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Stanford Researchers Use AI to Finally Prove Men’s and Women’s Brains Behave Differently

Published: February 21, 2024
A view of Hoover Tower through the arches of the Main Quadrangle on the campus of Stanford University in Palo Alto, California. (Image: David Madison/Getty Images)

Using a new artificial intelligence (AI) model researchers from Stanford Medicine have finally proven that men’s and women’s brains behave differently.

According to peer reviewed findings published on Feb. 19 in the Proceedings of the National Academy of Sciences the model was successful in determining whether scans of brain activity came from a man or a woman 90 percent of the time.

“The findings … help resolve a long-term controversy about whether reliable sex differences exist in the human brain,” a statement concerning the findings reads. 

Senior study author, Vinod Menon, said in the statement, “This is a very strong piece of evidence that sex is a robust determinant of human brain organization … overlooking sex difference in brain organization” may hinder proper treatment and diagnosis of neuropsychiatric conditions.

“A key motivation for this study is that sex plays a crucial role in human brain development, in aging, and in the manifestation of psychiatric and neurological disorders,” said Menon, PhD, professor of psychiatry and behavioral sciences and director of the Stanford Cognitive and Systems Neuroscience Laboratory. “Identifying consistent and replicable sex differences in the healthy adult brain is a critical step toward a deeper understanding of sex-specific vulnerabilities in psychiatric and neurological disorders.”

The AI model examined “hotspots” in the brain that helped it differentiate between a male or female brain. These hotspots include the “default mode network,” which is a brain system that helps us process self-referential information, and the “striatum and limbic network,” which are “involved in learning and how we respond to rewards.”

The researchers noted that their findings do not speak to whether sex-related differences arise early in life or are driven by hormonal differences. The findings also do not speak to whether or not societal circumstances influence brain behavior between the sexes. 


Mystery solved

“Researchers have long struggled to connect sex to concrete differences in the human brain,” the researchers said, adding that, “Brain structures tend to look much the same in men and women, and previous research examining how brain regions work together has also largely failed to turn up consistent brain indicators of sex.”

This, however, has all changed with this recent study.

“The model’s success suggests that detectable sex differences do exist in the brain but just haven’t been picked up reliably before. The fact that it worked so well in different datasets, including brain scans from multiple sites in the U.S. and Europe, make the findings especially convincing as it controls for many confounds that can plague studies of this kind,” researchers wrote. 

It’s been understood for some time that cognitive differences between men and women exist.

According to Diane Halpern, PhD, past president of the American Psychological Association, writing for Stanford Medicine Magazine in May 2017, “Women’s reading comprehension and writing ability consistently exceed that of men, on average. They outperform men in tests of fine-motor coordination and perceptual speed. They’re more adept at retrieving information from long-term memory.”

“Men, on average, can more easily juggle items in working memory. They have superior visuospatial skills: They’re better at visualizing what happens when a complicated two- or three-dimensional shape is rotated in space, at correctly determining angles from the horizontal, at tracking moving objects and at aiming projectiles,” among other things.

However, until the more recent findings concrete differences in brain organization alluded researchers. 


‘Explainable AI’

Menon says that his research utilized an AI tool called “explainable AI,” which can sift through vast amounts of data to explain how an AI model makes a decision. 

Without the tool, the AI model could sift through and sort brains into different groups but wouldn’t provide any information as to why the sorting happened. 

Using the tool Menon and his team “identified the brain networks that were important to the model’s judgment of whether a brain scan came from a man or a woman.”

His team created sex-specific models of cognitive abilities and successfully predicted cognitive performance in men but not women and vice versa, indicating that brain characteristics vary between sexes.

Menon says that the model can be used to answer other questions about the brain and that he and his team plan to make the AI model public for other researchers to use.

“Our AI models have very broad applicability,” Menon said. “A researcher could use our models to look for brain differences linked to learning impairments or social functioning differences, for instance — aspects we are keen to understand better to aid individuals in adapting to and surmounting these challenges.”