Neurogenesis and apoptotic cell death.

As recently as a decade ago, it seemed inconceivable to most neuroscientists that new neurons could be born routinely in the adult mammalian brain (neurogenesis) and that neurons and other brain cells die by committing a form of cell suicide (apoptosis). Both fields have evolved into large research enterprises that continue to revolutionize how we think about limiting cell injury and cell death in the adult brain and spinal cord. Moreover, both have afforded new possibilities that one day may help to restore normal function to the injured nervous system. In fact, this past year’s Nobel prize in Physiology and Medicine was awarded to Robert J. Horvitz of the Massachusetts Institute of Technology for his pioneering experiments elucidating complex pathways promoting and blocking programmed cell death in the nematode C elegans. Horvitz’s elegant discoveries showed how genes and proteins expressed within evolutionarily ancient and biologically less complex organisms can profoundly influence our understanding of cell death in the mammalian nervous system, with equally important implications for the developing brain and for brain cancer. This review examines recent advances underscoring the importance of neurogenesis and neuronal cell death to the adult brain after stroke.