Human otoacoustic emissions generated by active outer hair cells

2013 ◽  
Author(s):  
Reinhart Frosch
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Outer Hair Cells

scholarly journals Overexpression of SK2 Channels Enhances Efferent Suppression of Cochlear Responses Without Enhancing Noise Resistance

2007 ◽  
Vol 97 (4) ◽  
pp. 2930-2936 ◽  
Author(s):  
Stéphane F. Maison ◽  
Lisan L. Parker ◽  
Lucy Young ◽  
John P. Adelman ◽  
Jian Zuo ◽  
...  
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Outer Hair Cell ◽  
Outer Hair Cells ◽  
Sk Channels ◽  
Cochlear Function ◽  
Cochlear Hair Cells ◽  
Efferent Suppression

Cochlear hair cells express SK2, a small-conductance Ca2+-activated K+ channel thought to act in concert with Ca2+-permeable nicotinic acetylcholine receptors (nAChRs) α9 and α10 in mediating suppressive effects of the olivocochlear efferent innervation. To probe the in vivo role of SK2 channels in hearing, we examined gene expression, cochlear function, efferent suppression, and noise vulnerability in mice overexpressing SK2 channels. Cochlear thresholds, as measured by auditory brain stem responses and otoacoustic emissions, were normal in overexpressers as was overall cochlear morphology and the size, number, and distribution of efferent terminals on outer hair cells. Cochlear expression levels of SK2 channels were elevated eightfold without striking changes in other SK channels or in the α9/α10 nAChRs. Shock-evoked efferent suppression of cochlear responses was significantly enhanced in overexpresser mice as seen previously in α9 overexpresser mice; however, in contrast to α9 overexpressers, SK2 overexpressers were not protected from acoustic injury. Results suggest that efferent-mediated cochlear protection is mediated by other downstream effects of ACh-mediated Ca2+ entry different from those involving SK2-mediated hyperpolarization and the associated reduction in outer hair cell electromotility.

scholarly journals The Role of Prestin in the Generation of Electrically Evoked Otoacoustic Emissions in Mice

2008 ◽  
Vol 99 (4) ◽  
pp. 1607-1615 ◽  
Author(s):  
Markus Drexl ◽  
Marcia M. Mellado Lagarde ◽  
Jian Zuo ◽  
Andrei N. Lukashkin ◽  
Ian J. Russell
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Temporal Structure ◽  
Organ Of Corti ◽  
Outer Hair Cells ◽  
Tectorial Membrane ◽  
Wild Type ◽  
Short Delay ◽  
Delay Component

Electrically evoked otoacoustic emissions are sounds emitted from the inner ear when alternating current is injected into the cochlea. Their temporal structure consists of short- and long-delay components and they have been attributed to the motile responses of the sensory-motor outer hair cells of the cochlea. The nature of these motile responses is unresolved and may depend on either somatic motility, hair bundle motility, or both. The short-delay component persists after almost complete elimination of outer hair cells. Outer hair cells are thus not the sole generators of electrically evoked otoacoustic emissions. We used prestin knockout mice, in which the motor protein prestin is absent from the lateral walls of outer hair cells, and Tecta ΔENT/ΔENT mice, in which the tectorial membrane, a structure with which the hair bundles of outer hair cells normally interact, is vestigial and completely detached from the organ of Corti. The amplitudes and delay spectra of electrically evoked otoacoustic emissions from Tecta ΔENT/ΔENT and Tecta +/+ mice are very similar. In comparison with prestin +/+ mice, however, the short-delay component of the emission in prestin −/− mice is dramatically reduced and the long-delay component is completely absent. Emissions are completely suppressed in wild-type and Tecta ΔENT/ΔENT mice at low stimulus levels, when prestin-based motility is blocked by salicylate. We conclude that near threshold, the emissions are generated by prestin-based somatic motility.

scholarly journals Amplification lags nonlinearity in the recovery from reduced endocochlear potential

2020 ◽  
Author(s):  
C. Elliott Strimbu ◽  
Yi Wang ◽  
Elizabeth S. Olson
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Basilar Membrane ◽  
Frequency Tuning ◽  
Organ Of Corti ◽  
Endocochlear Potential ◽  
Outer Hair Cells ◽  
Frequency Resolution ◽  
Operating Condition ◽  
Distortion Product

