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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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152
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Hamilton C, D'Arcy S, Pearlmutter BA, Crispino G, Lalor EC, Conlon BJ. An Investigation of Feasibility and Safety of Bi-Modal Stimulation for the Treatment of Tinnitus: An Open-Label Pilot Study. Neuromodulation 2016; 19:832-837. [PMID: 27310062 PMCID: PMC5157761 DOI: 10.1111/ner.12452] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/31/2016] [Accepted: 04/22/2016] [Indexed: 01/23/2023]
Abstract
Objectives Tinnitus is the perception of sound in the absence of an external auditory stimulus. It is widely believed that tinnitus, in patients with associated hearing loss, is a neurological phenomenon primarily affecting the central auditory structures. However, there is growing evidence for the involvement of the somatosensory system in this form of tinnitus. For this reason it has been suggested that the condition may be amenable to bi‐modal stimulation of the auditory and somatosensory systems. We conducted a pilot study to investigate the feasibility and safety of a device that delivers simultaneous auditory and somatosensory stimulation to treat the symptoms of chronic tinnitus. Methods A cohort of 54 patients used the stimulation device for 10 weeks. Auditory stimulation was delivered via headphones and somatosensory stimulation was delivered via electrical stimulation of the tongue. Patient usage, logged by the device, was used to classify patients as compliant or noncompliant. Safety was assessed by reported adverse events and changes in tinnitus outcome measures. Response to treatment was assessed using tinnitus outcome measures: Minimum Masking Level (MML), Tinnitus Loudness Matching (TLM), and Tinnitus Handicap Inventory (THI). Results The device was well tolerated by patients and no adverse events or serious difficulties using the device were reported. Overall, 68% of patients met the defined compliance threshold. Compliant patients (N = 30) demonstrated statistically significant improvements in mean outcome measures after 10 weeks of treatment: THI (−11.7 pts, p < 0.001), TLM (−7.5dB, p < 0.001), and MML (−9.7dB, p < 0.001). The noncompliant group (N = 14) demonstrated no statistical improvements. Conclusion This study demonstrates the feasibility and safety of a new bi‐modal stimulation device and supports the potential efficacy of this new treatment for tinnitus.
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Affiliation(s)
- Caroline Hamilton
- Brain and Computation Lab, National University of Ireland Maynooth, Co. Kildare, Ireland.,ENT Department, Hermitage Medical Centre, Dublin, Ireland
| | | | - Barak A Pearlmutter
- Brain and Computation Lab, National University of Ireland Maynooth, Co. Kildare, Ireland
| | | | - Edmund C Lalor
- Neural-Engineering, School of Engineering, Trinity College Institute of Neuroscience and Trinity Centre for Bioengineering, Trinity College Dublin, Dublin, Ireland
| | - Brendan J Conlon
- ENT Department, Hermitage Medical Centre, Dublin, Ireland.,Department of Otolaryngology, St. James's Hospital, Dublin, Ireland
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153
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Kim TS, Yoo MH, Lee HS, Yang CJ, Ahn JH, Chung JW, Park HJ. Short-term changes in tinnitus pitch related to audiometric shape in sudden sensorineural hearing loss. Auris Nasus Larynx 2016; 43:281-6. [DOI: 10.1016/j.anl.2015.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/02/2015] [Accepted: 10/16/2015] [Indexed: 11/16/2022]
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154
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Relationship Between Chronic Tinnitus and Glial Cell Line-Derived Neurotrophic Factor Gene rs3812047, rs1110149, and rs884344 Polymorphisms in a Turkish Population. Biochem Genet 2016; 54:552-563. [PMID: 27180191 DOI: 10.1007/s10528-016-9741-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 05/07/2016] [Indexed: 02/03/2023]
Abstract
Glial cell line-derived neurotrophic factor (GDNF) plays a key role in early development of central auditory pathway and the inner ear. However, the auditory pathway studies of GDNF gene polymorphisms are scarce in the literature, and the studies especially associated with tinnitus are limited. Our study aimed to identify whether GDNF gene polymorphisms play any roles in the pathophysiology of tinnitus by investigating the relationship between tinnitus and GDNF polymorphisms. A total of 52 patients with chronic tinnitus and ages ranging from 18 to 55 were admitted to the Ear-Nose-Throat outpatient clinic of Celal Bayar University Medical Faculty Hospital of Manisa, Turkey and constituted the study group. Another 42 patients of the same age range, without tinnitus symptoms and lacking any systemic disease, were also admitted to the clinic and formed the control group. The tympanometric, audiological, and psychoacoustic assessments of the subjects were performed. Deoxyribonucleic acid samples obtained using venous blood taken for routine inspections were used to investigate GDNF gene polymorphisms (rs884344, rs3812047, and rs1110149) by polymerase chain reaction-based restriction fragment length polymorphism method. No correlation could be detected between GDNF rs884344 and rs3812047 polymorphisms and subjects with tinnitus (p > 0.05). Heterozygosity was significantly lower for GDNF rs1110149 polymorphism in tinnitus subjects compared to the controls (p < 0.05). However, the allele frequencies for all 3 polymorphisms were not significantly different between tinnitus and control groups (p > 0.05). Failure to detect correlations between tinnitus and GDNF gene polymorphisms suggests this may be due to the fact that the GDNF gene has a variable expression pattern in different tissues and pathologies. Therefore, the study should be improved and its scope should be expanded by including a larger group of patients and different tissues to investigate the expression pattern of GDNF.
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155
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Mulders WHAM, Spencer TC, Robertson D. Effects of pulsatile electrical stimulation of the round window on central hyperactivity after cochlear trauma in guinea pig. Hear Res 2016; 335:128-137. [PMID: 26970475 DOI: 10.1016/j.heares.2016.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 02/09/2016] [Accepted: 03/03/2016] [Indexed: 11/17/2022]
Abstract
Partial hearing loss induced by acoustic trauma has been shown in animal models to result in an increased spontaneous firing rate in central auditory structures. This so-called hyperactivity has been suggested to be involved in the generation of tinnitus, a phantom auditory sensation. Although there is no universal cure for tinnitus, electrical stimulation of the cochlea, as achieved by a cochlear implant, can result in significant reduction of the tinnitus percept. However, the mechanism by which this tinnitus suppression occurs is as yet unknown and furthermore cochlear implantation may not be an optimal treatment option for tinnitus sufferers who are not profoundly deaf. A better understanding of the mechanism of tinnitus suppression by electrical stimulation of the cochlea, may lead to the development of more specialised devices for those for whom a cochlear implant is not appropriate. This study aimed to investigate the effects of electrical stimulation in the form of brief biphasic shocks delivered to the round window of the cochlea on the spontaneous firing rates of hyperactive inferior colliculus neurons following acoustic trauma in guinea pigs. Effects during the stimulation itself included both inhibition and excitation but spontaneous firing was suppressed for up to hundreds of ms after the cessation of the shock train in all sampled hyperactive neurons. Pharmacological block of olivocochlear efferent action on outer hair cells did not eliminate the prolonged suppression observed in inferior colliculus neurons, and it is therefore likely that activation of the afferent pathways is responsible for the central effects observed.
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Affiliation(s)
- W H A M Mulders
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia.
| | - T C Spencer
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
| | - D Robertson
- The Auditory Laboratory, School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
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156
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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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157
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Somatic memory and gain increase as preconditions for tinnitus: Insights from congenital deafness. Hear Res 2016; 333:37-48. [DOI: 10.1016/j.heares.2015.12.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/27/2015] [Accepted: 12/18/2015] [Indexed: 11/19/2022]
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158
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Abstract
UNLABELLED It is not known why tinnitus occurs in some cases of hearing damage but not others. Abnormalities of excitation-inhibition balance could influence whether tinnitus develops and its severity if it does. Animal models of hearing damage, which also produce tinnitus based on behavioral evidence, have identified abnormalities of GABAergic inhibition, both cortically and subcortically. However, the precise relationships of GABA inhibitory changes to tinnitus itself, as opposed to other consequences of hearing damage, remain uncertain. Here, we used magnetic resonance spectroscopy to non-invasively quantify GABA in the left (LAC) and right (RAC) auditory cortices of a group of 14 patients with lateralized tinnitus (eight left ear) and 14 controls matched for age, sex, and hearing. We also explored the potential relationships with other brain metabolites (i.e., choline, N-acetylaspartate, and creatine). The presence of tinnitus was associated with a reduction in auditory cortex GABA concentration. Regardless of tinnitus laterality, post hoc testing indicated reductions that were significant in RAC and nonsignificant in LAC. Tinnitus severity and hearing loss were correlated positively with RAC choline but not GABA. We discuss the results in the context of current models of tinnitus and methodological constraints. SIGNIFICANCE STATEMENT Permanently affecting one in seven adults, tinnitus lacks both widely effective treatments and adequate understanding of its brain mechanisms. Existing animal models represent tinnitus that may not be distinguishable from homeostatic responses to the auditory insults used to induce it. Human studies can be well controlled in this regard but are usually not (with few even matching control subjects for hearing loss) and are limited in scope as a result of relying solely on non-invasive recording techniques. Here, we exploit recent advances in non-invasive spectroscopic techniques to establish, in a human study tightly controlled for hearing loss and hyperacusis, that tinnitus is associated with a significant reduction in auditory cortex GABA concentration, which has implications for understanding and treatment of the condition.
