Robust learning-driven structural and functional plasticity of spines in the mature mouse cortex

Spines in the adult cortex are thought to be highly stable, and that their capacity for modest remodeling supports learning. Using a visual association task and a multilevel imaging approach in adult mice, we found a robust learning-driven increase in the complexity of spine nanostructure, as well as a rapid and persistent increase in spine formation during task acquisition that were accompanied by an overall reduction in spine size of layer 2/3 neurons in the primary visual cortex (V1). Trained animals further had an increased fraction of spines tuned to the task-relevant orientations, and the discriminability of spine responses in naïve mice was predictive of their subsequent performance. Our results demonstrate that learning drives an increase in spine preferences for task-relevant information and point to reconfiguration of spine nanostructure and spine inputs as the structural drivers of these changes.