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Persic D, Thomas ME, Pelekanos V, Ryugo DK, Takesian AE, Krumbholz K, Pyott SJ. Regulation of auditory plasticity during critical periods and following hearing loss. Hear Res 2020; 397:107976. [PMID: 32591097 PMCID: PMC8546402 DOI: 10.1016/j.heares.2020.107976] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/15/2020] [Accepted: 04/14/2020] [Indexed: 02/07/2023]
Abstract
Sensory input has profound effects on neuronal organization and sensory maps in the brain. The mechanisms regulating plasticity of the auditory pathway have been revealed by examining the consequences of altered auditory input during both developmental critical periods—when plasticity facilitates the optimization of neural circuits in concert with the external environment—and in adulthood—when hearing loss is linked to the generation of tinnitus. In this review, we summarize research identifying the molecular, cellular, and circuit-level mechanisms regulating neuronal organization and tonotopic map plasticity during developmental critical periods and in adulthood. These mechanisms are shared in both the juvenile and adult brain and along the length of the auditory pathway, where they serve to regulate disinhibitory networks, synaptic structure and function, as well as structural barriers to plasticity. Regulation of plasticity also involves both neuromodulatory circuits, which link plasticity with learning and attention, as well as ascending and descending auditory circuits, which link the auditory cortex and lower structures. Further work identifying the interplay of molecular and cellular mechanisms associating hearing loss-induced plasticity with tinnitus will continue to advance our understanding of this disorder and lead to new approaches to its treatment. During CPs, brain plasticity is enhanced and sensitive to acoustic experience. Enhanced plasticity can be reinstated in the adult brain following hearing loss. Molecular, cellular, and circuit-level mechanisms regulate CP and adult plasticity. Plasticity resulting from hearing loss may contribute to the emergence of tinnitus. Modifying plasticity in the adult brain may offer new treatments for tinnitus.
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Affiliation(s)
- Dora Persic
- University of Groningen, University Medical Center Groningen, Groningen, Department of Otorhinolaryngology and Head/Neck Surgery, 9713, GZ, Groningen, the Netherlands
| | - Maryse E Thomas
- Eaton-Peabody Laboratories, Massachusetts Eye & Ear and Department of Otorhinolaryngology and Head/Neck Surgery, Harvard Medical School, Boston, MA, USA
| | - Vassilis Pelekanos
- Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, University Park, Nottingham, UK
| | - David K Ryugo
- Hearing Research, Garvan Institute of Medical Research, Sydney, NSW, 2010, Australia; School of Medical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia; Department of Otolaryngology, Head, Neck & Skull Base Surgery, St Vincent's Hospital, Sydney, NSW, 2010, Australia
| | - Anne E Takesian
- Eaton-Peabody Laboratories, Massachusetts Eye & Ear and Department of Otorhinolaryngology and Head/Neck Surgery, Harvard Medical School, Boston, MA, USA
| | - Katrin Krumbholz
- Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, University Park, Nottingham, UK
| | - Sonja J Pyott
- University of Groningen, University Medical Center Groningen, Groningen, Department of Otorhinolaryngology and Head/Neck Surgery, 9713, GZ, Groningen, the Netherlands.
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Saalim M, Karjodkar FR, Sansare KP, Sharma SR. Andersen-Tawil Syndrome and Hypothyroidism: A Case Report with an Unusual Association. Int J Appl Basic Med Res 2019; 9:179-181. [PMID: 31392183 PMCID: PMC6652273 DOI: 10.4103/ijabmr.ijabmr_164_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Andersen-Tawil syndrome (ATS) is an autosomal dominant disorder, characterized by the triad of muscular paralysis, skeletal, and craniofacial anomalies and prolonged QT interval on echocardiogram with a tendency toward malignant ventricular arrhythmia. Although the patient may express one or two of the three components of triad, hypothyroidism is an endocrine disorder resulting in the delayed eruption of teeth, defective mineralization of bone and teeth, and speech and hearing deformity. Here, we report a case of ATS with hypothyroidism. To the best of authors' knowledge, no such association has been reported in the literature.
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Affiliation(s)
- Mohd Saalim
- Department of Oral Medicine and Radiology, Nair Hospital Dental College, Mumbai, Maharashtra, India
| | - Freny R Karjodkar
- Department of Oral Medicine and Radiology, Nair Hospital Dental College, Mumbai, Maharashtra, India
| | - Kaustubh P Sansare
- Department of Oral Medicine and Radiology, Nair Hospital Dental College, Mumbai, Maharashtra, India
| | - Sneha R Sharma
- Department of Oral Medicine and Radiology, Nair Hospital Dental College, Mumbai, Maharashtra, India
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Takasu K, Tateno T. In vivo transcranial flavoprotein autofluorescence imaging of tonotopic map reorganization in the mouse auditory cortex with impaired auditory periphery. Hear Res 2019; 377:208-223. [PMID: 30981948 DOI: 10.1016/j.heares.2019.03.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 02/22/2019] [Accepted: 03/24/2019] [Indexed: 12/11/2022]
Abstract
Ototoxic-drug-induced hearing disturbances in the auditory periphery are associated with tonotopic map reorganization and neural activity modulation, as well as changes in neural correlates in the central auditory pathway, including the auditory cortex (AC). Previous studies have reported that peripheral auditory impairment induces AC plasticity that involves changes in the balance of excitatory vs. inhibitory synapses, within existing and newly forming patterns of connectivity. Although we know that such plastic changes modulate sound-evoked neural responses and the organization of tonotopic maps in the primary AC (A1), little is known about the effects of peripheral impairment on other frequency-organized AC subfields, such as the anterior auditory field (AAF) and the secondary auditory cortex (A2). Therefore, to examine ototoxic-drug-induced spatiotemporal effects on AC subfields, we measured sound-evoked neural activity in mice before and after the administration of kanamycin sulfate (1 mg/g body weight) and bumetanide (0.05 mg/g body weight), using in vivo transcranial flavoprotein autofluorescence imaging over a 4-week period. At first, ototoxic treatment gradually reduced responses driven by tone bursts with lower- (≤8 kHz) and middle- (e.g., 16 kHz) range frequencies in all AC subfields. Subsequently, response intensities in the A1 recovered to more than 78% of the pre-drug condition; however, in the AAF and A2, they remained significantly lower and were unchanged over 3 weeks. Furthermore, after drug administration, the best frequency (BF) areas of the lower (4 and 8 kHz) and higher (25 and 32 kHz) ranges in all subfields were reduced and shifted to those of a middle range (centered around 16 kHz) during the 3 weeks following drug administration. Our results also indicated that, compared with A1, BF distributions in the AAF and A2 were sharper around 16 kHz 3 weeks after drug administration. These results indicate that the ototoxic-damage-induced tonotopic map reorganizations that occurred in each of the three AC subfields were similar, but that there were subfield-dependent differences in the extent of response intensities and in the activated areas that were responsive to tone bursts with specific frequencies. Thus, by examining cortical reorganization induced by ototoxic drugs, we may contribute to the understanding of how this reorganization can be caused by peripheral damage.
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Affiliation(s)
- Kengo Takasu
- Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo, 060-0814, Japan.
| | - Takashi Tateno
- Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo, 060-0814, Japan.
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D'Alessandro LM, Harrison RV. Changes to Neural Activation Patterns (c-fos Labeling) in Chinchilla Auditory Midbrain following Neonatal Exposure to an Enhanced Sound Environment. Neural Plast 2018; 2018:7160362. [PMID: 30123254 PMCID: PMC6079364 DOI: 10.1155/2018/7160362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/20/2018] [Accepted: 05/21/2018] [Indexed: 11/18/2022] Open
Abstract
Sensory brain regions show neuroplastic changes following deficits or experimental augmentation of peripheral input during a neonatal period. We have previously shown reorganization of cortical tonotopic maps after neonatal cochlear lesions or exposure to an enhanced acoustic environment. Such experiments probe the cortex and show reorganization, but it is unclear if such changes are intrinsically cortical or reflect projections from modified subcortical regions. Here, we ask whether an enhanced neonatal acoustic environment can induce midbrain (inferior colliculus (IC)) changes. Neonatal chinchillas were chronically exposed to a 70 dB SPL narrowband (2 ± 0.25 kHz) sound stimulus for 4 weeks. In line with previous studies, we hypothesized that such exposure would induce widening of the 2 kHz tonotopic map region in IC. To probe c-fos expression in IC (central nucleus), sound-exposed and nonexposed animals were stimulated with a 2 kHz stimulus for 90 minutes. In sound-exposed subjects, we find no change in the width of the 2 kHz tonotopic region; thus, our hypothesis is not supported. However, we observed a significant increase in the number of c-fos-labeled neurons over a broad region of best frequencies. These data suggest that neonatal sound exposure can modify midbrain regions and thus change the way neurons in IC respond to sound stimulation.
