时窗复杂度序列在睡眠脑电分期中的应用

运用时窗复杂度序列来分析睡眠脑电，减少了非平稳性及状态空间的不均匀性造成的脑状态信息的丢失，在一定程度上克服了复杂度自身的局限，有助于不同睡眠期状态特征的提取。另外采用独立分量分析（ICA），小波变换等方法对脑电进行预处理，实验表明它们能有效地去除脑电中的一些生理干扰，有利于提高复杂度算法在睡眠分期应用中的精确度。     

Sleep homeostasis in the rat: Simulation of the time course of EEG slow-wave activity

According to the two-process model of sleep regulation, a homeostatic Process S increases during waking and declines during sleep. For humans, the time course of S has been derived from the changes in EEG slow-wave activity (SWA; spectral power density in the 0.75–4.0 Hz range) during sleep. We tested the applicability of the model to sleep in the rat. The simulation was based on the vigilance states for consecutive 8-s epochs of a 96-h experiment in 9 animals. The level of S was made to decrease in epochs of non-REM sleep (NREMS), and to increase in epochs of waking or REM sleep according to exponential functions. By optimizing the initial value and the time constants of S, a close fit between the hourly values of SWA in NREMS and of S was obtained. The biphasic time course of SWA during baseline, its enhancement in the initial recovery period after 24-h sleep deprivation, and its subsequent prolonged undershoot were present in the simulation. We conclude that sleep homeostasis as conceptualized in the two-process model may be a general property of mammalian sleep.     

Sleep and EEG patterns in the chronic constriction injury model of neuropathic pain

Chronic neuropathic pain patients often report sleep disturbances such as reduced amount of sleep and excessive daytime tiredness. The aim of this study was to evaluate possible abnormalities in sleep patterns in a widely used animal model of neuropathic pain. Adult male Sprague-Dawley rats were chronically implanted with electrodes for electroencephalogram (EEG) and electromyogram (EMG) registrations to allow continuous 24-h polygraphic recording. Subsequently, a chronic constriction injury (CCI) was inflicted on eight rats in accordance with the CCI model of neuropathic pain and a sham operation was performed on another eight rats. The polygraphic recordings were repeated 13, 27, 55, and 146 days after surgery. Although the CCI animals developed significant mechanical and cold allodynia and heat hyperalgesia, there were no significant differences between the CCI rats and the sham-operated control animals in the spontaneous EEG/EMG in homecage-like conditions. It is concluded that in the chronic phase, this neuropathic pain model does not produce clear sleep disturbances. Such an absence of general suffering from sleep disturbances is advantageous to the CCI model as it makes use of the model more acceptable ethically. Nonetheless, this outcome appears to be in contrast with the clinical situation in neuropathic pain and therefore could also be seen as a disadvantage for the face validity of the CCI model.     

睡眠脑电的奇异系统分析

奇异系统分析具有抑制噪声的效果,并且方法简单,计算量小.睡眠脑电的奇异系统分析表明,第一主成分含量明显反映了睡眠状态差异:在清醒时最低,随着睡眠加深逐渐增加,但在REM期时介于S1期和S2期之间.这一结果基本不受个体、数据长度、嵌入维数以及延迟时间的影响.     

Neocortical and hippocampal EEG in normal and lateral hypothalamic-damaged rats

Cortical and hippocampal EEG were correlated with behavior in rats before and after bilateral hypothalamic (LH) damage. In Stage 1 of recovery (aphagia and adipsia), the neocortex showed continuous large amplitude slow activity. It did not desynchronize during spontaneous acts such as grooming as well as during tail pinch-induced struggling or orienting, even though a slow form of hippocampal theta accompanied these acts. However, during Stage 2 (anorexia), the neocortical EEG did desynchronize when such theta appeared. Therefore, as behavioral recovery progresses after LH damage, there appears to be a concomitant recovery of cortical participation in such behavior. Early in recovery, LH rats, unlike normals, showed slow (3–4.5 Hz) atropine-sensitive hippocampal theta during automatisms such as grooming as well as during immobility. Thus, LH damage, while temporarily abolishing fast. noncholinergic theta, appears to release slow cholinergic theta. Later in recovery, faster atropine-resistant (noncholinergic) theta becomes functional again.     

