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1 Departments of Communication Sciences and Disorders
3 Neurobiology and Physiology, Northwestern University, Evanston, IL 60208, USA
2
Department of Developmental Neurobiology, St Jude Children's Research Hospital, Memphis, TN 38105, USA
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Abstract |
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45 dB at 5 kHz and by 60 dB at 33 kHz. However, in order to conclude that outer hair cell (OHC) electromotility is associated with the cochlear amplifier, frequency selectivity must be evaluated and the integrity of the OHC's forward transducer ascertained. The present report demonstrates no frequency selectivity in CAP tuning curves recorded in homozygotes. In addition, CAP input–output functions indicate that responses in knockout mice approach those in controls at high levels where the amplifier has little influence. Although the cochlear microphonic in knockout mice remains 12 dB below that in wild-type mice even at the highest levels, this deficit is thought to reflect hair cell losses in mice lacking prestin. A change in OHC forward transduction is not implied because knockout mice display non-linear responses similar to those in controls. For example, homozygotes exhibit a bipolar summating potential (SP) with positive responses at high frequencies; negative responses at low frequencies. Measurement of intermodulation distortion also shows that the cubic difference tone, 2f1–f2, is 20 dB down from the primaries in both homozygotes and their controls. Because OHCs are the sole generators of the negative SP and because 2f1–f2 is also thought to originate in OHC transduction, these data support the idea that forward transduction is not degraded in OHCs lacking prestin. Finally, application of AM1-43, which initially enters hair cells through their transducer channels, produces fluorescence in wild-type and knockout mice indicating transducer channel activity in both inner and outer hair cells.
(Received 4 June 2004;
accepted after revision 16 August 2004;
first published online 19 August 2004)
Corresponding author M. A. Cheatham: 2-240 Frances Searle Building, 2240 Campus Drive, Northwestern University, Evanston, IL 60208-3550, USA. Email: m-cheatham{at}northwestern.edu
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Introduction |
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In spite of this evidence, an in vivo model is required in order to investigate the association between electromotility and the cochlear amplifier. This is because the OHCs are included in a tightly coupled feedback loop, which comprises the basilar membrane–OHC–tectorial membrane complex. Fortunately, development of the Prestin knockout mouse makes it possible to determine whether loss of OHC motor function affects cochlear sensitivity and/or frequency selectivity. Previous results (Liberman et al. 2002) indicate that OHCs isolated from F2 generation mice lacking prestin do not exhibit electromotility. There is also an 50 dB threshold shift for both auditory brainstem responses (ABRs) and otoacoustic emissions (OAEs). However, it is not known if frequency selectivity is also compromised. This information is required before one can conclude that prestin is associated with the cochlear amplifier.
It is also important to determine the functional status of mechanoelectrical transduction, which involves the mechanical gating of transducer channels located at the tips of the stereocilia (Hudspeth & Corey, 1977). In other words, an assessment of transducer function is required in order to learn if the loss of function phenotype reflects changes in forward, i.e. mechanoelectrical transduction, as opposed to the assumed reverse or electromechanical process. If prestin is a key component of the cochlear amplifier, then the functional changes observed in knockout mice should result from loss of OHC motor function, i.e. reverse or electromechanical transduction, and not from a change in forward transduction.
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Methods |
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Mice were generated from designated breeding pairs to produce litters of homozygous (–/–), heterozygous (+/–) and wild-type (+/+) pups. The physiological data in this report were obtained from a total of 32 mice: 10 +/+, 9 +/– and 13 –/–. Except where noted, the measurements were made using electrical recordings from the round window membrane in F4 generation mice (129/SvEv and C57BL/6 mixed background) between 30 and 58 days of age. Mice were anaesthetized with sodium pentobarbital (80 mg kg–1 I.P.) and supplemental doses, using dilute anaesthetic, were administered as needed. During surgery and recording, the animal's rectal temperature was maintained at 38°C and the headholder was heated to prevent cooling of the cochlea (Shore & Nuttall, 1985; Ohlemiller & Siegel, 1992). Using the traditional ventrolateral approach, the bulla was exposed and a small window was made in the bullar bone using a miniature knife. A recording electrode, fashioned from Teflon-coated silver wire (insulated diameter 140 µm), was placed on the round window membrane. The reference electrode was placed subcutaneously on the opposite side of the head. At the end of all experiments, animals were killed with a lethal dose of anaesthetic (200 mg kg–1 I.P.) and then decapitated.
