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.     

肺动脉血流时间间期法评估肺动脉压

为评价肺动脉血流时间间期法评估肺动脉压的价值,本文观察了37例左向右分流先天性心脏病患者。在相同体位及取样容积位置下测量心室射血前期(PEP)、射血时间(ET)、加速时间(AT)、加速度(ACC)、F[F=PEP/(ATET)];计算肺动脉/主动脉血流时间间期比(FPA/FAO),并以各项比例系数与肱动脉压(BAP)的乘积作为肺动脉压的估测值。结果显示:肺动脉/主动脉血流时间间期比与右心导管估测的肺动脉收缩压(PASP)、平均压(PAMP)取得了较好的相关性(r分别为0.84、0.81);ACC次之(r分别为0.72、0.65);PEP/AT较差(r分别为0.53、0.50)。提示:肺动脉/主动脉血流时间间期比为无创定量评估肺动脉压的最佳方法。     

Computation of Time-Specified Tolerance Intervals for Hybrid Time Series with Nonequidistant Sampling,Illustrated for Plasma Growth Hormone

The ideal reference interval for a variable of clinical interest would be specific for all deterministic factors affecting that variable, including the time of sampling in relation to biological rhythms. In particular, growth hormone is characterized in children by circadian and ultradian variability, with high peaks of secretion occurring mainly during sleep. For clinical applications, the use of tolerance intervals has been recommended, and they should substitute, whenever possible, for prediction limits. In the case of hybrid data (time series of data collected from a group of subjects), such a tolerance interval could be very difficult to determine following a parametric approach similar to the procedure used for the computation of prediction intervals, especially when consideration of both within-subjects and among-subjects variances is wanted. Accordingly, we have developed a nonparametric method for the computation of such tolerance intervals. Because the method is based on bootstrap techniques, it does not require the assumption of normality or symmetry in the data and is also more appropriate when dealing with small samples. The method was used to establish time-qualified reference limits for a series of growth hormone sampled around the clock in groups of prepubertal children differentiated according to stature. The use of these tolerance intervals may eliminate many false-positive and false-negative diagnoses that might be obtained when relying on time-unspecified single samples. The provision of such tolerance limits introduces time-specification and time-structure evaluation into prevention, diagnosis, and treatment of growth disorders. (Chronobiology International, 14(4), 409–425, 1997)     

血雉的产卵时间和产卵间隔

鸟类的产卵时间和产卵间隔因种而异 ,并会影响其繁殖成功。采用在巢内放置含有温度数据自动记录装置的假卵 ,通过记录其温度的变化来监测雌鸟产卵行为的方法 ,对分布于我国青藏高原森林鸟类血雉(Ithaginiscruentus)的产卵时间和产卵间隔进行了研究。结果表明 ,雌鸟每次入巢产卵的时间是在 15 :16± 2 2min (13 :30～ 18:5 1) ,产卵高峰集中在 14:0 0～ 16 :0 0 ,每次在巢中停留 (2 2± 0 2 6 )h。产卵间隔为 (46 4± 3 0 8)h ,大多数 (75 % )产卵间隔 45 8～ 48 9h。由此推测 ,血雉产卵时间较为集中很可能与避开夜行性捕食者的活动高峰有关 ;而隔天产卵则是对高原恶劣环境条件的适应。     

Scheffy's Confidence Intervals in the Models of Analysis of Covariance

Scheffe's confidence intervals for linear functions of some subvectors of a vector of parameters are presented. The considered subvectors are such that covariance matrices of their estimators are known non-negative definite matrices multiplied by unknown positive constants. This property is characteristic of the least squares estimators of vectors of main and interaction effects in the analysis of covariance models of the following experimental designs: split-block, split-plot, completely randomized two-factor design and randomized complete block design. The formulas for confidence intervals for linear functions of vectors of main or interaction effects in the designs mentioned above are given in the paper. The practical example is given as an illustration.     

