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Kortas A, Pomianowski A, Kolecka M, Rytel L. Sensorineural deafness in purebred white Devon Rex cats. J Vet Intern Med 2024; 38:1120-1126. [PMID: 38332646 PMCID: PMC10937476 DOI: 10.1111/jvim.17007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 01/24/2024] [Indexed: 02/10/2024] Open
Abstract
BACKGROUND Data regarding congenital sensorineural deafness (CSD) in client-owned, white Devon Rex cats is limited because most of the information on this disease comes from experiments on mixed-breed cats. OBJECTIVES Provide data on the occurrence of CSD in a population of client-owned purebred white Devon Rex cats. ANIMALS Forty client-owned, purebred, white Devon Rex cats examined at 2 different facilities. Median age of the examined cats was 19 weeks. METHODS Hearing status was defined by use of brainstem auditory evoked responses. RESULTS The occurrence of sensorineural deafness in the studied population of Devon Rex cats was estimated at 10%. Unilateral and bilateral deafness occurred equally often, with 2 individuals having each (ie, 5.0%). No association between the occurrence of CSD and sex could be found, χ2 (1, n = 40) = 0.001 (P > .99). No association between blue irises and deafness was noted in the studied population, χ2 (1, n = 40) < 0.01 (P > .99). CONCLUSIONS The occurrence of CSD in a population of client-owned, white Devon Rex cats was found to be lower compared with data obtained in previously conducted studies of deafness in purebred cats. In the studied population of Devon Rex cats, no association between blue irises and CSD was found.
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Affiliation(s)
- Annemarie Kortas
- Department of Internal Diseases with Clinic, Faculty of Veterinary MedicineUniversity of Warmia and MazuryOlsztynPoland
| | - Andrzej Pomianowski
- Department of Internal Diseases with Clinic, Faculty of Veterinary MedicineUniversity of Warmia and MazuryOlsztynPoland
| | - Malgorzata Kolecka
- Neurology and Neurosurgery DepartmentSmall Animal Clinic KalbachFrankfurtGermany
| | - Liliana Rytel
- Department of Internal Diseases with Clinic, Faculty of Veterinary MedicineUniversity of Warmia and MazuryOlsztynPoland
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Annemarie K, Liliana R, Małgorzata K, Andrzej P. Evaluation of the prevalence of congenital sensorineural deafness in a population of 72 client-owned purebred white cats examined from 2007 to 2021. BMC Vet Res 2022; 18:287. [PMID: 35869465 PMCID: PMC9306025 DOI: 10.1186/s12917-022-03378-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 07/05/2022] [Indexed: 11/10/2022] Open
Abstract
Background Data on sensorineural deafness (CSD) in purebred white client-owned cats is limited as most of the information on this disease entity is assured from mixed-breed experimental colonies. It is known that cats with blue irises are more predisposed to CSD having been described as a condition in which many structures in the inner ear are damaged resulting in hearing loss. Cats with CSD are born deaf or lose their hearing irreversibly within the first 4-5 weeks of life. It is important to diagnose cats with this hereditary condition in order to eliminate affected individuals from breeding. The objectives of this study were to ensure data on prevalence of CSD in a population of 72 client-owned purebred white cats in Poland according to the color of the irises and to determine if there are any predispositions with regard to CSD among different breeds of cats in which the dominant W gene is present. Results Conducted study included 72 purebred white cats from six different breeds. The prevalence of CSD in the conducted study was 16.7%, CI95 [8.9%; 23.3%]. Unilateral deafness (11.1%, CI95 [4.9%; 20.7%]) was more common than bilateral CSD (5.6%, CI95 [1.5%; 13.6%]). The studies did not show any association between sex and CSD, p = .46. No association between the blue color of irises and deafness in the studied population could be found, p = .91. When compared to the rest of the examined population, no association was found between CSD and a particular breed. Conclusions Overall prevalence of CSD regarding the examined population of purebred client-owned cats was reported as lower when compared to previous studies concerning purebred cats. Cats with blue irises are more likely to be deaf in accordance to the current state of knowledge, however in the conducted study, no significant association between the presence of blue irises and deafness in white purebred cats could be identified. In order to eliminate CSD from the population, it is necessary to conduct examinations and diagnose CSD in white cats with blue irises as well as with irises of color other than blue. Association between particular breed and CSD wasn’t identified.
