Cryonics involves cooling legally-dead people to extremely low temperatures in hopes that future medical advances can revive them and potentially cure the cause of death. It aims to preserve the brain and body until reanimation is possible by preventing decay. While memory depends on brain activity lost at death, long-term memory is based on durable changes that may be preserved through cryopreservation. Some mammals have been cryopreserved and revived, showing the potential for the technique.