1. An isolated or purified mammalian platelet derived growth factor (PDGF)-responsive neural precursor (PRP) cell, wherein said cell expresses PDGF receptor alpha, and wherein said cell, when contacted with one or more of thyroid hormone, bone morphogenetic protein-2 (BMP-2), ciliary neurotrophic factor (CNTF) or triiodothyronine (T3), gives rise to a differentiated neural cell that expresses detectable amounts of one or more protein markers selected from: GABA, parvalbumin, beta-II tubulin, calbindin D, calretinin, O4, neurofilament M (NFM), myelin basic protein (MBP), TOA-64/TUC-2 and GFAP.