Centre for Cognitive and Neural Systems, University of Edinburgh, Edinburgh, United Kingdom.
Hippocampus. 2012 Aug;22(8):1770-80. doi: 10.1002/hipo.22011. Epub 2012 Mar 19.
Navigation abilities show marked decline in both normal ageing and dementia. Path integration may be particularly affected, as it is supported by the hippocampus and entorhinal cortex, both of which show severe degeneration with ageing. Age differences in path integration based on kinaesthetic and vestibular cues have been clearly demonstrated, but very little research has focused on visual path integration, based only on optic flow. Path integration is complemented by landmark navigation, which may also show age differences, but has not been well studied either. Here we present a study using several simple virtual navigation tasks to explore age differences in path integration both with and without landmark information. We report that, within a virtual environment that provided only optic flow information, older participants exhibited deficits in path integration in terms of distance reproduction, rotation reproduction, and triangle completion. We also report age differences in triangle completion within an environment that provided landmark information. In all tasks, we observed a more restricted range of responses in the older participants, which we discuss in terms of a leaky integrator model, as older participants showed greater leak than younger participants. Our findings begin to explain the mechanisms underlying age differences in path integration, and thus contribute to an understanding of the substantial decline in navigation abilities observed in ageing.
导航能力在正常衰老和痴呆症中都有明显下降。路径整合可能特别受到影响，因为它由海马体和内嗅皮层支持，这两个结构在衰老过程中都有严重退化。基于动觉和前庭线索的路径整合的年龄差异已得到明确证明，但基于光流的视觉路径整合的研究很少。路径整合由地标导航补充，地标导航也可能存在年龄差异，但也没有得到很好的研究。在这里，我们使用几个简单的虚拟导航任务来探索有和没有地标信息的情况下路径整合的年龄差异。我们报告说，在仅提供光流信息的虚拟环境中，年长的参与者在距离再现、旋转再现和三角形完成方面表现出路径整合的缺陷。我们还报告了在提供地标信息的环境中三角形完成的年龄差异。在所有任务中，我们观察到年长参与者的反应范围更窄，我们根据泄漏积分器模型讨论了这一点，因为年长参与者的泄漏比年轻参与者更大。我们的发现开始解释路径整合中年龄差异的机制，从而有助于理解衰老过程中导航能力的显著下降。
