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、听感知下模拟驾驶行为的脑电实验比较研究

目的 研究基于视觉、听觉以及视听融合感知的刺激源对脑电(EEG)识别率的影响。方法试验分别从视觉、听觉和视听融合3种情况提供与交通环境相关的刺激源,在不同刺激源的提示下,受试者利用左右手想象运动对车辆进行启动和制动控制,并对采集的脑电数据进行特征提取和分类处理,得到与想象运动相关的C3、C4导联上的特征信号和分类结果。...     

视听觉刺激下大脑头皮电位空间变化特性

目的:脑机接口（BCI）技术可以为肢体残障人士提供一种新的交流方式,在医疗康复领域具有很好的应用前景。目前单一视觉刺激的BCI系统难以适用于实际场合中多感觉信息输入的情况,需要进一步了解听觉刺激对视觉诱发电位的影响,为视听混合刺激下的BCI技术研究提供依据。 方法:在闪光刺激为12和42 Hz条件下分别加入12和42 Hz的听觉刺激,研究听觉刺激的加入对视觉刺激下大脑头表额、枕、中央、顶、颞5个空间点脑电功率的影响。 结果:视听脉冲同时刺激条件下,枕区脑电功率最大,其余空间点的功率随测试点到枕区距离的增加而减少;与单一视觉刺激下空间某点的脑电功率相比,听觉刺激的加入对该点脑电功率起增强还是抑制作用,主要取决于该点的空间位置。 结论:研究结果为听觉刺激和视觉刺激在BCI中的整合及多模态脑机接口的研究提供有意义的实验依据。     

体感电刺激诱发事件相关电位的研究

目的对视觉、听觉、体感3种不同模态下靶刺激诱发的事件相关电位(ERP)进行比较研究,探讨体感电刺激作为脑机接口(BCI)一种新的信号诱发模式的可能性,为基于体感ERP的BCI研究提供理论依据。方法选择17例视力或矫正视力正常、听力正常、躯体感觉正常且无任何大脑病史的被试者,其中男性8例,女性9例;年龄20~26岁,平均年龄22.6岁;均为右利手。分别记录17例健康的被试者在视觉、听觉、体感单通道靶刺激下诱发的脑电图;对3类靶刺激下ERP的时域参数(幅值、潜伏期)、行为学数据(反应时间、错误率)、脑源定位进行比较分析。结果 3类靶刺激模式下的ERP波形具有相似性,体感电刺激诱发的ERP幅值与视觉、听觉靶刺激相比无显著性差异;体感电刺激诱发ERP的峰值潜伏期显著长于视觉靶刺激;体感电刺激的反应时间显著长于视觉靶刺激,错误率也高于视觉、听觉靶刺激;体感电刺激诱发ERP的脑内源与视觉靶刺激相比具有相似性。结论相比于视觉、听觉靶刺激,大脑对于体感电刺激的探测难度高,敏感程度低;但从ERP的波形和幅值上看,体感电刺激可以诱发出稳定的、可被检测到的ERP波形,完全有可能应用于BCI系统作为一种新的ERP诱发模式。     

磁刺激内关穴的脑电源定位分析

与传统的针灸和电针刺激相比,磁刺激具有无创、无痛、不接触、易于操作等良好的安全性能.对磁刺激内关穴的脑电信号提取诱发电位并进行等效偶极子源定位分析研究.利用磁刺激仪对内关穴(PC6)及内关穴附近非穴位点(假穴)进行了相同强度、相同频率的磁刺激,分析了同步采集的脑电信号的诱发电位并对其进行了等效偶极子源定位研究.结果表明...     

基于FPGA的随机字符发生器在ERP中的应用

脑电领域的众多探索一直以来都是各国科学家研究的热点.刺激源是脑电实验中不可或缺的一部分.刺激序列正确编排和稳定发生是诱发脑电信号被正确提取的先决条件.利用可编程逻辑器件作为随机字符信号发生器,使之同时具有计数和VGA显示功能,由此产生的视觉ERP刺激序列,可以作为脑区功能存在病变的病人的理想刺激源.     

