脑干对谐波复合音反应中的基频成分与早期听觉信息处理

研究了以２００Ｈｚ为基频的谐波复合音诱发的持续性脑干听觉诱发电位。分析了刺激信号中各种参数的改变对诱发电位的影响。发现：１．不含基频的谐波复合音,其诱发反应频谱上除出现与刺激组分相对应的频率成分外,还出现基频成分及其它谐波成分。２．由高次谐波组成的三组分谐波复合音诱发的反应对各刺激组分相位结构有较大敏感性,而低次谐波组成的三组分谐波复合音诱发的反应对相位结构的敏感性较差。３．对双组分谐波复合音,无论其间差频等于基频或基频的两倍,其诱发反应频谱中均出现基频成分。     

听觉信息的编码

听觉系统能感受的声音干变万化,其参数变异范围极大,如频率上下限可相差1000倍,强度按能量计算上下限可相差10000倍。那么听觉系统是如何对如此巨量的听觉信息进行编码的呢？我们知道,声波经过耳蜗毛细胞的换能作用转变为神经冲动,成为传递声音的信息。但神经冲动是以全或无形式传布的,单纤维的神经冲动其振幅和与波形都是相对固定的,因此神经冲动的振幅波形不能反映声音的特性,只能依据神经冲动的节律、冲动的时间间隔以及发放神经冲动的纤维在耳蜗基底膜上的起源部位来传递不同形式的声音信息。我们把神经冲动在听神经纤维上传输…     

鸟类脑干听觉诱发电位的观察

采用短声刺激鸟类听觉感受器的方法,对15只健康成年虎皮鹦鹉的脑干听觉诱发电位进行了实验观察。结果发现,鸟类头顶均能记录到与听觉有关的脑干听觉诱发电位Ⅰ波、Ⅱ波、Ⅲ波、Ⅳ波和Ⅴ波。为鸟类语言发声研究的听力学评价提供一个简便可行的方法。     

橄榄桥脑小脑萎缩患者的脑干听觉诱发电位及其与桥脑体积的相关性

目的:观察橄榄桥脑小脑萎缩(OPCA)脑干听觉诱发电位各波、波间潜伏期的变化,并分析这些变化与桥脑体积/后颅窝体积比值(PV/PFV)的相关性。方法:利用丹麦KeypointEMG/EP电生理仪测定OPCA组、对照组脑干听觉诱发电位Ⅰ、Ⅲ、Ⅴ波潜伏期(PL),Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ峰间潜伏期(IPL)并采用1.5TMR3DVolumeRender-ing软件行桥脑体积(PV)、小脑体积(CV)、后颅窝体积(PFV)磁共振测量,算出PV/PFV、CV/PFV、PV/CV值。结果:与对照组相比,OPCA组Ⅲ波PL、Ⅰ-ⅢIPL明显延长(P<0.05),Ⅲ-ⅤIPL明显缩短(P<0.05);OPCA组PV/PFV值明显减少(P<0.01);Ⅲ-ⅤIPL与PV/PFV呈正相关(r=0.83,P<0.01)。结论:OPCA患者脑干听觉诱发电位Ⅲ波PL、Ⅰ-ⅢIPL延长,Ⅲ-ⅤIPL缩短,Ⅲ-ⅤIPL随着桥脑体积的变小而缩短。     

刺激强度,刺激音持续时间与脑干听觉诱发电位慢成分的关系

刺激强度、刺激音持续时间与脑干听觉诱发电位慢成分的关系郑辉,李善民（暨南大学医学院听觉生理学研究室广州５１０６３２）脑干听觉诱发电位（ＢＡＥＰ）是听觉诱发电位的早期成分,由听觉刺激后１０ｍｓ内所记录到的７个阳性快波所组成,该波群重叠在缓慢的阳性慢波上...     

