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Pupil Size Predicts Prefrontal Function Benefits During Light Exercise

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Credit: Amanda Dalbjörn / Unsplash.
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Mild exercise like yoga improves mood and executive function, but the neural mechanisms were unclear. Using pupillometry, researchers found that pupil size changes during very light exercise predict subsequent executive function improvement, indicating the involvement of the brain's arousal system.

Key Takeaways

  • Mild forms of exercise, like yoga or walking, improve mood and executive function, but the brain activity was unclear.
  • Pupillometry, a noninvasive technique, can measure neural activity during exercise, and pupil size changes predict executive function improvement.
  • Very light exercise caused pupil dilation and increased activity in the left dorsolateral prefrontal cortex, enhancing executive function. Pupil diameter shows potential as a biomarker for exercise effects on the brain.
  • Investigating pupil size variations

    Recent studies have revealed that mild forms of exercise, such as yoga or walking, can improve mood and enhance executive function, which involves the brain's prefrontal cortex and refers to the ability to control one's behavior to achieve a goal. However, the specific neural activity in the human brain that leads to the improvement of executive function during exercise has remained poorly understood due to tecFhnical limitations.

    It is often said that the eyes are a part of the brain and can effectively reflect a person's mental state. In recent years, there has been growing interest in investigating pupil size variations as these are closely linked to the neural activity associated with the brain's noradrenergic arousal system. Pupillometry, a noninvasive and contactless measurement technique, allows for the assessment of neural activity during aerobic exercise and could serve as an indicator of arousal neural activity. Based on this premise, a research team led by KUWAMIZU Ryuta and SOYA Hideaki hypothesized that changes in pupil size during very light exercise could predict improvement in prefrontal executive function after a single exercise session.

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    To test this theory, the research team asked a group of healthy young adults to participate in 10-min very light exercise followed by an executive function task. The findings revealed that pupils dilated during the exercise, and the extent of the dilation was an indicator of a subsequent improvement in executive function. Prefrontal cortex activity during the executive function task was examined using functional near-infrared spectroscopy, demonstrating an increase in the activity of the left dorsolateral prefrontal cortex, a region associated with executive function.

    These results strongly suggest that the enhancement of prefrontal executive function resulting from very light exercise can be attributed to pupil-linked neural activity, specifically the activation of the brain's noradrenergic arousal system. Looking ahead, pupil diameter holds promising potential as a novel biomarker that can be used to predict the effects of exercise on the brain.

    Reference: Kuwamizu R, Yamazaki Y, Aoike N, et al. Pupil dynamics during very light exercise predict benefits to prefrontal cognition. NeuroImage. 2023;277:120244. doi: 10.1016/j.neuroimage.2023.120244

    This article has been republished from the following materials. Article summaries may have been generated by fact-checked AI models. Note: material may have been edited for length and content. For further information, please contact the cited source.