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Affiliation(s)
- Lisa M. D'Alessandro
- Department of Physiology, University of Toronto, Toronto, Canada M5S 1A8
- Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, Canada M5S 3G9
- The Auditory Science Laboratory, Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada M5G 1X8
| | - Robert V. Harrison
- Department of Physiology, University of Toronto, Toronto, Canada M5S 1A8
- Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, Canada M5S 3G9
- The Auditory Science Laboratory, Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada M5G 1X8
- Department of Otolaryngology-Head and Neck Surgery, University of Toronto, Toronto, Canada M5G 2N2
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Abstract
Over the last 30 years a wide range of manipulations of auditory input and experience have been shown to result in plasticity in auditory cortical and subcortical structures. The time course of plasticity ranges from very rapid stimulus-specific adaptation to longer-term changes associated with, for example, partial hearing loss or perceptual learning. Evidence for plasticity as a consequence of these and a range of other manipulations of auditory input and/or its significance is reviewed, with an emphasis on plasticity in adults and in the auditory cortex. The nature of the changes in auditory cortex associated with attention, memory and perceptual learning depend critically on task structure, reward contingencies, and learning strategy. Most forms of auditory system plasticity are adaptive, in that they serve to optimize auditory performance, prompting attempts to harness this plasticity for therapeutic purposes. However, plasticity associated with cochlear trauma and partial hearing loss appears to be maladaptive, and has been linked to tinnitus. Three important forms of human learning-related auditory system plasticity are those associated with language development, musical training, and improvement in performance with a cochlear implant. Almost all forms of plasticity involve changes in synaptic excitatory - inhibitory balance within existing patterns of connectivity. An attractive model applicable to a number of forms of learning-related plasticity is dynamic multiplexing by individual neurons, such that learning involving a particular stimulus attribute reflects a particular subset of the diverse inputs to a given neuron being gated by top-down influences. The plasticity evidence indicates that auditory cortex is a component of complex distributed networks that integrate the representation of auditory stimuli with attention, decision and reward processes.
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Affiliation(s)
- Dexter R F Irvine
- Bionics Institute, East Melbourne, Victoria 3002, Australia; School of Psychological Sciences, Monash University, Victoria 3800, Australia.
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Disappearance of contralateral dominant neural activity of auditory cortex after single-sided deafness in adult rats. Neurosci Lett 2017; 657:171-178. [DOI: 10.1016/j.neulet.2017.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 07/30/2017] [Accepted: 08/01/2017] [Indexed: 11/21/2022]
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Acquired hearing loss and brain plasticity. Hear Res 2017; 343:176-190. [DOI: 10.1016/j.heares.2016.05.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/29/2016] [Accepted: 05/19/2016] [Indexed: 12/19/2022]
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Midbrain Frequency Representation following Moderately Intense Neonatal Sound Exposure in a Precocious Animal Model ( Chinchilla laniger). Neural Plast 2016; 2016:3734646. [PMID: 27895941 PMCID: PMC5118536 DOI: 10.1155/2016/3734646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 09/28/2016] [Indexed: 11/30/2022] Open
Abstract
Auditory brain areas undergo reorganization resulting from abnormal sensory input during early postnatal development. This is evident from studies at the cortical level but it remains unclear whether there is reorganization in the auditory midbrain in a species similar to the human, that is, with early hearing onset. We have explored midbrain plasticity in the chinchilla, a precocious species that matches the human in terms of hearing development. Neonatal chinchillas were chronically exposed to a 2 kHz narrowband sound at 70 dB SPL for 4 weeks. Tonotopic maps in inferior colliculus (central nucleus) were defined based on single neuron characteristic frequency. We hypothesized an overrepresentation of the 2 kHz region of the maps. However, we observed a significant decrease in the proportion of neurons dedicated to the 2 kHz octave band and also away from the exposure frequency at 8 kHz. In addition, we report a significant increase in low frequency representation (<1 kHz), again a change to tonotopic mapping distant to the 2 kHz region. Thus in a precocious species, tonotopic maps in auditory midbrain are altered following abnormal stimulation during development. However, these changes are more complex than the overrepresentation of exposure related frequency regions that are often reported.
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Todt I, Rademacher G, Mutze S, Ramalingam R, Wolter S, Mittmann P, Wagner J, Ernst A. Relationship between intracochlear electrode position and tinnitus in cochlear implantees. Acta Otolaryngol 2015; 135:781-5. [PMID: 25812721 DOI: 10.3109/00016489.2015.1024332] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION Cochlear implant electrode position has an impact on the rate of tinnitus suppression and generation. OBJECTIVE Suppression of pre-operative tinnitus or a generation of a new tinnitus in cochlear implantees is a known effect of cochlear implantation. The aim of the current study was to evaluate different cochlear implant electrode positions and their relationship with tinnitus suppression and tinnitus generation. METHOD This study retrospectively evaluated four groups of CI recipients with radiologically evaluated electrode positions in relation to their subjective tinnitus quality, as evaluated by an analogue loudness scale (ALS) and a questionnaire. Group 1 consisted of 19 patients with a scalar change of the electrode position. Group 2 consisted of 18 patients with a scala tympani position and a perimodiolar electrode. Group 3 consisted of 10 patients with a scala tympani position and a lateral wall electrode. Group 4 consisted of eight patients with a scala vestibuli position. RESULTS An overall tinnitus suppression rate of 45.9% and a generation of a new tinnitus or the deterioration of an existing one of 5.6% were observed. A significant difference in tinnitus suppression was found between groups 1 and groups 2, 3, and 4 in tinnitus suppression and tinnitus generation.
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Gauvin DV, Abernathy MM, Tapp RL, Yoder JD, Dalton JA, Baird TJ. The failure to detect drug-induced sensory loss in standard preclinical studies. J Pharmacol Toxicol Methods 2015; 74:53-74. [DOI: 10.1016/j.vascn.2015.05.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 05/12/2015] [Accepted: 05/27/2015] [Indexed: 12/19/2022]
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Doherty KA, Desjardins JL. The benefit of amplification on auditory working memory function in middle-aged and young-older hearing impaired adults. Front Psychol 2015; 6:721. [PMID: 26097461 PMCID: PMC4456569 DOI: 10.3389/fpsyg.2015.00721] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/14/2015] [Indexed: 11/21/2022] Open
Abstract
Untreated hearing loss can interfere with an individual’s cognitive abilities and intellectual function. Specifically, hearing loss has been shown to negatively impact working memory function, which is important for speech understanding, especially in difficult or noisy listening conditions. The purpose of the present study was to assess the effect of hearing aid use on auditory working memory function in middle-aged and young-older adults with mild to moderate sensorineural hearing loss. Participants completed two objective measures of auditory working memory in aided and unaided listening conditions. An aged matched control group followed the same experimental protocol except they were not fit with hearing aids. All participants’ aided scores on the auditory working memory tests were significantly improved while wearing hearing aids. Thus, hearing aids worn during the early stages of an age-related hearing loss can improve a person’s performance on auditory working memory tests.
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Affiliation(s)
- Karen A Doherty
- Department of Communication Sciences and Disorders, Syracuse University , Syracuse, NY, USA
| | - Jamie L Desjardins
- Department of Rehabilitation Sciences, University of Texas at El Paso , El Paso, TX, USA
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Mishra SK, Boddupally SP, Rayapati D. Auditory Learning in Children With Cochlear Implants. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2015; 58:1052-1060. [PMID: 25812172 DOI: 10.1044/2015_jslhr-h-14-0340] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 02/25/2015] [Indexed: 06/04/2023]
Abstract
PURPOSE The purpose of this study was to examine and characterize the training-induced changes in speech-in-noise perception in children with congenital deafness who have cochlear implants (CIs). METHOD Twenty-seven children with congenital deafness who have CIs were studied. Eleven children with CIs were trained on a speech-in-noise task, number recognition in white noise, at home for 5 weeks (total 40 hr). Speech recognition thresholds (SRTs) in the trained, partially trained (numbers in speech-shaped noise), and untrained (digit triplets in speech-shaped noise) conditions were measured before, immediately after, and 3 weeks after training completion. Data were also collected from children (n = 13) and adults (n = 5) with normal hearing for comparison. RESULTS Analyses indicated that following training, the performance of children with CIs improved for all speech-in-noise tasks (∆SRT was approximately 3 dB). Training-induced improvements in speech-in-noise performance were retained for 3 weeks following cessation of training. Untrained children with CIs showed no such improvements. The performance of children with CIs, even after intensive training, was significantly lower than children and adults with normal hearing. CONCLUSIONS Training enhances speech-in-noise performance for children with congenital deafness who have CIs. Learning effects were stable and generalized to similar but untrained conditions. Current findings are encouraging for the consideration of home-based auditory training to be included in the pediatric CI habilitation programs.
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Benovitski YB, Blamey PJ, Rathbone GD, Fallon JB. Behavioral frequency discrimination ability of partially deafened cats using cochlear implants. Hear Res 2014; 315:61-6. [PMID: 25008966 PMCID: PMC4140999 DOI: 10.1016/j.heares.2014.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 06/15/2014] [Accepted: 06/24/2014] [Indexed: 11/17/2022]
Abstract
The aim of this study was to determine the effects of cochlear implant (CI) use on behavioral frequency discrimination ability in partially deafened cats. We hypothesized that the additional information provided by the CI would allow subjects to perform better on a frequency discrimination task. Four cats with a high frequency hearing loss induced by ototoxic drugs were first trained on a go/no-go, positive reinforcement, frequency discrimination task and reached asymptotic performance (measured by d' - detection theory). Reference frequencies (1, 4, and 7 kHz) were systematically rotated (Block design) every 9-11 days to cover the hearing range of the cats while avoiding bias arising from the order of testing. Animals were then implanted with an intracochlear electrode array connected to a CI and speech processor. They then underwent 6 months of continuous performance measurement with the CI turned on, except for one month when the stimulator was turned off. Overall, subjects performed the frequency discrimination task significantly better with their CI turned on than in the CI-off condition (3-way ANOVA, p < 0.001). The analysis showed no dependence on subject (3-way ANOVA, subject × on-off condition, p > 0.5); however, the CI only significantly improved performance for two (1 and 7 kHz) of the three reference frequencies. In this study we were able to show, for the first time, that cats can utilize information provided by a CI in performing a behavioral frequency discrimination task.
