Sex hormones like testosterone can influence how the brain processes recognition of others in as little as 40 minutes, finds new research from the University of Guelph (U of G). The findings reveal how the brain quickly modulates social information processing — a function essential for everything from forming relationships to navigating social hierarchies.
The study, published in the Proceedings of the National Academy of Sciences, identifies a specific brain circuit through which these hormones sharpen “social recognition memory,” which is the ability to distinguish between familiar and unfamiliar individuals.
Dr. Elena Choleris, senior author of the study and professor of neuroscience in the Department of Psychology, says social interactions depend on the brain’s ability to determine who is familiar and what information matters.
“Our findings show that steroid hormones can rapidly modulate neural circuits involved in social cognition,” she says.
Dr. Choleris supervised Dr. Dario Aspesi who led the research while completing his PhD at U of G, and who is now a postdoctoral fellow at Georgia State University.
The team says that while scientists have long known that steroid hormones play a role in social behaviour, exactly how they act in the brain and how quickly has remained unclear.
In this study, they focused on a pathway connecting the bed nucleus of the stria terminalis and the lateral septum, brain regions known to play important roles in social recognition in rodents, especially in males.
The Science Behind Studying the Minds of Mice
Using a mouse model, the team found that testosterone and its metabolites, 17β-estradiol (E2) and dihydrotestosterone, significantly improved short-term social recognition memory within just 40 minutes of being administered directly into the brain.
Although all three hormones produced the same behavioural effect, they acted through different biological mechanisms. Testosterone and E2 relied on estrogen receptors and interacted with arginine–vasopressin, a neurochemical known to regulate social behaviour. In contrast, dihydrotestosterone acted through androgen receptors independently of vasopressin pathways.
The Meaning of Mice Memory and Hormones
The findings show that the brain can use multiple hormonal pathways to achieve the same behavioural outcome, and that closely related hormones can act in distinct ways.
The researchers also found evidence of a trade off between different forms of cognition: while these hormones enhanced social memory, they impaired forms of non-social memory, suggesting that hormonal states may dynamically shift how the brain allocates processing resources between social and non-social information.
In animals, social recognition is critical for survival, supporting behaviours such as forming social hierarchies, identifying mates and navigating complex environments. Because the experiments were conducted in mice using direct brain administration of hormones, the findings cannot be directly generalized to human behaviour. However, many of the same hormones, receptors and brain circuits are conserved in humans, making the work relevant for understanding basic mechanisms of social cognition. Disruptions in hormone signaling and social processing have been implicated in several psychiatric and neurodevelopmental conditions such as social anxiety, personality disorders and autism spectrum disorders.
Mapping Hormonal Pathways
By identifying the specific receptors and neural pathways involved, the study provides a foundation for future research into how hormonal systems influence social cognition and memory. It also highlights the complexity of hormone action, showing that a single hormone such as testosterone can exert its effects through multiple pathways depending on how it is metabolized in the brain and which receptors are engaged.
The work builds on ongoing research at the University of Guelph exploring how estrogens and androgens regulate memory and cognition. The study involved collaboration among researchers across several departments, as well as international partners, reflecting the interdisciplinary nature of the research.