"There's also a grain of truth, revealed through the brain structure,
              that we think underlies some of the ways people characterize the
              sexes."

              Scientists at Johns Hopkins have discovered "striking"
              differences between men and women in a part of the brain linked
              with ability to estimate time, judge speed, visualize things
              three-dimensionally and solve mathematical problems. The
              differences, the researchers say, may underlie well-known trends
              that vary by sex, such as the fact that more men than women are
              architects, mathematicians and race-car drivers.

              In a study reported this week in the journal Cerebral Cortex, the
              researchers show that a brain region called the inferior parietal
              lobule (IPL) is significantly larger overall in men than in women.
              The area is part of the cerebral cortex and appears on both sides
              of the brain, just above ear-level.

              Also, there's a symmetry difference, with men having a larger left
              IPL than right. In women in the study, it's the right IPL that's
              somewhat larger, though the difference between the two sides of
              the brain is less obvious than in men, says psychiatrist Godfrey
              Pearlson, M.D., who headed the project.

              "This is the same part of Albert Einstein's brain that was
              particularly large compared with controls," says Pearlson.
              "Scientists have noticed this region is also larger in the
              postmortem brains of other physicists and mathematicians."

              In the study, researchers reviewed MRI-scans of the brains of 15
              closely matched men and women. They used new computer
              software created by Hopkins psychiatrist Patrick Barta, M.D.,
              Ph.D. to compare overall IPL volume by gender. The software
              lets scientists highlight the IPL by "painting" it in on computer
              images of each subject's brain; it then calculates a highly accurate
              volume. Researchers also compared IPL volumes on the left and
              the right sides of the brain. After allowances for men's larger
              overall head and brain size, men had roughly 6 percent more IPL
              tissue than women.

              "The inferior parietal lobule is far more developed in people than
              in animals and has evolved relatively recently," says Pearlson. It
              allows the brain to process information from senses such as
              vision and touch, and enables the sort of thinking involved in
              selective attention and perception.

              Studies link the right IPL with a working memory of spatial
              relationships, the ability to sense relationships between body
              parts and awareness of a person's own affect or feelings. The left
              IPL, Pearlson says, is more involved in perception, such as
              judging how fast something is moving, estimating time and having
              the ability to mentally rotate 3-D figures.

              "To say this means men are automatically better at some things
              than women is a simplification," says Pearlson. "It's easy to find
              women who are fantastic at math and physics and men who excel
              in language skills. Only when we look at very large populations
              and look for slight but significant trends do we see the
              generalizations. There are plenty of exceptions, but there's also a
              grain of truth, revealed through the brain structure, that we think
              underlies some of the ways people characterize the sexes."

              Earlier research by Pearlson showed that two crucial language
              areas in the frontal and temporal lobes of the brain were
              significantly larger in women, perhaps explaining their advantage
              in language-associated thought.

              Other researchers in the study were Melissa Frederikse, M.D.,
              Angela Lu and Elizabeth Aylward, Ph.D. Funding was through the
              National Institute on Aging.
 

              Related Web Site: http://pni.med.jhu.edu