Journal articles on the topic 'Cochlea development'
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1
Chen, Penghui, Yongchuan Chai, Haijin Liu, Gen Li, Longhao Wang, Tao Yang, and Hao Wu. "Postnatal Development of Microglia-Like Cells in Mouse Cochlea." Neural Plasticity 2018 (July 31, 2018): 1–5. http://dx.doi.org/10.1155/2018/1970150.
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Microglial cells are involved in surveillance and cleaning of the central nervous system. Recently, microglial-like cells (MLC) have been found in an adult cochlea and investigated for their role in cochlear inflammation. The presence and potential roles of MLCs during the development of the cochlea, however, remain unclear. In this study, immunostaining was performed using the MLC-specific marker IBA1 to characterize the presence, distribution, and morphology of MLCs in the developing cochlea. From P0 to P14, MLCs were present in a variety of cochlear regions including the modiolus, spiral lamina, spiral ganglion, spiral ligament, and the organ of Corti. Interestingly, the overall number of MLCs in a mouse cochlea steadily increased since P0, peaks at P5, then gradually decreased from P5 to P14. In the spiral ligament, the distribution of the MLCs trends to shift from the type I/II fibrocyte-rich regions to the type III/IV fibrocyte-rich regions during the course of cochlear development, accompanied by the morphological changes of MLCs from the amoeboid, activated form to the ramified, quiescent form. Our results suggested that MLCs experience drastic morphological and distributional changes during postnatal cochlear development, which may play a role in the maturing and remodeling of the cochlea.
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Yu, J.-F., K.-C. Lee, Y.-L. Wan, and Y.-C. Peng. "Curvature measurement of human bilateral cochleae." Journal of Laryngology & Otology 129, no. 11 (September 21, 2015): 1085–90. http://dx.doi.org/10.1017/s0022215115002480.
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AbstractObjective:This study aimed to characterise the geometry of the human bilateral spiral cochlea by measuring curvature and length.Method:Eight subjects were recruited in this study. Magnetic resonance imaging was used to visualise the right and left cochlea. Visualisation of the cochlear spiral was enhanced by T2 weighting and further processing of the raw images. The spirals were divided into three segments: the basal turn, the middle turn and the apex turn. The length and curvature of each segment were non-invasively measured.Results:The mean left and right cochlear lengths were 3.11 cm and 3.95 cm, respectively. The measured lengths of the cochlear spiral are consistent with data in the literature derived from anatomical dissections. Overall, the apex turn segment of the cochlea had the greatest degree of curvature (p < 0.05). The mean apex turn segment curvatures for left and right cochleae were 9.65 cm−1 and 10.09 cm−1, respectively.Conclusion:A detailed description of the cochlear spiral is provided, using measurements of curvature and length. These data will provide a valuable reference in the development of cochlear implantation procedures for minimising the potential damage during implantation.
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Hang, Jianfeng, Wenlu Pan, Aoshuang Chang, Shun Li, Cuixian Li, Mingyu Fu, and Jie Tang. "Synchronized Progression of Prestin Expression and Auditory Brainstem Response during Postnatal Development in Rats." Neural Plasticity 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/4545826.
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Prestin is the motor protein expressed in the cochlear outer hair cells (OHCs) of mammalian inner ear. The electromotility of OHCs driven by prestin is responsible for the cochlear amplification which is required for normal hearing in adult animals. Postnatal expression of prestin and activity of OHCs may contribute to the maturation of hearing in rodents. However, the temporal and spatial expression of prestin in cochlea during the development is not well characterized. In the present study, we examined the expression and function of prestin from the OHCs in apical, middle, and basal turns of the cochleae of postnatal rats. Prestin first appeared at postnatal day 6 (P6) for basal turn, P7 in middle turn, and P9 for apical turn of cochlea. The expression level increased progressively over the next few days and by P14 reached the mature level for all three segments. By comparison with the time course of the development of auditory brainstem response for different frequencies, our data reveal that prestin expression synchronized with the hearing development. The present study suggests that the onset time of hearing may require the expression of prestin and is determined by the mature function of OHCs.
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Keppeler, Daniel, Christoph A. Kampshoff, Anupriya Thirumalai, Carlos J. Duque-Afonso, Jannis J. Schaeper, Tabea Quilitz, Mareike Töpperwien, et al. "Multiscale photonic imaging of the native and implanted cochlea." Proceedings of the National Academy of Sciences 118, no. 18 (April 26, 2021): e2014472118. http://dx.doi.org/10.1073/pnas.2014472118.
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The cochlea of our auditory system is an intricate structure deeply embedded in the temporal bone. Compared with other sensory organs such as the eye, the cochlea has remained poorly accessible for investigation, for example, by imaging. This limitation also concerns the further development of technology for restoring hearing in the case of cochlear dysfunction, which requires quantitative information on spatial dimensions and the sensorineural status of the cochlea. Here, we employed X-ray phase-contrast tomography and light-sheet fluorescence microscopy and their combination for multiscale and multimodal imaging of cochlear morphology in species that serve as established animal models for auditory research. We provide a systematic reference for morphological parameters relevant for cochlear implant development for rodent and nonhuman primate models. We simulate the spread of light from the emitters of the optical implants within the reconstructed nonhuman primate cochlea, which indicates a spatially narrow optogenetic excitation of spiral ganglion neurons.
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Swain, Santosh Kumar. "Cochlear deformities and its implication in cochlear implantation: a review." International Journal of Research in Medical Sciences 10, no. 10 (September 27, 2022): 2339. http://dx.doi.org/10.18203/2320-6012.ijrms20222547.
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Hearing loss is one of the world’s leading causes of chronic health conditions. Cochlea plays a vital role in the hearing mechanisms and it converts sound energy into electrical stimuli which are transmitted to the brain through the neural pathway. The human cochlea is difficult to explore because of its vulnerability and bordering bony capsule. Congenital malformation of the inner ear or cochlea is an important cause of congenital sensorineural hearing loss. The deformity of the cochlea may result from arrested development of cochlea at different stages of fetal life or from abnormal development due to genetic abnormalities. There are hair cells responsible for converting sound energy into electrical impulses. These hair cells are easily damaged, which results in permanent hearing loss. Cochlear implants are surgically implantable biomedical devices that bypass the sensory hair cells and directly stimulate the remaining fibers of the auditory nerve with an electric current. Cochlear implantation is capable of restoring a surprisingly large degree of auditory perception to patient that is suffering from severe to profoundly deaf. Children with cochlear anomalies are thought to have poorer outcomes with cochlear implantations, therefore would be poorer candidates due to their diminished ability to interpolate and use auditory information provided through a cochlear implant. Parents should be counselled to establish realistic post-implant expectations in case of children with cochlear deformity. So, patient selection has emerged as one of the most vital determinants of successful outcomes after pediatric cochlear implantation.
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Szczepek, Agnieszka J., Tatyana Dudnik, Betül Karayay, Valentina Sergeeva, Heidi Olze, and Alina Smorodchenko. "Mast Cells in the Auditory Periphery of Rodents." Brain Sciences 10, no. 10 (October 1, 2020): 697. http://dx.doi.org/10.3390/brainsci10100697.
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Mast cells (MCs) are densely granulated cells of myeloid origin and are a part of immune and neuroimmune systems. MCs have been detected in the endolymphatic sac of the inner ear and are suggested to regulate allergic hydrops. However, their existence in the cochlea has never been documented. In this work, we show that MCs are present in the cochleae of C57BL/6 mice and Wistar rats, where they localize in the modiolus, spiral ligament, and stria vascularis. The identity of MCs was confirmed in cochlear cryosections and flat preparations using avidin and antibodies against c-Kit/CD117, chymase, tryptase, and FcεRIα. The number of MCs decreased significantly during postnatal development, resulting in only a few MCs present in the flat preparation of the cochlea of a rat. In addition, exposure to 40 µM cisplatin for 24 h led to a significant reduction in cochlear MCs. The presence of MCs in the cochlea may shed new light on postnatal maturation of the auditory periphery and possible involvement in the ototoxicity of cisplatin. Presented data extend the current knowledge about the physiology and pathology of the auditory periphery. Future functional studies should expand and translate this new basic knowledge to clinics.
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Köles, László, Judit Szepesy, Eszter Berekméri, and Tibor Zelles. "Purinergic Signaling and Cochlear Injury-Targeting the Immune System?" International Journal of Molecular Sciences 20, no. 12 (June 18, 2019): 2979. http://dx.doi.org/10.3390/ijms20122979.
