视听联合刺激的跨感觉通道诱发电位源的分析

运用偶极子源分析方法分析视听单独刺激和联合刺激下脑区的区别和联系.采用64道脑电采集系统,记录了7名被试者在视觉、听觉和视听联合刺激下的脑诱发电位,并分别在初期、早期和晚期时间段对这3种任务做偶极子源分析.通过比较视听联合刺激和视听单独刺激下偶极子源的变化,可以得到视听联合刺激下的源不等于单独视听刺激下的源的简单叠加,从而提示存在视听相互作用的区域.     

视觉事件相关电位

一、概况 事件相关电位(event-related potential,ERP)1965年由Sutton提出。一般认为有广义和狭义之说,广义指ERP的全部成分,包括P1、N1、P2、N2、P3,MMN、N400、CNV,而狭义仅指P1、N1、P2、N2、N3。关于刺激模式,国内外大多采用听觉刺激。目前国内使用的仪器     

三音听觉刺激事件相关电位P300的初步研究

目的：观察不同注意状态下三音P300的特点及其初步应用价值。方法：对42名受试者进行三音和传统二音odd-ball诱发P300检测,并将不同状态下的三音P300与二音P300进行比较。结果：低概率靶刺激（r-T)和低概率双靶刺激（r-dT)状态下的P300潜伏期短,波高,二者间无明显差异,低概率非靶刺激（r-nT)P300和二音P300的潜伏期和波幅也无明显差异,但r-T和r-dT与r-nT和二音P300间差异显著。刺激的物理特性和记录部位对三音P300的影响不明显。结论：注意是影响三音P300的重要因素,三音P300反映注意等认知功能的变化方面比传统二音P300更灵敏而准确,有较好的临床应用前景。     

大鼠事件相关电位的立体声听觉刺激装置的研制和应用

大鼠事件相关电位的立体声听觉刺激装置的研制和应用暨南大学医学院生理学教研室（广州５１０６３２）林坚，林兴会，王子栋Ｐ３００是以作业的某种事件有锁时关系的脑电信号为基础的一种事件相关电位（ｅｖｏｋｅｄｒｅｌａｔｅｄｐｏｔｅｎｔｉａｌ，简称ＥＲＰ［１］，...     

三音听觉刺激事件相关电位P_(300)的初步研究

目的 :观察不同注意状态下三音P3 0 0 的特点及其初步应用价值。方法 :对 42名受试者进行三音和传统二音odd ball诱发P3 0 0 检测 ,并将不同状态下的三音P3 0 0 与二音P3 0 0 进行比较。结果 :低概率靶刺激 (r T)和低概率双靶刺激 (r dT)状态下的P3 0 0 潜伏期短、波幅高 ,二者间无明显差异 ,低概率非靶刺激 (r nT)P3 0 0 和二音P3 0 0 的潜伏期和波幅也无明显差异 ,但r T和r dT与r nT和二音P3 0 0 间差异显著。刺激的物理特性和记录部位对三音P3 0 0 的影响不明显。结论 :注意是影响三音P3 0 0 的重要因素。三音P3 0 0 反映注意等认知功能的变化方面比传统二音P3 0 0 更灵敏而准确 ,有较好的临床应用前景     

抑郁性神经症患者的听觉事件相关电位分析

近年来 ,抑郁神经症在综合医院神经科门诊日见增多。对其认知功能的评定 ,国内研究尚少。笔者自 2 0 0 0年 6月至 2 0 0 1年 5月 ,共检测 5 0例抑郁性神经症患者的听觉事件相关电位 (ＥＲＰ)Ｐ30 0波幅和潜伏期 ,并与健康人群作对照分析 ,以期为抑郁性神经症认知功能的评定提供客观资料。1　资料与方法1 1　病例选择病例组 5 0例 ,皆为我院神经科门诊或住院患者 ,符合ＣＣＭＤ Ⅱ Ｒ抑郁性神经症的诊断标准。按抑郁临床相分成轻度和中度二组。轻度组自评抑郁量表 (ＳＤＳ)评分指数 (各条目累计分 / 80 )为 0 .5 0～ 0 .5 9,中度组ＳＤＳ评分…     

