上肢辅助站立状态下姿态扰动诱发的脑电响应特征

探究上肢辅助站立状态下姿态扰动诱发的脑电响应特征,从而为下肢运动功能障碍患者失稳态的识别提供新的思路和方法。设计实验装置使人体随机侧的上肢支撑力发生快速变化,从而模拟人体在上肢辅助站立状态下的姿态扰动。实验同步采集20名被试64通道脑电、双侧支撑力和双侧前臂腕伸肌的表面肌电信号,分析姿态扰动事件发生时脑电诱发电位的神经响应特征,以及力学信号和表面肌电的行为学响应特征。在姿态扰动施加后,姿态扰动侧的支撑力在(200.5±15.4)ms的时间内快速减小。与此同时,双侧前臂腕伸肌的表面肌电值均增大,并且姿态扰动侧的表面肌电值更大。姿态扰动施加后诱发出了N1电位,其在FCz导联处幅值最大,其潜伏期为(62.3±5.5) ms,幅值为(15.6±6.1) μV;P2电位的潜伏期为(167.4±12.4) ms,幅值为(5.2±4.5) μV。该研究为通过神经响应过程识别人体的失稳态提供可行性。     

精神分裂症患者失匹性负波(MMN)研究

目的:了解首发精神分裂症患者失匹性负波(MMN)的特征以及治疗缓解后MMN的变化。方法:应用美国Bravo脑电生理仪,记录45例首发精神分裂症患者和40名健康人的MMN,同时记录P300电位比较,并用阳性和阴性症状量表(PANSS)评定患者精神症状。患者组于治疗5周和12周时进行MMN随访。结果:(1)与正常组比较,首发精神分裂症组的MMN潜伏期延迟和波幅降低(正常组199·7±29·9ms和7·8±3·8μV,患者组221·4±32·6ms,4·5±3·3μV,P均<0·01),患者组P300中靶潜伏期P3同时延迟(P<0·01)。(2)MMN潜伏期延长和波幅低,与PANSS阳性症状和思维障碍分呈负相关(P<0·05~0·01)。(3)患者组经治疗12周后,MMN波幅呈增大改变和潜伏期缩短(P<0·01),反映患者的认知功能改善。结论:MMN技术可反映首发精神分裂症患者诱发脑电的自动加工过程。MMN可作为精神分裂症患者的临床应用检测指标。     

首发与复发精神分裂症患者失配性负波MMN的对比研究

目的:探讨首发与复发精神分裂症患者前注意信息加工的电生理机制差异。方法:采用纯音"Oddball"诱发模式,对36例首发精神分裂症患者(首发组)、38例复发精神分裂症患者(复发组)进行事件相关电位MMN检查,测量MMN的潜伏期、波幅,并与33名健康被试的结果进行比较。结果:与对照组相比,首发组的MMN潜伏期差异不显著(t=1.06,P0.05),复发组的MMN潜伏期显著延迟(t=4.23,P0.05),首发和复发组的MMN波幅均显著降低(t=2.69,3.36;P0.05);与首发组相比,复发组的MMN潜伏期显著延迟、波幅显著降低(t=3.66,3.03;P0.05)。结论:首发与复发精神分裂症患者的前注意信息自动加工电生理机制均受损,患者的反复发作能加重其受损。提示MMN受损指标可能是精神分裂症患者复发的潜在生物学标记。     

脑电近似熵、失匹配负波在检测帕金森病患者认知功能障碍中的评估作用

目的:对比帕金森病(PD)患者与对照组的脑电近似熵(ApEn)、失匹配负波(MMN)检查结果,分析两种方法在帕金森病患者认知功能障碍中的评估作用.方法:病例组15例、对照组36例受试对象均接受常规16信道脑电图检查,选用脑电非线性指数近似熵对安静闭眼、闭眼心算、安静睁眼三种状态下的原始脑电数据进行分析;并收集简易智力状态检查量表(MMSE)得分、MMN的潜伏期和波幅相关数据,运用统计学方法对两组结果进行分析.结果:①病例组与对照组MMN在Cz、Fz点的潜伏期差异虽然没有统计学意义,但从数值上可见病例组的潜伏期有延长趋势;两组在Cz、Fz点的波幅比较差异无统计学意义;②病例组与对照组脑电ApEn对比,只在闭眼心算时,两组于中央感觉运动区(C3)、顶叶(P3)、枕叶(O2)点的脑电ApEn差异有统计学意义,病例组较对照组测值降低.结论:脑电ApEn和MMN潜伏期都可作为认知功能的评价措施.并且闭眼心算状态的脑电ApEn评价效果的敏感性较MMN潜伏期强.三种状态下,闭眼心算的脑电ApEn评价效果最好.     

