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Abstract
Central deafness has been linked historically to bihemispheric involvement of the temporal lobe, with more recent findings suggesting that compromise of other cortical and subcortical structures can also result in this disorder. The present investigation extends our understanding of the potential anatomical correlates to central deafness by demonstrating that bilateral involvement of an auditory structure within the midbrain can additionally result in this condition. Our subject was a 21-year-old male with a subarachnoid bleed affecting both inferior colliculi. Significant auditory deficits were noted for the middle and late auditory evoked potentials, while electrophysiologic measures of the periphery indicated normal function. The patient was enrolled in a rehabilitation program for approximately 14 weeks. Although initially unresponsive to sounds, the patient regained most of his auditory abilities during the 10 months he was followed. This case documents the range of auditory deficits that may be associated with damage to the inferior colliculi, and it profiles a hierarchical recovery of auditory function consistent with test findings.
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MESH Headings
- Adult
- Audiometry, Pure-Tone
- Audiometry, Speech
- Brain Infarction/complications
- Brain Infarction/diagnosis
- Dichotic Listening Tests
- Evoked Potentials, Auditory, Brain Stem
- Hearing Loss, Central/etiology
- Hearing Loss, Central/rehabilitation
- Humans
- Inferior Colliculi/blood supply
- Inferior Colliculi/pathology
- Inferior Colliculi/physiopathology
- Magnetic Resonance Imaging
- Male
- Meningitis, Meningococcal/complications
- Meningitis, Meningococcal/diagnosis
- Meningitis, Meningococcal/microbiology
- Otoacoustic Emissions, Spontaneous
- Speech Perception
- Speech Therapy/methods
- Subarachnoid Hemorrhage/complications
- Subarachnoid Hemorrhage/diagnosis
- Subarachnoid Hemorrhage/etiology
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Affiliation(s)
- Frank E Musiek
- Department of Communication Sciences, Neuroraudiology Lab, University of Connecticut, Storrs, Connecticut 06269-1085, USA.
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Gaebler AJ, Zweerings J, Koten JW, König AA, Turetsky BI, Zvyagintsev M, Mathiak K. Impaired Subcortical Detection of Auditory Changes in Schizophrenia but Not in Major Depression. Schizophr Bull 2020; 46:193-201. [PMID: 31220318 PMCID: PMC6942154 DOI: 10.1093/schbul/sbz027] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The mismatch negativity is a cortical response to auditory changes and its reduction is a consistent finding in schizophrenia. Recent evidence revealed that the human brain detects auditory changes already at subcortical stages of the auditory pathway. This finding, however, raises the question where in the auditory hierarchy the schizophrenic deficit first evolves and whether the well-known cortical deficit may be a consequence of dysfunction at lower hierarchical levels. Finally, it should be resolved whether mismatch profiles differ between schizophrenia and affective disorders which exhibit auditory processing deficits as well. We used functional magnetic resonance imaging to assess auditory mismatch processing in 29 patients with schizophrenia, 27 patients with major depression, and 31 healthy control subjects. Analysis included whole-brain activation, region of interest, path and connectivity analysis. In schizophrenia, mismatch deficits emerged at all stages of the auditory pathway including the inferior colliculus, thalamus, auditory, and prefrontal cortex. In depression, deficits were observed in the prefrontal cortex only. Path analysis revealed that activation deficits propagated from subcortical to cortical nodes in a feed-forward mechanism. Finally, both patient groups exhibited reduced connectivity along this processing stream. Auditory mismatch impairments in schizophrenia already manifest at the subcortical level. Moreover, subcortical deficits contribute to the well-known cortical deficits and show specificity for schizophrenia. In contrast, depression is associated with cortical dysfunction only. Hence, schizophrenia and major depression exhibit different neural profiles of sensory processing deficits. Our findings add to a converging body of evidence for brainstem and thalamic dysfunction as a hallmark of schizophrenia.
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Affiliation(s)
- Arnim Johannes Gaebler
- Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH Aachen, Aachen, Germany
- JARA (Translational Brain Medicine), Aachen, Germany
- To whom correspondence should be addressed; Pauwels str. 30, 52074 Aachen, Germany; tel: +49-241-8088650, fax: +49-241-8082401: e-mail:
| | - Jana Zweerings
- Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH Aachen, Aachen, Germany
- JARA (Translational Brain Medicine), Aachen, Germany
| | | | - Andrea Anna König
- Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH Aachen, Aachen, Germany
- JARA (Translational Brain Medicine), Aachen, Germany
| | - Bruce I Turetsky
- Neuropsychiatry Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Mikhail Zvyagintsev
- Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH Aachen, Aachen, Germany
- JARA (Translational Brain Medicine), Aachen, Germany
- Brain Imaging Facility, Interdisciplinary Centre for Clinical Studies (IZKF), Medical Faculty, RWTH Aachen, Aachen, Germany
| | - Klaus Mathiak
- Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH Aachen, Aachen, Germany
- JARA (Translational Brain Medicine), Aachen, Germany
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Gonzalez D, Tomasek M, Hays S, Sridhar V, Ammanuel S, Chang CW, Pawlowski K, Huber KM, Gibson JR. Audiogenic Seizures in the Fmr1 Knock-Out Mouse Are Induced by Fmr1 Deletion in Subcortical, VGlut2-Expressing Excitatory Neurons and Require Deletion in the Inferior Colliculus. J Neurosci 2019; 39:9852-9863. [PMID: 31666356 PMCID: PMC6891051 DOI: 10.1523/jneurosci.0886-19.2019] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 09/06/2019] [Accepted: 10/16/2019] [Indexed: 02/07/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and the leading monogenetic cause of autism. One symptom of FXS and autism is sensory hypersensitivity (also called sensory over-responsivity). Perhaps related to this, the audiogenic seizure (AGS) is arguably the most robust behavioral phenotype in the FXS mouse model-the Fmr1 knock-out (KO) mouse. Therefore, the AGS may be considered a mouse model of sensory hypersensitivity. Hyperactive circuits are hypothesized to underlie dysfunction in a number of brain regions in patients with FXS and Fmr1 KO mice, and the AGS may be a result of this. But the specific cell types and brain regions underlying AGSs in the Fmr1 KO are unknown. We used conditional deletion or expression of Fmr1 in different cell populations to determine whether Fmr1 deletion in those cells was sufficient or necessary, respectively, for the AGS phenotype in males. Our data indicate that Fmr1 deletion in glutamatergic neurons that express vesicular glutamate transporter 2 (VGlut2) and are located in subcortical brain regions is sufficient and necessary to cause AGSs. Furthermore, the deletion of Fmr1 in glutamatergic neurons of the inferior colliculus is necessary for AGSs. When we demonstrate necessity, we show that Fmr1 expression in either the larger population of VGlut2-expressing glutamatergic neurons or the smaller population of inferior collicular glutamatergic neurons-in an otherwise Fmr1 KO mouse-eliminates AGSs. Therefore, targeting these neuronal populations in FXS and autism may be part of a therapeutic strategy to alleviate sensory hypersensitivity.SIGNIFICANCE STATEMENT Sensory hypersensitivity in fragile X syndrome (FXS) and autism patients significantly interferes with quality of life. Audiogenic seizures (AGSs) are arguably the most robust behavioral phenotype in the FXS mouse model-the Fmr1 knockout-and may be considered a model of sensory hypersensitivity in FXS. We provide the clearest and most precise genetic evidence to date for the cell types and brain regions involved in causing AGSs in the Fmr1 knockout and, more broadly, for any mouse mutant. The expression of Fmr1 in these same cell types in an otherwise Fmr1 knockout eliminates AGSs indicating possible cellular targets for alleviating sensory hypersensitivity in FXS and other forms of autism.
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Affiliation(s)
| | | | - Seth Hays
- Department of Neuroscience, Dallas, and
| | | | | | | | - Karen Pawlowski
- Department of Otolaryngology and Biomedical Engineering Program, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9035
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Auerbach BD, Radziwon K, Salvi R. Testing the Central Gain Model: Loudness Growth Correlates with Central Auditory Gain Enhancement in a Rodent Model of Hyperacusis. Neuroscience 2019; 407:93-107. [PMID: 30292765 PMCID: PMC8792806 DOI: 10.1016/j.neuroscience.2018.09.036] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/18/2018] [Accepted: 09/25/2018] [Indexed: 10/28/2022]
Abstract
The central gain model of hyperacusis proposes that loss of auditory input can result in maladaptive neuronal gain increases in the central auditory system, leading to the over-amplification of sound-evoked activity and excessive loudness perception. Despite the attractiveness of this model, and supporting evidence for it, a critical test of the central gain theory requires that changes in sound-evoked activity be explicitly linked to perceptual alterations of loudness. Here we combined an operant conditioning task that uses a subject's reaction time to auditory stimuli to produce reliable measures of loudness growth with chronic electrophysiological recordings from the auditory cortex and inferior colliculus of awake, behaviorally-phenotyped animals. In this manner, we could directly correlate daily assessments of loudness perception with neurophysiological measures of sound encoding within the same animal. We validated this novel psychophysical-electrophysiological paradigm with a salicylate-induced model of hearing loss and hyperacusis, as high doses of sodium salicylate reliably induce temporary hearing loss, neural hyperactivity, and auditory perceptual disruptions like tinnitus and hyperacusis. Salicylate induced parallel changes to loudness growth and evoked response-intensity functions consistent with temporary hearing loss and hyperacusis. Most importantly, we found that salicylate-mediated changes in loudness growth and sound-evoked activity were correlated within individual animals. These results provide strong support for the central gain model of hyperacusis and demonstrate the utility of using an experimental design that allows for within-subject comparison of behavioral and electrophysiological measures, thereby making inter-subject variability a strength rather than a limitation.
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Affiliation(s)
- Benjamin D Auerbach
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, NY 14214, USA.
| | - Kelly Radziwon
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, NY 14214, USA
| | - Richard Salvi
- Center for Hearing and Deafness, State University of New York at Buffalo, Buffalo, NY 14214, USA
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Kim SY, Heo H, Kim DH, Kim HJ, Oh SH. Neural Plastic Changes in the Subcortical Auditory Neural Pathway after Single-Sided Deafness in Adult Mice: A MEMRI Study. Biomed Res Int 2018; 2018:8624745. [PMID: 30599000 PMCID: PMC6287207 DOI: 10.1155/2018/8624745] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/30/2018] [Accepted: 11/09/2018] [Indexed: 01/14/2023]
Abstract
Single-sided deafness (SSD) induces cortical neural plastic changes according to duration of deafness. However, it is still unclear how the auditory cortical changes accompany the subcortical neural changes. The present study aimed to find the neural plastic changes in the cortical and subcortical auditory system following adult-onset single-sided deafness (SSD) using Mn-enhanced magnetic resonance imaging (MEMRI). B57BL/6 mice (postnatal 8-week-old) were divided into three groups: the SSD-4-week group (postnatal 12-week-old, n = 11), the SSD-8-week group (postnatal 16-week-old, n = 11), and a normal-hearing control group (postnatal 8-week-old, n = 9). The left cochlea was ablated in the SSD groups. White Gaussian noise was delivered for 24 h before MEMRI acquisition. T1-weighted MRI data were analyzed from the cochlear nucleus (CN), superior olivary complex (SOC), lateral lemniscus (LL), inferior colliculus (IC), medial geniculate body (MG), and auditory cortex (AC). The differences in relative Mn2+-enhanced signal intensities (Mn2+SI) and laterality were analyzed between the groups. Four weeks after the SSD procedure, the ipsilateral side of the SSD showed significantly lower Mn2+SI in the CN than the control group. On the other hand, the contralateral side of the SSD demonstrated significantly lower Mn2+SI in the SOC, LL, and IC. These decreased Mn2+SI values were partially recovered at 8 weeks after the SSD procedure. The interaural Mn2+SI differences representing the interaural dominance were highest in CN and then became less prominently higher in the auditory neural system. The SSD-8-week group still showed interaural differences in the CN, LL, and IC. In contrast, the MG and AC did not show any significant intergroup or interaural differences in Mn2+SI. In conclusion, subcortical auditory neural activities were decreased after SSD, and the interaural differences were diluted in the higher auditory nervous system. These findings were attenuated with time. Subcortical auditory neural changes after SSD may contribute to the change in tinnitus severity and the outcomes of cochlear implantation in SSD patients.
