As we age, the added benefit of sleep for memory consolidation is lost. One of the hallmark age-related changes in sleep is the reduction of sleep spindles and slow waves. Gray matter neurodegeneration is related to both age-related changes in sleep and age-related changes in memory, including memory for problem-solving skills. Here, we investigated whether spindles and slow waves might serve as biological markers for neurodegeneration of gray matter and for the related memory consolidation deficits in older adults. Forty healthy young adults (20–35 yr) and 30 healthy older adults (60–85 yr) were assigned to either nap or wake conditions. Participants were trained on the Tower of Hanoi in the morning, followed by either a 90-min nap opportunity or period of wakefulness, and were retested afterward. We found that age-related changes in sleep spindles and slow waves were differentially related to gray matter intensity in young and older adults in brain regions that support sleep-dependent memory consolidation for problem-solving skills. Specifically, we found that spindles were related to gray matter in neocortical areas (e.g., somatosensory and parietal cortex), and slow waves were related to gray matter in the anterior cingulate, hippocampus, and caudate, all areas known to support problem-solving skills. These results suggest that both sleep spindles and slow waves may serve as biological markers of age-related neurodegeneration of gray matter and the associated reduced benefit of sleep for memory consolidation in older adults.

中文翻译：

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睡眠纺锤波和慢波是支持解决问题技能的大脑区域灰质与年龄相关变化的生理标志

随着年龄的增长，睡眠对巩固记忆的额外好处就会消失。睡眠中与年龄相关的标志性变化之一是睡眠纺锤波和慢波的减少。灰质神经变性与年龄相关的睡眠变化和记忆力的年龄相关变化有关，包括解决问题技能的记忆力。在这里，我们研究了纺锤波和慢波是否可以作为老年人灰质神经变性和相关记忆巩固缺陷的生物标志物。四十名健康的年轻人（20-35 岁）和 30 名健康的老年人（60-85 岁）被分配到午睡或清醒状态。参与者早上在河内塔上接受训练，然后是 90 分钟的小睡机会或清醒时间，然后再接受测试。我们发现，与年龄相关的睡眠纺锤波和慢波变化与大脑区域中支持依赖睡眠的记忆巩固以解决问题的技能的年轻人和老年人的灰质强度存在差异。具体来说，我们发现纺锤波与新皮层区域（例如体感和顶叶皮层）的灰质有关，而慢波与前扣带回、海马体和尾状核中的灰质有关，所有这些区域都支持解决问题的技能. 这些结果表明，睡眠纺锤波和慢波都可以作为与年龄相关的灰质神经变性以及老年人睡眠对记忆巩固的益处降低的相关生物标志物。