P物质抗体对豚鼠耳蜗核下丘核团内听觉诱发电位调谐曲线的影响

目的探索Ｐ物质在听觉脑干中枢中对声信号的频率分析作用。方法采用短音（ｔｏｎｅｐｉｐ）刺激、短纯音前掩蔽法和豚鼠耳蜗核（ｃｏｃｈｌｅａｒｎｕｃｌｅｕｓ,ＣＮ）、下丘（ｉｎｆｅｒｉｏｒｃｏｌｉｃｕｌｕｓ,ＩＣ）核团内电极,记录ＣＮ及ＩＣ核团内听觉诱发电位。观察核团内注射微量Ｐ物质抗体或对照注射等量兔血清后ＣＮ和ＩＣ核团内听觉诱发电位调谐曲线的变化。结果注入Ｐ物质抗体后,当探测音为１ｋＨｚ和２ｋＨｚ时,ＩＣ核团和ＣＮ核团内诱发电位调谐曲线的Ｑ１０ｄＢ值基本不变;当探测音为４ｋＨｚ和６ｋＨｚ时ＣＮ核团和ＩＣ核团内诱发电位调谐曲线的Ｑ１０ｄＢ值明显减小,与注入对照兔血清者相比差异非常显著（Ｐ＜０．０１）。高频侧斜率与低频侧斜率亦有相应改变。结论Ｐ物质可能作为听觉传入系统的神经递质或参与听觉脑干中枢的高频信号分析。     

听觉电生理动物实验平台组合

常用的听觉电生理动物实验主要有听觉诱发电位、耳声发射、蜗内电位（ＥＰ）、毛细胞内电位、听觉核团内电位等慢变化电位或直流电位。通常要完成以上实验，需听觉诱发电位仪、耳声发射仪、谱分析仪、多道生理记录仪等实验设备。这些仪器价格昂贵，且存在参数设置范围小，...     

不同龄豚鼠听性脑干反应和耳蜗核形态比较

为比较出生后不同时间及成年豚鼠听性脑干反应、耳蜗核结构、各亚核团细胞形态、细胞面积和密度，测试了出生后１２、２４、４８小时和成年豚鼠各５、５、９、２８只的听性脑干反应，部分作脑干切片，光学显微镜观察耳蜗核及各亚核团细胞形态，计算机图像处理系统测试前腹侧核和后腹侧核细胞面积和密度，发现（１）新生豚鼠除ＡＢＲ反应阈较成年豚鼠高平均１０ｄＢ外，波形、各波潜伏期和波间期无显著差异。（２）跟猫、沙土鼠和蝙蝠一样，新生豚鼠和成年豚鼠耳蜗核也可分为三个亚核团：背侧核（ＤＣＮ）、前腹侧核（ＡＶＣＮ）和后腹侧核（ＰＶＣＮ）。（３）豚鼠耳蜗核各亚核团内细胞分型也跟猫相似，ＡＶＣＮ内有大球细胞、小球细胞和球形细胞；ＰＶＣＮ内有章鱼细胞、多极细胞和球形细胞；ＤＣＮ内有颗粒细胞、锥形细胞和巨细胞。（４）成年豚鼠各亚核团平均细胞密度较新生豚鼠明显降低，出生１２小时到成年鼠ＡＶＣＮ和ＰＶＣＮ细胞密度分别减少２５．１３％和２２．１７％。（５）新生豚鼠ＡＶＣＮ细胞平均面积是成年组的８３．３６％，ＰＶＣＮ是成年组的９３．０４％。比较本实验测量的细胞密度和面积的改变和猫出生后到成熟耳蜗核细胞的资料，分析差异较大的可能原因。     

