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Capshaw G, Diebold CA, Adams DM, Rayner J, Wilkinson GS, Moss CF, Lauer AM. Resistance to age-related hearing loss in the echolocating big brown bat ( Eptesicus fuscus ). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.15.603592. [PMID: 39071368 PMCID: PMC11275774 DOI: 10.1101/2024.07.15.603592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Hearing mediates many behaviors critical for survival in echolocating bats, including foraging and navigation. Most mammals are susceptible to progressive age-related hearing loss; however, the evolution of biosonar, which requires the ability to hear low-intensity echoes from outgoing sonar signals, may have selected against the development of hearing deficits in echolocating bats. Although many echolocating bats exhibit exceptional longevity and rely on acoustic behaviors for survival to old age, relatively little is known about the aging bat auditory system. In this study, we used DNA methylation to estimate the ages of wild-caught big brown bats ( Eptesicus fuscus ) and measured hearing sensitivity in young and aging bats using auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs). We found no evidence for hearing deficits in aging bats, demonstrated by comparable thresholds and similar ABR wave and DPOAE amplitudes across age groups. We additionally found no significant histological evidence for cochlear aging, with similar hair cell counts, afferent, and efferent innervation patterns in young and aging bats. Here we demonstrate that big brown bats show minimal evidence for age-related loss of peripheral hearing sensitivity and therefore represent informative models for investigating mechanisms that may preserve hearing function over a long lifetime.
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Dias JW, McClaskey CM, Alvey AP, Lawson A, Matthews LJ, Dubno JR, Harris KC. Effects of age and noise exposure history on auditory nerve response amplitudes: A systematic review, study, and meta-analysis. Hear Res 2024; 447:109010. [PMID: 38744019 PMCID: PMC11135078 DOI: 10.1016/j.heares.2024.109010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 04/08/2024] [Accepted: 04/18/2024] [Indexed: 05/16/2024]
Abstract
Auditory nerve (AN) function has been hypothesized to deteriorate with age and noise exposure. Here, we perform a systematic review of published studies and find that the evidence for age-related deficits in AN function is largely consistent across the literature, but there are inconsistent findings among studies of noise exposure history. Further, evidence from animal studies suggests that the greatest deficits in AN response amplitudes are found in noise-exposed aged mice, but a test of the interaction between effects of age and noise exposure on AN function has not been conducted in humans. We report a study of our own examining differences in the response amplitude of the compound action potential N1 (CAP N1) between younger and older adults with and without a self-reported history of noise exposure in a large sample of human participants (63 younger adults 18-30 years of age, 103 older adults 50-86 years of age). CAP N1 response amplitudes were smaller in older than younger adults. Noise exposure history did not appear to predict CAP N1 response amplitudes, nor did the effect of noise exposure history interact with age. We then incorporated our results into two meta-analyses of published studies of age and noise exposure history effects on AN response amplitudes in neurotypical human samples. The meta-analyses found that age effects across studies are robust (r = -0.407), but noise exposure effects are weak (r = -0.152). We conclude that noise exposure effects may be highly variable depending on sample characteristics, study design, and statistical approach, and researchers should be cautious when interpreting results. The underlying pathology of age-related and noise-induced changes in AN function are difficult to determine in living humans, creating a need for longitudinal studies of changes in AN function across the lifespan and histological examination of the AN from temporal bones collected post-mortem.
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Affiliation(s)
- James W Dias
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States.
