The Effects Of TACS And TDCS On Mental Rotation Cognitive Tasks

Mental rotation an important yardstick to assess spatial intelligence.Recent mental rotation experiments have proved that human mental rotation activities not only affect the activities of different regions of the brain,but also affect people's cognition and judgment process.To a certain extent,the ability of mental rotation represents the strength of spatial cognitive ability.Transcranial Alternating Current Stimulation(tACS)and transcranial Direct Current Stimulation(tDCS)are both non-invasive electrical stimulation techniques by applying weak currents to the scalp.Studies have shown that both tDCS and tACS can improve mental rotation.In this paper,we use mental rotation as an experimental paradigm of spatial cognition and explore the differences of cognitive ability between tACS and tDCS from four aspects: behavioral statistical analysis,EEG signal analysis,brain function network analysis,and brain effective connection analysis.The main contents of this paper are:1.Completing the data collection of behavioral experiment.The response time and accuracy before and after pseudo stimulation,tACS and tDCS were statistically analyzed.The results showed that the response of tACS and tDCS decreased significantly after stimulation,and the effect of tDCS was more significant.2.EEG experimental data were collected and analyzed EEG data from two aspects of event-related potential and time-frequency after pseudo stimulation,tACS and tDCS stimulation.The results showed that the amplitude of N2 components decreased after tDCS and tACS stimulation,and the excitability of the brain decreased,the amplitude of N2 was smaller after tDCS stimulation.Event related desynchronization occurred after tACS and tDCS stimulation,which confirmed that the subjects had motor imagery processing during the mental rotation judgment.3.The Pearson correlation algorithm and phase synchronization algorithm were used to construct the correlation matrix of EEG data,and three network parameters,including node degree,clustering coefficient and characteristic path length were calculated.The results of Pearson correlation method show that the length of characteristic path is significantly affected by applying tACS and tDCS;The results of phase synchronization algorithm show that only the characteristic path length changes significantly after applying tDCS.4.Brain effective connectivity analysis.After tACS and tDCS,the strength of effective connections increased.The effective connections and outflow information nodes in the control group were mainly located in the right brain,the effective connections and outflow information nodes in the tACS and tDCS groups were mainly located in the left brain.The left brain is "cognitive brain",the right brain is "emotional brain",this suggests that tDCS and tACS make the left brain "cognitive brain" more active.In this study,behavioral experiments results and EEG experiments results are combined to comprehensively and deeply analyze the differences of tACS and tDCS effects on spatial cognition,and provides some reference for analyzing the mechanism of tACS and tDCS.