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Affiliation(s)
- Yuri B Benovitski
- Bionics Institute, Australia; Department of Electronic Engineering, La Trobe University, Australia
| | - Peter J Blamey
- Bionics Institute, Australia; Department of Medical Bionics University of Melbourne, Australia; Department of Otolaryngology, University of Melbourne, Australia
| | - Graeme D Rathbone
- Bionics Institute, Australia; Department of Electronic Engineering, La Trobe University, Australia
| | - James B Fallon
- Bionics Institute, Australia; Department of Medical Bionics University of Melbourne, Australia; Department of Otolaryngology, University of Melbourne, Australia.
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Huetz C, Guedin M, Edeline JM. Neural correlates of moderate hearing loss: time course of response changes in the primary auditory cortex of awake guinea-pigs. Front Syst Neurosci 2014; 8:65. [PMID: 24808831 PMCID: PMC4009414 DOI: 10.3389/fnsys.2014.00065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 04/07/2014] [Indexed: 11/21/2022] Open
Abstract
Over the last decade, the consequences of acoustic trauma on the functional properties of auditory cortex neurons have received growing attention. Changes in spontaneous and evoked activity, shifts of characteristic frequency (CF), and map reorganizations have extensively been described in anesthetized animals (e.g., Noreña and Eggermont, 2003, 2005). Here, we examined how the functional properties of cortical cells are modified after partial hearing loss in awake guinea pigs. Single unit activity was chronically recorded in awake, restrained, guinea pigs from 3 days before up to 15 days after an acoustic trauma induced by a 5 kHz 110 dB tone delivered for 1 h. Auditory brainstem responses (ABRs) audiograms indicated that these parameters produced a mean ABR threshold shift of 20 dB SPL at, and one octave above, the trauma frequency. When tested with pure tones, cortical cells showed on average a 25 dB increase in threshold at CF the day following the trauma. Over days, this increase progressively stabilized at only 10 dB above control value indicating a progressive recovery of cortical thresholds, probably reflecting a progressive shift from temporary threshold shift (TTS) to permanent threshold shift (PTS). There was an increase in response latency and in response variability the day following the trauma but these parameters returned to control values within 3 days. When tested with conspecific vocalizations, cortical neurons also displayed an increase in response latency and in response duration the day after the acoustic trauma, but there was no effect on the average firing rate elicited by the vocalization. These findings suggest that, in cases of moderate hearing loss, the temporal precision of neuronal responses to natural stimuli is impaired despite the fact the firing rate showed little or no changes.
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Affiliation(s)
- Chloé Huetz
- Centre de Neurosciences Paris-Sud, CNRS, UMR 8195, Université Paris-Sud Orsay, France
| | - Maud Guedin
- Centre de Neurosciences Paris-Sud, CNRS, UMR 8195, Université Paris-Sud Orsay, France
| | - Jean-Marc Edeline
- Centre de Neurosciences Paris-Sud, CNRS, UMR 8195, Université Paris-Sud Orsay, France
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Grande G, Negandhi J, Harrison RV, Wang LY. Remodelling at the calyx of Held-MNTB synapse in mice developing with unilateral conductive hearing loss. J Physiol 2014; 592:1581-600. [PMID: 24469075 DOI: 10.1113/jphysiol.2013.268839] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Structure and function of central synapses are profoundly influenced by experience during developmental sensitive periods. Sensory synapses, which are the indispensable interface for the developing brain to interact with its environment, are particularly plastic. In the auditory system, moderate forms of unilateral hearing loss during development are prevalent but the pre- and postsynaptic modifications that occur when hearing symmetry is perturbed are not well understood. We investigated this issue by performing experiments at the large calyx of Held synapse. Principal neurons of the medial nucleus of the trapezoid body (MNTB) are innervated by calyx of Held terminals that originate from the axons of globular bushy cells located in the contralateral ventral cochlear nucleus. We compared populations of synapses in the same animal that were either sound deprived (SD) or sound experienced (SE) after unilateral conductive hearing loss (CHL). Middle ear ossicles were removed 1 week prior to hearing onset (approx. postnatal day (P) 12) and morphological and electrophysiological approaches were applied to auditory brainstem slices taken from these mice at P17-19. Calyces in the SD and SE MNTB acquired their mature digitated morphology but these were structurally more complex than those in normal hearing mice. This was accompanied by bilateral decreases in initial EPSC amplitude and synaptic conductance despite the CHL being unilateral. During high-frequency stimulation, some SD synapses displayed short-term depression whereas others displayed short-term facilitation followed by slow depression similar to the heterogeneities observed in normal hearing mice. However SE synapses predominantly displayed short-term facilitation followed by slow depression which could be explained in part by the decrease in release probability. Furthermore, the excitability of principal cells in the SD MNTB had increased significantly. Despite these unilateral changes in short-term plasticity and excitability, heterogeneities in the spiking fidelity among the population of both SD and SE synapses showed similar continuums to those in normal hearing mice. Our study suggests that preservations in the heterogeneity in spiking fidelity via synaptic remodelling ensures symmetric functional stability which is probably important for retaining the capability to maximally code sound localization cues despite moderate asymmetries in hearing experience.
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Affiliation(s)
- Giovanbattista Grande
- Corresponding Author L.-Y. Wang, The Hospital for Sick Children, 555 University Ave, Toronto, Ontario, Canada M5G 1X8.
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Sereda M, Adjamian P, Edmondson-Jones M, Palmer AR, Hall DA. Auditory evoked magnetic fields in individuals with tinnitus. Hear Res 2013; 302:50-9. [PMID: 23639335 PMCID: PMC3709092 DOI: 10.1016/j.heares.2013.04.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Revised: 04/11/2013] [Accepted: 04/16/2013] [Indexed: 01/19/2023]
Abstract
Some forms of tinnitus are likely to be perceptual consequences of altered neural activity in the central auditory system triggered by damage to the auditory periphery. Animal studies report changes in the evoked responses after noise exposure or ototoxic drugs in inferior colliculus and auditory cortex. However, human electrophysiological evidence is rather equivocal: increased, reduced or no difference in N1/N1m evoked amplitudes and latencies in tinnitus participants have been reported. The present study used magnetoencephalography to seek evidence for altered evoked responses in people with tinnitus compared to controls (hearing loss matched and normal hearing) in four different stimulus categories (a control tone, a tone corresponding to the audiometric edge, to the dominant tinnitus pitch and a tone within the area of hearing loss). Results revealed that amplitudes of the evoked responses differed depending on the tone category. N1m amplitude to the dominant tinnitus pitch and the frequency within the area of hearing loss were reduced compared to the other two categories. Given that tinnitus pitch is typically within the area of hearing loss, the differences in the evoked responses pattern in tinnitus participants seem to be related more to the hearing loss than to the presence of tinnitus.
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Affiliation(s)
- Magdalena Sereda
- National Institute for Health Research Nottingham Hearing Biomedical Research Unit, School of Clinical Sciences, University of Nottingham, Ropewalk House, 113 The Ropewalk, NG1 5DU, Nottingham, UK.
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Liu X, Basavaraj S, Krishnan R, Yan J. Contributions of the thalamocortical system towards sound-specific auditory plasticity. Neurosci Biobehav Rev 2011; 35:2155-61. [DOI: 10.1016/j.neubiorev.2011.02.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 02/14/2011] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
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Baguley DM, Humphriss RL, Axon PR, Moffat DA. The clinical characteristics of tinnitus in patients with vestibular schwannoma. Skull Base 2011; 16:49-58. [PMID: 17077869 PMCID: PMC1502033 DOI: 10.1055/s-2005-926216] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVES To review the symptoms, signs, and clinical findings in a large series of patients diagnosed with unilateral sporadic vestibular schwannoma (VS) to describe the clinical characteristics of tinnitus in this population. Further, to ascertain which of the proposed mechanisms of tinnitus generation in VS was supported. DESIGN Retrospective case note and database review. SETTING Tertiary university teaching hospital departments of audiology and neuro-otology. PARTICIPANTS Nine hundred forty-one patients with unilateral sporadic VS, diagnosed during the period 1986 to 2002. Twenty-three additional patients were excluded due to missing clinical data. MAIN OUTCOME MEASURES The presence or absence of tinnitus, and its rated subjective severity were analyzed in conjunction with data regarding patient demographics, symptoms, signs, and diagnostic audiovestibular test findings. RESULTS No statistical association at the 5% level was found between tinnitus presence/absence and patient age, gender, 2- to 4-kHz audiometric thresholds, ipsilateral auditory brainstem response abnormality, length of history, tumor side, nor caloric test abnormality. Statistically significant associations were found between tinnitus presence/absence and tumor size (p = 0.012) and type of hearing loss (progressive, sudden, fluctuant, nil) with a tendency for patients without hearing loss to be less likely to experience tinnitus. Statistically significant associations were identified between classification of tinnitus severity and age at diagnosis (p < 0.001) (greater age being associated with greater tinnitus severity), abnormal findings on caloric testing (p = 0.01) (abnormal calorics being associated with greater tinnitus severity), and tinnitus as a principal presenting symptom (p < 0.001) (this being associated with greater tinnitus severity). CONCLUSIONS The analysis does not identify any single one of the proposed mechanisms for tinnitus as being the obvious culprit. In fact, even in a homogeneous group of patients such as this, there is evidence of multiple mechanisms that are not mutually exclusive. The association between increased tinnitus severity in older patients, patients with canal pareses on caloric testing, and with tinnitus as a principal presenting symptom should be borne in mind by the clinician.