失配性负波在阿尔茨海默病中的应用研究

目的:探讨阿尔茨海默病(AD)患者失配性负波(MMN)的特点。方法:应用美国NicoletSpirtit脑诱发电位仪,对34例AD患者和36名正常老人的MMN作了检测。结果:AD组波形不规则,MMN-Ⅰ型(延迟型)尤甚。与正常老人组比较,AD患者MMN潜伏期延迟(P<0.05),波幅降低(P<0.01)。结论:初步认为MMN是反映AD患者认知功能的一种脑电生理检测工具。     

首发精神分裂症患者前注意加工功能与其血清同型半胱氨酸水平分析

目的:探讨首发精神分裂症患者前注意加工功能与其血清同型半胱氨酸(Hcy)水平之间的关系。方法:采用高效液相色谱法测定36例首发精神分裂症患者和38例健康对照组的空腹血清Hcy水平,采用32导事件相关电位(ERP)测试仪测定患者组和对照组失匹配负波(MMN)潜伏期和波幅值,并将患者组MMN潜伏期、波幅值与血清Hcy浓度进行相关分析。结果:患者组Fz、Cz、Pz处MMN潜伏期较对照组延长,但差异无统计学意义;患者组Fz、Cz、Pz处MMN波幅较对照组降低,血清Hcy浓度较对照组明显增高,差异有统计学意义(t=-18.763,-15.232,-7.821,9.396;P0.05);患者组MMN波幅值PzCzFz(t=6.172,3.550;P0.05),对照组MMN波幅值FzCzPz(t=3.542,3.386;P0.05),对照组脑地形图MMN波幅能量分布以前额、中央区为主,而患者组脑地形图MMN波幅能量分布以中央、顶区为主,患者组脑地形图MMN波幅能量分布较对照组主效应后移。相关分析得出Fz、Cz、Pz处MMN平均潜伏期与血清Hcy水平呈正相关(t=0.423,P0.05),Fz、Cz、Pz处MMN平均波幅与血清Hcy水平呈负相关(t=-0.547,P0.05)。结论:首发精神分裂症患者存在前注意自动加工功能损害,且与其血清Hcy水平升高存在一定的相关性。     

老年抑郁症和阿尔茨海默病的事件相关电位失匹配负波(MMN)的对照研究

目的:探讨老年抑郁症(GD)和阿尔茨海默病(AD)的事件相关电位失匹配负波(mismatch negativity,MMN)变异。方法:应用美国Nicolet Bravo脑诱发电位仪,记录了35例GD患者的MMN,并与40例AD患者和39例健康老人(NC)的MMN进行比较。结果:MMN潜伏期3组差异有统计学意义(F=18.642,P0.01),AD组与GD组潜伏期均延长(P=0.000,0.006),AD组较GD组潜伏期延长(P=0.037);MMN波幅3组差异有统计学意义(F=13.491,P0.01),AD组较NC组、GD波幅降低(P=0.000,0.009)。结论:老年抑郁症和阿尔茨海默病患者MMN存在异常,MMN对GD与AD的鉴别诊断有一定的参考价值。     

阿尔茨海默病患者的前注意自动信息加工

目的探讨阿尔茨海默病患者(AD)的失配性负波(MMN)特征及其前注意加工电生理机制。方法对22例阿尔茨海默病患者(AD组)进行事件相关电位MMN检查,并与25名健康志愿者(对照组)的结果进行比较。结果 1与对照组相比,AD组情节记忆、执行功能、注意转换测试分均显著降低(t=14.30,6.81,7.20,5.11,P0.05);2AD组潜伏期差异不显著(t=1.26,P0.05),波幅显著降低(t=5.03,P0.05);3线性回归显示,AD患者降低的MMN波幅与注意转换分呈显著正相关(r=0.63,P0.05)。结论 AD患者多领域认知功能受损,前注意自动信息加工机制异常,提示电生理MMN异常指标可能预测AD患者的神经病理机制的进程。     

