Field: Neuroscience › NeurologyType: Couldn't replicate a published resultArea: neuromodulationTarget: Transcutaneous auricular vagus nerve stimulation (taVNS)Stage: replication
Hypothesis
Short 3.4-second bursts of taVNS would both widen the pupil and lower EEG alpha power, as Sharon et al. (2021) reported, indicating noradrenergic activation.
What failed
In a sham-controlled crossover with 29 volunteers using the original analysis scripts, pupil dilation replicated (p = .009, BF = 7.45) but the drop in EEG alpha power did not (p = .37; BF10 = 0.28, about four times more likely under the null).
Broken assumption
Brief taVNS reliably suppresses EEG alpha as a cortical readout of noradrenergic activation.
Why
The abstract offers no mechanism for the missing alpha effect; it calls for more direct replications of influential taVNS studies.
From the published paper: Lloyd et al. Brain stimulation, 2023. ↗CC BY