Teenagers and young adults who suffered a stroke in the left side of their brains around the time of birth use the right side of their brains for language in an exact, mirror opposite region to the left normal language areas, reports a team of researchers from Georgetown University Medical Center.
These findings demonstrate how “plastic” brain function is in infants, says cognitive neuroscientist Elissa L. Newport, PhD, professor of neurology at the School of Medicine, and director of the Center for Brain Plasticity and Recovery at Georgetown University and MedStar National Rehabilitation Network.
This finding makes sense in very young brains, Newport explains. “Imaging shows that children up to about age four can process language in both sides of their brains, and then the functions split up: the left side processes sentences and the right processes emotion in language.”
Newport’s study used imaging to study the brains of 12 individuals, aged 12 to 25, who had a left-brain perinatal stroke, finding that all of them used the right side of their brains for language. “Their language is good— normal,” she says, as are their basic cognitive functions like language comprehension and production.
This study was more carefully controlled in terms of the types and areas of injury included than were previous studies, which had reported inconsistent findings about the brain’s ability to relocate language functioning.
“We believe there are very important constraints to where functions can be relocated,” Newport says. “There are very specific regions that take over when part of the brain is injured, depending on the particular function.” Her research suggests that while “these young brains were very plastic and could relocate language to a healthy area, it doesn’t mean that new areas can be located willy-nilly on the right side” she explains.
The research team is also collaborating on studies looking for the molecular basis of plasticity in young brains, as such information might help switch on plasticity in adults who have suffered stroke or brain injury.