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PLoS Biology Jun 2024Loss of synapses between spiral ganglion neurons and inner hair cells (IHC synaptopathy) leads to an auditory neuropathy called hidden hearing loss (HHL) characterized...
Loss of synapses between spiral ganglion neurons and inner hair cells (IHC synaptopathy) leads to an auditory neuropathy called hidden hearing loss (HHL) characterized by normal auditory thresholds but reduced amplitude of sound-evoked auditory potentials. It has been proposed that synaptopathy and HHL result in poor performance in challenging hearing tasks despite a normal audiogram. However, this has only been tested in animals after exposure to noise or ototoxic drugs, which can cause deficits beyond synaptopathy. Furthermore, the impact of supernumerary synapses on auditory processing has not been evaluated. Here, we studied mice in which IHC synapse counts were increased or decreased by altering neurotrophin 3 (Ntf3) expression in IHC supporting cells. As we previously showed, postnatal Ntf3 knockdown or overexpression reduces or increases, respectively, IHC synapse density and suprathreshold amplitude of sound-evoked auditory potentials without changing cochlear thresholds. We now show that IHC synapse density does not influence the magnitude of the acoustic startle reflex or its prepulse inhibition. In contrast, gap-prepulse inhibition, a behavioral test for auditory temporal processing, is reduced or enhanced according to Ntf3 expression levels. These results indicate that IHC synaptopathy causes temporal processing deficits predicted in HHL. Furthermore, the improvement in temporal acuity achieved by increasing Ntf3 expression and synapse density suggests a therapeutic strategy for improving hearing in noise for individuals with synaptopathy of various etiologies.
Topics: Animals; Hair Cells, Auditory, Inner; Synapses; Neurotrophin 3; Mice; Auditory Threshold; Evoked Potentials, Auditory; Reflex, Startle; Auditory Perception; Spiral Ganglion; Female; Male; Hearing Loss, Hidden
PubMed: 38935589
DOI: 10.1371/journal.pbio.3002665 -
Journal of Clinical Medicine Jun 2024The authors present the case of a young boy who experienced progressive unilateral hearing loss initially believed to be unrelated to any other medical condition. The...
The authors present the case of a young boy who experienced progressive unilateral hearing loss initially believed to be unrelated to any other medical condition. The patient received a thorough evaluation, which included a comprehensive battery of audiological tests, a CT scan, and a gadolinium-enhanced MRI. A repeated imaging investigation revealed the presence of a mass that mimicked a vestibular schwannoma (VS), but despite this, the boy was ultimately diagnosed with cerebral manifestations of B-cell acute lymphoblastic leukemia (B-ALL). Cerebral lesions originating from the internal auditory canal are rare in cases of B-ALL. In this case, the initial signs and symptoms of the disease were solely related to the audiovestibular system, making the diagnostic process particularly complicated. Unilateral hearing loss cases may indicate the presence of potentially life-threatening conditions, even if the hearing loss appears to be clinically non-syndromic. For these reasons, unilateral hearing losses necessitate a comprehensive interdisciplinary diagnostic approach from the very start of auditory manifestation and, in particular, if the hearing impairment demonstrates threshold progression.
PubMed: 38930012
DOI: 10.3390/jcm13123483 -
Brain Sciences Jun 2024Palatine and pharyngeal tonsil hypertrophy may lead to dysfunction of the auditory tube due to a propensity for infection, potentially giving rise to otitis media. This...
Palatine and pharyngeal tonsil hypertrophy may lead to dysfunction of the auditory tube due to a propensity for infection, potentially giving rise to otitis media. This is a quantitative and longitudinal study, developed from 2019 to 2021, at the State University of Campinas (UNICAMP). The studied sample comprised 15 participants aged 5 to 12 years (mean 7.9 years), 12 male and 3 female, arranged into two groups: children diagnosed with pharyngeal and/or palatine tonsil hypertrophy who were candidates for surgery (G1), and children who were later evaluated after surgery (G2). As part of the test, an otoscopy and measurements of logoaudiometry, pure-tone threshold audiometry, wideband tympanometry (ambient and peak pressure), and otoacoustic emissions (TEOAEs and DPOAEs, both at ambient and peak pressure) were all performed. There were statistically significant differences between phases in pure-tone audiometry, in terms of 226 Hz tympanometry, wideband tympanometry in peak pressure conditions, in the amplitude measurement TEOAEs in both pressure conditions, in DPOAEs in ambient pressure conditions, and in the signal/noise measurement in both pressures in DPOAEs. Overall, it was found that hearing tests were different for subjects with palatine and pharyngeal tonsil hypertrophy compared to the post-surgical group.
