老年人视觉、听觉及体感诱发的ERP比较

对３０位神经系统正常、精神活动完整的老年人同时进行视觉、听觉、体感不同刺激模式检测得到的事件相关电位（ＥＲＰ）进行比较分析，结果提示不同的刺激模式诱发出来的ＥＲＰ各波的潜伏期、波幅、波型是不同的。如视觉刺激时Ｐ３波潜伏期为４００．７４±２６．５２ｍｓ，波幅为８．３５±４．９６μｖ；听觉刺激时Ｐ３波潜伏期为３３９．５２±２３．９０ｍｓ，波幅为８．４０±５．４３μｖ；体感刺激时Ｐ３波潜伏期为３４６．２±３５．１ｍｓ，波幅为８．５６±２．１４μｖ。并对不同刺激模式的最佳记录部位和产生机制进行初步讨论。     

靶与非靶刺激信息的认知事件相关电位比较

对靶与非靶刺激信息的认知事件相关电位进行比较研究。给予受试者汉语词汇作业刺激，被视觉感知，靶刺激以２０％的概率随机呈现，非靶刺激占８０％。结果发现这两种刺激状态下认知事件相关电位成分的Ｎ１，Ｐ２，Ｎ２无显著差异，而Ｐ３，Ｎ４和ＬＰＣ（ＬａｔｅＰｏｓｉｔｉｖｅＣｏｍｐｏｎｅｎｔ）则其波形变化和地形图特征有明显不同，靶刺激激活整个脑区，各波幅均较大，以Ｐ３波最为显著     

幼儿视觉 ERP: Ⅲ.P_3 波面积的研究

以往事件相关电位（ＥＲＰ）研究主要对峰波幅和峰潜伏期进行测量，本研究用人像照片按一定概率编排成刺激序列，成功诱发幼儿ＥＲＰ，并在此基础上对Ｐ３面积进行了测量。结果证明，低概率非靶刺激在幼儿可以诱发出Ｐ３，与任务Ｐ３相比波面积小，提示幼儿Ｐ３波面积有明显的任务效应，再认熟悉人的Ｐ３面积大于再认陌生人，波面积比波幅更合理地反映场合修正量。幼儿在高度选择注意时，Ｐ３面积大。幼儿Ｐ３波面积以Ｐｚ、Ｏｚ电极所描记的为大。     

智力低下儿童事件相关电位的研究

对３１例智力低下儿童进行事件相关电位（ＥＲＰ）和智商（ＩＱ）对照研究，并与正常儿童进行比较，发现Ｐ３波之潜伏期（ＰＬ）与ＩＱ的高低有显著的相关性，靶刺激时智力低下儿童组Ｐ２、Ｐ３波波幅较正常儿童组低。提示ＥＲＰ测定是评价智力低下儿童认知功能较为灵敏的一种客观指标。     

正常青年人视觉、听觉诱发的ERP的比较

35例正常青年人同时进行视觉、听觉不同刺激模式检测的事件相关电位(ERP)进行比较分析,我们发现不同刺激模式诱发出的ERP各波的潜伏期,波幅均不相同,尤其是不同模式的靶与非靶刺激诱发的P_2波的波幅有明显的差距(P<0.05)。本文对其原因和不同年龄的P_3波在颅顶有不同的分布部位以及其中一些人P_3波电位值两半球不对称性的机理进行了初步探讨。     

短暂性脑缺血发作认知功能与事件相关电位研究

目的：探讨短暂性脑缺血发作（ＴＩＡ）病人事件相关电位（ＥＲＰ）的变化规律及其临床意义。方法：用听觉Ｏｄｄｂａｌ刺激序列ＥＲＰ、认知能力筛选试验（ＣＣＳＥ）和简易智力状态试验（ＭＭＳＥ）检测３２例ＴＩＡ病人和３０例年龄、性别、利手和教育程度相匹配的正常人。结果：病人组ＥＲＰ的Ｎ２和Ｐ３峰潜伏期较对照组显著延长（Ｐ＜０．０１），Ｎ２和Ｐ３波幅两组均无显著性差异，Ｐ３峰潜伏期（Ｐ３ＰＬ）异常率为２５％。病人组ＭＭＳＥ较对照组低（Ｐ＜０．０５），但与Ｐ３ＰＬ未见有相关性（ｒ＝－０．２４４，Ｐ＞０．１）；ＣＣＳＥ与对照组无显著差异，但与Ｐ３ＰＬ呈显著负相关（ｒ＝－０．４７３，Ｐ＜０．０１）。结论：ＴＩＡ病人存在不同程度的认知功能障碍。对认知功能障碍的早期发现，ＥＲＰ检则有临床实用价值     

