Brain birth and personal identity.

The concept of brain birth has assumed a position of some significance in discussions on the status of the human embryo and on the point in embryonic development prior to which experimental procedures may be undertaken on human embryos. This paper reviews previous discussions of this concept, which have placed brain birth at various points between 12 days' and 20 weeks' gestation and which have emphasised the symmetry of brain birth and brain death. Major developmental features of brain development are outlined, including the gradualness with which new features generally appear, and also the electroencephalogram (EEG) characteristics of premature infants. From this it is concluded that, if the concept of brain birth is a valid one, it should be placed at 24-28 weeks' gestation. More importantly, it is concluded that the differences between brain development and brain death throw doubt on the concept itself.