Can a human brain be male or female? – Technologist

It’s a sensitive subject, to be approached with caution: A team of researchers from Stanford University, California, have chosen to study the human brain, questioning whether there were any relevant differences between men and women: Well, they found some. Their study, published in the February 20 issue of the journal Proceedings of the National Academy of Sciences (PNAS), is sure to provoke a reaction.

There was a time, not so long ago, when established researchers claimed that men were superior to women because their brain size was superior. That is, until it became clear that cranial volume is proportional to body size: A man who measures 1.95 meters tall wouldn’t be more intelligent than another just because he was 20 centimeters taller. QED.

This time, researchers from the Behavioral Sciences, Neurology and Human-Centered Artificial Intelligence departments at Stanford didn’t take such a crude approach. Gone are morphological comparisons! They were interested in the functional organization of our gray matter, not the shape or size of its various parts. Their conclusion is explicit: “Our study provides compelling evidence for replicable and generalizable sex differences in the functional organization of the human brain.” According to the authors, these “brain features accurately predicted sex-specific cognitive profiles” and that these “sex differences in functional brain dynamics are not only highly replicable and generalizable but also behaviorally relevant.”

Differences identified

How did they arrive at such assertions? Their basic research material consisted of functional MRI scans (fMRI) of some 1,500 individuals of both sexes aged between 20 and 35. This imaging technique, which allows for the indirect visualization of brain activity, was used on the default mode network – in other words, the pattern of activity across the brain’s regions that is active when we do not focus on the outside world, and when our attention is not required. “This is what the brain does when the mind wanders between associations of ideas and memories, for example. This resting activity is our brain’s signature,” explained Sylvie Chokron, a research director at the prestigious French National Centre for Scientific Research (CNRS) and the Psychology of Perception Laboratory of Paris-Descartes University, as well as a regular contributor to Le Monde.

To study this material, the American team developed a spatiotemporal deep neural network (stDNN) model, which they described as a form of explainable artificial intelligence (AI), as opposed to the black boxes that some AIs constitute. Trained on over a thousand cases, this artificial intelligence model was then tested using other fMRIs. The result? In over 90% of cases, the model was able to distinguish men’s brains from those of women. The differences identified in several brain areas (the default mode network, striatum, and limbic network) were precise enough to make it a reliable classification tool.

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