稳态白噪声对豚鼠听觉脑干诱发反应(ABR)功率谱的影响

本文对豚鼠125和131dBSPL稳态白噪声暴露后听觉脑干诱发反应(ABR)功率谱进行了研究.研究结果表明:125dBSPL噪声暴露组0—200、210—500Hz频段谱能量比对照组相应频段谱能量增多(P<0.05),而510—900Hz频段谱能量却显著下降(P<0.01);131dBSPL噪声暴露组0-200Hz频段谱能量显著下降(P<0.01),但210-500Hz、910-1400Hz频段谱能量却明显增多(P<0.01).     

白噪声对听觉脑干电反应(ABR)和耳蜗电图(ECochG)的影响

本文通过20例听力正常人和10例听力正常豚鼠研究了白噪声对耳蜗电图(ECochG)和听觉脑干电反应(ABR)的干涉作用。实验结果表明,白噪声比短声(信号)的声强级低30dB(SL)以上时,ECochG和ABR的振幅仅轻微减小。白噪声与短声的声强级相等时,ECochG与ABR的振幅和出现率会明显受到干涉而减小,甚至完全消失。但是,此时的耳蜗微音器电位(CM)并未观察到有明显的变化。这意味着白噪声对ECochG和ABR的干涉作用主要与围绕毛细胞基底部的突触产生的抑制密切相关。由于白噪声对ABR各波的干涉有些差异,所以认为这种抑制,可能既包括脑中抑制也包括侧方抑制。     

噪声短时暴露所致的耳蜗电位改变

本实验观察115dB(SPL)白噪声暴露20min对豚鼠耳蜗直流电位(EP),复合听神经动作电位(CAP),微音器电位(CM)的影响。发现此种噪声暴露确可提高源于血管纹的正EP(P-EP),说明有血管纹功能的代偿性增强;而负EP(N-EP)变化不大。AP及CM输入-输出函数的变化说明噪声首先影响外毛细胞的主动运动功能。EP与耳蜗电图的对照分析表明,血管纹功能的改变确能影响噪声性听损伤的发展。     

20 Hz方波及正弦波频闪光对豚鼠眼球发育的影响

目的评估持续高频正弦波及方波频闪光对豚鼠眼球正视化及眼球发育的影响。方法 30只2周龄豚鼠分为20 Hz方波、20 Hz正弦波频闪组及无频闪对照组共3组(n=10),光照强度统一为500 lx,每2周测量豚鼠眼球屈光度、眼轴长度及曲率半径,第8周时对三组豚鼠行电生理闪光视网膜电图(F-ERG)检查,取出眼球后行病理评估组织学改变。结果 3组豚鼠眼球屈光度与眼轴长度呈正相关,第8周时与对照组相比,20 Hz正弦波频闪组及20 Hz方波屈光度出现(-0.75±0.79)D及(-1.50±0.91)D近视性改变(P0.05),曲率半径3组间差异无显著性(P0.05),F-ERG潜伏期20 Hz正弦波及20 Hz方波频闪组a波延长了3.8 s及7.9 s,病理三组间组织学未见显著性差异。结论持续暴露于高频方波及正弦波频闪光一定程度上影响眼正视化。     

催产素对强噪声所致声音强度辨别功能损伤的拮抗作用

我们已发现外源性催产素能改善人及豚鼠以恼干电位或耳蜗电图为指标的听觉功能。本文在对照组和预先给予催产素处理的豚鼠上,比较了125dB(SPL)白噪声暴露20min前后声音强度辨别能力的改变,并比较了肌内注射和侧脑室微量注射两种不同给药途径的作用。实验以重复短声调幅引起的皮层慢反应电位阈值I_r为指标,观察了催产素对豚鼠声音强度辨别功能的影响。结果发现对照组噪声暴露所致I_r的升高明显高于催产素处理组,且此种暂时性阈移的恢复也明显慢于催产素组;催产素两种给药途径的结果无明显差异。这些结果进一步提示催产素对声音强度辨别功能具有保护作用。     

