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Siegbahn M, Jörgens D, Asp F, Hultcrantz M, Moreno R, Engmér Berglin C. Asymmetry in Cortical Thickness of the Heschl's Gyrus in Unilateral Ear Canal Atresia. Otol Neurotol 2024; 45:e342-e350. [PMID: 38361347 DOI: 10.1097/mao.0000000000004137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
HYPOTHESIS Unilateral congenital conductive hearing impairment in ear canal atresia leads to atrophy of the gray matter of the contralateral primary auditory cortex or changes in asymmetry pattern if left untreated in childhood. BACKGROUND Unilateral ear canal atresia with associated severe conductive hearing loss results in deteriorated sound localization and difficulties in understanding of speech in a noisy environment. Cortical atrophy in the Heschl's gyrus has been reported in acquired sensorineural hearing loss but has not been studied in unilateral conductive hearing loss. METHODS We obtained T1w and T2w FLAIR MRI data from 17 subjects with unilateral congenital ear canal atresia and 17 matched controls. Gray matter volume and thickness were measured in the Heschl's gyrus using Freesurfer. RESULTS In unilateral congenital ear canal atresia, Heschl's gyrus exhibited cortical thickness asymmetry (right thicker than left, corrected p = 0.0012, mean difference 0.25 mm), while controls had symmetric findings. Gray matter volume and total thickness did not differ from controls with normal hearing. CONCLUSION We observed cortical thickness asymmetry in congenital unilateral ear canal atresia but no evidence of contralateral cortex atrophy. Further research is needed to understand the implications of this asymmetry on central auditory processing deficits.
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Affiliation(s)
| | - Daniel Jörgens
- Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Filip Asp
- Division of ENT diseases, Department of Clinical Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Malou Hultcrantz
- Division of ENT diseases, Department of Clinical Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Rodrigo Moreno
- Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Stockholm, Sweden
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Polspoel S, Moore DR, Swanepoel DW, Kramer SE, Smits C. Sensitivity of the antiphasic digits-in-noise test to simulated unilateral and bilateral conductive hearing loss. Int J Audiol 2023; 62:1022-1030. [PMID: 36121040 DOI: 10.1080/14992027.2022.2119611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 08/28/2022] [Indexed: 11/05/2022]
Abstract
OBJECTIVES The objective of this study is (1) to assess whether the presentation level of the antiphasic digits-in-noise (DIN) test affects the speech recognition threshold (SRT), (2) to evaluate how accurately simulated unilateral and bilateral conductive hearing loss is detected (CHL) and (3) to determine whether increasing the presentation level normalises the antiphasic DIN SRT. DESIGN Participants performed antiphasic and diotic DINs at different presentation levels with unilateral, bilateral or no earplugs. STUDY SAMPLE Twenty-four and twelve normal hearing adults. RESULTS Without earplugs, antiphasic DIN SRTs did not differ between 60 and 80 dB SPL. At 60 dB SPL, the antiphasic DIN correctly classified 92% of the unilateral earplug cases; the diotic DIN 25%. The binaural intelligibility level difference did not differ between the no-earplug condition and the condition with bilateral earplugs when the presentation was increased with the attenuation level. CONCLUSIONS In normal hearing participants, diotic and antiphasic DIN SRTs are independent of presentation level above a minimum level of 60 dB SPL. The antiphasic DIN is more sensitive than the diotic DIN for detecting unilateral CHL; not for bilateral CHL. The effect of CHL on DIN SRTs can be largely compensated by increasing the presentation level. Audibility plays an important role in the antiphasic and diotic DIN.
