EEG in Children: Periodometric Analysis,Typology, and Age Peculiarities

We carried out a computer analysis of the EEG of 169 healthy schoolchildren (6 to 17 years old) with the use of a periodometric approach allowing us to obtain a number of quantitative indices that characterize the temporal structure of the analyzed EEG segment (histogram of distribution of the frequencies of EEG oscillations within the analyzed time period, indices of the different rhythms, and matrix of the probabilities of conversion from waves of one frequency range to waves of other ranges). We demonstrated that data of the periodometric analysis can be used for objective classification of EEG patterns. In children of different age groups, five types of background EEG activity were classified and described; we also demonstrated that the intragroup frequencies of these EEG types vary in healthy children with age. We discuss the advantages and disadvantages of the periodometric analysis of EEG, as well as the prospects and expediency of use of this analysis in physiological studies and in clinics.     

Parameter Estimation Methods for Single Neuron Models

With the advancement in computer technology, it has become possible to fit complex models to neuronal data. In this work, we test how two methods can estimate parameters of simple neuron models (passive soma) to more complex ones (neuron with one dendritic cylinder and two active conductances). The first method uses classical voltage traces resulting from current pulses injection (time domain), while the second uses measures of the neuron's response to sinusoidal stimuli (frequency domain). Both methods estimate correctly the parameters in all cases studied. However, the time-domain method is slower and more prone to estimation errors in the cable parameters than the frequency-domain method. Because with noisy data the goodness of fit does not distinguish between different solutions, we suggest that running the estimation procedure a large number of times might help find a good solution and can provide information about the interactions between parameters. Also, because the formulation used for the model's response in the frequency domain is analytical, one can derive a local sensitivity analysis for each parameter. This analysis indicates how well a parameter is likely to be estimated and helps choose an optimal stimulation protocol. Finally, the tests suggest a strategy for fitting single-cell models using the two methods examined.     

突触功能障碍大鼠模型EE G 频域特征

本文旨在探讨突触功能障碍大鼠模型在额叶、颞叶和海马这些与认知功能有关的脑区EEG频域特征。先用海马CA1区Aβ1-40加微量注射法制备突触功能障碍模型,用Morris水迷宫行为学测试系统检测其学习记忆能力;然后记录上述脑区的EEG并做频谱分析。结果显示：（1）模型组在第3,4、5、6训练时间段的平均逃避潜伏期较正常组明显延长,和第2训练时间段的相比较,正常组第5训练时间段平均逃避潜伏期明显缩短,模型组到第7训练时间段平均逃避潜伏期开始明显缩短（P〈0．05）;撤去平台后,模型组在原平台所在象限的时间百分比明显降低（P〈0．05）。（2）模型组的EEG表现为α节律慢化,功率下降,其主峰频率左移2Hz,并且额叶、颞叶和海马的δ波和θ波功率不同程度地增高。由此Aβ1-40微量注射法成功制备了突触功能障碍大鼠模型。该模型大鼠的学习记忆能力降低,其频谱特征表现为α节律慢化,功率下降或消失,慢波（δ波和θ波）活动增多,功率不同程度地增高。这些与阿尔茨海默病（Alzheimer’s disease,AD）的EEG一致,可为以后对突触功能障碍时受累皮层进行深入的可塑性和神经再生的研究提供电生理基础。     

Dielectric properties of developing rabbit brain at 37 degrees C

The dielectric properties of developing rabbit brain were measured at 37 degrees C between 10 MHz and 18 GHz using time domain and frequency domain systems. The results show a variation with age of the dielectric properties of brain. An analysis of the data suggests that the water dispersion in the brain of newly born animals can be represented by a Debye equation. This dispersion increases in complexity with age, and there is evidence of a smaller additional relaxation process centered around 1 GHz. It is concluded that the principal contribution to this subsidiary dispersion region arises from water of hydration.     

Dynamics of EEG potentials at the beginning of a series of EEG-feedback sessions

We studied changes in the amplitudes of event-related EEG potentials (ERPs) and power spectra of background EEG in the course of a series of EEG-feedback sessions directed toward an increase in the ratio of powers of the α vs θ rhythms. The examined group included 70 volunteers divided into an experimental group (n = 37) and a control group (n = 33). The intensity of acoustic white noise overlapping the musical background served as a feedback signal; it became lower with increase in the above ratio, while in the control group it remained constant. The EEG potentials were recorded from C3 and C4 leads. The ERPs were recorded within a paradigm of measuring time intervals. Within a series of EEG-feedback sessions, the α/θ ratio decreased somewhat both in the control and experimental groups, but in subjects of the latter group this decrease was less significant, and the mean intragroup index became significantly greater than the respective value in the control group after the end of the third session. The EEG-feedback sessions also resulted in significant increases in the amplitudes of early components of the readiness potential in both hemispheres and in the amplitude of the contingent negative variation in the right hemisphere. We conclude that, in most healthy subjects, at least three sessions of α/θ training are necessary to form an effective series providing considerable changes in the pattern of EEG potentials. Neirofiziologiya/Neurophysiology, Vol. 39, No. 1, pp. 88–98, January–February, 2007.     

