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Jimoh Z, Marouf A, Zenke J, Leung AWS, Gomaa NA. Functional Brain Regions Linked to Tinnitus Pathology and Compensation During Task Performance: A Systematic Review. Otolaryngol Head Neck Surg 2023; 169:1409-1423. [PMID: 37522290 DOI: 10.1002/ohn.459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 06/24/2023] [Accepted: 07/11/2023] [Indexed: 08/01/2023]
Abstract
OBJECTIVE To systematically search the literature and organize relevant advancements in the connection between tinnitus and the activity of different functional brain regions using functional magnetic resonance imaging (fMRI). DATA SOURCES MEDLINE (OVID), EMBASE (OVID), CINAHL (EBSCO), Web of Science, ProQuest Dissertations & Theses Global, Cochrane Database of Systematic Reviews, and PROSPERO from inception to April 2022. REVIEW METHODS Studies with adult human subjects who suffer from tinnitus and underwent fMRI to relate specific regions of interest to tinnitus pathology or compensation were included. In addition, fMRI had to be performed with a paradigm of stimuli that would stimulate auditory brain activity. Exclusion criteria included non-English studies, animal studies, and studies that utilized a resting state magnetic resonance imaging or other imaging modalities. RESULTS The auditory cortex may work to dampen the effects of central gain. Results from different studies show variable changes in the Heschl's gyrus (HG), with some showing increased activity and others showing inhibition and volume loss. After controlling for hyperacusis and other confounders, tinnitus does not seem to influence the inferior colliculus (IC) activation. However, there is decreased connectivity between the auditory cortex and IC. The cochlear nucleus (CN) generally shows increased activation in tinnitus patients. fMRI evidence indicates significant inhibition of thalamic gating. Activating the thalamus may be of important therapeutic potential. CONCLUSION Patients with tinnitus have significantly altered neuronal firing patterns, especially within the auditory network, when compared to individuals without tinnitus. Tinnitus and hyperacusis commonly coexist, making differentiation of the effects of these 2 phenomena frequently difficult.
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Affiliation(s)
- Zaharadeen Jimoh
- Faculty of Science, University of Alberta, Edmonton, Alberta, Canada
| | - Azmi Marouf
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve School of Medicine and University Hospitals Cleveland Medical Center, Cleveland, Ohio, USA
| | - Julianna Zenke
- Division of Otolaryngology-Head and Neck Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Ada W S Leung
- Department of Occupational Therapy, Neuroscience, and Mental Health Institute, Faculty of Rehabilitation Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Nahla A Gomaa
- Division of Otolaryngology-Head and Neck Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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2
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Focusing on the Emerging Role of Kainate Receptors in the Dorsal Cochlear Nucleus (DCN) and Cerebellum. Int J Mol Sci 2023; 24:ijms24021718. [PMID: 36675230 PMCID: PMC9865595 DOI: 10.3390/ijms24021718] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 12/31/2022] [Accepted: 01/04/2023] [Indexed: 01/17/2023] Open
Abstract
Mammals have a dorsal cochlear nucleus (DCN), which is thought to be a cerebellum-like structure with similar features in terms of structure and microcircuitry to the cerebellum. Both the DCN and cerebellum perform their functions depending on synaptic and neuronal networks mediated by various glutamate receptors. Kainate receptors (KARs) are one class of the glutamate receptor family and are strongly expressed in the hippocampus, the cerebellum, and cerebellum-like structures. The cellular distribution and the potential role of KARs in the hippocampus have been extensively investigated. However, the cellular distribution and the potential role of KARs in cerebellum-like structures, including the DCN and cerebellum, are poorly understood. In this review, we summarize the similarity between the DCN and cerebellum at the levels of structure, circuitry, and cell type as well as the investigations referring to the expression patterns of KARs in the DCN and cerebellum according to previous studies. Recent studies on the role of KARs have shown that KARs mediate a bidirectional modulatory effect at parallel fiber (PF)-Purkinje cell (PC) synapses in the cerebellum, implying insights into their roles in cerebellum-like structures, including the DCN, that remain to be explored in the coming years.
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Schilling A, Gerum R, Metzner C, Maier A, Krauss P. Intrinsic Noise Improves Speech Recognition in a Computational Model of the Auditory Pathway. Front Neurosci 2022; 16:908330. [PMID: 35757533 PMCID: PMC9215117 DOI: 10.3389/fnins.2022.908330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 05/09/2022] [Indexed: 01/05/2023] Open
Abstract
Noise is generally considered to harm information processing performance. However, in the context of stochastic resonance, noise has been shown to improve signal detection of weak sub- threshold signals, and it has been proposed that the brain might actively exploit this phenomenon. Especially within the auditory system, recent studies suggest that intrinsic noise plays a key role in signal processing and might even correspond to increased spontaneous neuronal firing rates observed in early processing stages of the auditory brain stem and cortex after hearing loss. Here we present a computational model of the auditory pathway based on a deep neural network, trained on speech recognition. We simulate different levels of hearing loss and investigate the effect of intrinsic noise. Remarkably, speech recognition after hearing loss actually improves with additional intrinsic noise. This surprising result indicates that intrinsic noise might not only play a crucial role in human auditory processing, but might even be beneficial for contemporary machine learning approaches.
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Affiliation(s)
- Achim Schilling
- Laboratory of Sensory and Cognitive Neuroscience, Aix-Marseille University, Marseille, France
- Neuroscience Lab, University Hospital Erlangen, Erlangen, Germany
- Cognitive Computational Neuroscience Group, Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Erlangen, Germany
| | - Richard Gerum
- Department of Physics and Center for Vision Research, York University, Toronto, ON, Canada
| | - Claus Metzner
- Neuroscience Lab, University Hospital Erlangen, Erlangen, Germany
- Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Erlangen, Germany
| | - Andreas Maier
- Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Erlangen, Germany
| | - Patrick Krauss
- Neuroscience Lab, University Hospital Erlangen, Erlangen, Germany
- Cognitive Computational Neuroscience Group, Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Erlangen, Germany
- Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Erlangen, Germany
- Linguistics Lab, Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Erlangen, Germany
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Malfatti T, Ciralli B, Hilscher MM, Leao RN, Leao KE. Decreasing dorsal cochlear nucleus activity ameliorates noise-induced tinnitus perception in mice. BMC Biol 2022; 20:102. [PMID: 35550106 PMCID: PMC9097071 DOI: 10.1186/s12915-022-01288-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 03/30/2022] [Indexed: 01/05/2023] Open
Abstract
Background The dorsal cochlear nucleus (DCN) is a region known to integrate somatosensory and auditory inputs and is identified as a potential key structure in the generation of phantom sound perception, especially noise-induced tinnitus. Yet, how altered homeostatic plasticity of the DCN induces and maintains the sensation of tinnitus is not clear. Here, we chemogenetically decrease activity of a subgroup of DCN neurons, Ca2+/Calmodulin kinase 2 α (CaMKII α)-positive DCN neurons, using Gi-coupled human M4 Designer Receptors Exclusively Activated by Designer Drugs (hM4Di DREADDs), to investigate their role in noise-induced tinnitus. Results Mice were exposed to loud noise (9–11kHz, 90dBSPL, 1h, followed by 2h of silence), and auditory brainstem responses (ABRs) and gap prepulse inhibition of acoustic startle (GPIAS) were recorded 2 days before and 2 weeks after noise exposure to identify animals with a significantly decreased inhibition of startle, indicating tinnitus but without permanent hearing loss. Neuronal activity of CaMKII α+ neurons expressing hM4Di in the DCN was lowered by administration of clozapine-N-oxide (CNO). We found that acutely decreasing firing rate of CaMKII α+ DCN units decrease tinnitus-like responses (p = 3e −3, n = 11 mice), compared to the control group that showed no improvement in GPIAS (control virus; CaMKII α-YFP + CNO, p = 0.696, n = 7 mice). Extracellular recordings confirmed CNO to decrease unit firing frequency of CaMKII α-hM4Di+ mice and alter best frequency and tuning width of response to sound. However, these effects were not seen if CNO had been previously administered during the noise exposure (n = 6 experimental and 6 control mice). Conclusion We found that lowering DCN activity in mice displaying tinnitus-related behavior reduces tinnitus, but lowering DCN activity during noise exposure does not prevent noise-induced tinnitus. Our results suggest that CaMKII α-positive cells in the DCN are not crucial for tinnitus induction but play a significant role in maintaining tinnitus perception in mice. Supplementary Information The online version contains supplementary material available at (10.1186/s12915-022-01288-1).