SP抗体对豚鼠耳蜗核、下丘核团内听觉诱发电位调谐曲线的影响

为探索P物质（SP）在听觉脑干中枢中对声信号的频率分析作用，采用短音刺激、短纯音前掩蔽法和豚鼠耳蜗核（Cochlea nucleus,CN)、下丘（Inferior coliculus,IC)核团内电极，记录耳侵略者 内的听觉诱发电位（CN－AEP）及下丘核团内听觉诱发电位（IC－AEP）。采用核团内注射微量抗SP抗体和等量兔血清作为对照观察CN－AEP调谐曲线（IC－AEP－TC）、IC－AEP调谐曲线（CN-AEP－TC）的变化。结果表明：注入抗SP抗体后，当探测音为1kHz和2kHz时，IC－AEP－TC与CN－AEP－TC的Q10 dB值基本不变，当探测音为4kHz和6kHz时CN－AEP－TC的Q10 dB值明显减小，与注入兔血清对照组相比有显著性差异（P＜0.05)，且IC－AEP－TC的Q10dB值减小更显著，高频端斜率（HFS）与低频端斜率（LFS）亦有相应改变。结果提示：SP抗体可能作为听觉传入系统的神经递质，且主要与听觉脑干中枢的高频信号分析有关。     

豚鼠下丘核团内听觉诱发电位时域及频域分析

用计算机叠加平均技术和脑干神经核团立体定位技术，记录10只豚鼠下丘核团内听觉诱发电位（IC－AEP）。对其时域中主波的潜伏期，振幅进行分析，并与豚鼠脑干听觉诱发电位（BAEP）时域比较，认为IC－AEP是BAEP之V波的主要成份。对侧耳给声刺激时，诱发的IC－AEP的振幅较高，提示在耳蜗核上行纤维中，大部分在到达下丘之前已交叉至对侧。用自回归模型谱估计（AR谱估计）及数字滤波技术对IC－AEP进行频域分析，发现豚鼠IC－AEP的频谱成份主要是在1000Hz以下，在AR变图上有3个峰：F0，F1和F2，谱峰分别位于160Hz，465Hz，745Hz左右，略低于豚鼠BAEP的相应谱峰频率，这可能由于BAEP的F1，F2是由多个神经元核团的不同谐振频率所合成，这一推测有待于其它神经核团进一步研究证实。     

无神经病学表现的人类免疫缺陷病毒阳性患者耳神经学和听觉脑干反应的表现

人类免疫缺陷病毒（ＨＩＶ）感染的神经病学表现（非晚期并发症）主要与ＨＩＶ在疾病早期的中枢神经系统（ＣＮＳ）定位有关。诱发电位（视觉、听觉和躯体党）和神经耳科学测试已证明在显示ＨＩＶ所致的亚临床ＣＮＳ功能紊乱方面十分敏感。本研究旨在通过脑干诱发电位（Ａ...     

听觉诱发电位在麻醉监测中的应用及进展

本综述了不同潜伏期的听觉诱发电位在麻醉深度及术中意识监测方面的应用，短潜伏听觉诱发电位应用较少，因只有吸入麻醉药对其影响显，中潜伏期听觉诱发电位可用于监测麻醉深度及术中意识水平，但与有意识的知觉恢复之间的关系还不是很明确。长潜伏期听觉诱发电位Ｐ３００可提供对意识水平正确的估计，但应用范围有限，而４０Ｈｚ听觉稳态电位的一些优点使其在可能成为一种新型的术中意识监测工具。     

耳蜗核蛋白在听觉信息处理中的作用

中枢听觉处理障碍（central auditory processing disorders，CAPD）是中枢听觉神经系统的一种神经生物学方面的缺陷，影响基本的听觉感知能力，包括定位、偏向，语音或非语音的辨别，听觉模式识别，听觉时间信息处理（时间统整、时间顺序和时间遮掩），竞争声或退化声下的听觉能力等。CAPD可能与其他疾病共存，影响患者的听力、学习和交流。病因包括创伤、神经毒性物质、神经系统疾病或损伤等。目前为止CAPD的发病机制不明。听觉中枢蛋白组学分析是研究CAPD发病机制的第一步，耳蜗核作为听觉传导通路中最底层的核团，对时间信息处理的准确性和声源定位起重要作用。本文重点分析耳蜗核相关蛋白在中枢听觉处理中的作用。     

