Transcutaneous Vagus Nerve Stimulation (tVNS) does not increase prosocial behavior in Cyberball

Cardiovascular effects of auricular stimulation -a systematic review and meta-analysis of randomized controlled clinical trials

Background

The number of randomized controlled trials using auricular stimulation (AS) such as transauricular vagus nerve stimulation, or other auricular electrostimulation or auricular acupuncture or acupressure, in experimental and clinical settings, has increased markedly over the last three decades. This systematic review focusses on cardiovascular effects of auricular stimulation.

Methods and analysis

The following databases were searched: MEDLINE (PubMed), EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), ISI Web of Science, and Scopus Database. RCTs were reviewed that had been published in English and European languages. Data collection and analysis was conducted by two reviewers independently. Quality and risk assessment of included studies was performed and the meta-analysis of the effect of the most frequently assessed biomarkers.

Results

Altogether, 78 trials were included. 38 studies assessed heart rate (HR), 19 studies analyzed heart rate variability (HRV), 31 studies analyzed blood pressure (BP) and 7 studies were identified that measured oxygen saturation (O2), 2 studies on baroreflex sensitivity and 2 studies on skin conductance were evaluated in this review. 26 studies contained continuous data and were eligible for meta-analysis, 50 trials reported non continuous data and were evaluated descriptively. The overall quality of the studies was moderate to low. AS leads to a significant reduction of HR, the changes though were not considered an adverse reaction. Furthermore, when looking at HRV, AS was able to reduce the LF/HF ratio significantly compared to control procedures. No other cardiovascular parameters (blood pressure, oxygen saturation, baroreflex sensitivity) were changed significantly. AS produced only minor side effects in all trials.

Conclusion

AS can lead to clinically safe reduction of HR and changes in the LF/HF ratio of the HRV, which is presumably via an increase in vagal activity. More research is needed to clarify whether AS can be used to modulate tachycardia or indications with autonomic imbalance.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=231885 PROSPERO, ID CRD42021231885.

The effect of transcutaneous auricular vagus nerve stimulation (taVNS) on cognitive control in multitasking

Current research in brain stimulation suggests transcutaneous auricular vagus nerve stimulation (taVNS) as a promising tool to modulate cognitive functions in healthy populations, such as attention, memory, and executive functions. Empirical evidence in single task contexts, suggests that taVNS promotes holistic task processing, which strengthens the integration of multiple stimulus features in task processing. However, it is unclear how taVNS might affect performance in multitasking, where the integration of multiple stimuli leads to an overlap in stimulus response translation processes, increasing the risk of between-task interference (crosstalk). In a single-blinded, sham-controlled, within-subject design, participants underwent taVNS while performing a dual task. To assess the effects of taVNS, behavioral (reaction times), physiological (heart-rate variability, salivary alpha-amylase), and subjective psychological variables (e.g., arousal) were recorded over three cognitive test blocks. Our results revealed no overall significant effect of taVNS on physiological and subjective psychological variables. However, the results showed a significant increase in between-task interference under taVNS in the first test block, but not in the subsequent test blocks. Our findings therefore suggest that taVNS increased integrative processing of both tasks early during active stimulation.

Sensitive responsiveness in expectant and new fathers

Fathers have an increasingly important role in the family and contribute through their sensitive responsiveness to positive child development. Research on parenting more often included fathers as caregivers in the past two decades. We present a neurobiological model of sensitive responsive parenting with a role for fathers' hormonal levels and neural connectivity and processing of infant signals. We tested this model in a research program ("Father Trials") with correlational and randomized experimental studies, and we review the results of these studies. So far, interaction-focused behavioral interventions seem most promising in supporting fathers' sensitive responsiveness, even though the mechanisms are still uncharted.

Non-invasive vagus nerve stimulation in epilepsy patients enhances cooperative behavior in the prisoner's dilemma task

The vagus nerve constitutes a key link between the autonomic and the central nervous system. Previous studies provide evidence for the impact of vagal activity on distinct cognitive processes including functions related to social cognition. Recent studies in animals and humans show that vagus nerve stimulation is associated with enhanced reward-seeking and dopamine-release in the brain. Social interaction recruits similar brain circuits to reward processing. We hypothesize that vagus nerve stimulation (VNS) boosts rewarding aspects of social behavior and compare the impact of transcutaneous VNS (tVNS) and sham stimulation on social interaction in 19 epilepsy patients in a double-blind pseudo-randomized study with cross-over design. Using a well-established paradigm, i.e., the prisoner’s dilemma, we investigate effects of stimulation on cooperative behavior, as well as interactions of stimulation effects with patient characteristics. A repeated-measures ANOVA and a linear mixed-effects model provide converging evidence that tVNS boosts cooperation. Post-hoc correlations reveal that this effect varies as a function of neuroticism, a personality trait linked to the dopaminergic system. Behavioral modeling indicates that tVNS induces a behavioral starting bias towards cooperation, which is independent of the decision process. This study provides evidence for the causal influence of vagus nerve activity on social interaction.

