Publication date: Available online 12 April 2017
Source:Hearing Research
Author(s): William J. Stewart, Jacob L. Johansen, James C. Liao
Experiments on the flow-sensitive lateral line system of fishes have provided important insights into the function and sensory transduction of vertebrate hair cells. A common experimental approach has been to pharmacologically block lateral line hair cells and measure how behavior changes. Cobalt chloride (CoCl2) blocks the lateral line by inhibiting calcium movement through the membrane channels of hair cells, but high concentrations can be toxic, making it unclear whether changes in behavior are due to a blocked lateral line or poor health. Here, we identify a non-toxic treatment of cobalt that completely blocks lateral line hair cells. We exposed 5-day post fertilization zebrafish larvae to CoCl2 concentrations ranging from 1-20 mM for 15 minutes and measured 1) the spiking rate of the afferent neurons contacting hair cells and 2) the larvae’s health and long-term survival. Our results show that a 15-minute exposure to 5 mM CoCl2 abolishes both spontaneous and evoked afferent firing. This treatment does not change swimming behavior, and results in >85% survival after 5 days. Weaker treatments of CoCl2 did not eliminate afferent activity, while stronger treatments caused close to 50% mortality. Our work provides a guideline for future zebrafish investigations where physiological confirmation of a blocked lateral line system is required.
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Τετάρτη 12 Απριλίου 2017
Delayed Changes in Auditory Status in Cochlear Implant Users with Preserved Acoustic Hearing
Publication date: Available online 12 April 2017
Source:Hearing Research
Author(s): Rachel A. Scheperle, Viral D. Tejani, Julia K. Omtvedt, Carolyn J. Brown, Paul J. Abbas, Marlan R. Hansen, Bruce J. Gantz, Jacob J. Oleson, Marie V. Ozanne
This retrospective review explores delayed-onset hearing loss in 85 individuals receiving cochlear implants designed to preserve acoustic hearing at the University of Iowa Hospitals and Clinics between 2001 and 2015. Repeated measures of unaided behavioral audiometric thresholds, electrode impedance, and electrically evoked compound action potential (ECAP) amplitude growth functions were used to characterize longitudinal changes in auditory status. Participants were grouped into two primary categories according to changes in unaided behavioral thresholds: (1) stable hearing or symmetrical hearing loss and (2) delayed loss of hearing in the implanted ear. Thirty-eight percent of this sample presented with delayed-onset hearing loss of various degrees and rates of change. Neither array type nor insertion approach (round window or cochleostomy) had a significant effect on prevalence. Electrode impedance increased abruptly for many individuals exhibiting precipitous hearing loss; the increase was often transient. The impedance increases were significantly larger than the impedance changes observed for individuals with stable or symmetrical hearing loss. Moreover, the impedance changes were associated with changes in behavioral thresholds for individuals with a precipitous drop in behavioral thresholds. These findings suggest a change in the electrode environment coincident with the change in auditory status. Changes in ECAP thresholds, growth function slopes, and suprathreshold amplitudes were not correlated with changes in behavioral thresholds, suggesting that neural responsiveness in the region excited by the implant is relatively stable. Further exploration into etiology of delayed-onset hearing loss post implantation is needed, with particular interest in mechanisms associated with changes in the intracochlear environment.
