1
|
Ordiway G, McDonnell M, Sanchez JT. Revisiting the Chicken Auditory Brainstem Response: Frequency Specificity, Threshold Sensitivity, and Cross Species Comparison. Neurosci Insights 2024; 19:26331055241228308. [PMID: 38304551 PMCID: PMC10832403 DOI: 10.1177/26331055241228308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 01/09/2024] [Indexed: 02/03/2024] Open
Abstract
The auditory brainstem response (ABR) is important for both clinical and basic auditory research. It is a non-invasive measure of hearing function with millisecond-level precision. The ABR can not only measure the synchrony, speed, and efficacy of auditory physiology but also detect different modalities of hearing pathology and hearing loss. ABRs are easily acquired in vertebrate animal models like reptiles, birds, and mammals, and complement existing molecular, developmental, and systems-level research. One such model system is the chicken; an excellent animal for studying auditory development, structure, and function. However, the ABR for chickens was last reported nearly 4 decades ago. The current study examines how decades of ABR characterization in other animal species support findings from the chicken ABR. We replicated and expanded on previous research using 43 chicken hatchlings 1- and 2-day post-hatch. We report that click-evoked chicken ABRs presented with a peak waveform morphology, amplitude, and latency like previous avian studies. Tone-evoked ABRs were found for frequencies from 250 to 4000 Hertz (Hz) and exhibited a range of best sensitivity between 750 and 2000 Hz. Objective click-evoked and tone-evoked ABR thresholds were comparable to subjective thresholds. With these revisited measurements, the chicken ABR still proves to be an excellent example of precocious avian development that complements decades of molecular, neuronal, and systems-level research in the same model organism.
Collapse
Affiliation(s)
- George Ordiway
- Roxelyn and Richard Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA
- Central Auditory Physiology Laboratory, Northwestern University, Evanston, IL, USA
| | - Miranda McDonnell
- Roxelyn and Richard Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA
- Central Auditory Physiology Laboratory, Northwestern University, Evanston, IL, USA
| | - Jason Tait Sanchez
- Roxelyn and Richard Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA
- Central Auditory Physiology Laboratory, Northwestern University, Evanston, IL, USA
- Knowles Hearing Research Center, Northwestern University, Evanston, IL, USA
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
| |
Collapse
|
2
|
Wang Y, Abrams KS, Youngman M, Henry KS. Histological Correlates of Auditory Nerve Injury from Kainic Acid in the Budgerigar (Melopsittacus undulatus). J Assoc Res Otolaryngol 2023; 24:473-485. [PMID: 37798548 PMCID: PMC10695905 DOI: 10.1007/s10162-023-00910-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 09/11/2023] [Indexed: 10/07/2023] Open
Abstract
PURPOSE Loss of auditory nerve afferent synapses with cochlear hair cells, called cochlear synaptopathy, is a common pathology in humans caused by aging and noise overexposure. The perceptual consequences of synaptopathy in isolation from other cochlear pathologies are still unclear. Animal models provide an effective approach to resolve uncertainty regarding the physiological and perceptual consequences of auditory nerve loss, because neural lesions can be induced and readily quantified. The budgerigar, a parakeet species, has recently emerged as an animal model for synaptopathy studies based on its capacity for vocal learning and ability to behaviorally discriminate simple and complex sounds with acuity similar to humans. Kainic acid infusions in the budgerigar produce a profound reduction of compound auditory nerve responses, including wave I of the auditory brainstem response, without impacting physiological hair cell measures. These results suggest selective auditory nerve damage. However, histological correlates of neural injury from kainic acid are still lacking. METHODS We quantified the histological effects caused by intracochlear infusion of kainic acid (1 mM; 2.5 µL), and evaluated correlations between the histological and physiological assessments of auditory nerve status. RESULTS Kainic acid infusion in budgerigars produced pronounced loss of neural auditory nerve soma (60% on average) in the cochlear ganglion, and of peripheral axons, at time points 2 or more months following injury. The hair cell epithelium was unaffected by kainic acid. Neural loss was significantly correlated with reduction of compound auditory nerve responses and auditory brainstem response wave I. CONCLUSION Compound auditory nerve responses and wave I provide a useful index of cochlear synaptopathy in this animal model.
Collapse
Affiliation(s)
- Yingxuan Wang
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA
| | - Kristina S Abrams
- Department of Neuroscience, University of Rochester, Rochester, NY 14642, USA
| | - Margaret Youngman
- Department of Otolaryngology, University of Rochester, Rochester, NY 14642, USA
| | - Kenneth S Henry
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA.
- Department of Neuroscience, University of Rochester, Rochester, NY 14642, USA.
- Department of Otolaryngology, University of Rochester, Rochester, NY 14642, USA.
| |
Collapse
|
3
|
Fettiplace R. Cochlear tonotopy from proteins to perception. Bioessays 2023:e2300058. [PMID: 37329318 DOI: 10.1002/bies.202300058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/01/2023] [Indexed: 06/19/2023]
Abstract
A ubiquitous feature of the auditory organ in amniotes is the longitudinal mapping of neuronal characteristic frequencies (CFs), which increase exponentially with distance along the organ. The exponential tonotopic map reflects variation in hair cell properties according to cochlear location and is thought to stem from concentration gradients in diffusible morphogenic proteins during embryonic development. While in all amniotes the spatial gradient is initiated by sonic hedgehog (SHH), released from the notochord and floorplate, subsequent molecular pathways are not fully understood. In chickens, BMP7 is one such morphogen, secreted from the distal end of the cochlea. In mammals, the developmental mechanism differs from birds and may depend on cochlear location. A consequence of exponential maps is that each octave occupies an equal distance on the cochlea, a spacing preserved in the tonotopic maps in higher auditory brain regions. This may facilitate frequency analysis and recognition of acoustic sequences.
Collapse
Affiliation(s)
- Robert Fettiplace
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| |
Collapse
|
4
|
McGee J, Nelson PB, Ponder JB, Marr J, Redig P, Walsh EJ. Auditory performance in bald eagles and red-tailed hawks: a comparative study of hearing in diurnal raptors. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:793-811. [PMID: 31520117 DOI: 10.1007/s00359-019-01367-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/26/2019] [Accepted: 08/28/2019] [Indexed: 12/19/2022]
Abstract
Collision with wind turbines is a conservation concern for eagles with population abundance implications. The development of acoustic alerting technologies to deter eagles from entering hazardous air spaces is a potentially significant mitigation strategy to diminish associated morbidity and mortality risks. As a prelude to the engineering of deterrence technologies, auditory function was assessed in bald eagles (Haliaeetus leucocephalus), as well as in red-tailed hawks (Buteo jamaicensis). Auditory brainstem responses (ABRs) to a comprehensive battery of clicks and tone bursts varying in level and frequency were acquired to evaluate response thresholds, as well as suprathreshold response characteristics of wave I of the ABR, which represents the compound potential of the VIII cranial nerve. Sensitivity curves exhibited an asymmetric convex shape similar to those of other avian species, response latencies decreased exponentially with increasing stimulus level and response amplitudes grew with level in an orderly manner. Both species were responsive to a frequency band at least four octaves wide, with a most sensitive frequency of 2 kHz, and a high-frequency limit of approximately 5.7 kHz in bald eagles and 8 kHz in red-tailed hawks. Findings reported here provide a framework within which acoustic alerting signals might be developed.
Collapse
Affiliation(s)
- JoAnn McGee
- Department of Speech-Language-Hearing Sciences and the Center for Applied and Translational Sensory Science, University of Minnesota, 164 Pillsbury Dr. SE, Minneapolis, MN, 55455, USA.
| | - Peggy B Nelson
- Department of Speech-Language-Hearing Sciences and the Center for Applied and Translational Sensory Science, University of Minnesota, 164 Pillsbury Dr. SE, Minneapolis, MN, 55455, USA
| | - Julia B Ponder
- The Raptor Center, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, 55108, USA
| | - Jeffrey Marr
- St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN, 55414, USA
| | - Patrick Redig
- The Raptor Center, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, 55108, USA
| | - Edward J Walsh
- Department of Speech-Language-Hearing Sciences and the Center for Applied and Translational Sensory Science, University of Minnesota, 164 Pillsbury Dr. SE, Minneapolis, MN, 55455, USA
| |
Collapse
|
5
|
Krumm B, Klump G, Köppl C, Langemann U. Barn owls have ageless ears. Proc Biol Sci 2018; 284:rspb.2017.1584. [PMID: 28931742 DOI: 10.1098/rspb.2017.1584] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 08/14/2017] [Indexed: 11/12/2022] Open
Abstract
We measured the auditory sensitivity of the barn owl (Tyto alba), using a behavioural Go/NoGo paradigm in two different age groups, one younger than 2 years (n = 4) and another more than 13 years of age (n = 3). In addition, we obtained thresholds from one individual aged 23 years, three times during its lifetime. For computing audiograms, we presented test frequencies of between 0.5 and 12 kHz, covering the hearing range of the barn owl. Average thresholds in quiet were below 0 dB sound pressure level (SPL) for frequencies between 1 and 10 kHz. The lowest mean threshold was -12.6 dB SPL at 8 kHz. Thresholds were the highest at 12 kHz, with a mean of 31.7 dB SPL. Test frequency had a significant effect on auditory threshold but age group had no significant effect. There was no significant interaction between age group and test frequency. Repeated threshold estimates over 21 years from a single individual showed only a slight increase in thresholds. We discuss the auditory sensitivity of barn owls with respect to other species and suggest that birds, which generally show a remarkable capacity for regeneration of hair cells in the basilar papilla, are naturally protected from presbycusis.
