Individual differences in behavioral responses to novelty in rats. Possible relationship with the sensation-seeking trait in man

Abstract

Sensation-seeking is a human personality trait characterized by the need for varied, novel and complex sensations, and a general liking for risk-taking activities. Analogies can be drawn with some behavioral tendencies shown in animals. In studies on rats, certain individuals labeled as high-responders (HR), opposed to low-responders (LR), have been shown to be highly reactive in a novel environment and also predisposed to drug taking. Given that the response to novelty is the basis of the definition of sensation-seeking, the present study was designed to obtain more detailed information on the exploratory tendencies of HR rats in behavioral tasks involving a free-choice response to various novel environments differing in levels of complexity and aversiveness. The animals' preferences for novelty and familiarity were tested in a Y-maze, and for a variety of novel places in a 16-arm radial maze. The animals' exploratory tendencies in a well illuminated area were evaluated in a dark-light emergence test. The HR rats visited one (Y-maze) or many (16-arm radial maze) novel places more frequently than the LR animals did. The visits in the 16-arm radial maze by HR rats were also of shorter duration, indicating a more rapid habituation to novelty. Finally, HR rats entered more often and more rapidly an area considered as stressful. In conclusion, HR rats appear to seek novelty, variety and emotional stimulation. These characteristics may be analogous to some of the factors found in human high-sensation seekers.