Cochlear sensitivity was determined by measuring thresholds for the compound action potential (CAP) produced in response to 20 ms tone bursts, averaged 32 times and presented with an interstimulus interval of 135 ms. In this procedure, a tracking program (Taylor & Creelman, 1967; Gummer et al. 1987) determined the sound pressure level needed to generate an N1/P1 voltage of 10 µV at any given stimulus frequency. The method of sound calibration used to obtain these values is described elsewhere (Pearce et al. 2000).
In addition to threshold determinations, tone-on-tone masking curves (Dallos & Cheatham, 1976a) were also obtained to generate CAP tuning curves. Although forward masking curves are quantitatively more comparable to single unit and mechanical tuning curves, higher masker levels are required to produce criterion decreases in the N1/P1 voltage. This occurs because masker and probe are non-overlapping in time. Only by obtaining simultaneous tuning curves was it possible to assay frequency selectivity in homozygotes where CAP thresholds are shifted by 50 dB. In other words, the maximum sound pressure levels produced by our signal generation system were insufficient to obtain forward masking tuning curves in knockout mice. Hence, our use of simultaneous masking. In this paradigm, a 10 ms probe tone was presented 24 ms after the onset of the masker, which was 44 ms in duration including the 5 ms rise/fall times. The masker was presented in alternating phase to minimize the cochlear microphonic (CM) generated in response to the masker. Prior to collecting the tuning curve, the 12 kHz probe tone was presented alone and adjusted in level until an N1/P1 voltage of 45 µV was recorded. Masker frequency and level were then varied to produce a 3 dB decrease in the probe response, i.e. a decrease to 32 µV. Responses to 20 stimulus presentations were averaged to improve the signal-to-noise ratio. The tuning curve was then constructed by tracing together the masker frequency level/combinations associated with the criterion reductions. The computer generated tone bursts used to elicit the CAP had 1 ms rise/fall times for both CAP threshold and CAP tuning curve determinations.
When collecting CAPs to determine sensitivity and/or frequency selectivity, a custom-made programmable filter was used to bandpass filter the round window responses between 0.2 and 3 kHz. In other cases, input–output functions were collected without bandpass, but with lowpass filtering at 49.9 kHz to prevent aliasing. This wideband configuration allowed the cochlear microphonic and summating potentials (SP) to be recorded, as well as the CAP. Magnitudes were taken from fast Fourier transforms (FFTs) of averaged response waveforms. Waveform segments, obtained during the steady-state portion of the response, were windowed prior to transformation using a Hanning function.
Two-tone inputs were also used to study intermodulation distortion. In these experiments, the stimulus consisted of two tones partially overlapping in time (Cheatham & Dallos, 1997). These and all signals were transduced by a single modified Realistic super tweeter (RS no. 40-1310B). Analysis windows for FFTs were chosen to measure the primaries alone, as well as combination tones generated when both signals were presented together. The level of f1 (10 kHz) was 14 dB higher than that of f2 (12.195 kHz) to produce similar CM responses for each primary. To assure that responses shown in Fig. 7 were not due to distortion in the sound, measurements were made in a knockout mouse after euthanasia. All postmortem responses were less than 0.7 µV, even at the highest input levels.
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Viability of the hair cell transducer was also evaluated using AM1-43 (Biotium, Hayward CA, USA), the fixable analogue of FM1-43 (Nishikawa & Sasaki, 1996; Gale et al. 2001; Meyer et al. 2001; Meyers et al. 2003; Géléoc & Holt, 2003b; Si et al. 2003). This fluorescent styryl dye is quickly taken up by hair cells through their transducer channels, with subsequent endocytotic entry occurring on a slower time scale. On postnatal day 12 (P12), AM1-43 (3 mg (kg body weight)–1) was injected into a litter of six pups that were produced by mating heterozygotes. At 5 weeks of age, the mice were killed with an overdose of sodium pentobarbital and cardiac perfused, first with heparinized saline and then with 4% paraformaldehyde. Cochleae were removed and apical turns dissected and mounted for viewing on a Leica confocal microscope.
