Neural mechanisms of speech learning in older adults

描述（由申请人提供）：健康的老年听者表现出认知和复杂言语感知能力的下降。在现实世界中，复杂的语音感知，包括听由多个说话者产生的高度变化的语音（音素）和听噪音中的语音，已被证明需要认知资源。这项新提出的研究的首要目标是验证一个假设，即在复杂的语言训练之前进行认知训练，会使健康的老年人在现实世界中有更好的语言交流能力。这一假说建立在大脑衰老的衰退补偿模型的基础上，该模型假设感觉能力（听觉皮层）的衰退可以通过增加一般认知皮质区域（如前额叶皮层）的参与来补偿，这是认知训练所期望提供的。PI目前的R01正在研究年轻人的语言学习，假设复杂语言学习（多语者/高变异性从音到词的学习）的效果是由大脑认知区域（负责听觉注意的顶叶上叶和负责工作记忆的前额叶皮层）调节的。这个K02奖的目的是允许PI将他目前在年轻人中的工作扩展到老年人，包括检查在多说话者的声音到单词和语音的噪音训练之前处方认知训练效果的神经生理学基础。根据衰退补偿模型，我们假设训练后大脑认知区域的参与对复杂语言学习的成功至关重要。本研究涉及的两个重要问题是老年人在退休后寻求认知刺激活动的趋势，包括有效的第二语言学习计划和克服中枢性听觉缺陷的需要（噪音困难的言语感知是主要的抱怨），以便充分参与（嘈杂的）日常环境。该K02奖还将允许PI接受老年学（包括老年人神经影像学）和临床研究设计的教学和实验室培训，为他作为临床-转化研究人员的终身职业做好准备。

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.