The neural substrate of expressive language functions in healthy and pathological aging

在全球平均寿命不断延长的背景下，研究与年龄相关的认知能力下降的潜在原因具有重要意义。先前使用功能成像技术的研究已经将老年人在几个认知领域的行为变化与主要在额脑区域的任务相关皮层活动的不对称性减少联系起来。尽管如此，人们对与年龄相关的单词检索困难的神经基础知之甚少，尽管这些困难(a)在老年人中经常观察到，(b)在病理性衰老（即痴呆）的最早迹象中。到目前为止，只有一项研究在命名任务中使用了功能性磁共振成像（fMRI），并证明了老年人的左额叶偏侧减少，这与行为表现受损有关。本项目的重点将是进一步阐明健康老年人和轻度认知障碍患者的单词发现障碍的神经伴随因素。这将通过功能磁共振成像在几个显性语言任务中完成，这些任务特别操纵额叶执行语言功能的需求。在这里，显性设计将允许将与年龄相关的大脑活动变化与行为表现联系起来。此外，我们将探讨是否可以通过旨在加强左额叶脑活动的训练来调节老年人潜在的有害的偏侧活动模式，以及这是否会导致语言功能的改善。

In the context of the increasing average lifespan worldwide, research on the underlying causes of age-related cognitive decline is of the utmost significance. Previous research using functional imaging techniques has linked behavioral changes in old age in several cognitive domains to reduced asymmetry of task-related cortical activity mainly in frontal brain areas. Still, little is known about the neural substrate of age-related word-retrieval difficulties even though these are (a) frequently observed in old-age and (b) among the earliest signs of pathological aging (i.e., dementia). Only one study so far used functional magnetic resonance imaging (fMRI) during a naming task and demonstrated reduced left-frontal lateralization in older adults, which was associated with impaired behavioral performance. The focus of the present project will be to further elucidate the neural concomitants of impaired word-finding in healthy older adults and in patients with Mild Cognitive Impairment. This will be accomplished by means of fMRI during several overt language tasks that specifically manipulate demands on frontal executive language functions. Here, the overt design will allow to relate age-related changes brain activity to behavioral performance. Moreover, we will explore whether the potentially detrimental lesslateralized activity pattern in old-age can be modulated by a training that is designed to strengthen left-frontal brain activity and wether this leads to an improvement of language function.