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Affiliation(s)
- David M. Baguley
- Department of Audiology, Addenbrooke's Hospital, Cambridge, United Kingdom
| | | | - Patrick R. Axon
- Department of Otolaryngology, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - David A. Moffat
- Department of Otolaryngology, Addenbrooke's Hospital, Cambridge, United Kingdom
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Sereda M, Hall DA, Bosnyak DJ, Edmondson-Jones M, Roberts LE, Adjamian P, Palmer AR. Re-examining the relationship between audiometric profile and tinnitus pitch. Int J Audiol 2011; 50:303-12. [PMID: 21388238 PMCID: PMC3082165 DOI: 10.3109/14992027.2010.551221] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 12/20/2010] [Indexed: 11/20/2022]
Abstract
OBJECTIVE We explored the relationship between audiogram shape and tinnitus pitch to answer questions arising from neurophysiological models of tinnitus: 'Is the dominant tinnitus pitch associated with the edge of hearing loss?' and 'Is such a relationship more robust in people with narrow tinnitus bandwidth or steep sloping hearing loss?' DESIGN A broken-stick fitting objectively quantified slope, degree and edge of hearing loss up to 16 kHz. Tinnitus pitch was characterized up to 12 kHz. We used correlation and multiple regression analyses for examining relationships with many potentially predictive audiometric variables. STUDY SAMPLE 67 people with chronic bilateral tinnitus (43 men and 24 women, aged from 22 to 81 years). RESULTS In this ample of 67 subjects correlation failed to reveal any relationship between the tinnitus pitch and the edge frequency. The tinnitus pitch generally fell within the area of hearing loss. The pitch of the tinnitus in a subset of subjects with a narrow tinnitus bandwidth (n = 23) was associated with the audiometric edge. CONCLUSIONS Our findings concerning subjects with narrow tinnitus bandwidth suggest that this can be used as an a priori inclusion criterion. A large group of such subjects should be tested to confirm these results.
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Affiliation(s)
- Magdalena Sereda
- MRC Institute of Hearing Research, University Park, Nottingham, UK.
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20
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Pienkowski M, Eggermont JJ. Cortical tonotopic map plasticity and behavior. Neurosci Biobehav Rev 2011; 35:2117-28. [PMID: 21315757 DOI: 10.1016/j.neubiorev.2011.02.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 02/02/2011] [Accepted: 02/04/2011] [Indexed: 11/16/2022]
Abstract
Central topographic representations of sensory epithelia have a genetic basis, but are refined by patterns of afferent input and by behavioral demands. Here we review such experience-driven map development and plasticity, focusing on the auditory system, and giving particular consideration to its adaptive value and to the putative mechanisms involved. Recent data have challenged the widely held notion that only the developing auditory brain can be influenced by changes to the prevailing acoustic environment, unless those changes convey information of behavioral relevance. Specifically, it has been shown that persistent exposure of adult animals to random, bandlimited, moderately loud sounds can lead to a reorganization of auditory cortex not unlike that following restricted hearing loss. The mature auditory brain is thus more plastic than previously supposed, with potentially troubling consequences for those working or living in noisy environments, even at exposure levels considerably below those presently considered just-acceptable.
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Affiliation(s)
- Martin Pienkowski
- Hotchkiss Brain Institute, Departments of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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21
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Rajan R, Irvine DRF. Severe and extensive neonatal hearing loss in cats results in auditory cortex plasticity that differentiates into two regions. Eur J Neurosci 2010; 31:1999-2013. [PMID: 20497473 DOI: 10.1111/j.1460-9568.2010.07214.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
We examined the response characteristics of primary auditory cortex (A1) neurons in adult cats partially but extensively deafened by ototoxic drugs 2-8 days after birth. The damage evoked extensive A1 topographic map reorganization as also found by others, but a novel finding was that in the majority of cats with low-frequency edges to the cochlear lesion, the area of reorganization segregated into two areas expressing the same novel frequency inputs but differentiated by neuronal sensitivity and responsiveness. Immediately adjacent to normal A1 is an approximately 1.2-mm-wide area of reorganization in which sensitivity and responsiveness to sound are similar to that in normal A1 in the same animals and in unlesioned adult animals. Extending further into deprived A1 is a more extensive area of reorganization where neurons have poorer sensitivity and responsiveness to new inputs. These two areas did not differ in response-area bandwidth and response latency. We interpret these novel changes as the cortical consequences of severe receptor organ lesions extending to low-frequency cochlear regions. We speculate that the two areas of A1 reorganization may reflect differences in the transcortical spatial distribution of thalamo-cortical and horizontal intracortical connections. Qualitatively similar changes in response properties have been seen after retinal lesions producing large areas of visual cortical reorganization, suggesting they might be a general consequence of receptor lesions that deprive large regions of cortex of normal input. These effects may have perceptual implications for the use of cochlear implants in patients with residual low-frequency hearing.
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Affiliation(s)
- R Rajan
- Department of Physiology, Monash University, Vic. 3800, Australia.
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22
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Fallon JB, Shepherd RK, Brown M, Irvine DRF. Effects of neonatal partial deafness and chronic intracochlear electrical stimulation on auditory and electrical response characteristics in primary auditory cortex. Hear Res 2009; 257:93-105. [PMID: 19703532 PMCID: PMC2803318 DOI: 10.1016/j.heares.2009.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 08/17/2009] [Accepted: 08/18/2009] [Indexed: 10/20/2022]
Abstract
The use of cochlear implants in patients with severe hearing losses but residual low-frequency hearing raises questions concerning the effects of chronic intracochlear electrical stimulation (ICES) on cortical responses to auditory and electrical stimuli. We investigated these questions by studying responses to tonal and electrical stimuli in primary auditory cortex (AI) of two groups of neonatally deafened cats with residual high-threshold, low-frequency hearing. One group were implanted with a multi-channel intracochlear electrode at 8 weeks of age, and received chronic ICES for up to 9 months before cortical recording. Cats in the other group were implanted immediately prior to cortical recording as adults. In all cats in both groups, multi-neuron responses throughout the rostro-caudal extent of AI had low characteristic frequencies (CFs), in the frequency range of the residual hearing, and high-thresholds. Threshold and minimum latency at CF did not differ between the groups, but in the chronic ICES animals there was a higher proportion of electrically but not acoustically excited recording sites. Electrical response thresholds were higher and latencies shorter in the chronically stimulated animals. Thus, chronic implantation and ICES affected the extent of AI that could be activated by acoustic stimuli and resulted in changes in electrical response characteristics.
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Affiliation(s)
- James B Fallon
- The Bionic Ear Institute, Melbourne, Vic. 3002, Australia.
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23
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Abstract
Congenital auditory deprivation leads to deficits in the auditory cortex. The present review focuses on central aspects of auditory deprivation: development, plasticity, corticocortical interactions, and cross-modal reorganization. We compile imaging data from human subjects, electroencephalographic data from cochlear implanted children, and animal research on congenital deafness. Behavioral, electroencephalographic, and imaging data in humans correspond well to data behavioral and neurophysiological data obtained from congenitally deaf cats. The available data indicate that auditory deprivation leads to 'decoupling' of the primary auditory cortex from cognitive modulation of higher-order auditory areas. Higher-order auditory areas undergo a strong cross-modal reorganization and take-over new functions. Due to these and other deficits of intrinsic microcircuitry, the cortical column can not integrate bottom-up and top-down influences in deaf auditory cortex. In the ultimate consequence perceptual learning is compromised, resulting in sensitive periods.
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Affiliation(s)
- Andrej Kral
- Laboratory of Auditory Neuroscience, Department of Neurophysiology and Pathophysiology, University Clinics Hamburg-Eppendorf, University of Hamburg, Germany.
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24
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Dinces E, Chobot-Rhodd J, Sussman E. Behavioral and electrophysiological measures of auditory change detection in children following late cochlear implantation: a preliminary study. Int J Pediatr Otorhinolaryngol 2009; 73:843-51. [PMID: 19380166 PMCID: PMC2688904 DOI: 10.1016/j.ijporl.2009.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 02/25/2009] [Accepted: 03/02/2009] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The purpose of the current study was to longitudinally assess the development of automatic sound feature discrimination and compare it to behavioral discrimination in late-implanted cochlear implant users. METHODS Scalp-recorded auditory evoked potentials (AEPs) and behavioral discrimination of frequency, duration and intensity differences within an oddball paradigm using complex stimuli were recorded in three late-implanted cochlear implant subjects beginning on turn-on day. RESULTS Variable results were obtained in behavioral and AEPs that were consistent with the amount of pre-implant auditory experience each subject had. The best user showed rapid development of neurophysiologic indices of change detection along with improvement in behavioral and real-world auditory skills. In contrast, there were no recordable AEPs in the poorer CI user and there was little change in behavioral outcomes. CONCLUSION There is evidence of utilization of usual auditory processing pathways in the AEPs of some children who receive cochlear implants late in their childhood. Some plasticity in the auditory cortical pathways may be present despite prolonged auditory deprivation in school-aged children who are late-implanted cochlear implant recipients.
