A Comparison of the mismatch negativity and a differential waveform response

A mismatch negativity response (MMN) and a new differential waveform were derived in an effort to evaluate a neural refractory or recovery effect in adult listeners. The MMN was elicited using oddball test runs in which the standard and deviant stimuli differed in frequency. To derive the differential waveform, the same standard and deviant stimuli were presented alone. MMN responses were obtained by subtracting the averaged responses to standards from the deviants. The differential waveforms were obtained by subtracting the averaged responses to standards presented alone from deviants presented alone. Scalp topography for the MMN and differential waveforms were similar. A significant (p<.05) positive and negative correlation was found between the earlier and later components of the bimodal MMN and the N1 and P2 component of the differential waveform, respectively. Further, N1 and P2 of the differential waveform were significant (p<.05) predictor variables of early and late peak amplitudes of the MMN. These results suggest that refractory effects may overlay/modify the morphology of the MMN waveform.

Sumario

Se obtuvo una respuesta de negatividad desigual (MMN) y una nueva onda “diferencial” en un esfuerzo por evaluar un efecto neural refractario o de recuperación en sujetos adultos. La MMN fue generada utilizando cursos peculiares de prueba en los que el estimulo estándar y el alterado tenían frecuencias diferentes. Para derivar la onda diferencial, se presentaron el mismo estímulo estándar y el alterado en forma aislada. Las respuestas MMN se obtuvieron restando las respuestas promediadas estándar de las alteradas. Las formas de onda diferenciales se obtuvieron restando las respuestas promediadas a estímulos estándar presentados aisladamente, de los estímulos alterados presentados también en forma aislada. La topografía craneana de los MMN y las onda diferenciales fueron similares. Se encontraron correlaciones positivas y negativas significativas (p<.05) entre los componentes tempranos y tardíos de la MMN bi-modal y de los componentes N1 y P2 de la onda diferencial, respectivamente. Más aún, los componentes N1 y P2 de la onda diferencial fueron variables de predicción significativas (p<.05) de los picos tempranos y tardíos de amplitud de las MMN. Estos resultados sugieren que los efectos refractarios pueden cubrir/modificar la morfología de las onda de la MMN.     

Statistical detection and analysis of mismatch negativity derived by a multi-deviant design from normal hearing children

To shorten the time of measurement of mismatch negativity (MMN) and to objectify the analysis of MMN characteristics, auditory evoked potentials (AEP) were recorded and MMNs were statistically examined. AEPs from 16 healthy children between the ages of 5 and 7 were elicited using a multi-deviant design including: frequency, duration, intensity, and gap. For detection of MMN an automatic method was applied based on statistical analysis (t-tests) of AEP sweeps. The incidences found were compared to the incidences of MMNs detected by visual inspection of difference waveforms. MMN features such as peak amplitude, peak latency, onset latency, duration of MMN, and area under the curve were evaluated for MMN intervals identified by statistical analysis. MMN incidences identified by statistical analysis (44) reflected a consistency of 84% to visually identified (52) incidences of MMN. Scalp distribution of MMN was mainly fronto-central. Peak latencies of the duration MMN differed significantly from those of the other deviant MMNs. The multi-deviant paradigm was successfully applied for measuring children’s AEPs. The statistical approach proved applicable for analysing the data objectively.     

不同频率与强度差值对正常人错配负反应的影响

目的 研究频率与强度的声学差异对正常人错配负反应(mismatch negativity,MMN)的影响.着重观察频率与强度的差异对正常人MMN潜伏期及幅度的影响以及可以引出MMN的声学差异的阈值.方法 24例受试者纯音听力测试各个频率纯音听阈均在20 dB HL以内.应用美国智听公司Smart EP听觉诱发电位仪测量MMN,观察频率与强度的差异对正常人MMN潜伏期及幅度的变化规律.结果 随着频率差异或强度差异的减小,MMN潜伏期逐渐延长,MMN振幅逐渐降低.结论 MMN图形稳定,是听觉分辨的客观神经生理检查的重要指标.     

