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PloS One 2024Neurons of the lateral superior olive (LSO) in the auditory brainstem play a fundamental role in binaural sound localization. Previous theoretical studies developed...
Neurons of the lateral superior olive (LSO) in the auditory brainstem play a fundamental role in binaural sound localization. Previous theoretical studies developed various types of neuronal models to study the physiological functions of the LSO. These models were usually tuned to a small set of physiological data with specific aims in mind. Therefore, it is unclear whether and how they can be related to each other, how widely applicable they are, and which model is suitable for what purposes. In this study, we address these questions for six different single-compartment integrate-and-fire (IF) type LSO models. The models are divided into two groups depending on their subthreshold responses: passive (linear) models with only the leak conductance and active (nonlinear) models with an additional low-voltage-activated potassium conductance that is prevalent among the auditory system. Each of these two groups is further subdivided into three subtypes according to the spike generation mechanism: one with simple threshold-crossing detection and voltage reset, one with threshold-crossing detection plus a current to mimic spike shapes, and one with a depolarizing exponential current for spiking. In our simulations, all six models were driven by identical synaptic inputs and calibrated with common criteria for binaural tuning. The resulting spike rates of the passive models were higher for intensive inputs and lower for temporally structured inputs than those of the active models, confirming the active function of the potassium current. Within each passive or active group, the simulated responses resembled each other, regardless of the spike generation types. These results, in combination with the analysis of computational costs, indicate that an active IF model is more suitable than a passive model for accurately reproducing temporal coding of LSO. The simulation of realistic spike shapes with an extended spiking mechanism added relatively small computational costs.
Topics: Models, Neurological; Superior Olivary Complex; Action Potentials; Neurons; Humans; Computer Simulation; Olivary Nucleus; Animals; Sound Localization
PubMed: 38900820
DOI: 10.1371/journal.pone.0304832 -
Diagnostics (Basel, Switzerland) Jun 2024Hearing impairment among adults with intellectual disability (ID) is notably prevalent yet frequently underdiagnosed due, in part, to the challenges associated with...
Hearing impairment among adults with intellectual disability (ID) is notably prevalent yet frequently underdiagnosed due, in part, to the challenges associated with traditional hearing screening methods in this population. This study explores the effectiveness of the Digit-in-Noise (DIN) test as a viable alternative for hearing screening within natural settings and with familiar personnel. A total of 16 Hebrew-speaking adults with ID were recruited from supported employment programs, 10 of whom completed the study. The DIN test, which was administered in a daily environment using a simple digital device, evaluated the speech recognition threshold in noise. Results indicated that while some participants performed comparably to typically developing individuals, others showed varying levels of hearing thresholds, suggesting diverse auditory capabilities within the ID population. This pilot study confirms that the DIN test can be feasibly integrated into routine care settings, offering a friendly and accessible method for assessing hearing abilities in adults with ID. The findings advocate for the broader adoption of and potential modifications to the DIN Test to enhance its applicability and inclusiveness, thereby improving diagnostic accuracy and subsequent auditory care for this underserved population.
PubMed: 38893727
DOI: 10.3390/diagnostics14111202 -
Journal of Otolaryngology - Head & Neck... 2024The long-term preservation of residual hearing after cochlear implantation has become a major goal over the past few years. The aim of the present study was to evaluate...
OBJECTIVE
The long-term preservation of residual hearing after cochlear implantation has become a major goal over the past few years. The aim of the present study was to evaluate residual hearing in the long-term follow-up using mid-scala electrodes.
METHODS
In this retrospective, single-center study, we collected data from 27 patients who were implanted between 2014 and 2015 with residual hearing in the low-frequency range using a mid-scala electrode. Measurements of the hearing thresholds were carried out directly postoperatively (day 1 after surgery) and in the long-term follow-up 43.7 ± 6.9 months. The calculation of the extent of audiological hearing preservation was determined using the HEARRING group formula by Skarsynski.
RESULTS
Postoperative preservation of residual hearing was achieved in 69.2% of the cases in the low-frequency range between 250 Hz and 1 kHz, of which 89.5% of the patients had frequencies that suggested using electroacoustic stimulation (EAS). In the long-term follow-up, 30.8% of the patients showed residual hearing; however, 57.1% had apparently benefited from EAS.
