脑电-肌电信号样本熵与小波熵分析

为了探索自主动作和电刺激产生动作两种不同模式下的大脑运动皮层活动与肌肉收缩之间的关系,搭建了脑电和肌电实验测量平台,设计了自主腕部外旋和穴位电刺激两种实验动作模式,同步采集不同动作模式诱发的脑电信号和表面肌电信号,计算和分析信号的样本熵与小波熵.结果发现穴位电刺激模式下,脑电信号样本熵增大,肌电信号样本熵减小,脑-肌电的平均互样本熵增大,肌电信号的小波熵明显减小.表明穴位电刺激使大脑活动复杂性提高,肌肉活动的有序性增强,出现了优势节律,脑-肌电协同性提高.     

经穴电刺激诱发的脑-肌电信号相干性研究

为探索自主动作和穴位电刺激诱发的大脑皮层活动与肌肉收缩之间的功能耦合作用,设计穴位电刺激和自主动作两种实验模式,分别采集对应的脑电信号和表面肌电信号,对信号进行预处理得到纯净的诱发脑电和肌电信号.然后进行小波变换,获得信号的小波谱和小波交叉谱,计算小波相干系数,分析脑电和肌电信号的时-频相干特性.结果表明:穴位电刺激诱发的脑-肌电相干性主要集中在15~25 Hz信号频段,对应于大脑β节律;而自主动作下的脑-肌电相干性集中在30~36Hz频段,对应于大脑γ节律;不同导联的脑-肌电信号相干特性,表明穴位电刺激诱发的腕部肌肉动作与对侧大脑运动区相干性最强.该研究为运动功能康复和智能假肢开发奠定了基础.     

视听诱发脑电特征提取与大脑认知机理分析

为探索视听跨感觉大脑认知机理,基于Stroop效应设计视听觉刺激实验范式,利用Neuroscan40导联脑事件相关电位仪,连续动态采集视听诱发脑电信号,采用独立成分分析方法去除眼电伪迹,AR模型结合相干平均方法提取诱发脑电P300特征．通过对P300电位幅值和潜伏期的分析,研究视听觉诱发大脑认知的信息整合规律、交叉干扰作用和注意竞争效应．实验结果表明,大脑在视听双通道刺激下,更容易整合信息,具有视觉为主、听觉为辅的协同补偿作用,且视觉对听觉有较强的交叉干扰作用以及视觉为主导的竞争效应．该研究成果可以应用于神经信息处理、脑认知科学和脑一机交互系统中．     

基于屈肌声肌图的假手控制初步研究

医学超声成像是研究骨骼肌的结构形态变化特性的有效工具。通过自行开发的信号采集与控制软件,同步采集手腕屈伸时前臂屈肌的超声图像、表面肌电（Surface Electromyography,SEMG）信号以及手腕屈伸角度值。简单分析了屈肌厚度变化的声肌图（SMG）和表面肌电、手腕角度之间的关系,并初步实现了利用屈肌厚度变化SMG控制假手的张合。实验结果表明,肌肉厚度变化SMG具有控制假手的可行性。     

人对连续纯音的派生脑干反应(dABR)

继成功地记录出连续纯音诱发的听神经总合动作电位（ＣＡＰ）之后，我们又建立了提取不同频率连续纯音诱发的听觉脑干电位（ＡＢＲ）的新方法。连续纯音才是真正的纯音，用它作刺激声突破了ＣＡＰ和ＡＢＲ只能用“很不纯”的宽频瞬态声诱发的局限，有利于深入研究耳蜗及脑干水平听觉分析功能和信息处理的频率特异性。按神经生理的规律，脑干各中枢在纯音连续作用的过程中必有连续的电活动，只是后者不能很好同步地组成清晰易辨的电位。新的方法用的是派生电位处理技术，其要点是从连续纯音与一瞬态声共同作用所诱发的脑干反应中扣除该瞬态声…     

