| Neural oscillatory activity is the spontaneous and rhythmic electrical activity generated by the electrophysiological activity of brain nerve cells in the cerebral cortex or scalp surface.Meanwhile,the oscillating activity of the human brain’s resting state is regarded as an indicator of the internal state of the brain,on which neuroscientists have been concentrating more and more attention.In recent decades,in the field of brain science,transcranial alternating current stimulation（tACS）has been adopted as a significant non-invasive brain stimulation（NIBS）technique to interfere with neural activities of the brain by an increasing number of scientists and researchers,an attempt to explore the causal relationship between brain activity and cognitive process with the help this technology.However,unlike the abundant studies on tACS with relatively longer duration of electrical stimulation（more than 10 minutes）,studies on tACS with shorter duration of stimulation（less than 1 minute）are apparently insufficient.It is considered that once short-term tACS has the same after-effect as long-term tACS,its convenience will definitely make it prior to be applied.Thus the study on the effect of short-time tACS is the primary purpose of this research.Additionally,alpha-tACS studies with longer stimulation time lack a comparison between 10Hz and individual alpha frequency（IAF）at different frequency levels in the same band.Through two experiments,new evidence for a causal relationship between tACS and resting state neural oscillations is provided.In experiment 1,a new short-time stimulation scheme is designed aiming to achieve different regulation effects of resting state neural oscillations by applying short-time tACS at different frequency bands and different frequency levels to the resting state of brain.Specifically,tACS at different frequency bands（1Hz,5Hz,10Hz,20Hz,40Hz and 80Hz）is applied to the F3 and P3 points of the left frontal parietal region of the participants in eyes-closed resting state and at different frequency levels（1Hz,5Hz,10Hz,20Hz,40Hz and 80Hz）for 10s.As is shown in the result,under eyes-closed resting state,10Hz-tACS inhibited neural oscillations in alpha band.Besides that beta band oscillations are significantly inhibited in the parietal lobe near occipital lobe and significantly enhanced in the right frontal region,other band oscillations are significantly enhanced in some regions under the regulation of tACS at other frequencies.In experiment 2,the effects of tACS at 10Hz and IAF levels are investigated.In the same eyes-closed resting state,the stimulation area and intensity are the same as experiment 1,but the stimulation lasts for 15 minutes,with the stimulation frequency set 10Hz and individual alpha frequency（IAF）respectively.As is shown in the result,10Hz-tACS significantly enhanced the delta,beta and gamma oscillations in some regions of the right brain,while a small part of the right parietal lobe near the occipital lobe（between P4 and PO4）showed a significant inhibitory effect on alpha oscillation.Also,IAF-tACS showed significant inhibition of other oscillations except gamma oscillations in different brain regions,especially for alpha oscillations,the inhibition of which almost covered the whole brain.Additionally,the inhibition degrees of 10Hz-tACS and IAF-tACS on alpha oscillation in the overlapping region（P4 and PO4）are also compared,which turns out to be not significantly different.The results of the two experiments show that short-time tACS is effective and convenient for regulating brain activity in the resting state,which reflects the potential of the technology.Furthermore,10Hz-tACS and IAF-tACS target the resting state alpha oscillation,and the latter shows a more active inhibition.In addition,tACS at F3 and P3 on the left side of the brain are desirable stimulation targets. |
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