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3
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Mari L, Freeman J, Van Dijk J, De Risio L. Prevalence of congenital sensorineural deafness in a population of client-owned purebred kittens in the United Kingdom. J Vet Intern Med 2019; 33:1707-1713. [PMID: 31144374 PMCID: PMC6639530 DOI: 10.1111/jvim.15515] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 05/01/2019] [Indexed: 01/08/2023] Open
Abstract
Background Data about congenital sensorineural deafness (CSD) in white blue‐eyed cats derive mainly from research colonies, and information about client‐owned cats is limited. Objectives To describe the prevalence of CSD in a client‐owned population of white purebred kittens and colored littermates in the United Kingdom. Animals One hundred thirty‐two solid white client‐owned purebred kittens and 61 colored littermates, 6 to 21 weeks of age. Methods Retrospective (56 cases) and prospective (137 cases) study. Hearing was assessed by brainstem auditory evoked response testing, and the entire litter was tested. Results Congenital sensorineural deafness was diagnosed only in solid white kittens, with a prevalence of 30.3% (15.9% bilateral, 14.4% unilateral). The prevalence of CSD was significantly higher in white kittens with 1 (44.4%) or 2 (50%) blue irises than in those without blue irises (22.2%). Kittens with at least 1 blue iris were 3.2 times more likely to have CSD than kittens without blue irises. In solid white kittens, CSD was diagnosed in 7 of 15 (46.7%) Turkish Vankedisi, 8 of 18 (44.0%) Maine Coon, 18 of 41 (43.9%) Norwegian Forest, 3 of 11 (27.3%) British Shorthair, 2 of 12 (16.7%) Devon Rex, 2 of 12 (8.3%) Persian, 1 of 21 (4.8%) Russian, and 0 of 2 Sphinx. The prevalence of CSD was significantly different in Norwegian Forest, Maine Coon, and Turkish Vankedisi kittens compared with Persian or Russian kittens. Conclusion and Clinical Importance We identified a high prevalence of CSD in a population of client‐owned purebred white kittens in the United Kingdom and suggest differences in breed‐specific prevalence of CSD.
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Affiliation(s)
- Lorenzo Mari
- Neurology/Neurosurgery Service, Center for Small Animal Studies, Animal Health Trust, Newmarket, United Kingdom
| | - Julia Freeman
- Neurology/Neurosurgery Service, Center for Small Animal Studies, Animal Health Trust, Newmarket, United Kingdom
| | - Jan Van Dijk
- Centre for Preventive Medicine, Animal Health Trust, Newmarket, United Kingdom
| | - Luisa De Risio
- Neurology/Neurosurgery Service, Center for Small Animal Studies, Animal Health Trust, Newmarket, United Kingdom
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4
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Abstract
Practical relevance: Auditory function is a sense that is central to life for cats - being important in situational awareness of potential predators, pursuit of prey, and for communication with conspecifics, humans and other species. Deafness in cats is most frequently the result of a genetic disorder, strongly associated with white fur and blue eyes, but may also result from acquired causes such as advancing age, ototoxic drugs, infection, environmental noise and physical trauma. Deafness can be sensorineural, where there is loss of cochlear hair cells, or conductive, where sound is muffled on its way to the inner ear. Clinical challenges: Establishing whether a cat is deaf can be difficult as behavioral testing of hearing is subjective and does not reliably detect unilateral deafness. Brainstem auditory evoked response testing is an objective measure but is limited in its availability. Currently, sensorineural deafness is irreversible because no treatments are available to restore lost hair cells. Conductive hearing loss can usually be treated, although full hearing recovery following otitis media may take weeks as the body clears the middle ear of debris. Evidence base: The author draws on the published literature and his extensive research on clinical aspects and molecular genetics of deafness, principally in companion animals, to review types and forms of deafness in cats. He also discusses current diagnostic approaches and provides brief advice for managing cats with hearing loss.
