Figure 6.

Mean ± s.em. responding during the summation (Panel A) and retardation (Panel B) tests of Experiment 2. Panel A shows responding to the A and C (averaged) element conditioned stimuli (CSs, solid bars) and their compounds (open bars) with the suspected inhibitor, V. Lower responding to A/C in the Over condition than in the CTL condition indicates the overexpectation effect, and greater differences between A/C and VA/VC responding in the Over condition than in the CTL condition implies that V was a conditioned inhibitor in the Over condition. Although significant overexpectation was observed only in sham-lesioned rats and rats with lesions of the basolateral amygdala (BLA), significant (and equivalent) conditioned inhibition was observed in all three lesion conditions, including rats with lesions of the amygdala central nucleus (CeA). Responding to the other stimuli presented during the summation test is given in Table 3. Panel B shows acquisition of conditioned responding to the visual CS alone in the retardation test. In all three lesion conditions, acquisition of excitatory learning was significantly slowed in the rats previously trained in the Over condition compared to the acquisition of responding in the rats previously trained in the CTL condition.