"Recently it has become clear that new oligodendrocytes and myelin are generated throughout adult life in rodents. Some major axon tracts including the corpus callosum contain a majority of unmyelinated axons even in maturity, suggesting that at least some of the adult-born oligodendrocytes might myelinate previously naked axons. This would be expected to alter dramatically the conduction properties of the newly-myelinated axons and the properties of the circuits in which they participate, contributing to neural plasticity.It has been known for a long time that proliferation and differentiation of oligodendrocyte precursor cells (also known as NG2 cells) in the developing CNS is controlled in part by electrical activity in axons. More recently, it was shown that NG2 cells form synapses with axons (""axoglial synapses"") and receive electrical stimulation from passing action potentials. This suggests that NG2 cells are “listening in” to electrical activity which, at some threshold, might stimulate them to differentiate and myelinate the active axon(s). MRI imaging of human brain has revealed that white matter volume continues to increase into the fourth decade of life and that specific tracts can undergo structural changes in response to complex activities such as piano playing or juggling. These and other observations raise the intriguing possibility that motor skills learning and motor memory might depend on new myelination. Testing this startling new idea is at the core of my proposed program of research. We shall investigate 1) the role of axoglial synapses in regulating NG2 cell proliferation and differentiation in the adult CNS and 2) the role of NG2 cells and myelin genesis in motor learning. Behavioural, cellular and molecular analyses of genetically manipulated mice will form the major part of the experimental approach."