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. 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. 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. 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.

Non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) has attracted increasing interest as a neurostimulation tool with potential applications in modulating cognitive processes such as attention and memory, possibly through the modulation of the locus–coeruleus noradrenaline system. Studies examining the P300 brain-related component as a correlate of noradrenergic activity, however, have yielded inconsistent findings, possibly due to differences in stimulation parameters, thus necessitating further investigation. In this event-related potential study involving 61 participants, therefore, we examined how changes in taVNS parameters, specifically stimulation type (interval vs. continuous stimulation) and duration, influence P300 amplitudes during a visual novelty oddball task. Although no effects of stimulation were found over the whole cluster and time window of the P300, cluster-based permutation tests revealed a distinct impact of taVNS on the P300 response for a small electrode cluster, characterized by larger amplitudes observed for easy targets (i.e., stimuli that are easily discernible from standards) following taVNS compared to sham stimulation. Notably, our findings suggested that the type of stimulation significantly modulated taVNS effects on the P300, with continuous stimulation showing larger P300 differences (taVNS vs. sham) for hard targets and standards compared to interval stimulation. We observed no interaction effects of stimulation duration on the target-related P300. While our findings align with previous research, further investigation is warranted to fully elucidate the influence of taVNS on the P300 component and its potential utility as a reliable marker for neuromodulation in this field.

The Covid-19 pandemic imposed new constraints on empirical research and forced researchers to transfer from traditional laboratory research to the online environment. This study tested the validity of a web-based episodic memory paradigm by comparing participants’ memory performance for trustworthy and untrustworthy facial stimuli in a supervised laboratory setting and an unsupervised web setting. Consistent with previous results, we observed enhanced episodic memory for untrustworthy compared to trustworthy faces. Most importantly, this memory bias was comparable in the online and the laboratory experiment, suggesting that web-based procedures are a promising tool for memory research.

Remembering emotionally significant events is critical for the organisms’ behavior and survival. While the mechanisms underlying the formation of such memories are well understood and closely linked to the vagus nerve and the brain’s arousal system, less is known about its contribution to memory retrieval. The current study tested whether non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) applied during a long-term recognition memory task influenced retrieval of unpleasant and neutral scenes that had been incidentally encoded one week earlier. Results showed that taVNS, compared to a sham condition, selectively enhanced the recollection of unpleasant images. Despite a modest effect size ( d = 0.33 ), these findings provide initial human support suggesting a role of the vagus nerve in emotional memory retrieval, thus extending current theoretical models of emotional memory retrieval and opening a new pathway for memory modulation and non-invasive therapeutic interventions.

Remembering emotionally significant events is critical for the organisms’ behavior and survival. While the mechanisms underlying formation of such memories are well understood and closely linked to the vagus nerve and the brain’s arousal system, less is known about its contribution to memory retrieval. The current study tested whether non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) applied during a long-term recognition memory task influenced retrieval of unpleasant and neutral scenes that have been incidentally encoded one week earlier. Results showed that taVNS, compared to a sham condition, selectively enhanced the recollection of unpleasant images. Despite a modest effect size ( d = 0 . 33 ), these findings provide first human evidence for a direct link of the vagus nerve in emotional memory retrieval, thus extending current theoretical models of emotional memory retrieval and opening a new pathway for memory modulation and non-invasive therapeutic interventions.