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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: 5] [Impact Index Per Article: 1.7] [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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2
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Zhang Q, Zhao L, Shen W, Yang S. Subjective tinnitus: lesion-induced pathological central homeostasis remodeling. J Otol 2021; 16:266-272. [PMID: 34548874 PMCID: PMC8438635 DOI: 10.1016/j.joto.2021.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/07/2021] [Accepted: 04/07/2021] [Indexed: 11/25/2022] Open
Abstract
Subjective tinnitus is the most common type of tinnitus, which is the manifestation of pathological activities in the brain. It happens in a substantial portion of the general population and brings significant burden to the society. Severe subjective tinnitus can lead to depression and insomnia and severely affects patients' quality of life. However, due to poor understanding of its etiology and pathogenesis, treatment of subjective tinnitus remains challenging. In recent decades, a growing number of studies have shown that subjective tinnitus is related to lesion-induced neural plasticity of auditory and non-auditory central systems. This article reviews cellular mechanisms of neural plasticity in subjective tinnitus to provide further understanding of its pathogenesis.
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Affiliation(s)
- Qi Zhang
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Fuxing Street NO.28, Haidian District, Beijing, 100039, China
| | - Lidong Zhao
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Fuxing Street NO.28, Haidian District, Beijing, 100039, China
| | - Weidong Shen
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Fuxing Street NO.28, Haidian District, Beijing, 100039, China
| | - Shiming Yang
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Fuxing Street NO.28, Haidian District, Beijing, 100039, China
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Gault R, McGinnity TM, Coleman S. Perceptual Modeling of Tinnitus Pitch and Loudness. IEEE Trans Cogn Dev Syst 2020. [DOI: 10.1109/tcds.2020.2964841] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Shore SE, Wu C. Mechanisms of Noise-Induced Tinnitus: Insights from Cellular Studies. Neuron 2019; 103:8-20. [PMID: 31271756 DOI: 10.1016/j.neuron.2019.05.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 03/25/2019] [Accepted: 05/03/2019] [Indexed: 01/21/2023]
Abstract
Tinnitus, sound perception in the absence of physical stimuli, occurs in 15% of the population and is the top-reported disability for soldiers after combat. Noise overexposure is a major factor associated with tinnitus but does not always lead to tinnitus. Furthermore, people with normal audiograms can get tinnitus. In animal models, equivalent cochlear damage occurs in animals with and without behavioral evidence of tinnitus. But cochlear-nerve-recipient neurons in the brainstem demonstrate distinct, synchronized spontaneous firing patterns only in animals that develop tinnitus, driving activity in central brain regions and ultimately giving rise to phantom perception. Examining tinnitus-specific changes in single-cell populations enables us to begin to distinguish neural changes due to tinnitus from those that are due to hearing loss.
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Affiliation(s)
- Susan E Shore
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109, USA; Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA; Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Calvin Wu
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109, USA
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5
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Sedley W. Tinnitus: Does Gain Explain? Neuroscience 2019; 407:213-228. [DOI: 10.1016/j.neuroscience.2019.01.027] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 02/01/2023]
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Gault R, Mcginnity TM, Coleman S. A Computational Model of Thalamocortical Dysrhythmia in People With Tinnitus. IEEE Trans Neural Syst Rehabil Eng 2018; 26:1845-1857. [PMID: 30106678 DOI: 10.1109/tnsre.2018.2863740] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tinnitus is a problem that affects a diverse range of people. One common trait amongst people with tinnitus is the presence of hearing loss, which is apparent in over 90% of the cohort. It is postulated that the remainder of people with tinnitus have hidden hearing loss in the form of cochlear synaptopathy. The loss of hearing sensation is thought to cause a reduction in the bottom-up excitatory signals of the auditory pathway leading to a change in the frequency of thalamocortical oscillations known as thalamocortical dysrhythmia (TCD). The downward shift in oscillatory behavior, characteristic of TCD, has been recorded experimentally but the underlying mechanisms responsible for TCD in tinnitus subjects cannot be directly observed. This paper investigates these underlying mechanisms by creating a biologically faithful model of the auditory periphery and thalamocortical network, called the central auditory processing (CAP) model. The proposed model replicates tinnitus related activity in the presence of hearing loss and hidden hearing loss in the form of cochlear synaptopathy. The results of this paper show that, both the bottom-up and top-down changes are required in the auditory system for tinnitus related hyperactivity to coexist with TCD, contrary to the theoretical model for TCD. The CAP model provides a novel modeling approach to account for tinnitus related activity with and without hearing loss. Moreover, the results provide additional clarity to the understanding of TCD and tinnitus and provide direction for future approaches to treating tinnitus.
