'Cross-talk' in the brain responsible for slowed responses in old age, study says

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What we might have here is a failure to communicate: Breakdowns in certain brain connections could be responsible for slowed physical reaction times as we age, new research suggests.

“Cross-talk” occurs in the brain when one side sends out signals that control movements on the opposite side of the body—for example, when the left side of the brain sends signals that control movements on the right side of the body. This signal chatter is regulated by an area of the brain called the corpus callosum, according to researchers at the University of Michigan. But as we age, the brain's ability to regulate the cross-talk diminishes. As a result, both sides of the brain send signals when one side of the body moves.

Researchers compared the response times and brain activity of a group of 65 to 75-year-olds with those of a group of 20 to 25-year-olds. The researchers used computer joysticks to measure physical response times, and functional MRIs to measure brain blood flow and activity. As regulation of the cross-talk lessened and both sides began chatting at once, physical response time slowed, according to the report. Full implications of the discovery were not known but give researchers another springboard from which to study aging, the brain and behavior. The study appears in a recent edition of the journal Frontiers in Systems Neuroscience.