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Wednesday, November 1 2023

Brain maturation: researchers uncover an important mechanism occurring in adolescence

Montréal, November 1st, 2023 – What determines the structure of the human brain and how it evolves during adolescence? In a new study, postdoctoral fellow Zhijie Liao, researcher Tomas Paus and their colleagues highlight the close link between brain activity and one of the brain’s maturation processes, cortical thinning.

Cortical thinning and brain asymmetry

Like all parts of the human body, the brain’s hemispheres are not perfectly symmetrical. Using magnetic resonance imaging (MRI) data from the brains of a cohort of 532 teenagers (IMAGEN cohort), the study has shown for the first time that this asymmetry changes with age, and that each region of the cortex and each hemisphere thins at a different rate. The right hemisphere thins faster than the left, with a few exceptions. But even within each hemisphere, thinning occurs at different rates from one region to another.

“So the differences in thickness between the two hemispheres are not the same at age 14 as they are at age 22”, explained Tomas Paus. “By early adulthood, however, the asymmetry between the two hemispheres has largely stabilized.” 

Brain activity, neurotransmitters and maturation

Looking to identify the roots of this process and asymmetry, the study also found that the rate of thinning reflects the density of neurotransmitter receptors, the substances that enable communication between brain cells. So the more neurotransmitter receptors there are in a given area, the faster that area thins. It was also discovered that corresponding areas in the right and left hemispheres thin at a more similar rate the more they communicate with each other and act in concert. “There’s a correlation, but it seems that the more you use a region of the brain, the faster it matures,” said Tomas Paus. “It’s possible that the organization of the neurotransmitter system is genetic, but the way we use our brains also has an impact.” 

For certain psychopathologies where an abnormal asymmetry has been identified, this may enable us to modify the structure by changing brain activity and function. “If these results are confirmed, it means that we could, for example, give personalized exercises to stimulate brain maturation right down to the structural level!” added the researcher. “Just as we can prescribe exercises to strengthen underused muscles, we could help stimulate less active parts of the brain.” 



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About this study

The article “Hemispheric asymmetry in cortical thinning reflects intrinsic organization of the neurotransmitter systems and homotopic functional connectivity” was published on October 13, 2023, by Zhijie Liaoa, Tobias Banaschewski, Arun L. W. Bokde, …, Tomas Paus and the IMAGEN Consortium in the journal Proceedings of the National Academy of Sciences (PNAS).

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Updated on 10/26/2023
Created on 10/26/2023
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