Thalamocortical architecture shapes structural and functional plasticity after early sensory loss.

UNLABELLED: Early sensory loss transforms the functional organization of affected sensory systems, with regions that normally support vision or audition participating in noncanonical perceptual and cognitive functions. Such reorganization requires coordination across distributed networks. Higher-order thalamic nuclei are positioned to support these interactions through their widespread reciprocal cortical connectivity, yet studies of sensory-loss plasticity have focused primarily on cortex and first-order sensory pathways. Here, we combined structural and functional MRI in early blind and early deaf adults to test how reorganization after sensory loss is expressed across thalamocortical networks. In blindness, structural differences were concentrated along the primary input pathway, with reduced lateral geniculate nucleus volume that covaried with areal organization of primary visual cortex. Functional reorganization was more broadly distributed, with visual cortex showing greater similarity with higher-order (association) thalamic nuclei linked to cognitive control, paralleling a shift toward cognitive-control networks across cortex. This pattern was amplified during a nonvisual perceptual judgment task. Across visual cortex, cross-network functional differences were strongest in regions showing the largest structural effects. A related shift toward control-associated higher-order thalamus was observed in deafness, indicating that higher-order thalamic involvement generalizes across sensory modalities. Together, these results indicate that thalamocortical architecture shapes both the developmental consequences of early sensory loss and the capacity for distributed functional reorganization.

HIGHLIGHTS: Structural reorganization tracks first-order thalamocortical architectureHigher-order thalamus participates in cross-network functional plasticityStructural and functional thalamocortical reorganization are anchored to the primary cortical target of sensory inputControl-related thalamocortical plasticity generalizes across blindness and deafness.

ETOC BLURB: Nishio et al. show that early sensory loss differentially reorganizes first-order and higher-order thalamocortical systems. First-order pathways track cortical structural differences, whereas higher-order thalamus shows cross-network functional reorganization that is enhanced during nonvisual tasks in blindness. Control-related thalamocortical reorganization generalizes to deafness.