刺激间隔对事件相关电位N270的影响

目的：观察刺激间隔对颜色冲突诱发的事件相关电位Ｎ２７０的影响。方法：采用美国Ｎｅｕｒｏｓｃａｎ脑电诱发电位工作站,对１５名健康受试做刺激匹配的事件相关电位研究,要求受试判断前后两个刺激的颜色是否相同,并作出按键反应,每对刺激以不同的刺激间隔呈现（ｏｍｓ,１５０ｍｓ,５００ｍｓ,１０００ｍｓ）,结果;５００ｍｓ和１０００ｍｓ状态,当一对刺激颜色不同时,在第二个刺激出现后约２７０ｍｓ处从头皮可记录     

癫痫大鼠听觉事件相关电位P3样波的研究

目的：研究正常大鼠听觉事件相关电位（ERP）的P3样波（下简称听觉P3样电位）特点及癫痫大鼠P3样电位变化。方法：癫痫组大鼠每日予戊四氮腹腔注射，直至达到点燃标准，正常组大鼠每日注射生理盐水。记录并分析两组动物听觉ERP特点及其P3样电位的变化。结果：（1）在大鼠可发现与人类听觉ERP的P3电位波形、潜伏期及反应特点相似的ERP；（2）癫痫大鼠与正常大鼠相比，其P3样电位的听觉ERP的P3电位潜伏期明显延长（P＜0．01），波幅相对降低（P＞0．05），波形分化不清。结论：P3样电位的产生具有跨越种属的相似性，提示P3样电位在哺乳动物中可能具有共同的神经回路。     

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。     

化学刺激诱发的人嗅觉相关电位

选取 2 0例主观嗅觉正常的健康青年人 ,将 0 3mL醋酸异戊酯饱和气在吸气早期释放入右侧鼻腔 ,反复刺激16次 ,刺激间隔约 6 0s,在头皮中央点 (Cz)处记录到稳定的相关电位。刺激前应用洁净空气做对照试验 ,无可辩波形引出。证明该相关电位系由醋酸异戊酯刺激嗅觉系统而产生。嗅觉相关电位波形主要由P1 、N1 、P2 、N2 、P3五个波组成 ,各波的潜伏期 (ms) :P1 :2 2 2± 2 5 ,N1 :2 6 5± 31,P2 :36 4± 4 0 ,N2 :4 90± 4 7,P3:5 77± 71;振幅 (μV) :P1 :0 5 1±4 5 1,N1 :- 5 2 3± 4 18,P2 :6 83± 3 78,N2 :- 7 35± 4 18,P3:- 2 82± 4 2 5。N1 P2 的峰 -峰振幅 (μV) :12 99± 5 6 2。     

A current source density analysis of field potentials evoked in slices of visual cortex

Summary The method of one-dimensional current source density (CSD) analysis was applied to field potentials recorded from 350 m thick slices of the primary visual cortex of rats and cats. Field potentials were elicited by stimulation of the white matter and recorded along trajectories perpendicular to the cortical layers at spatial intervals of 25 to 50 m. The resulting CSD distributions resembled closely those recorded from the cat visual cortex in vivo. The responses with the shortest latency were distinct sinks in layers IV and VI probably reflecting monosynaptic EPSP's from specific thalamic afferents. From layer IV activity was relayed along three major routes: 1. to the supragranular layers via strong local connections to layer III and from there via both short and long range connections to layer II, 2. to targets within layer IV, and 3. to layer V. The source distributions suggest that the projections to layers III and II terminate on the proximal and distal segments, respectively, of apical dendrites of layer III pyramidal cells while the projection to layer V contacts the apical dendrites of layer VI pyramidal cells. These results indicate that all the excitatory pathways that are detectable with the CSD technique in the in vivo preparation remain intact in 350 m thick cortical slices. However, in the slice paired pulse stimulation did not lead to a depression of the response to the second stimulus while this is the case in vivo. This might be due to reduced inhibition in the slice which has been reported by several authors.     

