A sensorimotor-association axis of thalamocortical connection development

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Human Brain Development

Background:

• Human cortical development progresses from sensorimotor to association areas throughout childhood and adolescence.
• The precise mechanisms regulating the timing of cortical maturation and its regional differences remain poorly understood.
• Thalamic axon signaling in animal models influences critical periods of cortical plasticity.

Purpose of the Study:

• To test the hypothesis that thalamocortical connections coordinate the asynchronous maturation of cortical regions during youth.
• To develop and validate a novel atlas of human thalamocortical connections.

Main Methods:

• Created and anatomically validated a human thalamocortical connection atlas using diffusion tractography.
• Applied the atlas to three independent datasets of youth (ages 8-23 years; N=2,676).
• Analyzed maturational trajectories of thalamocortical connections in relation to cortical functional organization.

Main Results:

• Thalamocortical connections exhibit a reproducible maturational gradient mirroring the sensorimotor-to-association cortical axis.
• Cortical regions with later-maturing thalamic connections show prolonged markers of plasticity and environmental sensitivity.
• This gradient aligns with established sequences of human cortical maturation.

Conclusions:

• The thalamus plays a crucial role in orchestrating the timing of cortical development.
• Thalamocortical structural connectivity helps coordinate maturational heterochronicity across the human cortex.
• This coordination influences environmentally sensitive periods of developmental plasticity in associative brain regions.