科研之友
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摘要
BACKGROUND: According to observable behaviors, sleep and wakefulness are two fundamentally different behavioral states. Although electroencephalogram (EEG) is traditionally used to define sleep stage, it is difficult to detect or to quantify microarousals or disruptions during sleep. In addition, initial sleep cannot be defined. It is thought that the wake-sleep transition cannot be defined by EEG patterns. OBJECTIVE: To observe the behavioral response magnitude during wake-sleep transition by EEG monitoring and to define the wake-sleep transition. DESIGN, TIME AND SETTING: A behavioral and neural network study was performed at the Key Lab of Human Being Development and Mental Health of Central China Normal University, and Lab of Brain and Cognitive Science of South Central University for Nationalities, China in July 2007. PARTICIPANTS: A total of 30 healthy volunteers, of equal gender and aged (1 9.7 +/- 1.1) years, were recruited from the Central China Normal University, China for this study. None of the subjects had undergone EEG recording prior to this study or received any medication for sleep disturbances. METHODS: A novel adaptive approach was applied to detect wake-sleep transition, which avoided stimulus-induced waking. To test the difference between wake state and wake-sleep transition, the amount of self-information and mutual-information were effective parameters to analyze wake-sleep transition. MAIN OUTCOME MEASURES: The following parameters were measured: morphological changes in reaction time-magnitude, as well as correlation between phase changes and sleep, and wake and wake-sleep transition. RESULTS: There were three typical phases in morphological changes of reaction time-magnitude. With regard to the behavioral definition and criterion for sleep, the phase morphological characteristics displayed good correlation with behavioral states, such as sleep, wakefulness, and sleep onset. Entropy as an indicator of brain cognitive processes was introduced to test for differences between the wakefulness and sleep onset phase. Results indicated a cognitive declined transitional period different between sleep and wake. After staggered cognitive changes during the wake-sleep transition, the brain underwent marked alterations and transitioned into sleep quickly with no bi-directional EEG changes. CONCLUSION: Wake-sleep transition exists as an independent stage.