| | - Carolyn M McClaskey
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - April P Alvey
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - Abigail Lawson
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - Lois J Matthews
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - Judy R Dubno
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - Kelly C Harris
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
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Temboury-Gutierrez M, Märcher-Rørsted J, Bille M, Yde J, Encina-Llamas G, Hjortkjær J, Dau T. Electrocochleographic frequency-following responses as a potential marker of age-related cochlear neural degeneration. Hear Res 2024; 446:109005. [PMID: 38598943 DOI: 10.1016/j.heares.2024.109005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 03/19/2024] [Accepted: 04/01/2024] [Indexed: 04/12/2024]
Abstract
Auditory nerve (AN) fibers that innervate inner hair cells in the cochlea degenerate with advancing age. It has been proposed that age-related reductions in brainstem frequency-following responses (FFR) to the carrier of low-frequency, high-intensity pure tones may partially reflect this neural loss in the cochlea (Märcher-Rørsted et al., 2022). If the loss of AN fibers is the primary factor contributing to age-related changes in the brainstem FFR, then the FFR could serve as an indicator of cochlear neural degeneration. In this study, we employed electrocochleography (ECochG) to investigate the effects of age on frequency-following neurophonic potentials, i.e., neural responses phase-locked to the carrier frequency of the tone stimulus. We compared these findings to the brainstem-generated FFRs obtained simultaneously using the same stimulation. We conducted recordings in young and older individuals with normal hearing. Responses to pure tones (250 ms, 516 and 1086 Hz, 85 dB SPL) and clicks were recorded using both ECochG at the tympanic membrane and traditional scalp electroencephalographic (EEG) recordings of the FFR. Distortion product otoacoustic emissions (DPOAE) were also collected. In the ECochG recordings, sustained AN neurophonic (ANN) responses to tonal stimulation, as well as the click-evoked compound action potential (CAP) of the AN, were significantly reduced in the older listeners compared to young controls, despite normal audiometric thresholds. In the EEG recordings, brainstem FFRs to the same tone stimulation were also diminished in the older participants. Unlike the reduced AN CAP response, the transient-evoked wave-V remained unaffected. These findings could indicate that a decreased number of AN fibers contributes to the response in the older participants. The results suggest that the scalp-recorded FFR, as opposed to the clinical standard wave-V of the auditory brainstem response, may serve as a more reliable indicator of age-related cochlear neural degeneration.
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Affiliation(s)
- Miguel Temboury-Gutierrez
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark.
| | - Jonatan Märcher-Rørsted
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark
| | - Michael Bille
- Copenhagen Hearing and Balance Center, Ear, Nose and Throat (ENT) and Audiology Clinic, Rigshospitalet, Copenhagen University Hospital, Denmark, Inge Lehmanns Vej 8, DK-2100 København Ø, Denmark
| | - Jesper Yde
- Copenhagen Hearing and Balance Center, Ear, Nose and Throat (ENT) and Audiology Clinic, Rigshospitalet, Copenhagen University Hospital, Denmark, Inge Lehmanns Vej 8, DK-2100 København Ø, Denmark
| | - Gerard Encina-Llamas
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark; Copenhagen Hearing and Balance Center, Ear, Nose and Throat (ENT) and Audiology Clinic, Rigshospitalet, Copenhagen University Hospital, Denmark, Inge Lehmanns Vej 8, DK-2100 København Ø, Denmark; Faculty of Medicine. University of Vic - Central University of Catalonia (UVic-UCC), Vic, 08500, Catalonia - Spain
| | - Jens Hjortkjær
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark; Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Kettegård Allé 30, DK-2650 Hvidovre, Denmark
| | - Torsten Dau
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark
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Mellott JG, Duncan S, Busby J, Almassri LS, Wawrzyniak A, Iafrate MC, Ohl AP, Slabinski EA, Beaver AM, Albaba D, Vega B, Mafi AM, Buerke M, Tokar NJ, Young JW. Age-related upregulation of dense core vesicles in the central inferior colliculus. Front Cell Neurosci 2024; 18:1396387. [PMID: 38774486 PMCID: PMC11107844 DOI: 10.3389/fncel.2024.1396387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 04/11/2024] [Indexed: 05/24/2024] Open
Abstract
Presbycusis is one of the most prevalent disabilities in aged populations of industrialized countries. As we age less excitation reaches the central auditory system from the periphery. To compensate, the central auditory system [e.g., the inferior colliculus (IC)], downregulates GABAergic inhibition to maintain homeostatic balance. However, the continued downregulation of GABA in the IC causes a disruption in temporal precision related to presbycusis. Many studies of age-related changes to neurotransmission in the IC have therefore focused on GABAergic systems. However, we have discovered that dense core vesicles (DCVs) are significantly upregulated with age in the IC. DCVs can carry neuropeptides, co-transmitters, neurotrophic factors, and proteins destined for the presynaptic zone to participate in synaptogenesis. We used immuno transmission electron microscopy across four age groups (3-month; 19-month; 24-month; and 28-month) of Fisher Brown Norway rats to examine the ultrastructure of DCVs in the IC. Tissue was stained post-embedding for GABA immunoreactivity. DCVs were characterized by diameter and by the neurochemical profile (GABAergic/non-GABAergic) of their location (bouton, axon, soma, and dendrite). Our data was collected across the dorsolateral to ventromedial axis of the central IC. After quantification, we had three primary findings. First, the age-related increase of DCVs occurred most robustly in non-GABAergic dendrites in the middle and low frequency regions of the central IC during middle age. Second, the likelihood of a bouton having more than one DCV increased with age. Lastly, although there was an age-related loss of terminals throughout the IC, the proportion of terminals that contained at least one DCV did not decline. We interpret this finding to mean that terminals carrying proteins packaged in DCVs are spared with age. Several recent studies have demonstrated a role for neuropeptides in the IC in defining cell types and regulating inhibitory and excitatory neurotransmission. Given the age-related increase of DCVs in the IC, it will be critical that future studies determine whether (1) specific neuropeptides are altered with age in the IC and (2) if these neuropeptides contribute to the loss of inhibition and/or increase of excitability that occurs during presbycusis and tinnitus.