噪声对学生课堂行为的影响

强噪声对听觉的感受和辨别功能均有影响,但二者并不平行。对于后者,已有的研究尚少。本工作系统地比较了强脉冲声暴露后豚鼠的听觉感受阈及辨别阈受影响的时间、程度及恢复情况,所用强噪声为由一串波宽为0.1ms、间隔0.9ms的矩形波经扩音系统产生的宽带脉冲声,其时程为30ms,峰值强度150dBLp,每秒一次,连续暴露2小时,在预先装好慢性记录电极的清醒豚鼠上(共14耳),用单个短声及重复短声调频、调幅、调相诱发的皮层慢反应作指标,测定听阈、频率辨别阈、强度辨别阈和相位辨别阈的变化,并进行比较。主要结果如下: 1.听阈变化;在暴露后2—4小时14…     

基于少次相干平均和样本熵的视听诱发脑电特征提取

针对脑电信号的非平稳性和非线性,采用少次相干平均结合样本熵的方法对视听诱发脑电信号进行特征提取.首先,对预处理后的脑电信号进行15次相干平均,获得视觉、听觉及视听觉诱发脑电的时域特征信号;然后,将该特征信号做为原始信号输入,构成m维矢量序列,计算相关导联在靶刺激、非靶刺激和自发脑电状态的样本熵值;最后,比较分析单一视觉、听觉和视听刺激下,不同状态脑电样本熵值,文中阐明了视听觉诱发下,大脑认知的复杂性和信息耦合性.结果显示:只进行少次相干平均即可有效提取视听刺激模式下脑电的样本熵特征量,减少了因长时间视觉刺激引起神经疲劳导致的误差.同时,靶刺激的出现可使脑电样本熵值增大,表明中枢神经系统与外周刺激发生信息耦合,导致了大脑系统复杂性的提高.该研究可以应用于神经认知科学和脑-机交互系统中.     

预先暴露低强度噪声对噪声损伤听力保护作用的观察

强噪声暴露可致听力损伤，产生暂时性或永久性听阈偏移。听力损伤程度除和噪声暴露参数有关外，还和听觉系统本身的生理和代谢状态有关［１］。实验证实，外毛细胞在声刺激后有类似耳肌收缩样作用［２］，但这种收缩作用对听力的生物效应还不清楚。低强度无损害性噪声暴露对后来的强声刺激是否有保护作用，国内尚未见有报导。本实验以豚鼠为实验动物，预先暴露低剂量安全噪声，随后暴露能产生听觉损害的强噪声，观察前者对后者的听力损伤有无保护作用。     

一种表面肌电信号测试电路设计

表面肌电信号(SEMG)是一种伴随肌肉活动在皮肤表面产生的生物电信号,它蕴涵了许多肢体运动的信息,对其进行模式信息处理可以获得人-机仿生系统的控制信号.SEMG的特点是内阻高,影响因素多,并极易受到干扰.本文在分析肌电信号产生机理的基础上,给出了一种SEMG的采集、放大和滤波电路.对信号处理电路的特性分析表明,所设计的处理电路可以有效提取(10～500)Hz的肌电信号,并能对50 Hz的工频干扰起到很好的抑制作用,该电路在实际应用时取得了理想的实验结果,信号的采集能力和信噪比达到或接近美国kistler公司的肌电采集仪水平.     

压电型人工耳蜗的实验研究

系统研究了不同特性的压电陶瓷植入耳蜗及其植入位置对听阈变化的影响，实验结果表明，植入材料的机电耦合系数和电容越大，听阈下降越明显；陶瓷片置于鼓介中内侧贴于螺旋神经表面成功率最高。充分证实了压电陶瓷片植入耳蜗可模拟毛细胞进行声电转换，刺激听神经引起听觉，提高聋耳的呼力这一新构想是成功的。     

基于事件相关电位技术(ERPs)的消费者废旧手机回收方式选择决策研究

采用事件相关电位技术,研究消费者选择废旧手机回收方式的态度与行为决策。以 20名大学师生作为被试,刺激事件（以图片形式呈现）包括二手商贩/个体维修商手机回收、手机运营商设点回收和基于O2O电商平台手机回收3类手机回收方式。被试分别完成60张测试图片的实验任务。被试在评估选择过程中产生了LPP波形,并且不同刺激事件诱发的LPP波幅有明显差异。其中,在中央顶区,以手机运营商设点回收方式所诱发的与情绪有关的LPP波形,在400~500 ms窗口内,其波幅明显高于其他手机回收方式;在枕区,基于O2O电商平台手机回收方式所诱发的与认知有关的LPP波形,在700~800 ms窗口内,其波幅明显高于其他手机回收方式。该实验进一步验证了LPP成分与刺激的重要性、态度评估、注意、记忆、情绪与认知等因素有关,与决策者的决策行为也密切相关。     

