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Cai R, Ling L, Ghimire M, Brownell KA, Caspary DM. Tinnitus-related increases in single-unit activity in awake rat auditory cortex correlate with tinnitus behavior. Hear Res 2024; 445:108993. [PMID: 38518392 DOI: 10.1016/j.heares.2024.108993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/04/2024] [Accepted: 03/10/2024] [Indexed: 03/24/2024]
Abstract
Tinnitus is known to affect 10-15 % of the population, severely impacting 1-2 % of those afflicted. Canonically, tinnitus is generally a consequence of peripheral auditory damage resulting in maladaptive plastic changes in excitatory/inhibitory homeostasis at multiple levels of the central auditory pathway as well as changes in diverse nonauditory structures. Animal studies of primary auditory cortex (A1) generally find tinnitus-related changes in excitability across A1 layers and differences between inhibitory neuronal subtypes. Changes due to sound-exposure include changes in spontaneous activity, cross-columnar synchrony, bursting and tonotopic organization. Few studies in A1 directly correlate tinnitus-related changes in neural activity to an individual animal's behavioral evidence of tinnitus. The present study used an established condition-suppression sound-exposure model of chronic tinnitus and recorded spontaneous and driven single-unit responses from A1 layers 5 and 6 of awake Long-Evans rats. A1 units recorded from animals with behavioral evidence of tinnitus showed significant increases in spontaneous and sound-evoked activity which directly correlated to the animal's tinnitus score. Significant increases in the number of bursting units, the number of bursts/minute and burst duration were seen for A1 units recorded from animals with behavioral evidence of tinnitus. The present A1 findings support prior unit recording studies in auditory thalamus and recent in vitro findings in this same animal model. The present findings are consistent with sensory cortical studies showing tinnitus- and neuropathic pain-related down-regulation of inhibition and increased excitation based on plastic neurotransmitter and potassium channel changes. Reducing A1 deep-layer tinnitus-related hyperactivity is a potential target for tinnitus pharmacotherapy.
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Affiliation(s)
- Rui Cai
- Department of Pharmacology, Southern Illinois University School of Medicine, PO Box 19629, Springfield, IL 62794-9629, United States
| | - Lynne Ling
- Department of Pharmacology, Southern Illinois University School of Medicine, PO Box 19629, Springfield, IL 62794-9629, United States
| | - Madan Ghimire
- Department of Pharmacology, Southern Illinois University School of Medicine, PO Box 19629, Springfield, IL 62794-9629, United States
| | - Kevin A Brownell
- Department of Pharmacology, Southern Illinois University School of Medicine, PO Box 19629, Springfield, IL 62794-9629, United States
| | - Donald M Caspary
- Department of Pharmacology, Southern Illinois University School of Medicine, PO Box 19629, Springfield, IL 62794-9629, United States.
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2
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Rezapour M, Akbari M, Dargahi L, Zibaii MI, Shahbazi A. The Auditory Brainstem Response (ABR) Test, Supplementary to Behavioral Tests for Evaluation of the Salicylate-Induced Tinnitus. Indian J Otolaryngol Head Neck Surg 2023; 75:6-15. [PMID: 37206728 PMCID: PMC10188764 DOI: 10.1007/s12070-022-03117-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 06/28/2022] [Indexed: 10/16/2022] Open
Abstract
Tinnitus is a symptom of various disorders that affects the quality of life of millions people. Given the significance of the access to an objective and non-invasive method for tinnitus detection, in this study the auditory brainstem response (ABR) electrophysiological test was used to diagnose salicylate-induced tinnitus, in parallel with common behavioral tests. Wistar rats were divided into saline (n = 7), and salicylate (n = 7) groups for behavioral tests, and salicylate group (n = 5) for the ABR test. The rats were evaluated by pre-pulse inhibition (PPI), gap pre-pulse inhibition of the acoustic startle (GPIAS), and ABR tests, at baseline, 14 and 62 h after salicylate (350 mg/kg) or vehicle injection. The mean percentage of GPIAS test was significantly reduced following salicylate administration, which confirms the induction of tinnitus. The ABR test results showed an increase in the hearing threshold at click and 8, 12, and 16 kHz tones. Moreover, a decline was observed in the latency ratio of II-I waves in all tone burst frequencies with the highest variation in 12 and 16 kHz as well as a decrement in the latency ratio of III-I and IV-I only in 12 and 16 kHz. ABR test is able to evaluate the salicylate induced tinnitus pitch and confirm the results of behavioral tinnitus tests. GPIAS reflexive response is dependent on brainstem circuits and the auditory cortex while, ABR test can demonstrate the function of the auditory brainstem in more details, and therefore, a combination of these two tests can offer a more accurate tinnitus evaluation. Graphical Abstract