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Affiliation(s)
- Jeffrey G. Mellott
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
- University Hospitals Hearing Research Center, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Syllissa Duncan
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Justine Busby
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Laila S. Almassri
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
- University Hospitals Hearing Research Center, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Alexa Wawrzyniak
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Milena C. Iafrate
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Andrew P. Ohl
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Elizabeth A. Slabinski
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Abigail M. Beaver
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Diana Albaba
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Brenda Vega
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Amir M. Mafi
- The Ohio State University College of Medicine, Columbus, OH, United States
| | - Morgan Buerke
- Department of Psychology, Louisiana State University, Baton Rouge, LA, United States
| | - Nick J. Tokar
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
| | - Jesse W. Young
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, United States
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Wang X, Nie S, Wen Y, Zhao Z, Li J, Wang N, Zhang J. Age-related differences in auditory spatial processing revealed by acoustic change complex. Front Hum Neurosci 2024; 18:1342931. [PMID: 38681742 PMCID: PMC11045960 DOI: 10.3389/fnhum.2024.1342931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 04/01/2024] [Indexed: 05/01/2024] Open
Abstract
Objectives The auditory spatial processing abilities mature throughout childhood and degenerate in older adults. This study aimed to compare the differences in onset cortical auditory evoked potentials (CAEPs) and location-evoked acoustic change complex (ACC) responses among children, adults, and the elderly and to investigate the impact of aging and development on ACC responses. Design One hundred and seventeen people were recruited in the study, including 57 typically-developed children, 30 adults, and 30 elderlies. The onset-CAEP evoked by white noise and ACC by sequential changes in azimuths were recorded. Latencies and amplitudes as a function of azimuths were analyzed using the analysis of variance, Pearson correlation analysis, and multiple linear regression model. Results The ACC N1'-P2' amplitudes and latencies in adults, P1'-N1' amplitudes in children, and N1' amplitudes and latencies in the elderly were correlated with angles of shifts. The N1'-P2' and P2' amplitudes decreased in the elderly compared to adults. In Children, the ACC P1'-N1' responses gradually differentiated into the P1'-N1'-P2' complex. Multiple regression analysis showed that N1'-P2' amplitudes (R2 = 0.33) and P2' latencies (R2 = 0.18) were the two most variable predictors in adults, while in the elderly, N1' latencies (R2 = 0.26) explained most variances. Although the amplitudes of onset-CAEP differed at some angles, it could not predict angle changes as effectively as ACC responses. Conclusion The location-evoked ACC responses varied among children, adults, and the elderly. The N1'-P2' amplitudes and P2' latencies in adults and N1' latencies in the elderly explained most variances of changes in spatial position. The differentiation of the N1' waveform was observed in children. Further research should be conducted across all age groups, along with behavioral assessments, to confirm the relationship between aging and immaturity in objective ACC responses and poorer subjective spatial performance. Significance ACCs evoked by location changes were assessed in adults, children, and the elderly to explore the impact of aging and development on these differences.
