APERIODIC NEURAL ACTIVITY IN THE POSTERIOR CINGULATE CORTEX REFLECTS CARDIAC SYMPATHOVAGAL BALANCE: A RESTING-STATE MEG-ECG STUDY

This study investigated the relationship between the excitation/inhibition (E/I) balance in the brain using the aperiodic exponent (1/f slope) of the neural power spectrum and cardiac autonomic regulation. Although the brain and autonomic systems are closely integrated, the specific cortical neurophysiological markers reflecting these interactions remain to be fully elucidated.We recorded five minutes of resting-state magnetoencephalography (MEG) and electrocardiography (ECG) simultaneously in 128 healthy young adults. The LF/HF ratio was calculated from the ECG as an index of sympathovagal balance. Using individual structural MRI and the Desikan-Killiany atlas, MEG data were source-localized to extract the aperiodic exponent from each brain region.
Correlation analyses with FDR correction revealed that the aperiodic exponents in the bilateral posterior cingulate cortex (PCC) were significantly and positively correlated with the LF/HF ratio. Notably, this relationship was spatially specific to the PCC and was not observed in other regions.
The PCC is a critical hub within the default mode network and a key component of the Central Autonomic Network (CAN), which plays a vital role in integrating interoceptive information and modulating autonomic output. Our findings indicate that a higher aperiodic exponent in the PCC, which may reflect a shift toward excitatory signalling, is associated with greater sympathetic dominance. These results demonstrate that regional aperiodic neural activity serves as a robust neurophysiological marker of central autonomic control, providing new insights into the cortical mechanisms underlying brain-heart interactions in humans.