Quantitative analysis of the innervation of the chicken basilar papilla

Fischer, Franz Peter

doi:10.1016/0378-5955(92)90048-r

Cited by 136 publications

(93 citation statements)

References 29 publications

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“…In contrast, I A decreases in amplitude across the width of the distal half of the cochlea, where there is a gradient from short to tall hair cells, and is absent from the most distal regions, where tall hair cells dominate (Murrow, 1994). Interestingly, short hair cells are innervated by large caliciform efferent endings (Tanaka and Smith, 1978;Fischer, 1992), suggesting a role similar to that of mammalian outer hair cells, which regulate cochlear tuning. Although A-channels are found throughout much of the chick cochlea, little is known about their function or structure.…”

Section: Introductionmentioning

confidence: 86%

“…Immunostaining revealed that protein expression was clustered toward the apical ridge on one side of the hair cell. This clustering is outside the afferent and efferent synaptic zones (Fischer, 1992), thereby placing these channels outside the sphere of direct junctional activity; however, they are in a suitable location for modulating electrical signals originating at the efferent terminals and the transduction site, the stereocilia. Additionally, A-channel transcription and protein expression occurred in the soma of the cochlear ganglion cells.…”

Section: Discussionmentioning

confidence: 99%

“…The striking aspect of the short hair cells is that they are innervated only by efferents (Fischer 1992). A-channels conduct the largest fast-activating current, yet remain in an inactivated state at the average resting potential (Ϫ46 mV) of short hair cells (Murrow, 1994).…”

Section: Discussionmentioning

confidence: 99%

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Identification and Localization of an Arachidonic Acid-Sensitive Potassium Channel in the Cochlea

Sokolowski¹,

Sakai²,

Harvey³

et al. 2004

J. Neurosci.

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Receptor cells of the auditory and vestibular end organs of vertebrates acquire various types of potassium channels during development. Their expression and kinetics can differ along the tonotopic axis as well as in different cell types of the sensory epithelium. These variations can play a crucial role in modulating sensory transduction and cochlear tuning. Whole-cell tight-seal recordings of isolated hair cells revealed the presence of an arachidonic acid-sensitive A-type channel in the short (outer) hair cells of the chicken cochlea. This polyunsaturated fatty acid blocked the A-current, thereby increasing the amplitude and duration of the voltage response in these cells. We identified the gene encoding this channel as belonging to a member of the Shal subfamily, Kv4.2. Expression of the recombinant channel shows half-activation and inactivation potentials shifted to more positive values relative to native channels, suggesting that the native channel is coexpressed with an accessory subunit. RT-PCR revealed that transcription begins early in development, whereas in situ hybridization showed mRNA expression limited to the intermediate and short hair cells located in specific regions of the adult cochlea. Additional localization, using immunofluorescent staining, revealed clustering in apical-lateral regions of the receptor cell as well as in the cochlear ganglion. These experiments provide evidence that in addition to membrane proteins modulating excitation in these receptor cells, fatty acids contribute to the coding of auditory stimuli via these channels.

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Section: Introductionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

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Identification and Localization of an Arachidonic Acid-Sensitive Potassium Channel in the Cochlea

Sokolowski¹,

Sakai²,

Harvey³

et al. 2004

J. Neurosci.

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“…The reserve pool appears to be released at a constant rate of about 10,000 vesicles/s . Because the typical tall hair cell divides its output between two synapses (Fischer 1992), the rate at which each afferent receives neurotransmitter is expected to be about half these values. Basal hair cells have seemingly more variability in their number of afferent contacts than apical hair cells (Fischer 1992), so this perhaps accounts for the increased scattering of firing rates and phasic component sizes in the high CF units (Fig.…”

Section: Adaptation Across the Tonotopic Axis Of The Basilar Papillamentioning

confidence: 99%

Tonotopic Distribution of Short-Term Adaptation Properties in the Cochlear Nerve of Normal and Acoustically Overexposed Chicks