Collapse
Affiliation(s)
- Bianca Krumm
- Cluster of Excellence 'Hearing4all', Animal Physiology and Behaviour Group, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111 Oldenburg, Germany
| | - Georg Klump
- Cluster of Excellence 'Hearing4all', Animal Physiology and Behaviour Group, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111 Oldenburg, Germany
| | - Christine Köppl
- Cluster of Excellence 'Hearing4all', Animal Physiology and Behaviour Group, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111 Oldenburg, Germany
| | - Ulrike Langemann
- Cluster of Excellence 'Hearing4all', Animal Physiology and Behaviour Group, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, 26111 Oldenburg, Germany
| |
Collapse
|
6
|
Xia A, Liu X, Raphael PD, Applegate BE, Oghalai JS. Hair cell force generation does not amplify or tune vibrations within the chicken basilar papilla. Nat Commun 2016; 7:13133. [PMID: 27796310 PMCID: PMC5095595 DOI: 10.1038/ncomms13133] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 09/07/2016] [Indexed: 12/22/2022] Open
Abstract
Frequency tuning within the auditory papilla of most non-mammalian species is electrical, deriving from ion-channel resonance within their sensory hair cells. In contrast, tuning within the mammalian cochlea is mechanical, stemming from active mechanisms within outer hair cells that amplify the basilar membrane travelling wave. Interestingly, hair cells in the avian basilar papilla demonstrate both electrical resonance and force-generation, making it unclear which mechanism creates sharp frequency tuning. Here, we measured sound-induced vibrations within the apical half of the chicken basilar papilla in vivo and found broadly-tuned travelling waves that were not amplified. However, distortion products were found in live but not dead chickens. These findings support the idea that avian hair cells do produce force, but that their effects on vibration are small and do not sharpen tuning. Therefore, frequency tuning within the apical avian basilar papilla is not mechanical, and likely derives from hair cell electrical resonance. The avian auditory papilla has many similarities to the mammalian cochlea but whether force generation by hair cells amplifies the travelling wave, as it does in mammals, remains unknown. Here the authors show that the chicken basilar papilla does not have a ‘cochlear amplifier' and that sharp frequency tuning does not derive from mechanical vibrations.
Collapse
Affiliation(s)
- Anping Xia
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, California 94305, USA
| | - Xiaofang Liu
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, California 94305, USA.,Department of Anorectal Surgery, the First Affiliated hospital of China Medical University, 155 NanjingBei Street, ShenYang, LiaoNing Province 110001, China
| | - Patrick D Raphael
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, California 94305, USA
| | - Brian E Applegate
- Department of Biomedical Engineering, Texas A&M University, 5059 Emerging Technology Building, 3120 TAMU, College Station, Texas 77843, USA
| | - John S Oghalai
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, California 94305, USA
| |
Collapse
|
7
|
Kim JW, Lee JH, Ma JH, Chung E, Choi H, Bok J, Cheon J. Magnetic Force Nanoprobe for Direct Observation of Audio Frequency Tonotopy of Hair Cells. NANO LETTERS 2016; 16:3885-91. [PMID: 27215487 DOI: 10.1021/acs.nanolett.6b01392] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Sound perception via mechano-sensation is a remarkably sensitive and fast transmission process, converting sound as a mechanical input to neural signals in a living organism. Although knowledge of auditory hair cell functions has advanced over the past decades, challenges remain in understanding their biomechanics, partly because of their biophysical complexity and the lack of appropriate probing tools. Most current studies of hair cells have been conducted in a relatively low-frequency range (<1000 Hz); therefore, fast kinetic study of hair cells has been difficult, even though mammalians have sound perception of 20 kHz or higher. Here, we demonstrate that the magnetic force nanoprobe (MFN) has superb spatiotemporal capabilities to mechanically stimulate spatially-targeted individual hair cells with a temporal resolution of up to 9 μs, which is equivalent to approximately 50 kHz; therefore, it is possible to investigate avian hair cell biomechanics at different tonotopic regions of the cochlea covering a full hearing frequency range of 50 to 5000 Hz. We found that the variation of the stimulation frequency and amplitude of hair bundles creates distinct mechanical responsive features along the tonotopic axis, where the kinetics of the hair bundle recovery motion exhibits unique frequency-dependent characteristics: basal, middle, and apical hair bundles can effectively respond at their respective ranges of frequency. We revealed that such recovery kinetics possesses two different time constants that are closely related to the passive and active motilities of hair cells. The use of MFN is critical for the kinetics study of free-standing hair cells in a spatiotemporally distinct tonotopic organization.
Collapse
Affiliation(s)
- Ji-Wook Kim
- Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, Republic of Korea
- Yonsei-IBS Institute, Yonsei University , Seoul 03722, Republic of Korea
- Department of Chemistry, Yonsei University , Seoul 03722, Republic of Korea
| | - Jae-Hyun Lee
- Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, Republic of Korea
- Yonsei-IBS Institute, Yonsei University , Seoul 03722, Republic of Korea
- Department of Chemistry, Yonsei University , Seoul 03722, Republic of Korea
| | | | - Eunna Chung
- Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, Republic of Korea
- Yonsei-IBS Institute, Yonsei University , Seoul 03722, Republic of Korea
- Department of Chemistry, Yonsei University , Seoul 03722, Republic of Korea
| | - Hongsuh Choi
- Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, Republic of Korea
- Yonsei-IBS Institute, Yonsei University , Seoul 03722, Republic of Korea
- Department of Chemistry, Yonsei University , Seoul 03722, Republic of Korea
| | | | - Jinwoo Cheon
- Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, Republic of Korea
- Yonsei-IBS Institute, Yonsei University , Seoul 03722, Republic of Korea
- Department of Chemistry, Yonsei University , Seoul 03722, Republic of Korea
| |
Collapse
|
8
|
Corfield JR, Krilow JM, Vande Ligt MN, Iwaniuk AN. A quantitative morphological analysis of the inner ear of galliform birds. Hear Res 2013; 304:111-27. [DOI: 10.1016/j.heares.2013.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 06/12/2013] [Accepted: 07/06/2013] [Indexed: 11/30/2022]
|
9
|
Tan X, Beurg M, Hackney C, Mahendrasingam S, Fettiplace R. Electrical tuning and transduction in short hair cells of the chicken auditory papilla. J Neurophysiol 2013; 109:2007-20. [PMID: 23365177 DOI: 10.1152/jn.01028.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The avian auditory papilla contains two classes of sensory receptor, tall hair cells (THCs) and short hair cells (SHCs), the latter analogous to mammalian outer hair cells with large efferent but sparse afferent innervation. Little is known about the tuning, transduction, or electrical properties of SHCs. To address this problem, we made patch-clamp recordings from hair cells in an isolated chicken basilar papilla preparation at 33°C. We found that SHCs are electrically tuned by a Ca(2+)-activated K(+) current, their resonant frequency varying along the papilla in tandem with that of the THCs, which also exhibit electrical tuning. The tonotopic map for THCs was similar to maps previously described from auditory nerve fiber measurements. SHCs also possess an A-type K(+) current, but electrical tuning was observed only at resting potentials positive to -45 mV, where the A current is inactivated. We predict that the resting potential in vivo is approximately -40 mV, depolarized by a standing inward current through mechanotransducer (MT) channels having a resting open probability of ∼0.26. The resting open probability stems from a low endolymphatic Ca(2+) concentration (0.24 mM) and a high intracellular mobile Ca(2+) buffer concentration, estimated from perforated-patch recordings as equivalent to 0.5 mM BAPTA. The high buffer concentration was confirmed by quantifying parvalbumin-3 and calbindin D-28K with calibrated postembedding immunogold labeling, demonstrating >1 mM calcium-binding sites. Both proteins displayed an apex-to-base gradient matching that in the MT current amplitude, which increased exponentially along the papilla. Stereociliary bundles also labeled heavily with antibodies against the Ca(2+) pump isoform PMCA2a.
Collapse
Affiliation(s)
- Xiaodong Tan
- Department of Neuroscience, University of Wisconsin Medical School, Madison, Wisconsin, USA
| | | | | | | | | |
Collapse
|
10
|
Tabor KM, Coleman WL, Rubel EW, Burger RM. Tonotopic organization of the superior olivary nucleus in the chicken auditory brainstem. J Comp Neurol 2012; 520:1493-508. [PMID: 22102107 DOI: 10.1002/cne.22807] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Topographic maps are salient features of neuronal organization in sensory systems. Inhibitory components of neuronal circuitry are often embedded within this organization, making them difficult to isolate experimentally. The auditory system provides opportunities to study the topographic organization of inhibitory long-range projection nuclei, such as the superior olivary nucleus (SON). We analyzed the topographic organization of response features of neurons in the SON of chickens. Quantitative methods were developed to assess and communicate this organization. These analyses led to three main conclusions: 1) sound frequency is linearly arranged from dorsal (low frequencies) to ventral (high frequencies) in SON; 2) this tonotopic organization is less precise than the organization of the excitatory nuclei in the chicken auditory brainstem; and 3) neurons with different response patterns to pure tone stimuli are interspersed throughout the SON and show similar tonotopic organizations. This work provides a predictive model to determine the optimal stimulus frequency for a neuron from its spatial location in the SON.
Collapse
Affiliation(s)
- Kathryn M Tabor
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology, Head and Neck Surgery and Neurobiology and Behavior Graduate Program, University of Washington, Seattle, Washington 98195, USA
| | | | | | | |
Collapse
|
11
|
Manley GA, Narins PM, Fay RR. Experiments in comparative hearing: Georg von Békésy and beyond. Hear Res 2012; 293:44-50. [PMID: 22560960 DOI: 10.1016/j.heares.2012.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 04/16/2012] [Accepted: 04/17/2012] [Indexed: 11/17/2022]
Abstract
Georg von Békésy was one of the first comparative auditory researchers. He not only studied basilar membrane (BM) movements in a range of mammals of widely different sizes, he also worked on the chicken basilar papilla and the frog middle ear. We show that, in mammals, at least, his data do not differ from those that could be collected using modern techniques but with the same, very loud sounds. There is in all cases a major difference to frequency maps collected using low-level sounds. In contrast, the same cannot be said of his chicken data, perhaps due to the different roles played by the BM in mammals and birds. In lizards, the BM is not tuned and it is perhaps good that Békésy did not begin with those species and get discouraged in his seminal comparative work.