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Affiliation(s)
- So Young Kim
- Department of Otorhinolaryngology-Head & Neck Surgery, CHA Bundang Medical Center, CHA University, Seongnam, Republic of Korea
| | - Hwon Heo
- Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Doo Hee Kim
- Department of Otorhinolaryngology-Head & Neck Surgery, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Brain Science, Seoul National University, Seoul, Republic of Korea
| | - Hyun Jin Kim
- Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Seung-ha Oh
- Department of Otorhinolaryngology-Head & Neck Surgery, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Brain Science, Seoul National University, Seoul, Republic of Korea
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Coleman JR, Thompson KC, Wilson MA, Wilson SP. Audiogenic seizure activity following HSV-1 GAD65 sense or antisense injection into inferior colliculus of Long-Evans rat. Epilepsy Behav 2017; 71:238-242. [PMID: 27993512 DOI: 10.1016/j.yebeh.2016.08.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 08/22/2016] [Accepted: 08/25/2016] [Indexed: 11/19/2022]
Abstract
Herpes virus technology involving manipulation of GAD65 was used to study effects on audiogenic seizures (AGS). Audiogenic seizure behaviors were examined following injections of replication-defective herpes simplex virus (HSV-1) vectors incorporating sense or antisense toward GAD65 along with 10% lac-Z into the central nucleus of inferior colliculus (CNIC) of Long-Evans rats. In seizure-sensitive animals developmentally primed by intense sound exposure, injection of GAD65 in the sense orientation increased wild running latencies and reduced incidence of clonus compared with lac-Z only, unoperated, and vehicle seizure groups. In contrast, infection of CNIC with GAD65 antisense virus resulted in 100% incidence of wild running and clonus behaviors in AGS animals. Unprimed animals not operated continued to show uniform absence of seizure activity. Administration of GAD65 antisense virus into CNIC produced novel wild running and clonus behaviors in some unprimed animals. Staining for β-galactosidase in all vector animals revealed no differences in pattern or numbers of immunoreactive cells at injection sites. Qualitatively, typical small and medium multipolar/stellate and medium fusiform neurons appeared in the CNIC of vector animals. These results demonstrate that HSV-1 vector constructs implanted into the CNIC can predictably influence incidence and severity of AGS and suggest that viral vectors can be useful in studying GABA mechanisms with potential for therapeutic application in epilepsy. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".
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Affiliation(s)
- James R Coleman
- Department of Psychology, University of South Carolina, Barnwell College, Columbia, SC 20208, United States; Department of Pharmacology, Physiology & Neuroscience, University of South Carolina, School of Medicine, Columbia, SC 29209, United States; Psychology Program, South University, 9 Science Ct., Columbia, SC 29203, United States.
| | - Karen C Thompson
- Department of Psychology, University of South Carolina, Barnwell College, Columbia, SC 20208, United States; Behavioral Studies Program, Columbia College, Columbia, SC 29203, United States
| | - Marlene A Wilson
- Department of Pharmacology, Physiology & Neuroscience, University of South Carolina, School of Medicine, Columbia, SC 29209, United States
| | - Steven P Wilson
- Department of Pharmacology, Physiology & Neuroscience, University of South Carolina, School of Medicine, Columbia, SC 29209, United States
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Jiang C, Luo B, Manohar S, Chen GD, Salvi R. Plastic changes along auditory pathway during salicylate-induced ototoxicity: Hyperactivity and CF shifts. Hear Res 2017; 347:28-40. [PMID: 27989950 PMCID: PMC5403591 DOI: 10.1016/j.heares.2016.10.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/30/2016] [Accepted: 10/26/2016] [Indexed: 12/27/2022]
Abstract
High dose of salicylate, the active ingredient in aspirin, has long been known to induce transient hearing loss, tinnitus and hyperacusis making it a powerful experimental tool. These salicylate-induced perceptual disturbances are associated with a massive reduction in the neural output of the cochlea. Paradoxically, the diminished neural output of the cochlea is accompanied by a dramatic increase in sound-evoked activity in the auditory cortex (AC) and several other parts of the central nervous system. Exactly where the increase in neural activity begins and builds up along the central auditory pathway are not fully understood. To address this issue, we measured sound-evoked neural activity in the cochlea, cochlear nucleus (CN), inferior colliculus (IC), and AC before and after administering a high dose of sodium salicylate (SS, 300 mg/kg). The SS-treatment abolished low-level sound-evoked responses along the auditory pathway resulting in a 20-30 dB threshold shift. While the neural output of the cochlea was substantially reduced at high intensities, the neural responses in the CN were only slightly reduced; those in the IC were nearly normal or slightly enhanced while those in the AC considerably enhanced, indicative of a progress increase in central gain. The SS-induced increase in central response in the IC and AC was frequency-dependent with the greatest increase occurring in the mid-frequency range the putative pitch of SS-induced tinnitus. This frequency-dependent hyperactivity appeared to result from shifts in the frequency receptive fields (FRF) such that the response areas of many FRF shifted/expanded toward the mid-frequencies. Our results suggest that the SS-induced threshold shift originates in the cochlea. In contrast, enhanced central gain is not localized to one region, but progressively builds up at successively higher stage of the auditory pathway either through a loss of inhibition and/or increased excitation.
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Affiliation(s)
- Chen Jiang
- Department of Neurosurgery, Anhui Provincial Hospital, 17 Lujiang Road, Hefei, Anhui 230001, China; Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA
| | - Bin Luo
- Department of Neurosurgery, Anhui Provincial Hospital, 17 Lujiang Road, Hefei, Anhui 230001, China; Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA
| | - Senthilvelan Manohar
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA
| | - Guang-Di Chen
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA.
| | - Richard Salvi
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA
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Yang S, Mei Z, Tan L, Ma W, Zhang D, Wang Z, Li T, Huang K, Cai S. [Effects of electrical stimulation at acupoints in the distribution area of auricular vagus nerve combined with sound masking method on auditory brainstem response and neurotransmitters of inferior colliculus in rats of tinnitus]. Zhongguo Zhen Jiu 2016; 36:517-522. [PMID: 27509615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
OBJECTIVE To explore the effects of electrical stimulation at acupoints in the distribution area of auricular vagus nerve combined with sound masking on auditory brainstem response (ABR) and contents of neurotransmitters of γ-aminobutyric acid (γ-GABA), 5-hydroxytryptamine (5-HT) and acetyl choline (Ach) in inferior colliculus of tinnitus rats. METHODS Twenty-four male adult SD rats were randomized into a control group, a model group, a 7-d treatment group and a 15-d treatment group. Except the control group, rats in the remaining groups were treated with intraperitoneal injection of 10% salicylate sodium at a dose of 350 mg/kg to establish tinnitus model. Rats in the control group were treated with injection of 0.9% NaCl. Rats in the 7-d treatment group and 15-d treatment group were treated with electrical stimulation at "Shenmen (TF₄)" and "Yidan (CO₁₁)" in the distribution area of auricular vagus nerve combined with sound masking, once a day, for 7 days and 15 days. The SigGenRP software of TDT system was applied to provide voice for single ear and collect the signal, and the voice threshold of ABR was tested. The levels of γ-GABA, 5-HT and Ach in inferior colliculus of rats were detected by enzyme linked immunosorbent assay (ELISA) and compared. RESULTS Compared with the model group, the threshold values of ABR in 12 kHz and 16 kHz voice stimulation in the 7-d treatment group were significantly lower all P < 0.05); the threshold values of ABR from 4 kHz to 28 kHz voice stimulation in the 15-d treatment group were signally reduced (P < 0.05, P < 0.01), which was more significant than those in the 7-d treatment group. The level of γ-GABA in the model group was significantly lower than that in the control group (P < 0.05), and that in the 15-d treatment group was apparently higher than that in the model group (P < 0.05). The level of 5-HT in the model group was markedly higher than that in the control group (P < 0.05), and that in the 7-d treatment group was lower than that in the model group (P < 0.05), while that in the 15-d treatment group was apparently higher than that in the model group (P < 0.05). The level of Ach in the model group was obviously; lower than that in the control group (P < 0.05), and that in the 7-d treatment group was higher than that in the model group (P < 0.05). CONCLUSION Electrical stimulation at auricular vagus nerve combined with sound masking) could regulate the threshold of ABR, especially in the 15-d treatment group. This may be ascribed to modulating the levels of neurotransmitter of γ-GABA, 5-HT and Ach in inferior colliculus.
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Mulders WHAM, Spencer TC, Robertson D. Effects of pulsatile electrical stimulation of the round window on central hyperactivity after cochlear trauma in guinea pig. Hear Res 2016; 335:128-137. [PMID: 26970475 DOI: 10.1016/j.heares.2016.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 02/09/2016] [Accepted: 03/03/2016] [Indexed: 11/17/2022]
Abstract
Partial hearing loss induced by acoustic trauma has been shown in animal models to result in an increased spontaneous firing rate in central auditory structures. This so-called hyperactivity has been suggested to be involved in the generation of tinnitus, a phantom auditory sensation. Although there is no universal cure for tinnitus, electrical stimulation of the cochlea, as achieved by a cochlear implant, can result in significant reduction of the tinnitus percept. However, the mechanism by which this tinnitus suppression occurs is as yet unknown and furthermore cochlear implantation may not be an optimal treatment option for tinnitus sufferers who are not profoundly deaf. A better understanding of the mechanism of tinnitus suppression by electrical stimulation of the cochlea, may lead to the development of more specialised devices for those for whom a cochlear implant is not appropriate. This study aimed to investigate the effects of electrical stimulation in the form of brief biphasic shocks delivered to the round window of the cochlea on the spontaneous firing rates of hyperactive inferior colliculus neurons following acoustic trauma in guinea pigs. Effects during the stimulation itself included both inhibition and excitation but spontaneous firing was suppressed for up to hundreds of ms after the cessation of the shock train in all sampled hyperactive neurons. Pharmacological block of olivocochlear efferent action on outer hair cells did not eliminate the prolonged suppression observed in inferior colliculus neurons, and it is therefore likely that activation of the afferent pathways is responsible for the central effects observed.
