New study reveals how thalamus orchestrates the maturation of sensory and cognitive processing

Our brains seamlessly process streams of visual information from the world around us while simultaneously understanding the causal structure of events. These essential cognitive functions, known as external sensory processing and internal world modeling, are critical for navigating complex environments.

The achieves this through large-scale functional systems responsible for these processes. Recently, an international collaboration of scientists led by the Institute for Basic Science (IBS) explored the role of thalamocortical connectivity in the development of brain networks. Their findings, published in Nature Neuroscience, shed new light on how these crucial connections evolve.

One longstanding question in is how the brain's large-scale functional networks form during development. This study investigated the changes in connectivity between the thalamus and cerebral cortex from infancy to adulthood, and how these changes influence the formation of the brain's functional networks. For the first time, researchers have shown that thalamocortical connectivity is essential for the emergence and specialization of the brain's functional networks, particularly those involved in processing external and internal information.

Traditionally seen as a relay station for sensory information, the thalamus also plays a significant role in higher cognitive functions. Sensory connections between the thalamus and cortex become established quickly at an early age, while higher-order cognitive connections develop later in maturity. However, the exact mechanisms and timeline of these developments have remained unclear.

This study addressed these challenges by using advanced neuroimaging techniques, transcriptomic analyses, and on cross-sectional and longitudinal datasets, to map the development of thalamocortical connectivity across different age groups.

The research revealed that during infancy, thalamocortical connectivity reflects early sensorimotor network differentiation and patterns related to brain development. As children grow, this connectivity evolves to establish connections with the salience network, which differentiates external (sensorimotor, visual, dorsal attention networks) and internal (default mode network) functional cortical systems.

Computational simulations confirmed the thalamus's role in developing key features of the mature brain, such as functional segregation and the sensory-association axis.

Perturbation of developmentally informed growth models. (a) A schematic illustrates the growth model based on thalamo-salience connectivity rules that change over the developmental age span. Four perturbation models were tested: perturbation applied to the 8–12 years age group, 12–16 years age group, 16–22 years age group, and all age groups, compared to a non-perturbation model. (b) The segregation indices (salience-external and salience-internal) were calculated for each growth model, with percentages indicating the difference compared to the no-perturbation model. (c) Cortical gradients extracted from the simulated affinity matrix of each growth model demonstrate the impact of these perturbations on brain connectivity development. Credit: Nature Neuroscience (2024). DOI: 10.1038/s41593-024-01679-3

“Our study for the first time provides a detailed map of how thalamocortical connectivity contributes to the large-scale functional organization in the human brain from infancy through young adulthood,” said lead author Park Shinwon. “By integrating advanced neuroimaging techniques, gene expression analysis, and computational modeling, we were able to systematically track and analyze the changes in brain connectivity across different developmental stages. This comprehensive approach has allowed us to uncover the pivotal role of the thalamus in the emergence and specialization of functional brain networks.”

These insights into thalamocortical connectivity's role in brain development could have significant implications for understanding various neurodevelopmental disorders. By revealing how these connections form and evolve, scientists hope to identify potential intervention points for conditions where these processes go awry, such as autism spectrum disorders or schizophrenia.

Moreover, understanding the intricate dynamics of thalamocortical connectivity might inform the development of targeted therapies to enhance or restore cognitive functions in individuals affected by brain injuries or degenerative diseases.

Source: Institute for Basic Science