Collapse
Affiliation(s)
- Geoffrey A Manley
- Cochlear and Auditory Brainstem Physiology, IBU, Faculty V, Carl von Ossietzky University Oldenburg, Carl von Ossietzky Strasse 9-11, 26129 Oldenburg, Germany.
| | | | | |
Collapse
|
12
|
Levic S, Bouleau Y, Dulon D. Developmental acquisition of a rapid calcium-regulated vesicle supply allows sustained high rates of exocytosis in auditory hair cells. PLoS One 2011; 6:e25714. [PMID: 21998683 PMCID: PMC3188563 DOI: 10.1371/journal.pone.0025714] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 09/08/2011] [Indexed: 11/19/2022] Open
Abstract
Auditory hair cells (HCs) have the remarkable property to indefinitely sustain high rates of synaptic vesicle release during ongoing sound stimulation. The mechanisms of vesicle supply that allow such indefatigable exocytosis at the ribbon active zone remain largely unknown. To address this issue, we characterized the kinetics of vesicle recruitment and release in developing chick auditory HCs. Experiments were done using the intact chick basilar papilla from E10 (embryonic day 10) to P2 (two days post-hatch) by monitoring changes in membrane capacitance and Ca(2+) currents during various voltage stimulations. Compared to immature pre-hearing HCs (E10-E12), mature post-hearing HCs (E18-P2) can steadily mobilize a larger readily releasable pool (RRP) of vesicles with faster kinetics and higher Ca(2+) efficiency. As assessed by varying the inter-pulse interval of a 100 ms paired-pulse depolarization protocol, the kinetics of RRP replenishment were found much faster in mature HCs. Unlike mature HCs, exocytosis in immature HCs showed large depression during repetitive stimulations. Remarkably, when the intracellular concentration of EGTA was raised from 0.5 to 2 mM, the paired-pulse depression level remained unchanged in immature HCs but was drastically increased in mature HCs, indicating that the Ca(2+) sensitivity of the vesicle replenishment process increases during maturation. Concomitantly, the immunoreactivity of the calcium sensor otoferlin and the number of ribbons at the HC plasma membrane largely increased, reaching a maximum level at E18-P2. Our results suggest that the efficient Ca(2+)-dependent vesicle release and supply in mature HCs essentially rely on the concomitant engagement of synaptic ribbons and otoferlin at the plasma membrane.
Collapse
Affiliation(s)
- Snezana Levic
- Equipe Neurophysiologie de la Synapse Auditive, Unité Mixte de Recherche, Inserm U587 et Université Victor Segalen, Institut des Neurosciences de Bordeaux, Centre Hospitalier Universitaire Pellegrin, Bordeaux, France
- * E-mail: (SL) (SL); (DD) (DD)
| | - Yohan Bouleau
- Equipe Neurophysiologie de la Synapse Auditive, Unité Mixte de Recherche, Inserm U587 et Université Victor Segalen, Institut des Neurosciences de Bordeaux, Centre Hospitalier Universitaire Pellegrin, Bordeaux, France
| | - Didier Dulon
- Equipe Neurophysiologie de la Synapse Auditive, Unité Mixte de Recherche, Inserm U587 et Université Victor Segalen, Institut des Neurosciences de Bordeaux, Centre Hospitalier Universitaire Pellegrin, Bordeaux, France
- * E-mail: (SL) (SL); (DD) (DD)
| |
Collapse
|
13
|
Gutiérrez-Ibáñez C, Iwaniuk AN, Wylie DR. Relative size of auditory pathways in symmetrically and asymmetrically eared owls. BRAIN, BEHAVIOR AND EVOLUTION 2011; 78:286-301. [PMID: 21921575 DOI: 10.1159/000330359] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 05/16/2011] [Indexed: 11/19/2022]
Abstract
Owls are highly efficient predators with a specialized auditory system designed to aid in the localization of prey. One of the most unique anatomical features of the owl auditory system is the evolution of vertically asymmetrical ears in some species, which improves their ability to localize the elevational component of a sound stimulus. In the asymmetrically eared barn owl, interaural time differences (ITD) are used to localize sounds in azimuth, whereas interaural level differences (ILD) are used to localize sounds in elevation. These two features are processed independently in two separate neural pathways that converge in the external nucleus of the inferior colliculus to form an auditory map of space. Here, we present a comparison of the relative volume of 11 auditory nuclei in both the ITD and the ILD pathways of 8 species of symmetrically and asymmetrically eared owls in order to investigate evolutionary changes in the auditory pathways in relation to ear asymmetry. Overall, our results indicate that asymmetrically eared owls have much larger auditory nuclei than owls with symmetrical ears. In asymmetrically eared owls we found that both the ITD and ILD pathways are equally enlarged, and other auditory nuclei, not directly involved in binaural comparisons, are also enlarged. We suggest that the hypertrophy of auditory nuclei in asymmetrically eared owls likely reflects both an improved ability to precisely locate sounds in space and an expansion of the hearing range. Additionally, our results suggest that the hypertrophy of nuclei that compute space may have preceded that of the expansion of the hearing range and evolutionary changes in the size of the auditory system occurred independently of phylogeny.
Collapse
|
14
|
Manley GA, Jones TA. The development and evolution of a tonotopic organization in the cochlea. Hear Res 2011; 277:1-3. [PMID: 21527326 DOI: 10.1016/j.heares.2011.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 04/12/2011] [Indexed: 11/20/2022]
|
15
|
Vergne AL, Pritz MB, Mathevon N. Acoustic communication in crocodilians: from behaviour to brain. Biol Rev Camb Philos Soc 2009; 84:391-411. [PMID: 19659884 DOI: 10.1111/j.1469-185x.2009.00079.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Crocodilians and birds are the modern representatives of Phylum Archosauria. Although there have been recent advances in our understanding of the phylogeny and ecology of ancient archosaurs like dinosaurs, it still remains a challenge to obtain reliable information about their behaviour. The comparative study of birds and crocodiles represents one approach to this interesting problem. One of their shared behavioural features is the use of acoustic communication, especially in the context of parental care. Although considerable data are available for birds, information concerning crocodilians is limited. The aim of this review is to summarize current knowledge about acoustic communication in crocodilians, from sound production to hearing processes, and to stimulate research in this field. Juvenile crocodilians utter a variety of communication sounds that can be classified into various functional categories: (1) "hatching calls", solicit the parents at hatching and fine-tune hatching synchrony among siblings; (2) "contact calls", thought to maintain cohesion among juveniles; (3) "distress calls", induce parental protection; and (4) "threat and disturbance calls", which perhaps function in defence. Adult calls can likewise be classified as follows: (1) "bellows", emitted by both sexes and believed to function during courtship and territorial defence; (2) "maternal growls", might maintain cohesion among offspring; and (3) "hisses", may function in defence. However, further experiments are needed to identify the role of each call more accurately as well as systematic studies concerning the acoustic structure of vocalizations. The mechanism of sound production and its control are also poorly understood. No specialized vocal apparatus has been described in detail and the motor neural circuitry remains to be elucidated. The hearing capabilities of crocodilians appear to be adapted to sound detection in both air and water. The ear functional anatomy and the auditory sensitivity of these reptiles are similar in many respects to those of birds. The crocodilian nervous system likewise shares many features with that of birds, especially regarding the neuroanatomy of the auditory pathways. However, the functional anatomy of the telencephalic auditory areas is less well understood in crocodilians compared to birds.
Collapse
Affiliation(s)
- A L Vergne
- Université de Saint-Etienne, Ecologie & Neuro-Ethologie Sensorielles EA3988, Saint-Etienne, France.
| | | | | |
Collapse
|
16
|
Schuck JB, Smith ME. Cell proliferation follows acoustically-induced hair cell bundle loss in the zebrafish saccule. Hear Res 2009; 253:67-76. [PMID: 19327392 DOI: 10.1016/j.heares.2009.03.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 03/11/2009] [Accepted: 03/16/2009] [Indexed: 10/21/2022]
Abstract
Fishes are capable of regenerating sensory hair cells in the inner ear after acoustic trauma. However, a time course of auditory hair cell regeneration has not been established for zebrafish. Adult zebrafish (Danio rerio) were exposed to a 100 Hz pure tone at 179 dB re 1 microPa RMS for 36 h and then allowed to recover for 0-14 days before morphological analysis. Hair cell bundle loss and recovery were determined using phalloidin to visualize hair bundles. Cell proliferation was quantified through bromodeoxyuridine (BrdU) labeling. Immediately following sound exposure, zebrafish saccules exhibited significant hair bundle damage (e.g., splayed, broken, and missing stereocilia) and loss (i.e., missing bundles and lesions in the epithelia) in the caudal region. Hair bundle counts increased over the course of the experiment, reaching pre-treatment levels at 14 days post-sound exposure (dpse). Low levels of proliferation were observed in untreated controls, indicating that some cells of the zebrafish saccule are mitotically active in the absence of a damaging event. In sound-exposed fish, cell proliferation peaked two dpse in the caudal region, and to a lesser extent in the rostral region. This proliferation was followed by an increase in numbers of cuticular plates with rudimentary stereocilia and immature-like hair bundles at 7 and 14 dpse, suggesting that at least some of the saccular cell proliferation resulted in newly formed hair cells. This study establishes a time course of hair cell bundle regeneration in the zebrafish inner ear and demonstrates that cell proliferation is associated with the regenerative process.
Collapse
Affiliation(s)
- Julie B Schuck
- Department of Biology and Biotechnology Center, Western Kentucky University, 1906 College Heights Blvd. #11080, Bowling Green, KY 42104-1080, USA
| | | |
Collapse
|
17
|
Miller MR, Beck J. Innervation of a lizard auditory organ having gap junctions between most hair cells: a serial transmission electron microscopy study. J Comp Neurol 2009; 293:223-35. [PMID: 19189713 DOI: 10.1002/cne.902930206] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Two apical unidirectional and 16 basal bidirectional papillar hair cells of the yucca night lizard, Xantusia vigilis, were serially sectioned for transmission electron microscopy (TEM) to determine the pattern of hair cell innervation. The 16 bidirectional hair cells (central group) were sectioned across the entire width of the papilla and consisted of four complete hair cells in each of the first three rows and the upper (or neural) half of the four hair cells in the fourth or last row. Both hair cell types were nonexclusively innervated, i.e., each afferent nerve fiber innervated two or more hair cells. The apical unidirectional hair cells were innervated by six or seven different afferent nerve fibers and five or six efferent fibers. The afferent nerve fibers made an average of 52.5 synapses/hair cell. In the central group of 16 bidirectional hair cells, 25 different afferent nerve fibers innervated an average of 4.5 hair cells. The average number of hair cells innervated by the eight afferent nerve fibers limited to the central group was 5.4. An unusual finding was the presence of gap junctions directly interconnecting more than half the hair cells in both papillar segments. In the bidirectional hair cell region, it was possible to count the number of gap junctions between 24 contiguous hair cells. The average number of gap junctions was four per hair cell, and all bidirectional hair cells were either directly or indirectly interconnected by gap junctions. The possible functions of a nonexclusive type of hair cell innervation and the presence of large numbers of gap junctions are discussed.