犬脑干缺血时BAEP动态变化及海风藤的保护作用

犬脑干缺血时ＢＡＥＰ动态变化及海风藤的保护作用李黔宁王东武郑健赵士福岳桂明邓志宽何英（第三军医大学新桥医院,重庆６３００３７）本文观察了犬基底动脉结扎后脑干听觉诱发电位（ＢＡＥＰ）的动态变化并探讨了海风藤（ＰＷ）对脑干缺血的早期保护作用。Ｔａｂ．Ｐｅ...     

犬脑干缺血兴奋性氨基酸含量的改变对BAEP影响的初步研究

犬脑干缺血兴奋性氨基酸含量的改变对ＢＡＥＰ影响的初步研究岳桂明邓志宽（第三军医大学新桥医院神经内科,重庆６３００３７）目前的研究已经证实,兴奋性氨基酸（Ｅｘｃｉｔａｔｏｒｙａｍｉｎｏａｃｉｄｓ,ＥＡＡｓ）在脑缺血损伤中起重要病理作用。由于脑干内神经核...     

听觉诱发脑电小波分量的混沌研究——婴儿痉挛症认知功能障碍的机制探讨

通过对婴幼儿期难治性癫痫———婴儿痉挛症(infantile spasms, IS)听觉诱发脑电细貌混沌特性的研究,探讨与IS相伴的认知功能障碍的发生机制。研究方法是分别记录IS组及正常对照组对象的听觉诱发脑电,经Mexihat连续小波变换后,分别计算信号各尺度小波分量的相关维数。结果表明IS组与正常对照组的各小波分量相关维数的差别主要表现在小波的第3尺度分量上(频带范围是32~64 Hz,主要为γ频带范围),在这个尺度上正常组相关维数明显低于IS组(P<0.05)。相关维数的降低意味着大脑活动自由度的减少,表明大脑的各单元耦合加强。因为正常组脑干内信息传递通道完好,使得大脑各个单元之间的信息耦合较强; IS组则由于脑干功能的异常,存在神经信息传递障碍,进而影响到脑干及其与大脑各个局部之间的信息耦合。小波第3尺度处于较高频率范围(γ频带范围),而在大脑皮层上的基频信号与听觉调频信号经加工后所产生的神经信号正在这一频率范围,且这一信号与大脑高级认知功能密切相关。因此,IS患者γ频带细貌信号的相关维数高于正常值,能够解释IS认知功能发生障碍的原因。     

正常和卡那霉素中毒豚鼠听觉脑干诱发反应及频率跟随反应的比较研究

通过测定阈值和频谱分析,比较了正常和卡那霉素中毒后豚鼠听觉脑干反应(ABR)及频率跟随反应(FFR)的特性.正常FFR的非线性随刺激频率的减低而增加,表现为高次谐波的出现.从频谱中基频成分的峰很容易识别FFR阈值.卡那霉素作用后,高频FFR首先受到影响,波幅下降,阈值显著升高.低频FFR受到影响较小.同一动物ABR阈值尚未变化时高频FFR的基频峰值已下降,乃至消失.实验结果表明FFR对耳毒性药物中毒反应由于其包含有频率特性比ABR更灵敏,更便于定量分析.     

豚鼠脑干听觉中枢的立体定位

用常规组织学、声诱发电位、HRP逆行追踪等方法确定了豚鼠耳蜗核、上橄榄复合体、外侧丘系核及下丘的定位坐标值。对320—700g的豚鼠,耳蜗核中心位置的模坐标值为P 2.3,LL/RL 3.0,H1.5;上橄榄复合体为P2.3,LL/RL1.6,H-1.5;外侧丘系核为P0.8,LL/RL 2.0,H-1.5;下丘为A2.0,LL/RL 2.2,H5.5。对每一脑干中枢,当记录电极插至中心位置时短声诱发电位的振幅最大,主波为负。     

