The Vagus Nerve as a Gateway to Body Ownership: <scp>taVNS</scp> Reduces Susceptibility to a Virtual Version of the Cardiac and Tactile Rubber Hand Illusion

Transcutaneous auricular vagus nerve stimulation (taVNS) has been shown to influence cognitive and emotional function and enhance interoceptive awareness. This study investigates if taVNS effects extend to the experience of body ownership, as measured via susceptibility to the rubber hand illusion (RHI) in a virtual reality setting. The experiment involved 27 participants who underwent real and sham stimulation in two separate sessions while experiencing synchronous or asynchronous visuo-cardiac and visuo-tactile feedback on a virtual arm in place of their own. Results indicated that active compared to sham taVNS decreased sensitivity to the illusion in both cardiac and tactile trials. Specifically, a greater proprioceptive drift difference (PDD) toward the rubber hand was observed for synchronous compared to asynchronous trials only during sham (t(26) = -4.58, p_bonf < 0.001) but not during active (p_bonf = 1.00) stimulation. A similar pattern was also observed for subjective ownership, where synchronous trials led to greater subjective ownership than asynchronous trials only during sham (t(26) = -3.52, p_bonf = 0.010) but not during active (p_bonf = 1.00) stimulation. These findings suggest that stimulation might enhance body ownership, making individuals more attuned to their real bodily signals and less susceptible to bodily illusions. Additionally, physiological measures such as heart rate (HR), heart rate variability (HRV), and skin sympathetic nervous activity (SKNA) were assessed to explore the autonomic effects of taVNS. We observed a decrease in HR during active stimulation (t(26) = 4.30, p_bonf < 0.001), and an increase in SKNA during both sham (t(26) = -4.40, p_bonf < 0.001) and active stimulation (t(26) = -4.85, p_bonf < 0.002). These findings contribute to the understanding of the vagus nerve's role in integrating visceral and somatosensory signals, with implications for clinical applications in conditions characterized by altered interoception and body ownership.