The BBC's Sue Nelson: "Within seven hours of his death his brain was removed and preserved"

Albert Einstein, who discovered the theory of relativity, died in 1955, aged 76. His brain was then removed and preserved for scientific research.

Scientists at McMaster University, Ontario, Canada compared the shape and size Einstein's brain with those of 35 men and 56 women with average intelligence.

They think their findings may well explain his genius for mathematical and spatial thinking.

In general, Einstein's brain was the same as all the others except in one particular area - the region responsible for mathematical thought and the ability to think in terms of space and movement.

Albert Einstein

Extensive development of this region meant that Einstein's brain was 15% wider than the other brains studied.

Uniquely, Einstein's brain also lacked a groove that normally runs through part of this area. The researchers suggest that its absence may have allowed the neurons to communicate much more easily.

"This unusual brain anatomy may explain why Einstein thought the way he did," said Professor Sandra Witelson, who led the research published in the Lancet.

"Einstein's own description of his scientific thinking was that words did not seem to play a role. Instead he saw more or less clear images of a visual kind," she said.

Einstein allowed his brain to be studied after his death

The idea that differing abilities are determined by physical differences in the structure of the brain is currently of great interest to scientists.

"To say there is a definite link is one bridge too far, at the moment," said Professor Laurie Hall, a brain imaging expert from the University of Cambridge.

"So far the case isn't proven. But magnetic resonance and other new technologies are allowing us to start to probe those very questions."