Shim, H.-J.; Jung, W. B.; Im, G. H.; Lee, S.; Kim, G.; Kim, S.-G.

Sensory loss triggers crossmodal reorganization across sensory modalities, and accumulating evidence indicates that this adaptive capacity persists into adulthood. However, the global organizing principles of such plasticity remain poorly understood, as conventional animal model approaches do not permit longitudinal, whole-brain measurements. Here, we use ultra-high-field (15.2T) BOLD fMRI to map deafening-induced functional reorganization across the entire brain in young adult mice. Within one week of deafening, the auditory cortex is recruited by somatosensory and visual inputs, while stimulus-evoked responses are potentiated in the spared sensory pathways. Reorganization extends beyond sensory cortices to higher-order association areas, including anterior cingulate, retrosplenial, and posterior parietal cortices. Resting-state fMRI further reveals strengthened coupling both within sensory systems and between sensory systems and a default mode-like network. These findings demonstrate that adult-onset deafness rapidly reorganizes functional brain networks and further implicate the default mode-like network as a potential mediator of crossmodal integration.