Recent research by Sharon et al. (2020) indicated an activating effect of transcutaneous auricular vagus nerve stimulation (taVNS) on the locus coreleus noradrenergic (LC-NA) system. Given the...Show moreRecent research by Sharon et al. (2020) indicated an activating effect of transcutaneous auricular vagus nerve stimulation (taVNS) on the locus coreleus noradrenergic (LC-NA) system. Given the mixed findings of previous research, we replicated this study to validate and extend their results. Twenty-one subjects participated in a repeated measures design using the same no-task paradigm as Sharon et al. (2020). Additionally, we extended the analysis to explore indicators of LC-NA activity in the EEG time domain. We compared EEG activity between sham (earlobe) and stimulation (cymba conchae) conditions. Our analysis found significantly less alpha activity during taVNS compared to sham stimulation. This confirms the finding of Sharon et al. (2020) - taVNS attenuates alpha oscillations. However, we found no differences in ERPs between conditions. This was likely due to methodological limitations that make the design inappropriate for ERP research. Our results support an effect of taVNS on phasic LC-NA activity, but the effect on tonic LC-NA remains unknown. This is discussed from the perspective of using taVNS as an intervention for disorders such as ADHD. Based on our exploratory analysis and literature findings, recommendations are made for future research.Show less
In the current study, we aim to replicate Sharon and colleagues’ (2020) study on tVNS. The current conflicting evidence in the area of tVNS and pupil dilation research makes results unreliable and...Show moreIn the current study, we aim to replicate Sharon and colleagues’ (2020) study on tVNS. The current conflicting evidence in the area of tVNS and pupil dilation research makes results unreliable and findings inapplicable in practice. As such we attempt to confirm the finding that transcutaneous vagus nerve stimulation (tVNS) of the auricular branch of the vagus nerve induces pupil dilation. In an experiment utilizing an eye tracker, we found that there’s no statistically significant difference between control and intervention conditions at 3-6 seconds after stimulation onset. We discuss the implications of our failure to replicate the results of Sharon et al. and possible underlying mechanisms which led to the findings. Finding the current evidence lacking, we suggest further experimentation and replication in the area, as well as proposing that underlying mechanisms of locus coerleus (LC) activation and pupil dilation be the subject of further research in the area.Show less
Learning by trial and error is a very fundamental type of learning. In cognitive sciences, this concept is called reinforcement learning and is widely used for research, since it allows comparably...Show moreLearning by trial and error is a very fundamental type of learning. In cognitive sciences, this concept is called reinforcement learning and is widely used for research, since it allows comparably easy operationalisation. In order to translate this into computable data, models of reinforcement learning such as the Rescorla-Wagner learning rule are used. These models usually neglect disturbance in learning, which is called computational noise and reduces the precision of neural computations during the learning process. Recent research has looked further into exactly this parameter of learning and found that it indeed plays a big part and should not be neglected (Drugowitsch, Wyart, Devauchelle & Koechlin, 2016). Besides replicating a study by Findling and colleagues (2019), this study specifically looks into the role of noradrenaline in the reinforcement learning process and learning noise. Noradrenaline excretion was triggered by transcutaneous vagus nerve stimulation, while a two-armed bandit task was used as learning task. We did not find significant effects of this neurotransmitter on the learning process, however, successfully replicated the research of Findling et al. (2019). These results imply that computational noise during the learning process is still a crucial factor in reinforcement learning and should therefore be further investigated. Noradrenaline might not impact the amount of learning noise to the expected extent.Show less
BACKGROUND: Exposure therapy, which is based on extinction learning, is the therapy of choice for several anxiety disorders. However, the remission rate is not optimal for adults with an anxiety...Show moreBACKGROUND: Exposure therapy, which is based on extinction learning, is the therapy of choice for several anxiety disorders. However, the remission rate is not optimal for adults with an anxiety disorder, which could be due to non-response or to the return of the original fear after exposure therapy. Persons with high levels of anxiety have more difficulties constructing and consolidating extinction memories. Stimulating the vagus nerve (tVNS) is a promising method of enhancing the process of extinction learning as shown in previous animal and human studies. AIM: The aim of this study was to assess whether participants with high levels of anxiety would benefit more from the addition of tVNS measured in US expectancy ratings and skin conductance response. METHOD: This paper is a reanalysis of the data from the study of Burger et al. (2018). In this study healthy humans participated in a prepared fear learning paradigm, spider pictures were used as conditioned stimulus. After the acquisition phase participants were randomly allocated to the tVNS condition (N=42) and to the sham condition (N=43) for the extinction phase. High- and low-scoring groups were created based on the state and trait subscales of the STAI. RESULTS: There were no differences found between the high- and low-scoring groups in the effectiveness of tVNS, although the low state group in the tVNS condition showed lower US expectancy ratings for the CS- trials. CONCLUSION: This distinct study does not provide conclusive evidence to support the direction of studying tVNS in a clinical sample.Show less