Collapse
Affiliation(s)
- M R Miller
- Department of Anatomy, University of California, San Francisco, California 94143, USA
| | | |
Collapse
|
18
|
Bergevin C, Freeman DM, Saunders JC, Shera CA. Otoacoustic emissions in humans, birds, lizards, and frogs: evidence for multiple generation mechanisms. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2008; 194:665-83. [PMID: 18500528 PMCID: PMC2562659 DOI: 10.1007/s00359-008-0338-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 04/18/2008] [Accepted: 04/19/2008] [Indexed: 10/22/2022]
Abstract
Many non-mammalian ears lack physiological features considered integral to the generation of otoacoustic emissions in mammals, including basilar-membrane traveling waves and hair-cell somatic motility. To help elucidate the mechanisms of emission generation, this study systematically measured and compared evoked emissions in all four classes of tetrapod vertebrates using identical stimulus paradigms. Overall emission levels are largest in the lizard and frog species studied and smallest in the chicken. Emission levels in humans, the only examined species with somatic hair cell motility, were intermediate. Both geckos and frogs exhibit substantially higher levels of high-order intermodulation distortion. Stimulus frequency emission phase-gradient delays are longest in humans but are at least 1 ms in all species. Comparisons between stimulus-frequency emission and distortion-product emission phase gradients for low stimulus levels indicate that representatives from all classes except frog show evidence for two distinct generation mechanisms analogous to the reflection- and distortion-source (i.e., place- and wave-fixed) mechanisms evident in mammals. Despite morphological differences, the results suggest the role of a scaling-symmetric traveling wave in chicken emission generation, similar to that in mammals, and perhaps some analog in the gecko.
Collapse
Affiliation(s)
- Christopher Bergevin
- Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Cambridge, MA, USA.
| | | | | | | |
Collapse
|
19
|
Crumling MA, Saunders JC. Tonotopic distribution of short-term adaptation properties in the cochlear nerve of normal and acoustically overexposed chicks. J Assoc Res Otolaryngol 2007; 8:54-68. [PMID: 17200911 PMCID: PMC2538420 DOI: 10.1007/s10162-006-0061-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Accepted: 10/18/2006] [Indexed: 10/23/2022] Open
Abstract
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+/-0.8 ms (mean+/-SEM). The number of spikes contributed by the adapting part of the response increased tonotopically for characteristic frequencies up to approximately 0.8 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.
Collapse
Affiliation(s)
- Mark A Crumling
- David Mahoney Institute of Neurological Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | | |
Collapse
|
20
|
Abstract
It is commonly held that hearing generally begins on incubation day 12 (E12) in the chicken embryo ( Gallus domesticus). However, little is known about the response properties of cochlear ganglion neurons for ages younger than E18. We studied ganglion neurons innervating the basilar papilla of embryos (E12–E18) and hatchlings (P13–P15). We asked first, when do primary afferent neurons begin to encode sounds? Second, when do afferents evidence frequency selectivity? Third, what range of characteristic frequencies (CFs) is represented in the late embryo? Finally, how does sound transfer from air to the cochlea affect responses in the embryo and hatchling? Responses to airborne sound were compared with responses to direct columella footplate stimulation of the cochlea. Cochlear ganglion neurons exhibited a profound insensitivity to sound from E12 to E16 (stages 39–42). Responses to sound and frequency selectivity emerged at about E15. Frequency selectivity matured rapidly from E16 to E18 (stages 42 and 44) to reflect a mature range of CFs (170–4,478 Hz) and response sensitivity to footplate stimulation. Limited high-frequency sound transfer from air to the cochlea restricted the response to airborne sound in the late embryo. Two periods of ontogeny are proposed. First is a prehearing period (roughly E12–E16) of endogenous cochlear signaling that provides neurotrophic support and guides normal developmental refinements in central binaural processing pathways followed by a period (roughly E16–E19) wherein the cochlea begins to detect and encode sound.
Collapse
Affiliation(s)
- Timothy A Jones
- Department of Communication Sciences and Disorders, School of Allied Health Sciences, East Carolina University, Greenville, NC 27858, USA.
| | | | | |
Collapse
|
21
|
Smittkamp SE, Durham D. Effect of cochlear integrity on cochlear nucleus neuron glucose metabolism in aged adult broiler chickens. Hear Res 2005; 202:209-21. [PMID: 15811713 DOI: 10.1016/j.heares.2004.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Accepted: 10/21/2004] [Indexed: 11/27/2022]
Abstract
Abrupt removal of excitatory input is devastating to post-synaptic neurons in normally functioning sensory systems. In both mammalian and avian auditory systems, abrupt temporary or permanent experimental deafferentation stimulates a cascade of changes in central auditory structures that can result in neuron death. Effects of naturally occurring progressive deafferentation on central auditory structure and function have not been fully described. Extensive naturally occurring cochlear damage is found in some aged chickens, despite their regenerative capacity, providing the opportunity to examine the effects of this type of deafferentation on the avian cochlear nucleus (nucleus magnocellularis, NM). Previous evaluation of NM oxidative metabolism using cytochrome oxidase histochemistry revealed that naturally occurring cochlear damage results in down-regulated metabolism in corresponding regions of NM. It is unknown how progressive hair cell damage and loss affects NM glucose uptake. Here, NM glucose metabolism is assessed using 2-deoxyglucose uptake as a marker for metabolic activity in the presence of normal, mildly damaged, severely damaged, and totally damaged cochlear hair cells. Results indicate that while severe and total cochlear damage significantly decrease NM oxidative metabolism, only total damage results in significantly decreased NM glucose metabolism. Results are discussed in the context of functional reorganization and trophic support.
Collapse
Affiliation(s)
- Susan E Smittkamp
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, 66160, USA
| | | |
Collapse
|
22
|
Gleich O, Fischer FP, Köppl C, Manley GA. Hearing Organ Evolution and Specialization: Archosaurs. EVOLUTION OF THE VERTEBRATE AUDITORY SYSTEM 2004. [DOI: 10.1007/978-1-4419-8957-4_8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
|
23
|
Molea D, Rubel EW. Timing and topography of nucleus magnocellularis innervation by the cochlear ganglion. J Comp Neurol 2003; 466:577-91. [PMID: 14566951 DOI: 10.1002/cne.10896] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This series of experiments examined the arrival and organization of cochlear nerve axons in the primary auditory brainstem nucleus, nucleus magnocellularis (NM), of the chick. DiI and DiD were injected into the cochlear nerve, cochlear ganglion, and basilar papilla (i.e., avian cochlea) in fixed tissue and labeled axons were studied in NM and its vicinity. Cochlear nerve axons first penetrate NM between stages 29 (E6) and 36 (E10). Axons penetrate NM in a middle-to-posterior-to-anterior developmental sequence; the anterior, high-frequency region of NM receives axons last. When cochlear nerve axons arrive in the NM, they are already organized in a topographic map related to the position of their cell bodies along the basilar papilla, foreshadowing the tonotopic mapping observed between NM and the basilar papilla later in development. Evidence of a topographic map was also observed in the other primary auditory brainstem nucleus, nucleus angularis. These results indicate that topographic mapping of position (and ultimately characteristic frequency) between the basilar papilla and NM is established as cochlear nerve axons arrive in the NM prior to the onset of synaptic activity. .
Collapse
Affiliation(s)
- David Molea
- Virginia Merrill Bloedel Hearing Research Center, Department of Physiology and Biophysics, Department of Otolaryngology-HNS, University of Washington, Seattle, Washington 98195-7923, USA
| | | |
Collapse
|
24
|
Duncan RK, Fuchs PA. Variation in large-conductance, calcium-activated potassium channels from hair cells along the chicken basilar papilla. J Physiol 2003; 547:357-71. [PMID: 12562934 PMCID: PMC2342658 DOI: 10.1113/jphysiol.2002.029785] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The mechanism for electrical tuning in non-mammalian hair cells rests within the widely diverse kinetics of functionally distinct, large-conductance potassium channels (BK), thought to result from alternative splicing of the pore-forming alpha subunit and variable co-expression with an accessory beta subunit. Inside-out patches from hair cells along the chicken basilar papilla revealed 'tonotopic' gradations in calcium sensitivity and deactivation kinetics. The resonant frequency for the hair cell from which the patch was taken was estimated from deactivation rates, and this frequency reasonably matched that predicted from the originating cell's tonotopic location. The rates of deactivation for native BK channels were much faster than rates reported for cloned chicken BK channels including both alpha and beta subunits. This result was surprising since patches were pulled from hair cells in the apical half of the papilla where beta subunits are most highly expressed. Heterogeneity in the properties of native chicken BK channels implies a high degree of molecular variation and hinders our ability to identify those molecular constituents.
