Time-varying brain potentials and interhemispheric coherences of anterior and posterior regions during repetitive unimanual finger movements

Previous brain electrophysiological research has studied the interregional connectivity during the tapping task and found that inter-hemispheric alpha coherence was more significant under bimanual task conditions than that under unilateral conditions, but the interregional connectivity situation in the unilateral tapping condition was not explored clearly. We have designed a unilateral repetitive finger-tapping task to delineate the anterior and posterior cortex contributions to unilateral finger movement. Sixteen right handed college students participated in this study. Event related potentials (ERPs) and the strength of event related coherence (ERCoh) were analyzed to examine the antero-postero dominance of cortical activity in the phase of early visual process (75-120ms), pre-execution (175-260ms), execution (310-420ms) and post-execution (420-620ms). Results showed that the occipital (Oz, 01 and 02), frontal (Fz, F3, and F4), fronto-central (Fz, Cz, F3 and C3), and parietal regions were the most pronounced in the early visual, pre-execution, execution, and post-execution phases, respectively. Moreover, among four inter-hemispheric pairs only the Coh (C3 and C4) was significantly correlated to reaction time (RT) of tapping in the execution phase. In conclusion, the aforementioned variability of electrophysiological data (ERPs and coherence) and the change of antero-postero regional dominance with time reflect the relative importance of different mechanisms in different phases. The mechanisms of visual processing, motor planning, motor execution and feedback reward were operational, respectively.