Individual personality-related characteristics of event-related EEG potentials recorded in an experimental situation requiring production of time intervals

Event-related EEG potentials (ERP) were recorded from 75 tested adult men and women; recording was performed from C3 and C4 points. The experimental situation required internal counting of time intervals limited by two pushes of a button. The experimental paradigm provided a substantial level of uncertainty, and a high level of attention needed to be maintained. The tested subjects were not informed by the experimenter about the precise value of the preset time interval; they knew only its limits, 17–23 sec. The subject obtained information about the agreement or disagreement between the produced interval and its value preset by the experimenter by visual feedback signals obtained 2 sec after termination of counting; in the case of agreement the subject had to perform a confirming (third) push of the button. Pushes were preceded by readiness potentials (RP); contingent negative variation (CNV) developed before the feedback signals, and the latter were accompanied by P300 potentials. Significant positive correlations were found between the parameters of RP and P300 in both hemispheres. In general, ERP were characterized by very high interindividual variability, which in a few respects correlated with the personality-related characteristics of tested subjects evaluated by psychological testing with the use of corresponding questionnaires. In particular, under the experimental conditions used, negative correlations were observed between the RP amplitude and psychotism indices, CNV amplitude and emotional stability; CNV amplitude and extroversive features, and P300 amplitude and domination properties of a person. Positive correlations were observed between the CNV amplitude and autia factor (according to Eysenck’s PEN and Cattell’s 16 PF questionnaires). We suppose that correlations between the personal psychical features and ERP parameters are grounded in both inherited constitutional specificities of the nervous system and neurochemical/structural modifications in the brain determined by the acquired vital experience.     

Adjustment of Prediction Intervals in Nonlinear Regression

By treating the nonlinear model as if it were linear in the parameterization θ in the neighbourhood of the least squares estimate θC, two-sided nominally-q-prediction intervals can be constructed by applying the usual linear model theory. The quadratic approximation of the expected coverage of the prediction intervals is derived for a p-parameter nonlinear model. An adjustment of the nominally-q-prediction intervals is proposed. It is shown that, to the extent that quadratic approximation is adequate, the actual expected coverage of the adjusted prediction intervals is q.     

Processing of Auditory Midbrain Interspike Intervals by Model Neurons

A question central to sensory processing is how signal information is encoded and processed by single neurons. Stimulus features can be represented through rate coding (via firing rate), temporal coding (via firing synchronization to temporal periodicities), or temporal encoding (via intricate patterns of spike trains). Of the three, examples of temporal encoding are the least documented. One region in which temporal encoding is currently being explored is the auditory midbrain. Midbrain neurons in the plainfin midshipman generate different interspike interval (ISI) distributions depending on the frequencies of the concurrent vocal signals. However, these distributions differ only along certain lengths of ISIs, so that any neurons trying to distinguish the distributions would have to respond selectively to specific ISI ranges. We used this empirical observation as a realistic challenge with which to explore the plausibility of ISI-tuned neurons that could validate this form of temporal encoding. The resulting modeled cells—point neurons optimized through multidimensional searching—were successfully tuned to discriminate patterns in specific ranges of ISIs. Achieving this task, particularly with simplified neurons, strengthens the credibility of ISI coding in the brain and lends credence to its role in auditory processing.     

The Analysis of the Geometric Structure of the Delayed Time Used in the Embedding Process in Predicting Chaotic Time Series

1IntroductionForaphysicssyStem,onemayonlyobtainapieceOfiofo~ionabbotitSd~edPaces.In~cases,oneorat~SeveralvariableSoftheSyStemismeaSUledasthesyStemevolvesinaclodoftime.ExamplesarethemeaSuredtetnperatUle,blabsP~ofahumanthey;concentrationsof~entsinachendcalreaction,componentsofthevelvetyOfthefluidincertaindirectionSandthefluctuationOfthePriceinasacmarket.AllthesemeasureddatapresentasatIme~esxl,xZ,'.,xj,inwhichthesuhiindexpreSentSthetimeSampledregUlarlybyatimenitedr.Thequestionhereishow…     

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.     