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Affiliation(s)
| | | | | | | | | | - Ningyu Wang
- Department of Otolaryngology-Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Juan Zhang
- Department of Otolaryngology-Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
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Dias JW, McClaskey CM, Alvey AP, Lawson A, Matthews LJ, Dubno JR, Harris KC. Effects of Age and Noise Exposure History on Auditory Nerve Response Amplitudes: A Systematic Review, Study, and Meta-Analysis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.20.585882. [PMID: 38585917 PMCID: PMC10996537 DOI: 10.1101/2024.03.20.585882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Auditory nerve (AN) function has been hypothesized to deteriorate with age and noise exposure. Here, we perform a systematic review of published studies and find that the evidence for age-related deficits in AN function is largely consistent across the literature, but there are inconsistent findings among studies of noise exposure history. Further, evidence from animal studies suggests that the greatest deficits in AN response amplitudes are found in noise-exposed aged mice, but a test of the interaction between effects of age and noise exposure on AN function has not been conducted in humans. We report a study of our own examining differences in the response amplitude of the compound action potential N1 (CAP N1) between younger and older adults with and without a self-reported history of noise exposure in a large sample of human participants (63 younger adults 18-30 years of age, 103 older adults 50-86 years of age). CAP N1 response amplitudes were smaller in older than younger adults. Noise exposure history did not appear to predict CAP N1 response amplitudes, nor did the effect of noise exposure history interact with age. We then incorporated our results into two meta-analyses of published studies of age and noise exposure history effects on AN response amplitudes in neurotypical human samples. The meta-analyses found that age effects across studies are robust (r=-0.407), but noise-exposure effects are weak (r=-0.152). We conclude that noise-exposure effects may be highly variable depending on sample characteristics, study design, and statistical approach, and researchers should be cautious when interpreting results. The underlying pathology of age-related and noise-induced changes in AN function are difficult to determine in living humans, creating a need for longitudinal studies of changes in AN function across the lifespan and histological examination of the AN from temporal bones collected post-mortem.
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Affiliation(s)
- James W Dias
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Carolyn M McClaskey
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - April P Alvey
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Abigail Lawson
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Lois J Matthews
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Judy R Dubno
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Kelly C Harris
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
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McClaskey CM. Neural hyperactivity and altered envelope encoding in the central auditory system: Changes with advanced age and hearing loss. Hear Res 2024; 442:108945. [PMID: 38154191 PMCID: PMC10942735 DOI: 10.1016/j.heares.2023.108945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 12/04/2023] [Accepted: 12/22/2023] [Indexed: 12/30/2023]
Abstract
Temporal modulations are ubiquitous features of sound signals that are important for auditory perception. The perception of temporal modulations, or temporal processing, is known to decline with aging and hearing loss and negatively impact auditory perception in general and speech recognition specifically. However, neurophysiological literature also provides evidence of exaggerated or enhanced encoding of specifically temporal envelopes in aging and hearing loss, which may arise from changes in inhibitory neurotransmission and neuronal hyperactivity. This review paper describes the physiological changes to the neural encoding of temporal envelopes that have been shown to occur with age and hearing loss and discusses the role of disinhibition and neural hyperactivity in contributing to these changes. Studies in both humans and animal models suggest that aging and hearing loss are associated with stronger neural representations of both periodic amplitude modulation envelopes and of naturalistic speech envelopes, but primarily for low-frequency modulations (<80 Hz). Although the frequency dependence of these results is generally taken as evidence of amplified envelope encoding at the cortex and impoverished encoding at the midbrain and brainstem, there is additional evidence to suggest that exaggerated envelope encoding may also occur subcortically, though only for envelopes with low modulation rates. A better understanding of how temporal envelope encoding is altered in aging and hearing loss, and the contexts in which neural responses are exaggerated/diminished, may aid in the development of interventions, assistive devices, and treatment strategies that work to ameliorate age- and hearing-loss-related auditory perceptual deficits.
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Affiliation(s)
- Carolyn M McClaskey
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Ave, MSC 550, Charleston, SC 29425, United States.