Toward Diverse or Standardized: A Systematic Review Identifying Transcutaneous Stimulation of Auricular Branch of the Vagus Nerve in Nomenclature

OBJECTIVES

After 20 years of development, there is confusion in the nomenclature of transcutaneous stimulation of the auricular branch of the vagus nerve (ABVN). We performed a systematic review of transcutaneous stimulation of ABVN in nomenclature.

MATERIALS AND METHODS

A systematic search of the literature was carried out, using the bibliographic search engine PubMed. The search covered articles published up until June 11, 2020. We recorded the full nomenclature and abbreviated nomenclature same or similar to transcutaneous stimulation of ABVN in the selected eligible studies, as well as the time and author information of this nomenclature.

RESULTS

From 261 studies, 67 full nomenclatures and 27 abbreviated nomenclatures were finally screened out, transcutaneous vagus nerve stimulation and tVNS are the most common nomenclature, accounting for 38.38% and 42.06%, respectively. In a total of 97 combinations of full nomenclatures and abbreviations, the most commonly used nomenclature for the combination of transcutaneous vagus nerve stimulation and tVNS, accounting for 30.28%. Interestingly, the combination of full nomenclatures and abbreviations is not always a one-to-one relationship, there are ten abbreviated nomenclatures corresponding to transcutaneous vagus nerve stimulation, and five full nomenclatures corresponding to tVNS. In addition, based on the analysis of the usage habits of nomenclature in 21 teams, it is found that only three teams have fixed habits, while other different teams or the same team do not always use the same nomenclature in their paper.

CONCLUSIONS

The phenomenon of confusion in the nomenclature of transcutaneous stimulation of ABVN is obvious and shows a trend of diversity. The nomenclature of transcutaneous stimulation of ABVN needs to become more standardized in the future.

Measuring Brain Response to Transcutaneous Vagus Nerve Stimulation (tVNS) using Simultaneous Magnetoencephalography (MEG)

Objective: Transcutaneous vagus nerve stimulation (tVNS) is form of non-invasive brain stimulation that delivers a sequence of electrical pulses to the auricular branch of the vagus nerve, and is used increasingly in the treatment of a number of health conditions such as epilepsy and depression. Recent research has focused on the efficacy of tVNS to treat different medical conditions, but there is little conclusive evidence concerning the optimal stimulation parameters.There are relatively few studies that have combined tVNS with a neuroimaging modality, and none that have attempted simultaneous magnetoencephalography (MEG) and tVNS due to the presence of large stimulation artifacts produced by the electrical stimulation which are many orders of magnitude larger than underlying brain activity. Approach: The aim of this study is to investigate the utility of MEG to gain insight into the regions of the brain most strongly influenced by tVNS and how variation of the stimulation parameters can affect this response in healthy participants. Main Results: We have successfully demonstrated that MEG can be used to measure brain response to tVNS. We have also shown that varying the stimulation frequency can lead to a difference in brain response, with the brain also responding in different anatomical regions depending on the frequency. Significance: The main contribution of this paper is to demonstrate the feasibility of simultaneous pulsed tVNS and MEG recording, allowing direct investigation of the changes in brain activity that result from different stimulation parameters. This may lead to the development of customised therapeutic approaches for the targeted treatment of different conditions.

Transcutaneous auricular vagus nerve stimulators: a review of past, present and future devices

INTRODUCTION

As an emerging neuromodulation therapy, transcutaneous auricular vagus nerve stimulation (taVNS) has been proven to be safe and effective for epilepsy, major depressive disorders, insomnia, glucose metabolic disorders, pain, stroke, post stroke rehabilitation, anxiety, fear, cognitive impairment, cardiovascular disorders, tinnitus, Prader-Willi Syndrome and COVID-19.

AREAS COVERED

Although the history of taVNS is only two decades, the devices carrying taVNS technique have been constantly updated. Especially in recent years, the development of taVNS devices has presented a new trend. To conclude, the development of taVNS devices has entered a new era, thus the update speed and quality of taVNS devices will be considerably improved in the future. This article reviewed the history and classification of taVNS devices.

