Excitation Comparison between Multi-site Stimulation using Network-based tDCS and Focal Stimulation using High-definition tDCS

Transcranial direct current stimulation (tDCS) has been developed rapidly in recent years and derived various forms which serve as therapeutic tools for neurological disorders. However, differences of stimulation effect among these stimulation strategies have not been fully explored. In this pilot study, we compared the stimulation effect between High-definition tDCS (HD-tDCS) and Network-based tDCS (NB-tDCS) on a healthy subject. HD-tDCS mainly stimulated primary motor cortex with 2mA current and NB-tDCS was designed to stimulate main motor-related areas including primary motor cortex, premotor cortex and supplementary motor area with the same amount of current in total. Cortico-muscular coherence (CMC) derived from EEG/EMG, which measures the synchrony between cortical neural activity and muscles, was collected from isometric wrist extension tasks. The results demonstrated more motor-related regions excited and longer high-level lasting effect after NB-tDCS compared with HD-tDCS, which indicated the potential power of multi-site stimulation. This study might provide some guidance and hints for transcranial stimulation strategies in the future.