Regulation Of Motor Learning Capability Based On Transcranial Alternating Current Stimulation

Motor learning refers to the acquisition and consolidation of a new motor skill,which is closely linked with our daily life.Motor learning involves multiple brain regions,accompanied with synaptic plasticity and changes in motor cortex plasticity.Motor learning and relearning can improve dyskinesia caused by cerebral injury,for example,stroke.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.It mainly includes transcranial direct current stimulation(tDCS)and transcranial alternating current stimulation(tACS).Previous studies have demonstrated that tDCS can increase motor learning capability,and can improve dyskinesia caused by stroke to some extent.This study aims to investigate the tACS influences on motor learning,which has never been studied before.A total of 60 subjects were recruited in this study,which were equally divided into four groups.All subjects were first required to execute four kinds of serial reaction time tasks(SRTTs),respectively,i.e.pressing keyboard randomly/sequently using left/right hand.During the test,their behavioral performances and electroencephalogram were recorded.During the execution of movements,event related desynchronization/synchronization always appears near 20 Hz,and studies showed 20 Hz tACS can make an effect on the motor learning capability,so the present study chose 20 Hz as stimulation frequency.Then all subjects underwent a period of 20 Hz tACS.The four groups were stimulated with different patterns,i.e.real/sham stimulation on the left/right primary motor cortex(the area near C3/C4 lead).After the stimulation,the SRTT tests were performed again for all subjects,while the behavioral performance and EEG were recorded.The behavioral and EEG data were analyzed and compared between pre-and post-stimulation.It showed that,compared with the right hand keypress,the speed of left hand keypress had a significant improvement after the real stimulation on the right side.The readiness potential analyses revealed that the latency was significantly smaller for the real stimulation than the sham stimulation on the right primary motor cortex.The event related desynchronization/synchronization analyses found that under the real right-side stimulation,the ERD for the right hand keypress was significantly lower than that for the left hand at C3,While significantly higher at C4.In summary,this study revealed that the 20 Hz tACS on the right primary motor cortex can facilitate the motor learning capability of left hand.It indicates that tACS has a potential application in the rehabilitation of motor function after stroke.