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Affiliation(s)
- Thawann Malfatti
- Hearing and Neuronal activity Lab, Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Barbara Ciralli
- Hearing and Neuronal activity Lab, Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Markus M Hilscher
- Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria
| | - Richardson N Leao
- Hearing and Neuronal activity Lab, Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Katarina E Leao
- Hearing and Neuronal activity Lab, Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil.
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Dotan A, Shriki O. Tinnitus-like "hallucinations" elicited by sensory deprivation in an entropy maximization recurrent neural network. PLoS Comput Biol 2021; 17:e1008664. [PMID: 34879061 PMCID: PMC8687580 DOI: 10.1371/journal.pcbi.1008664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 12/20/2021] [Accepted: 11/24/2021] [Indexed: 11/19/2022] Open
Abstract
Sensory deprivation has long been known to cause hallucinations or "phantom" sensations, the most common of which is tinnitus induced by hearing loss, affecting 10-20% of the population. An observable hearing loss, causing auditory sensory deprivation over a band of frequencies, is present in over 90% of people with tinnitus. Existing plasticity-based computational models for tinnitus are usually driven by homeostatic mechanisms, modeled to fit phenomenological findings. Here, we use an objective-driven learning algorithm to model an early auditory processing neuronal network, e.g., in the dorsal cochlear nucleus. The learning algorithm maximizes the network's output entropy by learning the feed-forward and recurrent interactions in the model. We show that the connectivity patterns and responses learned by the model display several hallmarks of early auditory neuronal networks. We further demonstrate that attenuation of peripheral inputs drives the recurrent network towards its critical point and transition into a tinnitus-like state. In this state, the network activity resembles responses to genuine inputs even in the absence of external stimulation, namely, it "hallucinates" auditory responses. These findings demonstrate how objective-driven plasticity mechanisms that normally act to optimize the network's input representation can also elicit pathologies such as tinnitus as a result of sensory deprivation.
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Affiliation(s)
- Aviv Dotan
- Department of Cognitive and Brain Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Oren Shriki
- Department of Cognitive and Brain Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Department of Computer Science, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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6
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Urbanek ME, Zuo J. Genetic predisposition to tinnitus in the UK Biobank population. Sci Rep 2021; 11:18150. [PMID: 34518561 PMCID: PMC8437971 DOI: 10.1038/s41598-021-97350-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 08/17/2021] [Indexed: 01/10/2023] Open
Abstract
Tinnitus, the phantom perception of noise originating from the inner ear, has been reported by 15% of the world's population, with many patients reporting major deficits to cognition and mood. However, both objective diagnostic tools and targeted therapeutic strategies have yet to be established. To better understand the underlying genes that may preclude tinnitus, we performed a genome-wide association study of the UK Biobank's 49,960 whole exome sequencing participants to identify any loci strongly associated with tinnitus. We identified 17 suggestive single nucleotide polymorphisms (p < 1e-5) spanning 13 genes in two sex-separated cohorts reporting chronic, bothersome tinnitus (control males n = 7,315, tinnitus males n = 226, control females n = 11,732, tinnitus females n = 300). We also found a significant missense mutation in WDPCP (p = 3.959e-10) in the female cohort, a mutation which has been previously implicated in typical neuronal functioning through axonal migration and structural reinforcement, as well as in Bardet-Biedl syndrome-15, a ciliopathy. Additionally, in situ hybridization in the embryonic and P56 mouse brain demonstrated that the majority of these genes are expressed within the dorsal cochlear nucleus, the region of the brain theorized to initially induce tinnitus. Further RT-qPCR and RNAScope data also reveals this expression pattern. The results of this study indicate that predisposition to tinnitus may span across multiple genomic loci and be established by weakened neuronal circuitry and maladaptive cytoskeletal modifications within the dorsal cochlear nucleus.
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Affiliation(s)
- Madeleine E Urbanek
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, USA.,Department of Biology, Creighton University College of Arts and Sciences, Omaha, NE, USA
| | - Jian Zuo
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, USA.
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7
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Saeed S, Khan QU. The Pathological Mechanisms and Treatments of Tinnitus. Discoveries (Craiova) 2021; 9:e137. [PMID: 35350720 PMCID: PMC8956333 DOI: 10.15190/d.2021.16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 09/21/2021] [Accepted: 09/30/2021] [Indexed: 11/22/2022] Open
Abstract
Tinnitus is defined as the ringing, hissing, clicking or roaring sounds an individual consciously perceives in the absence of an external auditory stimulus. Currently, the literature on the mechanism of tinnitus pathology is multifaceted, ranging from tinnitus generation at the cellular level to its perception at the system level. Cellular level mechanisms include increased neuronal synchrony, neurotransmission changes and maladaptive plasticity. At the system level, the role of auditory structures, non-auditory structures, changes in the functional connectivities in higher regions and tinnitus networks have been investigated. The exploration of all these mechanisms creates a holistic view on understanding the changes the pathophysiology of tinnitus undertakes. Although tinnitus percept may start at the level of cochlear nerve deafferentation, the neuronal changes in the central auditory system to the neuronal and connectivity changes in non-auditory regions, such as the limbic system, become cardinal in chronic tinnitus generation. At the present moment, some tinnitus generation mechanisms are well established (e.g., increased neuronal synchrony) whereas other mechanisms have gained more traction recently (e.g., tinnitus networks, tinnitus-distress networks) and therefore, require additional investigation to solidify their role in tinnitus pathology.
The treatments and therapeutics designed for tinnitus are numerous, with varied levels of success. They are generally two-fold: some treatments focus on tinnitus cessation (including cochlear implants, deep brain stimulation, transcranial direct current stimulation and transcranial magnetic stimulation) whereas the other set focuses on tinnitus reduction or masking (including hearing aids, sound therapy, cognitive behavioral therapy, tinnitus retraining therapy, and tailor made notched musical training). Tinnitus management has focused on implementing tinnitus masking/reducing therapies more than tinnitus cessation, since cessation treatments are still lacking in streamlined treatment protocols and long-term sustainability and efficacy of the treatment.
This review will focus on concisely exploring the current and most relevant tinnitus pathophysiology mechanisms, treatments and therapeutics.
