Speech‐in‐noise understanding in older age: The role of inhibitory cortical responses. (3rd October 2019)

• Record Type: Journal Article
• Authors: Ross, Bernhard; Dobri, Simon; Schumann, Annette
• Is Part Of: European journal of neuroscience. Volume 51:Number 3(2020)
• Page Start: 891
• Page End: 908
• Publication Date: 2019-10-03
• Subjects: auditory evoked responses -- auditory perception -- Gamma‐band responses -- Magnetoencephalography -- sensory gating; Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.14573
• Languages: English
• ISSNs: 0953-816X

Abstract

Abstract: Studies of central auditory processing underlying speech‐in‐noise (SIN) recognition in aging have mainly concerned the degrading neural representation of speech sound in the auditory brainstem and cortex. Less attention has been paid to the aging‐related decline of inhibitory function, which reduces the ability to suppress distraction from irrelevant sensory input. In a response suppression paradigm, young and older adults listened to sequences of three short sounds during MEG recording. The amplitudes of the cortical P30 response and the 40‐Hz transient gamma response were compared with age, hearing loss and SIN performance. Sensory gating, indicated by the P30 amplitude ratio between the last and the first responses, was reduced in older compared to young listeners. Sensory gating was correlated with age in the older adults but not with hearing loss nor with SIN understanding. The transient gamma response expressed less response suppression. However, the gamma amplitude increased with age and SIN loss. Comparisons of linear multi‐variable modeling showed a stronger brain–behavior relationship between the gamma amplitude and SIN performance than between gamma and age or hearing loss. The findings support the hypothesis that aging‐related changes in the balance between inhibitory and excitatory neural mechanisms modify the generation of gamma oscillations, which impacts on perceptual binding and consequently on SIN understanding abilities. In conclusion, SIN recognition in older age is less affected by central auditory processing at the level of sensation, indicated by sensory gating, but is strongly affected at the level of perceptual organization, indicated by the correlation with the gamma responses. Abstract : Auditory cortex responses differentiate between levels of central processing affecting speech‐in‐noise (SIN) recognition in aging. Reduced suppression of the P30 wave indicated impaired sensory gating in older compared to young adults. In contrast to sensory gating, the 40‐Hz gamma amplitude was correlated with SIN loss. Auditory processing at the level of perceptual organization beyond sensory processing may contribute predominantly to SIN recognition deficits in older listeners.