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Affiliation(s)
- Mitra Rezapour
- Rehabilitation Research Center, Department of Audiology, School of Rehabilitation Sciences, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Mehdi Akbari
- Rehabilitation Research Center, Department of Audiology, School of Rehabilitation Sciences, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Leila Dargahi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Ali Shahbazi
- Cellular and Molecular Research Center, Iran University of Medical Sciences (IUMS), Tehran, Iran
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
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3
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Objective Detection of Tinnitus Based on Electrophysiology. Brain Sci 2022; 12:brainsci12081086. [PMID: 36009149 PMCID: PMC9406100 DOI: 10.3390/brainsci12081086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/29/2022] [Accepted: 08/12/2022] [Indexed: 11/24/2022] Open
Abstract
Tinnitus, a common disease in the clinic, is associated with persistent pain and high costs to society. Several aspects of tinnitus, such as the pathophysiology mechanism, effective treatment, objective detection, etc., have not been elucidated. Any change in the auditory pathway can lead to tinnitus. At present, there is no clear and unified mechanism to explain tinnitus, and the hypotheses regarding its mechanism include auditory plasticity theory, cortical reorganization theory, dorsal cochlear nucleus hypothesis, etc. Current theories on the mechanism of tinnitus mainly focus on the abnormal activity of the central nervous system. Unfortunately, there is currently a lack of objective diagnostic methods for tinnitus. Developing a method that can detect tinnitus objectively is crucial, only in this way can we identify whether the patient really suffers from tinnitus in the case of cognitive impairment or medical disputes and the therapeutic effect of tinnitus. Electrophysiological investigations have prompted the development of an objective detection of tinnitus by potentials recorded in the auditory pathway. However, there is no objective indicator with sufficient sensitivity and specificity to diagnose tinnitus at present. Based on recent findings of studies with various methods, possible electrophysiological approaches to detect the presence of tinnitus have been summarized. We analyze the change of neural activity throughout the auditory pathway in tinnitus subjects and in patients with tinnitus of varying severity to find available parameters in these methods, which is helpful to further explore the feasibility of using electrophysiological methods for the objective detection of tinnitus.
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Chen M, Min S, Zhang C, Hu X, Li S. Using Extracochlear Multichannel Electrical Stimulation to Relieve Tinnitus and Reverse Tinnitus-Related Auditory-Somatosensory Plasticity in the Cochlear Nucleus. Neuromodulation 2021; 25:1338-1350. [PMID: 34346133 DOI: 10.1111/ner.13506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/15/2021] [Accepted: 06/29/2021] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Tinnitus has no reliable cure but may be significantly relieved by the usage of cochlear implants. However, not all tinnitus patients necessitate cochlear implantation that can impair hearing. This study was to investigate whether a novel extracochlear electrical stimulation (EES) strategy could relieve tinnitus of guinea pigs without hearing impairment, and the roles of auditory-somatosensory plasticity in the cochlear nucleus in the tinnitus relief. MATERIALS AND METHODS We used a novel four-electrode extracochlear implant to electrically stimulate the cochlea of tinnitus guinea pigs. Tinnitus was assessed by the gap-prepulse inhibition of the acoustic startle reflex (GPIAS) ratios and the tinnitus index. The plasticity of auditory and somatosensory innervation in the different subdivisions of cochlear nucleus was evaluated by immunostaining of vesicular glutamate transporter 1 (VGLUT1) and VGLUT2, respectively. RESULTS The EES induced significant decreases of GPIAS ratios and the tinnitus index of tinnitus guinea pigs, indicating reductions of tinnitus behavioral manifestations. Meanwhile, the EES reversed the abnormal auditory-somatosensory innervation in the cochlear nucleus of tinnitus animals but did not change the hearing and the numbers of inner hair cell synapses. CONCLUSIONS This study demonstrated that the novel EES strategy could effectively relieve tinnitus without impairment to hearing and cochlear structure of tinnitus animals. The reversal of tinnitus-related auditory-somatosensory plasticity in the cochlear nucleus was correlated with the tinnitus relief induced by the EES.
