老年人视听觉整合的影响因素及其神经机制

老年人的视听觉整合能力强于还是弱于年轻人, 目前尚存在很大争议。对老年人视听觉整合脑机制的研究, 将为老年人脑保健提供一种科学的跨通道整合方案。基于已有研究成果从两方面进行论述：1)影响老年人视听觉整合的因素, 包括刺激的物理属性、刺激呈现的时空关系以及刺激得到的注意资源。2)老年人视听觉整合效应。研究表明, 一方面, 老年人表现出更高的功能连接性、网络效率和较强的视听觉整合效应, 如：老年人在后顶叶、内侧前额叶和左前额叶等脑区有较强的激活, 额中央区的P2振幅表现出超加性; 老年人比年轻人的视听觉整合发生较早并有较长的延伸。另一方面, 老年人有较长的反应时和较弱的整合促进, 以及对视听觉刺激进行反应时颞上回脑区的振幅弱于年轻人。简单刺激诱发的老年人视听觉整合为进一步揭示整合机制提供了可靠的基础, 但是对于复杂情景下的视听觉信息整合加工机制仍待探究。

The influential factors and neural mechanisms of audiovisual integration in older adults

There is still much debate over whether older adults have enhanced or attenuated audiovisual integration. Research on the neural mechanism of audiovisual integration in older adults is needed to provide a scientific brain-health programme based on crossmodal integration. Here, we summarized two parts based on previous studies. First, audiovisual integration ability in older adults is influenced by the characteristics of the physical stimuli, the spatial and temporal relationships of the stimuli, and the attentional allocation. Second, audiovisual integration effects are observed in older adults. On the one hand, older adults showed higher functional connectivity, network efficiency and enhanced audiovisual integration effects, such as stronger activity in the posterior parietal lobe, medial prefrontal lobe, left prefrontal lobe, and the super-additive amplitude of P2 observed in the central prefrontal region. In addition, audiovisual integration in older adults occurred earlier and extended longer than that in younger adults. On the other hand, older adults have slower response times and smaller amplitudes to audiovisual stimuli in the superior temporal gyrus than younger adults, which shows a weaker integration facilitation effect in older adults. The study of audiovisual integration in older adults induced by simple stimuli provides a reliable basis for further revealing the integration mechanism, but the processing mechanism of audiovisual integration for complex situations remains to be explored.