A Preliminary Study Of Nap Effect On Declarative Memory Consolidation

In recent years, sleep has become a hot research problem. As we all know, sleep can make our mental and physical rest and relaxation. In addition, sleep has some impacts on human cognitive function. Most studies on sleep function are focused on memory consolidation. During sleep, memory fragments are processed and coded to consolidate memory and form a stable long-term memory in the brain. As a special form of sleep, the siesta sleep plays an important role in memory consolidation. This research investigates the sleep impact on declarative memory consolidation from the perspective of a nap.In this thesis, the research is based on the theory of sleep and memory. First, this thesis outlines the basic concepts and the relationship between the sleep and memory, and summarizes the effects of sleep on different types of memory and the different stages of sleep on memory consolidation from the status of sleep and memory research. In addition, this thesis has a detailed discussion of the mechanism of memory consolidation and the classification of memory. This thesis analyzes the features and analytical method of EEG in sleep state, including the delineation of EEG classification, sleep stages and the algorithm of spindle detection.In this thesis, twenty college students were recruited. The declarative memory task used is associated word pairs. After the task, subjects went to sleep with their sleep EEG data collected simultaneously, to investigate the memory consolidation mechanism. In the experiments in this thesis, the subjects were divided into two groups of sleep and wakefulness, both of groups used the same memory task to study the effect of sleep on declarative memory. To further investigate the mechanisms of sleep and memory consolidation, this thesis focused on analysis of the EEG during sleep, sleep architecture, sleep stages and sleep spindles.The results show that the increasing number of words remembered in sleep group significantly higher than the wake group, indicating sleep does have a certain role on declarative memory consolidation. The time duration of stage REM and stage N3 has a positive correlation with the increased number of word pairs, which describes the important role of the slow-wave sleep on memory consolidation. REM sleep may also impact on the consolidation of declarative memory. Negative trends were shown between N1 and N2 sleep latency and the number of words. The longer sleep latency is, the weaker the sleep effect on memory consolidation. And the number of sleep spindles has a significant positive correlation with the increased word pairs, indicating that the spindles may play an irreplaceable role in memory consolidation.Overall, on one hand, this study verified the nap can process declarative memory, on the other hand, described the structure of sleep, sleep time of REM and N3, sleep latency of N1 and N2 stages and spindles number play an important role on the declarative memory consolidation. The Conclusions of this study improve our understanding of sleep and provide theoretical support for the consolidation of mechanisms of memory in some extent.