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Increased Synchrony and Bursting of Dorsal Cochlear Nucleus Fusiform Cells Correlate with Tinnitus. J Neurosci 2016; 36:2068-73. [PMID: 26865628 DOI: 10.1523/jneurosci.3960-15.2016] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED Tinnitus, the perception of phantom sounds, is thought to arise from increased neural synchrony, which facilitates perceptual binding and creates salient sensory features in the absence of physical stimuli. In the auditory cortex, increased spontaneous cross-unit synchrony and single-unit bursting are de facto physiological correlates of tinnitus. However, it is unknown whether neurons in the dorsal cochlear nucleus (DCN), the putative tinnitus-induction site, exhibit increased synchrony. Using a temporary-threshold shift model and gap-prepulse inhibition of the acoustic startle to assess tinnitus, we recorded spontaneous activity from fusiform cells, the principle neurons of the DCN, in normal hearing, tinnitus, and non-tinnitus guinea pigs. Synchrony and bursting, as well as spontaneous firing rate (SFR), correlated with behavioral evidence of tinnitus, and increased synchrony and bursting were associated with SFR elevation. The presence of increased synchrony and bursting in DCN fusiform cells suggests that a neural code for phantom sounds emerges in this brainstem location and likely contributes to the formation of the tinnitus percept. SIGNIFICANCE STATEMENT Tinnitus, a phantom auditory percept, is encoded by pathological changes in the neural synchrony code of perceptual processing. Increased cross-unit synchrony and bursting have been linked to tinnitus in several higher auditory stations but not in fusiform cells of the dorsal cochlear nucleus (DCN), key brainstem neurons in tinnitus generation. Here, we demonstrate increased synchrony and bursting of fusiform cell spontaneous firing, which correlate with frequency-specific behavioral measures of tinnitus. Thus, the neural representation of tinnitus emerges early in auditory processing and likely drives its pathophysiology in higher structures.
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Abstract
Tinnitus is a phantom auditory sensation that reduces quality of life for millions of people worldwide, and for which there is no medical cure. Most cases of tinnitus are associated with hearing loss caused by ageing or noise exposure. Exposure to loud recreational sound is common among the young, and this group are at increasing risk of developing tinnitus. Head or neck injuries can also trigger the development of tinnitus, as altered somatosensory input can affect auditory pathways and lead to tinnitus or modulate its intensity. Emotional and attentional state could be involved in the development and maintenance of tinnitus via top-down mechanisms. Thus, military personnel in combat are particularly at risk owing to combined risk factors (hearing loss, somatosensory system disturbances and emotional stress). Animal model studies have identified tinnitus-associated neural changes that commence at the cochlear nucleus and extend to the auditory cortex and other brain regions. Maladaptive neural plasticity seems to underlie these changes: it results in increased spontaneous firing rates and synchrony among neurons in central auditory structures, possibly generating the phantom percept. This Review highlights the links between animal and human studies, and discusses several therapeutic approaches that have been developed to target the neuroplastic changes underlying tinnitus.
