Difference between brains of women & men lies in activity patterns, could provide insights into psychiatric disorders: Study

Males and females show varying patterns of brain activity, suggesting that sex differences exist in the brain, according to a new study.

These differences can be seen in the regions such as the default mode network as well as the striatum and limbic network, which are involved in learning and reward.

Previous research had shown that males and females show anatomical differences. For instance, males have a larger total brain volume and more percentage of white matter (connects neurons within the gray matter to each other) whereas females have a higher gray matter percentage (regions where neurons are concentrated).

“Despite growing evidence of sex differences in structural human brain organisation, it is unclear whether and how these structural differences translate to functional brain organisation differences,” the paper published in the journal Proceedings of the National Academy of Sciences read.

The study focused on functional organisation to assess sex differences between males and females.

Functional brain organisation “refers to the dynamic patterns of brain activity, which are functional but localised to specific anatomical regions and brain system,” Vinod Menon, professor of psychiatry and behavioral sciences and director of the Stanford Cognitive and Systems Neuroscience Laboratory and one of the study authors, told Down To Earth.

These differences, he added, could also explain why males and females are vulnerable to certain psychiatric disorders. Females are more likely than males to experience depression, anxiety and eating disorders while autism, attention-deficit hyperactivity disorder and schizophrenia are more common in males.

The team trained a deep neural network model (a type of artificial intelligence that mimics the brain’s ability to process information) with functional magnetic resonance imaging, a type of imaging that tracks blood flow to “see” or map brain activity. When they tested the model on 1,500 brain scan images, its accuracy in identifying male or female brains was more than 90 per cent.

To understand how the model made its decisions, Menon and his team used a tool called explainable artificial intelligence. They saw that the model arrived at its decision by looking at patterns in the default mode network, striatum and limbic network.

The observed sex differences in the default mode network, striatum and limbic network, Menon explained, were primarily functional differences (varying brain activity levels and interactions), rather than anatomical differences.

The default mode network may influence how individuals perceive and reflect upon their own experiences during learning tasks. The striatum and limbic network, on the other hand, may potentially impact motivation, decision-making and responses to rewards between males and females, the author highlighted.

“Understanding these differences can inform tailored approaches to learning and reward-based interventions that better address the specific needs of each gender,” Menon added.

These findings could also provide more insights into neuropsychiatric disorders. Menon links observed differences in reward processing and emotional regulation to differences in vulnerabilities to mood disorders such as depression or anxiety between the sexes.

Similarly, he added, variations within the default mode network may contribute to differences in vulnerability to disorders characterised by disturbances in self-perception and social cognition. In the future, the team wants to study the neurobiology of sex differences in psychiatric disorders.