Neural mechanisms of social behavior in rodents

Trustees Of Boston University, Boston

Investigators

Abstract

Animals of all species need to recognize potential mates and known foes, and adjust their behavior accordingly. The brain has evolved hardwired neural pathways for controlling key social behaviors like aggression and mating, but basic organizing principles of these neural circuits remain poorly understood. This project tests how pheromonal signals-- chemical signals that impact behavior of the receiving organism-- are used to guide reproduction-specific behaviors, and how the corresponding neural pathways are altered by social experience. Like many animals, male mice form dominance hierarchies that strongly influence their behavior, where aggression is reduced in low-status males and preserved or increased in high-status males. The present experiments examine how becoming familiar with new social partners changes the way their pheromonal signals are processed in the brain, shifting thresholds for triggering aggressive behavior in dominant and submissive animals. First, to examine the basic biological processes that underlie learning, the investigators use single-neuron recordings to test the cellular changes that alter their responses to familiar individuals. Second, the investigators use new tools for visualizing neural activity during active social interactions, evaluating how familiarity shapes the patterns of brain activity corresponding to both dominant and submissive partners. Overall, this work addresses the neural changes that allow animals to adapt their behavior to reflect the history of their social experience with others. The project also offers opportunities for local high school students and undergraduate trainees from diverse backgrounds to engage in neuroscience research, including the use of cutting-edge technologies, and includes the development and dissemination of educational materials for local elementary schools and a science museum. Key social behaviors, such as aggression, reproduction, and parenting are controlled by conserved neural circuits with strong similarities across species. Despite their critical role, little is known about the pathways that translate sensory cues into male- and female-appropriate behaviors. This project characterizes neural coding and plasticity in the mouse vomeronasal system, which plays a key role in mapping social chemosignals onto sex-specific responses. The main hypothesis of this work is that distinct behaviors are mediated by dedicated pathways in the accessory olfactory system, which are selectively altered by social experience to reflect individual relationships. It focuses primarily on aggression, a core male behavior that is rapidly and reliably triggered by other males, yet is also dramatically altered as animals establish dominance relationships. To characterize experience-dependent changes in aggression, these experiments combine ex vivo cellular electrophysiology and in vivo imaging of activity in the accessory olfactory bulb, a key node for routing sensory signals to central behavioral networks. The resulting data will address basic principles of sensory coding in a circuit intimately linked to innate behaviors, as well as characterize a novel form of cellular plasticity that may support adaptive changes in diverse social interactions. Together, this work helps establish how the brain organizes and routes the sensory signals that guide stereotyped behavioral responses, while still allowing flexibility in interactions with familiar partners. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.