Neuroimaging of Age-Related Changes in Speech Recognition

与年龄相关的听力和语言识别能力下降日益引起公众对健康的关注，对沟通能力产生了深远的影响。老年人将语音识别描述为疲劳，即使考虑到可听性，语音识别能力也会下降，这表明中枢神经系统（CNS）的衰退会影响语音识别。项目2中提出的神经影像学实验研究了老年性耳聋和衰老对支持语音识别的中央听觉和注意系统的影响。目的2.1使用新颖的结构成像来验证老年性耳聋的独特听觉模式会产生独特的大脑结构模式的假设。本目的目的是描述以下程度：1)高频听力损失发生在由感觉毛细胞丧失引起的突触变性，而2)低频听力损失发生在被假设为代谢性耳聋基础的血管疾病。目的2.2涉及注意系统的功能成像和操作，以验证注意相关系统支持听力损失老年人语音识别的假设。这个目标的目的是提供一个机制的解释，为什么单词识别可以比预期的听力损失更好或更差，基于特定的注意系统的参与。目的2.3涉及结构和功能成像，以验证纵向语音识别变化发生在听觉和注意力相关皮层的附加结构下降的假设。这一目标旨在识别在听觉阈值相对稳定的一段时间内，随着语音识别能力下降而出现变化的神经系统。因此，项目2描述了听觉阈值下降和年龄对语音识别的独特影响，是项目1关注听觉外围区年龄相关变化的延伸，并将为项目3和项目4研究的听力损失机制提供体内证据。我们的总体目标是描述：(1)老年人中枢神经系统衰退对语音识别的负面影响；(2)保留支持语音识别的结构和功能，从而指导改善老年人沟通和提高生活质量的努力。

Age-related declines in hearing and speech recognition are growing public health concerns that have a profound impact on the ability to communicate. Older adults describe speech recognition as fatiguing and experience speech recognition declines even after accounting for audibility, suggesting that central nervous system (CNS) declines affect speech recognition. The neuroimaging experiments proposed in Project 2 examine effects of presbyacusis and aging on central auditory and attention systems that support speech recognition. Aim 2.1 uses novel structural imaging to test the hypothesis that unique patterns of brain structure occur with unique audiometric patterns of presbyacusis. This aim is designed to characterize the extent to which 1) high frequency hearing loss occurs with trans-synaptic degeneration that stems from sensory hair cell loss, while 2) low frequency hearing loss occurs with vascular disease that is hypothesized to underlie metabolic presbyacusis. Aim 2.2 involves functional imaging and manipulations of attention systems to test the hypothesis that attention-related systems support speech recognition in older adults with hearing loss. This aim is designed to provide a mechanistic explanation for why word recognition can be better or worse than expected for hearing loss based on the engagement of specific attention systems. Aim 2.3 involves structural and functional imaging to test the hypothesis that longitudinal speech recognition changes occur with additive structural declines in auditory and attention-related cortex. This aim is designed to identify neural systems exhibiting changes that track with declines in speech recognition during a time period when auditory thresholds are relatively stable. Thus, Project 2 characterizes the unique impacts of declines in auditory thresholds and age on speech recognition, is an extension of Project 1's focus on age related changes in the auditory periphery, and will provide in vivo evidence to support mechanisms for hearing loss that are studied in Projects 3 and 4. Our overarching goal is to characterize 1) CNS declines in older adults that negatively affect speech recognition and 2) preserved structure and function that support speech recognition, thereby guiding efforts to improve communication and enhance the quality of life for older adults.