10例阿尔茨海默型老年痴呆事件相关电位的初步研究

对１０例临床诊断为阿尔茨海默型老年痴呆（ＳＤＡＴ）的患者及１９例正常人进行听觉事件相关电位（ＥＲＰ）检测，同时还观察ＳＤＡＴ患者体外反搏治疗前后ＥＲＰ的变化。发现患者组Ｎ１波潜伏期明显延长，Ｐ３波出现率低仅４％（正常青年组１００％，老年组８０％）。Ｐ３潜伏期显著延长，波幅明显降低。体外反搏治疗后，患者组Ｎ１波潜伏期明显缩短，Ｐ３波出现率升至８０％。     

精神分裂症听觉事件相关电位 P_(300)研究进展

精神分裂症听觉事件相关电位Ｐ３００研究进展王京鹤综述陈学诗审校事件相关电位（ＥＲＰ）中的一个重要成分是出现在３００ｍｓ左右（实际为２８０～７００ｍｓ）的一个正波，故称之为Ｐ３００，也因是第三个正相波，也称Ｐ３。其特点是不受刺激形式和刺激参量的影响，而...     

视觉模式事件相关电位方法的建立

视觉模式事件相关电位方法的建立董瑞国，孙相如，高素荣，吴一兵，赵似兰，李普事件相关电位（ＥＲＰ）的内源性成份与人脑对某一刺激信息进行认知加工的过程密切相关［１］。因此，采用不同的模式，不同的刺激及不同的作业所引出的内源性成份（如Ｐ３００，Ｎ４００）具...     

正常人的视觉事件相关电位研究

本文利用三种视觉符号编排的刺激序列，记录了９５名正常人的视觉ＥＲＰ，报道了Ｆｚ、Ｐｚ点Ｎ２、Ｐ３波幅和潜伏期的正常值及Ｎ２、Ｐ３的影响因素。结果表明：该刺激序列可引出清晰、稳定的ＥＲＰ波形；Ｐ３波幅与任务和部位有关，靶Ｐ３波幅大于非靶Ｐ３，靶Ｐ３于Ｐｚ点波幅大于Ｆｚ，非靶Ｐ３在Ｆｚ、Ｐｚ点间波幅无明显差异；Ｎ２波幅与任务无关，靶与非靶之间Ｎ２波幅无差异，而与部位有关，Ｆｚ点波幅大于Ｐｚ点；Ｎ２、Ｐ３受年龄的影响．中老年人Ｎ２、Ｐ３潜伏期长于青年人，而波幅中老年人较青年人低。     

Visual motion perception from stimulation of the human medial parieto-occipital cortex

Summary Visual phenomena evoked by direct electrical stimulation of extrastriate cortex were observed in 30 epileptic patients as part of a presurgical investigation. An incremental sequence of low-level bipolar stimulation trains was delivered at medial and lateral pairs of contacts of stereotaxically-implanted multilead intracerebral electrodes in parietal, occipital and posterior temporal regions. Diffusion of stimulus afterdischarges was monitored by electrodes in temporal and frontal lobes and by the non-stimulated contacts of the stimulated electrode. Localized stimulations evoked few visual phenomena. The strongest anatomo-perceptual correlation was found for stimulation in the medial parieto-occipital fissure which evoked visual motion phenomena in all three patients stimulated in that region. The evoked motion perceptions were not associated with eye movements or any particular localization of the epileptic focus. These perceptions were only evoked once outside of the medial PO region at the 61 sites examined. The results suggest that the medial parieto-occipital region is closely linked to the human visual motion processing system.     

The effect on corticospinal volleys of reversing the direction of current induced in the motor cortex by transcranial magnetic stimulation

Descending corticospinal volleys were recorded from a bipolar electrode inserted into the cervical epidural space of four conscious human subjects after monophasic transcranial magnetic stimulation over the motor cortex with a figure-of-eight coil. We examined the effect of reversing the direction of the induced current in the brain from the usual posterior-anterior (PA) direction to an anterior-posterior (AP) direction. The volleys were compared with D waves evoked by anodal electrical stimulation (two subjects) or medio-lateral magnetic stimulation (two subjects). As reported previously, PA stimulation preferentially recruited I1 waves, with later I waves appearing at higher stimulus intensities. AP stimulation tended to recruit later I waves (I3 waves) in one of the subjects, but, in the other three, I1 or D waves were seen. Unexpectedly, the descending volleys evoked by AP stimulation often had slightly different peak latencies and/or longer duration than those seen after PA stimulation. In addition the relationship between the size of the descending volleys and the subsequent EMG response was often different for AP and PA stimulation. These findings suggest that AP stimulation does not simply activate a subset of the sites activated by PA stimulation. Some sites or neurones that are relatively inaccessible to PA stimulation may be the low-threshold targets of AP stimulation.     

