Functional deactivations: Change with age and dementia of the Alzheimer type
Functional deactivations: Change with age and dementia of the Alzheimer type
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DOI：
10.1073/pnas.2235925100
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发表时间：
2003-11-25
影响因子：
11.1
通讯作者：
Buckner, RL
中科院分区：
文献类型：
--
作者：
Lustig, C;Snyder, AZ;Buckner, RL
年轻成年人在执行主动任务时通常会使特定的大脑区域失活。失活区域与那些在衰老和痴呆中静息代谢活动降低的区域有重叠，这增加了两者存在关联的可能性。在此，通过对82名参与者进行功能性磁共振成像，研究了这些通常失活区域在衰老过程中的程度和动态时间特性。年轻成年人（n = 32）、无痴呆的老年人（n = 27）以及患有早期阿尔茨海默病型痴呆（DAT）的老年人（n = 23）在主动语义分类任务组块和被动注视基线之间交替时接受了成像。顶叶外侧区域的失活在各组之间是相同的；在额叶内侧区域，失活因衰老而减少，但不因DAT进一步减少。最令人感兴趣的是，内侧顶叶/后扣带区域在年轻成年人和无痴呆的老年人之间存在差异，与DAT患者的差异更为显著。内侧顶叶/后扣带反应的时间曲线表明，三组最初都有激活，但年轻成年人的反应很快反转，而DAT患者在整个任务组块中都保持激活。探索性全脑分析证实了内侧顶叶/后扣带皮层在衰老和DAT中的差异的重要性。这些结果为探索显示失活的区域的功能特性、它们的动态功能特性如何与其基线代谢率相关以及它们如何随年龄和痴呆而变化提供了重要契机。
Young adults typically deactivate specific brain regions during active task performance. Deactivated regions overlap with those that show reduced resting metabolic activity in aging and dementia, raising the possibility of a relation. Here, the magnitude and dynamic temporal properties of these typically deactivated regions were explored in aging by using functional MRI in 82 participants. Young adults (n = 32), older adults without dementia (n = 27), and older adults with early-stage dementia of the Alzheimer type (DAT) (n = 23) were imaged while alternating between blocks of an active semantic classification task and a passive fixation baseline. Deactivation in lateral parietal regions was equivalent across groups; in medial frontal regions, it was reduced by aging but was not reduced further by DAT. Of greatest interest, a medial parietal/posterior cingulate region showed differences between young adults and older adults without dementia and an even more marked difference with DAT. The temporal profile of the medial parietal/posterior cingulate response suggested that it was initially activated by all three groups, but the response in young adults quickly reversed sign, whereas DAT individuals maintained activation throughout the task block. Exploratory whole-brain analyses confirmed the importance of medial parietal/posterior cingulate cortex differences in aging and DAT. These results introduce important opportunities to explore the functional properties of regions showing deactivations, how their dynamic functional properties relate to their baseline metabolic rates, and how they change with age and dementia.