健康青年人失匹配负波的提取及刺激偏差对波形的影响

目的 研究失匹配负波(mismatch negativity,MMN)波形提取的相关因素及刺激偏差对波形的影响,获得一套实验室标准值.方法 以oddBall序列给予21名健康青年志愿者短纯音刺激,分为频率偏差刺激和强度偏差刺激两组,每组中又包含3个刺激系列,共6个小组.用偏差刺激引出的事件相关电位(event-related potential,ERP)减去标准刺激引出的ERP即得到MMN波形.记录各组潜伏期与波幅并两两比较,分析听刺激偏差程度对MMN的影响.结果 本实验诱发出了健康青年人的MMN波形,并获得了潜伏期与波幅的正常值.频率偏差组中,频率差异为2 kHz时的MMN潜伏期[(155.81±29.08)ms]与频率差异为1 kHz时[(182.89±45.85)ms,(183.32±43.33)ms]相比,明显缩短(P值均<0.05);差异程度相同时,改变标准刺激与偏差刺激频率的绝对值,MMN潜伏期没有明显变化;各小组间MMN的波幅[(3.85±2.22)、(2.90±2.05)、(2.66±2.12)μV]差异无统计学意义(P值均>0.05).强度偏差组中,强度差异为加dB时MMN潜伏期[(157.04±34.87)ms]与强度差异为10 dB时[(184.46±38.05)ms,(186.24±42.36)ms]相比,明显缩短(P值均<0.05);差异程度相同时,改变标准刺激与偏差刺激强度的绝对值,MMN潜伏期没有明显变化;其中只有组4和组6的MMN波幅[(3.41±1.64)μV,(2.37±1.47)μV]差异有统计学意义(P<0.05),其余各组的波幅差异均无统计学意义.结论 MMN只与刺激差异程度有关,与受试者的注意无关,属于认知功能的产物,能够客观地反映大脑探测刺激特征变化的能力.     

Automatic and controlled processing of acoustic and phonetic contrasts

Changes in the temporal properties of the speech signal provide important cues for phoneme identification. An impairment or inability to detect such changes may adversely affect one’s ability to understand spoken speech. The difference in meaning between the Finnish words tuli (fire) and tuuli (wind), for example, lies in the difference between the duration of the vowel /u/. Detecting changes in the temporal properties of the speech signal, therefore, is critical for distinguishing between phonemes and identifying words. In the current study, we tested whether detection of changes in speech sounds, in native Finnish speakers, would vary as a function of the position within the word that the informational changes occurred (beginning, middle, or end) by evaluating how length contrasts in segments of three-syllable Finnish pseudo-words and their acoustic correlates were discriminated. We recorded a combination of cortical components of event-related brain potentials (MMN, N2b, P3b) along with behavioral measures of the perception of the same sounds. It was found that speech sounds were not processed differently than non-speech sounds in the early stages of auditory processing indexed by MMN. Differences occurred only in later stages associated with controlled processes. The effects of position and attention on speech and non-speech stimuli are discussed.     

前庭刺激对人脑事件相关电位的影响

目的本研究采用事件相关电位(ERPs)技术探讨前庭刺激对人脑加工功能的影响。方法选取15名健康男子进行实验。实验中受试者坐于转椅上,在下述条件下完成视觉操作任务:(1)实验测试,(2)对照测试,同时记录原始脑电资料。结果前庭刺激后,结果显示CPZ和PZ位置得到的差异波振幅均可见有显著性的改变,在前庭刺激后均明显减小。结论前庭刺激对人体的其他功能产生了明显影响,受试者在对视觉信号的感知时,特别是对需要选择的信号,明显产生了抑制现象。     

Effects of musical training on sound pattern processing in high-school students

Objective

Recognizing melody in music involves detection of both the pitch intervals and the silence between sequentially presented sounds. This study tested the hypothesis that active musical training in adolescents facilitates the ability to passively detect sequential sound patterns compared to musically non-trained age-matched peers.

Methods

Twenty adolescents, aged 15-18 years, were divided into groups according to their musical training and current experience. A fixed order tone pattern was presented at various stimulus rates while electroencephalogram was recorded. The influence of musical training on passive auditory processing of the sound patterns was assessed using components of event-related brain potentials (ERPs).