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Affiliation(s)
- Min Chen
- ENT Institute and Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, 200031, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Shiyao Min
- ENT Institute and Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, 200031, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Chen Zhang
- ENT Institute and Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, 200031, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Xuerui Hu
- ENT Institute and Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, 200031, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Shufeng Li
- ENT Institute and Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, 200031, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
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5
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Salicylate decreases the spontaneous firing rate of guinea pig auditory nerve fibres. Neurosci Lett 2021; 747:135705. [PMID: 33548408 PMCID: PMC7957321 DOI: 10.1016/j.neulet.2021.135705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 01/26/2021] [Accepted: 01/29/2021] [Indexed: 02/03/2023]
Abstract
Spontaneous firing rates were recorded from single auditory fibres in vivo. Salicylate was injected at 350 mg/kg by the subcutaneous route. Median firing rate decreased by 32 spikes/s in nerve fibres after salicylate injection. The high spontaneous rate fibres (type 1A) showed the main reduction.
Tinnitus has similarities to chronic neuropathic pain where there are changes in the firing rate of different types of afferent neurons. We postulated that one possible cause of tinnitus is a change in the distribution of spontaneous firing rates in at least one type of afferent auditory nerve fibre in anaesthetised guinea pigs. In control animals there was a bimodal distribution of spontaneous rates, but the position of the second mode was different depending upon whether the fibres responded best to high (> 4 kHz) or low (≤4 kHz) frequency tonal stimulation. The simplest and most reliable way of inducing tinnitus in experimental animals is to administer a high dose of sodium salicylate. The distribution of the spontaneous firing rates was different when salicylate (350 mg/kg) was administered, even when the sample was matched for the distribution of characteristic frequencies in the control population. The proportion of medium spontaneous rate fibres (MSR, 1≤ spikes/s ≤20) increased while the proportion of the highest, high spontaneous firing rate fibres (HSR, > 80 spikes/s) decreased following salicylate. The median rate fell from 64.7 spikes/s (control) to 35.4 spikes/s (salicylate); a highly significant change (Kruskal-Wallis test p < 0.001). When the changes were compared with various models of statistical probability, the most accurate model was one where most HSR fibres decreased their firing rate by 32 spikes/s. Thus, we have shown a reduction in the firing rate of HSR fibres that may be related to tinnitus.
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6
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Noise Exposure Alters Glutamatergic and GABAergic Synaptic Connectivity in the Hippocampus and Its Relevance to Tinnitus. Neural Plast 2021; 2021:8833087. [PMID: 33510780 PMCID: PMC7822664 DOI: 10.1155/2021/8833087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 12/16/2020] [Accepted: 12/30/2020] [Indexed: 01/08/2023] Open
Abstract
Accumulating evidence implicates a role for brain structures outside the ascending auditory pathway in tinnitus, the phantom perception of sound. In addition to other factors such as age-dependent hearing loss, high-level sound exposure is a prominent cause of tinnitus. Here, we examined how noise exposure altered the distribution of excitatory and inhibitory synaptic inputs in the guinea pig hippocampus and determined whether these changes were associated with tinnitus. In experiment one, guinea pigs were overexposed to unilateral narrow-band noise (98 dB SPL, 2 h). Two weeks later, the density of excitatory (VGLUT-1/2) and inhibitory (VGAT) synaptic terminals in CA1, CA3, and dentate gyrus hippocampal subregions was assessed by immunohistochemistry. Overall, VGLUT-1 density primarily increased, while VGAT density decreased significantly in many regions. Then, to assess whether the noise-induced alterations were persistent and related to tinnitus, experiment two utilized a noise-exposure paradigm shown to induce tinnitus and assessed tinnitus development which was assessed using gap-prepulse inhibition of the acoustic startle (GPIAS). Twelve weeks after sound overexposure, changes in excitatory synaptic terminal density had largely recovered regardless of tinnitus status, but the recovery of GABAergic terminal density was dramatically different in animals expressing tinnitus relative to animals resistant to tinnitus. In resistant animals, inhibitory synapse density recovered to preexposure levels, but in animals expressing tinnitus, inhibitory synapse density remained chronically diminished. Taken together, our results suggest that noise exposure induces striking changes in the balance of excitatory and inhibitory synaptic inputs throughout the hippocampus and reveal a potential role for rebounding inhibition in the hippocampus as a protective factor leading to tinnitus resilience.