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Source:Hearing Research
Author(s): Rachel A. Scheperle, Viral D. Tejani, Julia K. Omtvedt, Carolyn J. Brown, Paul J. Abbas, Marlan R. Hansen, Bruce J. Gantz, Jacob J. Oleson, Marie V. Ozanne
This retrospective review explores delayed-onset hearing loss in 85 individuals receiving cochlear implants designed to preserve acoustic hearing at the University of Iowa Hospitals and Clinics between 2001 and 2015. Repeated measures of unaided behavioral audiometric thresholds, electrode impedance, and electrically evoked compound action potential (ECAP) amplitude growth functions were used to characterize longitudinal changes in auditory status. Participants were grouped into two primary categories according to changes in unaided behavioral thresholds: (1) stable hearing or symmetrical hearing loss and (2) delayed loss of hearing in the implanted ear. Thirty-eight percent of this sample presented with delayed-onset hearing loss of various degrees and rates of change. Neither array type nor insertion approach (round window or cochleostomy) had a significant effect on prevalence. Electrode impedance increased abruptly for many individuals exhibiting precipitous hearing loss; the increase was often transient. The impedance increases were significantly larger than the impedance changes observed for individuals with stable or symmetrical hearing loss. Moreover, the impedance changes were associated with changes in behavioral thresholds for individuals with a precipitous drop in behavioral thresholds. These findings suggest a change in the electrode environment coincident with the change in auditory status. Changes in ECAP thresholds, growth function slopes, and suprathreshold amplitudes were not correlated with changes in behavioral thresholds, suggesting that neural responsiveness in the region excited by the implant is relatively stable. Further exploration into etiology of delayed-onset hearing loss post implantation is needed, with particular interest in mechanisms associated with changes in the intracochlear environment.
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A non-toxic dose of cobalt chloride blocks hair cells of the zebrafish lateral line
Publication date: Available online 12 April 2017
Source:Hearing Research
Author(s): William J. Stewart, Jacob L. Johansen, James C. Liao
Experiments on the flow-sensitive lateral line system of fishes have provided important insights into the function and sensory transduction of vertebrate hair cells. A common experimental approach has been to pharmacologically block lateral line hair cells and measure how behavior changes. Cobalt chloride (CoCl2) blocks the lateral line by inhibiting calcium movement through the membrane channels of hair cells, but high concentrations can be toxic, making it unclear whether changes in behavior are due to a blocked lateral line or poor health. Here, we identify a non-toxic treatment of cobalt that completely blocks lateral line hair cells. We exposed 5-day post fertilization zebrafish larvae to CoCl2 concentrations ranging from 1-20 mM for 15 minutes and measured 1) the spiking rate of the afferent neurons contacting hair cells and 2) the larvae’s health and long-term survival. Our results show that a 15-minute exposure to 5 mM CoCl2 abolishes both spontaneous and evoked afferent firing. This treatment does not change swimming behavior, and results in >85% survival after 5 days. Weaker treatments of CoCl2 did not eliminate afferent activity, while stronger treatments caused close to 50% mortality. Our work provides a guideline for future zebrafish investigations where physiological confirmation of a blocked lateral line system is required.
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Source:Hearing Research
Author(s): William J. Stewart, Jacob L. Johansen, James C. Liao
Experiments on the flow-sensitive lateral line system of fishes have provided important insights into the function and sensory transduction of vertebrate hair cells. A common experimental approach has been to pharmacologically block lateral line hair cells and measure how behavior changes. Cobalt chloride (CoCl2) blocks the lateral line by inhibiting calcium movement through the membrane channels of hair cells, but high concentrations can be toxic, making it unclear whether changes in behavior are due to a blocked lateral line or poor health. Here, we identify a non-toxic treatment of cobalt that completely blocks lateral line hair cells. We exposed 5-day post fertilization zebrafish larvae to CoCl2 concentrations ranging from 1-20 mM for 15 minutes and measured 1) the spiking rate of the afferent neurons contacting hair cells and 2) the larvae’s health and long-term survival. Our results show that a 15-minute exposure to 5 mM CoCl2 abolishes both spontaneous and evoked afferent firing. This treatment does not change swimming behavior, and results in >85% survival after 5 days. Weaker treatments of CoCl2 did not eliminate afferent activity, while stronger treatments caused close to 50% mortality. Our work provides a guideline for future zebrafish investigations where physiological confirmation of a blocked lateral line system is required.
