Estimation of brain activity sources of sympathovagal dynamics.

Characterizing source brain activity in relation to peripheral neural-autonomic function is crucial in neuroscience research. Despite recent advances for estimating brain-heart interplay (BHI), the specific intracortical sources underlying this interaction remain poorly understood, and especially a non-invasive model to localize the brain source of cardiac autonomic functions is lacking. In an effort to estimate the joint intrinsic activity of central and autonomic systems, this study extends canonical EEG source localization by introducing a framework for brain source reconstruction of sympathovagal and vagal components. The proposed method integrates EEG and ECG-derived heart rate variability series within a low-resolution electromagnetic tomography framework and was validated using data from 26 healthy subjects undergoing a well-known sympathovagal elicitation paradigm - the cold pressor test - compared to the resting state. Experimental results demonstrate that accounting for heartbeat dynamics significantly alters source activation patterns, aligning coherently with current knowledge on central autonomic networks and BHI dynamics. The proposed method opens new avenues for research into the neural sources of autonomic functions.