Women Have 'Thicker' brains Than Men

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Women are not too good at performing spatial tasks as compared to men. According to the researchers at the University of Iowa researchers found that a thicker cortex in the parietal lobe in women is linked to poorer mental rotation ability.

Women are not good in identifying how a 3-D object would appear if rotated in space. The new study shows n association between this sex-linked ability and the structure of the brain region that controls this type of skill.

The parietal lobe is differently developed in men and women, with women's parietal lobes having proportionally thicker cortexes or "grey matter." However, this difference was never linked back to actual performance differences on the mental rotation test.

The thicker cortex in women is linked to poorer mental rotation ability, as the the surface area of the parietal lobe is increased in men, compared to women. In men the greater parietal lobe surface area is directly related to better performance on mental rotation tasks.

"Differences in parietal lobe activation have been seen in other studies. This study represents the first time we have related specific structural differences in the parietal lobe to sex-linked performances on a mental rotation test," said Tim Koscik, the study's lead author and a graduate student in the University of Iowa Neuroscience Graduate Program.

"It's important to note that it isn't that women cannot do the mental rotation tasks, but they appear to do them slower, and neither men nor women perform the tasks perfectly," Koscik added.

The study was conducted on 38 women and 38 men, all right-handed except for two men. The groups were analysed for age, education, IQ and socioeconomic upbringing. When tested on mental rotation tasks, men averaged 66 percent correct compared to 53 percent correct for women. Magnetic resonance imaging (MRI) revealed an approximately 10 percent difference between men and women in the overall amount of parietal lobe surface area: 43 square centimeters for men and 40 square centimeters for women.

"It's likely that the larger surface area in men's parietal lobes leads to an increase in functional columns, which are the processing unit in the cortex. This may represent a specialization for certain spatial abilities in men," said Koscik.

The study showed that the brain structure in men and women are different and also perform tasks differently, according to Peg Nopoulos, M.D., a study co-author and professor of psychiatry and pediatrics at the University of Iowa Carver College of Medicine.

"One possible explanation is that the different brain structures allow for different strategies used by men and women. While men appear able to globally rotate an object in space, women seem to do it piecemeal. The strategy is inefficient but it may be the approach they need to take," said Nopoulos, who also is a psychiatrist with University of Iowa Hospitals and Clinics. AGENCIES