Oligodendrocyte progenitor cells (OPCs) were first described more than two decades ago. Novel labeling techniques have shown them to be cells with more than just progenitor functions, with their classification as a fourth glial cell type in addition to astrocytes, oligodendrocytes, and microglial cells. Another term used for this cell type is polydendrocytes, owing to both their morphology and to the evolving knowledge about their diverse functions. Recently, an exclusive hallmark of neurons--the generation of action potentials--became debatable, because a subset of polydendrocytes was reported to generate action potentials in response to adequate stimuli. The new technique of inducible reporter gene expression has brought new insights into the fate and function of polydendrocytes. In recent studies, so-called "silenced" OPCs were detected in cortical tissue, and which underwent proliferation with subsequent cell cycle exit, but without any signs of differentiation. Within this review, we focus on the identification of this new subset of polydendrocytes and their possible functions within cortical networks.