中枢性老年耳聋的言语障碍认知神经机制研究

Central presbycusis is a central auditory processing disorder that is common in aging adults. It typically manifests itself as deficits of speech perception in noise. To date, neural mechanism underlying speech disorders caused by central presbycusis remains unclear, leading to the difficulty in the effective treatment of these disorders. There is evidence to suggest that speech perception in noise is related to cognitive functions such as auditory attention and working memory, and interactions between speech perception and speech motor control have been demonstrated. Accordingly, we propose a hypothesis that cognitive function may play an important role in the processing of speech perception in noise, and auditory cognitive training may result in an improvement of speech perception in noise, which in turn leads to a better control of vocal motor behavior. The primary purpose of the present project is to address the neural mechanisms underlying speech perception in noise and speech motor control in central presbycusis. In order to achieve this goal, we develop the method of hearing in noise test and the protocol of auditory cognitive training based on auditory attention and working memory. Psychoacoustic and neurophysiological techniques that incorporate the altered auditory feedback are used to investigate the role of cognitive function in speech perception in noise and auditory-vocal integration. Finally, we plan to address the neurocognitive mechanisms underlying speech perception and production in central presbycusis, determine how auditory cognitive training facilitate the cortical processing of speech through the functional connectivity between cognitive and auditory system, and reveal the integration of cognitive system with auditory and motor system in vocal production.This work will lay a foundation for the development of new techniques according to the decline-compensation theory in sensory processing to treat speech disorders caused by central presbycusis.

中枢性老年耳聋（central presbycusis）是老年人常见的一种中枢性听觉处理障碍，主要表现为噪声环境下无法正确地感知言语信息。目前中枢性老年耳聋的言语障碍机制尚不明了，致使临床上缺乏有效的康复方法。研究表明噪声环境下的言语感知与听觉注意和工作记忆等认知功能有关，并且言语感知和言语运动系统存在交互性作用。据此，我们提出噪声环境下的言语感知与认知功能相关，并且听觉认知训练能够改善中枢性老年耳聋的言语感知障碍，进而提高言语运动控制水平。本项目拟利用噪声环境下的言语感知测试方法与基于听觉注意和工作记忆的听觉认知训练方法，结合基于听觉反馈扰动的心理声学与神经生理学方法，研究中枢性老年耳聋言语障碍的认知神经机制，揭示听觉认知训练改善言语感知障碍的神经可塑性，阐释认知处理-听觉感知-运动控制在言语产生中的整合机制，为利用认知-感觉系统的平衡补偿机制治疗中枢性老年耳聋言语障碍提供科学依据。

本项目以正常年轻人和老年人与帕金森病、颞叶癫痫患者为对象，利用基于听觉反馈扰动的心理声学方法和事件相关电位，结合静息态磁共振成像技术，通过基于逆序数字广度和频率模式重建的工作记忆训练、声调感知的言语感知学习等多种研究范式，围绕“中枢听觉处理影响听觉-发声整合及其障碍的认知神经机制”进行了系统地研究，取得了一系列原创性的研究成果。1）听觉工作记忆训练和言语感知学习能够显著言语感知能力，并且产生迁移效应进而提高听觉反馈与发声运动的整合效率；2）选择性和分散性注意力能够影响言语运动调控的神经编码和行为表达，并且工作记忆能够提高言语运动中听觉偏差感知的处理效率和抑制声学行为的过度补偿，提出和证实了言语运动调控存在自上而下的认知处理过程；3）帕金森病的听觉反馈过度依赖行为与其听觉和运动皮层的过度活跃有关，并且可以通过外在听觉提示信息的介入而得到有效的抑制；颞叶癫痫的听觉反馈功能障碍与脑功能网络连接异常和皮层活动受到抑制有关；不同的神经系统疾病处理言语听觉反馈信息的神经活动模式存在差异，说明言语运动调控障碍的发病机制存在疾病特异性；4）大脑皮层的功能连接、皮层下结构的形态以及性激素水平的周期性变化与言语运动调控的行为活动和皮层活动均存在显著关联，为理解言语运动调控个体差异的神经生物学基础提供了重要依据。本项目执行期间，课题组在J. Neurosci.、NeuroImage、Hum. Brain Mapp.、Neurobiol. Aging等国际权威/一流期刊上发表高水平SCI论文15篇，其中IF-5>5的论文5篇，并培养6名博士和2名硕士。综上所述，本项目的各项研究内容顺利完成，实现了预期的研究目标。本项目揭示了听觉感知-发声运动整合及其障碍的认知神经机制，多个角度阐释了言语运动调控个体差异的神经生物学基础，为从认知训练的角度实现中枢性老年耳聋患者的言语感知与运动障碍康复奠定了理论基础。