While a number of studies have shown that the early social environment can have a significant effect on the subsequent expression of social behavior, these studies have either failed to examine the effects of early social experience on control mechanisms, (changes in the brain), or have been conducted in relatively asocial species. The aim of this project is to use the highly social bi-parental prairie vole (Microtus ochragaster) to study the effect of early social environment on the organization of the brain, specifically effects on neuropeptides, steroids and their receptors, in regulating the ultimate expression of social behavior. This study takes advantage of significant population differences in the expression of social behavior, with prairie voles from Kansas (KN) expressing significantly lower levels of prosocial behavior and higher levels of aggression than voles from Illinois (IL). These differences are also associated with differential expression of the central mechanisms. The research will examine the effect of parent of origin and the presence of the father on the expression of social behavior and mechanisms that regulate the expression of behavior. The heritability of the mechanisms controlling social behavior will also be determined. The expression of social behavior will be directly related to the degree of social interaction during the neonatal period. These changes will be associated with specific changes with the central nervous system, such as an increase in the presence of estrogen receptors in less social males. This study will provide critical understanding of how early experiences act to mold the ultimate expression of behavior. Broader Impacts include significant educational opportunities for undergraduate participation in research, with an emphasis on minority inclusion through the McNair program and interdisciplinary studies with Sociology.
Using two socially distinct populations of prairie voles one from Kansas and the other from Illinois this research tested the effect of the parent of origin and the early social environment on the expression of social behavior and the expression of the underlying mechanisms, vasopressin and oxytocin, in the brain that regulate social behavior. Illinois prairie voles are socially monogamous with a family structure that is very similar to humans which consists of a mother and father rear and caring for their offspring together. While Kansas prairie voles can form family units they are less social and males typically display many characteristics associated with polygynous males, such as increased aggression, larger males and lower levels of prosocial behavior. Cross-fostering and cross-breeding between populations was used to determine the effects of rearing environment and parent of origin on the expression subsequent adult social behavior. The significant behavioral findings from these studies were that early social environment does effect the subsequent expression of adult social behavior and that male behavior is influenced by the maternal population of origin but not the paternal. Which means mom influence the behavior of her sons more than dad. Specifically in the cross-fostering study less social Kansas pups raised by Illinois parents displayed higher levels of prosocial behavior and lower levels of aggression while in the cross-breeding study males with Kansas mothers were more aggressive and less social compared to males with Illinois mothers regardless of whether the father was from Kansas or Illinois. These differences were associated with changes in the expression of oxytocin and not vasopressin in the brain with more aggressive and less social males displaying lower levels of cells in the brain that produced oxytocin. This research provided hands on research opportunities for 16 students, three graduate, ten undergraduate (one underrepresented minority) four of which were honors students, and three high school students (all underrepresented minorities). Their experiences included learning animal care, conducting behavioral tests, tissue preparation, and data analysis. Many of the students were authors and/or coauthors on local and national presentations.