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159
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Novák O, Zelenka O, Hromádka T, Syka J. Immediate manifestation of acoustic trauma in the auditory cortex is layer specific and cell type dependent. J Neurophysiol 2016; 115:1860-74. [PMID: 26823513 DOI: 10.1152/jn.00810.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 01/28/2016] [Indexed: 02/02/2023] Open
Abstract
Exposure to loud sounds damages the auditory periphery and induces maladaptive changes in central parts of the auditory system. Diminished peripheral afferentation and altered inhibition influence the processing of sounds in the auditory cortex. It is unclear, however, which types of inhibitory interneurons are affected by acoustic trauma. Here we used single-unit electrophysiological recording and two-photon calcium imaging in anesthetized mice to evaluate the effects of acute acoustic trauma (125 dB SPL, white noise, 5 min) on the response properties of neurons in the core auditory cortex. Electrophysiological measurements suggested the selective impact of acoustic trauma on inhibitory interneurons in the auditory cortex. To further investigate which interneuronal types were affected, we used two-photon calcium imaging to record the activity of neurons in cortical layers 2/3 and 4, specifically focusing on parvalbumin-positive (PV+) and somatostatin-positive (SST+) interneurons. Spontaneous and pure-tone-evoked firing rates of SST+ interneurons increased in layer 4 immediately after acoustic trauma and remained almost unchanged in layer 2/3. Furthermore, PV+ interneurons with high best frequencies increased their evoked-to-spontaneous firing rate ratios only in layer 2/3 and did not change in layer 4. Finally, acoustic trauma unmasked low-frequency excitatory inputs only in layer 2/3. Our results demonstrate layer-specific changes in the activity of auditory cortical inhibitory interneurons within minutes after acoustic trauma.
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Affiliation(s)
- Ondřej Novák
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Ondřej Zelenka
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Tomáš Hromádka
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Josef Syka
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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160
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Stefanescu RA, Shore SE. NMDA Receptors Mediate Stimulus-Timing-Dependent Plasticity and Neural Synchrony in the Dorsal Cochlear Nucleus. Front Neural Circuits 2015; 9:75. [PMID: 26622224 PMCID: PMC4653590 DOI: 10.3389/fncir.2015.00075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 10/30/2015] [Indexed: 12/19/2022] Open
Abstract
Auditory information relayed by auditory nerve fibers and somatosensory information relayed by granule cell parallel fibers converge on the fusiform cells (FCs) of the dorsal cochlear nucleus, the first brain station of the auditory pathway. In vitro, parallel fiber synapses on FCs exhibit spike-timing-dependent plasticity with Hebbian learning rules, partially mediated by the NMDA receptor (NMDAr). Well-timed bimodal auditory-somatosensory stimulation, in vivo equivalent of spike-timing-dependent plasticity, can induce stimulus-timing-dependent plasticity (StTDP) of the FCs spontaneous and tone-evoked firing rates. In healthy guinea pigs, the resulting distribution of StTDP learning rules across a FC neural population is dominated by a Hebbian profile while anti-Hebbian, suppressive and enhancing LRs are less frequent. In this study, we investigate in vivo, the NMDAr contribution to FC baseline activity and long term plasticity. We find that blocking the NMDAr decreases the synchronization of FC- spontaneous activity and mediates differential modulation of FC rate-level functions such that low, and high threshold units are more likely to increase, and decrease, respectively, their maximum amplitudes. Three significant alterations in mean learning-rule profiles were identified: transitions from an initial Hebbian profile towards (1) an anti-Hebbian; (2) a suppressive profile; and (3) transitions from an anti-Hebbian to a Hebbian profile. FC units preserving their learning rules showed instead, NMDAr-dependent plasticity to unimodal acoustic stimulation, with persistent depression of tone-evoked responses changing to persistent enhancement following the NMDAr antagonist. These results reveal a crucial role of the NMDAr in mediating FC baseline activity and long-term plasticity which have important implications for signal processing and auditory pathologies related to maladaptive plasticity of dorsal cochlear nucleus circuitry.
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Affiliation(s)
- Roxana A Stefanescu
- 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 ; Department of Molecular and Integrative Physiology, University of Michigan Medical School Ann Arbor, MI, USA ; Department of Biomedical Engineering, University of Michigan Ann Arbor, MI, USA
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161
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Heeringa AN, van Dijk P. The immediate effects of acoustic trauma on excitation and inhibition in the inferior colliculus: A Wiener-kernel analysis. Hear Res 2015; 331:47-56. [PMID: 26523371 DOI: 10.1016/j.heares.2015.10.007] [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: 07/12/2015] [Revised: 09/27/2015] [Accepted: 10/15/2015] [Indexed: 12/13/2022]
Abstract
Noise-induced tinnitus and hyperacusis are thought to correspond to a disrupted balance between excitation and inhibition in the central auditory system. Excitation and inhibition are often studied using pure tones; however, these responses do not reveal inhibition within the excitatory pass band. Therefore, we used a Wiener-kernel analysis, complemented with singular value decomposition (SVD), to investigate the immediate effects of acoustic trauma on excitation and inhibition in the inferior colliculus (IC). Neural responses were recorded from the IC of three anesthetized albino guinea pigs before and immediately after a one-hour bilateral exposure to an 11-kHz tone of 124 dB SPL. Neural activity was recorded during the presentation of a 1-h continuous 70 dB SPL Gaussian-noise stimulus. Spike trains were subjected to Wiener-kernel analysis in which the second-order kernel was decomposed into excitatory and inhibitory components using SVD. Hearing thresholds between 3 and 22 kHz were elevated (13-47 dB) immediately after acoustic trauma. The presence and frequency tuning of excitation and inhibition in units with a low characteristic frequency (CF; < 3 kHz) was not affected, inhibition disappeared whereas excitation was not affected in mid-CF units (3 < CF < 11 kHz), and both excitation and inhibition disappeared in high-CF units (CF > 11 kHz). This specific differentiation could not be identified by tone-evoked receptive-field analysis, in which inhibitory responses disappeared in all units, along with excitatory responses in high-CF units. This study is the first to apply Wiener-kernel analysis, complemented with SVD, to study the effects of acoustic trauma on spike trains derived from the IC. With this analysis, a reduction of inhibition and preservation of good response thresholds was shown in mid-CF units immediately after acoustic trauma. These neurons may mediate noise-induced tinnitus and/or hyperacusis. Moreover, an immediate profound high-frequency hearing loss was reflected by reduced evoked firing rates and loss of both excitation and inhibition in high-CF units.
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Affiliation(s)
- Amarins Nieske Heeringa
- University of Groningen, University Medical Center Groningen, Department of Otorhinolaryngology - Head and Neck Surgery, P.O. Box 30.001, 9700 RB Groningen, The Netherlands; University of Groningen, Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), P.O. Box 72, 9700 AB Groningen, The Netherlands.
| | - Pim van Dijk
- University of Groningen, University Medical Center Groningen, Department of Otorhinolaryngology - Head and Neck Surgery, P.O. Box 30.001, 9700 RB Groningen, The Netherlands; University of Groningen, Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), P.O. Box 72, 9700 AB Groningen, The Netherlands.
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162
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Hinkley LB, Mizuiri D, Hong O, Nagarajan SS, Cheung SW. Increased striatal functional connectivity with auditory cortex in tinnitus. Front Hum Neurosci 2015; 9:568. [PMID: 26578924 PMCID: PMC4623204 DOI: 10.3389/fnhum.2015.00568] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 09/28/2015] [Indexed: 12/22/2022] Open
Abstract
Tinnitus is a common auditory perceptual disorder whose neural substrates are under intense debate. One physiologically based model posits the dorsal striatum to play a key role in gating auditory phantoms to perceptual awareness. Here, we directly test this model along with the roles of auditory and auditory-limbic networks in tinnitus non-invasively by comparing resting-state fMRI functional connectivity patterns in chronic tinnitus patients against matched control subjects without hearing loss. We assess resting-state functional connectivity of the caudate dorsal striatum (area LC), caudate head (CH), nucleus accumbens (NA), and primary auditory cortex (A1) to determine patterns of abnormal connectivity. In chronic tinnitus, increases in ipsilateral striatal–auditory cortical connectivity are found consistently only in area LC. Other patterns of increased connectivity are as follows: (1) right striatal area LC, A1, CH, and NA with parietal cortex, (2) left and right CHs with dorsal pre-frontal cortex, (3) NA and A1 with cerebellum, hippocampus, visual and ventral pre-frontal cortex. Those findings provide further support for a striatal gating model of tinnitus, where dysfunctionally permissive area LC enables auditory phantoms to reach perceptual awareness.
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Affiliation(s)
- Leighton B Hinkley
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco CA, USA
| | - Danielle Mizuiri
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco CA, USA
| | - OiSaeng Hong
- Department of Community Health Systems, School of Nursing, University of California at San Francisco, San Francisco CA, USA
| | - Srikantan S Nagarajan
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco CA, USA ; Department of Otolaryngology-Head and Neck Surgery, University of California at San Francisco, San Francisco CA, USA
| | - Steven W Cheung
- Department of Otolaryngology-Head and Neck Surgery, University of California at San Francisco, San Francisco CA, USA ; Surgical Services, San Francisco Veterans Affairs Medical Center, San Francisco CA, USA
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163
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Wang H, Li B, Feng Y, Cui B, Wu H, Shi H, Yin S. A Pilot Study of EEG Source Analysis Based Repetitive Transcranial Magnetic Stimulation for the Treatment of Tinnitus. PLoS One 2015; 10:e0139622. [PMID: 26430749 PMCID: PMC4592205 DOI: 10.1371/journal.pone.0139622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 09/15/2015] [Indexed: 12/17/2022] Open
Abstract
Objective Repetitive Transcranial Magnetic Stimulation (rTMS) is a novel therapeutic tool to induce a suppression of tinnitus. However, the optimal target sites are unknown. We aimed to determine whether low-frequency rTMS induced lasting suppression of tinnitus by decreasing neural activity in the cortex, navigated by high-density electroencephalogram (EEG) source analysis, and the utility of EEG for targeting treatment. Methods In this controlled three-armed trial, seven normal hearing patients with tonal tinnitus received a 10-day course of 1-Hz rTMS to the cortex, navigated by high-density EEG source analysis, to the left temporoparietal cortex region, and to the left temporoparietal with sham stimulation. The Tinnitus handicap inventory (THI) and a visual analog scale (VAS) were used to assess tinnitus severity and loudness. Measurements were taken before, and immediately, 2 weeks, and 4 weeks after the end of the interventions. Results Low-frequency rTMS decreased tinnitus significantly after active, but not sham, treatment. Responders in the EEG source analysis-based rTMS group, 71.4% (5/7) patients, experienced a significant reduction in tinnitus loudness, as evidenced by VAS scores. The target site of neuronal generators most consistently associated with a positive response was the frontal lobe in the right hemisphere, sourced using high-density EEG equipment, in the tinnitus patients. After left temporoparietal rTMS stimulation, 42.8% (3/7) patients experienced a decrease in tinnitus loudness. Conclusions Active EEG source analysis based rTMS resulted in significant suppression in tinnitus loudness, showing the superiority of neuronavigation-guided coil positioning in dealing with tinnitus. Non-auditory areas should be considered in the pathophysiology of tinnitus. This knowledge in turn can contribute to investigate the pathophysiology of tinnitus.