Collapse
Affiliation(s)
- R K Duncan
- Department of Otolaryngology: Head and Neck Surgery, Johns Hopkins University, 521 Traylor Building, 720 Rutland Avenue, Baltimore, MD 21205, USA.
| | | |
Collapse
|
25
|
Pantelias AA, Monsivais P, Rubel EW. Tonotopic map of potassium currents in chick auditory hair cells using an intact basilar papilla. Hear Res 2001; 156:81-94. [PMID: 11377884 DOI: 10.1016/s0378-5955(01)00269-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The avian basilar papilla is tonotopically organized such that hair cells along the sensory epithelium respond best to acoustic stimulation at differing frequencies. This specificity arises due to the mechanics of the cochlea itself and intrinsic electrical properties of the hair cells. Tall hair cells show membrane voltage oscillations in response to step current injection that may allow cells to act as electrical resonators, boosting the response at the resonant frequency. These oscillations and the underlying currents have been studied in enzymatically isolated cells. This study uses a whole chick (Gallus domesticus) basilar papilla preparation where the entire epithelium and its afferent connections are intact. With this preparation, a map of changes in potassium currents of tall hair cells was produced. All cells recorded from expressed two K+ currents, a calcium-activated K+ current, I(K(Ca)), and a voltage-activated K+ current, I(K). Also, apical cells expressed an inward rectifier K+ current, I(IR). The amplitude of total outward current increases in a gradient along the tonotopic axis. Pharmacological blockers were used to separate the outward K+ currents. These experiments showed that both currents individually increase in magnitude along a gradient from apex to base. Finally, measurements of oscillation frequency in response to current steps suggest a discontinuous change in the electrical resonances at about 33% from the apex. This study demonstrates a new preparation to study the electrical properties of hair cells in more detail along the tonotopic axis of the chick basilar papilla.
Collapse
Affiliation(s)
- A A Pantelias
- Virginia Merrill Bloedel Hearing Research Center and Department of Otolaryngology-Head and Neck Surgery, P.O. Box 357923 CHDD CD 176, University of Washington, Seattle, WA 98195, USA
| | | | | |
Collapse
|
26
|
Lang H, Fekete DM. Lineage Analysis in the Chicken Inner Ear Shows Differences in Clonal Dispersion for Epithelial, Neuronal, and Mesenchymal Cells. Dev Biol 2001; 234:120-37. [PMID: 11356024 DOI: 10.1006/dbio.2001.0248] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The epithelial components of the vertebrate inner ear and its associated ganglion arise from the otic placode. The cell types formed include neurons, hair-cell mechanoreceptors, supporting cells, secretory cells that make endolymphatic fluid or otolithic membranes, and simple epithelial cells lining the fluid-filled cavities. The epithelial sheet is surrounded by an inner layer of connective and vascular tissues and an outer capsule of bone. To explore the mechanisms of cell fate specification in the ear, retrovirus-mediated lineage analysis was performed after injecting virus into the chicken otocyst on embryonic days 2.5-5.5. Because lineage analysis might reveal developmental compartments, an effort was made to study clonal dispersion by sampling infected cells from different parts of the same ear, including the auditory ganglion, cochlea, saccule, utricle, and semicircular canals. Lineage relationships were confirmed for 75 clones by amplification and sequencing of a variable DNA tag carried by each virus. While mesenchymal clones could span different structural parts of the ear, epithelial clones did not. The circumscribed epithelial clones indicated that their progenitors were not highly migratory. Ganglion cell clones, in contrast, were more dispersed. There was no evidence for a common lineage between sensory cells and their associated neurons, a prediction based on a proposal that the ear sensory organs and fly mechanosensory organs are evolutionarily homologous. As expected, placodal derivatives were unrelated to adjacent mesenchymal cells or to nonneuronal cells of the ganglion. Within the otic capsule, fibroblasts and cartilage cells could be related by lineage.
Collapse
Affiliation(s)
- H Lang
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, 47907-1392, USA
| | | |
Collapse
|
27
|
Woolley SM, Wissman AM, Rubel EW. Hair cell regeneration and recovery of auditory thresholds following aminoglycoside ototoxicity in Bengalese finches. Hear Res 2001; 153:181-95. [PMID: 11223308 DOI: 10.1016/s0378-5955(00)00217-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Birds regenerate auditory hair cells when original hair cells are lost. Regenerated hair cells become innervated and restore hearing function. Functional recovery during hair cell regeneration is particularly interesting in animals that depend on hearing for vocal communication. Bengalese finches are songbirds that depend on auditory feedback for normal song learning and maintenance. We examined the structural and functional recovery of the Bengalese finch basilar papilla after aminoglycoside ototoxicity. Birds were treated with the ototoxic aminoglycoside, amikacin, daily for 1 week. Treatment resulted in hair cell loss across the basal half of the basilar papilla and corresponding high frequency hearing loss. Hair cell regeneration and recovery of auditory brainstem responses were compared in the same animals. Survival times following treatment were between 1 day and 12 weeks. Analysis of structural recovery at weekly intervals indicated that hair cells in the Bengalese finch papilla require a maximum of 1 week to regenerate and appear with immature morphology at the epithelial surface. An additional 6 days are required for adult-like morphology to develop. Repopulation of the damaged region was complete by 8 weeks. Recovery of auditory thresholds began 1 week after treatment and reached asymptote by 4 weeks. Slight residual threshold shifts at 2.0 kHz and above were observed up to 12 weeks after treatment. Direct comparison of structural and functional recovery indicates that auditory thresholds recover maximally before a full complement of hair cells has regenerated.
Collapse
Affiliation(s)
- S M Woolley
- Neurobiology and Behavior Program, Department of Otolaryngology-HNS and Virginia Merrill Bloedel Hearing Research Center, P.O. Box 357923, University of Washington, Seattle, WA 98195, USA
| | | | | |
Collapse
|
28
|
beta subunits modulate alternatively spliced, large conductance, calcium-activated potassium channels of avian hair cells. J Neurosci 2000. [PMID: 10684869 DOI: 10.1523/jneurosci.20-05-01675.2000] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Electrical tuning confers frequency selectivity onto sensory hair cells in the auditory periphery of frogs, turtles, and chicks. The resonant frequency is determined in large part by the number and kinetics of large conductance, calcium-activated potassium (BK) channels. BK channels in hair cells are encoded by the alternatively spliced slo gene and may include an accessory beta subunit. Here we examine the origins of kinetic variability among BK channels by heterologous expression of avian cochlear slo cDNAs. Four alternatively spliced forms of the slo-alpha gene from chick hair cells were co-expressed with accessory beta subunits (from quail cochlea) by transient transfection of human embryonic kidney 293 cells. Addition of the beta subunit increased steady-state calcium affinity, raised the Hill coefficient for calcium binding, and slowed channel deactivation rates, resulting in eight functionally distinct channels. For example, a naturally occurring splice variant containing three additional exons deactivated 20-fold more slowly when combined with beta. Deactivation kinetics were used to predict tuning frequencies and thus tonotopic location if hair cells were endowed with each of the expressed channels. All beta-containing channels were predicted to lie within the apical (low-frequency) 30% of the epithelium, consistent with previous in situ hybridization studies. Individual slo-alpha exons would be found anywhere within the apical 70%, depending on the presence of beta, and other alternative exons. Alternative splicing of the slo-alpha channel message provides intrinsic variability in gating kinetics that is expanded to a wider range of tuning by modulation with beta subunits.
Collapse
|
29
|
Abstract
Statoacoustic ganglion cells in the mature bird include neurons that are responsive to sound (auditory) and those that are not (nonauditory). Those that are nonauditory have been shown to innervate an otolith organ, the macula lagena, whereas auditory neurons innervate the basilar papilla. In the present study, single-unit recordings of statoacoustic ganglion cells were made in embryonic (E19, mean = 19.2 days of incubation) and hatchling (P6-P14, mean = 8.6 days posthatch) chickens. Spontaneous activity from the two age groups was compared with developmental changes. Activity was evaluated for 47 auditory, 11 nonauditory, and 6 undefined eighth nerve neurons in embryos and 29 auditory, 26 nonauditory, and 1 undefined neurons in hatchlings. For auditory neurons, spontaneous activity displayed an irregular pattern [discharge interval coefficient of variation (CV) was >0.5, mean CV for embryos was 1.46 +/- 0.58 and for hatchlings was 1.02 +/- 0.25; means +/- SD]. Embryonic discharge rates ranged from 0.05 to 97.6 spikes per second (sp/s) for all neurons (mean 18.6 +/- 16.9 sp/s). Hatchling spontaneous rates ranged from 1.2 to 185.2 sp/s (mean 66.5 +/- 39.6 sp/s). Discharge rates were significantly higher for hatchlings (P < 0.001). Many embryonic auditory neurons displayed long silent periods between irregular bursts of neural activity, a feature not seen posthatch. All regular bursting discharge patterns were correlated with heart rate in both embryos and hatchlings. Preferred intervals were visible in the time interval histograms (TIHs) of only one embryonic neuron in contrast to 55% of the neurons in posthatch animals. Generally, the embryonic auditory TIH displayed a modified quasi-Poisson distribution. Nonauditory units generally displayed regular (CV <0.5) or irregular (CV >0.5) activity and Gaussian and modified-Gaussian TIHs. Long silent periods or bursting patterns were not a characteristic of embryonic nonauditory neurons. CV varied systematically as a function of discharge rate in nonauditory but not auditory primary afferents. Minimum spike intervals (dead time) and interval modes for auditory neurons were longer in embryos (dead time: embryos 2.88 +/- 6.85 ms; hatchlings 1.50 +/- 1.76 ms; modal intervals: embryo 10.09 +/- 22.50 ms, hatchling 3.54 +/- 3.29 ms). The results show that significant developmental changes occur in spontaneous activity between E19 and posthatch. It is likely that both presynaptic and postsynaptic changes in the neuroepithelium contribute to maturational refinements during this period of development.
Collapse
Affiliation(s)
- T A Jones
- Department of Surgery/Otolaryngology, School of Medicine, University of Missouri-Columbia, Columbia, Missouri 65212, USA
| | | |
Collapse
|
30
|
|
31
|
Abstract
A published model of the frequency responses of different locations on the basilar papilla of the Tokay gecko Gekko gecko (Authier and Manley, 1995. Hear. Res. 82, 1-13) had implied that (a) unlike all other amniotes studied so far, the frequency map is reversed, with the low frequencies at the base and the high frequencies at the apex, and (b) the high-frequency area is split into two parallel-lying hair cell areas covering different frequency ranges. To test these hypotheses, the frequency representation along the basilar papilla of Gekko gecko was studied by recording from single auditory afferent nerve fibers and labelling them iontophoretically with horseradish peroxidase. Successfully labelled fibers covered a range of characteristic frequencies from 0.42 to 4.9 kHz, which extended from 78% to 9% of the total papillar length, as measured from the apex. The termination sites of labelled fibers within the basilar papilla correlated with their characteristic frequency, the lowest frequencies being represented basally, and the highest apically. This confirms the first prediction of the model. The map indicates, however, that one of the two high-frequency papillar regions (the postaxial segment) represents the full high-frequency range, from about 1 to 5 kHz. No functionally identified labelling was achieved in the preaxial segment. Thus the assumptions underlying the proposed model need revision. A good mathematical description of the frequency distribution was given by an exponential regression with a mapping constant in the living state of approximately 0.4 mm/octave.
