Relations between frequency selectivity and two-tone rate suppression in lizard cochlear-nerve fibers

Holton, Thomas

doi:10.1016/0378-5955(80)90014-3

Cited by 27 publications

(12 citation statements)

References 32 publications

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“…In nerve-fibre experiments, we measured the visual detection level (v.d.l. ), defined as the lowest stimulus level (expressed in decibels re maximum click amplitude at the earphone input) at which the grcss-response wave form to clicks could be detected on an oscilloscope screen (Holton, 1980). In the hair-cell experiments, a similar but objective response measure, the computer detection level (c.d.l.)…”

Section: Methodsmentioning

confidence: 99%

“…Most of the techniques used in these two sets of experiments were similar, and technical details of animal surgery, acoustic stimulus generation and response recording are described elsewhere (Weiss, Mulroy, Turner & Pike, 1976;Holton, 1980;Baden-Kristensen & Weiss, 1983;Holton & Weiss, 1983). In brief, the basilar papilla of anaesthetized alligator lizards was exposed by opening and enlarging the round window.…”

Section: Methodsmentioning

confidence: 99%

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Frequency selectivity of hair cells and nerve fibres in the alligator lizard cochlea.

Holton¹,

Weiß²

1983

The Journal of Physiology

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SUMMARY1. Receptor potentials of hair cells and spike discharges of cochlear nerve fibres were recorded with micropipettes from the free-standing region of the basilar papilla of anaesthetized alligator lizards in response to tones. In this region the hair-cell stereocilia are free-standing, i.e. they protrude directly into endolymph and are not in contact with a tectorial membrane.2. The frequency selectivity of hair-cell responses was measured by means of isovoltage contours of the d.c. ( VJ) and fundamental-a.c. (V1) component of the receptor potential, i.e. iso-Vo and iso-V1 contours. The frequency selectivity of the nerve-fibre discharge was measured by iso-rate (iso-A0) contours. Iso-V0, iso-V1 and iso-A0 contours are basically V-shaped with a characteristic frequency (c.f.) defined as the frequency at which minimum sound pressure (Pmin) is required to evoke the criterion value of the response.3. Receptor potential iso-V0 contours and neural iso-A0 contours have similar slopes: the mean slopes of the low-frequency sides (dB/decade) are -43 0 and -44-3; the slopes of the high-frequency sides are 85-0 and 802. The band widths of iso-V0 and iso-A0 contours away from c.f. are similar (mean values of Q30dB are 040 and 053, respectively). The band widths of iso-A0 contours near c.f. are narrower than those of iso-V0 contours (mean values of QlodB are 2-34 and 1-20, respectively). However, the shapes of the contours near c.f. depend on the iso-response criteria, and we have not determined whether or not iso-V0 and iso-A0 contours are similar near c.f. The shapes of iso-V1 contours differ from those of iso-V0 and iso-A0 contours.4. Nerve fibre c.f.s are tonotopically organized in the nerve, with lowest c.f.s recorded from fibres innervating the border of free-standing and tectorial regions, a region in which hair-cell stereocilia are longest, and the highest c.f.s recorded from fibres innervating the end of the free-standing region in which hair-cell stereocilia are shortest. The c.f. of nerve-fibre response (and by implication hair-cell response) is, therefore, correlated with the height of the stereociliary tuft.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Frequency selectivity of hair cells and nerve fibres in the alligator lizard cochlea.

Holton¹,

Weiß²

1983

The Journal of Physiology

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“…Hill, 1998;Lukashkin and Russell, 1998] and is observed in the auditory nerve fiber responses of mammals and lower vertebrates, including birds [Sachs et al, 1974;Hill et al, 1989;Manley et al, 1991;Chen et al, 1996a]. In the alligator-lizard it is shown that TTRS only occurs in nerve fibers innervating hair cells covered by a tectorial membrane structure [Holton, 1980]. 290 Audiol Neurootol 1999;4:286-302 Smolders the remainder.…”

Section: Single Auditory Nerve Fibersmentioning

confidence: 99%

Functional Recovery in the Avian Ear after Hair Cell Regeneration

Smolders

1999

Audiol Neurotol

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Trauma to the inner ear in birds, due to acoustic overstimulation or ototoxic aminoglycosides, can lead to hair cell loss which is followed by regeneration of new hair cells. These processes are paralleled by hearing loss followed by significant functional recovery. After acoustic trauma, functional recovery is rapid and nearly complete. The early and major part of functional recovery after sound trauma occurs before regenerated hair cells become functional. Even very intense sound trauma causes loss of only a proportion of the hair cell popu- lation, mainly so-called short hair cells residing on the abneural mobile part of the avian basilar membrane. Uncoupling of the tectorial membrane from the hair cells during sound overexposure may serve as a protection mechanism. The rapid functional recovery after sound trauma appears not to be associated with regeneration of the lost hair cells, but with repair processes involving the surviving hair cells. Small residual functional deficits after recovery are most likely associated with the missing upper fibrous layer of the tectorial membrane which fails to regenerate after sound trauma. After aminoglycoside trauma, functional recovery is slower and parallels the structural regeneration more closely. Aminoglycosides cause damage to both types of hair cells, starting at the basal (high frequency) part of the basilar papilla. However, functional hearing loss and recovery also occur at lower frequencies, associated with areas of the papilla where hair cells survive. Functional recovery in these low frequency areas is complete, whereas functional recovery in high frequency areas with complete hair cell loss is incomplete, despite regeneration of the hair cells. Permanent residual functional deficits remain. This indicates that in low frequency regions functional recovery after aminoglycosides involves repair of nonlethal injury to hair cells and/or hair cell-neural synapses. In the high frequency regions functional recovery involves regenerated hair cells. The permanent functional deficits after the regeneration process in these areas are most likely associated with functional deficits in the regenerated hair cells or shortcomings in the synaptic reconnections of nerve fibers with the regenerated hair cells. In conclusion, the avian inner ear appears to be much more resistant to trauma than the mammalian ear and possesses a considerable capacity for functional recovery based on repair processes along with its capacity to regenerate hair cells. The functional recovery in areas with regenerated hair cells is considerable but incomplete.

