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Wood NJ, Lowe AS, Walton JP. Sodium salicylate alters temporal integration measured through increasing stimulus presentation rates. Int J Audiol 2019; 58:141-150. [PMID: 30845859 DOI: 10.1080/14992027.2018.1544424] [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: 10/27/2022]
Abstract
OBJECTIVE High doses of sodium salicylate (SS) are known to induce tinnitus, general hyperexcitability in the central auditory system, and to cause mild hearing loss. We used the auditory brainstem response (ABR) to assess the effects of SS on auditory sensitivity and temporal processing in the auditory nerve and brainstem. ABRs were evoked using tone burst stimuli varying in frequency and intensity with presentation rates from 11/s to 81/s. DESIGN ABRs were recorded and analysed prior to and after SS treatment in each animal, and peak 1 and peak 4 amplitudes and latencies were determined along with minimal response threshold. STUDY SAMPLE Nine young adult CBA/CaJ mice were used in a longitudinal within-subject design. RESULTS No measurable effects of presentation rate were found on ABR threshold prior to SS; however, following SS administration increasing stimulus rates lowered ABR thresholds by as much as 10 dB and compressed the peak amplitude by intensity level functions. CONCLUSIONS These results suggest that SS alters temporal integration and compressive nonlinearity, and that varying the stimulus rate of the ABR may prove to be a useful diagnostic tool in the study of hearing disorders that involve hyperexcitability.
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Affiliation(s)
- Nicole J Wood
- a Department of Biology , University of South Florida , Tampa , FL , USA.,b Morsani College of Medicine , University of South Florida , Tampa , FL , USA.,c Global Center for Hearing and Speech Research , University of South Florida , Tampa , FL , USA
| | - Andrea S Lowe
- c Global Center for Hearing and Speech Research , University of South Florida , Tampa , FL , USA.,d Department of Chemical and Biomedical Engineering , University of South Florida , Tampa , FL , USA
| | - Joseph P Walton
- c Global Center for Hearing and Speech Research , University of South Florida , Tampa , FL , USA.,d Department of Chemical and Biomedical Engineering , University of South Florida , Tampa , FL , USA.,e Department of Communication Sciences and Disorders , University of South Florida , Tampa , FL , USA
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Wu C, Bao W, Yi B, Wang Q, Wu X, Qian M, Zuo C, Huang Z. Increased metabolic activity and hysteretic enhanced GABA A receptor binding in a rat model of salicylate-induced tinnitus. Behav Brain Res 2019; 364:348-355. [PMID: 30797852 DOI: 10.1016/j.bbr.2019.02.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/20/2019] [Accepted: 02/21/2019] [Indexed: 11/16/2022]
Abstract
Tinnitus is relevant to neural hyperactivity in the central nervous system (CNS). Normal quantity and functioning of the γ-aminobutyric acid (GABA) receptor are crucial for maintaining the balance between excitation and inhibition in the brain. In this study, we applied a rat model of tinnitus via long-term salicylate administration. The combination of the gap pre-pulse inhibition of acoustic startle (GPIAS) and pre-pulse inhibition (PPI) tests were used to detect tinnitus-like behavior, and rats receiving 7 or 14 consecutive days of salicylate administration showed evidence of tinnitus. After positron emission tomography (PET) scan, we found that the metabolic activity was increased after salicylate treatment followed by enhanced GABAA receptor binding with cessation of salicylate administration in the auditory cortex (AC), medial prefrontal cortex (mPFC), hippocampus (HP), cingulate cortex (CiC) and insular (InC). The inferior colliculus (IC) showed an elevated metabolic activity with no change in the GABAA receptor binding. All the alterations returned to baseline several days after cessation of salicylate treatment despite a mismatch between the time-course of them. By contrast, we found alterations in neither the metabolic activity nor the GABAA receptor binding in the amygdala (AMY) and cerebellum (CRB). These findings indicate that enhanced neural activity in the auditory and limbic system may contribute to the development of tinnitus, while the hysteretic increase of GABAA receptor binding in specific areas of the CNS may be a compensation for hyperactivity, which may be involved in tinnitus relieving.