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Affiliation(s)
- Sigrid Polspoel
- Otolaryngology-Head and Neck Surgery, Section Ear and Hearing, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, De Boelelaan, The Netherlands
- Amsterdam Public Health Research Institute, Quality of Care, Amsterdam, The Netherlands
| | - David R Moore
- Communication Sciences Research Center, Cincinnati Childrens' Hospital Medical Center and University of Cincinnati, Cincinnati, OH, USA
- Manchester Centre for Audiology and Deafness, University of Manchester, Manchester, UK
| | - De Wet Swanepoel
- Ear Sciences Centre, School of Surgery, University of Western Australia, Perth, WA, Australia
- Department of Speech-Language Pathology and Audiology, University of Pretoria, Pretoria, South Africa
| | - Sophia E Kramer
- Otolaryngology-Head and Neck Surgery, Section Ear and Hearing, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, De Boelelaan, The Netherlands
- Amsterdam Public Health Research Institute, Quality of Care, Amsterdam, The Netherlands
| | - Cas Smits
- Amsterdam Public Health Research Institute, Quality of Care, Amsterdam, The Netherlands
- Amsterdam UMC location University of Amsterdam, Otolaryngology-Head and Neck Surgery, Ear and Hearing, Meibergdreef, Amsterdam, The Netherlands
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Boothalingam S, Peterson A, Powell L, Easwar V. Auditory brainstem mechanisms likely compensate for self-imposed peripheral inhibition. Sci Rep 2023; 13:12693. [PMID: 37542191 PMCID: PMC10403563 DOI: 10.1038/s41598-023-39850-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 08/01/2023] [Indexed: 08/06/2023] Open
Abstract
Feedback networks in the brain regulate downstream auditory function as peripheral as the cochlea. However, the upstream neural consequences of this peripheral regulation are less understood. For instance, the medial olivocochlear reflex (MOCR) in the brainstem causes putative attenuation of responses generated in the cochlea and cortex, but those generated in the brainstem are perplexingly unaffected. Based on known neural circuitry, we hypothesized that the inhibition of peripheral input is compensated for by positive feedback in the brainstem over time. We predicted that the inhibition could be captured at the brainstem with shorter (1.5 s) than previously employed long duration (240 s) stimuli where this inhibition is likely compensated for. Results from 16 normal-hearing human listeners support our hypothesis in that when the MOCR is activated, there is a robust reduction of responses generated at the periphery, brainstem, and cortex for short-duration stimuli. Such inhibition at the brainstem, however, diminishes for long-duration stimuli suggesting some compensatory mechanisms at play. Our findings provide a novel non-invasive window into potential gain compensation mechanisms in the brainstem that may have implications for auditory disorders such as tinnitus. Our methodology will be useful in the evaluation of efferent function in individuals with hearing loss.
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Affiliation(s)
- Sriram Boothalingam
- Waisman Center and Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI, 53705, USA.
- Macquarie University, Sydney, NSW, 2109, Australia.
- National Acoustic Laboratories, Sydney, NSW, 2109, Australia.
| | - Abigayle Peterson
- Waisman Center and Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Macquarie University, Sydney, NSW, 2109, Australia
| | - Lindsey Powell
- Waisman Center and Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Vijayalakshmi Easwar
- Waisman Center and Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Macquarie University, Sydney, NSW, 2109, Australia
- National Acoustic Laboratories, Sydney, NSW, 2109, Australia
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Herrmann B, Maess B, Johnsrude IS. Sustained responses and neural synchronization to amplitude and frequency modulation in sound change with age. Hear Res 2023; 428:108677. [PMID: 36580732 DOI: 10.1016/j.heares.2022.108677] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 12/09/2022] [Accepted: 12/16/2022] [Indexed: 12/23/2022]
Abstract
Perception of speech requires sensitivity to features, such as amplitude and frequency modulations, that are often temporally regular. Previous work suggests age-related changes in neural responses to temporally regular features, but little work has focused on age differences for different types of modulations. We recorded magnetoencephalography in younger (21-33 years) and older adults (53-73 years) to investigate age differences in neural responses to slow (2-6 Hz sinusoidal and non-sinusoidal) modulations in amplitude, frequency, or combined amplitude and frequency. Audiometric pure-tone average thresholds were elevated in older compared to younger adults, indicating subclinical hearing impairment in the recruited older-adult sample. Neural responses to sound onset (independent of temporal modulations) were increased in magnitude in older compared to younger adults, suggesting hyperresponsivity and a loss of inhibition in the aged auditory system. Analyses of neural activity to modulations revealed greater neural synchronization with amplitude, frequency, and combined amplitude-frequency modulations for older compared to younger adults. This potentiated response generalized across different degrees of temporal regularity (sinusoidal and non-sinusoidal), although neural synchronization was generally lower for non-sinusoidal modulation. Despite greater synchronization, sustained neural activity was reduced in older compared to younger adults for sounds modulated both sinusoidally and non-sinusoidally in frequency. Our results suggest age differences in the sensitivity of the auditory system to features present in speech and other natural sounds.