PubMed: 38928598
DOI: 10.3390/brainsci14060598 -
Biology Jun 2024Understanding speech in noise is particularly difficult for individuals occupationally exposed to noise due to a mix of noise-induced auditory lesions and the energetic...
Understanding speech in noise is particularly difficult for individuals occupationally exposed to noise due to a mix of noise-induced auditory lesions and the energetic masking of speech signals. For years, the monitoring of conventional audiometric thresholds has been the usual method to check and preserve auditory function. Recently, suprathreshold deficits, notably, difficulties in understanding speech in noise, has pointed out the need for new monitoring tools. The present study aims to identify the most important variables that predict speech in noise understanding in order to suggest a new method of hearing status monitoring. Physiological (distortion products of otoacoustic emissions, electrocochleography) and behavioral (amplitude and frequency modulation detection thresholds, conventional and extended high-frequency audiometric thresholds) variables were collected in a population of individuals presenting a relatively homogeneous occupational noise exposure. Those variables were used as predictors in a statistical model (random forest) to predict the scores of three different speech-in-noise tests and a self-report of speech-in-noise ability. The extended high-frequency threshold appears to be the best predictor and therefore an interesting candidate for a new way of monitoring noise-exposed professionals.
PubMed: 38927296
DOI: 10.3390/biology13060416 -
Frontiers in Neuroscience 2024Sensorineural hearing loss (SNHL) can arise from a diverse range of congenital and acquired factors. Detecting it early is pivotal for nurturing speech, language, and...
INTRODUCTION
Sensorineural hearing loss (SNHL) can arise from a diverse range of congenital and acquired factors. Detecting it early is pivotal for nurturing speech, language, and cognitive development in children with SNHL. In our study, we utilized synthetic magnetic resonance imaging (SyMRI) to assess alterations in both gray and white matter within the brains of children affected by SNHL.
METHODS
The study encompassed both children diagnosed with SNHL and a control group of children with normal hearing {1.5-month-olds ( = 52) and 3-month-olds ( = 78)}. Participants were categorized based on their auditory brainstem response (ABR) threshold, delineated into normal, mild, moderate, and severe subgroups.Clinical parameters were included and assessed the correlation with SNHL. Quantitative analysis of brain morphology was conducted using SyMRI scans, yielding data on brain segmentation and relaxation time.Through both univariate and multivariate analyses, independent factors predictive of SNHL were identified. The efficacy of the prediction model was evaluated using receiver operating characteristic (ROC) curves, with visualization facilitated through the utilization of a nomogram. It's important to note that due to the constraints of our research, we worked with a relatively small sample size.
RESULTS
Neonatal hyperbilirubinemia (NH) and children with inner ear malformation (IEM) were associated with the onset of SNHL both at 1.5 and 3-month groups. At 3-month group, the moderate and severe subgroups exhibited elevated quantitative T1 values in the inferior colliculus (IC), lateral lemniscus (LL), and middle cerebellar peduncle (MCP) compared to the normal group. Additionally, WMV, WMF, MYF, and MYV were significantly reduced relative to the normal group. Additionally, SNHL-children with IEM had high T1 values in IC, and LL and reduced WMV, WMF, MYV and MYF values as compared with SNHL-children without IEM at 3-month group. LL-T1 and WMF were independent risk factors associated with SNHL. Consequently, a prediction model was devised based on LL-T1 and WMF. ROC for training set, validation set and external set were 0.865, 0.806, and 0.736, respectively.
CONCLUSION
The integration of T1 quantitative values and brain volume segmentation offers a valuable tool for tracking brain development in children affected by SNHL and assessing the progression of the condition's severity.
PubMed: 38919907
DOI: 10.3389/fnins.2024.1365141 -
BioRxiv : the Preprint Server For... Jun 2024The vestibular short-latency evoked potential (VsEP) reflects the activity of irregular vestibular afferents and their target neurons in the brain stem. Attenuation of...
Wavelet transform of single-trial vestibular short-latency evoked potential reveals temporary reduction in signal detectability and temporal precision following noise exposure.
