Myelin, once considered a static structure, is now increasingly recognized as dynamic in adulthood. Converging evidence from studies in humans and rodents indicates that learning and neural activity modulate white matter structure, oligodendrogenesis and myelination. Recent studies have demonstrated that inhibiting oligodendrogenesis in adult mice selectively impairs certain motor learning tasks and memory consolidation. Using the same conditional knock-out mouse model, we replicated the finding that inhibiting oligodendrogenesis impairs the same motor learning task while leaving motor control unaffected. Ablating oligodendrogenesis over a 6–7 week period also led to increases in EEG power density(1–30 Hz) across wakefulness and sleep. These results suggest that adult oligodendrocyte formation is important not only for skill acquisition but may also contribute to the maintenance of oscillatory brain activity. Task-independent changes following oligodendrogenesis ablation should be considered when interpreting learning and memory deficits in this model.