The method of correlation analysis of EEG synchronism and its possibilities

A new method for estimation of EEG synchronism based on the analysis of correlation between amplitude modulation processes (envelopes) is considered. The efficiency of the given method is shown in different aspects: for detection of a topographical pattern, for analysis in frequency domains, for estimation of stability of the functional state and its changes, for detection of heterogeneous subgroups of subjects and outliers, for analysis of individual and group distinctions and distinctions in synchronism between symmetrical pairs of leads and hemispheric asymmetry, and for classifying division between mentally healthy subjects and deviations of schizophrenic spectrum with reliability approaching 100%.     

EEG source identification: frequency analysis during sleep

This article deals with a new approach in sleep characterization that combines EEG source localisation methods with standard frequency analysis of multielectrode EEGs. First, we describe the theoretical methodology and the benefits that we get from a three-dimensional image (LORETA) of the cerebral activity related to a frequency band. Then, this new application is used as signal-processing technique on sleep EEG recordings obtained from young male adults using four frequency bands (delta 0.5-3.5 Hz, theta 4.0-7.5 Hz, alpha 8.0-12.5 Hz and beta 13.0-32.0 Hz) in different sleep stages. Finally, we show that the obtained results are highly consistent with other physiological assessments (standard EEG mapping, functional magnetic resonance imaging, etc.), but give us more realistic additional information on the generators of electromagnetic cerebral activity.     

Multichannel EEG analysis of respiratory evoked-potential components during wakefulness and NREM sleep

Airway occlusion in awake humans producesa somatosensory evoked response called the respiratory-related evokedpotential (RREP). In the present study, 29 channel evoked-potentialrecordings were obtained from seven men who were exposed to 250-msinspiratory airway occlusions during wakefulness, stage 1, stage 2, andslow-wave sleep. The RREP recorded during wakefulness was similar toprevious reports, with the unique observation of an additionalshort-latency positive peak with a mean latency of 25 ms. Short-latencyRREP components were maintained in non-rapid-eye-movement (NREM) sleep. The clearly seen N₁ vertex andlate positive complex components during wakefulness were markedlyattenuated during NREM sleep, and two large negative components(N₃₀₀ andN₅₅₀) dominated the sleep RREP.These findings indicate the maintenance of central nervous systemmonitoring of respiratory afferent information during NREM sleep,presumably to facilitate protective arousal responses topathophysiological respiratory phenomena.

     

Concerning the amplitude modulation of the human EEG

Amplitude-modulated processes can be formally presented as a product of two or more sinusoids. This makes it possible to study them by means of analysis of multiplicative phenomena using the Fast Fourier Transform (FFT). To assess the contribution of amplitude EEG modulation to the dynamic of electrical activity of the human brain, the results of the FFT of simulated signals obtained by multiplication of oscillatory processes with different parameters were compared with the results of the FFT of a single EEG recording from a subject at rest. We studied the temporal dynamics of spectral components calculated with different spectral resolution under similar conditions for real and simulated signals. An attempt was made to analyze and interpret the amplitude-modulated EEG processes using the additive properties of the FTT. It was shown that processes of amplitude modulation are present in electrical brain activity and determine the synchronism of changes in time in the majority of frequency components of the EEG spectrum. The presence of the amplitude modulation in bioelectrical processes is of a fundamental nature, since it is a direct reflection of the control, synchronization, regulation, and intersystem interaction in the nervous and other body systems. The study of this modulation gives a clue to the mechanisms of these processes.     

Experience in using correlation analysis for evaluating the synchronism of the fluctuations in the level of infectious morbidity in individual areas

The possibility of using correlation analysis for evaluating the synchronism of changes in infectious morbidity rate on different territories was studied. The study demonstrated that the intensity of correlative relationships was mainly influenced by the degree of manifestation and the direction of prolonged tendencies in the changes of infectious morbidity on the territories under study. The presence of prolonged pronounced tendencies towards growth or decrease in the compared curves characterizing prolonged morbidity dynamics was found to limit the use of correlation analysis for the evaluation of synchronism of changes in morbidity rate.     

Comparative frequency analysis of single EEG - Evoked potential records

The aim of this study is to expand our previous results on the important relation between the spontaneous EEG and EPs (Basar et al. 1976 a,b). These previous results were obotained from single recordings of combined EEG-EP epochs by comparing the rms-magnitude of thespontaneous EEG prior to stimulus with the maximal amplitude of the response. Both were pass-band-filtered by means of the response adaptive filter, determined according to the band limits of the studied selectivity channel. In this earlier analysis, although the relation between the amplitudes of EEG and EP components in various frequency channels could be determined in the time domain, no exact statement could be made (1) on possible relations between the frequency distributions of spontaneous and evoked activities of a given brain centre, nor (2) on the phase relationships between the electrical activities of various brain structures. These gaps are filled in our present report with the further analysis of the EEG-EPograms simultaneously recorded from 5 different brain structures.     

