Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada; Centre de Recherche, Institut Universitaire de Gériatrie de Montréal, Montreal, Quebec, Canada.
Neurosci Res. 2013 Apr;75(4):295-304. doi: 10.1016/j.neures.2013.01.012. Epub 2013 Feb 27.
It has been proposed that cognitive reserve is supported by two neural mechanisms: neural compensation and neural reserve. The purpose of this study was to test how these neural mechanisms are solicited in aging in the context of visual selective attention processing and whether they are inter- or intra-hemispheric. Younger and older participants were scanned using fMRI during a visual letter-matching task with two attentional load levels. The results show that in the low-load condition, the older participants activated frontal superior gyri bilaterally; these regions were not activated in the younger participants, in accordance with the compensation mechanism and the Posterior-Anterior Shift in Aging (PASA) phenomenon. However, when task demand increased, the older participants recruited the same regions (parietal) as the younger ones, showing the involvement of a similar neural reserve mechanism. This result suggests that successful cognitive aging relies on the concurrent use of both neural compensation and neural reserve in high-demand tasks, calling on the frontoparietal network. In addition, the finding of intra-hemispheric-based neurofunctional reorganization with a PASA phenomenon for all attentional load levels suggests that the PASA phenomenon is a function more of compensation than of reserve.
有人提出，认知储备由两种神经机制支持：神经补偿和神经储备。本研究的目的是测试在视觉选择性注意处理的背景下，这些神经机制在衰老过程中是如何被激发的，以及它们是跨半球的还是半球内的。使用 fMRI 对年轻和年长的参与者进行扫描，让他们在视觉字母匹配任务中完成两个注意力负荷水平。结果表明，在低负荷条件下，年长的参与者双侧激活额上回；年轻的参与者则没有激活这些区域，这符合补偿机制和衰老中的后前转移（PASA）现象。然而，当任务需求增加时，年长的参与者像年轻的参与者一样招募了相同的区域（顶叶），这表明存在类似的神经储备机制。这一结果表明，成功的认知老化依赖于在高需求任务中同时使用神经补偿和神经储备，调用额顶网络。此外，对于所有注意力负荷水平，基于半球内的神经功能重组和 PASA 现象的发现表明，PASA 现象更多是补偿的功能，而不是储备的功能。
