Neuroimaging of Age-Related Changes in Speech Recognition

与听力和语言识别相关的听力和语言识别能力下降是日益严重的公共卫生问题，对沟通能力产生深远影响。老年人将语音识别描述为疲劳，并且即使在考虑可听度之后，语音识别也会下降，这表明中枢神经系统（CNS）的下降会影响语音识别。项目2中提出的神经成像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力系统的影响。目的2.1使用新的结构成像来验证以下假设：大脑结构的独特模式与老年性聋的独特听力模式一起发生。这一目的旨在表征以下情况的程度：1）高频听力损失与源于感觉毛细胞损失的跨突触变性一起发生，而2）低频听力损失与血管疾病一起发生，假设血管疾病是代谢性老年性聋的基础。目标2.2涉及注意系统的功能成像和操作，以检验注意相关系统支持听力损失老年人语音识别的假设。这一目的旨在提供一个机械的解释，为什么单词识别可以更好或更差的听力损失的基础上参与特定的注意系统的预期。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相关皮层的附加结构下降的假设。这一目标旨在识别神经系统，这些神经系统在听觉阈值相对稳定的时间段内表现出跟踪语音识别下降的变化。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关注听觉周边年龄相关变化的延伸，并将提供体内证据支持项目3和4中研究的听力损失机制。我们的总体目标是描述1）老年人CNS下降对语音识别产生负面影响，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.