NEW YORK (Reuters Health) - Understanding exactly how the brain develops from birth has confounded scientists for decades, largely because tools to finely measure brain activity have been lacking. With regard to language, earlier research on the subject has led some scientists to believe that the brain's language centers develop around the time a person is born.

Writing in the May 24th issue of the journal Science, researchers report that language centers in the brain actually develop more slowly during childhood, and may not be completely formed even by age 10. The investigation revealed that adults and children as old as 10 are using slightly, but nevertheless different, regions of the brain when performing first-grade-level word tasks.

According to lead researcher Dr. Brad L. Schlaggar of Washington University in St. Louis, Missouri, knowing exactly how the brain masters language skills may help researchers better understand learning disorders like dyslexia.

Schlaggar and his team evaluated brain scans taken while adults aged 18 to 35 and children aged 7 to 10 performed word tasks. The brain scanning technique, known as fMRI, measures activity in different parts of the brain.

The children and adults were asked to think of verbs, rhyming words and opposite words when presented with a word, Schlaggar told Reuters Health in an interview.

Typical words for the verb-generating task, for example, are nouns like cake, nose and water, Schlaggar explained. The participants were asked to name a verb to go with the noun, "like what you might do with it or what it does." Appropriate responses, then, would include bake, smell and drink, respectively, he added.

Upon review of the data, the investigators found that "when children and adults perform identical reading tasks, and perform these tasks equally well, they use similar, but not identical parts of the brain," Schlaggar told Reuters Health.

"Specifically, there are places in the brain that the adults use and the children do not--a region in the left frontal lobe for example," he said. There also are places in the brain children use much more than adults do--"a region in the left extrastriate cortex--in the back of the brain where processing of visual information occurs," he added.

Knowledge of what brain activity looks like for a given mental function--like reading words--at a particular point in development will help scientists to understand what goes wrong in different developmental disorders, such as dyslexia and other learning disabilities, Schlaggar pointed out.

"This idea is interesting from a clinical neuroscience perspective in that to come up with rational interventions, we should have a clear idea of what goes wrong in development," he said. "And to study the effect of an intervention, we should be able to measure what happens in the brain as a consequence of the intervention."

SOURCE: Science 2002;296:1476-1479.

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