Oxygenation of cells and tissues in mammals according to metabolic needs is always a life-or-death necessity. Over the last decade, life scientists have gained an impressive understanding of cellular and molecular mechanisms in hypoxic-ischemic injury and memory deficits, survival, and death. Functional recovery from hypoxia-ischemia depends on how the individual responds to the insult, and whether appropriate responses are initiated and maintained. Unraveling the biochemical and molecular mechanisms and responses of hypoxia-ischemia is likely to dramatically shape and improve medical practice in the treatments of hypoxia-ischemia and memory deficits.