UC Davis

This dissertation focused on variables that affect social behavior of California mice (Peromyscus californicus) first with a literature review. Subsequent experiments examined the effects that routine laboratory conditions may have on the behavior as well as the neurotransmitter Oxytocin in specific areas of the paraventricular nucleus. Chapter 1 discusses the types of variables that may contribute to varying behavioral neuroscience results. Rodents are the largest species of animals used for scientific research yet results from these studies produce conflicting conclusions. We found through an extensive literature review that variables such as transportation methods, social environment, circadian rhythms, and the home cage environment all can have profound effects on behavior that may mask the effects of experimental variables. We ask that researchers studying behavior, especially those in the field of neuropsychopharmachology, consider these variables when designing their studies and improve reporting methods. Chapter 2 examined the effects that olfactory cues or witnessing/interacting with a stressed individual had on the behavior of California mice. This study was conducted in order to examine routine laboratory methods on the social behavior of California mice. The results from the study found that cage changes the morning of behavior testing and olfactory cues were not significant enough disruptors to affect social approach behavior. Interestingly, when a non-stressed animal interacted with a stressed animal, they spent less time approaching a novel con-specific mouse compared to controls. Chapter 3 focused on the neurotransmitter oxytocin, which is heavily involved in social behavior, and its effects in the anterior and posterior paraventricular nucleus (PVN). The PVN has two anatomically distinct parts, the anterior made up primarily of large magnocellular neurons and the posterior that contains primarily the smaller parvocellular neurons. Both of these cell types are capable of producing oxytocin but project to different regions of the brain. Through pharmacological intervention with in-vivo morpholinos, oxytocin was successfully reduced in either the anterior or posterior PVN. Female mice did not express any difference in behavior when knockdown of oxytocin occurred in the anterior PVN but both males and female mice decreased social approach behavior with knockdown of oxytocin in the posterior PVN.