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Affiliation(s)
- Cong Wu
- Department of Otorhinolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Laboratoryof Auditory Neuroscience, Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Weiqi Bao
- PET Center, Huashan Hospital, Fudan University, Shanghai, China.
| | - Bin Yi
- Department of Otorhinolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Laboratoryof Auditory Neuroscience, Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Qixuan Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Laboratoryof Auditory Neuroscience, Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Xu Wu
- Department of Otorhinolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Laboratoryof Auditory Neuroscience, Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Minfei Qian
- Department of Otorhinolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Laboratoryof Auditory Neuroscience, Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
| | - Chuantao Zuo
- PET Center, Huashan Hospital, Fudan University, Shanghai, China.
| | - Zhiwu Huang
- Department of Otorhinolaryngology Head and Neck Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Laboratoryof Auditory Neuroscience, Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
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3
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Cao C, Li X, Qin L, Luo J, Zhang M, Ou Z, Wang K. High Selenium Yeast mitigates aluminum-induced cerebral inflammation by increasing oxidative stress and blocking NO production. Biometals 2018; 31:835-843. [DOI: 10.1007/s10534-018-0128-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/08/2018] [Indexed: 12/15/2022]
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Jiang C, Luo B, Manohar S, Chen GD, Salvi R. Plastic changes along auditory pathway during salicylate-induced ototoxicity: Hyperactivity and CF shifts. Hear Res 2017; 347:28-40. [PMID: 27989950 PMCID: PMC5403591 DOI: 10.1016/j.heares.2016.10.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/30/2016] [Accepted: 10/26/2016] [Indexed: 12/27/2022]
Abstract
High dose of salicylate, the active ingredient in aspirin, has long been known to induce transient hearing loss, tinnitus and hyperacusis making it a powerful experimental tool. These salicylate-induced perceptual disturbances are associated with a massive reduction in the neural output of the cochlea. Paradoxically, the diminished neural output of the cochlea is accompanied by a dramatic increase in sound-evoked activity in the auditory cortex (AC) and several other parts of the central nervous system. Exactly where the increase in neural activity begins and builds up along the central auditory pathway are not fully understood. To address this issue, we measured sound-evoked neural activity in the cochlea, cochlear nucleus (CN), inferior colliculus (IC), and AC before and after administering a high dose of sodium salicylate (SS, 300 mg/kg). The SS-treatment abolished low-level sound-evoked responses along the auditory pathway resulting in a 20-30 dB threshold shift. While the neural output of the cochlea was substantially reduced at high intensities, the neural responses in the CN were only slightly reduced; those in the IC were nearly normal or slightly enhanced while those in the AC considerably enhanced, indicative of a progress increase in central gain. The SS-induced increase in central response in the IC and AC was frequency-dependent with the greatest increase occurring in the mid-frequency range the putative pitch of SS-induced tinnitus. This frequency-dependent hyperactivity appeared to result from shifts in the frequency receptive fields (FRF) such that the response areas of many FRF shifted/expanded toward the mid-frequencies. Our results suggest that the SS-induced threshold shift originates in the cochlea. In contrast, enhanced central gain is not localized to one region, but progressively builds up at successively higher stage of the auditory pathway either through a loss of inhibition and/or increased excitation.
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Affiliation(s)
- Chen Jiang
- Department of Neurosurgery, Anhui Provincial Hospital, 17 Lujiang Road, Hefei, Anhui 230001, China; Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA
| | - Bin Luo
- Department of Neurosurgery, Anhui Provincial Hospital, 17 Lujiang Road, Hefei, Anhui 230001, China; Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA
| | - Senthilvelan Manohar
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA
| | - Guang-Di Chen
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA.