Feedback delay and amplitude threshold and control of the occipital EEG

Six normal adults looked at 12 color transparencies that were presented 30 times each in response to the occurrence of alpha in the occipital EEG and that were not presented when no-alpha occurred. The time delay between the occurrence of recorded EEG alpha and the feedback stimulus was systematically varied, as was the threshold value of alpha amplitude required for feedback stimulus to occur. As time delay increased, the replicative reliability of the temporal association between alpha and the visual stimulus decreased. The measures of the EEG response were: the mean durations of alpha and of no-alpha durations ; an estimate of random scatter or variability in a single trial (S _e ); and the ratio of these , which is the reciprocal of the coefficient of variation. The latter ratio defines control of the EEG response. Control was greatest for the minimum feedback delay (.25 sec) and a feedback threshold of 25% of the maximum peak alpha amplitude recorded under a prior eyes-closed. resting condition. Control of the EEG decreased as time delays increased and at lower and higher feedback thresholds. It was proposed that the measurement of control for various combinations of values of relevant experimental parameters could be used to select that combination which gave the best control. This optimum combination of values of parameters could be chosen for astandardized method.This research was supported in its entirety by the Veterans Administration Medical Research Program.     

Comparative analysis of plastomes in Oxalidaceae: Phylogenetic relationships and potential molecular markers

The wood sorrel family, Oxalidaceae, is mainly composed of annual or perennial herbs, a few shrubs, and trees distributed from temperate to tropical zones. Members of Oxalidaceae are of high medicinal, ornamental, and economic value. Despite the rich diversity and value of Oxalidaceae, few molecular markers or plastomes are available for phylogenetic analysis of the family. Here, we reported four new whole plastomes of Oxalidaceae and compared them with plastomes of three species in the family, as well as the plastome of Rourea microphylla in the closely related family Connaraceae. The eight plastomes ranged in length from 150,673 bp (Biophytum sensitivum) to 156,609 bp (R. microphylla). Genome annotations revealed a total of 129–131 genes, including 83–84 protein-coding genes, eight rRNA genes, 37 tRNA genes, and two to three pseudogenes. Comparative analyses showed that the plastomes of these species have minor variations at the gene level. The smaller plastomes of herbs B. sensitivum and three Oxalis species are associated with variations in IR region sizes, intergenic region variation, and gene or intron loss. We identified sequences with high variation that may serve as molecular markers in taxonomic studies of Oxalidaceae. The phylogenetic trees of selected superrosid representatives based on 76 protein-coding genes corroborated the Oxalidaceae position in Oxalidales and supported it as a sister to Connaraceae. Our research also supported the monophyly of the COM (Celastrales, Oxalidales, and Malpighiales) clade.     

完全睡眠剥夺对大脑注意网络冲突效应和脑电样本熵的影响*

目的: 本研究分析睡眠剥夺对个体选择性注意网络冲突效应和脑电样本熵的影响,探讨睡眠剥夺对大脑注意网络的影响。方法: 25名健康受试者参与36 h完全睡眠剥夺试验。试验于当天9:00开始,于次日21:00结束,试验采用自身前后对照设计。受试者在睡眠剥夺前后分别完成注意网络任务,同步采集受试者的脑电图。用脑电样本熵算法分析脑电图的delta、theta、alpha、beta和gamma频率段的脑电复杂度并对比各频段脑电样本熵在睡眠剥夺前、后的变化。结果: 同睡眠剥夺前比较,睡眠剥夺后与受试者的注意网络冲突效应密切相关的反应时显著下降(P＜0.01),正确率显著增加(P＜0.01)。脑电样本熵分析发现在beta频率段,与注意网络冲突控制相关的脑电样本熵值在睡眠剥夺后明显增大(P＜0.01)。其余脑电频率段脑电样本熵未发现显著差异。结论: 表明完全睡眠剥夺后大脑的注意网络冲突效应降低,表明睡眠剥夺后执行冲突控制能力的下降。     

Comparative analysis of genetic relationships in barley based on RFLP and RAPD markers

Genetic relationships have seldom been analyzed with different types of molecular markers in order to compare the information provided by each marker class. We investigated genetic relationships among nine barley cultivars using separate cluster analyses based on restriction fragment length polymorphisms (RFLPs) and random amplified polymorphic DNAs (RAPDs). Genomic DNA restricted with three enzymes and hybridized with 68 probes revealed 415 RFLPs (74.2% of all bands). Among the 128 primers used for RAPD analysis, 100 provided a reproducible profile, 89 of which revealed 202 polymorphic and 561 monomorphic bands (26.5 and 73.5%, respectively). A nonrandom distribution of 62 RAPDs with a tendency to cluster near centromeric regions was produced when these RAPDs were mapped using 76 doubled-haploid lines derived from a cross between two of the nine cultivars. The correlation between the RFLP and RAPD similarity matrices computed for the 36 pairwise comparisons among the nine cultivars was equal to 0.83. The dendrograms obtained by cluster analyses of the RFLP and RAPD data differed. These results indicate that in barley the information provided by RFLPs and RAPDs is not equivalent, most likely as a consequence of the fact that the two marker classes explore, at least in part, different portions of the genome.