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Hearing impairment is the most common sensory deficit, affecting more than 400 million people worldwide. Sensorineural hearing losses currently lack any specific or efficient pharmacotherapy largely due to the insufficient knowledge of the pathomechanism. Purinergic signaling plays a substantial role in cochlear (patho)physiology. P2 (ionotropic P2X and the metabotropic P2Y) as well as adenosine receptors expressed on cochlear sensory and non-sensory cells are involved mostly in protective mechanisms of the cochlea. They are implicated in the sensitivity adjustment of the receptor cells by a K+ shunt and can attenuate the cochlear amplification by modifying cochlear micromechanics. Cochlear blood flow is also regulated by purines. Here, we propose to comprehend this field with the purine-immune interactions in the cochlea. The role of harmful immune mechanisms in sensorineural hearing losses has been emerging in the horizon of cochlear pathologies. In addition to decreasing hearing sensitivity and increasing cochlear blood supply, influencing the immune system can be the additional avenue for pharmacological targeting of purinergic signaling in the cochlea. Elucidating this complexity of purinergic effects on cochlear functions is necessary and it can result in development of new therapeutic approaches in hearing disabilities, especially in the noise-induced ones.
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Henley, Charles M. "Kanamycin Depletes Cochlear Polyamines in the Developing Rat." Otolaryngology–Head and Neck Surgery 110, no. 1 (January 1994): 103–9. http://dx.doi.org/10.1177/019459989411000112.
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Developing mammals are more sensitive to aminoglycoside antibiotics and other ototoxic agents than adults, with maximum sensitivity occurring during the period of anatomic and functional maturation of the cochlea. For the aminoglycoside antibiotics, the hypersensitive period in rats occurs during the second and third postnatal weeks. Toxicity is initially expressed as outer hair cell (OHC) damage in the high-frequency, basal region of the cochlea. Distortion-product otoacoustic emissions (DPOAEs), physiologic measures of OHC function, are particularly sensitive to aminoglycoside exposure during the period of rapid cochlear physiologic development. Toxicity is characterized by increased DPOAE thresholds and decreased amplitudes. The mechanism of developmental sensitivity to aminoglycosides is unknown. A potential biochemical target of aminoglycosides is the ornithine decarboxylase (ODC)-polyamine pathway. ODC activity is elevated in the developing rat cochlea, aminoglycosides inhibit cochlear ODC in developing rats, and α-difluoromethylornithine (a specific ODC inhibitor) impairs development of cochlear function. In the present study we demonstrate an incomplete polyamnine response to aminoglycoside damage, characterized by inhibition of the polyamines spermidine and spermine and accumulation of putrescine in the organ of Corti. Aminoglycoside inhibition of polyamine synthesis may mediate developmental ototoxic hypersensitivity by interfering with developmental and repair processes.
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Kössl, M., E. Foeller, M. Drexl, M. Vater, E. Mora, F. Coro, and I. J. Russell. "Postnatal Development of Cochlear Function in the Mustached Bat, Pteronotus parnellii." Journal of Neurophysiology 90, no. 4 (October 2003): 2261–73. http://dx.doi.org/10.1152/jn.00100.2003.
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Postnatal development of the mustached bat's cochlea was studied by measuring cochlear microphonic and compound action potentials. In adults, a cochlear resonance is involved in enhanced tuning to the second harmonic constant frequency component (CF2) of their echolocation calls at ∼61 kHz This resonance is present immediately after birth in bats that do not yet echolocate. Its frequency is lower (46 kHz) and the corresponding threshold minimum of cochlear microphonic potentials is broader than in adults. Long-lasting ringing of the cochlear microphonic potential after tone stimulus offset that characterizes the adult auditory response close to CF2 is absent in newborns. In the course of the first 5 postnatal weeks, there is a concomitant upward shift of CF2 and the frequency of cochlear threshold minima. Up to the end of the third postnatal week, sensitivity of auditory threshold minima and the Q value of the cochlear resonance increase at a fast rate. Between 2 and 4 wk of age, two cochlear microphonic threshold minima are found consistently in the CF2 range that differ in their level-dependent dynamic growth behavior and are 1.5–5.7 kHz apart from each other. In older animals, there is a single minimum that approaches adult tuning in its sharpness. The data provide evidence to show that during maturation of the cochlea, the frequency and the sensitivity of the threshold minimum associated with CF2 increases and that these increases are associated with the fusion of two resonances that are partly dissociated in developing animals.
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Vlajkovic, Srdjan M., and Peter R. Thorne. "Purinergic Signalling in the Cochlea." International Journal of Molecular Sciences 23, no. 23 (November 28, 2022): 14874. http://dx.doi.org/10.3390/ijms232314874.
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The mammalian cochlea is the sensory organ of hearing with a delicate, highly organised structure that supports unique operating mechanisms. ATP release from the secretory tissues of the cochlear lateral wall (stria vascularis) triggers numerous physiological responses by activating P2 receptors in sensory, supporting and neural tissues. Two families of P2 receptors, ATP-gated ion channels (P2X receptors) and G protein-coupled P2Y receptors, activate intracellular signalling pathways that regulate cochlear development, homeostasis, sensory transduction, auditory neurotransmission and response to stress. Of particular interest is a purinergic hearing adaptation, which reflects the critical role of the P2X2 receptor in adaptive cochlear response to elevated sound levels. Other P2 receptors are involved in the maturation of neural processes and frequency selectivity refinement in the developing cochlea. Extracellular ATP signalling is regulated by a family of surface-located enzymes collectively known as “ectonucleotidases” that hydrolyse ATP to adenosine. Adenosine is a constitutive cell metabolite with an established role in tissue protection and regeneration. The differential activation of A1 and A2A adenosine receptors defines the cochlear response to injury caused by oxidative stress, inflammation, and activation of apoptotic pathways. A1 receptor agonism, A2A receptor antagonism, and increasing adenosine levels in cochlear fluids all represent promising therapeutic tools for cochlear rescue from injury and prevention of hearing loss.
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Yang, Nan, Jing Xuan Wang, Lan Tian, and Yong Wang. "Laser Stimulation Control System Design of the Auditory Nerve." Advanced Materials Research 1046 (October 2014): 116–20. http://dx.doi.org/10.4028/www.scientific.net/amr.1046.116.
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Optical stimulation of the inner ear, the cochlea, has been proved as a possible alternative to conventional cochlear implant with the hypothetical improvement of dynamic range and frequency resolution. Moreover, the laser has good directionality character and optical signal between adjacent fibers do not readily interfere. Therefore, cochlear implant based on optical stimulation is promising for further exploration and development. The design of an experimental system for optical stimulation of the cochlea is introduced in this paper. For the important part, the selection of NIR laser and the optical signal control methods were discussed. The pulsed laser light was coupled by fiber or fiber array and radiated to the cochlea. For each channel laser pulse, the width modulation was varied from 10us to 1ms, the pulse repetition rate from 5 Hz to 10 KHz, single pulse energy from 0 to 3.6mJ. The application of high precision DAC made the resolution of the pulse energy regulation up to 1uJ/div. The experiment results show that this design and implementation can meet the requirements on further optical stimulation of the cochlea research.
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Weddell, Thomas D., Yury M. Yarin, Markus Drexl, Ian J. Russell, Stephen J. Elliott, and Andrei N. Lukashkin. "A novel mechanism of cochlear excitation during simultaneous stimulation and pressure relief through the round window." Journal of The Royal Society Interface 11, no. 93 (April 6, 2014): 20131120. http://dx.doi.org/10.1098/rsif.2013.1120.
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The round window (RW) membrane provides pressure relief when the cochlea is excited by sound. Here, we report measurements of cochlear function from guinea pigs when the cochlea was stimulated at acoustic frequencies by movements of a miniature magnet which partially occluded the RW. Maximum cochlear sensitivity, corresponding to subnanometre magnet displacements at neural thresholds, was observed for frequencies around 20 kHz, which is similar to that for acoustic stimulation. Neural response latencies to acoustic and RW stimulation were similar and taken to indicate that both means of stimulation resulted in the generation of conventional travelling waves along the cochlear partition. It was concluded that the relatively high impedance of the ossicles, as seen from the cochlea, enabled the region of the RW not occluded by the magnet, to act as a pressure shunt during RW stimulation. We propose that travelling waves, similar to those owing to acoustic far-field pressure changes, are driven by a jet-like, near-field component of a complex pressure field, which is generated by the magnetically vibrated RW. Outcomes of research described here are theoretical and practical design principles for the development of new types of hearing aids, which use near-field, RW excitation of the cochlea.
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Guo, Weiwei, Haijin Yi, Zhang Yan, Lili Ren, Lei Chen, Li Dong Zhao, Yu Ning, David Z. Z. He, and Shi-Ming Yang. "The morphological and functional development of the stria vascularis in miniature pigs." Reproduction, Fertility and Development 29, no. 3 (2017): 585. http://dx.doi.org/10.1071/rd15183.
