Making of the brain and the birth of consciousness
December 10, 2009 Leave a comment
Blog Post by Hugo Lagercrantz, Karolinska Institutet, Stockholm
The birth of consciousness is one of the three most fundamental stages of creation like the origin of the universe and life according to Thomas Mann and cited by Christof Koch. When does the human infant become conscious? Is the fetus conscious? Even the preterm infant seems to be aware of him/her –self and reacts to pain at a cortical level where consciousness is processed. The newborn responds more to human voices than noise and looks longer on human faces. Consciousness can be defined as the hump from what is happening at the neuronal level to subjective feeling. Although the newborn is probably conscious only at a minimal level, all the ”atoms” of consciousness – the neurons in the cortex are formed before birth. Synaptogenesis has also started long before birth, but it peaks after about one year. The newborn brain is more like a jungle than a computer and it is necessary to prune the brain and organize the neuronal network before full consciousness is achieved. Putative neurotransmitters involved in consciousness like acetylcholine and norepinephrine and their receptors appear also at an early stage.
In the new second edition of the Newborn Brain – Neuroscience and clinical applications edited by H Lagercrantz, M Hanson, L Ment and D Peebles you can read more about the development of the human brain. Chapters on making of the brain, development of sensory systems, brain imaging and clinical aspects have been updated. New chapters on behaviour , follow-up and consciousness have been included.