@article{FischerVenturaBortHammetal.2018,
  author    = {Fischer, Rico and Ventura-Bort, Carlos and Hamm, Alfons O. and Weymar, Mathias},
  title     = {Transcutaneous vagus nerve stimulation (tVNS) enhances conflict-triggered adjustment of cognitive control},
  series = {Cognitive, affective, \& behavioral neuroscience : a journal of the Psychonomic Society},
  volume    = {18},
  journal   = {Cognitive, affective, \& behavioral neuroscience : a journal of the Psychonomic Society},
  number    = {4},
  publisher = {Springer},
  address   = {New York},
  issn      = {1530-7026},
  doi       = {10.3758/s13415-018-0596-2},
  pages     = {680 -- 693},
  year      = {2018},
  abstract  = {Response conflicts play a prominent role in the flexible adaptation of behavior as they represent context-signals that indicate the necessity for the recruitment of cognitive control. Previous studies have highlighted the functional roles of the affectively aversive and arousing quality of the conflict signal in triggering the adaptation process. To further test this potential link with arousal, participants performed a response conflict task in two separate sessions with either transcutaneous vagus nerve stimulation (tVNS), which is assumed to activate the locus coeruleus-noradrenaline (LC-NE) system, or with neutral sham stimulation. In both sessions the N2 and P3 event-related potentials (ERP) were assessed. In line with previous findings, conflict interference, the N2 and P3 amplitude were reduced after conflict. Most importantly, this adaptation to conflict was enhanced under tVNS compared to sham stimulation for conflict interference and the N2 amplitude. No effect of tVNS on the P3 component was found. These findings suggest that tVNS increases behavioral and electrophysiological markers of adaptation to conflict. Results are discussed in the context of the potentially underlying LC-NE and other neuromodulatory (e.g., GABA) systems. The present findings add important pieces to the understanding of the neurophysiological mechanisms of conflict-triggered adjustment of cognitive control.},
  language  = {en}
}
@misc{VenturaBortWirknerGenheimeretal.2018,
  author    = {Ventura-Bort, Carlos and Wirkner, Janine and Genheimer, Hannah and Wendt, Julia and Hamm, Alfons O. and Weymar, Mathias},
  title     = {Effects of Transcutaneous Vagus Nerve Stimulation (tVNS) on the P300 and Alpha-Amylase Level},
  series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {473},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419259},
  pages     = {12},
  year      = {2018},
  abstract  = {Recent research suggests that the P3b may be closely related to the activation of the locus coeruleus-norepinephrine (LC-NE) system. To further study the potential association, we applied a novel technique, the non-invasive transcutaneous vagus nerve stimulation (tVNS), which is speculated to increase noradrenaline levels. Using a within-subject cross-over design, 20 healthy participants received continuous tVNS and sham stimulation on two consecutive days (stimulation counterbalanced across participants) while performing a visual oddball task. During stimulation, oval non-targets (standard), normal-head (easy) and rotated-head (difficult) targets, as well as novel stimuli (scenes) were presented. As an indirect marker of noradrenergic activation we also collected salivary alpha-amylase (sAA) before and after stimulation. Results showed larger P3b amplitudes for target, relative to standard stimuli, irrespective of stimulation condition. Exploratory post hoc analyses, however, revealed that, in comparison to standard stimuli, easy (but not difficult) targets produced larger P3b (but not P3a) amplitudes during active tVNS, compared to sham stimulation. For sAA levels, although main analyses did not show differential effects of stimulation, direct testing revealed that tVNS (but not sham stimulation) increased sAA levels after stimulation. Additionally, larger differences between tVNS and sham stimulation in P3b magnitudes for easy targets were associated with larger increase in sAA levels after tVNS, but not after sham stimulation. Despite preliminary evidence for a modulatory influence of tVNS on the P3b, which may be partly mediated by activation of the noradrenergic system, additional research in this field is clearly warranted. Future studies need to clarify whether tVNS also facilitates other processes, such as learning and memory, and whether tVNS can be used as therapeutic tool.},
  language  = {en}
}
@article{VenturaBortWirknerGenheimeretal.2018,
  author    = {Ventura-Bort, Carlos and Wirkner, Janine and Genheimer, Hannah and Wendt, Julia and Hamm, Alfons O. and Weymar, Mathias},
  title     = {Effects of Transcutaneous Vagus Nerve Stimulation (tVNS) on the P300 and Alpha-Amylase Level},
  series = {Frontiers in Human Neuroscience},
  volume    = {12},