UNLABELLED
The vestibular short-latency evoked potential (VsEP) reflects the activity of irregular vestibular afferents and their target neurons in the brain stem. Attenuation of trial-averaged VsEP waveforms is widely accepted as an indicator of vestibular dysfunction, however, more quantitative analyses of VsEP waveforms could reveal underlying neural properties of VsEP waveforms. Here, we present a time-frequency analysis of the VsEP with a wavelet transform on a single-trial basis, which allows us to examine trial-by-trial variability in the strength of VsEP waves as well as their temporal coherence across trials. Using this method, we examined changes in the VsEP following 110 dB SPL noise exposure in rats. We found detectability of head jerks based on the power of wavelet transform coefficients was significantly reduced 1 day after noise exposure but recovered nearly to pre-exposure level in 3 - 7 days and completely by 28 days after exposure. Temporal coherence of VsEP waves across trials was also significantly reduced on 1 day after exposure but recovered with a similar time course. Additionally, we found a significant reduction in the number of calretinin-positive calyces in the sacculi collected 28 days after noise exposure. Furthermore, the number of calretinin-positive calyces was significantly correlated with the degree of reduction in temporal coherence and/or signal detectability of the smallest-amplitude jerks. This new analysis of the VsEP provides more quantitative descriptions of noise-induced changes as well as new insights into potential mechanisms underlying noise-induced vestibular dysfunction.
SIGNIFICANCE STATEMENT
Our study presents a new method of VsEP quantification using wavelet transform on a single-trial basis. It also describes a novel approach to determine the stimulus threshold of the VsEP based on signal-detection theory and Rayleigh statistics. The present analysis could also be applied to analysis of auditory brain stem response (ABR). Thus, it has the potential to provide new insights into the physiological properties that underlie peripheral vestibular and auditory dysfunction.
PubMed: 38915602
DOI: 10.1101/2024.06.10.596660 -
Noise & HealthOtitis media (OM) refers to a common clinical ear disease. Noise seriously damages human hearing function. This study aimed to investigate the effects of various noise...
BACKGROUND
Otitis media (OM) refers to a common clinical ear disease. Noise seriously damages human hearing function. This study aimed to investigate the effects of various noise types on the hearing function of patients who have recovered from mild OM.
MATERIALS AND METHODS
A total of 160 patients with mild OM treated at our hospital from May 2020 to May 2023 were retrospectively selected for this study. Based on clinical data, the patients were divided into the non-noise group (n = 80) and the noise (n = 80) group. The hearing thresholds of the two groups were compared across various noise types at 500, 1000, and 2000 Hz. In addition, the hearing thresholds of the noise group were compared under the same conditions.
RESULTS
The noise group exhibited significantly higher hearing thresholds at 500, 1000, and 2000 Hz than the non-noise group (P < 0.05). Under traffic, urban construction, and industrial noises, the auditory thresholds at 500, 1000, and 2000 Hz in the noise group were significantly higher than those observed under domestic and speech noises (P < 0.05).
CONCLUSION
Noise shows a close relationship with the hearing function of patients with OM. Traffic, urban construction, and industrial noises greatly influence the hearing function of patients who have recovered from mild OM.
Topics: Humans; Otitis Media; Male; Female; Adult; Middle Aged; Retrospective Studies; Auditory Threshold; Noise; Hearing Loss, Noise-Induced; Aged
PubMed: 38904828
DOI: 10.4103/nah.nah_6_24 -
Noise & HealthDigital noise reduction (DNR) minimizes the effect of noise on speech signals by continuously monitoring frequency bands in the presence of noise. In the present study,...
AIMS
Digital noise reduction (DNR) minimizes the effect of noise on speech signals by continuously monitoring frequency bands in the presence of noise. In the present study, we explored the effect of DNR technology on speech intelligibility in individuals using hearing aids (HAs) and investigated implications for daily use.
METHODS AND MATERIAL
Eighteen participants with bilateral moderate sensorineural hearing loss (aged 16-45 years) were included. Bilateral receiver-in-the-ear HAs were fitted in the participants. The adaptive and nonadaptive (with a signal-to-noise ratio (SNR) of +5 and -5 dB, respectively) Turkish matrix sentence test (TURMatrix) in noise and free-field hearing assessments, including hearing thresholds with hearing aids, speech recognition thresholds (SRT), and speech discrimination scores, were conducted in two different conditions: HA in the DNR-on and DNR-off conditions.