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Stahl AN, Racca JM, Kerley CI, Anderson A, Landman B, Hood LJ, Gifford RH, Rex TS. Comprehensive behavioral and physiologic assessment of peripheral and central auditory function in individuals with mild traumatic brain injury. Hear Res 2024; 441:108928. [PMID: 38086151 DOI: 10.1016/j.heares.2023.108928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/27/2023]
Abstract
Auditory complaints are frequently reported by individuals with mild traumatic brain injury (mTBI) yet remain difficult to detect in the absence of clinically significant hearing loss. This highlights a growing need to identify sensitive indices of auditory-related mTBI pathophysiology beyond pure-tone thresholds for improved hearing healthcare diagnosis and treatment. Given the heterogeneity of mTBI etiology and the diverse peripheral and central processes required for normal auditory function, the present study sought to determine the audiologic assessments sensitive to mTBI pathophysiology at the group level using a well-rounded test battery of both peripheral and central auditory system function. This test battery included pure-tone detection thresholds, word understanding in quiet, sentence understanding in noise, distortion product otoacoustic emissions (DPOAEs), middle-ear muscle reflexes (MEMRs), and auditory evoked potentials (AEPs), including auditory brainstem responses (ABRs), middle latency responses (MLRs), and late latency responses (LLRs). Each participant also received magnetic resonance imaging (MRI). Compared to the control group, we found that individuals with mTBI had reduced DPOAE amplitudes that revealed a compound effect of age, elevated MEMR thresholds for an ipsilateral broadband noise elicitor, longer ABR Wave I latencies for click and 4 kHz tone burst elicitors, longer ABR Wave III latencies for 4 kHz tone bursts, larger MLR Na and Nb amplitudes, smaller MLR Pb amplitudes, longer MLR Pa latencies, and smaller LLR N1 amplitudes for older individuals with mTBI. Further, mTBI individuals with combined hearing difficulty and noise sensitivity had a greater number of deficits on thalamic and cortical AEP measures compared to those with only one/no self-reported auditory symptoms. This finding was corroborated with MRI, which revealed significant structural differences in the auditory cortical areas of mTBI participants who reported combined hearing difficulty and noise sensitivity, including an enlargement of left transverse temporal gyrus (TTG) and bilateral planum polare (PP). These findings highlight the need for continued investigations toward identifying individualized audiologic assessments and treatments that are sensitive to mTBI pathophysiology.
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Affiliation(s)
- Amy N Stahl
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN USA; Department of Ophthalmology & Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN USA
| | - Jordan M Racca
- Department of Hearing & Speech Sciences, Vanderbilt University Medical Center, Nashville, TN USA; Collaborative for STEM Education and Outreach, Vanderbilt Peabody College of Education, Vanderbilt University, Nashville, TN USA
| | - Cailey I Kerley
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN, USA
| | - Adam Anderson
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Bennett Landman
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN, USA
| | - Linda J Hood
- Department of Hearing & Speech Sciences, Vanderbilt University Medical Center, Nashville, TN USA
| | - René H Gifford
- Department of Hearing & Speech Sciences, Vanderbilt University Medical Center, Nashville, TN USA
| | - Tonia S Rex
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA.
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McHaney JR, Hancock KE, Polley DB, Parthasarathy A. Sensory representations and pupil-indexed listening effort provide complementary contributions to multi-talker speech intelligibility. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.13.553131. [PMID: 37645975 PMCID: PMC10462058 DOI: 10.1101/2023.08.13.553131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Optimal speech perception in noise requires successful separation of the target speech stream from multiple competing background speech streams. The ability to segregate these competing speech streams depends on the fidelity of bottom-up neural representations of sensory information in the auditory system and top-down influences of effortful listening. Here, we use objective neurophysiological measures of bottom-up temporal processing using envelope-following responses (EFRs) to amplitude modulated tones and investigate their interactions with pupil-indexed listening effort, as it relates to performance on the Quick speech in noise (QuickSIN) test in young adult listeners with clinically normal hearing thresholds. We developed an approach using ear-canal electrodes and adjusting electrode montages for modulation rate ranges, which extended the rage of reliable EFR measurements as high as 1024Hz. Pupillary responses revealed changes in listening effort at the two most difficult signal-to-noise ratios (SNR), but behavioral deficits at the hardest SNR only. Neither pupil-indexed listening effort nor the slope of the EFR decay function independently related to QuickSIN performance. However, a linear model using the combination of EFRs and pupil metrics significantly explained variance in QuickSIN performance. These results suggest a synergistic interaction between bottom-up sensory coding and top-down measures of listening effort as it relates to speech perception in noise. These findings can inform the development of next-generation tests for hearing deficits in listeners with normal-hearing thresholds that incorporates a multi-dimensional approach to understanding speech intelligibility deficits.