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The purpose of this study was to examine the morphological and functional development of the lateral wall of the scala media of the cochlea in miniature pigs; light and transmission electron microscopy and electrophysiology were used for this purpose. We showed that the lateral wall of the scala media of the cochlea appears at embryonic Day 21 (E21) when the cochlear duct begins to form. From E28 to E49, the lateral wall can be distinguished according to its position along the cochlea. At E56, cells in the lateral wall begin to differentiate into three different types. At E70, three cell types, marginal, intermediate and basal, can be clearly distinguished. At E91, the stria vascularis is adult-like and the organ of Corti is also morphologically mature. The average endocochlear potential measured from the second turn of the cochlea (at E98, postnatal Day 1 (P1), P13 and P30) was 71.4 ± 2.5 (n = 7), 78.8 ± 1.5 (n = 10), 77.3 ± 2.3 (n = 10) and 78.0 ± 2.1 mV (n = 10), respectively. Our results suggest that in miniature pigs the stria vascularis develops during the embryonic period, concurrent with maturation of the organ of Corti. The magnitude of the endocochlear potential reached its mature level when the stria vascularis was morphologically adult-like at E98. These findings provide a morphological and functional basis for future animal studies using the miniature pig model concerning the pathogenesis of various inner-ear diseases.
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Driver, Elizabeth Carroll, and Matthew W. Kelley. "Development of the cochlea." Development 147, no. 12 (June 15, 2020): dev162263. http://dx.doi.org/10.1242/dev.162263.
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Murofushi, Toshihisa, Robert I. Graham, Robert A. Ouvrier, Merl Da Silva, Geoffrey D. Parker, and G. Michael Halmagyi. "Vestibular Abnormalities in Charge Association." Annals of Otology, Rhinology & Laryngology 106, no. 2 (February 1997): 129–34. http://dx.doi.org/10.1177/000348949710600207.
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We report the vestibular abnormalities in 5 patients with the CHARGE association (Coloboma, Heart disease, Atresia of choanae, Retarded growth and development and/or central nervous system anomalies, Genital hypoplasia, and Ear anomalies). All patients had absent vestibular function as indicated by absent vestibulo-ocular reflexes and severe imbalance on simultaneous deprivation of proprioception and vision, as well as delayed motor development. All 6 semicircular canals were aplastic in each of the patients. While cochlear function was severely reduced in 6 of the 10 ears, it was absent only in 3 ears and was actually intact below 3 kHz in 1 ear. All 10 bony cochleas were present on computed tomography, and although 7 appeared abnormal, 3 appeared normal. This study confirms that absence of the bony semicircular canals in the presence of a bony cochlea is a characteristic finding in CHARGE association. It also demonstrates that these disproportionate structural abnormalities are reflected in the functional abnormalities: absent vestibular function with preservation of some cochlear function.
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Horvath, Lukas, Daniel Bodmer, Vesna Radojevic, and Arianne Monge Naldi. "Activin Signaling Disruption in the Cochlea Does Not Influence Hearing in Adult Mice." Audiology and Neurotology 20, no. 1 (November 26, 2014): 51–61. http://dx.doi.org/10.1159/000366152.
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Activin, a member of the TGF-F superfamily, was found to play an important role in the development, repair and apoptosis of different tissues and organs. Accordingly, activin signaling is involved in the development of the cochlea. Activin binds to its receptor ActRII, then dimerizes with ActRI and induces a signaling pathway resulting in gene expression. A study reported a case of fibrodysplasia ossificans progressiva with an unusual mutation in the ActRI gene leading to sensorineural hearing loss. This draws attention to the role of activin and its receptors in the developed cochlea. To date, only the expression of ActRII is known in the adult mammalian cochlea. In this study, we present for the first time the presence of activin A and ActRIB in the adult cochlea. Transgenic mice with postnatal dominant-negative ActRIB expression causing disruption of activin signaling in vivo were used for assessing cochlear morphology and hearing ability through the auditory brainstem response (ABR) threshold. Nonfunctioning ActRIB did not affect the ABR thresholds and did not alter the microscopic anatomy of the cochlea. We conclude, therefore, that activin signaling is not necessary for hearing in adult mice under physiological conditions but may be important during and after damaging events in the inner ear. i 2014 S. Karger AG, Basel
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Lu, Yong, Julie A. Harris, and Edwin W. Rubel. "Development of Spontaneous Miniature EPSCs in Mouse AVCN Neurons During a Critical Period of Afferent-Dependent Neuron Survival." Journal of Neurophysiology 97, no. 1 (January 2007): 635–46. http://dx.doi.org/10.1152/jn.00915.2006.
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During a critical period prior to hearing onset, cochlea ablation leads to massive neuronal death in the mouse anteroventral cochlear nucleus (AVCN), where cell survival is believed to depend on glutamatergic input. We investigated the development of spontaneous miniature excitatory postsynaptic currents (mEPSCs) in AVCN neurons using whole cell patch-clamp techniques during [postnatal day 7 (P7)] and after (P14, P21) this critical period. We also examined the effects of unilateral cochlea ablation on mEPSC development. The two main AVCN neuron types, bushy and stellate cells, were distinguished electrophysiologically. Bushy cell mEPSCs became more frequent and faster between P7 and P14/P21 but with little change in amplitude. Dendritic filtering of mEPSCs was not detected as indicated by the lack of correlation between 10 and 90% rise times and decay time constants. Seven days after cochlea ablation at P7 or P14, mEPSCs in surviving bushy cells were similar to controls, except that rise and decay times were positively correlated ( R = 0.31 and 0.14 for surgery at P7 and P14, respectively). Consistent with this evidence for a shift of synaptic activity from the somata to the dendrites, SV2 staining (a synaptic vesicle marker) forms a ring around somata of control but not experimental bushy cells. In contrast, mEPSCs of stellate cells showed few significant changes over these ages with or without cochlea ablation. Taken together, mEPSCs in mouse AVCN bushy cells show dramatic developmental changes across this critical period, and cochlea ablation may lead to the emergence of excitatory synaptic inputs impinging on bushy cell dendrites.
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Schart-Morén, Nadine, Sune Larsson, Helge Rask-Andersen, and Hao Li. "Anatomical Characteristics of Facial Nerve and Cochlea Interaction." Audiology and Neurotology 22, no. 1 (2017): 41–49. http://dx.doi.org/10.1159/000475876.
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Objective: The aim was to study the relationship between the labyrinthine portion (LP) of the facial canal and the cochlea in human inner ear molds and temporal bones using micro-CT and 3D rendering. A reduced cochlea-facial distance may spread electric currents from the cochlear implant to the LP and cause facial nerve stimulation. Influencing factors may be the topographic anatomy and otic capsule properties. Methods: An archival collection of human temporal bones underwent micro-CT and 3D reconstruction. In addition, cochlea-facial distance was assessed in silicone and polyester resin molds, and the association between the LP and upper basal turn of the cochlea was analyzed. Results: Local thinning of the otic capsule and local anatomy may explain the development of cochlea-facial dehiscence, which was found in 1.4%. A reduced cochlea-facial distance was noted in 1 bone with a superior semicircular canal dehiscence but not in bones with superior semicircular canal “blue line.” The otic capsule often impinged upon the LP and caused narrowing. Conclusion: Micro-CT with 3D rendering offers new possibilities to study the topographic anatomy of the human temporal bone. The varied shape of the cross-section of the LP could often be explained by an “intruding” cochlea.
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Chen, Bei, Yunfeng Wang, Manying Geng, Xi Lin, and Wenxue Tang. "Localization of Glucose Transporter 10 to Hair Cells’ Cuticular Plate in the Mouse Inner Ear." BioMed Research International 2018 (June 14, 2018): 1–7. http://dx.doi.org/10.1155/2018/7817453.
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This study aimed to investigate the localization pattern of glucose transporters (Gluts) in mouse cochlea. Genome-wide gene expression analysis using CodeLink™ bioarrays indicated that Glut1 and Glut10 were highly expressed (~10-fold) in mouse cochlea compared with the other members of glucose transporters (Glut2-6, Glut8, and Glut9). Semiquantitative RT-PCR and western blotting confirmed that Glut10 expression in mouse cochlea was high throughout the embryogenesis and postnatal development. Immunofluorescent staining showed that Glut10 protein was localized in the cuticular plate of the outer and inner cochlear hair cells and in the ampullary crest of the vestibular system. Based on these results, it was supposed that Glut10 may contribute to glucose transport from the endolymph to the hair cells across the cuticular plate.
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Najarro, Elvis Huarcaya, Jennifer Huang, Adrian Jacobo, Lee A. Quiruz, Nicolas Grillet, and Alan G. Cheng. "Dual regulation of planar polarization by secreted Wnts and Vangl2 in the developing mouse cochlea." Development 147, no. 19 (September 9, 2020): dev191981. http://dx.doi.org/10.1242/dev.191981.
