Neural and cardiac rhythms interact differently during stress and meditation. In 21 young adults with no meditation experience, heart rate and alpha brainwave frequency both slowed more during breath focus meditation than during a stressful arithmetic task. The ratio between alpha and heart rate frequencies was smaller under stress, and a specific 8:1 cross-frequency relationship occurred more often, suggesting a mechanism for coupling neural and cardiac rhythms during mild cognitive stress. Changes in these cross-frequency relationships were mostly driven by shifts in heart rate. Integrating physiological markers and their interactions may better characterize stress responses and meditation, guiding biofeedback and neurofeedback interventions.
Expert meditators show a shift from reactive to proactive control over the connection between brain and body compared to novices. During breath-focused meditation, both groups slowed their breathing, but experts had the lowest rates and higher parasympathetic (rest-and-digest) tone. Information-flow analysis showed that novices' heart and breathing signals more strongly influenced brain alpha activity, whereas experts showed stronger top-down control from the brain to breathing, especially in frontal brain regions. Experts also showed a reduced ratio between alpha brain waves and heart rate during meditation. These results suggest that meditation training changes how the brain and body interact, consistent with predictive processing theories of interoception.