Neurogenesis and progenitor cells in the adult human brain: a comparison between hippocampal and subventricular progenitor proliferation

But we next need to know which starting place  will migrate neurons to the area of need.
http://onlinelibrary.wiley.com/doi/10.1002/dneu.22028/abstract

Abstract

For more than a decade we have known that the human brain harbours progenitor cells capable of becoming mature neurons in the adult human brain. Since the original landmark paper by Eriksson and colleagues in 1998 there have been many studies investigating the effect depression, epilepsy, Alzheimer's disease, Huntington's disease and Parkinson's disease have on the germinal zones in the adult human brain. Of particular interest is the demonstration that there are far fewer progenitor cells in the hippocampal subgranular zone (SGZ) compared with the subventricular zone (SVZ) in the human brain. Furthermore the quantity of progenitor cell proliferation in human neurodegenerative diseases differs from that of animal models of neurodegenerative diseases; there is minimal progenitor proliferation in the SGZ and extensive proliferation in the SVZ in the human. In this review we will present the data from a range of human and rodent studies from which we can compare the amount of proliferation of cells in the SVZ and SGZ in different neurodegenerative diseases.