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Affiliation(s)
- Jacie R. McHaney
- Department of Communication Science and Disorders, University of Pittsburgh, Pittsburgh, PA
| | - Kenneth E. Hancock
- Deparment of Otolaryngology – Head and Neck Surgery, Harvard Medical School, Boston, MA
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA
| | - Daniel B. Polley
- Deparment of Otolaryngology – Head and Neck Surgery, Harvard Medical School, Boston, MA
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA
| | - Aravindakshan Parthasarathy
- Department of Communication Science and Disorders, University of Pittsburgh, Pittsburgh, PA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh PA
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10
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Karunathilake IMD, Dunlap JL, Perera J, Presacco A, Decruy L, Anderson S, Kuchinsky SE, Simon JZ. Effects of aging on cortical representations of continuous speech. J Neurophysiol 2023; 129:1359-1377. [PMID: 37096924 PMCID: PMC10202479 DOI: 10.1152/jn.00356.2022] [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: 08/24/2022] [Revised: 04/04/2023] [Accepted: 04/20/2023] [Indexed: 04/26/2023] Open
Abstract
Understanding speech in a noisy environment is crucial in day-to-day interactions and yet becomes more challenging with age, even for healthy aging. Age-related changes in the neural mechanisms that enable speech-in-noise listening have been investigated previously; however, the extent to which age affects the timing and fidelity of encoding of target and interfering speech streams is not well understood. Using magnetoencephalography (MEG), we investigated how continuous speech is represented in auditory cortex in the presence of interfering speech in younger and older adults. Cortical representations were obtained from neural responses that time-locked to the speech envelopes with speech envelope reconstruction and temporal response functions (TRFs). TRFs showed three prominent peaks corresponding to auditory cortical processing stages: early (∼50 ms), middle (∼100 ms), and late (∼200 ms). Older adults showed exaggerated speech envelope representations compared with younger adults. Temporal analysis revealed both that the age-related exaggeration starts as early as ∼50 ms and that older adults needed a substantially longer integration time window to achieve their better reconstruction of the speech envelope. As expected, with increased speech masking envelope reconstruction for the attended talker decreased and all three TRF peaks were delayed, with aging contributing additionally to the reduction. Interestingly, for older adults the late peak was delayed, suggesting that this late peak may receive contributions from multiple sources. Together these results suggest that there are several mechanisms at play compensating for age-related temporal processing deficits at several stages but which are not able to fully reestablish unimpaired speech perception.NEW & NOTEWORTHY We observed age-related changes in cortical temporal processing of continuous speech that may be related to older adults' difficulty in understanding speech in noise. These changes occur in both timing and strength of the speech representations at different cortical processing stages and depend on both noise condition and selective attention. Critically, their dependence on noise condition changes dramatically among the early, middle, and late cortical processing stages, underscoring how aging differentially affects these stages.