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Affiliation(s)
- Hui Wang
- Department of Otolaryngology head and neck surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China, 200233
| | - Bei Li
- Department of Otolaryngology head and neck surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China, 200233
| | - Yanmei Feng
- Department of Otolaryngology head and neck surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China, 200233
| | - Biao Cui
- Department of Otolaryngology head and neck surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China, 200233
| | - Hongmin Wu
- Department of Otolaryngology head and neck surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China, 200233
- * E-mail: (HS); (HW)
| | - Haibo Shi
- Department of Otolaryngology head and neck surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China, 200233
- * E-mail: (HS); (HW)
| | - Shankai Yin
- Department of Otolaryngology head and neck surgery, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China, 200233
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164
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Cunha AOS, de Oliveira JAC, Almeida SS, Garcia-Cairasco N, Leão RM. Inhibition of long-term potentiation in the schaffer-CA1 pathway by repetitive high-intensity sound stimulation. Neuroscience 2015; 310:114-27. [PMID: 26391920 DOI: 10.1016/j.neuroscience.2015.09.040] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 09/01/2015] [Accepted: 09/14/2015] [Indexed: 10/23/2022]
Abstract
High-intensity sound can induce seizures in susceptible animals. After repeated acoustic stimuli changes in behavioural seizure repertoire and epileptic EEG activity might be seen in recruited limbic and forebrain structures, a phenomenon known as audiogenic kindling. It is postulated that audiogenic kindling can produce synaptic plasticity events leading to the spread of epileptogenic activity to the limbic system. In order to test this hypothesis, we investigated if long-term potentiation (LTP) of hippocampal Schaffer-CA1 synapses and spatial navigation memory are altered by a repeated high-intensity sound stimulation (HISS) protocol, consisting of one-minute 120 dB broadband noise applied twice a day for 10 days, in normal Wistar rats and in audiogenic seizure-prone rats (Wistar Audiogenic Rats - WARs). After HISS all WARs exhibited midbrain seizures and 50% of these animals developed limbic recruitment, while only 26% of Wistar rats presented midbrain seizures and none of them had limbic recruitment. In naïve animals, LTP in hippocampal CA1 neurons was induced by 50- or 100-Hz high-frequency stimulation of Schaffer fibres in slices from both Wistar and WAR animals similarly. Surprisingly, HISS suppressed LTP in CA1 neurons in slices from Wistar rats that did not present any seizure, and inhibited LTP in slices from Wistar rats with only midbrain seizures. However HISS had no effect on LTP in CA1 neurons from slices of WARs. Interestingly HISS did not alter spatial navigation and memory in both strains. These findings show that repeated high-intensity sound stimulation prevent LTP of Schaffer-CA1 synapses from Wistar rats, without affecting spatial memory. This effect was not seen in hippocampi from audiogenic seizure-prone WARs. In WARs the link between auditory stimulation and hippocampal LTP seems to be disrupted which could be relevant for the susceptibility to seizures in this strain.
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Affiliation(s)
- A O S Cunha
- Department of Physiology, FMRP, University of São Paulo, Ribeirão Preto-SP, Brazil
| | - J A C de Oliveira
- Department of Physiology, FMRP, University of São Paulo, Ribeirão Preto-SP, Brazil
| | - S S Almeida
- Departament of Psychology, FFCLRP, University of São Paulo, Ribeirão Preto-SP, Brazil
| | - N Garcia-Cairasco
- Department of Physiology, FMRP, University of São Paulo, Ribeirão Preto-SP, Brazil.
| | - R M Leão
- Department of Physiology, FMRP, University of São Paulo, Ribeirão Preto-SP, Brazil.
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165
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Ravikumar G, Ashok Murthy V. A Study of Brainstem Auditory Evoked Responses in Normal Hearing Patients with Tinnitus. Indian J Otolaryngol Head Neck Surg 2015; 68:429-433. [PMID: 27833867 DOI: 10.1007/s12070-015-0917-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 09/21/2015] [Indexed: 11/24/2022] Open
Abstract
Tinnitus is thought to be an auditory phenomenon resulting from spontaneous neuronal activity somewhere along the auditory pathway either in the peripheral or central auditory system. The neural abnormalities underlying tinnitus are largely unknown. This study analysis the auditory brainstem responses in normal hearing patients with tinnitus. This study consisted of 100 patients divided into two groups. Group I (Control): 50 Normal hearing patients without tinnitus. Group II (Study): 50 Normal hearing patients complaining of tinnitus. Both groups were submitted to full audiological history taking, otological examination, basic audiologic evaluation and Auditory brainstem responses (ABR) followed by calculation of the absolute latencies of wave I, III and V and interpeak latencies between waves I-III, III-V and I-V. In the study group 20 patients showed abnormal results in at least 1 of the 6 parameters evaluated. The results of absolute latencies of wave I, III and V showed significant prolongation, but the interpeak latencies of waves I-III, III-V and I-V were not significantly prolonged when compared with control group. Our study data showed that there are changes in the central pathways in the study group. The significance of these changes must be investigated with further audiological and neurological tests. We also understand that ABR has to be included in the work up of tinnitus patients whose hearing is within normal parameters.
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Affiliation(s)
- G Ravikumar
- Department of ENT, Rajiv Gandhi Institute of Medical Sciences, Kadapa, 516 001 India
| | - V Ashok Murthy
- Department of ENT, Rajiv Gandhi Institute of Medical Sciences, Kadapa, 516 001 India
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166
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Elgoyhen AB, Langguth B, De Ridder D, Vanneste S. Tinnitus: perspectives from human neuroimaging. Nat Rev Neurosci 2015; 16:632-42. [DOI: 10.1038/nrn4003] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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167
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Mwilambwe-Tshilobo L, Davis AJO, Aizenberg M, Geffen MN. Selective Impairment in Frequency Discrimination in a Mouse Model of Tinnitus. PLoS One 2015; 10:e0137749. [PMID: 26352864 PMCID: PMC4564173 DOI: 10.1371/journal.pone.0137749] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 08/20/2015] [Indexed: 01/26/2023] Open
Abstract
Tinnitus is an auditory disorder, which affects millions of Americans, including active duty service members and veterans. It is manifested by a phantom sound that is commonly restricted to a specific frequency range. Because tinnitus is associated with hearing deficits, understanding how tinnitus affects hearing perception is important for guiding therapies to improve the quality of life in this vast group of patients. In a rodent model of tinnitus, prolonged exposure to a tone leads to a selective decrease in gap detection in specific frequency bands. However, whether and how hearing acuity is affected for sounds within and outside those frequency bands is not well understood. We induced tinnitus in mice by prolonged exposure to a loud mid-range tone, and behaviorally assayed whether mice exhibited a change in frequency discrimination acuity for tones embedded within the mid-frequency range and high-frequency range at 1, 4, and 8 weeks post-exposure. A subset of tone-exposed mice exhibited tinnitus-like symptoms, as demonstrated by selective deficits in gap detection, which were restricted to the high frequency range. These mice exhibited impaired frequency discrimination both for tones in the mid-frequency range and high-frequency range. The remaining tone exposed mice, which did not demonstrate behavioral evidence of tinnitus, showed temporary deficits in frequency discrimination for tones in the mid-frequency range, while control mice remained unimpaired. Our findings reveal that the high frequency-specific deficits in gap detection, indicative of tinnitus, are associated with impairments in frequency discrimination at the frequency of the presumed tinnitus.
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Affiliation(s)
- Laetitia Mwilambwe-Tshilobo
- Department of Otorhinolaryngology HNS, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Andrew J. O. Davis
- Department of Otorhinolaryngology HNS, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Mark Aizenberg
- Department of Otorhinolaryngology HNS, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Maria N. Geffen
- Department of Otorhinolaryngology HNS, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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168
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Enhanced GABAA-Mediated Tonic Inhibition in Auditory Thalamus of Rats with Behavioral Evidence of Tinnitus. J Neurosci 2015; 35:9369-80. [PMID: 26109660 DOI: 10.1523/jneurosci.5054-14.2015] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Accumulating evidence suggests a role for inhibitory neurotransmitter dysfunction in the pathology of tinnitus. Opposing hypotheses proposed either a pathologic decrease or increase of GABAergic inhibition in medial geniculate body (MGB). In thalamus, GABA mediates fast synaptic inhibition via synaptic GABAA receptors (GABAARs) and persistent tonic inhibition via high-affinity extrasynaptic GABAARs. Given that extrasynaptic GABAARs control the firing mode of thalamocortical neurons, we examined tonic GABAAR currents in MGB neurons in vitro, using the following three groups of adult rats: unexposed control (Ctrl); sound exposed with behavioral evidence of tinnitus (Tin); and sound exposed with no behavioral evidence of tinnitus (Non-T). Tonic GABAAR currents were evoked using the selective agonist gaboxadol. Months after a tinnitus-inducing sound exposure, gaboxadol-evoked tonic GABAAR currents showed significant tinnitus-related increases contralateral to the sound exposure. In situ hybridization studies found increased mRNA levels for GABAAR δ-subunits contralateral to the sound exposure. Tin rats showed significant increases in the number of spikes per burst evoked using suprathreshold-injected current steps. In summary, we found little evidence of tinnitus-related decreases in GABAergic neurotransmission. Tinnitus and chronic pain may reflect thalamocortical dysrhythmia, which results from abnormal theta-range resonant interactions between thalamus and cortex, due to neuronal hyperpolarization and the initiation of low-threshold calcium spike bursts (Walton and Llinás, 2010). In agreement with this hypothesis, we found tinnitus-related increases in tonic extrasynaptic GABAAR currents, in action potentials/evoked bursts, and in GABAAR δ-subunit gene expression. These tinnitus-related changes in GABAergic function may be markers for tinnitus pathology in the MGB.