Crumling

Saunders

2007

JARO

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Cochlear nerve adaptation is thought to result, at least partially, from the depletion of neurotransmitter stores in hair cells. Recently, neurotransmitter vesicle pools have been identified in chick tall hair cells that might play a role in adaptation. In order to understand better the relationship between adaptation and neurotransmitter release dynamics, short-term adaptation was characterized by using peristimulus time histograms of single-unit activity in the chick cochlear nerve. The adaptation function resulting from 100-ms pure tone stimuli presented at the characteristic frequency, +20 dB relative to threshold, was well described as a single exponential decay process with an average time constant of 18.6 T 0.8 ms (mean T SEM). The number of spikes contributed by the adapting part of the response increased tonotopically for characteristic frequencies up to õ0.8 kHz. Comparison of the adaptation data with known physiological and anatomical hair cell properties suggests that depletion of the readily releasable pool is the basis of short-term adaptation in the chick. With this idea in mind, short-term adaptation was used as a proxy for assessing tall hair cell synaptic function following intense acoustic stimulation. After 48 h of exposure to an intense pure tone, the time constant of short-term adaptation was unaltered, whereas the number of spikes in the adapting component was increased at characteristic frequencies at and above the exposure frequency. These data suggest that the rate of readily releasable pool emptying is unaltered, but the neurotransmitter content of the pool is increased, by exposure to intense sound. The results imply that an increase in readily releasable pool size might be a compensatory mechanism ensuring the strength of the hair cell afferent synapse in the face of ongoing acoustic stress.

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“…3, Smith, 1985). However, the bird cochlea does have a population of "inner" and "outer" hair cells that function similar to those in the mammal and are connected to afferent and efferent nerve fibers in a pattern quite similar to that of mammals (Fischer, 1992). The hair cells are arranged in a mosaic pattern, rather than four discrete rows, but the entire sensory epithelium exhibits a similar tonotopic organization to that seen in the mammalian organ of Corti.…”

Section: The Avian Cochleamentioning

confidence: 86%

Genetic and pharmacological intervention for treatment/prevention of hearing loss

Cotanche

2008

Journal of Communication Disorders

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Twenty years ago it was first demonstrated that birds could regenerate their cochlear hair cells following noise damage or aminoglycoside treatment. An understanding of how this structural and functional regeneration occurred might lead to the development of therapies for treatment of sensorineural hearing loss in humans. Recent experiments have demonstrated that noise exposure and aminoglycoside treatment lead to apoptosis of the hair cells. In birds, this programmed cell death induces the adjacent supporting cells to undergo regeneration to replace the lost hair cells. Although hair cells in the mammalian cochlea undergo apoptosis in response to noise damage and ototoxic drug treatment, the supporting cells do not possess the ability to undergo regeneration. However, current experiments on genetic manipulation, gene therapy, and stem cell transplantation suggest that regeneration in the mammalian cochlea may eventually be possible and may 1 day provide a therapeutic tool for hearing loss in humans.Learning outcomes-The reader should be able to: (1) Describe the anatomy of the avian and mammalian cochlea, identify the individual cell types in the organ of Corti, and distinguish major features that participate in hearing function, (2) Demonstrate a knowledge of how sound damage and aminoglycoside poisoning induce apoptosis of hair cells in the cochlea, (3) Define how hair cell loss in the avian cochlea leads to regeneration of new hair cells and distinguish this from the mammalian cochlea where there is no regeneration following damage, and (4) Interpret the potential for new approaches, such as genetic manipulation, gene therapy and stem cell transplantation, could provide a therapeutic approach to hair cell loss in the mammalian cochlea.

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Quantitative analysis of the innervation of the chicken basilar papilla

Cited by 136 publications

References 29 publications

Identification and Localization of an Arachidonic Acid-Sensitive Potassium Channel in the Cochlea

Identification and Localization of an Arachidonic Acid-Sensitive Potassium Channel in the Cochlea

Tonotopic Distribution of Short-Term Adaptation Properties in the Cochlear Nerve of Normal and Acoustically Overexposed Chicks

Genetic and pharmacological intervention for treatment/prevention of hearing loss

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