Relation of autonomic measures to the Default Mode Network

Respiration and heart rate related variations have very often been described as nuisance factors, confounding the hemodynamic response in the brain (BOLD signal). Recently, it has been argued that physiological signals should not necessarily be treated as artifacts. These signals might be meaningful for investigating brain networks for physiological control. The default mode network (DMN) is a resting state network containing the ventromedial prefrontal cortex and posterior cingulate cortex as core regions. Both regions are known to be part of central autonomic regulation. The presentation will firstly describe the different methodological approaches to relate individual cardiac parameters and BOLD signal during resting state in healthy subjects with significantly different heart rates. The involvement of both regions in cardiac autonomic regulation will be shown. Furthermore, our main goal was to clarify neural mechanisms underlying autonomic dysregulations in patients with Major Depression (MDD) by comparing two patient groups in the resting state condition with respect to different antidepressant medication. In this analysis, the methods derived from the study with healthy controls are applied. We will show in patients with MDD how varying cardiac parameter impact BOLD signal fluctuation in brain regions of the DMN.