How Is Your Brain Wired?
By Jennifer Wider, M.D.
Society for Women’s Health Research
March 1, 2005
Researchers at the University of California, Irvine, recently discovered
structural differences in the brains of men and women in the areas responsible
for thinking and transferring information.
“We studied general intelligence, which is the same between men
and women,” said Richard Haier, lead researcher and professor of
psychology at the Department of Pediatrics at University of California,
Irvine. “But we looked at structural brain differences and found
that gray and white matter areas differed. This suggests to us that the
brain has different ways to accomplish the same thing in men and women.”
Gray matter is where information is processed in the brain. White matter
is a bundle of fibers that contain connections among brain cells.
“The connections among neurons might be better in women,”
Haier theorized. “Women’s brains may be more efficient.”
Women and men perform equally well on intelligence tests, but a growing
body of research shows that the brains of women and men process information
differently at a biological level. More studies are needed to understand
the functional effects of these differences.
Previous studies have shown that, in general, men seem to perform better
on tasks that require spatial reasoning and advanced mathematical skills;
whereas women outperform men in areas including verbal reasoning and memory.
These differences may explain why some women and men often take different
career paths.
“The difference in the number of women in high end mathematical
reasoning careers may be a reflection of differences in gray and white
matter,” Haier said. Women may gravitate toward careers involved
more with verbal reasoning. But because there are no apparent sex differences
in measures of intelligence and intellectual capacities, other factors
may play a role in career choices.
There is a tremendous amount of overlap between the abilities of men and
women, so it is important to examine cultural, social and economic influences
as well.
In many countries, for example, the difference in performance in science
and mathematics between boys and girls is not statistically significant.
This implies that factors beyond brain structure play a role.
“There is so much overlap between the abilities of men and women
that we cannot predict an individual’s performance solely on the
basis of whether they are male or female,” Sherry Marts, vice president
of scientific affairs for the Society for Women’s Health Research
said. “We must be careful to not over apply generalizations about
brain structure to individuals.”
Marts points to social and environmental factors as indicators of brain
performance.
“In addition to biological sex,” Marts said, “many other
factors have an impact on brain development. Beginning with the environment
in uterus and continuing throughout an individual’s life, the body’s
internal environment combines with external conditions such as nutrition,
physical activity, parental educational levels and the availability of
educational opportunities to have a profound impact on brain development
and function.”
The UC Irvine study may also help elucidate gender differences in neurological
diseases such as Alzheimer’s disease.
“You may not see the symptoms of Alzheimer’s disease in women
as early in the disease process as you would in men,” Haier said.
Stronger verbal and memory skills in women may explain why some women
are diagnosed later with the disease than men. In addition, certain diseases
that cause brain cell loss in the cerebral cortex are more damaging to
women because women appear to have a lower number of brain cells in that
specific area of the brain when compared with men.
There are gender differences in certain brain injuries as well. Frontal
brain injuries can be more serious in women: “cognitive impairment
is greater in women,” Haier said. These types of injuries can be
more harmful to the intelligence and cognitive processing of women than
men.
From intelligence to illness and injuries, additional brain research holds
the key to understanding much of human health and performance.
Sources
Kimura D. Sex Hormones Influence Human Cognitive Pattern. Neuroendocrinology
Letters 2002; 23(Suppl.4):67–77.
Haier, R. Neuroimage, Jan. 16, 2005 online edition. News release, University
of California, Irvine.
Rabinowicz, T., et al., Structure of the cerebral cortex in men and women.
J Neuropathol Exp Neurol, 2002. 61(1): p. 46-57.
© March 1, 2005 Society for Women's Health Research