Children, unlike adults, use both brain hemispheres to understand language.


Examples of individual activation maps in each age group. Strong activation in the right-hemisphere homolog of left-hemisphere language regions is evident in the youngest children, declines in age, and is completely absent in most adults. Sincerely: Alyssa Newport

Georgetown University Medical Center neuroscientists say infants and young children have a superpower in their brains. While adults process most discrete neural functions in specific areas in one or two hemispheres of their brain, youngsters use both the right and left hemispheres to perform the same task. This finding suggests a possible reason that children recover from nerve injury much more easily than adults.

The study published in September 7, 2020 PNAS One task focuses on language, and finds that to understand language (more specifically, processing spoken sentences), children use both hemispheres. This finding fits with prior and ongoing research, led by Georgetown Neurology Professor Alyssa L. Newport, Ph.D., a former postdoctoral fellow, Olumide Oluled, M.D., Ph.D., and neurology assistant professor Anna Greenad, Ph.D.

“This is great news for children who experience a nerve injury,” says Newport, director of the Center for Brain Plasticity and Recovery, a joint venture between Georgetown University and the Medstar National Rehabilitation Network. “The use of both hemispheres provides a mechanism to compensate after a nerve injury. For example, if the left hemisphere is damaged by a perinatal stroke – which occurs just after birth – a baby is in the right hemisphere. Will learn the language using. A child who is born with it. Cerebral palsy that damages only one hemisphere can develop the necessary cognitive abilities in the other hemisphere. Our study demonstrates how this is possible. ”

His study solves a mystery in which longtime physicians and neuroscientists have a mess, Newport says.

In almost all adults, sentence processing is possible in the left hemisphere, according to brain scan research and clinical findings of language loss in patients who suffered left hemisphere stroke.

But in very young children, there is a lack of language due to damage in either hemisphere; Language can be cured in many patients, even if the left hemisphere is severely damaged. These facts suggest that language is distributed to both hemispheres early in life, Newport says. However, traditional scanning had not revealed the details of these events until now. Newport explains, “It was unclear whether strong left dominance for language exists at birth or appears gradually during development.”

Now, analyzed in a more complex manner using functional magnetic resonance imaging (fMRI), researchers have shown that adult lateralization patterns are not established in young children and that both hemispheres participate in language during early development .

She states that brain networks localize specific functions in one or the other hemisphere but are not complete until the child is 10 or 11 years old. “We now have a better platform on which to understand brain injury and recovery.”

Originally Allied, William D. Gillard, MD, and Madison M. Burl, PhD, who is from Children’s National Medical Center, which includes 39 healthy children, ages 4–13; The lab at Newport added 14 adults, ages 18–29, and conducted a series of new analyzes from both groups. The participants were given a well-studied sentence comprehension task. The analysis examined fMRI activation patterns in each hemisphere of individual participants rather than looking at total lateralization in group averages. The investigators then compared language activation maps for four age groups: 4–6, 7–9, 10–13 and 18–29. Penetrance maps revealed the percentage of subjects in each age group with significant language activation in each tone of each hemisphere. (A tone is a small dot in a pixel-like brain image on a television monitor.) Investigators performed a whole-brain analysis across all participants to identify areas of the brain in which language activation was correlated with age .

Researchers found that, at the group level, even young children show left-lateral language activation. However, a large proportion of the youngest children also show significant activation in the respective right-hemisphere regions. (In adults, the corresponding region in the right hemisphere is activated in quite different tasks. For example, processing the emotions expressed with the voice. In young children, the area in both hemispheres interprets the meaning of each sentence as well. Engaged in understanding. Emotional impact.)

Newport believes that “high levels of right hemisphere activation in a sentence processing task and a slow decline in this activation on development are reflections of changes in the neural distribution of language tasks and not mere developmental changes in sentence comprehension strategies.”

She also states that, if the team were able to do the same analysis in younger children, “chances are that we are more functional of right hemisphere in language processing than our youngest participants (ages 4–6 years)” Will see participation. Years old).

“Our findings suggest that normal involvement of the right hemisphere in language processing during very short childhoods may allow maintenance and enhancement of development of the right hemisphere when the left hemisphere is injured,” Newport says.

Investigators are now investigating language activation in adolescents and young adults who have had a major hemispheric stroke at birth.


Brain restructuring predicts language production


more information:
Olumide a. Olulad et al., “The Neural Basis of Language Development: Changes in Lateralization with Age,”. PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.1905590117

Provided by Georgetown University Medical Center

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