视频脑电图与常规脑电图在癫痫患儿诊断和定位中的应用价值对比研究

目的:比较视频脑电图(VEEG)与常规脑电图(REEG)在癫痫患儿诊断和定位中的应用价值,为癫痫诊断提供依据。方法:对2014年1月~2016年12月间本院收治的有临床症状拟诊断为癫痫的102例患儿的临床资料进行回顾性分析,比较VEEG与REEG两种方法痫样放电检出率、临床发作检出率、睡眠期检出率以及痫灶定位中的诊断价值。结果:102例患儿中,VEEG检测到痫样放电80例,痫样放电检出率为78.43%,REEG检测到痫样放电42例,痫样放电检出率为41.18%,VEEG痫样放电检出率显著高于REEG(P0.05)。VEEG临床发作检出率为48.75%,显著高于REEG临床发作检出率的14.29%(P0.05)。VEEG检测出睡眠期痫样放电检出率为46.25%,高于觉醒期痫样放电检出率的12.50%(P0.05)。VEEG睡眠期各电图时相痫样放电检出率比较,组间差异均有统计学意义(均P0.05)。根据VEEG确定39例癫痫患儿痫样放电起源部位为额区9例、颞区10例、额颞区9例、枕区4例、中央区4例、颞枕后区3例。结论:VEEG对癫痫患儿的脑部痫样放电检出率和临床发作检出率均明显优于REEG,同时定位诊断效果更优,值得临床推广应用。     

Analysis of inphase interaction pattern in EEG

Inphase interactions among EEG signals recorded using eight electrodes were investigated. The inphase interaction parameters are presented in two ways: (1) matrix form in which the number of inphase interactions are tabulated; and (2) histogram in which the number of inphase interactions are plotted pair-wise between two sites as a function of phase delays in milliseconds. The highest number of interactions occurs between 0 and 8 ms in normal brains. The values of interaction parameters are enhanced by various activities. For example, inphase interaction parameters increase in the motor area in the right hemisphere if the EEG is recorded during repeated left fist clenching. Inphase interactions are drastically altered by the presence of a tumor. We studied the inphase interactions of the EEG of a patient having an occipital tumor. The interaction parameters are greatly diminished in this area, indicating a severe impairment of neuronal communications between both hemispheres in the occipital region. The confidence limits of the changes in inphase interaction parameters during fist clenching are tested statistically using the Student's t test. The test shows that the interaction parameters increase, in general, with 1–5% confidence limits in respective cortex areas as a result of fist clenching.     

Modifications of EEG Related to Repeated Static Grasp Efforts Developed by the Hand in Humans

The characteristics of EEG recorded before, in the course, and after three sequential static grasp efforts developed by the right hand were analyzed in 14 healthy volunteers of both sexes, 19 to 56 years old. The grasps were 3 min long, and intervals between the sequential trials were 5 min long. The mean intensity was, as a rule, the greatest in the first trial and decreased, because of fatigue, in the second and third trials. In the course of the grasp effort, significant (P ≤ 0.05) or close to significant decreases in the spectral power were observed in all trials within the alpha2 subrange in some frontal, central, and central/temporal leads. This reaction of desynchronization of alpha2 oscillations probably reflects activation of the sensorimotor cortical zones. Within the above period, the power of alpha2 oscillations increased in the occipital leads. In a few leads of the frontal group, the powers of delta, theta1, theta2, and alpha1 oscillations increased significantly (P < 0.05) in the course of the first trial. Such reaction was not observed in the second and third trials, while the powers of delta and alpha1 ranges increased in the occipital sites (P < 0.05). The powers of delta and theta oscillations increased, as compared with the control values, after the second and third grasps. Such specific EEG modifications in sequential trials can be related to the actions of a novelty factor in the first trial and a fatigue factor in the subsequent trials. The coherence coefficient (CC) of alpha and beta oscillations for symmetric leads usually increased in the course of the grasp. This effect reached a significance level (P < 0.05) for alpha2 oscillations in central, posterotemporal, parietal, and occipital pairs. The CC for beta2 oscillations increased in both temporal lead pairs. A drop in the interhemisphere coherence was more typical of the delta and theta1 ranges. Therefore, changes in the CC values show that the structure of interhemisphere interaction undergoes modifications with the development of the grasp static efforts. Neirofiziologiya/Neurophysiology, Vol. 37, No. 4, pp. 362–371, July–August, 2005.     

