Suzuki Maki, Kawagoe Toshikazu, Nishiguchi Shu, Abe Nobuhito, Otsuka Yuki, Nakai Ryusuke, Asano Kohei, Yamada Minoru, Yoshikawa Sakiko, Sekiyama Kaoru
Division of Cognitive Psychology, Faculty of Letters, Kumamoto University, Kumamoto, Japan.
Department of Behavioral Neurology and Neuropsychiatry, United Graduate School of Child Development, Osaka University, Suita, Japan.
Front Aging Neurosci. 2018 Nov 6;10:358. doi: 10.3389/fnagi.2018.00358. eCollection 2018.
Working memory (WM)-related brain activity is known to be modulated by aging; particularly, older adults demonstrate greater activity than young adults. However, it is still unclear whether the activity increase in older adults is also observed in advanced aging. The present functional magnetic resonance imaging (fMRI) study was designed to clarify the neural correlates of WM in advanced aging. Further, we set out to investigate in the case that adults of advanced age do show age-related increase in WM-related activity, what the functional significance of this over-recruitment might be. Two groups of older adults - "young-old" (61-70 years, = 17) and "old-old" (77-82 years, = 16) - were scanned while performing a visual WM task (the -back task: 0-back and 1-back). WM effects (1-back > 0-back) common to both age groups were identified in several regions, including the bilateral dorsolateral prefrontal cortex (DLPFC), the inferior parietal cortex, and the insula. Greater WM effects in the old-old than in the young-old group were identified in the right caudal DLPFC. These results were replicated when we performed a separate analysis between two age groups with the same level of WM performance (the young-old vs. a "high-performing" subset of the old-old group). There were no regions where WM effects were greater in the young-old group than in the old-old group. Importantly, the magnitude of the over-recruitment WM effects positively correlated with WM performance in the old-old group, but not in the young-old group. The present findings suggest that cortical over-recruitment occurs in advanced old age, and that increased activity may serve a compensatory function in mediating WM performance.
已知与工作记忆（WM）相关的大脑活动会受到衰老的调节；特别是，老年人比年轻人表现出更强的活动。然而，目前尚不清楚在高龄阶段是否也会观察到老年人的活动增加。本功能磁共振成像（fMRI）研究旨在阐明高龄阶段WM的神经关联。此外，我们着手研究在高龄成年人确实表现出与年龄相关的WM相关活动增加的情况下，这种过度激活的功能意义可能是什么。两组老年人——“年轻老年人”（61 - 70岁，n = 17）和“年老老年人”（77 - 82岁，n = 16）——在执行视觉WM任务（n - 回溯任务：0 - 回溯和1 - 回溯）时接受扫描。在包括双侧背外侧前额叶皮质（DLPFC）、顶下皮质和脑岛在内的几个区域中，发现了两个年龄组共有的WM效应（1 - 回溯 > 0 - 回溯）。在右侧尾状DLPFC中，年老老年人组的WM效应比年轻老年人组更大。当我们在具有相同WM表现水平的两个年龄组（年轻老年人组与年老老年人组的“高表现”子集）之间进行单独分析时，这些结果得到了重复。没有发现年轻老年人组的WM效应比年老老年人组更大的区域。重要的是，过度激活的WM效应的大小与年老老年人组的WM表现呈正相关，但与年轻老年人组无关。本研究结果表明，皮质过度激活发生在高龄阶段，并且增加的活动可能在介导WM表现中起到补偿作用。