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Chen GD, Sheppard A, Salvi R. Noise trauma induced plastic changes in brain regions outside the classical auditory pathway. Neuroscience 2015; 315:228-45. [PMID: 26701290 DOI: 10.1016/j.neuroscience.2015.12.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/19/2015] [Accepted: 12/02/2015] [Indexed: 10/22/2022]
Abstract
The effects of intense noise exposure on the classical auditory pathway have been extensively investigated; however, little is known about the effects of noise-induced hearing loss on non-classical auditory areas in the brain such as the lateral amygdala (LA) and striatum (Str). To address this issue, we compared the noise-induced changes in spontaneous and tone-evoked responses from multiunit clusters (MUC) in the LA and Str with those seen in auditory cortex (AC) in rats. High-frequency octave band noise (10-20 kHz) and narrow band noise (16-20 kHz) induced permanent threshold shifts at high-frequencies within and above the noise band but not at low frequencies. While the noise trauma significantly elevated spontaneous discharge rate (SR) in the AC, SRs in the LA and Str were only slightly increased across all frequencies. The high-frequency noise trauma affected tone-evoked firing rates in frequency and time-dependent manner and the changes appeared to be related to the severity of noise trauma. In the LA, tone-evoked firing rates were reduced at the high-frequencies (trauma area) whereas firing rates were enhanced at the low-frequencies or at the edge-frequency dependent on severity of hearing loss at the high frequencies. The firing rate temporal profile changed from a broad plateau to one sharp, delayed peak. In the AC, tone-evoked firing rates were depressed at high frequencies and enhanced at the low frequencies while the firing rate temporal profiles became substantially broader. In contrast, firing rates in the Str were generally decreased and firing rate temporal profiles become more phasic and less prolonged. The altered firing rate and pattern at low frequencies induced by high-frequency hearing loss could have perceptual consequences. The tone-evoked hyperactivity in low-frequency MUC could manifest as hyperacusis whereas the discharge pattern changes could affect temporal resolution and integration.
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Affiliation(s)
- G-D Chen
- Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, NY 14214, USA.
| | - A Sheppard
- Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, NY 14214, USA
| | - R Salvi
- Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, NY 14214, USA
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10
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Zhang J, Luo H, Pace E, Li L, Liu B. Psychophysical and neural correlates of noised-induced tinnitus in animals: Intra- and inter-auditory and non-auditory brain structure studies. Hear Res 2015; 334:7-19. [PMID: 26299842 DOI: 10.1016/j.heares.2015.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 08/04/2015] [Accepted: 08/17/2015] [Indexed: 12/19/2022]
Abstract
Tinnitus, a ringing in the ear or head without an external sound source, is a prevalent health problem. It is often associated with a number of limbic-associated disorders such as anxiety, sleep disturbance, and emotional distress. Thus, to investigate tinnitus, it is important to consider both auditory and non-auditory brain structures. This paper summarizes the psychophysical, immunocytochemical and electrophysiological evidence found in rats or hamsters with behavioral evidence of tinnitus. Behaviorally, we tested for tinnitus using a conditioned suppression/avoidance paradigm, gap detection acoustic reflex behavioral paradigm, and our newly developed conditioned licking suppression paradigm. Our new tinnitus behavioral paradigm requires relatively short baseline training, examines frequency specification of tinnitus perception, and achieves sensitive tinnitus testing at an individual level. To test for tinnitus-related anxiety and cognitive impairment, we used the elevated plus maze and Morris water maze. Our results showed that not all animals with tinnitus demonstrate anxiety and cognitive impairment. Immunocytochemically, we found that animals with tinnitus manifested increased Fos-like immunoreactivity (FLI) in both auditory and non-auditory structures. The manner in which FLI appeared suggests that lower brainstem structures may be involved in acute tinnitus whereas the midbrain and cortex are involved in more chronic tinnitus. Meanwhile, animals with tinnitus also manifested increased FLI in non-auditory brain structures that are involved in autonomic reactions, stress, arousal and attention. Electrophysiologically, we found that rats with tinnitus developed increased spontaneous firing in the auditory cortex (AC) and amygdala (AMG), as well as intra- and inter-AC and AMG neurosynchrony, which demonstrate that tinnitus may be actively produced and maintained by the interactions between the AC and AMG.
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Affiliation(s)
- Jinsheng Zhang
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University, School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA; Department of Communication Sciences & Disorders, Wayne State University, College of Liberal Arts & Sciences, 60 Farnsworth St., Detroit, MI 48202, USA.
