Networks in the gray matter undergo complex transformations from neonatal age to childhood. The transformation supports the rapid cognitive development during the very early childhood.

Functional magnetic resonance imaging, or fMRI, has long been a cornerstone in studying brain function and researchers have long studied the functional networks in the gray matter of the brain.

However, until recently, the development of white matter networks, which consist primarily of nerve fibers connecting the different brain regions, was difficult to study due to their weaker fMRI signals.

New research has now allowed scientists to explore these networks in greater detail, shedding light on how white matter contributes to cognitive growth from infancy into childhood.

New Findings on White Matter in Brain Development
In a recent study, researchers compared the white matter functional networks in neonates and 8-year-old children.

Using the same imaging protocols and fMRI techniques across groups, they assessed and contrasted how these networks function and change with age. For both neonates and 8-year-olds, they analyzed the brain’s white matter network activity, considering various connectivity measures.

These measures included intra-network functional connectivity, which captures connections within single networks, inter-network connectivity, or the communication between different networks, and a measure of brain activity energy called fractional amplitude of low-frequency fluctuation.

The study revealed significant developmental changes in white matter networks between these two age groups. White matter connectivity within certain regions, like the optic radiations (vision) and corticospinal tracts (movements), decreased in 8-year-olds compared to neonates. This suggests that as the brain matures, some connections within individual networks may become more refined or specialized.

In contrast, inter-network connectivity was higher in older children, indicating that the communication between distinct brain networks becomes stronger with age. Additionally, brain activity energy was more distributed across higher frequencies in 8-year-olds, suggesting a shift in brain processing patterns as children grow.

Linking White and Gray Matter in Cognitive Development
The researchers also studied gray matter networks in the same children, finding similar patterns of increased inter-network connectivity and decreased intra-network connectivity with age.

This supports earlier studies showing that as children grow, their brains develop not just by strengthening individual networks but also by integrating these networks into more efficient communication systems.

These findings reveal that white matter functional networks undergo similar transformations, suggesting that white matter plays a vital role in cognitive development alongside gray matter.

Implications for Understanding Brain Growth
By observing how white matter networks evolve, this study provides a broader picture of brain development.

White matter connectivity changes reflect the brain’s increasing capacity for complex processing and integration, the key to the rapid cognitive growth seen in childhood.

These findings may help inform future research into developmental disorders, where differences in white matter connectivity may play a role in symptoms or cognitive challenges.

About the scientific paper:

First author: Yali Huang, USA
Published: Frontiers in Neuroscience. October 2024 Link to paper: https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2024.1467446/full