Age-related Changes in Neural Coding of Envelope Cues: Peripheral Declines and Central Compensation

Parthasarathy, Aravindakshan; Bartlett, Edward E.; Kujawa, Sharon G.

doi:10.1016/j.neuroscience.2018.12.007

Cited by 61 publications

(48 citation statements)

References 172 publications

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“… Our analyses were restricted to ABRs wave I, III and V, and thus the present results do not exclude further gain compensation from occurring at sites central to the inferior colliculus (e.g. reviewed by Parthasarathy et al., 2019 ). The present analyses and findings were restricted to click-evoked ABRs.…”

Section: Discussionmentioning

confidence: 96%

Age-related central gain compensation for reduced auditory nerve output for people with normal audiograms, with and without tinnitus

Johannesen

Lopez‐Poveda

2021

iScience

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Central gain compensation for reduced auditory nerve output has been hypothesized as a mechanism for tinnitus with a normal audiogram. Here, we investigate if gain compensation occurs with aging. For 94 people (aged 12-68 years, 64 women, 7 tinnitus) with normal or close-to-normal audiograms, the amplitude of wave I of the auditory brainstem response decreased with increasing age but was not correlated with wave V amplitude after accounting for age-related subclinical hearing loss and cochlear damage, a result indicative of age-related gain compensation. The correlations between age and wave I/III or III/V amplitude ratios suggested that compensation occurs at the wave III generator site. For each one of the seven participants with non-pulsatile tinnitus, the amplitude of wave I, wave V, and the wave I/V amplitude ratio were well within the confidence limits of the non-tinnitus participants. We conclude that increased central gain occurs with aging and is not specific to tinnitus.

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Section: Discussionmentioning

confidence: 96%

Age-related central gain compensation for reduced auditory nerve output for people with normal audiograms, with and without tinnitus

Johannesen

Lopez‐Poveda

2021

iScience

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“…CS effects in CBA/CaJ mice are largest for MF ~ 1 kHz ( Shaheen et al., 2015 ), that reflect mostly auditory nerve activity, but some differences are apparent also at MFs ~ 100 Hz ( Parthasarathy and Kujawa, 2018 ), that reflect mostly brainstem activity. It has been hypothesized that smaller CS effects are seen at lower AM rates because of compensatory mechanisms increasing gain at brainstem and cortical levels ( Parthasarathy, Bartlett, Kujawa, 2019 , Parthasarathy, Kujawa, 2018 ); however, there is evidence that these compensatory mechanisms may themselves decline with age ( Möhrle et al., 2016 ). A recent study using transposed tones with a 4-kHz carrier failed to find age effects at higher modulation rates in the range of 240–285 Hz ( Prendergast et al., 2019 ), suggesting that targeting higher MFs may not better reveal potential CS effects.…”

Section: Discussionmentioning

confidence: 99%

Effects of age on electrophysiological measures of cochlear synaptopathy in humans

Carcagno

Plack

2020

Hearing Research

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Highlights We used highpass masking to record ABRs and FFRs from low-frequency regions. Wave I ABRs with highpass masking are not consistent with low-frequency synaptopathy. Wave I ABRs without highpass masking are consistent with high-frequency synaptopathy. Highpass-masked FFRs do not provide evidence of low-frequency synaptopathy.

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“…Because the attentional modulation of the brainstem response must involve the corticofugal pathways from the cortex to the brainstem, our finding may indicate that subjects who found it harder to understand speech in noise relied more on this neural feedback mechanism, perhaps to compensate for more central processing deficits. The increased attentional modulation of the brainstem response in subjects who exhibited poorer speech-in-noise comprehension might also have reflected compensation mechanisms at a subcortical level, such as in the inferior colliculus [59][60][61] .…”

Section: Discussionmentioning

confidence: 99%

Individual differences in the attentional modulation of the human auditory brainstem response to speech inform on speech-in-noise deficits

Saiz-Alía

Forte

Reichenbach

2019

Sci Rep

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People with normal hearing thresholds can nonetheless have difficulty with understanding speech in noisy backgrounds. The origins of such supra-threshold hearing deficits remain largely unclear. Previously we showed that the auditory brainstem response to running speech is modulated by selective attention, evidencing a subcortical mechanism that contributes to speech-in-noise comprehension. We observed, however, significant variation in the magnitude of the brainstem's attentional modulation between the different volunteers. Here we show that this variability relates to the ability of the subjects to understand speech in background noise. In particular, we assessed 43 young human volunteers with normal hearing thresholds for their speech-in-noise comprehension. We also recorded their auditory brainstem responses to running speech when selectively attending to one of two competing voices. To control for potential peripheral hearing deficits, and in particular for cochlear synaptopathy, we further assessed noise exposure, the temporal sensitivity threshold, the middle-ear muscle reflex, and the auditory-brainstem response to clicks in various levels of background noise. These tests did not show evidence for cochlear synaptopathy amongst the volunteers. Furthermore, we found that only the attentional modulation of the brainstem response to speech was significantly related to speech-in-noise comprehension. Our results therefore evidence an impact of topdown modulation of brainstem activity on the variability in speech-in-noise comprehension amongst the subjects.Understanding speech in noisy backgrounds such as other competing speakers is a challenging task at which humans excel 1,2 It requires the separation of different sound sources, selective attention to the target speaker, and the processing of degraded signals 3-5 Hearing impairment such as resulting from noise exposure often leads to an increase of hearing thresholds, a reduction in the information conveyed about a sound to the central auditory system, and thus to greater difficulty in understanding speech in noise 6-8 However, even listeners with normal hearing thresholds can have problems with understanding speech in noisy environments 9,10 .An extensive neural network of efferent fibers can feed information from the central auditory cortex back to the auditory brainstem and even to the cochlea 11,12 . Research on the role of these neural feedback loops for speech-in-noise listening has mostly focused on the medial olivocochlear reflex (MOCR), in which stimulation of the medial olivocochlear fibers that synapse on the outer hair cells in the cochlea reduces cochlear amplification across a wide frequency band 13 . Computational modelling as well as animal studies have shown that such reduced broad-band amplification can improve the signal-to-noise ratio of a transient signal embedded in background noise [14][15][16][17] . However, it remains debated whether the reduction of cochlear amplification through the MOCR contributes to better speech-in-noise comprehe...

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Age-related Changes in Neural Coding of Envelope Cues: Peripheral Declines and Central Compensation

Cited by 61 publications

References 172 publications

Age-related central gain compensation for reduced auditory nerve output for people with normal audiograms, with and without tinnitus

Age-related central gain compensation for reduced auditory nerve output for people with normal audiograms, with and without tinnitus

Effects of age on electrophysiological measures of cochlear synaptopathy in humans

Individual differences in the attentional modulation of the human auditory brainstem response to speech inform on speech-in-noise deficits

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