| | - Hao Luo
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University, School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA
| | - Edward Pace
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University, School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA
| | - Liang Li
- Department of Psychology, McGovern Institute for Brain Research at PKU, Key Laboratory on Machine Perception (Ministry of Education), Peking University, Beijing, 100080, China
| | - Bin Liu
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University, School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA
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11
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Wu C, Stefanescu RA, Martel DT, Shore SE. Tinnitus: Maladaptive auditory-somatosensory plasticity. Hear Res 2015; 334:20-9. [PMID: 26074307 DOI: 10.1016/j.heares.2015.06.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/25/2015] [Accepted: 06/02/2015] [Indexed: 01/05/2023]
Abstract
Tinnitus, the phantom perception of sound, is physiologically characterized by an increase in spontaneous neural activity in the central auditory system. However, as tinnitus is often associated with hearing impairment, it is unclear how a decrease of afferent drive can result in central hyperactivity. In this review, we first assess methods for tinnitus induction and objective measures of the tinnitus percept in animal models. From animal studies, we discuss evidence that tinnitus originates in the cochlear nucleus (CN), and hypothesize mechanisms whereby hyperactivity may develop in the CN after peripheral auditory nerve damage. We elaborate how this process is likely mediated by plasticity of auditory-somatosensory integration in the CN: the circuitry in normal circumstances maintains a balance of auditory and somatosensory activities, and loss of auditory inputs alters the balance of auditory somatosensory integration in a stimulus timing dependent manner, which propels the circuit towards hyperactivity. Understanding the mechanisms underlying tinnitus generation is essential for its prevention and treatment. This article is part of a Special Issue entitled <Tinnitus>.
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Affiliation(s)
- Calvin Wu
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Roxana A Stefanescu
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - David T Martel
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Susan E Shore
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA.
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12
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Kalappa BI, Brozoski TJ, Turner JG, Caspary DM. Single unit hyperactivity and bursting in the auditory thalamus of awake rats directly correlates with behavioural evidence of tinnitus. J Physiol 2014; 592:5065-78. [PMID: 25217380 DOI: 10.1113/jphysiol.2014.278572] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Tinnitus is an auditory percept without an environmental acoustic correlate. Contemporary tinnitus models hypothesize tinnitus to be a consequence of maladaptive plasticity-induced disturbance of excitation-inhibition homeostasis, possibly convergent on medial geniculate body (MGB, auditory thalamus) and related neuronal networks. The MGB is an obligate acoustic relay in a unique position to gate auditory signals to higher-order auditory and limbic centres. Tinnitus-related maladaptive plastic changes of MGB-related neuronal networks may affect the gating function of MGB and enhance gain in central auditory and non-auditory neuronal networks, resulting in tinnitus. The present study examined the discharge properties of MGB neurons in the sound-exposure gap inhibition animal model of tinnitus. MGB single unit responses were obtained from awake unexposed controls and sound-exposed adult rats with behavioural evidence of tinnitus. MGB units in animals with tinnitus exhibited enhanced spontaneous firing, altered burst properties and increased rate-level function slope when driven by broadband noise and tones at the unit's characteristic frequency. Elevated patterns of neuronal activity and altered bursting showed a significant positive correlation with animals' tinnitus scores. Altered activity of MGB neurons revealed additional features of auditory system plasticity associated with tinnitus, which may provide a testable assay for future therapeutic and diagnostic development.
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Affiliation(s)
- Bopanna I Kalappa
- Southern Illinois University School of Medicine Department of Pharmacology, Springfield, IL, USA
| | - Thomas J Brozoski
- Southern Illinois University School of Medicine Department of Surgery, Division of Otolaryngology, Springfield, IL, USA
| | - Jeremy G Turner
- Southern Illinois University School of Medicine Department of Surgery, Division of Otolaryngology, Springfield, IL, USA Department of Psychology-Illinois College, Jacksonville, IL, USA
| | - Donald M Caspary
- Southern Illinois University School of Medicine Department of Pharmacology, Springfield, IL, USA Southern Illinois University School of Medicine Department of Surgery, Division of Otolaryngology, Springfield, IL, USA
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13
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Luo H, Pace E, Zhang X, Zhang J. Blast-induced tinnitus and spontaneous activity changes in the rat inferior colliculus. Neurosci Lett 2014; 580:47-51. [DOI: 10.1016/j.neulet.2014.07.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 07/04/2014] [Accepted: 07/24/2014] [Indexed: 11/16/2022]
