MICROSTRUCTURAL ORGANIZATION OF CORTICO-SUBCORTICAL FUNCTIONAL CONVERGENCE

The human subcortex integrates information from distributed cortical regions through functionally organized cortico-subcortical systems. Using the publicly available MICA-MICs multimodal MRI dataset of 50 healthy adults, we characterized the microstructural organization of functionally converging cortical regions. First, using resting-state fMRI., we identified cortical regions converging on subcortical targets, including thalamic, basal ganglia, and subcortical limbic structures. Then, using depth-resolved quantitative T1 profiles, we constructed a convergence-restricted microstructural profile covariance matrix, followed by diffusion-map embedding. The first microstructural gradient predominantly differentiated primary and association cortex, whereas the second gradient showed target-related differentiation beyond differences in primary versus association cortex. Cytoarchitectural analysis further revealed target-related differences in cortical composition. Together, these findings reveal complementary dimensions of cortico-subcortical functional organization, spanning broad cortical hierarchy, target-related microstructural differentiation, and cytoarchitectural composition.