A possible contribution of the locus coeruleus to arousal enhancement with mild exercise: evidence from pupillometry and neuromelanin imaging

Yudai Yamazaki; Kazuya Suwabe; Atsuko Nagano-Saito; Kousaku Saotome; Ryuta Kuwamizu; Taichi Hiraga; Ferenc Torma; Kenji Suzuki; Yoshiyuki Sankai; Michael A Yassa; Hideaki Soya

doi:10.1093/texcom/tgad010

A possible contribution of the locus coeruleus to arousal enhancement with mild exercise: evidence from pupillometry and neuromelanin imaging

Cereb Cortex Commun. 2023 Jun 8;4(2):tgad010. doi: 10.1093/texcom/tgad010. eCollection 2023.

Authors

Yudai Yamazaki^{1

2}, Kazuya Suwabe^{2

3

4}, Atsuko Nagano-Saito^{1

2

5}, Kousaku Saotome^{4

6}, Ryuta Kuwamizu^{1

7}, Taichi Hiraga¹, Ferenc Torma^{1

2}, Kenji Suzuki⁴, Yoshiyuki Sankai⁴, Michael A Yassa^{2

8

9}, Hideaki Soya^{1

2}

Affiliations

¹ Laboratory of Exercise Biochemistry and Neuroendocrinology, Faculty of Health and Sport Sciences, University of Tsukuba, 1-1-1 Tannoudai, Tsukuba, Ibaraki 305-8574, Japan.
² Sport Neuroscience Division, Advanced Research Initiative for Human High Performance (ARIHHP), Faculty of Health and Sport Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8574, Japan.
³ Faculty of Health and Sport Sciences, Ryutsu Keizai University, 120 Ryugasaki, Ibaraki 301-0844, Japan.
⁴ Center for Cybernics Research, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573, Japan.
⁵ Department of Radiology, Ushiku Aiwa General Hospital, 896 Inoko-cho, Ushiku, Ibaraki 300-1296, Japan.
⁶ Department of Radiological Sciences, School of Health Sciences, Fukushima Medical University, 1 Hikarigaoka, Fukushima, Fukushima 960-1295, Japan.
⁷ Graduate School of Letters, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
⁸ Department of Neurobiology and Behavior, University of California, Irvine, CA 92679-3800, United States.
⁹ Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA 92679-3800, United States.

Abstract

Acute mild exercise has been observed to facilitate executive function and memory. A possible underlying mechanism of this is the upregulation of the ascending arousal system, including the catecholaminergic system originating from the locus coeruleus (LC). Prior work indicates that pupil diameter, as an indirect marker of the ascending arousal system, including the LC, increases even with very light-intensity exercise. However, it remains unclear whether the LC directly contributes to exercise-induced pupil-linked arousal. Here, we examined the involvement of the LC in the change in pupil dilation induced by very light-intensity exercise using pupillometry and neuromelanin imaging to assess the LC integrity. A sample of 21 young males performed 10 min of very light-intensity exercise, and we measured changes in the pupil diameters and psychological arousal levels induced by the exercise. Neuromelanin-weighted magnetic resonance imaging scans were also obtained. We observed that pupil diameter and psychological arousal levels increased during very light-intensity exercise, which is consistent with previous findings. Notably, the LC contrast, a marker of LC integrity, predicted the magnitude of pupil dilation and psychological arousal enhancement with exercise. These relationships suggest that the LC-catecholaminergic system is a potential a mechanism for pupil-linked arousal induced by very light-intensity exercise.

Keywords: arousal; locus coeruleus; neuromelanin; pupil diameter; very light-intensity exercise.