视觉听觉同时刺激模式下ERP的同步性研究

目的：研究视觉、听觉脑区在认知过程中的同步性。方法：设计了视觉、听觉同时刺激模式下的脑电实验，采用128道高密度脑电采集系统，记录了14位年龄在18～29岁之间的在校男性大学生的诱发脑电信号数据，并运用希尔伯特(Hilbert)相位同步算法对视觉、听觉区域的事件相关电位(ERP)进行同步量化。结果：在视听觉同时利用模式下，视觉脑区(枕叶)和听觉脑区(颞叶)之间的同步指数明显大于它们与其他脑区间的同步指数。结论：人在感知和认知事物时，相关的脑区间自动产生了神经活动的同步化。     

正常青年人视觉、听觉诱发的ERP的比较

对３５例正常青年人同时进行视觉、听觉不同刺激模式检测到的事件相关电位（ＥＲＰ）进行比较分析，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。本文对其原因和不同年龄的Ｐ３波在颅顶有不同的分布部位以及其中一些Ｐ３波电位值两半球不对称性的机理进行了初步探讨。     

视、听感觉刺激双模增进作用研究

目的 研究了视(V)、听(A)单模靶刺激与视听双模联合靶刺激(VA)条件下大脑认知作用的差异,进而讨论了双模增进作用的神经机制.方法 采用64道脑电(EEG)信号采集系统,记录了14个被试者在视觉、听觉和视听联合靶刺激条件下的脑诱发电位和行为学数据.检测了单模与双模间行为学[反应时间(RT)与错误率(ER)]和事件相关电位(ERPs)(P2峰值和峰值潜伏期,P3峰值和峰值潜伏期)结果的差异;分析了行为学与ERPs数据间的相关性.结果 结果显示RT、ER和P3峰值潜伏期在单模与双模间的差异具有统计学意义;P3峰值潜伏期与行为学数据特别是反应时间有显著性相关.结论 通过对比视听双模靶刺激和视、听单模靶刺激的行为学和ERPs结果,提示相对视、听单模靶刺激,视听双模靶刺激不仅在早期ERP成份(P1和N1)而且在晚期ERP成分(P2和P3),都表现出优越的感觉信号神经处理机制.     

焦虑症患者的听觉P300偶极子源分析

目的:研究焦虑症患者的听觉事件相关电位P300的偶极子模型及特征.方法:选择焦虑症患者25例和正常人28名,记录受试者32导听觉事件相关电位P300,并采用ASA脑源分析软件建立偶极子电流源模型,提取偶极子电流波形的P300波幅参数;对照正常人研究焦虑症患者偶极子参数的异常特征.结果:通过多因素方差分析发现焦虑症组和正常对照组都呈现偶极子波幅的左右脑半区非对称性,右半区波幅高于左半区,而且焦虑症组的这一非对称性更强,研究还发现在焦虑症组中,位于脑后区左右颞叶位置的一对偶极子呈现的非对称性最强.结论:通过多导联记录听觉P300,并采用偶极子电流源分析方法,研究发现了焦虑症患者以左侧颞叶偶极子活动异常为主的电生理特征,这一结论有助于阐明焦虑症发病机理,提高P300诊断焦虑症的特异性水平.     

A Nonparametric Statistical Evaluation of Changes in Evoked Potentials to Different Stimuli

An experiment yielding the evoked electroencephalographic potentials (EPs) to seven different stimuli was conducted on a population of 13 female and 7 male normal subjects. Patterned-visual, auditory and combined (bimodal) stimuli were used. One stimulus case required subject responses. Calculations of the first four statistical sample moments at the EP time points indicated nongaussian amplitude distributions. A nonparametric statistical test, the Mann-Whitney (U-test, was used to den it the significant point (p <.01) differences among the EPs to the visual, auditory and bimodal stimuli. The most extensive differences were obtained from EPs to stimulus pairs requiring subject response (identification). Differences among the EPs to different visual patterns existed to a lesser extent than to stimuli of different sensory modalities. In general, a change in the physical parameter of the stimulus induced changes in the earlier components, while the response requirement induced changes in the late components of the EP. No significant differences were found in EPs to the same stimuli between recording locations with hemispheric symmetry.     

