Myelin-forming oligodendrocytes (OLs) are formed continuously in the healthy adult brain. In this work, we study the function of these late-forming cells and the myelin they produce. Learning a new motor skill (such as juggling) alters the structure of the brain’s white matter, which contains many OLs, suggesting that late-born OLs might contribute to motor learning. Consistent with this idea, we show that production of newly formed OLs is briefly accelerated in mice that learn a new skill (running on a “complex wheel” with irregularly spaced rungs). By genetically manipulating the transcription factor myelin regulatory factor in OL precursors, we blocked production of new OLs during adulthood without affecting preexisting OLs or myelin. This prevented the mice from mastering the complex wheel. Thus, generation of new OLs and myelin is important for learning motor skills.

Learning requires the brain to change

We may be leveraging change in our brains more than we have thought. Ohayon et al. knocked out cells responsible for laying down insulating myelin along neuronal axons in the brains of otherwise normal adult mice (see the Perspective by Long and Corfas). The mice lacking the myelin-forming cells were less able to learn a new motor skill involving running on a wheel with unevenly spaced bars. Although we may not run on a wheel, when trying to master new motor skills such as juggling, we too may well rely on similar myelin-producing cells.

Science, this issue p. 318; see also p. 298