Vagus Nerve Stimulation At The Ear Strengthens Communication Between Stomach and Brain

The vagus nerve is considered one of the most complex cranial nerves in our central nervous system because of its central role in human behavior, connecting various bodily signals with the brain in a "super highway" of connectivity. This nerve is responsible for regulating internal organ functions such as heart rate, respiratory rate, and digestion. 

For example, the vagus nerve signals to the brain when the stomach is empty to help support the directive search for food to eat. The nerve plays a central role in digestive processes and, therefore, the communication relayed via this nerve pathway has important implications for human health. 

"We showed for the first time that electrical stimulation strengthens the coupling between signals from the stomach and the brain – and we can do it within a few minutes," said Professor Nils Kroemer in a statement. 

The researchers investigated 31 subjects who underwent vagus nerve stimulation at the ear while simultaneously receiving functional magnetic resonance imaging (fMRI) to record brain activation. At the same time, electrogastrogram recordings were made over their stomach regions to record signals from the digestive tract. They found that vagus nerve stimulation increased coupling between the stomach and brain and it was widespread, especially in areas of the brain that normally connect more strongly with the stomach before the stimulation was applied.

"We observed that vagus nerve stimulation increased coupling with signals from the stomach in the brainstem and midbrain," explained Kroemer. "These regions are important because they are the first targets of the vagus nerve in the brain. Changes in the midbrain may already mediate our actions." 

The researchers say the new discovery could open up new therapeutic avenues for depression, obesity, and eating disorders in the future. The findings are reported in the journal Brain Stimulation.