ERP Study Of Information Automatic Processing And Conflict Processing In The Mental Fatigue

Mental fatigue is a kind of fatigue that is induced by a long time or intense mental activity. In modern time, the intensity of brainwork increases significantly .And the accelerating of the life pace, increased competitive pressures of society, that induce the expanding of population of mental fatigue and increasing of the level of mental fatigue. Mental fatigue has tough impact on the individual activity physiologically and psychologically. There are many relative studies in military or other special fields.It is general agreement that mental workload is a multidimensional construct, and there is no uniform standard to measure at present. Many factors can cause mental fatigue, and its performance is often induced by factors related to the commonly used model of mental fatigue, including sleep deprivation, lack of oxygen, time-on cogmitive performance et al. There are many studies showing that the level of arouse and cognition are reduced by fatigue. How to assess mental fatigue is an important issue with the value of application. There is much limitation in the past studies in which subjective evaluation was involved. ERP was employed in the present study in which the classical and creative modes were used to explore the information automatic processing and conflict processing after fatigue.16 male volunteers attended in the experiment.The experiment was employed before and after fatigue so as to get the grades of different scales and experiment data. The objective index and subjective evaluation were both used to assess the characteristic of cognition before and after fatigue. The experiment consisted of three parts: first, the subjective fatigue symptom questionnaire and VAS were employed to evaluate the subjects'state of fatigue and emotion. Secondly, different ERP modes (classical MMN, optimal MMN) were used to assess the features of pre-attentive ability in the mental fatigue. We discussed the amplitudes and latencies of classical MMN and optimal MMN induced by sounds with different frequency, intensity and duration.At last, color conflict ERP mode was used to assess the feature of conflict information processing in the mental fatigue.We discuss the impact of mental fatigue under consciousness state with N270.The main conclusions of the present study are as follows:1. The automatic processing of information was influenced by the mental fatigue, and the pre-attention was impaired. The reduction of the amplitudes of both classical and optimal MMN after fatigue occurred,which induced by sounds with different frequency, intensity and duration.2. The active cognitive processing was influenced by the mental fatigue.N270 is more sensitive to cognitive impairment. That could be supported by the reduction of the amplitudes of N270 and the reaction time becoming longer after mental fatigue.3. The subjective evaluation showed the obvious sense of fatigue after mission, and the scale grade was significantly increased after fatigue. The negative emotion was stimulated by fatigue. the indexes of Alert,Anxious, Energetic, Feel confident and Sleepy were all different from those before fatigue.