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Affiliation(s)
- Sana Saeed
- CMH Lahore Medical College & Institute of Dentistry, Lahore, Pakistan
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8
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Ghosh S, Stansak K, Walters BJ. Cannabinoid Signaling in Auditory Function and Development. Front Mol Neurosci 2021; 14:678510. [PMID: 34079440 PMCID: PMC8165240 DOI: 10.3389/fnmol.2021.678510] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 04/15/2021] [Indexed: 12/20/2022] Open
Abstract
Plants of the genus Cannabis have been used by humans for millennia for a variety of purposes. Perhaps most notable is the use of certain Cannabis strains for their psychoactive effects. More recently, several biologically active molecules within the plants of these Cannabis strains, called phytocannabinoids or simply cannabinoids, have been identified. Furthermore, within human cells, endogenous cannabinoids, or endocannabinoids, as well as the receptors and secondary messengers that give rise to their neuromodulatory effects, have also been characterized. This endocannabinoid system (ECS) is composed of two primary ligands-anandamide and 2-arachidonyl glycerol; two primary receptors-cannabinoid receptors 1 and 2; and several enzymes involved in biosynthesis and degradation of endocannabinoid ligands including diacylglycerol lipase (DAGL) and monoacylglycerol lipase (MAGL). Here we briefly summarize cannabinoid signaling and review what has been discerned to date with regard to cannabinoid signaling in the auditory system and its roles in normal physiological function as well as pathological conditions. While much has been uncovered regarding cannabinoid signaling in the central nervous system, less attention has been paid to the auditory system specifically. Still, evidence is emerging to suggest that cannabinoid signaling is critical for the development, maturation, function, and survival of cochlear hair cells (HCs) and spiral ganglion neurons (SGNs). Furthermore, cannabinoid signaling can have profound effects on synaptic connectivity in CNS structures related to auditory processing. While clinical cases demonstrate that endogenous and exogenous cannabinoids impact auditory function, this review highlights several areas, such as SGN development, where more research is warranted.
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Affiliation(s)
- Sumana Ghosh
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, United States
| | - Kendra Stansak
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, United States
| | - Bradley J Walters
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, United States.,Department of Otolaryngology-Head and Neck Surgery, University of Mississippi Medical Center, Jackson, MS, United States
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Xing M, Kallogjeri D, Piccirillo JF. Investigating the Impact of Cognitive Training for Individuals With Bothersome Tinnitus: A Randomized Controlled Trial. Otolaryngol Head Neck Surg 2021; 165:854-861. [PMID: 33650921 DOI: 10.1177/0194599821994742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To evaluate the effectiveness of cognitive training in improving tinnitus bother and to identify predictors of patient response. STUDY DESIGN Prospective open-label randomized controlled trial. SETTING Online. METHODS Participants were adults with subjective idiopathic nonpulsatile tinnitus causing significant tinnitus-related distress. The intervention group trained by using auditory-intensive exercises for 20 minutes per day, 5 days per week, for 8 weeks. The active control group trained on the same schedule with non-auditory intensive games. Surveys were completed at baseline, 8 weeks, and 12 weeks. RESULTS A total of 64 participants completed the study. The median age was 63 years (range, 25-69) in the intervention group and 61 years (34-68) in the control group. Mixed model analysis revealed that within-subject change in Tinnitus Functional Index in the intervention group was not different than the control group, with marginal mean differences (95% CI): 0.24 (-11.20 to 10.7) and 2.17 (-8.50 to 12.83) at 8 weeks and 2.33 (-8.6 to 13.3) and 3.36 (-7.91 to 14.6) at 12 weeks, respectively. When the 2 study groups were compared, the control group had higher Tinnitus Functional Index scores than the intervention group by 10.5 points at baseline (95% CI, -0.92 to 29.89), 8.1 at 8 weeks (95% CI, -3.27 to 19.42), and 9.4 at 12 weeks (95% CI, -2.45 to 21.34). CONCLUSION Auditory-intensive cognitive training was not associated with changes in self-reported tinnitus bother. Given the potential for neuroplasticity to affect tinnitus, we believe that future studies on cognitive training for tinnitus remain relevant.
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Affiliation(s)
- Maggie Xing
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, Missouri, USA
| | - Dorina Kallogjeri
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, Missouri, USA
| | - Jay F Piccirillo
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, Missouri, USA
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Using Cortical Neuron Markers to Target Cells in the Dorsal Cochlear Nucleus. eNeuro 2021; 8:ENEURO.0413-20.2020. [PMID: 33563600 PMCID: PMC7920538 DOI: 10.1523/eneuro.0413-20.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 11/21/2022] Open
Abstract
The dorsal cochlear nucleus (DCN) is a region of particular interest for auditory and tinnitus research. However, lack of useful genetic markers for in vivo manipulations hinders elucidation of the DCN contribution to tinnitus pathophysiology. This work assesses whether adeno-associated viral vectors (AAV) containing the calcium/calmodulin-dependent protein kinase 2α (CaMKIIα) promoter and a mouse line of nicotinic acetylcholine receptor α2 subunit (Chrna2)-Cre can target specific DCN populations. We found that CaMKIIα cannot be used to target excitatory fusiform DCN neurons as labeled cells showed diverse morphology indicating they belong to different classes of DCN neurons. Light stimulation after driving Channelrhodopsin2 (ChR2) by the CaMKIIα promoter generated spikes in some units but firing rate decreased when light stimulation coincided with sound. Expression and activation of CaMKIIα-eArchaerhodopsin3.0 in the DCN produced inhibition in some units but sound-driven spikes were delayed by concomitant light stimulation. We explored the existence of Cre+ cells in the DCN of Chrna2-Cre mice by hydrogel embedding technique (CLARITY). There were almost no Cre+ cell bodies in the DCN; however, we identified profuse projections arising from the ventral cochlear nucleus (VCN). Anterograde labeling in the VCN revealed projections to the ipsilateral superior olive and contralateral medial nucleus of the trapezoid body (MNTB; bushy cells), and a second bundle terminating in the DCN, suggesting the latter to be excitatory Chrna2+ T-stellate cells. Exciting Chrna2+ cells increased DCN firing. This work shows that cortical molecular tools may be useful for manipulating the DCN especially for tinnitus studies.
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Perin P, Mabou Tagne A, Enrico P, Marino F, Cosentino M, Pizzala R, Boselli C. Cannabinoids, Inner Ear, Hearing, and Tinnitus: A Neuroimmunological Perspective. Front Neurol 2020; 11:505995. [PMID: 33329293 PMCID: PMC7719758 DOI: 10.3389/fneur.2020.505995] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 08/18/2020] [Indexed: 12/14/2022] Open
Abstract
Cannabis has been used for centuries for recreational and therapeutic purposes. Whereas, the recreative uses are based on the psychotropic effect of some of its compounds, its therapeutic effects range over a wide spectrum of actions, most of which target the brain or the immune system. Several studies have found cannabinoid receptors in the auditory system, both at peripheral and central levels, thus raising the interest in cannabinoid signaling in hearing, and especially in tinnitus, which is affected also by anxiety, memory, and attention circuits where cannabinoid effects are well described. Available studies on animal models of tinnitus suggest that cannabinoids are not likely to be helpful in tinnitus treatment and could even be harmful. However, the pharmacology of cannabinoids is very complex, and most studies focused on neural CB1R-based responses. Cannabinoid effects on the immune system (where CB2Rs predominate) are increasingly recognized as essential in understanding nervous system pathological responses, and data on immune cannabinoid targets have emerged in the auditory system as well. In addition, nonclassical cannabinoid targets (such as TRP channels) appear to play an important role in the auditory system as well. This review will focus on neuroimmunological mechanisms for cannabinoid effects and their possible use as protective and therapeutic agents in the ear and auditory system, especially in tinnitus.
