In the event of brain damage, children recover better than adults at the level of language. According to a US study, the explanation lies in the fact that children use both hemispheres in understanding sentences, while adults use only the left.
Adults only use the left hemisphere of their brain to process understanding spoken sentences. However, young children use both hemispheres. This is a discovery that could help explain why some individuals who suffered a left hemisphere lesion at birth can still acquire language skills. In a publication in the journal PNAS on September 8, 2020, a team of researchers from the Georgetown University Medical Center (United States) reported on their progress. The researchers used functional MRI to examine 39 children and 14 adults aged 4 to 29.
Science has long known that language-related abilities are on the left hemisphere side in most neurologically healthy adults. This hemisphere therefore plays a crucial role in the understanding of sentences. However, there are other abilities such as the processing of prosody and discourse devices which are more to the right.
Just like adults, babies and toddlers prefer the left hemisphere for understanding sentences. However, there was still an unknown that in children damage to the right hemisphere can cause language deficits.
Functional MRI can visualize oxygenation and therefore the activation of brain areas over time. The volunteers who took part in the experiment heard sentences from inside the machine. If the sentence was correct, individuals had to press a button. According to the researchers, this is a very reliable language comprehension task. The data collected allowed them to analyze the brains of the volunteers as a whole. The goal? Identify areas of the brain in which language activation was correlated with age.
According to the results, language analysis in children leaned more towards the side of the left hemisphere. However, a significant proportion of children showed significant activation in certain areas of the right hemisphere . The directors of the study have also confirmed that this involvement of the right hemisphere decreases over time in favor of the left hemisphere, and this, until an absence in adulthood.
For scientists, this is very good news for young children with neural damage. After this kind of incident, the initial use of both hemispheres makes it possible to maintain a compensation mechanism. Thus, a child suffering a lesion caused by a perinatal attack will learn language thanks to his right hemisphere. In the case of a child born with cerebral palsy, this child will develop the necessary cognitive abilities in the right hemisphere.
This study therefore makes it possible to understand that the right hemisphere is a substitute for the left hemisphere during childhood. This then explains why language recovery following left hemisphere damage is much better in children . The researchers want to continue their research in order to confirm their initial results. New tests to come will concern adults and adolescents who suffered a stroke at birth.
