With the expectation of recruiting 1,500 patients during a 36-month time frame, the study will examine everything that happens to the human brain during cardiac arrest, from oxygen levels to the ability to recall images. The participating hospitals will be outfitted with equipment to monitor any patient who goes into cardiac arrest. While the person is in arrest, resulting in a flat line, doctors will monitor oxygen levels and blood flow into the brain. If patients consent to additional testing after recovery, they will be asked to recall any memories they can from the time while they were in cardiac arrest. Regardless of the recollection, each experience is useful to the study. "If they have no memories, they're useful because we'll use them as a control group," says Dr. Sam Parnia, director of the Human Consciousness Project and leader of the study.