Language-Control Shift May Aid Rehab

Scientists have found that the region in the brain that controls language in right-handed people shifts with aging--a finding that might have potential for the treatment of speech disorders caused by traumatic brain injury or stroke.

The shift was documented by scientists led by Jerzy Szaflarski, M.D., Ph.D., assistant professor in the department of neurology at the University of Cincinnati (UC, OH, USA) Academic Health Center, and Scott Holland, Ph.D., professor in the UC departments of biomedical engineering, pediatrics, and radiology. Their results are to be published in the February 2006 issue of the journal Human Brain Mapping.

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

This, according to the investigators, may clarify why young children who have had a large portion of one side of the brain surgically removed frequently recover completely. Dr. Szaflarski said, "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 believed that the hemisphere or side of the brain that controls language and speech is determined before birth. Most individuals are right-handed and demonstrate more activity during speech in the left hemisphere of the brain. In left-handed individuals, language centers are located more symmetrically.

Drs. Szaflarski and Holland assessed brain activity in 177 right-handed children and adults aged five to 67 at Cincinnati's University Hospital and Cincinnati Children's utilizing functional magnetic resonance imaging (fMRI). This modality shows brain activity, in this instance, language tasks such as reading or speaking, in a specific color.

From around age five until about 25, according to Dr. Szaflarski, language ability in right-handers grows stronger in the left hemisphere of the brain. Similarly, fMRI demonstrated increasing brain activity in the right hemisphere of left-handed persons until age 25. In children, according to Dr. Szaflarski, the brain appears able to reorganize and shift the functions to the uninjured side. In adults, this does not occur as easily. Looking to develop better treatments for brain injury in children and adults, the researchers are now trying to determine at what age this transition occurs.




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