Dye uptake into cochlear hair cells was also studied in vitro. Following an overdose of sodium pentobarbital (200 mg kg–1 I.P.), cochleae from +/+ and –/– mice at 7 weeks of age were harvested. Openings at the apex and base allowed exposure to 0.3 µM AM1-43 for 1–2 min. After washing for 2 min, the tissue was fixed in 4% paraformaldehyde for 30 min. Organ of Corti segments from the apical half of the cochlea were then removed and viewed on the Leica confocal microscope. The medium used in all cases was composed of the following: 5 mM KCl, 10 mM Hepes, 45 mM NaCl, 105 mM NaOH, 24 mM HCO3, 100 mM lactobionic acid. The osmolarity was 317 mosmol l–1 and the pH was 7.3 after bubbling with carbogen (95% O2, 5% CO2).
In order to verify that dye uptake was via the transducer channels and not via endocytosis (Meyer et al. 2001; Griesinger et al. 2002; Si et al. 2003), the transducer channel was blocked using dihydrostreptomycin (DHSM) (Kroese et al. 1989). In these experiments, cochleae were harvested from wild-type mice. The first cochlea dissected was pre-incubated with 1 mM DHSM for 5 min. After exposure of one ear to the blocker, both ears were then placed in 3.5 µM AM1-43 for 1.5 min. After washing, the cochleae were again fixed in 4% paraformaldehyde for 30 min. It should be emphasized that DHSM was added to the AM1-43 and to the wash medium, but only for the ear pre-incubated with the blocker. In contrast to all other results, the DHSM experiments were performed on F5 generation wild-type mice. All procedures were approved by the National Institutes of Health and by Northwestern University's Institutional Review Board.
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Results |
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Mean CAP thresholds for all three genotypes are shown in Fig. 1 for F4 generation mice. Although +/+ (circles) and +/– (triangles) mice show similar thresholds, those for –/– (squares) mice are shifted in sensitivity in a frequency-dependent manner, ranging from 35 dB at low frequencies to 60 dB at high frequencies. These threshold shifts are similar to those from Liberman et al. (2002) in F2 generation homozygous mice using ABRs and OAEs. The mean CAP thresholds in Fig. 1 were obtained from a total of six mice, except at 38 kHz where a threshold was measured in only two animals. In addition, at 45 kHz and above, the sound pressure levels were not sufficient to generate the criterion 10 µV N1/P1 voltage in homozygotes. These data imply that the number of functional hair cells in the basal 1.5 mm of the cochlea is probably small in animals older than 46 days of age, which is the mean age of homozygotes represented in Fig. 1. This estimate is based on a physiological frequency-place map (Mueller et al. 2004). This map indicates that the lower frequency limit at the apex of the mouse cochlea occurs at 4.8 kHz. This frequency limit suggests that the smaller threshold shifts measured below 5 kHz probably reflect responses by contributing single units on the tails of their tuning curves where the amplifier has less influence. In other words, frequency-dependent CAP threshold shifts do not imply that the gain of the cochlear amplifier is reduced at 2 vs. 5 kHz. The frequency-dependent gain change, attributable to the cochlear amplifier, is from 45 dB at 5 kHz to 60 dB at higher frequencies.
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38 kHz. This observation limits the number of fibres that can be recruited to provide the high-level segment of the CAP function.
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In order to evaluate the status of the hair cell transducer, CM input–output functions were collected at 6 kHz. This stimulus, which is a relatively low frequency for the mouse, was chosen to minimize the effect of OHC loss at the base of the cochlea in mice lacking prestin (Wu et al. 2004). Figure 5 shows average CM responses, as well as standard deviations, for wild-type controls and knockout mice. Also included are individual functions for the nine mice used to generate the wild-type mean. These results are plotted with dotted lines. The dashed lines show data from the knockout with the largest CM responses. Although shifted in sensitivity, the CM recorded in mice with the largest responses (dashed lines) approaches wild-type magnitudes at high levels.