Collapse
Affiliation(s)
- G A Manley
- Institut für Zoologie der Technischen Universität München, Garching, Germany.
| | | | | |
Collapse
|
32
|
Müller M, Smolders JW. Responses of auditory nerve fibers innervating regenerated hair cells after local application of gentamicin at the round window of the cochlea in the pigeon. Hear Res 1999; 131:153-69. [PMID: 10355612 DOI: 10.1016/s0378-5955(99)00029-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hair cells in the basilar papilla of birds have the capacity to regenerate after injury. There is also functional recovery of hearing after regeneration of the hair cells. The present study was undertaken to determine the effect of local aminoglycoside application on the physiology of auditory nerve fibers innervating regenerated hair cells. Collagen sponges loaded with gentamicin were placed at the round window of the cochlea in adult pigeons. The local application of gentamicin-loaded collagen sponges resulted in total hair cell loss over at least the basal 62% of the basilar papilla. According to the pigeon cochlear place-frequency map (Smolders, Ding-Pfennigdorff and Klinke, Hear. Res. 92 (1995) 151-169), frequencies above 0.3 kHz are represented in this area. Physiological data on single auditory nerve fibers were obtained 14 weeks after gentamicin treatment. The response properties showed the following characteristics when compared to control data: CF thresholds (CF = characteristic frequency) were elevated in units with CF above 0.15 kHz, sharpness of tuning (Q10dB) was reduced in units with CF above 0.38 kHz, low-frequency slopes of the tuning curves were reduced in units with CF above 0.25 kHz, high frequency slopes of the tuning curves were reduced in units with CF above 0.4 kHz, spontaneous firing rate was reduced in units with CF above 0.38 kHz, dynamic range of rate-intensity functions at CF was reduced in units with CF above 0.4 kHz and the slopes of these rate-intensity functions were elevated in units with CF above 0.4 kHz. Maximum discharge rate was the only parameter that remained unchanged in regenerated ears. The results show that the response properties of auditory nerve fibers which innervate areas of the papilla that were previously devoid of hair cells are poorer than the controls, but that action potential generation in the afferent fibers is unaffected. This suggests that despite structural regeneration of the basilar papilla, functional recovery of the auditory periphery is incomplete at the level of the hair cell or the hair cell-afferent synapse.
Collapse
Affiliation(s)
- M Müller
- Klinikum der J.W. Goethe-Universität, Physiologisches Institut III, Frankfurt am Main, Germany
| | | |
Collapse
|
33
|
Abstract
Male Bengalese finches do not normally change their vocal patterns in adulthood; song is stereotyped and stable over time. Adult song maintenance requires auditory feedback. If adults are deafened, song will degrade within 1 week. We tested whether feedback of all sound frequencies is required for song maintenance. The avian basilar papilla is tonotopically organized; hair cells in the basal region encode high frequencies, and low frequencies are encoded in progressively apical regions. We restricted the spectral range of feedback available to a bird by killing either auditory hair cells encoding higher frequencies or those encoding both high and low frequencies and documented resultant changes in song. Birds were treated with either Amikacin alone to kill high-frequency hair cells or Amikacin and sound exposure to target hair cells across the entire papilla. During treatment, song was recorded from all birds weekly. After treatment and song recording, evoked-potential audiograms were evaluated on each bird, and papillas were evaluated by scanning electron microscopy. Results showed that hair cell damage over 46-63% of the basal papilla and the corresponding high-frequency hearing loss had no effect on song structure. In birds with hair cell damage extending further into the apical region of the papilla and corresponding low-frequency and high-frequency hearing loss, song degradation occurred within 1 week of beginning treatment and was comparable with degradation after surgical deafening. We conclude that either low-frequency spectral cues or temporal cues via feedback of the song amplitude envelope are sufficient for song maintenance in adult Bengalese finches.
Collapse
|
34
|
Park DL, Girod DA, Durham D. Evidence for loss and recovery of chick brainstem auditory neurons during gentamicin-induced cochlear damage and regeneration. Hear Res 1998; 126:84-98. [PMID: 9872137 DOI: 10.1016/s0378-5955(98)00157-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
It is well documented that damage to the chick cochlea caused by acoustic overstimulation or ototoxic drugs is reversible. Second-order auditory neurons in nucleus magnocellularis (NM) are sensitive to changes in input from the cochlea. However, few experiments studying changes in NM during cochlear hair cell loss and regeneration have been reported. Chicks were given a single systemic dose of gentamicin, which results in maximal hair cell loss in the base of the cochlea after 5 days. Many new hair cells are present by 9 days. These new hair cells are mature but not completely recovered in organization by 70 days. We counted neurons in Nissl-stained sections of the brainstem within specific tonotopic regions of NM, comparing absolute cell number between gentamicin- and saline-treated animals at both short and long survival times. Our data suggest that neuronal number in rostral NM parallels hair cell number in the base of the cochlea. That is, after a single dose of gentamicin, we see a loss of both cochlear hair cells and NM neurons early, followed by a recovery of both cochlear hair cells and NM neurons later. These results suggest that neurons, like cochlear hair cells, can recover following gentamicin-induced damage.
Collapse
Affiliation(s)
- D L Park
- Department of Otolaryngology and the Smith Mental Retardation Research Center, University of Kansas Medical Center, Kansas City, 66160-7380, USA
| | | | | |
Collapse
|
35
|
Shero M, Salvi RJ, Chen L, Hashino E. Excitotoxic effect of kainic acid on chicken cochlear afferent neurons. Neurosci Lett 1998; 257:81-4. [PMID: 9865932 DOI: 10.1016/s0304-3940(98)00821-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The excitotoxic effects of kainic acid, a glutamate analog, on the auditory neurons in the chicken cochlea were assessed by light and transmission electron microscopy. Kainic acid was directly applied onto the round window of adult chickens and their cochleas were harvested 3 h after application. Transverse microscopic sections of the basilar papilla revealed swelling of afferent dendrites without any morphological changes in efferent endings. The regions of the basilar papilla damaged by kainic acid were localized in the apical 80% and primarily on the neural side where tall hair cells are located. The basal, abneural short hair cell region was devoid of damage. These results imply that glutamate is a primary neurotransmitter in chicken auditory afferent neurons that synapse on tall hair cells.
Collapse
Affiliation(s)
- M Shero
- Center for Hearing and Deafness, State University of New York at Buffalo, 14214, USA
| | | | | | | |
Collapse
|
36
|
Abstract
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.
Collapse
Affiliation(s)
- D M Mills
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology, Head and Neck Surgery, University of Washington, Seattle 98195-7923, USA.
| | | |
Collapse
|
37
|
Abstract
The emu, being a member of the rather primitive bird group of the palaeognathid Ratitae, may reveal primitives features of the avian basilar papilla. There are, however, no qualitative differences with the papillae of other birds such as the chicken or the starling. There are only quantitative differences in the continuous morphological gradients (such as hair cell height, stereovillar height) from neural to abneural, and from the base to the apex of the papilla. Only few (about two in the emu) afferent terminals and on average one efferent fiber contact each hair cell. Along the abneural edge, there is a population of hair cells that lack afferent innervation (short hair cells), suggesting that their function must lie in the papilla itself. There is thus a general pattern in the structures of the avian basilar papilla. In detail, however, a number of primitive characters were observed in the emu, as compared to advanced birds such as the starling and the barn owl. The hair cells are very densely packed and comparatively tall (up to 40 microm in the apex). This anatomy correlates well with the good lower-frequency hearing (see Köppl and Manley, J. Acoust. Soc. Am. 101 (1997) 1574 1584). The afferent nerve fibers contacting the hair cells within the basilar papilla are rather thick, and there are a large number of afferent fibers that contact more than one hair cell. The zone of hair cells without afferent innervation (short hair cells) along the abneural edge of the basilar papilla is rather narrow in the emu.
Collapse
Affiliation(s)
- F P Fischer
- Institut für Zoologie, Technische Universität München, Garching, Germany.
| |
Collapse
|
38
|
Heil P, Irvine DR. Functional specialization in auditory cortex: responses to frequency-modulated stimuli in the cat's posterior auditory field. J Neurophysiol 1998; 79:3041-59. [PMID: 9636107 DOI: 10.1152/jn.1998.79.6.3041] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The mammalian auditory cortex contains multiple fields but their functional role is poorly understood. Here we examine the responses of single neurons in the posterior auditory field (P) of barbiturate- and ketamine-anesthetized cats to frequency-modulated (FM) sweeps. FM sweeps traversed the excitatory response area of the neuron under study, and FM direction and the linear rate of change of frequency (RCF) were varied systematically. In some neurons, sweeps of different sound pressure levels (SPLs) also were tested. The response magnitude (number of spikes corrected for spontaneous activity) of nearly all field P neurons varied with RCF. RCF response functions displayed a variety of shapes, but most functions were of low-pass characteristic or peaked at rather low RCFs (<100 kHz/s). Neurons with strong responses to high RCFs (high-pass or nonselective RCF response function characteristics) all displayed spike count-SPL functions to tone burst onsets that were monotonic or weakly nonmonotonic. RCF response functions and best RCFs often changed with SPL. For most neurons, FM directional sensitivity, quantified by a directional sensitivity (DS) index, also varied with RCF and SPL, but the mean and width of the distribution of DS indices across all neurons was independent of RCF. Analysis of response timing revealed that the phasic response of a neuron is triggered when the instantaneous frequency of the sweep reaches a particular value, the effective Fi. For a given neuron, values of effective Fi were independent of RCF, but depended on FM direction and SPL and were associated closely with the boundaries of the neuron's frequency versus amplitude response area. The standard deviation (SD) of the latency of the first spike of the response decreased with RCF. When SD was expressed relative to the rate of change of stimulus frequency, the resulting index of frequency jitter increased with RCF and did so rather uniformly in all neurons and largely independent of SPL. These properties suggest that many FM parameters are represented by, and may be encoded in, orderly temporal patterns across different neurons in addition to the strength of responses. When compared with neurons in primary and anterior auditory fields, field P neurons respond better to relatively slow FMs. Together with previous studies of responses to modulations of amplitude, such as tone onsets, our findings suggest more generally that field P may be best suited for processing signals that vary relatively slowly over time.
