Transcutaneous Auricular Vagus Nerve Stimulation for Working Memory Enhancement: A Comparative Study of Electrical and Ultrasound Stimulation
Alicia Falcon-Caro, Nicholas Myers, Marcus Kaiser, Hyuk Choi, Jae-Jun Song, JeYoung Jung
Neuromodulation: Technology at the Neural Interface 2026 · 10.1016/j.neurom.2026.08.004
Abstract
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.
Abstract via europepmc.
Exposures
Exposure 1: U-taVNS to right cymba conchae
Target: vagus nerve — “right cymba conchae”
Device: other named manufacturer · NeurGear Inc, Rochester, NY · ZenBud ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 5,300 | ✓✓✓ |
| Pulse duration (ms) | not reportedimplied by duty cycle ÷ PRF: 12.1951 ms (not stated by the paper) | ⚑ |
| Pulse repetition frequency (Hz) | 41 | ✓✓✓ |
| Duty cycle (%) | 50 | ✓✓✓ |
| Sonication duration (s) | 1,800 | ✓✓✓⚑ |
| Free-field pressure (kPa) | 1,030 | ✓✓✓⚑ |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | 0.0405 | ✓✓✓ |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported | |
| Isppa, domain unspecified (W/cm²) | 0.081 | ✓✓✓⚑ |
Single 30 minute session of ultrasound taVNS to the right cymba conchae (41 Hz PRF, 50% duty cycle), before and after which a 3-back task was performed; active and sham sessions at least five days apart, order counterbalanced.
Flags from extraction
n_subjects— 59 were recruited (30 E-taVNS, 29 U-taVNS); the 29 U-taVNS participants received ultrasound, 28 were analysed after one exclusion. Enrolled count given.exposures[0].free_field.pressure_kpa— Stated as 'average intensity (free-field peak pressure) of 1.03 MPa'; wording is confusing.exposures[0].unspecified_domain.isppa_w_cm2— 'Peak mechanical output of 0.081 W/cm2' is not labelled as Isppa or given a domain.exposures[0].timing.sonication_duration_s— 30 minutes of taVNS stated; whether sonication was continuous over that time is not described.exposures[0].in_situ— No in situ value reported; the electrical arm is not an ultrasound exposure and is not recorded.exposures[0].timing.pulse_duration_ms— Pulse duration not stated; not computed from PRF and duty cycle.sham_type— Sham used an identical device delivering no active ultrasound.blinding— Single-blind; blinding checked informally by debrief.