Flavor-illness aversions: gustatory neocortex ablations disrupt taste but not taste-potentiated odor cues.

Abstract

Two experiments evaluated the contribution of the gustatory neocortex (GN) to the potentiation of odor by taste during illness-induced aversions in rats. In Experiment 1, rats lacking GN and control rats were given an odor, a taste, or an odor-taste compound cue followed by intragastric gavage of lithium chloride. Prior to conditioning, neophobia for flavored solutions was absent in rats with GN lesions. After pairing with LiCl, GN rats developed normal conditioned odor aversions (Experiment 1B), whereas conditioned taste aversions were attenuated (Experiment 1A) or totally blocked (Experiment 1B). Potentiation of odor by taste after compound conditioning was evident in both control and GN rats, although GN lesions attenuated the effect slightly in Experiment 1B. In Experiment 2, normal rats were given compound conditioning to induce potentiated odor aversions and then given GN lesions prior to tests with the odor and taste components. Taste aversion retention was disrupted totally by GN ablation; potentiated odor aversions were retained by both groups, although the GN group extinguished faster. Gustatory neocortex ablations produced differential effects on odor and taste, disrupting taste memorial and associative processes but leaving odor conditioning and the potentiation of odor by taste processes relatively unaffected. Integrity of the GN apparently is not necessary for the acquisition or retention of potentiation odor aversions.