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14
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Luo H, Pace E, Zhang X, Zhang J. Blast-Induced tinnitus and spontaneous firing changes in the rat dorsal cochlear nucleus. J Neurosci Res 2014; 92:1466-77. [DOI: 10.1002/jnr.23424] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 05/12/2014] [Accepted: 05/12/2014] [Indexed: 11/05/2022]
Affiliation(s)
- Hao Luo
- Department of Otolaryngology-Head and Neck Surgery; Wayne State University School of Medicine; Detroit Michigan
| | - Edward Pace
- Department of Otolaryngology-Head and Neck Surgery; Wayne State University School of Medicine; Detroit Michigan
| | - Xueguo Zhang
- Department of Otolaryngology-Head and Neck Surgery; Wayne State University School of Medicine; Detroit Michigan
| | - Jinsheng Zhang
- Department of Otolaryngology-Head and Neck Surgery; Wayne State University School of Medicine; Detroit Michigan
- Department of Communication Sciences and Disorders; Wayne State University College of Liberal Arts and Sciences; Detroit Michigan
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15
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Gold JR, Bajo VM. Insult-induced adaptive plasticity of the auditory system. Front Neurosci 2014; 8:110. [PMID: 24904256 PMCID: PMC4033160 DOI: 10.3389/fnins.2014.00110] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 04/28/2014] [Indexed: 01/10/2023] Open
Abstract
The brain displays a remarkable capacity for both widespread and region-specific modifications in response to environmental challenges, with adaptive processes bringing about the reweighing of connections in neural networks putatively required for optimizing performance and behavior. As an avenue for investigation, studies centered around changes in the mammalian auditory system, extending from the brainstem to the cortex, have revealed a plethora of mechanisms that operate in the context of sensory disruption after insult, be it lesion-, noise trauma, drug-, or age-related. Of particular interest in recent work are those aspects of auditory processing which, after sensory disruption, change at multiple—if not all—levels of the auditory hierarchy. These include changes in excitatory, inhibitory and neuromodulatory networks, consistent with theories of homeostatic plasticity; functional alterations in gene expression and in protein levels; as well as broader network processing effects with cognitive and behavioral implications. Nevertheless, there abounds substantial debate regarding which of these processes may only be sequelae of the original insult, and which may, in fact, be maladaptively compelling further degradation of the organism's competence to cope with its disrupted sensory context. In this review, we aim to examine how the mammalian auditory system responds in the wake of particular insults, and to disambiguate how the changes that develop might underlie a correlated class of phantom disorders, including tinnitus and hyperacusis, which putatively are brought about through maladaptive neuroplastic disruptions to auditory networks governing the spatial and temporal processing of acoustic sensory information.
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Affiliation(s)
- Joshua R Gold
- Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK
| | - Victoria M Bajo
- Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK
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16
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Church MW, Zhang JS, Langford MM, Perrine SA. 'Ecstasy' enhances noise-induced hearing loss. Hear Res 2013; 302:96-106. [PMID: 23711768 DOI: 10.1016/j.heares.2013.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/07/2013] [Accepted: 05/15/2013] [Indexed: 10/26/2022]
Abstract
'Ecstasy' or 3,4-methylenedioxy-N-methamphetamine (MDMA) is an amphetamine abused for its euphoric, empathogenic, hallucinatory, and stimulant effects. It is also used to treat certain psychiatric disorders. Common settings for Ecstasy use are nightclubs and "rave" parties where participants consume MDMA and dance to loud music. One concern with the club setting is that exposure to loud sounds can cause permanent sensorineural hearing loss. Another concern is that consumption of MDMA may enhance such hearing loss. Whereas this latter possibility has not been investigated, this study tested the hypothesis that MDMA enhances noise-induced hearing loss (NIHL) by exposing rats to either MDMA, noise trauma, both MDMA and noise, or neither treatment. MDMA was given in a binge pattern of 5 mg/kg per intraperitoneal injections every 2 h for a total of four injections to animals in the two MDMA-treated groups (MDMA-only and Noise + MDMA). Saline injections were given to the animals in the two non-MDMA groups (Control and Noise-only). Following the final injection, noise trauma was induced by a 10 kHz tone at 120 dB SPL for 1 h to animals in the two noise trauma-treated groups (Noise-only and Noise + MDMA). Hearing loss was assessed by the auditory brainstem response (ABR) and cochlear histology. Results showed that MDMA enhanced NIHL compared to Noise-only and that MDMA alone caused no hearing loss. This implies that "clubbers" and "rave-goers" are exacerbating the amount of NIHL when they consume MDMA and listen to loud sounds. In contrast to earlier reports, the present study found that MDMA by itself caused no changes in the click-evoked ABR's wave latencies or amplitudes.