Collapse
Affiliation(s)
- P Heil
- Department of Psychology, Monash University, Clayton, Victoria 3168, Australia
| | | |
Collapse
|
39
|
Müller M, Smolders JW. Hair cell regeneration after local application of gentamicin at the round window of the cochlea in the pigeon. Hear Res 1998; 120:25-36. [PMID: 9667428 DOI: 10.1016/s0378-5955(98)00049-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Hair cells in the basilar papilla of birds have the capacity to regenerate after injury. Methods commonly used to induce cochlear damage are systemic application of ototoxic substances such as aminoglycoside antibiotics or loud sound. Both methods have disadvantages. The systemic application of antibiotics results in damage restricted to the basal 50% of the papilla and has severe side effects on the kidneys. Loud sound damages only small parts of the papilla and is restricted to the short hair cells. The present study was undertaken to determine the effect of local aminoglycoside application on the physiology and morphology of the avian basilar papilla. Collagen sponges loaded with gentamicin were placed at the round window of the cochlea in adult pigeons. The time course of hearing thresholds was determined from auditory brain stem responses elicited with pure tone bursts within a frequency range of 0.35-5.565 kHz. The condition of the basilar papilla was determined from scanning electron micrographs. Five days after application of the collagen sponges loaded with gentamicin severe hearing loss, except for the lowest frequency tested, was observed. Only at the apical 20% of the basilar papilla hair cells were left intact, all other hair cells were missing or damaged. At all frequencies there was little functional recovery until day 13 after implantation. At frequencies above 1 kHz functional recovery occurred at a rate of up to 4 dB/day until day 21, beyond that day recovery continued at a rate below 1 dB/day until day 48 at the 5.6 kHz. Below 1 kHz recovery occurred up to day 22, the recovery rate was below 2 dB/day. A residual hearing loss of about 15-25 dB remained at all frequencies, except for the lowest frequency tested. At day 20 new hair cells were seen on the basilar papilla. At day 48 the hair cells appeared to have recovered fully, except for the orientation of the hair cell bundles. The advantage of the local application of the aminoglycoside drug over systemic application is that it damages almost all hair cells in the basilar papilla and it has no toxic side effects. The damage is more extensive than with systemic application.
Collapse
MESH Headings
- Acoustic Stimulation
- Animals
- Anti-Bacterial Agents
- Audiometry
- Auditory Threshold/drug effects
- Auditory Threshold/physiology
- Basilar Membrane/drug effects
- Basilar Membrane/ultrastructure
- Collagen
- Columbidae/physiology
- Evoked Potentials, Auditory, Brain Stem/drug effects
- Evoked Potentials, Auditory, Brain Stem/physiology
- Gentamicins
- Hair Cells, Auditory/drug effects
- Hair Cells, Auditory/pathology
- Hearing Loss, Sensorineural/chemically induced
- Microscopy, Electron, Scanning
- Nerve Regeneration/physiology
- Round Window, Ear/drug effects
- Round Window, Ear/ultrastructure
Collapse
Affiliation(s)
- M Müller
- Klinikum der J.W. Goethe-Universität, Physiologisches Institut III, Frankfurt am Main, Germany.
| | | |
Collapse
|
40
|
Rübsamen R, Lippe WR. The Development of Cochlear Function. DEVELOPMENT OF THE AUDITORY SYSTEM 1998. [DOI: 10.1007/978-1-4612-2186-9_5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
41
|
Rosenblatt KP, Sun ZP, Heller S, Hudspeth AJ. Distribution of Ca2+-activated K+ channel isoforms along the tonotopic gradient of the chicken's cochlea. Neuron 1997; 19:1061-75. [PMID: 9390519 DOI: 10.1016/s0896-6273(00)80397-9] [Citation(s) in RCA: 177] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In some cochleae, the number and kinetic properties of Ca2+-activated K+ (KCa) channels partly determine the characteristic frequency of each hair cell and thus help establish a tonotopic map. In the chicken's basilar papilla, we found numerous isoforms of KCa channels generated by alternative mRNA splicing at seven sites in a single gene, cSlo. In situ polymerase chain reactions demonstrated cSlo expression in hair cells and revealed differential distributions of KCa channel isoforms along the basilar papilla. Analysis of single hair cells by the reverse transcription polymerase chain reaction confirmed the differential expression of channel variants. Heterologously expressed cSlo variants differed in their sensitivities to Ca2+ and voltage, suggesting that the distinct spatial distributions of cSlo variants help determine the tonotopic map.
Collapse
Affiliation(s)
- K P Rosenblatt
- Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, The Rockefeller University, New York, New York 10021-6399, USA
| | | | | | | |
Collapse
|
42
|
Müller M, Smolders JW, Ding-Pfennigdorff D, Klinke R. Discharge properties of pigeon single auditory nerve fibers after recovery from severe acoustic trauma. Int J Dev Neurosci 1997; 15:401-16. [PMID: 9263022 DOI: 10.1016/s0736-5748(96)00100-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The time course of recovery of compound action potential (CAP) thresholds was observed in individual adult pigeons after severe acoustic trauma. Each bird had electrodes implanted on the round window of both ears. One ear was exposed to a tone of 0.7 kHz at 136-142 dB SPL for 1 hr under general anesthesia. Recovery of CAP audiograms was monitored twice a week after trauma. Single unit recordings from auditory nerve fibers were made after 3 weeks and after 4 or more months of the exposure. The CAP was abolished immediately after overstimulation in all animals. Based on the temporal patterns of functional recovery of the CAP three groups of animals were identified. The first group was characterized by fast functional recovery starting immediately after trauma followed by a return to pre-exposure values within 3 weeks. In the second group, slow functional recovery of threshold started 1-2 weeks after trauma followed by a return to pre-exposure values by 4-5 weeks. A mean residual hearing loss of 26.3 dB at 2 kHz remained. The third group consisted of animals that did not recover after trauma. Three weeks after the exposure, tuning curves of single auditory nerve fibers were very broad and sometimes irregular in shape. Their thresholds hovered around 120 dB SPL. Spontaneous firing rate and driven rate were much reduced. Four or more months after exposure, the thresholds and sharpness of tuning of many single units were almost completely recovered. Spontaneous firing rate and driven rate were comparable to those of control animals. In the slow recovery group neuronal tuning properties showed less recovery, especially at frequencies above the exposure frequency. Thresholds and sharpness of tuning were normal at frequencies below the exposure frequency, but were much poorer at frequencies above the exposure. Spontaneous firing rate was much reduced in fibers with high characteristic frequencies. In fast recovering animals, the papilla was repopulated with hair cells after 4 months. In slow recovering animals, short (abneural) hair cells were still missing over large parts of the papilla after 4 months of recovery. Residual short (abneural) hair cell loss was largest at two areas, one more basal and the other more apical to the characteristic place of the traumatizing frequency. The results show that, in adult birds, functional recovery from severe damage to both short (abneural) and tall (neural) hair cells occurs. However, the onset of recovery is delayed and the time course is slower than after destruction of short (abneural) hair cells alone. Also, recovery is incomplete, both functionally and morphologically. There is residual permanent hearing loss, and regeneration of short (abneural) hair cells is incomplete.
Collapse
Affiliation(s)
- M Müller
- Klinikum der J. W. Goethe-Universität, Zentrum der Physiologie, Frankfurt am Main, Germany
| | | | | | | |
Collapse
|
43
|
|
44
|
Abstract
During the early development of the bird and the mammalian peripheral auditory system, a restricted range of low--mid frequencies is recorded in immature animals. These early recordings are correlated to the base or mid-basal region of the cochlea which codes high frequencies in the adult. In order to reconcile the functional observations with anatomical ones, two main hypotheses have been put forward: one called the development of the place principle derived from observations of acoustic trauma in chick cochlea and a second derived from auditory nerve fiber recordings in kittens. Whatever the theories, the tonotopic shift during development is a well-established phenomenon in both birds and mammals that could be explained by a synthetic theory including active and passive cochlear processes. The tonotopic shift observed in the central auditory system mimics quite closely the frequency representation of the peripheral auditory system. The same trend is observed in all auditory nuclei including the cortex, except that the frequency representation is more complex because it shows tonotopic maps that can be twisted in three dimensions. From current observations, there is a simultaneous onset of tonotopic maps across auditory nuclei up to the cortex. A hypothesis is presented related to the frequency changes observed in the cochlea that affect the central auditory pathway, along with possible consequences on auditory behavior.