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Affiliation(s)
- Paola Perin
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | | | | | | | | | - Roberto Pizzala
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Cinzia Boselli
- Department of Drug Sciences, University of Pavia, Pavia, Italy
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12
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Yin M, Xia C, Wu C, Ji Y, Zhou Y. Aberrant expression of Nav1.6 in the cochlear nucleus correlates with salicylate-induced tinnitus in rats. Biochem Biophys Res Commun 2020; 526:786-792. [PMID: 32268959 DOI: 10.1016/j.bbrc.2020.03.123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 03/21/2020] [Indexed: 12/31/2022]
Abstract
Hyperactivity in cochlear nucleus (CN) is one of the major neural correlates for tinnitus induction, yet the molecular factors that participate in the neuronal hyperexcitability remain unclear. The present study showed that acute and chronic administrations of salicylate were both capable of inducing reversible tinnitus in rats. The number of GAD 65/67-immunoreactive neurons in the AVCN and DCN was decreased, while the number of VGLUT 1/2-immunoreactive neurons in the AVCN and DCN was increased when rats were experiencing tinnitus, providing evidence for excitatory-inhibitory imbalance in CN is correlated with tinnitus. Interestingly, the expression level of Nav1.6, an important subtype of voltage-gated sodium channels was significantly increased in the DCN and AVCN of rats experiencing tinnitus, the up-regulation of Nav1.6 was returned to normal level following the disappearance of tinnitus. Double-labeling experiments revealed that Nav1.6 expression was down-regulated in the GAD 65/67-positive neurons in the DCN and AVCN of rats experiencing tinnitus. Notably, the percentage of co-localization of Nav1.6 and NeuN-labeling fusiform neurons was markedly increased in the DCN during tinnitus. These findings uncover the tinnitus-associated alteration in Nav1.6, a potential key contributor that can lead to hyperexcitability in CN and contribute to salicylate-induced tinnitus.
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Affiliation(s)
- Manli Yin
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, 200444, China
| | - Chenchen Xia
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, 200444, China
| | - Cong Wu
- Department of Otolaryngology-Head and Neck Surgery, Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200011, China; Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, 200125, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200125, China
| | - Yonghua Ji
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, 200444, China; Translational Institute for Cancer Pain, Xinhua Hospital Chongming Branch, Shanghai, 202150, China.
| | - You Zhou
- Department of Otolaryngology-Head and Neck Surgery, Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200011, China; Ear Institute, Shanghai Jiaotong University School of Medicine, Shanghai, 200125, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, 200125, China.
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Freemyer A, Neal C, Nelson-Brantley J, Staecker H, Durham D. Early Onset Region and Cell Specific Alterations of Doublecortin Expression in the CNS of Animals with Sound Damage Induced Hearing Loss. IBRO Rep 2019; 7:129-140. [PMID: 31872150 PMCID: PMC6906648 DOI: 10.1016/j.ibror.2019.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 10/18/2019] [Indexed: 01/03/2023] Open
Abstract
Sound damage induced hearing loss has been shown to elicit changes in auditory and non-auditory brain regions. A protein critical for neuronal migration and brain development, doublecortin (DCX), has been used as a marker of central nervous system (CNS) neuroplasticity. DCX is expressed in unipolar brush cells (UBCs) of the dorsal cochlear nucleus (DCN), cerebellar parafloccular lobe (PFL) and neuronal precursor cells in the sub-granular zone of the hippocampal dentate gyrus (DG). Sound damage induced hearing loss has been shown to differentially impact DCX expression months later. To identify earlier alterations in DCX expression, we utilized immunohistochemistry to detect DCX protein in three brain regions (DCN, PFL, DG) approximately one month following unilateral sound damage. Auditory brainstem response was used to measure hearing loss. Unilateral hearing loss was evident in all sound damaged animals. Hearing loss related decreases in DCX expression were evident bilaterally in the DG while hearing loss related increases in DCX expression were evident bilaterally in the PFL. No changes to DCX expression were evident in the auditory DCN. Gap detection was used to assess whether this sound damage paradigm induced tinnitus-like behavior. However, results obtained from this behavioral test as used here were inconclusive and are presented here only as a guide to others wishing to design similar studies.
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Affiliation(s)
- Andrea Freemyer
- Department of Otolaryngology- Head and Neck Surgery, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
- Department of Rehabilitation Sciences and Physical Therapy, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
| | - Christopher Neal
- Department of Otolaryngology- Head and Neck Surgery, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
| | - Jennifer Nelson-Brantley
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
| | - Hinrich Staecker
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
| | - Dianne Durham
- Department of Otolaryngology- Head and Neck Surgery, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, United States
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Guex AA, Hight AE, Narasimhan S, Vachicouras N, Lee DJ, Lacour SP, Brown MC. Auditory brainstem stimulation with a conformable microfabricated array elicits responses with tonotopically organized components. Hear Res 2019; 377:339-352. [PMID: 30867111 DOI: 10.1016/j.heares.2019.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 01/11/2019] [Accepted: 02/22/2019] [Indexed: 02/07/2023]
Abstract
Auditory brainstem implants (ABIs) restore hearing to deaf individuals not eligible for cochlear implants. Speech comprehension in ABI users is generally poor compared to that of cochlear implant users, and side effects are common. The poor performance may result from activating broad areas and multiple neuronal populations of the cochlear nucleus, however detailed studies of the responses to surface stimulation of the cochlear nucleus are lacking. A conformable electrode array was microfabricated to fit on the rat's dorsal cochlear nucleus (DCN). It hosts 20 small electrodes (each 100 μm diam.). The array was tested by recording evoked potentials and neural activity along the tonotopic axis of the inferior colliculus (IC). Almost all bipolar electrode pairs elicited responses, in some cases with an even, or relatively constant, pattern of thresholds and supra-threshold measures along the long axis of the array. This pattern suggests that conformable arrays can provide relatively constant excitation along the surface of the DCN and thus might decrease the ABI side effects caused by spread of high current to adjacent structures. We also examined tonotopic patterns of the IC responses. Compared to sound-evoked responses, electrically-evoked response mappings had less tonotopic organization and were broader in width. They became more tonotopic when the evoked activity common to all electrodes and the late phase of response were subtracted out, perhaps because the remaining activity is from tonotopically organized principal cells of the DCN. Responses became less tonotopic when inter-electrode distance was increased from 400 μm to 800 μm but were relatively unaffected by changing to monopolar stimulation. The results illustrate the challenges of using a surface array to present tonotopic cues and improve speech comprehension in humans who use the ABI.
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Affiliation(s)
- Amélie A Guex
- Laboratory for Soft Bioelectronic Interfaces, Centre for Neuroprosthetics, School of Engineering, Institute of Microengineering & Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Ariel Edward Hight
- Eaton-Peabody Laboratories and Department of Otolaryngology, Head and Neck Surgery, Massachusetts Eye and Ear, and Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
| | - Shreya Narasimhan
- Eaton-Peabody Laboratories and Department of Otolaryngology, Head and Neck Surgery, Massachusetts Eye and Ear, and Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
| | - Nicolas Vachicouras
- Laboratory for Soft Bioelectronic Interfaces, Centre for Neuroprosthetics, School of Engineering, Institute of Microengineering & Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Daniel J Lee
- Eaton-Peabody Laboratories and Department of Otolaryngology, Head and Neck Surgery, Massachusetts Eye and Ear, and Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA
| | - Stéphanie P Lacour
- Laboratory for Soft Bioelectronic Interfaces, Centre for Neuroprosthetics, School of Engineering, Institute of Microengineering & Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - M Christian Brown
- Eaton-Peabody Laboratories and Department of Otolaryngology, Head and Neck Surgery, Massachusetts Eye and Ear, and Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA.