EEG differences in monozygotic twins discordant and concordant for schizophrenia

In an electroencephalographic (EEG) study of 27 pairs of monozygotic (MZ) twins discordant for schizophrenia, 13 pairs of MZ twins concordant for schizophrenia, 40 pairs of healthy MZ twins, and 91 healthy, unrelated subjects with repeated assessments, we investigated (a) the trait quality of brainwave patterns with respect to interindividual differences, intraindividual stability over time, and within-pair MZ concordance; (b) the EEG characteristics that enable discrimination between affected and unaffected individuals; and (c) the EEG characteristics that reflect the severity of illness. In comparison with healthy control subjects, the MZ twins who were discordant and concordant for schizophrenia exhibited a much lower within-pair EEG concordance, so that EEG abnormalities associated with schizophrenia and manifested differently in the co-twins concordant for schizophrenia seemed to reflect nongenetic, pathological developments of genetically identical brains.     

EOG and Delta Rhythmicity in Human Sleep EEG

The use of the electroencephalogram (EEG) is accepted as the only objective method of studying sleep. However, EEG sleep study may not be feasible, although it would be highly desirable, in some non-laboratory operational environments due to difficulties in EEG recordings. Results of the present study showed that the ultradian delta rhythmicity of sleep as defined by EEG could be obtained from electro-oculograms (EOGs) alone.     

改进G-P算法与睡眠脑电的关联维

脑电的非线性参数能有效表达大脑的不同生理状态,不同睡眠期脑电的关联维数不同.但用G- P算法求关联维数存在抗干扰能力较差、可靠性不稳定、运算量巨大等缺点.先对相空间进行奇异谱分析,进而对原始相空间进行旋转,使其成为正交的等效空间,然后再使用G- P算法.改进后的算法能有效地抑制噪声干扰,降低相空间规模,减少运算复杂性,在睡眠脑电的关联维数计算上效果良好.     

睡眠脑电的自回归模型阶数特性

传统睡眠脑电 (Sleep EEG)研究从信号的时域和频域的特征分析睡眠过程 ,通常根据功率谱观察信号中特定节律的出现和频带的分布。而功率谱估计中基于参数模型的方法得到广泛应用 ,但建模时通常只能根据经验选择一个固定较低的阶数。本文讨论了自回归模型阶数 (Autoregressive m odel order,ARMO)估计准则的一些最新进展 ,并且统计了一段睡眠过程中 EEG的阶数分布。结果显示 EEG的 ARMO分布集中在差别很大的几个区间 ,可以用来表示睡眠 EEG分期内微结构和过渡过程 ,并在一定程度上提供 EEG的特征和组成成分的信息     

EEG phase synchronization in patients with paranoid schizophrenia

Recent findings suggest that specific deficits in neural synchrony and binding may underlie cognitive disturbances in schizophrenia and that key aspects of schizophrenia pathology involve discoordination and disconnection of distributed processes in multiple cortical areas associated with cognitive deficits. In the present study we aimed to investigate the underlying cortical mechanism of disturbed frontal-temporal-central-parietal connectivity in schizophrenia by examination of the synchronization patterns using wavelet phase synchronization index and coherence between all defined couples of 8 EEG signals recorded at different cortical sites in its relationship to positive and negative symptoms of schizophrenia. 31 adult schizophrenic outpatients with diagnosis of paranoid schizophrenia (mean age 27.4) were assessed in the study. The obtained results present the first quantitative evidence indicating direct relationship between wavelet phase synchronization and coherence in pairs of EEG signals recorded from frontal, temporal, central and parietal brain areas and positive and negative symptoms of schizophrenia. The performed analysis demonstrates that the level of phase synchronization and coherence in some pairs of EEG signals is inversely related to positive symptoms, negative symptoms and general psychopathology in temporal scales (frequency ranges) given by wavelet frequencies (WFs) equal to or higher than 7.56 Hz, and positively related to negative symptoms in wavelet frequencies equal to or lower than 5.35 Hz. This finding suggests that higher and lower frequencies may play a specific role in binding and connectivity and may be related to decreased or increased synchrony with specific manifestation in cognitive deficits of schizophrenia.     

