Three Hundred Hertz Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) Impacts Pupil Size Non‐Linearly as a Function of Intensity.
Saved in:
| Title: | Three Hundred Hertz Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) Impacts Pupil Size Non‐Linearly as a Function of Intensity. |
|---|---|
| Authors: | Phillips, Ian (AUTHOR), Johns, Michael A. (AUTHOR), Pandža, Nick B. (AUTHOR), Calloway, Regina C. (AUTHOR), Karuzis, Valerie P. (AUTHOR), Kuchinsky, Stefanie E. (AUTHOR) |
| Source: | Psychophysiology. Feb2025, Vol. 62 Issue 2, p1-25. 25p. |
| Subjects: | Vagus nerve stimulation, Pupillary reflex, Pupillometry, Biomarkers |
| Abstract: | Transcutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that may have numerous potential health and human performance benefits. However, optimal stimulation parameters for maximizing taVNS efficacy are unknown. Progress is impeded by disagreement on the identification of a biomarker that reliably indexes activation of neuromodulatory systems targeted by taVNS, including the locus coeruleus‐norepinephrine (LC‐NE) system. Pupil size varies with LC‐NE activity and is one potential taVNS biomarker that has shown inconsistent sensitivity to taVNS in prior studies. The present study examined the relationship between pupil size and taVNS using stimulation parameters that have shown promising behavioral effects in prior studies but have received comparatively little attention. Participants received trains of 50 μs taVNS pulses delivered continuously below perceptual threshold at 300 Hz to the left external acoustic meatus (EAM) while pupil size was recorded during a pupillary light reflex task. Analysis of pupil size using generalized additive mixed modeling (GAMM) revealed a non‐linear relationship between taVNS intensity and pupil diameter. Active taVNS increased pupil size during stimulation for participants who received taVNS between 2 and approximately 4.8 mA, but not for participants who received higher‐intensity taVNS (up to 8.1 mA). In addition, taVNS effects persisted in subsequent blocks, mitigating decreases in pupil size over the course of the task. These findings suggest 300 Hz taVNS activates the LC‐NE system when applied to the EAM, but its effects may be counteracted at higher intensities. Impact statement: This study indicates that active taVNS delivered at 300 Hz to the external acoustic meatus increases pupil size for taVNS intensities between 2.0 and approximately 4.8 mA. This finding provides evidence that pupillometry can be used as a biomarker to titrate taVNS intensity to maximize its neuromodulatory effects. [ABSTRACT FROM AUTHOR] |
| Copyright of Psychophysiology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Psychology and Behavioral Sciences Collection |
|
Full text is not displayed to guests.
Login for full access.
|
|
| Abstract: | Transcutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that may have numerous potential health and human performance benefits. However, optimal stimulation parameters for maximizing taVNS efficacy are unknown. Progress is impeded by disagreement on the identification of a biomarker that reliably indexes activation of neuromodulatory systems targeted by taVNS, including the locus coeruleus‐norepinephrine (LC‐NE) system. Pupil size varies with LC‐NE activity and is one potential taVNS biomarker that has shown inconsistent sensitivity to taVNS in prior studies. The present study examined the relationship between pupil size and taVNS using stimulation parameters that have shown promising behavioral effects in prior studies but have received comparatively little attention. Participants received trains of 50 μs taVNS pulses delivered continuously below perceptual threshold at 300 Hz to the left external acoustic meatus (EAM) while pupil size was recorded during a pupillary light reflex task. Analysis of pupil size using generalized additive mixed modeling (GAMM) revealed a non‐linear relationship between taVNS intensity and pupil diameter. Active taVNS increased pupil size during stimulation for participants who received taVNS between 2 and approximately 4.8 mA, but not for participants who received higher‐intensity taVNS (up to 8.1 mA). In addition, taVNS effects persisted in subsequent blocks, mitigating decreases in pupil size over the course of the task. These findings suggest 300 Hz taVNS activates the LC‐NE system when applied to the EAM, but its effects may be counteracted at higher intensities. Impact statement: This study indicates that active taVNS delivered at 300 Hz to the external acoustic meatus increases pupil size for taVNS intensities between 2.0 and approximately 4.8 mA. This finding provides evidence that pupillometry can be used as a biomarker to titrate taVNS intensity to maximize its neuromodulatory effects. [ABSTRACT FROM AUTHOR] |
|---|---|
| ISSN: | 00485772 |
| DOI: | 10.1111/psyp.70011 |