双耳分听汉语普通话声调研究

系统地探讨与研究了以汉语为母语的右利手被试者对汉语普通话声调感知的偏侧优势。选取40个常用的汉语普通话单音节词作为实验材料,在合适的反应时间和信噪比下采用双耳分听范式进行声调辨别听觉感知实验。实验要求被试者从同时、分别播放到左右耳的不同声调中选出一个最清楚听到的声调,而不考虑所选的声调来自左耳还是右耳。30位听力正常的右利手被试者参与了此项实验。实验结果表明,在本研究设定的双耳分听实验条件下,汉语为母语的右利手被试者对汉语普通话声调的感知存在显著的右耳(大脑左半球)优势,且对四个声调的感知具有相同的偏侧优势;左、右耳对四个声调间感知差异的趋势基本一致,且对3声的感知显著较其余声调差。     

Driver experience and cognitive workload in different traffic environments

How do levels of cognitive workload differ between experienced and inexperienced drivers? In this study we explored cognitive workload and driver experience, using a secondary task method, the peripheral detection task (PDT) in a field study. The main results showed a large and statistically significant difference in cognitive workload levels between experienced and inexperienced drivers. Inexperienced, low mileage drivers had on average approximately 250 milliseconds (ms) longer reaction times to a peripheral stimulus, than the experienced drivers. It would, therefore, appear that drivers with better training and experience were able to automate the driving task more effectively than their less experienced counterparts in accordance with theoretical psychological models. It has been suggested that increased training and experience may provide attention resource savings that can benefit the driver in handling new or unexpected traffic situations.     

基于ERP的扁平化与拟物化图标认知效率研究

目的研究扁平化和拟物化图标对使用者认知效率的影响,为图标设计提供科学依据。方法采用ERP技术,以扁平化和拟物化图标为靶刺激,选取青年群体为被试,进行诱发事件相关电位实验,记录实验数据。结论扁平化图标和拟物化图标刺激下的平均反应时间分别为396.18 ms和405.29 ms,被试对于扁平化图标的反应速度更快,对于两种图标的反应正确率没有显著性差异;扁平化图标诱发的P300成分的潜伏期短于拟物化图标,幅值大于拟物化图标。在图标保持相同像素,颜色相近的前提下,被试产生不同的反应速度与脑电特征。相对拟物化图标,扁平化简洁高效,使用者会投入更多的注意力并获得较高的认知效率。     

等待时距与系统响应度对语音交互等待体验及学习效果的影响

目的 本研究模拟用户向教育人工智能提问英文单词释义的情境,以词汇学习为主要任务,探究语音交互系统的系统反应时间以及系统响应度对词汇学习效果以及主观体验的影响.方法 采取2(等待时距:500 ms、2450 ms)×2(系统响应度:有提示音、无提示音)被试内设计.结果 最佳等待时距下的主观体验及学习效果优于较慢等待时距,...     

Psychophysical estimation of speed discrimination. II. Aging effects

We studied the effects of aging on a speed discrimination task using a pair of first-order drifting luminance gratings. Two reference speeds of 2 and 8 deg/s were presented at stimulus durations of 500 ms and 1000 ms. The choice of stimulus parameters, etc., was determined in preliminary experiments and described in Part I. Thresholds were estimated using a two-alternative-forced-choice staircase methodology. Data were collected from 16 younger subjects (mean age 24 years) and 17 older subjects (mean age 71 years). Results showed that thresholds for speed discrimination were higher for the older age group. This was especially true at stimulus duration of 500 ms for both slower and faster speeds. This could be attributed to differences in temporal integration of speed with age. Visual acuity and contrast sensitivity were not statistically observed to mediate age differences in the speed discrimination thresholds. Gender differences were observed in the older age group, with older women having higher thresholds.     

