AMYGDALA CENTRAL NUCLEUS LESIONS DISRUPT INCREMENTS, BUT NOT DECREMENTS, IN CONDITIONED-STIMULUS PROCESSING

The effects of neurotoxic lesions of the amygdala central nucleus (CN) on changes in the associability of a conditioned stimulus (CS) in app etitive Pavlovian conditioning were examined in 2 experiments with rat s. In Experiment 1, CN lesions had no effect on the reduction in the a ssociability of a CS produced by preexposure to that cue (latent inhib ition). In Experiment 2, CN lesions prevented the enhancement of the a ssociability of a CS that is normally observed when an inconsistent pr edictive relation is arranged between that CS and another cue. The res ults support previous claims that the amygdala CN is involved in broad -based incremental, but not decremental, changes in the processing of CSs in Pavlovian conditioning.