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169
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Drexler D, López-Paullier M, Rodio S, González M, Geisinger D, Pedemonte M. Impact of reduction of tinnitus intensity on patients' quality of life. Int J Audiol 2015; 55:11-9. [PMID: 26328778 DOI: 10.3109/14992027.2015.1072772] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Assess the impact of a reduction of tinnitus intensity achieved through sound stimulation during sleep on the improvement in the patients' quality of life. DESIGN Acoustic stimuli consisted of a highly customized sound that reproduced the spectral and intensity characteristics of the tinnitus in each patient. This stimulus was uploaded into a portable electronic device and delivered through customized ear buds during sleep, every night for three months. STUDY SAMPLE Twelve patients with subjective idiopathic chronic tinnitus were studied. RESULTS Results were assessed through: (1) the measurement in dB SPL of tinnitus intensity reduction over time; (2) the results of three psychometric tests: Tinnitus handicap inventory (THI), Tinnitus reaction questionnaire (TRQ), Tinnitus functional index (TFI); and (3) a Visual analog scale (VAS) for tinnitus annoyance. After three months of treatment, we observed an average decrease in tinnitus intensity of 14.1 dB SPL (p < 0.001), implying a 62% reduction of the perceived sound. This improvement was followed by a statistically significant decrease of TRQ (78%), THI (65%), and TFI (77%). CONCLUSIONS These results suggested that the intensity reduction achieved through the protocol used in this study had a direct impact on the improvement in the patients' quality of life.
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Affiliation(s)
| | - Matías López-Paullier
- a Centro de Tinnitus Montevideo , Uruguay .,b Centro de Medicina del Sueño, Facultad de Medicina, Instituto Universitario CLAEH , Uruguay , and.,c Cátedra Otorrinolaringología, Facultad de Medicina, Universidad de la República , Uruguay
| | | | | | | | - Marisa Pedemonte
- a Centro de Tinnitus Montevideo , Uruguay .,b Centro de Medicina del Sueño, Facultad de Medicina, Instituto Universitario CLAEH , Uruguay , and
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170
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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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171
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Donovan C, Sweet J, Eccher M, Megerian C, Semaan M, Murray G, Miller J. Deep Brain Stimulation of Heschl Gyrus. Neurosurgery 2015; 77:940-7. [PMID: 26280116 DOI: 10.1227/neu.0000000000000969] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND:
Tinnitus is a source of considerable morbidity, and neuromodulation has been shown to be a potential treatment option. However, the location of the primary auditory cortex within Heschl gyrus in the temporal operculum presents challenges for targeting and electrode implantation.
OBJECTIVE:
To determine whether anatomic targeting with intraoperative verification using evoked potentials can be used to implant electrodes directly into the Heschl gyrus (HG).
METHODS:
Nine patients undergoing stereo-electroencephalogram evaluation for epilepsy were enrolled. HG was directly targeted on volumetric magnetic resonance imaging, and framed stereotaxy was used to implant an electrode parallel to the axis of the gyrus by using an oblique anterolateral-posteromedial trajectory. Intraoperative evoked potentials from auditory stimuli were recorded from multiple electrode contacts. Postoperatively, stimulation of each electrode was performed and participants were asked to describe the percept. Audiometric analysis was performed for 2 participants during subthreshold stimulation.
RESULTS:
Sounds presented to the contralateral and ipsilateral ears produced evoked potentials in HG electrodes in all participants intraoperatively. Stimulation produced a reproducible sensation of sound in all participants with perceived volume proportional to amplitude. Four participants reported distinct sounds when different electrodes were stimulated, with more medial contacts producing tones perceived as higher in pitch. Stimulation was not associated with adverse audiometric effects. There were no complications of electrode implantation.
CONCLUSION:
Direct anatomic targeting with physiological verification can be used to implant electrodes directly into primary auditory cortex. If deep brain stimulation proves effective for intractable tinnitus, this technique may be useful to assist with electrode implantation.
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Affiliation(s)
- Chris Donovan
- The Neurological Institute, University Hospital Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Jennifer Sweet
- The Neurological Institute, University Hospital Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Matthew Eccher
- The Neurological Institute, University Hospital Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Cliff Megerian
- The Neurological Institute, University Hospital Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Maroun Semaan
- The Neurological Institute, University Hospital Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Gail Murray
- The Neurological Institute, University Hospital Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Jonathan Miller
- The Neurological Institute, University Hospital Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
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172
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Eggermont JJ, Roberts LE. Tinnitus: animal models and findings in humans. Cell Tissue Res 2015; 361:311-36. [PMID: 25266340 PMCID: PMC4487353 DOI: 10.1007/s00441-014-1992-8] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 08/14/2014] [Indexed: 12/19/2022]
Abstract
Chronic tinnitus (ringing of the ears) is a medically untreatable condition that reduces quality of life for millions of individuals worldwide. Most cases are associated with hearing loss that may be detected by the audiogram or by more sensitive measures. Converging evidence from animal models and studies of human tinnitus sufferers indicates that, while cochlear damage is a trigger, most cases of tinnitus are not generated by irritative processes persisting in the cochlea but by changes that take place in central auditory pathways when auditory neurons lose their input from the ear. Forms of neural plasticity underlie these neural changes, which include increased spontaneous activity and neural gain in deafferented central auditory structures, increased synchronous activity in these structures, alterations in the tonotopic organization of auditory cortex, and changes in network behavior in nonauditory brain regions detected by functional imaging of individuals with tinnitus and corroborated by animal investigations. Research on the molecular mechanisms that underlie neural changes in tinnitus is in its infancy and represents a frontier for investigation.
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Affiliation(s)
- Jos J Eggermont
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, and Department of Psychology, University of Calgary, 2500 University Drive N.W, Calgary, AB, Canada,
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173
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Maslin MRD, Lloyd SK, Rutherford S, Freeman S, King A, Moore DR, Munro KJ. Rapid Increase in Neural Conduction Time in the Adult Human Auditory Brainstem Following Sudden Unilateral Deafness. J Assoc Res Otolaryngol 2015; 16:631-40. [PMID: 26055149 DOI: 10.1007/s10162-015-0526-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 05/20/2015] [Indexed: 12/25/2022] Open
Abstract
Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.
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Affiliation(s)
- M R D Maslin
- School of Psychological Sciences, University of Manchester, A3.11 Ellen Wilkinson Building, Oxford Road, Manchester, M13 9PL, UK
| | - S K Lloyd
- Salford Royal NHS Foundation Trust, Salford, UK
| | | | - S Freeman
- Salford Royal NHS Foundation Trust, Salford, UK
| | - A King
- Salford Royal NHS Foundation Trust, Salford, UK
| | - D R Moore
- School of Psychological Sciences, University of Manchester, A3.11 Ellen Wilkinson Building, Oxford Road, Manchester, M13 9PL, UK.,Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - K J Munro
- School of Psychological Sciences, University of Manchester, A3.11 Ellen Wilkinson Building, Oxford Road, Manchester, M13 9PL, UK. .,Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK.
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174
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D. P. S, T. L, B. T, M. A. P, K. K, C. M. S, G. D. S. Multisensory attention training for treatment of tinnitus. Sci Rep 2015; 5:10802. [PMID: 26020589 PMCID: PMC4447068 DOI: 10.1038/srep10802] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/23/2015] [Indexed: 12/28/2022] Open
Abstract
Tinnitus is the conscious perception of sound with no physical sound source. Some models of tinnitus pathophysiology suggest that networks associated with attention, memory, distress and multisensory experience are involved in tinnitus perception. The aim of this study was to evaluate whether a multisensory attention training paradigm which used audio, visual, and somatosensory stimulation would reduce tinnitus. Eighteen participants with predominantly unilateral chronic tinnitus were randomized between two groups receiving 20 daily sessions of either integration (attempting to reduce salience to tinnitus by binding with multisensory stimuli) or attention diversion (multisensory stimuli opposite side to tinnitus) training. The training resulted in small but statistically significant reductions in Tinnitus Functional Index and Tinnitus Severity Numeric Scale scores and improved attentional abilities. No statistically significant improvements in tinnitus were found between the training groups. This study demonstrated that a short period of multisensory attention training reduced unilateral tinnitus, but directing attention toward or away from the tinnitus side did not differentiate this effect.
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Affiliation(s)
- Spiegel D. P.
- Section of Audiology, School of Population Health, The University of Auckland, 261 Morrin Road, Glenn Innes, Auckland, New Zealand
- Centre for Brain Research, The University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand
- McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Canada
| | - Linford T.
- Section of Audiology, School of Population Health, The University of Auckland, 261 Morrin Road, Glenn Innes, Auckland, New Zealand
| | - Thompson B.
- Centre for Brain Research, The University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand
- Department of Optometry and Vision Science, The University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand
| | - Petoe M. A.
- Section of Audiology, School of Population Health, The University of Auckland, 261 Morrin Road, Glenn Innes, Auckland, New Zealand
- The Bionics Institute of Australia, 384-388 Albert Street, Melbourne, Australia
| | - Kobayashi K.