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20 dB below the level of f1. This result is consistent with normal forward transducer function in OHCs (Patuzzi et al. 1989b; Jaramillo et al. 1993). AM1-43 fluorescence
Hair cell transducer function was also assessed in +/+ and –/– mice using the fixable fluorescent styryl dye AM1-43, which is quickly taken up by hair cells through their transducer channels (Gale et al. 2001; Meyers et al. 2003; Géléoc & Holt, 2003b; Si et al. 2003). Figure 8 indicates that in vivo injection of the dye at P12 results in the labelling of both inner and outer hair cells in wild-type (A) and knockout (B) mice. In addition, both populations of cochlear hair cells were fluorescent when dissected apical segments were exposed to AM1-43 in vitro for 2 min as shown in Fig. 8C and D for wild-type and knockout mice, respectively. Finally, Fig. 8E and F show images obtained using DHSM, a known blocker of the hair cell transducer channel (Kroese et al. 1989). In spite of using a 10-fold increase in the concentration of AM1-43, fluorescence is drastically reduced in the presence of DHSM, as shown in Fig. 8F. Therefore, AM1-43 is probably entering the hair cells through transducer channels and not via endocytosis.
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Discussion |
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In contrast to CAPs, which are summed neural responses, the CM reflects hair cell receptor currents. Although IHCs probably make some contribution to the CM, evidence suggests that this response is dominated by OHC receptor currents (Dallos & Wang, 1974; Dallos & Cheatham, 1976b; Patuzzi et al. 1989a). In addition, the CM recorded from the round window is a population response with contributing hair cell groups changing with stimulus frequency and level. It is therefore important to exercise caution when interpreting CM results. For example, CM data in normal animals suggests that low-level responses are more dependent on hair cell populations near the BF of the stimulus, whereas high-level responses are strongly dominated by cells near the round-window electrode even at low frequencies (Patuzzi et al. 1989a). This level of dependence is probably minimized in knockout mice where hair cell death begins at 3 weeks of age, and by 6 weeks of age IHC and OHC loss is observed over the basal 28% of the cochlea (Wu et al. 2004). To make matters worse, the reported profile of hair cell loss probably underestimates functional hair cell loss. Just because a cell is present does not mean that it is working properly (Steel & Bock, 1983).
Data in Fig. 4 indicate that CM responses in the present study for +/+ and +/– mice are commensurate with those obtained by Legan et al. (2000) who also used the same mixed 129SvEv/C57BL6 background to develop their 
-tectorin knockout mice. Both studies show CM responses in wild-type controls that are much larger that those of Liberman et al. (2002). Independent of whether these differences are due to variations between F2 and F4 generations or whether the Liberman et al. (2002) data are abnormal, it is incorrect to assume that the similarity of CM responses in all three genotypes implies normal OHC transducer function (Liberman et al. 2002). In other words, one should not expect identical CM functions from ears that possess normal amplification and from those with impaired amplification. No matter how the amplification-providing feedback loop is opened, the system gain will be reduced and with it the input to the forward transducer. As a result, the transducer current, and thus the CM, will decrease. These reductions in the CM observed in F4 homozygotes could reflect a deficit in either forward or reverse transduction. Therefore, the status of the forward transducer was evaluated.
Results obtained in homozygotes using AM1-43 suggest that both inner and outer hair cells have open transducer channels. Although it is possible that this dye is taken up into hair cells via endocytosis (Nishikawa & Sasaki, 1996; Meyer et al. 2001; Griesinger et al. 2002), the time course is slower than that through functional transducer channels. While the latter occurs in seconds, endocytosis takes at least 2 min dye exposure in isolated sense organs (Si et al. 2003). In our case, however, the entire cochlea was incubated in AM1-43. While isolated organ segments were dissected for examination, this took place only after fixation in order to prevent damage to the transducer channels. Because of the longer diffusion time for the dye to enter scala media in intact preparations, one should probably not use estimates of AM1-43 entry via endocytosis that are derived from studies on organ segments. Furthermore, we have observed OHC fluorescence in knockout mice for cochlear incubation times as short as 68 s. Hence, the different time course, as well as the squelching of fluorescence in the presence of DHSM, suggests that the route of entry by AM1-43 for short exposures is via transducer channels. However, it is conceivable that transducer channels in homozygotes are fully open, allowing dye to enter, but not fully functional. If this were the case, one would not expect signal-dependent modulation of the channel. The presence of a CM argues against this possibility.