Results

The mismatch negativity (MMN) ERP component was elicited in different stimulus onset asynchrony (SOA) conditions in non-musicians than musicians, indicating that musically active adolescents were able to detect sound patterns across longer time intervals than age-matched peers.

Conclusions

Musical training facilitates detection of auditory patterns, allowing the ability to automatically recognize sequential sound patterns over longer time periods than non-musical counterparts.     

多巴胺对豚鼠听觉传入神经的抑制作用及其频率选择性

目的 观察多巴胺对听觉传入神经的抑制作用及其频率选择性,为进一步探讨多巴胺在内毛细胞下突触复合体中的调控作用奠定基础.方法 健康杂色豚鼠40只,随机分为4组,行全耳蜗灌流:①灌流人工外淋巴液组;②灌流10 mmol/L多巴胺组;③灌流30 mmol/L多巴胺组;④灌流50 mmol/L多巴胺组.灌流过程中分别在第0 h、1 h和2 h通过蜗窗记录不同频率刺激声(250、500、1000、2000、4000、8000及16 000 Hz)所引出的复合动作电位(CAP)阈值和4000 Hz刺激声所引出的耳蜗微音器电位(CM)的幅值.结果 灌流人工外淋巴液前后各频率CAP阈值差异均没有统计学意义(P值均>0.05);灌流多巴胺后大部分频率的CAP阈值提高,与灌流前相比差异具有统计学意义(P值均<0.05),而且随着多巴胺浓度的增加,其抑制作用也逐渐增强;灌流后各组内不同刺激声频率间的CAP阈移存在差异,灌流30 mmol/L多巴胺时最明显,该组中4000 Hz和8000 Hz处阈移最大.灌流人工外淋巴液和多巴胺对CM的非线性没有明显影响,灌流前后CM的相对幅值差异没有统计学意义(P值均>0.05).结论 多巴胺对豚鼠听觉传入神经具有抑制性作用,而对外毛细胞无影响;这种抑制作用具有频率选择性,对高频纤维的抑制作用较强,而对低频的抑制作用较弱.     

电极位置和滤波对婴幼儿短纯音诱发听性脑干反应阈值的影响

目的比较婴幼儿记录电极置于颅顶、滤波为30-1500Hz(简称第一组测试参数)与记录电极置于前额发际、滤波为30-3000Hz(简称第二组测试参数)各频率短纯音听性脑干反应(Auditory Brain Stem Re-sponse,ABR)阈值之间的差别,总结两种记录参数下短纯音ABR(tone burst ABR,tb-ABR)波形特点对阈值判断的影响,选择更优化的tb-ABR测试条件。方法应用SmartEP听觉诱发电位仪(美国IHS公司)记录0-6月龄婴幼儿短声及上述两种记录参数下tb-ABR各频率反应阈,共12例(10男/2女)20耳。结果 0.5kHz、1kHz、2kHz、4kHz记录电极置于前额发际、滤波为30-3000Hz时tb-ABR反应阈比记录电极置于颅顶、滤波为30-1500Hz时tb-ABR反应阈分别高7.00±5.5、7.25±6.0、7.25±4.7、8.00±5.5dB。各频率两种记录参数下tb-ABR反应阈之间差异均有统计学意义(t值分别为5.715、5.445、6.866、6.532,P值均<0.01)。同等强度时,两种记录参数下tb-ABR各波振幅差别明显,第一组测试参数下tb-ABR各波振幅高于第二组测试参数下tb-ABR各波振幅,前者的反应曲线较后者平滑,波V更容易辨认。结论用短纯音诱发ABR评估婴幼儿听力时,记录电极置于颅顶、滤波为30-1500Hz时各频率测试时反应阈和波形均优于记录电极置于前额发际、滤波为30-3000Hz,可提供更好的阈值测试结果。     