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Affiliation(s)
- Elizabeth Dinces
- Department of Otorhinolaryngology - Head and Neck Surgery, Albert Einstein College of Medicine, 3400 Bainbridge Ave, Bronx, NY 10467, USA.
| | - Janie Chobot-Rhodd
- Department of Pediatrics, Children’s Evaluation and Rehabilitation Center, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY 10461
| | - Elyse Sussman
- Department of Otorhinolaryngology - Head and Neck Surgery, Albert Einstein College of Medicine, 3400 Bainbridge Ave, Bronx NY 10467, Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx NY 10461
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Moffat G, Adjout K, Gallego S, Thai-Van H, Collet L, Noreña AJ. Effects of hearing aid fitting on the perceptual characteristics of tinnitus. Hear Res 2009; 254:82-91. [PMID: 19409969 DOI: 10.1016/j.heares.2009.04.016] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 04/18/2009] [Accepted: 04/20/2009] [Indexed: 11/27/2022]
Abstract
Restoration of auditory input through the use of hearing aids has been proposed as a potentially important means of altering tinnitus among those tinnitus sufferers who experience significant sensorineural hearing loss. In animal models of neural plasticity induced by noise trauma, high-frequency stimulation in deafferented regions of the auditory spectrum has been shown to modulate cortical reorganization after hearing loss, a result which suggests that the neural basis of tinnitus is subject to interference by acoustic stimulation. This study drew on deafferentation models to investigate the effect of hearing aids on the psychoacoustic properties of the tinnitus sensation, using both conventional amplification and high-bandwidth amplification regimes. The tinnitus percept was affected only weakly in the conventional amplification group, and was not at all affected in the high-bandwidth group. The changes observed under conventional, low-to-medium frequency amplification may indicate that the perceptual characteristics of tinnitus depend on the pattern of sensory inputs - notably a contrast in activity between adjacent central auditory regions of more and less afferent activity - while the absence of modifications in the high-bandwidth amplification group suggests limit on the tractability of the tinnitus percept. This limit to the malleability of the tinnitus percept may arise from either the extent of hearing deficits or the duration and robustness of the neuroplastic changes that originally give rise to tinnitus.
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Affiliation(s)
- G Moffat
- Laboratoire de neurobiologie intégrative et adaptative, UMR CNRS 6149, 3 Place Victor Hugo, Marseille, F-13331 Cedex 03, France
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26
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Takesian AE, Kotak VC, Sanes DH. Developmental hearing loss disrupts synaptic inhibition: implications for auditory processing. FUTURE NEUROLOGY 2009; 4:331-349. [PMID: 20161214 PMCID: PMC2716048 DOI: 10.2217/fnl.09.5] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hearing loss during development leads to central deficits that persist even after the restoration of peripheral function. One key class of deficits is due to changes in central inhibitory synapses, which play a fundamental role in all aspects of auditory processing. This review focuses on the anatomical and physiological alterations of inhibitory connections at several regions within the central auditory pathway following hearing loss. Such aberrant inhibitory synaptic function may be linked to deficits in encoding binaural and spectral cues. Understanding the cellular changes that occur at inhibitory synapses following hearing loss may provide specific loci that can be targeted to improve function.
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Affiliation(s)
- Anne E Takesian
- Center for Neural Science, New York, University, NY 10003, USA, Tel.: +1 212 998 3914, Fax: +1 212 995 4011,
| | - Vibhakar C Kotak
- Center for Neural Science, New York, University, NY 10003, USA, Tel.: +1 212 998 3916, Fax: +1 212 995 4011,
| | - Dan H Sanes
- Center for Neural Science & Department of Biology, New York, University, NY 10003, USA, Tel.: +1 212 998 3924, Fax: +1 212 998 4348,
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27
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Chadha NK, Gordon KA, James AL, Papsin BC. Tinnitus is prevalent in children with cochlear implants. Int J Pediatr Otorhinolaryngol 2009; 73:671-5. [PMID: 19185357 DOI: 10.1016/j.ijporl.2008.12.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 12/22/2008] [Accepted: 12/23/2008] [Indexed: 01/17/2023]
Abstract
OBJECTIVES To explore the prevalence and the perceived impact of tinnitus in children using cochlear implants. METHOD Cross-sectional study of implanted children attending a cochlear implant family event organized annually by our academic tertiary pediatric care center. Children were interviewed together with their parents, using open-questioning and structured interview qualitative methodologies. The main outcome measures were the prevalence of tinnitus and any impact of these symptoms. RESULTS 40 children (age range: 3-15, mean: 7 years) and their families were interviewed. These included unilateral implantees (n=21), and bilateral implantees (n=19) whose two procedures were simultaneous (n=6), within 6-12 months (n=3), or >2 years apart (n=10). Tinnitus was reported by 38% (n=15). Tinnitus occurred most commonly in the implanted ear, when the implants were not in use (e.g. in bed at night). The children were generally untroubled by the tinnitus, although two reported difficulty sleeping. Tinnitus was most frequent in children aged 6-8 years (8/17, 47%), and in bilateral implantees with an inter-procedure delay of at least 2 years (6/10, 60%). Tinnitus was least reported in those implanted bilaterally simultaneously (1/6, 17%), and in those 5 years old or younger (3/11, 27%). No obvious relationship was identified between the prevalence of tinnitus and the etiology of deafness, age of implantation, or time elapsed since implantation. CONCLUSIONS To our knowledge this is the first study to report the widespread prevalence of tinnitus in implanted children. Further work, particularly examining the effect of inter-implant delay on tinnitus in bilateral implantees, may contribute to our understanding of the neuronal plasticity after implantation.
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Affiliation(s)
- Neil K Chadha
- Department of Otolaryngology, The Hospital for Sick Children, Toronto, Ontario, Canada.
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28
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Brown TA, Harrison RV. Responses of neurons in chinchilla auditory cortex to frequency-modulated tones. J Neurophysiol 2009; 101:2017-29. [PMID: 19211659 DOI: 10.1152/jn.90931.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Frequency-modulated (FM) stimuli have been used to explore the behavior of neurons in the auditory cortex of several animal models; however, the properties of FM-sensitive auditory cortical neurons in the chinchilla are still unknown. Single-unit responses to FM stimulation were obtained from the auditory cortex of anesthetized adult chinchillas (Chinchilla laniger). Upward and downward linear FM sweeps spanning frequencies from 0.1 to 20 kHz were presented at speeds of 0.05 to 0.82 kHz/ms. Results indicated that >90% of sampled neurons were responsive to FM sweeps. The population preference was for upward FM sweeps and for medium to fast speeds (> or =0.3 kHz/ms). Few units (3%) were selective for downward FM sweeps, whereas <22% of units preferred slow speeds (< or =0.1 kHz/ms). Velocity preference and direction sensitivity were positively correlated for upward sweeps only (r = 0.40, P = 0.0021, t-test). Three types of firing rate patterns were observed in the FM response peristimulus time histograms: a single peak at sweep onset/offset ("onset") and a single peak ("late") or multiple peaks ("burst") during the sweep. "Late" units expressed the highest mean values for direction sensitivity and speed selectivity; "onset" units were selective only for direction and "burst" units were not selective for either direction or speed. The robust responsiveness of these neurons to FM sweeps suggests a functional role for FM detection such as the identification of FM sweeps present in vocalizations of other organisms within the chinchilla's natural environment.
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Affiliation(s)
- Trecia A Brown
- The Hospital for Sick Children, 555 University Avenue, Room 3005, McMaster Building, Toronto, Ontario, Canada M5G 1X8.
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29
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Snyder RL, Bonham BH, Sinex DG. Acute changes in frequency responses of inferior colliculus central nucleus (ICC) neurons following progressively enlarged restricted spiral ganglion lesions. Hear Res 2008; 246:59-78. [PMID: 18938235 PMCID: PMC2630712 DOI: 10.1016/j.heares.2008.09.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 09/24/2008] [Accepted: 09/24/2008] [Indexed: 11/30/2022]
Abstract
Immediate effects of sequential and progressively enlarged spiral ganglion (SG) lesions were recorded from cochleas and inferior colliculi. Small SG-lesions produced modest elevations in cochlear tone-evoked compound action potential (CAP) thresholds across narrow frequency ranges; progressively enlarged lesions produced progressively higher CAP-threshold elevations across progressively wider frequency ranges. No comparable changes in distortion product otoacoustic emissions (DPOAEs) amplitudes were observed consistent with silencing of auditory nerve sectors without affecting organ of Corti function. Frequency response areas (FRAs) of inferior colliculus (IC) neurons were recorded before and immediately after SG-lesions using multi-site silicon arrays fixed in place with recording sites arrayed along IC frequency gradient. Individual post-lesion FRAs exhibited progressively elevated response thresholds and diminished response amplitudes at lesion frequencies, whereas responses at non-lesion frequencies were either unchanged or enhanced. Characteristic frequencies were shifted and silent areas were introduced within these FRAs. Sequentially larger lesions produced sequentially larger shifts in CF and/or enlarged silent areas within affected FRAs, producing immediate changes in IC frequency organization. These results contrast with those from the auditory nerve, extend previous reports of experience-induced plasticity in the auditory CNS, and support results indicating afferent convergence onto ICC neurons across broad frequency bands.
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Affiliation(s)
- Russell L Snyder
- Department of Otolaryngology, University of California, San Francisco, CA 94143-0526, United States.
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Residual inhibition functions overlap tinnitus spectra and the region of auditory threshold shift. J Assoc Res Otolaryngol 2008; 9:417-35. [PMID: 18712566 DOI: 10.1007/s10162-008-0136-9] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Accepted: 08/01/2008] [Indexed: 10/21/2022] Open
Abstract
Animals exposed to noise trauma show augmented synchronous neural activity in tonotopically reorganized primary auditory cortex consequent on hearing loss. Diminished intracortical inhibition in the reorganized region appears to enable synchronous network activity that develops when deafferented neurons begin to respond to input via their lateral connections. In humans with tinnitus accompanied by hearing loss, this process may generate a phantom sound that is perceived in accordance with the location of the affected neurons in the cortical place map. The neural synchrony hypothesis predicts that tinnitus spectra, and heretofore unmeasured "residual inhibition functions" that relate residual tinnitus suppression to the center frequency of masking sounds, should cover the region of hearing loss in the audiogram. We confirmed these predictions in two independent cohorts totaling 90 tinnitus subjects, using computer-based tools designed to assess the psychoacoustic properties of tinnitus. Tinnitus spectra and residual inhibition functions for depth and duration increased with the amount of threshold shift over the region of hearing impairment. Residual inhibition depth was shallower when the masking sounds that were used to induce residual inhibition showed decreased correspondence with the frequency spectrum and bandwidth of the tinnitus. These findings suggest that tinnitus and its suppression in residual inhibition depend on processes that span the region of hearing impairment and not on mechanisms that enhance cortical representations for sound frequencies at the audiometric edge. Hearing thresholds measured in age-matched control subjects without tinnitus implicated hearing loss as a factor in tinnitus, although elevated thresholds alone were not sufficient to cause tinnitus.
