Selective excitotoxic lesions of the nucleus accumbens core and shell differentially affect aversive Pavlovian conditioning to discrete and contextual cues

The nucleus accumbens (NAcc) is implicated in reward-related processes and in reinforcement learning. However, its precise role in associative process es is unclear and may not be related solely to appetitive learning. In the present study, the differential effects of selective excitotoxic lesions of the NAcc core and shell were studied on the acquisition of an aversive Pav lovian conditioning task that assessed conditioning to both discrete and co ntextual cues. Rats with selective lesions of the NAcc shell were not impai red on measures of aversive Pavlovian conditioning to either discrete or co ntextual cues. In contrast, animals with lesions of the NAcc core showed an impairment; in conditioning to discrete cues and an enhancement in conditi oning to contextual cues. The NAcc is thus implicated in aspects of aversiv e Pavlovian conditioning; the significance of this finding for theories of cortico-striatal function is discussed.