长期高海拔暴露影响移居者空间工作记忆——来自时域和频域分析的证据

长期高海拔暴露影响空间工作记忆。以往研究主要集中于分析时域脑电成分,而非关注频域上不同频段的神经振荡。为探究长期高海拔暴露影响空间工作记忆的时间动态特征与神经振荡过程,本研究采用n-back任务结合事件相关电位技术记录生长在低海拔地区、成年后移居高海拔地区满3年的20名健康年轻人(高海拔组)和从未到过高海拔的21名年轻人(低海拔组)的脑电数据,并进行时域与频域分析。结果显示,与低海拔组相比,高海拔组反应时更长,在2-back条件下正确率更低;在2-back条件下,高海拔组的P2波幅更正,晚期正电位(late positive potential, LPP)波幅更负;早期delta频段(1～4 Hz,160～300 ms)的能量值更大,晚期delta频段(1～4 Hz, 450～650 ms)、theta频段(4～8 Hz, 450～650 ms)的能量值更小。以上结果表明,长期高海拔暴露影响移居者空间工作记忆能力,主要体现为后期匹配阶段注意资源不足,反应抑制能力与信息维持能力降低,从而损害空间工作记忆能力。     

脑干听觉诱发电位的时序分析及频谱分析

本文从参数建模和频域方面对40例BAEP信号进行了分析,在参数建模方面,对正常BAEP信号建立了10阶自回归AR模型,着重分析两侧极点辐角总差和最大极点辐角,发现正常情况下两侧BAEP信号的AR模型的极点分布大致相同,极点辐角总差不超过50度,最大极点辐角范围为120～160度。在频域上,对正常BAEP信号进行了自/互功率谱分析。发现自功率谱和互功率谱在140Hz,550Hz和920Hz附近各有一个主峰,而在1.2kHz以后能量衰减很快。本文探讨了各参数的变化的生理意义,并给出了正常值的统计结果。     

豚鼠耳蜗电图面神经管慢性引导方法的改进

豚鼠耳蜗电图(ECochG)是目前听觉电生理研究的常用手段。Hildesher介绍了经面神经管引导豚鼠ECochG的方法,国内尚未见报道。我们对此法做了改进,使其更简单易行,并提高了成功率及远期效果,同时应用此法对清醒豚鼠的ECochG各种指标做了系统观察。     

豚鼠耳蜗电图慢成分的研究

选用0.8-150Hz的带通滤波,从豚鼠圆窗记录出一负一正相慢电位.实验结果表明.其对0.5kHz短音的反应阈为729dB nHL.较耳蜗电图快成分低38.27dB nHL.通过离断听觉传导径路不同水平对该电位的观察,表明它是毛细胞及听神经电反应的慢成分.而且可能受听觉传出神经的调控.     

吗啡诱导大鼠穿梭觅药状态下内侧前额皮层边缘前区遥测脑电小波包提取及熵分析

本研究旨在研究内侧前额皮质(medial prefrontal cortex,m PFC)边缘前区(prelimbic cortical area,PL)遥测脑电的特征性改变与觅药行为之间的关系。将PL区埋藏脑立体定位电极的大鼠分成手术对照组和吗啡诱导组,后者制作吗啡诱导条件性位置偏爱(conditioned place preference,CPP)模型。利用CPP视频系统结合脑电无线遥测技术,记录两组大鼠在黑-白箱穿梭和白-黑箱穿梭时大鼠PL区实时脑电,采用小波包提取、Welch谱功率算法、归一化幅值和Shannon熵分析技术,对所测原始脑电波进行综合分析。结果显示,与手术对照组比较,吗啡诱导CPP组大鼠黑-白箱穿梭潜伏期,左侧PL区小波提取脑电各频段平均波幅减小,脑电成分在10~50 Hz频段Welch谱功率强度显著增加(P0.01或P0.05),脑电β、γ1、γ2波Shannon熵值升高(P0.01或P0.05),平均信息熵降低(P0.01)。上述结果提示,吗啡诱导CPP组大鼠黑-白箱穿梭时,左侧PL区脑电各频段大幅波减少,脑电10~50 Hz频率Welch谱功率强度增加,β、γ1和γ2波Shannon熵值升高;这些变化可能与大鼠觅药意识的形成和即将发动的觅药行为产生有关。     

Power spectral analysis of heart rate variability for assessment of diurnal variation of autonomic nervous activity in guinea pigs.

