Neuromaturation of the human fetus.
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.
D033421:Beginning of Human Life; D002490:Central Nervous System / Q000196:embryology*; D002540:Cerebral Cortex / Q000196:embryology; D004622:Embryo, Mammalian / Q000502:physiology*; D005260:Female; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D040821:Human Characteristics; D006801:Humans; D019369:Life; D009043:Motor Activity; D009434:Neural Pathways / Q000196:embryology; D010146:Pain / Q000503:physiopathology; D028723:Personhood; D011247:Pregnancy; D012018:Reflex / Q000502:physiology; D012677:Sensation / Q000502:physiology; D013788:Thalamus / Q000196:embryology