A) Enhanced or reduced experiential input or neuronal activity can directly alter any stage of oligodendrocyte lineage progression, including OPC (green) proliferation, OPC differentiation, or death of newly generated oligodendrocytes (blue). Experiential input or neuronal activity can also directly alter myelination by newly generated or preexisting oligodendrocytes by B) altering internodal localization, nodal geometry, or various aspects of myelin sheath geometry.