Delay estimation for cortical-muscular interaction via the rate of voxels change

It is evident that corticomuscular coherence (CMC), representing the functional coupling between motor cortex and muscle tissues, plays a crucial role in neurophysiologic studies and applications. It is hypothesized that there is an unknown time delay comprising at least neural conduction time in the process of corticomuscular interaction. In this study, we developed a novel delay estimation method, defined as the rate of voxels change (RVC) for the estimation of time delay in two coupled physiological signals. The RVC is the dynamic variation of the local CMCs observed in different time offsets. Both simulation and physiological data confirm the capability of RVC in estimating cortical-muscular delay. The underlying mechanisms of individual discrepancy of the latency is also investigated via exploring the correlation between delays, brain activity and motor performance. Correlation analyses indicate an intrinsic link between the connectivity strength of the brain network and the length of time delay in cortical-muscular interactions.