Scientists create a new map of the developing cerebral cortex

Scientists at the UNC College of Drugs have mapped the surface area of ​​the cortex of the young human brain with unprecedented resolution, revealing the development of key functional regions of two months before birth to two years after.

The new mapping of cortical development, reported online in the Proceedings of the National Academy of Sciences, represents a valuable resource for further research on brain development and offers a powerful new approach to the study of brain development conditions such as autism and schizophrenia.

“These findings provide an important benchmark for exploring and understanding the dynamics of early brain development,” said study lead author Gang Li, PhD, associate professor of radiology at UNC University of Medicine.

The first author of the study was Ying Huang, a doctoral candidate in Li’s lab.

The cortex is a sheet of brain cells that envelops much of the rest of the brain. The most evolutionarily advanced region of the brain, it is proportionally larger in humans than in other mammals, and is responsible for higher, typically human functions, including linguistic abilities and abstract reasoning.

The third trimester of pregnancy until the first two years of life is the most dynamic period of cortical development. The cortex thickens markedly during this interval and grows at an even faster rate in terms of area, forming complicated cortical folds.

Disturbances in thickening and of cortical expansion in this phase have been linked to autism and schizophrenia. However, neuroscientists do not have as detailed an understanding of this section of development as they would like. In particular, they needed more comprehensive, high-resolution mapping, across the fetal-to-toddler age range, that divides or “particles” the developing cortex into distinct regions with their own unique rates of growth. growth – especially the area Growth rates.

In the study, Li and his colleagues have done such mapping. They first put together a set of 1 037 high-quality magnetic resonance imaging (MRI) scans of infants in the age range from the third trimester to two years. The scans came from two other research projects, the UNC/UMN Baby Connectome Project (BCP) and the Developing Human Connectome Project. The team analyzed the scan data using state-of-the-art computerized image processing methods, essentially dividing the cortical floor into a virtual mesh containing thousands of tiny circular areas and calculating the rate of surface expansion for each of these areas..

The analysis did not start with assumptions about the locations of brain constructs or functional regions, but this regionalization of the brain became evident from the resulting maps, based solely on the different rates at which the areas of the floor have developed. In all, the researchers defined distinct regions, which they found to correlate well with what is already known about the functional regions of the developing cortex.

“All of these regions show dramatic surface area enlargement during this developmental window, with each region having a distinct trajectory,” Li said.

The maps revealed that each region tended to have the same developmental path as its counterpart in the opposite hemisphere of the cortex. Gender differences were also apparent. Even controlling for gender differences in the overall area — with male brains having larger area — there remained differences in several regions. For example, the medial prefrontal region of the left hemisphere, thought to house important functions such as attention and working memory, became proportionally larger in males at the start of the second year of postnatal life.

The analysis also showed that the patterns of cortical area expansion during this early period of life were very different from the developmental patterns of cortical thickness, which suggests that these two measures of brain development involve distinct mechanisms.

In the Together, Li said, the mapping provides fundamental new insights into brain development.

He and his team now plan to extend this approach with datasets from MRIs that start at earlier ages and end at older ages. They also hope to eventually study analysis datasets covering children with the autism spectrum or other neurodevelopmental situations. Such analyzes could offer not only clues to the origins of these conditions, but also the identification of early signs or biomarkers, which could in the future be used to administer early and more effective treatments.

The PNAS article titled “Mapping of developmental regionalization and cortical surface area patterns from 29 weeks submit -Menstrual at 2 Years” was co-authored by Ying Huang, Zhengwang Wu, Fan Wang, Dan Hu, Tengfei Li, Lei Guo, Li Wang, Weili Lin, and Gang Li. At UNC-Chapel Hill, BCP MRIs were performed at the UNC Biomedical Research Imaging Center (BRIC), led by Weili Lin, PhD.

Funding was provided by the Nationwide Institutes of Wellness (MH116225, MH117943, MH109773, MH123202, 1UMH110274) and the UNC/UMN Little one Connectome Project Consortium.

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