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Affiliation(s)
- Björn Herrmann
- Rotman Research Institute, Baycrest, North York, ON M6A 2E1, Canada; Department of Psychology, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Psychology & Brain and Mind Institute, The University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Burkhard Maess
- Max Planck Institute for Human Cognitive and Brain Sciences, Brain Networks Unit, Leipzig 04103, Germany
| | - Ingrid S Johnsrude
- Department of Psychology & Brain and Mind Institute, The University of Western Ontario, London, ON N6A 3K7, Canada; School of Communication Sciences & Disorders, The University of Western Ontario, London, ON N6A 5B7, Canada
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Valderrama JT, de la Torre A, McAlpine D. The hunt for hidden hearing loss in humans: From preclinical studies to effective interventions. Front Neurosci 2022; 16:1000304. [PMID: 36188462 PMCID: PMC9519997 DOI: 10.3389/fnins.2022.1000304] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 08/29/2022] [Indexed: 11/30/2022] Open
Abstract
Many individuals experience hearing problems that are hidden under a normal audiogram. This not only impacts on individual sufferers, but also on clinicians who can offer little in the way of support. Animal studies using invasive methodologies have developed solid evidence for a range of pathologies underlying this hidden hearing loss (HHL), including cochlear synaptopathy, auditory nerve demyelination, elevated central gain, and neural mal-adaptation. Despite progress in pre-clinical models, evidence supporting the existence of HHL in humans remains inconclusive, and clinicians lack any non-invasive biomarkers sensitive to HHL, as well as a standardized protocol to manage hearing problems in the absence of elevated hearing thresholds. Here, we review animal models of HHL as well as the ongoing research for tools with which to diagnose and manage hearing difficulties associated with HHL. We also discuss new research opportunities facilitated by recent methodological tools that may overcome a series of barriers that have hampered meaningful progress in diagnosing and treating of HHL.
