Читать книгу Brain Fitness for Women - Sondra Kornblatt - Страница 15

New studies of brains use functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), both of which measure blood flow and produce three-dimensional imaging. Researchers compared male and female brains and compared the brains of those doing puzzles to those meditating, those looking at happy pictures or at sad ones, or those just listening or responding actively in a conversation. They've measured the sizes of brain components and the blood flow to areas that were active; the results were pictures of brains filled with bright blobs of color indicating which sections were active.

These studies aimed to show that male and female brains are significantly different at birth in many areas. Supposedly:

 Males have better right-hemisphere skills, such as those involved in art, music, and math, due to the testosterone male embryos receive; females are better at communicating, observing, and processing emotion.

 Males are better able to systematize and are more aggressive than females, also because of this infusion of testosterone in male embryos; females have more collaborative and verbal brains.

 Compared to men, women have the stronger ability to “mirror” others, feeling what others are feeling or sensing what others are thinking.

 Men have a larger amygdala, dubbed the “instinctual core of the brain,” than women.

 Women worry more than men because their anterior cingulate cortex is larger.

 Women have more neurons for language processing and comprehension in the temporal lobe cortex than men have.

 The corpus callosum, a pathway of 200 to 250 million nerve fibers between the right and left hemispheres, is larger in women than in men. This greater number of cross-brain connections means women are better at activities involving both sides of the brain, and men are better at activities requiring the focus of one side or the other.

But several authors have called these studies on the carpet. They scientifically challenged whether (1) our advanced instruments tell as much as we’d like, (2) the assumptions they tell are true, and (3) the studies are large enough for their statistics to have veracity.

For instance, when looking at the corpus callosum, some studies found that it is the same size in men and women, and other studies found that it's bigger in men. Studies also question whether having a larger right hemisphere means increased learning or more difficulty learning. And while the anterior cingulate cortex is the part of the brain that generates worry, this part is also involved with a wide variety of cognitive, motor, and emotional tasks, such as decision-making; so it makes as much sense to say that a larger anterior cingulate cortex means women think better than men, instead of that women worry more.

Cordelia Fine, author of Delusions of Gender, says that these studies are looking at the brain through traditional assumptions. It's just like 1915, she says, when studies “proved” that women couldn't judge political initiatives and couldn't vote, all because they had smaller upper spinal cords. The results of these studies are similarly biased because of what she calls neurosexism. ¹⁷

We are starting to get larger and more valid studies about gender and the brain, which we hope will clarify the issue. And we know some consistent male-female brain differences in animals and humans from previous decades of study.