认知与发展心理学研究室知识库

随着全球人口老龄化的加剧，老龄化引发的认知功能下降问题日益突出，其中就包括了空间导航能力的损伤。导航作为一项与日常生活息息相关的高级认知功能，主要依赖于内侧颗叶的海马等脑区，这些脑区极易受到老化的影响出现萎缩或功能紊乱。因此对于导航老化的行为、神经机制测量将为健康老化提供思路。本研究拟从导航成绩及导航策略方面探索老年人的导航能力并结合磁共振成像技术探究脑结构的改变。

本研究共包含两个研究，包括导航能力老化的行为研究及脑结构改变的研究。研究一中，通过虚拟现实星型迷宫范式来测量老化过程中，导航成绩与导航策略的互相影响。我们招募了老年人和青年人各30名，这些被试均完成了虚拟现实星型迷宫导航实验。通过对比老化过程中老年人和青年人的导航能力，我们发现，相对青年人来说，老年人在策略选择能力上存在损伤，并且根据任务与环境需要改变策略的能力较差。策略选择的损伤会进一步影响老年人的导航成绩，特别是非自我中心导航成绩，且选择不合适策略的老年人在视空加工速度上显著更差。

研究二是行为结合磁共振研究，我们利用快速照片呈现任务来测量导航过程中老年人对场景的区分能力及其神经机制。研究纳入共计巧名老年人与巧名青年人，通过快速呈现照片的形式模拟被动导航过程。我们比较了青年人与老年人在区分场景上的差异，发现老年人区分场景的速度更慢，且正确率更差。结构磁共振成像结果表明老年人的海马显著小于青年人，且不同海马子区域存在不同程度的萎缩。其中，行为成绩与海马子区域中的齿状回体积存在显著相关。

老年人的策略选择会影响其导航成绩，而视空加工速度在其中可能存在重要作用，因此对于健康老化的干预可以针对导航成绩以及视空加工速度进行。此外，老年人对相似场景的区分能力的下降可能同样会影响其导航成绩，且这一能力与齿状回体积相关，这也许意味着能够通过相似刺激区分的训练改善或者减缓这一区域的体积萎缩，从而改善老年人的导航能力，进一步的预防老年人迷路现象。

With the aggravation of global population aging, the cognitive decline caused by aging has become increasingly prominent, including the impairment of space navigation ability. Navigation, as an advanced cognitive function closely related to daily life, mainly relies on medial temporal lobe, which are vulnerable to atrophy or dysfunction due to aging. Therefore, the measurement of behavior and neural mechanism of the aging in navigation will provide ideas for intervention. The purpose of this study is to explore the navigation ability of the elderly from the aspects of navigation performance and strategies. Furthermore, using magnetic resonance imaging to explore the changes of brain structure.

There are two studies in this study, including the behavioral study of aging navigation ability and the study of brain structure changes.

In the first study, we used the virtual reality star maze paradigm to measure the interaction between navigation performance and strategies during healthy aging. We recruited 30 older and 30 young adults. Compared with the young adults, older adults have impairment in strategy choosing according to the needs of tasks. The impairment of strategy selection will further hinder their navigation performance, especially the allocentric navigation performance. And the older adults who choose inappropriate strategies have significantly worse visual processing speed.

In the second study, the ability to distinguish different scenes was tested. And magnetic resonance imaging was used to measure the neurological mechanisms. A total of 15 elderly people and 15 young people were included in the study. The passive navigation process was simulated by rapid photo presentation. We compared the differences between the young and the old adults in the performance of scenes differentiation, and found that the older adults distinguished the scene more slowly and the accuracy was worse. Combined with structural magnetic resonance scanning, we found that the hippocampus of the elderly was significantly smaller than that of the young, and there were different degrees of atrophy in different subfields of hippocampus. Among them, we found a significant correlation between behavioral performance and the volumes of dentate gyrus.

According to the above two studies, we believe that the older adults have impairment in the use of navigation strategies, and the impairment of this ability will, in return, hamper the navigation performance of the older adults. In the older adults, the speed of visuospatial processing is related with the choice of navigation strategies. And during navigation, the ability to distinguish scenes of the older adults was significantly impaired, which was related to the atrophy of dentate gyrus in the hippocampal subfields.