“Some 85 billion neurones and upwards of 100 trillion connections – the adult human brain is the most complex object in the known universe. But how does such a rich neural network grow from a tiny foetus? And how does that growth affect the way our brains ultimately function? Scientists have a rough picture of how a brain develops in the womb. About three weeks after conception, brain cells begin to form at the tip of the embryo into a tube that will eventually form the spinal cord. This tube then begins to form a brain, where the neurones – brain cells – develop and begin to form contacts with each other. Until the foetus is about 20 weeks old, some quarter of a million cells are growing every minute…” 

Full article available here on pages 7-8: http://mag.digitalpc.co.uk/fvx/iop/physworld/medical-imaging13/