Effects And Potential Mechanism Of Transcranial Direct Current Stimulation On Visual Working Memory Subprocess

Currently,transcranial direct current stimulation(tDCS)is widely used to change the cognitive ability of the human brain,so that the relationship between cognitive function and brain-related functional areas is more accurately confirmed.Previous tDCS studies have found that anodal tDCS stimulation can show a promotion effect,that is,improving the accuracy of the test or accelerate the reaction time;Cathodal tDCS stimulation has the opposite effect and appears to inhibit the relevant function in the local brain area.Working memory,as a complex dynamic memory system,consists of two separate parts: the executive control and the maintenance process,which are defined as the execution control process and the storage process,respectively.However,previous studies have discussed the whole effects of tDCS stimulation on working memory,but cannot provide the evidence of how the tDCS affects the above independent working memory subprocesses.Therefore,this study aims to explore the independent effects of tDCS stimulation on different working memory subprocesses by applying tDCS stimulation to the right dorsolateral prefrontal cortex(DLPFC)which are closely related to the working memory subprocess,confirming the causal relationship between right DLPFC and working memory subprocesses.At the same time,combined with the resting-state EEG signal spectrum analysis,this study further analyze the neurophysiological changes in the right DLPFC after the tDCS stimulation,and determine the specific mechanism of tDCS stimulation on the working memory.This lays a fine foundation for the further exploration of complex working memory systems in the future,and also presents the possibility that the cognitive abilities contained in the brain can be finely regulated by external stimuli.The study mainly includes two parts:Part ?: This study uses the modified spatial n-back paradigm and uses the working memory capabilities required under different n conditions to distinguish two relatively independent working memory phases from the experimental paradigm: the executive control and the maintenance subprocess.This study discussed the independent changes of the working memory subprocess under different tDCS environments.The results showed that the cathodal tDCS enhanced the performance of the working memory maintenance subprocess,whereas the anodal tDCS resulted in the reduction of working memory ability by affecting the executive control function.At the same time,both tDCS stimuli applied to the right DLPFC will not affect the executive control(updating).Part ?: Combined the experimental results observed in the first part of the study: Cathodal tDCS stimulation can enhance the ability of working memory maintenance subprocesses.Through the resting state rhythm analysis of EEG signal,this study further observed the neurophysiological changes produced by the right DLPFC after applying cathodal tDCS stimulation.The results showed that the cathodal tDCS stimulation resulted in theta rhythm and alpha rhythm intensity changes in the resting state of the subjects during working memory tasks.At the same time,the theta,alpha and gamma rhythmic intensities in the fronto-parietal lobe network demonstrated the enhancement of the maintaining ability.Finally,this study concludes that the cathodal tDCS stimulation applied to the right DLPFC can selectively improve the performance of the working memory maintenance process by suppressing disturbances with irrelevant information,while the right DLPFC is not functional specific brain areas for updating.The resting state EEG rhythm analysis further provided evidence that the cathodal tDCS stimulation provided a good preparation for the subject's physiological state of tasks,enhanced the ability of maintaining working memory,and the functional connectivity of the whole brain network.