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The emergence of consciousness: Science and ethics.

Research paper by Hugo H Lagercrantz

Indexed on: 28 Aug '14Published on: 28 Aug '14Published in: Seminars in Fetal & Neonatal Medicine



Abstract

The newborn human infant is conscious at a minimal level. It is aware of its body, itself and to some extent of the outside world. It recognizes faces and vowels to which it has been exposed. It expresses emotions like joy. Functional magnetic resonance imaging of the newborn brain shows highest activity in the somatosensory, auditory, and visual cortex but less activity in association area and the prefrontal cortex as compared with adults. There is an incomplete default mode network which is assumed to be related to consciousness. Although the fetus reacts to pain, maternal speaking, etc., it is probably not aware of this due to the low oxygen level and sedation. Assuming that consciousness is mainly localized in the cortex, consciousness cannot emerge before 24 gestational weeks when the thalamocortical connections from the sense organs are established. Thus the limit of legal abortion at 22-24 weeks in many countries makes sense. It should also be possible to withdraw or withhold life-saving therapy of extremely preterm infants, especially if they are severely brain-damaged. This may also apply to full-term infants with grade III hypoxic-ischemic encephalopathy, who show no signs of consciousness.