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Affiliation(s)
- W H A M Mulders
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia.
| | - T C Spencer
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
| | - D Robertson
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
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Peng L, Yu S, Chen R, Jing Y, Liang J. [Correlation of diffusion tensor imaging between the cerebral cortex and speech discrimination in presbycusis]. Lin Chuang Er Bi Yan Hou Tou Jing Wai Ke Za Zhi 2015; 29:1605-1609. [PMID: 26790258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
OBJECTIVE To investigate the relationship between pure-tone average (PTA), the fractional anisotropy (FA) of the auditory pathway, cognitive cortex and auditory cortex in presbycusis. METHOD Twenty-five elderly subjects with presbycusis were participated in the study. PTA, speech discrimination abilities were evaluated in each subject. Diffusion tensor imaging (DTI) was applied to access the FA of the IC, the superior frontal gyrus and the Heschl's gyrus. Compare the difference between two sides of the values of FA in the three areas. Bivariate correlation analysis was performed to evaluate the effects of PTA and FA of the inferior colliculus (IC), the superior frontal gyrus and the Heschl's gyrus on speech discrimination abilities. RESULT There were no significant differences between the left and right side of the inferior colliculus (P > 0.05). Higher FA values were recorded at the left side of the Heschl's gyrus and the superior frontal gyrus (P < 0.05). Both PTA and the FA of the superior frontal gyrus have a negative association with speech discrimination abilities (P < 0.01, P < 0.05), while the FA of the Heschl's gyrus has a positive association with speech discrimination abilities (P < 0.05). CONCLUSION Our findings indicated that the speech discrimination abilities of the elderly is not only related to the peripheral auditory function, but also to the central auditory and cognitive function.
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N'Gouemo P. Altered voltage-gated calcium channels in rat inferior colliculus neurons contribute to alcohol withdrawal seizures. Eur Neuropsychopharmacol 2015; 25:1342-52. [PMID: 25914156 PMCID: PMC4526435 DOI: 10.1016/j.euroneuro.2015.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Accepted: 04/01/2015] [Indexed: 11/16/2022]
Abstract
We have previously reported that enhanced susceptibility to alcohol withdrawal seizures (AWS) parallels the enhancement of the current density of high-threshold voltage-gated Ca(2+) (CaV) channels in rat inferior colliculus (IC) neurons. However, whether this increased current density is a cause or consequence of AWS is unclear. Here, I report changes in the current density of CaV channels in IC neurons during the course of alcohol withdrawal and the potential anticonvulsant effect of intra-IC infusions of L- and P-type CaV channel antagonists. Whole-cell currents were activated by depolarizing pulses using barium as the charge carrier. Currents and seizure susceptibility were evaluated in control animals 3h after alcohol intoxication, as well as 3h (before AWS), 24h (when AWS susceptibility is maximal), and 48h (when AWS susceptibility is no longer present) after alcohol withdrawal. Nifedipine, nimodipine (L-type antagonists) or ω-agatoxin TK (P-type antagonist) were infused intra-IC to probe the role of CaV channels in the pathogenesis of AWS. CaV current density and conductance in IC neurons were significantly increased 3 and 24h after alcohol withdrawal compared with the control group or the group tested 3h following ethanol intoxication. Blockade of L-type CaV channels within the IC completely suppressed AWS, and inhibition of P-type channels reduced AWS severity. These findings suggest that the enhancement of CaV currents in IC neurons occurs prior to AWS onset and that alterations in L- and P-type CaV channels in these neurons may underlie the pathogenesis of AWS.
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Affiliation(s)
- Prosper N'Gouemo
- Department of Pediatrics, Georgetown, University Medical Center, Washington, DC, USA.
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Gloeckner CD, Smith BT, Markovitz CD, Lim HH. A new concept for noninvasive tinnitus treatment utilizing multimodal pathways. Annu Int Conf IEEE Eng Med Biol Soc 2015; 2013:3122-5. [PMID: 24110389 DOI: 10.1109/embc.2013.6610202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Current noninvasive treatments for tinnitus have shown mixed results. There have been encouraging developments in using invasive brain or vagal nerve stimulation to modulate neural populations driving the tinnitus percept. However, these invasive treatments can only be used in a small patient population with severe conditions. In this preliminary study, we present a new treatment option we call Multimodal Synchronization Therapy (MST), which attempts to achieve synchronized and localized brain activation without invasive neural stimulation. MST combines multiple sensory, motor, limbic, and cognitive inputs to elicit activation of multimodal neurons to potentially modulate specific neurons driving the tinnitus percept. We present preliminary data in a guinea pig model showing activation of somatosensory and auditory pathways to alter neural activity within the inferior colliculus, a multimodal integration region that has shown pathological changes in animals and patients with tinnitus. Electrical stimulation of different body locations induced excitatory responses in the inferior colliculus, eliciting responses in up to 41% of all recording sites for a given somatic site. Paired somatic and acoustic stimulation resulted in enhanced or suppressed acoustic-driven neural activity in the inferior colliculus that varied depending on stimulation and recording location. Similar modulation effects were observed in the auditory cortex, which may relate to changes in auditory perception. Further studies need to incorporate multiple multimodal pathways and must also confirm that MST can suppress the abnormal neural patterns that directly drive the tinnitus percept.
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Abstract
The inferior colliculus is a mesencephalic structure endowed with serotonergic fibers that plays an important role in the processing of acoustic information. The implication of the neuromodulator serotonin also in the aetiology of sudden unexplained fetal and infant death syndromes and the demonstration in these pathologies of developmental alterations of the superior olivary complex (SOC), a group of pontine nuclei likewise involved in hearing, prompted us to investigate whether the inferior colliculus may somehow contribute to the pathogenetic mechanism of unexplained perinatal death. Therefore, we performed in a wide set of fetuses and infants, aged from 33 gestational weeks to 7 postnatal months and died of both known and unknown cause, an in-depth anatomopathological analysis of the brainstem, particularly of the midbrain. Peculiar neuroanatomical and functional abnormalities of the inferior colliculus, such as hypoplasia/structural disarrangement and immunonegativity or poor positivity of serotonin, were exclusively found in sudden death victims, and not in controls. In addition, these alterations were frequently related to dysgenesis of connected structures, precisely the raphé nuclei and the superior olivary complex, and to nicotine absorption in pregnancy. We propose, on the basis of these results, the involvement of the inferior colliculus in more important functions than those related to hearing, as breathing and, more extensively, all the vital activities, and then in pathological conditions underlying a sudden death in vulnerable periods of the autonomic nervous system development, particularly associated to harmful risk factors as cigarette smoking.
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Affiliation(s)
- Anna M Lavezzi
- From the "Lino Rossi" Research Center for the Study and Prevention of Unexpected Perinatal Death and SIDS, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Italy (AML, LM) and Institute of Anatomic Pathology, Hospital of Rovereto (Trento), Italy (TP)
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Ropp TJF, Tiedemann KL, Young ED, May BJ. Effects of unilateral acoustic trauma on tinnitus-related spontaneous activity in the inferior colliculus. J Assoc Res Otolaryngol 2014; 15:1007-22. [PMID: 25255865 PMCID: PMC4389963 DOI: 10.1007/s10162-014-0488-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 09/08/2014] [Indexed: 12/13/2022] Open
Abstract
This study describes the long-term effects of sound-induced cochlear trauma on spontaneous discharge rates in the central nucleus of the inferior colliculus (ICC). As in previous studies, single-unit recordings in Sprague-Dawley rats revealed pervasive increases in spontaneous discharge rates. Based on differences in their sources of input, it was hypothesized that physiologically defined neural populations of the auditory midbrain would reveal the brainstem sources that dictate ICC hyperactivity. Abnormal spontaneous activity was restricted to target neurons of the ventral cochlear nucleus. Nearly identical patterns of hyperactivity were observed in the contralateral and ipsilateral ICC. The elevation in spontaneous activity extended to frequencies well below and above the region of maximum threshold shift. This lack of frequency organization suggests that ICC hyperactivity may be influenced by regions of the brainstem that are not tonotopically organized. Sound-induced hyperactivity is often observed in animals with behavioral signs of tinnitus. Prior to electrophysiological recording, rats were screened for tinnitus by measuring gap pre-pulse inhibition of the acoustic startle reflex (GPIASR). Rats with positive phenotypes did not exhibit unique patterns of ICC hyperactivity. This ambiguity raises concerns regarding animal behavioral models of tinnitus. If our screening procedures were valid, ICC hyperactivity is observed in animals without behavioral indications of the disorder. Alternatively, if the perception of tinnitus is strictly linked to ongoing ICC hyperactivity, our current behavioral approach failed to provide a reliable assessment of tinnitus state.
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Affiliation(s)
- Tessa-Jonne F. Ropp
- />Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Kerrie L. Tiedemann
- />Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Eric D. Young
- />Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Bradford J. May
- />Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University School of Medicine, Traylor Research Building, Room 521 720 Rutland Avenue, Baltimore, MD 21205 USA
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15
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Abstract
Hearing loss induces plasticity in excitatory and inhibitory neurotransmitter systems in auditory brain regions. Excitatory-inhibitory balance is also influenced by a range of neuromodulatory regulatory systems, but less is known about the effects of auditory damage on these networks. In this work, we studied the effects of acoustic trauma on neuromodulatory plasticity in the auditory midbrain of CBA/J mice. Quantitative PCR was used to measure the expression of serotonergic and GABAergic receptor genes in the inferior colliculus (IC) of mice that were unmanipulated, sham controls with no hearing loss, and experimental individuals with hearing loss induced by exposure to a 116 dB, 10 kHz pure tone for 3 h. Acoustic trauma induced substantial hearing loss that was accompanied by selective upregulation of two serotonin receptor genes in the IC. The Htr1B receptor gene was upregulated tenfold following trauma relative to shams, while the Htr1A gene was upregulated threefold. In contrast, no plasticity in serotonin receptor gene expression was found in the hippocampus, a region also innervated by serotonergic projections. Analyses in the IC demonstrated that acoustic trauma also changed the coexpression of genes in relation to each other, leading to an overexpression of Htr1B compared to other genes. These data suggest that acoustic trauma induces serotonergic plasticity in the auditory system, and that this plasticity may involve comodulation of functionally-linked receptor genes.
