Responses to trigeminal irritants at different locations of the human nasal mucosa

BACKGROUND: Previous work suggests differences in the distribution of human intranasal trigeminal receptors. The aim of this study was to investigate these topographic differences for different concentrations of different trigeminal irritants using an electrophysiologic measure of trigeminal activation, the negative mucosa potential (NMP). MATERIALS AND METHODS: A total of 15 healthy volunteers participated. Presented by a computer-controlled olfactometer CO2 (30% and 40% v/v), ethyl acetate (5.5% and 9.3% v/v) and acetic acid (205 and 40% v/v) were used for stimulation. NMP was recorded at the middle septum, the middle turbinate, and the floor of the nasal cavity. RESULTS: Maximum amplitudes of the NMP were found at the middle septum and were lowest at the nasal floor. Response amplitudes were related to stimulus concentrations. There was no significant difference between responses to the three different stimuli in relation to three recording sites. CONCLUSIONS: In agreement with previous work, the present data suggest that there are topographic differences in the responsiveness of the mucosa to chemical irritants.     

Mechanics of the basilar membrane in Caiman crocodilus

Vibration measurements were made at a number of positions near the proximal (basal) end of the basilar membrane, and on the columella footplate, of Caiman crocodilus using a capacitive probe. The measurements established the existence of a mechanical travelling wave in this species. They showed no significant change of mechanical tuning with temperature, and were highly significantly different from previous reports of neural temperature sensitivity (Smolders, J. and Klinke, R. (1984): J. Comp. Physiol. 155, 19-30). Thus the neural sensitivity to temperature change appears not to depend upon basilar membrane mechanics. One interpretation of this is that the basilar membrane passively precedes an active temperature-sensitive filter. It was also found that the limbus supporting the basilar membrane had a measurable, but unturned, vibration and that the effect of draining scala tympani for the measurements was to increase the basilar membrane tuning frequency by a factor of about 1.5.     

声带息肉的发生部位与手术效果的声学评价

目的探讨不同部位的单发声带息肉在手术前后嗓音客观声学参数之间的变化规律。方法对48例女性单发声带息肉患者术前行Ofympus内镜测量器检查,明确声带息肉的位置、形态;使用MDVP嗓音分析软件对声带息肉患者术前、术后3天及1周行声学分析检查。比较分析声学参数基频F0、频率微扰百分比Jitt．振幅微扰百分比shim、噪谐经N／H之间的变化。结果①术前：基频F0元音／a／两组间存在显著性差异,／i／和／ ／音两组间无显著性差异;／a／、／i／和／ ／3个元音的Jitt、shim、N／H声带息肉前1／3组均明显高于中1／3组,其中／i／和／ ／两元音的N／H两组间差异不显著。②术后3天：3个元音的基频F0显示声带息肉前1／3组较中1／3组平均值稍低;3个元音的Jitt平均值显示声带前1／3组较中1／3组平均值稍低;／a／、／ ／音的shim平均值声带息肉前1／3组比中1／3组值略高;3个元音的N／H平均值声带息肉前1／3组与中1／3组相似。③术后1周：3个元音的F0、Jitt、Shim、N／H平均值声带息肉前1／3组与中1／3组相似。结论声带息肉术后声嘶均有明显好转;术后3天声带息肉前1／3组较中1／3组声嘶明显,但术后1周基本相同,提示声带息肉术后恢复时间为1周左右。     

Behavioural measurement of level-dependent shifts in the vibration pattern on the basilar membrane at 1 and 2 kHz

Physiological data suggest that the peak of the travelling wave on the basilar membrane evoked by a high-frequency sinusoid moves towards the base with increasing level. Previously, we used a forward-masking technique to provide evidence for a similar effect in humans at 4 and 6.5 kHz. In the present study, we used a similar technique to determine whether level-dependent shifts occur for mid-range frequencies. The signal was a brief 1-kHz or 2-kHz tone presented at 10 dB SL (approximately 30 dB SPL). For three fixed masker levels (75, 85 and 95 dB SPL), we measured the duration of the gap between the masker and signal required to give 79.4% correct detection of the signal (called the 'gap threshold') as a function of masker frequency; the longer the gap threshold, the more effective is the masker. The gap-threshold patterns nearly always showed a single peak close to the signal frequency. The gap-threshold patterns spread markedly towards lower frequencies with increasing masker level, but the frequency at the peak did not change systematically with level. We conclude that, for mid-range frequencies, the peak of the travelling wave does not shift significantly with increasing level over the range 30-95 dB SPL, but the envelope of the travelling wave becomes more shallow on its basal side.     

Travelling wave motion along the pigeon basilar membrane

The basilar membrane (BM) motion in the pigeon was measured using the M?ssbauer technique. Tonotopic frequency mapping and travelling wave motion were observed over the basal 35% of the BM. The sensitivity and sharpness of the BM tuning depended on the physiological condition of the cochlea. The observed amplitude responses did not match the frequency threshold tuning curves of single primary auditory fibers.     

Damage of the basilar membrane by acoustic stimulation

Summary Sound exposures of more than 130 dB lead to typical tears in the basilar membrane in the area of maximal damage. The position, size, and number of these tears are evaluated.     

