Magazine article The Wilson Quarterly

The Bulging Brain

Magazine article The Wilson Quarterly

The Bulging Brain

Article excerpt

THE SOURCE: "Sculpting the Brain" by Claus C. Hilgetag and Helen Barbas, in Scientzfic American, Feb. 2009.

EVERY TIME YOU READ AN IN Essence article, responding to it by saying "hmmm," getting mad at the author, or even flipping the page, you are exercising your cerebral cortex, which is about as thick as a piece of cardboard and as big as an extra-large pizza. The cortex fits in your skull because it folds up into consistent patterns of bulges and valleys. The geography of the brain has been studied for hundreds of years. A pseudoscience called phrenology once did considerable harm to people whose brain and, particularly, skull measurements were judged to be savage. But Claus C. Hilgetag, a neuroscientist at Jacobs University Bremen, and Helen Barbas, a professor at Boston University, say that the phrenologists may have been on to something. The shape of the brain may be critical to the causes of such mental disorders as schizophrenia and autism.

The cortex of a human fetus starts out smooth, and stays that way for about the first six months of development, according to Hilgetag and Barbas. Fetal neurons send out spindly fibers called axons that become tethered to target neurons in other areas of the cortex. As the cortex expands, the axons tighten up like bungee cords. That's how bulges are formed, as the two parts of the cortex are pulled together. By the time a baby is born, the brain has become characteristically wrinkled.

Animals lower on the evolutionary chain, such as zebra finches and platypuses, have nearly smooth cortexes. …

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