Studies of neural circuit plasticity focus almost exclusively on functional and structural changes of neuronal synapses. In recent years, however, myelin plasticity has emerged as a potential modulator of neuronal networks. Indeed, myelination of previously unmyelinated axons and changes in the structure on already-myelinated axons can have large effects on the function of neuronal networks. As myelin plasticity is increasingly being implicated as a mechanism for sensory-motor and non-motor learning, my goal is to investigate the role of myelin in the context of complex cognitive learning tasks. I am doing so by using a cutting-edge multi-disciplinary approach combining behavioural experiments, confocal and two-photon microscopy, molecular biology, immunohistochemistry, histology and transgenics.