Study On Cognitive Impairment Caused By Mental Fatigue And Music Intervention Based On EEG Signals

Mental fatigue is a common problem in modern people’s daily life.Many accidents happened because of operational errors caused by mental fatigue of operators.Researches have found that mental fatigue can damage many kinds of cognitive functions,and music can effectively relieve fatigue.Therefore,this study induced mental fatigue by 70 min continuous task,and used Go /Nogo task and CNV(contingent negative variation)experimental paradigm as fatigue evaluation tasks.Through EEG ERP,time-frequency analysis and source analysis,the physiological and psychological mechanism of mental fatigue damage response inhibition and attention maintenance function was explored.In addition,music intervention was used to study whether the attention maintenance of mental fatigue damaged could be effectively recovered and the psychological cognitive process behind it.Study 1 used Go stimulus(response task)and Nogo stimulus(inhibition task)in Go/Nogo task paradigm was used to evaluate changes of behavioral and EEG characteristics before and after mental fatigue,and to study the psychological and cognitive mechanism that mental fatigue damaged response inhibition function.This study included nineteen health male subjects.Metrics of EEG analysis included amplitude and latency of event-related potential N2 and P3,and brain oscillation rhythm of θ and β frequency band.Repeated measures ANOVA was used to analyze the EEG Metrics before and after mental fatigue.Results show that: reaction times and correct rates of Go stimulus after mental fatigue didn’t change significantly,but the correct rates of Nogo stimulus decreased significantly.After mental fatigue,the N2-latency of Nogo stimulus on Cz electrode and P3-latency of Go stimulus on Fz electrode all prolonged significantly,the P3-amplitude of both Go and Nogo stimulus on Fz and Cz electrodes decreased significantly.On Fz electrode,mental fatigue caused β band power with 200-500 m time window and 600-750 ms time window of Nogo stimulus both significantly.Study 2 used CNV paradigm to evaluate the changes in behavioral and EEG characteristics before and after mental fatigue,and to explore the psychological and cognitive mechanism that mental fatigue impaired attention maintenance function.This study included twenty-five healthy subjects.Reaction time and lapse rate in the CNV paradigm was used to evaluate mental fatigue induced behavioral changes.Metrics of event-related potential(ERP)analysis included mean amplitudes of the early component and late component of CNV,which correspond to 500-1000 ms and 2250-3050 after the presentation of the warning signal.Standardized low resolution tomographic analysis(s LORETA)was used to compute the cortical 3D distribution of current density for different time window of CNV before and after mental fatigue.Results show that: reaction time of the command signal in CNV didn’t change after mental fatigue,but lapse rate increased significantly.After mental fatigue,the amplitude of the early CNV component decreased significantly in the central and parietal electrodes,and the amplitude of the late CNV component decreased significantly in the prefrontal,central and parietal electrodes.Source localization results indicated decreased activity in the left posterior insular cortex within the late component time window.Study 3 based on study 2.This study asked subjects to listen to a Mozart music or sit down for 5 minutes after completing a fatigue,to study whether music intervention can alleviate the decline of attention maintenance caused by mental fatigue,and to explore the underlying psychological and cognitive mechanism.This study included 25 healthy male subjects,among13 in the music group and 12 in the control group.The response time of CNV paradigm was used to evaluate the behavioral changes caused by mental fatigue.The other indicators were the same as those in study 2.The results showed that: response time of CNV command signal in the group of music significantly decreased after the music intervention.The amplitude of CNV in the music group on the CPz electrode has little recovery compared with that after fatigue induction.The difference in the early components of CNV before and after CPz electrode intervention was marginal significant between the music group and the control group.The difference in mid-term of CNV on Cz electrode before and after intervention was marginal significant between the two groups.The source localization results showed that in the control group,the activity of the parahippocampal gyrus cortex significantly increased during the time window of CNV mid-term after music intervention.In summary,the prolonged latency of N2 and decreased β band power are important neurophysiological features of impaired response inhibition function after mental fatigue.The posterior insular cortex is involved in sensorimotor processes,which may underlie the attenuated CNV amplitude and impaired attention maintenance after prolonged mental tasks.Music intervention can restore the attention maintenance function of brain fatigue damage,possibly due to the maintenance of early attention response orientation and post reaction movement expections by music,and music may inhibit the involvement of the parahippocampal gyrus in emotional experience process.