癫痫病人发作间期脑电背景活动的地形图分析

采用脑电地形图分析技术,以33例健康成人作对照,对92例成年癫痫病人发作间期脑电图背景活动进行定量分析。并与脑电目测分析、CT、临床表现进行对比,脑电地形图分析的频域范围为1～30Hz。结果表明:癫痫病人发作间期脑电图背景活动可表现δ、θ、δ+θ/α+β活动局灶增强;脑电地形图在反映局灶性改变方面较目测EEG分析敏感。其所示病变部位与CT、临床定位大多数符合,可用来对病灶进行定位定侧。     

癫癎病人δ、θ活动地形图研究

目的：利用脑电地形图（ＢＥＡＭ） 分析技术,判断不对称性δ、θ活动在癫癎患者中的临床意义。方法：用Ｚ 值概率差异ＢＥＡＭ 进行分析,并与其它检查结果比较。结果：在８３ 例癫癎病人中,ＢＥＡＭ 对不对称性δ、θ的检出率高达７２ ％ ,较脑电图（ＥＥＧ） 目测分析敏感,其显示的异常区与ＥＥＧ 目测分析、ＣＴ、单光子发射ＣＴ（ＳＰＥＣＴ） 大多符合。结论：背景脑电的不对称性δ、θ活动对癫癎的辅助诊断与癎灶定位有重要价值。     

脑电地形图对癫痫诊断价值的探讨

81例癫痫的临床及脑电地形图(BEAM)结果显示:继发性全身性发作,BEAM显示较高的异常检测率和定位率,病变部位δ、θ频率的能量值增高,α频率显示低能量功率值。原发性癫痫发作的间歇期,棘、尖波与背景脑电活动相比,发放能量较弱,背景活动能量掩盖了真实性棘、尖波能量,计算机很难准确作出异常放电的定位诊断。故4例常规EEG背景中显示棘、尖波发放,而BEAM未能显示棘、尖波地形图.癫痫小发作,BEAM不能反映特异性异常脑波的棘波成份,仅能反映与棘波共同发放的慢波频率范围的能量值。     

闭合性脑外伤脑电图变化与脑电地形图结果比较

目的:探讨脑电学检查在闭合性脑外伤中的应用.方法:对123例闭合性脑外伤患者进行EEG和BEAM检查.结果:EEG异常率为56.9%,表现为弥漫性或局部性慢波增多,BEAM异常率为70.7%,表现为θ或δ频带功率呈弥漫性或局限性增高.结论:闭合性脑外伤的损伤程度与EEG的变化有良好的正相关性;闭合性脑外伤EEG和BEAM,两者有显著性差异;多次重复脑电学检查,有重要临床价值.     

颅内病变患者脑电地形图脑电图与CT的对比分析

本文对326例颅内病变患者的BEAM、EEG与CT进行对比分析。结果表明,在脑外伤、脑动脉硬化、脑炎、癫痫及头痛等以脑机能改变为主的疾病中,BEAM的阳性率高于EEG与CT,但在以脑结构改变为主的疾病中(如脑肿瘤),CT的阳性率高于EEG,而与BEAM相近。说明BEAM不仅能显示大脑功能性病变,也能形象地诊断颅内器质性病变,并能对病变的疗效判断和预后提供重要诊断依据。     

重要或然性的图形化:帮助脑电话活动定位的记录分析

EEG已证明在产生局灶和(或)发作性异常(即脓肿、癫痫)的某种神经疾病的识别中是重要的工具。但是,有少数例外,EEG对识别引起背景活动的更细微改变(如智能发育不全,早老痴呆)的神经疾病很少有用。皮层诱发电位(EP)也还未能达到临床应用的水平。为了帮助这些资料的临床评价,著者最近制成一种局部记录图形化系统和计算机显示的头皮记录信号,即脑电活动图形化(Brain Electrical actvity mapping,BEAM)。图象来自EEG和EP两方面的资料。对于EEG资料可显示传统的δ、θ、α和β频带的空间分布。对于     