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Affiliation(s)
- George M Strain
- Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
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5
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Abstract
Although deafness can be acquired throughout an animal's life from a variety of causes, hereditary deafness, especially congenital hereditary deafness, is a significant problem in several species. Extensive reviews exist of the genetics of deafness in humans and mice, but not for deafness in domestic animals. Hereditary deafness in many species and breeds is associated with loci for white pigmentation, where the cochlear pathology is cochleo-saccular. In other cases, there is no pigmentation association and the cochlear pathology is neuroepithelial. Late onset hereditary deafness has recently been identified in dogs and may be present but not yet recognized in other species. Few genes responsible for deafness have been identified in animals, but progress has been made for identifying genes responsible for the associated pigmentation phenotypes. Across species, the genes identified with deafness or white pigmentation patterns include MITF, PMEL, KIT, EDNRB, CDH23, TYR, and TRPM1 in dog, cat, horse, cow, pig, sheep, ferret, mink, camelid, and rabbit. Multiple causative genes are present in some species. Significant work remains in many cases to identify specific chromosomal deafness genes so that DNA testing can be used to identify carriers of the mutated genes and thereby reduce deafness prevalence.
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Affiliation(s)
- George M. Strain
- Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
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6
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David VA, Menotti-Raymond M, Wallace AC, Roelke M, Kehler J, Leighty R, Eizirik E, Hannah SS, Nelson G, Schäffer AA, Connelly CJ, O'Brien SJ, Ryugo DK. Endogenous retrovirus insertion in the KIT oncogene determines white and white spotting in domestic cats. G3 (BETHESDA, MD.) 2014; 4:1881-91. [PMID: 25085922 PMCID: PMC4199695 DOI: 10.1534/g3.114.013425] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/26/2014] [Indexed: 01/06/2023]
Abstract
The Dominant White locus (W) in the domestic cat demonstrates pleiotropic effects exhibiting complete penetrance for absence of coat pigmentation and incomplete penetrance for deafness and iris hypopigmentation. We performed linkage analysis using a pedigree segregating White to identify KIT (Chr. B1) as the feline W locus. Segregation and sequence analysis of the KIT gene in two pedigrees (P1 and P2) revealed the remarkable retrotransposition and evolution of a feline endogenous retrovirus (FERV1) as responsible for two distinct phenotypes of the W locus, Dominant White, and white spotting. A full-length (7125 bp) FERV1 element is associated with white spotting, whereas a FERV1 long terminal repeat (LTR) is associated with all Dominant White individuals. For purposes of statistical analysis, the alternatives of wild-type sequence, FERV1 element, and LTR-only define a triallelic marker. Taking into account pedigree relationships, deafness is genetically linked and associated with this marker; estimated P values for association are in the range of 0.007 to 0.10. The retrotransposition interrupts a DNAase I hypersensitive site in KIT intron 1 that is highly conserved across mammals and was previously demonstrated to regulate temporal and tissue-specific expression of KIT in murine hematopoietic and melanocytic cells. A large-population genetic survey of cats (n = 270), representing 30 cat breeds, supports our findings and demonstrates statistical significance of the FERV1 LTR and full-length element with Dominant White/blue iris (P < 0.0001) and white spotting (P < 0.0001), respectively.
