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Bigras C, Villatte B, Duda V, Hébert S. The electrophysiological markers of hyperacusis: a scoping review. Int J Audiol 2022:1-11. [PMID: 35549972 DOI: 10.1080/14992027.2022.2070083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Hyperacusis is known as a reduced tolerance to sounds perceived as normal to the majority of the population. There is currently no agreed definition, diagnostic tool, or objective measure of its occurrence. The purpose of this review is to catalogue the research to date on the use of auditory evoked potentials (AEP) to assess hyperacusis. DESIGN A step-by-step methodology was conducted following guidelines. Four databases were searched. A total of 3343 papers were identified. A final yield of 35 articles were retained for analysis. RESULTS The analysis identified four types of aetiologies to describe the hyperacusic population in AEP studies; developmental disorders (n = 19), neurological disorders (n = 3), induced hearing damage (n = 8) and idiopathic aetiology (n = 5). Electrophysiological measures were of short (n = 16), middle (n = 13) and long (n = 19) latencies, believed to reflect the activity of the ascending and descending pathways of the auditory system from periphery to cortex. CONCLUSIONS The results of this review revealed the potential use of electrophysiological measures for further understanding the mechanisms of hyperacusis. However, according to the disparity of concepts to define hyperacusis, definitions and populations need to be clarified before biomarkers specific to hyperacusis can be identified.
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Affiliation(s)
- Charlotte Bigras
- School of Speech-Language Pathology and Audiology, Université de Montréal, Montreal, Canada.,Center of Research on Brain, Language and Music (CRBLM), Montreal, Canada
| | - Bérangère Villatte
- School of Speech-Language Pathology and Audiology, Université de Montréal, Montreal, Canada.,Center of Research on Brain, Language and Music (CRBLM), Montreal, Canada
| | - Victoria Duda
- School of Speech-Language Pathology and Audiology, Université de Montréal, Montreal, Canada.,Centre de recherche interdisciplinaire en réadaptation (CRIR), Montreal, Canada
| | - Sylvie Hébert
- School of Speech-Language Pathology and Audiology, Université de Montréal, Montreal, Canada.,Center of Research on Brain, Language and Music (CRBLM), Montreal, Canada
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2
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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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3
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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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4
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Hayes SH, Schormans AL, Sigel G, Beh K, Herrmann B, Allman BL. Uncovering the contribution of enhanced central gain and altered cortical oscillations to tinnitus generation. Prog Neurobiol 2020; 196:101893. [PMID: 32783988 DOI: 10.1016/j.pneurobio.2020.101893] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/20/2020] [Accepted: 08/02/2020] [Indexed: 12/22/2022]
Abstract
Various theories and their associated mechanisms have been proposed as the neural basis of phantom sound perception (tinnitus), including central gain enhancement and altered cortical oscillations. However, it remains unknown whether these cortical changes directly cause tinnitus, or simply coexist with the phantom percept. Using chronically-implanted electrodes and drug delivery cannulae in rats, we examined whether enhanced central gain and cortical oscillations are consistent across different tinnitus induction methods (noise exposure; salicylate), and if directly-inducing enhanced central gain or altered cortical oscillations via pharmacologic manipulation of inhibition along the auditory pathway would cause behavioral evidence of tinnitus. We show that, while there appeared to be no clear link between tinnitus and the presence of enhanced sound-evoked cortical activity or altered spontaneous cortical oscillations, pharmacologic impairment of GABAergic neurotransmission in the auditory cortex was sufficient to cause tinnitus; collective findings which further advance our understanding of the neural basis of tinnitus.
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Affiliation(s)
- Sarah H Hayes
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, N6A 3K7, Canada.