OSAHS与耳鸣的相关性研究现状

阻塞性睡眠呼吸暂停低通气综合征(OSAHS)是睡眠障碍性疾病的常见类型,长期的呼吸暂停和低通气可引起不同程度的低氧血症,继发组织缺血缺氧,引起中枢及周围听觉系统损伤,使听觉传导通路异常、中枢听觉皮层产生适应性变化,进而导致耳鸣的感知。OSAHS患者体内5-羟色胺(5-HT)神经递质增多,激活受5-HT控制的听觉核团,影响听觉核团的神经电活动,继发耳鸣的产生。OSAHS患者自主交感神经系统兴奋,刺激耳蜗神经纤维诱发耳鸣;同时激活边缘系统和自主植物神经系统,进而产生焦虑、抑郁等不良情绪加重耳鸣。OSAHS患者长期睡眠结构紊乱形成睡眠剥夺,大脑内有毒代谢物质堆积,使耳鸣的中枢代偿障碍,继发耳鸣的产生。     

听力学

日50921 GABA和苦毒素等药物对鑫斯听觉中间神经元ANZ声反应特征的影响/于琦…/生物物理学报一1994,10(4)。一597~600 利用单细胞电生理记录技术,观测了在前胸施加GABA、苦毒素和筒箭毒等药物对轰斯Gampocleis grati。sa听觉上升神经元AN2的声反应放电活动的影响。发现GABA和简箭毒都能抑制ANZ的放电活动,而苦毒素则将其放电模式变为“toni。”型。图3参6(原提要)舫O马22P物质抗体对豚鼠耳蜗核、下丘核团内听觉诱发电位振幅、潜伏期的影响/郭梦和…/第四军医大学学报一1994,15(9)二401~404 目的:探索P物质(SP)在听觉脑干中枢中对…     

Frequency specificity of ABR evaluated by tuning curves

A tone on tone simultaneous masking paradigm was used to determine tuning curves of ABR both from the normal and hearing-impaired subjects. ABR tuning curves were constructed to define masker intensity that resulted in a 50% reduction in probe elicited wave V amplitude. The frequency specificity of each probe stimulus was evaluated by Q10, low cut-off slope, high cut-off slope and the maximum masker frequency calculated for the tuning curves. The results were as follows; 1) Q10, low cut-off slope and high cut-off slope increased gradually with the increase in rise time. However, prolongations of the rise time beyond 3 cycles of probe frequency yielded little improvement in Q10, low cut-off slope and high cut-off slope. 2) Q10, low cut-off slope and high cut-off slope for normal-hearing subjects increased gradually with the increase in stimulus frequency or the decrease in stimulus pressure. Maximum masker frequency of the tuning curves was not always equal to the frequency of probe without the 2-kHz. For the 0.5, 1kHz probe, the maximum masker frequency of the tuning curves showed higher values than the frequency of probe. For the 4kHz probe, the maximum masker frequency of the tuning curves showed lower values than the frequency of probe. The results indicate that the tone pip stimuli will allow to assess certain conditions of auditory function at different frequencies, and they show wider frequencies' spread in the cochlea area near stimulus frequencies. 3) For subject with abrupt high-frequency hearing loss (30dB/oct), a pronounced down-ward shift of maximum masker frequency, down-ward shift of high cut-off slope and up-ward shift of low cut-off slope were found when the probe was placed in the region of elevated threshold. For subject with low-frequency hearing loss (25dB/oct), a pronounced up-ward shift of maximum masker frequency, down-ward shift of low cut-off slope were found. Maximum masker frequency, low and high cut-off slope of hearing-impaired subjects were not always equal to those of normal subjects for same probe. Especially the value of the maximum masker frequency shifted to the direction in which the most sensitive frequency was observed in audiogram. The threshold of ABR reflected the cochlea function of the most sensitive area near stimulus frequencies. Greatest predictive error was observed in steeply sloping audiograms.     

