Differential effects of excitotoxic lesions of the basolateral amygdala, ventral subiculum and medial prefrontal cortex on responding with conditioned reinforcement and locomotor activity potentiated by intra-accumbens infusions ofd-amphetamine (original) (raw)

1993, Behavioural Brain Research

The experiments reported here have investigated the impact on re,,vard-rclated processes of Icsioning the basolateral amsgdala, ventral subiculum and pretimbic cortex which represent the major limhic sources of ",ffl'erents to the ventral striatum. The results showed that. while lesions of the prelimbic cortex were without effect on the approach to a CS predictive of sucrose reinforcement and the acquisition of a new response with conditioned reinforcement, lesions of the other two structures significantly impaired both responses. Howe,,er. there '.~ere important dil-I'erences between the eft'cots of basolateral amygdala and ventral subiculum lesions. Thus, lesions of the ventral subiculum completel.,, abolished the loconlotor response to inlra-accumbens infusions of D-amphetamine, in addition to blocking the potentiative eftcot ot the same treatment em responding with conditioned reinforcement, l.esions of the basolateral am vgdala, b.v contrast, reduced the control over behaviour by a conditioned reinforcer, bt, t not the potentiation of that control by intra-accumbens D-amphetamine except at the highest dose. Moreover, the locomotor response to D-amphetamine-induced increases in dopamine in the nucleus accumbens was unaffected b,, amygdala lesions over the dose range blocked b5 ventral subiculum lesions. The results suggest a rather selective effect of am,,gdala-ventral striatal interactions ~n processes subserving conditioned reinforcement and a more fundamental influence of ventral st, biculum-venlral striatal interactions in mediating the psychomotor stimulant effects ol" D-amphetamine.