Transcutaneous Vagus Nerve Stimulation Modulates EEG Microstates and Delta Activity in Healthy Subjects

Abstract

Transcutaneous vagus nerve stimulation (tVNS) is an alternative non-invasive method for the electrical stimulation of the vagus nerve with the goal of treating several neuropsychiatric disorders. The objective of this study is to assess the effects of tVNS on cerebral cortex activity in healthy volunteers using resting-state microstates and power spectrum electroencephalography (EEG) analysis. Eight male subjects aged 25–45 years were recruited in this randomized sham-controlled double-blind study with cross-over design. Real tVNS was administered at the left external acoustic meatus, while sham stimulation was performed at the left ear lobe, both of them for 60 min. The EEG recording lasted 5 min and was performed before and 60 min following the tVNS experimental session. We observed that real tVNS induced an increase in the metrics of microstate A mean duration (p = 0.039) and an increase in EEG power spectrum activity in the delta frequency band (p < 0.01). This study confirms that tVNS is an effective way to stimulate the vagus nerve, and the mechanisms of action of this activation can be successfully studied using scalp EEG quantitative metrics. Future studies are warranted to explore the clinical implications of these findings and to focus the research of the prognostic biomarkers of tVNS therapy for neuropsychiatric diseases.

Transcutaneous Cervical Vagus Nerve Stimulation Induces Changes in the Electroencephalogram and Heart Rate Variability of Healthy Dogs, a Pilot Study

“…The decrease in the power of the theta and alpha frequency bands via both methods of power analyses in our study are suggestive of adequate tcVNS, similar to reported EEG changes with VNS/tcVNS in people ( 38 , 39 , 54 , 55 ). These acute changes in the EEG are thought to be secondary to the desynchronization of brain activity as afferent vagus nerve signals cause a shift from predominantly low frequency activity (like delta, theta and alpha) to high frequency bands (like beta and gamma) thus promoting a higher arousal/awareness state ( 38 , 39 , 54 ).…”

Training and Transfer Effects of Combining Inhibitory Control Training With Transcutaneous Vagus Nerve Stimulation in Healthy Adults

“…Another new approach for improving IC is non-invasive brain stimulation, such as transcutaneous vagus nerve stimulation (tVNS), which is a novel non-invasive intervention for modulating nervous system function by applying direct-current pulse electrical stimulation on the ear branch of the vagus nerve ( Ventureyra, 2000 ). Recent studies have shown that tVNS activates the locus coeruleus-noradrenergic (LC-NA) system ( Warren et al, 2019 ; Ricci et al, 2020 ; Sharon et al, 2021 ). The LC-NA system modulates and improves cognitive functions, such as IC.…”

Men Show Reduced Cardiac Baroreceptor Sensitivity during Modestly Painful Electrical Stimulation of the Forearm: Exploratory Results from a Sham-Controlled Crossover Vagus Nerve Stimulation Study

“…In contrast, two recent studies did not find any changes in pupillary responses and cardiac vagal activity associated with active tVNS during cognitive tasks [54,55]. Using electroencephalography, one study showed an increased attenuation of alpha oscillations during tVNS [53], while another reported a greater power in the delta band frequencies [56].…”