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Affiliation(s)
- I M Dushyanthi Karunathilake
- Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland, United States
| | - Jason L Dunlap
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland, United States
| | - Janani Perera
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland, United States
| | - Alessandro Presacco
- Institute for Systems Research, University of Maryland, College Park, Maryland, United States
| | - Lien Decruy
- Institute for Systems Research, University of Maryland, College Park, Maryland, United States
| | - Samira Anderson
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland, United States
| | - Stefanie E Kuchinsky
- Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, Maryland, United States
| | - Jonathan Z Simon
- Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland, United States
- Institute for Systems Research, University of Maryland, College Park, Maryland, United States
- Department of Biology, University of Maryland, College Park, Maryland, United States
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11
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Koehler CC, Almassri LS, Tokar N, Mafi AM, O’Hara MJ, Young JW, Mellott JG. Age-related Changes of GAD1 mRNA Expression in the Central Inferior Colliculus. TRANSLATIONAL MEDICINE OF AGING 2023; 7:20-32. [PMID: 38111912 PMCID: PMC10727507 DOI: 10.1016/j.tma.2023.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023] Open
Abstract
Encoding sounds with a high degree of temporal precision is an essential task for the inferior colliculus (IC) to perform and maintain the accurate processing of sounds and speech. However, the age-related reduction of GABAergic neurotransmission in the IC interrupts temporal precision and likely contributes to presbycusis. As presbycusis often manifests at high or low frequencies specifically, we sought to determine if the expression of mRNA for glutamic decarboxylase 1 (GAD1) is downregulated non-uniformly across the tonotopic axis or cell size range in the aging IC. Using single molecule in situ fluorescent hybridization across young, middle age and old Fisher Brown Norway rats (an aging model that acquires low frequency presbycusis) we quantified individual GAD1 mRNA in small, medium and large GABAergic cells. Our results demonstrate that small GABAergic cells in low frequency regions had ~58% less GAD1 in middle age and continued to decline into old age. In contrast, the amount of GAD1 mRNA in large cells in low frequency regions significantly increased with age. As several studies have shown that downregulation of GAD1 decreases the release of GABA, we interpret our results in two ways. First, the onset of presbycusis may be driven by small GABAergic cells downregulating GAD1. Second, as previous studies demonstrate that GAD67 expression is broadly downregulated in the old IC, perhaps the translation of GAD1 to GAD67 is interrupted in large GABAergic IC cells during aging. These results point to a potential genetic mechanism explaining reduced temporal precision in the aging IC, and in turn, presbycusis.
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Affiliation(s)
- Christina C. Koehler
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Laila S. Almassri
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Nick Tokar
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Amir M. Mafi
- The Ohio State College of Medicine The Ohio State Columbus, OH USA
| | - Mitchell J. O’Hara
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Jesse W. Young
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
| | - Jeffrey G. Mellott
- Department of Anatomy and Neurobiology Northeast Ohio Medical University Rootstown, OH USA
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12
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Gómez-Álvarez M, Johannesen PT, Coelho-de-Sousa SL, Klump GM, Lopez-Poveda EA. The Relative Contribution of Cochlear Synaptopathy and Reduced Inhibition to Age-Related Hearing Impairment for People With Normal Audiograms. Trends Hear 2023; 27:23312165231213191. [PMID: 37956654 PMCID: PMC10644751 DOI: 10.1177/23312165231213191] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 10/18/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
Older people often show auditory temporal processing deficits and speech-in-noise intelligibility difficulties even when their audiogram is clinically normal. The causes of such problems remain unclear. Some studies have suggested that for people with normal audiograms, age-related hearing impairments may be due to a cognitive decline, while others have suggested that they may be caused by cochlear synaptopathy. Here, we explore an alternative hypothesis, namely that age-related hearing deficits are associated with decreased inhibition. For human adults (N = 30) selected to cover a reasonably wide age range (25-59 years), with normal audiograms and normal cognitive function, we measured speech reception thresholds in noise (SRTNs) for disyllabic words, gap detection thresholds (GDTs), and frequency modulation detection thresholds (FMDTs). We also measured the rate of growth (slope) of auditory brainstem response wave-I amplitude with increasing level as an indirect indicator of cochlear synaptopathy, and the interference inhibition score in the Stroop color and word test (SCWT) as a proxy for inhibition. As expected, performance in the auditory tasks worsened (SRTNs, GDTs, and FMDTs increased), and wave-I slope and SCWT inhibition scores decreased with ageing. Importantly, SRTNs, GDTs, and FMDTs were not related to wave-I slope but worsened with decreasing SCWT inhibition. Furthermore, after partialling out the effect of SCWT inhibition, age was no longer related to SRTNs or GDTs and became less strongly related to FMDTs. Altogether, results suggest that for people with normal audiograms, age-related deficits in auditory temporal processing and speech-in-noise intelligibility are mediated by decreased inhibition rather than cochlear synaptopathy.