| | - Ashley L Schormans
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Gregory Sigel
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Krystal Beh
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Björn Herrmann
- Department of Psychology, Brain and Mind Institute, The University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Brian L Allman
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, N6A 3K7, Canada
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5
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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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6
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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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7
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Hockley A, Berger JI, Smith PA, Palmer AR, Wallace MN. Nitric oxide regulates the firing rate of neuronal subtypes in the guinea pig ventral cochlear nucleus. Eur J Neurosci 2019; 51:963-983. [PMID: 31494975 PMCID: PMC7078996 DOI: 10.1111/ejn.14572] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 08/20/2019] [Accepted: 08/29/2019] [Indexed: 12/21/2022]
Abstract
The gaseous free radical, nitric oxide (NO) acts as a ubiquitous neuromodulator, contributing to synaptic plasticity in a complex way that can involve either long term potentiation or depression. It is produced by neuronal nitric oxide synthase (nNOS) which is presynaptically expressed and also located postsynaptically in the membrane and cytoplasm of a subpopulation of each major neuronal type in the ventral cochlear nucleus (VCN). We have used iontophoresis in vivo to study the effect of the NOS inhibitor L‐NAME (L‐NG‐Nitroarginine methyl ester) and the NO donors SIN‐1 (3‐Morpholinosydnonimine hydrochloride) and SNOG (S‐Nitrosoglutathione) on VCN units under urethane anaesthesia. Collectively, both donors produced increases and decreases in driven and spontaneous firing rates of some neurones. Inhibition of endogenous NO production with L‐NAME evoked a consistent increase in driven firing rates in 18% of units without much effect on spontaneous rate. This reduction of gain produced by endogenous NO was mirrored when studying the effect of L‐NAME on NMDA(N‐Methyl‐D‐aspartic acid)‐evoked excitation, with 30% of units showing enhanced NMDA‐evoked excitation during L‐NAME application (reduced NO levels). Approximately 25% of neurones contain nNOS and the NO produced can modulate the firing rate of the main principal cells: medium stellates (choppers), large stellates (onset responses) and bushy cells (primary‐like responses). The main endogenous role of NO seems to be to partly suppress driven firing rates associated with NMDA channel activity but there is scope for it to increase neural gain if there were a pathological increase in its production following hearing loss.
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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
| | - Paul A Smith
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - 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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8
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Morse K, Vander Werff KR. Comparison of Silent Gap in Noise Cortical Auditory Evoked Potentials in Matched Tinnitus and No-Tinnitus Control Subjects. Am J Audiol 2019; 28:260-273. [PMID: 31184965 DOI: 10.1044/2018_aja-18-0074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Purpose Previous research suggests the existence of gap detection impairments because of tinnitus. The current study aimed to determine whether there was objective evidence of gap impairment in individuals with tinnitus by recording silent gap in white noise cortical auditory evoked potentials (CAEPs) in a chronic tinnitus group and a no-tinnitus group. The results were compared to previous gap-evoked potential and behavioral gap detection studies. Method Chronic tinnitus and no-tinnitus groups were formed by matching pairs of subjects ( n = 26) based on age, gender, and hearing thresholds. Behaviorally determined gap detection thresholds were used to define the electrophysiological gap duration conditions of subthreshold, threshold, and suprathreshold gaps in white noise. Amplitude, latency, and area of the CAEP were analyzed by group and condition using mixed-model analyses of variance. Results Across all participants, as the duration of the gap increased, amplitude and area of the CAEP increased. There were no significant differences by tinnitus status between groups for any outcome measures, except for a significant interaction between group and gap duration for P1 latency. Conclusions Silent gap-evoked CAEPs can be recorded in adults with and without tinnitus. Amplitude and area were sensitive to gap duration across groups; latency was not. Contrary to hypotheses, there was little evidence supporting differences in gap-evoked CAEPs between the tinnitus and control groups. Stimulus and other factors that may have contributed to the lack of a group difference in the current study are discussed, as well as implications for future studies of objective measures of tinnitus perception. Supplemental Material https://doi.org/10.23641/asha.7822601.
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Affiliation(s)
- Kenneth Morse
- Department of Communication Sciences and Disorders, Syracuse University, New York
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9
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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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10
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Berger JI, Owen W, Wilson CA, Hockley A, Coomber B, Palmer AR, Wallace MN. Gap-induced reductions of evoked potentials in the auditory cortex: A possible objective marker for the presence of tinnitus in animals. Brain Res 2017; 1679:101-108. [PMID: 29191772 PMCID: PMC5780299 DOI: 10.1016/j.brainres.2017.11.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/09/2017] [Accepted: 11/23/2017] [Indexed: 01/03/2023]
Abstract
Gap-suppression of startle responses is regularly used as a measure for tinnitus. We studied this phenomenon in auditory cortical evoked potentials in awake animals. Gap-suppression of evoked potentials was also examined following noise exposure. 120 dB SPL noise exposure, but not 105 dB, resulted in deficits in gap-suppression. Results are discussed in the context of a potential correlate of tinnitus.