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Karimi Boroujeni M, Mahmoudian S, Jarollahi F. The investigation of semantic memory deficit in chronic tinnitus: a behavioral report. Braz J Otorhinolaryngol 2019; 86:185-190. [PMID: 30683563 PMCID: PMC9422494 DOI: 10.1016/j.bjorl.2018.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 07/28/2018] [Accepted: 11/05/2018] [Indexed: 01/03/2023] Open
Abstract
Introduction Tinnitus is a central auditory disorder in which different processing systems are involved as a network. One of these networks is memory. Previous studies have demonstrated some deficits in various types of memory in chronic tinnitus. Objectives The main purpose of the present study was to investigate the semantic memory, which is not yet investigated in the tinnitus population. Methods In this case–control study, 15 subjects with chronic tinnitus and 16 matched healthy controls were included. 40 semantically related and 40 semantically unrelated word pairs were presented to the participants in a counter-balanced fashion. They were asked to make decision about their semantic relatedness. Then the participants’ reaction times and the accuracy of responses were calculated. Results Mean of reaction times were significantly longer in the tinnitus group (M = 1034 ms, SD = 0.31) compared to the control group (Mean = 1016 ms, SD = 0.13), p < 0.05. However, no significant difference was found for the mean percentage of correct responses between the two groups. Conclusion The current study provided behavioral evidence that chronic tinnitus can affect the semantic memory. Such behavioral outcomes may provide new insights into more research activities in the field of electrophysiology and neuroimaging in the tinnitus population.
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Affiliation(s)
- Maryam Karimi Boroujeni
- Iran University of Medical Sciences (IUMS), School of Rehabilitation Sciences, Department of Audiology, Tehran, Iran
| | - Saeid Mahmoudian
- Iran University of Medical Sciences (IUMS), ENT and Head & Neck Research Center, Tehran, Iran
| | - Farnoush Jarollahi
- Iran University of Medical Sciences (IUMS), School of Rehabilitation Sciences, Department of Audiology, Tehran, Iran.
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The ion channels and synapses responsible for the physiological diversity of mammalian lower brainstem auditory neurons. Hear Res 2018; 376:33-46. [PMID: 30606624 DOI: 10.1016/j.heares.2018.12.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/12/2018] [Accepted: 12/22/2018] [Indexed: 11/20/2022]
Abstract
The auditory part of the brainstem is composed of several nuclei specialized in the computation of the different spectral and temporal features of the sound before it reaches the higher auditory regions. There are a high diversity of neuronal types in these nuclei, many with remarkable electrophysiological and synaptic properties unique to these structures. This diversity reflects specializations necessary to process the different auditory signals in order to extract precisely the acoustic information necessary for the auditory perception by the animal. Low threshold Kv1 channels and HCN channels are expressed in neurons that use timing clues for auditory processing, like bushy and octopus cells, in order to restrict action potential firing and reduce input resistance and membrane time constant. Kv3 channels allow principal neurons of the MNTB and pyramidal DCN neurons to fire fast trains of action potentials. Calcium channels on cartwheel DCN neurons produce complex spikes characteristic of these neurons. Calyceal synapses compensate the low input resistance of bushy and principal neurons of the MNTB by releasing hundreds of glutamate vesicles resulting in large EPSCs acting in fast ionotropic glutamate receptors, in order to reduce temporal summation of synaptic potentials, allowing more precise correspondence of pre- and post-synaptic potentials, and phase-locking. Pre-synaptic calyceal sodium channels have fast recovery from inactivation allowing extremely fast trains of action potential firing, and persistent sodium channels produce spontaneous activity of fusiform neurons at rest, which expands the dynamic range of these neurons. The unique combinations of different ion channels, ionotropic receptors and synaptic structures create a unique functional diversity of neurons extremely adapted to their complex functions in the auditory processing.
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Basura GJ, Hu X, Juan JS, Tessier A, Kovelman I. Human central auditory plasticity: A review of functional near-infrared spectroscopy (fNIRS) to measure cochlear implant performance and tinnitus perception. Laryngoscope Investig Otolaryngol 2018; 3:463-472. [PMID: 30599031 PMCID: PMC6302720 DOI: 10.1002/lio2.185] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
OBJECTIVE Functional near-infrared spectroscopy (fNIRS) is an emerging noninvasive technology used to study cerebral cortex activity. Being virtually silent and compatible with cochlear implants has helped establish fNIRS as an important tool when investigating auditory cortex as well as cortices involved with hearing and language processing in adults and during child development. With respect to this review article, more recently, fNIRS has also been used to investigate central auditory plasticity following hearing loss and tinnitus or phantom sound perception. METHODS Here, we review the currently available literature reporting the use of fNIRS in human studies with cochlear implants and tinnitus to measure human central auditory cortical circuits. We also provide the reader with detailed reviews of the technology and traditional recording paradigms/methods used in these auditory-based studies. RESULTS The purpose of this review article is to summarize theoretical advancements in our understanding of the neurocognitive mechanisms underlying auditory processes and their plasticity through fNIRS research of human auditory performance with cochlear implantation and plasticity that may contribute to the central percepts of tinnitus. CONCLUSION fNIRS is an emerging noninvasive brain imaging technology that has wide reaching application that can be applied to human studies involving cochlear implants and tinnitus. LEVEL OF EVIDENCE N/A.
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Affiliation(s)
- Gregory J. Basura
- Center for Human Growth and DevelopmentUniversity of MichiganAnn ArborMichiganU.S.A
- Department of Otolaryngology/Head and Neck Surgery, Kresge Hearing Research InstituteUniversity of MichiganAnn ArborMichiganU.S.A
| | - Xiao‐Su Hu
- Center for Human Growth and DevelopmentUniversity of MichiganAnn ArborMichiganU.S.A
| | - Juan San Juan
- Department of Otolaryngology/Head and Neck Surgery, Kresge Hearing Research InstituteUniversity of MichiganAnn ArborMichiganU.S.A
| | | | - Ioulia Kovelman
- Center for Human Growth and DevelopmentUniversity of MichiganAnn ArborMichiganU.S.A
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Muca A, Standafer E, Apawu AK, Ahmad F, Ghoddoussi F, Hali M, Warila J, Berkowitz BA, Holt AG. Tinnitus and temporary hearing loss result in differential noise-induced spatial reorganization of brain activity. Brain Struct Funct 2018; 223:2343-2360. [PMID: 29488007 PMCID: PMC6129978 DOI: 10.1007/s00429-018-1635-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 02/17/2018] [Indexed: 12/27/2022]
Abstract
Loud noise frequently results in hyperacusis or hearing loss (i.e., increased or decreased sensitivity to sound). These conditions are often accompanied by tinnitus (ringing in the ears) and changes in spontaneous neuronal activity (SNA). The ability to differentiate the contributions of hyperacusis and hearing loss to neural correlates of tinnitus has yet to be achieved. Towards this purpose, we used a combination of behavior, electrophysiology, and imaging tools to investigate two models of noise-induced tinnitus (either with temporary hearing loss or with permanent hearing loss). Manganese (Mn2+) uptake was used as a measure of calcium channel function and as an index of SNA. Manganese uptake was examined in vivo with manganese-enhanced magnetic resonance imaging (MEMRI) in key auditory brain regions implicated in tinnitus. Following acoustic trauma, MEMRI, the SNA index, showed evidence of spatially dependent rearrangement of Mn2+ uptake within specific brain nuclei (i.e., reorganization). Reorganization of Mn2+ uptake in the superior olivary complex and cochlear nucleus was dependent upon tinnitus status. However, reorganization of Mn2+ uptake in the inferior colliculus was dependent upon hearing sensitivity. Furthermore, following permanent hearing loss, reduced Mn2+ uptake was observed. Overall, by combining testing for hearing sensitivity, tinnitus, and SNA, our data move forward the possibility of discriminating the contributions of hyperacusis and hearing loss to tinnitus.