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7
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Ku Y, Kim DY, Kwon C, Noh TS, Park MK, Lee JH, Oh SH, Kim HC, Suh MW. Effect of age on the gap-prepulse inhibition of the cortical N1-P2 complex in humans as a step towards an objective measure of tinnitus. PLoS One 2020; 15:e0241136. [PMID: 33152745 PMCID: PMC7644010 DOI: 10.1371/journal.pone.0241136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/08/2020] [Indexed: 11/18/2022] Open
Abstract
The gap-prepulse inhibition of the acoustic startle reflex has been widely used as a behavioral method for tinnitus screening in animal studies. The cortical-evoked potential gap-induced inhibition has also been investigated in animals as well as in human subjects. The present study aimed to investigate the effect of age on the cortical N1-P2 complex in the gap-prepulse inhibition paradigm. Fifty-seven subjects, aged 20 to 68 years, without continuous tinnitus, were tested with two effective gap conditions (embedded gap of 50- or 20-ms duration). Retest sessions were performed within one month. A significant gap-induced inhibition of the N1-P2 complex was found in both gap durations. Age differently affected the inhibition, depending on gap duration. With a 50-ms gap, the inhibition decreased significantly with the increase in age. This age-inhibition relationship was not found when using a 20-ms gap. The results were reproducible in the retest session. Our findings suggest that the interaction between age and gap duration should be considered when applying the gap-induced inhibition of the cortical-evoked potential as an objective measure of tinnitus in human subjects. Further studies with tinnitus patients are warranted to identify gap duration that would minimize the effects of age and maximize the difference in the inhibition between those with and without tinnitus.
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Affiliation(s)
- Yunseo Ku
- Department of Biomedical Engineering, College of Medicine, Chungnam National University, Daejeon, Korea
| | - Do Youn Kim
- Interdisciplinary Program in Bioengineering, Graduate School, Seoul National University, Seoul, Korea
| | - Chiheon Kwon
- Interdisciplinary Program in Bioengineering, Graduate School, Seoul National University, Seoul, Korea
| | - Tae Soo Noh
- Department of Otorhinolaryngology- Head and Neck Surgery, Seoul National University Hospital, Seoul, Korea
| | - Moo Kyun Park
- Department of Otorhinolaryngology- Head and Neck Surgery, Seoul National University Hospital, Seoul, Korea
| | - Jun Ho Lee
- Department of Otorhinolaryngology- Head and Neck Surgery, Seoul National University Hospital, Seoul, Korea
| | - Seung Ha Oh
- Department of Otorhinolaryngology- Head and Neck Surgery, Seoul National University Hospital, Seoul, Korea
| | - Hee Chan Kim
- Interdisciplinary Program in Bioengineering, Graduate School, Department of Biomedical Engineering, College of Medicine, Seoul, Korea
- Institute of Medical & Biological Engineering, Medical Research Center, Seoul National University, Seoul, Korea
| | - Myung-Whan Suh
- Department of Otorhinolaryngology- Head and Neck Surgery, Seoul National University Hospital, Seoul, Korea
- * E-mail:
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8
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Hockley A, Berger JI, Palmer AR, Wallace MN. Nitric oxide increases gain in the ventral cochlear nucleus of guinea pigs with tinnitus. Eur J Neurosci 2020; 52:4057-4080. [PMID: 32686192 DOI: 10.1111/ejn.14913] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 07/10/2020] [Accepted: 07/11/2020] [Indexed: 12/21/2022]
Abstract
Previous work has led to the hypothesis that, during the production of noise-induced tinnitus, higher levels of nitric oxide (NO), in the ventral cochlear nucleus (VCN), increase the gain applied to a reduced input from the cochlea. To test this hypothesis, we noise-exposed 26 guinea pigs, identified evidence of tinnitus in 12 of them and then compared the effects of an iontophoretically applied NO donor or production inhibitor on VCN single unit activity. We confirmed that the mean driven firing rate for the tinnitus and control groups was the same while it had fallen in the non-tinnitus group. By contrast, the mean spontaneous rate had increased for the tinnitus group relative to the control group, while it remained the same for the non-tinnitus group. A greater proportion of units responded to exogenously applied NO in the tinnitus (56%) and non-tinnitus groups (71%) than a control population (24%). In the tinnitus group, endogenous NO facilitated the driven firing rate in 37% (7/19) of neurons and appeared to bring the mean driven rate back up to control levels by a mechanism involving N-methyl-D-aspartic acid (NMDA) receptors. By contrast, in the non-tinnitus group, endogenous NO only facilitated the driven firing rate in 5% (1/22) of neurons and there was no facilitation of driven rate in the control group. The effects of endogenous NO on spontaneous activity were unclear. These results suggest that NO is involved in increasing the gain applied to driven activity, but other factors are also involved in the increase in spontaneous activity.
