Ethobehavioral Studies of Fear, Sex, and Biological Rhythms

Abstract

All animals, to varying degrees, must make decisions regarding when and how to balance the need to acquire resources (“foraging”) and the need to avoid threats (“avoidance”). The neurobiological and psychological processes supporting strategy selection have evolved not just within specific ecological contexts, but they have also evolved to be plastic and integrate information across contexts and motivational states to promote survival and reproductive fitness. The research methods commonly used among behavioral neuroscientists are inadequate to understand the dynamics of neurobiological and psychological processes as integrated functions of space and time. The studies described in this dissertation explore a closed behavioral system which attempts to hold context constant in order to measure the temporal dynamics and functions of behavior. The first study demonstrates that cyclic experiences of fear can entrain circadian rhythms and reverse the “natural” active period of rats. The next study examines sex differences in behavioral decisions regarding approach-avoidance conflict in the closed behavioral system and in a novel foraging task containing an artificial predatory threat, and compares these results to traditional Pavlovian fear conditioning. Finally, the influence of female’s reproductive cycle on risky foraging behaviors is analyzed, demonstrating that a phase-specific increase in risky-taking behavior is not met with greater reward.