Structural Connections of Functionally Defined Human Insular Subdivisions

Area of Science:

• Neuroscience
• Neuroimaging
• Human Brain Anatomy

Background:

• The human insular cortex's organization has been debated, with traditional anterior-posterior dichotomy models challenged by recent functional neuroimaging suggesting a tripartite structure.
• Functional studies indicate distinct roles for dorsal anterior insula (cognitive), ventral anterior insula (affective), and posterior insula (interoceptive) subdivisions, alongside overlapping functional profiles.

Purpose of the Study:

• To investigate the structural white matter organization supporting a tripartite insular cortex model.
• To visualize and characterize the unique and overlapping connections of insular subdivisions using high-angular-resolution diffusion imaging (HARDI).

Main Methods:

• Utilized a large HARDI diffusion MRI dataset (n=199) for detailed tractography.
• Developed novel visualizations to map insula white matter pathways.

Main Results:

• Identified specific white matter tracts supporting the tripartite insular organization.
• Overlapping connections involved association pathways like the inferior fronto-occipital, uncinate, and arcuate fasciculi.
• Unique connections included the corona radiata, subcortical-cortical tracts, and horizontal/u-shaped tracts.

Conclusions:

• The findings support a tripartite structure-function organization of the insular cortex.
• Insular subdivisions exhibit both unique and overlapping connectivity profiles, consistent with functional data.