CONCLUSION
Preservation of residual hearing is feasible in the long term using mid-scala electrodes. Postoperatively, there is over the half of patients who benefit from an EAS strategy. The long-term follow-up shows a certain decrease in residual hearing. However, these results are comparable to studies relating to other types of electrodes. Further research should be conducted in future to better evaluate hearing loss in long-term follow-up, compared to direct postoperative audiological results.
Topics: Humans; Retrospective Studies; Male; Female; Cochlear Implantation; Middle Aged; Adult; Cochlear Implants; Follow-Up Studies; Hearing; Aged; Auditory Threshold; Adolescent; Child, Preschool; Treatment Outcome; Child; Electrodes, Implanted; Young Adult; Prosthesis Design; Hearing Loss; Time Factors
PubMed: 38888946
DOI: 10.1177/19160216241250351 -
Trends in Hearing 2024This multi-center study examined the safety and effectiveness of cochlear implantation of children between 9 and 11 months of age. The intended impact was to support...
This multi-center study examined the safety and effectiveness of cochlear implantation of children between 9 and 11 months of age. The intended impact was to support practice regarding candidacy assessment and prognostic counseling of pediatric cochlear implant candidates. Data in the clinical chart of children implanted at 9-11 months of age with Cochlear Ltd devices at five cochlear implant centers in the United States and Canada were included in analyses. The study included data from two cohorts implanted with one or two Nucleus devices during the periods of January 1, 2012-December 31, 2017 (Cohort 1, n = 83) or between January 1, 2018 and May 15, 2020 (Cohort 2, n = 50). Major adverse events (requiring another procedure/hospitalization) and minor adverse events (managed with medication alone or underwent an expected course of treatment that did not require surgery or hospitalization) out to 2 years post-implant were monitored and outcomes measured by audiometric thresholds and parent-reports on the IT-MAIS and LittlEARS questionnaires were collected. Results revealed 60 adverse events in 41 children and 227 ears implanted (26%) of which 14 major events occurred in 11 children; all were transitory and resolved. Improved hearing with cochlear implant use was shown in all outcome measures. Findings reveal that the procedure is safe for infants and that they show clear benefits of cochlear implantation including increased audibility and hearing development.
Topics: Humans; Infant; Cochlear Implantation; Male; Female; Cochlear Implants; Treatment Outcome; Canada; United States; Time Factors; Retrospective Studies; Auditory Threshold; Postoperative Complications
PubMed: 38887094
DOI: 10.1177/23312165241261480 -
Scientific Reports Jun 2024Low-grade chronic inflammation is associated with many age-related conditions. Non-invasive methods to monitor low-grade chronic inflammation may improve the management...
Low-grade chronic inflammation is associated with many age-related conditions. Non-invasive methods to monitor low-grade chronic inflammation may improve the management of older people at risk of poorer outcomes. This longitudinal cohort study has determined baseline inflammation using neopterin volatility in monthly urine samples of 45 independent older adults (aged 65-75 years). Measurement of neopterin, an inflammatory metabolite, enabled stratification of individuals into risk categories based on how often in a 12-month period their neopterin level was raised. Hearing was measured (pure-tone audiometry) at baseline, 1 year and 3 years of the study. Results show that those in the highest risk category (neopterin raised greater than 50% of the time) saw greater deterioration, particularly in high-frequency, hearing. A one-way Welch's ANOVA showed a significant difference between the risk categories for change in high-frequency hearing (W (3, 19.6) = 9.164, p = 0.0005). Despite the study size and duration individuals in the highest risk category were more than twice as likely to have an additional age-related morbidity than those in the lowest risk category. We conclude that volatility of neopterin in urine may enable stratification of those at greatest risk of progression of hearing loss.
Topics: Humans; Neopterin; Aged; Male; Female; Longitudinal Studies; Hearing Loss; Audiometry, Pure-Tone; Biomarkers; Auditory Threshold; Inflammation
PubMed: 38871776
DOI: 10.1038/s41598-024-64648-7 -
Redox Biology Aug 2024The ABCC1 gene belongs to the ATP-binding cassette membrane transporter superfamily, which plays a crucial role in the efflux of various endogenous and exogenous...
