Neurology professor and principal investigator Elissa Newport, at Georgetown University in Washington, US, said it was yet unclear whether strong left dominance for language is present at birth or appears gradually during development.

“However, use of both hemispheres provides a mechanism to compensate after a neural injury,” said Newport.

As specific brain networks which cause lateralisation are only complete at around 10 or 11 years of age, Newport and colleagues worked with 39 children aged 4 through to 13, and 14 adults aged 18-29 – they were each given a sentence comprehension task and had their brain activity (language comprehension) examined as they went about it.

Functional magnetic resonance imaging (fMRI) data showed left lateralisation of language processing in the brains of the children. There was also heavy activation in their right hemispheres, which was not seen in adults.(This area of the brain is involved in processing the emotional content of conversation in adults.)

Newport explained that higher levels of right hemisphere activation in a sentence processing task and the slow decline in this activation across the ages are likely reflections of changes in the neural distribution of language functions, and not merely developmental changes in sentence comprehension strategies. The use of both hemispheres of the brain may also be the reason why children grasp language faster than many adults.