| | - Richard Salvi
- Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA
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Berger JI, Coomber B, Wallace MN, Palmer AR. Reductions in cortical alpha activity, enhancements in neural responses and impaired gap detection caused by sodium salicylate in awake guinea pigs. Eur J Neurosci 2016; 45:398-409. [PMID: 27862478 PMCID: PMC5763375 DOI: 10.1111/ejn.13474] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 11/07/2016] [Indexed: 11/30/2022]
Abstract
Tinnitus chronically affects between 10-15% of the population but, despite its prevalence, the underlying mechanisms are still not properly understood. One experimental model involves administration of high doses of sodium salicylate, as this is known to reliably induce tinnitus in both humans and animals. Guinea pigs were implanted with chronic electrocorticography (ECoG) electrode arrays, with silver-ball electrodes placed on the dura over left and right auditory cortex. Two more electrodes were positioned over the cerebellum to monitor auditory brainstem responses (ABRs). We recorded resting-state and auditory evoked neural activity from awake animals before and 2 h following salicylate administration (350 mg/kg; i.p.). Large increases in click-evoked responses (> 100%) were evident across the whole auditory cortex, despite significant reductions in wave I ABR amplitudes (in response to 20 kHz tones), which are indicative of auditory nerve activity. In the same animals, significant decreases in 6-10 Hz spontaneous oscillations (alpha waves) were evident over dorsocaudal auditory cortex. We were also able to demonstrate for the first time that cortical evoked potentials can be inhibited by a preceding gap in background noise [gap-induced pre-pulse inhibition (PPI)], in a similar fashion to the gap-induced inhibition of the acoustic startle reflex that is used as a behavioural test for tinnitus. Furthermore, 2 h following salicylate administration, we observed significant deficits in PPI of cortical responses that were closely aligned with significant deficits in behavioural responses to the same stimuli. Together, these data are suggestive of neural correlates of tinnitus and oversensitivity to sound (hyperacusis).
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Affiliation(s)
- Joel I Berger
- MRC Institute of Hearing Research, University Park, Nottingham, NG7 2RD, UK.,School of Medicine, University of Nottingham, Nottingham, UK
| | - Ben Coomber
- MRC Institute of Hearing Research, University Park, Nottingham, NG7 2RD, UK.,School of Medicine, University of Nottingham, Nottingham, UK
| | - Mark N Wallace
- MRC Institute of Hearing Research, University Park, Nottingham, NG7 2RD, UK.,School of Medicine, University of Nottingham, Nottingham, UK
| | - Alan R Palmer
- MRC Institute of Hearing Research, University Park, Nottingham, NG7 2RD, UK.,School of Medicine, University of Nottingham, Nottingham, UK
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Lowe AS, Walton JP. Alterations in peripheral and central components of the auditory brainstem response: a neural assay of tinnitus. PLoS One 2015; 10:e0117228. [PMID: 25695496 PMCID: PMC4335042 DOI: 10.1371/journal.pone.0117228] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 12/22/2014] [Indexed: 11/18/2022] Open
Abstract
Chronic tinnitus, or “ringing of the ears”, affects upwards of 15% of the adult population. Identifying a cost-effective and objective measure of tinnitus is needed due to legal concerns and disability issues, as well as for facilitating the effort to assess neural biomarkers. We developed a modified gap-in-noise (GIN) paradigm to assess tinnitus in mice using the auditory brainstem response (ABR). We then compared the commonly used acoustic startle reflex gap-prepulse inhibition (gap-PPI) and the ABR GIN paradigm in young adult CBA/CaJ mice before and after administrating sodium salicylate (SS), which is known to reliably induce a 16 kHz tinnitus percept in rodents. Post-SS, gap-PPI was significantly reduced at 12 and 16 kHz, consistent with previous studies demonstrating a tinnitus-induced gap-PPI reduction in this frequency range. ABR audiograms indicated thresholds were significantly elevated post-SS, also consistent with previous studies. There was a significant increase in the peak 2 (P2) to peak 1 (P1) and peak 4 (P4) to P1 amplitude ratios in the mid-frequency range, along with decreased latency of P4 at higher intensities. For the ABR GIN, peak amplitudes of the response to the second noise burst were calculated as a percentage of the first noise burst response amplitudes to quantify neural gap processing. A significant decrease in this ratio (i.e. recovery) was seen only at 16 kHz for P1, indicating the presence of tinnitus near this frequency. Thus, this study demonstrates that GIN ABRs can be used as an efficient, non-invasive, and objective method of identifying the approximate pitch and presence of tinnitus in a mouse model. This technique has the potential for application in human subjects and also indicates significant, albeit different, deficits in temporal processing in peripheral and brainstem circuits following drug induced tinnitus.