利用小波级数检测睡眠EEG中的K-复合波

本文提出了一种利用小波级数检测睡眠脑电中Ｋ－复合波的方法。这种方法使用Ｄａｕｂｅｃｈｉｅｓ正交小波基,把ＥＥＧ信号分解成４个尺度上的小波级数,利用最大尺度的信号逼近检测Ｋ－复合波中的大慢波脉冲,然后,利用信号细节检测紧跟大慢波脉冲之后的梭形波。     

Intact hippocampal gray matter in schizophrenia as revealed by automatized image analysis postmortem

Implicated as a key structure in the pathophysiology of schizophrenia, the hippocampus is at the forefront of neuropathological and neuroimaging research. To elucidate the cellular basis of hippocampal pathology in schizophrenia, we studied the postmortem hippocampal sections of 16 patients suffering from schizophrenia and 16 controls applying the gray-level index (GLI) method. We determined the area-percentage covered by neuronal perikarya in relation to the total area of the pyramidal cell layer in the four subdivisions of the ammon’s horn (cornu ammonis, CA1–4) bilaterally. Additionally, we determined the area size of the pyramidal cell layer (CA1–4) and dentate gyrus (DG) granule cell layer. Results showed no significant differences between diagnostic groups with respect to the dependent variables, supporting the view that there is no primary alteration of hippocampal gray matter in schizophrenia.     

Sleep, EEG and mental function changes in senile dementia of the Alzheimer's type

—Sleep, EEG and mental function variables were studied in 44 subjects diagnosed as having probable senile dementia of the Alzheimer's type (SDAT) and 22 controls matched for age and minimal depression. Results indicate that sleep, EEG and mental function variables all undergo significant change even in the early, mild stage of SDAT, with further change in the moderate and severe stages of dementia. Mental function variables also underwent significant decline across levels of dementia. Sleep and mental function variables had strong power in correctly classifying subjects into control vs. mild dementia groups (90 and 100%, respectively). Dominant occipital rhythm frequency, a clinical EEG measure, also discriminate as well (75%). The results indicate that sleep and EEG variables discriminate well for early, mild SDAT in minimally depressed aged individuals.     

偏执型精神分裂症病人与正常人脑电图向量分析

目的 :用向量分析法处理脑电图 ,为脑电图研究提供一个新的手段。方法 :将 94例偏执型精神分裂症病人 (病人组 )与 35例正常人 (对照组 )的脑电向量分析结果进行比较。结果 :病人组中 6 9例异常 ,2 5例正常。对照组中 ,1例异常 ,34例正常。结论 :脑电信息流的向量分析技术 ,对精神病人的临床诊断有重要价值。     

Sleep During and After Gradual Sleep Reduction

To determine: 1) the minimum amounts of sleep subjects would tolerate, 2) the changes in EEG sleep measures, and 3) whether subjects would revert to baseline sleep after study termination, 4 couples gradually reduced their sleep. Three couples reduced their TST in 30-min steps from a baseline of 8 hrs and one couple from a baseline of 6.5 hrs. Subjective estimates of sleep time, sleep quality, and mood were collected daily. Home EEG sleep recordings were obtained 3 nights a week. Two of the 8-hr sleepers reduced their sleep to 5.5 hrs, 2 to 5.0 hrs, and 2 reached 4.5 hrs. These 6 subjects continued sleeping 1 to 2.5 hrs below baseline amounts a year after reduction terminated. The 6.5-hr baseline couple reached 5.0 hrs and returned to 6.5 hrs TST during follow-up. Stages W, 2, and REM decreased significantly in absolute amounts. Percentage of stages W and 2 also decreased significantly. REM percent remained constant. Stage 3 was constant while stage 4 increased in both absolute and relative amounts. REM cycle length remained constant. Stage 4 rebound on 7-hr nights was not observed during times of greatest sleep reduction. Occurrences of stage REM within 10 min of stage 1 onset were observed in 2 subjects when their TST was below 6.5 hrs. Our results are consistent with other studies of shortened sleep, indicating that TST is the major determinant of sleep-stage characteristics.     

Sleep, EEG and mental function changes in senile dementia of the Alzheimer''s type

—Sleep, EEG and mental function variables were studied in 44 subjects diagnosed as having probable senile dementia of the Alzheimer's type (SDAT) and 22 controls matched for age and minimal depression. Results indicate that sleep, EEG and mental function variables all undergo significant change even in the early, mild stage of SDAT, with further change in the moderate and severe stages of dementia. Mental function variables also underwent significant decline across levels of dementia. Sleep and mental function variables had strong power in correctly classifying subjects into control vs. mild dementia groups (90 and 100%, respectively). Dominant occipital rhythm frequency, a clinical EEG measure, also discriminate as well (75%). The results indicate that sleep and EEG variables discriminate well for early, mild SDAT in minimally depressed aged individuals.     