ABSTRACTThe mammalian hearing organ, the cochlea, contains an active amplifier to boost the vibrational response to low level sounds. Hallmarks of this active process are sharp location-dependent frequency tuning and compressive nonlinearity over a wide stimulus range. The amplifier relies on outer hair cell (OHC) generated forces driven in part by the endocochlear potential (EP), the ~ +80 mV potential maintained in scala media, generated by the stria vascularis. We transiently eliminated the EP in vivo by an intravenous injection of furosemide and measured the vibrations of different layers in the cochlea’s organ of Corti using optical coherence tomography. Distortion product otoacoustic emissions (DPOAE) were monitored at the same times. Following the injection, the vibrations of the basilar membrane lost the best frequency (BF) peak and showed broad tuning similar to a passive cochlea. The intra-organ of Corti vibrations measured in the region of the OHCs lost their BF peak and showed low-pass responses, but retained nonlinearity, indicating that OHC electromotility was still operational. Thus, while electromotility is presumably necessary for amplification, its presence is not sufficient for amplification. The BF peak recovered nearly fully within 2 hours, along with a non-monotonic DPOAE recovery that suggests that physical shifts in operating condition are a final step in the recovery process.SIGNIFICANCEThe endocochlear potential, the +80 mV potential difference across the fluid filled compartments of the cochlea, is essential for normal mechanoelectrical transduction, which leads to receptor potentials in the sensory hair cells when they vibrate in response to sound. Intracochlear vibrations are boosted tremendously by an active nonlinear feedback process that endows the cochlea with its healthy sensitivity and frequency resolution. When the endocochlear potential was reduced by an injection of furosemide, the basilar membrane vibrations resembled those of a passive cochlea, with broad tuning and linear scaling. The vibrations in the region of the outer hair cells also lost the tuned peak, but retained nonlinearity at frequencies below the peak, and these sub-BF responses recovered fairly rapidly. Vibration responses at the peak recovered nearly fully over 2 hours. The staged vibration recovery and a similarly staged DPOAE recovery suggests that physical shifts in operating condition are a final step in the process of cochlear recovery.

scholarly journals Electroacoustic and electrophysiological auditory assessment in aphasic individuals

Revista CEFAC ◽  
2020 ◽  
Vol 22 (2) ◽  
Author(s):  
Ana Karina Lima Buriti ◽  
Lilian Aguiar de Mello ◽  
Bruna de Souza Pedroso Machado ◽  
Daniela Gil
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Tone Burst ◽  
Outer Hair Cells ◽  
Auditory Pathways ◽  
Suppression Effect ◽  
Speech Stimuli ◽  
Olivocochlear System ◽  
Significant Difference ◽  
The Mean

ABSTRACT Purpose: to verify the functioning of the outer hair cells and the medial efferent olivocochlear system, and the integrity of the auditory pathways in the brainstem up to the auditory cortex, in aphasic individuals. Methods: the sample comprised 20 individuals - 10 without aphasia and 10 with it, aged from 21 to 58 years. The procedures used were the research of the otoacoustic emissions by a transient stimulus with and without noise, and the cognitive potential (tone-burst and speech stimuli). The findings were analyzed based on descriptive statistics. Results: the suppression effect was more present in individuals without aphasia when compared with the aphasic ones. In the cognitive potential, the mean latency values of P3 was within normality standards, with a higher latency in the individuals presented with aphasia for the tone-burst stimulus in both ears. A statistically significant difference of the P3-N2 amplitude was observed for the tone-burst stimulus, comparing the ears in both groups, and for speech stimulus only to the left ear in both groups. Conclusions: aphasic individuals did not present significant differences regarding suppression of the otoacoustic emissions. As for the cognitive potential, the aphasic individuals presented higher latency values when compared to those with no aphasia.

scholarly journals Effect of selective damage to cochlear outer hair cells on alternating current induced otoacoustic emissions.

1992 ◽  
Vol 13 (4) ◽  
pp. 231-240
Author(s):  
Tomoo Homma ◽  
Yutaka Hosokawa ◽  
Toshio Moriyama ◽  
Keiichi Murata
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Alternating Current ◽  
Outer Hair Cells

Otoacoustic Emissions in an Adult With Severe Hearing Loss

1991 ◽  
Vol 34 (2) ◽  
pp. 379-385 ◽  
Author(s):  
Beth A. Prieve ◽  
Michael P. Gorga ◽  
Stephen T. Neely
Keyword(s):  
Hearing Loss ◽  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Outer Hair Cells ◽  
Unexpected Finding ◽  
Inner Hair Cell ◽  
Neural Damage ◽  
The Subject ◽  
Bilateral Sensorineural Hearing Loss ◽  
The Right

The present study describes the unexpected finding of evoked otoacoustic emissions (EOAEs) from the left ear of a subject with severe-to-profound bilateral sensorineural hearing loss. No EOAEs could be measured from the right ear. To ensure that the EOAEs were not artifacts, two different instrumentation systems were used and both provided similar results. It is suggested that the subject may have a group of surviving outer hair cells in some regions of her left cochlea with corresponding inner hair cell or neural damage.

scholarly journals Modulation of Cochlear Afferent Response by the Lateral Olivocochlear System: Activation Via Electrical Stimulation of the Inferior Colliculus

2003 ◽  
Vol 90 (5) ◽  
pp. 3178-3200 ◽  
Author(s):  
J. Alan Groff ◽  
M. Charles Liberman
Keyword(s):  
Inferior Colliculus ◽  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Round Window ◽  
Acoustic Stimulus ◽  
Outer Hair Cells ◽  
Olivocochlear System ◽  
Compound Action Potentials ◽  
The Face ◽  
Afferent Response

