Tiny human brains capable of thinking for themselves have been grown in a lab, according to scientists.

Their creator is US toxicologist Thomas Hartung. His idea is that the brains could be used to test drugs - and he hopes to set up a production line by the end of the year.

While this may sound like something out of a horror film, a plentiful supply of identical mini-brains - which are only the size of a fly's eye - could help speed the quest to cure conditions such as Alzheimer's.

"Ninety-five per cent of drugs that look promising when tested in animal models fail once they are tested in humans at great expense of time and money," Professor Hartung told the American Association for the Advancement of Science's annual conference in Washington DC.