Impact of Stimulation Duration in taVNS—Exploring Multiple Physiological and Cognitive Outcomes

Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique that modulates the noradrenergic activity of the locus coeruleus (LC). Yet, there is still uncertainty about the most effective stimulation and reliable outcome parameters. In a double blind, sham-co...

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Main Authors: Till Bömmer, Luisa M. Schmidt, Katharina Meier, Julius Kricheldorff, Heiko Stecher, Christoph S. Herrmann, Christiane M. Thiel, Kathrin Janitzky, Karsten Witt
Format: Article
Language:English
Published: MDPI AG 2024-08-01
Series:Brain Sciences
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Online Access:https://www.mdpi.com/2076-3425/14/9/875
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author Till Bömmer
Luisa M. Schmidt
Katharina Meier
Julius Kricheldorff
Heiko Stecher
Christoph S. Herrmann
Christiane M. Thiel
Kathrin Janitzky
Karsten Witt
author_facet Till Bömmer
Luisa M. Schmidt
Katharina Meier
Julius Kricheldorff
Heiko Stecher
Christoph S. Herrmann
Christiane M. Thiel
Kathrin Janitzky
Karsten Witt
author_sort Till Bömmer
collection DOAJ
description Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique that modulates the noradrenergic activity of the locus coeruleus (LC). Yet, there is still uncertainty about the most effective stimulation and reliable outcome parameters. In a double blind, sham-controlled study including a sample of healthy young individuals (<i>N</i> = 29), we compared a shorter (3.4 s) and a longer (30 s) stimulation duration and investigated the effects of taVNS (real vs. sham) on saliva samples (alpha amylase and cortisol concentration), pupil (pupillary light reflex and pupil size at rest) and EEG data (alpha and theta activity at rest, ERPs for No-Go signals), and cognitive tasks (Go/No-Go and Stop Signal Tasks). Salivary alpha amylase concentration was significantly increased in the real as compared to sham stimulation for the 30 s stimulation condition. In the 3.4 s stimulation condition, we found prolonged reaction times and increased error rates in the Go/No-Go task and increased maximum acceleration in the pupillary light reflex. For the other outcomes, no significant differences were found. Our results show that prolonged stimulation increases salivary alpha-amylase, which was expected from the functional properties of the LC. The finding of longer response times to short taVNS stimulation was not expected and cannot be explained by an increase in LC activity. We also discuss the difficulties in assessing pupil size as an expression of taVNS-mediated LC functional changes.
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spelling doaj-art-c78cd47e766e49f4b4779832e6913f982025-08-20T01:56:05ZengMDPI AGBrain Sciences2076-34252024-08-0114987510.3390/brainsci14090875Impact of Stimulation Duration in taVNS—Exploring Multiple Physiological and Cognitive OutcomesTill Bömmer0Luisa M. Schmidt1Katharina Meier2Julius Kricheldorff3Heiko Stecher4Christoph S. Herrmann5Christiane M. Thiel6Kathrin Janitzky7Karsten Witt8Department of Neurology, Carl von Ossietzky University, 26121 Oldenburg, GermanyDepartment of Neurology, Carl von Ossietzky University, 26121 Oldenburg, GermanyDepartment of Neurology, Carl von Ossietzky University, 26121 Oldenburg, GermanyDepartment of Neurology, Carl von Ossietzky University, 26121 Oldenburg, GermanyExperimental Psychology Lab, Department of Psychology, Carl von Ossietzky University, 26129 Oldenburg, GermanyExperimental Psychology Lab, Department of Psychology, Carl von Ossietzky University, 26129 Oldenburg, GermanyBiological Psychology Lab, Department of Psychology, Carl von Ossietzky University, 26129 Oldenburg, GermanyDepartment of Neurology, Carl von Ossietzky University, 26121 Oldenburg, GermanyDepartment of Neurology, Carl von Ossietzky University, 26121 Oldenburg, GermanyTranscutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique that modulates the noradrenergic activity of the locus coeruleus (LC). Yet, there is still uncertainty about the most effective stimulation and reliable outcome parameters. In a double blind, sham-controlled study including a sample of healthy young individuals (<i>N</i> = 29), we compared a shorter (3.4 s) and a longer (30 s) stimulation duration and investigated the effects of taVNS (real vs. sham) on saliva samples (alpha amylase and cortisol concentration), pupil (pupillary light reflex and pupil size at rest) and EEG data (alpha and theta activity at rest, ERPs for No-Go signals), and cognitive tasks (Go/No-Go and Stop Signal Tasks). Salivary alpha amylase concentration was significantly increased in the real as compared to sham stimulation for the 30 s stimulation condition. In the 3.4 s stimulation condition, we found prolonged reaction times and increased error rates in the Go/No-Go task and increased maximum acceleration in the pupillary light reflex. For the other outcomes, no significant differences were found. Our results show that prolonged stimulation increases salivary alpha-amylase, which was expected from the functional properties of the LC. The finding of longer response times to short taVNS stimulation was not expected and cannot be explained by an increase in LC activity. We also discuss the difficulties in assessing pupil size as an expression of taVNS-mediated LC functional changes.https://www.mdpi.com/2076-3425/14/9/875transcutaneous auricular vagus nerve stimulation (taVNS)neuromodulationlocus coeruleus (LC)stimulation durationoutcome parameters
spellingShingle Till Bömmer
Luisa M. Schmidt
Katharina Meier
Julius Kricheldorff
Heiko Stecher
Christoph S. Herrmann
Christiane M. Thiel
Kathrin Janitzky
Karsten Witt
Impact of Stimulation Duration in taVNS—Exploring Multiple Physiological and Cognitive Outcomes
Brain Sciences
transcutaneous auricular vagus nerve stimulation (taVNS)
neuromodulation
locus coeruleus (LC)
stimulation duration
outcome parameters
title Impact of Stimulation Duration in taVNS—Exploring Multiple Physiological and Cognitive Outcomes
title_full Impact of Stimulation Duration in taVNS—Exploring Multiple Physiological and Cognitive Outcomes
title_fullStr Impact of Stimulation Duration in taVNS—Exploring Multiple Physiological and Cognitive Outcomes
title_full_unstemmed Impact of Stimulation Duration in taVNS—Exploring Multiple Physiological and Cognitive Outcomes
title_short Impact of Stimulation Duration in taVNS—Exploring Multiple Physiological and Cognitive Outcomes
title_sort impact of stimulation duration in tavns exploring multiple physiological and cognitive outcomes
topic transcutaneous auricular vagus nerve stimulation (taVNS)
neuromodulation
locus coeruleus (LC)
stimulation duration
outcome parameters
url https://www.mdpi.com/2076-3425/14/9/875
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