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Eye and visual cortex nerves.
Source: CLIPAREA l Custom media/Shutterstock

Low-intensity aerobic exercise arouses neurons in the visual cortex and enhances human vision more effectively than high-intensity exercise, according to a new study by researchers at the University of California, Santa Barbara. (The visual cortex is a brain region within the cerebral cortex that plays an important role in processing visual information.)

The February 2017 study, "Acute Exercise Modulates Feature-Selective Responses in Human Cortex," was published yesterday in the Journal of Cognitive Neuroscience.

Any organism's current behavioral state influences brain activity and perceptions of the environment. But, how do various intensities of physical activity influence the human brain? Is moderate-to-vigorous physical activity (MVPA) always the most effective way to dynamize the brain benefits of exercise? Or does low-intensity exercise have significant brain benefits, too?

Because of the prescriptive importance of answering these questions, neuroscientific research continues making strides to pinpoint clear-cut brain benefits of various intensities of aerobic exercise. Interestingly, in the past week, two different studies have identified that low-intensity physical activity appears to have specific brain benefits that have gone under the radar until now.

Earlier this week, researchers in Denmark reported that lower intensity physical activities improve math performance for first graders when motor-enriched learning is integrated into the classroom. Contrary to previous hypotheses, the Danish researchers found that low-intensity exercise may be more beneficial to academic learning than high-intensity aerobic activity for some children.

In the aforementioned study on visual processing, UC Santa Barbara psychology and brain scientists Barry Giesbrecht and Tom Bullock from the UCSB Attention Lab recruited 18 volunteers to test the link between various intensities of physical activity and brain activity.

During the experiment, participants rode a stationary bicycle at varying aerobic intensities while wearing an EEG cap to monitor brain activity as they performed a variety of visual discrimination tasks. Visual tasks were performed while resting and during bike intervals at both low- and high-intensity output.

As noted earlier, neurons in the visual cortex became most sensitive to visual stimuli during the low-intensity exercise condition relative to both other conditions.

Locomotion Enhances Visual Perception Across Species, Including Humans

Chetty Thomas/Shutterstock
Source: Chetty Thomas/Shutterstock

Previous research on mice and flies identified that physical activity increases neuron firing rates in brain areas associated with visual processing. However, until now, scientific research on the impact of aerobic activity on visual processing in humans has been scarce. Therefore, Giesbrecht and Bullock were curious to see if physical activity boosts visual processing in the human brain by increasing neuron firing rates in the visual cortex.

A wide range of previous studies have found that during any type of locomotion, there is a spike in neural responses within the sensory cortex of invertebrates and nonhuman mammals.

Although there are significant differences in the structure of visual pathways in various species, this UCSB study provides empirical evidence that neural mechanisms in the human visual cortex are stimulated by locomotive behavior. Exercise-induced enhancement of visual processing appears to occur across species, including humans.

Based on our evolutionary and neurobiological roots, it would make sense that our hunter-gatherer ancestors relied on enhanced visual processing during all forms of locomotion as they traversed diverse landscapes hunting for prey and scavenging for food. 

In a statement, co-author Barry Giesbrecht, professor in UCSB's Department of Psychological and Brain Sciences, touched on the evolutionary roots linking locomotion and enhanced visual processing.  

"There’s an interesting cross-species link that shows these effects of arousal might have similar consequences for how visual information is processed. That implies the evolution of something that might provide a competitive advantage in some way.”

The latest research from UCSB's Attention Lab underscores the importance of physical activity in a fresh light. As Giesbrecht concluded, "The benefits of brief bouts of exercise might provide a better and more tractable way to influence information processing—versus, say, brain training games or meditation—and in a way that's not tied to a particular task."

In recent years, countless studies have illuminated the widespread brain benefits of moderate to vigorous physical activity. Now, there is growing evidence that low-intensity physical activity also has significant brain benefits that require further investigation. 

The next frontier of scientific research on the brain benefits of physical activity will focus on pinpointing specific dose-responses to various aerobic intensities and optimal durations of exercise to achieve targeted outcomes. Stay tuned for future research on this topic. 

References

Tom Bullock, James C. Elliott, John T. Serences, Barry Giesbrecht. Acute Exercise Modulates Feature-selective Responses in Human Cortex. Journal of Cognitive Neuroscience, 2016; 1 DOI: 10.1162/jocn_a_01082

Mikkel M. Beck, Rune R. Lind, Svend S. Geertsen, Christian Ritz, Jesper Lundbye-Jensen, Jacob Wienecke. Motor-Enriched Learning Activities Can Improve Mathematical Performance in Preadolescent Children. Frontiers in Human Neuroscience, 2016; 10 DOI: 10.3389/fnhum.2016.00645

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