Adult neurogenesis: a mechanism for brain repair?

It is now generally accepted that new neurons are added to the adult mammalian brain. This raises the possibility that naturally occurring neurogenesis may be useful for repairing the damaged adult brain. Indeed, several studies have shown that damage to the adult brain can stimulate reparative neurogenesis. However, the production of new neurons is only one of several steps necessary to restore damaged neural circuits to their original state. Studies carried out on intact animals have identified several conditions that affect the production and survival of new neurons in adult brains. This review considers the evidence for compensatory neurogenesis in the adult mammalian brain with a view toward applying information from the undamaged brain to studies of regeneration.