Basolateral amygdala NMDA receptors are selectively involved in the acquisition of taste-potentiated odor aversion in the rat

In the taste-potentiated odor aversion (TPOA) paradigm, animals acquire a strong aversion to an odor that is followed by delayed intoxication only if a gustatory stimulus is presented with the odor during conditioning. Although previous work has shown that N-methyl-D-aspartate (NMDA) receptors in the basolateral nucleus of the amygdala (BLA) play a role in the acquisition of TPOA, the present study aimed at describing the process in which NMDA receptors in the BLA are involved during acquisition of TPOA. Male Long-Evans rats received intra-BLA infusions of the competitive NMDA receptor antagonist D,L-2-2-amino-5-phosphonovalerate (D-APV; 0.05 and 0.50 mu g) immediately before or after the odor-taste conditioned stimulus (CS) presentation, or immediately before the test. Results showed that D-APV impaired acquisition of TPOA when infused before, bur not after, the CS presentation, but did not affect retrieval. These results suggest that NMDA receptors of the BLA are involved in the formation of potentiation-by taste-of the olfactory memory trace, but not in the maintenance of this process.