@article{D'AgostiniBurgerFranssenetal.2021,
  author    = {D'Agostini, Martina and Burger, Andreas M. and Franssen, Mathijs and Claes, Nathalie and Weymar, Mathias and Leupoldt, Andreas von and Van Diest, Ilse},
  title     = {Effects of transcutaneous auricular vagus nerve stimulation on reversal learning, tonic pupil size, salivary alpha-amylase, and cortisol},
  series = {Psychophysiology : journal of the Society for Psychophysiological Research},
  volume    = {58},
  journal   = {Psychophysiology : journal of the Society for Psychophysiological Research},
  number    = {10},
  publisher = {Wiley-Blackwell},
  address   = {Malden, Mass. [u.a.]},
  issn      = {1469-8986},
  doi       = {10.1111/psyp.13885},
  pages     = {20},
  year      = {2021},
  abstract  = {This study investigated whether transcutaneous auricular vagus nerve stimulation (taVNS) enhances reversal learning and augments noradrenergic biomarkers (i.e., pupil size, cortisol, and salivary alpha-amylase [sAA]). We also explored the effect of taVNS on respiratory rate and cardiac vagal activity (CVA). Seventy-one participants received stimulation of either the cymba concha (taVNS) or the earlobe (sham) of the left ear. After learning a series of cue-outcome associations, the stimulation was applied before and throughout a reversal phase in which cue-outcome associations were changed for some (reversal), but not for other (distractor) cues. Tonic pupil size, salivary cortisol, sAA, respiratory rate, and CVA were assessed at different time points. Contrary to our hypothesis, taVNS was not associated with an overall improvement in performance on the reversal task. Compared to sham, the taVNS group performed worse for distractor than reversal cues. taVNS did not increase tonic pupil size and sAA. Only post hoc analyses indicated that the cortisol decline was steeper in the sham compared to the taVNS group. Exploratory analyses showed that taVNS decreased respiratory rate but did not affect CVA. The weak and unexpected effects found in this study might relate to the lack of parameters optimization for taVNS and invite to further investigate the effect of taVNS on cortisol and respiratory rate.},
  language  = {en}
}
@misc{GiraudierVenturaBortBurgeretal.2022,
  author    = {Giraudier, Manon and Ventura-Bort, Carlos and Burger, Andreas M. and Claes, Nathalie and D'Agostini, Martina and Fischer, Rico and Franssen, Mathijs and Kaess, Michael and Koenig, Julian and Liepelt, Roman and Nieuwenhuis, Sander and Sommer, Aldo and Usichenko, Taras and Van Diest, Ilse and von Leupoldt, Andreas and Warren, Christopher Michael and Weymar, Mathias},
  title     = {Evidence for a modulating effect of transcutaneous auricular vagus nerve stimulation (taVNS) on salivary alpha-amylase as indirect noradrenergic marker: A pooled mega-analysis},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {808},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-57766},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-577668},
  pages     = {1378 -- 1388},
  year      = {2022},
  abstract  = {Background Non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) has received tremendous attention as a potential neuromodulator of cognitive and affective functions, which likely exerts its effects via activation of the locus coeruleus-noradrenaline (LC-NA) system. Reliable effects of taVNS on markers of LC-NA system activity, however, have not been demonstrated yet. Methods The aim of the present study was to overcome previous limitations by pooling raw data from a large sample of ten taVNS studies (371 healthy participants) that collected salivary alpha-amylase (sAA) as a potential marker of central NA release. Results While a meta-analytic approach using summary statistics did not yield any significant effects, linear mixed model analyses showed that afferent stimulation of the vagus nerve via taVNS increased sAA levels compared to sham stimulation (b = 0.16, SE = 0.05, p = 0.001). When considering potential confounders of sAA, we further replicated previous findings on the diurnal trajectory of sAA activity. Conclusion(s) Vagal activation via taVNS increases sAA release compared to sham stimulation, which likely substantiates the assumption that taVNS triggers NA release. Moreover, our results highlight the benefits of data pooling and data sharing in order to allow stronger conclusions in research.},
  language  = {en}
}
@article{GiraudierVenturaBortBurgeretal.2022,
  author    = {Giraudier, Manon and Ventura-Bort, Carlos and Burger, Andreas M. and Claes, Nathalie and D'Agostini, Martina and Fischer, Rico and Franssen, Mathijs and Kaess, Michael and Koenig, Julian and Liepelt, Roman and Nieuwenhuis, Sander and Sommer, Aldo and Usichenko, Taras and Van Diest, Ilse and von Leupoldt, Andreas and Warren, Christopher Michael and Weymar, Mathias},
  title     = {Evidence for a modulating effect of transcutaneous auricular vagus nerve stimulation (taVNS) on salivary alpha-amylase as indirect noradrenergic marker: A pooled mega-analysis},
  series = {Brain Stimulation},
  volume    = {15},
  journal   = {Brain Stimulation},
  edition   = {6},
  publisher = {Elsevier},
  address   = {New York, NY, USA},
  issn      = {1876-4754},
  doi       = {10.1016/j.brs.2022.09.009},
  pages     = {1378 -- 1388},
  year      = {2022},
  abstract  = {Background Non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) has received tremendous attention as a potential neuromodulator of cognitive and affective functions, which likely exerts its effects via activation of the locus coeruleus-noradrenaline (LC-NA) system. Reliable effects of taVNS on markers of LC-NA system activity, however, have not been demonstrated yet. Methods The aim of the present study was to overcome previous limitations by pooling raw data from a large sample of ten taVNS studies (371 healthy participants) that collected salivary alpha-amylase (sAA) as a potential marker of central NA release. Results While a meta-analytic approach using summary statistics did not yield any significant effects, linear mixed model analyses showed that afferent stimulation of the vagus nerve via taVNS increased sAA levels compared to sham stimulation (b = 0.16, SE = 0.05, p = 0.001). When considering potential confounders of sAA, we further replicated previous findings on the diurnal trajectory of sAA activity. Conclusion(s) Vagal activation via taVNS increases sAA release compared to sham stimulation, which likely substantiates the assumption that taVNS triggers NA release. Moreover, our results highlight the benefits of data pooling and data sharing in order to allow stronger conclusions in research.},
  language  = {en}
}