@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} } @article{VenturaBortWirknerDolcosetal.2019, author = {Ventura-Bort, Carlos and Wirkner, Janine and Dolcos, Florin and Wendt, Julia and Hamm, Alfons O. and Weymar, Mathias}, title = {Enhanced spontaneous retrieval of cues from emotional events: an ERP study}, series = {Biological psychology}, volume = {148}, journal = {Biological psychology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0301-0511}, doi = {10.1016/j.biopsycho.2019.107742}, pages = {7}, year = {2019}, abstract = {Recent evidence points to enhanced episodic memory retrieval not only for emotional items but also for neutral information encoded in emotional contexts. However, prior research only tested instructed explicit recognition, and hence here we investigated whether memory retrieval is also heightened for cues from emotional contexts when retrieval is not explicitly probed. During the first session of a two-session experiment, neutral objects were presented on different background scenes varying in emotional and neutral contents. One week later, objects were presented again (with no background) intermixed with novel objects. In both sessions, participants were instructed to attentively watch the stimuli (free viewing procedure), and during the second session, ERPs were also collected to measure the ERP Old/New effect, an electrophysiological correlate of episodic memory retrieval. Analyses were performed using cluster-based permutation tests in order to identify reliable spatiotemporal ERP differences. Based on this approach, old relative to new objects, were associated with larger ERP positivity in an early (364-744 ms) and late time window (760-1148 ms) over distinct central electrode clusters. Interestingly, significant late ERP Old/New differences were only observed for objects previously encoded with emotional, but not neutral scenes (504 to 1144 ms). Because these ERP differences were observed in a non-instructed retrieval context, our results indicate that long-term, spontaneous retrieval for neutral objects, is particularly heightened if encoded within emotionally salient contextual information. These findings may assist in understanding mechanisms underlying spontaneous retrieval of emotional associates and the utility of ERPs to study maladaptive involuntary memories in trauma- and stress-related disorders.}, language = {en} } @article{VenturaBortWirknerWendtetal.2021, author = {Ventura-Bort, Carlos and Wirkner, Janine and Wendt, Julia and Hamm, Alfons O. and Weymar, Mathias}, title = {Establishment of emotional memories is mediated by vagal nerve activation}, series = {The journal of neuroscience : the official journal of the Society for Neuroscience}, volume = {41}, journal = {The journal of neuroscience : the official journal of the Society for Neuroscience}, number = {36}, publisher = {Society for Neuroscience}, address = {Washington, DC}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.2329-20.2021}, pages = {7636 -- 7648}, year = {2021}, abstract = {Emotional memories are better remembered than neutral ones, but the mechanisms leading to this memory bias are not well under-stood in humans yet. Based on animal research, it is suggested that the memory-enhancing effect of emotion is based on central nor-adrenergic release, which is triggered by afferent vagal nerve activation. To test the causal link between vagus nerve activation and emotional memory in humans, we applied continuous noninvasive transcutaneous auricular vagus nerve stimulation (taVNS) during exposure to emotional arousing and neutral scenes and tested subsequent, long-term recognition memory after 1 week. We found that taVNS, compared with sham, increased recollection-based memory performance for emotional, but not neutral, material. These findings were complemented by larger recollection-related brain potentials (parietal ERP Old/New effect) during retrieval of emotional scenes encoded under taVNS, compared with sham. Furthermore, brain potentials recorded during encoding also revealed that taVNS facilitated early attentional discrimination between emotional and neutral scenes. Extending animal research, our behavioral and neu-ral findings confirm a modulatory influence of the vagus nerve in emotional memory formation in humans.}, language = {en} } @misc{WeymarVenturaBortWirkneretal.2019, author = {Weymar, Mathias and Ventura-Bort, Carlos and Wirkner, Janine and Genheimer, Hannah and Wendt, Julia and Hamm, Alfons O.}, title = {Effects of Transcutaneous Vagus Vagus Nerve Stimulation (TVNS) on selective attentions and emotional episodic memory : findings from ERP research}, series = {Psychophysiology : journal of the Society for Psychophysiological Research}, volume = {56}, journal = {Psychophysiology : journal of the Society for Psychophysiological Research}, publisher = {Wiley}, address = {Hoboken}, issn = {0048-5772}, doi = {10.1111/psyp.13501}, pages = {S12 -- S12}, year = {2019}, abstract = {Recent research indicates that non- invasive stimulation of the afferent auricular vagal nerve (tVNS) may modulate various cognitive and affec-tive functions, likely via activation of the locus coeruleus- norepinephrine (LC- NE) system. In a series of ERP studies we found that the attention- related P300 component is enhanced during continuous vagal stimula-tion, compared to sham, which is also related to increased salivary alpha amylase levels (a putative indirect marker for central NE activation). In another study, we investigated the effect of continuous tVNS on the late positive