Optimization of laboratory conditions for the study of social behavior.

Social behavior--an action directed toward, or in response to, a member of the same species--is tightly regulated but also highly plastic. It is influenced by many internal (e.g., age, hormonal state, and experience) and external (e.g., time of day, availability of food, encounters with conspecifics) factors. The study of social behavior in the laboratory can be challenging because many facets of social behavior are optimally expressed under specific circumstances. In addition, social behavior is particularly sensitive to environmental factors that are affected by routine animal husbandry. The goal of this article is to review for new investigators and for animal facility staff the major factors that can affect animals' social behavior in the laboratory in order to optimize conditions for the laboratory analysis of social behavior. The authors outline a basic theoretical foundation about the study of social behavior, including the concept of umwelt, an animal's subjective sensory world. They then briefly describe some of the most commonly studied social behaviors and a few examples of the basic methods to analyze these social behaviors. They discuss the potential effects of a facility's husbandry practices on social behavior and how to control these factors as well as possible, with suggestions of several new standard operating procedures toward this end. Although this paper focuses on rodents, the general principles apply to all species. The authors hope that the reader will consider all these factors when designing experiments or working in the animal facility.