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Affiliation(s)
- Victor A David
- Laboratory of Genomic Diversity, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702
| | - Marilyn Menotti-Raymond
- Laboratory of Genomic Diversity, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702
| | - Andrea Coots Wallace
- Laboratory of Genomic Diversity, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702
| | - Melody Roelke
- Leidos Biomedical Research Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702 Labooratory Animal Sciences Program (LASP) Bethesda Leidos Biomedical Research, Bethesda, Maryland 20892-2471
| | - James Kehler
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20814
| | - Robert Leighty
- Data Management Services, Inc., National Cancer Institute-Frederick, Frederick, Maryland 21702
| | - Eduardo Eizirik
- Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 90619-900, Brazil Instituto Pró-Carnívoros, Atibaia, Sao Paulo 12945-010, Brazil
| | | | - George Nelson
- BSP-CCR Genetics Core, Frederick National Laboratory, Frederick, Maryland 21702
| | - Alejandro A Schäffer
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, Maryland 20894
| | | | - Stephen J O'Brien
- Laboratory of Genomic Diversity, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702 Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg, Russia
| | - David K Ryugo
- Department of Otolaryngology, Head and Neck Surgery, Center for Hearing Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 Garvan Institute of Medical Research, Sydney, New South Wales, Australia
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7
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Butler BE, Lomber SG. Functional and structural changes throughout the auditory system following congenital and early-onset deafness: implications for hearing restoration. Front Syst Neurosci 2013; 7:92. [PMID: 24324409 PMCID: PMC3840613 DOI: 10.3389/fnsys.2013.00092] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 11/03/2013] [Indexed: 11/23/2022] Open
Abstract
The absence of auditory input, particularly during development, causes widespread changes in the structure and function of the auditory system, extending from peripheral structures into auditory cortex. In humans, the consequences of these changes are far-reaching and often include detriments to language acquisition, and associated psychosocial issues. Much of what is currently known about the nature of deafness-related changes to auditory structures comes from studies of congenitally deaf or early-deafened animal models. Fortunately, the mammalian auditory system shows a high degree of preservation among species, allowing for generalization from these models to the human auditory system. This review begins with a comparison of common methods used to obtain deaf animal models, highlighting the specific advantages and anatomical consequences of each. Some consideration is also given to the effectiveness of methods used to measure hearing loss during and following deafening procedures. The structural and functional consequences of congenital and early-onset deafness have been examined across a variety of mammals. This review attempts to summarize these changes, which often involve alteration of hair cells and supporting cells in the cochleae, and anatomical and physiological changes that extend through subcortical structures and into cortex. The nature of these changes is discussed, and the impacts to neural processing are addressed. Finally, long-term changes in cortical structures are discussed, with a focus on the presence or absence of cross-modal plasticity. In addition to being of interest to our understanding of multisensory processing, these changes also have important implications for the use of assistive devices such as cochlear implants.
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Affiliation(s)
- Blake E. Butler
- Cerebral Systems Laboratory, Department of Physiology and Pharmacology, Brain and Mind Institute, University of Western OntarioLondon, ON, Canada
| | - Stephen G. Lomber
- Cerebral Systems Laboratory, Department of Physiology and Pharmacology and Department of Psychology, National Centre for Audiology, Brain and Mind Institute, University of Western OntarioLondon, ON, Canada
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Hancock KE, Chung Y, Delgutte B. Congenital and prolonged adult-onset deafness cause distinct degradations in neural ITD coding with bilateral cochlear implants. J Assoc Res Otolaryngol 2013; 14:393-411. [PMID: 23462803 PMCID: PMC3642270 DOI: 10.1007/s10162-013-0380-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/15/2013] [Indexed: 10/27/2022] Open
Abstract
Bilateral cochlear implant (CI) users perform poorly on tasks involving interaural time differences (ITD), which are critical for sound localization and speech reception in noise by normal-hearing listeners. ITD perception with bilateral CI is influenced by age at onset of deafness and duration of deafness. We previously showed that ITD coding in the auditory midbrain is degraded in congenitally deaf white cats (DWC) compared to acutely deafened cats (ADC) with normal auditory development (Hancock et al., J. Neurosci, 30:14068). To determine the relative importance of early onset of deafness and prolonged duration of deafness for abnormal ITD coding in DWC, we recorded from single units in the inferior colliculus of cats deafened as adults 6 months prior to experimentation (long-term deafened cats, LTDC) and compared neural ITD coding between the three deafness models. The incidence of ITD-sensitive neurons was similar in both groups with normal auditory development (LTDC and ADC), but significantly diminished in DWC. In contrast, both groups that experienced prolonged deafness (LTDC and DWC) had broad distributions of best ITDs around the midline, unlike the more focused distributions biased toward contralateral-leading ITDs present in both ADC and normal-hearing animals. The lack of contralateral bias in LTDC and DWC results in reduced sensitivity to changes in ITD within the natural range. The finding that early onset of deafness more severely degrades neural ITD coding than prolonged duration of deafness argues for the importance of fitting deaf children with sound processors that provide reliable ITD cues at an early age.