potential (LPP), an electrophysiological index for motivated atten-tion toward emotionally evocative cues, and the effects of tVNS on later recognition memory (1- week delay). Here, vagal stimulation prompted earlier LPP differences (300- 500 ms) between unpleasant and neutral scenes. During retrieval, vagal stimulation significantly improved memory performance for unpleasant, but not neutral pictures, compared to sham stimulation, which was also related to enhanced salivary alpha amylase levels. In line, unpleasant images encoded under tVNS compared to sham stimulation also produced enhanced ERP old/new differences (500- 800 ms) during retrieval indicating better recollection. Taken together, our studies suggest that tVNS facilitates attention, learning and episodic memory, likely via afferent projections to the arousal- modulated LC- NE system. We will, however, also show data that point to critical stimulation parameters (likely duration and frequency) that need to be considered when applying tVNS}, 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} } @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{WeymarVenturaBortGenheimeretal.2017, author = {Weymar, Mathias and Ventura-Bort, Carlos and Genheimer, Hannah and Wirkner, Janine and Wendt, Julia and Hamm, Alfons O.}, title = {THE P300 AND THE LC-NE SYSTEM: NEW INSIGHTS FROM TRANSCUTANEOUS VAGUS NERVE STIMULATION (TVNS)}, series = {Psychophysiology : journal of the Society for Psychophysiological Research}, volume = {54}, journal = {Psychophysiology : journal of the Society for Psychophysiological Research}, publisher = {Wiley}, address = {Hoboken}, issn = {0048-5772}, pages = {S145 -- S145}, year = {2017}, language = {en} } @article{WirknerVenturaBortSchwabeetal.2019, author = {Wirkner, Janine and Ventura-Bort, Carlos and Schwabe, Lars and Hamm, Alfons O. and Weymar, Mathias}, title = {Chronic stress and emotion: Differential effects on attentional processing and recognition memory}, series = {Psychoneuroendocrinology}, volume = {107}, journal = {Psychoneuroendocrinology}, publisher = {Elsevier}, address = {Oxford}, issn = {0306-4530}, doi = {10.1016/j.psyneuen.2019.05.008}, pages = {93 -- 97}, year = {2019}, abstract = {Previous research indicates that acute stress around the time of learning facilitates attention and memory for emotionally salient information. Despite accumulating evidence for these acute stress effects, less is known about the role of chronic stress. In the present study, we therefore tested emotional and neutral scene processing and later recognition memory in female participants using hair cortisol concentrations as a biological marker for chronic stress. Event-related potentials recorded during picture viewing indicated enhanced late positive potentials (LPPs) for emotional, relative to neutral contents. These brain potentials varied as a function of long-term hair cortisol levels: hair-cortisol levels were positively related to overall LPP amplitudes. Results from recognition memory testing one week after encoding revealed better memory for emotional relative to neutral scenes. Hair-cortisol levels, however, were related to poorer memory accuracy. Taken together, our results indicate that chronic stress enhanced attentional processing during encoding of new stimuli and impaired later recognition memory. Results are discussed with regard to putatively opposite effects of chronic stress on certain brain regions (e.g., amygdala and hippocampus).}, language = {en} } @article{VenturaBortDolcosWendtetal.2017, author = {Ventura-Bort, Carlos and Dolcos, Florin and Wendt, Julia and Wirkner, Janine and Hamm, Alfons O. and Weymar, Mathias}, title = {Item and source memory for emotional associates is mediated by different retrieval processes}, series = {Neuropsychologia : an international journal in behavioural and cognitive neuroscience}, volume = {145}, journal = {Neuropsychologia : an international journal in behavioural and cognitive neuroscience}, publisher = {Elsevier}, address = {Oxford}, issn = {0028-3932}, doi = {10.1016/j.neuropsychologia.2017.12.015}, pages = {11}, year = {2017}, abstract = {Recent event-related potential (ERP) data showed that neutral objects encoded in emotional background pictures were better remembered than objects encoded in neutral contexts, when recognition memory was tested one week later. In the present study, we investigated whether this long-term memory advantage for items is also associated with correct memory for contextual source details. Furthermore, we were interested in the possibly dissociable contribution of familiarity and recollection processes (using a Remember/Know procedure). The results revealed that item memory performance was mainly driven by the subjective experience of familiarity, irrespective of whether the objects were previously encoded in emotional or neutral contexts. Correct source memory for the associated background picture, however, was driven by recollection and enhanced when the content was emotional. In ERPs, correctly recognized old objects evoked frontal ERP Old/New effects (300-500 ms), irrespective of context category. As in our previous study (Ventura-Bort et al., 2016b), retrieval for objects from emotional contexts was associated with larger parietal Old/New differences (600-800 ms), indicating stronger involvement of recollection. Thus, the results suggest a stronger contribution of recollection-based retrieval to item and contextual background source memory for neutral information associated with an emotional event.}, language = {en} }