The physiological data also support the idea that forward transduction is normal in OHCs lacking prestin. CAP input–output functions at 6 kHz show near-normal magnitudes at high levels where minimal amplification is expected. However, the CM in the knockout mouse with the largest responses is still 12 dB down when compared to the wild-type mean. Reduction in the number of contributing hair cells in knockout mice could underlie this observation that homozygotes produce smaller maximal CM responses than do controls at high levels. In the presence of hair cell loss, the high-level CM in knockout mice will be diminished reflecting the reduction in the number of contributing hair cells, their increasing distance from the recording electrode and the complications associated with phase cancellation. For example, contributions from basal-turn OHCs in wild-type mice at 6 kHz are expected to grow linearly with level up to the point where the transducers of contributing hair cells begin to saturate. These contributions, obtained well below the BF of contributing OHCs, would not suffer reductions due to phase cancellation. As a result, the CM in wild-type mice at low frequencies is minimally influenced by the cochlear amplifier because the hair cells dominating the CM are responding linearly on the tails of their tuning curves. In contrast, the CM recorded from homozygotes is probably dominated by OHCs with BFs nearer to the stimulus frequency because of the incidental hair cell death occurring in these mice. As a result, increasing the level of a 6 kHz tone does not recruit as many OHCs from the base of the cochlea in knockout mice. Moreover, the summed responses from hair cells that do contribute are probably subject to phase cancellation. This argument suggests that the reduced CM is probably not due to a modification in forward transduction. This conclusion is supported by the existence of tip links between OHC stereocilia in knockout mice (Wu et al. 2004).
The presence of a bipolar SP is also consistent with normal OHC transducer function. Evidence from intracellular recordings suggests that OHCs respond to inputs below BF with negative, hyperpolarizing dc receptor potentials (Dallos et al. 1982; Russell & Sellick, 1983; Dallos, 1985, 1986; Cody & Russell, 1987), whereas IHCs never produce this polarity. These intracellular responses are reflected at the round window as negative SPs. It is also known that no negative SP is recorded in animals lacking OHCs in the basal half of the guinea pig cochlea due to kanamycin intoxication. Therefore, Dallos & Wang (1974) concluded that OHCs alone generate this SP polarity. This knowledge implies that SP responses, obtained at what are low frequencies in the mouse, should be asymmetrical in the negative direction when OHCs with viable transducers, basal to the BF location of the stimulus, contribute to the responses.
The presence of a cubic difference tone at 20 dB below the primaries in both wild-type and knockout mice is also consistent with normal OHC transducer function. Measurement of intermodulation distortion in cochlear mechanics (Robles et al. 1997) or in neural responses (Dallos et al. 1980) suggests that the most prominent distortion product, 2f1–f2, is probably generated by OHCs. Because reverse transduction cannot produce this component in mice lacking prestin, present data support the idea that the cubic difference tone is associated with OHC mechanoelectrical transduction (Patuzzi et al. 1989b; Jaramillo et al. 1993), i.e. cochlear distortion originates in hair cell non-linearities (Goldstein, 1967; Dallos et al. 1969). The fact that intermodulation distortion in both knockout and wild-type mice is 20 dB down from the primaries also indicates that shortening of OHCs does not alter ciliary mechanics or the residual mechanical response (Santos-Sacchi, 2003).
Although results shown here are consistent with the idea that prestin and OHC motility are required for normal cochlear function, one cannot conclude that prestin alone is the cochlear amplifier. While we show that OHC motility is necessary for amplification, it is yet to be determined if it is sufficient or whether its interaction with other processes is required. This caveat is needed because removal of prestin makes it difficult to determine whether other elements in the feedback path contribute to the sensitivity and frequency selectivity of the peripheral auditory system (Géléoc & Holt, 2003a; Fettiplace & Ricci, 2003). This difficulty is exacerbated by the hair cell loss in the Prestin-null mouse, which complicates comparisons with controls.
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References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Belyantseva IA, Adler HJ, Curi R, Frolenkov GI & Kachar B (2000). Expression and localization of Prestin and the sugar transporter GLUT-5 during development of electromotility in cochlear outer hair cells. J Neurosci 20, RC116, 1–5.
Brownell WE, Bader CR, Bertrand D & de Ribaupierre Y (1985). Evoked mechanical responses of isolated outer hair cells. Science 227, 194–196.
Cheatham MA & Dallos P (1997). Intermodulation components in inner hair cell and organ of Corti responses. J Acoust Soc Am 102, 1038–1048.[CrossRef][Medline]
Cody AR & Russell IJ (1987). The responses of hair cells in the basal turn of the guinea-pig cochlea to tones. J Physiol 383, 551–569.
Dallos P (1973). The Auditory Periphery. Academic Press, New York.
