The Effect of taVNS and Upper GI Motility

This single-center randomized controlled cross-over trial aims to investigate the effect of transcutaneous auricular vagus nerve stimulation on upper gastrointestinal motility in healthy individuals.

The primary aim of this study is to assess the impact of tVNS on gut motor function, with regards to its potential to induce phase III contractions in the upper GI tract.

Secondary objectives include:

* To study the effect of tVNS on other parameters characterizing upper GI motility such as the number of duodenal phase III contractions, gastric and duodenal phase MMCs, amplitude of antral contractions and motility index * To study the effect of tVNS on plasma levels of motilin and PP * To evaluate the effect of tVNS on parameters related to autonomic outflow, using a Shimmer3 GSR Sensor for heart rate variability and skin conductance. * To compare the results of the measurements of antroduodenal manometry with measurements of Gastric Alimetry

Participants will undergo tVNS (applied to the cymba conchae of the left ear) alternating with sham stimulation (using a non-conducting electrode) in a blinded, pre-randomized fashion, using two 4-hour blocks during an 8-hour fasted antroduodenal manometry recording period. Optionally, participants may simultaneously also undergo body surface gastric mapping using the Gastric Alimetry system.