Age-related changes in cochleas of mongolian gerbils

Tarnowski, Betty I.; Schmiedt, Richard A.; Hellstrom, Lisa I.; Lee, F.S.; Adams, Joe C.

doi:10.1016/0378-5955(91)90142-v

Cited by 113 publications

(74 citation statements)

References 38 publications

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“…Variances are not shown. These derived values are also compared with previous determinations of the frequency-place relationship for the adult gerbil by Mu ë ller (1996) and Tarnowski et al (1991), and for 18 day olds by Mu ë ller (1996). The latter ¢t is based on only seven data points, however.…”

Section: Conversion From Frequency To Placementioning

confidence: 82%

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Development of the base of the cochlea: place code shift in the gerbil

Mills

Rubel

1998

Hearing Research

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Distortion product otoacoustic emission measurements were made at 1/12 octave intervals before and after the injection of furosemide in gerbils aged 15 days after birth to adult, in order to obtain estimates of cochlear amplifier gain as a function of stimulus frequency. The frequency at which the gains went sharply to zero, defined as the`base cutoff frequency', increased from about 20 kHz to over 50 kHz during development. This increase provides further confirmation of the hypothesis that the place code changes during development in the basal part of the cochlea. If the measured base cutoff frequency is identified with the characteristic frequency at the basal end of the cochlea, as defined by electrophysiological measures, then these emission data can be used to generate a frequency-place map as a function of age. The derived place code shift is consistent with published electrophysiological measures, and can be used to extend these measures. Near the base cutoff frequency, the observed cochlear amplifier gain typically dropped sharply from a relative maximum to zero, over a distance of about a half octave. Specifically, this distance appeared to exhibit a curvilinear variation with age, reaching a maximum of 3/4 of an octave at 19^21 days. After transforming from frequency to place using the map derived from emissions, however, the distance between the extreme base and the place associated with the peak gain decreased monotonically from about 1.2 mm at age 15^19 days to 0.6 mm at maturity. This distance is assumed to be characteristic of the length of the active amplification zone for the cochlear amplifier in the base region. Over the same time period, there was approximately a doubling of the rate of amplification with distance from the base, so that the cochlear amplifier gain at the peak actually changed very little from 15 days to adult. z 1998 Published by Elsevier Science B.V. All rights reserved.

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Section: Conversion From Frequency To Placementioning

confidence: 82%

“…The curves from Mu ë ller (1996) are the published least square ¢ts to the traced neurons. The Tarnowski et al (1991) relationship is placed using a total length of 11.1 mm (Mu ë ller, 1996). For clarity, error bars are not shown; for the emission data, these may be obtained from the f display in Fig.…”

Section: Discussionmentioning

confidence: 99%

Development of the base of the cochlea: place code shift in the gerbil

Mills

Rubel

1998

Hearing Research

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“…At frequencies below 2 kHz, the thresholds were similar to those from the 36-month-old group. The increased threshold shift at low frequencies seen in the older group is probably due to the increased outer hair cell loss in the apex seen in these very old animals (Tarnowski et al 1991). EP values and CAP threshold profiles across frequency seen in gerbil ears exposed to furosemide for 7 days closely resemble those in quiet-aged gerbils, thereby forming the basis of the furosemide model of age-related hearing loss Schmiedt 2009).…”

Section: Cochlear Adaptation To Chronic-furosemide Treatment In Youngmentioning

confidence: 91%

Chronic Reduction of Endocochlear Potential Reduces Auditory Nerve Activity: Further Confirmation of an Animal Model of Metabolic Presbyacusis

Lang

Jyothi

Smythe

et al. 2010

JARO

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Gerbils aged in quiet show a decline of the endocochlear potential (EP) and elevated auditory nerve compound action potential (CAP) thresholds. However, establishing a direct relationship between an age-related reduction in the EP and changes in the activities of primary auditory neurons is difficult owing to the complexity of age-related histological changes in the cochlea. To address this issue, we developed a young gerbil model of "metabolic" presbyacusis that uses an osmotic pump to deliver furosemide into the round window niche for 7 days, resulting in a chronically reduced EP. In this model, the only major histopathologic changes were restricted to the hook region of the cochlea and consisted of loss of strial intermediate cells and massive edema in the lateral wall. The morphological and physiological evidence suggests that the cochlea can adapt to furosemide application over time. The morphology of spiral ganglion cells and hair cells appeared normal throughout the cochlea. CAP responses and EP values in this model are similar to those of quiet-aged ears. The spontaneous activity of single auditory fibers (n= 188) was assessed in 15 young gerbils treated with furosemide for 7 days. The percentage of recorded low-spontaneous rate (SR) fibers at characteristic frequencies (CFs)≥6 kHz was significantly lower in furosemide-treated than in control ears. Recovery function tests of CAP responses after prior stimulation also showed a decline in activity of the low-SR population with CFs≥6 kHz in the treated cochleas. A similar loss in the activity of low-SR fiber has been previously shown in quiet-aged gerbils. These results suggest that dysfunction of the cochlear lateral wall and subsequent chronic reduction in the EP can directly affect the activity patterns of primary auditory neurons in a manner similar to that seen in aged gerbils.

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“…When the cochlear place-frequency map is known, frequency specific hearing loss can be directly correlated with hair cell loss. Tarnowski et al (1991) performed such a comparison of cytocochleograms and CAP thresholds in 16 old gerbils raised in a low-noise environment. In their sample, they found a substantial inter-animal variation of threshold shift and hair cell loss and defined 3 groups based on the degree of hair cell loss.…”

Section: Age-dependent Hair Cell Lossmentioning

confidence: 99%