Salient features of otoacoustic emissions are common across tetrapod groups and suggest shared properties of generation mechanisms.
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ABSTRACT:
SUBMITTER: Bergevin C
PROVIDER: S-EPMC4371923 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Objective: To investigate whether otoacoustic emissions (OAEs) are impaired in patients with myasthenia gravis (MG) and whether such dysfunction is associated with serological and electrophysiological features of MG. Methods: We tested 15 patients with MG (30 ears) and 10 healthy age- and sex-matched subjects (20 ears) for transiently evoked OAE (TEOAE) and distortion product OAE (DPOAE). Results: Compared with controls, MG patients revealed a significant reduction in the amplitude of TEOAEs (p < 0.05) and DPOAEs at higher frequencies between 2,026 and 4,053 Hz (p < 0.05). In the subgroup analysis, TEOAE and DPOAE amplitudes were significantly lower in the acetylcholine receptor (AChR) antibody-positive group (p < 0.05) as well as in the repetitive nerve stimulation (RNS)-positive (p < 0.05) group. In particular, the OAE alteration significantly correlated with anti-AChR antibody titers. No significant difference of the OAEs was found between thymomatous and non-thymomatous MG or between purely ocular and generalized MG. Conclusions: Our study confirms that OAEs reveal subclinical dysfunction of the cholinergic neurotransmission of cochlear outer hair cells and correlate well with electrophysiological and serological characteristics of MG patients. Our findings imply that the measurement of OAEs might increase the diagnostic accuracy and help to monitor the severity of MG.
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Project description:BACKGROUND:Advances in next-generation sequencing (NGS) of antibody repertoires have led to an explosion in B cell receptor sequence data from donors with many different disease states. These data have the potential to detect patterns of immune response across populations. However, to this point it has been difficult to interpret such patterns of immune response between disease states in the absence of functional data. There is a need for a robust method that can be used to distinguish general patterns of immune responses at the antibody repertoire level. RESULTS:We developed a method for reducing the complexity of antibody repertoire datasets using principal component analysis (PCA) and refer to our method as "repertoire fingerprinting." We reduce the high dimensional space of an antibody repertoire to just two principal components that explain the majority of variation in those repertoires. We show that repertoires from individuals with a common experience or disease state can be clustered by their repertoire fingerprints to identify common antibody responses. CONCLUSIONS:Our repertoire fingerprinting method for distinguishing immune repertoires has implications for characterizing an individual disease state. Methods to distinguish disease states based on pattern recognition in the adaptive immune response could be used to develop biomarkers with diagnostic or prognostic utility in patient care. Extending our analysis to larger cohorts of patients in the future should permit us to define more precisely those characteristics of the immune response that result from natural infection or autoimmunity.
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Project description:Long-delay components showing a symmetrical pattern with positive and negative delays can be observed in the time-frequency representation (or in the inverse Fourier transform) of distortion product otoacoustic emissions. Positive-only phase-gradient delays are predicted by place-fixed backscattering mechanisms, such as coherent reflection due to roughness, whereas the nonlinear distortion wave-fixed mechanism should generate an almost null-delay component. The symmetrical delay pattern arises whenever spectral amplitude fluctuations are not fully correlated to phase fluctuations. An interpretation of this phenomenon is proposed, involving place-fixed modulation of the spectral strength of the wave-fixed nonlinear generator. Experimental data are shown in which these negative-delay sources are particularly strong, and further amplified by contralateral stimulation, suggesting that this effect could be dynamically enhanced. Analytical solutions of a linear 1-d transmission line model, in which cubic nonlinearity and roughness were added as small perturbations, have been used to test this hypothesis.