The relation among hearing loss, sensory cell loss and tuning characteristics in the chinchilla

Evoked-potential tuning curves were obtained on over 150 chinchillas before and after acoustic overstimulation in order to relate the effects of changes in frequency selectivity to sensory cell loss over a wide range of hearing loss. Pre- and post-exposure measures of auditory thresholds and masked thresholds (simultaneous tone-on-tone paradigm) were obtained in each animal at 0.5, 1.0, 2.0, 4.0, 8.0 and 11.2 kHz, using the auditory evoked potential recorded from the inferior colliculus. Three tuning curve variables (Q10dB, low-frequency slope and high-frequency slope) were compared to the amount of noise-induced permanent threshold shift and to the percent sensory cell loss produced by a variety of noise exposures. Based upon large sample averages, frequencies showing permanent threshold shifts in excess of 10 dB also showed statistically significant differences between pre- and post-exposure measures of all three tuning curve variables. Shifts of less than 10 dB were not accompanied by statistically significant changes in the tuning curve variables. The percentage of outer hair cell loss, and percentage change in tuning curve characteristics showed systematic and parallel increases as threshold shifts increased at all probe tone frequencies except 8.0 and 11.2 kHz. In general, the results were consistent in showing that there is a systematic change in the variables which define the quality of tuning as hearing loss progressively increases and that these changes are clearly related to outer hair cell losses.     

Recovery of psychophysical tuning curves following noise exposure

Psychophysical tuning curves (PTCs) at 2 kHz and auditory thresholds (2 kHz and 4 kHz) were obtained from 18 normal-hearing listeners before and after exposure to a 5-min 110 dB SPL white noise. PTCs were quantified on five dimensions (Q10 tip, Q10 probe, d1oct, tip level and tip frequency). PTCs revealed continued cochlear effects beyond the time when TTS at 2 kHz demonstrated complete recovery.     

Recovery of auditory function following intense sound exposure in the neonatal chick

We report the changes in auditory function that occurred at selected intervals following exposure to an intense pure-tone stimulus. One day old chicks were exposed to a 0.9 kHz tone for 48 h at 120 dB. At 0, 1, 3, 6, 9, 12 and 15 days after exposure, cochlear nucleus sound-evoked potentials were used to assess threshold sensitivity and frequency selectivity. Immediately after removal from the pure tone a threshold shift of 60 dB relative to age-matched controls was measured. The sharpness of tuning curves, as measured by Q10 dB, decreased by over 50%. By post-exposure day 15, near complete recovery of function was seen, with the greatest recovery occurring within the first three days. We relate these results to recent reports of structural recovery on the basilar papilla of the chick.     

Tuning of the auditory brainstem OFF responses is complementary to tuning of the auditory brainstem ON response

Continuous masking studies show a complementary pattern of effects on the auditory brainstem responses (ABRs) which are generated by the onset and by the offset of a midfrequency tone. The masking profiles of the two responses are almost opposite with a probe stimulus frequency of 32 kHz (16-32 kHz is the midfrequency region for the CBA/J mouse). The Offset and Onset ABR tuning curves (TCs) also reveal very different properties at the midfrequencies of 16, 20, 24 and 32 kHz. The Offset TC is exquisitely sensitive to masking by very low intensity stimuli at a narrow range of frequencies which are lower than the probe stimulus frequency. Continuous masking produces a well-tuned low frequency tip to the Offset TC. For Offset TCs generated in response to midfrequency tones, the Q+10 dB of this tip averages 8.3. Masking at this low frequency tip of the Offset TC has no observable effect on the Onset ABR. The Offset ABR is also sensitive to masking by a narrow range of frequencies which are higher than the probe stimulus frequency. This occurs at an intensity which also has no observable effect on the Onset ABR. The Q+10 dB of this high frequency tip averages 9.2. The average frequencies where these Offset TC tips occur fit the cubic difference formula (2f1-f2), which describes a distortion product of two-tone suppression. At low probe stimulus frequencies, there is only a high frequency Offset TC tip; at high stimulus frequencies, only a low frequency tip. The high frequency tip has a higher threshold and appears more susceptible to metabolic disturbance. The Offset ABR TC also has a peak which corresponds to the probe stimulus frequency. Continuous masking with the stimulus frequency produces nonmonotonic enhancement of the Offset ABR, while it simultaneously reduces the magnitude of the Onset ABR. The tuning of this Offset TC peak (measured as Q-10 dB) is almost always much sharper than the corresponding Onset TC tip in the same mouse. These values for midfrequency stimuli average 6.2 for the Onset, and 13.6 for the Offset TCs. This fine tuning of the Offset TC at the probe stimulus frequency occurs at SPLs from 50 to more than 90 dB.     