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Affiliation(s)
- Antonela Muca
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA
| | - Emily Standafer
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA
| | - Aaron K Apawu
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA
| | - Farhan Ahmad
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA
| | - Farhad Ghoddoussi
- Department of Anesthesiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Mirabela Hali
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA
| | - James Warila
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA
| | - Bruce A Berkowitz
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA
- Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Avril Genene Holt
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, 550 East Canfield Ave., Detroit, MI, 48201, USA.
- John D. Dingell VAMC, Detroit, MI, USA.
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19
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Krauss P, Tziridis K, Metzner C, Schilling A, Hoppe U, Schulze H. Stochastic Resonance Controlled Upregulation of Internal Noise after Hearing Loss as a Putative Cause of Tinnitus-Related Neuronal Hyperactivity. Front Neurosci 2016; 10:597. [PMID: 28082861 PMCID: PMC5187388 DOI: 10.3389/fnins.2016.00597] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 12/14/2016] [Indexed: 11/25/2022] Open
Abstract
Subjective tinnitus is generally assumed to be a consequence of hearing loss. In animal studies it has been demonstrated that acoustic trauma induced cochlear damage can lead to behavioral signs of tinnitus. In addition it was shown that noise trauma may lead to deafferentation of cochlear inner hair cells (IHC) even in the absence of elevated hearing thresholds, and it seems conceivable that such hidden hearing loss may be sufficient to cause tinnitus. Numerous studies have indicated that tinnitus is correlated with pathologically increased spontaneous firing rates and hyperactivity of neurons along the auditory pathway. It has been proposed that this hyperactivity is the consequence of a mechanism aiming to compensate for reduced input to the auditory system by increasing central neuronal gain, a mechanism referred to as homeostatic plasticity (HP), thereby maintaining mean firing rates over longer timescales for stabilization of neuronal processing. Here we propose an alternative, new interpretation of tinnitus-related development of neuronal hyperactivity in terms of information theory. In particular, we suggest that stochastic resonance (SR) plays a key role in both short- and long-term plasticity within the auditory system and that SR is the primary cause of neuronal hyperactivity and tinnitus. We argue that following hearing loss, SR serves to lift signals above the increased neuronal thresholds, thereby partly compensating for the hearing loss. In our model, the increased amount of internal noise-which is crucial for SR to work-corresponds to neuronal hyperactivity which subsequently causes neuronal plasticity along the auditory pathway and finally may lead to the development of a phantom percept, i.e., subjective tinnitus. We demonstrate the plausibility of our hypothesis using a computational model and provide exemplary findings in human patients that are consistent with that model. Finally we discuss the observed asymmetry in human tinnitus pitch distribution as a consequence of asymmetry of the distribution of auditory nerve type I fibers along the cochlea in the context of our model.
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Affiliation(s)
- Patrick Krauss
- Experimental Otolaryngology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
- Biophysics Group, Department of Physics, Center for Medical Physics and Technology, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Konstantin Tziridis
- Experimental Otolaryngology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Claus Metzner
- Biophysics Group, Department of Physics, Center for Medical Physics and Technology, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Achim Schilling
- Experimental Otolaryngology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
- Biophysics Group, Department of Physics, Center for Medical Physics and Technology, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Ulrich Hoppe
- Department of Audiology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Holger Schulze
- Experimental Otolaryngology, ENT-Hospital, Head and Neck Surgery, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
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20
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Klessinger S. Radiofrequency neurotomy for the treatment of somatosensory tinnitus in a patient after spine trauma. A case report. OTOLARYNGOLOGY CASE REPORTS 2016. [DOI: 10.1016/j.xocr.2016.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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21
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Godfrey DA, Lee AC, Hamilton WD, Benjamin LC, Vishwanath S, Simo H, Godfrey LM, Mustapha AIAA, Heffner RS. Volumes of cochlear nucleus regions in rodents. Hear Res 2016; 339:161-174. [PMID: 27435005 DOI: 10.1097/sla.0000000000001177.complications] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 07/15/2016] [Indexed: 05/25/2023]
Abstract
The cochlear nucleus receives all the coded information about sound from the cochlea and is the source of auditory information for the rest of the central auditory system. As such, it is a critical auditory nucleus. The sizes of the cochlear nucleus as a whole and its three major subdivisions - anteroventral cochlear nucleus (AVCN), posteroventral cochlear nucleus (PVCN), and dorsal cochlear nucleus (DCN) - have been measured in a large number of mammals, but measurements of its subregions at a more detailed level for a variety of species have not previously been made. Size measurements are reported here for the summed granular regions, DCN layers, AVCN, PVCN, and interstitial nucleus in 15 different rodent species, as well as a lagomorph, carnivore, and small primate. This further refinement of measurements is important because the granular regions and superficial layers of the DCN appear to have some different functions than the other cochlear nucleus regions. Except for DCN layers in the mountain beaver, all regions were clearly identifiable in all the animals studied. Relative regional size differences among most of the rodents, and even the 3 non-rodents, were not large and did not show a consistent relation to their wide range of lifestyles and hearing parameters. However, the mountain beaver, and to a lesser extent the pocket gopher, two rodents that live in tunnel systems, had relative sizes of summed granular regions and DCN molecular layer distinctly larger than those of the other mammals. Among all the mammals studied, there was a high correlation between the size per body weight of summed granular regions and that of the DCN molecular layer, consistent with other evidence for a close relationship between granule cells and superficial DCN neurons.
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Affiliation(s)
- Donald A Godfrey
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States.
| | - Augustine C Lee
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Walter D Hamilton
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Louis C Benjamin
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Shilpa Vishwanath
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Hermann Simo
- Department of Medicine, University of Toledo, United States
| | - Lynn M Godfrey
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Abdurrahman I A A Mustapha
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
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22
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Godfrey DA, Lee AC, Hamilton WD, Benjamin LC, Vishwanath S, Simo H, Godfrey LM, Mustapha AIAA, Heffner RS. Volumes of cochlear nucleus regions in rodents. Hear Res 2016; 339:161-74. [PMID: 27435005 PMCID: PMC5835392 DOI: 10.1016/j.heares.2016.07.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 07/15/2016] [Indexed: 01/31/2023]
Abstract
The cochlear nucleus receives all the coded information about sound from the cochlea and is the source of auditory information for the rest of the central auditory system. As such, it is a critical auditory nucleus. The sizes of the cochlear nucleus as a whole and its three major subdivisions - anteroventral cochlear nucleus (AVCN), posteroventral cochlear nucleus (PVCN), and dorsal cochlear nucleus (DCN) - have been measured in a large number of mammals, but measurements of its subregions at a more detailed level for a variety of species have not previously been made. Size measurements are reported here for the summed granular regions, DCN layers, AVCN, PVCN, and interstitial nucleus in 15 different rodent species, as well as a lagomorph, carnivore, and small primate. This further refinement of measurements is important because the granular regions and superficial layers of the DCN appear to have some different functions than the other cochlear nucleus regions. Except for DCN layers in the mountain beaver, all regions were clearly identifiable in all the animals studied. Relative regional size differences among most of the rodents, and even the 3 non-rodents, were not large and did not show a consistent relation to their wide range of lifestyles and hearing parameters. However, the mountain beaver, and to a lesser extent the pocket gopher, two rodents that live in tunnel systems, had relative sizes of summed granular regions and DCN molecular layer distinctly larger than those of the other mammals. Among all the mammals studied, there was a high correlation between the size per body weight of summed granular regions and that of the DCN molecular layer, consistent with other evidence for a close relationship between granule cells and superficial DCN neurons.