Effects of 45-Hz magnetic fields on the functional state of the human brain

The influence of sinusoidal 45-Hz magnetic fields on the brain functions of 20 volunteers was investigated in a double-blind study using spectral analysis of EEG and measurements of Omega potentials and reaction time (RT). The field strength was 1,000 A/m (1.26 mT) and the duration of exposure was 1 h. Ten volunteers were exposed to a continuous field and ten received an intermittent exposure (1 s on/1 s off). Each person received one real and one sham exposure. One half of the volunteers got the real exposure first and the sham treatment after at least 24 h. For the rest, the sequence was inverse. The measurements of EEG, omega potentials and RT were performed before and after each exposure. Several statistically significant changes were observed, most of them after intermittent exposure. In the EEG, an increase of alpha (7.6–13.9 Hz) activity and a decrease of delta (1.5–3.9 Hz) activity were observed. β waves (14.2–20 Hz) increased in the frontal derivations as did the total power in occipital derivations. The mean and peak frequencies of EEG increased mainly in the frontal derivations. No direct effects on RT were seen. Learning to perform the RT test (decrease of RT in repeated trials), however, seemed to be affected by the exposure. The persons who received real exposure first learned more slowly than those who got sham exposure first. Further experiments are necessary to confirm the findings and for understanding the mechanisms of the effects. © 1993 Wiley-Liss. Inc.     

Measuring-off of Time Intervals: Correlations Between Peculiarities of Their Estimation and Parameters of EEG Phenomena, and Influence of the Subjects' Personality Features

In 76 healthy persons (right-handed men and women), we recorded background EEG and event-related potentials from the C3 and C4 sites; tests were performed within the framework of an experimental situation requiring internal measuring-off of the time intervals. To limit the interval, the tested person had to push a button; he/she did not know the precise value of the interval, which was preset by the experimenter, and was informed only of the lower and upper limits of this interval, 17 to 23 sec. The person obtained information about the coincidence/noncoincidence of the measured-off and preset intervals via visual feedback; the respective signal was presented 2 sec after measuring-off had been completed. In the case where the intervals coincided with each other, the person should confirm this by pushing the button next time (confirming push). We characterized the parameters of the measured-off time interval by the following indices: (i) measuring-off efficacy (accuracy of fitting the preset interval), (ii) estimation tendency (measured-off interval/preset standard interval ratio), and (iii) coefficient of variation (CV) of the measured-off interval. Features of the subject's personality were estimated using Eysenck's (PEN) and Cattell's (16PF) questionnaires. We found correlations of the powers of the background EEG rhythms (beta1, beta2, and alpha/theta ratio) and characteristics of the measured-off time interval. In addition, we observed significant positive correlations between the estimation tendency and extraversion index and between CV of the interval and urge toward domination and protension indices. Negative correlations were observed between the measuring-off efficacy and protension (suspiciousness), between the estimation tendency and anxiety, and between the CV of the interval and age of the subjects. We support the conclusion that correlations between the patterns of EEG potentials, peculiarities of measuring-off of the time interval, and psychological features of the personality are to a noticeable extent mediated by the individual specificity of the neurodynamics.     

铅染毒大鼠脑电信号的分形特性研究

利用混沌时间序列的分析方法,对铅中毒情况下的大鼠的脑电波进行了测试和分析,求出了其分形维数。从研究结果中得出了铅中毒情况与脑电信号的分形维数之间的关系,结果表明,铅中毒会引起脑电信号的分形维数的显著变化。通过这一工作,能够为临床上重金属中毒的早期诊断提供新的方便、灵敏的指标。     

The dynamics of EEG entropy

The scaling properties of human EEG have so far been analyzed predominantly in the framework of detrended fluctuation analysis (DFA). In particular, these studies suggested the existence of power-law correlations in EEG. In DFA, EEG time series are tacitly assumed to be made up of fluctuations, whose scaling behavior reflects neurophysiologically important information and polynomial trends. Even though these trends are physiologically irrelevant, they must be eliminated (detrended) to reliably estimate such measures as Hurst exponent or fractal dimension. Here, we employ the diffusion entropy method to study the scaling behavior of EEG. Unlike DFA, this method does not rely on the assumption of trends superposed on EEG fluctuations. We find that the growth of diffusion entropy of EEG increments of awake subjects with closed eyes is arrested only after approximately 0.5 s. We demonstrate that the salient features of diffusion entropy dynamics of EEG, such as the existence of short-term scaling, asymptotic saturation, and alpha wave modulation, may be faithfully reproduced using a dissipative, first-order, stochastic differential equation—an extension of the Langevin equation. The structure of such a model is utterly different from the “noise+trend” paradigm of DFA. Consequently, we argue that the existence of scaling properties for EEG dynamics is an open question that necessitates further studies.     

