Studies have shown that exercise can remodel the brain by prompting creation of new brain cells and inducing other changes.
Now it appears that inactivity, too, can remodel the brain, according to a new report.
The study -- conducted in rats but likely with implications for people, the researchers say -- found that being sedentary changes the shape of certain neurons in ways that significantly affect not just the brain but the heart as well. The findings may explain, in part, why a sedentary lifestyle is so bad for us.
For a study published in The Journal of Comparative Neurology, scientists at Wayne State University School of Medicine and other institutions gathered a dozen rats. They settled half of them in cages with running wheels. They were soon covering about 3 miles a day.
The other rats remained sedentary.
After almost three months, the animals were injected with a special dye that colors certain neurons in the brain. Using a computer program to recreate the inside of the animals' brains, the scientists established that the neurons in the brains of the running rats were still shaped much as they had been.
But many neurons in the brains of the sedentary rats had sprouted far more new tentaclelike arms known as branches. Branches connect healthy neurons into the nervous system. But these neurons now had more branches than normal neurons would have, making them more sensitive and apt to zap scattershot messages into the nervous system.
In effect, these neurons changed in ways that made them likely to overstimulate the sympathetic nervous system, potentially increasing blood pressure and contributing to development of heart disease.
–Gretchen Reynolds, The New York Times
he New York Times