What exactly is intelligence? Researchers are one step closer to answering that question after mapping out the brain structures involved in human intelligence.

After examining the brains of more than 200 patients with brain lesions, researchers at the California Institute of Technology and the University of Iowa mapped the location of the lesions and correlated the images with each patient's IQ score. This helped them produce a map of the brain regions that influence intelligence.

The map reveals that intelligence -- rather than residing in a single structure -- is built by a network of regions across both sides of the brain.

"It might have turned out that general intelligence doesn't depend on specific brain areas at all, and just has to do with how the whole brain functions," Ralph Adolphs, Bren Professor of Psychology and Neuroscience at the California Institute of Technology in Pasadena, Calif., was quoted as saying. "But that's not what we found. In fact, the particular regions and connections we found are quite in line with an existing theory about intelligence called the 'parieto-frontal integration theory.' It says that general intelligence depends on the brain's ability to integrate -- to pull together -- several different kinds of processing, such as working memory."

Researchers say the findings will open the door to new insights into how the brain, intelligence and environment interact.

Source: Proceedings of the National Academy of Sciences, February 2010