The olivocochlear (OC) efferent innervation of the mammalian inner ear consists of two subdivisions, medial (MOC) and lateral (LOC), with different peripheral terminations on outer hair cells and cochlear afferent terminals, respectively. The cochlear effects of electrically activating MOC efferents are well known, i.e., response suppression effected by reducing outer hair cells' contribution to cochlear amplification. LOC peripheral effects are unknown, because their unmyelinated axons are difficult to electrically stimulate. Here, stimulating electrodes are placed in the inferior colliculus (IC) to indirectly activate the LOC system, while recording cochlear responses bilaterally from anesthetized guinea pigs. Shocks at some IC sites produced novel cochlear effects attributable to activation of the LOC system: long-lasting (5–20 min) enhancement or suppression of cochlear neural responses (compound action potentials and round window noise), without changes in cochlear responses dominated by outer hair cells (otoacoustic emissions and cochlear microphonics). These novel effects also differed from classic MOC effects in their lack of dependence on the level and frequency of the acoustic stimulus. These effects disappeared on sectioning the entire OC bundle, but not after selective lesioning of the MOC tracts or the cochlea's autonomic innervation. We conclude that the LOC pathway comprises two functional subdivisions, capable of inducing slow increases or decreases in response magnitudes in the auditory nerve. Such a system may be useful in maintaining accurate binaural comparisons necessary for sound localization in the face of slow changes in interaural sensitivity.

scholarly journals Estimation of outer hair cells function in chronic bilateral tinnitus patients with normal hearing using distortion product otoacoustic emissions

2021 ◽  
Author(s):  
Aras Karimiani ◽  
Nematollah Rouhbakhsh ◽  
Farzaneh Zamiri Abdollahi ◽  
Shohreh Jalaie
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Normal Hearing ◽  
Outer Hair Cells ◽  
Distortion Product Otoacoustic Emissions ◽  
Control Group ◽  
Distortion Product Otoacoustic Emission ◽  
Frequency Range ◽  
Cochlear Function ◽  
Distortion Product

Background and Aim: It is not clear if the measurement of distortion product otoacoustic emissions (DPOAE) at frequencies above 8 kHz adds any value in determining the differences in the cochlear function between patients with and without tinnitus. This study aimed to compare DPOAE in the frequency range of 0.5−10 kHz in patients with normal hearing with and without tinnitus. Methods: This comparative cross-sectional study was conducted on 20 individuals with tinnitus and normal hearing as a study group (SG) and a control group (CG) of 20 normal-hearing individuals without tinnitus. The DPOAE was measured with F1/F2 = 1.22 and intensities of F1 = 65 dB SPL and F2 =55 dB SPL in the frequency range of 0.5−10 kHz, moreover in the frequency of tinnitus in SG and corresponding frequency in CG. Results: DPOAE level at 10 kHz did not differ significantly between SG and CG (p = 0.491). However, the mean of overall DPOAE level, DPOAE level at the frequency of tinnitus, and F2 values of 2.5, 5, and 6.298 kHz were significantly lower in SG than CG (p < 0.05). Conclusion: Measurement of DPOAE at 10 kHz did not seem to add any value in determining the differences in the cochlear function between patients with and without tinnitus. However, decreased DPOAE levels at 2.5, 5, and 6.298 kHz which were observed among patients who have tinnitus and normal hearing, indicates some outer hair cells damage that was not detectable by conventional audiometry. Keywords: Tinnitus; normal hearing; outer hair cell; distortion product otoacoustic emission

scholarly journals THE STUDY OF MATURATION OF THE AUDITORY ANALYZER RABBIT ACCORDING DISTORTION-PRODUCT OTOACOUSTIC EMISSIONS

2013 ◽  
Vol 68 (11) ◽  
pp. 94-97
Author(s):  
I. N. D'yakonova ◽  
Yu. S. Ishanova ◽  
I. V. Rakhmanova
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Normative Data ◽  
Outer Hair Cell ◽  
Rabbit Model ◽  
Outer Hair Cells ◽  
Distortion Product Otoacoustic Emissions ◽  
Acoustic Response ◽  
Auditory Analyzer ◽  
Distortion Product

Aim: In our chronic experiment to  register changes of acoustic response of Distortion-Product Otoacoustic Emissions (DPOAE) of intact rabbits in postnatal ontogenesis for the purpose of getting normative data which can be used for studying impact of pathological factors on auditory function and maturation of activity of outer hair cell in ontogenesis. Materials and methods: Study of otoacoustic emissions used mature chinchilla rabbits with a 19 day life of up to 3 months. Results: in the course of ripening were obtained functional activity of outer hair cells of the cochlea. Conclusion: normative data obtained allow us to study using a rabbit model, the pathological effects of agents on the maturation of the outer hair cells of the cochlea in the experiment.

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