Dallos P (1985). Response characteristics of mammalian cochlear hair cells. J Neurosci 5, 1591–1608.[Abstract]
Dallos P (1986). Neurobiology of cochlear inner and outer hair cells: intracellular recordings. Hear Res 22, 185–198.[CrossRef][Medline]
Dallos P (1992). The active cochlea. J Neurosci 12, 4575–4585.[Medline]
Dallos P & Cheatham MA (1976a). Compound action potential (AP) tuning curves. J Acoust Soc Am 59, 591–597.[CrossRef][Medline]
Dallos P & Cheatham MA (1976b). Production of cochlear potentials by inner and outer hair cells. J Acoust Soc Am 60, 510–512.[CrossRef][Medline]
Dallos P & Fakler B (2002). Prestin, a new type of motor protein. Nat Rev Mol Cell Biol 3, 104–111.[CrossRef][Medline]
Dallos P, Harris DM, Relkin E & Cheatham MA (1980). Two-tone suppression and intermodulation distortion in the cochlea: Effect of outer hair cell lesions. In Psychophysical, Physiological and Behavioural Studies in Hearing, ed. Brink G & van den & Bilsen FA, pp. 242–249. Delft University Press, Delft.
Dallos P, Santos-Sacchi J & Flock Å (1982). Cochlear outer hair cells: Intracellular recordings. Science 218, 582–585.
Dallos P, Schoeny ZG & Cheatham MA (1972). Cochlear summating potentials: Descriptive aspects. Acta Otolaryngol Suppl 302, 1–46.[Medline]
Dallos P, Schoeny ZG, Worthington DW & Cheatham MA (1969). Cochlear distortion: Effect of direct-current polarization. Science 164, 449–451.
Dallos P & Wang CY (1974). Bioelectric correlates of kanamycin intoxication. Audiology 13, 277–289.[Medline]
Davis H (1983). An active process in cochlear mechanics. Hear Res 9, 79–90.[CrossRef][Medline]
Fettiplace R & Ricci AJ (2003). Adaptation in auditory hair cells. Curr Opin Neurobiol 13, 446–451.[CrossRef][Medline]
Gale JE, Marcotti W, Kennedy HJ, Kros CJ & Richardson GP (2001). FM1-43 dye behaves as a permanent blocker of the hair cell mechano-transducer channel. J Neurosci 21, 7013–7025.
Géléoc GSG & Holt JR (2003a). Auditory amplification: outer hair cells pres the issue. Trends Neurosci 26, 115–117.[CrossRef][Medline]
Géléoc GSG & Holt JR (2003b). Developmental acquisition of sensory transduction in hair cells of the mouse inner ear. Nat Neurosci 6, 1019–1020.[CrossRef][Medline]
Goldstein JL (1967). Auditory nonlinearity. J Acoust Soc Am 41, 676–689.[CrossRef][Medline]
Griesinger CB, Richards CD & Ashmore JF (2002). FM1-43 reveals membrane recycling in adult inner hair cells of the mammalian cochlea. J Neurosci 22, 3939–3952.
Gummer AW, Smolders JWT & Klinke R (1987). Basilar membrane motion in the pigeon measured with the Mössbauer technique. Hear Res 29, 63–92.[CrossRef][Medline]
Hudspeth AJ & Corey DP (1977). Sensitivity, polarity and conductance changes in the responses of vertebrate hair cells to controlled mechanical stimuli. Proc Natl Acad Sci U S A 74, 2407–2411.