纯音和言语刺激声强度对听觉事件相关电位的影响

目的:探讨分别以纯音和言语作刺激声时声强度对听觉事件相关电位(AERP)的影响.方法:采用不同强度的纯音和言语作为刺激声对正常年青人进行AERP测试,比较纯音和言语诱出典型P300的强度范围,分析不同强度对P300的影响是否同时存在于纯音和言语刺激声.结果:言语刺激声比纯音更容易在40～70 dBSL范围内连续记录到典型波形,差异有统计学意义(P＜0.01).言语或纯音刺激时,强度对P300潜伏期的影响差异均有统计学意义(P＜0.01),在40～70 dBSL范围内潜伏期随强度增加而减小,强度对P300幅值的影响差异均无统计学意义.结论:强度对AERP的影响在纯音和言语刺激时基本相同,但言语得到典型AERP波形的强度范围较纯音宽,其原因可能与言语刺激声包含的信息较纯音刺激声丰富,受试者对汉语言语刺激声较纯音更熟悉有关.     

铅中毒对学龄儿童听性脑干反应的影响

目的 观察铅中毒对学龄儿童听觉神经系统的损害。方法 对100例无神经系统阳性体征的铅中毒儿童进行听性脑干反应、纯音测听及畸变产物耳声发射检测，并将其分为补钙组和未补钙组，观察治疗前后的听性脑干反应、纯音测听及畸变产物耳声发射的变化，同时与50例年龄性别相匹配的血铅正常儿童进行对比分析。结果 治疗前铅中毒组和正常组听性脑干反应比较：铅中毒组Ⅴ波潜伏期较正常组延长，差异有统计学意义（t=3．21，P〈0．01），Ⅰ、Ⅲ波潜伏期较正常组延长，但差异无统计学意义（前者t=2．06，P〉0．05，后者t=1．64，P〉0．05）。铅中毒组Ⅲ～Ⅴ、Ⅰ～Ⅴ波间期较对照组延长，差异有统计学意义（前者t=7．30，P〈0．01，后者t=3．14，P〈0．01），Ⅰ～Ⅲ波间期较对照组延长，但差异无统计学意义（t=0．91，P〉0．05）。铅中毒组Ⅰ、Ⅲ、Ⅴ波波幅均低于正常组，差异有统计学意义（Ⅰ波-t=3．20，P〈0．01，Ⅲ波：t=3．31，P〈0．01，Ⅴ波：t=3．41，P〈0．01）。补钙组、未补钙组及血铅正常组治疗半年前后比较：3组听性脑干反应各指标在治疗前后均无统计学意义（P〉0．05）。纯音测听及畸变产物耳声发射检测前后差异均无统计学意义（P值均〉0．05）。结论 铅中毒可以引起神经系统的亚临床损害，补钙对治疗后ABR无显著改变，ABR对于早期发现铅中毒对神经系统损害有一定的价值。     

谷氨酸对豚鼠畸变产物耳声发射和听性脑干反应的影响

目的 研究外源性谷氨酸对畸变产物耳声发射(distortion product otoacoustlcemission，DPOAE)、听性脑干反应(auditory brainstem response，ABR)及耳蜗形态学的影响。方法应用豚鼠全耳蜗灌流技术，耳蜗灌流10mmol/L谷氨酸2h，分别记录灌流前、后DPOAE和ABR；耳蜗微音电位(cochlear microphonics，CM)和听神经复合动作电位(compound action potential，CAP)；应用透射电镜进行耳蜗形态学观察。结果灌流人工外淋巴液前、后CM及CAP无改变；灌流10mmol／L谷氨酸后DPOAE无改变，ABR潜伏期延长；同样灌流10mmol／L谷氨酸后CM幅度虽有下降、但是其非线性特点无改变；CAP阈值平均升高了35dB；灌流谷氨酸后内毛细胞及其下方神经纤维出现空泡。结论谷氨酸作为耳蜗主要的兴奋性传入神经递质，过度释放可以产生兴奋性毒性，损伤耳蜗内毛细胞及传入神经。同时本实验为建立听神经病的动物模型提供了一个参考方法。     

