Neural stem cells have the potential to generate all neural cell types, such as neuron (neuronal progenitor), astrocytes and oligodendrocytes (glial progenitors). The proneural gene expression is induced by neurogenic signals and results in the activation of neuronal-differentiation pathway . At the same time, glial differentiation is inhibited. Neural stem cells lead to neuron differentiation while proneural genes inhibit glyogenic signals and consequently the glial-differentiation pathway.