Neuroscientists have conducted the first detailed examination of Albert Einstein's brain and found evidence that part of the renowned physicist's genius may have come from a section involved in abstract thought that was unusually large and uniquely shaped.

Although the discovery does not conclusively explain the source of Einstein's towering intellect, and probably was just one factor in the development of his intelligence, it does provide a clue to how subtle differences in the human brain can profoundly affect how the mind works, the researchers said.

"This is an individual case and we can't prove one is the basis of the other, but it fits together in a very reasonable and consistent way," said Sandra F. Witelson, a neuroscientist at McMaster University in Hamilton, Ontario, who led the research.

"The results suggest that maybe there is a larger region of the brain supporting spatial cognition in Einstein, and this may be true for other people with excellent skills in this area as well," she said.

The German-born U.S. physicist was one of the great thinkers of all time because of his fundamental discoveries about the nature of time, space and matter. When he died in 1955, at age 76, his brain was removed within seven hours, weighed, measured and carefully preserved. It was later dissected into more than 200 sections and meticulously coded so it could be studied later.

Thomas Harvey, who conducted the autopsy and preservation and has maintained the brain ever since, contacted Witelson when he learned that she had assembled a collection of about 100 brains from normal people about whom she gathered detailed information, including data on their intelligence.

"The purpose of our research is to elucidate some of the relationships between brain anatomy and function. If one studies an extreme case, sometimes that highlights the possible relationship in a clearer way. So when the opportunity came to study Einstein's brain, it seemed like a potentially fruitful study," she said.

Witelson and her colleagues used some of the original measurements of Einstein's brain, plus some new ones, to compare more than two dozen parts of Einstein's brain with the brains of 35 men and 56 women of normal intelligence.

In most respects, Einstein's brain was no different than the others. "Einstein's brain weight was not different from that of controls, clearly indicating that a large (heavy) brain is not a necessary condition for exceptional intellect," they wrote in reporting their findings in today's issue of The Lancet, a British medical journal.

However, Einstein's brain did clearly differ when the researchers examined the parietal lobes, which are located in the top back of the brain. Portions of Einstein's parietal lobes, known as the inferior parietal lobules, were larger on both sides, making his brain 15 percent wider than the other brains.

The inferior parietal region is believed to be involved in spatial visualization, mathematical thought and three-dimensional thinking.

"Einstein's exceptional intellect in these cognitive domains and his self-described mode of scientific thinking may be related to the atypical anatomy of his inferior parietal lobules," the researchers wrote.

In addition, Einstein's brain did not have a structure, called the parietal operculum, that typically runs through this area of the brain. The absence of this structure may have allowed neurons there to establish more connections with each other and work together more easily, the researchers speculated.

"These are crucial centers for spatial visualization, for three-dimensional thinking, that certainly would be involved in the theories that Einstein was working with," Witelson said. "Perhaps the interconnectivity in that region is different, and maybe it conferred some advantage."

Witelson stressed that intelligence is a complicated attribute that stems from the interplay of many different factors. Environmental influences most likely also played an important role in Einstein's intelligence, she said.

Studying the brains of other exceptional people would help clarify the relationship between neuroanatomy and intelligence, and its relative importance, she said.

CAPTION: Albert Einstein, the German-born U.S. physicist, is considered one of the great thinkers of all time. When he died in 1955, his brain was removed and preserved.

CAPTION: The Shape of a Great Mind

1955 photographs of Albert Einstein's brain:

Portions of Einstein's parietal lobes, the inferior parietal lobules, are larger than normal, making his brain 15 percent wider than average. The inferior parietal region is involved in mathematical thought, three-dimensional thinking and spatial visualization.

In Einstein's brain, a groove called the sylvian fissure runs in such a way that his brain does not have the normal formation known as the parietal operculum.

SOURCE: The Lancet