Effects of Lesions of the Bed Nucleus of the Stria Terminalis, Laterual Hypothalamus, or Insular Cortex on Conditioned Taste Aversion and Conditioned Odor Aversion

The effects of permanent forebrain lesions on conditioned taste aversions (CTAs) and conditioned odor aversions (COAs) were examined in 3 experiments. In Experiment 1, lesions of the bed nucleus of the stria terminalis had no influence on CTA or COA acquisition. Although lesions of the lateral hypothalamus induced severe hypodipsia in Experiment 2, they did not prevent the acquisition of CTAs or COAs. Finally, in Experiment 3, lesions of the insular cortex retarded CTA acquisition but had no influence on COA acquisition. The implications of these findings are discussed with regard to the forebrain influence on parabrachial nucleus function during CTA acquisition

Failure to Obtain Instrumental Successive Negative Contrast in Tasks that Support Consummatory Successive Negative Contrast

In four experiments (three in operant chambers, one in a runway) with food-deprived rats, we sought to obtain instrumental successive negative contrast (iSNC) and consummatory successive negative contrast (cSNC) following shifts in the value of liquid rewards. Despite finding robust cSNC in each of the four experiments, there was no indication of iSNC in any of the measured instrumental responses (pressing a lever, licking an empty spout, or time to traverse a runway). Consistent with the literature, these results might be taken to suggest that iSNC cannot be obtained following a downshift in liquid reward value. However, behaviors observed in the downshifted rats suggests that the absence of iSNC might be due to the occurrence of competing responses or nonoptimal test conditions. Thus, the failure to observe iSNC in rats that show cSNC is interpreted as a failure of performance