EXPERT OPINION

The correlation between the effectiveness and stimulation parameters from taVNS devices still remains unclear. There is a lack of standard or harmonization among different taVNS devices. Strategies, including further comparative research and establishment of standard, have been recommended in this article to promote the future development of taVNS devices.

Recognizing emotions in bodies: Vagus nerve stimulation enhances recognition of anger while impairing sadness

According to the Polyvagal theory, the vagus nerve is the key phylogenetic substrate that supports efficient emotion recognition for promoting safety and survival. Previous studies showed that the vagus nerve affects people's ability to recognize emotions based on eye regions and whole facial images, but not static bodies. The purpose of this study was to verify whether the previously suggested causal link between vagal activity and emotion recognition can be generalized to situations in which emotions must be inferred from images of whole moving bodies. We employed transcutaneous vagus nerve stimulation (tVNS), a noninvasive brain stimulation technique that stimulates the vagus nerve by a mild electrical stimulation to the auricular branch of the vagus, located in the anterior protuberance of the outer ear. In two sessions, participants received active or sham tVNS before and while performing three emotion recognition tasks, aimed at indexing their ability to recognize emotions from static or moving bodily expressions by actors. Active tVNS, compared to sham stimulation, enhanced the recognition of anger but reduced the ability to recognize sadness, regardless of the type of stimulus (static vs. moving). Convergent with the idea of hierarchical involvement of the vagus in establishing safety, as put forward by the Polyvagal theory, we argue that our findings may be explained by vagus-evoked differential adjustment strategies to emotional expressions. Taken together, our findings fit with an evolutionary perspective on the vagus nerve and its involvement in emotion recognition for the benefit of survival.

International Consensus Based Review and Recommendations for Minimum Reporting Standards in Research on Transcutaneous Vagus Nerve Stimulation (Version 2020)

Given its non-invasive nature, there is increasing interest in the use of transcutaneous vagus nerve stimulation (tVNS) across basic, translational and clinical research. Contemporaneously, tVNS can be achieved by stimulating either the auricular branch or the cervical bundle of the vagus nerve, referred to as transcutaneous auricular vagus nerve stimulation(VNS) and transcutaneous cervical VNS, respectively. In order to advance the field in a systematic manner, studies using these technologies need to adequately report sufficient methodological detail to enable comparison of results between studies, replication of studies, as well as enhancing study participant safety. We systematically reviewed the existing tVNS literature to evaluate current reporting practices. Based on this review, and consensus among participating authors, we propose a set of minimal reporting items to guide future tVNS studies. The suggested items address specific technical aspects of the device and stimulation parameters. We also cover general recommendations including inclusion and exclusion criteria for participants, outcome parameters and the detailed reporting of side effects. Furthermore, we review strategies used to identify the optimal stimulation parameters for a given research setting and summarize ongoing developments in animal research with potential implications for the application of tVNS in humans. Finally, we discuss the potential of tVNS in future research as well as the associated challenges across several disciplines in research and clinical practice.

Critical Review of Transcutaneous Vagus Nerve Stimulation: Challenges for Translation to Clinical Practice

Several studies have illustrated that transcutaneous vagus nerve stimulation (tVNS) can elicit therapeutic effects that are similar to those produced by its invasive counterpart, vagus nerve stimulation (VNS). VNS is an FDA-approved therapy for the treatment of both depression and epilepsy, but it is limited to the management of more severe, intervention-resistant cases as a second or third-line treatment option due to perioperative risks involved with device implantation. In contrast, tVNS is a non-invasive technique that involves the application of electrical currents through surface electrodes at select locations, most commonly targeting the auricular branch of the vagus nerve (ABVN) and the cervical branch of the vagus nerve in the neck. Although it has been shown that tVNS elicits hypo- and hyperactivation in various regions of the brain associated with anxiety and mood regulation, the mechanism of action and influence of stimulation parameters on clinical outcomes remains predominantly hypothetical. Suppositions are largely based on correlations between the neurobiology of the vagus nerve and its effects on neural activity. However, tVNS has also been investigated for several other disorders, including tinnitus, migraine and pain, by targeting the vagus nerve at sites in both the ear and the neck. As most of the described methods differ in the parameters and protocols applied, there is currently no firm evidence on the optimal location for tVNS or the stimulation parameters that provide the greatest therapeutic effects for a specific condition. This review presents the current status of tVNS with a focus on stimulation parameters, stimulation sites, and available devices. For tVNS to reach its full potential as a non-invasive and clinically relevant therapy, it is imperative that systematic studies be undertaken to reveal the mechanism of action and optimal stimulation modalities.