"the elad concept had concept had caused a lot of interest and some detached academic concern. the notion of an electrical addict - a man who needed his jolts of electricity just as some men needed doses of drugs - had seemed almost fancifully speculative.  but now they had a patient who was clearly a potential addict...there were areas in the brain where electrical stimulation produced intense pleasure - strips of brain tissue he called "rivers of reward". if an electrode was placed in such an area, a rat would press a self-stimulation lever to receive a shock as often as 5000 times an hour.  in it's quest for pleasure it would ignore food and water.  it would stop pressing the lever only when it was prostrate with exhaustion... there was no longer any question that the pleasure terminals in the brain were a universal phenomenon.  they had also been located in humans.  out of these considerations had come the notion of the electrical addict, the man who needed pleasurable shocks.  at first glance, it seemed impossible for a person to become an addict.  but it actually wasn't..." -

 Michael Crichton  -  The Terminal Man