The ABCC1 gene belongs to the ATP-binding cassette membrane transporter superfamily, which plays a crucial role in the efflux of various endogenous and exogenous substances. Mutations in ABCC1 can result in autosomal dominant hearing loss. However, the specific roles of ABCC1 in auditory function are not fully understood. Through immunofluorescence, we found that ABCC1 was expressed in microvascular endothelial cells (ECs) of the stria vascularis (StV) in the murine cochlea. Then, an Abcc1 knockout mouse model was established by using CRISPR/Cas9 technology to elucidate the role of ABCC1 in the inner ear. The ABR threshold did not significantly differ between WT and Abcc1 mice at any age studied. After noise exposure, the ABR thresholds of the WT and Abcc1 mice were significantly elevated. Interestingly, after 14 days of noise exposure, ABR thresholds largely returned to pre-exposure levels in WT mice but not in Abcc1 mice. Our subsequent experiments showed that microvascular integrity in the StV was compromised and that the number of outer hair cells and the number of ribbons were significantly decreased in the cochleae of Abcc1 mice post-exposure. Besides, the production of ROS and the accumulation of 4-HNE significantly increased. Furthermore, StV microvascular ECs were cultured to elucidate the role of ABCC1 in these cells under glucose oxidase challenge. Notably, 30 U/L glucose oxidase (GO) induced severe oxidative stress damage in Abcc1 cells. Compared with WT cells, the ROS and 4-HNE levels and the apoptotic rate were significantly elevated in Abcc1 cells. In addition, the reduced GSH/GSSG ratio was significantly decreased in Abcc1 cells after GO treatment. Taken together, Abcc1 mice are more susceptible to noise-induced hearing loss, possibly because ABCC1 knockdown compromises the GSH antioxidant system of StV ECs. The exogenous antioxidant N-acetylcysteine (NAC) may protect against oxidative damage in Abcc1 murine cochleae and ECs.
Topics: Animals; Mice; Multidrug Resistance-Associated Proteins; Cochlea; Hearing Loss, Noise-Induced; Mice, Knockout; Antioxidants; Oxidative Stress; Disease Models, Animal; Reactive Oxygen Species; Endothelial Cells
PubMed: 38870779
DOI: 10.1016/j.redox.2024.103218 -
Trends in Hearing 2024Almost since the inception of the modern-day electroacoustic audiometer a century ago the results of pure-tone audiometry have been characterized by an audiogram. For...
Almost since the inception of the modern-day electroacoustic audiometer a century ago the results of pure-tone audiometry have been characterized by an audiogram. For almost as many years, clinicians and researchers have sought ways to distill the volume and complexity of information on the audiogram. Commonly used approaches have made use of pure-tone averages (PTAs) for various frequency ranges with the PTA for 500, 1000, 2000 and 4000 Hz (PTA4) being the most widely used for the categorization of hearing loss severity. Here, a three-digit triad is proposed as a single-number summary of not only the severity, but also the configuration and bilateral symmetry of the hearing loss. Each digit in the triad ranges from 0 to 9, increasing as the level of the pure-tone hearing threshold level (HTL) increases from a range of optimal hearing (< 10 dB Hearing Level; HL) to complete hearing loss (≥ 90 dB HL). Each digit also represents a different frequency region of the audiogram proceeding from left to right as: (Low, L) PTA for 500, 1000, and 2000 Hz; (Center, C) PTA for 3000, 4000 and 6000 Hz; and (High, H) HTL at 8000 Hz. This LCH Triad audiogram-classification system is evaluated using a large United States (U.S.) national dataset (N = 8,795) from adults 20 to 80 + years of age and two large clinical datasets totaling 8,254 adults covering a similar age range. Its ability to capture variations in hearing function was found to be superior to that of the widely used PTA4.
Topics: Adult; Aged; Aged, 80 and over; Female; Humans; Male; Middle Aged; Young Adult; Acoustic Stimulation; Audiometry, Pure-Tone; Auditory Threshold; Hearing; Hearing Loss; Predictive Value of Tests; Reproducibility of Results; Severity of Illness Index
PubMed: 38870447
DOI: 10.1177/23312165241260041 -
The Journal of International Medical... Jun 2024To investigate which factors influence the adherence to hearing aid (HA) use in elderly patients with moderate-to-severe hearing loss. (Observational Study)
Observational Study
OBJECTIVE
To investigate which factors influence the adherence to hearing aid (HA) use in elderly patients with moderate-to-severe hearing loss.
METHODS
This observational, prospective, single-centre study enrolled patients with moderate-to-severe hearing loss. They were evaluated before and 1 year after having either one or two HAs fitted.
RESULTS
A total of 86 patients were enrolled in the study and of these 69.8% (60 of 86; USER group) continued to use their HA at 1 year after fitting; six patients had not continued their use (NON-USERS). The USER group was younger than the NON-USER group, but the difference was not significant. The USER group had a significantly better unaided auditory threshold at baseline than the NON-USER group. HA use resulted in improvements in speech audiometry and auditory threshold. There was also a maintenance of cognitive function in the USER group.
