Moreover, in the analysis of the three major categories of neuronal death, it must be kept in mind that although apoptosis and necrosis are clearly cell death pathways and autophagy has been associated with neuronal death, autophagy is also considered to be a cell protective mechanism, induced as a major catabolic pathway to generate intracellular nutrients to maintain energy production and macromolecular synthesis when external nutrients are limited (19). Two very recent studies performed by inactivating proteins of the autophagic pathway have led to results indicating that the role and importance of autophagy in neuronal death is still an object of debate: inactivation of either protein Atg-7 or Atg-5 in mice leads to behavioral defects and progressive neuronal degeneration (20,21).