We established characteristics of power spectral analysis of heart rate variability, and assessed the diurnal variations of autonomic nervous function in guinea pigs. For this purpose, an electrocardiogram (ECG) was recorded for 24 hr from conscious and unrestrained guinea pigs using a telemetry system. There were two major spectral components, at low frequency (LF) and high frequency (HF) bands, in the power spectrum of HR variability. On the basis of these data, we defined two frequency bands of interest: LF (0.07-0.7 Hz) and HF (0.7-3.0 Hz). The power of LF was higher than that of HF in the normal guinea pigs. Atropine significantly reduced power at HF. Propranolol also significantly reduced power at LF. Furthermore, the decrease in the parasympathetic mechanism produced by atropine was reflected in a slight increase in the LF/HF ratio. The LF/HF ratio appeared to follow the reductions of sympathetic activity produced by propranolol. Autonomic blockade studies indicated that the HF component reflected parasympathetic activity and the LF/HF ratio seemed to be a convenient index of autonomic balance. Nocturnal patterns, in which the values of heart rate in the dark phase (20:00-06:00) were higher than those in the light phase (06:00-20:00), were observed. However, the HF, LF and the LF/HF ratio showed no daily pattern. These results suggest that the autonomic nervous function in guinea pigs has no clear circadian rhythmicity. Therefore, this information may be useful for future studies concerning the autonomic nervous function in this species.     

黑蝉(C.atrata Fabricius.)鸣声的方向性和第三气门的功能

黑蝉鸣声的波形结构无明显的方向性.单音节的重复周期和调幅脉冲列的间隔(I_1和I_2)分别为9.787±0.813ms、2.286±0.093ms和1.874±0.063ms.幅值特性有明显的方向性.主峰频率(MPF=5.47±0.11kHz)的幅值,头向和背向分别比尾向下降5.9dB和3.9dB,侧向和腹向分别增高1.1dB和2.3dB.两侧第三气门受阻后鸣声的波形结构和音色都产生明显变化.I_1和I_2分别为0.912±0.156ms和1.099±0.113ms,约为正常值的40—59%.有三个谱带,MPF为5775Hz,两侧谱带的峰值频率为4575Hz和7025Hz,分别下降1.5dB和3.4dB.     

变压器噪声暴露对SD大鼠听力及应激状态的影响研究

目的:探究短时间内低声级强度低频的变压器噪声暴露对SD大鼠听力及应激状态方面的影响。方法:选取90只SPF级健康无听力障碍的(雌雄各半)SD大鼠作为实验对象,随机分为实验A、B组和对照C组,A、B组分别给予声级上限为65 dB SPL、60 dB SPL(频谱范围:100~800 Hz)的变压器噪声,噪声暴露时程为8周,每日噪声给予时间为22点至次日8点,C组在相同条件下饲养,不给予噪声暴露。噪声暴露结束后,通过DPOAE(畸变耳声发射)、ABR(听性脑干反应)检测、耳蜗铺片及毛细胞计数对SD大鼠听力学状况进行评估;通过血清中促肾上腺皮质激素(ACTH)、血清皮质醇(CORT)对SD大鼠的应激状态进行评估。结果:在变压器噪声暴露的8周内,各组大鼠生长状况良好,体重均呈正常生理性增长,组间无明显差异(P0.05);在变压器噪声暴露8周后,对A、B、C三组大鼠的听力学指标进行两两比较,组间均无明显差异(P0.05),对大鼠血清中促肾上腺皮质激素(ACTH)、血清皮质醇(CORT)的含量进行三组间比较,组间差异均无统计学意义(P0.05)。结论:连续暴露于声压级上限65/60 dB SPL,频谱范围为100~800 Hz的变压器噪声下8周(10小时/天)对SD大鼠听力未产生明显影响,未引发SD大鼠应激状态。     

A new method for estimating voice sounds transmitted to the chest wall in children and adolescents

A new method for estimating voice sound transmission to the chest wall is proposed. The spectral characteristics of voice-transmitted sounds have been estimated in children and adolescents. A total of 37 subjects aged 7–17 yers were examined. The frequency of the first spectral peak of the voice-transmitted sounds “tree, tree” (M ± SD) is 263.7 ± 7.82 and 253 ± 4.29 Hz at ages of 7–11 and 12–14 years, respectively. In male adolescents aged 15–17 years, this frequency is decreased to 100–150 Hz. The slope of the descending segment of the spectrum on the high-frequency side of the peak steadily increases on moving from the upper to the lower zones of the lungs, which may be related to the increase in the air content of the lung tissue. The difference between the amplitudes of the first and second spectral peaks of voice-transmitted sounds over symmetric regions of the chest on the right and left sides (Me(Q75-Q25)) is ?0.1(11.0) dB and does not depend on age or sex, which can be interpreted as an average statistical symmetry of sound transmission.     

