MCAGE-ULTRA: SOCIAL HIERARCHIES AND PSYCHEDELIC MODULATION IN AUTOMATED MOUSE SOCIETIES

Social hierarchies regulate access to resources in both humans and animals. In wild mice, dominance is expressed via behaviours such as chasing, which can be continuously tracked in Eco-HAB, a fully automated, semi-naturalistic home-cage monitoring system. Using groups of C57BL/6 mice (male n = 30; female n = 30), we investigate (1) the stability of dominance hierarchies in Eco-HAB, (2) whether such hierarchies are flexibly formed across different social contexts, (3) if males and females differ in their hierarchical organisation, and (4) how hierarchy dynamics change following reproduction/parenthood (i.e., in fathers and mothers). Our findings show that hierarchies emerge within 2-3 days and remain stable in both males and females. Female hierarchies appear to be less hierarchical than males (i.e., chasing is reduced and is more equally distributed). Females are very flexible, taking the same social organisational structure in many different contexts. However, males are less flexible, evidenced via increased territoriality and fighting. Leading to a final question: (5) can we reduce male territoriality and fighting with psychedelics?
To examine the neural correlates of social rank, we additionally employed iDISCO whole- brain mapping and quantified c-Fos expression following exposure to a social scent cue. This approach provided insight into the circuits supporting dominance dynamics.
Together, these findings establish Eco-HAB as a powerful platform for studying social hierarchy regulation and motivate future work testing whether psychedelic interventions can reduce maladaptive male aggression and territoriality.