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Stimulation of the vagus nerve enhances communication between the stomach and brain

To summarize: Non-invasive stimulation of the vagus nerve can help strengthen communication between the stomach and brain in minutes.

resource: University of Tübingen

The nervous system receives sensory stimuli, processes them and triggers responses, such as muscle movements or pain sensations. A few years ago, it was discovered that a network in the brain, combined with signals from the stomach, may influence human hunger and satiety.

Now, a research team led by Prof. Nils Kroemer at the University Hospitals Tübingen and Bonn has shown for the first time that non-invasive stimulation of the vagus nerve in the ear can enhance communication between the stomach and the brain within minutes.

The findings are currently published in brain stimulation.

The vagus nerve is responsible for controlling many aspects of human behavior: This cranial nerve connects several important organ systems to the brain, supporting the transmission of endogenous signals.

For example, these facilitate goal-directed food searches by tuning the reward system for food stimulation on an empty stomach. Previous research has shown that the vagus nerve can regulate digestion through the brain. This mechanism is relevant for therapeutic applications because the vagus nerve can be stimulated noninvasively.

Through a new study, a team of Ph.D. Students Sophie Müller and Professor Nils Kroemer have solved the previously unanswered question of how exactly modulation through the brain works.

About research

The team, comprising scientists from the Universities of Tübingen and Bonn as well as the German Institute for Human Nutrition in Potsdam and the German Center for Diabetes Research, studied a total of 31 participants.

They combined stimulation of the vagus nerve in the ear with simultaneous recordings of brain activation via functional magnetic resonance imaging (MRI) and a so-called electrogastrogram.

An electrogastrogram involves placing electrodes on the stomach (similar to an electrocardiogram) to record signals from the digestive tract.

“We have shown for the first time that electrical stimulation enhances the coupling between signals from the stomach and the brain – we can do this in minutes,” says Professor Kroemer.

Kroemer leads a research group at the Department of Psychiatry and Psychotherapy at the University Hospital Tübingen investigating the neurobiological basis of motivation, action and desire (neuroMADLAB) and has been Professor of Medical Psychology at the Department of Psychiatry at the University of Bonn since 2022 Engaged in psychotherapy and psychotherapy.

The results of the study are clear at a glance

The team stimulated the vagus nerve in the ear and, under control conditions, other nerves in the participants’ ears.

The vagus nerve is responsible for controlling many aspects of human behavior.Image is in the public domain

“We observed that vagal stimulation increased coupling to gastric signals from the brainstem and midbrain,” explains Professor Kroemer.

“These regions are important because they are the first targets of the vagus nerve in the brain. Changes in the midbrain may have modulated our actions.”

In addition, the researchers found that coupling to the stomach increased throughout the brain, particularly in areas that were already communicating more strongly with the stomach prior to stimulation. Coupling changes between the stomach and brain can occur almost instantaneously and spread rapidly.

The findings could lead to new treatment options. For example, Professor Kroemer’s group is currently conducting further research into possible applications for depression, where changes in communication between the body and the brain have been identified as a key factor.

see also

This shows the outlines of the mother and baby

Likewise, in obesity and eating disorders, stimulation of the vagus nerve can help affected individuals restore perception of bodily signals in the future.

About this Brain Stimulation Research News

author: News office
resource: University of Tübingen
touch: Press Office – University of Tübingen
picture: Image is in the public domain

Original research: Open access.
“Vagus nerve stimulation increases gastro-brain coupling through vagal afferent pathways”, Müller, Sophie, et al. brain stimulation


Abstract

Vagus nerve stimulation increases gastric-brain coupling through vagal afferent pathways

background

Maintaining energy homeostasis is critical and supported by vagal signaling between the digestive organs and the brain. Previous studies have established a gastric network in the brain that is phase-synchronized with gastric rhythms, but lacked tools to interfere with its function.

objective

To assess whether gastro-brain coupling can be dramatically increased by non-invasive stimulation of vagal afferent projections to the brain.

method

Using a single-blind randomized crossover design, we investigated the effect of acute right-sided transcutaneous vagus nerve stimulation (taVNS) versus sham stimulation on gastro-brain coupling.

result

Consistent with preclinical studies, taVNS increased gastro-brain coupling in the nucleus tractus solitarius (NTS) and midbrain, while promoting whole-brain coupling. Crucially, in the cortex, taVNS-induced coupling changes occurred predominantly in cross-modal regions and were associated with changes in starvation levels as an indicator of subjective metabolic status.

in conclusion

taVNS increases gastro-brain coupling through the NTS-midbrain pathway, which signals gut-induced reward, suggesting that communication between the brain and body is efficiently regulated by vagal signaling. These insights may help us better understand the role of vagal afferents in coordinating gastric network recruitment, which may pave the way for new neuromodulation treatments.

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