The ultrastructure of the basilar membrane in the cat

A detailed study of the feline basilar membrane was performed in 13 cochleae with light microscopy and in six with electron microscopy. The distribution of the mesothelial cells and homogeneous ground substance with the filaments was recorded and plotted as a function of length along the cochlear duct. The width, thickness and number of filaments were also measured. In the lower basal turn the basilar membrane was narrowest and its entire thickness was occupied by filaments. In the apical region the width was maximal and the filaments were fewer. The density of the filaments counted in the bundles showed no significant difference along the cochlear duct or across the width of the basilar membrane, but the number of filaments decreased markedly (approximately a ten-fold difference) from base to apex. The number of mesothelial cells increased towards the apex. These morphological characteristics may be related to the different motion pattern of the basilar membrane along the length of the cochlear duct. A discontinuity of the basement membrane was noted in the apical region in all cochleae studied. These gaps seemed to provide structural evidence for the permeability of the basilar membrane in this area. The vas spiralis was present as a blood vessel in two specimens and only in the apical region. Thus, its function as the sole nutritional source for the organ of Corti is doubtful.     

不同部位鼓室骨瘤临床特征分析

目的:探讨不同部位鼓室骨瘤患者的临床特征以及干预、治疗方法。方法:回顾总结2例不同部位鼓室骨瘤患者的临床资料,包括病史、听力学及影像学检查、手术方案和随访结果,结合国内外文献报道的36例鼓室骨瘤患者的临床特征、治疗方式及疗效进行总结分析。结果:本研究收集的2例鼓室骨瘤患者病变分别来源于中鼓室的鼓岬和砧骨,均无明显的病因...     

Studies on fibrous tissues of the basilar membrane in inner ear

Of a number of electron microscope studies on the basilar membrane of the inner ear cochlear duct so far reported, none seems to have been conducted using PAM of R.R. staining, excellent stainings especially suited for the observation of connective tissue. In this study the basilar membrane of the cochlear duct in young and mature guinea pigs and human fetuses was examined with an electron microscope using these stainings, and obtained the interesting results described below. Fibrils of the basilar membrane, although strongly PAM-positive, all lacked periodic stripes, indicating that they were collagenous fibrils in an immature state. Young guinea pigs clearly differed from mature ones in that numerous fibroblasts were present. In human fetuses, the basilar membrane exhibited no clear fibrillar structure in the 13th week, but had PAM-positive fibrils in the 20th week. By the 23rd week, it had assumed roughly the same structure as in adults, although numerous fibroblasts were still present, and resembled the basilar membrane in young guinea pigs. The basilar membrane is a part of a unique organ, a sensory organ. Though comparison is difficult because of the extremely complicated anatomy of the organ, it is concluded that the fibrils of basilar membrane are collagenous fibrils in a peculiarly immature state, and similar to those in the cartilage and tympanic membrane.     

Effect of modulation of basilar membrane position on the cochlear microphonic

Certain characteristics of the extracellular cochlear microphonic (CM) recorded by intracochlear electrodes change in a bimodal manner as a function of prior acoustic exposure, intensity of stimulation, or stimulus frequency. In the present study, it as shown that blasing the basilar membrane position toward scala tympani serves to enhance the CM amplitude when the cochlea is unfatigued, when low-intensity stimuli are used, or when frequencies below the best frequency of a differential electrode pair are used. Conversely, after acoustic fatigue, or during high-intensity or high-frequency stimulation, the microphonic potential is enhanced by a movement of the basilar membrane toward the scala vestibuli. The two populations of hair cells, whose responses are enhanced and diminished on opposing positions of the basilar membrane, are probably outer and inner hair cells.     

Modeling rapid waveform compression on the basilar membrane as multiple-bandpass-nonlinearity filtering

Evidence has accumulated from experimental intracochlear studies that nonlinear mechanical response of the basilar membrane is responsible for cochlear frequency tuning and is the major source of extracochlear nonlinear phenomena in cochlear sound analysis. Known basilar-membrane data provide a basis for synthesizing and quantifying conceptions of cochlear signal processing derived earlier from extracochlear studies that indicated the existence of rapid waveform compression and dual signal processing. The multiple-bandpass-nonlinearity (MBNL) model represents and generalizes available measurements of basilar-membrane mechanical responses in terms of a rapid nonlinear mixing at each place of an insensitive, linearlike lowpass filter with a sensitive, compressive bandpass filter. The dual filters are associated with the tails and tips of cochlear frequency tuning curves. Simulations of published nonlinear mechanical responses of the basilar membrane and predicted correlations with auditory-nerve responses are systematically explored. Correlations between model and biophysical data suggest that the model represents a nonlinear mixing by outer hair cells of hydromechanical and electromechanical signals, and thus provides a quantitative tool for biophysical study of cochlear mechanisms.     

