scholarly journals Power Amplification and Frequency Selectivity in the Inner Ear: A New Physical Model

10.5772/66542 ◽  
2017 ◽  
Author(s):  
Piotr Kielczynski
Keyword(s):  
Inner Ear ◽  
Physical Model ◽  
Frequency Selectivity ◽  
Power Amplification

Auditory and vestibular hair cell stereocilia: relationship between functionality and inner ear disease

2011 ◽  
Vol 125 (10) ◽  
pp. 991-1003 ◽  
Author(s):  
R R Ciuman
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Inner Ear ◽  
Frequency Selectivity ◽  
Cellular Structures ◽  
Hereditary Deafness ◽  
Mechanoelectrical Transduction ◽  
Cochlear Amplification ◽  
Inner Ear Disease ◽  
Syndromic Hearing Loss

AbstractThe stereocilia of the inner ear are unique cellular structures which correlate anatomically with distinct cochlear functions, including mechanoelectrical transduction, cochlear amplification, adaptation, frequency selectivity and tuning. Their function is impaired by inner ear stressors, by various types of hereditary deafness, syndromic hearing loss and inner ear disease (e.g. Ménière's disease). The anatomical and physiological characteristics of stereocilia are discussed in relation to inner ear malfunctions.

scholarly journals Static length changes of cochlear outer hair cells can tune low-frequency hearing

2017 ◽  
Author(s):  
Nikola Ciganović ◽  
Rebecca L. Warren ◽  
Batu Keçeli ◽  
Stefan Jacob ◽  
Anders Fridberger ◽  
...  
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Outer Hair Cells ◽  
Frequency Selectivity ◽  
Apical Region ◽  
Low Frequencies ◽  
Inner Hair Cells ◽  
Length Changes ◽  
The Brain

AbstractThe cochlea not only transduces sound-induced vibration into neural spikes, it also amplifies weak sound to boost its detection. Actuators of this active process are sensory outer hair cells in the organ of Corti, whereas the inner hair cells transduce the resulting motion into electric signals that propagate via the auditory nerve to the brain. However, how the outer hair cells modulate the stimulus to the inner hair cells remains unclear. Here, we combine theoretical modeling and experimental measurements near the cochlear apex to study the way in which length changes of the outer hair cells deform the organ of Corti. We develop a geometry-based kinematic model of the apical organ of Corti that reproduces salient, yet counter-intuitive features of the organ’s motion. Our analysis further uncovers a mechanism by which a static length change of the outer hair cells can sensitively tune the signal transmitted to the sensory inner hair cells. When the outer hair cells are in an elongated state, stimulation of inner hair cells is largely inhibited, whereas outer hair cell contraction leads to a substantial enhancement of sound-evoked motion near the hair bundles. This novel mechanism for regulating the sensitivity of the hearing organ applies to the low frequencies that are most important for the perception of speech and music. We suggest that the proposed mechanism might underlie frequency discrimination at low auditory frequencies, as well as our ability to selectively attend auditory signals in noisy surroundings.Author summaryOuter hair cells are highly specialized force producers inside the inner ear: they can change length when stimulated electrically. However, how exactly this electromotile effect contributes to the astonishing sensitivity and frequency selectivity of the inner ear has remained unclear. Here we show for the first time that static length changes of outer hair cells can sensitively regulate how much of a sound signal is passed on to the inner hair cells that forward the signal to the brain. Our analysis holds for the apical region of the inner ear that is responsible for detecting the low frequencies that matter most in speech and music. This shows a mechanisms for how frequency-selectivity can be achieved at low frequencies. It also opens a path for the efferent neural system to regulate hearing sensitivity.

Frequency Selectivity of Central Auditory Neurons Without Inner Ear

1993 ◽  
Vol 113 (3) ◽  
pp. 266-270 ◽  
Author(s):  
Dietrich W. F. Schwarz ◽  
Attila Dezsö ◽  
Peter R. Neufeld
Keyword(s):  
Inner Ear ◽  
Frequency Selectivity ◽  
Auditory Neurons ◽  
Central Auditory Neurons

scholarly journals Hypobaric pressure exposure effects on cochlear frequency selectivity in fluctuating, low-frequency hearing loss

2009 ◽  
Vol 123 (7) ◽  
pp. 710-717
Author(s):  
K J Brännström ◽  
J Grenner
Keyword(s):  
Hearing Loss ◽  
Speech Recognition ◽  
Inner Ear ◽  
Otoacoustic Emissions ◽  
Tuning Curve ◽  
Low Frequency ◽  
Frequency Selectivity ◽  
Pressure Chamber ◽  
Positive Pressure ◽  
Tuning Curves

AbstractAim:To study the effects of hypobaric pressure chamber exposure on the cochlear frequency selectivity of subjects with monaural, fluctuating, low-frequency hearing loss, such as occurs in Ménière's disease.Methods:We used a hypobaric pressure chamber to create relative underpressure in the ear canal, in order to impose positive pressure gradients on the inner ear. Psychophysical tuning curves, transiently evoked otoacoustic emissions and speech recognition scores in noise were measured in 10 subjects with fluctuating, low-frequency hearing loss, before and after pressure exposure.Results:After the exposure, subjects’ overall pure tone averages showed no improvement, but individual results showed improved speech recognition scores in noise (six subjects), increased transiently evoked otoacoustic emission strength (three subjects) and increased psychophysical tuning curve steepness (two subjects). Deteriorations were also seen, mainly in psychophysical tuning curves. No association could be established between the different tests, and the measured parameters could not predict subjective improvement.Conclusion:The results suggest variable effects of hypobaric pressure exposure on inner-ear physiology.

Otoconia formation in the chick embryo

1983 ◽  
Vol 41 ◽  
pp. 572-573
Author(s):  
C.D. Fermin ◽  
M. Igarashi
Keyword(s):  
Chick Embryo ◽  
Inner Ear ◽  
Gallus Domesticus ◽  
The Body ◽  
Abnormal Behavior ◽  
Intensive Study ◽  
Basic Fuchsin ◽  
Gestational Period ◽  
Sensory Epithelia ◽  
Transmission Electron

Otoconia are microscopic geometric structures that cover the sensory epithelia of the utricle and saccule (gravitational receptors) of mammals, and the lagena macula of birds. The importance of otoconia for maintanance of the body balance is evidenced by the abnormal behavior of species with genetic defects of otolith. Although a few reports have dealt with otoconia formation, some basic questions remain unanswered. The chick embryo is desirable for studying otoconial formation because its inner ear structures are easily accessible, and its gestational period is short (21 days of incubation).The results described here are part of an intensive study intended to examine the morphogenesis of the otoconia in the chick embryo (Gallus- domesticus) inner ear. We used chick embryos from the 4th day of incubation until hatching, and examined the specimens with light (LM) and transmission electron microscopy (TEM). The embryos were decapitated, and fixed by immersion with 3% cold glutaraldehyde. The ears and their parts were dissected out under the microscope; no decalcification was used. For LM, the ears were embedded in JB-4 plastic, cut serially at 5 micra and stained with 0.2% toluidine blue and 0.1% basic fuchsin in 25% alcohol.

Control of the Microcirculation of the Inner Ear

1975 ◽  
Vol 8 (2) ◽  
pp. 455-466 ◽  
Author(s):  
James B. Snow ◽  
Fumiro Suga
Keyword(s):  
Inner Ear
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