The Dramatic Differences in Male and Female Brain Connectivity

By creating highly detailed connectome maps of nearly 1,000 men, women, boys, and girls, neuroscientists have shown the dramatic extent to which male and female brains are "wired" differently — cognitive variations that may help to explain why men and women fare better at certain tasks.

Of course, we know that our brains don't actually have wires, nor are we "hardwired" in the same way our technologies are. But the analogies aren't entirely useless; certain parts, or modules, of our brain are connected by a kind of neural circuitry. These linkages can be shown in structural connectome maps, much like the one shown in this article's header image (credit: nibib.nih.gov).

Structural connectomes are created using diffusion tensor imaging, and they're providing neuroscientists with an unprecedented glimpse into the inner workings of the human brain.

Looking to learn more about potential morphological differences in the way male and female brains are interconnected, a team from the University of Pennsylvania embarked on a significant study involving 949 individuals.

Adaptive Complementarity

The resulting scans showed that women's brains were highly connected across the left and right hemispheres, whereas in men's brains, the connections were typically stronger between the front and back regions. Put another way, female brains appear to be optimized for inter-hemispheric communication, and male brains for intra-hemispheric communication. These structural changes happen at a young age, which may explain why we start to see stark differences in male and female behavior during adolescence.

Image: The top two brains are male, the bottom two female.

The Dramatic Differences in Male and Female Brain Connectivity

The scientists also say that these variations may explain why males have better motor and spatial abilities, while females have superior memory and social cognition skills.

"Overall, the results suggest that male brains are structured to facilitate connectivity between perception and coordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes," note the authors in the study, which now appears in PNAS. These differences may explain why men tend to be better at learning and performing a single task, like cycling or navigating, and why women are better at multitasking, say the researchers.

The same volunteers performed a series of cognitive tests which appeared to support these notions; women did well on tasks related to attention, word, and facial memory, whereas men did well on spatial processing and sensori-motor speed.

Reading Too Much Into It?

That said, words of caution would seem appropriate. Check out these remarks from one of the researchers, Ragini Verma:

If you look at functional studies, the left of the brain is more for logical thinking, the right of the brain is for more intuitive thinking. So if there's a task that involves doing both of those things, it would seem that women are hardwired to do those better. Women are better at intuitive thinking. Women are better at remembering things. When you talk, women are more emotionally involved – they will listen more. I was surprised that it matched a lot of the stereotypes that we think we have in our heads. If I wanted to go to a chef or a hairstylist, they are mainly men.

Yikes! Careful, now, neuroscientists. Let's not take these findings too far. This study was just a map of sex differences in the human connectome with some possible correlations to the results of cognitive tests.

Indeed, as neuroscientist Heidi Johansen-Berg told the BBC, the brain is far too complex to make such broad generalizations:

We know that there is no such thing as 'hard wiring' when it comes to brain connections. Connections can change throughout life, in response to experience and learning. Often, sophisticated mathematical approaches are used to analyse and describe these brain networks. These methods can be useful to identify differences between groups, but it is often challenging to interpret those differences in biological terms.

Read the entire study at PNAS: "Sex differences in the structural connectome of the human brain".

Image: National Academy of Sciences.
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