State of stress within the basilar membrane: a re-evaluation of the membrane misnomer

By deforming and making incisions in the basilar membrane (BM), von Békésy showed that the BM seems to behave as a thin elastic plate, rather than as a membrane. However, it has never been shown whether a traveling wave could be sustained by a prestretched material in which the tension is insufficient to cause a visible retraction of the cut edges of an incision when viewed with a light microscope. We have shown that the necessary radial tension would decrease exponentially along the cochlea, from a value of 39 ± 9 N/m at the base, with a space constant of 4.3 ± 1.1 mm, for the guinea pig. This variable tension would be produced by a constant prestretching surface force of 2.4 ± 0.1 × 10⁶ N/m², acting on the BM edges. Using values of Young's modulus in the radial direction, ranging from that of elastin to collagen, it is shown that this force would most likely cause a visible retraction of the cut edges of an incision. Therefore one must either conclude, once again, that the BM is effectively an unstretched material or question the original interpretation of the incision experiments.     

Effects of lidocaine on basilar membrane vibration in the guinea pig.

The effects of lidocaine on basilar membrane (BM) vibration and compound action potential (CAP) were studied in guinea pigs in order to elucidate the site of lidocaine action in the cochlea. BM vibration was measured with a laser Doppler vibrometer through an opening made in the lateral bony wall of the scala tympani at the basal turn. Ten min after local administration of lidocaine (250 microg) into the scala tympani, the velocity of BM vibration and the CAP amplitude decreased significantly at around the characteristic frequency of the stimulus sound (p < 0.05). The maximum decreases were 4 dB in the velocity of the BM vibration and 40 dB in the CAP amplitude. In contrast, such changes were not observed after i.v. injection of lidocaine (1.5 mg/kg). These results suggest that when lidocaine is administered locally in the cochlea it acts not only on the cochlear nerve but also on the outer hair cells.     

蜗内直流电对耳蜗基底膜振动的影响

目的探讨外加直流电流后对耳蜗基底膜振动的影响.方法在豚鼠耳蜗底回距圆窗龛缘2.4mm处开一直径约0.4mm小孔,作为测量活体基底膜的振动速度测试窗.在测试窗上、下缘的鼓阶、前庭阶各开一小孔,将铂-铱电极置入鼓阶、前庭阶作为跨蜗管的电刺激电极.用激光多普勒干涉测速仪观察直流电流对纯音诱发的基底膜振动速度的影响.结果当外加电流前庭阶极性为正,鼓阶极性为负时,可以看到基底膜振动速度显著增大,给相反极性电流时,基底膜振动速度减小.结论生理状态下的正内淋巴电位是耳蜗将声音能量转变为神经冲动的必要条件.适当提高外毛细胞顶端正电位,有助于提高耳蜗放大器的增益.外加负电位则严重影响耳蜗放大器的增益.     

Behavioural measurement of level-dependent shifts in the vibration pattern on the basilar membrane.

Physiological data suggest that the travelling wave on the basilar membrane evoked by a sinusoid of fixed frequency moves towards the base with increasing level. We describe two psychoacoustic experiments that attempted to provide evidence for and quantify the extent of such a shift in humans. In experiment 1, masking patterns were measured in forward masking using a fixed 6-kHz tone presented at 65 or 85 dB sound pressure level. The threshold for detecting a brief sinusoidal signal was measured as a function of signal frequency for several time delays of the signal relative to the end of the masker. A background noise was included to reduce 'off-frequency listening'. As the signal delay was increased, the signal level at the peaks of the masking patterns decreased and the signal frequency at the peak of the patterns moved progressively towards higher frequencies. The pattern of results was consistent with the idea of a basalward shift of the travelling wave with increasing level. The estimated shift corresponds to about 0.25 octaves for a 40-dB change in level. Experiment 2 also used forward masking. The signal was a 4-kHz tone presented at 10 dB sensation level. For three fixed masker levels (65, 85 and 95 dB), we measured the duration of the gap between the masker and signal required to give 79.4% correct detection of the signal (called the 'gap threshold') as a function of masker frequency; the longer the gap threshold, the more effective is the masker. The gap threshold patterns sometimes showed two peaks. One occurred just below the signal frequency and the frequency at the peak was hardly affected by masker level. The second peak fell at a lower frequency, and this frequency tended to decrease with increasing masker level. The gap threshold patterns tended to spread markedly towards lower frequencies with increasing masker level. The shift with level provides further evidence for a basalward spread of the travelling wave with increasing level.     

Auditory brain stem potentials recorded at different scalp locations in neonates and adults

The auditory evoked brain stem potential was recorded in 14 normal full-term infants and nine normal-hearing adults. Silver-silver chloride electrodes were placed at nasion, forehead, vertex, each mastoid over the bony prominence, and the seventh cervical vertebra (noncephalic reference) in order to study the scalp distribution of the auditory brain stem response. Large differences in the scalp distribution between the newborn and adult populations were observed. At the ipsilateral mastoid, an x wave occurring at approximately 2 ms and a y wave occurring at approximately 3.3 ms were identified in the adult; this contrasts to a y wave at approximately 3.7 ms in the neonate. It appears that there are either separate generators for some of the components in the adult versus the neonate, and/or as the nervous system matures, myelinization occurs with a concomitant change in the scalp distribution of the auditory brain stem potentials.