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Affiliation(s)
- Adam R Smith
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
| | - Jae Hyun Kwon
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Marco Navarro
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Department of Biology, Saint Louis University, Saint Louis, MO 63103, USA
| | - Laura M Hurley
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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Vataev SI, Mal'gina NA, Oganesian GA. [Inferior colliculus stimulation effects in KrushinskiI-Molodkina strain rats]. Ross Fiziol Zh Im I M Sechenova 2014; 100:699-709. [PMID: 25665395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The effects of the central nucleus of the inferior colliculus chemical and electrical stimulation on the producing and forming the convulsive manifestations, as well as on the organization of sleep, was studied in Krushinskii-Molodkina strain rats, which have an inherited predisposition to audiogenic seizures. Microinjections of quinolinic acid (10 micrograms) or electrical stimulation with 70 Hz frequency produced the paroxysmal manifestations in the form of intensive circular excursions coincident wild running behaviors on the initial nonseizures motor exitation stage of audiogenic seizures. The results suggest that in Krushinskii-Molodkina strain rats the inferior colliculus is involved in the neuronal network, responsible for initiation and realization to the scampering stage of the evoked convulsive reactions to sound. The reduction of fast-wave (paradoxical) sleep total duration after the given actions it was observed. However, the inferior colliculus electrical stimulation with 7 Hz frequency during slow-wave sleep cause appearance the episodes fast-wave sleep. A significant (almost twice due) increase of the total time of fast-wave sleep by increasing the quantity, but not the duration of these episodes after 3-4 sessions of such sort stimulations were observed. These results showed that the inferior colliculus rats can produce the modulating action on the brain system responsible for triggering fast-wave sleep.
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Mulders WHAM, Barry KM, Robertson D. Effects of furosemide on cochlear neural activity, central hyperactivity and behavioural tinnitus after cochlear trauma in guinea pig. PLoS One 2014; 9:e97948. [PMID: 24835470 PMCID: PMC4023991 DOI: 10.1371/journal.pone.0097948] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 04/27/2014] [Indexed: 11/19/2022] Open
Abstract
Cochlear trauma causes increased spontaneous activity (hyperactivity) to develop in central auditory structures, and this has been suggested as a neural substrate for tinnitus. Using a guinea pig model we have previously demonstrated that for some time after cochlear trauma, central hyperactivity is dependent on peripheral afferent drive and only later becomes generated intrinsically within central structures. Furosemide, a loop diuretic, reduces spontaneous firing of auditory afferents. We investigated in our guinea pig model the efficacy of furosemide in reducing 1) spontaneous firing of auditory afferents, using the spectrum of neural noise (SNN) from round window recording, 2) hyperactivity in inferior colliculus, using extracellular single neuron recordings and 3) tinnitus at early time-points after cochlear trauma. Tinnitus was assessed using gap prepulse inhibition of acoustic startle (GPIAS). Intraperitoneal furosemide, but not saline, caused a marked decrease in both SNN and central hyperactivity. Intracochlear perfusion with furosemide similarly reversed central hyperactivity. In animals in which GPIAS measurements suggested the presence of tinnitus (reduced GPIAS), this could be reversed with an intraperitoneal injection with furosemide but not saline. The results are consistent with furosemide reducing central hyperactivity and behavioural signs of tinnitus by acting peripherally to decrease spontaneous firing of auditory afferents. The data support the notion that hyperactivity may be involved in the generation of tinnitus and further suggest that there may be a therapeutic window after cochlear trauma using drug treatments that target peripheral spontaneous activity.
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Affiliation(s)
- Wilhelmina H. A. M. Mulders
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, Western Australia, Australia
- * E-mail:
| | - Kristin M. Barry
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, Western Australia, Australia
| | - Donald Robertson
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, Western Australia, Australia
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Nakajima M, Nishikawa C, Miyasaka Y, Kikkawa Y, Mori H, Tsuruta M, Okuyama S, Furukawa Y. Dilation of the inferior colliculus and hypersensitivity to sound in Wnt1-cre and Wnt1-GAL4 double-transgenic mice. Neurosci Lett 2014; 566:236-40. [PMID: 24607930 DOI: 10.1016/j.neulet.2014.02.061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Revised: 02/21/2014] [Accepted: 02/26/2014] [Indexed: 11/17/2022]
Abstract
The processing of sound information is mediated by the cochlea and the central auditory system. Among the central auditory system, the inferior colliculus (IC) has leading roles in the acoustic processing. In a previous study, we demonstrated psychiatric disorder-related behavioral abnormalities in a genetically modified animal of Wnt1-cre and Wnt1-GAL4 double-transgenic (dTg) mouse. Here we report an abnormal morphology of the IC and dysacusis in the dTg mice. The IC in the brain of the dTg mice is dilated in appearance and histologic analysis revealed a high cell-density in the IC. Also, the dTg mice showed high scores in a startle response test using a click box that emits a 20-kHz sound. Auditory brainstem response (ABR) test revealed lower ABR thresholds of the dTg mice at a test-stimulus frequency of 32kHz, but not at 4-16kHz. These findings suggest that the dTg mice could be a useful animal model for studying the physiologic function of the IC and the pathophysiology of psychiatric disorder-related dysacusis.
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Affiliation(s)
- Mitsunari Nakajima
- Department of Pharmaceutical Pharmacology, School of Clinical Pharmacy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Ehime, Japan.
| | - Chisa Nishikawa
- Department of Pharmaceutical Pharmacology, School of Clinical Pharmacy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Ehime, Japan
| | - Yuki Miyasaka
- Mammalian Genetics Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan; Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8510, Japan
| | - Yoshiaki Kikkawa
- Mammalian Genetics Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Hisamichi Mori
- Department of Pharmaceutical Pharmacology, School of Clinical Pharmacy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Ehime, Japan
| | - Momoko Tsuruta
- Department of Pharmaceutical Pharmacology, School of Clinical Pharmacy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Ehime, Japan
| | - Satoshi Okuyama
- Department of Pharmaceutical Pharmacology, School of Clinical Pharmacy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Ehime, Japan
| | - Yoshiko Furukawa
- Department of Pharmaceutical Pharmacology, School of Clinical Pharmacy, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Ehime, Japan
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Abstract
BACKGROUND The study of tinnitus mechanisms has increased tenfold in the last decade. The common denominator for all of these studies is the goal of elucidating the underlying neural mechanisms of tinnitus with the ultimate purpose of finding a cure. While these basic science findings may not be immediately applicable to the clinician who works directly with patients to assist them in managing their reactions to tinnitus, a clear understanding of these findings is needed to develop the most effective procedures for alleviating tinnitus. PURPOSE The goal of this review is to provide audiologists and other health-care professionals with a basic understanding of the neurophysiological changes in the auditory system likely to be responsible for tinnitus. RESULTS It is increasingly clear that tinnitus is a pathology involving neuroplastic changes in central auditory structures that take place when the brain is deprived of its normal input by pathology in the cochlea. Cochlear pathology is not always expressed in the audiogram but may be detected by more sensitive measures. Neural changes can occur at the level of synapses between inner hair cells and the auditory nerve and within multiple levels of the central auditory pathway. Long-term maintenance of tinnitus is likely a function of a complex network of structures involving central auditory and nonauditory systems. CONCLUSIONS Patients often have expectations that a treatment exists to cure their tinnitus. They should be made aware that research is increasing to discover such a cure and that their reactions to tinnitus can be mitigated through the use of evidence-based behavioral interventions.
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Affiliation(s)
- James A. Henry
- VA RR&D National Center for Rehabilitative Auditory Research (NCRAR), VA Medical Center, Portland, OR
- Department of Otolaryngology/Head and Neck Surgery, Oregon Health and Science University, Portland, OR
| | - Larry E. Roberts
- Department of Psychology, Neuroscience, and Behaviour, McMaster University, Hamilton, Ontario, Canada
| | - Donald M. Caspary
- Pharmacology Department, Southern Illinois University School of Medicine, Springfield, IL
| | - Sarah M. Theodoroff
- VA RR&D National Center for Rehabilitative Auditory Research (NCRAR), VA Medical Center, Portland, OR
- Department of Otolaryngology/Head and Neck Surgery, Oregon Health and Science University, Portland, OR
| | - Richard J. Salvi
- Center for Hearing and Deafness, University of Buffalo, Buffalo, NY
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Hancock KE, Chung Y, Delgutte B. Congenital and prolonged adult-onset deafness cause distinct degradations in neural ITD coding with bilateral cochlear implants. J Assoc Res Otolaryngol 2013; 14:393-411. [PMID: 23462803 PMCID: PMC3642270 DOI: 10.1007/s10162-013-0380-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/15/2013] [Indexed: 10/27/2022] Open
Abstract
Bilateral cochlear implant (CI) users perform poorly on tasks involving interaural time differences (ITD), which are critical for sound localization and speech reception in noise by normal-hearing listeners. ITD perception with bilateral CI is influenced by age at onset of deafness and duration of deafness. We previously showed that ITD coding in the auditory midbrain is degraded in congenitally deaf white cats (DWC) compared to acutely deafened cats (ADC) with normal auditory development (Hancock et al., J. Neurosci, 30:14068). To determine the relative importance of early onset of deafness and prolonged duration of deafness for abnormal ITD coding in DWC, we recorded from single units in the inferior colliculus of cats deafened as adults 6 months prior to experimentation (long-term deafened cats, LTDC) and compared neural ITD coding between the three deafness models. The incidence of ITD-sensitive neurons was similar in both groups with normal auditory development (LTDC and ADC), but significantly diminished in DWC. In contrast, both groups that experienced prolonged deafness (LTDC and DWC) had broad distributions of best ITDs around the midline, unlike the more focused distributions biased toward contralateral-leading ITDs present in both ADC and normal-hearing animals. The lack of contralateral bias in LTDC and DWC results in reduced sensitivity to changes in ITD within the natural range. The finding that early onset of deafness more severely degrades neural ITD coding than prolonged duration of deafness argues for the importance of fitting deaf children with sound processors that provide reliable ITD cues at an early age.
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Affiliation(s)
- Kenneth E. Hancock
- />Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, MA 02114 USA
- />Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115 USA
| | - Yoojin Chung
- />Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, MA 02114 USA
- />Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115 USA
| | - Bertrand Delgutte
- />Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, MA 02114 USA
- />Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115 USA
- />Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
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Su YY, Luo B, Jin Y, Wu SH, Lobarinas E, Salvi RJ, Chen L. Altered neuronal intrinsic properties and reduced synaptic transmission of the rat's medial geniculate body in salicylate-induced tinnitus. PLoS One 2012; 7:e46969. [PMID: 23071681 PMCID: PMC3468622 DOI: 10.1371/journal.pone.0046969] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 09/10/2012] [Indexed: 12/31/2022] Open
Abstract
Sodium salicylate (NaSal), an aspirin metabolite, can cause tinnitus in animals and human subjects. To explore neural mechanisms underlying salicylate-induced tinnitus, we examined effects of NaSal on neural activities of the medial geniculate body (MGB), an auditory thalamic nucleus that provides the primary and immediate inputs to the auditory cortex, by using the whole-cell patch-clamp recording technique in MGB slices. Rats treated with NaSal (350 mg/kg) showed tinnitus-like behavior as revealed by the gap prepulse inhibition of acoustic startle (GPIAS) paradigm. NaSal (1.4 mM) decreased the membrane input resistance, hyperpolarized the resting membrane potential, suppressed current-evoked firing, changed the action potential, and depressed rebound depolarization in MGB neurons. NaSal also reduced the excitatory and inhibitory postsynaptic response in the MGB evoked by stimulating the brachium of the inferior colliculus. Our results demonstrate that NaSal alters neuronal intrinsic properties and reduces the synaptic transmission of the MGB, which may cause abnormal thalamic outputs to the auditory cortex and contribute to NaSal-induced tinnitus.
