CAREER: Social tolerance and the neurobiology of group living

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Why do some individuals come together to live in groups while others are solitary? This project investigates the brain basis of behaviors that promote formation of social groups. Meadow voles provide an ideal opportunity to study mechanisms that support social grouping because they naturally transition between solitary and colonial in the wild, depending on the season. In summer, meadow voles maintain individual territories, while in winter they come together to form communal nesting groups. The goal of this research program is to understand how the nervous system changes to support this transition to sociality. By mimicking summer and winter day lengths in the laboratory, researchers can drive changes in meadow vole social behavior. These changes in behavior are accompanied by physiological changes in signaling pathways involved in stress, fear, and affiliation. This CAREER award focuses on how the pathways that change alongside social behavior are involved in shaping different aspects of social behavior including avoidance of unfamiliar individuals, social interest and tolerance, and preferences for specific companions. The proposed studies cross levels of analysis—connecting molecules, brain, and behavior to reveal neural mechanisms underlying the tendency to form social groups. These research activities are coupled to educational goals that will provide numerous training opportunities for undergraduate and graduate students, and will lead to the development of a new undergraduate research course to engage students in inquiry-driven learning. For species that live in groups, peer social interactions are fundamental to group structure, and relationships regularly form between group members who are not reproductive partners. These relationships can be supported by prosocial factors such as motivation for social interaction, and/or by lack of antisocial tendencies such as avoidance, intolerance, and social fear. This project will test the hypothesis that winter sociality in meadow voles is facilitated by relaxation of antisocial factors including territoriality and fear, promoting social tolerance. Targeted pharmacological and viral manipulations will be used to investigate the functional role of seasonal changes in three pathways related to social fear and arousal. Specifically these include (1) the role of seasonal changes in oxytocin receptor signaling in mediating social selectivity and interaction with novel individuals; (2) how day length-mediated changes in corticotropin releasing factor signaling in specific brain regions influence social behavior; and (3) the role of seasonal changes in autonomic nervous system regulation. Understanding the neural causes and consequences of social grouping in meadow voles will yield fundamental insights into how non-reproductive relationships are mediated. The complementary educational plan focuses on undergraduate research training in the laboratory and classroom. These activities will make use of the data sets generated within this proposal and engage students in studying behavioral and physiological variation in meadow voles.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.