利用VEP测量视觉系统红,绿通道的反应时间差

本文应用彩色诱发电位（ＣＯＬＯＲ ＶＥＰ）在专门研制的双计算机互连系统，对人眼视觉系统中颜色通道的时间响应特性作初步研究，实验发现，在等主观亮度而颜色不同的棋盘格图形翻转刺激下ＶＥＰ中Ｎ１波的伏期因刺激颜色不同而不同。对实验结果的数据做统计的分析得出人眼颜色并行通道对三基色的响应有明显的差别，绿通道快于红通道。此结果１９９０年ＳＳ．Ｍ．Ｃｏｕｒｔｎｅｙａｎｄ Ｇ．Ｂｕｃｈｓｈａｕｍ提出的视觉颜色的     

基于Labview和VC的脑机接口系统设计

目的：在ActiveOne生理信号采集系统基础上采用Labview和VC编程实现基于视觉诱发电位的脑机接口实时系统。方法：数据采集软件采用Labview编程实现,采用VC编程实现脑机接口人机界面、实时信号处理及动态链接库,Labview和VC通过动态链接库共享内存实现数据传输。视觉刺激界面设计采用了多媒体定时、DirectDraw技术和并口输出技术。采用累加平均与5点平均滤波提取视觉诱发电位信号,再通过计算相关系数实现信号识别。结果：实验表明,刺激模块能产生有效的视觉刺激。基于动态链接库的数据传输能满足系统要求,实现VC与Labview程序的同步控制。结论：本文提出的实时信号处理方法能提高信噪比,实现视觉诱发电位的提取与识别,判断出受试者所注视的目标,并将结果实时反馈到人机界面．实现了脑机接口实时系统。     

脑诱发电位的三维显示,功率谱分析及其应用

常见的诱发电位仪虽然能给出波形和数据,但没有存储数据的功能,不利于病例数据的分析和判别,而且只可对波形进行时域分析。因而在临床应用中,只能局限于潜伏期、波幅的分析和判断,对一些波形难以给出正确的结论。为了开发使用MEB—5100诱发电位仪的功能,使其给出的数据更加准确,我们实现了计算机和诱发电位仪联机,建立了数据采集和     

脑电检查在脑卒中患者中的应用(续)

二诱发电位(EP) EP是中枢神经系统感受外在的或内在的刺激过程中产生的生物电活动,目前常用的诱发电位是采用光(图形、照片、闪光、词或字等)、声或低压脉冲电流分别刺激视觉系统、听觉系统或躯体感觉系统,刺激后     

大鼠三叉神经诱发电位检测方法的研究

目的 获得较佳的大鼠三叉神经诱发电位检测方法。方法 使用多导诱发电位仪在不同刺激及不同导联记录方法下检测大鼠三又神经诱发电位。结果 0．04ms波宽的电脉冲刺激和Cz-Cv7导联方法记录时，大鼠三叉神经诱发电位各导联波形重合较好，各波检出率均较高，潜伏期的标准差较小。结论 采用0.04ms渡宽电脉冲刺激和Cz-Cv7导联方法记录的大鼠三叉神经诱发电位较佳。     

运动皮质的经颅刺激产生运动诱发电位

利用诱发电位进行神经系统的监察是一种正处发展中的手段。以传统测试手段为依据而得到的一种新型诱发电位——运动诱发电位(MEP)则是利用对大脑的刺激来监察运动神经系统。MEP对现有的全感觉模式是一个补充,对运动皮质的直接刺激可产生MEP,但更普遍的一种形式就是经颅刺激。电和磁的方法都可以。电的系统包括置于运动皮质的一个电极,此电极与置于硬腭顶部的阴极配对。记录电极则置于脊髓、外周神经及肌肉上。信号记录是用一个标准的、诱发电位用的信号平均计算机。动物研究表明:电刺激首先激活椎体系统,在脊髓腹侧和背外侧产生一个下行的诱发电位。在     