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Affiliation(s)
- Kenneth E. Hancock
- />Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, MA 02114 USA
- />Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115 USA
| | - Yoojin Chung
- />Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, MA 02114 USA
- />Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115 USA
| | - Bertrand Delgutte
- />Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, MA 02114 USA
- />Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115 USA
- />Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
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9
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Abstract
Cats have among the best hearing of all mammals in that they are extremely sensitive to a broad range of frequencies. The ear is a highly complex structure that is delicately balanced in terms of its biochemistry, types of receptors, ion channels, mechanical properties, and cellular organization. Sensorineural deafness is caused by "flawed" genes that are inherited from one or both parents. Hearing loss can also be acquired as a result of noise trauma from industrialized environment, viral infection, or blunt trauma. To date, it is not practical to intervene and attempt to correct these forms of deafness in cats.
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Affiliation(s)
- David K Ryugo
- Hearing Research Program, Garvan Institute of Medical Research, Sydney, New South Wales 2010, Australia.
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10
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Tirko NN, Ryugo DK. Synaptic plasticity in the medial superior olive of hearing, deaf, and cochlear-implanted cats. J Comp Neurol 2012; 520:2202-17. [PMID: 22237661 DOI: 10.1002/cne.23038] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The medial superior olive (MSO) is a key auditory brainstem structure that receives binaural inputs and is implicated in processing interaural time disparities used for sound localization. The deaf white cat, a proven model of congenital deafness, was used to examine how deafness and cochlear implantation affected the synaptic organization at this binaural center in the ascending auditory pathway. The patterns of axosomatic and axodendritic organization were determined for principal neurons from the MSO of hearing, deaf, and deaf cats with cochlear implants. The nature of the synapses was evaluated through electron microscopy, ultrastructure analysis of the synaptic vesicles, and immunohistochemistry. The results show that the proportion of inhibitory axosomatic terminals was significantly smaller in deaf animals when compared with hearing animals. However, after a period of electrical stimulation via cochlear implants the proportion of inhibitory inputs resembled that of hearing animals. Additionally, the excitatory axodendritic boutons of hearing cats were found to be significantly larger than those of deaf cats. Boutons of stimulated cats were significantly larger than the boutons in deaf cats, although not as large as in the hearing cats, indicating a partial recovery of excitatory inputs to MSO dendrites after stimulation. These results exemplify dynamic plasticity in the auditory brainstem and reveal that electrical stimulation through cochlear implants has a restorative effect on synaptic organization in the MSO.
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Affiliation(s)
- Natasha N Tirko
- Department of Biomedical Engineering, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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11
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Hancock KE, Chung Y, Delgutte B. Neural ITD coding with bilateral cochlear implants: effect of binaurally coherent jitter. J Neurophysiol 2012; 108:714-28. [PMID: 22592306 DOI: 10.1152/jn.00269.2012] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Poor sensitivity to the interaural time difference (ITD) constrains the ability of human bilateral cochlear implant users to listen in everyday noisy acoustic environments. ITD sensitivity to periodic pulse trains degrades sharply with increasing pulse rate but can be restored at high pulse rates by jittering the interpulse intervals in a binaurally coherent manner (Laback and Majdak. Binaural jitter improves interaural time-difference sensitivity of cochlear implantees at high pulse rates. Proc Natl Acad Sci USA 105: 814-817, 2008). We investigated the neural basis of the jitter effect by recording from single inferior colliculus (IC) neurons in bilaterally implanted, anesthetized cats. Neural responses to trains of biphasic pulses were measured as a function of pulse rate, jitter, and ITD. An effect of jitter on neural responses was most prominent for pulse rates above 300 pulses/s. High-rate periodic trains evoked only an onset response in most IC neurons, but introducing jitter increased ongoing firing rates in about half of these neurons. Neurons that had sustained responses to jittered high-rate pulse trains showed ITD tuning comparable with that produced by low-rate periodic pulse trains. Thus, jitter appears to improve neural ITD sensitivity by restoring sustained firing in many IC neurons. The effect of jitter on IC responses is qualitatively consistent with human psychophysics. Action potentials tended to occur reproducibly at sparse, preferred times across repeated presentations of high-rate jittered pulse trains. Spike triggered averaging of responses to jittered pulse trains revealed that firing was triggered by very short interpulse intervals. This suggests it may be possible to restore ITD sensitivity to periodic carriers by simply inserting short interpulse intervals at select times.
