Hoping to learn more, the authors located 241 patients who had some sort of brain lesion. They then diagrammed the location of their lesions and had them take IQ tests.
"We took patients who had damaged parts of their brain, tested them on intelligence to see where they were good and where they were bad, then we correlated those scores across all the patients with the location of the brain lesions," Glascher explained. "That way, you can highlight the areas that are associated with reduced performance on these tests which, by the reverse inference, means these areas are really important for general intelligence."
"These studies infer results based on the absence of brain tissue," added Paul Sanberg, distinguished professor of neurosurgery and director of the University of South Florida Center for Aging and Brain Repair in Tampa. "It allows them to systemize and pinpoint areas important to intelligence."
Young said the findings echo what's come before. "The map they came up with was what we expected and involves areas of the cortex we thought would be involved -- the parietal and frontal cortex. They're important for language and mathematics," he said.
In an earlier study, the same team of investigators found that this brain network was also important for working memory, "the ability to hold a certain number of items [in your mind]," Glascher said. "In the past, people have associated general intelligence very strongly with enhanced working memory capacity so there's a close theoretical connection with that."
Learn more about the workings of the brain at Harvard University's Whole Brain Atlas.
SOURCES: Paul Sanberg, Ph.D., D.Sc., distinguished professor, neurosurgery, and director, University of South Florida Center fo
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