Connectivity mapping of human brain by phase based evolution map approach

Electrocorticography (ECoG) is recorded directly on the exposed surface of cortex, and directional connectivity mapping of ECoG signal was proved essential in the definition of epileptogenic zones, and besides, could also be one kind of command source for Brain-Machine Interface (BMI) controlling. In this study, brain connectivity was evaluated and represented by directionality index, which was computed by phase based evolution map approach (EMA). In simulation study, directionality index and its short time correction were compared. The result showed that corrected algorithm had smaller variance and was more reasonable in cascade signal ensembles study. We applied this method to hand movement related human ECoG data, the primary motor cortex is found to have higher driving during the hand open-close movement onset than the baseline. By the experiments, the method could be further used to explore the alteration of information transfer and neural circuits during movement and could be the source for BMI tasks.