For our brain and spinal cord to work properly, allowing us to move, see, hear, feel and think quickly, fast electrical communication between different parts of the nervous system is essential. This is achieved by surrounding the nerve cells with an insulating layer called myelin; accordingly, significant mental or physical impairment occurs when myelin is damaged in disease. However, despite the importance of myelin, we have a limited understanding of how myelination is regulated. Throughout life stem cells in our brain called oligodendrocyte precursor cells (OPCs) differentiate into myelinating oligodendrocytes, and recent work implicates new myelinating cells as a mechanism for learning. In this project, I will study chemical signals, neurotransmitters, that neurons send to OPCs to instruct them to produce new myelinating oligodendrocytes during development and learning. I will focus on G protein-coupled receptors (GPCRs), a family of receptors that OPCs express and that are activated by neurotransmitters. Indeed, a number of drugs acting on GPCRs regulate experience-dependent myelin, and promote the formation of new myelin following injury. However, there is little understanding of the mechanism of action of these receptors. Thus, studying these signals in OPCs will give us a better understanding of myelination, brain function, and learning.