Sources of attention-sensitive visual event-related potentials

Summary In a study of the neural processes that mediate visual attention in humans, 32-channel recordings of event-related potentials were obtained from 14 normal subjects while they performed a spatial attention task. The generator locations of the early C1, P1, and Nl components of the visual evoked response were estimated by means of topographic maps of voltage and current source density in conjunction with dipole modelling. The topography of the C1 component (ca. 85 ms post-stimulus) was consistent with a generator in striate cortex, and this component was unaffected by attention. In contrast, the P1 and Nl components (ca. 95 and 170ms) exhibited current density foci at scalp sites overlying lateral extrastriate cortex and were larger for attended stimuli than for unattended stimuli. The voltage topographies in the 75–175 ms latency range were modeled with a 5-dipole configuration consisting of a single striate dipole and left-right pairs of dipoles located in lateral extrastriate and inferior occipito-temporal areas. This model was found to account for the voltage topographies produced by both attended and unattended stimuli with low residual variance. These results support the proposal that visual-spatial attention modulates neural activity in extrastriate visual cortex but does not affect the initial evoked response in striate cortex.This study was supported by ONR Contract N00014-89-J-1806, by grants from NIMH (MH-25594), NINCDS (NS 17778), the Human Frontier Science Program, DGICYT (PM92-0128), and by a Fulbright scholarship to the first author.     

Auditory and somatosensory event-related brain potentials in early blind humans

Previous event-related potential (ERP) studies have suggested a possible participation of the visual cortex of the blind in auditory processing. In the present study, somatosensory and auditory ERPs of blind and sighted subjects were recorded when subjects were instructed to attend to stimuli of one modality and to ignore those of the other. Both modalities were stimulated with frequent (standard) and infrequent (deviant) stimuli, which differed from one another in their spatial locus of origin. In the sighted, deviant stimuli of the attended modality elicited N2 type of deflections (auditory N2b and somatosensory N250) over the lateral scalp areas. In contrast, in the blind, these ERP components were centroposteriorly distributed, suggesting an involvement of posterior brain areas in auditory and somatosensory stimulus discrimination. In addition, the mismatch negativity, elicited by deviant auditory stimuli even when the somatosensory stimuli were attended, was larger in the blind than in the sighted. This appears to indicate enhanced automatic processing of auditory stimulus changes in the blind. Thus, the present data suggest several compensatory changes in both auditory and somatosensory modalities after the onset of early visual deprivation.     

Unsupervised clustering of evoked potentials by waveform

A procedure for clustering evoked potentials (EPs) according to their waveforms is presented. Clustering is performed without a priori selection of basis waveforms, the number of basis waveforms or the number of clusters. The method uses the principal-component-analysis coefficients of EP records as features for unsupervised optimal fuzzy clustering (UOFC) of the records. The validity of the procedure is demonstrated in two instances: visual evoked potentials (VEPs) and cognitive event-related potentials (ERPs) from humans in a memory-scanning task. In the clustering of VEPs, the procedure differentiates between waveforms judged to be clinically normal and abnormal. In the clustering of ERPs, the procedure correctly differentiates between waveforms evoked by the same stimuli which differ in their context to the performance of a memory-scanning task (memorised items against probes). Within this classification, the procedure detects two subgroups to probeevoked waveforms, which are not obvious from visual inspection of the waveforms. The advantage of the procedure, which conducts clustering by UOFC, is the adaptive and machine-learning nature of its operation.     

Cortical sources of event-related potentials in the prosaccade and antisaccade task

The cortical sources of event-related potentials (ERP) were examined in a prosaccade and antisaccade task in college-age participants. The task included a cue that indicated the spatial location of the target, a cue that indicated the type of eye movement, or no cue. A principal component analysis and equivalent current dipole analysis showed that a peripheral spatial cue resulted in extrastriate activity localized in Brodmann's area 19 whereas a central cue results in activity in areas 19 or 37. This extrastriate activity reflects an enhanced response to the target when attention was directed to that location. The presaccadic ERP activity primarily consisted of a contralateral positive potential and ipsilateral negative potential, localized in Brodmann's areas 8, 10, and 11. The temporal proximity of this cortical activity and its relation to movement cueing suggests it reflects eye movement planning processes.     