Development of multimodal attention in young infants: modification of the startle reflex by attention

This study examined the effect of attention engagement to compound auditory-visual stimuli on the modification of the startle blink reflex in infants. Infants at 8, 14, 20, or 26 weeks of age were presented with interesting audiovisual stimuli. After stimulus onset, at delays defined by heart rate changes known to be associated with sustained attention or attention disengagement, blink reflexes were elicited by visual or auditory stimuli. Blink amplitude to either visual or auditory stimuli was enhanced when the infants were engaged in attention to the foreground auditory-visual stimuli relative to control trials with no foreground patterns. This enhancement of the blink amplitude increased from 8 to 26 weeks of age. In contrast to selective modality enhancement for single-modality foreground stimuli, these results show that these multimodal stimuli engage both visual and auditory attention systems in this age range.     

Similarities and Differences Among the P3 Waves to Detected Signals in Three Modalities

Event-related brain potentials were recorded from the scalp while subjects detected visual, auditory, and somatosensory stimuli presented near threshold. The waveforms were characterized by large, late-positive (P3) waves to signal detections in all three modalities. The scalp distributions of these P3s revealed no substantial differences among the three modalities. There were, however, reliable latency and amplitude differences, with the P3 to visual signals occurring later than to somatic (Study 1) or to auditory (Study 2) signals. Further, the P3s to detected visual signals were substantially larger than those to auditory or somatosensory signals. Taken together, the data suggest that P3 waves to all modalities arise from a common neural generating system but that visual signals access this system in a different fashion from the other modalities.     

便携式听觉稳态诱发响应声音刺激器设计

目的 听觉稳态诱发响应（auditory steady state response,ASSR）对大脑的听觉系统研究有重要意义,但传统的用于ASSR实验的刺激设备较为昂贵且使用不便,本文给出一种便携式听觉刺激器的设计方案.方法 以TI的TMS320C5515芯片作为核心处理器,利用SD卡存储用于声音刺激的配置文件以及声音数据,通过主芯片提供的SD卡接口及DMA通道读取声音数据,然后经过I2S总线,传递数据至音频编解码器中,最后完成声音的播放.该系统提供可视化的界面,供用户选择配置文件.同时提供一个基于MATLAB的工具包,用于将普通的音乐格式转化为系统兼容的声音数据格式.结果 本系统支持8～ 192 kHz的声音采样率,支持单声道和立体声,支持声音位宽包括16位和32位,且允许输出声压级在87.5 dB的动态范围内变化,变化的步长为0.5dB.为验证本系统的实用性,4个受试参与了一系列ASSR实验,获得了预期的实验结果.结论 本系统可用于ASSR实验中,且系统可保证长时间稳定频率的声音输出,因系统功耗小于200 mW,如果使用1000 mA·h的3.7V的锂电池供电,则系统可持续工作超过18.5 h.     

Stimulus complexity effects on the event-related potentials to task-irrelevant stimuli

The effects of irrelevant stimuli complexity on event-related potentials were investigated in 3 conditions using both auditory and visual oddball tasks. In Conditions 1 and 2, simple standard and target stimuli were presented in series with complex, identical (Condition 1) or variable (Condition 2), task-irrelevant stimuli. In Condition 3, complex standards and targets were presented with simple, identical, task-irrelevant stimuli. In Conditions 1 and 2, but not Condition 3, the irrelevant stimuli elicited the P3a component in both auditory and visual modalities and the N2b component in the visual modality. While we found that variable, irrelevant stimuli evoked larger P3a in the auditory modality compared with identical irrelevant stimuli, we observed the opposite effect in the visual modality. These results suggest that stimuli rareness and irrelevance are not sufficient for eliciting P3a. This component is only elicited by irrelevant stimuli that are at least as complex as the task-related stimuli.     