Offset tuning curves generated by simultaneous masking are more finely tuned than those generated by forward masking

The rapid ending of a tone produces an evoked potential which has different properties than that which is produced by the sudden onset of a tone. At the level of the round window, the offset N1 N2 follows the ending of the cochlear microphonic (CM) by approximately the same amount of time as does the onset N1 N2 to the onset of the CM. Both onset and offset responses are abolished with cochlear lesion. Continuous masking was used to generate tuning curves (TCs) from the NI-PI component of the evoked potential recorded from the round window of the gerbil. Those evoked potentials generated in response to the tone onset were complementary in appearance to those generated in response to the tone offset. TCs generated by continuous masking of the NI-PII component of the auditory brainstem response (ABR) of the gerbil show the same pattern. When it is generated by simultaneous masking, the midfrequency offset TC in the gerbil and mouse is W-shaped. It has two well tuned tips which occur at frequencies below and above that of the probe stimulus used to generate the TC. It also has an even better tuned peak occurring at or slightly above the probe stimulus frequency, which becomes sharper as the masker sound pressure level (SPL) is increased from 50 to over 80 dB. Because the midfrequency onset response is approximately 40 dB lower than the midfrequency offset response, probe stimuli for onset TCs are generally set at lower SPLs. When the onset probe stimulus is set to the same level as that of the offset probe, the Q10 dB of the offset TC may be up to 10 times the value of the Q10 dB of the onset TC. The offset TC generated in the CBA/J mouse by forward masking is quite different from that produced by simultaneous masking. Both forward and simultaneous conditions utilized a 40 ms duration tone to mask the PI-NI component of offset and onset ABRs of the mouse which were evoked by a 10 ms duration, 32 kHz tone, presented at an interstimulus interval of 160 ms. Forward masking (when compared with simultaneous masking) resulted in a more sharply tuned onset TC. But the offset TC was much less sharply tuned in the forward masking condition. This suggests that the offset response may reflect functions which are involved with fine tuning at moderate to high intensities in the presence of simultaneous sounds of similar spectral characteristics.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cochlear and CNS tonotopy: normal physiological shifts in the mustached bat.

The ear of the mustached bat (Pteronotus parnellii) shows marked cochlear resonance near 60 kHz and many sharply tuned neurons throughout the brain have best frequencies (BF) near the cochlear resonance frequency (CRF). Controlled changes in the normal physiological range of body temperature (approx 37-42 degrees C) were used to change the CRF and to study the tuning properties of neurons in the cochlear nucleus (CN) and inferior colliculus (IC). In all cases there were concomitant shifts in the CRF and the BFs. Results were the same for single and multi-units, and for CN and IC units. Although the BF reliably changed with shifts in the CRF, the majority of the units showed no change in minimum threshold or the sharpness (Q10 dB) of tuning. The temperature-induced effects on cochlear tuning were similar to those previously described in nonmammalian vertebrates. The physiological data reveal that, within a narrow frequency band, cochlear and CNS tonotopy are labile in the mustached bat. The lability of tuning is further substantiated by adaptations of biosonar emission behavior with shifts in CRF (Henson et al., 1990).     

The influence of cochlear hearing loss and probe tone level on compound action potential tuning curves in humans