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Affiliation(s)
- Kenneth E Hancock
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.
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12
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Multiple effects of childhood deafness on cortical activity in children receiving bilateral cochlear implants simultaneously. Clin Neurophysiol 2011; 122:823-33. [DOI: 10.1016/j.clinph.2010.10.037] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 10/21/2010] [Accepted: 10/26/2010] [Indexed: 11/22/2022]
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13
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Chen I, Limb CJ, Ryugo DK. The effect of cochlear-implant-mediated electrical stimulation on spiral ganglion cells in congenitally deaf white cats. J Assoc Res Otolaryngol 2010; 11:587-603. [PMID: 20821032 PMCID: PMC2975880 DOI: 10.1007/s10162-010-0234-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 08/13/2010] [Indexed: 10/19/2022] Open
Abstract
It has long been observed that loss of auditory receptor cells is associated with the progressive degeneration of spiral ganglion cells. Chronic electrical stimulation via cochlear implantation has been used in an attempt to slow the rate of degeneration in cats neonatally deafened by ototoxic agents but with mixed results. The present study examined this issue using white cats with a history of hereditary deafness as an alternative animal model. Nineteen cats provided new data for this study: four normal-hearing cats, seven congenitally deaf white cats, and eight congenitally deaf white cats with unilateral cochlear implants. Data from additional cats were collected from the literature. Electrical stimulation began at 3 to 4 or 6 to 7 months after birth, and cats received stimulation for approximately 7 h a day, 5 days a week for 12 weeks. Quantitative analysis of spiral ganglion cell counts, cell density, and cell body size showed no marked improvement between cochlear-implanted and congenitally deaf subjects. Average ganglion cell size from cochlear-implanted and congenitally deaf cats was statistically similar and smaller than that of normal-hearing cats. Cell density from cats with cochlear implants tended to decrease within the upper basal and middle cochlear turns in comparison to congenitally deaf cats but remained at congenitally deaf levels within the lower basal and apical cochlear turns. These results provide no evidence that chronic electrical stimulation enhances spiral ganglion cell survival, cell density, or cell size compared to that of unstimulated congenitally deaf cats. Regardless of ganglion neuron status, there is unambiguous restoration of auditory nerve synapses in the cochlear nucleus of these cats implanted at the earlier age.
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Affiliation(s)
- Iris Chen
- Department of Otolaryngology-HNS, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Traylor 510, 720 Rutland Ave, Baltimore, MD 21205 USA
| | - Charles J. Limb
- Department of Otolaryngology-HNS, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Traylor 510, 720 Rutland Ave, Baltimore, MD 21205 USA
| | - David K. Ryugo
- Department of Otolaryngology-HNS, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Traylor 510, 720 Rutland Ave, Baltimore, MD 21205 USA
- Department of Neuroscience, Center for Hearing and Balance, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Garvan Institute of Medical Research, Darlinghurst, Sydney, NSW 2010 Australia
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14
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Neural coding of interaural time differences with bilateral cochlear implants: effects of congenital deafness. J Neurosci 2010; 30:14068-79. [PMID: 20962228 DOI: 10.1523/jneurosci.3213-10.2010] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Human bilateral cochlear implant users do poorly on tasks involving interaural time differences (ITD), a cue that provides important benefits to the normal hearing, especially in challenging acoustic environments, yet the precision of neural ITD coding in acutely deafened, bilaterally implanted cats is essentially normal (Smith and Delgutte, 2007a). One explanation for this discrepancy is that the extended periods of binaural deprivation typically experienced by cochlear implant users degrades neural ITD sensitivity, by either impeding normal maturation of the neural circuitry or altering it later in life. To test this hypothesis, we recorded from single units in inferior colliculus of two groups of bilaterally implanted, anesthetized cats that contrast maximally in binaural experience: acutely deafened cats, which had normal binaural hearing until experimentation, and congenitally deaf white cats, which received no auditory inputs until the experiment. Rate responses of only half as many neurons showed significant ITD sensitivity to low-rate pulse trains in congenitally deaf cats compared with acutely deafened cats. For neurons that were ITD sensitive, ITD tuning was broader and best ITDs were more variable in congenitally deaf cats, leading to poorer ITD coding within the naturally occurring range. A signal detection model constrained by the observed physiology supports the idea that the degraded neural ITD coding resulting from deprivation of binaural experience contributes to poor ITD discrimination by human implantees.
