Researchers have found that when a newborn suffers a stroke in the left brain, the right part of the brain takes over the language processing ability throwing new light on how neurons rewire in the brain in case of an injury and opening up potential treatment options.
In the study published on October 10 in PNAS (Proceedings of the National Academy of Sciences), researchers say that in the event of such a stroke, the right part of the newborn’s brain steps in to compensate for the loss and manages both the left and right brain’s language processing mechanisms as the child grows up.
Normally, language is processed by both the left and right parts of the brain. The left comprehends words and sentences in a speech, while the right picks up the tone and emotion (such as a happy or angry tone).
“Plasticity in the brain, specifically the ability to reorganise language to the opposite side of the brain in early life is possible,” says Prof Elissa Newport, the study’s first author, from the Centre for Brain Plasticity and Recovery at Georgetown Medical Centre, USA, in a statement.
For this study, researchers identified people with perinatal arterial ischemic stroke, a rare type of stroke that strikes one in 4,000 newborns. The stroke is caused by a blood clot that cuts off blood flow to the left half of the brain.
To assess long-term outcomes in their language abilities, participants were given language tests at 9 to 26 years of age and were compared to their close-in-age healthy siblings.
MRI scans recorded the brain activity of both the groups while performing the test to reveal which brain areas were involved in sentence comprehension, the statement said. The researchers found that both groups performed equally in the language test. In the healthy siblings, the left part of the brain activated during language processing, while participants with a history of stroke processed the sentences on the right side of the brain.
Newport said that early plasticity for language is restricted to a specific brain region. Despite experiencing strokes, these individuals are highly functional adults. “Their achievements are remarkable, especially since some of their parents had been told when they were born that their strokes would produce life-long impairments,” she added.
While the study’s most important conclusion is that plasticity in the brain, specifically the ability to reorganise language to the opposite side of the brain, “is possible early in life”, the brain is not able to reorganise injured functions (of itself) just anywhere, she said.