Exteroceptive stimuli override interoceptive state in reaction time control

The processing of reaction time (RT) stimulus is modulated by its timing relative to the cardiac cycle. RT stimulus processing is also influenced by task‐irrelevant stimuli: a sensory stimulus speeds RT when it accompanies a cue to react in another sensory modality. Different theories have been proposed to explain this accessory stimulus effect (ASE). However, it is unclear whether the ASE interacts with the cardiac timing effect. In the present study, the relationship of the ASE, cardiac timing, and stimulus valence was examined. Fifty‐two subjects performed 400 trials of a simple RT task. Images of neutral and fear faces served as visual accessory stimuli; the RT stimulus was a 75 dB tone. Electrocardiography was recorded. Visual and auditory stimuli were presented at either cardiac systole or diastole. The stimulus onset asynchrony between visual and auditory stimuli was either 0 or 75 ms. Repeated measures ANOVAs showed that cardiac timing modulated RT, but only when accessory stimuli were absent. RT was shorter when the accessory stimulus preceded the imperative stimulus with respect to simultaneous presentation. The ASE was not influenced by visual stimulus valence or cardiac timing. Results indicate that the ASE overrides cardiac timing effects, suggesting a dynamic balance between exteroceptive stimuli and interoceptive states, and highlight the importance of embodied information processing.     

The P3 produced by auditory stimuli presented in a passive and active condition: modulation by visual stimuli

The aim of this study was to investigate how the processing of auditory stimuli is affected by the simultaneous presentation of visual stimuli. This was approached in an active and passive condition, during which a P3 was elicited in the human EEG by single auditory stimuli. Subjects were presented tones, either alone or accompanied by the simultaneous exposition of pictures. There were two different sessions. In the first, the presented tones demanded no further cognitive activity from the subjects (passive or 'ignore' session), while in the second session subjects were instructed to count the tones (active or 'count' session). The central question was whether inter-modal influences of visual stimulation in the active condition would modulate the auditory P3 in the same way as in the passive condition. Brain responses in the ignore session revealed only a small P3-like component over the parietal and frontal cortex, however, when the auditory stimuli co-occurred with the visual stimuli, an increased frontal activity in the window of 300-500 ms was observed. This could be interpreted as the reflection of a more intensive involuntary attention shift, provoked by the preceding visual stimulation. Moreover, it was found that cognitive load caused by the count instruction, resulted in an evident P3, with maximal amplitude over parietal locations. This effect was smaller when auditory stimuli were presented on the visual background. These findings might support the thesis that available resources were assigned to the analysis of visual stimulus, and thus were not available to analyze the subsequent auditory stimuli. This reduction in allocation of resources for attention was restricted to the active condition only, when the matching of a template with incoming information results in a distinct P3 component. It is discussed whether the putative source of this effect is a change in the activity of the frontal cortex.     

Age and novelty: event-related potentials to visual stimuli within an auditory oddball--visual detection task.

Age-related change of event-related potentials to novel visual stimuli was investigated while participants attended to both auditory and visual stimulation. Meaningful but irrelevant pictures (novel stimuli) were presented to younger (mean=21.8, range=18-26 years) and older (mean=70.0, range=60-78) participants (10 in each group). The participants were performing an auditory oddball task and counting silently the changes of a visually presented letter. In the younger group novel stimuli elicited a posterior positivity in the 220-255 ms range. This component habituated to the repetition of the same picture. In the older group this component had longer latency, and did not habituate. A later positivity had shorter latency and larger amplitude in the younger group, but this positivity was preceded by a negative component (N2b) only in the elderly. Results show decreased sensitivity to the content of the visual stimuli in an earlier stage of novelty processing in the elderly, and the age-related slowing of both orientation-related and task-related processes.