Immediate effects and duration of a short and single application of transcutaneous auricular vagus nerve stimulation on P300 event related potential

Abstract

IntroductionTranscutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that stimulates the auricular branch of the vagus nerve. The modulation of the locus coeruleus-norepinephrine (LC-NE) network is one of the potential working mechanisms of this method. Our aims were 1-to investigate if short and single applications of taVNS can modulate the P300 cognitive event-related potential (ERP) as an indirect marker that reflects NE brain activation under control of the LC, and 2-to evaluate the duration of these changes.Methods20 healthy volunteers executed an auditory oddball paradigm to obtain P300 and reaction time (RT) values. Then a 7 min active or sham taVNS period was initiated and simultaneously a new P300 paradigm was performed. We successively repeated the paradigm on 4 occasions with different time intervals up to 56 min after the stimulation onset.ResultsDuring active taVNS an immediate and significant effect of increasing the amplitude and reducing the latency of P300, as well as a shortening in the RT was observed. This effect was prolonged in time up to 28 min. The values then returned to pre-stimulation levels. Sham stimulation did not generate changes.DiscussionOur results, demonstrate differential facilitating effects in a concrete time window after taVNS. Literature about the modulatory effect of taVNS over P300 ERP shows a wide spread of results. There is not a standardized system for taVNS and currently the great heterogeneity of stimulation approaches concerning targets and parameters, make it difficult to obtain conclusions about this relationship. Our study was designed optimizing several stimulation settings, such as a customized earbud stimulator, enlarged stimulating surface, simultaneous stimulation over the cymba and cavum conchae, a Delayed Biphasic Pulse Burst and current controlled stimulation that adjusted the output voltage and guaranteed the administration of a preset electrical dose. Under our stimulation conditions, targeting vagal nerve fibers via taVNS modulates the P300 in healthy participants. The optimal settings of modulatory function of taVNS on P300, and their interdependency is insufficiently studied in the literature, but our data provides several easily optimizable parameters, that will produce more robust results in future.

Transcutaneous auricular vagus nerve stimulation enhances short-latency afferent inhibition via cholinergic system activation

“…While we cannot provide direct neurophysiological evidence, we speculate that taVNS, through one of the neural circuits mentioned above, activated the cholinergic BF, leading to the observed enhancement of SAI. Furthermore, the observed augmentation of SAI in our study did not occur immediately after taVNS, but rather 15 minutes after its completion, suggesting that mechanisms producing after-effects (o ine effects) are involved post-stimulation, possibly related to synaptic plasticity following taVNS 51 . Fragons et al 17 in an fMRI study, reported a decrease in the observed BOLD signal enhancement in the subthalamic nucleus (STN) during taVNS, which was followed by an increase in LC activity after stimulation.…”

Cognitive Functions following Trigeminal Neuromodulation

“…However, the external ear is also innervated by trigeminal nerve fibers, partially overlapping with the vagus territory [ 100 , 101 ]; therefore, an appropriate electrode positioning easily results in the stimulation of both trigeminal and vagal afferents [ 6 , 102 ]. The study of auricular tVNS has seen great development in recent years, especially with regard to improved cognitive performance, not only in the clinical population but also in healthy subjects [ 103 , 104 , 105 , 106 , 107 ]. While the neurobiological mechanisms are still unclear, the available literature mostly seek to explain the positive effects of tVNS on cognitive performance in terms of a change in brain NE levels [ 64 , 108 ].…”

EEG denoising during transcutaneous auricular vagus nerve stimulation across simulated, phantom and human data

“…A variety of methods have been proposed for the removal of artifacts in taVNS-EEG/MEG recordings. These include notch filtering (Chen et al, 2023; Lloyd et al, 2023; Sharon et al, 2021), independent component analysis (ICA) (Gurtubay et al, 2023), the Cleanline algorithm (Poppa et al, 2022), linear interpolation (Schuerman et al, 2021), and autoregressive modelling (Keatch et al, 2023). A lack of thoroughly evaluated artifact correction methods is recognized as a current challenge for concurrent taVNS-M/EEG studies (Wienke et al, 2023).…”