Source separation on single channel EEG: A pilot study on effect of transcranial alternating current stimulation on scalp meridian.

Brain electrical stimulation has shown the capability to modulate neural activities in a variety of ways. Compared with transcranial direct current stimulation(tDCS), transcranial alternating current stimulation (tACS) may affect brain activities differently through a frequency-based mechanism. This pilot study applied tACS to the scalp following the meridian (Jingluo) of traditional Chinese medicine to explore its potential neural modulation effect. A wearable electroencephalogram (EEG) device was used to measure the frontal activity in a female participant before and after tACS longitudinally. A combined method of singular spectrum analysis (SSA)-independent components analysis (ICA) was applied to separate potential artifacts from ocular and other irrelevant sources. The results demonstrated that SSA-ICA could effectively separate signals from different sources especially the ocular artifact. EEG spectrum analysis showed that short-term tACS could increase the power of delta waves. This study has good implications for the use of tACS and SSA-ICA method for the study of brain activities. Future research is needed to refine more optimum parameters of tACS and SSA-ICA to make the evidence more solid.Clinical Relevance- tACS may influence the brain wave oscillations through the frequency-based mechanism. SSA-ICA method helps to broaden the use of wearable EEG devices for various clinical applications.