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Mao B, Wang Y, Balasubramanian T, Urioste R, Wafa T, Fitzgerald TS, Haraczy SJ, Edwards-Hollingsworth K, Sayyid ZN, Wilder D, Sajja VSSS, Wei Y, Arun P, Gist I, Cheng AG, Long JB, Kelley MW. Assessment of auditory and vestibular damage in a mouse model after single and triple blast exposures. Hear Res 2021; 407:108292. [PMID: 34214947 DOI: 10.1016/j.heares.2021.108292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 05/17/2021] [Accepted: 06/02/2021] [Indexed: 12/18/2022]
Abstract
The use of explosive devices in war and terrorism has increased exposure to concussive blasts among both military personnel and civilians, which can cause permanent hearing and balance deficits that adversely affect survivors' quality of life. Significant knowledge gaps on the underlying etiology of blast-induced hearing loss and balance disorders remain, especially with regard to the effect of blast exposure on the vestibular system, the impact of multiple blast exposures, and long-term recovery. To address this, we investigated the effects of blast exposure on the inner ear using a mouse model in conjunction with a high-fidelity blast simulator. Anesthetized animals were subjected to single or triple blast exposures, and physiological measurements and tissue were collected over the course of recovery for up to 180 days. Auditory brainstem responses (ABRs) indicated significantly elevated thresholds across multiple frequencies. Limited recovery was observed at low frequencies in single-blasted mice. Distortion Product Otoacoustic Emissions (DPOAEs) were initially absent in all blast-exposed mice, but low-amplitude DPOAEs could be detected at low frequencies in some single-blast mice by 30 days post-blast, and in some triple-blast mice at 180 days post-blast. All blast-exposed mice showed signs of Tympanic Membrane (TM) rupture immediately following exposure and loss of outer hair cells (OHCs) in the basal cochlear turn. In contrast, the number of Inner Hair Cells (IHCs) and spiral ganglion neurons was unchanged following blast-exposure. A significant reduction in IHC pre-synaptic puncta was observed in the upper turns of blast-exposed cochleae. Finally, we found no significant loss of utricular hair cells or changes in vestibular function as assessed by vestibular evoked potentials. Our results suggest that (1) blast exposure can cause severe, long-term hearing loss which may be partially due to slow TM healing or altered mechanical properties of healed TMs, (2) traumatic levels of sound can still reach the inner ear and cause basal OHC loss despite middle ear dysfunction caused by TM rupture, (3) blast exposure may result in synaptopathy in humans, and (4) balance deficits after blast exposure may be primarily due to traumatic brain injury, rather than damage to the peripheral vestibular system.
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Affiliation(s)
- Beatrice Mao
- Section on Developmental Neuroscience, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA.
| | - Ying Wang
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | - Tara Balasubramanian
- Section on Developmental Neuroscience, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Rodrigo Urioste
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Talah Wafa
- Mouse Auditory Testing Core Facility, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Tracy S Fitzgerald
- Mouse Auditory Testing Core Facility, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Scott J Haraczy
- Section on Developmental Neuroscience, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Kamren Edwards-Hollingsworth
- Section on Developmental Neuroscience, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - Zahra N Sayyid
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Donna Wilder
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Venkata Siva Sai Sujith Sajja
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Yanling Wei
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Peethambaran Arun
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Irene Gist
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Alan G Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Joseph B Long
- Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | - Matthew W Kelley
- Section on Developmental Neuroscience, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
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Ertl M, Klaus M, Mast FW, Brandt T, Dieterich M. Spectral fingerprints of correct vestibular discrimination of the intensity of body accelerations. Neuroimage 2020; 219:117015. [PMID: 32505699 DOI: 10.1016/j.neuroimage.2020.117015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 05/04/2020] [Accepted: 06/02/2020] [Indexed: 12/18/2022] Open
Abstract
