Defensive responses to predator threat in the rat and mouse.

Defensive responses include an array of specific behaviors, including flight, freezing, risk assessment, and defensive threat/attack, that are elicited by unconditioned threat stimuli such as predators or predator odors. Some individual defensive behaviors are selectively responsive to drugs effective against generalized anxiety disorder or panic, providing a rationale for their use in investigation of compounds that may be useful in treating these disorders. In addition, defensive behaviors toward predators and some predator odors show rapid conditioning to contextual stimuli, whereas other predator odors do not, although they too elicit defensiveness. This pattern suggests that the ability of a predator odor to predict danger may be a determinant of the degree to which that odor supports aversive conditioning. Predators and predator odors are also increasingly used in studies of brain systems potentially related to emotionality. These factors indicate the need for selective, reliable, and convenient tests of defensiveness to predators and predator odors using rat and mouse subjects.