Robert A. Hill1, Akiko Nishiyama2 and Ethan G. Hughes3 1Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA 2Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269, USA 3Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado 80045, USA Correspondence: robert.hilldartmouth.edu

Oligodendrocyte precursor cells (OPCs) are a central nervous system resident population of glia with a distinct molecular identity and an ever-increasing list of functions. OPCs generate oligodendrocytes throughout development and across the life span in most regions of the brain and spinal cord. This process involves a complex coordination of molecular checkpoints and biophysical cues from the environment that initiate the differentiation and integration of new oligodendrocytes that synthesize myelin sheaths on axons. Outside of their progenitor role, OPCs have been proposed to play other functions including the modulation of axonal and synaptic development and the participation in bidirectional signaling with neurons and other glia. Here, we review OPC identity and known functions and discuss recent findings implying other roles for these glial cells in brain physiology and pathology.