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Affiliation(s)
- Marcelo Gómez-Álvarez
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Peter T. Johannesen
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Sónia L. Coelho-de-Sousa
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Georg M. Klump
- Department of Neuroscience and Cluster of Excellence “Hearing4all”, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Enrique A. Lopez-Poveda
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
- Departamento de Cirugía, Facultad de Medicina, Universidad de Salamanca, Salamanca, Spain
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13
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Mafi AM, Tokar N, Russ MG, Barat O, Mellott JG. Age-related ultrastructural changes in the lateral cortex of the inferior colliculus. Neurobiol Aging 2022; 120:43-59. [PMID: 36116395 PMCID: PMC10276896 DOI: 10.1016/j.neurobiolaging.2022.08.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 08/15/2022] [Accepted: 08/15/2022] [Indexed: 10/15/2022]
Abstract
Temporal precision, a key component of sound and speech processing in the inferior colliculus (IC), depends on a balance of inhibition and excitation, and this balance degrades during aging. The cause of disrupted excitatory-inhibitory balance in aging is unknown, however changes at the synapse are a likely candidate. We sought to determine whether synaptic changes occur in the lateral cortex of the IC (IClc), a multimodal nucleus that processes lemniscal, intrinsic, somatosensory, and descending auditory input. Using electron microscopic techniques across young, middle age and old Fisher Brown Norway rats, our results demonstrate minimal loss of synapses in middle age, but significant (∼28%) loss during old age. However, in middle age, targeting of GABAergic dendrites by GABAergic synapses is increased and the active zones of excitatory synapses (that predominantly target GABA-negative dendrites) are lengthened. These synaptic changes likely result in a net increase of excitation in the IClc during middle age. Thus, disruption of excitatory-inhibitory balance in the aging IClc may be due to synaptic changes that begin in middle age.
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Affiliation(s)
- Amir M Mafi
- The Ohio State College of Medicine, The Ohio State, Columbus, OH, USA
| | - Nick Tokar
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Matthew G Russ
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Oren Barat
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Jeffrey G Mellott
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, OH, USA.
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Harris KC, Dias JW, McClaskey CM, Rumschlag J, Prisciandaro J, Dubno JR. Afferent Loss, GABA, and Central Gain in Older Adults: Associations with Speech Recognition in Noise. J Neurosci 2022; 42:7201-7212. [PMID: 35995564 PMCID: PMC9512571 DOI: 10.1523/jneurosci.0242-22.2022] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 07/20/2022] [Accepted: 08/14/2022] [Indexed: 11/21/2022] Open
Abstract
Deficits in auditory nerve (AN) function for older adults reduce afferent input to the cortex. The extent to which the cortex in older adults adapts to this loss of afferent input and the mechanisms underlying this adaptation are not well understood. We took a neural systems approach measuring AN and cortical evoked responses within 50 older and 27 younger human adults (59 female) to estimate central gain or increased cortical activity despite reduced AN activity. Relative to younger adults, older adults' AN response amplitudes were smaller, but cortical responses were not. We used the relationship between AN and cortical response amplitudes in younger adults to predict cortical response amplitudes for older adults from their AN responses. Central gain in older adults was thus defined as the difference between their observed cortical responses and those predicted from the parameter estimates of younger adults. In older adults, decreased afferent input contributed to lower cortical GABA levels, greater central gain, and poorer speech recognition in noise (SIN). These effects on SIN occur in addition to, and independent from, effects attributed to elevated hearing thresholds. Our results are consistent with animal models of central gain and suggest that reduced AN afferent input in some older adults may result in changes in cortical encoding and inhibitory neurotransmission, which contribute to reduced SIN. An advancement in our understanding of the changes that occur throughout the auditory system in response to the gradual loss of input with increasing age may provide potential therapeutic targets for intervention.SIGNIFICANCE STATEMENT Age-related hearing loss is one of the most common chronic conditions of aging, yet little is known about how the cortex adapts to this loss of sensory input. We measured AN and cortical responses to the same stimulus in younger and older adults. In older adults we found hyperexcitability in cortical activity relative to concomitant declines in afferent input that are consistent with central gain. Lower levels of cortical GABA, an inhibitory neurotransmitter, were associated with greater central gain, which predicted poorer SIN. The results suggest that the cortex in older adults may adapt to attenuated sensory input by reducing inhibition to amplify the cortical response, but this amplification may lead to poorer SIN.
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Affiliation(s)
| | - James W Dias
- Department of Otolaryngology-Head and Neck Surgery
| | | | | | - James Prisciandaro
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, South Carolina 29425-5500
| | - Judy R Dubno
- Department of Otolaryngology-Head and Neck Surgery
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