Animal models of tinnitus are essential for determining the underlying mechanisms and testing pharmacotherapies. However, there is doubt over the validity of current behavioural methods for detecting tinnitus. Here, we applied a stimulus paradigm widely used in a behavioural test (gap-induced inhibition of the acoustic startle reflex GPIAS) whilst recording from the auditory cortex, and showed neural response changes that mirror those found in the behavioural tests. We implanted guinea pigs (GPs) with electrocorticographic (ECoG) arrays and recorded baseline auditory cortical responses to a startling stimulus. When a gap was inserted in otherwise continuous background noise prior to the startling stimulus, there was a clear reduction in the subsequent evoked response (termed gap-induced reductions in evoked potentials; GIREP), suggestive of a neural analogue of the GPIAS test. We then unilaterally exposed guinea pigs to narrowband noise (left ear; 8–10 kHz; 1 h) at one of two different sound levels – either 105 dB SPL or 120 dB SPL – and recorded the same responses seven-to-ten weeks following the noise exposure. Significant deficits in GIREP were observed for all areas of the auditory cortex (AC) in the 120 dB-exposed GPs, but not in the 105 dB-exposed GPs. These deficits could not simply be accounted for by changes in response amplitudes. Furthermore, in the contralateral (right) caudal AC we observed a significant increase in evoked potential amplitudes across narrowband background frequencies in both 105 dB and 120 dB-exposed GPs. Taken in the context of the large body of literature that has used the behavioural test as a demonstration of the presence of tinnitus, these results are suggestive of objective neural correlates of the presence of noise-induced tinnitus and hyperacusis.
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Affiliation(s)
- Joel I Berger
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - William Owen
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Caroline A Wilson
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Adam Hockley
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Ben Coomber
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Alan R Palmer
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Mark N Wallace
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham NG7 2RD, UK
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11
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Berger JI, Coomber B, Hill S, Alexander SPH, Owen W, Palmer AR, Wallace MN. Effects of the cannabinoid CB 1 agonist ACEA on salicylate ototoxicity, hyperacusis and tinnitus in guinea pigs. Hear Res 2017; 356:51-62. [PMID: 29108871 PMCID: PMC5714060 DOI: 10.1016/j.heares.2017.10.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 10/09/2017] [Accepted: 10/30/2017] [Indexed: 11/25/2022]
Abstract
Cannabinoids have been suggested as a therapeutic target for a variety of brain disorders. Despite the presence of their receptors throughout the auditory system, little is known about how cannabinoids affect auditory function. We sought to determine whether administration of arachidonyl-2′-chloroethylamide (ACEA), a highly-selective CB1 agonist, could attenuate a variety of auditory effects caused by prior administration of salicylate, and potentially treat tinnitus. We recorded cortical resting-state activity, auditory-evoked cortical activity and auditory brainstem responses (ABRs), from chronically-implanted awake guinea pigs, before and after salicylate + ACEA. Salicylate-induced reductions in click-evoked ABR amplitudes were smaller in the presence of ACEA, suggesting that the ototoxic effects of salicylate were less severe. ACEA also abolished salicylate-induced changes in cortical alpha band (6–10 Hz) oscillatory activity. However, salicylate-induced increases in cortical evoked activity (suggestive of the presence of hyperacusis) were still present with salicylate + ACEA. ACEA administered alone did not induce significant changes in either ABR amplitudes or oscillatory activity, but did increase cortical evoked potentials. Furthermore, in two separate groups of non-implanted animals, we found no evidence that ACEA could reverse behavioural identification of salicylate- or noise-induced tinnitus. Together, these data suggest that while ACEA may be potentially otoprotective, selective CB1 agonists are not effective in diminishing the presence of tinnitus or hyperacusis. CB1 agonist (ACEA) effects were assessed in awake guinea pigs following salicylate. Salicylate-induced decreases in brainstem response amplitudes were tempered by ACEA. Decreases in alpha band oscillations were not evident following salicylate + ACEA. ACEA did not eliminate salicylate-induced increases in cortical evoked potentials. ACEA failed to prevent or reverse salicylate- or noise-induced tinnitus behaviour.
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Affiliation(s)
- Joel I Berger
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom.
| | - Ben Coomber
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Samantha Hill
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Steve P H Alexander
- School of Life Sciences, Medical School, The University of Nottingham, Nottingham, NG7 2UH, United Kingdom
| | - William Owen
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Alan R Palmer
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Mark N Wallace
- Medical Research Council Institute of Hearing Research, School of Medicine, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
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