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Affiliation(s)
- Yan-Yan Su
- CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, China
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Abstract
CONCLUSIONS Conductive hearing loss (CHL) lowers resting neural activity patterns in the auditory periphery. Such reductions of peripheral auditory activity may influence the developing central brain during early postnatal years when the system is still highly plastic. OBJECTIVES A common cause of CHL in young children is otitis media; if chronic and/or episodic there may be a risk to speech and language development. In this clinical context we have investigated changes in neural activity patterns in the brainstem and midbrain in an animal model of CHL. METHODS In a mouse model, a 50-60 dB CHL was produced by blocking the ear canals. We quantified resting neural activity patterns in the cochlear nucleus and inferior colliculus using c-fos immuno-labelling. This experimental group was compared with normal-hearing controls and with animals with bilateral cochlear ablation. RESULTS Subjects with CHL had a statistically significant reduction in c-fos-labelled cells in the cochlear nucleus and central nucleus of the inferior colliculus compared with normal controls. This decreased c-fos expression suggests a change in resting neural activity generated at the inner hair cell synapse, leading to a reduction in activity levels in the ascending auditory pathways.
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Affiliation(s)
- Robert V Harrison
- Auditory Science Laboratory, Department of Otolaryngology-HNS, Hospital for Sick Children, ON, Canada.
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Cowper-Smith CD, Dingle RN, Guo Y, Burkard R, Phillips DP. Synchronous auditory nerve activity in the carboplatin-chinchilla model of auditory neuropathy. J Acoust Soc Am 2010; 128:EL56-EL62. [PMID: 20649190 PMCID: PMC2905450 DOI: 10.1121/1.3453764] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Accepted: 05/20/2010] [Indexed: 05/29/2023]
Abstract
Two hallmark features of auditory neuropathy (AN) are normal outer hair cell function in the presence of an absent/abnormal auditory brainstem response (ABR). Studies of human AN patients are unable to determine whether disruption of the ABR is the result of a reduction of neural input, a loss of auditory nerve fiber (ANF) synchrony, or both. Neurophysiological data from the carboplatin model of AN reveal intact neural synchrony in the auditory nerve and inferior colliculus, despite significant reductions in neural input. These data suggest that (1), intact neural synchrony is available to support an ABR following carboplatin treatment and, (2), impaired spike timing intrinsic to neurons is required for the disruption of the ABR observed in human AN.
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Affiliation(s)
- C D Cowper-Smith
- Department of Psychology, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia B3H 4J1, Canada.
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Vollmer M, Hartmann R, Tillein J. Neuronal responses in cat inferior colliculus to combined acoustic and electric stimulation. Adv Otorhinolaryngol 2009; 67:61-69. [PMID: 19955722 DOI: 10.1159/000262597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
The present study explored the interactions of combined electric and acoustic stimulation (EAS) on neural responses in the central auditory system. Normal-hearing cats were implanted unilaterally with scala tympani electrodes. Two experimental approaches were used. First, in a forward-masking paradigm, single biphasic electric pulses were used as maskers, unmodulated acoustic tone bursts at the neuron's characteristic frequency (CF) were used as probes. Then, in a simultaneous-masking paradigm, the masking effects of acoustic tones (CF) on responses to single electric pulses (probes) were examined. In the second approach, we studied the effects of phase relationship between acoustic and electric stimulation. Sinusoidal amplitude-modulated (30 Hz) CF tones and electric sinusoids (30 Hz) were shifted in relative phase (0-270 degrees). For all experimental conditions, the levels of the two stimuli were changed systematically. Responses were recorded in the contralateral central nucleus of the inferior colliculus. Single neuron analyses of spike rate and thresholds demonstrated that combined EAS resulted in complex interactions that were strongly dependent on the relative level of the given stimulus modes. The amount of masking increased with masker level and decreased with probe level. At higher current levels, the masking effect of electric responses dominated the effect of acoustic responses. The degree of these general masking effects was highly influenced by the relative phase between the combined stimuli. It seems likely that such interactions of combined stimulation have perceptual consequences in human cochlear implant subjects with residual hearing.
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Chen Z, Yu D, Feng Y, Su K, Wang J, Yin S. Off-channel effect of high-frequency overstimulation on duration tuning of low-frequency inferior colliculus neurons in guinea pigs. Acta Otolaryngol 2009; 129:1451-5. [PMID: 19922096 DOI: 10.3109/00016480902856562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION High-frequency overstimulation can cause the loss of duration selectivity in low-frequency inferior colliculus neurons in guinea pigs. OBJECTIVE To investigate the effect of high-frequency overstimulation on duration tuning in low-frequency inferior colliculus neurons in guinea pigs. MATERIALS AND METHODS Duration tuning pattern was recorded by measuring the spikes of single neurons in response to the best frequency (BF) of different durations. The effect of high-frequency overstimulation was verified by comparing the responses before and after the tone exposure. RESULTS In total, 40 duration-tuned neurons were successfully recorded before and after the tone exposure. After the high-frequency tone trauma, a total of 29 neurons (72.5%) became non-duration-tuned.
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Affiliation(s)
- Zhengnong Chen
- Institute of Otolaryngology, Shanghai JiaoTong University, Shanghai, China
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26
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Dror V, Eliash S, Rehavi M, Assaf Y, Biton IE, Fattal-Valevski A. Neurodegeneration in thiamine deficient rats-A longitudinal MRI study. Brain Res 2009; 1308:176-84. [PMID: 19857469 DOI: 10.1016/j.brainres.2009.10.032] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 10/13/2009] [Accepted: 10/14/2009] [Indexed: 11/19/2022]
Abstract
Selective neurodegeneration accompanied by mitochondrial dysfunction characterizes neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Thiamine deficiency (TD) in rats is a model for the study of cellular and molecular mechanisms that lead to selective neuronal loss caused by chronic oxidative deficits. Neurodegeneration in TD-rats develops over a period of 12 to 14 days and can be partially reversed by thiamine administration. The aim of this study was to characterize the in-vivo progression of neurodegeneration and the neuronal rescue processes in TD using T(2) magnetic resonance mapping and diffusion tensor imaging (DTI). Each rat was scanned prior to TD induction (day 0), before the appearance of neurological symptoms (day 10), during the symptomatic stage (days 12 and 14) and during the recuperation period (days 31 and 87). Time-dependent lesions were revealed mainly in the thalamus and the inferior colliculi. Early decrease in the fractional anisotropy (FA) was found on day 10 in the inferior colliculi and to a lesser degree in the thalamus, while the earliest detectable changes in the T(2) parameter occurred only on day 12. FA values in the thalamus remained significantly low after thiamine restoration, suggesting irreversible disarrangement and replacement of neuronal structures. While T(2) values in the frontal cortex demonstrated no lesions, FA values significantly increased on days 14 and 31. An enlargement of the lateral ventricles was observed and persevered during the recovery period. This longitudinal MRI study demonstrated that in TD MRI can detect neurodegeneration and neuronal recovery. DTI is more sensitive than T(2) mapping in the early detection of TD lesions.
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Affiliation(s)
- Vered Dror
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel
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27
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Abstract
The auditory midbrain implant (AMI) is a new hearing prosthesis designed for stimulation of the inferior colliculus in deaf patients who cannot sufficiently benefit from cochlear implants. The authors have begun clinical trials in which five patients have been implanted with a single shank AMI array (20 electrodes). The goal of this review is to summarize the development and research that has led to the translation of the AMI from a concept into the first patients. This study presents the rationale and design concept for the AMI as well a summary of the animal safety and feasibility studies that were required for clinical approval. The authors also present the initial surgical, psychophysical, and speech results from the first three implanted patients. Overall, the results have been encouraging in terms of the safety and functionality of the implant. All patients obtain improvements in hearing capabilities on a daily basis. However, performance varies dramatically across patients depending on the implant location within the midbrain with the best performer still not able to achieve open set speech perception without lip-reading cues. Stimulation of the auditory midbrain provides a wide range of level, spectral, and temporal cues, all of which are important for speech understanding, but they do not appear to sufficiently fuse together to enable open set speech perception with the currently used stimulation strategies. Finally, several issues and hypotheses for why current patients obtain limited speech perception along with several feasible solutions for improving AMI implementation are presented.
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Affiliation(s)
- Hubert H Lim
- Department of Biomedical Engineering, University of Minnesota, Minneapolis.
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28
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Melcher JR, Levine RA, Bergevin C, Norris B. The auditory midbrain of people with tinnitus: abnormal sound-evoked activity revisited. Hear Res 2009; 257:63-74. [PMID: 19699287 DOI: 10.1016/j.heares.2009.08.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 07/24/2009] [Accepted: 08/05/2009] [Indexed: 11/19/2022]
Abstract
Sound-evoked fMRI activation of the inferior colliculi (IC) was compared between tinnitus and non-tinnitus subjects matched in threshold (normal), age, depression, and anxiety. Subjects were stimulated with broadband sound in an "on/off" fMRI paradigm with and without on-going sound from the scanner coolant pump. (1) With pump sounds off, the tinnitus group showed greater stimulus-evoked activation of the IC than the non-tinnitus group, suggesting abnormal gain within the auditory pathway of tinnitus subjects. (2) Having pump sounds on reduced activation in the tinnitus, but not the non-tinnitus group. This result suggests response saturation in tinnitus subjects, possibly occurring because abnormal gain increased response amplitude to an upper limit. (3) In contrast to Melcher et al. (2000), the ratio of activation between right and left IC did not differ significantly between tinnitus and non-tinnitus subjects or in a manner dependent on tinnitus laterality. However, new data from subjects imaged previously by Melcher et al. suggest a possible tinnitus subgroup with abnormally asymmetric function of the IC. The present and previous data together suggest elevated responses to sound in the IC are common among those with tinnitus and normal thresholds, while abnormally asymmetric activation is not, even among those with lateralized tinnitus.
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Affiliation(s)
- Jennifer R Melcher
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.
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29
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N'Gouemo P, Yasuda RP, Faingold CL. Protein expression of small conductance calcium-activated potassium channels is altered in inferior colliculus neurons of the genetically epilepsy-prone rat. Brain Res 2009; 1270:107-11. [PMID: 19254702 PMCID: PMC2697038 DOI: 10.1016/j.brainres.2009.02.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 02/06/2009] [Accepted: 02/13/2009] [Indexed: 11/28/2022]
Abstract
The genetically epilepsy-prone rat (GEPR) exhibits inherited predisposition to sound stimuli-induced generalized tonic-clonic seizures (audiogenic reflex seizures) and is a valid model to study the physiopathology of epilepsy. In this model, the inferior colliculus (IC) exhibits enhanced neuronal firing that is critical in the initiation of reflex audiogenic seizures. The mechanisms underlying IC neuronal hyperexcitability that leads to seizure susceptibility are not as yet fully understood. The present report shows that the levels of protein expression of SK1 and SK3 subtypes of the small conductance Ca2+-activated K+ channels were significantly decreased, while SK2 channel proteins were increased in IC neurons of seizure-naive GEPR-3s (SN-GEPR-3), as compared to control Sprague-Dawley rats. No significant change was found in the expression of BK channel proteins in IC neurons of SN-GEPR-3s. Single episode of reflex audiogenic seizures in the GEPR-3s did not significantly alter the protein expression of SK1-3 and BK channels in IC neurons compared to SN-GEPR-3s. Thus, downregulation of SK1 and SK3 channels and upregulation of SK2 channels provide direct evidence that these Ca2+-activated K+ channels play important roles in IC neuronal hyperexcitability that leads to inherited seizure susceptibility in the GEPR.