脑出血、脑梗塞急性期脑电图、脑电地形图、经颅多普勒与CT对比研究

本文对CI组(29例),CH组(34例),健康人对照组(30例),同时进行了EEG、BEAM、TCD与CT的前瞻性对比研究。结果CI组和CH组EEG、BEAM异常率分别为96.5％和97.1％,而BEAM定侧定位率远远高于EEG。在CI组,BEAM出现异常早于CT,且异常率(96.5％)高于CT(93.1％)。说明脑功能障碍早于形态学改变。(δ+θ)/(α+β)比值,两组无差异。本文提出病、健侧频带功率差的百分比可作为BEAM一项观察指标。CH组病、健侧δ、θ频带功率均值差的百分比分别为48.58％和47.91％,高于CI组(29.05％和26.38％)。TCD异常率CI组(100％)和CH组(97.1％)两组均高,说明在脑卒中急性期TCD对颅内血流动力学改变很敏感,它虽不能定位定性,但通过动态观察,可了解脑血管功能状态、侧枝循环、颅内动脉开放程度等,对治疗前后疗效评价及预后有指导意义。     

38例网络成瘾青少年脑电图分析

目的:探讨互联网络成瘾(IAD)青少年的脑电信号特点及可能的发生机制.方法:描记符合诊断标准的38例IAD患者和35例健康对照者的脑电图(EEG),进行目测阅图和功率谱组间对比分析,并对异常程度与IAD时间做组内相关性分析.结果:EEG目测阅图结果显示,IAD组EEG异常率明显高于对照组,病变部位主要是额区,两者比较差异有统计学意义(P＜0.05);IAD组EEG异常程度与IAD时间无明显关联性(P＞0.05).EEG相对功率值分析显示,与正常对照组相比,IAD组双侧额、颞区慢波(δ、θ波)功率增高.结论:IAD青少年EEG结果提示额、颞区脑功能处于抑制状态,抑制程度与IAD的时间不相关;推测大脑额、颞区兴奋性降低是导致IAD的可能原因之一.     

老年慢性精神分裂症患者脑电地形图初步研究

目的：为探讨老年慢性精神分裂症患者（SCS）与正常老人在脑电地形图（BEAM）检查中的各自特点。方法：使用16道地形图仪，对39例正常老人和24例SCS患者的BEAM作了检测。结果：在头颅模式图中，SCS患者的BEAM趋向凹字形低密度带。在前颞区θ频域及枕区和中央区δ频域均右侧高于左侧（P＜0．05）。与正常老人相比，SCS患者δ与θ波功率在主要记录点均增高（P＜0．05或P＜0．01）。α波功率在F3、F4、P3、P4以及Fp1、F7记录点下降（P＜0．01或P＜0．05）。β波功率在主要记录点（Fp1、Fp2、T3、T4、T5、T6、O1、O2、F3、F4）上降低也有显著性差异（P＜0．05）。SCS患者BEAM－EEG比EEG提高阳性检出率12．5％。结论：SCS患者的BEAM－EEG具有不同于正常衰老的改变。     

慢性肾炎患者的BEAM和EEG分析

本文通过对80例慢性肾炎的BEAM和EEG对比分析,发现BEAM异常率72.5％,EEG异常率43.8％。在对慢性肾炎的敏感方面,BEAM优于EEG,其主要表现为弥漫性慢功率增高,EEG则表现为α波缓慢,波幅降低,调节调幅差,伴有低幅慢波及5—7c/sθ活动。 BEAM和EEG异常率的发生率及异常程度与病程有关,病程越长,异常度越重。通过治疗观察,其异常程度是可逆的。     

Behavioral correlates of human hippocampal delta and theta oscillations during navigation

