How brain efficiency, dopamine, and fitness are intertwined

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Dopamine molecule and 3D diagram. Dopaminergic means “related to dopamine”.

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Researchers in Japan have found a new and relatively simple way to determine whether the link between higher aerobic fitness and more efficient executive function is mediated by activity in the brain’s dopamine system. This study (Kuwamizu et al., 2021) was recently published in the journal Medicine & Science in Sports & Exercise.

For this study, a team of scientists from Tsukuba University, led by lead author Ryuta Kuwamizu and lead author Hideaki Soya, used measurements of the spontaneous blink rate (sEBR) to determine whether higher levels of cardiorespiratory fitness, increased sEBR, and more efficient neural activity present in the prefrontal cortex are interconnected.

Accumulating evidence suggests that the spontaneous wink rate is a non-invasive marker of central dopamine function. A higher sEBR predicts more robust dopamine function (Jongkees & Colzato, 2016). Previous research has also shown that moderate to vigorous physical activity (MVPA) and high-intensity interval training (HIIT) stimulate dopamine release in many areas of the brain.

Although several neural mechanisms (e.g., BDNF, neurogenesis, synaptic plasticity) and various neurotransmitters (e.g., endocannabinoids, serotonin) influence the brain-promoting benefits of physical activity, MVPA and HIIT workouts are known to increase dopamine levels, and so do so When this is the case For the neuromodulation of aerobic exercise, the dopaminergic system is of paramount importance (Heijnen et al., 2016).

For the recent study from Tsukuba University, Soya Lab’s goal was to determine whether sEBR was an effective marker for tracking exercise-induced changes in neural efficiency that previous studies have linked to the brain’s dopamine system.

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“The dopaminergic system is linked to both executive function and motivated behavior, including physical activity,” said Kuwamizu in a February 1 press release. “We used sEBR as a non-invasive measure of the function of the dopaminergic system to test whether it could be the missing link between aerobic fitness and cognitive function.”

To test this hypothesis, the researchers had a cohort of 35 healthy young men (18-24 years old) undergo aerobic fitness assessments in conjunction with sEBR assessments. They also performed a stroop task to measure executive functions. During the color word Stroop task, cortical activity in the prefrontal cortex (DLPFC) was monitored using near infrared functional spectroscopy (fNIRS). Correlation analyzes showed, among other things, that “a higher sEBR was correlated with a higher neuronal efficiency of the l-DLPFC”.

“As expected, we found significant correlations between aerobic fitness, cognitive function and sEBR,” noted Soya. “When we examined these relationships further, we found that the association between higher aerobic fitness and improved cognitive function was mediated in part through dopaminergic regulation.”

“Although previous studies have shown that aerobic fitness and cognitive function are correlated, this is the first to provide a neuromodulatory basis for this relationship in humans,” added Kuwamizu. “Our data shows that dopamine plays an essential role in the link between aerobic fitness and cognition.”

“These results show that sEBR mediates the association between aerobic fitness and executive function through prefrontal neural efficiency, which clearly supports the hypothesis that dopaminergic function of the brain connects at least in part the missing link between aerobic fitness and executive function.” The authors close.