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Affiliation(s)
- Michael W Church
- Department of Otolaryngology & Head Neck Surgery, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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17
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Eggermont JJ. Hearing loss, hyperacusis, or tinnitus: What is modeled in animal research? Hear Res 2013; 295:140-9. [DOI: 10.1016/j.heares.2012.01.005] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/09/2012] [Accepted: 01/16/2012] [Indexed: 11/29/2022]
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18
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Zhang J. Auditory cortex stimulation to suppress tinnitus: mechanisms and strategies. Hear Res 2012; 295:38-57. [PMID: 22683861 DOI: 10.1016/j.heares.2012.05.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 05/06/2012] [Accepted: 05/14/2012] [Indexed: 01/08/2023]
Abstract
Brain stimulation is an important method used to modulate neural activity and suppress tinnitus. Several auditory and non-auditory brain regions have been targeted for stimulation. This paper reviews recent progress on auditory cortex (AC) stimulation to suppress tinnitus and its underlying neural mechanisms and stimulation strategies. At the same time, the author provides his opinions and hypotheses on both animal and human models. The author also proposes a medial geniculate body (MGB)-thalamic reticular nucleus (TRN)-Gating mechanism to reflect tinnitus-related neural information coming from upstream and downstream projection structures. The upstream structures include the lower auditory brainstem and midbrain structures. The downstream structures include the AC and certain limbic centers. Both upstream and downstream information is involved in a dynamic gating mechanism in the MGB together with the TRN. When abnormal gating occurs at the thalamic level, the spilled-out information interacts with the AC to generate tinnitus. The tinnitus signals at the MGB-TRN-Gating may be modulated by different forms of stimulations including brain stimulation. Each stimulation acts as a gain modulator to control the level of tinnitus signals at the MGB-TRN-Gate. This hypothesis may explain why different types of stimulation can induce tinnitus suppression. Depending on the tinnitus etiology, MGB-TRN-Gating may be different in levels and dynamics, which cause variability in tinnitus suppression induced by different gain controllers. This may explain why the induced suppression of tinnitus by one type of stimulation varies across individual patients.
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Affiliation(s)
- Jinsheng Zhang
- Department of Otolaryngology - Head and Neck Surgery, Wayne State University, School of Medicine, 5E-UHC, 4201 Saint Antoine, Detroit, MI 48201, USA.
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Manzoor NF, Gao Y, Licari F, Kaltenbach JA. Comparison and contrast of noise-induced hyperactivity in the dorsal cochlear nucleus and inferior colliculus. Hear Res 2012; 295:114-23. [PMID: 22521905 DOI: 10.1016/j.heares.2012.04.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/26/2012] [Accepted: 04/03/2012] [Indexed: 01/13/2023]
Abstract
Induction of hyperactivity in the central auditory system is one of the major physiological hallmarks of animal models of noise-induced tinnitus. Although hyperactivity occurs at various levels of the auditory system, it is not clear to what extent hyperactivity originating in one nucleus contributes to hyperactivity at higher levels of the auditory system. In this study we compared the time courses and tonotopic distribution patterns of hyperactivity in the dorsal cochlear nucleus (DCN) and inferior colliculus (IC). A model of acquisition of hyperactivity in the IC by passive relay from the DCN would predict that the two nuclei show similar time courses and tonotopic profiles of hyperactivity. A model of acquisition of hyperactivity in the IC by compensatory plasticity mechanisms would predict that the IC and DCN would show differences in these features, since each adjusts to changes of spontaneous activity of opposite polarity. To test the role of these two mechanisms, animals were exposed to an intense hyperactivity-inducing tone (10 kHz, 115 dB SPL, 4 h) then studied electrophysiologically at three different post-exposure recovery times (from 1 to 6 weeks after exposure). For each time frame, multiunit spontaneous activity was mapped as a function of location along the tonotopic gradient in the DCN and IC. Comparison of activity profiles from the two nuclei showed a similar progression toward increased activity over time and culminated in the development of a central peak of hyperactivity at a similar tonotopic location. These similarities suggest that the shape of the activity profile is determined primarily by passive relay from the cochlear nucleus. However, the absolute levels of activity were generally much lower in the IC than in the DCN, suggesting that the magnitude of hyperactivity is greatly attenuated by inhibition.
