Fox urine exposure induces avoidance behavior in rats and activates the amygdalar olfactory cortex.

Predator odors represent a group of biologically-relevant chemosignals called kairomones. Kairomones enable prey animals to recognize potential predatory threats in their environment and to initiate appropriate defensive responses. Although the behavioral repertoire of anti-predatory responses (e.g. avoidance, freezing, risk assessment) has been investigated extensively, our knowledge about the neural network mediating these innate fear responses is rather limited. In the present study, the GABAA agonist muscimol was bilaterally injected (2.6 nmol/0.3 μl) into the amygdalar olfactory cortex (AOC), a brain area that receives massive olfactory input from both olfactory systems and is strongly interconnected with the medial hypothalamic defense circuit. Temporary inactivation of the AOC substantially disrupted avoidance behavior of rats to fox urine that is strongly avoided under control conditions (saline injections). Taken together, these results demonstrate that the AOC is critically involved in fox urine-induced fear behavior. This suggests that the AOC is part of a brain fear circuit that mediates innate fear responses toward predatory odors.