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Project description:OBJECTIVES:The purpose of this study was to analyze distortion product otoacoustic emission (DPOAE) level and signal to noise ratio in a group of infants from birth to 4 months of age to optimize prediction of hearing status. DPOAEs from infants with normal hearing (NH) and hearing loss (HL) were used to predict the presence of conductive HL (CHL), sensorineural HL (SNHL), and mixed HL (MHL). Wideband ambient absorbance was also measured and compared among the HL types. DESIGN:This is a prospective, longitudinal study of 279 infants with verified NH and HL, including conductive, sensorineural, and mixed types that were enrolled from a well-baby nursery and two neonatal intensive care units in Cincinnati, Ohio. At approximately 1 month of age, DPOAEs (1-8?kHz), wideband absorbance (0.25-8?kHz), and air and bone conduction diagnostic tone burst auditory brainstem response (0.5-4?kHz) thresholds were measured. Hearing status was verified at approximately 9 months of age with visual reinforcement audiometry (0.5-4?kHz). Auditory brainstem response air conduction thresholds were used to assign infants to an NH or HL group, and the efficacy of DPOAE data to classify ears as NH or HL was analyzed using receiver operating characteristic (ROC) curves. Two summary statistics of the ROC curve were calculated: the area under the ROC curve and the point of symmetry on the curve at which the sensitivity and specificity were equal. DPOAE level and signal to noise ratio cutoff values were defined at each frequency as the symmetry point on their respective ROC curve, and DPOAE results were combined across frequency in a multifrequency analysis to predict the presence of HL. RESULTS:Single-frequency test performance of DPOAEs was best at mid to high frequencies (3-8?kHz) with intermediate performance at 1.5 and 2?kHz and chance performance at 1?kHz. Infants with a conductive component to their HL (CHL and MHL combined) displayed significantly lower ambient absorbance values than the NH group. No differences in ambient absorbance were found between the NH and SNHL groups. Multifrequency analysis resulted in the best prediction of HL for the SNHL/MHL group with poorer sensitivity values when infants with CHL were included. CONCLUSIONS:Clinical interpretation of DPOAEs in infants can be improved by using age-appropriate normative ranges and optimized cutoff values. DPOAE interpretation is most predictive at higher F2 test frequencies in young infants (2-8?kHz) due to poor test performance at 1 to 1.5?kHz. Multifrequency rules can be used to improve sensitivity while balancing specificity. Last, a sensitive middle ear measure such as wideband absorbance should be included in the test battery to assess possibility of a conductive component to the HL.
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Project description:The tectorial membrane (TM) is widely believed to play an important role in determining the ear's ability to detect and resolve incoming acoustic information. While it is still unclear precisely what that role is, the TM has been hypothesized to help overcome viscous forces and thereby sharpen mechanical tuning of the sensory cells. Lizards present a unique opportunity to further study the role of the TM given the diverse inner-ear morphological differences across species. Furthermore, stimulus-frequency otoacoustic emissions (SFOAEs), sounds emitted by the ear in response to a tone, noninvasively probe the frequency selectivity of the ear. We report estimates of auditory tuning derived from SFOAEs for 12 different species of lizards with widely varying TM morphology. Despite gross anatomical differences across the species examined herein, low-level SFOAEs were readily measurable in all ears tested, even in non-TM species whose basilar papilla contained as few as 50-60 hair cells. Our measurements generally support theoretical predictions: longer delays/sharper tuning features are found in species with a TM relative to those without. However, SFOAEs from at least one non-TM species (Anolis) with long delays suggest there are likely additional micromechanical factors at play that can directly affect tuning. Additionally, in the one species examined with a continuous TM (Aspidoscelis) where cell-to-cell coupling is presumably relatively stronger, delays were intermediate. This observation appears consistent with recent reports that suggest the TM may play a more complex macromechanical role in the mammalian cochlea via longitudinal energy distribution (and thereby affect tuning). Although significant differences exist between reptilian and mammalian auditory biophysics, understanding lizard OAE generation mechanisms yields significant insight into fundamental principles at work in all vertebrate ears.
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Project description:The theory that glaucoma patients have a lower intracranial pressure (ICP) than healthy subjects is a controversial one. The aim of this study was to assess ICP noninvasively by determining the relationship between distortion product otoacoustic emission (DPOAE) phase and body position and to compare this relationship between patients with primary open angle glaucoma (POAG), patients with normal tension glaucoma (NTG), and controls. The relationship was also calibrated using published data regarding invasive measurements of ICP versus body position. DPOAEs were measured in 30 controls and 32 glaucoma patients (17 POAG, 15 NTG) at the following body positions (assuming 90° as upright): 45, 30, 20, 10, 0 (supine), -10, and -20°. DPOAE phase had a clear, nonlinear relationship with body position. The mean DPOAE phase shifts between the two most extreme body positions (45 to -20°) were 73.6, 80.7, and 66.3° for healthy, POAG, and NTG, respectively (P = 0.73), and the groups showed the same, nonlinear behaviour. This indicates that there is no evidence that glaucoma patients have a reduced ICP. When calibrated with invasive data, ICP and DPOAE phase were linearly related over an ICP of 3 mmHg. This suggests that, more broadly, DPOAEs could be used in the future to monitor changes in ICP in a clinical setting and to measure dynamic changes in ICP such as diurnal fluctuations or changes induced by certain medications.
