Effect of odor quality and intensity on conditioned odor aversion learning in the rat

Odor quality and intensity were varied to test the ability of rats to associate odor with an induced illness. Rats were allowed 10 minutes access to water on each of nine days; deodorized air was directed towards each rat's nose while drinking at familiarization and recovery sessions (days 1-5 and 7-8, respectively) and odorized air at treatment and test sessions (days 6 and 9, respectively). Each rat was injected with LiCl following its drinking period on day 6. The difference between the amount of water consumed on day 6 and day 9 gave a measure of the conditioned aversion. Only mild or no aversion occurred with odors of n-butyric acid, benzylamine, cyclohexanone, and n-butanol. Strong conditioned aversions were obtained to odors of triethylamine, 1,4-cineole, and isoamyl acetate, and the degree of aversion increased linearly with the log of odor concentration. The effect of odor quality, intensity and presentation method, and the role of the different chemoreceptor systems in the acquisition of odor aversions are discussed.