Research On The Brain Mechanism And Training Of Task Switching Based On Transcranial Direct Current Stimulation Technology

Task switching is one of the most common cognitive activities in daily study,work,and life.multiple tasks need to be processed simultaneously or continuously,which requires individuals switching between different tasks rapidly and frequently.In civil aviation flight activities,multitasking processing including task switching such as landing,observation of instrument,monitoring internal and external cabin environment,and changing flight status can be seen everywhere.At the same time,the superior cognitive ability can minimize the negative effects of fatigue and hypoxia,and other extreme environments.Thus,both daily multitasking and flight activities in extreme environments require pilots to have excellent switching ability.For flying cadets,flight training takes a long time.during this time,cadets are very likely to be delayed or even eliminated,which is not worth the loss for the student pilots,the school,and the society.Therefore,how to improve the switching ability of individuals more effioiently besides the daily behavior training has become a problem that needs to be solved urgently.In recent years,transcranial direct current stimulation(tDCS)has been used in researches of cognitive plasticity.However,there are insufficient studies on specific brain areas and influencing factors,and few scholars have analyzed the training effect and transfer effect of the joint training mode combining long-term tDCS and task switching training,and compared it with behavioral training.Based on this,the current research conducted four studies to investigate the causal relationship between task switching and specific brain regions and its influencing factors,as well as the training effect of joint training mode.In the study 1,a confirmatory experiment(i.e.,Experiment 1)was conducted to compare the switching ability of flying cadets and college students.The results showed that there was no significant difference in the switching ability between cadets and college students when they are freshman.However,when they are graduated,the switching ability of cadets was significantly higher than the college students.The results of Experiment 1 showed that switching ability played an important role in flight activities,which laid a foundation for the follow-up researches on the brain mechanism and task switching training.In the study 2,the causal relationship between specific brain regions and task switching was explored through two experiments.In Experiment 2,we found that a-tDCS over the right dorsolateral prefrontal cortex significantly improved the unpredictable task switching performance,but had no significant effect on the predictable task switching performance.In Experiment 3,we found that a-tDCS over the right parietal cortex significantly impaired the switching performance of predictable tasks,but not unpredictable tasks.The results of Experiment 2 suggested that the right dorsolateral prefrontal cortex improved the unpredictable task switching performance though the active inhibition process of irrelevant information.The results of Experiment 3 suggested that active tDCS over the right parietal cortex would impair the endogenous preparation for task switching,which led to the worse task switching performance.In the study 3,we conducted two experiments to explore the moderation effects of task type and task cue separation on a-tDCS induced effect over the right dorsolateral prefrontal cortex.In Experiment 4,we found that a-tDCS had significantly opposite a-tDCS effects on different types of switching tasks,that is,it positively affected the parity/magnitude task,but negatively affected the parity/vowel-consonant task.These results demonstrate the relationship between the right dorsolateral prefrontal cortex and the active inhibition of irrelevant information.Experiment 5 showed that the task-cue separated task switching had higher mixing cost and lower switching cost than the unseparated task switching.Meanwhile,the main effect of the group was significant only after the inconsistent task trials were eliminated.The switching cost of the RA group was significantly lower than that of the Sham and the LA group.The results of Experiment 5 indicates that task-cue separation plays a negative role in the causal relationship between the right dorsolateral prefrontal cortex and task switching.The results of study 4 showed that task type and task cue separation moderated the a-tDCS induced effect over the right dorsolateral prefrontal cortex.In the study 4,one experiment(Experiment 6)was used to investigate the difference of training effect and transfer effect on different groups(behavioral training,joint training,behavioral control and a-tDCS control)in task switching training.The results showed that the task-switching performance in both the behavioral training group and the joint training group improved continuously with the increase of training times.At the same time,the first increase rate of switching cost in the joint training group was significantly higher than in the behavioral training group.The results show that the a-tDCS joint training mode can significantly improve the training effect in the early stage of task switching training.In addition,in experiment 6,no significant transfer effect was found on inhibition,updating and new switching tasks.To sum up,current research confirmed that the flying cadets(graduated)have task-switching ability advantages.Based on the results of the relationship between specific brain regions(the dorsolateral prefrontal cortex and the parietal cortex)and task switching,also the moderation effects of task predictability,task type and task-cue separation in a-tDCS induced effect over the right dorsolateral prefrontal cortex,we used a-tDCS joint training mode in unpredictable task switching,and found an improved training effect of the early stage.Current research provides a new experimental evidence and thought for future researches.