AUTHOR=Obst Martina A. , Heldmann Marcus , Alicart Helena , Tittgemeyer Marc , Münte Thomas F. 

TITLE=Effect of Short-Term Transcutaneous Vagus Nerve Stimulation (tVNS) on Brain Processing of Food Cues: An Electrophysiological Study

JOURNAL=Frontiers in Human Neuroscience

VOLUME=Volume 14 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2020.00206

DOI=10.3389/fnhum.2020.00206

ISSN=1662-5161

ABSTRACT=Background
The vagus nerve plays an important role in the regulation of food intake. Modulating vagal activity via electrical stimulation (VNS) in patients and animal studies caused changes in food intake, energy metabolism, and body weight. However, the moderating impact of cognitive processes on VNS effects on eating behavior, has not been investigated so far.
Hypothesis
We hypothesized that transcutaneous VNS (tVNS) affects food intake by altering cognitive functions relevant to the processing of food-related information.
Methods
Using a repeated measurement design, we applied tVNS and a sham stimulation for 2h on two different days in normal-weight subjects. We recorded standard scalp EEG while subjects watched food and object pictures presented in an oddball-task. We analyzed the event-related potentials (ERPs) P1, P2, N2, and LPP, and also examined the amount of consumed food and eating duration in a free-choice test meal.
Results
Significant differences between stimulations were observed for the P1, P2, and N2 amplitudes. However, we found no tVNS dependent modulation of food intake nor a specific food-related stimulation effect on the ERPs. Further analyses revealed a negative relationship between P2-amplitude and food intake for the sham stimulation. Significant effects are additionally confirmed by Bayesian statistics.
Conclusion 
Our study demonstrates tVNS’ impact on visual processing. Since the effects were similar between food and object stimuli, a general effect on visual perceptual processing can be assumed. More detailed investigations of these effects and their relationship with food intake and metabolism seem reasonable for future studies.