Stimulus-specific adaptation in the anesthetized mouse revealed by brainstem auditory evoked potentials

Publication date: Available online 31 August 2018

Source: Hearing Research

Author(s): Daniel Duque, Rui Pais, Manuel S. Malmierca

Abstract

Neural responses to sensory inputs in a complex and natural environment must be weighted according to their relevance. To do so, the brain needs to be able to deal with sudden stimulus fluctuations in an ever-changing acoustic environment. Stimulus-specific adaptation (SSA) is a phenomenon of some neurons along the auditory pathway that show a reduced response to repetitive sounds while responsive to those that occur rarely. SSA has been shown from the inferior colliculus to auditory cortex, but has not been detected in the cochlear nucleus. To discover where SSA is first generated along the auditory pathway, auditory brainstem responses (ABRs) to pure tones were evaluated in anesthetized mice using an oddball paradigm. Using a typical narrow band-pass filter, changes in the ABRs suggest unspecific short-term adaptation may occur as early as the auditory nerve fibers. Furthermore, after applying a wide band-pass filter –allowing the visualization of a late slow wave in the ABR– we found a reduction of the amplitude of the response to repetitive sounds, compared to rare ones, in the slow wave component P₀ that follow the fast wave V. Previous studies have shown the P₀ shows temporal correlation with the sustained responses of inferior colliculus, thus we suggest that this nucleus is the first to show stimulus specific adaptation in the auditory pathway.

Graphical abstract

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Stimulus-specific adaptation in the anesthetized mouse revealed by brainstem auditory evoked potentials

Publication date: Available online 31 August 2018

Source: Hearing Research

Author(s): Daniel Duque, Rui Pais, Manuel S. Malmierca

Abstract

Neural responses to sensory inputs in a complex and natural environment must be weighted according to their relevance. To do so, the brain needs to be able to deal with sudden stimulus fluctuations in an ever-changing acoustic environment. Stimulus-specific adaptation (SSA) is a phenomenon of some neurons along the auditory pathway that show a reduced response to repetitive sounds while responsive to those that occur rarely. SSA has been shown from the inferior colliculus to auditory cortex, but has not been detected in the cochlear nucleus. To discover where SSA is first generated along the auditory pathway, auditory brainstem responses (ABRs) to pure tones were evaluated in anesthetized mice using an oddball paradigm. Using a typical narrow band-pass filter, changes in the ABRs suggest unspecific short-term adaptation may occur as early as the auditory nerve fibers. Furthermore, after applying a wide band-pass filter –allowing the visualization of a late slow wave in the ABR– we found a reduction of the amplitude of the response to repetitive sounds, compared to rare ones, in the slow wave component P₀ that follow the fast wave V. Previous studies have shown the P₀ shows temporal correlation with the sustained responses of inferior colliculus, thus we suggest that this nucleus is the first to show stimulus specific adaptation in the auditory pathway.

Graphical abstract

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Residual Cochlear Function in Adults and Children Receiving Cochlear Implants: Correlations With Speech Perception Outcomes

Objectives: Variability in speech perception outcomes with cochlear implants remains largely unexplained. Recently, electrocochleography, or measurements of cochlear potentials in response to sound, has been used to assess residual cochlear function at the time of implantation. Our objective was to characterize the potentials recorded preimplantation in subjects of all ages, and evaluate the relationship between the responses, including a subjective estimate of neural activity, and speech perception outcomes. Design: Electrocochleography was recorded in a prospective cohort of 284 candidates for cochlear implant at University of North Carolina (10 months to 88 years of ages). Measurement of residual cochlear function called the “total response” (TR), which is the sum of magnitudes of spectral components in response to tones of different stimulus frequencies, was obtained for each subject. The TR was then related to results on age-appropriate monosyllabic word score tests presented in quiet. In addition to the TR, the electrocochleography results were also assessed for neural activity in the forms of the compound action potential and auditory nerve neurophonic. Results: The TR magnitude ranged from a barely detectable response of about 0.02 µV to more than 100 µV. In adults (18 to 79 years old), the TR accounted for 46% of variability in speech perception outcome by linear regression (r2 = 0.46; p

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Residual Cochlear Function in Adults and Children Receiving Cochlear Implants: Correlations With Speech Perception Outcomes

