Abstract

Moment-to-moment fluctuations in brain signal assessed by functional magnetic resonance imaging blood oxygenation level dependent (BOLD) variability is increasingly thought to represent important “signal” rather than measurement-related “noise.” Efforts to characterize BOLD variability in healthy aging have yielded mixed outcomes, demonstrating both age-related increases and decreases in BOLD variability and both detrimental and beneficial associations. Utilizing BOLD mean-squared-successive-differences (MSSD) during a digit n-back working memory (WM) task in a sample of healthy adults (aged 20–94 years; n = 171), we examined effects of aging on whole-brain 1) BOLD variability during task (mean condition MSSD across 0–2–3-4 back conditions), 2) BOLD variability modulation to incrementally increasing WM difficulty (linear slope from 0–2–3-4 back), and 3) the association of age-related differences in variability with in- and out-of-scanner WM performance. Widespread cortical and subcortical regions evidenced increased mean variability with increasing age, with no regions evidencing age-related decrease in variability. Additionally, posterior cingulate/precuneus exhibited increased variability to WM difficulty. Notably, both age-related increases in BOLD variability were associated with significantly poorer WM performance in all but the oldest adults. These findings lend support to the growing corpus suggesting that brain-signal variability is altered in healthy aging; specifically, in this adult lifespan sample, BOLD-variability increased with age and was detrimental to cognitive performance.

中文翻译：

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更大的 BOLD 变异性与成人寿命样本中较差的认知功能相关。

摘要

通过功能性磁共振成像血氧水平依赖 (BOLD) 变异性评估的大脑信号的时刻波动越来越多地被认为代表重要的“信号”，而不是与测量相关的“噪音”。描述健康老龄化中 BOLD 变异性的努力产生了不同的结果，表明 BOLD 变异性与年龄相关的增加和减少以及有害和有益的关联。利用BOLD均方逐次差异（MSSD）一个数字时ň -back工作记忆（WM）任务，健康的成年人（年龄20-94岁样品中; ñ = 171），我们检查了衰老对全脑的影响 1）任务期间的 BOLD 变异性（平均条件 MSSD 跨越 0-2-3-4 背部条件），2）BOLD 变异性调制以逐渐增加 WM 难度（线性斜率从 0 –2–3-4 back）和 3）与年龄相关的变异性差异与扫描仪内外 WM 性能的关联。广泛的皮质和皮质下区域证明平均变异性随着年龄的增长而增加，没有区域证明与年龄相关的变异性降低。此外，后扣带回/楔前叶对 WM 难度的变异性增加。值得注意的是，与年龄相关的 BOLD 变异性增加都与除了最年长的成年人之外的所有人的 WM 表现显着较差有关。这些发现为不断增长的语料库提供了支持，表明大脑信号变异性在健康老龄化过程中发生了改变。具体来说，在这个成年寿命样本中，BOLD 变异性随着年龄的增长而增加，并且不利于认知表现。