Experimentally induced arousals during sleep: a cross-modality matching paradigm

Micro-arousals occur spontaneously or in response to exogenous and endogenous sensory input during sleep. The function of micro-arousals remains unclear, for example, whether it reflects a disturbance or a preparatory response to environmental changes. The goal of this study was to assess arousal responsiveness when two types of sensory stimulations were used: auditory (AD) alone and the addition of a vibrotactile (VT) sensation. Ten normal sleepers participated in three nights of polygraphic recordings. The first night was for habituation and to rule out sleep disorders, and the second to collect baseline sleep data. During the third night, AD and VT + AD stimuli, with three levels of intensities for auditory and vibratory signals, were randomly given to induce arousal responses in sleep stages 2, 3 and 4 and rapid eye movement (REM). The frequency of the arousal responses increased with stimulus intensity for all sleep stages and was lowest in stages 3 and 4. In non-REM (NREM) sleep, combined VT + AD stimulation induced more frequent and more intense arousal responses than AD alone. In REM sleep, more frequent micro-arousals rather than awakenings were triggered by combined stimulations. In stage 2, the response rate of total induced K-complexes did not differ between both types of stimulations while more K-complexes followed by arousals were evoked by the combined VT + AD stimulation than by the AD alone. The induced arousals were associated with an increase in heart rate in all sleep stages. An increase in suprahyoid muscle tone was observed in NREM sleep only, REM being not associated with a rise in muscle tone following experimental stimulation. Most leg and body movements occurred in response to induced awakenings. These results suggest that the cross-modality sensory stimuli triggered more arousal responses in comparison with single-modality stimuli. In an attempt to wake a sleeping subject, the addition of a tactile stimulation, such as shaking the shoulder, is an effective strategy that increases the arousal probability.     

脑梗死患者的运动及体感诱发电位研究

目的：研究脑梗死患者的运动诱发电位（ＭＥＰ）及体感诱发电位（ＳＥＰ）改变。方法：对３０便脑梗死患者在急性期行经颅磁刺激ＭＥＰ检测,对其中２０例同时行电刺激ＳＥＰ检测,１０例患者２月后复查ＭＥＰ,并以３０例健康者作为正常对照组。结果：急性期ＭＥＰ的异常率为９３％,主要表现为皮层ＭＥＰ消失,中枢运动传导时间（ＣＭＣＴ）延长,波形异常及阈刺激强度增高。ＳＥＰ的异常率为３０％,表现为皮层波的缺失及中枢传导时间延长。复查ＭＥＰ有９例明显改善。结论：对于脑梗死的诊断,ＭＥＰ较ＳＥＰ敏感,但将ＭＥＰ与ＳＥＰ联合应用,可从不同的两个侧面反映运动及感觉功能受损的情况,弥补了ＣＴ仅能提供颅内解剖学改变而不能反映功能状态的不足。     

Modelling of auditory evoked potentials of human sleep-wake states

The shape of evoked potentials is influenced by the level of vigilance, varying with sleep-wake states. In this paper the shape of auditory evoked potentials is modelled by taking two factors, both modulating the underlying neuronal substrate, into account: 'sensory gating' and 'neuronal firing mode'. Under low levels of vigilance sensory gating reduces the amount of neuronal activity reaching the cortical centres. Due to a rise in hyperpolarisations of thalamocortical neurons associated with an increasing depth of sleep, stimulus evoked primary and secondary excitations, seen as correlates of the N1 and N2 waves of the evoked potential, become smaller. Heightened hyperpolarisations also change the spontaneous activity of neurons from the 'tonic' firing mode of wakefulness into the 'burst-pause' firing mode of sleep. The large P220 complex together with the N350 and N550 waves in sleep are caused by the stimulus induced triggering of pauses and bursting of neurons. The results of this modelling experiment confirm the view that sleep-specific components such as P220, N350 and N550 are waves that facilitate and protect sleep, whereas the wake-specific components N1, P2-P3 and N2 have perceptual-cognitive functions. In particular the wake P2-P3 wave is sensitive to cognitive functions, such as attention. Based on the modelling results it is suggested that component negativities, expressed in N1, N2 and N350, reflect excitatory processes, whereas positivity in P2-P3 and P220 is a correlate of inhibitory processes. Hence, the large P3 in an attended condition is also interpreted as an inhibitory process suppressing irrelevant information, facilitation the saliency of relevant information.     

