The electroencephalographic characteristics of mental fatigue, which was induced by long-term working memory task of 2-back, were studied by event-related potential (ERP) technology in order to obtain objective evaluation indicators for mental fatigue. Thirty-two healthy male subjects, 22-28 years old, were divided into two groups evenly, one is un-fatigue group and the other is fatigue group. The fatigue group performed a 2-back task for 100 min continuously, while the un-fatigue group just performed a 2-back task at the first and last 10 min respectively, and rested during the middle 80 min. The subjective levels of fatigue, task performance and electroencephalogram were recorded. The impaired thought and attention states, enhanced sleepy and fatigue feeling were found in the fatigue group, meanwhile their reaction time to 2-back task extended, and the accuracy decreased significantly. These results verified the validity of mental fatigue model induced by 2-back task, and then the ERP characteristic parameters were compared and analyzed between fatigue group and un-fatigue group. The results showed that the fatigue group's amplitudes of P300 ( F = 2.539, P < 0.05) and error-related negativity (ERN) ( F = 10.040, P < 0.05) decreased significantly along with the increase of fatigue comparing with the un-fatigue group, however, there were no significant change in other parameters (all P > 0.05). These results demonstrate that P300 and ERN can be considered as potential evaluation indictors for mental fatigue induced by long-term working memory task, which will provide basis for the future exploring of countermeasure for mental fatigue.
利用事件相关电位（ERP）技术研究 2-back 任务下长时间的工作记忆所诱发的脑力疲劳的脑电特征变化，从而获取脑力疲劳评价的客观指标。32 名健康男性受试者，年龄 22～28 岁，均分为两组：疲劳组和正常组。疲劳组通过连续执行 100 min 2-back 任务来诱发脑力疲劳，而正常组在前后分别执行 10 min 的 2-back 任务，中间 80 min 休息。采集实验过程中的主观疲劳评分值、行为绩效及脑电信号并进行分析。任务后疲劳组与正常组相比，思维清晰度和注意力明显减弱，困倦程度增加，综合疲劳感上升，且操作 2-back 的反应时明显延长，正确率下降，即从主观评价和行为绩效相结合的角度验证了所诱发的脑力疲劳模型的有效性。进一步比较疲劳组与正常组的 ERP 特征参数的变化情况，结果表明：相比正常组，随着脑力疲劳的加深，疲劳组的 P300（ F = 2.539， P < 0.05）和错误相关负波（ERN）（ F = 10.040， P < 0.05）的波幅都明显下降，其他参数则未发生明显变化（均有 P > 0.05）。因此，P300 和 ERN 被证实可以作为评价长时间工作记忆任务下脑力疲劳模型的潜在指标，为后期研究脑力疲劳对抗措施提供依据。.
Keywords: 2-back; P300; error related negativity; event-related potential; mental fatigue.