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“…The basilar papilla of an anaesthetized alligator lizard was exposed by chipping away the ventral edge of the round-window foramen with forceps and then carefully removing the round-window membranes. It was previously established that this surgical procedure can be accomplished without measurably affecting the response of the ear (Holton, 1980). The circulation of the ear remained intact during surgery and was monitored during the experiment through the operating microscope.…”

Section: Definitions and Symbols V(t)mentioning

confidence: 99%

“…In this study iso-voltage contours were measured over a frequency range not exceeding 50 Hz-20 kHz with a resolution of 10 points/decade. In order to facilitate comparisons between the frequency selectivity of hair cells and cochlear neurones, the algorithm used to generate the iso-voltage contours was similar to that previously used to measure neural iso-rate contours (Kiang, Moxon & Levine, 1970;Weiss et al 1976;Liberman, 1978;Holton, 1980;Holton & Weiss, 1983). We shall describe the algorithm we used to measure the iso-V0 contours; iso-V, contours were measured in an analogous manner.…”

Section: Stimulus Paradigms and Response Measurementsmentioning

confidence: 99%

Receptor potentials of lizard cochlear hair cells with free‐standing stereocilia in response to tones.

Holton¹,

Weiß²

1983

The Journal of Physiology

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SUMMARY1. Intracellular potentials were recorded with micropipettes from hair cells with free-standing stereocilia in the cochleae of anaesthetized alligator lizards.2. Wave forms of intracellular responses to click stimuli were classified into three types: hair cells, supporting cells, and untuned cells. We studied primarily the responses of hair cells to tonal stimuli.3. For most frequencies, f, and levels, P, of tone-burst stimuli, the response envelope of the receptor potential increases monotonically at the tone-burst onset, and decreases monotonically at tone-burst offset. Overshoot in the envelope of the response at the onset and offset of tone bursts is observed only for tone bursts of low f, high P, and short ( and V' components was measured by means of iso-voltage (iso-V0 and iso-V,)contours. Iso-V0 and iso-V' contours are V-shaped: the maximum sensitivity occurs at a characteristic frequency (c.f. ). The shapes of these contours near the c.f. depend on the values of V0 and V1 at which the contours were measured and are sharper for lower values of V1 and V1. The mean slopes of the low-and high-frequency sides of these contours are: -45-0 and + 85-1 dB/decade for iso-V0 contours (n = 26), and -33'6 and + 103'8 dB/decade for iso-V1 contours (n = 28).6. The receptor potential has non-linear properties. The magnitudes and phase angles of V0, 'l, V2, and V3 receptor-potential components were measured as a function of P for different f. The slopes of level functions (the dependence of log V0 and log V1I on log P) were measured at low levels for different f. T. HOLTON AND T. F. WEISSdiffering from c.f. by more than a half-octave, the slope for VT is between 1 and 2 with a mean of 1P3; the slope for V1 is about 1, i.e. V11 increases approximately linearly with P. For frequencies near c.f., the slopes for V0 and V1 are approximately 0-8 and 0 5, respectively, indicating the presence of a compressive non-linearity. An effect of this frequency-dependent non-linearity is to sharpen the frequency selectivity at lower response magnitudes for f near c.f.7. The receptor potential shows low-pass filtering. Whereas the maximum response magnitude of V0 (i.e. the saturation value measured at high P) does not depend on f, the maximum Vj decreases by approximately 20 dB/decade with increasing f. Values of IIJ1I measured at a constant value of V0 also decline by approximately 20 dB/decade.8. Many of the results are consistent with the predictions of a three-stage model of the generation of the receptor potential. The first stage, which represents the mechanical properties ofthe middle and inner ear, is a linear, time-invariant, band-pass filter; the second stage, which represents mechanoelectric transduction in hair cells, is a zero-memory non-linearity; the third stage, which represents the electrical properties of hair cells, is a linear, time-invariant, low-pass filter. However, the results differ from the model predictions for low-level acoustic stimuli near c.f., and indicate the presence of a frequency-dependent compr...

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Relations between frequency selectivity and two-tone rate suppression in lizard cochlear-nerve fibers

Cited by 27 publications

References 32 publications

Frequency selectivity of hair cells and nerve fibres in the alligator lizard cochlea.

Frequency selectivity of hair cells and nerve fibres in the alligator lizard cochlea.

Functional Recovery in the Avian Ear after Hair Cell Regeneration

Receptor potentials of lizard cochlear hair cells with free‐standing stereocilia in response to tones.

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