Contralateral Seventh Cervical Nerve Transfer Drives Staged Central Remodeling After Traumatic Brain Injury: A Multiscale Resting-State fMRI Study

Contralateral seventh cervical nerve transfer (CC7) improves paretic-limb function after unilateral brain injury, but how peripheral rerouting reshapes distributed brain systems remain unclear. Here, we used longitudinal resting-state functional magnetic resonance imaging in a mouse traumatic brain injury model to determine whether CC7 is associated with multiscale reorganization of intrinsic brain function. Across post-transfer stages, functional connectivity density showed distinct stage-related spatial patterns, with predominantly contralesional sensorimotor involvement at earlier follow-up stages and additional striatal and hippocampal involvement at later stages, whereas regional homogeneity and fractional amplitude of low-frequency fluctuations showed complementary changes in local coordination and regional activity involving limbic-parahippocampal, thalamic, and sensorimotor regions. CC7 also improved late-phase skilled grasping, and secondary motor cortex and CA1 hubness correlated positively with behavioral recovery. These findings suggest that CC7-related recovery is not limited to contralesional sensorimotor compensation but increasingly recruits higher-order motor and learning-related systems, supporting a model of staged adaptive central remodeling after brain injury.