Stern Yaakov, Habeck Christian, Moeller James, Scarmeas Nikolaos, Anderson Karen E, Hilton H John, Flynn Joseph, Sackeim Harold, van Heertum Ronald
Cognitive Neuroscience Division, Taub Institute, College of Physicians and Surgeons, Columbia University, New York, USA.
Cereb Cortex. 2005 Apr;15(4):394-402. doi: 10.1093/cercor/bhh142.
In order to understand the brain networks that mediate cognitive reserve, we explored the relationship between subjects' network expression during the performance of a memory test and an index of cognitive reserve. Using H2(15)O positron emission tomography, we imaged 17 healthy older subjects and 20 young adults while they performed a serial recognition memory task for nonsense shapes under two conditions: low demand, with a unique shape presented in each study trial; and titrated demand, with a study list size adjusted so that each subject recognized shapes at 75% accuracy. A factor score that summarized years of education, and scores on the NART and the WAIS-R Vocabulary subtest was used as an index of cognitive reserve. The scaled subprofile model was used to identify a set of functionally connected regions (or topography) that changed in expression across the two task conditions and was differentially expressed by the young and elderly subjects. The regions most active in this topography consisted of right hippocampus, posterior insula, thalamus, and right and left operculum; we found concomitant deactivation in right lingual gyrus, inferior parietal lobe and association cortex, left posterior cingulate, and right and left calcarine cortex. Young subjects with higher cognitive reserve showed increased expression of the topography across the two task conditions. Because this topography, which is responsive to increased task demands, was differentially expressed as a function of reserve level, it may represent a neural manifestation of innate or acquired reserve. In contrast, older subjects with higher cognitive reserve showed decreased expression of the topography across tasks. This suggests some functional reorganization of the network used by the young subjects. Thus, for the old subjects this topography may represent an altered, compensatory network that is used to maintain function in the face of age-related physiological changes.
为了理解介导认知储备的脑网络，我们探究了受试者在执行记忆测试时的网络表达与认知储备指标之间的关系。我们使用H2(15)O正电子发射断层扫描技术，对17名健康的老年受试者和20名年轻成年人进行成像，他们在两种条件下对无意义形状执行序列识别记忆任务：低需求条件下，每个学习试验中呈现一个独特形状；滴定需求条件下，调整学习列表大小，使每个受试者以75%的准确率识别形状。一个综合教育年限、NART分数和WAIS-R词汇子测试分数的因子得分被用作认知储备指标。使用缩放子轮廓模型来识别一组在两种任务条件下表达发生变化且在年轻和老年受试者中差异表达的功能连接区域（或拓扑结构）。在这个拓扑结构中最活跃的区域包括右侧海马体、后岛叶、丘脑以及左右脑岛盖；我们发现右侧舌回、下顶叶和联合皮层、左侧后扣带回以及左右距状皮层伴随失活。认知储备较高的年轻受试者在两种任务条件下该拓扑结构的表达增加。因为这个对增加的任务需求有反应的拓扑结构根据储备水平差异表达，它可能代表先天或后天储备的神经表现。相比之下，认知储备较高的老年受试者在各任务中该拓扑结构的表达减少。这表明年轻受试者使用的网络存在一些功能重组。因此，对于老年受试者来说，这个拓扑结构可能代表一个改变的、代偿性网络，用于在面对与年龄相关的生理变化时维持功能。