婴儿痉挛症脑干信息传导障碍的混沌学研究

婴儿痉挛症（Infantile Spasms,IS）是婴幼儿难治性癫痫。IS的发病机理至今也不清楚,目前比较一致的假说是：脑干是IS的责任结构,但该假说不能用神经生理学的传统方法来证实。从信息学的角度,婴儿弃挛症的发病机制可能是源自脑干神经信息传递障碍的脑干功能失调,为了证实这一论点,用可以反遇脑干传导功能的听觉诱发响应的相关维数,来评估脑干神经信息传导不同的功能状态,经过对IS患者、颞叶癫痫患者和健康人三个组的结果比较分析,表明IS患者脑干听觉诱发响应的相关维数明显低下,而颞叶癫痫患者该相关维数在颞叶病灶处最低。以上结果,证实了IS患者脑干神经信息传导功能障碍的存在。     

脑干听觉诱发电位与后循环TIA及脑干梗死的相关性研究

目的:研究脑干听觉诱发电位(BAEP)与后循环短暂性脑缺血发作(TIA)及脑干梗死的相关性。方法:选取我院收治的后循环TIA患者46例作为TIA组,选取同期收治的脑干梗死患者44例作为脑干梗死组,选取同期健康体检者49例作为健康组,TIA组和脑干梗死组均在发病后1周内进行BAEP检查,健康体检者在体检时进行BAEP检查,比较3组的Ⅰ、Ⅲ、Ⅴ波的潜伏期(PL)及Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ波峰间的潜伏期(IPL)。结果:TIA组BAEP异常率71.74%,脑干梗死组BAEP异常率56.82%,健康组BAEP异常率24.49%,TIA组患者BAEP异常率高于健康组,差异有统计学意义(P0.05)。脑干梗死组BAEP异常率高于健康组,差异有统计学意义(P0.05)。TIA组患者PL的Ⅰ、Ⅲ、Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。TIA组患者IPL的Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者PL的Ⅰ、Ⅲ、Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者IPL的Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者IPL与PL均明显高于TIA组(P0.05)。结论:BAEP与后循环TIA及脑干梗死存在相关性,并且较为敏感,是优秀的诊断方法之一。     

No effects of mobile phone electromagnetic field on auditory brainstem response

The present study investigated the possible effects of the electromagnetic field (EMF) emitted by an ordinary GSM mobile phone (902.4 MHz pulsed at 217 Hz) on brainstem auditory processing. Auditory brainstem responses (ABR) were recorded in 17 healthy young adults, without a mobile phone at baseline, and then with a mobile phone on the ear under EMF‐off and EMF‐on conditions. The amplitudes, latencies, and interwave intervals of the main ABR components (waves I, III, V) were compared among the three conditions. ABR waveforms showed no significant differences due to exposure, suggesting that short‐term exposure to mobile phone EMF did not affect the transmission of sensory stimuli from the cochlea up to the midbrain along the auditory nerve and brainstem auditory pathways. Bioelectromagnetics 31:48–55, 2010. © 2009 Wiley‐Liss, Inc.     

EEG动力学模型中混沌现象的研究

通过对脑电图（electroencephalogram,EEG）动力学模型模拟出的EEG信号的相图、分岔图、功率谱、关联维数和Lyapunov指数的对比研究,得出如下结论：1）该模型是按周期行为与混沌现象交替出现的间歇突发通向混沌的,且该间歇性与Hopf分岔、倍周期分岔和逆分岔有关;2）支持了EEG中存在混沌运动的观点。     

Effects of weak mobile phone - electromagnetic fields (GSM, UMTS) on event related potentials and cognitive functions

Modern mobile phones emit electromagnetic fields (EMF) ranging from 900 to 2000 MHz which are suggested to have an influence on well-being, attention and neurological parameters in mobile phone users. Until now most studies have investigated Global System for Mobile Communications (GSM)-EMF and only very few studies have focused on Universal Mobile Telecommunications System (UMTS)-EMF. Therefore, we tested the effects of both types of unilaterally presented EMF, 1950 UMTS (0.1 and 1 W/kg) and pulsed 900 MHz GSM (1 W/kg), on visually evoked occipital P100, the P300 of a continuous performance test, auditory evoked central N100 and the P300 during an oddball task as well as on the respective behavioral parameters, reaction time and false reactions, in 15 healthy, right handed subjects. A double-blind, randomized, crossover application of the test procedure was used. Neither the UMTS- nor the GSM-EMF produced any significant changes in the measured parameters compared to sham exposure. The results do not give any evidence for a deleterious effect of the EMF on normal healthy mobile phone users.     