  journal   = {Frontiers in Human Neuroscience},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {1662-5161},
  doi       = {10.3389/fnhum.2018.00202},
  pages     = {1 -- 12},
  year      = {2018},
  abstract  = {Recent research suggests that the P3b may be closely related to the activation of the locus coeruleus-norepinephrine (LC-NE) system. To further study the potential association, we applied a novel technique, the non-invasive transcutaneous vagus nerve stimulation (tVNS), which is speculated to increase noradrenaline levels. Using a within-subject cross-over design, 20 healthy participants received continuous tVNS and sham stimulation on two consecutive days (stimulation counterbalanced across participants) while performing a visual oddball task. During stimulation, oval non-targets (standard), normal-head (easy) and rotated-head (difficult) targets, as well as novel stimuli (scenes) were presented. As an indirect marker of noradrenergic activation we also collected salivary alpha-amylase (sAA) before and after stimulation. Results showed larger P3b amplitudes for target, relative to standard stimuli, irrespective of stimulation condition. Exploratory post hoc analyses, however, revealed that, in comparison to standard stimuli, easy (but not difficult) targets produced larger P3b (but not P3a) amplitudes during active tVNS, compared to sham stimulation. For sAA levels, although main analyses did not show differential effects of stimulation, direct testing revealed that tVNS (but not sham stimulation) increased sAA levels after stimulation. Additionally, larger differences between tVNS and sham stimulation in P3b magnitudes for easy targets were associated with larger increase in sAA levels after tVNS, but not after sham stimulation. Despite preliminary evidence for a modulatory influence of tVNS on the P3b, which may be partly mediated by activation of the noradrenergic system, additional research in this field is clearly warranted. Future studies need to clarify whether tVNS also facilitates other processes, such as learning and memory, and whether tVNS can be used as therapeutic tool.},
  language  = {en}
}
@misc{WeymarVenturaBortWirkneretal.2018,
  author    = {Weymar, Mathias and Ventura-Bort, Carlos and Wirkner, Janine and Wendt, Julia and Hamm, Alfons},
  title     = {Effects of Transcutaneous Vagus Nerve Stimulation (TVNS) on unpleasant picture processing and long-term memory},
  series = {Psychophysiology : journal of the Society for Psychophysiological Research},
  volume    = {55},
  journal   = {Psychophysiology : journal of the Society for Psychophysiological Research},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0048-5772},
  pages     = {S18 -- S18},
  year      = {2018},
  language  = {en}
}
@article{WirknerVenturaBortSchulzetal.2018,
  author    = {Wirkner, Janine and Ventura-Bort, Carlos and Schulz, Paul and Hamm, Alfons O. and Weymar, Mathias},
  title     = {Event-related potentials of emotional and neutral memories},
  series = {Psychophysiology : journal of the Society for Psychophysiological Research},
  volume    = {55},
  journal   = {Psychophysiology : journal of the Society for Psychophysiological Research},
  number    = {7},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0048-5772},
  doi       = {10.1111/psyp.13069},
  pages     = {12},
  year      = {2018},
  abstract  = {Previous research found that memory is not only better for emotional information but also for neutral information that has been encoded in the context of an emotional event. In the present ERP study, we investigated two factors that may influence memory for neutral and emotional items: temporal proximity between emotional and neutral items during encoding, and retention interval (immediate vs. delayed). Forty-nine female participants incidentally encoded 36 unpleasant and 108 neutral pictures (36 neutral pictures preceded an unpleasant picture, 36 followed an unpleasant picture, and 36 neutral pictures were preceded and followed by neutral pictures) and participated in a recognition memory task either immediately (N=24) or 1 week (N=25) after encoding. Results showed better memory for emotional pictures relative to neutral pictures. In accordance, enhanced centroparietal old/new differences (500-900 ms) during recognition were observed for unpleasant compared to neutral pictures, most pronounced for the 1-week interval. Picture position effects, however, were only subtle. During encoding, late positive potentials for neutral pictures were slightly lower for neutral pictures following unpleasant ones, but only at trend level. To summarize, we could replicate and extend previous ERP findings showing that emotionally arousing events are better recollected than neutral events, particularly when memory is tested after longer retention intervals. Picture position during encoding, however, had only small effects on elaborative processing and no effects on memory retrieval.},
  language  = {en}
}