Neuroanatomy of the Cochlea

Spoendlin, H.

doi:10.1007/978-3-642-65902-7_2

Cited by 44 publications

(10 citation statements)

References 16 publications

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“…Y. Ota and R. S. Kimura the range of individual differences. These figures are strikingly similar to those of the cat before section of the efferent nerve fibers (Spoendlin, 1974) and our own study on the normal squirrel monkey (Kimura, 1978). Thus the same distribution pattern holds in the human as in animals; however, termination of dendritic processes of the neurons remains to be determined in the human.…”

Section: Discussionsupporting

confidence: 86%

“…In the cat large unmyelinated neurons were not normally present and were only seen in pathological specimens in which the myelinated type was converted into the unmyelinated type (Spoendlin, 1974). Although large unmyelinated neurons were often observed in the hydropic inner ear of the guinea pig (Kimura, unpublished data), degenerative changes were not always associated with the loss of myelin sheath.…”

Section: Discussionmentioning

confidence: 99%

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Ultrastructural Study of the Human Spiral Ganglion

Ota

Kimura

1980

Acta Oto-Laryngologica

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Electron microscopic study of the human spiral ganglion was conducted on 17 ears from 12 individuals aged 9 months to 92 years. Two types of neurons, large and small, with distinct cytological characteristics were found. Both types of neurons were myelinated and unmyelinated; however, a majority of the population was unmyelinated (94%). The distribution of myelinated neurons varied greatly among individuals, though a slight increase in their population was noted in aged individuals, the highest count being 28% in a specimen from an individual 75 years old. The small neurons constituted 6% of the population, and their cytoplasms were highly filamentous in both myelinated and unmyelinated types. The findings of this study provide no evidence as to the functional significance of the myelination of spiral ganglion cells.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Ultrastructural Study of the Human Spiral Ganglion

Ota

Kimura

1980

Acta Oto-Laryngologica

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“…The giant fiber ( fig. 2) at the base of an inner hair cell demonstrating myelin figures and neurofi brillary degeneration was very similar to that previously described by Spoendlin [21,22] in experimentally induced retrograde degen eration of the cochlear nerve, to the degener ative pattern observed by electron micros copy in the organ of Corti of hereditary deaf ness in the cat [23], and to other examples of degenerating nerve fibers [24,25].…”

Section: Usher's Syndromesupporting

confidence: 84%

Innervation Densities of Inner and Outer Hair Cells of the Human Organ of Corti

Nadol

1988

ORL

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The innervation densities, i.e. the number of afferent endings per inner and outer hair cell, number of synaptic specializations per inner hair cell and the number of efferent endings per outer hair cell, were evaluated by serial section electron microscopy in the normal human inner ear and a case of Usher’s syndrome (retinitis pigmentosa and sen-sorineural hearing loss). There was a significant decrease in the innervation density in Usher’s syndrome as compared to normative controls, which could not be explained by the decrease in density of spiral ganglion cells. This was interpreted as suggesting a decrease in the number of neural processes and endings within the dendritic arborization of remaining spiral ganglion cells in this disorder.

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“…(Merzenich etal., 1973). It can be argued that type I neurons, presumably associated with the inner hair cells, will degenerate with the 'loss of their hair cells (Spoendlin, 1974). However, examinations of the temporal bones of implanted cats from 6 weeks to over a year after electrode implantation indicated that while cochlear implants result in the loss of cochlear hair cells and of some supporting cells in the basal cochlea• the spiral ganglion appeared normal, (Merzenich et al, 1973.…”

Section: The Data Available On Human Subjects With Implanted Eiectr0desmentioning

confidence: 99%

Uncertainty concerning the direct use of time information in hearing: Place clues in white-spectra stimuli

Pierce

Lipes

Cheetham

1977

The Journal of the Acoustical Society of America

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Data on time response in the nervous system are available for animals. Rate-matching data for humam ,,ubject,, with implanted electrodes are available. These data do not tell us with certainty up to what rate people with normal hearing utilize time information directly. In many experiments an attempt to measure time re,,ponse is confused by the presence of spectral clues. Short-term spectral clues exist in stochastic •,½qu½.cc•, of positive and negative pulses and in modulated white noise, both of which have a white longterm •,p½ctrum. These clues are periodicity (with a period equal to the pulse or modulation rate) and •,ymmctry (about frequencies equal to integer multiples of half this rate), differences at different frequencies in' the peak-or rrns-voltage distribution function of the output of a narrow-band filter and, in the case of ,,rochaslit pulse sequences, differences in extreme intensity at different frequencies. It may be that the ability to match at high rates and the perception of tonal quality that subjects with excellent and trained hcari.g, such a•, musicians, exhibit for white-spectrum stochastic pulse sequences or gated noise is due to the re•,idue phenomenon or to spectral clues discussed in this paper. I'ACS numbers' 43.66.Mk, 43.66.Ba, 43.66.Lj INTRODUCTION In animal hearing direct measurements can be made of the firing of neurons in response to sine waves or pulse trains of various frequencies or rates. Histograms of firings show that statistical synchrony of firings with stimuli is preserved in the eighth nerve up to stimulus frequencies of about 4000-5000 Hz (Rupert, Moushegian, and Galambos, 1963; Peake, Kiang, and Goldstein, 1962; Rose etal., 1967). However, it is not clear up to what repetition rate animals make any use of time information. 1 Neurophysiological data on synchrony in firing are not available for human beings. However, electrodes have been implanted in totally deaf patients who exhibit function of the eighth nerve. These give a partial restoration of hearing through electrical stimulation. In such subjects, all neurons are stimulated by the same signal and any ability to distinguish among stimuli must be based on time information.Tests on a patient with six electrodes permanently implanted in the modiolus portion of the eighth nerve by F. Blair Simmons in 1964 showed an ability to discriminate pulse rates up to 300 pulses per second and an ability to discriminate two short pulses from a single pulse when the interval was increased and when the pulses were separated by more than 5 msec. (Simmons etal. , 1965.) Michelson and his associates have reported on the responses of four patients implanted with intracochlear stimulating electrodes. Prior to implant, the hearing of the ear later implanted had deteriorated to total deafness in three of the patients; in the other, the implanted ear had been deaf from birth (Michelson, 1971). The apparent pitch reported by three subjects rose steadily with increasing frequency to about 500 Hz. At higher frequencies the "tones" heard ...

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Neuroanatomy of the Cochlea

Cited by 44 publications

References 16 publications

Ultrastructural Study of the Human Spiral Ganglion

Ultrastructural Study of the Human Spiral Ganglion

Innervation Densities of Inner and Outer Hair Cells of the Human Organ of Corti

Uncertainty concerning the direct use of time information in hearing: Place clues in white-spectra stimuli

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