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Distinct Neurophysiological and Psychological Effects of tVNS and Neurofeedback: Insights for EEG-Guided Neuromodulation

Authors :

Seyedeh Zeinab Molaeizadeh¹ Aitor Aritzeta Galan²

1- University of the Basque Country 2- University of the Basque Country

Keywords :

Neurofeedback،Transcutaneous Vagus Nerve Stimulation،Emotion Regulation،Electroencephalogram،Alpha/Theta Ratio

Abstract :

This pilot study investigates the neurophysiological and psychological effects of two emerging non-invasive neuromodulation techniques, transcutaneous vagus nerve stimulation (tVNS) and neurofeedback (NF), in healthy adults. Fifteen participants were allocated to one of three groups: tVNS (applied to the left tragus), NF (Alpha/Theta protocol), or a control group. Each intervention included eight sessions of 30 minutes over a four-week period. Resting-state electroencephalography (EEG) was employed to quantify the alpha/theta power ratio, while psychological outcomes were assessed using the Beck Anxiety Inventory (BAI) and selected subscales of the Millon Clinical Multiaxial Inventory-IV (MCMI-IV). Non-parametric within-group analyses indicated that tVNS significantly increased the alpha/theta ratio (p = 0.042), reflecting a shift toward neurophysiological relaxation. In contrast, NF significantly reduced anxiety (p = 0.042) and depressive symptoms (p = 0.048). No significant effects were found in the control condition. Interestingly, although NF was expected to exert stronger effects on EEG-based biomarkers, it primarily influenced psychological outcomes, whereas tVNS showed more pronounced modulation of neurophysiological indices. These findings highlight distinct mechanisms of action and underscore the potential of tVNS for EEG-guided neuromodulation, motivating future work toward adaptive closed-loop tVNS systems tailored to individual neural oscillatory dynamics.