Effects of a Synthetic Predator Odor (TMT) on Freezing, Analgesia, Stereotypy, and Spatial Memory

Exposing rats to the predator odor of trimethylthiazoline (TMT), obtained from the red fox, was compared to exposure to the novel control odor of citronella. In Experiment 1, TMT produced defensive freezing and an analgesic reaction that was reversed by an opiate antagonist. In Experiment 2, TMT augmented response stereotypy induced by an amphetamine injection. In Experiment 3, TMT interfered with working memory during 30-s, but not 0-s, delay trials of a spatial-alternation task. However, a larger amount of TMT disrupted performance during delay and no-delay trials. In Experiment 4, TMT impaired the recall of the location of a hidden platform in a Morris water maze, and a preexposure injection of a benzodiazepine agonist prevented this deficit. These findings and their implications are discussed in terms of research involving similar paradigms with other stressors.