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Delayed Changes in Auditory Status in Cochlear Implant Users with Preserved Acoustic Hearing
Publication date: Available online 12 April 2017
Source:Hearing Research
Author(s): Rachel A. Scheperle, Viral D. Tejani, Julia K. Omtvedt, Carolyn J. Brown, Paul J. Abbas, Marlan R. Hansen, Bruce J. Gantz, Jacob J. Oleson, Marie V. Ozanne
This retrospective review explores delayed-onset hearing loss in 85 individuals receiving cochlear implants designed to preserve acoustic hearing at the University of Iowa Hospitals and Clinics between 2001 and 2015. Repeated measures of unaided behavioral audiometric thresholds, electrode impedance, and electrically evoked compound action potential (ECAP) amplitude growth functions were used to characterize longitudinal changes in auditory status. Participants were grouped into two primary categories according to changes in unaided behavioral thresholds: (1) stable hearing or symmetrical hearing loss and (2) delayed loss of hearing in the implanted ear. Thirty-eight percent of this sample presented with delayed-onset hearing loss of various degrees and rates of change. Neither array type nor insertion approach (round window or cochleostomy) had a significant effect on prevalence. Electrode impedance increased abruptly for many individuals exhibiting precipitous hearing loss; the increase was often transient. The impedance increases were significantly larger than the impedance changes observed for individuals with stable or symmetrical hearing loss. Moreover, the impedance changes were associated with changes in behavioral thresholds for individuals with a precipitous drop in behavioral thresholds. These findings suggest a change in the electrode environment coincident with the change in auditory status. Changes in ECAP thresholds, growth function slopes, and suprathreshold amplitudes were not correlated with changes in behavioral thresholds, suggesting that neural responsiveness in the region excited by the implant is relatively stable. Further exploration into etiology of delayed-onset hearing loss post implantation is needed, with particular interest in mechanisms associated with changes in the intracochlear environment.
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Source:Hearing Research
Author(s): Rachel A. Scheperle, Viral D. Tejani, Julia K. Omtvedt, Carolyn J. Brown, Paul J. Abbas, Marlan R. Hansen, Bruce J. Gantz, Jacob J. Oleson, Marie V. Ozanne
This retrospective review explores delayed-onset hearing loss in 85 individuals receiving cochlear implants designed to preserve acoustic hearing at the University of Iowa Hospitals and Clinics between 2001 and 2015. Repeated measures of unaided behavioral audiometric thresholds, electrode impedance, and electrically evoked compound action potential (ECAP) amplitude growth functions were used to characterize longitudinal changes in auditory status. Participants were grouped into two primary categories according to changes in unaided behavioral thresholds: (1) stable hearing or symmetrical hearing loss and (2) delayed loss of hearing in the implanted ear. Thirty-eight percent of this sample presented with delayed-onset hearing loss of various degrees and rates of change. Neither array type nor insertion approach (round window or cochleostomy) had a significant effect on prevalence. Electrode impedance increased abruptly for many individuals exhibiting precipitous hearing loss; the increase was often transient. The impedance increases were significantly larger than the impedance changes observed for individuals with stable or symmetrical hearing loss. Moreover, the impedance changes were associated with changes in behavioral thresholds for individuals with a precipitous drop in behavioral thresholds. These findings suggest a change in the electrode environment coincident with the change in auditory status. Changes in ECAP thresholds, growth function slopes, and suprathreshold amplitudes were not correlated with changes in behavioral thresholds, suggesting that neural responsiveness in the region excited by the implant is relatively stable. Further exploration into etiology of delayed-onset hearing loss post implantation is needed, with particular interest in mechanisms associated with changes in the intracochlear environment.
