Research

Neural substrates of peer affiliation

What determines whether an organism is solitary or lives in social groups? Despite reasonable understanding of the costs and benefits of sociality, little is known about the biological mechanisms that promote sociality. Decades of research have explored the neurobiology of parental behavior and monogamy; our work focuses on the pathways that support affiliation between peers.
Meadow voles are territorial during the summer reproductive season, but huddle in groups in the winter. Day length variation in the laboratory induces a behavioral shift in huddling behavior, allowing us to explore the proximate mechanisms including neurotransmitters, neuropeptides, hormones, and circuits that affect social bonding between same-sex individuals. More recently, we have begun to study peer affiliation in prairie voles to provide an understanding of how peer affiliation is similar or different in a monogamous vole species. Both species of voles are hard at work, pressing levers to gain access to familiar peers!

Neuropeptides and sociality

We are examining neurobiological correlates of social behavior in field collected samples from South American rodents. One such effort is comparing the oxytocin receptor systems of social and nonsocial rodents from the genus Ctenomys (tuco-tucos). Tuco-tucos are special because they belong to a species-rich group of social and solitary congeners who share a polygamous mating system. This has allowed us to explore the neural circuits that may be involved in social behavior outside the context of sexual pair-bonding. Initial work focused on two species from similar habitats in the Limay river valley of Argentina. More recently I have extended this analysis to a broad range of tuco-tucos from Argentina, Uruguay, and Peru, as well as degus. Related side-projects involve Alaskan Taiga voles, Belding’s ground squirrels, and hamster species.

Sex bias in subject use, variability and sex

The vast majority of biological research is performed on male animals. There are many important functional differences between male and female organisms, so this sex bias has important negative implications for both scientific understanding and for women’s health. With Dr. Irv Zucker, I published a comprehensive analysis of bias across 10 biological disciplines in 2011. Following on the demonstration that female mice are not more variable than males, we are now undertaking a laboratory study of why and how trait variability is similar across males and females in both cycling and non-cycling species.

Early life experience/plasticity in the brain

Exposure of rat pups to high or low levels of maternal care-giving in the first few days of life can alter the regulation of stress-reactivity and other phenotypic outcomes into adulthood. These changes in behavior accompany changes in gene expression and DNA methylation. We examined the effects of early life maternal care on social behavior, as well as experience-dependent changes in epigenetic regulation of genes in central and peripheral tissues. In more recent work, we are focusing on how gestational nutritional exposures are linked to later behavior via epigenetic pathways.