9. All or Nothing

Dr Geoff Bunn's ten-part history is a journey through 5000 years of our understanding of the most complex thing in the known universe.

From Neolithic times to the present day, Geoff journeys through the many ideas of what the brain is for and how it fulfils its functions.

What soon becomes obvious is that our understanding of this most inscrutable organ has in all periods been coloured by the social and political expedients of the day no less than by the contemporary scope of scientific or biological exploration.

In this episode, the focus is on the invention of the electroencephalograph, which made our brain waves visible. Invented by Hans Berger, one of its main proponents was the eccentric English robotics pioneer and neuroscientist, William Grey Walter. Until a near fatal accident, Walter was one of 15% of the population who can't produce the resting, alpha wave - only the active, beta wave. After the accident he could emit alpha waves. Meanwhile, at Cambridge, Edgar Adrian, no fan of the EEG, established the 'all or nothing' principle of nerve transmission to explain simple reflex actions.

Featuring the voices of Paul Bhattacharjee, Jonathan Forbes and Hattie Morahan.

Produced by Marya Burgess.

First broadcast on BBC Radio 4 in November 2011.