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ABSTRACTPlanar cell polarity (PCP) proteins localize asymmetrically to instruct cell polarity within the tissue plane, with defects leading to deformities of the limbs, neural tube and inner ear. Wnt proteins are evolutionarily conserved polarity cues, yet Wnt mutants display variable PCP defects; thus, how Wnts regulate PCP remains unresolved. Here, we have used the developing cochlea as a model system to show that secreted Wnts regulate PCP through polarizing a specific subset of PCP proteins. Conditional deletion of Wntless or porcupine, both of which are essential for secretion of Wnts, caused misrotated sensory cells and shortened cochlea – both hallmarks of PCP defects. Wntless-deficient cochleae lacked the polarized PCP components dishevelled 1/2 and frizzled 3/6, while other PCP proteins (Vangl1/2, Celsr1 and dishevelled 3) remained localized. We identified seven Wnt paralogues, including the major PCP regulator Wnt5a, which was, surprisingly, dispensable for planar polarization in the cochlea. Finally, Vangl2 haploinsufficiency markedly accentuated sensory cell polarization defects in Wntless-deficient cochlea. Together, our study indicates that secreted Wnts and Vangl2 coordinate to ensure proper tissue polarization during development.
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Graham, John M., Peter D. Phelps, and Leslie Michaels. "Congenital malformations of the ear and cochlear implantation in children: review and temporal bone report of common cavity." Journal of Laryngology & Otology 114, S25 (March 2000): 1–14. http://dx.doi.org/10.1258/0022215001904842.
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The objective of this review is to analyze aspects of congenital malformation of the ear in relation to cochlear implantation in children. Having briefly described the in utero development of the ear and the classification of types of external, middle and inner ear malformation, five practical aspects of these malformations are discussed. It seems likely that the combination of bilateral profound sensorineural deafness with bilateral microtia severe enough to make a surgical approach to the cochlea difficult will be extremely uncommon. No such cases have been reported, although Klippel-Feil deformity seems the syndrome most likely to produce this set of circumstances.Abnormalities in the intratympanic course of the facial nerve have been associated with cochlear malformation, emphasizing the benefit of intra-operative facial nerve monitoring, and a technique suggested for safely avoiding an abnormally placed nerve. Fistulae of cerebrospinal fluid (CSF) and perilymph can complicate surgery and are relatively common in common cavity and Mondini malformations. Strategies for facilitating surgery in the presence of ‘gushers’, for measuring the pressure of a gusher and for placement of the cochlear implant electrode array are reviewed, with reports of fluctuating levels of electric current when implants lie in dysplastic cochleas.The relationship of implant performance to VIIIth nerve tissue in malformed cochleas is discussed, with a description of the histological findings in a common cavity cochlea. Techniques for identifying the absence of the cochlear nerve are reviewed. Stimulation of the facial nerve by cochlear implants has been described in cases of congenital malformation of the labyrinth but is relatively uncommon. Case reports of the benefit received by implanted children with congenital cochlear malformation have appeared since 1988. Most cases reported have not yet been followed for long enough to establish a clear picture of the outcome following cochlear implantationin such children; no centre has yet built up a large series of cases, but there have been two multicentre postal surveys. It seems likely that in cochlear malformation the range of potential outcomes in terms of hearing threshold and the development of speech perception and production will be similar to the range found in implanted children without cochlear dysplasia. However there is, as yet, no clear picture of the mean level of performance within this range.
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Ng, Lily, Arturo Hernandez, Wenxuan He, Tianying Ren, Maya Srinivas, Michelle Ma, Valerie A. Galton, Donald L. St. Germain, and Douglas Forrest. "A Protective Role for Type 3 Deiodinase, a Thyroid Hormone-Inactivating Enzyme, in Cochlear Development and Auditory Function." Endocrinology 150, no. 4 (December 18, 2008): 1952–60. http://dx.doi.org/10.1210/en.2008-1419.
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Thyroid hormone is necessary for cochlear development and auditory function, but the factors that control these processes are poorly understood. Previous evidence indicated that in mice, the serum supply of thyroid hormone is augmented within the cochlea itself by type 2 deiodinase, which amplifies the level of T3, the active form of thyroid hormone, before the onset of hearing. We now report that type 3 deiodinase, a thyroid hormone-inactivating enzyme encoded by Dio3, is expressed in the immature cochlea before type 2 deiodinase. Dio3−/− mice display auditory deficits and accelerated cochlear differentiation, contrasting with the retardation caused by deletion of type 2 deiodinase. The Dio3 mRNA expression pattern in the greater epithelial ridge, stria vascularis, and spiral ganglion partly overlaps with that of thyroid hormone receptor β (TRβ), the T3 receptor that is primarily responsible for auditory development. The proposal that type 3 deiodinase prevents premature stimulation of TRβ was supported by deleting TRβ, which converted the Dio3−/− cochlear phenotype from one of accelerated to one of delayed differentiation. The results indicate a protective role for type 3 deiodinase in hearing. The auditory system illustrates the considerable extent to which tissues can autoregulate their developmental response to thyroid hormone through both type 2 and 3 deiodinases.
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Sarreal, Ressa Reneth, and Pamela Bhatti. "Characterization and Miniaturization of Silver-Nanoparticle Microcoil via Aerosol Jet Printing Techniques for Micromagnetic Cochlear Stimulation." Sensors 20, no. 21 (October 26, 2020): 6087. http://dx.doi.org/10.3390/s20216087.
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According to the National Institute of Deafness and other Communication Disorders 2012 report, the number of cochlear implant (CI) users is steadily increasing from 324,000 CI users worldwide. The cochlea, located in the inner ear, is a snail-like structure that exhibits a tonotopic geometry where acoustic waves are filtered spatially according to frequency. Throughout the cochlea, there exist hair cells that transduce sensed acoustic waves into an electrical signal that is carried by the auditory nerve to ultimately reach the auditory cortex of the brain. A cochlear implant bridges the gap if non-functional hair cells are present. Conventional CIs directly inject an electrical current into surrounding tissue via an implanted electrode array and exploit the frequency-to-place mapping of the cochlea. However, the current is dispersed in perilymph, a conductive bodily fluid within the cochlea, causing a spread of excitation. Magnetic fields are more impervious to the effects of the cochlear environment due to the material properties of perilymph and surrounding tissue, demonstrating potential to improve precision. As an alternative to conventional CI electrodes, the development and miniaturization of microcoils intended for micromagnetic stimulation of intracochlear neural elements is described. As a step toward realizing a microcoil array sized for cochlear implantation, human-sized coils were prototyped via aerosol jet printing. The batch reproducible aerosol jet printed microcoils have a diameter of 1800 μm, trace width and trace spacing of 112.5 μm, 12 μm thickness, and inductance values of approximately 15.5 nH. Modelling results indicate that the coils have a combined depolarization–hyperpolarization region that spans 1.5 mm and produce a more restrictive spread of activation when compared with conventional CI.
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Pujol, Remy, Mireille Lavigne-rebillard, and Alain Uziel. "Development of the Human Cochlea." Acta Oto-Laryngologica 111, sup482 (January 1991): 7–13. http://dx.doi.org/10.3109/00016489109128023.
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Kitzes, L. M., and M. N. Semple. "Single-unit responses in the inferior colliculus: effects of neonatal unilateral cochlear ablation." Journal of Neurophysiology 53, no. 6 (June 1, 1985): 1483–500. http://dx.doi.org/10.1152/jn.1985.53.6.1483.
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Monaural responses of single units isolated in the inferior colliculus of adult gerbils that have developed postnatally with one cochlea were compared with monaural responses recorded in animals that have developed with both cochleas. One cochlea of 2-day-old gerbils was ablated, and at approximately 6 mo of age, excitatory responses to stimulation of the nonoperated ear were recorded in the ipsilateral inferior colliculus. These responses were compared quantitatively with responses evoked by ipsilateral and contralateral monaural stimulation in normal gerbils. Responses to ipsilateral stimulation in adult gerbils subjected at 2 days of age to ablation of the contralateral cochlea are significantly different from ipsilateral responses in nonoperated gerbils. In several respects they are very similar to contralateral responses in nonoperated gerbils. (Differences between monaural contralateral and ipsilateral responses in control animals are documented in the companion paper, Ref. 24.) These conclusions are based on analyses of response threshold, peak discharge rate, response pattern, and minimum response latency. The mean dynamic range of ipsilateral rate/intensity functions obtained in neonatally ablated gerbils is significantly larger than the mean ipsilateral and contralateral dynamic ranges in control animals. Analyses of threshold tuning curves indicate that the frequency tuning of units in the inferior colliculus of neonatally ablated animals does not differ significantly from the tuning of units in control animals in response to either ipsilateral or contralateral stimulation. These data reveal that in normal gerbils responses of single units in the inferior colliculus to stimulation of the ipsilateral ear result in part from interactions during postnatal development between pathways that convey information from the contralateral ear. The results are discussed in terms of the known anatomic consequences of a neonatal cochlear ablation and the competition for available synaptic space in the development of the retinotectal system.
