Brain-heart interactions in novice meditation practitioners during breath focus and an arithmetic task

Objectives The study of neural and visceral oscillatory activities reveals that both subsystems and their interactions influence human cognition. In particular, cardiac and neural changes during self-regulation processes can be studied through a comparison of stress-inducing procedures and meditation practices. Methods In this study, we investigate the characteristic profiles of neural-cardiac interactions during a stress-inducing arithmetic task and a breath focus meditation period in a sample of 21 young participants (10 women, age range 20-29) with no prior experience in meditation practices. Using recordings of electroencephalography (EEG) and electrocardiography (ECG), we assessed instantaneous cross-frequency relationships between the alpha neural band and heart rate in both conditions. Results Our results indicate significant heart rate and alpha frequency decelerations during breath focus compared to the stress-inducing task. Regarding alpha: heart rate cross-frequency relationships, the stress-inducing arithmetic task exhibited ratios of smaller magnitude than the breath focus task, including a higher incidence of the specific 8:1 cross-frequency relationship, compared to the breath-focus task, proposed to enable cross-frequency coupling among neural and cardiac rhythms during mild cognitive stress. The change in cross-frequency relationships were mostly driven by changes in heart rate frequency between the two tasks, as indicated through surrogate data analyses. Conclusions Our results provide novel evidence that stress responses and changes during meditation practices can be better characterized by integrating physiological markers and, more crucially, their interactions. Together, this physiologically comprehensive approach can aid in guiding interventions such as physiology modulation protocols (biofeedback and neurofeedback) for emotion and stress-regulation.