Neuronal precursor cells - (Oct/22/2009 )

I keep coming across the term 'neuronal precursor cells' whilst researching for an essay, but I can't seem to find any info on what they actually are. Are neuronal precursor cells just embryonic stem cells? Have they just differentiated to a sort of 'no going back' point meaning they definitely will become neurones and nothing else but are not neurones yet? Or is it just because of their location in the sub-ventricular zone that means they will become neurones and nothing else? Any info greatly appretiated, thanks:)

This is my take on them -they are multipotent (not totipotent) cells, so they can differentiate into the different cells lineages in the brain, astrocytes/neurons/oligodendrocytes etc. There are various steps where they divide either symmetrically to give rise to more progenitors or asymmetrically to give lineage restricted cells which either self renew or divide again asymetrically... There is debate about how multipotenet they are. I think there are lots of papers out there on it...