Combined effects of vibration and noise on palmar sweating in healthy subjects

The combined effects of vibration and noise on palmar sweating were studied experimentally in healthy subjects. Ten subjects were exposed to vibration at an acceleration of 100 m.sec-2 root mean square at a frequency of 125 Hz, a noise level of 105 dB(A) at a frequency of 1000 Hz and both stimuli together. Vibration was applied to the right hand and noise to both ears from headphones. Palmar sweating was measured by the ventilated capsule method. Vibration caused a marked increase in palmar sweating of the right hand directly exposed to vibration and also of the left hand not exposed to vibration. Simultaneous vibration and noise caused a greater increase in palmar sweating than by each of the factors separately. The combined effects tended to be greater in subjects who were more susceptible to vibration or noise.     

Critical ratio: effects of contralateral masking on normal and pathological ears]

In order to evaluate the central interferences on the auditory efficiency, the effect of contralateral masking noise on Critical Ratio (CR) has been studied in 14 normal ears (control group), in 12 ears with cochlear disorders and in 6 with retrocochlear lesion (acoustic neuromas); in all cases the impairment was unilateral, while the other ear was normal. CR values were calculated for 1 KHz pulsed tones (duration 500 ms, rise/fall 25 ms, duty cycle of 50%); the masking noise was a wide band (90-20,000 Hz) delivered at 40 dB SL. The results have demonstrated that in the presence of contralateral masking noise, CRs don't modify both in the normal ears and in those with retrocochlear disorder, whereas they increase, almost always, in ears with cochlear deafness. These results demonstrate that the involvement of central auditory pathways, because of contralateral noise, makes the auditory efficiency worse, only in ears with cochlear dysfunctions; this behaviour seems to confirm the peripheral origin of CR.     

Spectral analysis of heart rate variability in the beluga (<Emphasis Type="Italic">Delphinapterus leucas</Emphasis>) during exposure to acoustic noise

The spectral parameters of heart rate variability are a measure of activation of the sympathetic and parasympathetic branches of the mammalian autonomic nervous system. In this study, spectral analysis was used for the first time to evaluate the impact of acoustic noise (one of the major anthropogenic factors) on a cetacean. We analyzed cardiac intervals in a captive beluga (a member of the Odontoceti whales) in response to a 10-min band-pass acoustic noise at an intensity of 150–165 dB and frequency of 19–38 kHz. The beluga’s response to acoustic noise, when examined shortly after the animal’s capture, was characterized by a sharp tachycardia (the first phase) followed by a decrease in the heart rate (the second phase). Based on spectral analysis, the frequency range of heart rate oscillations in the beluga decreased during the period of tachycardia while shifting to a lower frequency range (below 0.01 Hz) as compared with the control conditions. Accordingly, the spectral power of low-frequency components was reduced. During the second phase, the range of heart rate variability oscillations expanded and fully recovered only after the noise had been turned off. After one year in captivity, no significant changes in the heart rate parameters (both in time and frequency domain) were recorded in response to a similar noise exposure. Therefore, the changes in the heart rate spectral components in the studied beluga exposed to acoustic noise were comparable to those recorded in terrestrial mammals and in humans in stressful and emotionally negative situations. The spectral characteristics of heart rate oscillations can be used as a quantitative measure of beluga whales’ response to acoustic noise as a stress factor.     

Capsaicin increases modulation of sympathetic nerve activity in rats: measurement using power spectral analysis of heart rate fluctuations

We assessed the sympatho-vagal activities of the heart after administration of capsaicin by measuring the power spectral analysis in rats. There were major two frequency components of heart rate variability, which we defined as high (1.0 Hz <, HF) and low (LF, < 1.0 Hz) frequency components. Vagal blockade by atropine abolished the high frequency component, and lowered the amplitude of the low frequency component. On the other hand, under conditions of sympathetic blockade by propranolol, the low frequency component was reduced. Combined vagal and sympathetic blockade abolished all heart rate fluctuations. We analyzed the low and high frequency components by integrating the spectrum for the respective band width. The rats administered capsaicin had a higher heart rate and sympathetic nervous system index (LF/HF) than the control group of rats. These results suggest that power spectral analysis is an effective and noninvasive method for detecting subtle changes in autonomic activity in response to the intake of foods or drugs.