Regulation Of Motor Learning Capability Based On Gamma Rhythm Transcranial Alternating Current Stimulation

Transcranial electrical stimulation is a painless,non-invasive brain stimulation method,which can regulate the synaptic plasticity,modulate change cortical excitability,so as to improve the neuronal function.As a relatively new brain stimulation technique that regulates the neurophysiological activation pattern of transcranial electrical stimulation,t ACS can directly interfere with the brain activity of a specific frequency,change the cognitive performance and influence the neuroplasticity.This research conducts an in-depth study of the influence of gamma t ACS on the task capability of motor performance and its mechanismA total of 20 healthy subjects were recruited in this study,which were required to complete the 80 Hz t ACS and sham stimulation tests(the two experiments were separated by two weeks).The real stimulation group is divided into three parts: the first part is the initial motion state test.During the test,subjects needed to complete four types of tasks,including the sequential left/right hand reaction task and the imaginary left/right hand reaction task.Subject’s reaction time and accuracy were recorded,and subject’s neuronal oscillation activity was acquired by EEG.The second part is performed by 80 Hz t ACS.80 Hz t ACS was applied to the primary motor cortex of the subject for a duration of 20 min.The third part repeats the motion state test,and we recorded the subject’s reaction time and EEG signals.The experimental procedure and stimulation parameters of the sham stimulation group were consistent with the real stimulation group,with the difference that the stimulation duration was 30 s.The behavioral and EEG data were analyzed and compared between pre-and post-stimulation.It showed that,response times of both hand of subjects were significantly shorted,meanwhile,learning capability was significantly enhanced.There was no remarkable change in the sham stimulation group.The accuracy of two groups did not change significantly,indicating that applying gamma t ACS to the primary motor cortex could shorten the response time of both hand in reaction tasks and facilitate motor learning capability.The event related desynchronization/synchronization analyses found that under the real stimulation,the ERD of contralateral hemisphere was significantly lower than that of the ipsilateral hemisphere in gamma band.the ERD of contralateral hemisphere was significantly lower than that of the ipsilateral hemisphere in gamma and alpha～beta band.From the perspective of electrophysiology,80 Hz t ACS can synchronize the neuron response and affect the excitability of different cortical regions in a specific frequency,resulting in a so-called "resonance" phenomenon,which in turn regulates the motor performance of left/right hand.In summary,this study revealed that the 80 Hz t ACS can improve motor learning capability of hand and modulate related motor areas.It indicates that 80 Hz t ACS has a potential application in the rehabilitation of motor function after stroke and provides technical support for the optimal design of t ACS regulation parameters.