The interplay between cardiac and brain activities within a balancing skill-challenge context during goal-directed motor control

The cardiac oscillatory is found to regulate the brain's functional networks that support cognitive processing and self-awareness. However, whether these associations are specific to certain clinical contexts or general principles remains unclear. The present study investigated oscillatory associations between heart rate variability (HRV) and electroencephalogram (EEG) rhythms to explore the dynamic co-regulatory mechanisms between them when facing tactical motor demands. We performed two studies using a simulated quadrotor UAV operation system, which provided tasks with adjustable skill-challenge balance. Through the variations in motor control prompted by skill proficiency (Study 1) and task demands (Study 2), we conducted some common analyses within the same group of participants, including heartbeat-evoked potentials (HEPs), phase-amplitude coupling (PAC) cross-modal phase-amplitude coupling (xPAC), heart rate variability, and predictive relationships among them. Our results suggested that the association between HRV and PAC can be characterized by the functional relationship between brain and heart, such as xPAC and HEP. As participants became more flexible and adept in motor control, cardiac-brain oscillatory interactions tended to become more coordinated. Within individuals, xPAC robustly tracked PAC across conditions, whereas HRV showed predictive power primarily when skill and task demands were reasonably balanced. Such findings may hold promising implications for enhancing our understanding of performance in neuroergonomics and clinical rehabilitation.