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Affiliation(s)
- Andrea S. Lowe
- Department of Chemical & Biomedical Engineering, University of South Florida, Tampa, Florida, United States of America
- Global Center for Hearing & Speech Research, University of South Florida, Tampa, Florida, United States of America
| | - Joseph P. Walton
- Department of Communication Sciences & Disorders, University of South Florida, Tampa, Florida, United States of America
- Department of Chemical & Biomedical Engineering, University of South Florida, Tampa, Florida, United States of America
- Global Center for Hearing & Speech Research, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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Zhao Y, Xu X, He J, Xu J, Zhang J. Age-related changes in neural gap detection thresholds in the rat auditory cortex. Eur J Neurosci 2014; 41:285-92. [PMID: 25388865 DOI: 10.1111/ejn.12791] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 10/13/2014] [Accepted: 10/20/2014] [Indexed: 11/30/2022]
Abstract
The ability of the auditory system to resolve sound temporal information is crucial for the understanding of human speech and other species-specific communications. Gap detection threshold, i.e. the ability to detect the shortest duration of a silent interval in a sound, is commonly used to study the auditory temporal resolution. Behavioral studies in humans and rats have shown that normal developing infants have higher gap detection thresholds than adults; however, the underlying neural mechanism is not fully understood. In the present study, we determined and compared the neural gap detection thresholds in the primary auditory cortex of three age groups of rats: the juvenile group (postnatal day 20-30), adult group I (8-10 weeks), and adult group II (28-30 weeks). We found age-related changes in auditory temporal acuity in the auditory cortex, i.e. the proportion of cortical units with short neural gap detection thresholds (< 5 ms) was much lower in juvenile groups compared with that in both adult groups at a constant sound level, and no significant differences in neural gap detection thresholds were found between the two adult groups. In addition, units in the auditory cortex of each group generally showed better gap detection thresholds at higher sound levels than at lower sound levels, exhibiting a level-dependent temporal acuity. These results provided evidence for neural correlates of age-related changes in behavioral gap detection ability during postnatal hearing development.
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Affiliation(s)
- Yin Zhao
- Key Laboratory of Brain Functional Genomics, Ministry of Education, NYU-ECNU Institute of Brain and Cognitive Science at NYU Shanghai, School of Life Science, East China Normal University, Shanghai, 200062, China
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Hayes SH, Radziwon KE, Stolzberg DJ, Salvi RJ. Behavioral models of tinnitus and hyperacusis in animals. Front Neurol 2014; 5:179. [PMID: 25278931 PMCID: PMC4166233 DOI: 10.3389/fneur.2014.00179] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/02/2014] [Indexed: 12/31/2022] Open
Abstract
The phantom perception of tinnitus and reduced sound-level tolerance associated with hyperacusis have a high comorbidity and can be debilitating conditions for which there are no widely accepted treatments. One factor limiting the development of treatments for tinnitus and hyperacusis is the lack of reliable animal behavioral models of these disorders. Therefore, the purpose of this review is to highlight the current animal models of tinnitus and hyperacusis, and to detail the advantages and disadvantages of each paradigm. To date, this is the first review to include models of both tinnitus and hyperacusis.