汉语双字词启动任务的事件相关电位时空模式

目的:考察汉语双字词启动任务的事件相关电位(ERP)时空模式特性。方法:以词汇重复(例:大豆-大豆)、语义启动(例:高粱-大豆)和语义失配(例:轮船-大豆)三类关系先后显示启动词和靶词,16名被试判断靶词是否与启动词同类而分别按键,同时记录其行为绩效和19通道ERP,应用单因素三水平重复测量方差分析和配对比较,采用统计参数映像(statistical parametric mapping,SPM)呈现ERP结果。结果:反应时间(F(2,26)=77.28,P=0.00)和正确率(F(2,26)=42.91,P=0.00)的重复启动效应均显著,词汇重复组的行为绩效(反应时间601.44±69.39ms,正确率98.7±1.3%)分别优于语义启动组(774.98±87.34ms,88.2±5.9%)和语义失配组(788.75±88.10ms,87.8±4.8%)。虽然后两组行为绩效差异不显著,但其ERP均可见P200、N400和P600成分。SPM提示额顶颞分布的P200效应(200-250ms)与注意调控相关;中央顶分布的N400效应(300-450ms)与语义加工相关;枕颞分布的P600效应(500-1000ms)可能反映语境重构。结论:双字词启动任务的ERP时空模式反映多层次语言加工功能,适用于语言功能评价。     

重复经颅磁刺激治疗对抑郁症患者时间知觉的作用效应

目的:探讨左背外侧前额叶高频重复经颅磁刺激(rTMS)治疗对抑郁症患者时间知觉的影响。方法:接受固定剂量帕罗西汀治疗(40mg/d)的抑郁症患者随机分组,在药物治疗的同时,研究组(n=30)合并左背外侧前额叶高频rTMS治疗,对照组(n=32)予伪刺激,为期4周。于治疗前、治疗后4周,进行汉密尔顿抑郁量表(HAMD)评定;完成600ms、3s时距复制任务,以时距复制误差作为时间知觉的评估指标。结果:1治疗后,研究组、对照组患者HAMD评分均显著下降(分别t=12.047,9.275;P均0.01),差异有统计学意义;研究组600ms、3s时距复制误差较治疗前下降(分别t=3.342,6.389;P0.01),差异有统计学意义;对照组3s时距复制误差较治疗前下降(t=2.978,P=0.008),差异有统计学意义,而600ms时距复制误差较治疗前无显著变化(P0.05);2治疗后,研究组HAMD评分的下降值高于对照组(t=4.062,P=0.000),差异有统计学意义;600ms、3s时距复制误差的下降值也均高于对照组(分别t=2.240,2.096;P0.05,0.041),差异有统计学意义;3研究组、对照组治疗前后3s时距复制误差的下降值,与HAMD评分的下降值正相关(分别r=0.330,0.391;P0.05)。研究组、对照组治疗前后600ms时距复制误差的下降值,则与HAMD评分的下降值均无显著相关性(P均0.05)。结论:左背外侧前额叶高频rTMS治疗可影响抑郁症患者的时间知觉,并可能存在继发于改善抑郁之外的其他作用机制。     

Hearing the speed: visual motion biases the perception of auditory tempo

The coupling between sensory and motor processes has been established in various scenarios: for example, the perception of auditory rhythm entails an audiomotor representation of the sounds. Similarly, visual action patterns can also be represented via a visuomotor transformation. In this study, we tested the hypothesis that the visual motor information, such as embedded in a coherent motion flow, can interact with the perception of a motor-related aspect in auditory rhythm: the tempo. In the first two experiments, we employed an auditory tempo judgment task where participants listened to a standard auditory sequence while concurrently watching visual stimuli of different motion information, after which they judged the tempo of a comparison sequence related to the standard. In Experiment 1, we found that the same auditory tempo was perceived as faster when it was accompanied by accelerating visual motion than by non-motion luminance change. In Experiment 2, we compared the perceived auditory tempo among three visual motion conditions, increase in speed, decrease in speed, and no speed change, and found the corresponding bias in judgment of auditory tempo: faster than it was, slower than it was, and no bias. In Experiment 3, the perceptual bias induced by the change in motion speed was consistently reflected in the tempo reproduction task. Taken together, these results indicate that between a visual spatiotemporal and an auditory temporal stimulation, the embedded motor representations from each can interact across modalities, leading to a spatial-to-temporal bias. This suggests that the perceptual process in one modality can incorporate concurrent motor information from cross-modal sensory inputs to form a coherent experience.     

