Research Of The Regulation Effect Of Transcranial Direct Current Stimulation On Mental Fatigue

Mental fatigue refers to a state in which an individual feels uncomfortable after a high-intensity or long-term continuous mental activity.The occurrence of mental fatigue can lead to much decrease in working ability efficiency.Being in the state of mental fatigue for a long time would even cause great damage to the mental state and physical health.Therefore,research on the detection and regulation of mental fatigue is very important.In recent years,test of mental fatigue based on long-term driving,sleep deprivation and other conditions has been a research hotspot,aiming to detect the current fatigue state and make reminders so that mental fatigue can be alleviated by rest.However,some special fields,such as key operations in space stations,military operations,and long-term surgical operations,cannot take time to resist mental fatigue.Therefore,a method which can work quickly and safely for regulating mental fatigue is urgently needed.This research proposes a method based on transcranial direct current stimulation(t DCS)to modulate states of mental fatigue and characteristics of Electroencephalograph(EEG)signals,and then examine action effects and explore related mechanisms.In this research,we designed a task that induces mental fatigue.The 90-minute digital n-back task was chosen to construct the mental fatigue model.The combination of self-reported scales and psychomotor vigilance tests(PVT)was used to detect whether the mental fatigue model was successful before and after the task.In the regulation section,the dorsolateral prefrontal lobe(DLPFC),which is closely related to the working memory task,was selected as the stimulation position.The anodal t DCS stimulation was applied after 40 minutes since the fatigue induction task begins.The behavioral performance and EEG signals were recorded throughout the task.Both scores of self-reported scales and behavioral indicators in PVTs showed that the 90-minute digital n-back task successfully induced the mental fatigue.Behavioral indicators of the fatigue-induced task showed that the average response time of the task in the 20-minute t DCS stimulation group was significantly lower than that in the sham t DCS.Analysis of the average power and time-frequency information of EEG signals showed that the energy of alpha and beta bands in the true stimulation group increased significantly,and the energy of the beta band in the sham stimulation group significantly decreased.The analysis of brain network based on PDC matrix showed that the average path length in the true stimulation group was significantly lower than that in the sham stimulation group.The node degree and global efficiency both increased in the true stimulation group compared with the sham group.This study indicates that the 90-minute digital n-back task successfully induces mental fatigue in the current state of the subject.Transcranial direct current stimulation has a certain regulation effect on the behavioral performance,brain energy and the efficiency of information transmission of brain network,which lays a theoretical foundation for the future application of transcranial direct current stimulation on mental fatigue.