Afferent-efferent connectivity between auditory brainstem and cortex accounts for poorer speech-in-noise comprehension in older adults

ABSTRACT

Age-related hearing loss leads to poorer speech comprehension, particularly in noise. Speech-in-noise (SIN) deficits among the elderly could result from weaker neural activity within, or poorer signal transmission between brainstem and auditory cortices. By recording neuroelectric responses from brainstem (BS) and primary auditory cortex (PAC), we show that beyond simply attenuating neural activity, hearing loss in older adults compromises the transmission of speech information between subcortical and cortical hubs of the auditory system. The strength of afferent BS→PAC neural signaling (but not the reverse efferent flow; PAC→BS) varied with mild declines in hearing acuity and this “bottom-up” functional connectivity robustly predicted older adults’ SIN perception. Our neuroimaging findings underscore the importance of brain connectivity, particularly afferent neural communication, in understanding the biological basis of age-related hearing deficits in real-world listening environments.