中文摘要：

目的研究连续长时间脑力劳动对中枢疲劳的影响，探讨脑电的Hilbert—Huang变换参数与中枢疲劳之间的关系，寻找中枢疲劳程度评价的客观指标。方法对连续脑力劳动前后状态下的脑电信号进行Hilbert．Huang变换，提取基本模式（IMF）分量及整个脑电信号的中心频率和能量比参数进行分析，并采用主观评价法对前后状态进行对照分析。结果连续长时间脑力劳动后，主观感觉疲劳程度显著增加，脑电各IMF分量和整个脑电的能量重心向低频迁移，信号中能量分量较大的信号成分的频率降低。结论Hilbert—Huang变换参数可以较好地反映疲劳前后脑电能量的分布情况，刻画整个脑电能量重心的迁移情况，为实时分析与监测中枢疲劳提供可能，有望成为衡量中枢疲劳程度的客观指标。

英文摘要：

Objective To study the effects of long termmental work on mental fatigue, and investigate the rela tionship between mental fatigue and parameters of HilbertHuang transform of electroencephalogram （EEG） so as to find feasible objective indexes for analyzing mental fatigue level. Methods HilbertHuang transform was used to analyze EEG of different mental fatigue states before and after long period mental work. Middle fre quency and energy percentage of IMF and whole EEG were extracted to analyze the different states. For com parison, subjective measurements were also conducted to evaluate the mental fatigue state. Results After long period mental task, the scale of subjectively perceived fatigue decreased, the energy gravity of IMF and whole EEG moved to the low frequency, and the frequency of larger energy EEG component decreased. Conclusion The parameters of HilbertHuang transform can effectively reflect the distribution of EEG energy before and af ter mental fatigue, and characterize the changes of the energy gravity of the whole EEG. Therefore, it provides the feasibility of analyzing and monitoring the mental fatigue state in real time, and is expected to serve as the obiective index for detectin~ mental fatigue level.