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Sharlin, David S., Theo J. Visser, and Douglas Forrest. "Developmental and Cell-Specific Expression of Thyroid Hormone Transporters in the Mouse Cochlea." Endocrinology 152, no. 12 (August 30, 2011): 5053–64. http://dx.doi.org/10.1210/en.2011-1372.
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Thyroid hormone is essential for the development of the cochlea and auditory function. Cochlear response tissues, which express thyroid hormone receptor β (encoded by Thrb), include the greater epithelial ridge and sensory epithelium residing inside the bony labyrinth. However, these response tissues lack direct blood flow, implying that mechanisms exist to shuttle hormone from the circulation to target tissues. Therefore, we investigated expression of candidate thyroid hormone transporters L-type amino acid transporter 1 (Lat1), monocarboxylate transporter (Mct)8, Mct10, and organic anion transporting polypeptide 1c1 (Oatp1c1) in mouse cochlear development by in situ hybridization and immunofluorescence analysis. L-type amino acid transporter 1 localized to cochlear blood vessels and transiently to sensory hair cells. Mct8 localized to the greater epithelial ridge, tympanic border cells underlying the sensory epithelium, spiral ligament fibrocytes, and spiral ganglion neurons, partly overlapping with the Thrb expression pattern. Mct10 was detected in a highly restricted pattern in the outer sulcus epithelium and weakly in tympanic border cells and hair cells. Organic anion transporting polypeptide 1c1 localized primarily to fibrocytes in vascularized tissues of the spiral limbus and spiral ligament and to tympanic border cells. Investigation of hypothyroid Tshr−/− mice showed that transporter expression was delayed consistent with retardation of cochlear tissue maturation but not with compensatory responses to hypothyroidism. The results demonstrate specific expression of thyroid hormone transporters in the cochlea and suggest that a network of thyroid hormone transport underlies cochlear development.
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Otsuka, Kelly S., Christopher Nielson, Matthew A. Firpo, Albert H. Park, and Anna E. Beaudin. "Early Life Inflammation and the Developing Hematopoietic and Immune Systems: The Cochlea as a Sensitive Indicator of Disruption." Cells 10, no. 12 (December 20, 2021): 3596. http://dx.doi.org/10.3390/cells10123596.
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Emerging evidence indicates that perinatal infection and inflammation can influence the developing immune system and may ultimately affect long-term health and disease outcomes in offspring by perturbing tissue and immune homeostasis. We posit that perinatal inflammation influences immune outcomes in offspring by perturbing (1) the development and function of fetal-derived immune cells that regulate tissue development and homeostasis, and (2) the establishment and function of developing hematopoietic stem cells (HSCs) that continually generate immune cells across the lifespan. To disentangle the complexities of these interlinked systems, we propose the cochlea as an ideal model tissue to investigate how perinatal infection affects immune, tissue, and stem cell development. The cochlea contains complex tissue architecture and a rich immune milieu that is established during early life. A wide range of congenital infections cause cochlea dysfunction and sensorineural hearing loss (SNHL), likely attributable to early life inflammation. Furthermore, we show that both immune cells and bone marrow hematopoietic progenitors can be simultaneously analyzed within neonatal cochlear samples. Future work investigating the pathogenesis of SNHL in the context of congenital infection will therefore provide critical information on how perinatal inflammation drives disease susceptibility in offspring.
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Sekiya, Tetsuji, Ken Kojima, Masahiro Matsumoto, Matthew C. Holley, and Juichi Ito. "REBUILDING LOST HEARING USING CELL TRANSPLANTATION." Neurosurgery 60, no. 3 (March 1, 2007): 417–33. http://dx.doi.org/10.1227/01.neu.0000249189.46033.42.
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Abstract OBJECTIVE The peripheral auditory nervous system (cochlea and auditory nerve) has a complex anatomy, and it has traditionally been thought that once the sensorineural structures are damaged, restoration of hearing is impossible. In the past decade, however, the potential to restore lost hearing has been intensively investigated using molecular and cell biological techniques, and we can now part with such a pessimistic view. In this review, we examine an important field in hearing restoration research: cell transplantation. METHODS Most efforts in this field have been directed to the replacement of hair cells by transplantation to the cochlea. Here, we focus on transplantation to the auditory nerve, from the side of the cerebellopontine angle rather than the cochlea. RESULTS Delivery of cells to the cochlea is potentially damaging, and nerve cells transplanted distally to the Schwann-glial transitional zone (cochlear side) may become inhibited when they reach the transitional zone. The auditory nerve is probably the most suitable route for cell transplantation. CONCLUSION The auditory nerve occupies an important position not only in neurosurgery but also in various diseases in other disciplines, and several lines of recent evidence indicate that it is a key target for hearing restoration. It is familiar to most neurosurgeons, and the recent advances in the molecular and cell biology of inner-ear development are of direct importance to neurorestorative medicine. In this article, we review the anatomy, development, and molecular biology of the auditory nerve and cochlea, with emphasis on the advances in cell transplantation.
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Jansson, Lina, Michael Ebeid, Jessica W. Shen, Tara E. Mokhtari, Lee A. Quiruz, David M. Ornitz, Sung-Ho Huh, and Alan G. Cheng. "β-Catenin is required for radial cell patterning and identity in the developing mouse cochlea." Proceedings of the National Academy of Sciences 116, no. 42 (September 30, 2019): 21054–60. http://dx.doi.org/10.1073/pnas.1910223116.
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Development of multicellular organs requires the coordination of cell differentiation and patterning. Critical for sound detection, the mammalian organ of Corti contains functional units arranged tonotopically along the cochlear turns. Each unit consists of sensory hair cells intercalated by nonsensory supporting cells, both specified and radially patterned with exquisite precision during embryonic development. However, how cell identity and radial patterning are jointly controlled is poorly understood. Here we show that β-catenin is required for specification of hair cell and supporting cell subtypes and radial patterning of the cochlea in vivo. In 2 mouse models of conditional β-catenin deletion, early specification of Myosin7-expressing hair cells and Prox1-positive supporting cells was preserved. While β-catenin-deficient cochleae expressed FGF8 and FGFR3, both of which are essential for pillar cell specification, the radial patterning of organ of Corti was disrupted, revealed by aberrant expression of cadherins and the pillar cell markers P75 and Lgr6. Moreover, β-catenin ablation caused duplication of FGF8-positive inner hair cells and reduction of outer hair cells without affecting the overall hair cell density. In contrast, in another transgenic model with suppressed transcriptional activity of β-catenin but preserved cell adhesion function, both specification and radial patterning of the organ of Corti were intact. Our study reveals specific functions of β-catenin in governing cell identity and patterning mediated through cell adhesion in the developing cochlea.
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Yu, Kathy K., Suresh Mukherji, Vincent Carrasco, Harold C. Pillsbury, and Carol G. Shores. "Molecular Genetic Advances in Semicircular Canal Abnormalities and Sensorineural Hearing Loss: A Report of 16 Cases." Otolaryngology–Head and Neck Surgery 129, no. 6 (December 2003): 637–46. http://dx.doi.org/10.1016/s0194-59980301593-6.
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OBJECTIVES: The study goals were (1) to determine if the degree and pattern of semicircular canal dysmorphology and the presence or absence of a cochlea in patients with congenital sensorineural hearing loss predict audiologic outcome, severity, or the frequencies involved and (2) to review the recent advances in molecular genetics of the semicircular canals and correlate this information with audiologic and anatomic patterns seen in our series of patients DESIGN AND SETTING: We conducted a retrospective study at a tertiary care center with a large otologic and cochlear implant service. PATIENTS AND METHODS: The study population consisted of 16 patients with congenital sensorineural hearing loss in 28 congenitally malformed inner ears consisting of semicircular canal dysplasia or aplasia, with or without cochlear malformation. History, physical examination, computed tomography scans, and serial audiograms were reviewed. Factors analyzed included other phenotypic dysmorphology characteristic of syndromes, audiometric configuration, severity and type of hearing loss, and the presence of associated inner ear anomalies other than the vestibular system. An extensive review of the literature regarding molecular genetic factors in semicircular canal anomalies, with or without cochlear abnormalities, was performed. RESULTS: Sixteen patients (31 ears) were identified with profound sensorineural hearing loss and semicircular canal abnormalities. Only 3 patients had known syndromes, although 4 patients had other congenital anomalies. Most radiographic detectable abnormalities were bilateral. Audiograms of the patients demonstrated pure tone averages between 90 and 100 dB in the affected ears with few exceptions. No correlation was found between type and severity of malformation of either the cochlea or semicircular canals with the severity of hearing loss. There was no stepwise progression of hearing loss increasing malformation severity. Seven of the 16 patients received cochlear implants. Of these 7, 3 patients had cochlear hypoplasia and 1 patient had a common cavity deformity. Audiologic follow-up on all 7 patients revealed improvement in both speech assessment threshold and pure tone average. Presence or absence of the cochlea was not a factor in outcome after cochlear implantation. CONCLUSION: We have assembled the largest series of patients with semicircular canal dysmorphology, with or without various cochlear abnormalities. Our study failed to correlate the type and severity of semicircular canal malformation with any specific audiologic outcome. The variation in hearing loss severity and pattern even in patients with similar bony radiographic findings must be explained by other non-radiologically detectable defects, likely abnormalities in membranous labyrinthine development. New molecular genetic discoveries have linked specific genes to the development of certain inner ear structures in mice studies. The independent development of the individual semicircular canals in relation to the cochlea and vestibule and the variability in hearing loss suggest a more complex embryologic process than merely an arrest in development as previously thought. As genetic studies are extended into humans, we will likely be able to stratify these patients by molecular defect and severity of hearing loss. (Otolaryngol Head Neck Surg 2003;129:637-46.)