Previous rodent studies demonstrate movement-related increases in theta oscillations, and recent evidence suggests that multiple navigationally relevant variables are reflected in this activity. Human invasive recordings have revealed movement-related modulations in delta and theta activity, although it is unclear whether additional behavioral variables are responsible for modulating this neural activity during navigation. We tested the role of delta and theta oscillations during navigation by addressing whether spatial-related processing, in addition to speed and task variables, modulates delta and theta activity. Recording from 317 hippocampal intracranial electrodes in 10 patients undergoing seizure monitoring, we observed increasing delta and theta power with increasing virtual speed at significantly more electrodes than would be expected by chance, replicating previous findings in nonhuman mammals. Delta and theta power were more consistently modulated, however, as a function of spatial view, including when subjects looked at stores in the virtual environment both to find a relevant goal or for spatial updating. A significantly larger proportion of electrodes showed view-related effects than speed-related modulations. Although speed, task, and spatial view affected delta and theta activity, individual electrodes were most frequently modulated by only one variable, rather than a combination of variables. These electrodes likely sampled independent delta and theta generators, which reflected movement-related and allocentric processing, respectively. These results extend previous findings in nonhuman mammals and humans, expanding our knowledge of the role of human hippocampal low-frequency oscillations in navigation.     

Topographic sleep EEG changes in the acute and chronic stage of hemispheric stroke

After stroke, the injured brain undergoes extensive reorganization and reconnection. Sleep may play a role in synaptic plasticity underlying stroke recovery. To test this hypothesis, we investigated topographic sleep electroencephalographic characteristics, as a measure of brain reorganization, in the acute and chronic stages after hemispheric stroke. We studied eight patients with unilateral stroke in the supply territory of the middle cerebral artery and eight matched controls. All subjects underwent a detailed clinical examination including assessment of stroke severity, sleep habits and disturbances, anxiety and depression, and high‐density electroencephalogram examination with 128 electrodes during sleep. The recordings were performed within 10 days after stroke in all patients, and in six patients also 3 months later. During sleep, we found higher slow‐wave and theta activity over the affected hemisphere in the infarct area in the acute and chronic stage of stroke. Slow‐wave, theta activity and spindle frequency range power over the affected hemisphere were lower in comparison to the non‐affected side in a peri‐infarct area in the patients’ group, which persisted over time. Conversely, in wakefulness, only an increase of delta, theta activity and a slowing of alpha activity over the infarct area were found. Sleep slow‐wave activity correlated with stroke severity and outcome. Stroke might have differential effects on the generation of delta activity in wakefulness and sleep slow waves (1–8 Hz). Sleep electroencephalogram changes over both the affected and non‐affected hemispheres reflect the acute dysfunction caused by stroke and the plastic changes underlying its recovery. Moreover, these changes correlate with stroke severity and outcome.     

Phase coupling between rhythmic slow activity and gamma characterizes mesiotemporal rapid-eye-movement sleep in humans

In the human sleep literature there is much controversy regarding the existence and the characteristics of hippocampal rhythmic slow activity (RSA). Generally the human RSA is believed to occur in short bursts of theta activity. An earlier study, however, reported mesiotemporal RSA during rapid-eye-movement (REM) sleep that instead of theta fell in the delta frequency band. We conjectured that if this RSA activity is indeed a human analogue of the animal hippocampal theta then characteristics associated with the animal theta should also be reflected in the human recordings. Here our aim was to examine possible phase coupling between mesiotemporal RSA and gamma activity during REM sleep. The study relied on nine epilepsy surgery candidates implanted with foramen ovale electrodes. Positive half-waves of the 1.5–3 Hz RSA were identified by an automatic algorithm during REM sleep. High-frequency activity was assessed for 11 consecutive 20 Hz–wide frequency bands between 20 and 240 Hz. Increase in high frequency activity was phase coupled with RSA in most frequency bands and patients. Such a phase coupling closely resembles that seen between theta and gamma in rodents. We consider this commonality to be an additional reason for regarding delta rather than theta as the human analogue of RSA in animals.     

Resting posterior versus frontal delta/theta EEG activity is associated with extraversion and the COMT VALMET polymorphism

