Estimation of the cortico-cortical and brain-heart functional coupling with directed transfer function and corrected conditional entropy

The brain activity involved mental stress can increase the risk of sudden cardiac death in patients with organic and ischemic heart disease. Thus, the interaction between the senior nerve and autonomic nerve has recently been given more attention. The purpose of this study was to analyze the cortico-cortical functional coupling and direction of information flow between the brain and heart during a mental arithmetic (MA) task. Forty-three healthy male volunteer participated in the study. Functional coupling patterns of cerebral cortex and heart activity were determined by directed transfer function (DTF) and corrected conditional entropy (CCE). The experimental results showed that sympathetic activity increased, parasympathetic activity and heart rate variability (HRV) decreased, and the heart rate increased during the was quickened by MA task. Furthermore, a reciprocal pattern was observed in the changes of the autonomic nervous system. Meanwhile, cortico-cortical functional coupling was stronger during the MA task. Activity directed to post-central areas of brain and heart localized to the C4 and Cz regions. Our findings suggest that a stress-inducing mental task may cause an increase in the coupling of brain regions and an increase in heart rate though the increase of sympathetic activity.