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Affiliation(s)
- Sarah H Hayes
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, University at Buffalo, The State University of New York , Buffalo, NY , USA
| | - Kelly E Radziwon
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, University at Buffalo, The State University of New York , Buffalo, NY , USA
| | - Daniel J Stolzberg
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario , London, ON , Canada
| | - Richard J Salvi
- Center for Hearing and Deafness, Department of Communicative Disorders and Sciences, University at Buffalo, The State University of New York , Buffalo, NY , USA
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Zhang C, Flowers E, Li JX, Wang Q, Sun W. Loudness perception affected by high doses of salicylate—A behavioral model of hyperacusis. Behav Brain Res 2014; 271:16-22. [DOI: 10.1016/j.bbr.2014.05.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 05/18/2014] [Accepted: 05/21/2014] [Indexed: 12/20/2022]
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Gold JR, Bajo VM. Insult-induced adaptive plasticity of the auditory system. Front Neurosci 2014; 8:110. [PMID: 24904256 PMCID: PMC4033160 DOI: 10.3389/fnins.2014.00110] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 04/28/2014] [Indexed: 01/10/2023] Open
Abstract
The brain displays a remarkable capacity for both widespread and region-specific modifications in response to environmental challenges, with adaptive processes bringing about the reweighing of connections in neural networks putatively required for optimizing performance and behavior. As an avenue for investigation, studies centered around changes in the mammalian auditory system, extending from the brainstem to the cortex, have revealed a plethora of mechanisms that operate in the context of sensory disruption after insult, be it lesion-, noise trauma, drug-, or age-related. Of particular interest in recent work are those aspects of auditory processing which, after sensory disruption, change at multiple—if not all—levels of the auditory hierarchy. These include changes in excitatory, inhibitory and neuromodulatory networks, consistent with theories of homeostatic plasticity; functional alterations in gene expression and in protein levels; as well as broader network processing effects with cognitive and behavioral implications. Nevertheless, there abounds substantial debate regarding which of these processes may only be sequelae of the original insult, and which may, in fact, be maladaptively compelling further degradation of the organism's competence to cope with its disrupted sensory context. In this review, we aim to examine how the mammalian auditory system responds in the wake of particular insults, and to disambiguate how the changes that develop might underlie a correlated class of phantom disorders, including tinnitus and hyperacusis, which putatively are brought about through maladaptive neuroplastic disruptions to auditory networks governing the spatial and temporal processing of acoustic sensory information.
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Affiliation(s)
- Joshua R Gold
- Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK
| | - Victoria M Bajo
- Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK
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Sun W, Doolittle L, Flowers E, Zhang C, Wang Q. High doses of salicylate causes prepulse facilitation of onset-gap induced acoustic startle response. Behav Brain Res 2014; 258:187-92. [DOI: 10.1016/j.bbr.2013.10.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 10/08/2013] [Accepted: 10/14/2013] [Indexed: 11/26/2022]
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Suh MW, Kim KW, Park IY, Oh SH. Parameter optimization for applying the prepulse gap paradigm to humans. KOREAN JOURNAL OF AUDIOLOGY 2013; 17:118-23. [PMID: 24653919 PMCID: PMC3936552 DOI: 10.7874/kja.2013.17.3.118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 12/04/2013] [Accepted: 12/06/2013] [Indexed: 11/26/2022]
Abstract
Background and Objectives Turner and colleagues introduced a new method that can detect tinnitus in animals. The stimulus is composed of a small background noise that is identical to the pitch of the tinnitus and a large pulse noise that can evoke a startle response. In normal rats, the gap decreases the startle reflex. However, in tinnitus rats, the gap does not decrease the startle reflex. The goal of this study was to optimize the stimulation paradigm so that the prepulse inhibition of N1-P2 amplitude would be maximized in the normal human subjects. Subjects and Methods Seven normal control subjects without tinnitus were recruited. The stimulus was composed of two different sounds: the softer background noise and the louder pulse noise. A 50 msec silent gap was inserted before the pulse noise as the gap condition (G condition) but not in the no-gap condition (N condition). The averaged amplitude of the N1-P2 cortical response was recorded for the G and N conditions. Results The G/N ratio was the smallest when the gap was 20 msec prior to the pulse noise. The G/N ratio was 84.8±16.8% with the Hanning window and 78.5±5.9% without the window. The G/N ratio was 91.1±24.9%, 78.0±5.4%, and 79.0±18.1% when the intensity of the background noise was 10, 20, and 32 dB SL, respectively. When the intensity of the background noise was 20 and 32 dB SL, the N1-P2 amplitude of the G condition was significantly smaller than that of the N condition. Conclusions The optimal stimulus should be composed of the 1 kHz pulse noise without Hanning window. The intensity of the background noise should be 20 dB HL and the location of the gap should be 20 msec prior to the pulse noise. It seems that with these optimized parameters we could expect a 78.0% inhibition of N1-P2 amplitude in normal subjects without tinnitus.
