a, D1 and D2 inhibitors were intracranially infused into five rats implanted with cannulae targeting the ventral striatum, and imaged during rewarding LH stimulation. Maps show per cent signal change (%SC) before (top) and after (middle) administration of a cocktail containing SCH 23390 and eticlopride, both for voxels with significant activation in the pre-blocker condition (P ≤ 10−5). The corresponding difference map is presented in Fig. 4e. Labels in the top panel denote coordinates with respect to bregma. Filled arrowheads denote areas of highly reduced activation in the ICx (−1.5 mm) and MCx (+1.5 and +2.5 mm) observed upon local blockade of the D1 and D2 receptors. Reduced activation in the Tu and ventral pallidum (open arrowheads) probably reflects direct effects of the locally infused dopamine blockers. b, A combination of dopamine inhibitors and a noradrenaline inhibitor was intracranially infused into four rats implanted with cannulae targeting the ventral striatum (vStr), and imaged during rewarding stimulation of LH. Maps show per cent signal change (%SC) before (top) and after (middle) infusion of a cocktail containing SCH 23390, eticlopride and the α2 receptor antagonist yohimbine, both for voxels with significant activation in the pre-blocker condition (P ≤ 10−5). The bottom row shows the corresponding difference signal map. Filled arrowheads at bregma −1.5 and +1.5 denote areas at the intersection of ICx and S2, and also in MCx, in which the reduction of the BOLD signal parallels effects observed with blockade of the D1 and D2 receptors alone (a, Fig. 4e). Open arrowhead at bregma −1.5 mm indicates an amygdalar region that may be sensitive to the addition of yohimbine in the treatment mixture.