水杨酸钠对幼年和成年豚鼠听性脑干反应阈值及螺旋神经节谷氨酸脱羧酶表达的影响

目的 观察水杨酸钠对幼年和成年豚鼠听性脑干反应(ABR)阈值以及螺旋神经节谷氨酸脱羧酶(glutamic acid decarboxylase,GAD)表达的影响.方法 选择出生4 d的豚鼠40只和出生后1个月的成年豚鼠40只,分成4组(每组20只):幼年对照组,成年对照组,幼年水杨酸钠给药组[300 mg/(kg·d)],成年水杨酸钠给药组[300 mg/(kg·d)].给药15 d后每组随机选取10只豚鼠检测ABR阈值,采用免疫组织化学染色方法检测螺旋神经节GAD的表达.各组剩下的动物停止给药,继续喂养30 d后检测ABR阈值和螺旋神经节GAD的表达.结果 给药15 d后幼年水杨酸钠给药组和成年水杨酸钠给药组豚鼠ABR阈值较给药前以及同期对照组均有提高(P值均<0.001),停药30 d后幼年水杨酸钠给药组ABR阈值恢复到给药前水平,而成年水杨酸钠给药组仍停留在高阈值水平;水杨酸钠给药15 d后能明显下调幼年以及成年豚鼠螺旋神经节GAD蛋白表达,幼年豚鼠GAD表达水平低于成年豚鼠(t=4.7,P<0.001),停药30 d后幼年给药组螺旋神经节GAD表达恢复到同期对照组水平,而成年给药组则继续停留在低表达水平.结论 水杨酸钠在对幼年和成年豚鼠ABR阚值以及螺旋神经节GAD表达的影响上存在差异,其对幼年豚鼠的影响更为明显,但停药后幼年豚鼠较成年豚鼠更容易恢复到正常水平.     

西地那非对豚鼠噪声性听觉损伤阈移的影响

目的 探讨西地那非(sildenafil)对豚鼠噪声性听觉损伤阈移的影响.方法 将豚鼠按随机数字表法分为对照组、噪声暴露组和西地那非给药组,每组10只.西地那非组及噪声组豚鼠在白噪声(A计权声压级110 dB)暴露1周后分别腹腔注射西地那非10 mg/(kg·d)及生理盐水4mL/(kg·d),连续给药4周.分别测试噪声暴露前1日、噪声暴露后1、2及4周听性脑干反应(ABR)阈值,并通过扫描电镜观察噪声暴露后4周豚鼠耳蜗毛细胞的形态变化.结果 噪声暴露1后,噪声暴露组豚鼠ABR阈值(声压级)平均提高19.1 dB,随着时间推移,阈移逐渐加大,暴露后4周,阈值平均提高22.0 dB;西地那非组噪声暴露后ABR阈值提高19.8 dB,给药后阈移逐渐减小,给药后4周,阈值仅平均提高4.8 dB.西地那非组与噪声暴露组相比,除噪声暴露结束后这一时间点以外,其余给药后各时间点ABR阈值差异均具有统计学意义(P值均＜0.05).扫描电镜显示,噪声组豚鼠耳蜗内、外毛细胞均出现听毛紊乱、融合及缺失;而西地那非组耳蜗病变较轻,听毛仅有轻微倒伏、融合现象.结论 西地那非能够减轻噪声对豚鼠耳蜗毛细胞的损害,降低噪声性听觉损伤引起的ABR阈值升高.     

用MP3播放器通过耳机播放音乐对豚鼠听觉系统的影响

目的研究用MP3播放器通过耳机播放音乐对豚鼠的听性脑干反应(auditory brainstem response,ABR)阈值及耳蜗形态学的影响,探讨其对听觉系统的损伤作用。方法实验动物分为对照组及实验组,每组动物12只。对照组不给予音乐暴露,其他条件与实验组相同。实验组每天用MP3播放器播放流行音乐5 h,连续14 d。观察对照组、实验组ABR反应阈及耳蜗形态学的变化。结果实验组动物在音乐暴露过程中及暴露后数天均呈现明显ABR反应阈上移,而对照组ABR反应阈无明显变化,两组间差异有统计学意义;基底膜铺片示实验组耳蜗各转外毛细胞均有不同程度的缺失,以耳蜗底转近钩端最为严重,3排外毛细胞以第二、三排损伤较重。结论用MP3播放器通过耳机播放音乐能引起豚鼠听觉系统的损害,表现为ABR反应阈升高及耳蜗外毛细胞形态的改变。