40 Hz transcutaneous auricular vagus nerve stimulation enhances verbal free recall in healthy adults by modulating frontal theta oscillations.
Yinpei Luo, Shu Yin, Liping Chen et al.
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In 30 seconds
This randomized, single-blind, sham-controlled, three-arm trial examined whether 20 Hz or 40 Hz transcutaneous auricular vagus nerve stimulation (taVNS) affected verbal free recall and resting-state EEG theta activity in healthy young adults. Participants receiving 40 Hz stimulation had better free recall than those receiving sham or 20 Hz stimulation. The 40 Hz intervention also produced an immediate increase in relative theta power, particularly frontally, which gradually declined over time. Frontal theta activity and stimulation-related theta changes were positively correlated with recall performance; exploratory Bayesian mediation analysis supported a theta-dependent model.
Key findings
- The 40 Hz taVNS group showed better free recall than both the sham and 20 Hz groups.
- 40 Hz taVNS immediately increased relative theta power, particularly in frontal regions, with the effect gradually decreasing over time.
- Frontal theta activity and stimulation-induced theta changes were positively correlated with free recall performance.
Why it matters
The findings link a specific taVNS frequency with transient changes in frontal theta activity and verbal recall, suggesting a possible neural mechanism for memory modulation. They add preliminary evidence that stimulation frequency may matter when studying non-invasive neuromodulation and memory. The results are from healthy young adults and do not establish benefit for people with memory impairment.
What to keep in mind
The study involved healthy young adults, and the authors characterize the evidence as preliminary. The mediation analysis was exploratory.