C臂X线机不同投射角度透视对股骨颈骨折经皮内固定后上方in-out-in螺钉的评估

目的 探讨采用C臂X线机不同投射角度透视图像评估股骨颈骨折经皮内固定模型后上方in-out-in（IOI）螺钉的精准性。方法 选取6个Synbone股骨近端人工骨标准模型,模拟股骨颈骨折经皮倒三角空心螺钉内固定手术方式向股骨颈内分别置入3枚2.5 mm的导针,其中后上方的那枚导针设计成IOI状态。使用C臂X线机,观察以下不同投射角度X线透视图像上股骨颈后上方的IOI导针穿出皮质的情况：（1）标准正侧位和轴位透视;（2）动态旋转手术床透视;（3）C臂X线机顺序旋转透视。结果 （1）6个模型的标准正侧位透视图像均显示置入的3枚导针完全位于股骨颈内,未见穿破皮质;股骨颈轴位透视均可见后上方IOI导针明显穿出皮质。（2）逆时针旋转手术床与水平面约20°时透视可发现IOI导针穿出皮质。（3）C臂X线机影像增强器顺时针旋转40°时,可清晰观察到IOI导针穿破了皮质,在股骨颈内呈现IOI状态。结论 C臂X线机正侧位透视图像在评估股骨颈骨折经皮内固定后上方的IOI螺钉时存在假象,而使用40°顺时针旋转透视的图像可清晰显示股骨颈后上方IOI螺钉。     

Rhythm perception: Speeding up or slowing down affects different subcomponents of the ERP P3 complex

The aim of this study was to investigate, by measuring the event related potential (ERP) P3 complex, whether the perception of small accelerations differs from that of small decelerations. Participants had to decide whether the last beat of a short sequence was presented 'too early' or 'too late'. Target beats were accelerated or decelerated with 0%, 2%, 5%, or 10%. Individuals differed in their capability to detect small tempo changes. We found that good responders were able to identify all tempo changes whereas poor responders were only able to identify large (10%) tempo changes. In addition, we found that tempo changes affected two subcomponents of the ERP P3 in good performers. Accelerations increased a late-P3 amplitude whereas decelerations increased an early-P3 amplitude. These results imply the principle possibility to measure differential P3 effects within one task. This is important for acquiring more refined knowledge concerning different subcomponents of the ERP P3 complex and the cognitive processes by which they are elicited.     

Musically induced arousal affects pain perception in females but not in males: a psychophysiological examination

The present study investigated affective and physiological responses to changes of tempo and mode in classical music and their effects on heat pain perception. Thirty-eight healthy non-musicians (17 female) listened to sequences of 24 music stimuli which were variations of 4 pieces of classical music. Tempo (46, 60, and 95 beats/min) and mode (major and minor) were manipulated digitally, all other musical elements were held constant. Participants rated valence, arousal, happiness and sadness of the musical stimuli as well as the intensity and the unpleasantness of heat pain stimuli which were applied during music listening. Heart rate, respiratory rate and end-tidal PCO(2) were recorded. Pain ratings were highest for the fastest tempo. Also, participants' arousal ratings, their respiratory rate and heart rate were accelerated by the fastest tempo. The modulation of pain perception by the tempo of music seems to be mediated by the listener's arousal.     

Processes involved in tempo perception: a CNV analysis

The purpose of this research was to study the mechanisms underlying tempo perception, by looking at their electrophysiological brain correlates. The subjects' task consisted of comparing the tempos of two isochronous tone sequences made up of either three (condition 13) or six (condition 16) 600-ms intervals. Contingent negative variation (CNV), known to be linked to the judgment of a single interval, kept increasing in amplitude for three intervals during tempo encoding, thereby providing evidence of the occurrence of CNVs also for several intervals in succession. This CNV increase could reflect the use of interval-based processes in the building of the interval memory trace. During the comparison phase, a CNV decrease was observed in condition 16, suggesting that subjects did not build a new memory trace, but used beat-based processes to check whether the beats of the new tempo occurred at the times they anticipated.     