Different modulation of the cortical silent period by two phases of short interval intracortical inhibition

PURPOSE: To investigate the influence of 2 phases of short interval intracortical inhibition (SICI) on the cortical silent period (SP). MATERIALS AND METHODS: Single- and paired-pulse transcranial magnetic stimulations (TMSs) at 1 and 2.5ms interstimulus intervals (ISIs) were applied to the left motor cortex in 12 healthy subjects while their right hand muscles were moderately activated. Conditioning stimulation intensity was 90% of the active motor threshold (AMT). Test stimulation intensities were 120, 140, 160, 180, 200, 220, 240, 260% of the AMT and at 100% of the maximal stimulator output, the order of which was arranged randomly. The rectified electromyography area of motor evoked potential (MEP) and duration of the SP were measured off-line using a computerized program. RESULTS: At high-test stimulation intensities, MEP areas were saturated in both single- and paired-pulse stimulations, except that saturated MEPs were smaller for the paired-pulse TMS at 1ms ISI than for the other conditions. As the test stimulation intensity increased, SP was progressively prolonged in both single- and paired-pulse stimulations but was shorter in paired-pulse than single-pulse TMS. Overall, the ratio of SP duration/MEP area was comparable between single- and paired-pulse TMS except for the paired-pulse TMS at 1 ms ISI with a test stimulation intensity at 140-180% of the AMT, in which the ratio was significantly higher than in the single pulse TMS. CONCLUSION: These results suggest that 2 phases of SICI modulate MEP saturation and SP duration differently and provide additional evidence supporting the view that 2 phases of SICI are mediated by different inhibitory mechanisms.     

不同手按键对事件相关电位的影响

对30名正常青年人分别采用左、右手按键测定听觉事件相关电位(ERP)。我们发现,当靶刺激或非靶刺激出现时,不同的手按键,各导联诱发的P_3或P_2波的潜伏期无明显差异(P>0.05),但当靶刺激出现时,不同的手按键能引起按键手对侧半球后部P_3波电位值的降低,而颅顶中线各导联之P_3波电位值无明显差异。     

Effects of voluntary contraction on descending volleys evoked by transcranial electrical stimulation over the motor cortex hand area in conscious humans

 The spinal volleys evoked by electric anodal and cathodal stimulation over the cerebral motor cortex hand area were recorded from a bipolar electrode inserted into the cervical epidural space of two conscious human subjects. We measured the size of volleys elicited by electric stimulation at active motor threshold and at 3% of maximum stimulator output above this value with subjects at rest and during maximum voluntary contraction of the contralateral first dorsal interosseous muscle. Surface EMG activity was recorded at the same time. Electrical anodal stimulation evoked a single negative wave that we termed D-wave in analogy with data in experimental animals. Cathodal stimulation evoked a single negative wave with a latency of 0.2 ms longer than the D-wave recruited by anodal stimulation. At both intensities tested, voluntary contraction did not modify the amplitude of the descending waves. We conclude that changes in cortical excitability induced by voluntary activity do not modify the corticospinal volley evoked by electric stimulation and that the D-waves evoked by both anodal and cathodal electric stimulation are probably initiated several nodes distant to the cell body. Received: 9 September 1998 / Accepted: 21 October 1998     

Motor control of the costal and crural diaphragm--insights from transcranial magnetic stimulation in man

The costal and crural parts of the diaphragm differ in their embryological development and physiological function. It is not known if this is reflected in differences in their motor cortical representation. We compared the response of the costal and crural diaphragms using varying intensities of transcranial magnetic stimulation of the motor cortex at rest and during submaximal and maximal inspiratory efforts. The costal and crural motor evoked potential recruitment curves during submaximal inspiratory efforts were similar. The response to stimulation before, during and at 10 and 30 min after 44 consecutive maximal inspiratory efforts was also the same. Using paired stimulations to investigate intra-cortical facilitatory and inhibitory circuits we found no difference between the costal and crural response with varying interstimulus intervals, or when conditioning and test stimulus intensity were varied. We conclude that supraspinal control of the costal and crural diaphragm is identical during inspiratory tasks.