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31
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Moore BCJ, Vinay SN. Enhanced discrimination of low-frequency sounds for subjects with high-frequency dead regions. Brain 2008; 132:524-36. [DOI: 10.1093/brain/awn308] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
Guided by findings from neural imaging and population responses in humans, where tinnitus is well characterized, several morphological and physiological substrates of tinnitus in animal studies are reviewed. These include changes in ion channels, receptor systems, single unit firing rate, and population responses. Most findings in humans can be interpreted as resulting from increased neural synchrony.
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Affiliation(s)
- Jos J Eggermont
- Department of Physiology & Biophysics, University of Calgary, Calgary, AB, Canada.
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33
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Eggermont JJ. Correlated neural activity as the driving force for functional changes in auditory cortex. Hear Res 2007; 229:69-80. [PMID: 17296278 DOI: 10.1016/j.heares.2007.01.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Revised: 10/31/2006] [Accepted: 01/03/2007] [Indexed: 10/23/2022]
Abstract
The functional role of neural synchrony is reflected in cortical tonotopic map reorganization and in the emergence of pathological phenomena such as tinnitus. First of all experimenter-centered and subject-centered views of neural activity will be contrasted; this argues against the use of stimulus-correction procedures and favors the use of a correction procedure based on neural activity without reference to stimulus timing. Within a cortical column neurons fired synchronously with on average about 6% of their spikes in a 1 ms bin and occasionally showing 30% or more of such coincident spikes. For electrode separations exceeding 200 microm the average peak correlation strength only occasionally reached 3%. The experimental evidence for coincidence of neural activity, neural correlation and neural synchrony shows that horizontal fibers activity can induce strong neural correlations. Cortico-cortical connections for a large part connect cell groups with characteristic frequencies differing by more than one octave. Such neurons have generally non-overlapping receptive fields but still can have sizeable peak cross-correlations. Correlated neural activity and heterotopic neural interconnections are presented as the substrates for cortical reorganization; increased neural synchrony and tonotopic map reorganization go hand in hand. This links cortical reorganization with hypersynchrony that can be considered as an important driving force underlying tinnitus.
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Affiliation(s)
- Jos J Eggermont
- Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada.
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34
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Roberts LE, Moffat G, Bosnyak DJ. Residual inhibition functions in relation to tinnitus spectra and auditory threshold shift. Acta Otolaryngol 2006:27-33. [PMID: 17114139 DOI: 10.1080/03655230600895358] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
CONCLUSIONS Psychoacoustic functions relating the depth and duration of tinnitus suppression ('residual inhibition') to the center frequency of band-passed noise masking sounds appear to span the region of hearing loss, as do psychoacoustic measurements of the tinnitus spectrum. The results (1) suggest that cortical map reorganization induced by hearing loss is not the principal source of the tinnitus sensation and (2) provide a necessary baseline for optimizing residual inhibition in individual cases. OBJECTIVE To measure residual inhibition functions and tinnitus spectra using sounds spanning the region of hearing loss. MATERIALS AND METHODS Three subject-driven, computer-based tools were developed and applied to measure psychoacoustic properties of tinnitus and residual inhibition in 32 subjects with chronic tonal, ringing, or hissing tinnitus. Residual inhibition functions were measured with band-passed noise sounds varying in center frequency up to 12.0 kHz. RESULTS The depth and duration of residual inhibition increased with the center frequency of the band-passed noise stimuli. Near-elimination of tinnitus for up to 45 s was reported by 8/24 (33%) subjects at center frequencies above 3 kHz (these cases distributed across tinnitus types). Tinnitus spectra covered the region of hearing loss with no preponderance of frequencies near the audiometric edge of normal hearing.
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Affiliation(s)
- Larry E Roberts
- Department of Psychology, Neuroscience, and Behavior, McMaster University, Hamilton, Ontario, Canada.
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35
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Firszt JB, Ulmer JL, Gaggl W. Differential representation of speech sounds in the human cerebral hemispheres. THE ANATOMICAL RECORD. PART A, DISCOVERIES IN MOLECULAR, CELLULAR, AND EVOLUTIONARY BIOLOGY 2006; 288:345-57. [PMID: 16550560 PMCID: PMC3780356 DOI: 10.1002/ar.a.20295] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Various methods in auditory neuroscience have been used to gain knowledge about the structure and function of the human auditory cortical system. Regardless of method, hemispheric differences are evident in the normal processing of speech sounds. This review article, augmented by the authors' own work, provides evidence that asymmetries exist in both cortical and subcortical structures of the human auditory system. Asymmetries are affected by stimulus type, for example, hemispheric activation patterns have been shown to change from right to left cortex as stimuli change from speech to nonspeech. In addition, the presence of noise has differential effects on the contribution of the two hemispheres. Modifications of typical asymmetric cortical patterns occur when pathology is present, as in hearing loss or tinnitus. We show that in response to speech sounds, individuals with unilateral hearing loss lose the normal asymmetric pattern due to both a decrease in contralateral hemispheric activity and an increase in the ipsilateral hemisphere. These studies demonstrate the utility of modern neuroimaging techniques in functional investigations of the human auditory system. Neuroimaging techniques may provide additional insight as to how the cortical auditory pathways change with experience, including sound deprivation (e.g., hearing loss) and sound experience (e.g., training). Such investigations may explain why some populations appear to be more vulnerable to changes in hemispheric symmetry such as children with learning problems and the elderly.
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Affiliation(s)
- Jill B Firszt
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Hunt DL, Yamoah EN, Krubitzer L. Multisensory plasticity in congenitally deaf mice: how are cortical areas functionally specified? Neuroscience 2006; 139:1507-24. [PMID: 16529873 DOI: 10.1016/j.neuroscience.2006.01.023] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Revised: 01/12/2006] [Accepted: 01/21/2006] [Indexed: 11/17/2022]
Abstract
The neocortex of congenitally deaf mice was examined using electrophysiological recording techniques combined with cortical myeloarchitecture. Our results indicate that relative activity patterns across sensory systems during development contribute to modality assignment of cortical fields as well as the size of cortical fields. In congenitally deaf mice, "auditory cortex" contained neurons that responded to somatosensory, visual, or both somatosensory and visual stimulation; the primary visual area contained a larger proportion of neurons that responded to somatosensory stimulation than in normal animals, and the primary visual area had significantly increased in size. Thus, cortical architecture and functional specification were de-correlated. When results are considered in the light of molecular studies and studies in which peripheral activity is altered in development, it becomes clear that similar types of changes to the neocortex, such as alterations in cortical field size, can be achieved in more than one way in the developing and evolving neocortex.
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Affiliation(s)
- D L Hunt
- Center for Neuroscience, University of California, Davis, Center for Neuroscience, 95616, USA
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Gordon KA, Papsin BC, Harrison RV. Effects of cochlear implant use on the electrically evoked middle latency response in children. Hear Res 2006; 204:78-89. [PMID: 15925193 DOI: 10.1016/j.heares.2005.01.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Accepted: 01/06/2005] [Indexed: 11/24/2022]
Abstract
The electrically evoked middle latency response (eMLR) reflects central auditory activity in cochlear implant users. This response was recorded repeatedly in 50 children over the first year of cochlear implant use and in 31 children with 5.3+/-2.9 years of implant experience. The eMLR was rarely detected at the time of implantation in anaesthetized or sedated children and was detected in only 35% of awake children at initial device stimulation. The detectability of the eMLR increased over the first year of implant use becoming 100% detectable in children after at least one year. Acutely evoked responses were more likely to be present in older children despite longer periods of auditory deprivation. Within six months of implant use, most children had detectable eMLRs. At early stages of device use, eMLR amplitudes were lower in children implanted below the age of 5 years compared to children implanted at older ages; amplitudes increased over time in both groups. Latencies after six months of implant use were prolonged in the younger group and decreased with implant use. EMLR changes with chronic cochlear implant use suggest an activity-dependent plasticity of the central auditory system. Results suggest that the pattern of electrically evoked activity and development in the auditory thalamocortical pathways will be dependent upon the duration of auditory deprivation occurring in early childhood.
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Affiliation(s)
- Karen A Gordon
- Department of Otolaryngology, The Hospital for Sick Children, University of Toronto, Toronto, Ont., Canada M5G 1X8.
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Strata F, deIpolyi AR, Bonham BH, Chang EF, Liu RC, Nakahara H, Merzenich MM. Perinatal anoxia degrades auditory system function in rats. Proc Natl Acad Sci U S A 2005; 102:19156-61. [PMID: 16365292 PMCID: PMC1323198 DOI: 10.1073/pnas.0509520102] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Little is known about the neural bases of the reduced auditory and cortical processing speeds that have been recorded in language-impaired, autistic, schizophrenic, and other disabled human populations. Although there is strong evidence for genetic contributions to etiologies, epigenetic factors such as perinatal anoxia (PA) have been argued to be contributors, or causal, in a significant proportion of cases. In this article, we explored the consequences of PA on this elementary aspect of auditory behavior and on auditory system function in rats that were briefly perinatally anoxic. PA rats had increased acoustic thresholds and reduced processing efficiencies recorded in an auditory behavioral task. These rats had modestly increased interpeak intervals in their auditory brainstem responses, and substantially longer latencies in poststimulus time histogram responses recorded in the primary auditory cortex. The latter were associated with degraded primary auditory cortex receptive fields and a disrupted tonotopy. These processing deficits are consistent with the parallel behavioral and physiological deficits recorded in children and adults with a history of language-learning impairment and autism.
