEG During Evoked Emotions

Forecasting ability applied to a single EEG time sequence may quantify loss of memory of past brain states. This fundamental property of complex dynamical systems could prove to be an important measure of current brain states. The present study examined nonlinear forecasting (or nonlinear predictability) estimates of the scalp-recorded EEG in 76 healthy volunteers in response to emotionally charged (negative, positive and control neutral) video-clip stimuli. EEG was recorded from 18 sites (10-20 system). The obtained results indicate that the negative emotional impact led to a more predictable EEG dynamics, compared with neutral or positive emotional video content, and this effect was restricted to the posterior cerebral sites. The studied signatures of EEG dynamics succeed also in specific discrimination between effects of positive and negative film categories: significantly more predictable dynamics over posterior cerebral sites in response to negative film category was accompanied by enhanced predictability in answer to positive film category over frontocortical loci. It is concluded that these findings suggest the association of basic cortical nonlinear mechanisms with the specific physiological processes of emotional processing.     

Occipital Alpha and the Attributes of the "Alpha Experience"

The present research was designed to study to what extent occipital alpha strength is related to five subjective dimensions that are associated with the “alpha experience.” These are (1) the degree of oculomotor processing, (2) the degree of sensory awareness, (3) the degree of body awareness, (4) the deliberateness of thought, and (5) the pleasantness of emotional state. One experimental group of 8 persons was run for each of the above five dimensions. First, while an integrated amplitude measure of occipital alpha strength was recorded, our research participants practiced two “simple awareness techniques” (without feedback) corresponding to the two poles of their group's dimension. Later they were given the task of associating their two “awareness techniques” with occipital alpha strength by means of feedback-augmented alpha enhancement and suppression. The results showed that only the first two dimensions—the degree of oculomotor processing and the degree of sensory awareness—are significantly related to occipital alpha strength. These findings support the notion that the “alpha experience” as a whole is not intrinsically or directly associated with enhanced occipital alpha strength, and that occipital alpha strength is a direct function of only oculomotor processing.     

HRV非线性动力学分析的动物实验初步研究

采用非线性动力学分析方法,观察了交感,迷走神经单独作用和冠状动脉狭窄时,非线性动力学参数的改变,以探讨非线性动力学参数所反映的心脏生理功能和心脏电生理学意义。