Comparing Electrical and Ultrasound Transcutaneous Auricular Vagus Nerve Stimulation on Associative Memory
Benjamin J. Griffiths, Ziqi He, Irem Ciftepinar, Hyuk Choi, Jae-Jun Song, Marcus Kaiser, JeYoung Jung
Neuromodulation: Technology at the Neural Interface 2026 · 10.1016/j.neurom.2026.07.001
Abstract
Objectives Associative memory, the ability to bind and retrieve relationships between unrelated elements, is a cornerstone of human cognition and a primary target for neurorehabilitation. Vagus nerve stimulation (VNS) has emerged as a promising method to modulate the locus coeruleus-norepinephrine system and hippocampal-prefrontal circuits essential for memory. However, the comparative efficacy of noninvasive modalities such as electrical transcutaneous VNS (E-taVNS) and the emerging field of ultrasound (U-taVNS) remains poorly understood in the context of active recall. Materials and methods In this study, participants performed a cross-modal video-word associative memory task before and after receiving either E-taVNS or U-taVNS in active and sham conditions. We investigated whether these modalities enhance cued recall accuracy and retrieval reaction time. Results Our results revealed that neither E-taVNS nor U-taVNS significantly improved recall accuracy. However, E-taVNS significantly accelerated response times specifically for correctly recalled items. These findings suggest that although taVNS may not increase the likelihood of recalling associative memories after a brief retention interval, electrical stimulation may enhance the efficiency with which we do so. Conclusions These findings suggest that E-taVNS is a viable tool for facilitating memory processes, although further research is required to optimize ultrasound parameters and validate mechanistic pathways through physiologic monitoring.
Abstract via europepmc.
Exposures
Exposure 1: Ultrasound taVNS (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) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| 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 | |
| Pressure, domain unspecified (kPa) | 1,030 | ✓✓✓⚑ |
| Isppa, domain unspecified (W/cm²) | 0.081 | ✓✓✓⚑ |
Participants received 30 minutes of taVNS per session; each participant completed two sessions (active and sham), scheduled >=5 days apart, with stimulation order counterbalanced. For the sham condition, a dedicated sham device reproduced the same auditory buzzing sound as the active device but delivered no ultrasound output, matching auditory cues between active and sham sessions.
Consistency checks: intensity pressure inconsistent unspecified domain.
Flags from extraction
exposures[0].unspecified_domain.pressure_kpa— The paper reports this as 'an average pressure amplitude of 1.03 MPa', which is unambiguously a pressure value; converted to 1030 kPa.exposures[0].unspecified_domain.isppa_w_cm2— 'A peak mechanical output of 0.081 W/cm2' is not explicitly labelled ISPPA or ISPTA; assigned to ISPPA given the word 'peak', but this is an inference.exposures[0].timing.pulse_duration_ms— Duty cycle (50%) and PRF (41 Hz) are stated but pulse duration is not; not computed per the no-arithmetic rule.exposures[0].free_field— The paper does not state whether the reported pressure/intensity values are free-field or in-situ; recorded under unspecified_domain.sham_type— The U-taVNS sham used a separate 'dedicated sham device' rather than the active transducer powered off; classified as inactive_transducer (no acoustic output) as the closest vocabulary match.