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Brain Activity During Phonation in Women With Muscle Tension Dysphonia: An fMRI Study
Source:Journal of Voice
Author(s): Maryna Kryshtopava, Kristiane Van Lierde, Iris Meerschman, Evelien D'Haeseleer, Pieter Vandemaele, Guy Vingerhoets, Sofie Claeys
ObjectivesThe main objectives of this functional magnetic resonance imaging (fMRI) study are (1) to investigate brain activity during phonation in women with muscle tension dysphonia (MTD) in comparison with healthy controls; and (2) to explain the neurophysiological mechanism of laryngeal hyperfunction/tension during phonation in patients with MTD.MethodsTen women with MTD and fifteen healthy women participated in this study. The fMRI experiment was carried out using a block design paradigm. Brain activation during phonation and exhalation was analyzed using BrainVoyager software.ResultsThe statistical analysis of fMRI data has demonstrated that MTD patients control phonation by use of the auditory, motor, frontal, parietal, and subcortical areas similar to phonation control by healthy people. Comparison of phonation tasks in the two groups revealed higher brain activities in the precentral gyrus, inferior, middle and superior frontal gyrus, lingual gyrus, insula, cerebellum, midbrain, and brainstem as well as lower brain activities in the cingulate gyrus, superior and middle temporal gyrus, and inferior parietal lobe in the MTD group. No differences were found between the two groups regarding exhalation control.ConclusionsThe findings in this study provide insight into phonation and exhalation control in patients with MTD. The imaging results demonstrated that in patients with MTD, altered (higher/lower) brain activities may result in laryngeal tension and vocal hyperfunction.
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Acoustic and perceptual effects of magnifying interaural difference cues in a simulated "binaural" hearing aid.
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Acoustic and perceptual effects of magnifying interaural difference cues in a simulated "binaural" hearing aid.
Int J Audiol. 2017 Apr 10;:1-11
Authors: de Taillez T, Grimm G, Kollmeier B, Neher T
Abstract
OBJECTIVE: To investigate the influence of an algorithm designed to enhance or magnify interaural difference cues on speech signals in noisy, spatially complex conditions using both technical and perceptual measurements. To also investigate the combination of interaural magnification (IM), monaural microphone directionality (DIR), and binaural coherence-based noise reduction (BC).
DESIGN: Speech-in-noise stimuli were generated using virtual acoustics. A computational model of binaural hearing was used to analyse the spatial effects of IM. Predicted speech quality changes and signal-to-noise-ratio (SNR) improvements were also considered. Additionally, a listening test was carried out to assess speech intelligibility and quality.
STUDY SAMPLE: Listeners aged 65-79 years with and without sensorineural hearing loss (N = 10 each).
RESULTS: IM increased the horizontal separation of concurrent directional sound sources without introducing any major artefacts. In situations with diffuse noise, however, the interaural difference cues were distorted. Preprocessing the binaural input signals with DIR reduced distortion. IM influenced neither speech intelligibility nor speech quality.
CONCLUSIONS: The IM algorithm tested here failed to improve speech perception in noise, probably because of the dispersion and inconsistent magnification of interaural difference cues in complex environments.
PMID: 28395561 [PubMed - as supplied by publisher]
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Evaluation of a wireless remote microphone in bimodal cochlear implant recipients.
| Related Articles |
Evaluation of a wireless remote microphone in bimodal cochlear implant recipients.
Int J Audiol. 2017 Apr 10;:1-7
Authors: Vroegop JL, Dingemanse JG, Homans NC, Goedegebure A
Abstract
OBJECTIVE: To evaluate the benefit of a wireless remote microphone (MM) for speech recognition in noise in bimodal adult cochlear implant (CI) users both in a test setting and in daily life.
DESIGN: This prospective study measured speech reception thresholds in noise in a repeated measures design with factors including bimodal hearing and MM use. The participants also had a 3-week trial period at home with the MM.
STUDY SAMPLE: Thirteen post-lingually deafened adult bimodal CI users.
RESULTS: A significant improvement in SRT of 5.4 dB was found between the use of the CI with the MM and the use of the CI without the MM. By also pairing the MM to the hearing aid (HA) another improvement in SRT of 2.2 dB was found compared to the situation with the MM paired to the CI alone. In daily life, participants reported better speech perception for various challenging listening situations, when using the MM in the bimodal condition.
CONCLUSION: There is a clear advantage of bimodal listening (CI and HA) compared to CI alone when applying advanced wireless remote microphone techniques to improve speech understanding in adult bimodal CI users.
PMID: 28395552 [PubMed - as supplied by publisher]
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