老年人视听觉整合的脑神经机制及其干预研究

Population aging - a global social issue - is one of the principal challenges of the future, and it is related to social stability and development. Visual and auditory information are two important sources of human perception of the outside world. Stimuli from visual and auditory modalities can be integrated into a coherent representation through multiple phases of multisensory processing; this phenomenon is called audiovisual integration. The vision, hearing and other basic cognitive abilities gradually get weakened in older adults, but the audiovisual integration ability is still controversial for the older adults, and the brain mechanisms are not clear. In this project, utilizing behavioral and imaging (fMRI and ERP) technologies, we will apply the integration paradigm, and manipulate factors of intensity and complexity for stimulus information (simple flash beeps, dynamic handheld tools, and single syllable utterances) to investigate the time course and brain areas of audiovisual integration in older adults. We will explore the differences between young and older adults in order to verify the hypothesis of compensation mechanism. Based on brain mechanisms of audiovisual integration in older adults, the perceptual training including signal modality and cross-modal modalities are implemented to prove the plasticity of audiovisual integration in older adults in the aspects of brain nerve mechanism. The results of this project will contribute to propose scientific and effective intervention programs, which has practical application value to improve the ability of life for older adults.

人口老龄化是人类面临的一个重大社会问题，关系到社会稳定及其可持续发展。视觉和听觉信息是人类感知外部世界的两个重要来源，将视觉和听觉通道的信息有效地融合为统一、连贯的知觉过程，被称作视听觉整合。老年人的视力、听力等基本认知能力逐渐减弱，但有关视听觉整合能力仍有争议，其确切脑机制尚不清楚。本项目拟采用整合范式，操控刺激信息（简单Flash beep、手持工具和单音节言语）内容从静态到动态及刺激强度等变量，利用行为学、ERP和fMRI脑成像相结合的技术手段，旨在探明老年人视听觉整合的时程机制及精准脑结构，并探讨年轻人和老年人之间的差异从而验证老年人的补偿机制假说。在阐明老年人视听觉整合脑机制基础上，对老年人进行单通道视觉或听觉和跨通道视听觉的知觉训练，从脑神经机制方面证明老年人视听觉整合的可塑性，进而提出科学有效的干预方案，对提高老年人生活能力有实际的应用价值。

人口老龄化是人类面临的一个重大社会问题，关系到社会稳定及其可持续发展。视觉和听觉信息是人类感知外部世界的两个重要来源，将视觉和听觉通道的信息有效地融合为统一、连贯的知觉过程，被称作视听觉整合。老年人的视力、听力等基本认知能力逐渐减弱，但有关视听觉整合能力仍有争议，其确切脑机制尚不清楚。本项目采用整合范式，操控刺激信息（简单Flash beep、手持工具和单音节言语）内容从静态到动态及刺激强度等变量，考察老年人视听觉整合脑机制并探索其干预方案。研究结果发现：1）在静态简单刺激条件下，老年人和年轻人的视听觉整合在行为学上没有显著差异，但在信息加工的早期阶段，中央区老年人视听觉整合比年轻人大，而在信息加工的晚期阶段，额叶区年轻人的视听觉整合比老年人大。2）在动态手持工具刺激条件下，老年人的视听觉整合显著大于年轻人。在加工高强度和低强度视听刺激时，除了在高强度刺激条件下gamma频段外，老年人比年轻人具有更高的theta频段，而alpha、beta频段的功能连接显著小于年轻人。3）在动态语音刺激条件下，年轻人的额叶和中央区在相对早期整合阶段和老年人的中央区在相对晚期整合阶段低强度刺激比高强度刺激产生更大的视听整合效应，表明出现了逆效应。4）视听时空知觉训练可以改善老年人的认知能力，证明了老年人的大脑具有一定的可塑性。本项目研究结果不仅能为更深入地探究老年人多感觉通道整合能力奠定理论基础，还对延缓老龄化进程、提高老年人生活质量有重要的现实指导意义。