15:00 - 16:30
Tue-P2-Poster II-2
Tue-Poster II-2
Room: P2
WITHDRAWN Transcutaneous vagus nerve stimulation in humans induces pupil dilation and attenuates alpha oscillations: a replication study WITHDRAWN
Tue-P2-Poster II-202
Presented by: Franz Wurm
Franz Wurm 1, 2, Beth Lloyd 1, 2, Sander Nieuwenhuis 1, 2
1 Leiden University, The Netherlands, 2 Leiden Institute for Brain and Cognition, The Netherlands
Transcutaneous vagus nerve stimulation (tVNS) has emerged as a promising brain stimulation method for the treatment of various neurological and psychiatric conditions such as pharmaco-resistant epilepsy and depression. As a non-invasive alternative to vagus nerve stimulation, its clinical efficacy is hypothesized to work via modulations of the locus-coeruleus/noradrenaline neuromodulation system. Although some experimental studies suggest tVNS-induced changes in physiological and behavioral markers related to noradrenergic activity, robust and consistent findings are necessary to deepen our understanding of its working principles. The goal of the present study is to further elucidate the mechanistic underpinnings, by replicating a recent study which showed a direct relationship between tVNS stimulation and noradrenergic biomarkers, namely pupil dilation and electroencephalography (EEG) alpha oscillations. Using short bursts (3.4 s), the previous study found that pupil size increased and alpha power decreased for tVNS compared to sham stimulation. On the one hand, we show increased pupil size following the onset of tVNS stimulation compared to sham stimulation, replicating the recently published findings. On the other hand, we did not observe an attenuation of alpha oscillations for tVNS compared to sham but rather an overall increase in alpha power irrespective of condition, conflicting with previous findings. These inconsistent results put into question the underlying mechanisms for the efficacy of tVNS on locus-coeruleus/noradrenaline neuromodulation. We provide an in-depth discussion of the possible reasons for the partially reproducible findings.
Keywords: replication, transcutaneous vagus nerve stimulation, noradrenaline, pupillometry, EEG