SCIENCE

-- Juliet Eilperin

Blame Bad Golf Swing on Brain

If you cannot get your golf swing right, the problem may be in your head.

No matter how much a person practices a movement, the brain plans and processes it differently each time, leading to inevitable variations, according to a study published in the Dec. 21 issue of the journal Neuron. The inconsistency -- in a golf swing, a free throw or a fastball -- is a product of the mind, not just the muscles.

Stanford University researchers arrived at this conclusion after studying the brains of rhesus monkeys. The monkeys were trained to reach quickly for a red spot and slowly for a green one, earning juice as a reward. Researchers found that the animals seldom reached with the same speed, regardless of the target color. And the variation coincided with variations in brain activity before the monkeys began reaching.

"In general, when we fail at a well-practiced movement, we tend to assume that something went wrong during execution," the authors wrote. "Our results indicate that it is at least as likely that something went wrong during motor preparation."

Practice can help, but it cannot make the motion perfect. The inevitable variations may be an outgrowth of evolution. Because predators never face exactly the same conditions in pursuing prey, nature rewards those who improvise.

"The nervous system was not designed to do the same thing over and over," said Mark Churchland, a postdoctoral student and a co-author of the study. "The nervous system was designed to be flexible. You typically find yourself doing things you've never done before."

-- Christopher Lee