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Affiliation(s)
- N F Manzoor
- Department of Neurosciences, The Cleveland Clinic, NE-63, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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Baizer JS, Manohar S, Paolone NA, Weinstock N, Salvi RJ. Understanding tinnitus: the dorsal cochlear nucleus, organization and plasticity. Brain Res 2012; 1485:40-53. [PMID: 22513100 DOI: 10.1016/j.brainres.2012.03.044] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 03/16/2012] [Accepted: 03/19/2012] [Indexed: 02/07/2023]
Abstract
Tinnitus, the perception of a phantom sound, is a common consequence of damage to the auditory periphery. A major goal of tinnitus research is to find the loci of the neural changes that underlie the disorder. Crucial to this endeavor has been the development of an animal behavioral model of tinnitus, so that neural changes can be correlated with behavioral evidence of tinnitus. Three major lines of evidence implicate the dorsal cochlear nucleus (DCN) in tinnitus. First, elevated spontaneous activity in the DCN is correlated with peripheral damage and tinnitus. Second, there are somatosensory inputs to the DCN that can modulate spontaneous activity and might mediate the somatic-auditory interactions seen in tinnitus patients. Third, we have found a subpopulation of DCN neurons in the adult rat that express doublecortin, a plasticity-related protein. The expression of this protein may reflect a role of these neurons in the neural reorganization causing tinnitus. However, there is a problem in extending the findings in the rodent DCN to humans. Classic studies state that the structure of the primate DCN is quite different from that of rodents, with primates lacking granule cells, the recipients of somatosensory input. To address the possibility of major species differences in DCN organization, we compared Nissl-stained sections of the DCN in five different species. In contrast to earlier reports, our data suggest that the organization of the primate DCN is not dramatically different from that of the rodents, and validate the use of animal data in the study of tinnitus. This article is part of a Special Issue entitled: Tinnitus Neuroscience.
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Affiliation(s)
- Joan S Baizer
- Department of Physiology and Biophysics, 123 Sherman Hall, University at Buffalo, Buffalo, NY 14214, USA.
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Zhang J, Zhang Y, Zhang X. Auditory cortex electrical stimulation suppresses tinnitus in rats. J Assoc Res Otolaryngol 2011; 12:185-201. [PMID: 21057850 PMCID: PMC3046330 DOI: 10.1007/s10162-010-0246-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 10/21/2010] [Indexed: 12/19/2022] Open
Abstract
Recent clinical studies have demonstrated that auditory cortex electrical stimulation (ACES) has yielded promising results in the suppression of patients' tinnitus. However, the large variability in the efficacy of ACES-induced suppression across individuals has hindered its development into a reliable therapy. Due to ethical reasons, many issues cannot be comprehensively addressed in patients. In order to search for effective stimulation targets and identify optimal stimulation strategies, we have developed the first rat model to test for the suppression of behavioral evidence of tone-induced tinnitus through ACES. Our behavioral results demonstrated that electrical stimulation of all channels (frequency bands) in the auditory cortex significantly suppressed behavioral evidence of tinnitus and enhanced hearing detection at the central level. Such suppression of tinnitus and enhancement of hearing detection were respectively demonstrated by a reversal of tone exposure compromised gap detection at 10-12, 14-16, and 26-28 kHz and compromised prepulse inhibition at 10-12 and 26-28 kHz. On the contrary, ACES did not induce behavioral changes in animals that did not manifest any behavioral evidence of tinnitus and compromised hearing detection following the same tone exposure. The results point out that tinnitus may be more related to compromised central auditory processing than hearing loss at the peripheral level. The ACES-induced suppression of behavioral evidence of tinnitus may involve restoration of abnormal central auditory processing.
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Affiliation(s)
- Jinsheng Zhang
- Laboratory of Auditory Prostheses Research, Department of Otolaryngology-Head and Neck Surgery,Wayne State University School of Medicine, 4201 Saint Antoine, Detroit, MI 48201, USA.