- Section of Audiology, School of Population Health, The University of Auckland, 261 Morrin Road, Glenn Innes, Auckland, New Zealand
- Centre for Brain Research, The University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand
| | - Stinear C. M.
- Centre for Brain Research, The University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand
| | - Searchfield G. D.
- Section of Audiology, School of Population Health, The University of Auckland, 261 Morrin Road, Glenn Innes, Auckland, New Zealand
- Centre for Brain Research, The University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand
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175
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Noreña AJ. Revisiting the cochlear and central mechanisms of tinnitus and therapeutic approaches. Audiol Neurootol 2015; 20 Suppl 1:53-9. [PMID: 25997584 DOI: 10.1159/000380749] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
This short review aims at revisiting some of the putative mechanisms of tinnitus. Cochlear-type tinnitus is suggested to result from aberrant activity generated before or at the cochlear nerve level. It is proposed that outer hair cells, through their role in regulating the endocochlear potential, can contribute to the enhancement of cochlear spontaneous activity. This hypothesis is attractive as it provides a possible explanation for cochlear tinnitus of different aetiologies, such as tinnitus produced by acute noise trauma, intense low-frequency sounds, middle-ear dysfunction or temporomandibular joint disorders. Other mechanisms, namely an excitatory drift in the operating point of the inner hair cells and activation of NMDA receptors, are also briefly reported. Central-type tinnitus is supposed to result from aberrant activity generated in auditory centres, i.e. in these patients, the tinnitus-related activity does not pre-exist in the cochlear nerve. A reduction in cochlear activity due to hearing loss is suggested to produce tinnitus-related plastic changes, namely cortical reorganisation, thalamic neuron hyperpolarisation, facilitation of non-auditory inputs and/or increase in central gain. These central changes can be associated with abnormal patterns of spontaneous activity in the auditory pathway, i.e. hyperactivity, hypersynchrony and/or oscillating activity. Therapeutic approaches aimed at reducing cochlear activity and/or tinnitus-related central changes are discussed.
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176
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Stein A, Engell A, Lau P, Wunderlich R, Junghoefer M, Wollbrink A, Bruchmann M, Rudack C, Pantev C. Enhancing Inhibition-Induced Plasticity in Tinnitus – Spectral Energy Contrasts in Tailor-Made Notched Music Matter. PLoS One 2015; 10:e0126494. [PMID: 25951605 PMCID: PMC4423974 DOI: 10.1371/journal.pone.0126494] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 04/02/2015] [Indexed: 11/19/2022] Open
Abstract
Chronic tinnitus seems to be caused by reduced inhibition among frequency selective neurons in the auditory cortex. One possibility to reduce tinnitus perception is to induce inhibition onto over-activated neurons representing the tinnitus frequency via tailor-made notched music (TMNM). Since lateral inhibition is modifiable by spectral energy contrasts, the question arises if the effects of inhibition-induced plasticity can be enhanced by introducing increased spectral energy contrasts (ISEC) in TMNM. Eighteen participants suffering from chronic tonal tinnitus, pseudo randomly assigned to either a classical TMNM or an ISEC-TMNM group, listened to notched music for three hours on three consecutive days. The music was filtered for both groups by introducing a notch filter centered at the individual tinnitus frequency. For the ISEC-TMNM group a frequency bandwidth of 3/8 octaves on each side of the notch was amplified, additionally, by about 20 dB. Before and after each music exposure, participants rated their subjectively perceived tinnitus loudness on a visual analog scale. During the magnetoencephalographic recordings, participants were stimulated with either a reference tone of 500 Hz or a test tone with a carrier frequency representing the individual tinnitus pitch. Perceived tinnitus loudness was significantly reduced after TMNM exposure, though TMNM type did not influence the loudness ratings. Tinnitus related neural activity in the N1m time window and in the so called tinnitus network comprising temporal, parietal and frontal regions was reduced after TMNM exposure. The ISEC-TMNM group revealed even enhanced inhibition-induced plasticity in a temporal and a frontal cortical area. Overall, inhibition of tinnitus related neural activity could be strengthened in people affected with tinnitus by increasing spectral energy contrast in TMNM, confirming the concepts of inhibition-induced plasticity via TMNM and spectral energy contrasts.
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Affiliation(s)
- Alwina Stein
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
| | - Alva Engell
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
| | - Pia Lau
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
| | - Robert Wunderlich
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
| | - Markus Junghoefer
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
| | - Andreas Wollbrink
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
| | - Maximilian Bruchmann
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
| | - Claudia Rudack
- Department of Otolaryngology, University Hospital, Muenster, Germany
| | - Christo Pantev
- Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Muenster, Germany
- * E-mail:
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Evidence for differential modulation of primary and nonprimary auditory cortex by forward masking in tinnitus. Hear Res 2015; 327:9-27. [PMID: 25937134 DOI: 10.1016/j.heares.2015.04.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 04/07/2015] [Accepted: 04/10/2015] [Indexed: 11/21/2022]
Abstract
It has been proposed that tinnitus is generated by aberrant neural activity that develops among neurons in tonotopic of regions of primary auditory cortex (A1) affected by hearing loss, which is also the frequency region where tinnitus percepts localize (Eggermont and Roberts 2004; Roberts et al., 2010, 2013). These models suggest (1) that differences between tinnitus and control groups of similar age and audiometric function should depend on whether A1 is probed in tinnitus frequency region (TFR) or below it, and (2) that brain responses evoked from A1 should track changes in the tinnitus percept when residual inhibition (RI) is induced by forward masking. We tested these predictions by measuring (128-channel EEG) the sound-evoked 40-Hz auditory steady-state response (ASSR) known to localize tonotopically to neural sources in A1. For comparison the N1 transient response localizing to distributed neural sources in nonprimary cortex (A2) was also studied. When tested under baseline conditions where tinnitus subjects would have heard their tinnitus, ASSR responses were larger in a tinnitus group than in controls when evoked by 500 Hz probes while the reverse was true for tinnitus and control groups tested with 5 kHz probes, confirming frequency-dependent group differences in this measure. On subsequent trials where RI was induced by masking (narrow band noise centered at 5 kHz), ASSR amplitude increased in the tinnitus group probed at 5 kHz but not in the tinnitus group probed at 500 Hz. When collapsed into a single sample tinnitus subjects reporting comparatively greater RI depth and duration showed comparatively larger ASSR increases after masking regardless of probe frequency. Effects of masking on ASSR amplitude in the control groups were completely reversed from those in the tinnitus groups, with no change seen to 5 kHz probes but ASSR increases to 500 Hz probes even though the masking sound contained no energy at 500 Hz (an "off-frequency" masking effect). In contrast to these findings for the ASSR, N1 amplitude was larger in tinnitus than control groups at both probe frequencies under baseline conditions, decreased after masking in all conditions, and did not relate to RI. These results suggest that aberrant neural activity occurring in the TFR of A1 underlies tinnitus and its modulation during RI. They indicate further that while neural changes occur in A2 in tinnitus, these changes do not reflect the tinnitus percept. Models for tinnitus and forward masking are described that integrate these findings within a common framework.
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178
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Eggermont JJ. Animal models of spontaneous activity in the healthy and impaired auditory system. Front Neural Circuits 2015; 9:19. [PMID: 25983679 PMCID: PMC4415415 DOI: 10.3389/fncir.2015.00019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 04/10/2015] [Indexed: 11/30/2022] Open
Abstract
Spontaneous neural activity in the auditory nerve fibers and in auditory cortex in healthy animals is discussed with respect to the question: Is spontaneous activity noise or information carrier? The studies reviewed suggest strongly that spontaneous activity is a carrier of information. Subsequently, I review the numerous findings in the impaired auditory system, particularly with reference to noise trauma and tinnitus. Here the common assumption is that tinnitus reflects increased noise in the auditory system that among others affects temporal processing and interferes with the gap-startle reflex, which is frequently used as a behavioral assay for tinnitus. It is, however, more likely that the increased spontaneous activity in tinnitus, firing rate as well as neural synchrony, carries information that shapes the activity of downstream structures, including non-auditory ones, and leading to the tinnitus percept. The main drivers of that process are bursting and synchronous firing, which facilitates transfer of activity across synapses, and allows formation of auditory objects, such as tinnitus.
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Affiliation(s)
- Jos J Eggermont
- Department of Physiology and Pharmacology, Department of Psychology, University of Calgary Calgary, AB, Canada
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179
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Wan G, Corfas G. No longer falling on deaf ears: mechanisms of degeneration and regeneration of cochlear ribbon synapses. Hear Res 2015; 329:1-10. [PMID: 25937135 DOI: 10.1016/j.heares.2015.04.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 04/01/2015] [Accepted: 04/20/2015] [Indexed: 01/02/2023]
Abstract
Cochlear ribbon synapses are required for the rapid and precise neural transmission of acoustic signals from inner hair cells to the spiral ganglion neurons. Emerging evidence suggests that damage to these synapses represents an important form of cochlear neuropathy that might be highly prevalent in sensorineural hearing loss. In this review, we discuss our current knowledge on how ribbon synapses are damaged by noise and during aging, as well as potential strategies to promote ribbon synapse regeneration for hearing restoration.