Variations in Period-Analysed EEG Asymmetry in REM and NREM Sleep

Monopolar EEG was recorded from lateral frontal and parietal sites with linked ear reference during sleep in 24 adults. Electrode placement followed the 10-20 International system. EEG was quantified using digital period analyses. The absolute difference in interhemispheric EEG parameters was compared for Stage 2, REM, and a slow wave sleep measure. The absolute difference measures reflect the degree of symmetry or asymmetry, regardless of the hemisphere of origin. Theta and delta activity in slow wave sleep was more asymmetrical than in either Stage 2 or REM. REM sleep was associated with the smallest asymmetries. These results do not support a right hemisphere REM, left hemisphere NREM relationship. Rather they suggest that REM sleep is associated with relative hemispheric symmetry whereas asymmetries are most prominent in slow wave sleep. Stage 2 sleep was significantly less asymmetrical than slow wave on a number of theta and delta measures. The significant differences between slow wave and Stage 2 sleep may denote functional differences within NREM sleep stages.     

EEG Slow Wave Activity, REM Sleep, and Rectal Temperature During Night and Day Sleep in Morning-Type and Evening-Type Subjects

During 3 baseline nights (2 for adaptation) and during 3 days of a sleep-wake reversal, electrophysiological characteristics of sleep and rectal temperature were recorded in 8 morning-type (M-type) and 8 evening-type (E-type) subjects, living in a quiet sleep laboratory. Outcomes of visual sleep scoring revealed the following general tendencies for day-sleep as compared to night-sleep: shorter sleep latencies, shorter REM (rapid eye movement sleep) latencies, advance of the time of maximum REM duration, increased duration of slow wave sleep, more intermittent wakefulness, and decreased subjective sleep quality. Furthermore, for the M-types consistently shorter sleep latencies and--for day-sleep--longer REM latencies were observed than those for the E-types. With regard to the parabolic time course of REM duration, M-types appeared to be relatively phase advanced, in particular for their day-sleep. In addition, subjective sleep quality was consistently higher for the M-types, with the exception of the first day-sleep. The temporal distributions of EEG delta (0.5-3.5 Hz) energy over the first four NREM/REM cycles of day-sleep all deviated from a monotonically decreasing trend. Compared to night-sleep the M-types showed a relative increase of delta energy for Cycle 2, whereas for the E-types a relative increase for Cycles 3 and 4 was observed. An analysis of delta energy, employing a pattern-recognition technique independently from visual sleep scoring, revealed an overall faster rate of accumulation for the M-types. Following sleep onset, rectal temperature showed a decrement, which was larger for the M-types. Moreover, rectal temperature and delta energy were negatively related, as indicated by a negative mean intra-individual correlation. These results are discussed in relation to the characteristic sleep-wake behavior of M-types and E-types.     

Resting EEG in first-episode schizophrenia patients, bipolar psychosis patients, and their first-degree relatives

We evaluated the resting electroencephalogram (EEG) of 50 first-episode schizophrenia patients and 55 of their relatives, 31 first-episode bipolar patients and 35 of their relatives, and 113 nonpsychiatric subjects and 42 of their relatives. The frequency characteristics of the EEG showed moderate stability for a subgroup of these subjects (n= 106) who were tested twice, approximately 9 months apart. Both the schizophrenia and bipolar patients showed a generalized pattern of increased delta and theta and decreased alpha activity. The bipolar patients demonstrated additional right hemisphere activity that was not present among the schizophrenia patients and nonpsychiatric subjects, a finding consistent with hypotheses concerning nondominant hemisphere involvement in the regulation of elated mood. The schizophrenia patients' female relatives and/or relatives with affective disorders and the bipolar patients had significantly reduced peak alpha frequencies. This finding may be related to reduced information processing capacity among these subjects.     

Characterizing Dynamic Functional Connectivity Across Sleep Stages from EEG

Following a nonlinear dynamics approach, we investigated the emergence of functional clusters which are related with spontaneous brain activity during sleep. Based on multichannel EEG traces from 10 healthy subjects, we compared the functional connectivity across different sleep stages. Our exploration commences with the conjecture of a small-world patterning, present in the scalp topography of the measured electrical activity. The existence of such a communication pattern is first confirmed for our data and then precisely determined by means of two distinct measures of non-linear interdependence between time-series. A graph encapsulating the small-world network structure along with the relative interdependence strength is formed for each sleep stage and subsequently fed to a suitable clustering procedure. Finally the delineated graph components are comparatively presented for all stages revealing novel attributes of sleep architecture. Our results suggest a pivotal role for the functional coupling during the different stages and indicate interesting dynamic characteristics like its variable hemispheric asymmetry and the isolation between anterior and posterior cortical areas during REM.