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Affiliation(s)
- F Strata
- W. M. Keck Center for Integrative Neuroscience, Coleman Laboratory and Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, CA 94143-0732, USA.
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Kelly AS, Purdy SC, Thorne PR. Electrophysiological and speech perception measures of auditory processing in experienced adult cochlear implant users. Clin Neurophysiol 2005; 116:1235-46. [PMID: 15978485 DOI: 10.1016/j.clinph.2005.02.011] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2003] [Revised: 01/31/2005] [Accepted: 02/14/2005] [Indexed: 11/20/2022]
Abstract
OBJECTIVE This study determined the relationship between auditory evoked potential measures and speech perception in experienced adult cochlear implant (CI) users and compared the CI evoked potential results to those of a group of age- and sex-matched control subjects. METHODS CI subjects all used the Nucleus CI-22 implant. Middle latency response (MLR), obligatory cortical potentials (CAEP), mismatch negativity (MMN) and P3a auditory evoked potentials were recorded. Speech perception was evaluated using word and sentence tests. RESULTS Duration of deafness correlated with speech scores with poor scores reflecting greater years of deafness. Na amplitude correlated negatively with duration of deafness, with small amplitudes reflecting greater duration of deafness. Overall, N1 amplitude was smaller in CI than control subjects. Earlier P2 latencies were associated with shorter durations of deafness and higher speech scores. In general, MMN was absent or degraded in CI subjects with poor speech scores. CONCLUSIONS Auditory evoked potentials are related to speech perception ability and provide objective evidence of central auditory processing differences across experienced CI users. SIGNIFICANCE Since auditory evoked potentials relate to CI performance, they may be a useful tool for objectively evaluating the efficacy of speech processing strategies and/or auditory training approaches in both adults and children with cochlear implants.
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Affiliation(s)
- Andrea S Kelly
- Discipline of Audiology, The University of Auckland, Private Bag 92-019, Auckland, New Zealand.
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Baguley DM, Jones S, Wilkins I, Axon PR, Moffat DA. The Inhibitory Effect of Intravenous Lidocaine Infusion on Tinnitus after Translabyrinthine Removal of Vestibular Schwannoma: A Double-Blind, Placebo-Controlled, Crossover Study. Otol Neurotol 2005; 26:169-76. [PMID: 15793400 DOI: 10.1097/00129492-200503000-00007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Intravenous infusion of lidocaine has previously been demonstrated to have a transient inhibitory effect on tinnitus in 60% of individuals. The site of action has variously been proposed as the cochlea, the cochlea nerve, and the central auditory pathways. To determine whether a central site of action exists, this study investigated the effect of intravenous infusion of lidocaine in individuals with tinnitus who had previously undergone translabyrinthine excision of a vestibular schwannoma, which involves division of the cochlear nerve. STUDY DESIGN Double-blind, placebo-controlled, crossover study. SETTING University hospital. PATIENTS Patients who had undergone translabyrinthine removal of a unilateral, sporadic, and histologically proven vestibular schwannoma in the last decade and who had reported postoperative tinnitus at follow-up were identified from a departmental database. Sixteen patients participated (12 men and 4 women). The mean age (+/- standard deviation) of the patients was 58 +/- 8.6 years, and the meantime since operation was 24.3 +/- 7.3 months. INTERVENTION Solutions of 2% lidocaine hydrochloride and sodium chloride 0.9% were prepared in identical randomized vials. The volume required for 1.5 ml/kg body weight lidocaine was calculated, and this volume was given over 5 minutes for either vial. Blood pressure, pulse oximetry, and cardiac monitoring were set up and performed throughout the infusions. All investigators were blinded. OUTCOME MEASURES Patient-completed visual analogue scale measures of tinnitus intensity, pitch, and distress, performed before infusion, 5 minutes after infusion onset, and 20 minutes after infusion onset. RESULTS A significant difference (Wilcoxon signed-rank test, p < 0.05) between placebo and lidocaine infusion conditions was demonstrated for change in visual analogue scale estimates (preinfusion versus 5 min postinfusion) of tinnitus loudness (p = 0.036), pitch (p = 0.026), and distress (p = 0.04). No significant difference between placebo and lidocaine infusion conditions was demonstrated for change in visual analogue scale estimates (preinfusion versus 20 min postinfusion) of tinnitus loudness (p = 0.066), pitch (p = 0.173), and distress (p = 0.058). The indication is of a short-lasting inhibitory effect on tinnitus of lidocaine infusion compared with saline placebo in patients who have undergone translabyrinthine excision of a vestibular schwannoma. CONCLUSION Intravenous infusion of lidocaine has a statistically significant inhibitory effect on tinnitus in patients who have previously undergone translabyrinthine removal of a vestibular schwannoma. The site of action of lidocaine in this instance must be in the central auditory pathway, as the cochlear and vestibular nerves are sectioned during surgery, and this finding has important implications for the task of identifying other agents that will have a similar tinnitus-inhibiting effect.
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Affiliation(s)
- David M Baguley
- Department of Neuro-Otology, Addenbrooke's Hospital, Cambridge, UK.
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Harrison RV, Gordon KA, Mount RJ. Is there a critical period for cochlear implantation in congenitally deaf children? Analyses of hearing and speech perception performance after implantation. Dev Psychobiol 2005; 46:252-61. [PMID: 15772969 DOI: 10.1002/dev.20052] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A range of basic and applied studies have demonstrated that during the development of the auditory system, early experimental manipulations or clinical interventions are generally more effective than those made later. We present a short review of these studies. We investigated this age-related plasticity in relation to the timing of cochlear implantation in deaf-from-birth children. Cochlear implantation is a standard intervention for providing hearing in children with severe to profound deafness. An important practical question is whether there is a critical period or cutoff age of implantation after which hearing outcomes are significantly reduced. In this article, we present data from prelingually deaf children (mostly congenitally deaf) implanted at ages ranging from 1 to 15 years. Each child was tested with auditory and speech understanding tests before implantation, and at regular intervals up to 8 years postimplantation. We measured the improvement in performance of speech understanding tests in younger implanted children and compared it with the results of those implanted at a later age. We also used a binary partitioning algorithm to divide the data systematically at all ages at implant to determine the optimum split, i.e., to determine the age at implant which best separates performance of early implanted versus later implanted children. We observed distinct age-of-implant cutoffs, and will discuss whether these really represent critical periods during development.
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Affiliation(s)
- Robert V Harrison
- Auditory Science Laboratory, Department of Otolaryngology, Division of Brain and Behaviour, The Hospital for Sick Children, Toronto M5G 1X8, Canada.
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Irvine DRF, Wright BA. Plasticity of Spectral Processing. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 70:435-72. [PMID: 16472642 DOI: 10.1016/s0074-7742(05)70013-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Dexter R F Irvine
- Department of Psychology, Faculty of Medicine, Nursing, and Health Sciences, Monash University, Victoria 3800, Australia
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Hartmann R, Kral A. Central Responses to Electrical Stimulation. COCHLEAR IMPLANTS: AUDITORY PROSTHESES AND ELECTRIC HEARING 2004. [DOI: 10.1007/978-0-387-22585-2_6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Ison JR, Allen PD. Low-frequency tone pips elicit exaggerated startle reflexes in C57BL/6J mice with hearing loss. J Assoc Res Otolaryngol 2003; 4:495-504. [PMID: 12784135 PMCID: PMC3202743 DOI: 10.1007/s10162-002-3046-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2002] [Accepted: 04/01/2003] [Indexed: 11/28/2022] Open
Abstract
The strength of the acoustic startle reflex (ASR) as a function of age was studied in adult C57BL/6J and CBA/CaJ mice, because altered ASR levels are a potential behavioral consequence of the neural reorganization that accompanies the early-onset hearing loss of the C57BL, in contrast to the normal-hearing CBA. For C57BL mice at 14-36 weeks of age, compared with 7-week-old mice, high-frequency thresholds measured with the auditory brainstem response (ABR) were less sensitive by about 25-30 dB while the hearing loss at low frequencies was 10-15 dB, but by 60 weeks losses of 45-50 dB were present across the entire spectrum. Their ASR amplitudes for 16 kHz tone pips were highest at 7 weeks and then declined with age, but, for 4 kHz tones the ASR increased in strength at 18 weeks and beyond to levels above that of the younger mice. This hyperreactivity persisted even in 60-week-old mice. The ASR for 16 kHz stimuli was positively correlated with hearing sensitivity, but the ASR for 4 kHz stimuli was positively correlated with hearing loss for mice that were 18-36 weeks of age. Furthermore, ASR amplitudes for 4 kHz stimuli were positively correlated with the 16 kHz ASR in young C57BL mice but negatively correlated in older mice. There were no similar ASR or ABR changes in adult CBA mice through 19 weeks of age. Correlations between ASR and ABR scores were always weakly positive, and correlations between 4 kHz and 16 kHz ASR amplitudes were always strongly positive. The ASR data in older C57BL mice with hearing loss are consistent with reports describing their increased neural representation of low-frequency sounds and reinforce the value of this strain for studying the functional consequences that accompany age-related cochlear degeneration.
