Chadick James Z, Zanto Theodore P, Gazzaley Adam
Department of Neurology, Physiology and Psychiatry, Center for Integrative Neuroscience, University of California, San Francisco, California 94158, USA.
Nat Commun. 2014 Jun 30;5:4223. doi: 10.1038/ncomms5223.
Older adults experience deficits in working memory (WM) that are acutely exacerbated by the presence of distracting information. Human neurophysiological studies have revealed that these changes are accompanied by a diminished ability to suppress visual cortical activity associated with task-irrelevant information. Although this is often attributed to deficits in top-down control from a prefrontal cortical source, this has not yet been directly demonstrated. Here we evaluate the neural basis of distraction's negative impact on WM and the impairment in neural suppression in older adults by performing structural and functional MRIs while older participants engage in tasks that require remembering relevant visual stimuli in the context of overlapping irrelevant stimuli. Analysis supports both an age-related distraction effect and neural suppression deficit, and extends our understanding by revealing an alteration in functional connectivity between visual cortices and a region in the default network, the medial prefrontal cortex (mPFC). Moreover, within the older population, the magnitude of WM distractibility and neural suppression are both associated with individual differences in cortical volume and activity of the mPFC, as well as its associated white-matter tracts.
老年人在工作记忆（WM）方面存在缺陷，而干扰信息的出现会使这些缺陷急剧恶化。人类神经生理学研究表明，这些变化伴随着抑制与任务无关信息相关的视觉皮层活动能力的下降。尽管这通常归因于前额叶皮层自上而下控制的缺陷，但尚未得到直接证实。在这里，我们通过对老年参与者进行结构和功能磁共振成像，评估干扰对工作记忆的负面影响以及老年人神经抑制受损的神经基础，这些参与者在重叠的无关刺激背景下进行需要记住相关视觉刺激的任务。分析支持了与年龄相关的干扰效应和神经抑制缺陷，并通过揭示视觉皮层与默认网络中的一个区域——内侧前额叶皮层（mPFC）之间功能连接的改变，扩展了我们的理解。此外，在老年人群中，工作记忆的易分心程度和神经抑制程度都与内侧前额叶皮层的皮质体积和活动以及其相关白质束的个体差异有关。