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Affiliation(s)
- Prosper N'Gouemo
- Department of Pediatrics, Bldg D, Room 285, Georgetown University Medical Center, 3900 Reservoir Rd, NW, Washington, DC 20057, USA.
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30
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Song HY, Tong Z, Wang YM, Qian SJ, Guo RX, Shi JR. [Effect of electrical stimulation of the primary auditory cortex on the spontaneous activities of the external nucleus of the inferior colliculus in a rat model of tinnitus induced by salicylate acid.]. Sheng Li Xue Bao 2009; 61:121-126. [PMID: 19377822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This study aims to investigate corticofugal modulation on spontaneous activities of the external nucleus of the inferior colliculus (ICx) in a salicylate acid (SA) induced tinnitus rat model by the stimulation of the primary auditory cortex (AI). Extracellular recording techniques and stereotaxic method were used. The spontaneous activities of a single unit were recorded from the left ICx after electrical stimulation was given to the left AI of the rats duplicated as acute SA models. The average rate of spontaneous discharge and the interspike interval histogram of spontaneous activities were used as indices. The single unit spontaneous discharges of the same unit of ICx before and after AI stimulation were observed. There was an inhibitory effect of AI stimulation on the activities of the high discharge unit [(8.75+/-2.70) Hz vs (5.06+/-2.01) Hz] and a facilitatory effect on the low discharge unit [(1.41+/-0.45) Hz vs (2.46+/-0.79) Hz]. In the normal group, there was a restraining effect on the average rate of spontaneous discharge of the ICx after AI stimulation. The average rate of spontaneous discharge changed from (3.66+/-0.84) Hz to (2.47+/-0.43) Hz in the first hour after AI stimulation and then recovered within 2-4 h. And the discharge rate of the spike interval within 0-20 ms decreased (17% vs 7.3%, 11.2%) in the first 2 h and recovered 3-4 h after AI stimulation. The discharge rate of the spike interval within 0-6 ms (short interval) recovered 2 h after AI stimulation. In the acute SA model group, the average rate of spontaneous discharge recorded from the ICx decreased from (7.48+/-0.85) Hz to (3.38+/-0.39) Hz in the first hour after AI stimulation and the suppression effect remained 4 h (P<0.05). There was no difference in the average rate of spontaneous discharge between the acute SA model group and the normal group at 2-4 h after AI stimulation. The suppression effect after AI stimulation on the 0-20 ms interval spikes in the ICx lasted 4 h, while that on the shorter interval (0-6 ms) spikes recovered in the 3rd hour after AI stimulation in acute SA model group. It is concluded that the high average spontaneous discharge rate of ICx in acute SA model decreases significantly by AI stimulation, and the suppression effects on the shorter interval spikes recovers in the 3rd hour after AI stimulation. It might be inferred that stimulation of AI, through exciting the auditory descending projections, could remit the increased spontaneous discharge of ICx induced by SA that may relate with tinnitus in a period of time.
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Affiliation(s)
- Hai-Yan Song
- Experiment Center for Science and Technology, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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31
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Abstract
Recently, we characterized the more severe nature of hearing loss in aged Type 2 diabetic human subjects [Frisina, S.T., Mapes, F., Kim, S., Frisina, D.R., Frisina, R.D., 2006. Characterization of hearing loss in aged type II diabetics. Hear. Res. 211, 103-113]. The current study prospectively assessed hearing abilities in middle age CBA/CaJ mice with Type 1 diabetes mellitus (T1DM) (STZ injection) or Type 2 diabetes mellitus (T2DM) (high fat diet), for a period of 6 months. Blood glucose, body weight and auditory tests (Auditory Brainstem Response-ABR, Distortion Product Otoacoustic Emissions-DPOAE) were evaluated at baseline and every 2 months. Tone and broad-band noise-burst responses in the inferior colliculus were obtained at 6 months. Body weights of controls did not change over 6 months (approximately 32 g), but there was a significant (approximately 5 g) decline in the T1DM, while T2DM exhibited approximately 10 g weight gain. Blood glucose levels significantly increased: 3-fold for T1DM, 1.3-fold for T2DM; with no significant changes in controls. ABR threshold elevations were found for both types of diabetes, but were most pronounced in the T2DM, starting as early as 2 months after induction of diabetes. A decline of mean DPOAE amplitudes was observed in both diabetic groups at high frequencies, and for the T2DM at low frequencies. In contrast to ABR thresholds, tone and noise thresholds in the inferior colliculus were lower for both diabetic groups. Induction of diabetes in middle-aged CBA/CaJ mice promotes amplification of age-related peripheral hearing loss which makes it a suitable model for studying the interaction of age-related hearing loss and diabetes. On the other hand, initial results of effects from very high blood glucose level (T1DM) on the auditory midbrain showed disruption of central inhibition, increased response synchrony or enhanced excitation in the inferior colliculus.
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Affiliation(s)
- Olga N Vasilyeva
- Otolaryngology Department, University of Rochester Medical School & Dentistry, 601 Elmwood Ave., Rochester, NY 14642-8629, USA
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32
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Abstract
PURPOSE This review outlines the anatomical and functional bases of somatosensory influences on auditory processing in the normal brainstem and midbrain. It then explores how interactions between the auditory and somatosensory system are modified through deafness, and their impact on tinnitus is discussed. METHOD Literature review, tract tracing, immunohistochemistry, and in vivo electrophysiological recordings were used. RESULTS Somatosensory input originates in the dorsal root ganglia and trigeminal ganglia, and is transmitted directly and indirectly through 2nd-order nuclei to the ventral cochlear nucleus, dorsal cochlear nucleus (DCN), and inferior colliculus. The glutamatergic somatosensory afferents can be segregated from auditory nerve inputs by the type of vesicular glutamate transporters present in their terminals. Electrical stimulation of the somatosensory input results in a complex combination of excitation and inhibition, and alters the rate and timing of responses to acoustic stimulation. Deafness increases the spontaneous rates of those neurons that receive excitatory somatosensory input and results in a greater sensitivity of DCN neurons to trigeminal stimulation. CONCLUSIONS Auditory-somatosensory bimodal integration is already present in 1st-order auditory nuclei. The balance of excitation and inhibition elicited by somatosensory input is altered following deafness. The increase in somatosensory influence on auditory neurons when their auditory input is diminished could be due to cross-modal reinnervation or increased synaptic strength, and may contribute to mechanisms underlying somatic tinnitus.
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Affiliation(s)
- S Dehmel
- Kresge Hearing Research Institute, 1150 West Medical Center Drive, Room 5434A, Ann Arbor, MI 48109-5616, USA
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33
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Lenhardt ML. Tinnitus: a philosophical problem. Int Tinnitus J 2008; 14:37-41. [PMID: 18616085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Anatomical, physiological and metabolic properties of tinnitus have been identified and a comprehensive theory is immerging. The key elements and their interaction are presented in a general fashion highlighting areas of concern such as needed details of individual biosusceptibility and the need for continued tinnitus modeling for predictions as an aid in the development of effective treatment modalities. Nonetheless, there remains something of the uniqueness of tinnitus as a personal experience. The use of the final common pathway (FCP) as a unifying principle in diagnosis and treatment is presented.
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Vollmer M, Beitel RE, Snyder RL, Leake PA. Spatial selectivity to intracochlear electrical stimulation in the inferior colliculus is degraded after long-term deafness in cats. J Neurophysiol 2007; 98:2588-603. [PMID: 17855592 PMCID: PMC2430866 DOI: 10.1152/jn.00011.2007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In an animal model of electrical hearing in prelingually deaf adults, this study examined the effects of deafness duration on response thresholds and spatial selectivity (i.e., cochleotopic organization, spatial tuning and dynamic range) in the central auditory system to intracochlear electrical stimulation. Electrically evoked auditory brain stem response (EABR) thresholds and neural response thresholds in the external (ICX) and central (ICC) nuclei of the inferior colliculus were estimated in cats after varying durations of neonatally induced deafness: in animals deafened <1.5 yr (short-deafened unstimulated, SDU cats) with a mean spiral ganglion cell (SGC) density of approximately 45% of normal and in animals deafened >2.5 yr (long-deafened, LD cats) with severe cochlear pathology (mean SGC density <7% of normal). LD animals were subdivided into unstimulated cats and those that received chronic intracochlear electrical stimulation via a feline cochlear implant. Acutely deafened, implanted adult cats served as controls. Independent of their stimulation history, LD animals had significantly higher EABR and ICC thresholds than SDU and control animals. Moreover, the spread of electrical excitation was significantly broader and the dynamic range significantly reduced in LD animals. Despite the prolonged durations of deafness the fundamental cochleotopic organization was maintained in both the ICX and the ICC of LD animals. There was no difference between SDU and control cats in any of the response properties tested. These findings suggest that long-term auditory deprivation results in a significant and possibly irreversible degradation of response thresholds and spatial selectivity to intracochlear electrical stimulation in the auditory midbrain.
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Affiliation(s)
- Maike Vollmer
- Department of Otolaryngology, Head and Neck Surgery, University Hospital Würzburg, Germany.
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35
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Xie HS, Song WM, Shangguan DH, Li XP, Wang W, Wang L, Zhu L. [Level of glutamate on the auditory pathway of inferior colliculus after exposure to noise observed by microdialysis in vivo]. Beijing Da Xue Xue Bao Yi Xue Ban 2007; 39:409-11. [PMID: 17657270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
OBJECTIVE To explore the quality and quantity of glutamate(Glu) on the auditory pathway of inferior colliculus when exposed to conditioning noise or traumatic sound to find the relationship between the change of neurotransmitters and the protection of hearing, and the mechanism in the phenomena. METHODS Twenty Sprague-Dawley rats were divided into four groups: control group, conditioning group, intensive noise group and combining group. The hearing function was measured by ABR. Glu was detected by microdialysis and HPLC. RESULTS The ABR levels after exposure were (47.0+/-2.7) dB SPL (intensive noise group ),(31.0+/-2.2) dB SPL (conditioning group ) and (36.0+/-2.2) dB SPL (combining group ).The levels of Glu were (310.5+/-78.5)x 10(-7)mol/L (intense noise group ),(162.9+/-64.1)x10(-7)mol/L (conditioning group ); (113.6+/-38.1)x10(-7)mol/L (combining group),(56.3+/-23.9)x10(-7)mol/L (control group). CONCLUSION The level of Glu on the auditory pathway of inferior colliculus was higher when exposed to noise . Glu was exhausted when given conditioning sound, and the level of Glu was lower when given following intense noise. High level of Glu can damage hearing, so exhaustion of Glu in sound condition may contribute to the protection.
