human anatomy 1: Nerve Signalling: Tracing the Wiring of Life

The Nobel Prize in Physiology or Medicine has rewarded scientists for an amazing voyage of discovery inside the human nervous system - one that has revealed how the myriad tiny signals firing through nerve cells keeps us alive, thinking and moving.

Estimates vary wildly, since of course, no-one has counted them all, but there are some 100 billion separate nerve cells in the human brain - which is, by strange coincidence, around the same number as there are thought to be galaxies in the Universe. But this number, however awesome, doesn't begin to capture the almost miraculous complexity of the human nervous system. Each of those 100 billion cells can make hundreds and hundreds of separate connections with other cells - and unimaginably more alternative pathways - that allow nerve signals to crackle, fizz and buzz along as they make us jump up or sit down, laugh and cry, love and hate, sing, shout, swear, eat, drink and do everything that makes us human.

Science is only just beginning to understand the brain's remarkable form of 'software' - the way it works as a whole to enable us to live and think - but an amazing series of scientific breakthroughs have given us insight into its 'hardware'. Each of the Nobel Laureates who appear in this brief story has taken us further down the path towards understanding how nerves are made up and carry the signals that coordinate all the activities in our bodies.

Nerve networks

The nervous system consists of a complex, interwoven network of nerve cells that look like no other. This fluorescent microscopic image of neurons generated from human embryonic stem cells highlights this complexity. Spider-like nerve cell bodies with thin thread-like axons are visible in red and the nuclei in blue. Yellow neurons create and release the neurotransmitter dopamine, and are the type of neurons that deteriorate in patients with Parkinson's disease.
Copyright: Laboratory of Xianmin Zeng, the Buck Institute.