Octopamine and dopamine receptor antagonists impair appetitive and aversive visual memory recall, respectively. (A, B) Effects of octopamine (OA) (A) or dopamine (DA) (B) receptor antagonists on visual memory recall were studied. Twelve groups of animals were each subjected to 8-trial appetitive (left) or 12-trial aversive (right) conditioning trials. On the next day, each group was injected with 3 μl of saline or saline containing 1 μM epinastine, 1 μM mianserin, 500 μM fluphenazine, 500 μM chlorpromazine or 500 μM spiperone at 30 min before the final test. Preference indexes for rewarded odor (in the case of appetitive conditioning) or unpunished control odor (in the case of aversive conditioning) before (white bars) and after (black bars) conditioning are shown with means + SEM. The results of statistical comparison before and after conditioning (Wilcoxon's test) and between experimental and saline-injected control groups (Mann-Whitney test) are shown as asterisks (* P < 0.05; ** P < 0.01; NS P > 0.05).