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Affiliation(s)
- Hua Shun Xie
- Department of Otorhinolaryngology Head and Neck Surgery, Peking University Third hospital, Beijing 100083, China
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36
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Cui Y, Holt AG, Lomax CA, Altschuler RA. Deafness associated changes in two-pore domain potassium channels in the rat inferior colliculus. Neuroscience 2007; 149:421-33. [PMID: 17884299 PMCID: PMC2699593 DOI: 10.1016/j.neuroscience.2007.05.054] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 05/22/2007] [Accepted: 05/30/2007] [Indexed: 11/15/2022]
Abstract
Two-pore potassium channels can influence neuronal excitability by regulating background leakage of potassium ions and resting membrane potential. The present study used quantitative real time PCR and in situ hybridization to determine if the decreased activity from deafness would induce changes in two-pore potassium channel subunit expression in the rat inferior colliculus (IC). Ten subunits were assessed with quantitative real-time PCR at 3 days, 3 weeks and 3 months following bilateral cochlear ablation. TASK-1, TASK-5 and THIK-2 showed significant decreases in expression at all three times assessed. TASK-5, relatively specific to auditory neurons, had the greatest decrease. TWIK-1 was significantly decreased at 3 weeks and 3 months following deafness and TREK-2 was only significantly decreased at 3 days. TASK-3, TWIK-2, THIK-1, TRAAK and TREK-1 did not show any significant changes in gene expression. In situ hybridization was used to examine TASK-1, TASK-5, TWIK-1 and THIK-2 in the central nucleus, dorsal cortex and lateral (external) cortex of the IC in normal hearing animals and at 3 weeks following deafening. All four subunits showed expression in neurons throughout IC subdivisions in normal hearing rats, with TASK-5 having the greatest overall number of labeled neurons. There was no co-localization of subunit expression with glial fibrillary acidic protein immunostaining, indicating no expression in glia. Three weeks following deafening there was a significant decrease in the number of neurons expressing TASK-1 and THIK-2 in the IC, while TASK-5 had significant decreases in the central nucleus and dorsal cortex and TWIK-1 in the lateral and dorsal cortices.
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Affiliation(s)
- Yilei Cui
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109
| | - Avril G. Holt
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine
| | - Catherine A. Lomax
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109
| | - Richard A. Altschuler
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109
- Department of Cell and Developmental Biology, University of Michigan
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37
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Brozoski TJ, Ciobanu L, Bauer CA. Central neural activity in rats with tinnitus evaluated with manganese-enhanced magnetic resonance imaging (MEMRI). Hear Res 2007; 228:168-79. [PMID: 17382501 DOI: 10.1016/j.heares.2007.02.003] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 02/07/2007] [Accepted: 02/09/2007] [Indexed: 11/30/2022]
Abstract
The pathophysiology of tinnitus, the perception of sound in the absence of acoustic stimulation, is largely unknown, although several lines of research implicate long-term neuroplastic loss of inhibition. The evidence to date suggests that the neuroplastic alterations are likely to be found in multiple brain structures. The present study used manganese-enhanced magnetic resonance imaging (MEMRI) to assess the pattern of neural activity in the central auditory pathway of rats with psychophysical evidence of chronic acoustic-exposure-induced tinnitus. Manganese, an activity-dependent paramagnetic contrast agent, accumulates in active neurons through voltage-gated calcium channels, primarily at synapses, and serves as both a structural and functional indicator. Comparison images were obtained from normal subjects exposed to external tinnitus-like sound, and from tinnitus subjects treated with vigabatrin, a GABA agonist shown to eliminate the psychophysical evidence of tinnitus in rats. MEMRI indicated: (1) In rats with evidence of tinnitus, activity was generally elevated in the auditory brainstem, with significant elevation in the cerebellar paraflocculus, the posterior ventral cochlear nucleus, and the inferior colliculus; in general forebrain structures showed decreased activity, although MEMRI may be a less sensitive indicator of forebrain activity than brainstem activity; (2) in normal rats exposed to a tinnitus-like sound, a similar pattern of elevated brainstem activity and decreased forebrain activity was evident, with the notable exception of the paraflocculus, where artificial tinnitus had no effect and (3) vigabatrin, decreased brainstem activity to control levels, in rats with prior evidence of tinnitus, and decreased forebrain activity to below control levels. It was concluded that chronic tinnitus in rats is associated with focal activity elevation in the auditory brainstem and increased activity in the paraflocculus that may be unique to tinnitus.
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Affiliation(s)
- Thomas J Brozoski
- Division of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL 62794-9629, USA.
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38
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Barsz K, Wilson WW, Walton JP. Reorganization of receptive fields following hearing loss in inferior colliculus neurons. Neuroscience 2007; 147:532-45. [PMID: 17540507 PMCID: PMC2614669 DOI: 10.1016/j.neuroscience.2007.04.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 04/02/2007] [Accepted: 04/16/2007] [Indexed: 11/28/2022]
Abstract
We explored frequency and intensity encoding in the inferior colliculus (IC) of the C57 mouse model of sensorineural hearing loss. Consistent with plasticity reported in the IC of other models of hearing loss, frequency response areas (FRAs) in hearing-impaired (HI) mice were broader with fewer high-frequency units than normal-hearing (NH) mice. The broad FRAs recorded from HI mice had lower cutoffs on the low frequency edge of the FRA. Characteristic frequency (CF) and sharpness of tuning (Q10) calculated from the FRA were used to divide the sample into four categories: low-CF sharp-FRA, low-CF broad-FRA, high-CF sharp-FRA, and high-CF broad-FRA units. Rate-intensity functions (RIFs) for CF tones and noise were used to determine the minimum and maximum response counts as well as the sound pressure levels resulting in 10%, 50%, and 90% of the maximum spike count. Tone RIFs of broad FRA units were shifted to the right of tone RIFs of sharp FRA units in both NH and HI mouse IC, regardless of the unit CF. The main effects of hearing loss were seen in the noise RIFs. The low-CF broad-FRA units in HI mice had elevated responses to noise, and the high-CF sharp-FRA units in HI mice had lower maximum rates, as compared with the units recorded from NH mice. These results suggest that, as the IC responds to peripheral hearing loss with changes in the representation of frequency, an altered balance between inhibitory and excitatory inputs to the neurons recorded from the HI mice alters aspects of the units' intensity encoding. This altered balance likely occurs, at least in part, outside of the IC.
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Affiliation(s)
- K Barsz
- Department of Otolaryngology and Neurobiology and Anatomy, University of Rochester Medical School, Rochester, NY 14642, USA
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39
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Felix RA, Portfors CV. Excitatory, inhibitory and facilitatory frequency response areas in the inferior colliculus of hearing impaired mice. Hear Res 2007; 228:212-29. [PMID: 17412539 PMCID: PMC1950695 DOI: 10.1016/j.heares.2007.02.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 02/26/2007] [Accepted: 02/26/2007] [Indexed: 11/24/2022]
Abstract
Individuals with age-related hearing loss often have difficulty understanding complex sounds such as basic speech. The C57BL/6 mouse suffers from progressive sensorineural hearing loss and thus is an effective tool for dissecting the neural mechanisms underlying changes in complex sound processing observed in humans. Neural mechanisms important for processing complex sounds include multiple tuning and combination sensitivity, and these responses are common in the inferior colliculus (IC) of normal hearing mice. We examined neural responses in the IC of C57Bl/6 mice to single and combinations of tones to examine the extent of spectral integration in the IC after age-related high frequency hearing loss. Ten percent of the neurons were tuned to multiple frequency bands and an additional 10% displayed non-linear facilitation to the combination of two different tones (combination sensitivity). No combination-sensitive inhibition was observed. By comparing these findings to spectral integration properties in the IC of normal hearing CBA/CaJ mice, we suggest that high frequency hearing loss affects some of the neural mechanisms in the IC that underlie the processing of complex sounds. The loss of spectral integration properties in the IC during aging likely impairs the central auditory system's ability to process complex sounds such as speech.
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Affiliation(s)
- Richard A Felix
- School of Biological Sciences, Washington State University, 14204 NE Salmon Creek Avenue, Vancouver, WA 98686, United States
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40
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Bielefeld EC, Henderson D. Influence of sympathetic fibers on noise-induced hearing loss in the chinchilla. Hear Res 2007; 223:11-9. [PMID: 17092669 DOI: 10.1016/j.heares.2006.09.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 09/25/2006] [Accepted: 09/26/2006] [Indexed: 11/16/2022]
Abstract
The influence of the sympathetic efferent fibers on cochlear susceptibility to noise-induced hearing loss is still an open question. In the current study, we explore the effects of unilateral and bilateral Superior Cervical Ganglion (SCG) ablation in the chinchilla on hearing loss from noise exposure, as measured with inferior colliculus (IC) evoked potentials, distortion product otoacoustic emissions (DPOAE), and outer hair cell (OHC) loss. The SCG was isolated at the level of the bifurcation of the carotid artery and removed unilaterally in 15 chinchillas. Another eight chinchillas underwent bilateral ablation. Twelve animals were employed as sham controls. Noise exposure was a 4kHz octave band noise for 1h at 110dB SPL. Results showed improved recovery of DPOAE amplitudes after noise exposure in ears that underwent SCGectomy, as well as lower evoked potential threshold shifts relative to sham controls. Effects of SCGectomy on OHC loss were small. Results of the study suggest that sympathetic fibers do exert some influence on susceptibility to noise, but the influence may not be a major one.
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Affiliation(s)
- Eric C Bielefeld
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, United States.
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41
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Tadros SF, D’Souza M, Zettel ML, Zhu X, Frisina RD. Glutamate-related gene expression changes with age in the mouse auditory midbrain. Brain Res 2006; 1127:1-9. [PMID: 17113045 PMCID: PMC2423939 DOI: 10.1016/j.brainres.2006.09.081] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 09/18/2006] [Accepted: 09/25/2006] [Indexed: 01/01/2023]
Abstract
Glutamate is the main excitatory neurotransmitter in both the peripheral and central auditory systems. Changes of glutamate and glutamate-related genes with age may be an important factor in the pathogenesis of age-related hearing loss-presbycusis. In this study, changes in glutamate-related mRNA gene expression in the CBA mouse inferior colliculus with age and hearing loss were examined and correlations were sought between these changes and functional hearing measures, such as the auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs). Gene expression of 68 glutamate-related genes was investigated using both genechip microarray and real-time PCR (qPCR) molecular techniques for four different age/hearing loss CBA mouse subject groups. Two genes showed consistent differences between groups for both the genechip and qPCR. Pyrroline-5-carboxylate synthetase enzyme (Pycs) showed down-regulation with age and a high-affinity glutamate transporter (Slc1a3) showed up-regulation with age and hearing loss. Since Pycs plays a role in converting glutamate to proline, its deficiency in old age may lead to both glutamate increases and proline deficiencies in the auditory midbrain, playing a role in the subsequent inducement of glutamate toxicity and loss of proline neuroprotective effects. The up-regulation of Slc1a3 gene expression may reflect a cellular compensatory mechanism to protect against age-related glutamate or calcium excitoxicity.
