Human brain may be hard-wired by gender

  • Article by: Geoffrey Mohan
  • Los Angeles Times
  • December 7, 2013 - 4:02 PM


A map of the human brain may in fact be a two-volume edition, divided by gender, according to a new study that found significant differences between how the male and female brains are hard-wired.

Males tended to have stronger front-to-back circuits and links between perception and action, while women had stronger left-to-right links between reasoning and intuition, according to University of Pennsylvania Perelman School of Medicine researchers who imaged the brains of 949 adolescents and young adults.

Their maps of the brain’s so-called connectome, published online Monday in the journal Proceedings of the National Academy of Sciences, matched observed behavioral differences between the sexes. Women did better at tests of attention, word and face memory and cognition. Men did better on spatial processing, motor skills and sensorimotor speed.

The differences in the connectome have come to be called the hunter vs. gatherer divide by two of the main authors, the husband-wife team of Raquel and Ruben Gur. The results lend weight to growing evidence that humans have formed strong adaptive complementarity, suggesting that biological evolution predisposes the species to divide gender roles. That implication is sure to fuel debate over the roles of nature vs. nurture and the interplay of function and structure within the human brain. But they also could inform treatment of neurological disorders known to vary by age and sex, such as autism and schizophrenia.

“There is biology to some of the behavior we see among men and women,” said Ragini Verma, a University of Pennsylvania biomedical imaging analyst and lead author of the study.

“In the population, men have stronger front-back connectivity, and women have inter-hemispheric or left-right connectivity more than the men. It’s not that one or the other gender lacks the connectivity altogether, it’s just that one is stronger than the other,” Verma said.

That means men may be quicker on the perception-action path, while women better integrate the analytic side of the brain with the intuitive and social side. “So, if there was a task that involved logical and intuitive thinking, the study says that women are predisposed, or have stronger connectivity as a population, so they should be better at it,” Verma said.

“For men, it says they are very heavily connected in the cerebellum, which is an area that controls the motor skills. And they are connected front to back. The back side of the brain is the area by which you perceive things, and the front part of the brain interprets it and makes you perform an action. So if you had a task like skiing or learning a new sport, if you had stronger front-back connectivity and a very strong cerebellum connectivity, you would be better at it.”

Researchers used diffusion tensor imaging, a tool that can indirectly outline the path of myelinated axons, the “wire” section of neurons that facilitate long-range conduction of electrochemical signals and are part of the brain’s white matter. They looked at the brains of 428 men and 521 women, ages 8 to 22, who are part of a long-term study known as the Philadelphia Neurodevelopmental Cohort, conducted with the Children’s Hospital of Philadelphia.

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