Jaramillo F, Markin VS & Hudspeth AJ (1993). Auditory illusions and the single hair cell. Nature 364, 527–529.[CrossRef][Medline]
Judice TN, Nelson NC, Beisel CL, Delimont DC, Fritzsch B & Beisel KW (2002). Cochlear whole mount in situ hybridization: identification of longitudinal and radial gradients. Brain Res Protocols 9, 65–76.[CrossRef][Medline]
Kachar B, Brownell WE, Altschuler R & Fex J (1986). Electrokinetic shape changes of cochlear outer hair cells. Nature 322, 365–368.[CrossRef][Medline]
Kroese AB, Das A & Hudspeth AJ (1989). Blockage of the transduction channels of hair cells in the bullfrog's sacculus by aminoglycoside antibiotics. Hear Res 37, 203–217.[CrossRef][Medline]
Legan PK, Lukashkina VA, Goodyear RJ, Kössl M, Russell IJ & Richardson GP (2000). A targeted deletion in -tectorin reveals that the tectorial membrane is required for the gain and timing of cochlear feedback. Neuron 28, 273–285.[CrossRef][Medline]
Liberman MC, Gao J, He DZZ, Wu X, Jia S & Zuo J (2002). Prestin is required for electromotility of the outer hair cell and for the cochlear amplifier. Nature 419, 300–304.[CrossRef][Medline]
Liu XZ, Ouyang XM, Xia XJ, Zheng J, Pandya A, Li F, Du LL, Welch KO, Petit C, Smith RJ, Webb BT, Yan D, Arnos KS, Corey D, Dallos P, Nance WE, Chen ZY (2003). Prestin, a cochlear motor protein, is defective in non-syndromic hearing loss. Hum Mol Genet 12, 1155–1162.
Meyer J, Mack AF & Gummer AW (2001). Pronounced infranuclear endocytosis in mammalian outer hair cells. Hear Res 161, 10–22.[CrossRef][Medline]
Meyers JR, MacDonald RB, Duggan A, Lenzi DP, Standaert DG, Corwin JT, Corey DP (2003). Lighting up the senses: FM1-43 loading of sensory cells through nonselective ion channels. J Neurosci 23, 4054–4065.
Mueller M, von Huenerbein K, Hoidis S & Smolders JWT (2004). A physiological place-frequency map of the cochlea in the mouse. Abstract Assoc Res Otolaryngol, p. 143.
Narayan SS, Temchin AN, Recio A & Ruggero MA (1998). Frequency tuning of basilar membrane and auditory nerve fibers in the same cochleae. Science 282, 1882–1884.
Nishikawa S & Sasaki F (1996). Internalization of styryl dye FM1-43 in the hair cells of lateral line organs of Xenopus arvae. J Histochem Cytochem 44, 733–741.[Abstract]
Ohlemiller KK & Siegel JH (1992). The effects of moderate cooling on gross cochlear potentials in the gerbil: basal and apical differences. Hear Res 63, 79–89.[CrossRef][Medline]
Özdamar Ö & Dallos P (1976). Input–output functions of cochlear whole-nerve action potentials: interpretation in terms of one population of neurons. J Acoust Soc Am 59, 143–147.[CrossRef][Medline]
Patuzzi RB, Yates GK & Johnstone BM (1989a). The origin of the low-frequency microphonic in the first cochlear turn of guinea-pig. Hear Res 39, 177–188.[CrossRef][Medline]
Patuzzi RB, Yates GK & Johnstone BM (1989b). Outer hair cell receptor current and sensorineural hearing loss. Hear Res 42, 47–72.[CrossRef][Medline]
Pearce M, Richter C-P & Cheatham MA (2000). A reconsideration of sound calibration in the mouse. J Neurosci Methods 106, 57–67.[CrossRef]
Robles L, Ruggero MA & Rich NC (1997). Two-tone distortion at the basilar membrane of the chinchilla cochlea. J Neurophysiol 77, 2385–2399.
Russell IJ & Sellick PM (1983). Low-frequency characteristics of intracellularly recorded receptor potentials in guinea-pig cochlear hair cells. J Physiol 338, 179–206.
Santos-Sacchi J (2003). New tunes from Corti's organ: the outer hair cell boogie rules. Curr Opin Neurobiol 13, 1–10.[CrossRef]
Santos-Sacchi J & Dilger JP (1988). Whole-cell currents and mechanical responses of isolated outer hair cells. Hear Res 35, 143–150.[CrossRef][Medline]
Shnerson A & Pujol R (1981). Age-related changes in the C57BL/6J mouse cochlea. I. Physiological findings. Dev Brain Res 2, 65–75.[CrossRef]
Shore SE & Nuttall AL (1985). The effects of cochlear hypothermia on compound action potential tuning. J Acoust Soc Am 77, 590–598.[CrossRef][Medline]
Si F, Brodie H, Gillespie PG, Vazquez AE & Yamoah EN (2003). Developmental assembly of transducer apparatus in chick basilar papilla. J Neurosci 23, 10815–10826.