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Yamada, Satoshi, Junya Kita, Daichi Shinmura, Yuki Nakamura, Sosuke Sahara, Kiyoshi Misawa, and Hiroshi Nakanishi. "Update on Findings about Sudden Sensorineural Hearing Loss and Insight into Its Pathogenesis." Journal of Clinical Medicine 11, no. 21 (October 28, 2022): 6387. http://dx.doi.org/10.3390/jcm11216387.
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Sudden sensorineural hearing loss (SSNHL) is routinely encountered and is one of the most common emergent diseases in otolaryngology clinics. However, the etiology of SSNHL remains unclear. Due to the inaccessibility of the living human inner ear for biopsy, studies investigating the etiology of SSNHL have been performed by analyzing data obtained from examinations using peripheral blood or imaging. We updated the findings obtained from serological, magnetic resonance imaging, genetic, and viral examinations to reveal the etiology of SSNHL. Regarding viral examination, we focused on sensorineural hearing loss associated with coronavirus disease (COVID-19) because the number of correlated reports has been increasing after the outbreak. The updated findings revealed the following three possible mechanisms underlying the development of SSNHL: thrombosis and resulting vascular obstruction in the cochlea, asymptomatic viral infection and resulting damage to the cochlea, and cochlear inflammation and resulting damage to the cochlea. Thrombosis and viral infection are predominant, and cochlear inflammation can be secondarily induced through viral infection or even thrombosis. The findings about sensorineural hearing loss associated with COVID-19 supported the possibility that asymptomatic viral infection is one of the etiologies of SSNHL, and the virus can infect inner ear tissues and directly damage them.
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Zhao, Yu, Longlong Zhang, Daqi Wang, Bing Chen, and Yilai Shu. "Approaches and Vectors for Efficient Cochlear Gene Transfer in Adult Mouse Models." Biomolecules 13, no. 1 (December 26, 2022): 38. http://dx.doi.org/10.3390/biom13010038.
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Inner ear gene therapy using adeno-associated viral vectors (AAVs) in neonatal mice can alleviate hearing loss in mouse models of deafness. However, efficient and safe transgene delivery to the adult mouse cochlea is critical for the effectiveness of AAV-mediated therapy. Here, we examined three gene delivery approaches including posterior semicircular canal (PSCC) canalostomy, round window membrane (RWM) injection, and tubing-RWM+PSCC (t-RP) in adult mice. Transduction rates and survival rates of cochlear hair cells were analyzed, hearing function was recorded, AAV distribution in the sagittal brain sections was evaluated, and cochlear histopathologic images were appraised. We found that an injection volume of 1 μL AAV through the PSCC is safe and highly efficient and does not impair hearing function in adult mice, but local injection allows AAV vectors to spread slightly into the brain. We then tested five AAV serotypes (PHP.eB, IE, Anc80L65, AAV2, and PHP.s) in parallel and observed the most robust eGFP expression in inner hair cells, outer hair cells, and spiral ganglion neurons throughout the cochlea after AAV-Anc80L65 injection. Thus, PSCC-injected Anc80L65 provides a foundation for gene therapy in the adult cochlea and will facilitate the development of inner ear gene therapy.
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Kuzovkov, V. E., A. S. Lilenko, S. B. Sugarova, V. A. Tanaschishina, D. D. Kaliapin, D. S. Luppov, and I. N. Skirpichnikov. "Etiological factors of facial nerve stimulation in cochlear implant users." Meditsinskiy sovet = Medical Council, no. 20 (November 20, 2022): 170–76. http://dx.doi.org/10.21518/2079-701x-2022-16-20-170-176.
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Cochlear implantation is a high-tech method of rehabilitation of persons with complete deafness. However, cochlear implantation in patients may be accompanied by a number of difficulties due to the peculiarities of the structure of the cochlea, the relative position of anatomical structures relative to it and the nature of the acquired pathology of the inner ear. The reaction of the facial nerve during stimulation of one of the electrodes of the cochlear implant system is a common complication that can lead to a deterioration in the patient’s quality of life due to significant discomfort and restrictions on the use of the cochlear implant system. The debut of twitching of facial muscles in patients after cochlear implantation can occur both at the stage of connecting the speech processor and at the stages of further rehabilitation, which according to world literature can reach an interval of 10 years from the moment of surgery. Anatomical features of the cochlea, its interposition with the facial nerve, changes in the bone labyrinth, further progression of remodeling or ossification of the cochlea play a significant role in the development of symptoms of facial nerve stimulation in patients with sensorineural hearing loss of the IV degree, including at the stage of subsequent settings of the speech processor. The frequency of occurrence of this complication in various literature sources varies from 1 to 14.9 %. The purpose of this work is to review the world literature on the etiology of facial nerve stimulation in users of cochlear implants, highlighting the main theories of the origin of non-auditory sensations in this category of patients, since the data conducted in various studies are variable, and with a certain etiology reaches 38 %.
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Smith, O. D., A. M. Neumann, and K. S. Sirimanna. "Occipital meningocele and Mondini deformity of the cochlea." Journal of Laryngology & Otology 115, no. 1 (January 2001): 71–73. http://dx.doi.org/10.1258/0022215011906876.
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We present two cases of a previously unreported association between occipital meningocele and Mondini deformity of the cochlea. The probability of the association is supported by the intimate relationship between the development of these structures; the existence of dysembryoplastic factors that can cause both abnormalities; and the universal existence of cochlear abnormalities in anencephalic foetuses. The importance of considering the association is emphasized, in terms of early identification and referral of children with hearing loss, and avoidance of duplication of investigations.
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Hwang, Chan Ho. "Development of Vestibular Organ and Cochlea." Korean Journal of Otorhinolaryngology-Head and Neck Surgery 53, no. 5 (2010): 265. http://dx.doi.org/10.3342/kjorl-hns.2010.53.5.265.
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Wangemann, Philine, Hyoung-Mi Kim, Sara Billings, Kazuhiro Nakaya, Xiangming Li, Ruchira Singh, David S. Sharlin, Douglas Forrest, Daniel C. Marcus, and Peying Fong. "Developmental delays consistent with cochlear hypothyroidism contribute to failure to develop hearing in mice lacking Slc26a4/pendrin expression." American Journal of Physiology-Renal Physiology 297, no. 5 (November 2009): F1435—F1447. http://dx.doi.org/10.1152/ajprenal.00011.2009.
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Mutations of SLC26A4 cause an enlarged vestibular aqueduct, nonsyndromic deafness, and deafness as part of Pendred syndrome. SLC26A4 encodes pendrin, an anion exchanger located in the cochlea, thyroid, and kidney. The goal of the present study was to determine whether developmental delays, possibly mediated by systemic or local hypothyroidism, contribute to the failure to develop hearing in mice lacking Slc26a4 ( Slc26a4−/−). We evaluated thyroid function by voltage and pH measurements, by array-assisted gene expression analysis, and by determination of plasma thyroxine levels. Cochlear development was evaluated for signs of hypothyroidism by microscopy, in situ hybridization, and quantitative RT-PCR. No differences in plasma thyroxine levels were found in Slc26a4−/− and sex-matched Slc26a4+/− littermates between postnatal day 5 ( P5) and P90. In adult Slc26a4−/− mice, the transepithelial potential and the pH of thyroid follicles were reduced. No differences in the expression of genes that participate in thyroid hormone synthesis or ion transport were observed at P15, when plasma thyroxine levels peaked. Scala media of the cochlea was 10-fold enlarged, bulging into and thereby displacing fibrocytes, which express Dio2 to generate a cochlear thyroid hormone peak at P7. Cochlear development, including tunnel opening, arrival of efferent innervation at outer hair cells, endochondral and intramembraneous ossification, and developmental changes in the expression of Dio2, Dio3, and Tectb were delayed by 1–4 days. These data suggest that pendrin functions as a HCO3− transporter in the thyroid, that Slc26a4−/− mice are systemically euthyroid, and that delays in cochlear development, possibly due to local hypothyroidism, lead to the failure to develop hearing.
