Exploring the Alleviating Effects of taVNS on Negative Emotions: An EEG Study

Emotion inhibitory control is a key executive function of the human brain, which regulates behavior by suppressing inappropriate responses. It plays an integral part in alleviating negative emotions, improving mood, and preventing depression. Transcutaneous auricular vagus nerve stimulation (taVNS) has been proved to enhance behavioral control, potentially suppressing negative emotions or facilitating their reduction in healthy individuals. However, the neurocomputational mechanisms underlying taVNS-induced neuroenhancement remain unclear. In this work, a portable electroencephalography (EEG) acquisition and stimulation device is designed to collect eight-channel EEG signals and deliver taVNS to both sides of ears. Then, we design a protocol that successfully induced negative emotions in healthy subjects. Next, we conduct a sham-controlled experiment, involving 28 healthy subjects, to explore the changes in EEG of negative emotions under taVNS. Finally, we primarily analyze the power spectrum density (PSD) of EEG signals and the functional connectivity network of the brain, based on the phase locking value (PLV), to assess the effect of taVNS on neural activity induced by negative emotions. The results of the experiment reveal that taVNS is a promising method for enhancing emotional inhibitory control by reducing PSD in the alpha band and enhancing PLV within prefrontal inhibitory control networks. In addition, differences in graph theory parameters between the Sham and taVNS conditions indicate that taVNS helps regulate negative emotions. In conclusion, this study demonstrates that taVNS enhances inhibitory control and reveals its neurocomputational mechanisms of EEG in healthy individuals during the development of negative emotions. And results indicate that taVNS could serve as a promising neuromodulation therapy for psychiatric disorders and individuals with depression or emotional distress.