Analyses Of Auditory Evoked Potentials Features Based On Mental Fatigue

Mental fatigue is very common in our daily life,which generally includes such symptoms as fatigue,impaired working efficiency and declined vigilance.Students,white-collar workers and others who perform long-time cognitive tasks often face the problem of mental fatigue,which severely affacts their study and work.In this thesis,the mental fatigue model for sustained cognitive tasks was built aiming at the fatigue caused by a long-time heavy load mental activity.Event-Related Potential(ERP)technology was employed in which the P3 a,P3b and Mismatch Negativity(MMN)induced by auditory experimental paradigms were used to study the variance of cognitive function in the state of mental fatigue and to explore the objective indicators for evaluating and monitoring mental fatigue.Moreover,the regulation effect of magnetic stimulation at acupoints on mental fatigue was studied by stimulating corresponding acupoints.First,two sub-components of P300,namely P3 a and P3 b were induced by a novel oddball paradigm.In addition,Mismatch Negativity(MMN)component was induced by the traditional oddball paradigm.Then,a mental fatigue model for learning English four hours consecutively was established.The waveforms of the three Auditory Evoked Potentials(AEP)before and after cognitive tasks were compared and the peaks and latency were measured and analysed statistically.According to the statistical results,the evaluation indicators of mental fatigue were confirmed.And then,the SHENMEN,HEGU and LAOGONG points of subjects were stimulated successively by magnetic stimulator after sustained cognitive tasks.The indicators of mental fatigue before and after magnetic stimulation were measured and analysed statistically.Further the regulatory mechanism of time-varying pulsed magnetic field on mental fatigue through acupoints was explored.The results show that the peak values of P3 a,P3b and the average amplitude of MMN evoked by frequency deviation can be used as the evaluation indicators of mental fatigue caused by sustained cognitive tasks,but the latency can not be used as the evaluation indicator of mental fatigue;magnetic stimulation at acupoints can reduce the mental fatigue level in a certain extent.This thesis provides a theoretical basis for the assessment of mental fatigue caused by sustained cognitive tasks and gives a new way of thinking for the exploration of alleviation method of mental fatigue.