视觉适应与颜色图形识别的研究

本文用计算机设计不同彩色图形，使用心理物理学方法研究视觉在不同光色适应下对颜色和图形的反应，并与诱发电位方法所得的结果进行比较，在颜色反应敏感性方面基本一致。     

视学适应与颜色图形识别的研究

本文用计算机设计不同彩色图形，使用心理物理学方法研究视觉在不同光色适应下对颜色和图形的反应，，并与诱发电位方法所得的结果进行比较，在颜色反应敏感性方面基本一致。     

ZEP系列诱发电位／肌慢图仪体感刺激器

作者介绍了ＸＥＰ系列诱发电位／肌电图仪体感刺激器的工作原理。该刺激器精确地实现了计算机对刺激频率、脉宽和强度的数字化控制，并对消除刺激器的交流干扰、实现安全隔离提供了很好的解决方法。     

ZEP系列诱发电位／肌电图仪体感刺激器

作者介绍了ＺＥＰ系列诱发电位／肌电图仪体感刺激器的工作原理。该刺激器精确地实现了计算机对刺激频率、脉宽和强度的数字化控制，并对消除刺激器的交流干扰、实现安全隔离提供了很好的解决方法。     

Visual evoked potentials induced by illusory outlines (Kanizsa's square)

This report describes studies of visual evoked potentials (VEP) in ten subjects produced in response to Kanizsa's square and a control stimulus which did not involve a visual illusion but which had a similar spatial organization. The results showed that the amplitude-time characteristics of VEP depended on the illusory outlines. Differences in the parameters of VEP produced using the two stimuli were seen in the occipital, parietal, and temporal areas. VEP amplitude differences between the peaks of the N180 and P230 waves increased and the latent period of the N300 wave decreased on presentation of the illusory outlines as compared with the control stimulus. Interstimulus differences in amplitude were seen in the left and right occipital and left temporal areas, while differences in latency were seen in the left occipital lead. The data supported the suggestion that the visual perception system includes two areas encoding illusory outlines, which are associated with different aspects of visual analysis—encoding of individual signs and their complexes (O1 andO2) and comparing sensory codes with codes stored in memory (T5). Translated from Zhurnal Vysshei Nervnoi Deyatel'nosti imeni I. P. Pavlova, Vol. 48, No. 5, pp. 807–815, September–October, 1998.     

Automatic Discrimination of Abnormal Subjects Using the Visual Evoked Potential Spectral Components

Study of visual evoked potential (VEP) is one of the utilizedmethods in clinical diagnosis of ophthalmology and neurologicaldisorders. The automatic detection of VEP spectral components isan important tool in the diagnosis of mental activity. This paperpresents a novel computational approach using feedforward neuralnetwork to identify abnormal subjects from changes in spectralcomponents. The output vector from the feedforward neural networkis based on the VEP spectral components. The software wasdeveloped to identify mental state from the VEP spectralcomponents using Matlab software package. Using this approach, itis possible to perform real-time abnormality identificationaccurately on personal computers.     

Microcomputer control of a LED stimulus display device

A visual stimulus display system controlled by a microcomputer was constructed at low cost. The system consists of a LED stimulus display device, a microcomputer, two interface boards, a pointing device (a "mouse") and two kinds of software. The first software package is written in BASIC. Its functions are: to construct stimulus patterns using the mouse, to construct letter patterns (alphabet, digit, symbols and Japanese letters--kanji, hiragana, katakana), to modify the patterns, to store the patterns on a floppy disc, to translate the patterns into integer data which are used to display the patterns in the second software. The second software package, written in BASIC and machine language, controls display of a sequence of stimulus patterns in predetermined time schedules in visual experiments.     

Deficits in the visual evoked potentials of cats as a result of visual deprivation

Summary Visual evoked potentials in response to contrast reversal of grating patterns were used as a measure of visual function in normal and visually deprived cats. In cats which had been dark reared from birth (BD cats) there was a characteristic change in VEP waveform from normal, for both eyes and for all spatial frequencies of testing stimulus. In cats which had one eye sutured from the age of one week (MD cats), the VEP from the deprived eye was smaller for contrast reversal of coarse patterns. Kittens given only restricted periods of monocular exposure gave VEPs which resembled the pathological responses of the BD cats. However, the amplitudes of response were larger for the more experienced eye at higher spatial frequency. This work reinforces the idea that two factors govern cortical development: competition and experience. Lack of sufficient visual experience leads to severe intracortical pathology.     

