The brain-heart-gut connection: targeted modulation of the frontal-vagal network for the personalization of non-invasive brain stimulation

Zusammenfassung der Studie

Depression often occurs alongside cardiovascular and gastrointestinal symptoms, highlighting the importance of the brain-heart-gut axis in pathophysiology and treatment. Studies show that central structures in the depression network, such as the dorsolateral prefrontal cortex (DLPFC) and the subgenual anterior cingulate cortex (sgACC), overlap with areas involved in autonomic control, the vagus nerve. Although repetitive transcranial magnetic stimulation (rTMS) of the DLPFC is an established treatment method, optimal targeting remains a challenge. Personalized stimulation based on the connectivity between DLPFC and sgACC may improve treatment success but has so far been only limitedly applicable in clinical settings. rTMS-induced brain-heart coupling (HBC) offers a new approach to determine the target based on heart rate responses. The aim of this project is to personalize HBC to optimize targeting of the DLPFC and investigate further indicators of the frontal-vagal network. In study arm 1, we use a new frontal mapping technique to identify the personalized “Grid-Spot” that elicits the strongest HBC in healthy individuals. We compare the effects of a 10Hz “Dash” protocol over the “Grid-Spot” with the conventional “Beam-F3” method and a control region (Cz), while measuring additional parameters of the autonomic nervous system (ANS) such as gut motility, pupil dilation, and electrodermal activity. This methodology will also be extended to the application of high-definition transcranial direct current stimulation (HD-tDCS). We investigate the effects of anodic versus sham HD-tDCS over the HBC-based “Grid-Spot” on ANS parameters and compare these with the rTMS effects. In study arm 2, we repeat the rTMS experiments from arm 1 in individuals with increased depressive and ANS symptomatology.

(BASEC)

Untersuchte Intervention

TMS: Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation method, where targeted magnetic field pulses can modulate neuronal activity in specific brain areas. The aim of this study is to investigate the coupling between the brain and the heart to determine an individualized stimulation point above the dorsolateral prefrontal cortex. This intervention will be applied in a total of 6 sessions. The first session serves to localize the stimulation point and determine the stimulation intensity. In the following three sessions, this point and two other points will be stimulated for 18.75 minutes, and their effects on the heart and other organs will be examined. The order of sessions will be random.

TDCS: Transcranial direct current stimulation is another non-invasive method of brain stimulation, where the application of electric current to the head induces a change in neuronal activity in the underlying brain areas. In two sessions, stimulation will be applied for 18.75 minutes over the individual stimulation point. One session will serve as a control intervention, where no real stimulation occurs. Neither you nor the study leaders know the order of the protocol (random). Following the 18.75-minute tDCS stimulation, TMS will again be applied for 4 minutes to investigate the effects on brain-heart coupling.

(BASEC)

Untersuchte Krankheit(en)

Participants with gastrointestinal and concurrent depressive symptoms (Arm 2), as well as healthy subjects (Arm 1)

(BASEC)

Sponsor

University Hospital of Old Age Psychiatry and Psychotherapy (UPD)

(BASEC)