Neural mechanisms of speech learning in older adults

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DESCRIPTION (provided by applicant): Healthy older listeners show decline in cognitive and complex speech perception abilities. Complex speech perception in the real-world, including listening to highly variable speech sounds (phonemes) produced by multiple talkers and listening to speech in noise, has been shown to require cognitive resources. The overarching goal of the newly proposed research is to test the hypothesis that cognitive training preceding complex speech training will result in better real-world speech communication abilities in healthy older adults. This hypothesis is grounded in the decline-compensation model of the aging brain, which postulates that decline in sensory abilities (auditory cortex) can be compensated by increased engagement of general cognitive cortical regions such as the prefrontal cortex, which cognitive training is expected to provide. The PI's current R01 is examining speech learning in younger adults, with the hypothesis that efficacy of complex speech learning (multi-talker/high-variability sound-to-word learning) is mediated by cognitive brain regions (superior parietal lobule for auditory attention and prefrontal cortex for working memory). The purpose of this K02 award is to allow the PI to extend his current work in younger adults to the elderly population, including examinations of the neurophysiological underpinnings of the efficacy of prescribing cognitive training before multi-talker sound-to-word and speech in noise training. Per the decline-compensation model, we hypothesize that the engagement of cognitive brain regions post-training is critical to the success in complex speech learning. The two important issues concerning older adults addressed by this research is the trend for this population to seek cognitively stimulating post-retirement activities including effective second language learning programs and the need to overcome central auditory deficits (with speech perception in noise difficulty being the chief complaint) in order to participate fully in (noisy) everyday environments. This K02 award will also allow the PI to receive didactic and laboratory training in gerontology (including neuroimaging in older adults) and clinical research designs to prepare him for a life-long career as a clinician-translational researcher. PUBLIC HEALTH RELEVANCE: Many older adults experience difficulty understanding speech in real-world environments such as restaurants. Some elderly individuals reportedly avoid socializing (e.g., dining in restaurants) because it is difficult for them to communicate in such environments. While this difficulty can be related to their ears and to the fact that sounds are not loud enough for them to hear, reduced brain functions affecting memory and attention might also be playing a major role. Our research will seek to explore whether training focusing first on memory and attention prior to speech perception training of real-world environments could result in better overall spoken language communication in older adults; an additional goal is to examine the underlying brain responses to such possible improvements.