Researchers from Georgetown University medical center have found that young children use both the right and left sides of their brain to process language, unlike adults who almost exclusively use the right side.
For the study, the researchers recruited 39 healthy children aged between 4 and 13. They also analyzed 14 adults aged between 18 and 29. Each participant was given a sentence comprehension task while undergoing an fMRI scan to monitor their brain activity in each hemisphere.
The researchers then compared brain activity patterns between four age groups: 4-6, 7-9, 10-13, and 18-29. In the end, they found that, like in adults, the left hemisphere in young children tends to be more activated by language than the right hemisphere. In the youngest group of children, however, the researchers found that the right side of the brain was also similarly activated to the left when processing meaning.
For comparison, the same area of the right side of the brain, when activated in adults, corresponds more to processing emotions expressed by the voice, as opposed to the meaning of words. As such, the researchers say that in very young children, both hemispheres are involved both in comprehending verbal meaning and vocally-expressed emotion.
The researchers write that the high levels of right hemisphere activation in language processing during youth and its decline over time reflect changes in the neural distribution of language functions, as opposed to a shift in comprehension strategy.
“Our findings suggest that the normal involvement of the right hemisphere in language processing during very early childhood may permit the maintenance and enhancement of right hemisphere development if the left hemisphere is injured,” says lead author of the study, Elissa L. Newport.
To see whether this is the case, the researchers are now investigating language activation in teenagers and young adults who experienced a major left hemisphere stroke early in life.