However, these earlier studies of the plasticity of the brain generally focused on the gray matter, which contains the famous little gray cells, or neurons, that enable and generate thoughts and memories. Less research has gone into the white matter, the wiring of the brain. The white matter is mainly made up of fat-covered nerve fibers known as axons, connects neurons, and is essential for brain health. But it can be fragile, thin, and develop small lesions as we age, dilapidations that can herald cognitive decline. Worryingly, it was also viewed as relatively static, with little plasticity or the ability to adapt a lot to our lives.
However, Agnieszka Burzynska, professor of neuroscience and human development at Colorado State University in Fort Collins, suspects science is underestimating white matter. “It was like the ugly, neglected stepsister,” the gray matter, she says, ignored and misjudged. She thought it likely that the white matter possessed as much plasticity as its gray counterpart and could remodel itself, especially when people began to move.
For the new study, which was published online in NeuroImage in June, they, along with their PhD student Andrea Mendez Colmenares and other colleagues, set out to improve people’s white matter. They started by collecting nearly 250 older men and women who were sedentary but otherwise healthy. In the lab, they tested the current aerobic fitness and cognitive abilities of these volunteers, and also measured the health and function of their white matter with an ingenious form of MRI brain scan.
They then divided the volunteers into groups, one of which began a supervised program of stretching and balance training three times a week to serve as an active control. Another started walking briskly together for about 40 minutes three times a week. And the last group started dancing and met three times a week to learn and practice line dances and group choreographies. All groups trained for six months and then returned to the lab to repeat the tests from the start of the study.
And many had changed their bodies and brains, the scientists found. As expected, the walkers and dancers were aerobically fitter. More importantly, its white matter seemed renewed. In the new scans, the nerve fibers looked larger in certain parts of her brain and all of the tissue lesions had shrunk. These desirable changes were most common among hikers, who now also got better results on memory tests. The dancers in general didn’t.