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Affiliation(s)
- Guoqiang Wan
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Gabriel Corfas
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
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180
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Song JJ, Vanneste S, De Ridder D. Dysfunctional noise cancelling of the rostral anterior cingulate cortex in tinnitus patients. PLoS One 2015; 10:e0123538. [PMID: 25875099 PMCID: PMC4395158 DOI: 10.1371/journal.pone.0123538] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/05/2015] [Indexed: 12/31/2022] Open
Abstract
Background Peripheral auditory deafferentation and central compensation have been regarded as the main culprits of tinnitus generation. However, patient-to-patient discrepancy in the range of the percentage of daytime in which tinnitus is perceived (tinnitus awareness percentage, 0 – 100%), is not fully explicable only by peripheral deafferentation, considering that the deafferentation is a stable persisting phenomenon but tinnitus is intermittently perceived in most patients. Consequently, the involvement of a dysfunctional noise cancellation mechanism has recently been suggested with regard to the individual differences in reported tinnitus awareness. By correlating the tinnitus awareness percentage with resting-state source-localized electroencephalography findings, we may be able to retrieve the cortical area that is negatively correlated with tinnitus awareness percentage, and then the area may be regarded as the core of the noise cancelling system that is defective in patients with tinnitus. Methods and Findings Using resting-state cortical oscillation, we investigated 80 tinnitus patients by correlating the tinnitus awareness percentage with their source-localized cortical oscillatory activity and functional connectivity. The activity of bilateral rostral anterior cingulate cortices (ACCs), left dorsal- and pregenual ACCs for the delta band, bilateral rostral/pregenual/subgenual ACCs for the theta band, and left rostral/pregenual ACC for the beta 1 band displayed significantly negative correlations with tinnitus awareness percentage. Also, the connectivity between the left primary auditory cortex (A1) and the rostral ACC, as well as between the left A1 and the subgenual ACC for the beta 1 band, were negatively correlated with tinnitus awareness percentage. Conclusions These results may designate the role of the rostral ACC as the core of the descending noise cancellation system, and thus dysfunction of the rostral ACC may result in perception of tinnitus. The present study also opens a possibility of tinnitus modulation by neuromodulatory approaches targeting the rostral ACC.
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Affiliation(s)
- Jae Jin Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seongnam, Korea
- * E-mail:
| | - Sven Vanneste
- Department of Translational Neuroscience, Faculty of Medicine, University of Antwerp, Edegem, Belgium
- Lab for Auditory and Integrative Neuroscience, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, United States of America
| | - Dirk De Ridder
- Unit of Neurosurgery, Department of Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
- BRAIN, Sint Augustinus Hospital, Antwerp, Belgium
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181
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182
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Coomber B, Kowalkowski VL, Berger JI, Palmer AR, Wallace MN. Modulating central gain in tinnitus: changes in nitric oxide synthase in the ventral cochlear nucleus. Front Neurol 2015; 6:53. [PMID: 25806021 PMCID: PMC4354362 DOI: 10.3389/fneur.2015.00053] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 02/25/2015] [Indexed: 01/30/2023] Open
Abstract
A significant challenge in tinnitus research lies in explaining how acoustic insult leads to tinnitus in some individuals, but not others. One possibility is genetic variability in the expression and function of neuromodulators – components of neural signaling that alter the balance of excitation and inhibition in neural circuits. An example is nitric oxide (NO) – a free radical and potent neuromodulator in the mammalian brain – that regulates plasticity via both pre-synaptic and postsynaptic mechanisms. Changes in NO have previously been implicated in tinnitus generation, specifically in the ventral cochlear nucleus (VCN). Here, we examined nitric oxide synthase (NOS) – the enzyme responsible for NO production – in the guinea pig VCN following acoustic trauma. NOS was present in most cell types – including spherical and globular bushy cells, small, medium, and large multipolar cells, and octopus cells – spanning the entire extent of the VCN. The staining pattern was symmetrical in control animals. Unilateral acoustic over-exposure (AOE) resulted in marked asymmetries between ipsilateral and contralateral sides of the VCN in terms of the distribution of NOS across the cochlear nuclei in animals with behavioral evidence of tinnitus: fewer NOS-positive cells and a reduced level of NOS staining was present across the whole extent of the contralateral VCN, relative to the ipsilateral VCN. The asymmetric pattern of NOS-containing cells was observed as early as 1 day after AOE and was also present in some animals at 3, 7, and 21 days after AOE. However, it was not until 8 weeks after AOE, when tinnitus had developed, that asymmetries were significant overall, compared with control animals. Asymmetrical NOS expression was not correlated with shifts in the threshold hearing levels. Variability in NOS expression between animals may represent one underlying difference that can be linked to whether or not tinnitus develops after noise exposure.
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Affiliation(s)
- Ben Coomber
- MRC Institute of Hearing Research , Nottingham , UK
| | - Victoria L Kowalkowski
- MRC Institute of Hearing Research , Nottingham , UK ; Otology and Hearing, Division of Clinical Neuroscience, University of Nottingham , Nottingham , UK
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183
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Deep brain stimulation in tinnitus: current and future perspectives. Brain Res 2015; 1608:51-65. [PMID: 25758066 DOI: 10.1016/j.brainres.2015.02.050] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 11/22/2022]
Abstract
Chronic tinnitus, also known as ringing in the ears, affects up to 15% of the adults and causes a serious socio-economic burden. At present, there is no treatment available which substantially reduces the perception of this phantom sound. In the past few years, preclinical and clinical studies have unraveled central mechanisms involved in the pathophysiology of tinnitus, replacing the classical periphery-based hypothesis. In subcortical auditory and non-auditory regions, increased spontaneous activity, neuronal bursting and synchrony were found. When reaching the auditory cortex, these neuronal alterations become perceptually relevant and consequently are perceived as phantom sound. A therapy with a potential to counteract deeply located pathological activity is deep brain stimulation, which has already been demonstrated to be effective in neurological diseases such as Parkinson's disease. In this review, several brain targets are discussed as possible targets for deep brain stimulation in tinnitus. The potential applicability of this treatment in tinnitus is discussed with examples from the preclinical field and clinical case studies.
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184
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Eggermont JJ. The auditory cortex and tinnitus - a review of animal and human studies. Eur J Neurosci 2015; 41:665-76. [DOI: 10.1111/ejn.12759] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/23/2014] [Accepted: 09/24/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Jos J. Eggermont
- Department of Physiology and Pharmacology; University of Calgary; Calgary AB Canada
- Department of Psychology; University of Calgary; 2500 University Drive N.W. Calgary AB T2N 1N4 Canada
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185
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Eggermont JJ, Tass PA. Maladaptive neural synchrony in tinnitus: origin and restoration. Front Neurol 2015; 6:29. [PMID: 25741316 PMCID: PMC4330892 DOI: 10.3389/fneur.2015.00029] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 02/03/2015] [Indexed: 11/14/2022] Open
Abstract
Tinnitus is the conscious perception of sound heard in the absence of physical sound sources external or internal to the body, reflected in aberrant neural synchrony of spontaneous or resting-state brain activity. Neural synchrony is generated by the nearly simultaneous firing of individual neurons, of the synchronization of membrane-potential changes in local neural groups as reflected in the local field potentials, resulting in the presence of oscillatory brain waves in the EEG. Noise-induced hearing loss, often resulting in tinnitus, causes a reorganization of the tonotopic map in auditory cortex and increased spontaneous firing rates and neural synchrony. Spontaneous brain rhythms rely on neural synchrony. Abnormal neural synchrony in tinnitus appears to be confined to specific frequency bands of brain rhythms. Increases in delta-band activity are generated by deafferented/deprived neuronal networks resulting from hearing loss. Coordinated reset (CR) stimulation was developed in order to specifically counteract such abnormal neuronal synchrony by desynchronization. The goal of acoustic CR neuromodulation is to desynchronize tinnitus-related abnormal delta-band oscillations. CR neuromodulation does not require permanent stimulus delivery in order to achieve long-lasting desynchronization or even a full-blown anti-kindling but may have cumulative effects, i.e., the effect of different CR epochs separated by pauses may accumulate. Unlike other approaches, acoustic CR neuromodulation does not intend to reduce tinnitus-related neuronal activity by employing lateral inhibition. The potential efficacy of acoustic CR modulation was shown in a clinical proof of concept trial, where effects achieved in 12 weeks of treatment delivered 4–6 h/day persisted through a preplanned 4-week therapy pause and showed sustained long-term effects after 10 months of therapy, leading to 75% responders.
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Affiliation(s)
- Jos J Eggermont
- Department of Physiology and Pharmacology, University of Calgary , Calgary, AB , Canada ; Department of Psychology, University of Calgary , Calgary, AB , Canada
| | - Peter A Tass
- Institute of Neuroscience and Medicine - Neuromodulation (INM-7), Research Center Jülich , Jülich , Germany ; Department of Neurosurgery, Stanford University , Stanford, CA , USA ; Department of Neuromodulation, University of Cologne , Cologne , Germany
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186
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Liu XP, Chen L. Forward acoustic masking enhances the auditory brainstem response in a diotic, but not dichotic, paradigm in salicylate-induced tinnitus. Hear Res 2015; 323:51-60. [PMID: 25668125 DOI: 10.1016/j.heares.2015.01.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 01/22/2015] [Accepted: 01/29/2015] [Indexed: 11/30/2022]
Abstract
We recently reported that forward acoustic masking can enhance the auditory brainstem response (ABR) in rats treated with a high dose of sodium salicylate (NaSal), a tinnitus inducer, when tested in open acoustic field (Liu and Chen, 2012, Brain Research 1485, 88-94). In the present study, we first replicated this experiment in closed acoustic field under two conditions: (1) the forward masker and the probe were presented to both ears (diotic paradigm); (2) the forward masker was presented to one ear and the probe to the other ear (dichotic paradigm). We found that only when the stimuli were presented by using the diotic, rather than the dichotic, paradigm could forward acoustic masking enhance the ABR in the rat treated with NaSal (300 mg/kg). The enhancement was obvious for ABR waves II and IV, but not for wave I, indicating a central origin. The enhancement occurred at the high frequencies (16, 24, 32 kHz) at which the animals demonstrated a tinnitus-like behavior as revealed by using the gap prepulse inhibition of acoustic startle paradigm. We then administered vigabatrin, a GABA transaminase inhibitor, in the animals to suppress NaSal-induced tinnitus. The vigabatrin treatment successfully prevented forward acoustic masking from enhancing the ABR. These findings demonstrate that the observed enhancement of ABRs by forward acoustic masking originates in the central auditory pathway ipsilateral to the stimulated ear. We propose that the enhancement is closely associated with NaSal-induced tinnitus.