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Project description:The human auditory system is exceptional at comprehending an individual speaker even in complex acoustic environments. Because the inner ear, or cochlea, possesses an active mechanism that can be controlled by subsequent neural processing centers through descending nerve fibers, it may already contribute to speech processing. The cochlear activity can be assessed by recording otoacoustic emissions (OAEs), but employing these emissions to assess speech processing in the cochlea is obstructed by the complexity of natural speech. Here, we develop a novel methodology to measure OAEs that are related to the time-varying harmonic structure of speech [speech-distortion-product OAEs (DPOAEs)]. We then employ the method to investigate the effect of selective attention on the speech-DPOAEs. We provide tentative evidence that the speech-DPOAEs are larger when the corresponding speech signal is attended than when it is ignored. Our development of speech-DPOAEs opens up a path to further investigations of the contribution of the cochlea to the processing of complex real-world signals.
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Project description:Objective The virus called SARS-CoV-2, which is known as the first epidemic of the twenty-first century, is known to affect the central and peripheral nervous system. In the literature, complaints of sudden hearing loss, tinnitus, and vertigo have been reported in the patients. The aim of this study is to objectively reveal the effect of the coronavirus disease 2019 on the efferent auditory system. Methods Twenty-three participants, who had the coronavirus disease 2019, were included in the study group, while 20 healthy participants were included in the control group. The test of transient otoacoustic emissions with contralateral suppression was applied to individuals who had normal audiological and immitansmetric evaluations findings. Results In audiological evaluation, a significant difference was observed between the groups in the 125–500 Hz low frequency range and 4 kHz–12.5 kHz high frequency range. In the test of TEOAE and TEOAE with contralateral suppression, a significant difference was observed between the groups at 4 kHz. Conclusion The effect of the coronavirus disease 2019 on the peripheral hearing system has been shown. Its effect on the efferent hearing system in the high frequency region has been revealed. Supplementary Information The online version contains supplementary material available at 10.1186/s43163-022-00231-z.
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Project description:Distinct forms of age-related hearing loss are hypothesized based on evidence from animal models of aging, which are identifiable in human audiograms. The Sensory phenotype results from damage (e.g., excessive noise or ototoxic drugs) to outer hair cells and sometimes inner hair cells, producing large threshold increases predominately at high frequencies. The Metabolic phenotype results from a decline in endocochlear potential that can reduce outer hair cell motility throughout the cochlea, producing gradually sloping thresholds from lower to higher frequencies. Finally, the combined Metabolic?+?Sensory phenotype results in low-frequency losses similar to the Metabolic phenotype and high-frequency losses similar to the Sensory phenotype. Because outer hair cell function appears to be affected differently in each phenotype, this study used audiograms from 618 adults aged 50 to 93 years ( n?=?1,208 ears) to classify phenotypes and characterize differences in transient-evoked otoacoustic emission (TEOAE) data. Significant phenotype differences were observed in frequency-band TEOAEs and configuration (intercept and slope), including large and broadly distributed TEOAE reductions for Metabolic and Metabolic?+?Sensory ears and more focused high-frequency TEOAE reductions for Sensory ears. These findings are consistent with metabolic declines that reduce cochlear amplification across a broad range of frequencies and more basally situated, high-frequency declines in sensory hearing loss. The results provide further validation for the classification of age-related hearing loss phenotypes based on audiograms and show human TEOAE declines that are highly consistent with animal models.
| S-EPMC6131303 | biostudies-literature
Project description:Stimulus-frequency otoacoustic emissions (SFOAEs) can be useful tools for assessing cochlear function noninvasively. However, there is a lack of reports describing their utility in predicting hearing capabilities. Data for model training were collected from 245 and 839 ears with normal hearing and sensorineural hearing loss, respectively. Based on SFOAEs, this study developed an objective assessment system consisting of three mutually independent modules, with the routine test module and the fast test module used for threshold prediction and the hearing screening module for identifying hearing loss. Results evaluated via cross-validation show that the routine test module and the fast test module predict hearing thresholds with similar performance from 0.5 to 8 kHz, with mean absolute errors of 7.06-11.61 dB for the routine module and of 7.40-12.60 dB for the fast module. However, the fast module involves less test time than is needed in the routine module. The hearing screening module identifies hearing status with a large area under the receiver operating characteristic curve (0.912-0.985), high accuracy (88.4-95.9%), and low false negative rate (2.9-7.0%) at 0.5-8 kHz. The three modules are further validated on unknown data, and the results are similar to those obtained through cross-validation, indicating these modules can be well generalized to new data. Both the routine module and fast module are potential tools for predicting hearing thresholds. However, their prediction performance in ears with hearing loss requires further improvement to facilitate their clinical utility. The hearing screening module shows promise as a clinical tool for identifying hearing loss.
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