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Affiliation(s)
- Joaquin T. Valderrama
- National Acoustic Laboratories, Sydney, NSW, Australia
- Department of Linguistics, Macquarie University Hearing, Macquarie University, Sydney, NSW, Australia
| | - Angel de la Torre
- Department of Signal Theory, Telematics and Communications, University of Granada, Granada, Spain
- Research Centre for Information and Communications Technologies (CITIC-UGR), University of Granada, Granada, Spain
| | - David McAlpine
- Department of Linguistics, Macquarie University Hearing, Macquarie University, Sydney, NSW, Australia
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Callejón-Leblic MA, Barrios-Romero MM, Kontides A, Sánchez-Gómez S, Beynon AJ. Electrically evoked auditory cortical responses elicited from individually fitted stimulation parameters in cochlear implant users. Int J Audiol 2022:1-9. [PMID: 35477333 DOI: 10.1080/14992027.2022.2062578] [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 To investigate electrically evoked auditory cortical responses (eACR) elicited from the stimulation of intracochlear electrodes based on individually fitted stimulation parameters in cochlear implant (CI) users. DESIGN An eACR setup based on individual fitting parameters is proposed. A 50-ms alternating biphasic pulse train was used to stimulate apical, medial, and basal electrodes and to evoke auditory cortical potentials (N1-P2 complex). STUDY SAMPLE The eACR setup proposed was validated with 14 adult CI users. RESULTS Individual and grand-average eACR waveforms were obtained. The eACR amplitudes were lower in the basal than in the apical and medial regions. Earlier N1 latencies were found in CI users with lower maximum comfortable loudness levels and shorter phase duration in response to apical stimulation, while medial and basal stimulation resulted in earlier N1 latencies and larger N1-P2 amplitudes in users with longer CI experience. CONCLUSIONS eACR could be elicited by direct intracochlear stimulation using individual fitting parameters with a success rate of 71%. The highest cortical peak-to-peak amplitudes were obtained in response to apical stimulation. Unlike the P2, the N1 component appeared to be a consistent cortical potential to determine eACR and gain knowledge of the auditory processing beyond the cochlea in CI users. HighlightseACR can be elicited through direct stimulation of intracochlear electrodes.Stimulation of apical and medial regions yielded the highest N1-P2 amplitudes.CI users with lower maximum comfortable loudness levels had shorter N1 latencies during apical stimulation.The present dataset of mainly well-performing CI users suggests better cortical processing, that is, higher amplitudes and shorter latencies of N1.The N1 potential appears a more consistent and reliable potential than the P2 to determine eACR responses in CI users.
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Affiliation(s)
- María A Callejón-Leblic
- Department of Otolaryngology, Head and Neck Surgery, Virgen Macarena University Hospital, Seville, Spain.,Biomedical Engineering Group, University of Seville, Seville, Spain
| | | | - Alejandra Kontides
- MED-EL Headquarters, Innsbruck, Austria; dDonders Centre for Neurosciences, Radboud University Nijmegen Medical Center, Nijmegen, Netherlands
| | - Serafín Sánchez-Gómez
- Department of Otolaryngology, Head and Neck Surgery, Virgen Macarena University Hospital, Seville, Spain
| | - Andy J Beynon
- Otorhinolaryngology Department, Radboud University Nijmegen Medical Center, Nijmegen, Netherlands.,ENT Department, Radboud University Nijmegen Medical Center, Nijmegen, Netherlands
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Okada M, Welling DB, Liberman MC, Maison SF. Chronic Conductive Hearing Loss Is Associated With Speech Intelligibility Deficits in Patients With Normal Bone Conduction Thresholds. Ear Hear 2021; 41:500-507. [PMID: 31490800 PMCID: PMC7056594 DOI: 10.1097/aud.0000000000000787] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVES The main objective of this study is to determine whether chronic sound deprivation leads to poorer speech discrimination in humans. DESIGN We reviewed the audiologic profile of 240 patients presenting normal and symmetrical bone conduction thresholds bilaterally, associated with either an acute or chronic unilateral conductive hearing loss of different etiologies. RESULTS Patients with chronic conductive impairment and a moderate, to moderately severe, hearing loss had lower speech recognition scores on the side of the pathology when compared with the healthy side. The degree of impairment was significantly correlated with the speech recognition performance, particularly in patients with a congenital malformation. Speech recognition scores were not significantly altered when the conductive impairment was acute or mild. CONCLUSIONS This retrospective study shows that chronic conductive hearing loss was associated with speech intelligibility deficits in patients with normal bone conduction thresholds. These results are as predicted by a recent animal study showing that prolonged, adult-onset conductive hearing loss causes cochlear synaptopathy.
