This paper suggests that medically the term a 'human being' should be defined by the presence of an active human brain. The brain is the only unique and irreplaceable organ in the human body, as the orchestrator of all organ systems and the seat of personality. Thus, the presence or absence of brain life truly defines the presence or absence of human life in the medical sense. When viewed in this way, human life may be seen as a continuous spectrum (...) between the onset of brain life in utero (eight weeks gestation), until the occurrence of brain death. At any point human tissue or organ systems may be present, but without the presence of a functional human brain, these do not constitute a 'human being', at least in a medical sense. The implications of this theory for various ethical concerns such as in vitro fertilisation and abortion are discussed. This theory is the most consistent possible for the definition of a human being with no contradictions inherent. However, having a good theory of definition of a 'human being' does not necessarily solve the ethical problems discussed herein. (shrink)

The fetal human possesses an active central nervous system from at least the eighth week of development. Until mid-gestation the most significant center of activity is the brainstem. By the end of the first trimester, it appears that the brainstem could be acting as a rudimentary modulator of sensory information and motor activity. What importance ought to be attached to such regulatory activity is uncertain. Some argue that it represents a level of integrated activity sufficient to bolster an argument for (...) conferring some measure of standing at this point. Our thinking about sentience is not advanced a great deal, as we as yet have no good way of talking about it at the brainstem level. As for the neocortex, available evidence indicates that it does not become a functional part of the neuraxis until at least mid-gestation. It is not until then that the thalamus – the major gateway for sensory input to the cerebrum – makes its first afferent contacts with the neocortex. Keywords: neuromaturation, fetal behavior, fetal brainstem CiteULike Connotea Del.icio.us What's this? (shrink)