New research provides evidence that exercise enhances the plasticity of the adult brain.
That’s important because learning, memory, and brain repair depend on plasticity, the ability of our neurons to change and adapt with experience.
The new study, which focused on the visual cortex, could bring hope for people with conditions including amblyopia (sometimes called lazy eye), traumatic brain injury, and more, according to researchers.
“We provide the first demonstration that moderate levels of physical activity enhance neuroplasticity in the visual cortex of adult humans,” said Dr. Claudia Lunghi of the University of Pisa in Italy.
“By showing that moderate levels of physical activity can boost the plastic potential of the adult visual cortex, our results pave the way to the development of non-invasive therapeutic strategies exploiting the intrinsic brain plasticity in adult subjects.”
The plastic potential of the cerebral cortex is greatest early in life, when the developing brain is molded by experience, she said, noting that brain plasticity is generally thought to decline with age. This decline in the brain’s flexibility over time is especially pronounced in the sensory brain, which displays far less plasticity in adults than in younger people.
The latest studies follow on previous studies conducted by Alessandro Sale, Ph.D., of Italy’s National Research Council, in laboratory animals. Those studies showed that animals performing physical activity, for example rats running on a wheel, showed elevated levels of plasticity in the visual cortex and improved recovery from amblyopia in comparison to more sedentary animals.
To discover whether the same might hold true for people, Lunghi and Sale measured the residual plastic potential of the adult visual cortex in humans using a test of binocular rivalry.
Most of the time, our eyes work together. But when people have one eye patched for a short period of time, the closed eye becomes stronger as the visual brain attempts to compensate for the lack of visual input.
The strength of the resulting imbalance between the eyes is a measure of the brain’s visual plasticity and can be tested by presenting each eye with incompatible images, the researchers explained.
In the new study, Lunghi and Sale put 20 adults through this test twice. In one deprivation test, participants with one eye patched watched a movie while relaxing in a chair. In the other test, participants with one eye patched exercised on a stationary bike for 10-minute intervals during the movie.
The results were clear: Brain plasticity was enhanced by the exercise, the study found.
“We found that if, during the two hours of eye patching, the subject intermittently cycles, the perceptual effect of eye patching on binocular rivalry is stronger compared to a condition in which, during the two hours of patching, the subject watches a movie while sitting on a chair,” the researchers said in the study.
“That is, after physical activity, the eye that was patched is strongly potentiated, indicating increased levels of brain plasticity.”
While further study is needed, the researchers said they think that this effect may result from a decrease with exercise in the inhibitory neurotransmitter GABA. As concentrations of this inhibitory nerve messenger decline, the brain becomes more responsive.
Regardless of the mechanism, the findings suggest that exercise plays an important role in brain health and recovery. This could be especially good news for people with amblyopia, which is generally considered to be untreatable in adults.
“Our study suggests that physical activity, which is also beneficial for the general health of the patient, could be used to increase the efficiency of the treatment in adult patients,” Lunghi says. “So, if you have a lazy eye, don’t be lazy yourself!”
The study, which received funding from the European Research Council, was published in the Cell Press journal Current Biology.
Source: Current Biology, Cell Press