Identify the physiological mechanism underlying tcVNS-related behavioral effects

Determine whether the behavioral effects of momentary transcutaneous cervical vagus nerve stimulation are mediated by increased parasympathetic activity.

Background

Momentary tcVNS was associated with lower food intake, slower eating, and reduced heart rate, but the study found no significant condition-related differences in RMSSD or high-frequency heart-rate variability. Because these measures provided mixed evidence of autonomic engagement, the authors explicitly state that the available data cannot identify whether increased parasympathetic activity mediated the observed behavioral changes. Resolving this question would clarify the physiological pathway linking cervical vagus nerve stimulation to eating behavior.

References

We therefore cannot determine from these data whether the behavioral effects were mediated by increased parasympathetic activity.

— AppetiteCheck: Feasibility of Momentary Vagus Nerve Stimulation as an Implicit Intervention for Eating Behavior  (2609.09700 - Gemicioglu et al., 9 Sep 2026) in Section “Discussion,” subsection “Feasibility and Effectiveness of Momentary tcVNS”