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Affiliation(s)
- Xiao-Peng Liu
- Center for Biomedical Engineering, School of Information Science and Technology, University of Science and Technology of China, Hefei 230027, China
| | - Lin Chen
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China; Auditory Research Laboratory, University of Science and Technology of China, Hefei 230027, China.
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187
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188
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Eggermont JJ. Tinnitus and neural plasticity (Tonndorf lecture at XIth International Tinnitus Seminar, Berlin, 2014). Hear Res 2015; 319:1-11. [DOI: 10.1016/j.heares.2014.10.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/23/2014] [Accepted: 10/02/2014] [Indexed: 11/13/2022]
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189
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Noreña AJ, Mulders WHAM, Robertson D. Suppression of putative tinnitus-related activity by extra-cochlear electrical stimulation. J Neurophysiol 2015; 113:132-43. [DOI: 10.1152/jn.00580.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Studies on animals have shown that noise-induced hearing loss is followed by an increase of spontaneous firing at several stages of the central auditory system. This central hyperactivity has been suggested to underpin the perception of tinnitus. It was shown that decreasing cochlear activity can abolish the noise-induced central hyperactivity. This latter result further suggests that an approach consisting of reducing cochlear activity may provide a therapeutic avenue for tinnitus. In this context, extra-cochlear electric stimulation (ECES) may be a good candidate to modulate cochlear activity and suppress tinnitus. Indeed, it has been shown that a positive current applied at the round window reduces cochlear nerve activity and can suppress tinnitus reliably in tinnitus subjects. The present study investigates whether ECES with a positive current can abolish the noise-induced central hyperactivity, i.e., the putative tinnitus-related activity. Spontaneous and stimulus-evoked neural activity before, during and after ECES was assessed from single-unit recordings in the inferior colliculus of anesthetized guinea pigs. We found that ECES with positive current significantly decreases the spontaneous firing rate of neurons with high characteristic frequencies, whereas negative current produces the opposite effect. The effects of the ECES are absent or even reversed for neurons with low characteristic frequencies. Importantly, ECES with positive current had only a marginal effect on thresholds and tone-induced activity of collicular neurons, suggesting that the main action of positive current is to modulate the spontaneous firing. Overall, cochlear electrical stimulation may be a viable approach for suppressing some forms of (peripheral-dependent) tinnitus.
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Affiliation(s)
- A. J. Noreña
- Laboratory of Adaptive and Integrative Neuroscience, CNRS, and Aix-Marseille Université, Fédération de Recherche 3C, Marseille, France; and
| | | | - D. Robertson
- The University of Western Australia, Crawley, Western Australia, Australia
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190
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Offutt SJ, Ryan KJ, Konop AE, Lim HH. Suppression and facilitation of auditory neurons through coordinated acoustic and midbrain stimulation: investigating a deep brain stimulator for tinnitus. J Neural Eng 2014; 11:066001. [PMID: 25307351 PMCID: PMC4244264 DOI: 10.1088/1741-2560/11/6/066001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE The inferior colliculus (IC) is the primary processing center of auditory information in the midbrain and is one site of tinnitus-related activity. One potential option for suppressing the tinnitus percept is through deep brain stimulation via the auditory midbrain implant (AMI), which is designed for hearing restoration and is already being implanted in deaf patients who also have tinnitus. However, to assess the feasibility of AMI stimulation for tinnitus treatment we first need to characterize the functional connectivity within the IC. Previous studies have suggested modulatory projections from the dorsal cortex of the IC (ICD) to the central nucleus of the IC (ICC), though the functional properties of these projections need to be determined. APPROACH In this study, we investigated the effects of electrical stimulation of the ICD on acoustic-driven activity within the ICC in ketamine-anesthetized guinea pigs. MAIN RESULTS We observed ICD stimulation induces both suppressive and facilitatory changes across ICC that can occur immediately during stimulation and remain after stimulation. Additionally, ICD stimulation paired with broadband noise stimulation at a specific delay can induce greater suppressive than facilitatory effects, especially when stimulating in more rostral and medial ICD locations. SIGNIFICANCE These findings demonstrate that ICD stimulation can induce specific types of plastic changes in ICC activity, which may be relevant for treating tinnitus. By using the AMI with electrode sites positioned with the ICD and the ICC, the modulatory effects of ICD stimulation can be tested directly in tinnitus patients.
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Affiliation(s)
- Sarah J. Offutt
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
| | - Kellie J. Ryan
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
| | - Alexander E. Konop
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
| | - Hubert H. Lim
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, USA
- Department of Otolaryngology, Head and Neck Surgery, University of Minnesota, Minneapolis, USA
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191
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Pienkowski M, Tyler RS, Roncancio ER, Jun HJ, Brozoski T, Dauman N, Coelho CB, Andersson G, Keiner AJ, Cacace AT, Martin N, Moore BCJ. A review of hyperacusis and future directions: part II. Measurement, mechanisms, and treatment. Am J Audiol 2014; 23:420-36. [PMID: 25478787 DOI: 10.1044/2014_aja-13-0037] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 02/21/2014] [Indexed: 12/24/2022] Open
Abstract
PURPOSE Hyperacusis can be extremely debilitating, and at present, there is no cure. In this detailed review of the field, we consolidate present knowledge in the hope of facilitating future research. METHOD We review and reference the literature on hyperacusis and related areas. This is the 2nd of a 2-part review. RESULTS Hyperacusis encompasses a wide range of reactions to sounds, which can be grouped into the categories of excessive loudness, annoyance, fear, and pain. Reasonable approaches to assessing the different forms of hyperacusis are emerging, including brain-imaging studies. Researchers are only beginning to understand the many mechanisms at play, and valid animal models are still evolving. There are many counseling and sound-therapy approaches that some patients find helpful, but well-controlled studies are needed to measure their long-term efficacy and to test new approaches. CONCLUSIONS Hyperacusis can make life difficult in this increasingly noisy world, forcing sufferers to dramatically alter their work and social habits. We believe this is an opportune time to explore approaches to better understand and treat hyperacusis.
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Affiliation(s)
| | | | | | | | - Tom Brozoski
- Southern Illinois University School of Medicine, Springfield
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192
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Adjamian P. The application of electro- and magneto-encephalography in tinnitus research - methods and interpretations. Front Neurol 2014; 5:228. [PMID: 25431567 PMCID: PMC4230045 DOI: 10.3389/fneur.2014.00228] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 10/22/2014] [Indexed: 12/11/2022] Open
Abstract
In recent years, there has been a significant increase in the use of electroencephalography (EEG) and magnetoencephalography (MEG) to investigate changes in oscillatory brain activity associated with tinnitus with many conflicting results. Current view of the underlying mechanism of tinnitus is that it results from changes in brain activity in various structures of the brain as a consequence of sensory deprivation. This in turn gives rise to increased spontaneous activity and/or synchrony in the auditory centers but also involves modulation from non-auditory processes from structures of the limbic and paralimbic system. Some of the neural changes associated with tinnitus may be assessed non-invasively in human beings with MEG and EEG (M/EEG) in ways, which are superior to animal studies and other non-invasive imaging techniques. However, both MEG and EEG have their limitations and research results can be misinterpreted without appropriate consideration of these limitations. In this article, I intend to provide a brief review of these techniques, describe what the recorded signals reflect in terms of the underlying neural activity, and their strengths and limitations. I also discuss some pertinent methodological issues involved in tinnitus-related studies and conclude with suggestions to minimize possible discrepancies between results. The overall message is that while MEG and EEG are extremely useful techniques, the interpretation of results from tinnitus studies requires much caution given the individual variability in oscillatory activity and the limits of these techniques.
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193
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Auerbach BD, Rodrigues PV, Salvi RJ. Central gain control in tinnitus and hyperacusis. Front Neurol 2014; 5:206. [PMID: 25386157 PMCID: PMC4208401 DOI: 10.3389/fneur.2014.00206] [Citation(s) in RCA: 268] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 09/30/2014] [Indexed: 12/02/2022] Open
Abstract
Sensorineural hearing loss induced by noise or ototoxic drug exposure reduces the neural activity transmitted from the cochlea to the central auditory system. Despite a reduced cochlear output, neural activity from more central auditory structures is paradoxically enhanced at suprathreshold intensities. This compensatory increase in the central auditory activity in response to the loss of sensory input is referred to as central gain enhancement. Enhanced central gain is hypothesized to be a potential mechanism that gives rise to hyperacusis and tinnitus, two debilitating auditory perceptual disorders that afflict millions of individuals. This review will examine the evidence for gain enhancement in the central auditory system in response to cochlear damage. Further, it will address the potential cellular and molecular mechanisms underlying this enhancement and discuss the contribution of central gain enhancement to tinnitus and hyperacusis. Current evidence suggests that multiple mechanisms with distinct temporal and spectral profiles are likely to contribute to central gain enhancement. Dissecting the contributions of these different mechanisms at different levels of the central auditory system is essential for elucidating the role of central gain enhancement in tinnitus and hyperacusis and, most importantly, the development of novel treatments for these disorders.
