Juggling is Mind-Altering Experience

Newly trained jugglers show changes in shape of the brain

FRIDAY, Jan. 30, 2004 (HealthDayNews) -- In a discovery that could change assumptions in the world of neuroscience, European researchers have found human brains actually change shape while learning a complicated skill such as juggling.

Brain scans reveal that gray matter expands in people as they learn how to juggle, then retracts as they fail to practice. The findings appear to bring scientists closer to answering a major question: Do humans gain more brain cells over time, or are they stuck with what nature gave them?

The mystery remains, but by unearthing evidence of physical changes in the brain, "we challenge our view of the human central nervous system," says study co-author Dr. Arne May, a researcher at the University of Regensburg in Germany. "Human brains probably must be viewed as dynamic, changing with development and normal learning."

Scientists have long debated what happens in the brain during learning. Does the brain create new neurons to handle new skills, or, as some scientists have suggested, does the brain just shuffle around its resources?

About 10 years ago, researchers noticed that regions of the brain devoted to a task became larger as the skill level increased, says Rachael Seidler, an assistant professor of psychology and kinesiology at the University of Michigan. But it's been difficult to prove the brain is becoming larger, not just reorganizing itself, she says.

Meanwhile, studies have shown that adult animals can grow new neurons, just as they regenerate other kinds of cells. "The growth of new neurons can be influenced by things like exercise and whether the animal lives in an enriched environment," Seidler says. "It's been hard to show in humans."

In the new study, researchers divided 24 volunteers -- 21 women and three men, average age 22 -- into two groups. Members of one group were given three months to learn how to juggle three balls in the air for at least a minute; the others didn't learn how to juggle. The volunteers then had brain scans.

The findings appear in a recent issue of Nature.

In the jugglers, the researchers found structural changes in the brain regions devoted to two kinds of tasks -- perception and prediction of the movement of objects. The regions expanded after they learned how to juggle then grew smaller after they stopped practicing the skill. According to the researchers, this contradicts the belief that only the aging process and disease can change the structure of the human brain.

The study doesn't prove the brain actually creates new cells, but Seidler says it hints that may be the case. "This is getting at the question, are we born with a certain number of neurons, and that's all we have?" she says. "It's the step in the direction of showing that the adult human brain may add new neurons."

If the brain can regenerate itself, scientists could use that knowledge to develop treatments for diseases, she says. The idea of new neurons could also change the way people feel as they grow old. "It's a much more positive view of aging," she adds.

More information

Learn more about the brain from Harvard University's Whole Brain Atlas or BrainConnection.com.

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