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15
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O'Neil JN, Limb CJ, Baker CA, Ryugo DK. Bilateral effects of unilateral cochlear implantation in congenitally deaf cats. J Comp Neurol 2010; 518:2382-404. [PMID: 20437534 DOI: 10.1002/cne.22339] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Congenital deafness results in synaptic abnormalities in auditory nerve endings. These abnormalities are most prominent in terminals called endbulbs of Held, which are large, axosomatic synaptic endings whose size and evolutionary conservation emphasize their importance. Transmission jitter, delay, or failures, which would corrupt the processing of timing information, are possible consequences of the perturbations at this synaptic junction. We sought to determine whether electrical stimulation of the congenitally deaf auditory system via cochlear implants would restore the endbulb synapses to their normal morphology. Three and 6-month-old congenitally deaf cats received unilateral cochlear implants and were stimulated for a period of 10-19 weeks by using human speech processors. Implanted cats exhibited acoustic startle responses and were trained to approach their food dish in response to a specific acoustic stimulus. Endbulb synapses were examined by using serial section electron microscopy from cohorts of cats with normal hearing, congenital deafness, or congenital deafness with a cochlear implant. Synapse restoration was evident in endbulb synapses on the stimulated side of cats implanted at 3 months of age but not at 6 months. In the young implanted cats, postsynaptic densities exhibited normal size, shape, and distribution, and synaptic vesicles had density values typical of hearing cats. Synapses of the contralateral auditory nerve in early implanted cats also exhibited synapses with more normal structural features. These results demonstrate that electrical stimulation with a cochlear implant can help preserve central auditory synapses through direct and indirect pathways in an age-dependent fashion.
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Affiliation(s)
- Jahn N O'Neil
- Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Baker CA, Montey KL, Pongstaporn T, Ryugo DK. Postnatal development of the endbulb of held in congenitally deaf cats. Front Neuroanat 2010; 4:19. [PMID: 20640179 PMCID: PMC2904654 DOI: 10.3389/fnana.2010.00019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 04/24/2010] [Indexed: 11/13/2022] Open
Abstract
The endbulbs of Held are formed by the ascending branches of myelinated auditory nerve fibers and represent one of the largest synaptic endings in the brain. Normally, these endings are highly branched and each can form up to 1000 dome-shaped synapses. The deaf white cat is a model of congenital deafness involving a type of cochleosaccular degeneration that mimics the Scheibe deformity in humans. Endbulbs of mature deaf white cats exhibit reduced branching, hypertrophy of postsynaptic densities (PSDs), and changes in synaptic vesicle density. Because cats are essentially deaf at birth, we sought to determine if the progression of brain abnormalities was linked in time to the failure of normal hearing development. The rationale was that the lack of sound-evoked activity would trigger pathologic change in deaf kittens. The cochleae of deaf cats did not exhibit abnormal morphology at birth. After the first postnatal week, however, the presence of a collapsed scala media signaled the difference between deaf and hearing cats. By working backwards in age, endbulbs of deaf cats expressed flattened and elongated PSDs and increased synaptic vesicle density as compared to normal endbulbs. These differences are present at birth in some white kittens, presaging deafness despite their normal cochlear histology. We speculate that hearing pathology is signaled by a perinatal loss of spontaneous bursting activity in auditory nerve fibers or perhaps by some factor released by hair cell synapses before obliteration of the organ of Corti.
