Prefrontal cortex and the relative associability of taste and place cues in rats

The effects of cutting the corticocortical connections between medial and sulcal prefrontal areas on the conditioning of taste and place cues were examined. In Experiment 1, rats were simultaneously exposed to taste and place cues before injection of 0.15 M LiCl. In controls, a significant conditioned taste aversion (CTA) but no conditioned place aversion (CPA) was observed. In contrast, rats with bilateral knife cuts showed a significant CPA but a weaker CTA. To test whether these results could have been due to the effects of simultaneously exposing the rats to taste and place cues during conditioning, rats were trained independently in either CTA or CPA paradigms in Experiment 2. In the CTA test, rats both in operated and control groups showed a CTA when first tested. Rats with bilateral knife cuts, however, showed a weaker CTA than those in the control group. In the CPA test, rats in the control group did not exhibit a CPA, whereas the knife cut group did. Rats with sham lesions tested in Experiment 2 did not differ from control subjects on either the CPA or the CTA test. Thus, bilateral cuts increased the CPA and decreased the CTA even when tested independently. These results indicate that the relative ease of association of place and taste stimuli may be accounted for in part by the organization of the intrinsic connections of the prefrontal cortex in the rat.