Taste-mediated potentiation of odor aversion induced by lithium choloride: Effects of preconditioning exposure to the conditioned stimulus and postoconditioning extinction of the taste aversion

Abstract

An odor paired with LiCl becomes more aversive when it is accompanied by taste on the conditioning trial than when it occurs by itself; this is taste-mediated potentiation of the odor aversion. The effect of preconditioning exposure to the conditioned stimulus and postconditioning extinction of the taste aversion on taste-mediated potentiation of odor aversion were examined. Rats were either preexposed to water or to the conditioned stimulus twice prior to receiving a single conditioning trial during which they were poisoned with LiCl (low dose in Experiment 1 and high dose in Experiment 2) after consuming almond-scented water, saccharin-flavored water, or almond-scented and saccharin-flavored water mixed in the same drink, in a between-groups design. Half the water-preexposed and CS-preexposed animals that drank almond-saccharin water during conditioning subsequently had their saccharin aversion extinguished. Two-bottle tests revealed that rats which had been preexposed to water and had drunk almond-saccharin water during conditioning showed a stronger almond aversion than those which had consumed almond water, indicating saccharin-mediated potentiation of almond aversion. This was true regardless of whether the saccharin aversion had been extinguished or not, although the potentiated almond aversion was found to be more resistant to extinction if the saccharin aversion was intact (Experiment 2). In both experiments, preexposure to the conditioned stimulus prevented the acquisition of either direct or saccharin-mediated almond aversions. These results are discussed in terms of the within-compound learning (Durlach & Rescorla, 1980) and sensory and-gate channelling accounts (Garcia, Forthman Quick & White, 1984).