Adult neurogenesis and neuroplasticity.

After cerebral strokes and traumatic brain injuries (TBIs), there is a striking amount of neurological recovery in the following months and years, despite often-permanent structural damage. Though the mechanisms underlying such recovery are not fully understood, properties of plasticity of the central nervous system (CNS), such as the reorganization of the pre-existing network and axonal sprouting have been implicated in the recovery. With the recent evidences that neurogenesis occurs in the adult brain, and neural stem cells (NSCs) reside in the adult CNS, the involvement of newly generated neuronal cells in the recovery following injury to the CNS remains to be established. Neurogenesis is increased bilaterally in the dentate gyrus (DG) and the subventicular zone (SVZ) after cerebral strokes and TBIs, and new neuronal cells are generated at the sites of injury, where they replace some of the degenerated nerve cells. Newly generated neuronal cells at the sites of injury may represent an attempt by the CNS to regenerate itself after injury, whereas the increased neurogenesis in the DG and SVZ would also contribute to the CNS plasticity. Thus, injury-induced neurogenesis may contribute to the recovery and plasticity of the CNS.