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Affiliation(s)
- Masahiro Okada
- Department of Otolaryngology, Head and Neck Surgery, Ehime University Graduate School of Medicine, Toon Ehime, Japan
- Department of Otolaryngology, Harvard Medical School and Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, USA
| | - D. Bradley Welling
- Department of Otolaryngology, Harvard Medical School and Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, USA
| | - M. Charles Liberman
- Department of Otolaryngology, Harvard Medical School and Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, USA
| | - Stéphane F. Maison
- Department of Otolaryngology, Harvard Medical School and Eaton-Peabody Laboratories, Massachusetts Eye & Ear Infirmary, Boston, USA
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Herrmann B, Butler BE. Hearing loss and brain plasticity: the hyperactivity phenomenon. Brain Struct Funct 2021; 226:2019-2039. [PMID: 34100151 DOI: 10.1007/s00429-021-02313-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 06/03/2021] [Indexed: 12/22/2022]
Abstract
Many aging adults experience some form of hearing problems that may arise from auditory peripheral damage. However, it has been increasingly acknowledged that hearing loss is not only a dysfunction of the auditory periphery but also results from changes within the entire auditory system, from periphery to cortex. Damage to the auditory periphery is associated with an increase in neural activity at various stages throughout the auditory pathway. Here, we review neurophysiological evidence of hyperactivity, auditory perceptual difficulties that may result from hyperactivity, and outline open conceptual and methodological questions related to the study of hyperactivity. We suggest that hyperactivity alters all aspects of hearing-including spectral, temporal, spatial hearing-and, in turn, impairs speech comprehension when background sound is present. By focusing on the perceptual consequences of hyperactivity and the potential challenges of investigating hyperactivity in humans, we hope to bring animal and human electrophysiologists closer together to better understand hearing problems in older adulthood.
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Affiliation(s)
- Björn Herrmann
- Rotman Research Institute, Baycrest, Toronto, ON, M6A 2E1, Canada. .,Department of Psychology, University of Toronto, Toronto, ON, Canada.
| | - Blake E Butler
- Department of Psychology & The Brain and Mind Institute, University of Western Ontario, London, ON, Canada.,National Centre for Audiology, University of Western Ontario, London, ON, Canada
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Liu X, Li L, Chen GD, Salvi R. How low must you go? Effects of low-level noise on cochlear neural response. Hear Res 2020; 392:107980. [DOI: 10.1016/j.heares.2020.107980] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/17/2020] [Accepted: 04/21/2020] [Indexed: 10/24/2022]
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Transient Conductive Hearing Loss Regulates Cross-Modal VGLUT Expression in the Cochlear Nucleus of C57BL/6 Mice. Brain Sci 2020; 10:brainsci10050260. [PMID: 32365514 PMCID: PMC7287693 DOI: 10.3390/brainsci10050260] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 04/27/2020] [Accepted: 04/29/2020] [Indexed: 12/19/2022] Open
Abstract
Auditory nerve fibers synapse onto the cochlear nucleus (CN) and are labeled using the vesicular glutamate transporter-1 (VGLUT-1), whereas non-auditory inputs are labeled using the VGLUT-2. However, the underlying regulatory mechanism of VGLUT expression in the CN remains unknown. We examined whether a sound level decrease, without primary neural damage, induces cellular and VGLUT expression change in the CN, and examined the potential for neural plasticity of the CN using unilateral conductive hearing loss models. We inserted earplugs in 8-week-old mice unilaterally for 4 weeks and subsequently removed them for another 4 weeks. Although the threshold of an auditory brainstem response significantly increased across all tested frequencies following earplug insertion, it completely recovered after earplug removal. Auditory deprivation had no significant impact on spiral ganglion and ventral CN (VCN) neurons’ survival. Conversely, although the cell size and VGLUT-1 expression in the VCN significantly decreased after earplug insertion, VGLUT-2 expression in the granule cell lamina significantly increased. These cell sizes decreased and the alterations in VGLUT-1 and -2 expression almost completely recovered at 1 month after earplug removal. Our results suggested that the cell size and VGLUT expression in the CN have a neuroplasticity capacity, which is regulated by increases and decreases in sound levels. Restoration of the sound levels might partly prevent cell size decrease and maintain VGLUT expression in the CN.