Perceptual decision-making is a complex task that requires multiple processing steps performed by spatially distinct brain regions interacting in order to optimize perception and motor response. Most of our knowledge on these processes and interactions were derived from unimodal stimulations of the visual system which identified the lateral intraparietal area and the posterior parietal cortex as critical regions. Unlike the visual system, the vestibular system has no primary cortical areas and it is associated with separate multisensory areas within the temporo-parietal cortex with the parieto-insular vestibular cortex, PIVC, being the core region. The aim of the presented experiment was to investigate the transition from sensation to perception and to reveal the main structures of the cortical vestibular system involved in perceptual decision-making. Therefore, an EEG analysis was performed in 35 healthy subjects during linear whole-body accelerations of different intensities on a motor-driven motion platform (hexapod). We used a discrimination task in order to judge the intensity of the accelerations. Furthermore, we manipulated the expectation of the upcoming stimulus by indicating the probability (25%, 50%, 75%, 100%) of the motion direction. The analysis of the vestibular evoked potentials (VestEPs) showed that the decision-making process leads to a second positive peak (P2b) which was not observed in previous task-free experiments. The comparison of the estimated neural generators of the P2a and P2b components showed significant activity differences in the anterior cingulus, the parahippocampal and the middle temporal gyri. Taking into account the time courses of the P2 components, the physical properties of the stimuli, and the responses given by the subjects we conclude that the P2b likely reflects the transition from the processing of sensory information to perceptual evaluation. Analyzing the decision-uncertainty reported by the subjects, a persistent divergence of the time courses starting at 188 ms after the acceleration was found at electrode Pz. This finding demonstrated that meta-cognition by means of confidence estimation starts in parallel with the decision-making process itself. Further analyses in the time-frequency domain revealed that a correct classification of acceleration intensities correlated with an inter-trial phase clustering at electrode Cz and an inter-site phase clustering of theta oscillations over frontal, central, and parietal cortical areas. The sites where the phase clustering was observed corresponded to core decision-making brain areas known from neuroimaging studies in the visual domain.
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Affiliation(s)
- M Ertl
- Department of Psychology, University Bern, Switzerland; Department of Neurology, Ludwig-Maximilians-Universität München, Germany.
| | - M Klaus
- Department of Psychology, University Bern, Switzerland
| | - F W Mast
- Department of Psychology, University Bern, Switzerland
| | - T Brandt
- German Center for Vertigo and Balance Disorders-IFBLMU (DSGZ), Ludwig-Maximilians-Universität München, Germany; Hertie Senior Research Professor for Clinical Neuroscience, Ludwig-Maximilians-Universität München, Germany
| | - M Dieterich
- Department of Neurology, Ludwig-Maximilians-Universität München, Germany; German Center for Vertigo and Balance Disorders-IFBLMU (DSGZ), Ludwig-Maximilians-Universität München, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
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Parker-George JC, Bell SL, Griffin MJ. Ocular vestibular evoked myogenic potentials elicited with vibration applied to the teeth. Clin Neurophysiol 2016; 127:833-41. [PMID: 25881783 DOI: 10.1016/j.clinph.2015.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 02/13/2015] [Accepted: 02/17/2015] [Indexed: 11/22/2022]
Abstract
OBJECTIVES This study investigated whether the method for eliciting vibration-induced oVEMPs could be improved by applying vibration directly to the teeth, and how vibration-induced oVEMP responses depend on the duration of the applied vibration. METHODS In 10 participants, a hand-held shaker was used to present 100-Hz vibration tone pips to the teeth via a customised bite-bar or to other parts of the head. oVEMP potentials were recorded in response to vibration in three orthogonal directions and five stimulus durations (10-180 ms). The oVEMP responses were analysed in terms of the peak latency onset, peak-to-peak amplitude, and the quality of the trace. RESULTS Vibration applied to the teeth via the bite-bar produced oVEMPs that were more consistent, of higher quality and of greater amplitude than those evoked by vibration applied to the head. Longer duration stimuli produced longer duration oVEMP responses. One cycle duration stimuli produced responses that were smaller in amplitude and lower quality than the longer stimulus durations. CONCLUSIONS Application of vibration via the teeth using a bite-bar is an effective means of producing oVEMPs. A 1-cycle stimulus is not optimal to evoke an oVEMP because it produces less robust responses than those of longer stimulus duration. A positive relationship between the duration of the stimulus and the response is consistent with the notion that the vibration-induced oVEMP is an oscillatory response to the motion of the head, rather than being a simple reflex response that occurs when the stimulus exceeds a threshold level of stimulation. SIGNIFICANCE Applying acceleration to the teeth through a bite-bar elicits clearer oVEMP responses than direct application to other parts of the head and has potential to improve clinical measurements. A 100-Hz 1-cycle stimulus produces less robust oVEMP responses than longer 100-Hz stimuli.
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