Function of two β-carotenes near the D1 and D2 proteins in photosystem II dimers

The antenna proteins in photosystem II (PSII) not only promote energy transfer to the photosynthetic reaction center (RC) but provide also an efficient cation sink to re-reduce chlorophyll a if the electron transfer (ET) from the Mn-cluster is inhibited. Using the newest PSII dimer crystal structure (3.0 Å resolution), in which 11 β-carotene molecules (Car) and 14 lipids are visible in the PSII monomer, we calculated the redox potentials (E_m) of one-electron oxidation for all Car (E_m(Car)) by solving the Poisson-Boltzmann equation. In each PSII monomer, the D1 protein harbors a previously unlocated Car (Car_D1) in van der Waals contact with the chlorin ring of Chl_Z(D1). Each Car_D1 in the PSII dimer complex is located in the interface between the D1 and CP47 subunits, together with another four Car of the other PSII monomer and several lipid molecules. The proximity of Car bridging between Car_D1 and plastoquinone/Q_A may imply a direct charge recombination of Car⁺Q_A⁻. The calculated E_m(Car_D1) and E_m(Chl_Z(D1)) are, respectively, 83 and 126 mV higher than E_m(Car_D2) and E_m(Chl_Z(D2)), which could explain why Car_D2⁺ and Chl_Z(D2)⁺ are observed rather than the corresponding Car_D1⁺ and Chl_Z(D1)⁺.     

Analysis of the transformation effect in cytochrome b559 of photosystem II in terms of the model of the heme-quinone redox interaction

Transformation of three-component redox pattern of cytochrome (Cyt) b559 in PS II membrane fragments upon various treatments is manifested in decrease of the relative content (R) of the high potential (HP) redox form of Cyt b559 and concomitant increase in the fractions of the two lower potential forms. Redox titration of Cyt b559 in different types of PS II membrane preparations was performed and revealed that (1) alteration of redox titration curve of Cyt b559 upon treatment of a sample is not specific to the type of treatment; (2) each value of R_HP defines the individual shape of the redox titration curve; (3) population of Cyt b559 may exist in several stable forms with multicomponent redox pattern: three types of three-component redox pattern and one type of two-component redox pattern as well as in the form with a single E_m; (4) transformation of Cyt b559 proceeds as successive conversion between the stable forms with multicomponent redox pattern; (5) upon harsh treatments, Cyt b559 abruptly converts into the state with a single E_m which value is intermediate between the E_m values of the two lower potential forms. Analysis of the data using the model of Cyt b559-quinone redox interaction revealed that diminution of R_HP in a range from 80 to 10% reflects a shift in redox equilibrium between the heme group of Cyt b559 and the interacting quinone, due to a gradual decrease of 90?mV in E_m of the heme group at the virtually unchanged E_m of the quinone component.     

Influence of the temperature in the adsorption of sodium dodecyl sulfate on phosphatidylcholine liposomes

The influence of the temperature on the adsorption of monomeric and micellar solutions of the anionic surfactant sodium dodecyl sulfate (SDS) on phosphatidylcholine (PC) liposomes was investigated using the fluorescent probe 2-(p-toluidinyl)-naphthalene-6-sodium sulfonate (TNS). The number of adsorbed molecules was quantified by measuring changes in the electrostatic potential (Psi(o)) of the liposomes/probe during an incubation with SDS at varying temperatures. At low surfactant concentrations (from 0.05 to 0.25 mM), the increase in temperature reduced the number of surfactant molecules incorporated per vesicle regardless of the incubation time, whereas at high surfactant concentrations (from 0.50 to 1.0 mM) the incubation time has an opposite effect on this process. Thus, after 10s, the surfactant adsorption decreased with temperature, yet it increased progressively with time. The adsorption was linear with temperature below critical micellar concentration (CMC) of SDS and this linear tendency did not change above CMC. This suggests an adsorption of SDS monomers regardless of the surfactant concentration.