View Full Version : Sex on the Brain, Men's and Women's Brains Are Different

12-10-2008, 12:26 AM
Ruben Gur, Ph.D., always wanted to do the kind of psychological research that when he found something new, no one could say his grandmother already knew it. Well, "My grandmother couldn't tell you that women have a higher percentage of gray matter in their brains," he says. Nor could she explain how that discovery resolves a long-standing puzzle.

Gur's discovery that females have about 15 to 20 percent more gray matter than males suddenly made sense of another major sex difference: Men, overall, have larger brains than women (their heads and bodies are larger), but the sexes score equally well on tests of intelligence.

Gray matter, made up of the bodies of nerve cells and their connecting dendrites, is where the brain's heavy lifting is done. The female brain is more densely packed with neurons and dendrites, providing concentrated processing power -- and more thought-linking capability.

The larger male cranium is filled with more white matter and cerebrospinal fluid. "That fluid is probably helpful," says Gur, director of the Brain Behavior Laboratory at the University of Pennsylvania. "It cushions the brain, and men are more likely to get their heads banged about."

White matter, made of the long arms of neurons encased in a protective film of fat, helps distribute processing throughout the brain. It gives males superiority at spatial reasoning. White matter also carries fibers that inhibit "information spread" in the cortex. That allows a single-mindedness that spatial problems require, especially difficult ones. The harder a spatial task, Gur finds, the more circumscribed the right-sided brain activation in males, but not in females. The white matter advantage of males, he believes, suppresses activation of areas that could interfere with work.

The white matter in women's brains is concentrated in the corpus callosum, which links the brain's hemispheres, and enables the right side of the brain to pitch in on language tasks. The more difficult the verbal task, the more global the neural participation required -- a response that's stronger in females.


12-10-2008, 05:32 AM
I watched a video on Youtube a while back about Einstein's brain function. The doctor who autopsied Einstein noted that he didn't have any more neurons than the average man. What he did have was a greater population of glia cells. This was Greek to me, but a little research made clear why this contributed to Einstein's genius.