Immediate modulatory effects of transcutaneous auricular vagus nerve stimulation in healthy males: A multi-bands resting-state fMRI study.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a noninvasive neuromodulation technique that shows promise in treating disorders such as depression and insomnia. Previous studies have mainly focused on disease-specific populations, making it difficult to distinguish taVNS-induced neural changes from disease-related confounding factors. To investigate its immediate effects, we recruited 24 healthy males and randomly assigned them to a taVNS group (n = 12) or a sham group (n = 12). The taVNS group received 30 min of stimulation, while the sham group received a brief initial stimulation (<15 s) followed by device placement without power. Resting-state functional magnetic resonance imaging (rs-fMRI) scans were acquired pre-taVNS and post-taVNS. The paired sample t-test in the taVNS group showed reduced regional homogeneity (ReHo) in the left precentral gyrus (Precentral_L) (conventional frequency band) and left postcentral gyrus (Postcentral_L) (slow 4 frequency band). Functional connectivity (FC) analysis based on peak ReHo coordinates showed that the FC between Precentral_L and the right fusiform gyrus (Fusiform_R) (conventional band and slow band 4) and the right calcarine cortex (Calcarine_R) (slow band 5) was weakened, and the FC between the Postcentral_L and the Postcentral_L (conventional band), the Fusiform_R and the left cuneus (Cuneus_L) (slow band 4), and the Postcentral_L (slow band 5) was weakened. No significant differences were observed between the groups. These findings suggest that taVNS modulates neural activity in different frequency bands in healthy males, providing insights into its regulatory mechanisms and facilitating future applications in cognitive enhancement and targeted brain stimulation.