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Affiliation(s)
- Donald A Godfrey
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States.
| | - Augustine C Lee
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Walter D Hamilton
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Louis C Benjamin
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Shilpa Vishwanath
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Hermann Simo
- Department of Medicine, University of Toledo, United States
| | - Lynn M Godfrey
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
| | - Abdurrahman I A A Mustapha
- Department of Neurology, University of Toledo, United States; Division of Otolaryngology and Dentistry, Department of Surgery, University of Toledo, United States
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Human Auditory and Adjacent Nonauditory Cerebral Cortices Are Hypermetabolic in Tinnitus as Measured by Functional Near-Infrared Spectroscopy (fNIRS). Neural Plast 2016; 2016:7453149. [PMID: 27042360 PMCID: PMC4793139 DOI: 10.1155/2016/7453149] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 01/26/2016] [Accepted: 02/07/2016] [Indexed: 12/29/2022] Open
Abstract
Tinnitus is the phantom perception of sound in the absence of an acoustic stimulus. To date, the purported neural correlates of tinnitus from animal models have not been adequately characterized with translational technology in the human brain. The aim of the present study was to measure changes in oxy-hemoglobin concentration from regions of interest (ROI; auditory cortex) and non-ROI (adjacent nonauditory cortices) during auditory stimulation and silence in participants with subjective tinnitus appreciated equally in both ears and in nontinnitus controls using functional near-infrared spectroscopy (fNIRS). Control and tinnitus participants with normal/near-normal hearing were tested during a passive auditory task. Hemodynamic activity was monitored over ROI and non-ROI under episodic periods of auditory stimulation with 750 or 8000 Hz tones, broadband noise, and silence. During periods of silence, tinnitus participants maintained increased hemodynamic responses in ROI, while a significant deactivation was seen in controls. Interestingly, non-ROI activity was also increased in the tinnitus group as compared to controls during silence. The present results demonstrate that both auditory and select nonauditory cortices have elevated hemodynamic activity in participants with tinnitus in the absence of an external auditory stimulus, a finding that may reflect basic science neural correlates of tinnitus that ultimately contribute to phantom sound perception.
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Abstract
The dorsal cochlear nucleus (DCN) is one of the first stations within the central auditory pathway where the basic computations underlying sound localization are initiated and heightened activity in the DCN may underlie central tinnitus. The neurotransmitter serotonin (5-hydroxytryptamine; 5-HT), is associated with many distinct behavioral or cognitive states, and serotonergic fibers are concentrated in the DCN. However, it remains unclear what is the function of this dense input. Using a combination of in vitro electrophysiology and optogenetics in mouse brain slices, we found that 5-HT directly enhances the excitability of fusiform principal cells via activation of two distinct 5-HT receptor subfamilies, 5-HT2A/2CR (5-HT2A/2C receptor) and 5-HT7R (5-HT7 receptor). This excitatory effect results from an augmentation of hyperpolarization-activated cyclic nucleotide-gated channels (Ih or HCN channels). The serotonergic regulation of excitability is G-protein-dependent and involves cAMP and Src kinase signaling pathways. Moreover, optogenetic activation of serotonergic axon terminals increased excitability of fusiform cells. Our findings reveal that 5-HT exerts a potent influence on fusiform cells by altering their intrinsic properties, which may enhance the sensitivity of the DCN to sensory input.
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Zheng Y, McPherson K, Reid P, Smith PF. The anti-inflammatory selective melanocortin receptor subtype 4 agonist, RO27-3225, fails to prevent acoustic trauma-induced tinnitus in rats. Eur J Pharmacol 2015; 761:206-10. [PMID: 25977231 DOI: 10.1016/j.ejphar.2015.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/06/2015] [Accepted: 05/11/2015] [Indexed: 10/23/2022]
Abstract
In preliminary studies we have observed a massive microglial activation in the cochlear nucleus following acoustic trauma-induced tinnitus in rats, which suggests that inflammatory responses within the central auditory system may be involved in the development and maintenance of tinnitus. Recently, the anti-inflammatory properties of melanocortins (MCs), have gained increasing interest in pharmacology due to their promising therapeutic potential in the treatment of inflammatory-mediated diseases. Among the five subtypes of the MC receptor, MC3 and MC4 receptors are the predominant brain receptors and are thought to play an important role in brain inflammation and neuroprotection. Importantly, MC4 receptors have been found in the mouse and rat central auditory systems. In this study we investigated whether the MC4 receptor agonist, RO27-3225, injected s.c at a dose of 90 or 180µg/kg, 30min before acoustic trauma and then every 12h for 10 days, could prevent the development of acoustic trauma-induced tinnitus in rats, using a conditioned behavioural suppression model. Although evidence of tinnitus developed in the exposed-vehicle group compared to the sham-vehicle group (P≤0.03), in response to a 32kHz tone, there were no significant drug effects from treatment with RO27-3225, indicating that it did not confer any protection against the development of tinnitus in this animal model. This result suggests that the anti-inflammatory effects of MC4 receptor agonists may not be sufficient to prevent tinnitus.
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Affiliation(s)
- Yiwen Zheng
- Dept. of Pharmacology and Toxicology, School of Medical Sciences, and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
| | - Kate McPherson
- Dept. of Pharmacology and Toxicology, School of Medical Sciences, and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Peter Reid
- Dept. of Pharmacology and Toxicology, School of Medical Sciences, and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Paul F Smith
- Dept. of Pharmacology and Toxicology, School of Medical Sciences, and the Brain Health Research Centre, University of Otago, Dunedin, New Zealand
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Lowe AS, Walton JP. Alterations in peripheral and central components of the auditory brainstem response: a neural assay of tinnitus. PLoS One 2015; 10:e0117228. [PMID: 25695496 PMCID: PMC4335042 DOI: 10.1371/journal.pone.0117228] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 12/22/2014] [Indexed: 11/18/2022] Open
Abstract
Chronic tinnitus, or “ringing of the ears”, affects upwards of 15% of the adult population. Identifying a cost-effective and objective measure of tinnitus is needed due to legal concerns and disability issues, as well as for facilitating the effort to assess neural biomarkers. We developed a modified gap-in-noise (GIN) paradigm to assess tinnitus in mice using the auditory brainstem response (ABR). We then compared the commonly used acoustic startle reflex gap-prepulse inhibition (gap-PPI) and the ABR GIN paradigm in young adult CBA/CaJ mice before and after administrating sodium salicylate (SS), which is known to reliably induce a 16 kHz tinnitus percept in rodents. Post-SS, gap-PPI was significantly reduced at 12 and 16 kHz, consistent with previous studies demonstrating a tinnitus-induced gap-PPI reduction in this frequency range. ABR audiograms indicated thresholds were significantly elevated post-SS, also consistent with previous studies. There was a significant increase in the peak 2 (P2) to peak 1 (P1) and peak 4 (P4) to P1 amplitude ratios in the mid-frequency range, along with decreased latency of P4 at higher intensities. For the ABR GIN, peak amplitudes of the response to the second noise burst were calculated as a percentage of the first noise burst response amplitudes to quantify neural gap processing. A significant decrease in this ratio (i.e. recovery) was seen only at 16 kHz for P1, indicating the presence of tinnitus near this frequency. Thus, this study demonstrates that GIN ABRs can be used as an efficient, non-invasive, and objective method of identifying the approximate pitch and presence of tinnitus in a mouse model. This technique has the potential for application in human subjects and also indicates significant, albeit different, deficits in temporal processing in peripheral and brainstem circuits following drug induced tinnitus.