Listening strategy for auditory rhythms modulates neural correlates of expectancy and cognitive processing

A recently described auditory tempo perception paradigm revealed individual differences in perceived stimulus timing for identical stimulus sequences. The current study takes advantage of this paradigm by recording event‐related potentials (ERPs) concurrent with task performance in order to reveal brain responses that reflect individual differences in timing strategy. No strategy‐related differences were observed in sensory encoding of tones, as measured by the P1‐N1‐P2 complex. However, the contingent negative variation (CNV) leading up to the final tone of the sequence varied as a function of strategy, as did a parietal‐maximum late positive component (P3b) that occurred following the final tone. These data suggest that temporal expectancy for and cognitive processing of the final tone of rhythmic sequences underlies differences in strategy during rhythm perception.     

The perception of invariant speech features in children with autism

We investigated whether the good pitch-discrimination abilities reported in individuals with autism have adverse effects on their speech perception by compromising their ability to extract invariant phonetic features from speech input. The MMN, a brain response reflecting sound-discrimination processes, was recorded from children with autism and their controls for phoneme-category and pitch changes in speech stimuli under two different conditions: (a) when all the other features of the standard and deviant stimuli were kept constant, and (b) when constant variation with respect to an irrelevant feature was introduced to the standard and deviant stimuli. Children with autism had enhanced MMNs for pitch changes in both conditions, as well as for phoneme-category changes in the constant-feature condition. However, when the phoneme-category changes occurred in phonemes having pitch variation, the MMN enhancement was abolished in autistic children. This suggests that children with autism lose their advantage in phoneme discrimination when the context of the stimuli is speech-like and requires abstracting invariant speech features from varying input.     

Categorical perception of lexical tones in Chinese revealed by mismatch negativity

The present study investigated the neurophysiological correlates of categorical perception of Chinese lexical tones in Mandarin Chinese. Relative to standard stimuli, both within- and across-category deviants elicited mismatch negativity (MMN) in bilateral frontal-central recording sites. The MMN elicited in the right sites was marginally larger than in the left sites, which reflects the role of the right hemisphere in acoustic processing. At the same time, relative to within-category deviants, the across-category deviants elicited larger MMN in the left recording sites, reflecting the long-term phonemic traces of lexical tones. These results provide strong neurophysiological evidence in support of categorical perception of lexical tones in Chinese. More important, they demonstrate that acoustic and phonological information is processed in parallel within the MMN time window for the perception of lexical tones. Finally, homologous nonspeech stimuli elicited similar MMN patterns, indicating that lexical tone knowledge influences the perception of nonspeech signals.     

Combined diffusion weighting and CSF suppression in functional MRI

In this study, EPI pulse sequences with diffusion weighting for reduction of contributions from large vessels and inversion pulses in order to minimize the effects of CSF pulsations and CSF partial volume effects were developed for BOLD contrast investigations in functional MR imaging. One inversion recovery echo-planar imaging (IR-EPI) pulse sequence and one IR-EPI with additional diffusion weighting (DW-IR-EPI) were developed and compared to a standard gradient-echo EPI sequence in a cortical stimulation experiment in nine healthy volunteers. Stimulation of motor cortex was performed using a semi-complex finger-tapping paradigm in seven periods of alternating rest and stimulation. Comparison between the three pulse sequences was made by measuring the activated volume in each subject, as well as by calculating the relative signal increase during stimulation. Due to different baseline signal-to-noise levels in the images generated by the three pulse sequences, artificial noise was added so that the comparative investigation could be performed independently of the noise level. The activated volume was 128 +/- 73 pixels (mean +/- SD) using the standard EPI pulse sequence, 31 +/- 12 pixels using IR-EPI and 15 +/- 13 pixels when DW-IR-EPI was employed. The relative signal increase was 5.7 +/- 1.1% using standard EPI, 11.5 +/- 3.1% using IR-EPI and 9.9 +/- 2.4% using DW-IR-EPI. The activated volume obtained with the addition of extra noise, i.e. at equal S/N, was 70 +/- 50 pixels using the standard EPI, and when using IR-EPI, the activated volume was 28 +/- 13 pixels. At equal S/N, the signal increase was 7.3 +/- 1.4% using standard EPI and 12.0 +/- 3.6% using IR-EPI. In BOLD contrast imaging, a combination of diffusion weighting and inversion recovery appeared to reduce false activation caused by CSF pulsation and blood flow in large vessels.