睡眠依赖性记忆巩固受年老化影响的机制

发布时间：2018-08-28 16:16

【摘要】：睡眠不仅具有重要的生理意义,在人的认知过程中也扮演着重要角色。研究表明,学习后立即进入睡眠,相较于学习后保持同等时间的觉醒,有助于记忆的保持和提高,睡眠对于记忆的这种巩固作用被称为睡眠依赖性记忆巩固。随着年龄的增长,老年人的记忆功能逐渐下降;同时,老年人在老化的进程中伴随着睡眠时长的减少,睡眠片段化增加,睡眠效率下降以及慢波睡眠显著减少等睡眠功能的损伤。因此,依赖于记忆和睡眠的睡眠依赖性记忆巩固功能在老化进程中的变化引起了研究者的广泛关注。尽管大量研究证据表明睡眠依赖性记忆巩固效应在老化过程中受损,但是由于受到记忆类型、睡眠阶段、记忆提取方式等因素的影响,研究结果并不一致。此外,研究表明情绪对记忆巩固具有促进作用,即与中性记忆材料相比,情绪记忆材料不仅能得到更深程度的编码也能在随后被更好地提取。近年来,关于睡眠依赖性情绪记忆巩固的研究结果表明,相较于中性记忆的巩固,睡眠对情绪记忆巩固的促进作用更大,并且这种促进作用存在时间上的延迟效应。然而,睡眠依赖性情绪记忆巩固受老化影响的机制尚未阐明。前人研究普遍支持老年人在情绪加工过程中的正性情绪偏向,即在记忆、注意、决策等领域老年人表现出对正性刺激的偏向和对负性刺激的规避现象。然而老年人的睡眠依赖性情绪记忆巩固中是否同样存在正性情绪偏向尚未有研究进行过探讨。鉴于此,我们针对上述研究目的开展了以下三项研究:研究一采用元分析技术,探讨睡眠依赖性记忆巩固的年龄效应。通过文献筛选后,共15篇文献包含22个研究被纳入该元分析中。研究首先比较了年轻人和老年人睡眠依赖性记忆巩固效应的差异;接着分记忆类型考察了睡眠依赖性记忆巩固的年龄差异;最后在睡眠条件和觉醒条件下探索了年龄差异的真正来源。研究结果表明,睡眠依赖性记忆巩固在老化过程中受损,且主要表现在陈述性记忆方面,而显著的年龄的效应主要由被试在睡眠条件下的记忆差异造成。研究二从老年人对正性刺激偏向的角度考察老年人睡眠依赖性巩固的正性情绪偏向效应。结果表明,学习后睡眠有利于促进年轻人中性记忆的巩固,而对于老年人来说,睡眠选择性地促进了老年人正性情绪记忆的巩固,提示老年人的睡眠依赖性记忆巩固存在正性情绪偏向。此外,研究发现深度睡眠比例和年轻人负性情绪记忆保留量之间呈显著负相关,但这种相关在老年人当中并不显著,提示老年人睡眠依赖性记忆巩固中的正性情绪偏向可能与深度睡眠和负性记忆之间连接的中断有关。研究三从老年人对负性刺激规避的角度考察老年人睡眠依赖性巩固的正性情绪偏向效应。结果表明,相较于学习后保持觉醒,学习后睡眠的年轻人对负性图片的空间位置的遗忘率高于对中性图片空间位置的遗忘率;而老年人对负性图片的空间位置的遗忘率低于对中性图片空间位置的遗忘率。这些研究结果表明老年人在睡眠依赖性记忆上存在正性情绪偏向:老年人由于对图片负性情绪的规避,对图片空间位置的注意更多,而年轻人由于过多地被图片的负性情绪所吸引,减少了对图片空间位置的注意,导致了睡眠后对两种效价图片的空间位置记忆的差异。综合以上研究结果发现:相比于年轻人,睡眠对老年人记忆巩固的促进作用受损,且睡眠依赖性记忆巩固的年龄差异主要体现在陈述性记忆上;老年人在睡眠依赖性记忆巩固中也存在正性情绪偏向效应。本研究首次量化了睡眠依赖性记忆巩固受年老化影响的研究结果,进而考察了老化过程中情绪对睡眠依赖性记忆巩固的影响。在丰富老化影响睡眠依赖性记忆巩固的研究证据的同时,也对睡眠依赖性记忆巩固背后的神经机制研究和老年人的认知干预研究提供了一定的理论基础。
[Abstract]:Sleep not only has important physiological significance, but also plays an important role in the cognitive process. Studies have shown that sleep immediately after learning helps to maintain and improve memory compared with waking up at the same time after learning. With the increase of sleep duration, sleep fragmentation, sleep efficiency and slow-wave sleep, the memory-dependent memory consolidation is impaired in the aging process. Although a large number of studies have shown that sleep-dependent memory consolidation is impaired during aging, the results are inconsistent due to memory types, sleep stages, and memory retrieval methods. In recent years, studies on the consolidation of sleep-dependent emotional memory have shown that compared with the consolidation of neutral memory, sleep has a greater effect on the consolidation of emotional memory, and this effect exists when compared with the consolidation of neutral memory. Previous studies have generally supported the positive emotional bias in the emotional processing of the elderly, i.e. memory, attention, decision-making and other areas of the elderly showing a bias towards positive stimuli and avoidance of negative stimuli. In view of this, we carried out the following three studies for the purpose of this study: 1. To explore the age-related effects of sleep-dependent memory consolidation using meta-analysis techniques. A total of 15 literature packages were screened. Twenty-two studies were included in the meta-analysis. The study first compared the differences in the consolidation effects of sleep-dependent memory between young and old people; then examined the age differences in the consolidation of sleep-dependent memory by memory types; and finally explored the true sources of age differences under sleep and waking conditions. Dependent memory consolidation was impaired during aging and mainly manifested in declarative memory, while significant age-related effects were mainly caused by memory differences during sleep. Postschool sleep is beneficial to the consolidation of neutral memory in young adults, but for the elderly, sleep selectively promotes the consolidation of positive emotional memory in the elderly, suggesting that there is a positive emotional bias in the consolidation of sleep-dependent memory in the elderly. In addition, the study found a relationship between the proportion of deep sleep and the retention of negative emotional memory in young adults. There was a significant negative correlation, but this correlation was not significant in the elderly, suggesting that the positive emotional bias in the consolidation of sleep-dependent memory in the elderly may be related to the interruption of the connection between deep sleep and negative memory. The results showed that the spatial forgetting rate of negative pictures was higher than that of neutral pictures, while the spatial forgetting rate of negative pictures was lower than that of neutral pictures. There is a positive emotional bias in sleep-dependent memory: the elderly pay more attention to the spatial location of pictures because of the avoidance of negative emotions of pictures, while the young are attracted to the negative emotions of pictures too much, which reduces the attention to the spatial location of pictures, resulting in the spatial location of the two valence pictures after sleep. In summary, the results show that sleep impairs memory consolidation in older adults, and the age difference of sleep-dependent memory consolidation is mainly manifested in declarative memory. There is also a positive emotional bias effect in sleep-dependent memory consolidation in older adults. This study quantifies sleep for the first time. In addition to enriching the evidence of the effect of aging on the consolidation of sleep-dependent memory, we also studied the neural mechanism behind the consolidation of sleep-dependent memory and the cognitive intervention of the elderly. The study provides a theoretical basis.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：B842.3

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