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Affiliation(s)
- Christa A Baker
- Department of Otolaryngology, Johns Hopkins University Baltimore, MD, USA
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Cvejic D, Steinberg TA, Kent MS, Fischer A. Unilateral and bilateral congenital sensorineural deafness in client-owned pure-breed white cats. J Vet Intern Med 2009; 23:392-5. [PMID: 19192155 DOI: 10.1111/j.1939-1676.2008.0262.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Congenital sensorineural deafness has been reported frequently in experimental mixed-breed white cats but there is a paucity of data on occurrence of deafness in client-owned pure-breed white cats. OBJECTIVE To describe hearing status in client-owned pure-breed white cats. ANIMALS Eighty-four pure-breed client-owned cats with white coat color of 10 registered breeds presented for routine hearing evaluation before breeding (1995-2008). METHODS Hearing was assessed by click-evoked brainstem auditory evoked response. RESULTS Overall deafness prevalence was 20.2%; 9 cats (10.7%) were bilaterally deaf and 8 cats (9.5%) were unilaterally deaf. There was no association between sex and deafness status (P= .85). Deafness status was associated with iris color (P= .04). CONCLUSIONS AND CLINICAL IMPORTANCE Congenital sensorineural deafness frequently occurs in pure-breed cats with white coat color. Unilateral sensorineural deafness was as common as bilateral deafness.
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Affiliation(s)
- D Cvejic
- Section of Neurology, Clinic of Small Animal Medicine, Department of Veterinary Clinical Sciences, Ludwig Maximilian University, Munich, Germany
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Strain GM. Deafness in blue-eyed white cats: The uphill road to solving polygenic disorders. Vet J 2007; 173:471-2. [PMID: 17317244 DOI: 10.1016/j.tvjl.2006.01.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2006] [Indexed: 11/15/2022]
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Geigy CA, Heid S, Steffen F, Danielson K, Jaggy A, Gaillard C. Does a pleiotropic gene explain deafness and blue irises in white cats? Vet J 2006; 173:548-53. [PMID: 16956778 DOI: 10.1016/j.tvjl.2006.07.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The prevalence of deafness is high in cat populations in which the dominant white gene is segregating. The objective of this study was to investigate whether there is a gene that is responsible for deafness as well as for blue eyes and to establish a plausible mode of inheritance. For this purpose, data from an experimental colony with deaf cats were analyzed. The hearing status was determined by acoustically evoked brain stem responses (BAER). Complex segregation analyses were conducted to find out the most probable mode of inheritance using maximum likelihood procedures. The prevalence of deafness and partial hearing in the experimental colony was 67% and 29%, respectively. The results of the bivariate segregation analysis support the hypothesis of a pleiotropic major gene segregating for deafness and blue iris colour. The high heritability coefficients for both traits, 0.55 and 0.75 respectively, indicate that beside the major gene there is an important influence of polygenic effects.
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Affiliation(s)
- Caroline A Geigy
- Institute of Animal Genetics, Nutrition and Housing, Vetsuisse Faculty of the University of Berne, Switzerland
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Ryugo DK, Montey KL, Wright AL, Bennett ML, Pongstaporn T. Postnatal development of a large auditory nerve terminal: the endbulb of Held in cats. Hear Res 2006; 216-217:100-15. [PMID: 16497457 DOI: 10.1016/j.heares.2006.01.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Revised: 01/09/2006] [Accepted: 01/10/2006] [Indexed: 11/28/2022]
Abstract
The endbulbs of Held are formed by the ascending branches of myelinated auditory nerve fibers and represent one of the largest synaptic endings in the brain. Most of the developmental changes in structure occur during the first 30 postnatal days of age. The neonatal endbulb begins as a flattened expansion with many filopodia, resembling a growth cone and characterized by numerous puncta adherentia and synapses associated with small postsynaptic densities; the most impressive feature of the ending at this age is its highly irregular plasma membrane that interdigitates with that of the postsynaptic spherical bushy cell. During these first 30 days, the number of puncta adherentia diminishes, postsynaptic densities nearly double in size, intermembraneous cisternae emerge, and plasma membranes flatten. These features endow the endbulb with an adult-like appearance. On the other hand, synaptic vesicle density increases progressively from approximately 50/microm2 at birth to 100/microm2 at adulthood. Mitochondria size remains constant over this developmental period but mitochondrial volume fraction increases until 60 days postnatal. Although many features of endbulb morphology stabilize by 30 days, other features suggest that endbulb development continues into the third month of age. Many of these observations correlate with the maturation of physiological response properties and suggest issues for further study.
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Affiliation(s)
- D K Ryugo
- Center for Hearing and Balance, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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