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Affiliation(s)
- Myung-Whan Suh
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, Korea
| | - Kun Woo Kim
- Department of Otorhinolaryngology, Dankook University College of Medicine, Cheonan, Korea
| | - Il-Yong Park
- Department of Biomedical Engineering, Dankook University College of Medicine, Cheonan, Korea
| | - Seung-Ha Oh
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, Korea
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Liu XP, Chen L. Auditory brainstem response as a possible objective indicator for salicylate-induced tinnitus in rats. Brain Res 2012; 1485:88-94. [PMID: 22607819 DOI: 10.1016/j.brainres.2012.04.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Revised: 04/24/2012] [Accepted: 04/24/2012] [Indexed: 11/18/2022]
Abstract
The auditory response to an acoustic stimulus will usually be suppressed, or masked, by a preceding sound. Here, we show that forward acoustic masking at a high frequency can boost the auditory brainstem response (ABR) in rats injected with a high dose of sodium salicylate (NaSal), a tinnitus inducer. The forward narrow band noise caused a decrease in the amplitude of the ABR to a probe tone burst in normal rats, but caused an unexpected increase in the amplitude at 16 kHz in rats treated with NaSal (300 mg/kg). The observed effect could be manifested in normal rats presented with a background tone added to the masker and the probe, suggesting an underlying mechanism associated with tinnitus. We hypothesize that in NaSal-treated rats, tinnitus can "internally" mask the ABR in a similar way as an external background sound does and the "unmasking" effect of forward masking can result in a rebound of the otherwise suppressed ABR. Our study raises the possibility of using the ABR as an objective indicator for NaSal-induced tinnitus in animals. This article is part of a Special Issue entitled: Tinnitus Neuroscience.
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Affiliation(s)
- Xiao-Peng Liu
- CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
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Page KE, White KN, McCrohan CR, Killilea DW, Lithgow GJ. Aluminium exposure disrupts elemental homeostasis in Caenorhabditis elegans. Metallomics 2012; 4:512-22. [PMID: 22534883 DOI: 10.1039/c2mt00146b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Aluminium (Al) is highly abundant in the environment and can elicit a variety of toxic responses in biological systems. Here we characterize the effects of Al on Caenorhabditis elegans by identifying phenotypic abnormalities and disruption in whole-body metal homeostasis (metallostasis) following Al exposure in food. Widespread changes to the elemental content of adult nematodes were observed when chronically exposed to Al from the first larval stage (L1). Specifically, we saw increased barium, chromium, copper and iron content, and a reduction in calcium levels. Lifespan was decreased in worms exposed to low levels of Al, but unexpectedly increased when the Al concentration reached higher levels (4.8 mM). This bi-phasic phenotype was only observed when Al exposure occurred during development, as lifespan was unaffected by Al exposure during adulthood. Lower levels of Al slowed C. elegans developmental progression, and reduced hermaphrodite self-fertility and adult body size. Significant developmental delay was observed even when Al exposure was restricted to embryogenesis. Similar changes in Al have been noted in association with Al toxicity in humans and other mammals, suggesting that C. elegans may be of use as a model for understanding the mechanisms of Al toxicity in mammalian systems.
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Affiliation(s)
- Kathryn E Page
- The Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA
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