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Affiliation(s)
- Andrea S. Lowe
- Department of Chemical & Biomedical Engineering, University of South Florida, Tampa, Florida, United States of America
- Global Center for Hearing & Speech Research, University of South Florida, Tampa, Florida, United States of America
| | - Joseph P. Walton
- Department of Communication Sciences & Disorders, University of South Florida, Tampa, Florida, United States of America
- Department of Chemical & Biomedical Engineering, University of South Florida, Tampa, Florida, United States of America
- Global Center for Hearing & Speech Research, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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Hu SS, Mei L, Chen JY, Huang ZW, Wu H. Expression of immediate-early genes in the dorsal cochlear nucleus in salicylate-induced tinnitus. Eur Arch Otorhinolaryngol 2015; 273:325-32. [DOI: 10.1007/s00405-014-3479-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 12/25/2014] [Indexed: 02/08/2023]
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Zheng Y, Dixon S, MacPherson K, Smith PF. Glutamic acid decarboxylase levels in the cochlear nucleus of rats with acoustic trauma-induced chronic tinnitus. Neurosci Lett 2015; 586:60-4. [DOI: 10.1016/j.neulet.2014.11.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 11/26/2014] [Accepted: 11/28/2014] [Indexed: 11/30/2022]
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Effects of salicylate on the inflammatory genes expression and synaptic ultrastructure in the cochlear nucleus of rats. Inflammation 2014; 37:365-73. [PMID: 24092407 DOI: 10.1007/s10753-013-9748-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Aspirin (salicylate), as a common drug that is frequently used for long-term treatment in a clinical setting, has the potential to cause reversible tinnitus. However, few reports have examined the inflammatory cytokines expression and alteration of synaptic ultrastructure in the cochlear nucleus (CN) in a rat model of tinnitus. The tinnitus-like behavior of rats were detected by the gap prepulse inhibition of acoustic startle (GPIAS) paradigm. We investigated the expression levels of the tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), N-methyl D-aspartate receptor subunit 2A (NR2A) mRNA and protein in the CN and compared synapses ultrastructure in the CN of tinnitus rats with normal ones. GPIAS showed that rats with long-term administration of salicylate were experiencing tinnitus, and the mRNA and protein expression levels of TNF-α and NR2A were up-regulated in chronic treatment groups, and they returned to baseline 14 days after cessation of treatment. Furthermore, compared to normal rats, repetitive salicylate-treated rats showed a greater number of presynaptic vesicles, thicker and longer postsynaptic densities, increased synaptic interface curvature. These data revealed that chronic salicylate administration markedly, but reversibly, induces tinnitus possibly via augmentation of the expression of TNF-α and NR2A and cause changes in synaptic ultrastructure in the CN. Long-term administration of salicylate causes neural plasticity changes at the CN level.
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Baizer JS, Wong KM, Paolone NA, Weinstock N, Salvi RJ, Manohar S, Witelson SF, Baker JF, Sherwood CC, Hof PR. Laminar and neurochemical organization of the dorsal cochlear nucleus of the human, monkey, cat, and rodents. Anat Rec (Hoboken) 2014; 297:1865-84. [PMID: 25132345 DOI: 10.1002/ar.23000] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 06/09/2014] [Indexed: 01/02/2023]
Abstract
The dorsal cochlear nucleus (DCN) is a brainstem structure that receives input from the auditory nerve. Many studies in a diversity of species have shown that the DCN has a laminar organization and identifiable neuron types with predictable synaptic relations to each other. In contrast, studies on the human DCN have found a less distinct laminar organization and fewer cell types, although there has been disagreement among studies in how to characterize laminar organization and which of the cell types identified in other animals are also present in humans. We have reexamined DCN organization in the human using immunohistochemistry to analyze the expression of several proteins that have been useful in delineating the neurochemical organization of other brainstem structures in humans: nonphosphorylated neurofilament protein (NPNFP), nitric oxide synthase (nNOS), and three calcium-binding proteins. The results for humans suggest a laminar organization with only two layers, and the presence of large projection neurons that are enriched in NPNFP. We did not observe evidence in humans of the inhibitory interneurons that have been described in the cat and rodent DCN. To compare humans and other animals directly we used immunohistochemistry to examine the DCN in the macaque monkey, the cat, and three rodents. We found similarities between macaque monkey and human in the expression of NPNFP and nNOS, and unexpected differences among species in the patterns of expression of the calcium-binding proteins.
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Affiliation(s)
- Joan S Baizer
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, New York
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Kong L, Xiong C, Li L, Yan J. Frequency-specific corticofugal modulation of the dorsal cochlear nucleus in mice. Front Syst Neurosci 2014; 8:125. [PMID: 25071477 PMCID: PMC4076887 DOI: 10.3389/fnsys.2014.00125] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 06/16/2014] [Indexed: 01/03/2023] Open
Abstract
The primary auditory cortex (AI) modulates the sound information processing in the lemniscal subcortical nuclei, including the anteroventral cochlear nucleus (AVCN), in a frequency-specific manner. The dorsal cochlear nucleus (DCN) is a non-lemniscal subcortical nucleus but it is tonotopically organized like the AVCN. However, it remains unclear how the AI modulates the sound information processing in the DCN. This study examined the impact of focal electrical stimulation of AI on the auditory responses of the DCN neurons in mice. We found that the electrical stimulation induced significant changes in the best frequency (BF) of DCN neurons. The changes in the BFs were highly specific to the BF differences between the stimulated AI neurons and the recorded DCN neurons. The DCN BFs shifted higher when the AI BFs were higher than the DCN BFs and the DCN BFs shifted lower when the AI BFs were lower than the DCN BFs. The DCN BFs showed no change when the AI and DCN BFs were similar. Moreover, the BF shifts were linearly correlated to the BF differences. Thus, our data suggest that corticofugal modulation of the DCN is also highly specific to frequency information, similar to the corticofugal modulation of the AVCN. The frequency-specificity of corticofugal modulation does not appear limited to the lemniscal ascending pathway.
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Affiliation(s)
- Lingzhi Kong
- Department of Physiology and Pharmacology, Faculty of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Colin Xiong
- Department of Physiology and Pharmacology, Faculty of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Liang Li
- Department of Psychology, Department of Machine Intelligence, Speech and Hearing Research Center, Key Laboratory on Machine Perception (Ministry of Education), PKU-IDG/McGovern Institute for Brain Research, Peking University Beijing, China
| | - Jun Yan
- Department of Physiology and Pharmacology, Faculty of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
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Henry JA, Roberts LE, Caspary DM, Theodoroff SM, Salvi RJ. Underlying mechanisms of tinnitus: review and clinical implications. J Am Acad Audiol 2014; 25:5-22; quiz 126. [PMID: 24622858 PMCID: PMC5063499 DOI: 10.3766/jaaa.25.1.2] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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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Abstract
Snapshot of key developments in the patent literature accompanied by explanatory synopses
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