CONCLUSION
Use of HA for 1 year resulted in improved auditory performance and an absence of a deterioration of cognitive function. This research was retrospectively registered under no. NCT04333043 at ClinicalTrials.gov (http://www.clinicaltrials.gov/) on the 26 March 2020. This research has been registered with the Ethics Committee of the Area Vasta Emilia Nord under number 104, date of approval 17/07/2017.
Topics: Humans; Hearing Aids; Female; Male; Aged; Prospective Studies; Hearing Loss; Patient Compliance; Aged, 80 and over; Auditory Threshold; Middle Aged; Cognition
PubMed: 38861681
DOI: 10.1177/03000605241232549 -
Laryngoscope Investigative... Jun 2024To establish audiological and other outcomes following cochlear implantation in humans and animals with eluting electrodes. (Review)
Review
OBJECTIVES
To establish audiological and other outcomes following cochlear implantation in humans and animals with eluting electrodes.
METHODS
Systematic review and narrative synthesis. Databases searched (April 2023): MEDLINE, EMBASE, CENTRAL, ClinicalTrials.gov, and Web of Science. Studies reporting outcomes in either humans or animals following cochlear implantation with a drug-eluting electrode were included. No limits were placed on language or year of publication. Risk of bias assessment was performed on all included studies using either the Brazzelli or Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) assessment tools. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement.
RESULTS
Searches identified 146 abstracts and 108 full texts. Of these, 18 studies met the inclusion criteria, reporting outcomes in 523 animals (17 studies) and 24 humans (1 study). Eluting electrodes included dexamethasone (16 studies), aracytine (1 study), nicotinamide adenine dinucleotide (1 study), the growth factors insulin-like growth factor 1 (IGF1) and hepatocyte growth factor (HGF) (1 study), and neurotrophin-3 (1 study). All included studies compare outcomes following implantation with an eluting electrode with a control non-eluting electrode. In the majority of studies, audiological outcomes (e.g., auditory brainstem response threshold) were superior following implantation with an eluting electrode compared with a standard electrode. Most studies which investigated post-implantation impedance reported lower impedance following implantation with an eluting electrode. The influence of eluting electrodes on other reported outcomes (including post-implantation cochlear fibrosis and the survival of hair cells and spiral ganglion neurons) was more varied across the included studies.
CONCLUSIONS
Eluting electrodes have shown promise in animal studies in preserving residual hearing following cochlear implantation and in reducing impedance, though data from human studies remain lacking. Further in-human studies will be required to determine the clinical usefulness of drug-eluting cochlear implants as a future treatment for sensorineural hearing loss.
PubMed: 38855776
DOI: 10.1002/lio2.1263 -
Brain and Behavior Jun 2024This study aims to control all hearing thresholds, including extended high frequencies (EHFs), presents stimuli of varying difficulty levels, and measures...
OBJECTIVE
This study aims to control all hearing thresholds, including extended high frequencies (EHFs), presents stimuli of varying difficulty levels, and measures electroencephalography (EEG) and pupillometry responses to determine whether listening difficulty in tinnitus patients is effort or fatigue-related.
METHODS
Twenty-one chronic tinnitus patients and 26 matched healthy controls having normal pure-tone averages with symmetrical hearing thresholds were included. Subjects were evaluated with 0.125-20 kHz pure-tone audiometry, Montreal Cognitive Assessment Test (MoCA), Tinnitus Handicap Inventory (THI), EEG, and pupillometry.
RESULTS
Pupil dilatation and EEG alpha power during the "encoding" phase of the presented sentence in tinnitus patients were less in all listening conditions (p < .05). Also, there was no statistically significant relationship between EEG and pupillometry components for all listening conditions and THI or MoCA (p > .05).
CONCLUSION
EEG and pupillometry results under various listening conditions indicate potential listening effort in tinnitus patients even if all frequencies, including EHFs, are controlled. Also, we suggest that pupillometry should be interpreted with caution in autonomic nervous system-related conditions such as tinnitus.
Topics: Humans; Tinnitus; Male; Female; Electroencephalography; Adult; Middle Aged; Pupil; Audiometry, Pure-Tone; Auditory Perception; Auditory Threshold
PubMed: 38841736
DOI: 10.1002/brb3.3571