University Honors

Beginning with a base population of outbred Hsd:ICR strain mice in 1993, four replicate High Runner (HR) lines have been bred for high voluntary wheel-running activity in the Garland lab, while four non-selected Control (C) lines have also been maintained. The selection criterion is the number of wheel revolutions recorded on the fifth and sixth day of a six-day test when mice are young adults. After reaching selection limits at generations 17-27 (depending on sex and line), the High Runner lines run approximately three times as many revolutions/day as their Control counterparts. The High Runner lines have evolved various adaptations conducive for high physical activity, such as increased maximum aerobic activity. High Runner lines also exhibit differences in behavior, such as heightened predatory aggression against crickets and building smaller thermoregulatory nests. In this study, we test the hypothesis that High Runner mice have other differences in behavior that might represent a distinct personality. As part of a larger study, we conducted unconditioned elevated plus maze tests to investigate exploratory behavior, boldness, anxiety, and fear. Currently, analyses from the elevated plus maze do not indicate statistically significant differences between the High Runner and Control lines for either sex. More research is needed to produce a behavioral profile of the High Runner mouse model.