Observational methods used to assess rat behavior: general principles

INTRODUCTIONThe behavioral approach to solving neuroscience questions, unlike cellular and molecular approaches, is difficult to define and is therefore sometimes considered a less-disciplined approach. Methods describing behavioral procedures are often thought to be crude when compared to the precision of physiological or molecular methods. This apparent lack of precision results from the problems inherent in the study of behavior--deciding what to measure among the large number of variables, understanding that behavior is the final output of a vast array of neurochemical and electrophysiological changes, designing reproducible experiments that have appropriate controls, and most importantly, interpreting results. Conflicting results from similar protocols have led to prolonged debates and controversies in interpretation of behavioral data; therefore, it is necessary to strive for a high degree of precision through the cultivation of excellent handling and observational skills and thorough documentation strategies. This article is an introduction to several methods used to measure and assess normal behavior in a rat, including suggestions about how to make objective behavioral observations. Behavioral tests can be used to establish a "behavioral baseline" for a normal animal, to assess the effects of drugs or a lesion on behavior, and to determine whether transgenic animals have a normal behavioral repertoire. It should be kept in mind that, along with the intended effect, experimental manipulations often have unintended side effects, and behavioral tests can also be used to determine some of the less obvious changes.