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Affiliation(s)
- Adam Hockley
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK.,School of Life Sciences, University of Nottingham, Nottingham, UK.,Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Joel I Berger
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK.,Department of Neurosurgery, University of Iowa, Iowa City, IA, USA
| | - Alan R Palmer
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK.,Hearing Sciences, School of Medicine, University of Nottingham, Nottingham, UK
| | - Mark N Wallace
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK.,Hearing Sciences, School of Medicine, University of Nottingham, Nottingham, UK
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9
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Duda V, Scully O, Baillargeon MS, Hébert S. Does Tinnitus Fill in the Gap Using Electrophysiology? A Scoping Review. Otolaryngol Clin North Am 2020; 53:563-582. [PMID: 32334868 DOI: 10.1016/j.otc.2020.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The results showed a trend of increased post-gap amplitudes and reduced gap salience; however, the small number of articles yield and limited consensus prohibit any conclusions for clinical use. Nevertheless, gap-induced EPs may be further explored as a potential tool for tinnitus detection.
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Affiliation(s)
- Victoria Duda
- École d'orthophonie et d'audiologie, Faculty of Medicine, Université de Montréal, Pavillon 7077, Parc, C.P. 6128, Succ. Centre-ville, Montreal H3C 3J7, Canada
| | - Olivia Scully
- École d'orthophonie et d'audiologie, Faculty of Medicine, Université de Montréal, Pavillon 7077, Parc, C.P. 6128, Succ. Centre-ville, Montreal H3C 3J7, Canada
| | - Marie-Sarah Baillargeon
- École d'orthophonie et d'audiologie, Faculty of Medicine, Université de Montréal, Pavillon 7077, Parc, C.P. 6128, Succ. Centre-ville, Montreal H3C 3J7, Canada
| | - Sylvie Hébert
- École d'orthophonie et d'audiologie, Faculty of Medicine, Université de Montréal, Pavillon 7077, Parc, C.P. 6128, Succ. Centre-ville, Montreal H3C 3J7, Canada; International Laboratory for Brain, Music and Sound Research (BRAMS), Outremont, Quebec, Canada.
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10
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Zhang L, Wu C, Martel DT, West M, Sutton MA, Shore SE. Remodeling of cholinergic input to the hippocampus after noise exposure and tinnitus induction in Guinea pigs. Hippocampus 2019; 29:669-682. [PMID: 30471164 PMCID: PMC7357289 DOI: 10.1002/hipo.23058] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/23/2018] [Accepted: 11/03/2018] [Indexed: 01/12/2023]
Abstract
Here, we investigate remodeling of hippocampal cholinergic inputs after noise exposure and determine the relevance of these changes to tinnitus. To assess the effects of noise exposure on the hippocampus, guinea pigs were exposed to unilateral noise for 2 hr and 2 weeks later, immunohistochemistry was performed on hippocampal sections to examine vesicular acetylcholine transporter (VAChT) expression. To evaluate whether the changes in VAChT were relevant to tinnitus, another group of animals was exposed to the same noise band twice to induce tinnitus, which was assessed using gap-prepulse Inhibition of the acoustic startle (GPIAS) 12 weeks after the first noise exposure, followed by immunohistochemistry. Acoustic Brainstem Response (ABR) thresholds were elevated immediately after noise exposure for all experimental animals but returned to baseline levels several days after noise exposure. ABR wave I amplitude-intensity functions did not show any changes after 2 or 12 weeks of recovery compared to baseline levels. In animals assessed 2-weeks following noise-exposure, hippocampal VAChT puncta density decreased on both sides of the brain by 20-60% in exposed animals. By 12 weeks following the initial noise exposure, changes in VAChT puncta density largely recovered to baseline levels in exposed animals that did not develop tinnitus, but remained diminished in animals that developed tinnitus. These tinnitus-specific changes were particularly prominent in hippocampal synapse-rich layers of the dentate gyrus and areas CA3 and CA1, and VAChT density in these regions negatively correlated with tinnitus severity. The robust changes in VAChT labeling in the hippocampus 2 weeks after noise exposure suggest involvement of this circuitry in auditory processing. After chronic tinnitus induction, tinnitus-specific changes occurred in synapse-rich layers of the hippocampus, suggesting that synaptic processing in the hippocampus may play an important role in the pathophysiology of tinnitus.
