Developmental enrichment reorganizes the directional topography of mouse proprioceptive cortex

The organization of proprioceptive cortex emerges from experience-dependent patterns of limb use during development, rather than merely reflecting peripheral innervation. However, the degree and specifics of these developmental changes remain poorly understood. To address this question, we investigated how early environmental enrichment (EE) reshapes the topography and functional properties of the mouse forelimb proprioceptive cortex. Using wide-field calcium imaging, we found that EE did not induce major reorganization of the mesoscale activation map. To resolve cellular level topography, we used a custom large-field fluorescence macroscope enabling unbiased single neuron imaging across the entire activation area and mapped the preferred limb movement direction of each neuron. We identified a topographically organized directional bias (anisotropy) in neuronal tuning for movements directed toward the body, with neurons in somatosensory and motor parts of the map preferring different movement directions. EE did not abolish this anisotropy but reorganized it. Anisotropic zones matched the somatosensory and motor anatomical locations more closely, and neurons in both areas aligned to a single preferred direction. Our findings therefore show that enriched limb use, rather than redrawing the cortical map, coordinates its sensory and motor components, revealing a developmental mechanism that tunes the mouse proprioceptive cortex for body-directed movements prominent in its natural behavior.