The effect of cochlear hearing loss and of probe tone level on slopes and sharpness of compound action potential tuning curves was investigated. Thirty-one simultaneously masked isoreduction (50%) tuning curves were determined in 26 adults with cochlear hearing losses up to 60 dB. Probe tone frequency was 2 or 3 kHz. Probe tone level was chosen as close as possible to the action potential threshold, usually within 30 dB. In 5 cases a second tuning curve was determined at a 20–30 dB higher probe tone level in order to differentiate between effects of hearing loss and of probe tone level itself on decrease of selectivity. Tuning was analysed in terms of high- and low-frequency slopes of the tuning curves, both in the steepest parts near the tip and overall, and in terms of Q_10dB. Slopes and tuning quality diminished with increasing hearing loss up to 60 dB. Part of the decrease in Q₁₀ could be attributed to increased probe tone level, implying that frequency selectivity is also a level-dependent property. In the same group of subjects so called ‘narrow-band’ (or ‘derived response’) compound action potential latencies were determined at 90 dB per SPL and a derived frequency similar to the probe tone in the tuning curve experiments. Narrow band latencies did not change significantly out of the normal range (2 periods) with increasing hearing loss. This implies that narow band latencies are not related to hearing loss, but reflect only the probe-level dependent impulse response delay. Analysis shows that it is possible to derived Q_10dB from narrow band latencies with probe level as a parameter.     

Effects of efferent acoustic reflex activation on psychoacoustical tuning curves in humans

CONCLUSIONS: The results show that, in humans, activation of the contralateral EAR makes the PTC narrower at 1 kHz but wider at 4 kHz. These data are consistent with those reported previously in animals and demonstrate that, during medial efferent stimulation in humans, frequency resolution is improved at low frequencies but impaired at high frequencies. OBJECTIVE: To evaluate, in humans, the effect of activation of the contralateral efferent acoustic reflex (EAR) on the psychoacoustical tuning curves (PTCs) recorded for 1- and 4-kHz probe tones. MATERIAL AND METHODS. Ten young (20-30 years) volunteers served as subjects. They had normal hearing (thresholds <20 dB HL in the frequency range 0.25-8 kHz) and a functioning EAR (contralateral suppression of transient-evoked otoacoustic emissions > or = 0.8 dB). Frequency resolution was evaluated using PTCs. PTCs were recorded at 1 and 4 kHz using a simultaneous masking method. Q10 and Q20 were calculated as the ratio between the test frequency and the bandwidth of the PTC at 10 and 20 dB above the tip of the curve, respectively. The EAR was activated with a 40-dB SL contralateral narrow-band noise centered on the characteristic frequency of the PTC (1 or 4 kHz). Q10 and Q20 were measured in the presence and absence of the contralateral noise. RESULTS: Activation of the EAR led to a significant increase (p < 0.001) in Q10 at 1 kHz and a significant decrease (p <0.001) at 4 kHz. Changes in the value of Q20 were not significant.     

Long-Term Frequency Tuning of Local Field Potentials in the Auditory Cortex of the Waking Guinea Pig

The goal of our study was to determine the extent of changes in frequency tuning in the auditory cortex over weeks. The subjects were awake adult male guinea pigs (n = 8) bearing electrodes chronically implanted in layers IV-VI of primary auditory cortex. Tuning was determined by presenting sequences of pure tone bursts (approximately 0.97-41.97 kHz, -20 to 80 dB, 100-ms tone duration, 5-ms rise-fall, 800-ms intertone intervals, 1.5-s intersequence interval) either in 0.5-octave steps (n = 5, 14 probes) or 0.25-octave steps (n = 3, 9 probes) delivered to the ear contralateral to recording sites. Tuning curves were determined for local field potentials (LFPs), which were tuned to frequency (negative potential, latency to peak 15-20 ms), repeatedly for up to 27 days (0.5 octave) or 12 days (0.25 octave). Characteristic frequency (CF), best frequency at 10 and 30 dB above absolute threshold (BF10, BF30), threshold (TH), and bandwidth (10 dB above threshold; BW) were measured. Absolute amplitude often decreased across weeks, necessitating normalization of amplitude. However, there were no significant trends in tuning over days for CF, BF10, or BF30 for either the half- or the quarter-octave group. Both groups exhibited random daily variations in frequency tuning, the quarter-octave group revealing larger variations averaging 0.228, 0.211, and 0.250 octave for CF, BF10, and BF30, respectively. Therefore, frequency tuning in waking animals does not exhibit directional drift over very long periods of time. However, daily tuning variations on the order of 0.20-0.25 octave indicate that the peaks of tuning curves (CF, BF) represent a preferred frequency range rather than a fixed frequency.