Age-Related Compensation Mechanism Revealed in the Cortical Representation of Degraded Speech

Anderson, Samira; Roque, Lindsey; Gaskins, Casey R.; Gordon‐Salant, Sandra; Goupell, Matthew J.

doi:10.1007/s10162-020-00753-4

Cited by 19 publications

(10 citation statements)

References 48 publications

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“…However, this finding also opens up intriguing possibilities that cannot currently be ruled out. For instance, long-term exposure may elicit mechanisms either enhancing the sound-in-noise detection or compensating for the degraded neural representation of sounds, as during aging (Parthasarathy et al 2019;Anderson et al 2020) or hearing loss (Fuglsang et al 2020). The auditory cortex recordings made in this study do not support the hypothesis of improvements in the use of circuits dedicated to modulation depth coding (Ding et al 2014;Slama and Delgutte 2015;Fuglsang et al 2020).…”

Section: Discussioncontrasting

confidence: 63%

Temporal Alterations to Central Auditory Processing without Synaptopathy after Lifetime Exposure to Environmental Noise

et al. 2021

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People are increasingly exposed to environmental noise through the cumulation of occupational and recreational activities, which is considered harmless to the auditory system, if the sound intensity remains <80 dB. However, recent evidence of noise-induced peripheral synaptic damage and central reorganizations in the auditory cortex, despite normal audiometry results, has cast doubt on the innocuousness of lifetime exposure to environmental noise. We addressed this issue by exposing adult rats to realistic and nontraumatic environmental noise, within the daily permissible noise exposure limit for humans (80 dB sound pressure level, 8 h/day) for between 3 and 18 months. We found that temporary hearing loss could be detected after 6 months of daily exposure, without leading to permanent hearing loss or to missing synaptic ribbons in cochlear hair cells. The degraded temporal representation of sounds in the auditory cortex after 18 months of exposure was very different from the effects observed after only 3 months of exposure, suggesting that modifications to the neural code continue throughout a lifetime of exposure to noise.

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Section: Discussioncontrasting

confidence: 63%

Temporal Alterations to Central Auditory Processing without Synaptopathy after Lifetime Exposure to Environmental Noise

et al. 2021

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“…Ageing affects domains such as episodic memory, working memory, and attention [ 77 , 101 , 104 , 105 ]. There is evidence to suggest that older listeners rely more heavily on “top-down” cognitive mechanisms than younger listeners, compensating for the reduced fidelity of “bottom-up” auditory signal analysis [ 100 , 106 , 107 , 108 , 109 ].…”

Section: Factors Affecting Processing Of Degraded Speech In the Hementioning

confidence: 99%

Processing of Degraded Speech in Brain Disorders

et al. 2021

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The speech we hear every day is typically “degraded” by competing sounds and the idiosyncratic vocal characteristics of individual speakers. While the comprehension of “degraded” speech is normally automatic, it depends on dynamic and adaptive processing across distributed neural networks. This presents the brain with an immense computational challenge, making degraded speech processing vulnerable to a range of brain disorders. Therefore, it is likely to be a sensitive marker of neural circuit dysfunction and an index of retained neural plasticity. Considering experimental methods for studying degraded speech and factors that affect its processing in healthy individuals, we review the evidence for altered degraded speech processing in major neurodegenerative diseases, traumatic brain injury and stroke. We develop a predictive coding framework for understanding deficits of degraded speech processing in these disorders, focussing on the “language-led dementias”—the primary progressive aphasias. We conclude by considering prospects for using degraded speech as a probe of language network pathophysiology, a diagnostic tool and a target for therapeutic intervention.

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“…2016; Anderson et al . 2020). For young adults in cluttered acoustic environments and older individuals affected by age‐related hearing loss (presbycusis), higher‐order/cortical resources are brought into play to help disambiguate acoustic signals (Shinn‐Cunningham & Wang, 2008; Davis et al .…”

Section: Introductionmentioning

confidence: 99%

Corticothalamic projections deliver enhanced responses to medial geniculate body as a function of the temporal reliability of the stimulus

Kommajosyula

Bartlett

Cai

et al. 2021

The Journal of Physiology

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Ageing and challenging signal‐in‐noise conditions are known to engage the use of cortical resources to help maintain speech understanding. Extensive corticothalamic projections are thought to provide attentional, mnemonic and cognitive‐related inputs in support of sensory inferior colliculus (IC) inputs to the medial geniculate body (MGB). Here we show that a decrease in modulation depth, a temporally less distinct periodic acoustic signal, leads to a jittered ascending temporal code, changing MGB unit responses from adapting responses to responses showing repetition enhancement, posited to aid identification of important communication and environmental sounds. Young‐adult male Fischer Brown Norway rats, injected with the inhibitory opsin archaerhodopsin T (ArchT) into the primary auditory cortex (A1), were subsequently studied using optetrodes to record single‐units in MGB. Decreasing the modulation depth of acoustic stimuli significantly increased repetition enhancement. Repetition enhancement was blocked by optical inactivation of corticothalamic terminals in MGB. These data support a role for corticothalamic projections in repetition enhancement, implying that predictive anticipation could be used to improve neural representation of weakly modulated sounds. Key points In response to a less temporally distinct repeating sound with low modulation depth, medial geniculate body (MGB) single units show a switch from adaptation towards repetition enhancement. Repetition enhancement was reversed by blockade of MGB inputs from the auditory cortex. Collectively, these data argue that diminished acoustic temporal cues such as weak modulation engage cortical processes to enhance coding of those cues in auditory thalamus.

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Age-Related Compensation Mechanism Revealed in the Cortical Representation of Degraded Speech

Cited by 19 publications

References 48 publications

Temporal Alterations to Central Auditory Processing without Synaptopathy after Lifetime Exposure to Environmental Noise

Temporal Alterations to Central Auditory Processing without Synaptopathy after Lifetime Exposure to Environmental Noise

Processing of Degraded Speech in Brain Disorders

Corticothalamic projections deliver enhanced responses to medial geniculate body as a function of the temporal reliability of the stimulus

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