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Affiliation(s)
- Liqin Zhang
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
- Molecular & Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, Michigan, USA
- Xiangya Medical School, Central South University, Changsha, Hunan, China
| | - Calvin Wu
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
| | - David T. Martel
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Michael West
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
| | - Michael A. Sutton
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
- Molecular & Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, Michigan, USA
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
- Correspondence to: Michael A. Sutton, Molecular and Behavioral Neuroscience Institute, 5067, BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA. Tel: 734-615-2445; ; Susan E. Shore, Kresge Hearing Research Institute, 5434, Medical Science Building, 1100 W. Medical Center Drive, Ann Arbor, MI 48109, USA. Tel: 734-647-2116;
| | - Susan E. Shore
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
- Correspondence to: Michael A. Sutton, Molecular and Behavioral Neuroscience Institute, 5067, BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA. Tel: 734-615-2445; ; Susan E. Shore, Kresge Hearing Research Institute, 5434, Medical Science Building, 1100 W. Medical Center Drive, Ann Arbor, MI 48109, USA. Tel: 734-647-2116;
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11
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Pienkowski M. Rationale and Efficacy of Sound Therapies for Tinnitus and Hyperacusis. Neuroscience 2019; 407:120-134. [DOI: 10.1016/j.neuroscience.2018.09.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/05/2018] [Accepted: 09/07/2018] [Indexed: 12/20/2022]
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12
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Wilson CA, Berger JI, de Boer J, Sereda M, Palmer AR, Hall DA, Wallace MN. Gap-induced inhibition of the post-auricular muscle response in humans and guinea pigs. Hear Res 2019; 374:13-23. [PMID: 30685571 PMCID: PMC6408328 DOI: 10.1016/j.heares.2019.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 12/14/2018] [Accepted: 01/15/2019] [Indexed: 12/11/2022]
Abstract
A common method for measuring changes in temporal processing sensitivity in both humans and animals makes use of GaP-induced Inhibition of the Acoustic Startle (GPIAS). It is also the basis of a common method for detecting tinnitus in rodents. However, the link to tinnitus has not been properly established because GPIAS has not yet been used to objectively demonstrate tinnitus in humans. In guinea pigs, the Preyer (ear flick) myogenic reflex is an established method for measuring the acoustic startle for the GPIAS test, while in humans, it is the eye-blink reflex. Yet, humans have a vestigial remnant of the Preyer reflex, which can be detected by measuring skin surface potentials associated with the Post-Auricular Muscle Response (PAMR). A similar electrical potential can be measured in guinea pigs and we aimed to show that the PAMR could be used to demonstrate GPIAS in both species. In guinea pigs, we compare the GPIAS measured using the pinna movement of the Preyer reflex and the electrical potential of the PAMR to demonstrate that the two are at least equivalent. In humans, we establish for the first time that the PAMR provides a reliable way of measuring GPIAS that is a pure acoustic alternative to the multimodal eye-blink reflex. Further exploratory tests showed that while eye gaze position influenced the size of the PAMR response, it did not change the degree of GPIAS. Our findings confirm that the PAMR is a sensitive method for measuring GPIAS and suggest that it may allow direct comparison of temporal processing between humans and animals and may provide a basis for an objective test of tinnitus. Myogenic potentials from the guinea pig pinna show gap induced pre-pulse inhibition. Startle inhibition is also shown by gaps in background noise using the Preyer reflex. Startle potentials recorded behind the human pinna show gap-induced inhibition. Human post-auricular muscle potentials may form an objective test for tinnitus.
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Affiliation(s)
- Caroline A Wilson
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK
| | - Joel I Berger
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK
| | - Jessica de Boer
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK
| | - Magdalena Sereda
- Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK; National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Ropewalk House, 113 The Ropewalk, Nottingham, UK
| | - Alan R Palmer
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK
| | - Deborah A Hall
- Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK; National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Ropewalk House, 113 The Ropewalk, Nottingham, UK; Nottingham University Hospitals NHS Trust, Queens Medical Centre, Derby Road, Nottingham, NG7 2UH, UK; University of Nottingham Malaysia, Jalan Broga, 43500, Semeniyh, Selangor Darul Ehsan, Malaysia
| | - Mark N Wallace
- Medical Research Council Institute of Hearing Research, School of Medicine, University of Nottingham, Nottingham, UK; Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK.
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Paul BT, Schoenwiesner M, Hébert S. Towards an objective test of chronic tinnitus: Properties of auditory cortical potentials evoked by silent gaps in tinnitus-like sounds. Hear Res 2018; 366:90-98. [DOI: 10.1016/j.heares.2018.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 04/11/2018] [Accepted: 04/12/2018] [Indexed: 10/17/2022]
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