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Affiliation(s)
- Sherif F. Tadros
- Department of Otolaryngology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester NY, 14642-8629, USA
- International Center for Hearing & Speech Research, National Technical Institute for the Deaf, Rochester Institute of Technology, 52 Lomb Memorial Drive, Rochester NY, 14623, USA
| | - Mary D’Souza
- Department of Otolaryngology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester NY, 14642-8629, USA
- International Center for Hearing & Speech Research, National Technical Institute for the Deaf, Rochester Institute of Technology, 52 Lomb Memorial Drive, Rochester NY, 14623, USA
| | - Martha L. Zettel
- Department of Otolaryngology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester NY, 14642-8629, USA
- International Center for Hearing & Speech Research, National Technical Institute for the Deaf, Rochester Institute of Technology, 52 Lomb Memorial Drive, Rochester NY, 14623, USA
| | - XiaoXia Zhu
- Department of Otolaryngology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester NY, 14642-8629, USA
- International Center for Hearing & Speech Research, National Technical Institute for the Deaf, Rochester Institute of Technology, 52 Lomb Memorial Drive, Rochester NY, 14623, USA
| | - Robert D. Frisina
- Department of Otolaryngology, University of Rochester School of Medicine & Dentistry, 601 Elmwood Avenue, Rochester NY, 14642-8629, USA
- International Center for Hearing & Speech Research, National Technical Institute for the Deaf, Rochester Institute of Technology, 52 Lomb Memorial Drive, Rochester NY, 14623, USA
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Calvo F, Coimbra NC. Interactions between opioid-peptides-containing pathways and GABAA-receptors-mediated systems modulate panic-like-induced behaviors elicited by electric and chemical stimulation of the inferior colliculus. Brain Res 2006; 1104:92-102. [PMID: 16797498 DOI: 10.1016/j.brainres.2006.05.056] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 05/09/2006] [Accepted: 05/19/2006] [Indexed: 10/24/2022]
Abstract
Aiming to clarify the effect of interactive interconnections between the endogenous opioid peptides-neural links and GABAergic pathways on panic-like responses, in the present work, the effect of the peripheral and central administration of morphine or the non-specific opioid receptors antagonist naloxone was evaluated on the fear-induced responses (defensive attention, defensive immobility and escape behavior) elicited by electric and chemical stimulation of the inferior colliculus. Central microinjections of opioid drugs in the inferior colliculus were also performed followed by local administration of the GABA(A)-receptor antagonist bicuculline. The defensive behavior elicited by the blockade of GABAergic receptors in the inferior colliculus had been quantitatively analyzed, recording the number of crossing, jump, rotation and rearing, in each minute, during 30 min, in the open-field test. The opioid receptors stimulation with morphine decreased the defensive attention, the defensive immobility and escape behavior thresholds, and the non-specific opioid receptors blockade caused opposite effects, enhancing the defensive behavior thresholds. These effects were corroborated by either the stimulation or the inhibition of opioid receptors followed by the GABA(A) receptor blockade with bicuculline, microinjected into the inferior colliculus. There was a significant increase in the diverse fear-induced responses caused by bicuculline with the pretreatment of the inferior colliculus with morphine, and the opposite effect was recorded after the pretreatment of the inferior colliculus nuclei with naloxone followed by bicuculline local administration. These findings suggest an interaction between endogenous opioid-peptides-containing connections and GABA(A)-receptor-mediated system with direct influence on the organization of the panic-like or fear-induced responses elaborated in the inferior colliculus during critical emotional states.
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Affiliation(s)
- Fabrício Calvo
- Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, School of Medicine of Ribeirão Preto of the University of São Paulo (FMRP-USP), Av. dos Bandeirantes, 3900, Ribeirão Preto (SP), 1049-900, Brazil
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N'Gouemo P, Yasuda RP, Morad M. Ethanol withdrawal is accompanied by downregulation of calcium channel alpha 1B subunit in rat inferior colliculus neurons. Brain Res 2006; 1108:216-20. [PMID: 16860782 DOI: 10.1016/j.brainres.2006.06.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Revised: 06/08/2006] [Accepted: 06/10/2006] [Indexed: 11/19/2022]
Abstract
Ethanol withdrawal enhances the current density of calcium (Ca(2+)) channels in inferior colliculus (IC) neurons. The present report shows that ethanol withdrawal markedly enhanced the susceptibility to seizures as it decreased significantly the protein levels of alpha(1B) subunit associated with N-type Ca(2+) channel in IC neurons of animals not tested for seizures. Thus, remodeling of N-type Ca(2+) channels may play an important role in neuronal hyperexcitability that leads to ethanol withdrawal seizures.
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Affiliation(s)
- Prosper N'Gouemo
- Department of Pediatrics, Georgetown University Medical Center, Washington, DC 20057, USA.
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Wissel K, Wefstaedt P, Rieger H, Miller JM, Lenarz T, Stöver T. Upregulation of glial cell line-derived neurotrophic factor and artemin mRNA in the auditory nerve of deafened rats. Neuroreport 2006; 17:875-8. [PMID: 16738479 DOI: 10.1097/01.wnr.0000221836.26093.85] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Nerve growth factors play key roles in spiral ganglion cells survival and excitability. Our aim was to determine gene expression patterns of glial cell line-derived neurotrophic factor family (GDNF) members and their receptors in the auditory nerve and inferior colliculus of deafened rats. The gene expression of GDNF, persephin, artemin and neurturin, and their receptors GFRalpha1, GFRalpha2, GFRalpha3 and Ret, was determined by semiquantitative reverse transcriptase-polymerase chain reaction using GAPDH expression as an internal standard. Following deafness, no significant changes in expression of GDNF family genes were found in inferior colliculus. In contrast, artemin, GDNF, GFRalpha1-3 and Ret RNA expression were strongly upregulated in the auditory nerve following deafness, indicating their importance in protecting the auditory nerve against cell damage.
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Affiliation(s)
- Kirsten Wissel
- Department of Otolaryngology, Medical University of Hannover, Hannover, Germany
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Abstract
Presbycusis - age-related hearing loss - is a key communication disorder and chronic medical condition of our aged population. The cochlear nucleus is the major site of projections from the auditory portion of the inner ear. Relative to other levels of the peripheral and central auditory systems, relatively few studies have been conducted examining age-related changes in the cochlear nucleus. The neurophysiological investigations suggest declines in glycine-mediated inhibition, reflected in increased firing rates in cochlear nucleus neurons from old animals relative to young adults. Biochemical investigations of glycine inhibition in the cochlear nucleus are consistent with the functional aging declines of this inhibitory neurotransmitter system that affect complex sound processing. Anatomical reductions in neurons of the cochlear nucleus and their output pathways can occur due to aging changes in the brain, as well as due to age-dependent plasticity of the cochlear nucleus in response to the age-related loss of inputs from the cochlea, particularly from the basal, high-frequency regions. Novel preventative and curative biomedical interventions in the future aimed at alleviating the hearing loss that comes with age, will likely emanate from increasing our knowledge and understanding of its neural and molecular bases. To the extent that this sensory deficit resides in the central auditory system, including the cochlear nucleus, future neural therapies will be able to improve hearing in the elderly.
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Affiliation(s)
- Robert D Frisina
- Otolaryngology Department, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642-8629, USA.
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Abstract
Several physiological studies have linked experimentally induced tinnitus to increases in the spontaneous activity of auditory neurons. These results have led to the proposal of hyperactivity models of tinnitus in which elevated neural activity in the absence of auditory stimulation is perceived as phantom sound. Such models are appealing in their simplicity but remain controversial because a generalized elevation of spontaneous rates may not be observed after treatments that induce tinnitus in humans and experimental animals. Our study addressed these issues by characterizing the effects of common methods of tinnitus induction on spontaneous activity in the central nucleus of the inferior colliculus (ICC). The ICC is an interesting structure in tinnitus research because its diverse inputs include putative generator sites in the dorsal cochlear nucleus, as well as brainstem sources that appear to remain normal after tinnitus induction. Groups of CBA/J mice were subjected to one of three induction methods: bilateral or unilateral sound exposure, and acute salicylate intoxication. Relative to normal baselines, bilaterally exposed mice showed increases in the spontaneous rates of neurons with tuning near the exposure frequency. When the sample was separated into physiologically defined response classes, exposure effects were strongest among neurons with broad excitatory bandwidths. By contrast, salicylate decreased the spontaneous rates of low-frequency neurons with transient sound-evoked activity. Our results suggest that the disordered processes of hearing that give rise to tinnitus do not involve a pervasive elevation of spontaneous activity or a single mode of induction.
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Affiliation(s)
- Wei-Li Diana Ma
- Center for Hearing and Balance, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, 720 Rutland Avenue, Baltimore, MD 21205, USA
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Laemle LK, Strominger NL, Carpenter DO. Cross-modal innervation of primary visual cortex by auditory fibers in congenitally anophthalmic mice. Neurosci Lett 2005; 396:108-12. [PMID: 16377089 DOI: 10.1016/j.neulet.2005.11.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 11/03/2005] [Accepted: 11/08/2005] [Indexed: 11/19/2022]
Abstract
Auditory-visual cross-modal innervation was examined in control (sighted, ZRDCT-N) and congenitally anophthalmic (eyeless, ZRDCT-AN) mice using electrophysiological recording and pathway tracing with carbocyanine dyes. Electrophysiological data demonstrate that the primary visual cortex of congenitally eyeless, blind, mice receives auditory stimuli. Neuroanatomical data demonstrate a direct connection between the inferior colliculus (IC) and visual cortex. Our experiments provide new information about how the brain adapts to the loss of sight.
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Affiliation(s)
- L K Laemle
- Department of Ophthalmology, UMDNJ-New Jersey Medical School, 30 Bergen Street, Rm. 1409, Newark, NJ 07103, USA.
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Cerrato P, Lentini A, Baima C, Grasso M, Azzaro C, Bosco G, Destefanis E, Benna P, Bergui M, Bergamasco B. Hypogeusia and hearing loss in a patient with an inferior collicular infarction. Neurology 2005; 65:1840-1. [PMID: 16344541 DOI: 10.1212/01.wnl.0000187083.90889.72] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- P Cerrato
- Department of Neuroscience, University of Turin, Italy
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50
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Abstract
To investigate the effects of the tinnitus inducer sodium salicylate on L-type voltage-gated calcium channels, we studied freshly dissociated inferior colliculus neurons of rats by the whole-cell voltage clamp method. Salicylate's blocking of L-type calcium channels was concentration dependent, and the IC(50) value of salicylate was estimated to be 1.99 mM. An amount of 1 mM salicylate significantly shifted the steady-state inactivation curve of L-type calcium channels about 9 mV in the hyperpolarizing direction and significantly delayed calcium channel recovery. Our results suggest that salicylate's blocking of L-type calcium channels may contribute to salicylate-induced tinnitus by decreasing GABA release in the inferior colliculus.
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Affiliation(s)
- Yanxing Liu
- Department of Neurobiology, Hebei Medical University, No. 361 Zhongshan East Road, Changan District, Shijiazhuang 050017, PR China.
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