Recent studies suggest that resting posterior versus frontal EEG delta/theta activity (delta/theta Pz–Fz) is both sensitive to pharmacological manipulations of neural dopamine and associated with the agency facet of extraversion (i.e., a motivational disposition comprising enthusiasm, energy, assertiveness, achievement striving and social dominance). These observations suggest that posterior versus frontal resting EEG delta/theta activity may represent a useful marker for investigating the molecular genetic basis of extraversion. The present study aimed to test the novel hypothesis of an association between delta/theta Pz–Fz and a functional polymorphism of the enzyme catechol-O-methyltransferase (COMT VAL¹⁵⁸MET) involved in dopamine catabolism. This was conducted in a large EEG data set from the Brain Resource International Database (BRID; resting EEG from N = 1093 healthy individuals, 382 of which also genotyped for COMT VAL¹⁵⁸MET). In summary, we (1) showed for the first time that the VAL allele is associated with increased delta/theta Pz–Fz; (2) replicated the association between extraversion and delta/theta Pz–Fz in a large, heterogeneous sample including both genders; and (3) documented that the VAL allele of the COMT VAL¹⁵⁸MET is associated with increased extraversion scores, as previously reported for an overlapping BRID sample. This coherent pattern of findings adds further support to the suggestion that the posterior–anterior distribution of resting EEG slow wave activity in the delta/theta range represents a useful tool for probing the dopaminergic basis of extraversion.     

Effects of hydration and hyperventilation on cortical complexity

The effects of hydration and hyperventilation on cortical complexity were investigated in a sample of 19 healthy volunteers in a double-blind placebo design using magnetoencephalographic recordings. The subjects were asked to abstain from the intake of liquids 18 h before the study. Spontaneous magnetoencephalograms (MEG) were recorded before and after drinking 750 ml water (WAT group: nine subjects) or saline solution (SAL group: ten subjects) with eyes closed and open and during hyperventilation (HV) with eyes open. The MEG data were analysed using both linear (spectral power) and non-linear (pointwise dimension and largest Lyapunov exponent) algorithms. The prediction that intake of water, because of induced cell swelling, will lead to an increased synchronization and a decreased complexity of the spontaneous MEG during hyperventilation was confirmed. Hyperventilation following the drinking condition produced an increase in all power spectra with a stronger increase of delta and theta power after drinking of water. This synchronization of spontaneous MEG is accompanied by a general significant decrease of cortical complexity, especially after water drinking. Moreover, cortical complexity was inversely related to delta and theta power and partly also to alpha power. The SAL and WAT groups showed different relations between alpha power and dimensional complexity during HV: whereas in the SAL group the correlations between these measures became more negative during HV, they reversed in the WAT group to become positive. The synchronizing effect of hyperventilation, leading to a decrease of cortical complexity, is related in the SAL group to delta, theta and alpha power, whereas in the WAT group only delta and theta activity contribute to a reduction of cortical complexity. Electronic Publication     

Electroencephalographic comparison of veterans with combat-related post-traumatic stress disorder and healthy subjects.

Various investigations prove the biological basis for post-traumatic stress disorder (PTSD). There are only a few quantitative electroencephalographic (qEEG) studies of patients with PTSD. The aim of this investigation is to find out whether there are differences in qEEG parameters between PTSD patients and healthy subjects. The experimental group was comprised of 18 veterans with PTSD, and 20 healthy non-veterans were included in the control group. After informed consent was obtained, they were investigated by qEEG recordings. The artifact-free EEG epoch was analyzed by fast Fourier transformation (FFT). Power values of particular frequency bands (delta, theta, alpha 1, alpha 2, beta 1, beta 2) were observed on the regions: Fp I, Fp2, F3, F4, F7, F8, C3, C4, T3, T4, T5, T6, P3, P4, O1 and O2. PTSD patients had increased theta activity over central regions, and increased beta activity. Beta 1 activity increased over frontal, central and left occipital regions; beta 2 activity increased over frontal regions. No significant differences were noted between the PTSD and control group in delta and alpha activity. These results suggest a neurobiological basis for PTSD. Increased theta activity may help to explain changes in hippocampal volume. Various explanations (cortical hyperexcitability, prolonged wakefulness, or attention disturbances) have been offered for the beta activity increase observed in PTSD subjects.     

