Sequence memory is subject to age-related decline, but the underlying processes are not yet fully understood. We analyzed electroencephalography (EEG) in 21 healthy older (60–80 years) and 26 young participants (20–30 years) and compared time-frequency spectra and theta-gamma phase-amplitude-coupling (PAC) during encoding of the order of visually presented items. In older adults, desynchronization in theta (4–8 Hz) and synchronization in gamma (30–45 Hz) power did not distinguish between subsequently correctly and incorrectly remembered trials, while there was a subsequent memory effect for young adults. Theta-gamma PAC was modulated by item position within a sequence for older but not young adults. Specifically, position within a sequence was coded by higher gamma amplitude for successive theta phases for later correctly remembered trials. Thus, deficient differentiation in theta desynchronization and gamma oscillations during sequence encoding in older adults may reflect neurophysiological correlates of age-related memory decline. Furthermore, our results indicate that sequences are coded by theta-gamma PAC in older adults, but that this mechanism might lose precision in aging.

中文翻译：

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健康老年人与序列记忆相关的大脑振荡过程

序列记忆会随着年龄的增长而衰退，但其潜在过程尚未完全了解。我们分析了 21 名健康老年人（60-80 岁）和 26 名年轻参与者（20-30 岁）的脑电图 (EEG)，并比较了编码过程中的时频谱和 θ-γ 相位幅度耦合 (PAC)。视觉呈现的物品。在老年人中，theta（4-8 Hz）功率的去同步和gamma（30-45 Hz）功率的同步并不能区分随后正确和错误记忆的试验，而对年轻人来说则存在随后的记忆效应。 Theta-gamma PAC 通过项目在老年人而非年轻人的序列中的位置进行调节。具体来说，序列中的位置由连续 θ 相位的较高伽马振幅进行编码，以便以后正确记住试验。因此，老年人序列编码过程中 θ 去同步化和 γ 振荡的分化不足可能反映了与年龄相关的记忆衰退的神经生理学相关性。此外，我们的结果表明，老年人中的序列是由 theta-gamma PAC 编码的，但这种机制可能会在衰老过程中失去精确性。