Variations in BOLD response latency estimated from event‐related fMRI at 3T: Comparisons between gradient‐echo and Spin‐echo

Functional magnetic resonance imaging (fMRI) commonly uses gradient‐recalled echo (GRE) signals to detect regional hemodynamic variations originating from neural activities. While the spatial localization of activation shows promising applications, indexing temporal response remains a poor mechanism for detecting the timing of neural activity. Particularly, the hemodynamic response may fail to resolve sub‐second temporal differences between brain regions because of its signal origin or noise in data, or both. This study aimed at evaluating the performance of latency estimation using different fMRI techniques, with two event‐related experiments at 3T. Experiment I evaluated latency variations within the visual cortex and their relationship with contrast‐to‐noise ratios (CNRs) for GRE, spin echo (SE), and diffusion‐weighted SE (DWSE). Experiment II used delayed visual stimuli between two hemifields (delay time = 0, 250, and 500 ms, respectively) to assess the temporal resolving power of three protocols: GRE_TR1000, GRE_TR500, and SE_TR1000. The results of experiment I showed the earliest latency with DWSE, followed by SE, and then GRE. Latency variations decreased as CNR increased. However, similar variations were found between GRE and SE, when the latter had lower CNR. In experiment II, measured stimulus delays from all conditions were significantly correlated with preset stimulus delays. Inter‐subject variation in the measured delay was found to be greatest with GRE_TR1000, followed by GRE_TR500, and the least with SE_TR1000. Conclusively, blood oxygenation level‐dependent responses obtained from GRE exhibit greater CNR but no compromised latency variations in the visual cortex. SE is potentially capable of improving the performance of latency estimation, especially for group analysis. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 215–221, 2013     

水下液电强声技术的研究进展与展望

主要从强声技术的应用需求出发,阐述了水下液电强声的产生机理、物理特性和传播特性,介绍了水下强声能领域的研究进展,总结了水下强声能武器发展中的关键和瓶颈问题,最后给出了水下强声技术的发展展望。     

Mental workload when driving in a simulator: Effects of age and driving complexity

Driving errors for older drivers may result from a higher momentary mental workload resulting from complex driving situations, such as intersections. The present study examined if the mental workload of young and older active drivers vary with the difficulty of the driving context. We adopted the probe reaction time (RT) technique to measure the workload while driving in a simulator. The technique provided clear instructions about the primary (driving) and secondary (RT) tasks. To avoid structural interference, the secondary task consisted of responding as rapidly as possible with a vocal response (“top”) to an auditory stimulus. Participants drove through a continuous 26.4-km scenario including rural and urban sections and probes (stimuli) were given in a baseline static condition and in three different driving contexts embedded into the overall driving scenario. Specifically, stimuli were given randomly when (a) driving on straight roads at a constant speed, (b) approaching intersections for which the driver had to stop the car, and (c) when overtaking a slower vehicle. Unless a driving error was made, drivers did not need any emergency responses. Reaction time was defined as the temporal interval between the auditory stimulus and the onset of the corresponding verbal response detected from the analog signal of a piezo-electric microphone fixed on a headset (ms accuracy). Baseline RTs were similar for both groups. Both groups showed longer RTs when driving and RTs increased as the complexity of the driving contexts increased (driving straights, intersections, overtaking maneuvers). Compared to younger drivers, however, older drivers showed longer RTs for all driving contexts and the most complex driving context (overtaking maneuvers) yielded a disproportionate increase. In conclusion, driving leads to a greater mental workload for the older drivers than for the younger drivers and this effect was exacerbated by the more complex driving context (overtaking maneuvers).     

A study on the validity of a task complexity measure for emergency operating procedures of nuclear power plants—Comparing task complexity scores with two sets of operator response time data obtained under a simulated SGTR

The appropriateness of the task complexity (TACOM) measure that can quantify the complexity of procedural tasks was validated in this study. To this end, two sets of task performance time data that have been extracted under the simulated steam generator tube rupture (SGTR) conditions of the reference nuclear power plant (NPP) A and B were compared with the associated TACOM scores. As a result, it was observed that two sets of task performance time data seem to be soundly explained by the associated TACOM scores. Although more additional activities should be conducted to clarify the appropriateness of the TACOM measure, the result of this study provides a crucial clue supporting that the complexity of emergency tasks stipulated in emergency operating procedures (EOPs) can be properly quantified by the TACOM measure.