In the central nervous system (CNS), the formation of functional neuronal networks during development depends on the ability of neuroepithelial progenitor (NEPs) to generate neurons and glial cells – oligodendrocytes and astrocytes - in a highly specific manner, both temporally and spatially. In the ventral neural tube, depending on both its concentration and timing of exposure, Sonic Hedgehog (Shh) - released by the notochord and floor plate cells - regulates expression of transcription factors that demarcate distinct NEP domains dedicated to sequentially generate specific neuronal and glial cell sub-types (Rowitch & Kriegstein, 2010). Among them, the pMN domain, marked by expression of Olig2, first generates all of the motor neurons (MNs) to then switch to a gliogenic program and produces most oligodendrocyte precursor cells (OPCs). These pioneer OPCs then colonise the entire spinal cord through migration and proliferation, maturate into oligodendrocytes to form myelin sheaths necessary for the timely propagation of electrical impulses in the adult CNS. Although crucial for the proper development of the CNS, the cellular and molecular mechanisms regulating the end of neurogenesis and the switch to gliogenesis in ventral NEPs remain poorly understood. More particularly, it remains unknown to what extent physiological interactions (neurotransmission, electrical signaling) between NEP and their neuronal progeny could influence their transition from neurogenesis to gliogenesis.