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Male and Female Brains Wired Differently

The brains of men contain stronger front-to-rear connections while those of women are better connected from left to right.

By | December 4, 2013

WIKIMEDIA, MINIME 12358New research on the neural connections within the human brain suggests sex-based differences that many have suspected for centuries: women seem to be wired more for socialization and memory while men appear geared toward perception and coordinated action. The female brain appears to have increased connection between neurons in the right and left hemispheres of the brain, and males seem to have increased neural communication within hemispheres from frontal to rear portions of the organ. University of Pennsylvania researchers announced the results, generated by scanning the brains of about 1,000 people using a technique called diffusion tensor imaging, on Monday (December 2) in the Proceedings of the National Academy of Sciences (PNAS).

UPenn Perelman School of Medicine radiologist Ragini Verma and colleagues scanned the brains of more than 400 males and more than 500 females from 8 to 22 years old and found distinct differences in the brains of male versus female subjects older than age 13. The cortices in female brains were more connected between right and left hemispheres, an arrangement that facilitates emotional processing and the ability to infer others’ intentions in social interactions. In male brains, however, the cortex was more connected to rear brain regions, such as the cerebellum, which suggests greater synergy between perception and action.

“There is biology to some of the behavior we see among men and women,” Verma told the Los Angeles Times. “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.”

These physiological differences, which didn’t appear in stark contrast in those under 14, could possibly give rise to behavioral differences between the sexes. “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 told the LA Times. “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.”

Studying the structural and function differences between male and female brains could help ferret out causes and possible treatments for certain brain disorders, the authors suggested. “It’s quite striking how complementary the brains of women and men really are," Ruben Gur, a co-author on the study, said in a statement. “Detailed connectome maps of the brain will not only help us better understand the differences between how men and women think, but it will also give us more insight into the roots of neurological disorders, which are often sex-related.”

But at least one researcher is questioning the argument that Verma and her team are making for the neural connectivity differences they found being a function of sex. “One important possibility the authors don’t consider is that their results have more to do with brain size than brain sex,” wrote University of Melbourne social and developmental psychologist Cordelia Fine in a blog post published by The Conversation. “Male brains are, on average, larger than females and a large brain is not simply a smaller brain scaled up.”

Fine, who wrote 2011’s Delusions of Gender, a book that seeks to counter propositions that sex-based differences are biologically hardwired, explained that larger brains must be organized differently to deal with increased energy demands, decrease communication times, and minimize wiring costs. She cited an earlier study published by the same group at UPenn, also published in PNAS, which reported differences between how males and females performed on a spate of psychological tests.

“Rather than drawing on their impressively rich dataset to empirically test questions about how brain connectivity characteristics relate to behavior, the authors instead offer untested stereotype-based speculation,” wrote Fine. “These characteristics of the [current] PNAS study are very common in neuroscientific investigations of male/female sex differences, and represent two important ways in which scientific research can be subtly ‘neurosexist,’ reinforcing and legitimating gender stereotypes in ways that are not scientifically justified.”

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Avatar of: Stuart21

Stuart21

Posts: 7

December 4, 2013

So, Cordelia, we need to plot F / R & R / L variation as a function of brain size, irrespective of gender. See which correlation is stronger. Should not be too difficult to do if orig data was complete or subjects still accessible.

I would like to see the study extended to the many other 'genders'.

Just for interests sake.

December 4, 2013

This sounds like the same old nature vs nurture argument again. PC vs Macintosh. I went to a Dr once who told me I needed to take certain medication. I said I was a student and low on funds. He told me about a slower home treatment to make that I could use. Another time the doctor just gave me some free samples. Went to my dentist he said I needed one tooth taken out, he could save the other. Went to Dentist who takes out teeth he said they both must come out, its a must. I said my dentist said he could save the one. Was in the ER once the doctor said my spleen must come. My sister demanded a second opinion. I still have my spleen..........

Dr Lissa Rankin MD shows how mind works over matter. DR Amen MD uses brains scans successfully. Were does the debate end. What's the real motive? AC vs DC? We use both. Sheep self medicate so do butterflies. And the squirrels warn the rest of the woods hunters are coming. The coelacanth was thought extinct and if man were meant to fly he would have wings. The best line I heard in a research lab “put some electrodes on a real person.” How many people will die before they put up that needed stop light?

December 4, 2013

Dr David Page MD, Head of the Whitehead institute at MIT, said male and females cells “go about their business of making proteins differently.”

 

Many use our differences as a means of superiority

Martin Luther King had a dream of equality.

The French say vive la différence!

Jesus said, “in the beginning he made them male and female.”

 

Avatar of: James V. Kohl

James V. Kohl

Posts: 110

Replied to a comment from primativebeliever made on December 4, 2013

December 4, 2013

Nutrient-dependent pheromone-controlled adaptations lead to sex differences in unicellular yeasts "Signaling Crosstalk: Integrating Nutrient Availability and Sex." The same epigenetically-effected molecular mechanisms lead to Mosaic Copy Number Variation in Human Neurons.

We explained that fact in our 1996 Hormones and Behavior review article: From Fertilization to Adult Sexual Behavior. The model that links microbes to man was then used to explain the development of the brain and behavior in the honeybee model organism more than a decade ago.

Vertebrate life histories were addressed in Feedback loops link odor and pheromone signaling with reproduction. Invertebrate life histories were addressed in Honey bees as a model for understanding mechanisms of life history transitions 

Across species examples of the amino acid substitutions responsible for sex differences and species diversity are provided in Nutrient-dependent/pheromone-controlled adaptive evolution: a model.

Had Dobzhansky (1973) not attributed cause and effect to mutations, at least a few people might have by now realized that amino acid substitutions are obviously the cause of sex differences and species differences.

 

Avatar of: Neurona

Neurona

Posts: 29

December 9, 2013

This brain imaging study has an impressive sample size; with rampant misuse of statistical analysis in neuroscience, including imaging, I'd like to have some experts weigh in before I completely believe it.  

Even if all is by the book, Mr. Grant errs in referring to DTI data as having demonstrated "physiological differences" between male and female brains. DTI demonstrates structural differences, as it records the net flow of water molecules along myelinated tracts.  Any physiological correlate of those tract pathway differences is merely inferred, absent other kinds of testing.  

Conflating structure with function is no small error in the brain, in which we know that very early loss of tissue mass can be significantly compensated for by a subsequent alteration of the wiring diagram (e.g. the German girl with only one hemisphere).  I'm with Dr. Fine on this one; more myelinated tracts don't automatically constitute more ability.

Avatar of: cogsci

cogsci

Posts: 1

December 11, 2013

Given that these differences in wiring are only seen after age 13, couldn't it be the case that differences in male and female socialization and cultural environment caused the differences in wiring, rather than their being inherent?

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