Objectives: Variability in speech perception outcomes with cochlear implants remains largely unexplained. Recently, electrocochleography, or measurements of cochlear potentials in response to sound, has been used to assess residual cochlear function at the time of implantation. Our objective was to characterize the potentials recorded preimplantation in subjects of all ages, and evaluate the relationship between the responses, including a subjective estimate of neural activity, and speech perception outcomes. Design: Electrocochleography was recorded in a prospective cohort of 284 candidates for cochlear implant at University of North Carolina (10 months to 88 years of ages). Measurement of residual cochlear function called the “total response” (TR), which is the sum of magnitudes of spectral components in response to tones of different stimulus frequencies, was obtained for each subject. The TR was then related to results on age-appropriate monosyllabic word score tests presented in quiet. In addition to the TR, the electrocochleography results were also assessed for neural activity in the forms of the compound action potential and auditory nerve neurophonic. Results: The TR magnitude ranged from a barely detectable response of about 0.02 µV to more than 100 µV. In adults (18 to 79 years old), the TR accounted for 46% of variability in speech perception outcome by linear regression (r2 = 0.46; p

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The World’s First ‘Healthable’ Hearing Aid

​Starkey (https://www.starkey.com/) has introduced Livio AI, a "Healthable" hearing aid that not only tracks physical activity and cognitive health of the user but also features the company's latest sound technology. The 3D motion sensors inside Livio AI allow the hearing aids to detect movement, track activities, and recognize gestures. The hearing aids then communicate with each other and mobile accessories to deliver real-time feedback about the user's overall body and cognitive health and fitness in scores through the companion Thrive Hearing app. Livio AI also comes with the new Hearing Reality technology, which provides an average 50 percent reduction in noisy environments, significant reduced listening effort, and newly enhanced clarity of speech, while the use of artificial intelligence and integrated sensors enabled it to optimize the hearing experience. Livio AI is available as a RIC 312 and BTE 13 and is the first hearing aid to feature Amazon Alexa connectivity. Livio AI is currently available in the United States and Canada, with a global rollout to more than 20 countries in 2019.​

Published: 8/31/2018 8:09:00 AM

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The World’s First ‘Healthable’ Hearing Aid

​Starkey (https://www.starkey.com/) has introduced Livio AI, a "Healthable" hearing aid that not only tracks physical activity and cognitive health of the user but also features the company's latest sound technology. The 3D motion sensors inside Livio AI allow the hearing aids to detect movement, track activities, and recognize gestures. The hearing aids then communicate with each other and mobile accessories to deliver real-time feedback about the user's overall body and cognitive health and fitness in scores through the companion Thrive Hearing app. Livio AI also comes with the new Hearing Reality technology, which provides an average 50 percent reduction in noisy environments, significant reduced listening effort, and newly enhanced clarity of speech, while the use of artificial intelligence and integrated sensors enabled it to optimize the hearing experience. Livio AI is available as a RIC 312 and BTE 13 and is the first hearing aid to feature Amazon Alexa connectivity. Livio AI is currently available in the United States and Canada, with a global rollout to more than 20 countries in 2019.​

Published: 8/31/2018 8:09:00 AM

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How Do Age and Hearing Loss Impact Spectral Envelope Perception?

Purpose

The goal was to evaluate the potential effects of increasing hearing loss and advancing age on spectral envelope perception.

Method

Spectral modulation detection was measured as a function of spectral modulation frequency from 0.5 to 8.0 cycles/octave. The spectral modulation task involved discrimination of a noise carrier (3 octaves wide from 400 to 3200 Hz) with a flat spectral envelope from a noise having a sinusoidal spectral envelope across a logarithmic audio frequency scale. Spectral modulation transfer functions (SMTFs; modulation threshold vs. modulation frequency) were computed and compared 4 listener groups: young normal hearing, older normal hearing, older with mild hearing loss, and older with moderate hearing loss. Estimates of the internal spectral contrast were obtained by computing excitation patterns.

Results

SMTFs for young listeners with normal hearing were bandpass with a minimum modulation detection threshold at 2 cycles/octave, and older listeners with normal hearing were remarkably similar to those of the young listeners. SMTFs for older listeners with mild and moderate hearing loss had a low-pass rather than a bandpass shape. Excitation patterns revealed that limited spectral resolution dictated modulation detection thresholds at high but not low spectral modulation frequencies. Even when factoring out (presumed) differences in frequency resolution among groups, the spectral envelope perception was worse for the group with moderate hearing loss than the other 3 groups.

Conclusions

The spectral envelope perception as measured by spectral modulation detection thresholds is compromised by hearing loss at higher spectral modulation frequencies, consistent with predictions of reduced spectral resolution known to accompany sensorineural hearing loss. Spectral envelope perception is not negatively impacted by advancing age at any spectral modulation frequency between 0.5 and 8.0 cycles/octave.

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