Transcutaneous Auricular Vagus Nerve Stimulation for Working Memory Enhancement: A Comparative Study of Electrical and Ultrasound Stimulation.

OBJECTIVES

Transcutaneous auricular vagus nerve stimulation (taVNS) is a noninvasive neuromodulation technique that has shown potential to enhance cognitive function, including working memory. This study investigated the acute effects of both electrical taVNS (E-taVNS) and ultrasound taVNS (U-taVNS) modalities on working memory by using a 3-back task in healthy young adults. We hypothesized that active taVNS would enhance working memory performance compared with sham and that both stimulation modalities would engage similar neuromodulatory mechanisms.

MATERIALS AND

METHODS

Fifty-nine participants underwent a single-blind, sham-controlled, within-subject design study, with working memory performance assessed using a 3-back task before and after stimulation. Primary performance measures included overall accuracy and sensitivity index d', whereas secondary measures included correct rejection rate, hit accuracy, and average hit reaction time. Statistical analyses evaluated pre- and post-stimulation changes across active and sham conditions for both modalities. Additionally, linear regression and Pearson correlations analyzed the relationship between affective traits and stimulation responsiveness.

RESULTS

Active taVNS significantly enhanced working memory performance from pre- to post-stimulation. This enhancement was characterized by a significant improvement in sensitivity (measured by d'). The treatment effect did not differ significantly between U-taVNS and E-taVNS, as indicated by a nonsignificant three-way interaction, although the CIs remained compatible with potentially meaningful modality-specific differences. Baseline anxiety levels significantly predicted individual responsiveness to taVNS. In terms of tolerability, a higher proportion of participants receiving E-taVNS reported skin irritation compared with those receiving U-taVNS.

CONCLUSIONS

taVNS can acutely enhance working memory performance, and U-taVNS may offer a comparable, better-tolerated alternative to E-taVNS. Our findings highlight the potential of taVNS to support memory function, while showing the importance of further research to clarify modality-specific effects and to optimize stimulation parameters.