Sexually dimorphic processing of pheromonal information in mice

Animals exhibit appropriate social behaviors and physiological responses based on the opponent's sex. Mammals secrete sex-specific chemical cues, some of which act as pheromones and play crucial roles. Sex-specific pheromones are received by a largely sexually monomorphic detection system in the vomeronasal organ. Small populations of sensory neurons encode conspecific sex via sex-selective receptors, while complex traits are encoded by combinatorial neuronal activity. These signals are processed by sexually dimorphic dedicated neural circuits in the brain. Neural activity recording in these brain regions has revealed distributed neural encoding of sex and internal brain states associated with aggression and mating. Sex hormones play critical roles in establishing, remodeling, and modulating these systems across multiple levels, enabling adaptive responses. Emerging evidence in mice sheds light on how pheromonal information is transformed into the neural representation of sex and internal state through adaptive modulatory mechanisms, ultimately triggering appropriate sex-specific responses.