An investigation of the auditory streaming effect using event-related brain potentials

There is uncertainty concerning the extent to which the auditory streaming effect is a function of attentive or preattentive mechanisms. The mismatch negativity (MMN), which indexes preattentive acoustic processing, was used to probe whether the segregation associated with the streaming effect occurs preattentively. In Experiment 1, alternating high and low those were presented at fast and slow paces while subjects ignored the stimuli. At the slow pace, tones were heard as alternating high and low pitches, and no MMN was elicited. At the fast pace a streaming effect was induced and an MMN was observed for the low stream, indicating a preattentive locus for the streaming effect. The high deviant did not elicit an MMN. MMNs were obtained to both the high and low deviants when the interval between the across-stream deviance was lengthened to more than 250 ms in Experiment 2, indicating that the MMN system is susceptible to processing constraints.     

Principal component analysis of event-related potentials: Misallocation of variance revisited

Misallocating variance, in event-related potential analysis, refers to attributing an experimental effect to components not actually affected. A vector interpretation of the relationship between mathematically derived and true underlying components shows that misallocation depends exclusively on incorrect identification of the affected component. Simulations, using seven imperfect rotations, confirmed all predictions from the vector interpretation concerning the presence, direction, and size of misallocated variance. Contrary to principal component analysis (PCA), Möucks's topographic component model (TCM) is not subject to rotation problems. These two methods were compared over 100 simulations in which the components had constant waveforms and topographies across participants. The group effect was always detected, but only PCA and not TCM showed significance on other components, except when their random weights happened to differ between groups.     

Tracking the voluntary control of auditory spatial attention with event-related brain potentials

A lateralized event-related potential (ERP) component elicited by attention-directing cues (ADAN) has been linked to frontal-lobe control but is often absent when spatial attention is deployed in the auditory modality. Here, we tested the hypothesis that ERP activity associated with frontal-lobe control of auditory spatial attention is distributed bilaterally by comparing ERPs elicited by attention-directing cues and neutral cues in a unimodal auditory task. This revealed an initial ERP positivity over the anterior scalp and a later ERP negativity over the parietal scalp. Distributed source analysis indicated that the anterior positivity was generated primarily in bilateral prefrontal cortices, whereas the more posterior negativity was generated in parietal and temporal cortices. The anterior ERP positivity likely reflects frontal-lobe attentional control, whereas the subsequent ERP negativity likely reflects anticipatory biasing of activity in auditory cortex.     

精神运动性癫痫患者脑诱发电位初步观察

目的研究脑诱发电位在精神运动性癫痫病人的应用。方法应用诱发电位仪对１６例精神运动性癫痫的听觉诱发电位（ＡＥＰ）、视觉诱发电位（ＶＥＰ）和听觉事件相关电位（听觉Ｐ３００）作了检测，并与正常对照组进行了比较。结果患者组波形变异大，潜伏期ＡＥＰ的Ｐ２、Ｐ３，ＶＥＰ的Ｎ１、Ｐ２以及Ｐ３００靶刺激的Ｐ２、Ｎ２均延迟，非靶刺激的Ｎ１前移。波幅ＡＥＰ的Ｐ２、ＶＥＰ的Ｐ２、Ｐ３降低，与正常对照组有显著性差异。结论ＢＥＰ技术可作为脑电图检查的一种补充手段，以便临床参考诊断此类病征。     

Modulation of event-related potentials by word repetition: The role of visual selective attention

Event-related potentials (ERPs) were recorded while subjects viewed visually presented words, some of which occurred twice. Each trial consisted of two colored letter strings, the requirement being to attend to and make a word/non word discrimination for one of the strings. Attention was manipulated by color in Experiment 1, and color and a precue were used in Experiment 2. As in previous ERP studies of word repetition, a positive offset to repeated words developed when both first and second presentations were the focus of attention. In Experiment 2, ERPs showed evidence of positive-going repetition effects in all conditions in which at least one of the two presentations of the repeated word was attended. In the visual modality, the positive-going ERP repetition effect occurs only when at least one of the two presentations of a repeated item is the object of attention, which suggests that one or more of the processes reflected by the effect is capacity limited.