RESULTS
No significant difference was observed between free-field hearing assessments with the HA in the DNR-off and DNR-on conditions (P > 0.05). Furthermore, the adaptive and nonadaptive TURMatrix revealed significant differences between the scores under the DNR-on and DNR-off conditions (P < 0.05). Nevertheless, under the DNR-on condition, there was no correlation between free-field hearing assessments with HA and TURMatrix results (P > 0.05). However, a significant correlation was observed between SRT scores with HA and TURMatrix scores (adaptive and nonadaptive, +5 and -5 dB SNR, respectively) under the DNR-off condition (P < 0.05).
CONCLUSION
Our study findings suggest that DNR can improve speech intelligibility in noisy environments. Therefore, DNR can enhance an individual's auditory comfort by improving their capacity to grasp speech in background noise.
Topics: Humans; Hearing Aids; Adult; Noise; Male; Middle Aged; Hearing Loss, Sensorineural; Female; Young Adult; Adolescent; Speech Intelligibility; Signal-To-Noise Ratio; Auditory Threshold; Speech Perception; Speech Reception Threshold Test
PubMed: 38904826
DOI: 10.4103/nah.nah_67_23 -
Frontiers in Veterinary Science 2024Even with recent research advances, effective delivery of a compound to its target cells inside the inner ear remains a challenging endeavor due to anatomical and...
INTRODUCTION
Even with recent research advances, effective delivery of a compound to its target cells inside the inner ear remains a challenging endeavor due to anatomical and physiological barriers. Direct intracochlear drug administration with an inner ear catheter (IEC) aims to overcome this obstacle and strives to provide a safe and efficient way for inner ear pharmacotherapy. The goal of this study was to histologically and audiologically evaluate the traumatic properties of a novel IEC for intracochlear drug delivery in a large animal model.
METHODS
Seven inner ears of piglets that had undergone intracochlear fluorescein isothiocyanate dextran application via an IEC ( = 4) or round window membrane (RWM) puncture with a needle ( = 3) followed by sequential apical perilymph sampling were histologically analyzed. Additionally, obtained objective auditory compound action potential and cochlear microphonic measurements were compared. Cochlear cryosections were stained using hematoxylin and eosin, and preservation of inner ear structures was investigated. Moreover, one cochlea was methylmethacrylate-embedded and analyzed with the IEC .
RESULTS
Histological evaluation revealed an atraumatic insertion and subsequent compound application in a majority of IEC-inserted inner ears. Click cochlear compound action potential (CAP) shifts in the IEC groups reached a maximum of 5 dB (1.25 ± 2.5 dB) post administration and prior to perilymph sampling. In comparison, application by RWM puncture generated a maximum click CAP hearing threshold shift of 50 dB (23.3 ± 23.1 dB) coinciding with coagulated blood in the basal cochlear turn in one specimen of the latter group. Furthermore, histology showed an atraumatic insertion of the IEC demonstrating preserved intracochlear structures.
CONCLUSION
The IEC appears to be a promising and efficient way for inner ear drug delivery. The similarities between the porcine and human inner ear enhance the clinical translation of our findings and increase confidence regarding the safe applicability of the IEC in human subjects.
PubMed: 38903692
DOI: 10.3389/fvets.2024.1397554 -
Consciousness and Cognition Jun 2024The level-of-processing (LoP) hypothesis postulates that transition from unaware to aware visual stimuli is either graded or dichotomous depending on the depth of...
The level-of-processing (LoP) hypothesis postulates that transition from unaware to aware visual stimuli is either graded or dichotomous depending on the depth of stimulus processing. Humans can be progressively aware of the low-level features, such as colors or shapes, while the high-level features, such as semantic category, enter consciousness in an all-or none fashion. Unlike in vision, sounds always unfold in time, which might require mechanisms dissimilar from visual processing. We tested the LoP hypothesis in hearing for the first time by presenting participants with words of different categories, spoken in different pitches near the perceptual threshold. We also assessed whether different electrophysiological correlates of consciousness, the auditory awareness negativity (AAN) and late positivity (LP), were associated with LoP. Our findings indicate that LoP also applies to the auditory modality. AAN is an early correlate of awareness independent of LoP, while LP was modulated by awareness, performance accuracy and the level of processing.
PubMed: 38901129
DOI: 10.1016/j.concog.2024.103720