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Lanting C, de Kleine E, van Dijk P. Neural activity underlying tinnitus generation: Results from PET and fMRI. Hear Res 2009; 255:1-13. [PMID: 19545617 DOI: 10.1016/j.heares.2009.06.009] [Citation(s) in RCA: 216] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 06/15/2009] [Accepted: 06/15/2009] [Indexed: 10/20/2022]
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Zhang J, Guan Z. Modulatory effects of somatosensory electrical stimulation on neural activity of the dorsal cochlear nucleus of hamsters. J Neurosci Res 2008; 86:1178-87. [PMID: 17975829 DOI: 10.1002/jnr.21560] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effects of somatosensory electrical stimulation on the dorsal cochlear nucleus (DCN) activity of control and tone-exposed hamsters were investigated. One to three weeks after sound exposure and control treatment, multiunit activity was recorded at the surface of the left DCN before, during, and after electrical stimulation of the basal part of the left pinna. The results demonstrated that sound exposure induced hyperactivity in the DCN. In response to electrical stimulation, neural activity in the DCN of both control and exposed animals manifested four response types: S-S, suppression occurring during and after stimulation; E-S, excitation occurring during stimulation and suppression after; S-E, suppression occurring during stimulation and excitation after; and E-E, excitation occurring during and after stimulation. The results showed that there was a higher incidence of suppressive (up to 70%) than of excitatory responses during and after stimulation in both groups. In addition, there was a significantly higher degree of suppression after, rather than during stimulation. At high levels of electrical current, the degree of the induced suppression was generally higher during and after stimulation in exposed animals than in controls. The similarity of our results to those of previous clinical studies further supports the view that DCN hyperactivity is a direct neural correlate of tinnitus and that somatosensory electrical stimulation can be used to modulate DCN hyperactivity. Optimization of stimulation strategy through activating only certain neural pathways and applying appropriate stimulation parameters may allow somatosensory electrical stimulation to be used as an effective tool for tinnitus suppression.
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Affiliation(s)
- Jinsheng Zhang
- Department of Otolaryngology-Head and Neck Surgery, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
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Development of hyperactivity after hearing loss in a computational model of the dorsal cochlear nucleus depends on neuron response type. Hear Res 2008; 240:57-72. [PMID: 18396381 DOI: 10.1016/j.heares.2008.02.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 02/19/2008] [Accepted: 02/20/2008] [Indexed: 11/18/2022]
Abstract
Cochlear damage can change the spontaneous firing rates of neurons in the dorsal cochlear nucleus (DCN). Increased spontaneous firing rates (hyperactivity) after acoustic trauma have been observed in the DCN of rodents such as hamsters, chinchillas and rats. This hyperactivity has been interpreted as a neural correlate of tinnitus. In cats, however, the spontaneous firing rates of DCN neurons were not significantly elevated after acoustic trauma. Species-specific spontaneous firing rates after cochlear damage might be attributable to differences in the response types of DCN neurons: In gerbils, type III response characteristics are predominant, whereas in cats type IV responses are more frequent. To address the question of how the development of hyperactivity after cochlear damage depends on the response type of DCN neurons, we use a computational model of the basic circuit of the DCN. By changing the strength of two types of inhibition, we can reproduce salient features of the responses of DCN neurons. Simulated cochlear damage, which decreases the activity of auditory nerve fibers, is assumed to activate homeostatic plasticity in projection neurons (PNs) of the DCN. We find that the resulting spontaneous firing rates depend on the response type of DCN PNs: PNs with type III and type IV-T response characteristics may become hyperactive, whereas type IV PNs do not develop increased spontaneous firing rates after acoustic trauma. This theoretical framework for the mechanisms and circumstances of the development of hyperactivity in central auditory neurons might also provide new insights into the development of tinnitus.
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Abstract
Guided by findings from neural imaging and population responses in humans, where tinnitus is well characterized, several morphological and physiological substrates of tinnitus in animal studies are reviewed. These include changes in ion channels, receptor systems, single unit firing rate, and population responses. Most findings in humans can be interpreted as resulting from increased neural synchrony.
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Affiliation(s)
- Jos J Eggermont
- Department of Physiology & Biophysics, University of Calgary, Calgary, AB, Canada.
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