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Szalai, R., K. Tsaneva-Atanasova, M. E. Homer, A. R. Champneys, H. J. Kennedy, and N. P. Cooper. "Nonlinear models of development, amplification and compression in the mammalian cochlea." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1954 (November 13, 2011): 4183–204. http://dx.doi.org/10.1098/rsta.2011.0192.
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This paper reviews current understanding and presents new results on some of the nonlinear processes that underlie the function of the mammalian cochlea. These processes occur within mechano-sensory hair cells that form part of the organ of Corti. After a general overview of cochlear physiology, mathematical modelling results are presented in three parts. First, the dynamic interplay between ion channels within the sensory inner hair cells is used to explain some new electrophysiological recordings from early development. Next, the state of the art is reviewed in modelling the electro-motility present within the outer hair cells (OHCs), including the current debate concerning the role of cell body motility versus active hair bundle dynamics. A simplified model is introduced that combines both effects in order to explain observed amplification and compression in experiments. Finally, new modelling evidence is presented that structural longitudinal coupling between OHCs may be necessary in order to capture all features of the observed mechanical responses.
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Chan, Jeffrey, Ravi Telang, Dagmara Kociszewska, Peter R. Thorne, and Srdjan M. Vlajkovic. "A High-Fat Diet Induces Low-Grade Cochlear Inflammation in CD-1 Mice." International Journal of Molecular Sciences 23, no. 9 (May 6, 2022): 5179. http://dx.doi.org/10.3390/ijms23095179.
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There is growing evidence for a relationship between gut dysbiosis and hearing loss. Inflammatory bowel disease, diet-induced obesity (DIO), and type 2 diabetes have all been linked to hearing loss. Here, we investigated the effect of a chronic high-fat diet (HFD) on the development of inner ear inflammation using a rodent model. Three-week-old CD-1 (Swiss) mice were fed an HFD or a control diet for ten weeks. After ten weeks, mouse cochleae were harvested, and markers of cochlear inflammation were assessed at the protein level using immunohistochemistry and at the gene expression level using quantitative real-time RT-PCR. We identified increased immunoexpression of pro-inflammatory biomarkers in animals on an HFD, including intracellular adhesion molecule 1 (ICAM1), interleukin 6 receptor α (IL6Ra), and toll-like-receptor 2 (TLR2). In addition, increased numbers of ionized calcium-binding adapter molecule 1 (Iba1) positive macrophages were found in the cochlear lateral wall in mice on an HFD. In contrast, gene expression levels of inflammatory markers were not affected by an HFD. The recruitment of macrophages to the cochlea and increased immunoexpression of inflammatory markers in mice fed an HFD provide direct evidence for the association between HFD and cochlear inflammation.
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Fermin, Cesar D. "Tritiated thymidine in the chick embryo inner ear." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 846–47. http://dx.doi.org/10.1017/s0424820100156213.
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Development of the chick (Gallus domesticus) inner ear has been studied, and the maturation of cells that detect sound has been analyzed at the E.M. level [1,2,3]. Other workers showed correspondence between ultrastructural maturation and behavioral responses [4,5]. In mammals [6] hair cells mature after ceasation of mitosis {Fig.l}, in a pattern so that older cells are in the base of the cochlea while younger cells are in the apex [7]. But, electrophysiology indicates that cells at the base do not function first. Chicks are precocious with well developed sensory organs at birth, and their embryonic development follows, on a very short time span, a sequence that resembles that of the human ear. This study was undertaken to standarize tritiated thymidine (TT) because resolution of TT in avian embryos differs significantly from mammals [6]. Embryos were injected with 100 μl of TT, and sacrificed 1 or 2 hours later in order to label only those cells that were actively dividing cells at the time of the injection. Specimens were fixed and processed for autoradiography [6].Actively dividing cells incorporate TT after short exposure, with minimal background. It seems that vestibular sensory epithelia {Fig.2} have more dividing cells than the auditory sensory epithelia {Fig.3}, even though the vestibule develop before the cochlea. The ratio between the number of labeled cells over the length of the sensory epithelia is lower in the auditory basilar papilla (0.098 cell/(μm) than in the vestibular utricle (0.77 cell/μm) and saccule (1.66 cell/ μm). When dividing cells were analyzed in the basilar papilla alone, and their distribution displayed along the length of the cochlea over time, older cells were opposite to the VIIIth nerve fibers that innervate those hair cells. A lateral and a longitudinal gradient has been established and hair cells closer to the nerve in the mid-basal area mature earlier than hair cells at both ends of the cochlea [2]. This finding, if occuring in mammals, may explain why mid-frequency are the first to appear [5]. The first 1/3 of the chick cochlea contains mainly short hair cells and are innervated primarily by efferent nerve fibers, which arrive in the cochlea almost a week after the afferent do. Moreover, tall hair cells extend 2/3 of the cochlear length from apex to mid-base and show mature innervation patterns before the short hair cells do. In the short embryonic cochlea, frequencies may be produced first in the what will later be the mid-region because, early in development, that area contains more mature receptors [1,2,3].
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Son, Eun Jin, Ji-Hyun Ma, Harinarayana Ankamreddy, Jeong-Oh Shin, Jae Young Choi, Doris K. Wu, and Jinwoong Bok. "Conserved role of Sonic Hedgehog in tonotopic organization of the avian basilar papilla and mammalian cochlea." Proceedings of the National Academy of Sciences 112, no. 12 (March 9, 2015): 3746–51. http://dx.doi.org/10.1073/pnas.1417856112.
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Sound frequency discrimination begins at the organ of Corti in mammals and the basilar papilla in birds. Both of these hearing organs are tonotopically organized such that sensory hair cells at the basal (proximal) end respond to high frequency sound, whereas their counterparts at the apex (distal) respond to low frequencies. Sonic hedgehog (Shh) secreted by the developing notochord and floor plate is required for cochlear formation in both species. In mice, the apical region of the developing cochlea, closer to the ventral midline source of Shh, requires higher levels of Shh signaling than the basal cochlea farther away from the midline. Here, gain-of-function experiments using Shh-soaked beads in ovo or a mouse model expressing constitutively activated Smoothened (transducer of Shh signaling) show up-regulation of apical genes in the basal cochlea, even though these regionally expressed genes are not necessarily conserved between the two species. In chicken, these altered gene expression patterns precede morphological and physiological changes in sensory hair cells that are typically associated with tonotopy such as the total number of stereocilia per hair cell and gene expression of an inward rectifier potassium channel, IRK1, which is a bona fide feature of apical hair cells in the basilar papilla. Furthermore, our results suggest that this conserved role of Shh in establishing cochlear tonotopy is initiated early in development by Shh emanating from the notochord and floor plate.
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Li, Xiao-Jun, and Angelika Doetzlhofer. "LIN28B/let-7control the ability of neonatal murine auditory supporting cells to generate hair cells through mTOR signaling." Proceedings of the National Academy of Sciences 117, no. 36 (August 21, 2020): 22225–36. http://dx.doi.org/10.1073/pnas.2000417117.
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Mechano-sensory hair cells within the inner ear cochlea are essential for the detection of sound. In mammals, cochlear hair cells are only produced during development and their loss, due to disease or trauma, is a leading cause of deafness. In the immature cochlea, prior to the onset of hearing, hair cell loss stimulates neighboring supporting cells to act as hair cell progenitors and produce new hair cells. However, for reasons unknown, such regenerative capacity (plasticity) is lost once supporting cells undergo maturation. Here, we demonstrate that the RNA binding protein LIN28B plays an important role in the production of hair cells by supporting cells and provide evidence that the developmental drop in supporting cell plasticity in the mammalian cochlea is, at least in part, a product of declining LIN28B-mammalian target of rapamycin (mTOR) activity. Employing murine cochlear organoid and explant cultures to model mitotic and nonmitotic mechanisms of hair cell generation, we show that loss of LIN28B function, due to its conditional deletion, or due to overexpression of the antagonistic miRNAlet-7g, suppressed Akt-mTOR complex 1 (mTORC1) activity and renders young, immature supporting cells incapable of generating hair cells. Conversely, we found that LIN28B overexpression increased Akt-mTORC1 activity and allowed supporting cells that were undergoing maturation to de-differentiate into progenitor-like cells and to produce hair cells via mitotic and nonmitotic mechanisms. Finally, using the mTORC1 inhibitor rapamycin, we demonstrate that LIN28B promotes supporting cell plasticity in an mTORC1-dependent manner.