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Abstract
BACKGROUND Sensory gating is a measure used to evaluate inhibitory deficits underlying neurological disorders. However, the effects of hearing loss (HL), thought to decrease inhibition, remain unknown on gating function. PURPOSE The goal of this study was to investigate gating performance in HL. RESEARCH DESIGN This was a prospective, cross-sectional study with independent group comparison and correlational design. STUDY SAMPLE Eleven adults (mean age/standard deviation = 47.546 ± 7.967 years) with normal hearing (NH) and 11 adults (mean age/standard deviation = 56.273 ± 13.871 years) with mild-moderate high-frequency HL. DATA COLLECTION AND ANALYSIS Cortical auditory evoked potentials (CAEPs) were recorded in response to tonal pairs via high-density electroencephalography. The CAEP response to the second tone in the pair (S2) was compared with the response to the first tone in the pair (S1) within groups. Amplitude gating indices were compared between groups and correlated with auditory behavioral measures. Current density reconstructions were performed to estimate cortical gating generators. RESULTS Amplitude gating indices were decreased and correlated with elevated auditory thresholds. Gating generators in temporal, frontal, and prefrontal regions were localized in the NH group, while HL gating was localized in mainly temporal and parietal areas. CONCLUSIONS Reduced inhibition may be associated with compensatory cortical gating networks in HL and should be considered when utilizing gating in clinical populations.
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Affiliation(s)
- Julia Campbell
- Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, Texas.,Central Sensory Processes Laboratory, University of Texas at Austin, Austin, Texas
| | - Mashhood Nielsen
- Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, Texas.,Central Sensory Processes Laboratory, University of Texas at Austin, Austin, Texas
| | - Connor Bean
- Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, Texas.,Central Sensory Processes Laboratory, University of Texas at Austin, Austin, Texas
| | - Alison LaBrec
- Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, Texas.,Central Sensory Processes Laboratory, University of Texas at Austin, Austin, Texas
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Automated analysis of bone-conduction cortical auditory evoked potential in normal-hearing neonates. Braz J Otorhinolaryngol 2019; 87:290-297. [PMID: 31740284 PMCID: PMC9422526 DOI: 10.1016/j.bjorl.2019.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/05/2019] [Accepted: 09/11/2019] [Indexed: 11/23/2022] Open
Abstract
Introduction The cortical auditory evoked potential allows the possibility of objectively evaluating the entire auditory system, which is desirable in the pediatric population. Bone conduction auditory stimulation is recommended in the differential diagnosis of conductive hearing loss. However, there are not many studies of cortical auditory evoked potential using bone conduction. Objective The aim of this study was to characterize the response of cortical auditory evoked potential through bone conduction in normal-hearing neonates using an automated response analysis equipment. Methods This study included 30 normal-hearing neonates, without risk factors for hearing loss. The equipment used was the HEARlab automated response analysis and the cortical responses were evaluated at the frequencies of 500–4000 Hz through bone conduction, at intensity ranging from 0 to 60 dBnHL. The latencies and amplitudes were manually marked by experienced judges. Results Cortical auditory evoked potential responses were detected in 100% of the evaluated subjects and there was no difference regarding the cortical response of the neonates in relation to the variables of gender, ear and masking use. At an intensity of 60 dBnHL for the frequencies of 500, 1000, 2000 and 4000 Hz the latencies were 234; 241; 239 and 253 ms and the amplitudes were 15.6; 8.4; 6.2; 6.3 μV. The mean thresholds were 23.6; 28; 31 and 33.1 dBnHL, respectively. Conclusion It was possible to measure the cortical auditory evoked potential response in the neonatal population using bone vibrator as sound transducer and to draw the profile of the cortical auditory evoked potential latencies and amplitudes by frequencies at the intensity of 60 dBnHL and at the threshold.
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