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Affiliation(s)
- James R Ison
- Department of Brain and Cognitive Sciences, Meliora Hall, University of Rochester, Rochester, NY 14627, USA.
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45
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Irvine DRF, Rajan R, Smith S. Effects of restricted cochlear lesions in adult cats on the frequency organization of the inferior colliculus. J Comp Neurol 2003; 467:354-74. [PMID: 14608599 DOI: 10.1002/cne.10921] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Restricted cochlear lesions in adult animals result in plastic changes in the representation of the lesioned cochlea, and thus in the frequency map, in the contralateral auditory cortex and thalamus. To examine the contribution of subthalamic changes to this reorganization, the effects of unilateral mechanical cochlear lesions on the frequency organization of the central nucleus of the inferior colliculus (ICC) were examined in adult cats. Lesions typically resulted in a broad high-frequency hearing loss extending from a frequency in the range 15-22 kHz. After recovery periods of 2.5-18 months, the frequency organization of ICC contralateral to the lesioned cochlea was determined separately for the onset and late components of multiunit responses to tone-burst stimuli. For the late response component in all but one penetration through the ICC, and for the onset response component in more than half of the penetrations, changes in frequency organization in the lesion projection zone were explicable as the residue of prelesion responses. In half of the penetrations exhibiting nonresidue type changes in onset-response frequency organization, the changes appeared to reflect the unmasking of normally inhibited inputs. In the other half it was unclear whether the changes reflected unmasking or a dynamic process of reorganization. Thus, most of the observed changes were explicable as passive consequences of the lesion, and there was limited evidence for plasticity in the ICC. The implications of the data with respect to the primary locus of the changes and to the manner in which they contribute to thalamocortical reorganization are considered.
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Affiliation(s)
- Dexter R F Irvine
- Department of Psychology, Faculty of Medicine, Nursing and Health Science, Monash University, Victoria 3800, Australia.
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46
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Bonham BH, Cheung SW, Godey B, Schreiner CE. Spatial organization of frequency response areas and rate/level functions in the developing AI. J Neurophysiol 2003; 91:841-54. [PMID: 14534283 DOI: 10.1152/jn.00017.2003] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The current study was conducted to extend our understanding of changes in spatial organization and response properties of cortical neurons in the developing mammalian forebrain. Extracellular multiunit responses to tones were recorded from a dense array of penetrations covering entire isofrequency contours in the primary auditory cortex (AI) of pentobarbital anesthetized kittens. Ages ranged from postnatal day 14 (P14), shortly after acquisition of normal auditory response thresholds, through postnatal day 111 (P111), when the kittens were largely mature. Spatial organization of the AI was tonotopically ordered by P14. The tonotopic gradient decreased with chronological maturation. At P14 the gradient was about 3.5 kHz/mm. By P111 it had declined to about 2.5 kHz/mm, so that the cortical region encompassing a fixed 3- to 15-kHz frequency range enlarged along its posterior-anterior dimension. Response properties of developing AI neurons changed in both frequency selectivity and intensity selectivity. The mean frequency tuning bandwidth increased with age. Initially, tuning bandwidths were narrow throughout the entire AI. With progressive maturation, broader bandwidths were observed in areas dorsal and ventral to a central region in which neurons remained narrowly tuned. The resulting spatial organization of tuning bandwidth was similar to that reported in adult cats. The majority of recording sites manifested nonmonotonic rate/level functions at all ages. However, the proportion of sites with monotonic rate/level functions increased with age. No spatial organization of rate/level functions (monotonic and nonmonotonic) was observed through P111. The relatively late development of bandwidth tuning in the AI compared with the early presence of tonotopic organization suggests that different developmental processes are responsible for structuring these two dimensions of acoustic selectivity.
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Affiliation(s)
- Ben H Bonham
- Department of Otolaryngology-Head and Neck Surgery, and W. M. Keck Center for Integrative Neuroscience, University of California, San Francisco, California 94143, USA.
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Yan J. Canadian Association of Neuroscience Review: development and plasticity of the auditory cortex. Can J Neurol Sci 2003; 30:189-200. [PMID: 12945940 DOI: 10.1017/s0317167100002572] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The functions of the cerebral cortex are predominantly established during the critical period of development. One obvious developmental feature is its division into different functional areas that systematically represent different environmental information. This is the result of interactions between intrinsic (genetic) factors and extrinsic (environmental) factors. Following this critical period, the cerebral cortex attains its adult form but it will continue to adapt to environmental changes. Thus, the cerebral cortex is constantly adapting to the environment (plasticity) from its embryonic stages to the last minute of life. This review details important factors that contribute to the development and plasticity of the auditory cortex. The instructive role of thalamocortical innervation, the regulatory role of cholinergic projection of the basal forebrain and the potential role of the corticofugal modulation are presented.
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Affiliation(s)
- Jun Yan
- Department of Physiology and Biophysics, Neuroscience Research Group, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Khosla D, Ponton CW, Eggermont JJ, Kwong B, Dort M, Vasama JP. Differential ear effects of profound unilateral deafness on the adult human central auditory system. J Assoc Res Otolaryngol 2003; 4:235-49. [PMID: 12943375 PMCID: PMC3202721 DOI: 10.1007/s10162-002-3014-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2002] [Accepted: 08/12/2002] [Indexed: 10/26/2022] Open
Abstract
This study investigates the effects of profound acquired unilateral deafness on the adult human central auditory system by analyzing long-latency auditory evoked potentials (AEPs) with dipole source modeling methods. AEPs, elicited by clicks presented to the intact ear in 19 adult subjects with profound unilateral deafness and monaurally to each ear in eight adult normal-hearing controls, were recorded with a 31-channel system. The responses in the 70-210 ms time window, encompassing the N1b/P2 and Ta/Tb components of the AEPs, were modeled by a vertically and a laterally oriented dipole source in each hemisphere. Peak latencies and amplitudes of the major components of the dipole waveforms were measured in the hemispheres ipsilateral and contralateral to the stimulated ear. The normal-hearing subjects showed significant ipsilateral-contralateral latency and amplitude differences, with contralateral source activities that were typically larger and peaked earlier than the ipsilateral activities. In addition, the ipsilateral-contralateral amplitude differences from monaural presentation were similar for left and for right ear stimulation. For unilaterally deaf subjects, the previously reported reduction in ipsilateral-contralateral amplitude differences based on scalp waveforms was also observed in the dipole source waveforms. However, analysis of the source dipole activity demonstrated that the reduced inter-hemispheric amplitude differences were ear dependent. Specifically, these changes were found only in those subjects affected by profound left ear unilateral deafness.
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Affiliation(s)
| | - Curtis W. Ponton
- Neuroscan Labs, El Paso, TX 79912, USA
- Electrophysiology Department, House Ear Institute, Los Angeles, CA 90057, USA
| | - Jos J. Eggermont
- Department of Physiology and Biophysics and Department of Psychology, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Betty Kwong
- Electrophysiology Department, House Ear Institute, Los Angeles, CA 90057, USA
| | - Manuel Dort
- Electrophysiology Department, House Ear Institute, Los Angeles, CA 90057, USA
| | - Juha-Pekka Vasama
- Department of Otolaryngology, Helsinki University Central Hospital, Helsinki, Finland
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Abstract
It has been estimated that 15% of the population in the United States has tinnitus which lasts greater than 5 minutes. It has also been estimated that 155 million patients have previously sought care for this symptom. It is clear that the incidence of tinnitus increases with age and by 70 years of age at least 25 to 30% of patients experience tinnitus constantly. In addition, noise exposure and noise induced sensorineural hearing loss are most often seen in tinnitus patients. Furthermore, of interest to the physician, 94% of patients who have sought medical care have not been offered treatment for their tinnitus, rather they have been informed that nothing could be done for them, and they should "live with it".
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Affiliation(s)
- Mitchell K Schwaber
- Nashville Ear, Nose & Throat Clinic, 4230 Harding Road, Suite 803, Nashville, TN 37205, USA.
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50
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Syka J. Plastic changes in the central auditory system after hearing loss, restoration of function, and during learning. Physiol Rev 2002; 82:601-36. [PMID: 12087130 DOI: 10.1152/physrev.00002.2002] [Citation(s) in RCA: 271] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Traditionally the auditory system was considered a hard-wired sensory system; this view has been challenged in recent years in light of the plasticity of other sensory systems, particularly the visual and somatosensory systems. Practical experience in clinical audiology together with the use of prosthetic devices, such as cochlear implants, contributed significantly to the present view on the plasticity of the central auditory system, which was originally based on data obtained in animal experiments. The loss of auditory receptors, the hair cells, results in profound changes in the structure and function of the central auditory system, typically demonstrated by a reorganization of the projection maps in the auditory cortex. These plastic changes occur not only as a consequence of mechanical lesions of the cochlea or biochemical lesions of the hair cells by ototoxic drugs, but also as a consequence of the loss of hair cells in connection with aging or noise exposure. In light of the aging world population and the increasing amount of noise in the modern world, understanding the plasticity of the central auditory system has its practical consequences and urgency. In most of these situations, a common denominator of central plastic changes is a deterioration of inhibition in the subcortical auditory nuclei and the auditory cortex. In addition to the processes that are elicited by decreased or lost receptor function, the function of nerve cells in the adult central auditory system may dynamically change in the process of learning. A better understanding of the plastic changes in the central auditory system after sensory deafferentation, sensory stimulation, and learning may contribute significantly to improvement in the rehabilitation of damaged or lost auditory function and consequently to improved speech processing and production.
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Affiliation(s)
- Josef Syka
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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