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November 2005 Issue

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New Hope Offered for Brain Injury Sufferers

Published November 2005

Scientists have found that the site in the brain that controls language in right-handed people shifts with aging--a discovery that might offer hope in the treatment of speech problems resulting from traumatic brain injury or stroke.

The shift was documented by UC researchers led by Jerzy Szaflarski, MD, PhD, of the Department of Neurology, and Scott Holland, PhD, of the departments of biomedical engineering, pediatrics and radiology. Dr. Holland also heads the Pediatric Brain Imaging Research Program at Cincinnati Children's Hospital Medical Center.

Their results will be published in the February 2006 edition of the journal Human Brain Mapping.

While the site of language activity in right-handed people is originally the left side of the brain, the researchers report, starting as early as age 5 language gradually becomes a function shared by both sides. Between the ages of about 25 to 67, the site becomes more evenly distributed, until language activity can be measured in both hemispheres simultaneously.

This, the researchers say, may explain why children who have had a large portion of one side of the brain surgically removed often recover completely.

"This knowledge may give new hope for rehabilitation of brain function in adults after stroke or traumatic brain in-juries," says Dr. Szaflarski. "The fact that language adaptability is seen even in the older people supports the notion that these patients can be rehabilitated and returned to productive life, possibly even after a devastating stroke."

Scientists have long thought that the hemisphere or side of the brain that controls language and speech is determined before birth. Most people are right-handed and demonstrate more activity during language or speech in the brain's left hemisphere. In left-handed people language centers are located more symmetrically.

Drs. Szaflarski and Holland studied brain activity in 177 right-handed children and adults, aged 5 to 67, using functional magnetic resonance imaging (fMRI). The technique shows brain activity, in this case language tasks such as reading or speaking, in a specific color.

"Our research revealed that language activity in the brain increases in the dominant hemisphere from age 5 until about 25," Dr. Szaflarski says, "which may be related to improving linguistic skills and maturation of the central nervous system."

From around age 5 until about 25, says Dr. Szaflarski, language capacity in right-handers grows stronger in the brain's left hemisphere. Similarly, fMRI shows brain activity increasing in the right hemisphere of left-handed persons until age 25.

Drs. Szaflarski and Holland and their colleagues are also investigating how the brain handles language when it is damaged by a stroke or traumatic brain injury.

In children, Dr. Szaflarski says, the brain seems able to reorganize and shift the work load to the uninjured side. In adults, this doesn't happen as easily.

With a view to developing better treatment for brain injury in children and adults, the researchers are now trying to learn at what age this transition occurs.

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