Dose-dependent enhancement of coordination through multibrain transcranial stimulation: A fNIRS hyperscanning study

Coordination serves as a fundamental driving force in the evolution of human society, and transcranial electrical stimulation (tES) is increasingly recognized for its ability to modulate human coordination. However, the neural mechanisms underlying coordination and whether tES positively influences it remain under investigation. In this study, we explored the mechanisms of interbrain synchronization (IBS) and the neural efficiency enhancement of the mirror neuron system (MNS) using single multibrain tES combined with functional near-infrared spectroscopy (fNIRS) hyperscanning, with a focus on the unique advantages of single online transcranial alternating current stimulation (tACS). Our findings revealed that 10 high-dose tES sessions led to greater improvements in coordination compared to single sessions, while offline transcranial direct current stimulation (tDCS) demonstrated superior efficacy. Notably, enhanced neural efficiency played a significant role in cumulative coordination improvements, indicating that the benefits of improved coordination extend beyond basic tasks and can be applied to more complex scenarios, such as coordinative flight operations. These results underscore the dose-response relationship in modulating brain activity related to IBS or the neural efficiency of MNS through various external tES modalities, thereby enhancing human coordination.