Collapse
Affiliation(s)
- R Romand
- Laboratorie de Neurobiologie, Université Blaise Pascal-Clermont II, Aubière, France
| |
Collapse
|
45
|
Müller M, Smolders JW, Ding-Pfennigdorff D, Klinke R. Regeneration after tall hair cell damage following severe acoustic trauma in adult pigeons: correlation between cochlear morphology, compound action potential responses and single fiber properties in single animals. Hear Res 1996; 102:133-54. [PMID: 8951458 DOI: 10.1016/s0378-5955(96)00155-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The time course of recovery of compound action potential (CAP) thresholds was observed in individual adult pigeons after severe acoustic trauma. Pigeons were overstimulated with a tone of 0.7 kHz and 136-142 dB SPL presented to one ear for 1 h under general anesthesia. Recovery of CAP audiograms was monitored at regular intervals after trauma. A new semi-stereotaxic approach to the peripheral part of the auditory nerve was developed. This permitted activity from single auditory nerve fibers to be recorded over a wide range of characteristic frequencies (CFs), including high CFs, without having to open the inner ear. Single unit recordings were made after three weeks and after 4 or more months of recovery. The time course of recovery, the single unit properties, and the morphological status of the basilar papilla were correlated. The CAP was abolished in all animals after overstimulation. Three groups of animals were identified according to the functional recovery of the CAP thresholds recorded at regular intervals with implanted electrodes: Group 1: Fast functional recovery starting immediately after trauma, followed by recovery to pre-exposure values within 3 weeks. Group 2: Slow functional recovery of threshold starting 1-2 weeks after trauma and ending 4-5 weeks after trauma. A mean residual hearing loss of 26.3 dB at 2 kHz remained. Group 3: No recovery of CAP thresholds up to 8 months after trauma. Three weeks after trauma, very few responsive neurons were found in groups 2 and 3. Tuning curves were very broad and sometimes irregular in shape. Thresholds were very high, around 120 dB SPL. Spontaneous firing rate was much reduced, especially in neurons with high CFs. After 4 or more months of recovery, the response properties of single units in group 1 had only partially recovered. Thresholds and sharpness of tuning of many single units were normal: however, in general they were still poorer than in control animals. Spontaneous firing rate was comparable to control animals. Neurons from animals in group 2 showed less recovery, especially at frequencies above the exposure frequency. Thresholds and sharpness of tuning were normal at frequencies below the exposure frequency, but were much poorer at frequencies above the exposure. Spontaneous firing rate was much reduced in fibers with high CFs. The basilar papilla in animals without recovery showed total loss of the sensory epithelium. The basal lamina of the basilar membrane, however, remained intact and was covered with cuboidal cells. In fast recovering animals, the papilla was repopulated with hair cells after 4 months. In slow recovering animals, short (abneural) hair cells were still missing over large parts of the papilla after 4 months of recovery. Residual short (abneural) hair cell loss was largest at two areas, one more basal and the other more apical to the characteristic place of the traumatizing frequency. The results show that functional recovery from severe damage to both short (abneural) and tall (neural) hair cells occurs in adult birds. However, the onset of recovery is delayed and the time course is slower than after destruction of short (abneural) hair cells alone. Furthermore recovery is incomplete, both functionally and morphologically. There are residual permanent hearing losses and regeneration of short (abneural) hair cells is incomplete.
Collapse
Affiliation(s)
- M Müller
- Zentrum der Physiologie, Frankfurt am Main, Germany
| | | | | | | |
Collapse
|
46
|
Abstract
Spontaneous otoacoustic emissions were screened for in five advanced frog species (Hyla cinerea, n = 10 ears; Hyla chrysoscelis, n = 10; Hyla versicolor, n = 7; Leptodactylus albilabris, n = 2; Rana pipiens pipiens, n = 8), and two primitive frog species (Xenopus laevis, n = 9; Bombina orientalis, n = 12). Emissions were found in 90% of the advanced species' ears, whereas none of the primitive species' ears had emissions. Emission frequencies ranged from 645 Hz to 1680 Hz. The absence of emissions in the primitive species correlates with (1) the absence of a tympanic membrane, and (2) a reduced length of the caudal extension of the amphibian papilla. In eight frogs, the effect of body temperature on emissions was investigated. As a function of temperature, the frequency changed at a rate between 0.009 and 0.091 oct/degree C, and emission levels displayed a complex but consistent behavior. For 9 out of 15 spectral emission peaks encountered during the temperature experiments, the relation between the peak height and peak width was similar to that of an active oscillator.
Collapse
Affiliation(s)
- P van Dijk
- ENT Department, Audiology, University Hospital, Groningen, The Netherlands.
| | | | | |
Collapse
|
47
|
Abstract
The macula lagenae, an otolithic hair-cell organ with probable vestibular function, lies close to the apical end of the avian auditory hair-cell epithelium, the papilla basilaris. In an earlier study in the pigeon in which lesioning techniques were used, Boord and Rasmussen ([1963] J. Comp. Neurol. 120:463-473) reported finding a projection of lagenar fibers to parts of the cochlear nuclei (nucleus magnocellularis and nucleus angularis). Subsequent to this report, it has been generally assumed that at least part of the cochlear nuclei has a vestibular or a combined vestibular-auditory function. In this study, we labeled fibers innervating the macula lagenae of the chicken by using a lipophilic fluorescent tracer. The analysis of Vibratome sections of the brainstem with epifluorescence illumination showed no projection to the cochlear nuclei. In cases in which the apical part of the papilla basilaris was contaminated with tracer, however, we found labeling of the cochlear nuclei in the same areas as described with the lesioning technique in the pigeon. Our results thus imply that there is no processing of information from the macula lagenae in the cochlear nucleus of the chicken. In addition, we studied the origin of the few labeled efferent neurons in the brainstem. The location of all somata encountered was restricted to an area medial to the nucleus facialis dorsalis and corresponded to the dorsal efferent cell group, from which efferents to other vestibular organs also originate.
Collapse
Affiliation(s)
- A Kaiser
- Institut für Zoologie, Technische Universität München, Garching, Germany
| | | |
Collapse
|
48
|
Chen L, Trautwein PG, Shero M, Salvi RJ. Tuning, spontaneous activity and tonotopic map in chicken cochlear ganglion neurons following sound-induced hair cell loss and regeneration. Hear Res 1996; 98:152-64. [PMID: 8880189 DOI: 10.1016/0378-5955(96)00086-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Adult chickens were exposed for 48 h to a 525 Hz, 120 dB SPL tone that destroyed the hair cells and tectorial membrane in a crescent-shaped patch along the abneural edge of the basilar papilla. Single-unit recordings were obtained from cochlear ganglion neurons 0-1, 5, 14 and 28 days post-exposure to determine what effect the cochlear lesion had on neural discharge patterns and if the discharge patterns fully recovered. Immediately after exposure, the tuning curves were extremely broad and CF thresholds were elevated by 30-40 dB. In addition, the average spontaneous rate and percentage of neurons with interspike interval histograms with preferred intervals were greatly reduced. Tuning curves and spontaneous activity started to recover by 5 days post-exposure; however, some W-shaped tuning curves with two distinct tips and a hypersensitive tail were observed at this time. W-shaped tuning curves disappeared and spontaneous activity recovered to normal levels 14-28 days post-exposure. However, the CF thresholds of the most sensitive neurons were still slightly elevated, tuning curve slopes below CF were shallower than normal, and thresholds in the low-frequency tail of the tuning curves were often hypersensitive. These functional deficits were most closely associated with residual damage to the upper fibrous layer of the tectorial membrane. To determine if the cochlear frequency-place map was altered by the cochlear lesion, four physiologically characterized neurons were labeled with biocytin at 5 days post-exposure. The CFs of the labeled neurons were consistent with the normal frequency-place map (Chen et al. (1994) Hearing Research 81, 130-136) indicating that the tonotopic map was not altered.
Collapse
Affiliation(s)
- L Chen
- Hearing Research Laboratories, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, NY 14214, USA
| | | | | | | |
Collapse
|
49
|
Abstract
Epifluorescent light microscopy and confocal laser scanning microscopy were employed to visualize the distribution of nerve fibers in whole-mount preparations of normal and sound-damaged chick basilar papillae (BP). In normal cochleae, we identified a consistent pattern of nerve processes that ran transversely across the BP. The transverse processes increase in number from the proximal to the distal ends of the epithelium. However, when the processes are separated into populations of thin fibers and thick bundles, the thin fibers are more prevalent in distal regions whereas thick bundles are more extensive in proximal regions. Furthermore, the thick bundles form an elaborate longitudinal network in the border cell and hyaline cell region. Based on these data and no other previous studies, the thin fibers appear to be afferent nerves and the thick bundles represent efferent nerves. When birds are exposed to acoustic trauma, the normal pattern and number of nerve processes is not altered by levels of sound that produce moderate levels of damage, i.e., damage that leads to hair cell loss and regeneration. However, the nerve pattern is disrupted by severe levels of damage that destroy both hair cells and supporting cells. These findings indicate that the level of sound exposure that induces hair cell regeneration may damage the synaptic endings associated with the lost hair cells, but that the nerve processes that give rise to these endings remain intact within the sensory epithelium. In contrast, severe damage destroys both the hair cells and their associated nerve fibers.
Collapse
Affiliation(s)
- M S Ofsie
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Massachusetts 02118, USA
| | | |
Collapse
|
50
|
Wu YC, Fettiplace R. A developmental model for generating frequency maps in the reptilian and avian cochleas. Biophys J 1996; 70:2557-70. [PMID: 8744295 PMCID: PMC1225237 DOI: 10.1016/s0006-3495(96)79827-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Hair cells in the turtle cochlea are frequency-tuned by a mechanism involving the combined activation of voltage-sensitive Ca2+ channels and Ca(2+)-activated K+ (KCa) channels. The main determinants of a hair cell's characteristic frequency (Fo) are the KCa channels' density and kinetics, both of which change systematically with location in the cochlea in conjunction with the observed frequency map. We have developed a model based on the differential expression of two KCa channel subunits, which when accompanied by concurrent changes in other properties (e.g., density of Ca2+ channels and inwardly rectifying K+ channels), will generate sharp tuning at frequencies from 40 to 600 Hz. The kinetic properties of the two subunits were derived from previous single-channel analysis, and it was assumed that the subunits (A and B) combine to form five species of tetrameric channel (A4, A3B, A2B2, AB3, and B4) with intermediate kinetics and overlapping distribution. Expression of KCa and other channels was assumed to be regulated by diffusional gradients in either one or two chemicals. The results are consistent with both current- and voltage-clamp data on turtle hair cells, and they show that five channel species are sufficient to produce smooth changes in both Fo and kinetics of the macroscopic KCa current. Other schemes for varying KCa channel kinetics are examined, including one that allows extension of the model to the chick cochlea to produce hair cells with Fo's from 130 to 4000 Hz. A necessary assumption in all models is a gradient in the values of the parameters identified with the cell's cytoplasmic Ca2+ buffer.
Collapse
Affiliation(s)
- Y C Wu
- Department of Neurophysiology, University of Wisconsin Medical School, Madison 53706, USA
| | | |
Collapse
|