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BALCIOĞLU, Esra, Gözde Özge ÖNDER, Betül YALÇIN, Pınar BİLGİCİ, Menekşe ÜLGER, Arzu YAY, Mehtap N. İSARİ, and Mehmet Akif SOMDAŞ. "RAT COCHLEA CONTINUES TO DEVELOP AFTER BIRTH." Gevher Nesibe Journal IESDR 6, no. 12 (May 25, 2021): 104–11. http://dx.doi.org/10.46648/gnj.205.
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Introduction: The ear, originates from the ectoderm, exhibits a complex structure that differs from species to species in terms of development. Objectives: This study was conducted to describe the prenatal and postnatal development process of the organ of Corti in the iner ear using light microscopy. Methods: In this study, Wistar Albino rats were used. The rats were divided into two groups as prenatal and postnatal groups. Prenatal groups consisting of embryos on day 17, 19, 21 and postnatal groups consisting of pups on days 1, 5, 10 and 15. The rats were sacrificed to investigate the cochleas by light microscopy. Results: The lumen of the cochlear tunnel was lined with pseudostratified columnar epithelia throughout the prenatal period. The cochlear tunnel was not divided into scala media, scala tympani and scala vestibuli in the embryonic sections. Organ of corti hasn’t taken its final form until postnatal day 15. Conclusion: In rats, formation of organ of Corti is completed in postnatal 15 day. Pups of rats are not able to hear in the embronic and early postnatal life.
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Munnamalai, Vidhya, Nabilah H. Sammudin, Caryl A. Young, Ankita Thawani, Richard J. Kuhn, and Donna M. Fekete. "Embryonic and Neonatal Mouse Cochleae Are Susceptible to Zika Virus Infection." Viruses 13, no. 9 (September 14, 2021): 1823. http://dx.doi.org/10.3390/v13091823.
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Congenital Zika Syndrome (CZS) is caused by vertical transmission of Zika virus (ZIKV) to the gestating human fetus. A subset of CZS microcephalic infants present with reduced otoacoustic emissions; this test screens for hearing loss originating in the cochlea. This observation leads to the question of whether mammalian cochlear tissues are susceptible to infection by ZIKV during development. To address this question using a mouse model, the sensory cochlea was explanted at proliferative, newly post-mitotic or maturing stages. ZIKV was added for the first 24 h and organs cultured for up to 6 days to allow for cell differentiation. Results showed that ZIKV can robustly infect proliferating sensory progenitors, as well as post-mitotic hair cells and supporting cells. Virus neutralization using ZIKV-117 antibody blocked cochlear infection. AXL is a cell surface molecule known to enhance the attachment of flavivirus to host cells. While Axl mRNA is widely expressed in embryonic cochlear tissues susceptible to ZIKV infection, it is selectively downregulated in the post-mitotic sensory organ by E15.5, even though these cells remain infectible. These findings may offer insights into which target cells could potentially contribute to hearing loss resulting from fetal exposure to ZIKV in humans.
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Bulankina, A. V., and T. Moser. "Neural Circuit Development in the Mammalian Cochlea." Physiology 27, no. 2 (April 2012): 100–112. http://dx.doi.org/10.1152/physiol.00036.2011.
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The organ of Corti, the sensory epithelium of the mammalian auditory system, uses afferent and efferent synapses for encoding auditory signals and top-down modulation of cochlear function. During development, the final precisely ordered sensorineural circuit is established following excessive formation of afferent and efferent synapses and subsequent refinement. Here, we review the development of innervation of the mouse organ of Corti and its regulation.
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Santi, Peter A., Ian Rapson, and Arne Voie. "Development of the mouse cochlea database (MCD)." Hearing Research 243, no. 1-2 (September 2008): 11–17. http://dx.doi.org/10.1016/j.heares.2008.04.014.
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Kim, Ji Hyun, Jose Francisco Rodríguez-Vázquez, Samuel Verdugo-López, Kwang Ho Cho, Gen Murakami, and Baik Hwan Cho. "Early Fetal Development of the Human Cochlea." Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology 294, no. 6 (April 28, 2011): 996–1002. http://dx.doi.org/10.1002/ar.21387.
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Hussain, Raabid, Attila Frater, Roger Calixto, Chadlia Karoui, Jan Margeta, Zihao Wang, Michel Hoen, et al. "Anatomical Variations of the Human Cochlea Using an Image Analysis Tool." Journal of Clinical Medicine 12, no. 2 (January 8, 2023): 509. http://dx.doi.org/10.3390/jcm12020509.
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Understanding cochlear anatomy is crucial for developing less traumatic electrode arrays and insertion guidance for cochlear implantation. The human cochlea shows considerable variability in size and morphology. This study analyses 1000+ clinical temporal bone CT images using a web-based image analysis tool. Cochlear size and shape parameters were obtained to determine population statistics and perform regression and correlation analysis. The analysis revealed that cochlear morphology follows Gaussian distribution, while cochlear dimensions A and B are not well-correlated to each other. Additionally, dimension B is more correlated to duct lengths, the wrapping factor and volume than dimension A. The scala tympani size varies considerably among the population, with the size generally decreasing along insertion depth with dimensional jumps through the trajectory. The mean scala tympani radius was 0.32 mm near the 720° insertion angle. Inter-individual variability was four times that of intra-individual variation. On average, the dimensions of both ears are similar. However, statistically significant differences in clinical dimensions were observed between ears of the same patient, suggesting that size and shape are not the same. Harnessing deep learning-based, automated image analysis tools, our results yielded important insights into cochlear morphology and implant development, helping to reduce insertion trauma and preserving residual hearing.
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Ashmore, Jonathan. "The neuroscience of hearing or how to do a hard job with soft components." Brain and Neuroscience Advances 2 (January 2018): 239821281881068. http://dx.doi.org/10.1177/2398212818810687.
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The inner ear is a small and relatively inaccessible structure. The use of multiple biophysical recording techniques from the late 1970s onwards, combined with molecular genetics to identify genes critically involved in cochlear development, has revealed how the cochlea acts as the front end for the central nervous system analysis of the auditory world. Some notable progress has been made in clarifying the mechanisms of frequency coding and cochlear amplification, and of mechano-transduction in hair cells and in establishing molecules necessary for normal (and by implication in abnormal) development of hearing and balance. There has been a parallel growth in understanding some of the neural networks in the brainstem and cortical areas responsible for processing the information derived from the auditory nerve. Informing future technical improvements to hearing aids and cochlear implants (electrically and optogenetically encoded), this chapter concentrates mainly on the neuroscience of peripheral hearing.
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Chen, Jun, Feng Wang, Xue Gao, Dingjun Zha, Tao Xue, Xin Cheng, Cuiping Zhong, Yu Han, and Jianhua Qiu. "Decreased level of cyclin A2 in rat cochlea development and cochlear stem cell differentiation." Neuroscience Letters 453, no. 3 (April 2009): 166–69. http://dx.doi.org/10.1016/j.neulet.2009.02.019.
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Kitajiri, Shin-ichiro, Kanehisa Fukumoto, Masaki Hata, Hiroyuki Sasaki, Tatsuya Katsuno, Takayuki Nakagawa, Juichi Ito, Shoichiro Tsukita, and Sachiko Tsukita. "Radixin deficiency causes deafness associated with progressive degeneration of cochlear stereocilia." Journal of Cell Biology 166, no. 4 (August 16, 2004): 559–70. http://dx.doi.org/10.1083/jcb.200402007.
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Ezrin/radixin/moesin (ERM) proteins cross-link actin filaments to plasma membranes to integrate the function of cortical layers, especially microvilli. We found that in cochlear and vestibular sensory hair cells of adult wild-type mice, radixin was specifically enriched in stereocilia, specially developed giant microvilli, and that radixin-deficient (Rdx−/−) adult mice exhibited deafness but no obvious vestibular dysfunction. Before the age of hearing onset (∼2 wk), in the cochlea and vestibule of Rdx−/− mice, stereocilia developed normally in which ezrin was concentrated. As these Rdx−/− mice grew, ezrin-based cochlear stereocilia progressively degenerated, causing deafness, whereas ezrin-based vestibular stereocilia were maintained normally in adult Rdx−/− mice. Thus, we concluded that radixin is indispensable for the hearing ability in mice through the maintenance of cochlear stereocilia, once developed. In Rdx−/− mice, ezrin appeared to compensate for radixin deficiency in terms of the development of cochlear stereocilia and the development/maintenance of vestibular stereocilia. These findings indicated the existence of complicate functional redundancy in situ among ERM proteins.