In the 1960s a committee at Harvard Medical School developed the four criteria to define when the brain was truly alive. The presence of even one of the four criteria is sufficient to establish brain life. But the criteria assume the presence of a human being to whom they are being applied. The Harvard Criteria simply provide a gauge to ascertain the functioning of the brain. They do not determine humanness or when a life begins.
Conception is that moment when a woman's egg is fertilized by a man's sperm.
The result of this union of two cells is one unique cell known as the zygote. This single cell contains all the ingredients necessary for growth, development, and differentiation into the organ systems of a human adult. The zygote of each human being is distinctly different from every other human being. A common misunderstanding is that the zygote possesses only potential human life rather than actual human life. From a scientific standpoint, this assumption is invalid.