Figure 6.

Extinction test. The mean percentage of final response rate during the stimulus (A, B) and mean latency of the first action to the stimulus (C, D) for the first six stimuli for the devalued lever press group (A, C) and the devalued chain pull group (B, D) are shown. Gray and black bars represent the mean percentage or latency of devalued action for the 6-OHDA-injected and sham groups, respectively. White bars represent the mean percentage or latency of nondevalued action in sham and 6-OHDA-injected rats. Note that the lever press is not sensitive to outcome devaluation for sham animal either on the rate of action or on their latency. In contrast, for 6-OHDA-injected animals, both mean percentage of lever press and latency show sensitivity to the outcome devaluation. In contrast, the chain pull (percentage or latency) is sensitive to the outcome devaluation in sham as in 6-OHDA-injected animals. Data are expressed as means ± SEM. ^*p < 0.05; ^**p < 0.01.