After a stroke in the brain of an infant, right side

WASHINGTON – A clinical study by researchers at Georgetown University Medical Center found that for children who had suffered a major stroke in the left hemisphere of their brain within days of birth, the infant brain was sufficiently ” plastic” so that the right hemisphere acquires the linguistic abilities usually handled by the left side while also retaining its own linguistic abilities.

The left hemisphere of the brain is normally responsible for sentence processing (understanding words and sentences as we listen to speech). The right hemisphere of the brain is normally responsible for processing the emotion of the voice – is it happy or sad, angry or calm. This study aimed to answer the question “what happens when one of the hemispheres is injured at birth?”

The findings appear in PNAS the week of October 10, 2022.

The participants in this study developed normally during pregnancy. But around birth, they had a major stroke, which would have debilitating consequences in adults. In infants, a stroke is much rarer, but occurs in about one in four thousand births.

The researchers studied perinatal arterial ischemic stroke, a type of brain injury that occurs around the time of birth in which blood flow is cut off to part of the brain by a blood clot. The same type of stroke occurs much more frequently in adults. Previous studies of brain injury in infants have included multiple types of brain injury, but the focus in this study on one specific type of injury allowed the authors to find more consistent effects than in previous work.

“Our most important finding is that brain plasticity, specifically the ability to reorganize language to the opposite side of the brain, is certainly possible early in life,” says Elissa Newport, Ph.D., director of the Brain Plasticity and Recovery Center at Georgetown Medical Center, a professor in the departments of Neurology and Rehabilitation Medicine and first author of this study. “However, this early language plasticity is limited to one region of the brain. The brain is not able to reorganize injured functions anywhere, because more drastic reorganization is not possible even in early life. This gives us great insight into areas we could focus on for potential breakthroughs in the development of recovery techniques in adults as well.

The investigators recruited people from across the United States who all had moderate to large strokes in the cortex region of their left hemisphere at the time of birth. To assess the long-term results of their language abilities, participants took language tests between the ages of 9 and 26 and were compared to their nearby healthy siblings. They were also scanned in an MRI to reveal which areas of the brain were involved in understanding the sentences.

The participants and their healthy siblings all performed the language tasks almost perfectly. The main difference was that stroke participants processed the sentences on the right side of the brain while their siblings processed sentences on the left side. Stroke participants showed a very consistent pattern of language activation in the right hemisphere, regardless of the extent or location of stroke damage to the left hemisphere. Only one of the 15 participants, who had the smallest stroke, did not show clear dominant right-hemisphere activation.

“It is also remarkable that many years after their stroke, our participants are all highly functioning adults. Some are honor students and others are working or have graduated with a master’s degree,” says Newport. “Their achievements are remarkable, especially since some of their parents were told when they were born that their strokes would lead to lifelong disabilities.”

In future studies, researchers hope to better understand why the left hemisphere consistently becomes dominant in healthy brains, but consistently loses to the right hemisphere when there is a large left-hemisphere stroke. An additional question of particular interest – and clinical importance – is why left hemisphere language can successfully reorganize to the right hemisphere if injuries occur very early in life but not later. Research on stroke recovery and grief treatment in adults suggests that plasticity shrinks with age, which Newport hopes to study as it could be of great benefit and potential therapeutic interest for adults. adult stroke survivors.

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The researchers are very grateful to the participants and their families who made invaluable contributions to this work.

Besides Newport, other Georgetown University authors include Anna Seydell-Greenwald, Barbara Landau, Peter E. Turkeltaub, Catherine E. Chambers, Kelly C. Martin, and Rebecca Rennert. Margot Giannetti and Alexander W. Dromerick are at Georgetown University and MedStar National Rehabilitation Hospital. Rebecca N. Ichord is at the University of Pennsylvania Perelman School of Medicine and Children’s Hospital of Philadelphia. Jessica L. Carpenter is at the University of Maryland in Baltimore. William D. Gaillard and Madison M. Berl are at Children’s National Hospital and Center for Neuroscience, Washington, DC.

This work was supported by funds from Georgetown University and MedStar Health; by the Solomon James Rodan Pediatric Stroke Research Fund, the Feldstein Veron Innovation Fund and the Bergeron Visiting Scholars Fund at the Center for Brain Plasticity and Recovery; by American Heart Association grant 17GRNT33650054; by NIH grant P50HD105328 to DC-IDDRC of National Children’s Hospital and Georgetown University; and by NIH grants K18DC014558, K23NS065121, R01NS244280, and R01DC016902.

Newport reports having no personal financial interests related to the study.

About Georgetown University Medical Center

As a premier academic health and science center, Georgetown University Medical Center synergistically delivers excellence in education – training physicians, nurses, health administrators and medical professionals. health professionals, as well as biomedical scientists – and cutting-edge interdisciplinary research collaboration, strengthen our capacity for basic science and translational biomedical research to improve human health. Patient care, clinical research and education are conducted with our academic health system partner, MedStar Health. GUMC’s mission is carried out with a strong emphasis on social justice and a dedication to the Catholic and Jesuit principle of cura personalis – or “care for the whole person”. GUMC includes the School of Medicine, School of Nursing, School of Health, Biomedical Higher Education, and Georgetown Lombardi Comprehensive Cancer Center. Designated by the Carnegie Foundation as a doctoral university with “very high research activity”, Georgetown is home to a clinical and translational science award from the National Institutes of Health and a comprehensive cancer center designation from the National Cancer Institute. Connect with GUMC on Facebook (Facebook.com/GUMCUpdate) and on Twitter (@gumedcenter).


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