A multimodal characterization of low-dimensional thalamocortical structural connectivity patterns.

Area of Science:

• Neuroscience
• Human Brain Anatomy
• Connectomics

Background:

• The human thalamus is a complex subcortical structure crucial for whole-brain coordination.
• While thalamic subnuclei are recognized, their precise boundaries and organizational principles are debated.
• Emerging evidence suggests continuous organizational axes within the thalamus, beyond discrete nuclei.

Purpose of the Study:

• To investigate the relationship between low-dimensional axes of thalamocortical structural connectivity and intrathalamic microstructural/functional organization.
• To explore how these organizational axes relate to structural covariance across brain regions.
• To understand the multimodal associations of these thalamic organizational axes with large-scale brain networks.

Main Methods:

• Diffusion MRI was used to compute a thalamocortical structural connectome.
• Two primary axes of thalamic organization were derived from the structural connectome data.
• Multimodal associations were analyzed across various brain networks and modalities.

Main Results:

• A principal axis, from medial to lateral, correlated with intrathalamic myelin content and functional connectivity patterns.
• A secondary axis corresponded to the known core-matrix cell distribution within the thalamus.
• The principal axis effectively differentiated network nodes (limbic, frontoparietal, default mode) from attention networks across modalities, though sensory modality links varied.

Conclusions:

• Thalamocortical structural connectivity exhibits low-dimensional organizational principles that align with microstructural and functional properties.
• These findings provide insights into the multiscale organization of the human thalamus and its role in coordinating brain activity.
• The study highlights the coherence between structural connectivity patterns and functional network organization within the thalamus.