Effects of excitotoxic lesions of the central amygdaloid nucleus on the potentiation of reward-related stimuli by intra-accumbens amphetamine.

The present study examined the effects of lesions of the central nucleus of the amygdala (CeA) on the acquisition of a new response with conditioned reinforcement (CR) and its potentiation by intra-accumbens infusions of d-amphetamine (1, 3, 10, and 20 microg/microl). Rats were trained to associate a light-plus-noise compound stimulus with the availability of a sucrose solution before receiving both bilateral ibotenic acid lesions of the CeA and cannulas implanted above the nucleus accumbens. Lesions of the central nucleus did not impair the performance of positively reinforced discriminated approach, nor did they impair the acquisition of a new response with conditioned reinforcement. However, the potentiation of responding with CR following intra-accumbens amphetamine was blocked in lesioned animals. These results are discussed in terms of the possible interactions between associative mechanisms in the amygdala and the mesolimbic dopamine projection.