Statistical Comparison of Band Spectral Power: An Aid in Stochastical Analysis of Brain Electrical Activity Part 1: Approximation of the distribution of broad band power by a χ2-distribution

In this study the distribution of estimated broad band spectral power is evaluated. Under weak assumptions it is possible to appropriate this distribution by a χ2-distribution and to construct tolerance intervals with great statistical accuracy. The theoretical results implicate a new methodical basis for statistical comparison of spectral parameters in EEG analysis.     

耳蜗电位的持续反应与其中单个脉冲的反应

研究了豚鼠耳蜗电位中持续反应与其中的单个脉冲反应的关系。由于听学系统存在着非线性,因此仅仅知道由单个短声诱发的耳蜗电位脉冲反应还无法预测一串等间隔重复短声诱发的持续反应。然而,等间隔重复短声串中第5个以后的每个短声受前面所有短声的掩蔽都相同,诱发的反应都相同,因此持续反应的稳态部分可以由掩蔽作用达到饱和时单个短声的反应通过延时相加得到。本文在时间域和频率域上定量地证明了这点。     

Terahertz Pulsed Imaging of Skin Cancer in the Time and Frequency Domain

Terahertz Pulsed Imaging(TPI) is a new medical imaging modality forthe detection of epithelial cancers. Overthe last two years this technique has beenapplied to the study of in vitrobasal cell carcinoma (BCC). Usingtime-domain analysis the contrast betweendiseased and normal tissue has been shownto be statistically significant, andregions of increased terahertz (THz)absorption correlated well with thelocation of the tumour sites in histology.Understanding the source of this contrastthrough frequency-domain analysis mayfacilitate the diagnosis of skin cancer andrelated skin conditions using TPI. Wepresent the first frequency-domain analysisof basal cell carcinoma in vitro,with the raw power spectrum giving aninsight into the surface features of theskin. Further data manipulation is requiredto determine whether spectral informationcan be extrapolated at depth. These resultshighlight the complexity of working inreflection geometry.     

The evolutionary relationship of the domain architectures in the RhoGEF-containing proteins

Domain insertions and deletions lead to variations in the domain architectures of the proteins from their common ancestor. In this work, we investigated four groups of the RhoGEF-containing proteins from different organisms with domain architectures RhoGEF-PH-SH3, SH3-RhoGEF-PH, RhoGEF-PH, and SH3-RhoGEF defined in the Pfam database. The phylogenetic trees were constructed using each individual domain and/or the combinations of all the domains. The phylogenetic analysis suggests that RhoGEF-PH-SH3 and SH3-RhoGEF-PH might have evolved from RhoGEF-PH through the insertion of SH3 independently, while SH3- RhoGEF of proteins in fruit fly might have evolved from SH3-RhoGEF-PH by the degeneration of PH domain.     

正常小鼠高频心电图时域值和功率谱的研究

本文用南京新博公司生产的ＮＨＥ－１０００型心电高频信息检测分析仪研究了正常小鼠（昆明种）高频心电图（ＨＦ－ＥＣＧ）的时域值和ＱＲＳ波群的功率谱。主要结果如下（以正导为例,－Ｘ±ＳＤ）：心率６０３±８８次／ｍｉｎ（ｎ＝７４）;Ｐ－Ｒ间期相对较长。为３４．９±４．７ｍｓ（ｎ＝５８）,占心动周期的３４．９±４．９％,这与人类有很大的不同;ＱＲＳ波宽９．２±１．２ｍｓ,占心动周期的９．２±１．４％（ｎ＝７４）,这一结果与以前的文献报道相差较大。Ｔ波宽１０．３±３．２ｍｓ,占心动周期的１０．３±３．２％;Ｑ－Ｔ间期１９．４±３．２ｍｓ,占心动周期的１９．５±３．６％;ＱＲＳ波群峰－峰值（Ｖｐ－ｐ）为１．４５６±０．４８０ｍＶ;Ｔ波高０．３３６±０．１１５ｍＶ;７３只动物Ⅱ导联高频切迹总数只有３个,扭挫２６个。Ⅱ导联ＱＲＳ波群的功率谱特点：０—８０Ｈｚ的相对能量为４５．４８±１５．３２％;８０—２００Ｈｚ为４３．９７±９．９５％;２００—３００Ｈｚ为８．８９±７．３８％;３００—１０００Ｈｚ为１．６６±２．７４％。     

基于时频分析检测EEG中癫痫样棘/尖波的方法

提出了一种基于Ｃｈｏｉ－Ｗｉｌｌｉａｍｓ分布检测ＥＥＧ中癫痫样棘波／尖波的方法。该方法通过计算ＥＥＧ信号的时频分布,得到一段信号在各个时刻上沿频率方向上的能量分布。这种能量分布相当于一种瞬时频谱,反映了ＥＥＧ信号在局部时间范围里的波形特征。以一段ＥＥＧ信号在各个时刻的瞬时频谱的平均作为这段脑电的背景信号频谱,通过计算每一时刻的瞬时频谱与背景信号频谱之间的频谱差,检测这段信号中的棘波／尖波。对临床Ｅ