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Affiliation(s)
- Benjamin D Auerbach
- Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, University at Buffalo, The State University of New York , Buffalo, NY , USA
| | - Paulo V Rodrigues
- Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, University at Buffalo, The State University of New York , Buffalo, NY , USA
| | - Richard J Salvi
- Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, University at Buffalo, The State University of New York , Buffalo, NY , USA
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194
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Lanting CP, de Kleine E, Langers DRM, van Dijk P. Unilateral tinnitus: changes in connectivity and response lateralization measured with FMRI. PLoS One 2014; 9:e110704. [PMID: 25329557 PMCID: PMC4203817 DOI: 10.1371/journal.pone.0110704] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 09/25/2014] [Indexed: 12/26/2022] Open
Abstract
Tinnitus is a percept of sound that is not related to an acoustic source outside the body. For many forms of tinnitus, mechanisms in the central nervous system are believed to play a role in the pathology. In this work we specifically assessed possible neural correlates of unilateral tinnitus. Functional magnetic resonance imaging (fMRI) was used to investigate differences in sound-evoked neural activity between controls, subjects with left-sided tinnitus, and subjects with right-sided tinnitus. We assessed connectivity patterns between auditory nuclei and the lateralization of the sound-evoked responses. Interestingly, these response characteristics did not relate to the laterality of tinnitus. The lateralization for left- or right ear stimuli, as expressed in a lateralization index, was considerably smaller in subjects with tinnitus compared to that in controls, reaching significance in the right primary auditory cortex (PAC) and the right inferior colliculus (IC). Reduced functional connectivity between the brainstem and the cortex was observed in subjects with tinnitus. These differences are consistent with two existing models that relate tinnitus to i) changes in the corticothalamic feedback loops or ii) reduced inhibitory effectiveness between the limbic system and the thalamus. The vermis of the cerebellum also responded to monaural sound in subjects with unilateral tinnitus. In contrast, no cerebellar response was observed in control subjects. This suggests the involvement of the vermis of the cerebellum in unilateral tinnitus.
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Affiliation(s)
- Cornelis P. Lanting
- Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
- Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen, Groningen, Netherlands
- * E-mail:
| | - Emile de Kleine
- Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
- Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen, Groningen, Netherlands
| | - Dave R. M. Langers
- Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
- National Institute for Health Research, Nottingham Hearing Biomedical Research Unit, School of Clinical Sciences, University of Nottingham, Queen’s Medical Centre, Nottingham, United Kingdom
| | - Pim van Dijk
- Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
- Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen, Groningen, Netherlands
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195
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Heeringa AN, Agterberg MJH, van Dijk P. Spontaneous behavior in noise and silence: a possible new measure to assess tinnitus in Guinea pigs. Front Neurol 2014; 5:207. [PMID: 25360130 PMCID: PMC4197645 DOI: 10.3389/fneur.2014.00207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 09/30/2014] [Indexed: 12/20/2022] Open
Abstract
This study describes two experiments that were conducted in search for a behavioral paradigm to test for tinnitus in guinea pigs. Conditioning paradigms are available to determine the presence of tinnitus in animals and are based on the assumption that tinnitus impairs their ability to detect silent intervals in continuous noise. Guinea pigs have not been subjected to these paradigms yet; therefore, we investigated whether guinea pigs could be conditioned in the two-way shuttle-box paradigm to respond to silent intervals in noise. Even though guinea pigs could be trained relatively easy to respond to the presence of a noise interval, training guinea pigs to silent intervals in noise was unsuccessful. Instead, it appeared that they became immobile when the continuous stimulus was suddenly stopped. This was confirmed by the next experiment, in which we subjected guinea pigs to alternating intervals of noise and silence with a random duration between 30 and 120 s. Indeed, guinea pigs were significantly longer immobile during silence compared to during noise. By interpreting immobility as a signature of perceiving silence, we hypothesized that the presence of tinnitus would reduce immobility in silence. Therefore, we unilaterally exposed one group of guinea pigs to an 11-kHz tone of 124 dB sound pressure level for 1 h. A subset of the exposed animals was significantly more active in silence, but also more active in noise, as compared to the control group. The increased mobility during silent intervals might represent tinnitus. However, the increased mobility in noise of this group implies that the observed behavior could have derived from, e.g., an overall increase in activity. Therefore, conducting validation experiments is very important before implementing this method as a new screening tool for tinnitus. Follow-up experiments are discussed to further elucidate the origin of the increased mobility in both silence and noise.
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Affiliation(s)
- Amarins N Heeringa
- Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen , Groningen , Netherlands ; Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen , Groningen , Netherlands
| | - Martijn J H Agterberg
- Department of Otorhinolaryngology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre , Nijmegen , Netherlands ; Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen , Nijmegen , Netherlands
| | - Pim van Dijk
- Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen , Groningen , Netherlands ; Graduate School of Medical Sciences (Research School of Behavioural and Cognitive Neurosciences), University of Groningen , Groningen , Netherlands
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196
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Minen MT, Camprodon J, Nehme R, Chemali Z. The neuropsychiatry of tinnitus: a circuit-based approach to the causes and treatments available. J Neurol Neurosurg Psychiatry 2014; 85:1138-44. [PMID: 24744443 DOI: 10.1136/jnnp-2013-307339] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Patients presenting with tinnitus commonly have neuropsychiatric symptoms with which physicians need to be familiar. We provide an overview of tinnitus, including its types and pathophysiology. We discuss how recent methods such as transcranial magnetic stimulation, positron emission tomography, MRI, magnetoencephalography and quantitative EEG improve our understanding of the pathophysiology of tinnitus and connect tinnitus to the neuropsychiatric symptoms. We then explain why treatment of the tinnitus patient falls within the purview of neuropsychiatry. Psychiatric problems such as depression, anxiety and personality disorders are discussed. We also discuss how stress, headache, cognitive processing speed and sleep disturbance are associated with tinnitus. Finally, we provide a brief overview of treatment options and discuss the efficacy of various medications, including benzodiazepines, antidepressants, antipsychotics and mood-stabilising agents, and various non-pharmacological treatment options, such as cognitive behavioural therapy, habituation therapy and acupuncture. We also discuss how brain stimulation therapies are being developed for the treatment of tinnitus. In conclusion, a review of the literature demonstrates the varied neuropsychiatric manifestations of tinnitus. Imaging studies help to explain the mechanism of the association. However, more research is needed to elucidate the neurocircuitry underlying the association.
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Affiliation(s)
- Mia T Minen
- Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts, USA Harvard Medical School, Boston, Massachusetts, USA
| | - Joan Camprodon
- Harvard Medical School, Boston, Massachusetts, USA Departments of Neurology and Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Romy Nehme
- Department of Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Zeina Chemali
- Harvard Medical School, Boston, Massachusetts, USA Departments of Neurology and Psychiatry, Massachusetts General Hospital, Boston, Massachusetts, USA Massachusetts Eye Ear Infirmary, Boston, Massachusetts, USA
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197
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Longenecker RJ, Chonko KT, Maricich SM, Galazyuk AV. Age effects on tinnitus and hearing loss in CBA/CaJ mice following sound exposure. SPRINGERPLUS 2014; 3:542. [PMID: 25279331 PMCID: PMC4177444 DOI: 10.1186/2193-1801-3-542] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 09/10/2014] [Indexed: 11/17/2022]
Abstract
Tinnitus is a maladaptive neuropathic condition that develops in humans and laboratory animals following auditory insult. In our previous study we demonstrated that sound exposure leads to development of behavioral evidence of tinnitus in a sample of exposed mice. However, this tinnitus mouse model did not account for long-term maladaptive plasticity or aging, factors that are commonly linked to the human tinnitus population. Therefore the same group of mice was monitored for tinnitus for 360 days post exposure. Tinnitus was assessed behaviorally by measuring gap-induced pre-pulse suppression of the acoustic startle (GPIAS). Cochlear histology was performed on both control (unexposed) and experimental mice to determine whether sound exposure caused any evident cochlear damage. We found that 360 days after exposure the vast majority of exposed mice exhibited similar gap detection deficits as detected at 84 days post exposure. These mice did not demonstrate significant loss of inner/outer hair cells or spiral ganglion neurons compared to the control sample. Lastly, we demonstrated that GPIAS deficits observed in exposed animals were unlikely exclusively caused by cochlear damage, but could be a result of central auditory maladaptive plasticity. We conclude that CBA/CaJ mice can be considered a good animal model to study the possible contribution of age effects on tinnitus development following auditory insult.
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Affiliation(s)
- Ryan J Longenecker
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH 44272 USA ; Kent State University, Kent, OH 44240 USA
| | - Kurt T Chonko
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106 USA
| | - Steve M Maricich
- Department of Pediatrics, Richard King Mellon Foundation Institute for Pediatric Research, University of Pittsburgh, Pittsburgh, PA 15224 USA
| | - Alexander V Galazyuk
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH 44272 USA
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198
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Aberrant spontaneous brain activity in chronic tinnitus patients revealed by resting-state functional MRI. NEUROIMAGE-CLINICAL 2014; 6:222-8. [PMID: 25379434 PMCID: PMC4215464 DOI: 10.1016/j.nicl.2014.09.011] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/12/2014] [Accepted: 09/13/2014] [Indexed: 11/24/2022]
Abstract
OBJECTIVE The neural mechanisms that give rise to the phantom sound of tinnitus are poorly understood. This study aims to investigate whether aberrant spontaneous brain activity exists in chronic tinnitus patients using resting-state functional magnetic resonance imaging (fMRI) technique. MATERIALS AND METHODS A total of 31 patients with chronic tinnitus patients and 32 healthy age-, sex-, and education-matched healthy controls were prospectively examined. Both groups had normal hearing thresholds. We calculated the amplitude of low-frequency fluctuations (ALFFs) of fMRI signals to measure spontaneous neuronal activity and detect the relationship between fMRI information and clinical data of tinnitus. RESULTS Compared with healthy controls, we observed significant increased ALFF within several selected regions including the right middle temporal gyrus (MTG), right superior frontal gyrus (SFG), and right angular gyrus; decreased ALFF was detected in the left cuneus, right middle occipital gyrus and bilateral thalamus. Moreover, tinnitus distress correlated positively with increased ALFF in right MTG and right SFG; tinnitus duration correlated positively with higher ALFF values in right SFG. CONCLUSIONS The present study confirms that chronic tinnitus patients have aberrant ALFF in many brain regions, which is associated with specific clinical tinnitus characteristics. ALFF disturbance in specific brain regions might be used to identify the neuro-pathophysiological mechanisms in chronic tinnitus patients.
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199
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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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200
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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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