Rotman Research Institute at Baycrest Health Sciences, Toronto, Ontario, Canada.
Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada.
Neurobiol Aging. 2022 Apr;112:215-230. doi: 10.1016/j.neurobiolaging.2022.01.010. Epub 2022 Feb 5.
BOLD variability, which measures moment-to-moment fluctuations in brain signal, is sensitive to age differences in cognitive performance. However, the effect of aging on BOLD variability in the context of different cognitive demands is still unclear. The current study examined how aging affects brain variability across cognitive loads and the contribution of BOLD variability to working memory abilities. Participants (N = 149, ages 20‒86) completed an fMRI n-back paradigm with 3 loads and 10-minute resting state scan. We found that BOLD variability was greater during rest compared to task and decreased even further as n-back load increased. Older age was associated with smaller load-related modulations of BOLD variability in default mode and fronto-parietal control networks. Increased variability in default mode, fronto-parietal control, and limbic regions and decreased variability in sensori-motor regions during the n-back task was associated with better working memory performance, regardless of age. Our findings suggest that working memory reductions in older ages are related to failure of core cognitive control and default mode regions to modulate dynamic range of activity in the face of increased demands.
大脑信号的瞬间波动可以通过大脑活动的低频振幅（BOLD）变异性来衡量，其与认知表现的年龄差异有关。然而，在不同认知需求的背景下，年龄对 BOLD 变异性的影响仍不清楚。本研究旨在探讨衰老如何影响跨认知负荷的大脑变异性，以及 BOLD 变异性对工作记忆能力的贡献。参与者（N=149，年龄 20-86 岁）完成了 fMRI n-back 范式，包括 3 个负荷和 10 分钟的静息状态扫描。结果发现，与任务相比，静息状态下的 BOLD 变异性更大，随着 n-back 负荷的增加，BOLD 变异性进一步减小。与年轻参与者相比，老年参与者在默认模式和额顶叶控制网络中，与任务相关的 BOLD 变异性的调节幅度较小。在 n-back 任务中，默认模式、额顶叶控制和边缘区域的变异性增加，感觉运动区域的变异性减小，与工作记忆表现更好相关，与年龄无关。这些发现表明，老年工作记忆的下降与核心认知控制和默认模式区域无法在需求增加的情况下调节活动的动态范围有关。