Correlations between the psychological peculiarities of an individual and the efficacy of a single neurofeedback session (by the EEG characteristics)

Modifications of different EEG rhythms induced by a single neurofeedback session (by the EEG characteristics) directed toward an increase in the ratio of the spectral powers (SPs) of the α vs θ oscillations were compared with the psychological characteristics of the tested subjects (the group included 30 persons). A generally accepted neurofeedback technique was used; the intensity of acoustic white noise served as the feedback signal. EEG potentials were recorded from the C3 and C4 leads. Psychological testing was carried out using Eysenck’s (EPQ), Rusalov’s (OST), and (16 PF) questionnaires. The directions of changes in the SPs of EEG frequency components were found to significantly correlate with some individuality-related peculiarities of the tested subjects. The SP of the δ rhythm correlated with the EPQ scale “neuroticism,” OST scale “social plasticity,” and 16 PF factors H (“parmia”), I (“premsia”), and Q₃ (“self-control of behavior”). The SP of the θ component demonstrated correlations with the OST scales “ergisity,” “plasticity,” and “social temp” and with 16 PF factors M (“autia”), Q₄ (“frustration”), and Q1 (“exvia”). The SP of the α rhythm correlated with 16 PF factors Q₃ (“self-control of behavior”), G (“strength of superEgo”), O (“hypothymia”), L (“protension”), and N (“shrewdness”). The SP of the β rhythm correlated with the OST scale “emotionality,” while that of the γ rhythm showed correlations with the 16 PF indices L (“protension”) and M (“autia”). Changes in the ratio of the α vs θ SPs correlated with the EPQ scale “neuroticism.” Thus, our data confirm the statement that a high individual variability of the results of a single (first in the series) neurofeedback session is to a great extent related to peculiarities of the individual psychological pattern of the subject. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 239–247, May–June, 2006.     

The Effect of Activity on the Waking Temperature Rhythm in Humans

Nine healthy female subjects were studied when exposed to the natural light-dark cycle, but living for 17 “days” on a 27h day (9h sleep, 18h wake). Since the circadian endogenous oscillator cannot entrain to this imposed period, forced desynchronization between the sleep/activity cycle and the endogenous circadian temperature rhythm took place. This enabled the effects of activity on core temperature to be assessed at different endogenous circadian phases and at different stages of the sleep/activity cycle. Rectal temperature was measured at 6-minute intervals, and the activity of the nondominant wrist was summed at 1-minute intervals. Each waking span was divided into overlapping 3h sections, and each section was submitted to linear regression analysis between the rectal temperatures and the total activity in the previous 30 minutes. From this analysis were obtained the gradient (of the change in rectal temperature produced by a unit change in activity) and the intercept (the rectal temperature predicted when activity was zero). The gradients were subjected to a two-factor analysis of variance (ANOVA) (circadian phase/ time awake). There was no significant effect of time awake, but circadian phase was highly significant statistically. Post hoc tests (Newman-Keuls) indicated that gradients around the temperature peak were significantly less than those around its trough. The intercepts formed a sinusoid that, for the group, showed a mesor (±SE) of 36.97 (±0.12) and amplitude (95% confidence interval) of 0.22°C (0.12°C, 0.32°C). We conclude that this is a further method for removing masking effects from circadian temperature rhythm data in order to assess its endogenous component, a method that can be used when subjects are able to live normally. We suggest also that the decreased effect of activity on temperature when the endogenous circadian rhythm and activity are at their peak will reduce the possibility of hyperthermia.     

Effects of electromagnetic field emitted by cellular phones on the EEG during an auditory memory task: a double blind replication study

The effects of electromagnetic fields (EMF) emitted by cellular phones on the event related desynchronization/synchronization (ERD/ERS) of the 4-6, 6-8, 8-10, and 10-12 Hz electroencephalogram (EEG) frequency bands were studied in 24 normal subjects performing an auditory memory task. This study was a systematic replication of our previous work. In the present double blind study, all subjects performed the memory task both with and without exposure to a digital 902 MHz field in a counterbalanced order. We were not able to replicate the findings from our earlier study. All eight of the significant changes in our earlier study were not significant in the present double blind replication. Also, the effect of EMF on the number of incorrect answers in the memory task was inconsistent. We previously reported no significant effect of EMF exposure on the number of incorrect answers in the memory task, but a significant increase in errors was observed in the present study. We conclude that EMF effects on the EEG and on the performance on memory tasks may be variable and not easily replicable for unknown reasons.     

Accurate Confidence Intervals for the Ratio of Specific Occurrence/Exposure Rates in Risk and Survival Analysis

Transformation and computer intensive methods such as the jackknife and bootstrap are applied to construct accurate confidence intervals for the ratio of specific occurrence/exposure rates, which are used to compare the mortality (or survival) experience of individuals in two study populations. Monte Carlo simulations are employed to compare the performances of the proposed confidence intervals when sample sizes are small or moderate.