基于颜色VEP的色觉缺陷检测系统的研究

本研究介绍了一种基于颜色视觉诱发电位（VEP）的色觉缺陷检测系统。现代电生理检测理论认为当视觉神经系统接收到颜色刺激时，将产生相应的脑皮层电位分布。通过适当的颜色刺激诱发，能够定量地测量色觉缺陷人群的缺陷种类及缺陷程度。该系统由颜色刺激发生器、测试电极、放大滤波电路、A／D转换电路、工作主机等部分组成。系统用等亮度反转点来表征色觉缺陷的种类及程度，实现了客观定量的色觉缺陷检测要求。     

Hemispheric Asymmetries in the Visual Cortical Evoked Potential as a Function of Stimulus Location

The averaged visual cortical evoked potential (VEP) was examined in two separate experiments us a function of stimulus location. The VEP was recorded from over left and right occipital hemispheres and stimuli were presented binocularly. The results of Experiment I, in which three stimulus locations were used, indicated that stimuli presented in the left visual field resulted in shorter VKP latencies at the right occipital area than the left, while for stimuli presented in the right visual field, the opposite occurred. In Experiment II, seven locations were used and similar VEP latency asymmetries were observed. White no hemispheric amplitude asymmetries were found, there was a trend toward a decrease of VEP amplitude with increasing distance of stimulation from the fovea. The latency asymmetries may he explained in terms of the angle at which the stimuli impinge upon the retinas of the two eyes from different locations. Direct stimulation is produced at the primary projection area, whereas indirect stimulation probably occurs at the secondary area, after crossover of impulses via the corpus callosum.     

Is the Contingent Negative Variation Contingent on a Motor Response?

Ten subjects participated in an experiment in which each was presented with series of paired stimuli separated by 1000 msec. The first stimulus was a click. The second stimulus was either of two visual patterns, concentric circles or a star figure. Figure selection on each trial was determined by a random procedure. There were four experimental conditions: 1) Subjects pressed a switch following the presentation of either figure. 2) Subjects pressed a switch following the presentation of the star only. 3) Subjects guessed prior to the clicks, which figure would appear as S2; no overt motor response was required. 4) Subjects had to add 7 to a cumulative sum following a star, and subtract 7 following the circles; no overt motor response was required. Using data obtained from a vertex to linked ear derivation we conclude that the CNV is not contingent on a motor response to S2. The electrical potentials recorded following S2, and in particular the positive-going “resolution” of the CNV seemed to vary systematically with the experimental conditions. An application of Tucker's three-mode factor analysis to this CNV is reported.     

基于视觉诱发电位的脑机接口实验研究

脑机接口是一种新颖的基于脑电信号实现人脑与计算机或其他电子设备进行通讯和控制的系统 ,在康复医学工程等领域具有重要意义。作者开展了基于视觉诱发电位的脑机接口实验研究。采用计算机编程 ,在屏幕产生多种刺激模式图案 ,屏幕上闪烁的不同图案代表多种选择 ,受试者通过注视其中一个目标来作出选择。头皮电极采集枕骨粗隆部位的诱发电位信号 ,分析诱发电位信号 ,可以判别出受试者注视的目标。采用小波滤波及累加平均方法提高信噪比 ,用于提取微弱的脑电信号。离线实验数据分析表明 ,采用本文提出的方法可以有效地实现脑机接口 ,并达到较高的正确率和通信速度 ,目标为 12个时 ,通信率高于 30 bit/ min     

Stimulus Intensity Expectation and Visual Evoked Brain Potentials

In a sample of 32 adult subjects, we examined the relationship between amplitude measures of the visual evoked potential (VEP) and a subject's expectation that a stimulus would be either brighter or dimmer than the others in a series. It was found that when subjects expected a bright light flash, the VEP waveform changed in the direction associated with a stimulus intensity increase even though no actual intensity change occurred. Conversely, when subjects expected a dim light flash, the VEP waveform changed in the direction associated with a stimulus intensity decrease even though no actual intensity change occurred. The amplitude changes to the expected stimulus intensities occurred in specific VEP peaks and were related to the position of the stimulus in the sequence.