Steel KP & Bock GR (1983). Cochlear function in the jerker mouse. Behav Neurosci 97, 381–391.[CrossRef][Medline]
Taberner A & Liberman MC (2003). Response properties of single auditory nerve fibers in CBA/CaJ mice. Abstract Assoc Res Otolaryngol, p. 45.
Taylor MM & Creelman CD (1967). PEST: Efficient estimates on probability functions. J Acoust Soc Am 41, 782–787.[CrossRef]
Wu X, Gao J, Guo Y & Zuo J (2004). Hearing threshold elevation precedes hair cell loss in Prestin knockout mice. Brain Res Mol Brain Res 126, 30–37.[Medline]
Zheng J, Shen W, He DZZ, Long KB, Madison LD & Dallos P (2000). Prestin is the motor protein of cochlear outer hair cells. Nature 405, 149–155.[CrossRef][Medline]
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 M. E. Chiappe, A. S. Kozlov, and A. J. Hudspeth The Structural and Functional Differentiation of Hair Cells in a Lizard's Basilar Papilla Suggests an Operational Principle of Amniote Cochleas J. Neurosci., October 31, 2007; 27(44): 11978 - 11985. [Abstract] [Full Text] [PDF]
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 A. Toure, P. Lhuillier, J. A. Gossen, C. W. Kuil, D. Lhote, B. Jegou, D. Escalier, and G. Gacon The Testis Anion Transporter 1 (Slc26a8) is required for sperm terminal differentiation and male fertility in the mouse Hum. Mol. Genet., August 1, 2007; 16(15): 1783 - 1793. [Abstract] [Full Text] [PDF]
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J. Gao, X. Wang, X. Wu, S. Aguinaga, K. Huynh, S. Jia, K. Matsuda, M. Patel, J. Zheng, M. Cheatham, et al. Prestin-based outer hair cell electromotility in knockin mice does not appear to adjust the operating point of a cilia-based amplifier PNAS, July 24, 2007; 104(30): 12542 - 12547. [Abstract] [Full Text] [PDF]
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 F. Mammano, M. Bortolozzi, S. Ortolano, and F. Anselmi Ca2+ Signaling in the Inner Ear Physiology, April 1, 2007; 22(2): 131 - 144. [Abstract] [Full Text] [PDF]
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 P. Dallos, J. Zheng, and M. A. Cheatham Prestin and the cochlear amplifier J. Physiol., October 1, 2006; 576(1): 37 - 42. [Abstract] [Full Text] [PDF]
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J. Zheng, G.-G. Du, C. T. Anderson, J. P. Keller, A. Orem, P. Dallos, and M. Cheatham Analysis of the Oligomeric Structure of the Motor Protein Prestin J. Biol. Chem., July 21, 2006; 281(29): 19916 - 19924. [Abstract] [Full Text] [PDF]
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P. D. Marasco, P. R. Tsuruda, D. M. Bautista, D. Julius, and K. C. Catania Neuroanatomical evidence for segregation of nerve fibers conveying light touch and pain sensation in Eimer's organ of the mole PNAS, June 13, 2006; 103(24): 9339 - 9344. [Abstract] [Full Text] [PDF]
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M. A. Ruggero and A. N. Temchin Unexceptional sharpness of frequency tuning in the human cochlea PNAS, December 20, 2005; 102(51): 18614 - 18619. [Abstract] [Full Text] [PDF]
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M. A. Cheatham, J. Zheng, K. H. Huynh, G. G. Du, J. Gao, J. Zuo, E. Navarrete, and P. Dallos Cochlear function in mice with only one copy of the prestin gene J. Physiol., November 15, 2005; 569(1): 229 - 241. [Abstract] [Full Text] [PDF]
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 J. Zheng, G.-G. Du, K. Matsuda, A. Orem, S. Aguinaga, L. Deak, E. Navarrete, L. D. Madison, and P. Dallos The C-terminus of prestin influences nonlinear capacitance and plasma membrane targeting J. Cell Sci., July 1, 2005; 118(13): 2987 - 2996. [Abstract] [Full Text] [PDF]
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 Z.-W. Huang, Y. Luo, Z. Wu, Z. Tao, R. O. Jones, and H.-B. Zhao Paradoxical Enhancement of Active Cochlear Mechanics in Long-Term Administration of Salicylate J Neurophysiol, April 1, 2005; 93(4): 2053 - 2061. [Abstract] [Full Text] [PDF]
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