The role of TNF-alpha in amygdala kindled rats

In the present study, the interaction between epileptogenesis and the immune system were studied in a kindling model. First, the effects of a single administration of TNF-alpha (5.0 microg/kg, i.p.) on seizure and EEG activity were investigated in amygdala-kindled rats. TNF-alpha treated rats showed more prolonged epileptiformic discharges than control rats. TNF-alpha also induced a decrease in the power of delta band and an increase in theta and alpha activity. In addition, a marked increase in the power of beta and gamma band was observed. The EEG changes were most numerous in the frontal cortex and amygdala. All effects were registered 24 h after TNF-alpha administration. Finally, electrical stimulation enhanced the level of TNF-alpha in blood serum from 1.9 +/- 1.5 to 12.7 +/- 3.8 pg/ml and in brain tissue 56.8 +/- 6.0 to 109.2 +/- 6.0 pg/mg, as was determined via the ELISA method. It can be concluded that there is a mutual facilitative interaction of both epileptogenic and cytokine-derived mechanisms on this type of seizure. The changes in the power spectrum of the EEG after TNF-alpha might contribute to intensify thalamic-derived facilitation of epileptic discharge in cortical structures.     

Age-related increases in within-person variability: delta and theta oscillations indicate that the elderly are not always old

Behavioral and electrophysiological data related to performance in an auditory Go/NoGo task were analyzed in young and older adults in the present study. Especially, differences in within-person variability in behavior and neural activity between young and older adults and changes in topography of slow event-related oscillations (EROs) were of interest. Within-person variability in behavior was assessed by reaction time (RT) variability. Event-related delta and theta oscillations were analyzed using time-frequency transformation, which can give information on the time-course of single trial event-related EEG spectral power enhancement and intertrial phase-locking (ITC). In contrast to our previous visual Go/NoGo study, no under-recruitment of task-relevant brain regions was found for the auditory theta and delta EROs. Young did not differ from older adults in RT variability or in single trial delta/theta ITC. Altered recruitment of brain activity at advanced age was indicated, first, by stronger early theta phase-locking in older compared to young adults and, second, by a Go-specific lateralization of delta/theta activity. We conclude that within-person variability may increase with age, but the degree depends on performance level and the modality investigated.     

Alzheimer's disease patients not carrying the apolipoprotein E ε4 allele show more severe slowing of oscillatory brain activity

The objective of this study was to quantitatively assess the relationship between apolipoprotein (APOE) genotype and electroencephalographic oscillatory brain dynamics in Alzheimer's disease (AD) patients and control subjects and its regional distribution. We obtained resting-state electroencephalographs of 320 AD patients and 246 control subjects, categorized into APOE ε4 carriers and noncarriers. Peak frequency and relative power in 4 different frequency bands were calculated. We tested the associations between APOE genotype and relative power in 4 brain regions. Peak frequency was comparable in APOE ε4 carrying and noncarrying control subjects, but lower in APOE ε4 noncarrying AD patients. In control subjects, APOE ε4 carriers had a different regional distribution of alpha power than noncarriers. We found no APOE effect in beta, delta, and theta bands. In AD, APOE ε4 noncarriers had lower alpha and higher delta power than carriers. This difference was most pronounced in the parieto-occipital region. In the theta band, APOE ε4 noncarriers had a different regional distribution of power compared with carriers. In conclusion, the most pronounced effect of genotype was seen in AD patients, and APOE ε4 noncarriers showed slower activity, especially in parieto-occipital regions.     

Significant thalamocortical coherence of sleep spindle,theta, delta,and slow oscillations in NREM sleep: Recordings from the human thalamus

The electrophysiological studies of thalamocortical oscillations were mostly done in animal models. Placement of stimulation electrodes at the anterior nucleus of the thalamus (ANT) for seizure reduction enables the study of the thalamocortical interplay in human subjects. Nocturnal sleep electroencephalograms (EEGs) and local field potentials (LFPs) of the left and right thalamus (LT, RT) were recorded in three subjects receiving ANT stimulation. Sleep stages were scored according to American Academy of Sleep Medicine criteria. The whole-night time–frequency coherence maps between EEG (C3, C4) and LFP (LT, RT) showed specific coherence patterns during non-rapid eye movement (NREM) sleep. Pooled coherence in the NREM stage was significant in slow, delta, theta and spindle frequency ranges. The spindle oscillations had the highest coherence (0.17–0.58) in the homolateral hemisphere. Together, these observations indicate that the oscillations were related to thalamocortical circuitry.